03 FIRE BOOST Aftertreatment UsersGuide

Users Guide

FIRE BOOST Aftertreatment v2014

Contents 1. Introduction........................................................................................................ 4 1.1. Scope................................................................................................................................4 1.2. Symbols............................................................................................................................ 4 1.3. Configurations...................................................................................................................4

2. Overview............................................................................................................. 5 3. Theory................................................................................................................. 6 3.1. Catalytic Converter Model................................................................................................ 6 3.1.1. Principle of Heterogeneous Catalytic Reactions................................................ 6 3.1.2. General Approaches and Assumptions.............................................................. 7 3.1.3. FIRE Balance Equations.................................................................................. 10 3.1.4. BOOST Balance Equations, Single Channel Model......................................... 13 3.1.5. Washcoat Layer Pore Diffusion........................................................................20 3.1.6. General Chemical Reaction Rate Calculation.................................................. 26 3.1.7. Transfer Coefficients.........................................................................................28 3.1.8. Spray - Reactive Porosity Interaction............................................................... 31 3.1.9. Nomenclature....................................................................................................33 3.2. Particulate Filter Model.................................................................................................. 39 3.2.1. Introduction....................................................................................................... 39 3.2.2. Overall Modeling Concept................................................................................ 40 3.2.3. Filter Flow Model.............................................................................................. 48 3.2.4. Deposition and Regeneration of Soot and Ash................................................ 52 3.2.5. Soot Migration...................................................................................................56 3.2.6. Modeling a Partial Wall Flow Filter...................................................................57 3.2.7. Modeling Glueing Zones in SIC PFs................................................................ 57 3.2.8. Particulate Filter Model Integration in FIRE and BOOST................................. 58 3.2.9. Nomenclature....................................................................................................60 3.3. Pipe Model..................................................................................................................... 64 3.3.1. Gas Phase Balance Equation.......................................................................... 64 3.3.2. Multi-Layered Wall Model................................................................................. 65 3.3.3. Nomenclature....................................................................................................68 3.4. Injector Model................................................................................................................. 70 3.4.1. Injector Model................................................................................................... 70 3.4.2. Injection Process.............................................................................................. 70 3.4.3. Wallfilm Modeling..............................................................................................71 3.4.4. Nomenclature....................................................................................................72 3.5. Temperature Sensor Model............................................................................................73 3.5.1. Nomenclature....................................................................................................74 3.6. Liquid Species Transport................................................................................................75 3.7. Thermal Coupling of Exhaust Aftertreatment Components............................................ 75 3.8. Kinetic Models................................................................................................................ 77 3.8.1. DOC Catalyst Reactions...................................................................................77 3.8.2. TWC Catalyst Reactions.................................................................................. 78 3.8.3. HSO-SCR Catalyst Reactions, Steady-State Approach................................... 81 3.8.4. HSO-SCR Catalyst Reactions, Transient Approach.........................................83 3.8.5. Lean NOx Trap.................................................................................................84 3.8.6. NOx Trap Catalyst Reactions...........................................................................89 3.8.7. Filter Regeneration with Oxygen ..................................................................... 90 3.8.8. Filter Regeneration with Oxygen and Nitric Dioxide......................................... 91 3.8.9. Filter Regeneration with Oxygen, Nitric Dioxide and NO-Oxidation..................91 3.8.10. Filter CSF Catalytic Reactions....................................................................... 92 3.8.11. Nomenclature..................................................................................................93 3.9. Literature.........................................................................................................................95 3.10. Appendix....................................................................................................................... 98 3.10.1. Analysis Formulae.......................................................................................... 98 3.10.2. Conversion of Mole and Volume Fractions and ppm's to Mass Fractions and Vice Versa...................................................................................................... 99

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FIRE BOOST Aftertreatment

4. FIRE Aftertreatment....................................................................................... 100 4.1. Input Data..................................................................................................................... 100 4.1.1. Run Mode....................................................................................................... 100 4.1.2. Module Activation........................................................................................... 100 4.1.3. Aftertreatment................................................................................................. 100 4.1.4. Catalyst Specification..................................................................................... 100 4.1.5. Particulate Filter Specification........................................................................ 144 4.1.6. Reactive Porosity Specification...................................................................... 165 4.1.7. 3D Output Specification..................................................................................174 4.1.8. Mesh Requirements and MPI Decomposition................................................ 175 4.1.9. Aftertreatment-Device Import from BOOST....................................................178 4.1.10. FIRE Aftertreatment User Functions ........................................................... 178 4.1.11. Homogenous Gas Phase Reactions - Input data......................................... 179

5. BOOST Aftertreatment ................................................................................. 180 5.1. Input Data..................................................................................................................... 181 5.1.1. Aftertreatment Solver ..................................................................................... 181 5.1.2. Boundary Conditions...................................................................................... 185 5.1.3. Catalyst .......................................................................................................... 187 5.1.4. Particulate Filter .............................................................................................224 5.1.5. Aftertreatment Pipe ........................................................................................ 240 5.1.6. Aftertreatment Injector.................................................................................... 243 5.1.7. Control Elements ........................................................................................... 246 5.1.8. Solid Materials ............................................................................................... 249 5.1.9. Liquid Materials...............................................................................................249 5.1.10. Homogenous Gas Phase Reactions - Input data......................................... 250 5.1.11. Input Data Checklist: Catalytic Converter and Particulate Filter................... 250 5.1.12. Best Practice ................................................................................................252 5.2. Databus Channels........................................................................................................ 258 5.2.1. Aftertreatment Boundary Databus Channels.................................................. 258 5.2.2. Catalyst Databus Channels............................................................................ 259 5.2.3. Particulate Filter Databus Channels............................................................... 263 5.2.4. Aftertreatment Pipe Databus Channels.......................................................... 265 5.2.5. Aftertreatment Injector Databus Channels......................................................266 5.2.6. Solver Databus Channels...............................................................................267 5.3. Simulation Results........................................................................................................267 5.3.1. Catalyst Results..............................................................................................267 5.3.2. Particulate Filter Results.................................................................................274 5.3.3. Aftertreatment Pipe Results............................................................................284 5.3.4. Aftertreatment Injector Results....................................................................... 290 5.3.5. Aftertreatment Boundary Results....................................................................296 5.3.6. Temperature Sensor Results..........................................................................297 5.3.7. Solver Results.................................................................................................298 5.4. Simulation Messages................................................................................................... 301 5.4.1. Message Analysis...........................................................................................301 5.4.2. Preprocessing ................................................................................................ 302 5.4.3. Calculation ..................................................................................................... 310 5.4.4. Postprocessing ...............................................................................................314 5.4.5. Reaction Library .............................................................................................316

FIRE BOOST Aftertreatment

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1. Introduction

1. Introduction This manual describes the usage, files and the theoretical background of aftertreatment modeling and simulation using the AVL simulation codes BOOST and FIRE.

1.1. Scope This document is for users of the FIRE/BOOST Aftertreatment Module and anyone interested in catalyst theory and modeling.

1.2. Symbols The following symbols are used throughout this manual. Safety warnings must be strictly observed during operation and service of the system or its components. Caution: Cautions describe conditions, practices or procedures which could result in damage to, or destruction of data if not strictly observed or remedied. Note: Notes provide important supplementary information. Convention

Meaning

Italics

For emphasis, to introduce a new term.

monospace

To indicate a command, a program or a file name, messages, input/ output on a screen, file contents or object names.

MenuOpt

A MenuOpt font is used for the names of menu options, submenus and screen buttons.

1.3. Configurations Software configurations described in this manual were in effect on the publication date of this manual. It is the user's responsibility to verify the configuration of the equipment before applying procedures in this manual.

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FIRE BOOST Aftertreatment

2. Overview

2. Overview The FIRE/BOOST Aftertreatment Module enables the simulation of the chemical and physical processes occurring in various types of • honeycomb type catalytic converter • wall-flow type particle filter • pipes (for BOOST). The models account for the simulation of the fluid flow within these elements, for heterogeneous chemical reaction, for adsorption and desorption of species on the catalysts' surface and also for heterogeneous soot regeneration reactions. The solution of continuity, momentum, species and energy balances in the gas phase coupled with the solid phase energy conservation and chemical reactions models delivers detailed results resolved in time and space. Typical results are for example: • flow velocities inside the channels and overall pressure drop • species mass fractions and pollutant conversion • gas/solid temperatures and thermal behavior • reaction rates and chemical behavior • heat and mass transfer • soot decomposition and regeneration With the FIRE/BOOST aftertreatment models and their results, a broad range of aftertreatment applications can be investigated, developed and optimized: Catalytic Converter

Particle Filter

Three-way catalyst

Particle filter loading

Diesel oxidation catalyst

Bare trap regeneration

NOx storage catalyst

Fuel additive regeneration

Selective Catalytic Reduction (SCR) catalyst

Low temperature NO2 regeneration

Reformer catalyst

Catalytic supported regeneration

In order to model all the different chemical reactions given by these various types of applications, FIRE offers a general chemical reaction input language which has similar functionality to the CHEMKIN software package. Thus the user can set up his own chemical reaction models containing gas phase species and species stored on the surface. The kinetic rate equations are defined via a standard Arrhenius type rate law or via user models. The chemical equilibrium and sticking coefficient formulation is also considered. The FIRE Aftertreatment Module allows definition of different kinetic parameter sets that can be assigned to any number of different catalysts in one geometric model. Additionally, FIRE and BOOST offer pre-defined reaction sets. For the simulation of catalytic reactions Langmuir-Hinshelwood approaches were setup. The user has access to all kinetic parameters and therefore can adapt all pre-defined models to different types of catalysts. In the same way pre-defined soot regeneration models are implemented for all the regeneration types listed above. Free access to any reaction model, with an arbitrary number of reactions and species, is offered by user-routines that can be linked to BOOST and FIRE.

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3. Theory

3. Theory 3.1. Catalytic Converter Model Availability BOOST AT: Catalyst

page [187]

FIRE: Catalyst Specification

page [100]

3.1.1. Principle of Heterogeneous Catalytic Reactions In this section effects are discussed that should be considered when a mathematical formulation for the description of surface kinetics is developed. Catalytic combustion reactors are heterogeneous reactors because they contain a gas phase (reactants and products) and solid catalyst. Since the catalytic reactions occur on the catalyst, the reactants have to be transported to the external gas-solid interface. Modeling the overall combustion process therefore requires the consideration of both the physical transport and chemical kinetic steps. • Generally there is a boundary layer between the bulk fluid stream and the solid surface. Within this boundary layer there are variations in velocity, concentration and temperature. Species transport from the bulk fluid stream to the solid surface can have limiting effect on the rate of the catalytic reaction. • Most catalysts are porous materials. Much of the chemical reactions occur inside the porous catalyst, which in some cases can have significant effect on the complexity of the problem. Figure 1. Steps of a Catalytic Reaction

page [95]

The above figure (adapted from Hayes et al. [21 ]) shows the individual steps taking place page [95] during a heterogeneous catalytic reaction. As discussed by Froment and Bischoff [14 ] the following steps can be distinguished: 1. Transport of the reactants from the bulk gas phase to the external solid surface across the boundary layer. 2. Diffusion of the reactants into the porous catalyst. Since the main part of the catalyst is located inside the porous material (washcoat) the reactants must diffuse into it. 3. Adsorption of the reactants onto the surface. 4. Catalytic reaction at the surface. 5. Desorption of the products of the reaction. 6. Diffusion of the products to the surface of the catalyst. 6

FIRE BOOST Aftertreatment

3. Theory 7. Transport of the products into the bulk gas phase. Steps 1, 2, 6 and 7 are mass transport steps while steps 3, 4 and 5 are chemical kinetic steps. To account for these effects properly, the FIRE/BOOST Aftertreatment Module distinguishes the following types of species: • Gas phase species: • : Concentration in the bulk gas flow (Species transport equation) • : Concentration directly above the surface of the catalyst • Stored (adsorbed) species: A stored species occupies one 'site' of the catalytic surface. The number of sites is conserved. This allows to model steps 4, 5 and 6 either separately (i.e. Oxygen storage on the surface) or in one step (i.e. Langmuir-Hinshelwood-Hougen-Watson reaction model for 3 way catalysts). FIRE Example: Three-way catalyst:

CO + 0.5*O2 = CO2 C3H6 + 4.5*O2 = 3*CO2 + 3*H2O H2 + 0.5*O2 = H2O

This mechanism accounts for the catalytic oxidation of CO, C3H6 and H2 as proposed by page [97] page [95] numerous authors in literature (i.e. Voltz et al. [65 ], Chen et al. [11 ] and Wanker page [97] et al.[67 ]). The reactions are global reactions and do not contain any stored species. Therefore the influence of adsorption and desorption of species on the surface has to be considered in the formulation of the reaction rates (kinetics). Most commonly the LangmuirHinshelwood-Hougen-Watson type rate equations are used in literature for these reactions. FIRE Example: Oxygen storage:

O2 + 2*PT_s = 2*O_s

The above reaction accounts for the effect of Oxygen storage on the catalyst. The Oxygen molecule dissociates to two Oxygen atoms that are stored on the surface, which is indicated by the identifier "_s" added to "O". Since two surface sites are occupied by the two Oxygen atoms, the expression "2*PT_s" must appear on the left hand side of the reaction definition line. PT is a dummy identifier for one surface site.

3.1.2. General Approaches and Assumptions In the following section general approaches considering catalytic converter modeling are briefly summarized. For more detailed information please refer to the literature cited. 3.1.2.1. Cell Specification of Honeycomb-Type Catalytic Converter The Honeycomb-type catalytic converter consists of hundreds (thousands) of individual channels. The exhaust gas flows through these channels and reacts catalytically. The catalytic reactions take place at active sites that are spread within the so-called washcoat of the monolith. This washcoat is a porous solid layer that covers the solid substrate as shown in the following figure.

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3. Theory Figure 2. Structure of a Squared Cell Monolith

As shown, the total thickness of the monolith's wall

results to (1)

where wall is the thickness of the substrate wall and wcl,tot is the thickness of the washcoat layers. The repeat distance s of the monolith can be derived from the cell density CPSM according to: (2)

where CPSM is defined as the number of channels per square meter cross sectional area. Catalysts are often specified with the CPSI number determining the number of channels per square inch. With given CPSI number one obtains CPSM with equation (3)

Based on this information (CPSI, wall and washcoat thickness) FIRE/BOOST calculates the hydraulic channel diameter dhyd, open frontal area OFA and the geometric surface area GSA as shown below. Hydraulic channel diameter: (4) Monolith's open frontal area (= fluid volume fraction

g)

results from: (5)

Geometric surface area (= channel wetted perimeter) GSA given in surface per monolith volume is calculated as: (6)

In the same way as the dhyd, OFA and GSA are derived from the cell density CPSM and the total wall thickness , the latter can be calculated from the first three data. Therefore the above given equations have to be inverted. The cell density is given by (7)

and the total wall thickness of the monolith is (8)

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FIRE BOOST Aftertreatment

3. Theory

The washcoat layer thickness ( wcl,tot) of the monolith is assumed to be zero and therefore the page [8] page [8] total thickness is equal to the substrate thickness wall. Eq.7 and Eq.8 show that three different equations can be used for the evaluation of the cell density and the wall thickness. The difference between them is that only a pair of two values out of the three data (dhyd, OFA page [8] and GSA) is required. FIRE/BOOST uses the first term on the right hand side of Eq.7 and page [8] Eq.8 where the hydraulic diameter dhyd and the open frontal area OFA are needed. The above calculated values of CPSM and wall are exact for squared cells. If other geometries (round, sinusoidal channel) are given, the derived values of CPSM and wall have to be understood as approximate values. Deviations do not matter since the calculation kernel of FIRE/ BOOST use the values of dhyd, OFA and GSA in any case. 3.1.2.2. Conservation Equations of Mass or Moles In general the balance of mass or moles is equivalent and therefore leads to the exact same results. Due to chemical reactions the number of moles in the system changes, but their overall mass remains constant. Therefore mass balances are often preferred. In a mole balance equation, the change of the total number of moles has to be taken into account by an additional correction term. A second reason to use mass balances is the fact that many physical properties such as enthalpies or caloric values of combustibles are given as a function of their mass. The molar mass which is necessary to transform mass specific values to mole specific data is not always completely accessible. 3.1.2.3. Volume Fraction, Density and Mass Fraction Catalytic converter models have to describe a system consisting of two different phases (gas and solid substrate) with two different volumes. The volume of the gas phase in this system is given by means of an overall volume fraction. This volume fraction of gas phase in the entire system is defined as follows: (9)

where g is the volume fraction of the phase g(as) in the entire volume V. The volume of the solid phase Vs is evaluated by Vs=(1- g)V = sV. Note, the fluid volume fraction g is identical to the open frontal area OFA. If one phase comprises several different species, a cumulative density consisting of the densities of all species can be defined. For this purpose the next relation is used: (10)

The density of the entire phase g is the sum of the densities of all different species k in it. In an additional step the mass fraction wk,g of one species in a system can be defined as the fraction of the density of the species k,g and the total density g (11)

The relation given by these two equations defines that the sum of all mass fractions always has to be equal to one.

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3. Theory 3.1.2.4. Equation of State and Ideal Gas Law If conservation equations for a gaseous phase are given, a general relation between the intensive variables of the gas is necessary. Pressures and temperatures observed during typical catalytic converter applications lie within moderate ranges (p1 NOx storage and for EOR900K) whereas the third and the fourth reaction occur at temperatures around 600 K. The set of all four reactions offers the possibility to investigate soot regeneration within a wide range of temperatures. page [90] The reaction mechanism defined in Section Filter Regeneration with Oxygen is applied in this pre-defined reaction set in the same way. The kinetic approach of the third and fourth reaction is given by: (308)

This set of four reactions can be defined in two different soot layer zones with different reaction parameters. With the specification of a sub-layer height, catalytically supported reactions near the filter wall can be modeled.

3.8.9. Filter Regeneration with Oxygen, Nitric Dioxide and NO-Oxidation Availability BOOST FIRE AVL User Coding Interface Overview The soot regeneration with oxygen and nitric dioxide and NO oxidation, implemented in BOOST, considers the following four reactions:

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91

3. Theory Kinetic Model R1 R2 R3 R4 R5

In addition to the four reactions summarized in Section Filter Regeneration with Oxygen and page [91] Nitric Dioxide , the reversible oxidation of nitric monoxide to nitric dioxide is considered. The rates of the first three reactions are described in Section Filter Regeneration with Oxygen page [91] and Nitric Dioxide and the rate of the fourth reaction is given in Section DOC Catalyst page [77] Reactions .

3.8.10. Filter CSF Catalytic Reactions Availability BOOST FIRE AVL User Coding Interface Overview The predefined CSF Catalytic Reaction model considers the following four reactions: Kinetic Model R1 R2 R3 R4 These (oxidation) reactions are assumed to take place in the catalyzed wall of a PF independently of the presence of soot. The corresponding reaction rates are defined as follows: (309)

(310)

(311)

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FIRE BOOST Aftertreatment

3. Theory where (312)

(313)

(314)

where (315)

(316)

3.8.11. Nomenclature Units 2

3

2

3

2

3

2

3

2

3

ageo,F

Geometrical surface area on the ash core front (LNT model)

(m /m )

ap,max

Maximum specific particle surface area (LNT model)

(m /m )

ap,min

Minimum specific particle surface area (LNT model)

(m /m )

areac

Reactive surface area of the catalyst

(m /m )

atrans

Geometrical surface area (GSA) of the catalyst

(m /m )

ck

B

Concentrations of species k in the bulk gas

(kmol/m )

ck

L

Concentrations of species k in the reactive surface layer

(kmol/m )

cBa,p

Molar Density of the barium cluster particle

(kmol/m )

D

Term in reaction rate equation

(variable)

DBa,p

Pore diffusion coefficient (LNT model)

(m /s)

fCO

Temperature dependence factor of filter regeneration with oxygen

(-)

k

Arrhenius frequency factor

(variable)

K

Term in reaction rate equation

(variable)

Keq

Equilibrium constant

(variable)

Nk

Mole number of species k

(kmol/m )

p

Pressure

(Pa)

r

Radial coordinate

(m)

Reaction rate of reaction i

(kmol/(m ·s))

Universal gas constant

(kJ/(kmol·K))

R

FIRE BOOST Aftertreatment

3 3 3

2

3

3

93

3. Theory RBa,p

Radius of the barium cluster particle (LNT model)

(m)

TA

Arrhenius activation temperature

(K)

T

Temperature

(K)

VBa,p

Storage volume for the barium cluster particle (LNT model) (m )

3

yk

B

Mole fraction of species k in the bulk gas

yk

L

Mole fraction of species k in the reactive surface of the gas (kmol/kmol) phase

yk

front

Mole fraction of species k on the ash core front (LNT model)

(kmol/kmol)

Surface site coverage fraction of species k

(-)

Coverage fraction of species k on the current ash core front position (LNT model)

(-)

Zk Zk

front

(kmol/kmol)

Greek Letters Ratio of maximum and minimum specific particle surface area (LNT model)

(-)

Surface coverage dependency factor

(-)

Volume fraction of the barium cluster particle in the catalyst (LNT model)

(m /m )

Shift factor from fast to slow SCR reaction (R2, R3, R4 in SCR steady kinetics)

(-)

Excess oxygen ratio

(-)

Stoichiometric coefficient

(-)

F

Dimensionless radius of current ash core front position (LNT model)

(-)

st

Dimensionless ash core front position of previous storage (-) process (LNT model)

Ba,p

Ba,p

3

2

Site density

(kmol/m )

Indices

94

3

atm

Atmospheric

Ba,p

Barium cluster particle (LNT model)

eng

Engine

EOR

Excess Oxygen Ratio

equ

Equilibrium

i

Reaction index

FIRE BOOST Aftertreatment

3. Theory k

Species index

solid

Solid

3.9. Literature 1. Ahn T., Pinczewski V. and Trimm D.L., 'Transient Performance of Catalytic Combustors for Gas Turbine Applications.' Chemical Engineering Science 41, 1986, 55-64. 2. Baehr H. D., Stephan K., 'Waerme- und Stoffuebertragung', Springer, Berlin Heidelberg, New York, 1994. 3. Bardon S., Bouteiller B., Bonnail N., Girot P., Gleize V., Oxarango L., Higelin P., Michelin J., Schuerholz S. and Terres F. "Asymmetric Channels to Increase DPF Lifetime", SAE 2004-01-0950, 2004. 4. Barin I. 'Thermochemical Data of Pure Substances'. 3rd Edition, John Wiley & Sons Inc, New York, London, Sidney, 1985. 5. Becker C., Reinsch B., Strobel M., Frisse H. P. and Fritsch A. 'Particulate Filter Made of Cordierite - Design and Regeneration Management', MTZ 2008-06, Vol. 69, pp. 20-26, 2008. th 6. Bird R. B., Stewart W. E. Lightfoot E. N. 'Transport Phenomena', 6 Edition, John Wiley&Sons Inc., New York, London, Sydney, 1965. 7. Birkhold F., Meingast U., Wassermann P., Deutschmann, O. 'Analysis of the Injection of Urea-water-solution for automotive SCR DeNOx-Systems: Modeling of Two-phase Flow and Spray/Wall-Interaction'. SAE 2006-01-0643, 2006. 8. Birkhold F., Meingast U., Wassermann P., Deutschmann, O. 'Modeling and simulation of the injection of urea-water-solution for automotive SCR DeNOx-systems'. Appl. Catal. B: Environ. 70, pp. 119-127, 2007. 9. Bissett E. J. 'Mathematical model of the thermal regeneration of a wall-flow monolith diesel particulate filter'. Chem. Eng. Sci. , 39:1233-1244, 1984. 10. Brinkmeier C. 'Automotive Three-Way Exhaust Aftertreatment under Transient Conditions Measurements, Modeling and Simulation', 2006, PhD-Thesis, University of Stuttgart. 11. Chen D.K.S. and Cole C.E. 'Numerical Simulation and Experimental Verification of Conversion and Thermal Responses for a Pt/Rh Metal Monolithic Converter'. SAE 890798, 1989. 12. Coltrin M.E., Kee R.J., Rupley F.M. and Meeks E. 'Surface Chemkin III: A Fortran Package for Analyzing Heterogeneous Chemical Kinetics at a Solid Surface - Gas Phase Interface'. Sandia National Laboratories Report, SAND96-8217 Unlimited Release, 1996. 13. DieselNet Technology Guide 'Ceramic Monolith Substrates', May 2001, URL http:// www.dieselnet.com. 14. Froment G. F. and Bischoff K. B. 'Chemical Reactor Analysis and Design', John Wiley&Sons Inc., New York, London, Sydney, 1990. 15. Fuller E.N., Schettler P.D. and Giddings J.C. 'A new method for the prediction of gas phase diffusion coefficients'. Ind. Eng. Chem. 58:19-27, 1966. 16. Gaiser G. and Mucha P. 'Prediction of Pressure Drop in Diesel Particulate Filters Considering Ash Deposit and Partial Regeneration', SAE 2004-01-0158, 2004. 17. Gordon, S. and McBride, B.J. 'Computer Program for Calculation of Complex Chemical Equilibrium Compositions, Rocket Performance, Incident and Reflected Shocks and Chapman-Jouguet Detonations'. NASA SP-273, 1971. 18. Guo Z. and Zhang Z. 'Multi-Dimensional Modeling and Simulation of Wall-Flow Diesel Particulate Filter During Loading and Regeneration', SAE 2006-01-0265, 2006. 19. Haralampous O. A., Dardiotis C. K., Koltsakis G. C. and Samaras Z. C. 'Study of Catalytic Regeneration Mechanisms in Diesel Particulate Filters Using Coupled Reaction Diffusion Modeling', SAE 2004-01-1941, 2004. 20. Hauff C. H. 'Implementierung des Modells eines NOx-Speicherkatalysators in das Simulationstool BOOST', Master thesis at ICVT, Stuttgart University, 2007. 21. Hayes, R.E. and Kolackowski, S. 'Introduction to Catalytic Combustion'. Gordon and Breach Science Publishers, Amsterdam, 1997. 22. Herzog P.L., Strigl T., Diewald R., and Wanker R. 'Particlulate filter - a key technology for HSDI diesels: From simulation to series application'. JSAE 20025356, 2002. 23. Hughes K. W. and Floerchinger P., 'Ultra Thinwall Light-off Performance - Varying Substrates, Catalysts, and Flow Rates; Models and Engine Testing', SAE 2002-1-352.

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3. Theory 24. Huynh J. H., Cuong T. and Johnson, Yang S.T., Song L. and Bagley and Warner J.R. 'A one-dimensional computational model for studying the filtration and regeneration characteristics of a catalyzed wall-flow diesel particulate filter', SAE 2003-01-0841, 2003. 25. Johnson T. V. 'Diesel Emission Control in Review', SAE 2000-01-0184, 2000. 26. Kaviani M. 'Principles of Heat Transfer in Porous Media', Mechanical Engineering Series, Springer, Berlin Heidelberg, New York, 1991. 27. Kee R.J., Dixon Lewis, G., Warnatz J., Coltrin M.E. and Miller J.A. 'A Fortran Computer Package for the Evaluation of Gas Phase Multicomponent Transport Properties'. Sandia National Laboratories Report, SAND86-8246, 1986. 28. Kee R.J., Rupley F.M. and Miller J.A. 'The Chemkin Thermodynamic Database'. Sandia National Laboratories Report, SAND87-8215, 1987. 29. Khinast J., 'Kinetik, Reaktionsmechanismus und Simulation eines trockenen Rauchgasentschwefelungsverfahren', PhD-thesis, Technical University Graz, 1995. 30. Kirchner T. and Eigenberger G., 'Optimization of the Cold-Start Behaviour of Automotive Catalysts Using an Electrically Heated Pre-Catalyst', Chemical Engineering Science 51, 1996, 2409-2418. 31. Koltsakis G. C. and Stamatelos A. M. 'Modes of Catalytic Regeneration in Diesel Particulate Filters', Ind. Eng. Chem. Res., 36(10):4155-4165, 1997. 32. Koltsakis G. C. and Stamatelos, A. M. 'Modeling dynamic phenomena in 3-way catalytic converters', Chemical Engineering Science 54, 1999, 4567-4578. 33. Koltsakis G. C., Konstantinidis, P.A. and Stamatelos A. M.. 'Development and application range of mathematical models for 3-way catalysts',Applied Catalysis B. Environmental 12, 1997, 161-191. 34. Koltsakis G.C. and Stamatelos A.M., 'Modes of catalytic regeneration in diesel particle filters'. Ind. Eng. Chem. Res. , 36:4155-4165, 1997. 35. Konstandopoulos A. G. 'Flow Resistance Descriptors for Diesel Particulate Filters: Definitions, Measurements and Testing', SAE 2003-01-0846, 2003. 36. Konstandopoulos A. G. and Kostoglou M., 'Periodically reversed flow regeneration of diesel particulate traps'. SAE 1999-01-0469 , 1999. 37. Konstandopoulos A. G., Kostoglou M. and Housiada P. 'Spatial Non-Uniformities in Diesel Particulate Trap Regeneration', SAE 2001-01-0908, 2001. 38. Konstandopoulos A. G., Kostoglou M., Skaperdas E., Papioannou E., Zarvalis D., and Kladopoulou E., 'Fundamental studies of diesel particulate filters: Transient loading, regeneration and ageing'. SAE 2000-01-1016 , 2000. 39. Konstandopoulos A. G., Kostoglou M., Vlachos N. and Kladopoulou E. 'Progress in Diesel Particulate Filter Systems', SAE 2005-01-0946, 2005. 40. Konstandopoulos A. G., Skaperdas E. and Masoudi M. 'Interial Contributions to the Pressure Drop of Diesel Particulate Filters', SAE 2001-01-0909, 2001. 41. Konstandopoulos A. G., Skaperdas E. and Masoudi M. 'Microstructural Properties of Soot Deposits in Diesel Particulate Traps', SAE 2002-01-1015, 2002. 42. Konstandopoulos A. G., Skaperdas E., Warren J., and Allansson R. 'Optimise filter design and selection criteria for continuously generating diesel particulate traps'. SAE 1999-01-0468 , 1999. 43. Konstandopoulos A. G., Vlachos N., Housiada P. and Kostoglou M. 'Simulation of Triangular-Cell-Shaped Fibrous Wall-Flow Filters', SAE 2003-01-0844, 2003. 44. Konstandopoulos A.G. and Kostoglou M., 'Reciprocating flow regeneration of soot filters. Combustion and Flame', 121:488-500, 2000. 45. Konstandopoulos A.G.and Johnson J.H., 'Wall-flow diesel particulate filter - their pressure drop and collection efficiency'. SAE 890404 , 1989. 46. Kuhnke D., Spray Wall Interaction Modelling by Dimensionless Data Analysis, PhD thesis, Technische Universitaet Darmstadt, 2004. 47. Lienhard John H. IV and Lienhard John H. V 'A Heat Transfer Text Book Phlogiston Press, Cambridge Massachusetts, 3rd edition, 2003. 48. Liu Zheji and Hoffmanner Albert L. 'Exhaust Transient Temperature Response', SAE 950617, 1995. 49. Millet C. N., Menegazzi P., Martin B., Colas H. and Bourgeois C. 'Modeling of Diesel Particulate Filter, Regeneration: Effect of Fuel-Borne Catalyst', SAE 2002-01-2786, 2002. 50. Missy S., Thams J., Bollig M., Tatschl R., Wanker R., Bachler G., Ennemoser A., and Grantner H. 'Computer-aided optimisation of the exhaust gas aftertreatment system of the new BMW 1.8-litre valvetronic engine'. MTZ Journal , 11:18-29, 2001. 96

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3. Theory 51. Mohammed H., Triana A. P., Yang S. L. and Johnson J. H. 'An Advanced 1D 2-Layer Catalyzed Diesel Particulate Filter Model to Simulate: Filtration by the Wall and Particulate Cake, Oxidation in the Wall and Particulate Cake by NO2 and O2, and Regeneration by Heat Addition', SAE 2005-01-0467, 2005. 52. Ogyu K., Ohno K., Hong S. and Komori T. 'Ash Storage Capacity Enhancment of Diesel Particulate Filter', SAE 2004-01-0949, 2004. 53. Ohno K., Shimato N., Taoka K., Hong S., Ninomiya T., Komori T. and Salvat O., 'Characterization of SiC-DPF for Passenger Car', SAE 2000-01-0185, 2000. 54. Opris C. N. 'A Computational Model Based on the Flow, Filtration, Heat Transfer and Reaction Kinetics Theory in a Porous Ceramic Diesel Particulate Trap', PhD thesis, Michigan Technological University, 1997. 55. O'Rourke, P.J. 'Statistical Properties and Numerical Implementation of a Model for Droplet Dispersion in Turbulent Gas', J. Comput. Physics 83, 1989. 56. Perry R. and Green D., 'Perry's Chemical Engineer's Handbook'. New York, McGraw Hill Book Company, 6. Edition, 1984. 57. Peters B. and Dziugys A., 'Numerical modeling of electrified particle layer formation on the surface of filtration fabric'. Environmental Engineering , 9:4:191-197, 2001. 58. Peters B. and Dziugys A., 'Numerical simulation of the motion of granular material using object-oriented techniques'. Comput. Methods Appl. Mech. Eng. , 191:1983-2001, 2002. 59. Peters B. J., Wanker R., Muenzer A. and Wurzenberger J. C. 'Integrated 1D to 3D simulation Workflow of Exhaust Aftertreament Devices', SAE 2004-01-1132, 2004. 60. Reid R.C., Prausnitz J.M. and Poling B.E. 'The properties of gases and liquids'. 4th Edition, Mc Graw Hill, New York, 1988. 61. Shah R. K. and London A. L. 'Laminar flow forced convection in ducts: a sourcebook for compact heat transfer exchange analytical data'. Academic Press, 1978. 62. Taylor R., and Krishna R. 'Multicomponent Mass Transfer', John Wiley&Sons Inc., New York, London, Sydney, 1993. 63. Tuttlies U., Schmeisser V. and Eigenberger G. 'A mechanistic simulation model for NOx storage catalyst dynamics', Chemical Engineering Science, 59, 2004, 4731-4738. 64. Verein Deutscher Ingenieure (Ed.) VDI-Waermeatlas, Berechnungsblaetter fuer den th Warmeuebergang. 7 Edition, VDI Verlag, Duesseldorf, 1994. 65. Voltz E.V., Morgan C.R. and Liederman, D. and Jacob, S.M. 'Kinetic Study of Carbon Monoxide and Propylene Oxidation on Platinum Catalysts'. Ind. Eng. Chem. Prod. Res. Develop. 12:4, 1973, 294-301. 66. Wakao W., Smith J.M, 'Diffusion in catalyst pellets', Chemical Engineering Science 17 (1962): 825-834, 1962. 67. Wanker R. and Peters B., 'DPF pressure drop vs. soot mass during regeneration and loading'. Technical report, AVL Internal Communication, 2001. 68. Wanker R., Granter H., Bachler G., Rabenstein G., Ennemoser A., Tatschl R., and Bollig M. 'New physical and chemical models for the CFD simulation of exhaust gas lines: A generic approach'. SAE 2002-01-0066 , 2002. 69. Wanker R., Granter H., Tatschl R., and Bollig M. '3D CFD simulation of exhaust lines: A new approach to account for current and future challenges'. JSAE 20025336 , 2002. 70. Wanker R., Raupenstrauch H. and Staudinger G. 'A fully distributed model for the simulation of catalytic converter' Chemical Engineering Science 55, 2000, 4709-4718. 71. Wanker R., Wurzenberger J. C. and Higbie D. '1d and 3d CFD Simulation of Exhaust-Gas Aftertreatment Devices: Parameter Optimization via Genetic Algorithm', Proceedings of 5th ASME/JSME Int. Symposium on Computational Technologies for Fluid/Thermal/Stress Systems with Industrial Applications, San Diego, 2004 72. Wendland Daniel W. 'Automobile Exhaust-System Steady-State Heat Transfer', SAE 931085, 1993. 73. Wheeler A., In P.H. Emmett (Ed.), Catalysis, Reinhold New York, Vol II: 105, 1955. 74. Wilde Karl 'Erzwungene und freie Stroemung', Dietrich Steinkopff Verlag, Darmstadt, 2nd edition, 1978. 75. Winkler C. and Floerchinger P., Patil, M.D., Gieshoff, J., Spurk, P., Pfeifer, M., 'Modeling of SCR DeNOx Catalyst - Looking at the Impact of Substrate Attributes', SAE 2003-01-0845. 76. Wurzenberger J. C. and Peters B. 'Catalytic Converter in a 1D Cycle Simulation Code Considering 3D Behavior', SAE 2003-01-1002, 2003. 77. Wurzenberger J. C. and Peters B. 'Design and Optimization of Catalytic Converters taking into Account 3D and Transient Phenomena as an Integral Part in Engine Cycle Simulations', 97 FIRE BOOST Aftertreatment

3. Theory ICES 2003-611, Proceedings of STC2003, ASME Internal Combustion Engine Division, 2003. 78. Wurzenberger J. C. and Wanker R. 'Multi-Scale SCR Modeling, 1D Kinetic Analysis and 3D System Simulation', SAE 2005-01. 79. Wurzenberger J. C., Muenzer A., Peters B. and Wanker R. '1D/3D Simulation Workflow Optimization of Exhaust Gas Aftertreatment Devices', ATZ-Worldwide, 106(7-8):27-44, 2004. 80. Silvis, W. 'An Algorithm for Calculating the Air/Fuel Ratio from Exhaust Emissions', SAE Technical Paper 970514, 1997.

3.10. Appendix 3.10.1. Analysis Formulae (317)

(318)

A is an arbitrary element, z the number of oxygen atoms in the molecule AOz. x and y are the number of carbon and hydrogen atoms in an arbitrary composition of a hydrocarbon CxHy, respectively. (319)

A is an arbitrary element, z the number of oxygen atoms in the molecule AOz. x and y are the number of carbon and hydrogen atoms in an arbitrary composition of a hydrocarbon CxHy. (320)

(321)

(322)

(323)

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3. Theory 3.10.2. Conversion of Mole and Volume Fractions and ppm's to Mass Fractions and Vice Versa The correlation between mole fractions, volume fractions and parts per million (ppm) is given by: • One mole fraction is identical to one volume fraction 6 • One mole fraction is 10 ppm The evaluation of mass fractions out of mole (or volume) fractions is given by (324)

where wk is the mass fraction, yk is the mole fraction and Mk is the molar mass of the species k. The equation shows that for the evaluation of the individual k species mass fractions, the molar masses of the K species have to be known. For a system consisting of H2 and O2 with identical mole fractions (i.e. yH2=0.5, MH2 = 2 kg/kmol and yO2= 0.5, MO2 = 32 kg/kmol) the mass fractions are given by: (325)

The evaluation of mole (or volume) fractions out of mass fractions is given by the following formula (326)

For a system consisting of H2 and O2 with identical mass fractions (i.e. wH2 = 0.5, MH2 = 2 kg/ kmol and wO2=0.5, MO2 = 32 kg/kmol) the mole fractions are given by: (327)

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4. FIRE Aftertreatment

4. FIRE Aftertreatment In this section the application FIRE Aftertreatment is presented.

4.1. Input Data This chapter explains how catalyst input data can be generated within the FIRE Workflow Manager and describes the data in the Solver Steering File for the FIRE Aftertreatment Module. Aftertreatment examples are available in the Examples Manual and in the installation package.

4.1.1. Run Mode Select Run mode in the parameter tree to access the Run mode pull-down menu and then select Timestep or Steady. Note: Steady simulations of chemical reactions require the specification of the Pseudo time step for aftertreatment at Run mode. For steady pressure drop simulations without chemical reactions, the pseudo time step is not necessary.

4.1.2. Module Activation Select Module activation in the parameter tree to access the Aftertreatment toggle switch. Turn on toggle switch to activate. Note: The Aftertreatment Module cannot be activated without the Species Transport Module (General).

4.1.3. Aftertreatment The Aftertreatment parameter tree is displayed in the Modules folder as follows: Figure 37. Aftertreatment Parameter Tree

Click on Aftertreatment TNG with the right mouse button to access the following options: • Import from BOOST • Catalyst: Insert • DPF: Insert • Reactive Porosity: Insert page [101] Refer to the corresponding sections Catalyst Specification , General Particulate Filter page [144] page [165] Specification, Reactive Porosity Specification and Aftertreatment-Device Import page [178] from BOOST for further details.

4.1.4. Catalyst Specification To add a catalyst to the project, click on Aftertreatment TNG in the parameter tree with the right mouse button and select Catalyst: Insert from the submenu. To delete a catalyst from the project, click on the name of the catalyst (i.e. Catalyst[1]) with the right mouse button and select Remove from the submenu. The specification of a catalyst comprises data over its geometry, its fluid and thermodynamic behavior and the conversion reactions taking place. 100

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4. FIRE Aftertreatment Copy from CAT allows the complete set of input data to be copied from Catalyst[X] to the present catalyst. Figure 38. Copy from CAT Function

This input data is discussed in the following sub-sections. 4.1.4.1. Catalyst Specification Select Catalyst specification in the parameter tree to access the following input fields: 4.1.4.1.1. Catalyst Specification Typical Values and Ranges Cell selection

Supply a cell selection that defines the geometry of the catalyst.

NoSelection (default)

Inlet face selection

Supply a face selection that defines the inlet plane of the catalyst.

NoSelection (default)

Outlet face selection

Supply a face selection that defines the outlet plane of the catalyst.

NoSelection (default)

Monolith initialization temperature

Determines the initial temperature of the catalyst.

293.15-1500 (K)

4.1.4.1.2. Catalyst Type: Square Cell Catalyst Typical Values and Ranges 2

Cell density (cpsi)

Determines the type of monolith: Number of 2 channels per in = N.

100-900 (1/in )

Wall thickness

Determines the thickness of the monolith's walls = Wall.

0.006-0.015 (in)

Washcoat thickness

Determines the thickness of the washcoat = WC. For activated Activate Washcoat Layer (WCL) Model a value greater than zero is required.

0-0.003 (m)

4.1.4.1.3. Catalyst Type: General Catalyst Typical Values and Ranges Open frontal area (OFA)

Determines the open frontal area (= fluid volume fraction) of monolith ( ).

0.50-0.75 (-)

Hydraulic diameter

Determines the hydraulic diameter dhyd of the monolith.

0.001-0.005 (m)

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4. FIRE Aftertreatment 4.1.4.2. Pressure Drop Specification The pressure loss of the flow within a catalytic converter is determined by a flow-resistance model and corresponding parameters, which have to be supplied by the user. All necessary input data are summarized in the following sections. 4.1.4.2.1. Pressure Drop Models Four different pressure drop models are available to calculate the pressure drop within the catalyst: 4.1.4.2.1.1. Tube Friction The Tube Friction pressure drop model is especially applicable for flow through catalysts where empirical data of the pressure drop are not available. The pressure drop is based on the flow of fluid along the channels of the catalyst and the pressure drop is calculated due to the wall friction within pipes: (328)

The notation used is as follows: Pressure gradient within porous material dh

wi

Mean hydraulic diameter = A

Non-circular cross-sectional area

Lper

Wetted perimeter

Interstitial (local) velocity components in the tubes (

)

Laminar tube friction (HAGEN-POISEUILLE) = 1.0 for cross sections with circular shapes = 0.89 for cross sections with quadratic shapes (user-supplied input) Turbulent tube friction (BLASIUS) Reynolds number

To activate the Tube friction pressure drop model, select Tube friction from the Pressure drop model pull-down menu to access the following input fields: Typical Values and Ranges Shape factor

This specifies a shape factor for the laminar tube friction. In the laminar case the tube friction is dependent on the shape of the cross-sectional area. = 1.0 for cross sections with circular shapes. = 0.89 for cross sections with quadratic shapes.

0.8-1 (-)

4.1.4.2.1.2. Forchheimer If Forchheimer is chosen as pressure drop model, then the pressure gradients within the catalyst channels are calculated with following equation 102

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4. FIRE Aftertreatment (329)

The linear and the quadratic term take into account the viscous losses and the inertial losses, respectively, of the flow inside the catalyst channels. Pressure gradient within porous material 2

i

Viscous loss coefficient (x-, y- and z-components) (1/m ) 2

Molecular (laminar) dynamic viscosity of domain fluid (Ns/m ) wi

Interstitial (local) velocity components in porous medium according to the local volume-fraction Inertial loss coefficient (1/m) Domain fluid density

To activate the Forchheimer pressure drop model, select Forchheimer from the Pressure drop model pull-down menu to access the following input fields: Typical Values and Ranges Zeta-value

This specifies the parameter ( ) defining the dependency between the velocity and the pressure loss per unit length of porous material.

0-100 (1/m)

Alpha value

This specifies the parameter ( i) defining the dependency between the velocity in the i direction, the laminar viscosity, and the pressure loss per unit length of porous material. Only if Undirected is selected for Porosity Type, direction dependent alpha values ( i) can be defined to simulate an unisotropic porous media.

0-10 (1/m )

7

2

Instead of the direct specification of the pressure drop model parameters Alpha and Zeta, a set of corresponding measured pressure drop / velocity pairs and the corresponding reference density and viscosity could be specified. During a pre-processing step FIRE then fits Alpha and Zeta from this data. Typical Values and Ranges 3

Reference Density

This specifies the density of the medium which is used in the experiment, where the pressure/velocity data specified in the table are evaluated.

0.5-50 (kg/m )

Reference Viscosity

This specifies the viscosity of the medium which is used in the experiment, where the pressure/velocity data specified in the table are evaluated.

5.10 -5.10 (Ns/ 2 m )

-7

-4

Velocity Pressure Drop Table - Forchheimer

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4. FIRE Aftertreatment Typical Values and Ranges Interstitial velocity This specifies the measured interstitial velocities w (for fitting Alpha and Zeta, at least three different velocities are necessary). Pressure Gradient dp/dx

0-50 (m/s)

This specifies the measured pressure gradients -400000-0 (N/ 3 corresponding to the different velocities (for positive m ) pressure drops over the monolith length, the pressure gradients are negative!)

4.1.4.2.1.3. Re formulation If Re formulation is chosen as pressure drop model, the pressure gradients within the catalyst channels are calculated with following equation: (330)

The notation used is as follows: Pressure gradient within porous material dh

Mean hydraulic diameter = A

Non-circular cross-sectional area

Lper

Wetted perimeter

wi

Interstitial (local) velocity components in porous medium according to the local volume-fraction

f

General Re-number dependent correlation for the friction factor Reynolds Number

(square:0.89)

Fanning friction factor

The friction factor f is described as a function of the Reynolds Number Re and changes depending on the flow regime (laminar, transition or turbulent): (331) The bounds for the transition region from laminar to turbulent are set by Reynolds numbers of Relam = 2300 and Returb = 5000. In the turbulent region, fturb is considered as a constant input value. In the laminar region flam is given by (332)

To activate the Re formulation pressure drop model, select Re formulation from the Pressure drop model pull-down menu to access the following input fields: Typical Values 104

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4. FIRE Aftertreatment Coefficient a

Input for the calculation of the general Re number dependent correlation for the friction factor.

64 (-)

Coefficient b

Input for the calculation of the general Re number dependent correlation for the friction factor.

-1 (-)

Turbulent

Turbulent Friction Factor

0.019

Channel Shape

Input for the Fanning Friction Factor

Square: 0.89

4.1.4.2.1.4. Power Law For catalysts where empirical data of the pressure drop are available, the power law option may be suitable. The empirical pressure drop is used to prescribe the user-supplied pressure drop coefficients: (333)

The notation used is as follows: Pressure gradient within porous material wi ,

Interstitial (local) velocity components through porous material Power law parameters

To activate the power law pressure drop model, select Power law from the Pressure drop model pull-down menu to access the following input fields: Typical Values and Ranges alpha-value

This specifies the parameter defining the 0.1-1000 (-) dependency between velocity and the pressure loss per unit length of porous material.

beta-value

0-2 (-) This specifies the parameter defining the dependency between the velocity and the pressure loss per unit length of porous material.

4.1.4.2.1.5. User If User is chosen as pressure drop model, the pressure drop is calculated according to the coding in the user routine usepor_pres.f. 4.1.4.2.2. Turbulence Treatment Within the single channels of a catalytic converter, the turbulence kinetic energy k is calculated by the standard transport equation. To take into account the laminarization process within the single channels the dissipation rate is calculated from the algebraic equation shown below: (334)

Crel is a relative turbulent length scale, which is multiplied with the hydraulic channel diameter dhyd and estimates the turbulence characteristics inside the monolith channels. Crel is a problem dependent quantity which has to be specified by the user.

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4. FIRE Aftertreatment Typical Values and Ranges Rel. turb. length scale Crel

Relative turbulent length scale which is multiplied with the hydraulic channel diameter to estimate the turbulence characteristics within monolith channels.

0.0001-0.02 (-)

4.1.4.3. Catalyst Physical Properties Select Catalyst Physical Properties in the parameter tree to access the following input fields: 4.1.4.3.1. Catalyst Physical Properties Typical Values and Ranges Density

Determines the bulk density of the monolith material considering the volume in the pores.

400-2000 (kg/ 3 m )

Thermal conductivity

Determines the thermal conductivity of the monolith material (= bulk solid material considering the volume in the pores). The thermal conductivity can either be specified as a constant value or as a table where the value changes as a function of temperature. Click on

0.1-50 (W/(m·K))

to define table data. Specific heat

Determines the specific heat of the monolith material 500-2000 (J/ (= bulk solid material considering the volume in the (kg·K)) pores). The specific heat can either be specified as a constant value or as a table where the value changes as a function of temperature. Click on table data.

Anisotropic cond. Factor

to define

Corrects the diffusion coefficients of the solid temperature equation normal to axial direction. A value of 1.0 simulates an isotropic conductivity. A value of 0.5 would be a good choice for monoliths. The anisotropic conduction factor is not used if the user-defined parameter ATM_ACTIV_RADIATION is specified and the current catalyst is selected as shown in the following figure. Then the effective thermal conductivity including radiation is used instead of the default anisotropic model (see section page [10] Anisotropic Heat Conduction Matrix )

0-10 (-)

Figure 39. User Defined Parameters for Effective Heat Conduction Specification

4.1.4.3.2. Mass Transfer Model FIRE allows to specify mass and heat transfer models independently. The following mass transfer models are available: 106

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4. FIRE Aftertreatment Typical Values and Ranges Type of transport coefficients

Mass Transfer Multiplier

Sieder/Tate: The Sieder/Tate correlation is used to calculate heat page [29] and mass transfer coefficients (Eq.78 ). Hawthorn: The Hawthorn correlation is used to calculate heat page [29] and mass transfer coefficients (Eq.80 ). Hausen: The Hausen correlation is used to calculate heat and page [29] mass transfer coefficients (Eq.79 ). constant: Constant values which have to be defined by the user are taken as heat and mass transfer coefficients.

Sieder/Tate (default)

Mass transfer coefficient Martin: The Martin correlation is used to calculate heat and page [29] mass transfer coefficients (Eq.81 ). user: The user can specify the transfer coefficients in use_cattra.f.

0.1-10 (m/s)

Specify a factor by which the gas diffusion coefficient of the mass transfer model is scaled. Possible input is constant (mass transfer of every species is scaled in the same way) or table (mass transfer of selected species is scaled).

0.01-10 (-)

4.1.4.3.3. Heat Transfer Model The following heat transfer models are available: Typical Values and Ranges Type of transport coefficients

Sieder/Tate: The Sieder/Tate correlation is used to calculate heat page [29] and mass transfer coefficients (Eq.78 ). Hawthorn: The Hawthorn correlation is used to calculate heat page [29] and mass transfer coefficients (Eq.80 ). Hausen: The Hausen correlation is used to calculate heat and page [29] mass transfer coefficients (Eq.79 ). constant: Constant values which have to be defined by the user are taken as heat and mass transfer coefficients.

Sieder/Tate (default)

Heat transfer coefficient Martin: The Martin correlation is used to calculate heat and page [29] mass transfer coefficients (Eq.81 ).

5-500 (W/(m ·K))

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2

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4. FIRE Aftertreatment user: The user can specify the transfer coefficients in use_cattra.f. Heat Transfer Multiplier

Specify a factor by which the heat transfer is scaled.

0.1-10 (-)

4.1.4.3.4. Catalyst Segmentation FIRE provides a simple model to take into account perforations in the catalyst. If Repeat turbulent inlet region is activated, the distance to the channel inlet in the heat and mass transfer models (Sieder/Tate, Hausen, Hawthorn and Martin) is reset at every location of a page [28] perforation (see length l in section Transfer Coefficients ). Typical Values and Ranges Repeating Length Determines the repeating length of the uniformly distributed perforations.

0.001-0.2 (m)

4.1.4.3.5. External Heat Source FIRE allows to specify constant heat sources for arbitrary cell selections. The specification is done for catalyst, reactive porosity and particulate filter separately. A warning check is performed, if a cell selection is specified more than one time. Select Activate at External heat source and click New external heat source for every heat source selection to be specified: Figure 40. Specification of External Heat Sources

Select HeatSource_X to open the window for the heat source specification. To delete a heat source select the check box at delete? and click Delete external heat source. Figure 41. Specification of External Heat Sources

Typical Values and Ranges Cell selection

Determines the cell selections for which the constant heat sources are applied. Click on table or formula data.

Heat Source 108

NoSelection

to define

Determines the quantity of heat introduced.

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8

3

0-10 (W/m )

4. FIRE Aftertreatment 4.1.4.4. Washcoat Two different approaches are available to model heterogeneous reactions. In the standard model approach, the pore diffusion through the washcoat layer(s) is neglected. In the advanced model approach, pore diffusion is taken into account. Therefore, every washcoat layer is discretized in the direction perpendicular to the catalyst solid surface. The standard approach is equivalent to the advanced approach with only one washcoat layer of one computational cell. Therefore, the former specification at Conversion Reactions is now done at the My_Reaction branch. The advanced approach, taking into account pore diffusion through the washcoat layers, requires the specification of Transport Model and Reaction Model for each washcoat layer respectively. Note: For a deactivated button Activate Washcoat Layer (WCL) Model, the set-up of the Conversion Reactions is located in the first reaction branch My_Reaction. For the activated washcoat layer model one has to specify conversion reactions as well as a transport model for every layer separately. Note: The washcoat layer (WCL) model requires a Washcoat Thickness greater than zero to be specified at Catalyst Specification. Figure 42. Washcoat - Activated Washcoat Layer (WCL) Model

If Activate Washcoat Layer (WCL) Model is selected, the following input data has to be specified: Typical Values and Ranges -6

Layer Thickness

Determines the dimensionless layer thickness for every washcoat layer. The sum over all layer thicknesses must be 1.0. The dimensioned layer thickness is determined by multiplication with the Washcoat Thickness.

10 -1 (-)

No. Grid Points

Determines the number of computational cells of each washcoat layer.

1-10 (-)

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4. FIRE Aftertreatment Ref. WCL Volume

Determines the specific reference washcoat 0.01 (-) layer thickness as described in section page [20] Pore Diffusion Model . With Calculate Spec. Washcoat Layer Volume, a reasonable default value based on the geometrical specification is calculated.

Density

Determines the bulk density of the washcoat layer materials. Together with the density specified at Catalyst Physical Properties, a solid mixture density is calculated.

400-2000 (kg/m )

Reaction Model

User-given name of the reaction model for each washcoat layer.

My_Reaction (default)

Transport Model

User-given name of the transport model for each washcoat layer.

My_Transport (default)

3

4.1.4.4.1. Reaction Model (Conversion Reactions) Several different reaction models are available. Either no reactions are taken into account, pre-defined reaction models are chosen or the application of user-defined models is possible. If Activate Washcoat Layer (WCL) Model is selected, one has to specify a reaction model for each washcoat layer separately. More detailed information about the individual reaction page [77] mechanisms is given in Section DOC Catalyst Reactions . The pre-defined reaction models use global kinetic approaches given by Langmuir Hinshelwood equations and also transient mechanisms where adsorption and desorption steps are explicitly taken into account. All reaction models are supplied with default values for the individual kinetic parameters. The user can use the kinetic model and adjust all kinetic parameters. Note that the suggested reaction parameters have been successfully applied to several validation simulations, but they may have to be adjusted for use in other types of catalysts. In this case it is recommended to apply the pre-defined reaction model and to supply it with adequate reaction parameters. The following pre-defined reaction models are available: 1. Diesel Oxidation Catalyst (DOC). This model is dedicated for DOCs comprising the three major oxidation reactions of CO, HC and NO. 2. Three Way Catalyst (TWC). This model is a dedicated TWC model comprising seven conversion reactions and surface storage reactions on cerium, rhodium and barium. By selecting specific reactions and adapting the related kinetic parameters, this model also can be applied to other catalysts such as DOCs. 3. Selective Catalytic Reduction (SCR), Steady Kinetics. This model comprises seven reaction rates which can be enabled/disabled individually for three different reaction sections in the catalyst. The SCR rates use Eley-Rideal mechanisms, thus it assumes steady-state conditions for the reaction steps of adsorption, catalytic reaction and desorption. 4. Selective Catalytic Reduction (SCR), Transient Kinetics. This model comprises nine reactions that can be enabled/disabled individually for three different reaction sections in the catalyst. The transient effect of ad-/desorption is explicitly taken into account. 5. NOx Trap Catalyst Reactions. This model comprises two conversion reactions for NO and the surface storage of NO2 on barium. 6. Lean NOx Trap. This model comprises ten conversion reactions and surface storage on cerium. Furthermore, it offers two approaches of storing nitric oxides: an ash core model approach, developed by ICVT Stuttgart, and a surface storage approach. 4.1.4.4.1.1. Diesel Oxidation Catalyst (DOC) This reaction model offers a set of three oxidation reactions. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. page [77] More detailed information about this model is given in section DOC Catalyst Reactions . 110

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment The different reactions can be en/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: CO Oxidation

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

R2: C3H6 Oxidation

R3: NO Oxidation

K1 - K5

Determines the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determines the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of propane as representative of hydro carbons. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determines the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determines the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

Approach 2

K

Determines the frequency factors used in the pre-defined reversible power-law conversion mechanism.

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111

4. FIRE Aftertreatment E

Determines the activation temperatures used in the pre-defined reversible power-law conversion mechanism.

A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

4.1.4.4.1.2. Three Way Catalyst (TWC) This reaction model offers a set of nine conversion reactions and surface storage mechanisms at three different surface sites. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. page [78] More detailed information about this model is given in Section TWC Catalyst Reactions . The different reactions can be enabled/disabled individually by clicking the corresponding check boxes. When enabled, several sub-pages for the detailed specification of the reaction parameters become enabled. R1: CO Oxidation

R2: C3H6 Oxidation

R3: CO-NO Redox Reaction

112

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of propene as representative of hydrocarbons. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide and reduction of nitric monoxide. The denominator takes into account an inhibition effect of carbon monoxide. Each reaction constant is evaluated using Arrhenius'

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment law. The reaction order of carbon monoxide is a function of the carbon monoxide concentration itself and therefore the order changes between lean and rich conditions.

R4: H2 Oxidation

R5: NO Oxidation

m

Determines the reaction order of nitric monoxide in the pre-defined reaction approach.

n

This is a tuning value in order to determine the reaction order of carbon monoxide (n) in the pre-defined reaction approach. There are two possibilities, either a constant value for n (activate Reaction Order and specify n), or the evaluation of the Shift Function (activate Shift Function and specify o).

K1 - K2

Determine the frequency factors used in the predefined conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of hydrogen. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

Approach 2

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113

4. FIRE Aftertreatment

R6: CO-H20 Shift

R7: C3H8 Oxidation

R8: C3H6-H20 Shift

114

K

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism.

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism.

A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the water gas shift reaction. Its reversible behavior is taken into account by considering the equilibrium constant as part of the rate equation. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of propane. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for water gas shift reactions. Its reversible behavior is taken into account by considering the equilibrium constant as part of the rate equation. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment of the temperature and is derived from the free Gibbs reaction enthalpy.

R9: C3H8-H20 Shift

R10-R13: Ce Storage

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the water gas shift reaction. Its reversible behavior is taken into account by considering the equilibrium constant as part of the rate equation. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Under lean conditions cerium is oxidized by O2 and under rich conditions cerium is reduced by CO, C3H6 and C3H8. All rates are of first order with respect to the participating gas and solid phase components. All reaction constants are evaluated using Arrhenius' law. R10

R11

R12

R13

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4. FIRE Aftertreatment

R14-R19: Rh Storage

Cerium Storage Capacity

Determines the maximum amount of oxygen that can be stored on the cerium surface site.

Initial Surface Coverage fraction of CeO2

Determines the coverage fraction of CeO2 at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of CeO2

Determines the maximum surface coverage fraction of CeO2 at the solid surface. This property can be specified as a constant value or as a function of temperature. Range: 0-1 (-)

K1 - K4

Determines the frequency factors used in the predefined ad-/desorption mechanisms .

E1 - E4

Determines activation temperatures used in the pre- ad-/desorption mechanisms .

Under lean conditions rhodium is oxidized by O2 or NO and under rich conditions rhodium is reduced by CO, H2, C3H6 and C3H8. All rates are of first order with respect to the participating gas and solid phase components. All reaction constants are evaluated using Arrhenius' law. R14

R15

R16

R17

R18

R19

Rhodium Storage Capacity 116

Determines the maximum amount of oxygen that can be stored on the rhodium surface site.

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment

R20-R21: Ba Storage

Initial Surface Coverage fraction of RhO

Determines the coverage fraction of at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of RhO

Determines the maximum surface coverage fraction of at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

K1 - K6

Determine the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E6

Determine the activation temperatures used in the pre-defined sorption-equilibrium and ad/desorption mechanisms.

In the presence of NO2 and O2, barium carbonate is oxidized to barium nitrate and in the presence of CO, barium nitrate is reduced to barium carbonate. All rates are of first order with respect to the participating gas and solid phase components. All reaction constants are evaluated using Arrhenius' law. R20

R21

Barium Storage Capacity

Determines the maximum amount of nitric oxide that can be stored on the barium surface site.

Initial Surface Coverage fraction of Ba(NO3)2

Determines the coverage fraction of Ba(NO3)2 at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of Ba(NO3)2

Determines the maximum surface coverage fraction of Ba(NO3)2 at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E2

Determine the activation temperatures used in the pre- ad/desorption mechanisms.

R22: HC Storage

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117

4. FIRE Aftertreatment Metal Storage Capacity

Determines the maximum amount of C3H6 that can be stored on the metallic surface site.

Initial Surface Coverage fraction of C3H6

Determines the coverage fraction of C3H6 at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of C3H6

Determines the maximum surface coverage fraction of C3H6 at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined sorption-equilibrium and ad/desorption mechanisms.

E1 - E2

Determine the activation temperatures used in the pre-defined sorption-equilibrium and ad/desorption mechanisms.

4.1.4.4.1.3. Selective Catalytic Reduction (HSO SCR), Steady Kinetics This reaction model offers a set of seven conversion reactions that are typically used in SCR converters. This pre-defined model is setup in a way that three different reaction sections can be specified where in each section the reactions can be individually switched on. The name HSO is related to a typical SCR system where three different sections for Hydrolysis, SCR and Oxidation are used in one converter. If only one section is considered, the lengths of the two others sections can be simply set to zero. The model uses steady-state approaches for all SCR reactions as given by the Eley-Rideal mechanism. For the hydrolysis and all oxidation reactions also steady-state power-law reactions are applied. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. More detailed information about this model is given in Section HSO-SCR Catalyst Reactions, page [81] Steady-State Approach . The rate is assumed to be of first order with respect to both water vapor and isocyanic acid. The reaction constant is evaluated using Arrhenius' law. Length of Section 1 Length of Section 2

This is a dimensionless length that is used to specify up to three different reaction sections. The length of the third section is calculated by 1-Length_1-Length_2. If only one section is needed, set the length of section 1 to '1' and section 2 to '0'. Range: 0-1 (-)

The different reactions can be enabled/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: HNCO Hydrolysis

118

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment

R2: NO Reduction

R3: NOx Reduction

R4: NO2 Reduction

R5: NH3 Oxidation 1

K

Determines the frequency factor used in the predefined power law mechanism.

E

Determines the activation temperature used in the pre-defined power law conversion mechanism.

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide and dioxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

K1 - K2

Determine the frequency factors used in the predefined Eley-Rideal conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined Eley-Rideal conversion mechanism.

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide and dioxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

K1 - K2

Determine the frequency factors used in the predefined Eley-Rideal conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined Eley-Rideal conversion mechanism.

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide and dioxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

K1 - K2

Determine the frequency factors used in the predefined Eley-Rideal conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined Eley-Rideal conversion mechanism.

The rate is assumed to be of first order with respect to ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

FIRE BOOST Aftertreatment

119

4. FIRE Aftertreatment

R6: NH3 Oxidation 2

R7: NO Oxidation

K

Determines the frequency factor used in the predefined power law mechanism.

E

Determines the activation temperature used in the pre-defined power law conversion mechanism.

The rate is assumed to be of first order with respect to ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined power law mechanism.

E

Determines the activation temperature used in the pre-defined power law conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. Each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

Approach 2

K

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism.

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism.

A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

4.1.4.4.1.4. Selective Catalytic Reduction (HSO SCR), Transient Kinetics This reaction model offers a set of nine conversion reactions that are typically used in SCR converters. This pre-defined model is setup in a way that three different reaction sections can be specified where in each section the reactions can be individually switched on. The name HSO is related to a typical SCR system where three different section for Hydrolysis, SCR, and Oxidation are used in one converter. If only one section is considered, the lengths of the two other sections simply can be set to zero. The model uses steady-state approaches for the hydrolysis, one of the ammonia and one of the nitric monoxide oxidation reactions. For the SCR reactions explicit ad-/desorption steps of ammonia at the solid surface are taken into 120

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment account. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. More detailed information about this model is given in page [83] Section HSO-SCR Catalyst Reactions, Transient Approach . Length of Section 1 Length of Section 2

This is a dimensionless length that is used to specify up to three different reaction sections. The length of the third section is calculated by 1-Length_1-Length_2. If only one section is needed set the length of section 1 to '1' and of section 2 to '0'. Range: 0-1 (-)

The different reactions can be en/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: HNCO Hydrolysis

R2-R3: NH3 Adsoprtion, Desorption

The rate is assumed to be of first order with respect to both vapor and isocyanic acid. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factors used in the predefined power law mechanism.

E

Determines the activation temperatures used in the pre-defined power law conversion mechanism.

The adsorption rate is of first order with respect to ammonia in the gas phase and also proportional to the free site fraction at the surface. The desorption rate is proportional to the amount of ammonia stored at the surface. For the desorption a surface coverage dependency is additionally taken into account. Each reaction constant is evaluated using Arrhenius' law. R2

R3

NH3 Storage Capacity

Determines the maximum amount of ammonia that can be stored at the solid surface site.

Initial Surface Coverage Fraction of NH3

Determines the coverage fraction of NH3 at the solid surface. Range: 0-1 (-)

Coverage Determines a surface coverage dependency in the Dependency pre-defined ad/desorption mechanisms. (epsilon) Max Surface

Determines the maximum surface coverage fraction of NH3 at the solid surface. This property

FIRE BOOST Aftertreatment

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4. FIRE Aftertreatment Coverage Fraction of NH3

can be specified as constant value or as function of temperature. Range: 0-1 (-)

NH3 Determines the order of NH3 surface coverage Surface fraction in the adsorption rate formulation. Coverage Range: 0-2 (-) Fraction Dependency m

R4: NO Reduction

R5: NOx Reduction

R6: NO2 Reduction

122

K1 - K2

Determines the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E2

Determines the activation temperatures used in the pre- ad/desorption mechanisms.

The reaction rate is of first order with respect to nitric monoxide in the gas phase and it depends on the stored amount of ammonia at the surface. The reaction is additionally limited by a critical surface fraction of ammonia.

Critical Surface Coverage)

Determines a tuning factor that slows down the reaction rate above a critical surface coverage.

K

Determines the frequency factor used in the predefined transient conversion mechanism.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism.

The reaction rate is of first order with respect to nitric dioxide in the gas phase and it depends on the stored amount of ammonia at the surface. The reaction is additionally limited by a critical surface fraction of ammonia.

Critical Surface Coverage)

Determines a tuning factor that slows down the reaction rate above a critical surface coverage.

K

Determines the frequency factor used in the predefined transient conversion mechanism.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism.

The rate is assumed to be of first order with respect to stored ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment

R7: NH3 Oxidation 1

R8: NH3 Oxidation 2

R9: NO Oxidation

Critical Surface Coverage)

Determines a tuning factor that slows down the reaction rate above a critical surface coverage.

K

Determines the frequency factor used in the predefined transient conversion mechanism.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism.

The rate is assumed to be of first order with respect to stored ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined transient oxidation mechanism.

E

Determines the activation temperature used in the pre-defined transient oxidation.

The rate is assumed to be of first order with respect to stored ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined power-law oxidation mechanism.

E

Determines the activation temperature used in the pre-power-law transient oxidation.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

Approach 2

Temperature Determines the temperature dependency used in Dependency the pre-defined transient and reversible power-law (A) conversion mechanism. K

Determines the frequency factor used in the pre-defined transient and reversible power-law conversion mechanism.

FIRE BOOST Aftertreatment

123

4. FIRE Aftertreatment

R10: NO2 Formation

E1

Determines the activation temperature used in the pre-defined transient and reversible power-law conversion mechanism.

K

Determines the frequency factor used in the predefined power-law conversion mechanism.

E

Determines the activation temperature used in the pre-defined power-law conversion mechanism.

4.1.4.4.1.5. NOx Trap Catalyst Reactions This reaction model offers a set of two conversion reactions for NO and a surface storage mechanism at one surface site. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. page [78] More detailed information about this model is given in Section TWC Catalyst Reactions . The different reactions can be enabled/disabled individually be clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: CO-NO Redox Reaction

R2: NO Oxidation

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide and reduction of nitric monoxide. The denominator takes into account an inhibition effect of carbon monoxide. Each reaction constant is evaluated using Arrhenius' law. The reaction order of carbon monoxide is a function of the carbon monoxide concentration itself and therefore the order changes between lean and rich conditions.

m

Determines the reaction order of nitric monoxide in the pre-defined reaction approach.

o

This is a tuning value in order to determine the reaction order of carbon monoxide in the predefined reaction approach.

K1 - K2

Determine the frequency factors used in the predefined conversion mechanism..

E1 - E2

Determine the activation temperatures used in the pre-defined conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy.

K

124

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism.

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment

R3-R4: Ba Storage

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism.

A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

In the presence of NO2 and O2, barium carbonate is oxidized to barium nitrate and in the presence of CO, barium nitrate is reduced to barium carbonate. All rates are of first order with respect to the participating gas and solid phase components. All reaction constant is evaluated using Arrhenius' law. R3

R4

Barium Storage Capacity

Determines the maximum amount of nitric oxide that can be stored on the barium surface site.

Initial Surface Coverage fraction of Ba(NO3)2

Determines the coverage fraction of Ba(NO3)2 at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of Ba(NO3)2

Determines the maximum surface coverage fraction of Ba(NO3)2 at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E2

Determine the activation temperatures used in the pre- ad-/desorption mechanisms.

4.1.4.4.1.6. Lean NOx Trap (LNT) This reaction model offers a set of ten conversion reactions, surface storage on cerium and barium. The rate equations and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. The different reactions can be en/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: H2 Oxidation

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

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125

4. FIRE Aftertreatment E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Order m

Determines the reaction order of nitric oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

R2: CO Oxidation

Reaction Determines the reaction order of propene, nitric Orders m, n, oxide and oxygen in the pre-defined Langmuirp Hinshelwood conversion mechanism. R3: C3H6 Oxidation

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Determines the reaction order of oxygen and nitric Orders m, n oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism. R4: NO Oxidation

126

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment Kinetic Determines a kinetic coefficient used in the Coefficient f pre-defined Langmuir-Hinshelwood conversion mechanism. Reaction Determines the reaction order of propene, nitric Orders m, n, oxide and oxygen in the pre-defined Langmuirp Hinshelwood conversion mechanism. R5: NO Reduction H2

K1

Determines the frequency factor used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1

Determines the activation temperature used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

R6: NO Reduction CO

Reaction Determines the reaction order of propene and nitric Orders m, n oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism. R7: NO Reduction C3H6 K1

Determines the frequency factor used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1

Determines the activation temperature used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

R8: NO2 Reduction CO

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127

4. FIRE Aftertreatment E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Order m

Determines the reaction order of nitric oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Ce Storage Capacity

Determines the maximum amount of oxygen that can be stored on the cerium surface site.

Initial Surface Coverage Fraction of CeO2

Determines the coverage fraction of CeO2 at the solid surface. This property can be specified as a constant value or as a function of the catalyst length. Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined ad/desorption mechanism. Determine the frequency factors used in the predefined ad/desorption mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined ad/desorption mechanism.

R9: NO2 Reduction C3H6

R10: Water Gas Shift Reaction

R11: Surface Storage on Cerium

Reaction Determines the reaction order of oxygen stored on Orders m, n, the surface and oxygen ratio at the surface in the p, q pre-defined ad/desorption mechanism. 128

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4. FIRE Aftertreatment R12-R16: Surface Storage on Barium Carbonate

R12

R13

R14

R15

R16

BaCO3 Storage Capacity

Determines the maximum amount of nitric oxides that can be stored on the barium carbonate clusters (rate approach 1) and barium carbonate surface site (rate approach 2).

Initial Surface Coverage Fraction of Ba(NO3)2

Determines the coverage fraction of Ba(NO3)2 at the solid surface. This property can be specified as a constant value or as a function of the catalyst length. Range: 0-1 (-)

Rate approach 1

This activates the sophisticated ash core model where the NO and NO2 molecules are stored as Ba(NO3)2 in barium cluster particles. Additional differential equations are solved to determine mole fractions of all gas phase species on the dimensionless ash core front position in the barium cluster particles. The ash core front moves from the outer radius ( =1) toward the center ( =0) page [88] of the cluster particle (see sketch in Fig. 36

Rate approach 2

This activates the surface storage model where the NO and NO2 molecules are stored as Ba(NO3)2 on the catalytic surface represented by the surface coverage fraction ZBa(NO3)2.

K1 - K5

Determine the frequency factors used in the pre-defined ad/desorption mechanism for Rate approach 1 and Rate approach 2. Determine the frequency factors used in the pre-defined ad/desorption mechanism for Rate approach 1 and Rate approach 2.

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129

4. FIRE Aftertreatment E1 - E5

Determine the activation temperatures used in the pre-defined ad/desorption mechanism.

Reaction Determines the reaction order of Ba(NO3)2 in the Orders m, n, pre-defined ad/desorption mechanism of Rate p, q, r approach 2. R12-R16: Ash Core Model

The ash core model is activated by Rate approach 1. R12

R13

R14

R15

R16

Particle Radius

Determines the radius RBa,p of the barium cluster particle. Typical Value: 5.0e-8 (m)

Min Specific Surface

Determines the minimum specific particle surface area ap,min. 2 3 Typical Value: 48.4 (m /m )

Max Specific Surface

Determines the minimum specific particle surface area ap,max. 2 3 Typical Value: 452637 (m /m )

Pore Diffusion Coefficient

Determines the diffusion coefficient DBa,p of the barium cluster particle. This property can be specified as constant value or as function of temperature. 2 Typical Value: 2.672e-14 (m /s)

Scaling The LNT model assumes that NOx desorption Factor (regeneration) takes place faster than NOx During adsorption (storage). This factor increases the pore Regeneration diffusion coefficient during regeneration. Typical Value: 10 (-)

130

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4. FIRE Aftertreatment 4.1.4.4.1.7. User Defined Reactions (Without Archive) This reaction model offers the possibility to define an arbitrary number of conversion reactions and surface storage mechanisms at different surface sites. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. More page [78] detailed information about this model is given in Section TWC Catalyst Reactions . 4.1.4.4.1.7.1. Surface Species Select Surface species in the parameter tree and select the Activate surface species toggle switch to access the following input fields: Typical Values and Ranges Number of surface sites

Defines the total number of site types on the catalytic surface. Example: Describe the active surface of a 3-way catalytic converter by using 2 sites, i.e. 'Platinum' and 'Rhodium'.

0-4 (-)

Ratio catalytic/ geometric surface area

Determines the ratio between the catalytic ('reactive') and the geometric surface area of the catalyst.

1-30 (-)

After entering a value >0 for Number of surface sites, the project tree expands and the corresponding input window for each site type appears. Typical Values and Ranges Name

Defines the name of the surface site. This string is arbitrary, e.g. Platinum.

NoName

No. of surface species on site

Determines the number of surface species on this site.

1-3 (-)

Site density

Determines the value of for this site.

in equation (Eq.34

page [15]

)

2

0-0.03 (mol/m )

Select Edit surface species to open a table: Typical Values and Ranges Names

Specifies the name of the species stored on the Surface surface as strings. As for the gas phase species, Species1 FIRE must find the names of all species in the internal thermochemistry database or in the CHEMKIN database thermdat. The number of surface sites occupied by the species is specified as an extra option after the species name encased by two slashes "/". The default value of 1 requires no extra specification. E.g.: H2 /2/ means that H2 is occupied by two surface sites

Initial coverage fractions

Defines the surface coverage fractions at start-up. As for the mass fractions these values must add up to 1.

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0-1 (-)

131

4. FIRE Aftertreatment Note: As for the gas phase species, FIRE must find the names of all surface species in the internal thermochemistry database or in the CHEMKIN database thermdat. 4.1.4.4.1.7.2. Stoichiometry Specification Select Stoichiometry specification in the parameter tree and then enter the following: Typical Values and Ranges Number of reactions

Defines the number of chemical reactions in the case. 0-50 Select Stoichiometry to open a table as shown in the following figure.

Figure 43. Stoichiometry Specification Window

A set of chemical reactions can be entered. The input conventions for each reaction are: • Use one line for each reaction • Only use species defined either as gas phase species or as surface species • Indicate surface species by adding "_S1", "_S2", "_S3", etc to the species' name. The index depends on the actual surface site index, e.g. "_S2" for all surface species on the second surface site. • Separate reactants from products by "=" • Separate species by "+" • Separate species from stoichiometric coefficient by "*" • Use "/" to specify extra options like arbitrary reaction order "RO" or the surface coverage parameters "COV". • Blanks between the separators ("=", "*", "+", and "/") and the species names or values are ignored. • Use UPPERCASE characters for species names • For reversible reactions it is recommended to specify the forward and backward reactions including all extra options separately, if the Equilibrium option of the current reaction is disabled. E.g.: NO + 0.5*O2 = NO2 NO2 = NO + 0.5*O2 132

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4. FIRE Aftertreatment The mass balance and the conservation of surface sites are checked by FIRE at runtime. An example for oxygen storage is O2+2*PT_S1=2*O_S1 Particulate filter model: • "C_P" is the identifier for the solid carbon in the soot layer. An example for the oxidation of solid carbon to carbon dioxide is: C_P+O2=CO2 Arbitrary reaction order: page [26] For elementary reactions the reaction orders (Eq.62 ) are determined by the stoichiometric coefficients. However, often in real-world applications measurements find that the reaction rate is proportional to the concentration of a species raised to some arbitrary power. FIRE allows declaring the reaction order for any species participating in the chemical reaction by specification of the keyword 'RO'. Therefore, the user has to attach the extra options starting with "/", setting the keyword "RO", the species name and the new value of the reaction order, as described by: / RO / RO The following example shows the change of the reaction orders for the NO-oxidation. Forward and backward reactions are specified separately. NO + 0.5*O2 = NO2 / RO NO 1.04 / RO O2 0.46 NO2 = NO + 0.5*O2 / RO NO2 1.03 Note, if the Activation of the current reaction is set to User, the reaction order is not changed automatically, since in this case the reaction rate has to be specified by the user in use_catrat.f or use_dpfrat.f. Surface coverage parameters: FIRE allows modifying the Arrhenius expression for the reaction rate constant by the coverage of some surface species (identified by strings "_S1", "_S2", etc attached to the species name). page [27] There the three surface coverage parameters of reaction i in Eq.66 , , , and can be specified as extra option via the keyword 'COV', as described by: / COV / COV ... The following example shows the set-up of the surface coverage parameters for the ammonia desorption: ME-NH3_S1 = NH3 + ME_S1 / COV ME-NH3 0.0 1.0 -0.256 Here = 0.0, = 1.0 and = -0.256. Note, if the Activation of the current reaction is set to User, the surface coverage parameters are not taken into account automatically, since in this case the reaction rate has to be specified by the user in use_catrat.f or use_dpfrat.f. 4.1.4.4.1.7.3. Kinetic Parameters Specification Select Kinetic parameters specification in the parameter tree to access the following input fields. Typical Values and Ranges Number of kinetic models

Defines the number of reaction kinetic parameter sets. Select Name of kinetic model to open a table: The actual name given to a kinetic model is used for the .fla file output only. A certain model is assigned to a catalyst via its index.

1-3 (-)

In general three flags (activation type, chemical equilibrium, sticking coefficient type) and three parameters (frequency factor, temperature exponent, activation energy) should be supplied for each reaction. Typical Values and Ranges Activation

On:

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On (default) 133

4. FIRE Aftertreatment Activates the standard rate equation (equation Eq.61 ). Off: Completely deactivates the reaction. User: The user can specify the rate of the reaction in use_catrat.f. If the catalyst is assigned to be a particulate filter, the user specifies the rate of the reaction in use_dpfrat.f.

page [26]

Equilibrium

Activates/deactivates the chemical equilibrium for Off (default) this reaction. If active, the equilibrium constant Kc is calculated to determine the backward rate constant kr page [27] page [26] (Eq.66 ) as used in equation Eq.61 . Note, if the Activation of the current reaction is set to User, the equilibrium calculation is skipped, since then the reaction rate has to be specified in use_catrat.f or use_dpfrat.f.

Sticking Coefficient

Activates/deactivates the sticking coefficient type rate equation (surface reactions only). Note, if the Activation of the current reaction is set to User, the equilibrium calculation is skipped since in this case the reaction rate has to be specified in use_catrat.f or use_dpfrat.f.

Off (default)

Frequency factor

Frequency factor kf of the Arrhenius rate law; the actual units depend on the type of reaction.

0-10 s, k)

Use cgs units

When enabled, all frequency factors are interpreted in Disabled the cgs unit system (mol, cm, s). (default)

Temperature Exponent

Temperature exponent b of the Arrhenius rate law.

0-1 (-)

Activation Energy

Activation energy E of the Arrhenius rate law.

0-50000 (kJ/ kmol)

15

(kmol, m,

indicates that the user can input values in a table relating to the number of kinetic models. The following options are available: 1. Constant This is the default setting and specifies that the parameter value entered in the field will remain constant for all kinetic models. 2. Model Select it to open an input table where parameter values can be entered for each kinetic model separately. Select the User parameter toggle switch to activate the following: Default

134

Default

Default

UP_1

0

UP_6

0

UP_11

0

UP_2

0

UP_7

0

UP_12

0

UP_3

0

UP_8

0

UP_13

0

UP_4

0

UP_9

0

UP_14

0

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4. FIRE Aftertreatment UP_5

0

UP_10

0

UP_15

0

The user can input up to 15 user parameters for each reaction. These values are not used by FIRE directly, but they can be accessed by the user in use_catrat.f when supplying his own kinetic models. 4.1.4.4.1.8. Map Based Conversion This model comprises different input of conversion maps, where the user can specify the conversion of selected species depending on several conditions like massflow, substrate temperature and further more. Species conversion maps can be added or removed by clicking the right mouse button on the tree node Map Based Conversion. Conversion Definition The following input data has to be specified: Typical Values and Ranges Species

Enter the name of a General Species whose conversion is specified for. If the species is not contained in the Gas Composition then the Conversion map is ignored.

Conversion

Select the conversion specification Constant: Enter a constant conversion value. Table: Specify the conversion as a function of one of the conversion dependencies. Map: Specify the conversion as a function of two of the conversion dependencies. If Constant is selected, enter a value for constant species conversion.

Table for Conversion of The following input data has to be specified: Typical Values and Ranges Conversion Dependency

The following Conversion Dependencies are available: • Inlet Gas Temperature • Mean Solid Temperature • Inlet Massflow • Inlet Excess Oxygen Ratio • Inlet GHSV

Conversion Table

Specify the conversion as a function of the selected Conversion Dependency.

Map for Conversion of The following input data has to be specified:

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4. FIRE Aftertreatment Typical Values and Ranges Conversion Dependency 1 and Conversion Dependency 2

The following Conversion Dependencies are available: • Inlet Gas Temperature • Mean Solid Temperature • Inlet Massflow • Inlet Excess Oxygen Ratio • Inlet GHSV

Conversion Map

Specify the conversion as a function of the selected Conversion Dependency 1 and Conversion Dependency 2.

4.1.4.4.1.9. User Defined Reactions This is an interface to load custom kinetic models developed using the AVL User Coding Interface (AUCI). Loading and maintaining an AUCI Catalytic Reaction Mechanism In general an arbitrary number of AUCI Catalytic Reaction Mechanism models can be loaded. In order to add or delete an AUCI model click Insert and Remove repsectively next to the table. An AUCI model ("Archive") is stored in an ucp and uca file respectively, and the existing predefined kinetic models are available as ucp files in the installation. An already loaded Archive can be enabled or disabled in the simulation by selecting Yes and No respectively in the first column of the table. The buttons below the table provide the following functions: Button

Description

Select Archive

Opens a filebrowser to select an ucp or uca file.

Reload Archive

Reload the Archive from the selected row. In order to reset the Model Parameters with the default values from the AUCI model click "No" in the pop-up box "Keep current parameter values?".

Edit Archive

Launches AUCI Catalytic Reaction Mechanism graphical user interface (GUI). If a row has been selected in the table the AUCI model will be opened in that GUI.

Model Parameters

Interface to access the public model parameters from the selected Archive. In the pop-up window these parameters can be modified and global/local parameters can be assigned to them for access in the Parameter or Case Explorer.

Designing an AUCI Catalytic Reaction Mechanism AUCI is a graphical user interface that supports designing custom kinetic models for catalysts and filters as well as custom transfer models for heat and mass transfer as well as pore diffusion. Please, refer to the related AUCI documentation for more details on using AUCI. 4.1.4.4.2. Transport Model At "My_Transport" different pore diffusion models can be selected. The transport model for the active washcoat layer model determines the calculation of the diffusion coefficient Dk,eff for every species of the pore diffusion model (see section Transport Models 136

page [21]

).

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4. FIRE Aftertreatment Note: For specification of the transport model, Activate Washcoat Layer (WCL) Model must be active. The transport model has to be specified for each washcoat layer separately. The following models are available: 4.1.4.4.2.1. Constant Pore Diffusion For this model constant diffusion coefficients are applied. If Constant Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Layer Porosity

Determines the porosity wcl of the washcoat layer (= gas void fraction).

0-1 (-)

Diffusion Coefficients

Determines the effective diffusion coefficient Dk,eff of every species in the washcoat layer.

10

-14

-5

2

-10 (m /s)

4.1.4.4.2.2. Effective Pore Diffusion The effective diffusion coefficient is calculated with the free gas flow diffusion coefficient adapted with the washcoat layer porosity and tortuosity. A scaling factor allows linear variation of the calculated value for every species. If Effective Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Layer Porosity

Determines the porosity wcl of the washcoat layer (= gas void fraction).

0-1 (-)

Tortuosity

Determines the tortuosity layer.

1-5 (-)

Scaling Factors

Determines the scaling factors multiplied to the calculated effective diffusion coefficient Dk,eff of every species in the washcoat layer.

wcl

of the washcoat

0-100 (-)

4.1.4.4.2.3. Random Pore Diffusion This model assumes that the washcoat features two distinct characteristic pore size diameters, called macro- and micro-pores. The two macro and micro pore diffusion coefficients are combined applying probabilistic and geometrical considerations. If Random Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Macropore Porosity

Determines the porosity (= gas void fraction) of the macro pores.

Micropore Porosity

Determines the porosity (= gas void fraction) of the micro pores.

0-1 (-)

Macropore Diameter

Determines the mean diameter of the macro pores.

10 -10 (m)

Micropore Diameter

Determines the mean diameter of the micro pores.

10 -10 (m)

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M

0-1 (-)

-8

-4

-9

-5

137

4. FIRE Aftertreatment Scaling Factors

Determines the scaling factors multiplied to the calculated effective diffusion coefficient Dk,eff of every species in the washcoat layer.

0-100 (-)

4.1.4.4.2.4. Parallel Pore Diffusion The model combines the transport effects of the pure gas phase and Knudsen diffusion assuming both transport effects are taking place in parallel. If Parallel Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Layer Porosity

Determines the porosity wcl of the washcoat layer (= gas void fraction).

0-1 (-)

Tortuosity

Determines the tortuosity layer.

1-5 (-)

Pore Diameter

Determines the mean pore diameter of washcoat layer.

10 -10 (m)

Scaling Factors

Determines the scaling factors multiplied to the calculated effective diffusion coefficient Dk,eff of every species in the washcoat layer.

0-100 (-)

wcl

of the washcoat

-9

-3

4.1.4.4.2.5. User Pore Diffusion The effective diffusion coefficient is calculated in the user function use_catwcltra.f. An example of the user function can be found in the installation. If User Pore Diffusion is selected, the following input data can be specified: Typical Values and Ranges Layer Porosity

Determines the porosity wcl of the washcoat layer (= gas void fraction).

Parameter Label

Parameter strings which can be used in the user-function for identification of the Transport Parameter.

Transport Parameter

Double precision value which can be used in the user function.

0-1 (-)

4.1.4.5. Catalyst Reaction Solver Specification Select Catalyst Reaction Solver Specification in the parameter tree to access the following input fields. 4.1.4.5.1. Reaction Solver Parameters Typical Values

138

Catalytic reaction Specifies the maximum number of sub-iterations solver: max. no. of that the solver carries out for the catalytic reactions. iterations Normally no changes are required.

20000 (-)

Catalytic reaction solver: relative tolerance

1e-05 (-)

Specifies the relative tolerance for the solution of the reaction rate equation system. Normally no changes are required.

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4. FIRE Aftertreatment Catalytic reaction solver: absolute tolerance

Specifies the absolute tolerance for the solution of the 1e-08 (-) reaction rate equation system. Normally no changes are required.

4.1.4.5.2. General Settings Typical Values and Ranges Implicit solution of Normally the reaction rate equation system is solved chem. kinetics at the beginning of a time step. Depending on the problem (i.e. chemical equilibrium problems) it can be necessary to solve it within the time step also, i.e. th specify 5 to solve it every 5 iteration for large time steps. A value of 0 turns off implicit solver calls.

0-20 (-)

Reaction solver block size

In order to speed up the solution of the chemical 1-50 (-) kinetics, the corresponding equation system is not solved for each cell separately but more cells are considered for each solver call. The number of cells is given here.

Solve catalytic reactions

Activates/deactivates the solution of the kinetic rate equation system and the corresponding source terms for heat and mass. If deactivated, only the heat exchange between the gas and the monolith is calculated without chemical reactions.

Active (default)

Consider enthalpy Activates/deactivates the consideration of the sources from enthalpy sources from the catalytic reactions in the catalytic reactions enthalpy equation for the solid material ('isothermal'). If deactivated, only the species sources from the catalytic reactions are considered.

Active (default)

Activate user Activates/deactivates the user function model for use_catmod.f. This user function is called by FIRE catalytic reactions instead of the FIRE catalyst reaction model. Here (use_catmod.f) the user defines the source terms for the species transport equations and the enthalpy equation. It is typically used by advanced users who have their own models available and need full flexibility for their implementation. Please contact FIRE support for more information on use_catmod.f.

Inactive (default)

4.1.4.5.3. Reaction Solver Flags Select Reaction solver flags in the parameter tree to access the following input fields. Typical Values and Ranges On / Off

Activates/deactivates input flags. The 23 input fields are for AVL internal use only.

Off (default)

4.1.4.6. 2D Output Specification Select 2D Output Specification in the parameter tree to access the following input fields.

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4. FIRE Aftertreatment 4.1.4.6.1. Substrate Data Typical Values and Ranges Mean catalyst temperature

Activates/deactivates the output of the mean catalyst temperature to the .fla file and to the .fl2 file.

Active (default)

Maximum catalyst temperature

Activates/deactivates the output of the maximum catalyst temperature to the .fla file and to the .fl2 file.

Active (default)

Minimum catalyst Activates/deactivates the output of the minimum temperature catalyst temperature to the .fla file and to the .fl2 file.

Active (default)

Solid heat capacities

Inactive (default)

Activates/deactivates the output of the minimum, maximum and mean value of the solid specific heat capacity (J/(kg·K)) of the catalyst to the .fla file and to the .fl2 file. Data is only written for temperature dependent values. Click on

Solid thermal conductivities

Activates/deactivates the output of the minimum, Inactive (default) maximum and mean value of the solid thermal conductivity (W/(m·K)) of the catalyst to the .fla file and to the .fl2 file. Data is only written for temperature dependent values. Click on

Gradient of solid temperature

to define table data.

to define table data.

Activates/deactivates the output of the maximum and mean value of the solid temperature gradient (K/m).

Inactive (default)

4.1.4.6.2. Pressure Drop Typical Values and Ranges Catalyst pressure Activates/deactivates the output of the total pressure Active (default) drop drop (Pa) of the catalyst to the .fla file and to the .fl2 file. 4.1.4.6.3. Flow Uniformities Typical Values and Ranges Uniformity index

Activates/deactivates the output of the uniformity index Inactive (default) (-) of the catalyst to the .fla file and to the .fl2 file. The uniformity index is calculated in the first porous cell layer according to the equation where is the cell velocity vector, and is the crosssection area of face adjacent to cell i. Note: In the first porous cell layer, the gas velocity already points in the converter direction .

Centricity index

140

Activates/deactivates the output of the centricity index Inactive (default) (-) of the catalyst to the .fla file and to the .fl2 file.

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4. FIRE Aftertreatment The centricity index is determined at the inlet face selection of the particulate filter according to equation , where the eccentricity

denotes the

distance between the center of the mean mass flow rate and the center of gravity, as described by

is the equivalence radius, determined by the equation

.

is the mass flow rate through face j is the face area is the position vector of the face center. Max./Min. inlet velocities

Activates/deactivates the output of minimum and the Inactive maximum inlet velocity (m/s), and the position of the maximum inlet velocity (m) of the catalyst to the .fla file and to the .fl2 file. The max. and min. inlet velocity are determined in the last non-porous fluid cell layer in front of the particulate filter.

High and low speed inlet area

Activates/deactivates the output of the high and low Inactive (default) speed inlet areas (-) of the catalyst to the .fla file and to the .fl2 file. The high speed inlet area is defined as the inlet area fraction, where the flow velocity is greater than the bound of . The low speed inlet area is the inlet area fraction, where the flow velocity is smaller than . Both the high and the low speed inlet areas are evaluated in the first porous cell layer of the catalyst.

Tangential inlet velocity

Activates/deactivates the output of the mean, the Inactive(default) minimum, and the maximum tangential velocity (m/s) of the catalyst inlet to the .fla file and to the .fl2 file. The tangential inlet velocity is the amount of the velocity components which point into the direction perpendicular to the catalyst direction. It is evaluated in the last non-porous fluid cell layer in front of the catalyst.

Tangential inlet Activates/deactivates the output of the mean, the pressure gradient minimum, and the maximum tangential pressure gradient [Pa/m] of the catalyst inlet to the .fla file and to the .fl2 file. The tangential inlet pressure gradient is the amount of the gradient components which point into the direction

FIRE BOOST Aftertreatment

Inactive (default)

141

4. FIRE Aftertreatment perpendicular to the catalyst direction. It is evaluated in the last non-porous fluid cell layer in front of the catalyst. Gas hourly space Activates/deactivates the output of the gas hourly velocity (GHSV) space velocity at operation conditions (GHSV) (1/h) and the gas hourly space velocity at norm conditions (GHSVn) (1/h) of the catalyst to the .fla file and to the .fl2 file. The gas hourly space velocity is the volume flux of the gas divided by the entire volume of the catalyst or particulate filter. The GHSV at operation conditions is calculated by:

Inactive (default)

The GHSVn at norm conditions is calculated by:

where the gas density 1.013 bar.

is evaluated at 273.15 K and

4.1.4.6.4. Conversions Typical Values and Ranges Species conversions

Activates/deactivates the output of the species' conversions to the .fla file and to the .fl2 file. The conversion C for species k is calculated as:

Surface coverage Activates/deactivates the output of the mean surface fraction coverage fractions (-) of the surface species of the catalyst to the .fla file and to the .fl2 file.

Inactive (default)

Excess oxygen ratio at inlet

Inactive (default)

The excess oxygen ratio is the amount of molecular oxygen in the gas divided by the amount of required oxygen for full combustion of carbon and hydrogen minus the provided oxygen in nitric-oxides and other oxygen compounds. z is the number of oxygen in the molecule AOz where A is an arbitrary element. In the

142

Active (default)

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4. FIRE Aftertreatment molecule CxHy is x the number of carbon and y the number of hydrogen atoms respectively. Redox ratio at inlet

Inactive (default)

The redox ratio RR is the amount of oxygen required for full oxidation of carbon and hydrogen divided by the amount oxygen available in the gas-phase. A is an arbitrary element, z the number of oxygen atoms in the molecule AOz. x and y are the number of carbon and hydrogen atoms in an arbitrary composition of a hydrocarbon CxHy. 4.1.4.6.5. Washcoat Layer Results of the washcoat layer (WCL) model can be plotted as mean values over the whole layer, and they can be plotted individually for certain washcoat layer depths of selected mesh cells of the catalyst monolith. Therefore, one has to specify the cells at Select monolith cells for detailed 2D result output. The following results are available for both enabled and disabled washcoat layer model. The following input fields are available: Typical Values and Ranges WCL Mole Fraction

Activates/deactivates the mean value output and the selected cell output of the species' mole fractions to the .fla file and to the .fl2 file.

Inactive (default)

WCL Mass Fraction

Activates/deactivates the mean value output and the selected cell output of the species' mass fractions to the .fla file and to the .fl2 file.

Inactive (default)

WCL Species Concentration

Activates/deactivates the mean value output and the selected cell output of the species' concentrations fractions to the .fla file and to the .fl2 file.

Inactive (default)

WCL Effective Diffusion Coefficient

Activates/deactivates the mean value output and the selected cell output of the species' effective diffusion coefficients to the .fla file and to the .fl2 file. Only available for enabled washcoat layer model.

Inactive (default)

WCL Species Rate

Activates/deactivates the mean value output and the Inactive (default) selected cell output of the species' rates to the .fla file and to the .fl2 file.

WCL Reaction Rate

Activates/deactivates the mean value output and the Inactive (default) selected cell output of the reaction rates to the .fla file and to the .fl2 file.

WCL Stored Species Fraction

Activates/deactivates the mean value output and the selected cell output of the stored species' fractions to the .fla file and to the .fl2 file.

Inactive (default)

WCL Stored Species Loading

Activates/deactivates the mean value output and the selected cell output of the stored species' loadings to the .fla file and to the .fl2 file.

Inactive (default)

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143

4. FIRE Aftertreatment 4.1.5. Particulate Filter Specification To add a Particulate Filter (DPF) to the project, click on Aftertreatment TNG in the parameter tree with the right mouse button and select DPF: Insert from the submenu. To delete a DPF from the project, click on the name of the DPF (i.e. DPF[1]) with the right mouse button and select Remove from the submenu. The specification of the particulate filter follows the input concept of the catalytic converter page [100] presented in Section Catalyst Specification . Figure 44. DPF Specification Parameter Tree

Copy from DPF allows the complete set of input data to be copied from DPF[X] to the present DPF. Figure 45. Copy from DPF function

4.1.5.1. General Particulate Filter Specification Select DPF specification in the parameter tree to open the following window: Figure 46. DPF Specification Window

4.1.5.1.1. Particulate Filter Specification Typical Values and Ranges

144

Cell selection

Supply a cell selection that defines the geometry NoSelection of the particulate filter. (default)

Inlet face selection

Supply a face selection that defines the inlet plane of the particulate filter.

NoSelection (default)

Outlet face selection

Supply a face selection that defines the outlet plane of the particulate filter.

NoSelection (default)

Monolith initialization temperature

Determines the initial temperature of the particulate filter.

293.15-1500 (K)

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment 4.1.5.1.2. Square Cell + Asymmetrical Cell PF Click on Square + Asymmetrical Cell PF to obtain the parameter specification of the square cell PF. Typical Values and Ranges 2

Cell density (CPSI) Determines the type of monolith: Number of channels 2 per in .

100-900 (1/in )

Wall thickness

0.006-0.015 (in)

Determines the thickness of the monolith's walls = Wall.

Enable Enables the calculation for asymmetrical channel Asymmetrical diameters. Channel Diameters

Off (default)

Ratio of Channel Diameters

1-1.4 (-)

Determines the ratio of the channel diameters (d1/d2, page [144] see Fig. 46 ).

4.1.5.1.3. Simplified Square Cell PF Click on Simplified Square Cell PF to obtain the parameter specification of the square cell PF with equal inlet and outlet channel diameter. The simplified square cell PF corresponds to a Square + Asymmetrical Cell PF with diameter ratio of 1. Typical Values and Ranges Open frontal area (OFA)

Determines the open frontal area (= fluid volume fraction) of monolith ( g).

0.5-0.75 (-)

Hydraulic diameter

Determines the hydraulic diameter of the monolith (d). 0.001-0.005 (m)

4.1.5.1.4. Hexahex Click on Hexahex to obtain the following parameter specification. Typical Values and Ranges 2

Cell density (CPSI) Determines the total number of inlet and outlet 2 channels per in .

200-500 (1/in )

Wall thickness

Determines the thickness of the monolith's walls = Wall.

0.004-0.015 (in)

Inlet Channel Side Ratio (a/b)

Determines the ratio between the side lengths a and b of the hexagonal inlet channel.

0.666 (-) (default)

Perimeter Efficiency (a)

Since the side length a is located adjacent to another inlet channel wall of side length a, it is expected that there is reduced filtration along this wall. The Perimeter Efficiency determines the fraction of the side length used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall

0.0-1.0 (-)

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145

4. FIRE Aftertreatment 4.1.5.1.5. Hex3 Click on Hex3 to obtain the following parameter specification. Typical Values and Ranges 2

Cell density (CPSI) Determines the total number of inlet and outlet 2 channels per in .

200-500 (1/in )

Wall thickness

Determines the thickness of the monolith's walls = Wall.

0.004-0.015 (in)

Inlet Channel Side Ratio (a/b)

Determines the ratio between the side lengths a and b of the hexagonal inlet channel.

0.81 (-) (default)

Perimeter Efficiency (a)

Since the side length a is located adjacent to another inlet channel wall of side length a, it is expected that there is reduced filtration along this wall. The Perimeter Efficiency determines the fraction of the side length used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall

0.0-1.0 (-)

4.1.5.1.6. General Cell PF Click on General Cell PF to obtain the parameter specification of any arbitrary inlet channel geometry which can be reproduced by multiple reflection of the general symmetry element (GSE). Note, the GSE is the geometrical base of the PF inlet channel geometries in BOOST/ FIRE since it determines the formation and structure of the soot and ash layer. The Unity Cell represents the smallest repetitive element for reflection to represent the PF geometry consisting of inlet and outlet channels. Typical Values and Ranges 100-900 (1/in )

Nr of Inlet Determines the number of inlet channels per unity Channels per Unity cell. Cell

1-3 (-)

Nr of Outlet Determines the number of outlet channels per unity Channels per Unity cell. Cell

1 (-)

Nr of GSEs per Inlet Channel

Determines the number of general symmetry elements per single inlet channel.

1-12 (-)

Wall thickness

Determines the thickness of the monolith's walls = wall.

0.004-0.015 (-)

Center Corner Determines the sum of the angles Angle (alpha+beta) general symmetry element.

146

2

Cell density (CPSI) Determines the total number of inlet and outlet 2 channels per in .

and

of the

45-90 (deg)

Right Corner Angle (gamma)

Determines the angle

of the GSE.

45-90 (deg)

Left Corner Angle (phi)

Determines the angle

of the GSE.

45-90 (deg)

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment Side length (l1)

Determines the length of the first side along the channel wall of the GSE.

0.1-1 (mm)

Side length (l2)

Determines the length of the second side along the channel wall of the GSE.

0.1-1 (mm)

Filtration Efficiency at l1

The Filtration Efficiency determines the faction of the side length l1 used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall.

0-1 (-)

Filtration Efficiency at l2

The Filtration Efficiency determines the fraction of 0-1 (-) the side length l2 used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall.

Channel Shape Factor

Determines the difference of the pressure drop due to the gas flow in the channels between the present channel and a channel of circular shape. The shape factor is 0.89 for squared channels 0.95 for hexagonal channels 0.98 for octagonal channels, and 1.0 for channels with circular cross-section.

Outlet Channel Perimeter

Determines the perimeter of the single outlet channel. 1-10 (mm)

Outlet Channel Cross Section

Determines the cross-section of the single outlet channel.

0.5-1 (-)

2

0.5-5 (mm )

4.1.5.1.7. Physical Properties Select DPF Physical Properties in the parameter tree to access the following input fields. Typical Values and Ranges Density

Determines the bulk density of the monolith material considering the volume in the pores.

400-2000 (kg/ 3 m )

Thermal conductivity

Determines the thermal conductivity of the monolith material (= bulk solid material considering the volume in the pores). The thermal conductivity can either be specified as a constant value or as a table where the value changes as a function of temperature. Click on

0.1-50 (W/(m·K))

to define table data. Specific heat

Determines the specific heat of the monolith material 500-2000 (J/ (= bulk solid material considering the volume in the (kg·K)) pores). The specific heat can either be specified as a constant value or as a table where the value changes as a function of temperature. Click on table data.

Anisotropic cond. Factor

to define

Corrects the diffusion coefficients of the solid temperature equation normal to axial direction. A

FIRE BOOST Aftertreatment

0-10 (-) 147

4. FIRE Aftertreatment value of 1.0 simulates an isotropic conductivity. A value of 0.5 would be a good choice for monoliths. The anisotropic conduction factor is not used if the user-defined parameter ATM_ACTIV_RADIATION is specified and the current catalyst is selected (Fig. page [106] 39 ). Then the effective thermal conductivity including radiation is used instead of the default anisotropic model (see section Anisotropic Heat page [10] Conduction Matrix ). 4.1.5.1.7.1. Glueing Zones Typical Values and Ranges On/Off

Activates the consideration of glueing zones within particulate filters (e.g. SIC-PFs).

Off (default)

Selection

Specifies the glueing zone cell selection. This selection must not additionally be defined as particulate filter cell selection.

NoSelection (default)

Initialization temperature

Determines the initial temperature of the glueing material.

293.15-1500 (K)

Density

Determines the density of the glueing material.

400-2000 (kg/ 3 m )

Thermal Conductivity

Determines the thermal conductivity of the glueing material.

0.1-50 (W/(m·K))

Specific Heat

Determines the specific heat of the glueing material.

500-2500 (J/ kgK)

Filter area reduction

Activates the consideration of the filter area reduction of inlet channels which are directly adjacent to the glueing zones. A correct treatment of the filter area reduction requires a mesh size of these cells in the range of the inlet channel size.

Off (default)

4.1.5.1.7.2. Reduction of Heat Conduction Typical Values and Ranges

148

On/Off

Activates the local reduction of the heat conduction on a certain region in the particulate filter defined by a face selection of internal faces. Before the glueing zone model was available, this model was the only rough approximation of the heat transfer change in segmented particulate filters.

Off (default)

Selection

Face selection of internal faces on which the head conduction is multiplied with the factor defined at Reduction factor.

NoSelection (default)

Reduction factor

Heat reduction factor.

0-1 (-)

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment 4.1.5.1.8. External Heat Source FIRE allows to specify constant heat sources arbitrary cell selections. The setup is the same as page [108] for the catalyst which is explained in section External Heat Source . 4.1.5.2. Soot and Filter Properties Select Soot and Filter Properties in the parameter tree to access the following input fields. The soot and filter properties comprise thermodynamic data of the soot and fluid mechanic information of the soot and the filter. Additionally a particle mass can be specified that is used as initial condition for all soot mass balances. 4.1.5.2.1. Soot Layer Properties Typical Values and Ranges 3

Layer Packing Density

Determines the packing density of the soot.

5-30 (kg/m )

Migration Constant

Determines the impact of soot migration due to a convective transport.

1E-15-1E-5 (-)

4.1.5.2.2. Pressure Drop Typical Values and Ranges 2

Wall Permeability

Determines the permeability of the filter wall.

1E-15-1E-12 (m )

Soot Permeability

Determines the permeability of the soot bed. This property may be specified as one of: • Constant • Table (dependent on temperature or wall velocity) • Map (dependent on both, temperature and wall velocity) • Formula (see. Soot Permeability page [50])

1E-16-1E-13 (m )

Enable Depth Filtration

Enables the application of a depth filtration layer in addition to a cake filtration layer

Off (default)

Sublayer Thickness

Determines the thickness of the depth flirtation layer.

10-100 (micron)

Depth Filtration Threshold

Determines the maximum soot loading that can be deposited within the depth filtration layer

0-3 (g/l)

Depth Filtration Permeability

Determines the permeability of the soot depth filtration layer

1E-16-1E-13 (m )

Inlet Loss Coefficient

Friction factor for pressure losses at the inlet.

0.5-10 (-)

Outlet Loss Coefficient

Friction factor for pressure losses at the outlet.

0.5-10 (-)

Consider Inlet/ Outlet Plugs

Enables the specification of inlet and outlet plugs closing the inlet and outlet channel at one site.

Off (default)

Length of PF Inlet- Determines the length of the inlet and outlet plugs. Outlet Plugs

FIRE BOOST Aftertreatment

2

2

0-20 (mm)

149

4. FIRE Aftertreatment 4.1.5.2.3. Filter Inlet Boundary Condition Typical Values and Ranges Csoot [kg Particles/kg Gas]

Defines the concentration of soot in the gas phase at the inlet of the particulate filter. It has units [kg particles/kg gas]. Choose between constant, table and formula.

0-1 (kg/kg)

4.1.5.2.4. Particulate Filter Initialization Typical Values and Ranges Particulate filter initialization

Defines the initial particle mass and distribution in the filter. Choose between constant, table and formula. Particle mass

0-20 [kgsoot / 3 m Filter]

Distribution type Constant 0 uniform distribution 1 linearly increasing 2 linearly decreasing 3 all soot is distributed close to inlet (first 50% of filter length) 4 all soot is distributed close to outlet (second 50% of filter length) 5 parabolic distribution (minimum in the middle of the filter) 6 parabolic distribution (maximum in the middle of the filter) 7 constant in first 50% of filter, decreasing to outlet 8 constant in second 50% of filter, decreasing to inlet

0 (default)

Distribution type Table Click on

to define table or formula data.

Scaling factor for The scaling factor is multiplied by the existing soot soot mass (restart) mass in every particulate filter cell after the restart. This factor allows to adjust the total soot mass of a regeneration simulation restarted from a loading simulation. Extended Output

1.0-100 (-)

Activates an extended soot and filter property output On (default) to the file at the beginning of the calculation.

4.1.5.3. Ash Properties Select Ash Properties in the parameter tree to access the following input fields. Typical Values and Ranges Enable Ash Model 150

If On/Off is selected, the ash model is activated.

FIRE BOOST Aftertreatment

Off (default)

4. FIRE Aftertreatment 3

Ash Packing Density

Determines the packing density of the ash layer.

100-500 (kg/m )

Ash Permeability

Determines the permeability of the ash layer.

1E-15-1E-13 (m )

Specify Ash Plug Fraction

Enables the distribution of the ash mass into a Layer and a Plug fraction

Off (default)

2

Ash Layer/Plug Determines the ratio of ash that is stored in the Distribution Factor ash layer to ash stored in the ash plug. A factor of 1 means all the ash is stored in the layer. A factor of 0 means all the ash is stored in the ash plug. If the ash loading is not specified as constant value but as function of the filter length, the shape of the axial profile is kept but scaled down by the ashdistribution factor.

(0-1) (-)

Ash Mass

0-100 (g/l)

Determines the initial ash loading in the filter. This property can be specified as a constant value, as a function of the filter length or as a formula. Click on

to define table or formula data.

4.1.5.4. Chemical Reactions BOOST has four different pre-defined reaction models for the simulation of soot regeneration. The reaction model can be applied to two different reaction zones, an upper and a catalytic sub-layer. For both layers one and the same reaction approach is applied, where the user has access to all reaction parameters. The reaction scheme in the sub layer can only be activated if the Depth Filtration Model is also enabled. The parameters can be defined separately for each reaction layer. Additionally the user can specify an arbitrary number of coating zones which are applied to all catalytically supported reactions (depth filtration layer, filter wall and outlet channel). Each kinetic parameter of a chosen catalytically supported reaction can be individually specified for each Coating Zone. Together with the O2-thermal and O2-fuel-additive Soot Regeneration Mode the Oxygen diffusion into the soot layer can be considered. Therefore a lumped diffusion coefficient has to be specified. In the catalytic wall layer, a pre-defined reaction model is available with full access to all reaction parameters. Furthermore there is the possibility for the user to define a kinetic model with an page [132] arbitrary number of catalytic reactions (see section Stoichiometry Specification and page [133] section Kinetic Parameters Specification ). Note that all reaction parameters were chosen for one type of regeneration simulation. For other filter applications these reaction parameters may change and therefore have to be supplied by the user. Enable O2 Diffusion into Soot Layer Lumped DiffusionCoefficient

On /Off -6

-5

2

Coefficient for the concentration gradient driven O2 10 -10 (m /s) diffusion from the inlet channel into the soot layer.

Soot Regeneration Mode None

No reactions are taken into account. In this case sub-layer reactions cannot be specified.

O2-thermal

A reaction mechanism (see Section Filter Regeneration with Oxygen [90] ) consisting of two reactions is applied. Soot is oxidized depending on the temperature range either to CO or to CO2.

page

FIRE BOOST Aftertreatment

151

4. FIRE Aftertreatment O2-fuel-additive

The same reaction mechanism as given by O2-thermal is set up.

O2-NO2

In addition to the reaction mechanism of O2-thermal, a soot oxidation reaction in presence of NO2 can be used and specified. Details of this NO2 reaction are explained in Section Filter Regeneration with Oxygen page [91] and Nitric Dioxide .

O2-NO2-NO2catalytic

In addition to the reaction mechanism of O2-NO2 the reversible oxidation of NO to NO2 is taken into account. As explained in Section page [92] Filter CSF Catalytic Reactions , this reaction is catalytically supported and takes place in the sub-layer that can be specified. In the upper layer the reaction can be switched off by setting the appropriate reaction constants.

User Defined

This enables the possibility to supply user-defined soot regeneration models. The specification of these models is described in section page [132] Stoichiometry Specification and section Kinetic Parameters page [133] Specification .

PF Zone Coating Table

An arbitrary number of Coating Zones can be inserted for which dimensionless section lengths have to be defined. The sum of all section lengths has to be one.

Regeneration Mode Sublayer Toggle switch

This enables or disables the application of soot sub-layer reactions. The switch only can be activated if the Depth Filtration Model is also enabled.

Catalytic Wall Reactions None

No catalytic wall reactions are taken into account.

CO-HC-NOConversion

A pre-defined reaction mechanism for the catalytically supported conversion of CO, C3H6, C3H8 and NO is enabled.

Selective Catalytic Reduction

A predefined reaction mechanism for the catalytically supported SCR reactions is enabled.

User Defined

This enables the possibility to supply user-defined wall reaction models. The specification of these models is described in section Stoichiometry page [132] page [133] Specification and section Kinetic Parameters Specification .

Fraction of Catalytic Wall Height

Determines a fraction of the entire wall height that is catalytically active. A fraction of 1 comprises the entire wall height.

0-1 (-)

Catalytic Reactions Outlet Channel Enable Outlet Channel Reactions Mass Transfer Scaling Factor

This specifies a factor for the linear scaling of the mass transfer from the outlet channel bulk to the catalytic filter wall.

On/Off

Note: The activation of Regeneration Mode Sublayer is only possible if depth filtration is activated (Enable Depth Filtration at Soot and Filter Properties). 152

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment 4.1.5.4.1. Soot Regeneration Mode O2 - Thermal

O2 - Fuel Additive

K

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

Ef

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

K

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user

FIRE BOOST Aftertreatment

153

4. FIRE Aftertreatment can choose the table option to specify individual values for each coating section. Ef

O2 - NO2

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

O2 K1

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E1

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

Ef

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

NO2

154

K3

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E3

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment O2 - NO2-NO2-Catalytic O2 K1

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E1

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

Ef

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

NO2 K3-K4

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E3-E4

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

NO2- Catalytic K5

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table

FIRE BOOST Aftertreatment

155

4. FIRE Aftertreatment option to specify individual values for each coating section. E5

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

4.1.5.4.2. Catalytic Wall Reactions The different reactions can be enabled/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. The string "all" means that a certain reaction is activated in all PF Coating Sections, but it is also possible to replace "all" with specific coating section numbers separated by commas (e.g. "1,3,4"). 4.1.5.4.2.1. CO, HC and NO Oxidation R1: CO Oxidation

R2: C3H6 Oxidation

R3: C3H8 Oxidation

156

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section. R4: NO Oxidation

K

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism (see Section TWC Catalyst Reactions page [78] ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism (see Section TWC Catalyst Reactions page [78] ). The user can choose the table option to specify individual values for each coating section.

4.1.5.4.2.2. Selective Catalytic Reduction R1-R2: NH3 Adsoprtion, Desorption

NH3 Storage Capacity

Determines the maximum amount of ammonia that can be stored at the solid surface site (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

Initial Surface Coverage Fraction of NH3

Determines the coverage fraction of NH3 at the solid surface. This property can be specified as constant value or as function of the catalyst length. The user can choose the table option to specify individual values for each coating section. Typical Values & Ranges: 0-1[-]

Coverage Determines a surface coverage dependency in Dependency the pre-defined ad-/desorption mechanisms (see (epsilon) Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section. Typical Values & Ranges: 0-1[-] Max Surface Coverage Fraction of NH3

Determines the maximum surface coverage fraction of NH3 at the solid surface. This property can be specified as constant value or as function of temperature. The user can choose the table option to specify individual values for each coating section.

NH3 Surface Coverage Fraction Dependency m

Determines the adsorption rate dependence of the NH3 surface coverage fraction. The user can choose the table option to specify individual values for each coating section.

K1 - K2

Determine frequency factors used in the predefined ad/desorption mechanisms (see Section HSO-SCR Catalyst Reactions, Transient Approach

FIRE BOOST Aftertreatment

157

4. FIRE Aftertreatment page [83]

). The user can choose the table option to specify individual values for each coating section.

R3: NO Reduction

R4: NOx Reduction

R5: NO2 Reduction

158

E1 - E2

Determine the activation temperatures used in the pre-defined ad-/desorption mechanisms (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

Critical Surface Coverage

Determines a tuning factor that slows down the reaction rate above a critical surface coverage (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the predefined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

Critical Surface Coverage

Determines a tuning factor that slows down the reaction rate above a critical surface coverage (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the predefined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

Critical Surface Coverage

Determines a tuning factor that slows down the reaction rate above a critical surface coverage (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment option to specify individual values for each coating section.

R6: NH3 Oxidation (Transient Approach)

K

Determines the frequency factor used in the predefined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the pre-defined transient oxidation mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient oxidation (see Section HSOpage SCR Catalyst Reactions, Transient Approach [83] ). The user can choose the table option to specify individual values for each coating section.

R7: NH3 Oxidation K (Steady-State Approach)

Determines the frequency factor used in the predefined power-law oxidation mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-power-law transient oxidation (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

R8: NO Oxidation

Rate Approach 1 K

Determines the frequency factor used in the pre-defined transient and reversible power-law conversion mechanism (see Section HSO-SCR page [83] Catalyst Reactions, Transient Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient and reversible power-law conversion mechanism (see Section HSO-SCR page [83] Catalyst Reactions, Transient Approach ).

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4. FIRE Aftertreatment The user can choose the table option to specify individual values for each coating section. A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism see Section HSO-SCR Catalyst page [83] Reactions, Transient Approach ). The user can choose the table option to specify individual values for each coating section.

Rate Approach 2

R9: NO2 Formation

K, KR

Determine the frequency factors used in the pre-defined transient and reversible power-law conversion mechanism, respectively (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

E, ER

Determine the activation temperatures used in the pre-defined transient and reversible power-law conversion mechanism, respectively (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

A, AR

Determine the temperature dependencies used in the pre-defined transient and reversible power-law conversion mechanism, respectively (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

m

Modifies the NH3 dependency. The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the predefined power-law conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined power-law conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

4.1.5.4.2.3. Catalytic Outlet Channel Reactions page [156] The same reaction set as defined in the Catalytic Wall Reactions Model is selected. Sub-pages for the detailed specification of the reaction parameters appear. The user can choose the table option to specify individual values for each coating section.

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4. FIRE Aftertreatment 4.1.5.5. Reaction Solver Specification Select PF Reaction Solver Specification in the parameter tree to access the following input fields. 4.1.5.5.1. Reaction Solver Parameters Typical Values Regeneration reaction solver: max. no. of iterations

Specifies the maximum number of sub-iterations that the solver carries out for the catalytic reactions. Normally no changes are required.

20000 (-)

Regeneration reaction solver: relative tolerance

Specifies the relative tolerance for the solution of the reaction rate equation system. Normally no changes are required.

1e-05 (-)

Regeneration Specifies the absolute tolerance for the solution of the 1e-08 (-) reaction solver: reaction rate equation system. Normally no changes absolute tolerance are required. 4.1.5.5.2. General Settings Typical Values and Ranges Implicit DPF flow solution

Normally the PF flow solver and regeneration 0-100 (-) reactions are called once per time step at the beginning. Depending on the problem it can be useful to perform these calls more frequently, i.e. specify 5 th to call them every 5 iteration for large time steps. A value of 0 turns off implicit solver calls.

Scaling factor for The pressure drop calculation by the PF flow solver is 0.2-5 (-) dp underrelaxation separated from the CFD flow solution. The calculated pressure drop value is then impressed as source term in the momentum equation of the CFD flow solver. The scaling factor for dp underrelaxation enables to increase/decrease the underrelaxation of the pressure drop source. A value of 1 means that the default underrelaxation is used. Values greater than 1 increase, values less than 1 decrease the underrelaxation. Recommended values are in the range between 0.2 and 5. Refinement factor for DPF flow solution

Specifies the refinement factor of the PF flow solution. The PF flow solver is only called, if the changes of the flow conditions at the filter inlet since the last solver call exceed a certain tolerance value. By specifying a value greater than 1.0, this tolerance is reduced by the reciprocal of the refinement factor, and consequently the PF flow solver is called more often. This leads to smoother pressure curves, but increases simulation time.

0.2-10 (-)

4.1.5.5.3. Reaction Solver Flags Select Reaction solver flags in the parameter tree to access the following input fields.

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4. FIRE Aftertreatment Typical Values and Ranges On / Off

Activates/deactivates input flags. The 23 input fields are for AVL internal use only.

Off (default)

4.1.5.6. 2D Output Specification Select 2D Output Specification in the parameter tree to access the following input fields. 4.1.5.6.1. Substrate Data Typical Values and Ranges Mean DPF temperature

Activates/deactivates the output of the mean particulate filter temperature to the .fla file and to the .fl2 file.

Active (default)

Maximum DPF temperature

Activates/deactivates the output of the maximum particulate filter temperature to the .fla file and to the .fl2 file.

Active (default)

Minimum DPF temperature

Activates/deactivates the output of the minimum particulate filter temperature to the .fla file and to the .fl2 file.

Active (default)

Solid heat capacities

Activates/deactivates the output of the minimum, Inactive (default) maximum and mean value of the solid specific heat capacity (J/kgK) of the particulate filter to the .fla file and to the .fl2 file. Data is only written for temperature dependent values. Click on

Solid thermal conductivities

to define table data.

Activates/deactivates the output of the minimum, Inactive (default) maximum and mean value of the solid thermal conductivity (W/(m·K)) of the particulate filter to the .fla file and to the .fl2 file. Data is only written for temperature dependent values. Click on table data.

Gradient of solid temperature

to define

Activates/deactivates the output of the maximum and mean value of the solid temperature gradient (K/m).

Inactive (default)

4.1.5.6.2. Pressure Drop Typical Values and Ranges DPF pressure drop values

162

Activates/deactivates the output of all pressure drop Active (default) contributions (Pa) of the particulate filter to the .fla file and to the .fl2 file. The following data is written: • Overall DPF pressure drop • Converter pressure drop • Soot cake layer pressure drop • Soot depth layer pressure drop • Ash layer pressure drop • Wall pressure drop • Inlet pressure drop

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4. FIRE Aftertreatment • • • • •

Outlet pressure drop Inlet channel pressure drop Outlet channel pressure drop Inlet plug pressure drop Outlet plug pressure drop

4.1.5.6.3. Soot Typical Values and Ranges Total particle mass

Activates/deactivates the output of the total particle mass [kg] of the entire particulate filter to the .fla file and to the .fl2 file.

Inactive (default)

Specific particle mass

Activates/deactivates the output of the specific particle mass (g/l) of the entire particulate filter to the .fla file and to the .fl2 file.

Active (default)

Particle deposition rate

Activates/deactivates the output of the particle deposition rate [kg/s] of the entire particulate filter to the .fla file and to the .fl2 file.

Inactive (default)

4.1.5.6.4. Flow Uniformities Typical Values and Ranges Uniformity index

Activates/deactivates the output of the uniformity Inactive (default) index (-) of the particulate filter to the .fla file and to the .fl2 file. The definition of the uniformity index is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Centricity index

Activates/deactivates the output of the centricity index (-) of the particulate filter to the .fla file and to the .fl2 file. The definition of the centricity index is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Max./Min. inlet velocities

Activates/deactivates the output of minimum and the Inactive (default) maximum inlet velocity (m/s), and the position of the maximum inlet velocity (m) of the particulate filter to the .fla file and to the .fl2 file. The max. and min. inlet velocity are determined in the last non-porous fluid cell layer in front of the particulate filter.

High and low speed inlet area

Activates/deactivates the output of high and low speed Inactive (default) inlet areas (-) of the particulate filter to the .fla file and to the .fl2 file. The definition of the high and low speed inlet areas are described in the 2D results of the catalyst in section 2D page [139] Output Specification .

Tangential inlet velocity

Activates/deactivates the output of the mean, the Inactive (default) minimum, and the maximum tangential velocity (m/s) of

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Inactive (default)

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4. FIRE Aftertreatment the particulate filter inlet to the .fla file and to the .fl2 file. The tangential inlet velocity is described in the 2D results of the catalyst in section 2D Output page [139] Specification . Tangential inlet Activates/deactivates the output of the mean, the pressure gradient minimum, and the maximum tangential pressure gradient [Pa/m] of the particulate filter inlet to the .fla file and to the .fl2 file. The tangential inlet pressure gradient is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Inactive (default)

Gas hourly space Activates/deactivates the output of the gas hourly velocity (GHSV) space velocity at operation conditions (GHSV) (1/h) and the gas hourly space velocity at norm conditions (GHSVn) (1/h) of the particulate filter to the .fla file and to the .fl2 file. The definition of the GHSV is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Inactive (default)

4.1.5.6.5. Conversions Typical Values and Ranges Species conversions

Activates/deactivates the output of the species' conversions to the .fla file and to the .fl2 file. The species conversion is described in the 2D results page of the catalyst in section 2D Output Specification [139] .

Active (default)

Excess oxygen ratio at inlet

Activates/deactivates the output of the excess oxygen Inactive (default) ratio at the inlet to the .fla file and to the .fl2 file. The excess oxygen ratio is described in the 2D results of page [139] the catalyst in section 2D Output Specification

Redox ratio at inlet

Activates/deactivates the output of the redox ratio at the inlet to the .fla file and to the .fl2 file. The redox ratio is described in the 2D results of the catalyst in page [139] section 2D Output Specification

Inactive (default)

4.1.5.6.6. Filter flow model 2D results Typical Values and Ranges Filter flow model 2D results

If On/Off is selected, FIRE writes (for a given row number and a given output frequency) the results of the PF flow model as column data to ASCII files:

Off (default)

Output frequency (time steps)

50

Row number (particulate filter)

5

column no. data 164

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E.g.:

4. FIRE Aftertreatment 1 axial coordinate (m) 2 wall velocity (-) 3 V1 (m/s) 4 V2 (m/s) 5 h_soot (m) 6 Gas temperature (K) 7 Solid temperature (K) 8 Cell number

4.1.6. Reactive Porosity Specification To add a reactive porosity (RPOR) to the project, click on Aftertreatment TNG in the parameter tree with the right mouse button and select Reactive Porosity: Insert from the submenu. To delete a RPOR from the project, click on the name of the RPOR (i.e. RP[1]) with the right mouse button and select Remove from the submenu. The specification of a reactive porosity comprises data over its geometry, its fluid and thermodynamic behavior and the conversion reactions taking place. Figure 47. Reactive Porosity Specification Parameter Tree

Copy from RPOR allows the complete set of input data to be copied from RPOR[X] to the present reactive porosity. Figure 48. Copy from RPOR Function

4.1.6.1. General Reactive Porosity Specification Select RPOR specification in the parameter tree to access the following input fields. 4.1.6.1.1. Reactive Porosity Specification Typical Values and Ranges Cell selection

Supply a cell selection that defines the geometry NoSelection of the reactive porosity. (default)

Mesh requirements fulfilled

Specify if the mesh requirements for the RPOR cell selection which are summarized in section page [175] Mesh Requirements are fulfilled or not. The options available are: Yes and NO.

Yes (default)

Specified inlet/outlet of reactive porosity

Select this option for directed porosities. This option enables the user more heat and mass transfer models for selection including those are available for catalysts. Also, enables specification of an inlet and outlet face selection for additional 2D output.

Active (default)

Inlet face selection

If the geometry allows it, supply a face selection that defines the inlet plane of the reactive

NoSelection (default)

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4. FIRE Aftertreatment porosity. Only available for activated Specified inlet/outlet of reactive porosity. Outlet face selection

If the geometry allows it, supply a face selection that defines the outlet plane of the reactive porosity. Only available for activated Specified inlet/outlet of reactive porosity.

NoSelection (default)

RPOR initialization temperature

Determines the initial temperature of the reactive porosity.

293.15-1500 (K)

4.1.6.1.2. Reactive Porosity Type Typical Values and Ranges Fluid volume fraction (porosity)

Determines the fluid volume fraction (=porosity) of the RPOR porosity block.

0.1-0.95 (-)

Geometric surface area (GSA)

Determines the geometric surface area.

100-10000 (m / 3 m )

2

4.1.6.2. Pressure Drop Specification 4.1.6.2.1. Pressure Drop Models Two different pressure drop models and a user access are available to calculate the pressure drop within the RPOR block which is an undirected porosity. 4.1.6.2.1.1. Forchheimer If Forchheimer is chosen as pressure drop model, the pressure gradients within the reactive porosity are calculated with following equation (335)

The linear term and the quadratic terms take into account the viscous and the inertial losses, respectively, of the flow through the reactive porosity. Pressure gradient within porous material 2

i

Viscous loss coefficient (x-, y- and z-components) (1/m ) 2

Molecular (laminar) dynamic viscosity of domain fluid (N·s/m ) wi

Interstitial (local) velocity components in porous medium according to the local volume-fraction Inertial loss coefficient (x-, y- and z-components) (1/m) Domain fluid density

To activate the Forchheimer pressure drop model, select Forchheimer from the Pressure drop model pull-down menu to access the following input fields: Typical Values and Ranges 166

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4. FIRE Aftertreatment Zeta-value

This specifies the direction dependent parameters ( ) 0-100 (1/m) defining the dependency between the velocity and the pressure loss per unit length of porous material.

Alpha value

This specifies the direction dependent parameters ( i) 0-10 (1/m ) defining the dependency between the velocity in the i direction, the laminar viscosity, and the pressure loss per unit length of porous material.

7

2

4.1.6.2.1.2. Carman-Kozeny If Carman-Kozeny is chosen as pressure drop model, then the pressure gradients within the reactive porosity is calculated with following equation (336)

CCK is the Carman-Kozeny constant usually 150, is the molecular dynamic viscosity of domain 2 fluid in (N·s/m ), ui is the superficial and wi is the interstitial velocity in (m/s), is the fluid volume fraction (porosity) in (-), and dp is the equivalent solid particle diameter. To activate the Carman-Kozeny pressure drop model, select Carman-Kozeny from the Pressure drop model pull-down menu to access the following input fields: Typical Values and Ranges Model constant C1 Specifies the Carman-Kozeny constant.

0-1500 (-)

Equivalent particle Specifies the diameter of an equivalent solid sphere diameter for calculating the pressure drop.

0.0001-0.005 (m)

4.1.6.2.1.3. User If User is chosen as pressure drop model, the pressure drop is calculated according to the coding in the user routine usepor_pres.f. 4.1.6.2.2. Turbulence Treatment Within the interstices of the porosity the turbulence kinetic energy k is calculated by the standard transport equation. To take into account the laminarization process within the pores, the dissipation rate is calculated from the algebraic equation shown below: (337)

Crel is a relative turbulent length scale, which is multiplied with the hydraulic pore diameter dhyd and estimates the turbulence characteristics inside the porosity block. Crel is a problem dependent quantity which has to be specified by the user. Typical Values and Ranges Rel. turb. length scale Crel

Relative turbulent length scale Crel in equation page [167] Eq.337 to estimate the turbulence characteristics within the pores of the block.

0.0001-0.02 (-)

Hydraulic pore diameter dhyd

Hydraulic pore diameter dhyd in equation Eq.337 [167] to estimate the turbulence characteristics within the pores of the block.

page

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0.0001-0.005 (m)

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4. FIRE Aftertreatment 4.1.6.3. Physical Properties of Reactive Porosities Select RPOR Physical Properties in the parameter tree to access the following input fields. 4.1.6.3.1. RPOR Physical Properties Typical Values and Ranges Density

Determines the density of the reactive porosity material.

Thermal conductivity

Determines the thermal conductivity of 0.1-50 (W/(m·K)) the reactive porosity material. The thermal conductivity can either be specified as a constant value or as a table where the value changes as a function of temperature. Click on table data.

Specific heat

to define

Determines the specific heat of the reactive 500-2000 (J/ porosity material. The specific heat can either be (kg·K)) specified as a constant value or as a table where the value changes as a function of temperature. Click on

Anisotropic cond. Factor

400-2000 (kg/ 3 m )

to define table data.

Corrects the diffusion coefficients of the solid 0-10 (-) temperature equation normal to a preferential block direction. The default value of 1.0 means that there is no preferential block direction. This is reasonable for packed beds, granulated materials, etc. However, for blocks with preferential flow direction one can specify an anisotropic conductivity factor different from 1. Then the thermal conductivity matrix is calculated so that there is different thermal diffusion between block direction and the direction normal to the block direction. The preferential block direction vector is calculated from the center points of inlet and outlet face selection. (Inlet and outlet face selections have to be specified).

4.1.6.3.2. Mass Transfer Models 4.1.6.3.2.1. Constant Constant values which have to be defined by the user are taken as mass transfer coefficients. Typical Values and Ranges Mass transfer coefficient

Constant value of the species mass transfer coefficient.

4.1.6.3.2.2. VDI Packed Bed The VDI packed bed correlation is used to calculate mass transfer coefficients. 168

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0.1-10 (m/s)

4. FIRE Aftertreatment Typical Values and Ranges Equivalent particle Specifies the diameter of an equivalent solid sphere diameter of the granulated material.

0.0001-0.005 (m)

Shape factor mass Specifies the shape factor of the Sherwood number transfer for the mass transfer according to fe in section VDI page [30] Packed Bed .

1-2.1 (-)

4.1.6.3.2.3. User The user can specify the transfer coefficients in use_cattra.f. 4.1.6.3.3. Heat Transfer Models 4.1.6.3.3.1. Constant Constant values which have to be defined by the user are taken as heat transfer coefficients. Typical Values and Ranges Heat transfer coefficient

Constant value of the heat transfer coefficient.

2

5-500 (W/(m ·K))

4.1.6.3.3.2. VDI Packed Bed The VDI packed bed correlation is used to calculate heat transfer coefficients. Typical Values and Ranges Equivalent particle Specifies the diameter of an equivalent solid sphere diameter of the granulated material. Shape factor heat transfer

0.0001-0.005 (m)

Specifies the shape factor of the Nusselt number for 1-2.1 (-) the heat transfer according to fe in section VDI Packed page [30] Bed .

4.1.6.3.3.3. User The user can specify the transfer coefficients in use_cattra.f. 4.1.6.3.4. RPOR Segmentation FIRE provides a simple model to take into account perforations in the reactive porosities. The page [108] setup is the same as for catalysts explained in section Catalyst Segmentation . 4.1.6.3.5. External Heat Source FIRE allows to specify constant heat sources for arbitrary cell selections. The setup is the same page [108] as for catalysts explained in section External Heat Source . 4.1.6.4. Conversion Reactions FIRE offers the possibility to compute chemical reactions inside the reactive porosity. Either no reactions are taken into account or the application of user defined models is possible. 4.1.6.4.1. User Defined Kinetic Reactions The specification of the user defined kinetic reactions is identical to that of the catalyst described page [131] in section User Defined Reactions (Without Archive) .

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4. FIRE Aftertreatment 4.1.6.5. Reactive Porosity Reaction Solver Specification Select RPOR Reaction Solver Specification in the parameter tree to access the following input fields. 4.1.6.5.1. Reaction Solver Parameters Typical Values Reactive porosity solver: max. number of iterations

Specifies the maximum number of sub-iterations that the solver carries out for the catalytic reactions. Normally no changes are required.

20000 (-)

Reactive porosity solver: relative tolerance

Specifies the relative tolerance for the solution of the reaction rate equation system. Normally no changes are required.

1e-05 (-)

Reactive porosity solver: absolute tolerance

Specifies the absolute tolerance for the solution of the 1e-08 (-) reaction rate equation system. Normally no changes are required.

4.1.6.5.2. General Settings Typical Values and Ranges Implicit solution of Normally the reaction rate equation system is solved chem. kinetics at the beginning of a time step. Depending on the problem (i.e. chemical equilibrium problems) it can be necessary to solve it within the time step also, i.e. th specify 5 to solve it every 5 iteration for large time steps. A value of 0 turns off implicit solver calls. Reaction solver block size

0-100 (-)

In order to speed up the solution of the chemical 1-50 (-) kinetics, the corresponding equation system is not solved for each cell separately but more cells are considered for each solver call. The number of cells is given here.

Consider enthalpy Activates/deactivates the consideration of the sources from enthalpy sources from the catalytic reactions in the chemical reactions enthalpy equation for the solid material ('isothermal'). If deactivated, only the species sources from the catalytic reactions are considered.

Active (default)

Activate user Activates/deactivates the user function Inactive (default) model for use_catmod.f. This user function is called by the catalytic reactions CFD solver instead of the RPOR reaction model. Here (use_catmod.f) the user defines the source terms for the species transport equations and the enthalpy equation. It is typically used by advanced users who have their own models available and need full flexibility for their implementation. Please contact FIRE support for more information on use_catmod.f.

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4. FIRE Aftertreatment 4.1.6.6. Spray Particle Interaction Select Spray particle interaction in the parameter tree. If the Spray module is deactivated, the button Activate is greyed out, otherwise one clicks on Activate to access the following input fields. 4.1.6.6.1. Collision Typical Values and Ranges O'Rourke based

Selects the spray-porosity collision submodel based On (default) on the O'Rourke spray particle-particle collision model

User

Selects a user-defined spray-porosity collision submodel. The user submodel must be coded in the user function cyuse_rpor.f

Off (default)

Collision factor

Specifies the user-defined collision factor c. The higher the value is, the more probable a dropletporosity collision is.

1 (-) (default)

4.1.6.6.2. Interaction with solid Typical Values and Ranges Kuhnke based

Selects the spray-porosity interaction submodel based on the Kuhnke spray-wall interaction model.

On (default)

User

Selects a user-defined spray-wall interaction submodel. The user submodel must be coded in the user function cyuse_rpor.f

Off (default)

Maximum deviation angle

Specifies the maximum deviation angle max from the gas direction that a particle can undergo after a collision with the solid part of the porous medium.

65-85 (deg)

Number of secondary droplets

Specifies the number of secondary droplets ns generated after a splashing of a particle on the solid part of the porous medium.

2-4 (-)

4.1.6.6.3. Enhancement of evaporation Typical Values and Ranges Enhancement factor

Specifies the multiplication factor used for the evaporation massflow of each component.

1-5 (-)

Energy redistribution factor

Specifies the factor e used in the redistribution of 2-6 (-) the energy sink required to evaporate the liquid spray. The higher the factor is, the more energy is extracted from the solid for the evaporation.

4.1.6.7. 2D Output Specification Select 2D Output Specification in the parameter tree to access the following input fields.

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4. FIRE Aftertreatment 4.1.6.7.1. Substrate Data Typical Values and Ranges Mean porosity temperature

Activates/deactivates the output of the mean porosity temperature to the .fla file and to the .fl2 file.

Active (default)

Maximum porosity temperature

Activates/deactivates the output of the maximum porosity temperature to the .fla file and to the .fl2 file.

Active (default)

Minimum porosity temperature

Activates/deactivates the output of the minimum porosity temperature to the .fla file and to the .fl2 file.

Active (default)

Solid heat capacities

Activates/deactivates the output of the minimum, maximum and mean value of the solid specific heat capacity (J/(kg·K)) of the RPOR to the .fla file and to the .fl2 file. Data is only written for temperature

Inactive (default)

dependent values. Click on Solid thermal conductivities

Activates/deactivates the output of the minimum, Inactive (default) maximum and mean value of the solid thermal conductivity (W/(m·K)) of the RPOR to the .fla file and to the .fl2 file. Data is only written for temperature dependent values. Click on

Gradient of solid temperature

to define table data.

to define table data.

Activates/deactivates the output of the maximum and mean value of the solid temperature gradient (K/m).

Inactive (default)

4.1.6.7.2. Pressure Drop Typical Values and Ranges Pressure drop of reactive porosity

Activates/deactivates the output of the total pressure Active (default) drop (Pa) of the RPOR to the .fla file and to the .fl2 file. Output is only available if Specified inlet/outlet of reactive porosity is active.

4.1.6.7.3. Flow Uniformities Typical Values and Ranges

172

Uniformity index

Activates/deactivates the output of the uniformity index Inactive (default) (-) of the RPOR to the .fla file and to the .fl2 file. Output is only available if Specified inlet/outlet of reactive porosity is active. The definition of the uniformity index is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Centricity index

Activates/deactivates the output of the centricity index (-) of the RPOR to the .fla file and to the .fl2 file. Output is only available if Specified inlet/outlet of reactive porosity is active.

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Inactive (default)

4. FIRE Aftertreatment The definition of the centricity index is described in the 2D results of the catalyst in section 2D Output page [139] Specification . Max./Min. inlet velocities

Activates/deactivates the output of minimum and the Inactive (default) maximum inlet velocity (m/s), and the position of the maximum inlet velocity (m) of the RPOR to the .fla file and to the .fl2 file. The max. and min. inlet velocity are determined in the last non-porous fluid cell layer in front of the RPOR. Output is only available if Specified inlet/outlet of reactive porosity is active.

High and low speed inlet area

Activates/deactivates the output of high and low speed Inactive (default) inlet areas (-) of the RPOR to the .fla file and to the .fl2 file. Output is only available if Specified inlet/ outlet of reactive porosity is active. The definitions of the high and low speed inlet areas are described in the 2D results of the catalyst in page [139] section 2D Output Specification .

Tangential inlet velocity

Activates/deactivates the output of the mean, the minimum, and the maximum tangential velocity (m/s) of the RPOR inlet to the .fla file and to the .fl2 file. Output is only available if Specified inlet/outlet of reactive porosity is active. The tangential inlet velocity is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Inactive (default)

Tangential inlet Activates/deactivates the output of the mean, the pressure gradient minimum, and the maximum tangential pressure gradient (Pa/m) of the RPOR inlet to the .fla file and to the .fl2 file. Output is only available if Specified inlet/outlet of reactive porosity is active. The tangential inlet pressure gradient is described in the 2D results of the catalyst in section 2D Output page [139] Specification .

Inactive (default)

Gas hourly space Activates/deactivates the output of the gas hourly Inactive (default) velocity (GHSV) space velocity at operation conditions (GHSV) (1/h) and the gas hourly space velocity at norm conditions (GHSVn) (1/h) of the RPOR to the .fla file and to the .fl2 file. Output is only available if Specified inlet/ outlet of reactive porosity is active. The definition of the GHSV is described in the 2D results of the catalyst in section 2D Output page [139] Specification . 4.1.6.7.4. Conversions Typical Values and Ranges Species conversions

Activates/deactivates the output of the species' Active (default) conversions to the .fla file and to the .fl2 file. Output is only available if Specified inlet/outlet of reactive porosity is active.

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4. FIRE Aftertreatment The species conversion is described in the 2D results page of the catalyst in section 2D Output Specification [139] . Surface coverage Activates/deactivates the output of the mean surface fraction coverage fractions (-) of the surface species of the RPOR to the .fla file and to the .fl2 file.

Inactive (default)

Excess oxygen ratio at inlet

Activates/deactivates the output of the excess oxygen Inactive (default) ratio at the inlet to the .fla file and to the .fl2 file. The excess oxygen ratio is described in the 2D results of page [139] the catalyst in section 2D Output Specification . Output is only available if Specified inlet/outlet of reactive porosity is active.

Redox ratio at inlet

Activates/deactivates the output of the redox ratio at Inactive (default) the inlet to the .fla file and to the .fl2 file. The redox ratio is described in the 2D results of the catalyst in page [139] section 2D Output Specification . Output is only available if Specified inlet/outlet of reactive porosity is active.

4.1.7. 3D Output Specification Select 3D Output Specification in the parameter tree to access the following input fields. 4.1.7.1. Standard Typical Values and Ranges Monolith temperature

Activates/deactivates the output of the monolith temperature.

Active (default)

Surface coverage fraction

Activates/deactivates the output of the surface coverage fraction.

Active (default)

4.1.7.2. Extended Typical Values and Ranges

174

Heat transfer coefficients

Activates/deactivates the output of the heat transfer coefficient.

Inactive (default)

Solid heat capacity

Activates/deactivates the output of the specific solid heat capacity.

Inactive (default)

Solid thermal conductivity

Activates/deactivates the output of the solid thermal conductivity.

Inactive (default)

Mass transfer coefficients

Activates/deactivates the output of the mass transfer coefficients for each species.

Inactive (default)

Rates of user defined chemical reaction

Activates/deactivates the output of the rates for each user defined reaction.

Inactive (default)

Production/ depletion rates of chemical species

Activates/deactivates the output of the reaction rates for each species.

Inactive (default)

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4. FIRE Aftertreatment Tangential inlet velocity

Activates/deactivates the output of the velocity Inactive (default) components perpendicular to the monolith direction. The tangential velocity is plotted only in the fluid layer in front of the monolith inlet.

Tangential inlet pressure gradient

Activates/deactivates the output of the pressure gradient in the direction perpendicular to the monolith direction. The tangential pressure gradient is plotted only in the fluid layer in front of the monolith inlet.

Inactive (default)

Gradient of solid temperature

Activates/deactivates the output of the solid temperature gradient.

Inactive (default)

4.1.7.3. Washcoat Layer The washcoat layer (WCL) model is available for catalysts only. Note: 3D WCL results are plotted for every specified washcoat layer depth (YdPos). This may lead to a huge number of results and large result files. Typical Values and Ranges WCL Mole Fraction

Activates/deactivates the output of the species' mole fractions for all cells over all washcoat layers

Inactive (default)

WCL Mass Fraction

Activates/deactivates the output of the species' mass fractions for all cells over all washcoat layers

Inactive (default)

WCL Species Concentration

Activates/deactivates the output of the species' concentrations for all cells over all washcoat layers

Inactive (default)

WCL Effective Diffusion Coefficient

Activates/deactivates the output of the species' effective diffusion coefficients for all cells over all washcoat layers

Inactive (default)

WCL Species Rate

Activates/deactivates the output of the species rates in each cell of the washcoat layer.

Inactive (default)

WCL Reaction Rate

Activates/deactivates the output of the reaction rates for all activated reactions in each cell of the washcoat layer.

Inactive (default)

WCL Stored Species Fraction

Activates/deactivates the output of the stored species fraction in each cell of the washcoat layer.

Inactive (default)

WCL Stored Species Loading

Activates/deactivates the output of the stored species loading in each cell of the washcoat layer.

Inactive (default)

4.1.8. Mesh Requirements and MPI Decomposition 4.1.8.1. Mesh Requirements In aftertreatment simulations the cell selections for the catalyst, the reactive porosity (RPOR) and the particulate filter are defined internally as porosity blocks. It is no longer necessary (since FIRE v8.5) to activate the Porosity module in the GUI. Nevertheless, some mesh requirements have to be taken into account:

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4. FIRE Aftertreatment 4.1.8.1.1. Mesh Requirements for Catalyst and Particulate Filter The flow through a catalyst or a particulate filter is determined by the channel shaped structure of the monolith. Thus, the monolith is modeled as directed porosity for which the following mesh requirements have to be taken into account: • Arbitrary interfaces are not allowed within the porosity (catalyst or particulate filter) blocks. • The distance between arbitrary interfaces and the porosity/fluid interfaces must be at least two cell layers (see the following figure). • The catalyst or the particulate filter block must be a structured, direction-aligned grid. Porosity/fluid interfaces must be plane and normal to the porosity direction. Figure 49. Mesh Requirements for Catalysts and Particulate Filters

4.1.8.1.2. Mesh Requirements for Reactive Porosities In general there is no preferential flow direction in reactive porosities. Thus, they are modeled by undirected porosities for which the Mesh Requirements can be set to Yes (=fulfilled) or No (=not fulfilled). For not fulfilled mesh requirements no special treatment is necessary. For fulfilled mesh requirements the following conditions must be taken into account: • The distance between arbitrary interfaces and porosity/fluid interfaces must be at least two cell layers. • The face selection determining the porosity/fluid interface must be a smooth surface without protruded cells. However, it is recommended to create computational grids with fulfilled mesh requirements whenever possible. 4.1.8.2. MPI Decomposition 4.1.8.2.1. MPI Decomposition for Catalyst In general the computational effort for catalyst cells is higher than that for ordinary fluid cells. In addition to the transport equations, the chemical reactions and the solid temperature equation have to be solved for the porous cells of the catalyst. To achieve a good load balance in MPI simulations, FIRE offers the capability of weighted MPI decomposition. This means that if the user specifies a cell selection with the name "_decomp_weight_", then instead of the ordinary cell count, the cell count for the generated MPI domains is determined by the factor specified at . The weight must be an integer greater than 0. For all cells outside such cell selections, a weight of 1 is assigned. For example, if there is a cell selection specified with the name "CAT01_decomp_weight_3", during the MPI decomposition the cells contained by this selection have the weight 3, while the cells outside of this selection have the weight 1. For catalysts it is recommended to apply the weighting to all cells of the porous block. The quantity of the weighting factor depends on the setup of the simulated case, i.e. how many chemical reactions are active, how often the reaction solver is called (see Implicit solution of page [138] chem. kinetics in section Reaction Solver Parameters ), etc. For many cases a weighting factor of 3 seems to be a good choice.

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4. FIRE Aftertreatment Note: Any "_indivisible" or "_domain_"-selections and arbitrary-interface-cell-layers are processed afterwards. 4.1.8.2.2. MPI Decomposition for Particulate Filter Contrary to the catalyst selection the MPI decomposition of PF blocks is not arbitrary. The MPI interface must be aligned along the porosity block direction. This means that the PF cell rows in porosity direction (representing a certain number of PF channels) must not be located on different domains. Note: The MPI decomposition of PF blocks is not arbitrary. To avoid PF channels splitting onto different domains, the decomposition must be topologically normal to the front surface of the PF. By specification of "_domain_"-selections one can influence the MPI decomposition. The following figure shows the specification of the selections for the domain decomposition of a simulation with 4 CPUs. Figure 50. Example of Manual Domain Decomposition of a PF for 4 CPUs

If the cell selections are specified in that way, PF channels are not distributed onto more than one domain and the decomposition requirement for PF is fulfilled. The names of the selections are composed by the selection name plus the domain extensions "_domain_X" starting at index zero (e.g. mesh_domain_0, mesh_domain_1, mesh_domain_2, mesh_domain_3,..). This method is sophisticated and leads to an excellent load balance, since the user specifies exactly on which domain which PF channel row is calculated. However, the creation the cell selections may be circuitous, and if one changes the number of processors of the simulation, one has to create new selections. Therefore, FIRE offers a more convenient way for the domain decomposition. If face-selections with the names "_decomp_struct_front_" and "_decomp_struct_end" are found, then they are considered as the front and back sides of a structured cell-block, where the decomposition is performed only topologically normal to the front surface. If there is no "_decomp_struct_end" face selection, the structured block ends at the mesh boundary or as soon as a non-sweepable cell is encountered, the suffix specifies the cell count weighting factor, similar to that already described in section MPI Decomposition for page [176] Catalyst for the catalysts. The specified weight is assigned to the cells in the structured block. If no specific weight will be assigned, the suffix can be omitted. The prefix may be any name, but any "decomp_struct_end"-selection must have the same prefix as the corresponding "decomp_struct_front"-selection. An arbitrary number of such "decomp_weight"- or "decomp_struct_front"-selections may exist, but the structured cell-blocks must not overlap. Also here, any "_indivisible" or "_domain_"-selections and arbitrary-interface-cell-layers are processed afterwards. The quantity of the weighting factor depends on the set-up of the PF model, i.e. if there are chemical reactions active or not and if yes, how many chemical reactions are active, which PF

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4. FIRE Aftertreatment models are active (Depth filtration), etc. For many cases a weighting factor of 2 seems to be a good choice. The following figure shows an example of the face selections applied for weighted decomposition. The prefix "DEC_DPF_0" and the suffix "2" determine the names of the front and backside selections "DEC_DPF_0_decomp_struct_front_2" and "DEC_DPF_0_decomp_struct_end". For correct decomposition, these selections are located one cell layer before and after the PF block. Figure 51. Face Selections for Weighted MPI Decomposition of a PF

4.1.9. Aftertreatment-Device Import from BOOST To import Aftertreatment devices from BOOST, click on Aftertreatment in the parameter tree with the right mouse button, select Import from BOOST from the submenu and choose the corresponding .bwf file. After the import function is executed, all Aftertreatment devices (Catalysts and Particulate Filters) from the chosen BOOST project are added to the FIRE Case. If only one of multiple Aftertreatment devices specified in the BOOST project is needed, the redundant devices can be deleted from the project by clicking on the name of the catalyst or particulate filter with the right mouse button and selecting Remove from the submenu. Since the specification of Aftertreatment devices in the FIRE Solver GUI is not completely identical to the specification in the BOOST GUI, the following items have to be considered when using the Import from BOOST feature: • If more than one Case is specified in BOOST, the active one is chosen for the import. All parameters which are set in BOOST are resolved to values. • All imported values are highlighted orange. • All values which are not imported (i.e. the monolith cell selections with no corresponding entries in BOOST) are default (black) and have to be modified by the user. • Log files are written in the Case directory (ImportDataFromBoost_Match.log and ImportDataFromBoost_NO_Match.log), where the success of the data mapping procedure is recorded (Note: Quantities which are not imported because corresponding entries do not exist in BOOST, do not appear in the log file). • The highlighting of imported values disappears after saving the FIRE Project.

4.1.10. FIRE Aftertreatment User Functions

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use_catrat.f

This example shows how to program a user defined rate law (Langmuir-Hinshelwood kinetics for three-way catalyst). Refer to the User Functions Code Manual for details.

use_cattra.f

This example shows how to program a user defined calculation of mass and heat transfer coefficients in the catalyst. Refer to the User Functions Code Manual for details.

use_dpfrat.f

This example shows how to program a user defined rate law (Oxidation of soot (solid carbon) with oxygen to CO and CO2

FIRE BOOST Aftertreatment

4. FIRE Aftertreatment in the cake as well as in the depth layer. Refer to the User Functions Code Manual for details.

4.1.11. Homogenous Gas Phase Reactions - Input data The Homogenous Gas Phase Reactions chemistry interpreter needs a text based chemistry input file with an arbitrary name, where the stoichiometries of the reactions, the kinetic Parameters (A, b and E) and – optionally – auxiliary data are defined. The reaction specification part begins with 'REACTIONS' and ends with 'END'. The number of blanks or empty lines between specification blocks/lines is arbitrary. Comment lines beginning with '!' are allowed. Example for such a chemistry input file:

REACTIONS 2O+MO2+M 1.200E+17 -1.000 .00 H2/2.40/ H2O/15.40/ CH4/2.00/ CO/1.75/ CO2/3.60/ C2H6/3.00/ AR/ .83/ O+H+MOH+M 5.000E+17 -1.000 .00 H2/2.00/ H2O/6.00/ CH4/2.00/ CO/1.50/ CO2/2.00/ C2H6/3.00/ AR/ .70/ O+H2H+OH 3.870E+04 2.700 6260.00 END The chemistry interpreter reads this input file during the preprocessing and creates an Info file ('input_file_name'_out.dat in the input file directory) with the specified chemistry. Currently about 95% of the auxiliary-keywords known by the CHEMKIN-II Version 4.9, April 1994, DOUBLE PRECISION are considered by the interpreter. Therefore it is capable of reading and interpreting the corresponding chem.inp files.

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5. BOOST Aftertreatment

5. BOOST Aftertreatment In this section the application BOOST Aftertreatment is presented. General information about how to use the BOOST pre- and post-processor is available in the BOOST Users Guide and the IMPRESS Chart Users Guide. Aftertreatment examples are available on the installation media and described in the BOOST AT Examples Manual. A detailed step by step explanation of how to use BOOST Aftertreatment Analysis is available in the BOOST Aftertreatment Primer and on the installation media. Note: The values and ranges specified in the right column of all tables in this chapter are taken for 'typical' automotive applications. Its purpose is to give the user an idea in which range the considered value lies. The application of data outside this range is additionally checked by the GUI for physical reasonability. The aftertreatment simulation can be performed either completely decoupled from any BOOST cycle simulation or as an integrated part of a BOOST model as shown in the following figures.

Catalytic Converter Model

Particulate Filter Model

Pipe Model

Combined Exhaust System Model: Pipe, DOC, Pipe, DPF, Pipe and SCR

Figure 52. BOOST Aftertreatment Models Figure 53. BOOST Cycle Simulation Model with Aftertreatment Analysis Simulation

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5. BOOST Aftertreatment The aftertreatment connection visualizes the connection of aftertreatment elements (catalytic converter or particulate filter) with aftertreatment boundary conditions. It does not feature any specific data of its own. An arbitrary number of catalytic converters, particulate filters and pipes can be linked with aftertreatment connections to aftertreatment boundary conditions. Using these elements a complete aftertreatment analysis model is specified.

5.1. Input Data This section explains how the input data can be generated within BOOST.

5.1.1. Aftertreatment Solver For every BOOST Aftertreatment simulation general run information like for example simulation time and results writing as well as solver options have to be specified. This input data and the available ATM Solver output and databus channels are discussed in the following sub-sections: 5.1.1.1. Run Information Run information is defined in Simulation | Control, which can be accessed directly via the button . Different BOOST simulation tasks are available – the Aftertreatment Analysis toggle switch should be activated to run simulations in aftertreatment analysis mode. In this case the transient behavior of the catalyst is simulated. The specification of the aftertreatment simulation is located in the global tree element Aftertreatment Analysis as shown in the following figure. Figure 54. Aftertreatment Analysis - General Simulation Control

The following data concerning the integration horizon is required: Typical Values and Ranges Start Time

Determines the beginning of the simulation and therefore start time of the integration.

0 (s)

End Time

Determines the end of the simulation and therefore the end time of the integration.

0-1800 (s)

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5. BOOST Aftertreatment Time Step

Determines the interval for the stepwise integration. Note that larger time steps will increase the simulation speed but may lead to instabilities of the numerical procedure. Here it is recommended to specify the size of the time step according to the transient changing of the aftertreatment boundary conditions (section page [185] Boundary Conditions ). The time step may be variable, i.e. a table containing time step information may be set up. In this table, for different simulation periods, different time steps may be entered. The time steps entered here will be effective starting from the corresponding time. E.g. for a Variable Time Step Size table: Table 1: Time (X)

Time Step Size (Y)

0

0.5

60

5

0-End Time/30 (s)

the time step will be 0.5 s at the start of the simulation, and starting from second 60, a time step size of 5 s will be used for the rest of the simulation (i.e. the next output will be 65 s). Note: The values in the table will be interpreted as a step function (i.e. no interpolation between the values will take place). When employing the user-defined parameter ATM_PeriodicTimeSteps YES (see User Defined page [184] Parameters ) the data in the table will be interpreted as being periodic. In this case, the last entry in the table will only serve to mark the end of the period but its value will be ignored (when the new period begins, the first value in the table will be used instead). Output After ... Time Steps

Determines at which time step results of the simulation should be written to the results file. '1' each time step, '2' each second time step, ...

Use Enables the user to specify an external database Thermodynamic file for thermal gas properties. Please refer to the Property Database BOOST Users Guide for a detailed description of the expected input format. page [181]

1 (-)

-

As shown in Fig. 54 , the gas composition consisting of gaseous species and solid particles has to be specified. This is defined as global information since the gas flow links all elements considered in the aftertreatment simulation and therefore the number and type of any species has to be identical. The input of solid species is restricted to particulate filters since in the case of catalyst simulations any solid flows through without any impact or interaction. 182

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5. BOOST Aftertreatment The following species specifications are required: Typical Values Gas Composition

Determines the number and type of gas species transported through the system. The user can choose between 2 and 36 species from a popup menu. The list can be stored to an ASCII-file and also loaded from external files.

CO, CO2 O2, N2...

Solid Species

Determines the number and type of solid components transported by the gas flux. The species names can be chosen from a pulldown menu. The list can be stored to an ASCII-file and also loaded from external files.

C(s)

When the Engine A/F Ratio input at the inlet Aftertreatment Boundary is chosen (cf. section page [185] Boundary Conditions ), the reference fuel used for calculating emissions from the given Engine A/F Ratio needs to be specified by enabling Fuel Composition. In this case the following input is required: Typical Values C

Carbon content in fuel.

H

Hydrogen content in fuel.

O

Oxygen content in fuel.

The specification of the Homogenous Gas Phase Reactions, which can be considered in pipes page [181] and catalysts, is shown in Fig. 54 . The list of chemistry models is either typed in (by using the Insert/Remove options) or read in from an ASCII input file. For each chemistry model an arbitrary key (string) is defined. In the BOOST model a specific chemistry model is referred through this key. Typical Values Homogenous Gas Phase Reactions: Key

The key is an arbitrary string which is defined for each chemistry set. In the BOOST model a specific chemistry model is referred by this key.

e.g. CH4_autoignition

Homogenous Gas Phase Reactions: Chemistry

The file name of the chemistry set has to be specified here. The file has to be saved either in the Case or in the Project directory. More info about the format of such a chemistry input file can be found in Appendix Homogenous Gas Phase page [179] Reactions - Input data .

e.g. CH4_ignit.txt

The Restart Control section allows a restart file to be written during a simulation and/or a simulation to be restarted from an existing restart file: Typical Values Restart Simulation YES: Choose this option in order to run a restart simulation. This requires a valid restart file to be available. NO:

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5. BOOST Aftertreatment This is the standard mode for simulations. Write Restart File

Enable this option in order to write a restart file during the simulation: After Termination: A restart file is written after the simulation has been terminated by the user or due to a solver error (e.g. convergence error). After ... Time Steps: Two restart files are written in turn every ... time steps.

-

In the Solver Options section general solver settings can be set: Typical Values Enable HighRobustness Option

This option can lead to better performance especially in the simulation of numerically challenging models which show for example instability.

-

Tolerance Specify a factor in order to refine the default solver 0.1-100 Refinement Factor tolerances. Values > 1 lead to smaller tolerances (-) (more strict solver iteration abort criteria), and values < 1 lead to higher tolerances. Disable Result Writing

Choose this option in order to disable results collection and writing of gid files.

-

5.1.1.2. User Defined Parameters These can be used in order to supply the boost calculation kernel with additional input information. To do so, a Parameter Key and a corresponding Value may be specified. In this chapter, some user-defined parameters specific to BOOST Aftertreatment will be treated. For additional information about this feature please contact [email protected].

184

Parameter Key

Value

Description

ATM_AMEND_INPUT_TABLES

NO

Do not amend input tables which are missing a value at the simulation start time with a copy of the first given value, i.e. switch back to the old default behavior (default: YES, i.e. do take the first given value to be valid at the simulation start time in case its time is past the simulation start time; the new default behavior is useful when employing raw sensor data, which may be missing a value at t=0 s, which is usually the simulation's start time).

ATM_RUNNING_AVERAGE



Apply a running (moving) average to the input boundary tables using a window size of (> 1). For details and options, page [186] see Running Average

ATM_PeriodicTimeSteps

YES

Interpret user-defined variable time step page table as periodic data, see Time Step [182] .

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment Example The following figure shows the input of optional parameters. This page allows to specify model page [14] parameters in a general way. As shown, two values (see Eq.29 ) for the friction model of the catalyst are specified. If no optional parameter is set, the simulation uses its default settings. Figure 55. User Defined Parameters

5.1.2. Boundary Conditions In order to run an aftertreatment simulation in analysis-mode, aftertreatment boundary conditions (symbol ) at the inlet and at the outlet of the element have to be defined. At the inlet a mass flux and at the outlet a pressure has to be defined. In order to change the flow direction, negative mass fluxes at the inlet can be set. If no detailed information about the outlet conditions are given then the Adiabatic Backflow conditions can be chosen where no temperature and species mass fraction gradients are assumed. All boundary conditions either can be defined as constant values, or as tables where the boundary value changes as function of the time. Click on to define data in tables. Data can be entered directly in all input tables. If data is stored to a file it can be reloaded by providing the filename and path. The species composition can be defined as mass or mole fractions. At the inlet the following data is required: Typical Values and Ranges Temperature

Determines the temperature of the gas flux entering the aftertreatment element.

Inlet Flow Specification

Determine unit of inlet flow: • Mass Flux • Volume Flow

Mass Flux

Determines the mass entering the aftertreatment element. Negative values cause a change of the flow direction.

Volume Flow

Determines the gas volume entering the aftertreatment element. Negative values cause a change of the flow direction.

Gas Mass/Mole Fractions

Determines the mass or mole fractions of all the 0-1 (kg i /kggas) gas species defined. The sum of all mass fractions has to be '1'.

Solid Mass Fractions

Determines the mass flux of the solid species as a fraction of the gas mass flux. Soot, for example,

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300-1500 (K)

0 (kg/s) depends on the catalyst size

0-1 (kgs/kggas)

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5. BOOST Aftertreatment is required for the simulation of particulate filter loading. Engine A/F Ratio

The optional input of an inlet engine A/F ratio allows the calculation of selected emissions. For the following species the inlet gas fractions can be calculated from the given A/F ratio: CO2, H2O, O2 and N2. In addition, a species from the gas composition needs to be selected to which the correction of sum of fractions is applied. Note: Any value of one of the selected species is overruled by the calculated emissions. Note: A reference fuel needs to be specified in Simulation Control Aftertreatment Analysis (cf. page [181] section Run Information ).

If the Adiabatic backflow toggle switch is selected, only the outlet pressure is required: Typical Values and Ranges Pressure

Determines the pressure at the outlet of the aftertreatment element. In the case of negative flow directions this pressure has to be larger than the pressure loss of the element.

1-5 (bar)

If the Adiabatic backflow toggle switch is deselected (user-defined), the following data is required in addition to Pressure: Typical Values and Ranges Temperature

Determines the temperature of the gas flux entering the aftertreatment element in the case of a reversed flow direction.

300-1500 (K)

Gas Mass/Mole Fractions

Determines the mass or mole fractions of all the 0-1 (kg i /kggas) gas species defined in the case of reversed flow conditions. The sum of all mass fractions has to be 1.

Solid Mass Fractions

Determines the mass flux of the solid species as a fraction of the gas mass flux. This data is only required for particulate filter simulation in the case of a changed flow direction.

0-1 (kgs/kggas)

5.1.2.1. Running Average The data in the boundary input tables may be smoothed applying a running (moving) average method. This may improve solver stability in case of noisy input data. Generally speaking, the smoothed y values are calculated as a mean of the n y values inside the averaging window to be applied, and are centered between the first and the last time value of that averaging window. Since centering the time values would move the first and last given data point forward and backward in time, respectively, these end values are amended by default using the original first and last data points (this behavior may be turned off, although it is not recommended). Multiple averaging passes may be applied. Furthermore, the window size may be reduced by a given factor, in each subsequent pass. 186

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5. BOOST Aftertreatment Currently, this can be achieved by employing a user-defined parameter ATM_RUNNING_AVERAGE. The parameter has several options to control the smoothing procedure which are described in the following table. Parameter Key

Value

Description

ATM_RUNNING_AVERAGE



Apply a running (moving) average to the input boundary tables using a window size of . The method is only applied if is at least two.

PASSES



Number of sequential averaging passes (default: 1, i.e. one pass).

FACTOR



Factor by which to divide the averaging window in each subsequent pass (default: 1.0, i.e. do not change the window size in subsequent passes).

AMEND

NO

Do not amend the start and end points using the original data points (default: YES, i.e. do amend the end points).

NO

Turn off the running average method selectively for the given input table, where: PRESSURE: pressure (outlet boundary) TEMP: temperature MFRAC: species mass/mole fractions SFRAC: solid mass fraction INFLOW: mass/volume flux



Example: The User Defined Parameters table: Parameter Key

Value

ATM_RUNNING_AVERAGE

40

PASSES

3

FACTOR

1.3371

MFRAC

NO

PRESSURE

NO

would apply a three-pass running average with window sizes of 40, 30, and 22 points to all input tables, except for the species mass/mole fractions and the pressure tables, and amend the end points afterwards. Giving e.g. ATM_RUNNING_AVERAGE 20 as the only parameter would apply a one-pass running average with an averaging window of 20 points.

5.1.3. Catalyst The specification of the catalyst ( ) comprises data of its geometry, its fluid and thermodynamic behavior and the conversion reactions taking place. This input data is discussed in the following sub-sections:

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5. BOOST Aftertreatment 5.1.3.1. General In order to simulate the chemical processes in the catalyst - either heterogeneous or homogeneous reactions - the switch Chemical Reactions needs to be activated. As a consequence the input pages to define the required input for the single-channel converter model are activated as well. If deactivated, no chemical reactions can be modeled and default values will be considered for the numerical and physical properties for the single-channel converter model. Furthermore the basic geometry has to be defined by the following data: Typical Values and Ranges 3

Monolith Volume

Determines the volume of the monolith, comprising both, the volume of the gas phase and the solid substrate.

1-10 (dm )

Length of Monolith

Determines the length of the monolith.

0.1-0.5 (m)

Inlet Collector Volume

Determines the volume of the inlet cone. This information is only required for the Cycle Simulation task.

1 (dm )

Outlet Collector Volume

Determines the volume of the inlet cone. This information is only required for the Cycle Simulation task.

1 (dm )

Couple to upstream element

Select to thermally couple the catalyst to an upstream element via wall heat conduction (see page [75] Thermal Coupling for details).

-

Consider Air Gap between the Substrates

When deselected, thermal coupling to an upstream element's substrate (e.g. another catalyst or a particulate filter) is active. Select to suppress this thermal coupling (see Thermal page [76] Coupling (Substrates) for details).

-

3

3

Note: Relevant only when Couple to upstream element is active. 5.1.3.2. Initialization The monolith (solid phase) initial temperature can be defined by the user: Typical Values and Ranges Initial Solid Temperature

Determines the initial temperature of the solid substrate as constant or as a function of the catalyst length.

273-1000 (K)

5.1.3.3. Type Specification The cell structure of the monolith can either be defined assuming Squared Cell Catalysts in a simplified way or within any geometrical assumptions for General Catalysts. If Square Cell Catalyst is selected, the following input data has to be defined: Typical Values and Ranges

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5. BOOST Aftertreatment 2

Cell density (CPSI)

Determines the type of monolith using the 2 number of channels per in .

100-900 (1/in )

Wall Thickness

Determines the thickness of the monolith's walls.

0.006-0.015 (in)

If General Catalyst is selected, the following input data has to be defined: Typical Values and Ranges Open Frontal Area (OFA)

Determines the open frontal area (= fluid volume fraction) of monolith.

0.50-0.75 (-)

Hydraulic Diameter (Hydraulic Area)

Determines the hydraulic unit (diameter or area) of the monolith channels.

0.001-0.005 (m)

5.1.3.4. Friction The friction of the catalytic converter model can either be specified by Target Pressure Drop or by a friction Coefficient. If the catalyst is simulated in the aftertreatment analysis mode, only the specification of a friction coefficient can be used. For a standard BOOST cycle simulation both input variants can be used. If Target Pressure Drop is selected, the following data is required: Typical Values and Ranges Inlet Mass Flow

Determines the inlet mass flow, as reference value 0 (kg/s) for the evaluation of a friction coefficient. depends on the catalyst size

Inlet Temperature

Determines the inlet temperature, as reference value for the evaluation of a friction coefficient.

300 (K)

Inlet Pressure

Determines the inlet pressure, as reference value for the evaluation of a friction coefficient.

1 (bar)

Target Pressure Drop

Determines the pressure drop of the element as basis for the evaluation of a friction coefficient.

0.003 (bar)

For more detailed information about the input variant Pressure Drop refer to the BOOST Users Guide. If Coefficient is selected, the following input data is required: Typical Values and Ranges Laminar Coefficient a

Determines a laminar friction coefficient according page [14] to Eq.29 .

64 (-)

Laminar Coefficient b

Determines a laminar friction coefficient according page [14] to Eq.29 .

-1 (-)

Turbulent (Friction Determines a turbulent friction coefficient. The Coefficient) friction coefficient can be specified as constant or

0.01-0.04 (-)

table value (see typical values below). The latter value is defined as a function of the monolith length.

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5. BOOST Aftertreatment Friction Multiplier Channel Shape

Determines a dimensionless factor that considers 0.04-1 (-) the influence of the channel shape in the case of laminar flow. The multiplier either can be chosen for different channel geometries (see section BOOST Balance Equations, Single Channel Model page [13] ) or setup completely freely.

5.1.3.5. Discretization The required input of the discretization does not concern the physical situation of the catalyst, but is required in order to setup and 'tune' its numerical model. Typical Values and Ranges Model Dimension

Determines the dimension of the catalyst model. Here either 1D or 2D can be set. Note that for adiabatic radial heat loss conditions 2D models are page [191] reduced to 1D (refer to section Heat Loss ).

1D/2D

Axial Direction

Number of Grid Point: Determines the number of calculation cells in axial direction. Grid Shape Factor: Determines the allocation of the axial grid points. Values below 1 produce a grid which gets more dense toward the boundaries (according to a geometrical series), whereas values greater than 1 increase the grid density toward the middle of the catalyst.

10-100 (-) 0.8 (-)

If a 2D simulation is chosen, the following data should be set in addition to the radial direction: Typical Values and Ranges Radial Direction

Number of Channels: 2-7(-) Determines the number of channels located in radial direction 0.5 (-) Grid Shape Factor: Determines the allocation of the radial channels. Values below 1 produce a grid along the radius which is more dense toward the center and the shell of the catalyst (according to a geometrical series), whereas values greater than 1 yield a grid which is more dense in the middle of the radius.

5.1.3.6. Catalyst Physical Properties Physical properties of the catalyst's solid phase are required in order to model the thermal behavior of the converter. Typical Values and Ranges Density

190

3

Determines the bulk density of the monolith material 400-2000 (kg/m ) considering the volume in the pores.

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Determines the thermal conductivity of the monolith 0.1-50 (W/(m·K)) material (= bulk solid material considering the volume in the pores). This property can specified as constant value or as a function of temperature.

Specific Heat

Determines the specific heat of the monolith 500-2000 (J/ material (= bulk solid material considering the (kg·K)) volume in the pores). This property can specified as constant value or as a function of temperature.

Anisotropic Corrects the diffusion coefficients of the solid Conduction Factor temperature equation normal to axial direction. A value of 1.0 simulates an isotropic conductivity. A value of 0.5 would be a good choice for monoliths. This value is only needed for 2D simulations.

0-10 (-)

Heat Transfer Model

Determines different approaches for calculating the heat transfer through the boundary layer (see page [28] Section Transfer Coefficients ). If 'Constant' is chosen, a heat transfer coefficient needs to be specified.

Sieder-Tate (default)

Heat Transfer Coefficient

Determines a constant heat transfer coefficient through the boundary layer.

5-500 (W/m2)

Heat Transfer Multiplier

Specify a factor by which the heat transfer is scaled. 0.1-10 (-)

Mass Transfer Model

Determines different approaches for calculating the mass transfer through the boundary layer (see page [28] Section Transfer Coefficients ). If 'Constant' is chosen, a mass transfer coefficient needs to be specified.

Sieder-Tate (default)

Mass Transfer Coefficient

Determines a constant mass transfer coefficient through the boundary layer.

0.01-0.1 (kg/ (m2s))

Mass Transfer Multiplier

Specify a factor by which the mass transfer is 0.01-10 scaled. Possible input is 'Constant' (mass transfer (-) of every species is scaled in the same way) or 'Table' (mass transfer of selected species is scaled).

Catalysts whose substrates are axially structured in a way that there is heat- and mass-transfer between channels, can be modeled using the options from the Catalyst Segmentation section: Typical Values and Ranges Repeat Turbulent Inlet Region

Enable this option in order to consider recurrent turbulent inlet regions along the catalyst's axial direction.

-

Repeating Length

Specify a length at which the turbulent inlet region is 0.001-0.1 (m) repeated.

5.1.3.7. Heat Loss In the current model, Adiabatic Simulation can be chosen, or the radial heat transfer to the environment can be either specified in a simplified model or by using a multi-layered wall model. In the case of a simplified model the required input data must be specified as shown

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5. BOOST Aftertreatment in the following figure. More detailed information on how the radial heat transfer is modeled page [19] can be found in Section Boundary Conditions . In the second case, where the canning and insulation can be modeled in detail by specifying individual wall layers, Variable Wall Temperature needs to be enabled and the required input data can be provided on the related sub-page. Detailed information on the multi-layered wall model can be found in sectionMultipage [65] Layered Wall Model . Figure 56. Heat Loss - Specification of Radial Heat Transfer Conditions

The following input data has to be specified: Typical Values and Ranges

192

Variable Wall Temperature

Enables the specification of a multi-layer wall model around the monolith and disables the input for the simplified heat-loss-to-ambient model below.

External Heat Transfer Coefficient

Determines the heat transfer between the shell and the environment. This property can be defined as constant or as function of the simulation time.

10-100 (W/(m ·K))

Thickness, Shell

Determines the thickness of the shell.

0-5 (mm)

Thickness, Insulation

Determines the thickness of the insulation mat.

0-30 (mm)

Thermal Conductivity, Shell

Determines the thermal conductivity of the shell.

10-100 (W/(m·K))

Thermal Conductivity, Insulation

Determines the thermal conductivity of the insulation mat.

0.01-0.1 (W/(m·K))

Environment Temperature

Determines the temperature of the environment. This property can be defined as constant or as function of the simulation time. This (i.e. the temperature of the medium surrounding the catalyst) may be specified as a function of time. The temperature profile is considered to be periodic if not the entire integration time is covered by the input data.

298-350 (K)

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5. BOOST Aftertreatment 5.1.3.7.1. Variable Wall Temperature Typical Values and Ranges Solid Material Table

Add a solid wall layer by clicking on Insert.

Solid Material

Determines a solid material for a given wall layer. Click in the input field and select a material from the selection field. The properties of the solid material can be specified in the pull-down menu . The first line in the table represents the innermost wall layer and the last line the outermost wall layer.

Layer Thickness

Determines the thickness of each individual wall layer.

No. of Grid Points

Determines the numerical discretization of each wall 3-10 (-) layer in radial direction.

Ambient Temperature

Determines the temperature of the ambient. This value is a constant or a function of simulation time.

Radiation Sink Temperature

Determines the temperature used for the evaluation 273-1000 (K) of radiative heat transfer. This value is a constant or a function of simulation time.

Convection Model

Enables the application of a convection model for the external heat transfer from the outer wall layer surface to the ambient.

Convection Coefficient

Enables the application of a convection coefficient for the external heat transfer from the outer wall layer surface to the ambient.

Coolant

Determines a fluid which is assumed to flow around the outer wall layer. Fluid properties of air and water are available.

Characteristic Determines the velocity of the coolant flowing Velocity of Coolant around the outer wall layer. A cross-flow regime is assumed. Convection Coefficient

0.1-30 (mm)

273-1000 (K)

0.1-30 (m/s)

2

Determines a convective heat transfer coefficient for 7-100 (W/(m ·K)) the external heat transfer. This value is constant or a function of simulation time.

5.1.3.8. Washcoat At "Washcoat" the physical properties of the washcoat material, as well as the reaction mechanism and mass transfer models are specified. Two different approaches are available to model heterogeneous reactions in the catalyst's washcoat: In the Surface Reaction Model approach, the mass transfer, i.e. pore diffusion, through the washcoat layer(s) is neglected. In the Washcoat Layer (WCL) Model approach, pore diffusion is taken into account. Therefore, every washcoat layer is discretized in the direction perpendicular to the catalyst solid surface, resulting in a 1D+1D simulation model. The Surface Reaction Model approach is equivalent to the WCL Model approach with only one washcoat layer of one computational cell.

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5. BOOST Aftertreatment A single Catalyst can consider either the Surface Reaction Model or the WCL Model; they cannot be mixed. Surface Reaction Model The necessary input for the Surface Reaction Model is the thickness of the washcoat, as well as the reaction mechanism describing the chemical behavior of the converter. The set-up of the page [197] Conversion Reactions is located in the first reaction branch My_Reaction . The input of Washcoat Layer Thickness can be done directly in the Catalyst component mask, by selecting "Washcoat Layer Thickness" or it can be taken from an AUCI Catalytic Reaction Mechanism. Details on making use of washcoat properties from custom models can be found in page [221] the related section Washcoat Properties from AUCI Custom Models . Typical Values and Ranges Washcoat Thickness Washcoat Thickness (direct GUI input)

Specify the thickness of the washcoat.

>0-0.003 (m)

From AUCI Catalytic Indicate that the thickness of the washcoat Reaction Mechanism shall be taken from an AUCI custom kinetic page [197] model loaded at subnode My_Reaction . Additionally specify from which custom model it shall be taken by typing its row index in the User Defined Reactions table. Extruded Catalyst

The entire converter is modeled as an extruded catalyst. The washcoat thickness is calculated out page of the input from subnode Type Specification [188] . Tip: An example for extruded catalyst modeling can be found in the related section in the BOOST Aftertreatment Application Examples Guide.

The washcoat thickness is used in the calculation of the hydraulic diameter in case of a "Square Cell Catalyst" and the fraction of solid substrate in the overall converter volume in case of a page [188] "General Catalyst" (cf. Type Specification ). Washcoat Layer (WCL) Model In the WCL Model an arbitrary number of washcoat layers can be defined. This is done in the related table of washcoat layers that is editable as soon as the WCL model has been selected. For each washcoat layer a separate row is added to the table. The required input for the simulation is done on related subnodes: For each washcoat layer the following subnodes are created: 1. My_Layer page [195]: Specify the physical properties of the washcoat material and input required for the numerical simulation model. 2. My_Reaction page [197]: Specify the reaction mechanism taking place in the related washcoat layer. 3. My_Transport page [219]: Specify the pore diffusion model that describes the mass transfer within the washcoat layer.

194

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5. BOOST Aftertreatment Tip: The labels of these subnodes may be changed within the table listing all washcoat layers; for example "My_Layer" at washcoat layer #1 could be renamed to "Top_Layer": Simply double-click the related input field and enter a new label. 5.1.3.8.1. Washcoat Layer Specification At "My_Layer" physical properties of the washcoat layer as well as numerical simulation model input is given. Below, the required input for single washcoat layer (WCL) is described. Some of the WCL properties may either be typed-in directly at this input pages or an AUCI custom model may be indicated as source. Details on this treatment are given in the related section Washcoat page [221] Properties from AUCI Custom Models . Dimension For each washcoat layer its thickness needs to be indicated. Note that the washcoat layer thickness needs to be greater than zero. The following input possibilities are available: Typical Values and Ranges Washcoat Layer Thickness Washcoat Layer Thickness (direct GUI input)

Specify the thickness of the washcoat layer.

>0-0.003 (m)

From AUCI Catalytic Indicate that the thickness of the washcoat layer Reaction Mechanism shall be taken from an AUCI custom kinetic page [197] model loaded at the related My_Reaction subnode for this WCL. Additionally specify from which custom model it shall be taken by typing its row index in the User Defined Reactions table. From AUCI Transfer Model

Indicate that the thickness of the washcoat layer shall be taken from an AUCI custom pore diffusion model loaded at the related page [219] My_Transport subnode for this WCL.

Extruded Catalyst

The entire converter is modeled as an extruded catalyst. The washcoat thickness is calculated out page of the input from subnode Type Specification [188] . Note: In order to use this option in the Washcoat Layer Model there is only a single washcoat layer allowed in the catalyst. Tip: An example for extruded catalyst modeling can be found in the related section in the BOOST Aftertreatment Application Examples Guide.

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5. BOOST Aftertreatment Reference for Chemistry Data Optionally, reference data can be provided to specify the ratio of washcoat layer volume to converter volume of the particular catalyst for which the kinetic parameters have been calibrated. page [23] More details on this topic can be found in the related section Reference for Chemistry Data . Typical Values and Ranges Specify a Reference WCL Volume

Select this option to type-in the reference washcoat layer volume.

>0-0.01 (-)

Discretization The following input is required for the computational model. Typical Values and Ranges Number of Grid Points

Specify the number of computational cells of each washcoat layer.

1-10 (-)

Washcoat Physical Properties The following physical properties of the washcoat layer material can be specified. Typical Values and Ranges Washcoat Bulk Density WCL Bulk Density (direct GUI input)

Specify the density of the washcoat layer material.

3

400-2000 (kg/m )

From AUCI Catalytic Indicate that the bulk density of the washcoat Reaction Mechanism layer material shall be taken from an AUCI custom kinetic model loaded at the related page [197] My_Reaction subnode for this WCL. Additionally specify from which custom model it shall be taken by typing its row index in the User Defined Reactions table. Washcoat Porosity WCL Porosity (direct GUI input)

Specify the porosity of the washcoat layer material.

From AUCI Catalytic Indicate that the porosity of the washcoat layer Reaction Mechanism material shall be taken from an AUCI custom kinetic model loaded at the related My_Reaction page [197] subnode for this WCL. Additionally specify from which custom model it shall be taken by typing its row index in the User Defined Reactions table. From AUCI Transfer Model

196

Indicate that the porosity of the washcoat layer material shall be taken from an AUCI custom pore diffusion model loaded at the related page [219] My_Transport subnode for this WCL.

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0-1 (-)

5. BOOST Aftertreatment 5.1.3.8.2. Reaction Model (Conversion Reactions) At "My_Reaction" several different reaction models are available. Either no reactions are taken into account, pre-defined or custom kinetic models are chosen or the application of map based conversion is possible. Pre-Defined Kinetic Models The pre-defined reaction models use global kinetic approaches given by Langmuir Hinshelwood equations and also transient mechanisms where adsorption and desorption steps are explicitly taken into account. All reaction models are supplied with default values for the individual kinetic parameters. The user can use the kinetic model and adjust all kinetic parameters. Note: The suggested reaction parameters have been successfully applied to several validation simulations, but they may have to be adjusted for use in other types of catalysts. In this case it is recommended to apply the pre-defined reaction model and to supply it with adequate reaction parameters. The following pre-defined reaction models are available: • Diesel Oxidation Catalyst (DOC) This model is dedicated for DOCs comprising the three major oxidation reactions of CO, HC and NO. • Three Way Catalyst (TWC) This model is a dedicated TWC model comprising seven conversion reactions and surface storage reactions on cerium, rhodium and barium. By selecting specific reactions and adapting the related kinetic parameters, this model also can be applied to other catalysts such as DOCs. • Selective Catalytic Reduction (SCR), Steady Kinetics This model comprises seven reaction rates which can be enabled/disabled individually for three different reaction sections in the catalyst. The SCR rates use Eley-Rideal mechanisms, thus it assumes steady-state conditions for the reaction steps of adsorption, catalytic reaction and desorption. • Selective Catalytic Reduction (SCR), Transient Kinetics This model comprises nine reactions that can be enabled/disabled individually for three different reaction sections in the catalyst. The transient effect of ad-/desorption is explicitly taken into account. • Lean NOx Trap This model comprises ten conversion reactions and surface storage on cerium. Furthermore, it offers two approaches of storing nitric oxides: an ash core model approach, developed by ICVT Stuttgart, and a surface storage approach. Detailed information about the individual reaction mechanisms is given in section Kinetic Models page [77] . Custom Kinetic Models In addition to providing the above pre-defined reaction mechanism custom kinetic models can be simulated as well. For that two interfaces are available: • User Defined Reactions (Without Archive) Here, a custom kinetic model programmed in the FORTRAN file mod_userdef_cat.f90 can be activated. For details on using this approach of custom kinetic models contact the BOOST Support. Restriction: This type of custom kinetic model cannot be combined with any other kinetic model in the same surface or washcoat layer model. Note: This type of custom kinetic model is deprecated. It is recommended to use "User Defined Reactions" and AUCI for designing custom models.

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5. BOOST Aftertreatment • User Defined Reactions Using this option custom kinetic models designed in AUCI Catalytic Reaction Mechanism can be activated. Details in AUCI can be found in the related documentation. This type of custom kinetic model can be combined with the pre-defined models in the same surface or washcoat layer model. Map Based Conversion As an alternative to kinetic models in the catalyst, its conversion can also be modeled by providing maps that comprise the species conversion as a function of different parameters (e.g. temperature, space velocity), that are to be detailed at the related sub-page. In addition to these conversion maps it is also possible to use control elements to define conversion dependencies and to actuate a species' conversion. Restriction: None of the kinetic models can be combined with Map Based Conversion. Further input Typical Values and Ranges Effective Catalyst Loading

This dimensionless value is a measure for > 0 [-] the content of precious group metals (PGM) in the washcoat. It is used as a multiplier to all conversion reactions that are related to PGM. Hence one can model • different PGM loading in the washcoat, by increasing or decreasing the effective catalyst loading relative to a base set of kinetic parameter, assuming that the impact of loading can be linearly covered in the frequency factors, • aging or poising by choosing a value smaller 1.0. Note: Reactions involving surface site species (type "Storage") are not affected by this multiplier.

Tolerate Undefined Species

198

Each reaction requires the educts and products, and optionally those species that are being used in the rate formulation (e.g. as inhibitors), to be present in the Gas Composition (cf. Run page [181] Information ). Hence, if a required species is missing the solver will stop indicating to add that species to the Gas Composition. By checking this switch it is possible to continue the simulation without having all species required by the reaction mechanism available in the gas composition.

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5. BOOST Aftertreatment Attention: If species required by the stoichiometry as products are being omitted, mass conservation is broken and simulation results may be considered with care.

5.1.3.8.2.1. Diesel Oxidation Catalyst (DOC) This reaction model offers a set of three oxidation reactions. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. page [77] More detailed information about this model is given in section DOC Catalyst Reactions . The different reactions can be en/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: CO Oxidation

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

R2: C3H6 Oxidation

R3: NO Oxidation

K1 - K5

Determines the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determines the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of propane as representative of hydro carbons. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determines the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determines the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

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5. BOOST Aftertreatment

Approach 2

K

Determines the frequency factors used in the pre-defined reversible power-law conversion mechanism.

E

Determines the activation temperatures used in the pre-defined reversible power-law conversion mechanism.

A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

5.1.3.8.2.2. Three Way Catalyst (TWC) This reaction model offers a set of nine conversion reactions and surface storage mechanisms at three different surface sites. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. page [78] More detailed information about this model is given in Section TWC Catalyst Reactions . The different reactions can be enabled/disabled individually by clicking the corresponding check boxes. When enabled, several sub-pages for the detailed specification of the reaction parameters become enabled. R1: CO Oxidation

R2: C3H6 Oxidation

200

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of propene as representative of hydrocarbons. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

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5. BOOST Aftertreatment

R3: CO-NO Redox Reaction

R4: H2 Oxidation

R5: NO Oxidation

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of carbon monoxide and reduction of nitric monoxide. The denominator takes into account an inhibition effect of carbon monoxide. Each reaction constant is evaluated using Arrhenius' law. The reaction order of carbon monoxide is a function of the carbon monoxide concentration itself and therefore the order changes between lean and rich conditions.

m

Determines the reaction order of nitric monoxide in the pre-defined reaction approach.

n

This is a tuning value in order to determine the reaction order of carbon monoxide (n) in the pre-defined reaction approach. There are two possibilities, either a constant value for n (activate Reaction Order and specify n), or the evaluation of the Shift Function (activate Shift Function and specify o).

K1 - K2

Determine the frequency factors used in the predefined conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of hydrogen. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available.

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5. BOOST Aftertreatment The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

Approach 2

R6: CO-H20 Shift

R7: C3H8 Oxidation

K

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism.

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism.

A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the water gas shift reaction. Its reversible behavior is taken into account by considering the equilibrium constant as part of the rate equation. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the oxidation of propane. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law.

K1 - K5

202

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

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5. BOOST Aftertreatment E1 - E5

R8: C3H6-H20 Shift

R9: C3H8-H20 Shift

R10-R13: Ce Storage

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for water gas shift reactions. Its reversible behavior is taken into account by considering the equilibrium constant as part of the rate equation. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

The Langmuir-Hinshelwood kinetic approach is commonly accepted in the literature for the water gas shift reaction. Its reversible behavior is taken into account by considering the equilibrium constant as part of the rate equation. The denominator takes into account the different inhibition effects of all species involved and each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Under lean conditions cerium is oxidized by O2 and under rich conditions cerium is reduced by CO, C3H6 and C3H8. All rates are of first order with respect to the participating gas and solid phase components. All reaction constants are evaluated using Arrhenius' law. R10

R11

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5. BOOST Aftertreatment

R12

R13

R14-R19: Rh Storage

Cerium Storage Capacity

Determines the maximum amount of oxygen that can be stored on the cerium surface site.

Initial Surface Coverage fraction of CeO2

Determines the coverage fraction of CeO2 at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of CeO2

Determines the maximum surface coverage fraction of CeO2 at the solid surface. This property can be specified as a constant value or as a function of temperature. Range: 0-1 (-)

K1 - K4

Determines the frequency factors used in the predefined ad-/desorption mechanisms .

E1 - E4

Determines activation temperatures used in the pre- ad-/desorption mechanisms .

Under lean conditions rhodium is oxidized by O2 or NO and under rich conditions rhodium is reduced by CO, H2, C3H6 and C3H8. All rates are of first order with respect to the participating gas and solid phase components. All reaction constants are evaluated using Arrhenius' law. R14

R15

R16

R17

R18 204

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R19

R20-R21: Ba Storage

Rhodium Storage Capacity

Determines the maximum amount of oxygen that can be stored on the rhodium surface site.

Initial Surface Coverage fraction of RhO

Determines the coverage fraction of at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of RhO

Determines the maximum surface coverage fraction of at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

K1 - K6

Determine the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E6

Determine the activation temperatures used in the pre-defined sorption-equilibrium and ad/desorption mechanisms.

In the presence of NO2 and O2, barium carbonate is oxidized to barium nitrate and in the presence of CO, barium nitrate is reduced to barium carbonate. All rates are of first order with respect to the participating gas and solid phase components. All reaction constants are evaluated using Arrhenius' law. R20

R21

Barium Storage Capacity

Determines the maximum amount of nitric oxide that can be stored on the barium surface site.

Initial Surface Coverage fraction of Ba(NO3)2

Determines the coverage fraction of Ba(NO3)2 at the solid surface. Range: 0-1 (-)

Max Surface Coverage

Determines the maximum surface coverage fraction of Ba(NO3)2 at the solid surface. This property can be specified as constant value or as function of temperature.

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5. BOOST Aftertreatment fraction of Ba(NO3)2

Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E2

Determine the activation temperatures used in the pre- ad/desorption mechanisms.

Metal Storage Capacity

Determines the maximum amount of C3H6 that can be stored on the metallic surface site.

Initial Surface Coverage fraction of C3H6

Determines the coverage fraction of C3H6 at the solid surface. Range: 0-1 (-)

Max Surface Coverage fraction of C3H6

Determines the maximum surface coverage fraction of C3H6 at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined sorption-equilibrium and ad/desorption mechanisms.

E1 - E2

Determine the activation temperatures used in the pre-defined sorption-equilibrium and ad/desorption mechanisms.

R22: HC Storage

5.1.3.8.2.3. Selective Catalytic Reduction (HSO SCR), Steady Kinetics This reaction model offers a set of seven conversion reactions that are typically used in SCR converters. This pre-defined model is setup in a way that three different reaction sections can be specified where in each section the reactions can be individually switched on. The name HSO is related to a typical SCR system where three different sections for Hydrolysis, SCR and Oxidation are used in one converter. If only one section is considered, the lengths of the two others sections can be simply set to zero. The model uses steady-state approaches for all SCR reactions as given by the Eley-Rideal mechanism. For the hydrolysis and all oxidation reactions also steady-state power-law reactions are applied. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. More detailed information about this model is given in Section HSO-SCR Catalyst Reactions, page [81] Steady-State Approach . The rate is assumed to be of first order with respect to both water vapor and isocyanic acid. The reaction constant is evaluated using Arrhenius' law. Length of Section 1 Length of Section 2

206

This is a dimensionless length that is used to specify up to three different reaction sections. The length of the third section is calculated by 1-Length_1-Length_2. If only one section is needed, set the length of section 1 to '1' and section 2 to '0'. Range: 0-1 (-)

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5. BOOST Aftertreatment The different reactions can be enabled/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: HNCO Hydrolysis

R2: NO Reduction

R3: NOx Reduction

R4: NO2 Reduction

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined power law mechanism.

E

Determines the activation temperature used in the pre-defined power law conversion mechanism.

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide and dioxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

K1 - K2

Determine the frequency factors used in the predefined Eley-Rideal conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined Eley-Rideal conversion mechanism.

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide and dioxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

K1 - K2

Determine the frequency factors used in the predefined Eley-Rideal conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined Eley-Rideal conversion mechanism.

The Eley-Rideal kinetic approach is commonly accepted in the literature for the selective reduction of nitric monoxide and dioxide with ammonia. The denominator takes into account the inhibition effects of ammonia and each reaction constant is evaluated using Arrhenius' law.

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R5: NH3 Oxidation 1

R6: NH3 Oxidation 2

R7: NO Oxidation

K1 - K2

Determine the frequency factors used in the predefined Eley-Rideal conversion mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined Eley-Rideal conversion mechanism.

The rate is assumed to be of first order with respect to ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined power law mechanism.

E

Determines the activation temperature used in the pre-defined power law conversion mechanism.

The rate is assumed to be of first order with respect to ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined power law mechanism.

E

Determines the activation temperature used in the pre-defined power law conversion mechanism.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. Each reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

Approach 2

208

K

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism.

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism.

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5. BOOST Aftertreatment A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism.

5.1.3.8.2.4. Selective Catalytic Reduction (HSO SCR), Transient Kinetics This reaction model offers a set of nine conversion reactions that are typically used in SCR converters. This pre-defined model is setup in a way that three different reaction sections can be specified where in each section the reactions can be individually switched on. The name HSO is related to a typical SCR system where three different section for Hydrolysis, SCR, and Oxidation are used in one converter. If only one section is considered, the lengths of the two other sections simply can be set to zero. The model uses steady-state approaches for the hydrolysis, one of the ammonia and one of the nitric monoxide oxidation reactions. For the SCR reactions explicit ad-/desorption steps of ammonia at the solid surface are taken into account. The rate equation and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. More detailed information about this model is given in page [83] Section HSO-SCR Catalyst Reactions, Transient Approach . Length of Section 1 Length of Section 2

This is a dimensionless length that is used to specify up to three different reaction sections. The length of the third section is calculated by 1-Length_1-Length_2. If only one section is needed set the length of section 1 to '1' and of section 2 to '0'. Range: 0-1 (-)

The different reactions can be en/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: HNCO Hydrolysis

R2-R3: NH3 Adsoprtion, Desorption

The rate is assumed to be of first order with respect to both vapor and isocyanic acid. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factors used in the predefined power law mechanism.

E

Determines the activation temperatures used in the pre-defined power law conversion mechanism.

The adsorption rate is of first order with respect to ammonia in the gas phase and also proportional to the free site fraction at the surface. The desorption rate is proportional to the amount of ammonia stored at the surface. For the desorption a surface coverage dependency is additionally taken into account. Each reaction constant is evaluated using Arrhenius' law. R2

R3

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5. BOOST Aftertreatment NH3 Storage Capacity

Determines the maximum amount of ammonia that can be stored at the solid surface site.

Initial Surface Coverage Fraction of NH3

Determines the coverage fraction of NH3 at the solid surface. Range: 0-1 (-)

Coverage Determines a surface coverage dependency in the Dependency pre-defined ad/desorption mechanisms. (epsilon) Max Surface Coverage Fraction of NH3

Determines the maximum surface coverage fraction of NH3 at the solid surface. This property can be specified as constant value or as function of temperature. Range: 0-1 (-)

NH3 Determines the order of NH3 surface coverage Surface fraction in the adsorption rate formulation. Coverage Range: 0-2 (-) Fraction Dependency m

R4: NO Reduction

R5: NOx Reduction

210

K1 - K2

Determines the frequency factors used in the predefined ad/desorption mechanisms.

E1 - E2

Determines the activation temperatures used in the pre- ad/desorption mechanisms.

The reaction rate is of first order with respect to nitric monoxide in the gas phase and it depends on the stored amount of ammonia at the surface. The reaction is additionally limited by a critical surface fraction of ammonia.

Critical Surface Coverage)

Determines a tuning factor that slows down the reaction rate above a critical surface coverage.

K

Determines the frequency factor used in the predefined transient conversion mechanism.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism.

The reaction rate is of first order with respect to nitric dioxide in the gas phase and it depends on the stored amount of ammonia at the surface. The reaction is additionally limited by a critical surface fraction of ammonia.

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5. BOOST Aftertreatment

R6: NO2 Reduction

R7: NH3 Oxidation 1

R8: NH3 Oxidation 2

R9: NO Oxidation

Critical Surface Coverage)

Determines a tuning factor that slows down the reaction rate above a critical surface coverage.

K

Determines the frequency factor used in the predefined transient conversion mechanism.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism.

The rate is assumed to be of first order with respect to stored ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

Critical Surface Coverage)

Determines a tuning factor that slows down the reaction rate above a critical surface coverage.

K

Determines the frequency factor used in the predefined transient conversion mechanism.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism.

The rate is assumed to be of first order with respect to stored ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined transient oxidation mechanism.

E

Determines the activation temperature used in the pre-defined transient oxidation.

The rate is assumed to be of first order with respect to stored ammonia and of zero order with respect to oxygen. The reaction constant is evaluated using Arrhenius' law.

K

Determines the frequency factor used in the predefined power-law oxidation mechanism.

E

Determines the activation temperature used in the pre-power-law transient oxidation.

A reversible rate mechanism is commonly accepted in the literature for the oxidation of nitric monoxide. Two rate approaches are available. The reaction constant is evaluated using Arrhenius' law. The equilibrium constant is also a function of the temperature and is derived from the free Gibbs reaction enthalpy. Approach 1

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Approach 2

Temperature Determines the temperature dependency used in Dependency the pre-defined transient and reversible power-law (A) conversion mechanism.

R10: NO2 Formation

K

Determines the frequency factor used in the pre-defined transient and reversible power-law conversion mechanism.

E1

Determines the activation temperature used in the pre-defined transient and reversible power-law conversion mechanism.

K

Determines the frequency factor used in the predefined power-law conversion mechanism.

E

Determines the activation temperature used in the pre-defined power-law conversion mechanism.

5.1.3.8.2.5. Lean NOx Trap (LNT) This reaction model offers a set of ten conversion reactions, surface storage on cerium and barium. The rate equations and a set of default values of all kinetic parameters are given. The user can adjust all kinetic parameters. The different reactions can be en/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. R1: H2 Oxidation

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Order m

Determines the reaction order of nitric oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

R2: CO Oxidation

212

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5. BOOST Aftertreatment E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Determines the reaction order of propene, nitric Orders m, n, oxide and oxygen in the pre-defined Langmuirp Hinshelwood conversion mechanism. R3: C3H6 Oxidation

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Determines the reaction order of oxygen and nitric Orders m, n oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism. R4: NO Oxidation

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Kinetic Determines a kinetic coefficient used in the Coefficient f pre-defined Langmuir-Hinshelwood conversion mechanism. Reaction Determines the reaction order of propene, nitric Orders m, n, oxide and oxygen in the pre-defined Langmuirp Hinshelwood conversion mechanism. R5: NO Reduction H2

K1

Determines the frequency factor used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1

Determines the activation temperature used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

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5. BOOST Aftertreatment R6: NO Reduction CO

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Reaction Determines the reaction order of propene and nitric Orders m, n oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism. R7: NO Reduction C3H6 K1

Determines the frequency factor used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1

Determines the activation temperature used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

R8: NO2 Reduction CO

R9: NO2 Reduction C3H6

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5. BOOST Aftertreatment Reaction Order m

Determines the reaction order of nitric oxide in the pre-defined Langmuir-Hinshelwood conversion mechanism.

K1 - K4

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism. Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

E1 - E4

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism.

Ce Storage Capacity

Determines the maximum amount of oxygen that can be stored on the cerium surface site.

Initial Surface Coverage Fraction of CeO2

Determines the coverage fraction of CeO2 at the solid surface. This property can be specified as a constant value or as a function of the catalyst length. Range: 0-1 (-)

K1 - K2

Determine the frequency factors used in the predefined ad/desorption mechanism. Determine the frequency factors used in the predefined ad/desorption mechanism.

E1 - E2

Determine the activation temperatures used in the pre-defined ad/desorption mechanism.

R10: Water Gas Shift Reaction

R11: Surface Storage on Cerium

Reaction Determines the reaction order of oxygen stored on Orders m, n, the surface and oxygen ratio at the surface in the p, q pre-defined ad/desorption mechanism. R12-R16: Surface Storage on Barium Carbonate

R12

R13

R14

R15

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5. BOOST Aftertreatment R16

BaCO3 Storage Capacity

Determines the maximum amount of nitric oxides that can be stored on the barium carbonate clusters (rate approach 1) and barium carbonate surface site (rate approach 2).

Initial Surface Coverage Fraction of Ba(NO3)2

Determines the coverage fraction of Ba(NO3)2 at the solid surface. This property can be specified as a constant value or as a function of the catalyst length. Range: 0-1 (-)

Rate approach 1

This activates the sophisticated ash core model where the NO and NO2 molecules are stored as Ba(NO3)2 in barium cluster particles. Additional differential equations are solved to determine mole fractions of all gas phase species on the dimensionless ash core front position in the barium cluster particles. The ash core front moves from the outer radius ( =1) toward the center ( =0) page [88] of the cluster particle (see sketch in Fig. 36

Rate approach 2

This activates the surface storage model where the NO and NO2 molecules are stored as Ba(NO3)2 on the catalytic surface represented by the surface coverage fraction ZBa(NO3)2.

K1 - K5

Determine the frequency factors used in the pre-defined ad/desorption mechanism for Rate approach 1 and Rate approach 2. Determine the frequency factors used in the pre-defined ad/desorption mechanism for Rate approach 1 and Rate approach 2.

E1 - E5

Determine the activation temperatures used in the pre-defined ad/desorption mechanism.

Reaction Determines the reaction order of Ba(NO3)2 in the Orders m, n, pre-defined ad/desorption mechanism of Rate p, q, r approach 2. R12-R16: Ash Core Model

The ash core model is activated by Rate approach 1. R12

R13

R14 216

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R15

R16

Particle Radius

Determines the radius RBa,p of the barium cluster particle. Typical Value: 5.0e-8 (m)

Min Specific Surface

Determines the minimum specific particle surface area ap,min. 2 3 Typical Value: 48.4 (m /m )

Max Specific Surface

Determines the minimum specific particle surface area ap,max. 2 3 Typical Value: 452637 (m /m )

Pore Diffusion Coefficient

Determines the diffusion coefficient DBa,p of the barium cluster particle. This property can be specified as constant value or as function of temperature. 2 Typical Value: 2.672e-14 (m /s)

Scaling The LNT model assumes that NOx desorption Factor (regeneration) takes place faster than NOx During adsorption (storage). This factor increases the pore Regeneration diffusion coefficient during regeneration. Typical Value: 10 (-) 5.1.3.8.2.6. User Defined Reactions (Without Archive) This is an interface to load a custom kinetic from a custom kernel. User-defined reaction mechanisms can be set by linking a user-routine. In this case the user can supply his user-routine with parameters set in the GUI. The two columns are: • The left column is designated for comments (BOOST interprets each entry as character) • The right column is used to specify input values (integer, double and character). It is the user's responsibility to interpret these values in the correct way in his user-routine. 5.1.3.8.2.7. User Defined Reactions This is an interface to load custom kinetic models developed using the AVL User Coding Interface (AUCI). Loading and maintaining an AUCI Catalytic Reaction Mechanism In general an arbitrary number of AUCI Catalytic Reaction Mechanism models can be loaded. In order to add or delete an AUCI model click Insert and Remove repsectively next to the table. An AUCI model ("Archive") is stored in an ucp and uca file respectively, and the existing predefined kinetic models are available as ucp files in the installation. An already loaded Archive can be enabled or disabled in the simulation by selecting Yes and No respectively in the first column of the table. The buttons below the table provide the following functions:

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5. BOOST Aftertreatment Button

Description

Select Archive

Opens a filebrowser to select an ucp or uca file.

Reload Archive

Reload the Archive from the selected row. In order to reset the Model Parameters with the default values from the AUCI model click "No" in the pop-up box "Keep current parameter values?".

Edit Archive

Launches AUCI Catalytic Reaction Mechanism graphical user interface (GUI). If a row has been selected in the table the AUCI model will be opened in that GUI.

Model Parameters

Interface to access the public model parameters from the selected Archive. In the pop-up window these parameters can be modified and global/local parameters can be assigned to them for access in the Parameter or Case Explorer.

Designing an AUCI Catalytic Reaction Mechanism AUCI is a graphical user interface that supports designing custom kinetic models for catalysts and filters as well as custom transfer models for heat and mass transfer as well as pore diffusion. Please, refer to the related AUCI documentation for more details on using AUCI. 5.1.3.8.2.8. Map Based Conversion This model comprises different input of conversion maps, where the user can specify the conversion of selected species depending on several conditions like massflow, substrate temperature and further more. Species conversion maps can be added or removed by clicking the right mouse button on the tree node Map Based Conversion. Conversion Definition The following input data has to be specified: Typical Values and Ranges Species

Enter the name of a General Species whose conversion is specified for. If the species is not contained in the Gas Composition then the Conversion map is ignored.

Conversion

Select the conversion specification Constant: Enter a constant conversion value. Table: Specify the conversion as a function of one of the conversion dependencies. Map: Specify the conversion as a function of two of the conversion dependencies. If Constant is selected, enter a value for constant species conversion.

Table for Conversion of The following input data has to be specified:

218

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5. BOOST Aftertreatment Typical Values and Ranges Conversion Dependency

The following Conversion Dependencies are available: • Inlet Gas Temperature • Mean Solid Temperature • Inlet Massflow • Inlet Excess Oxygen Ratio • Inlet GHSV

Conversion Table

Specify the conversion as a function of the selected Conversion Dependency.

Map for Conversion of The following input data has to be specified: Typical Values and Ranges Conversion Dependency 1 and Conversion Dependency 2

The following Conversion Dependencies are available: • Inlet Gas Temperature • Mean Solid Temperature • Inlet Massflow • Inlet Excess Oxygen Ratio • Inlet GHSV

Conversion Map

Specify the conversion as a function of the selected Conversion Dependency 1 and Conversion Dependency 2.

5.1.3.8.3. Transport Model At "My_Transport" different pore diffusion models can be selected. The transport model for the active washcoat layer model determines the calculation of the diffusion coefficient Dk,eff for every species of the pore diffusion model (see section Transport Models

page [21]

).

Note: For specification of the transport model the Washcoat Layer (WCL) Model must be active. The transport model has to be specified for each washcoat layer separately. The following models are available: 5.1.3.8.3.1. Constant Pore Diffusion For this model constant diffusion coefficients are applied. If Constant Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Diffusion Coefficients

Determines the effective diffusion coefficient Dk,eff of every species in the washcoat layer.

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10

-14

-5

2

-10 (m /s)

219

5. BOOST Aftertreatment 5.1.3.8.3.2. Effective Pore Diffusion The effective diffusion coefficient is calculated with the free gas flow diffusion coefficient adapted with the washcoat layer porosity and tortuosity. A scaling factor allows linear variation of the calculated value for every species. If Effective Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Tortuosity

Determines the tortuosity layer.

Diffusion Scaling Factors

Determines the scaling factors multiplied to the calculated effective diffusion coefficient Dk,eff of every species in the washcoat layer.

wcl

of the washcoat

1-5 (-) 0-100 (-)

5.1.3.8.3.3. Random Pore Diffusion This model assumes that the washcoat features two distinct characteristic pore size diameters, called macro- and micro-pores. The two macro and micro pore diffusion coefficients are combined applying probabilistic and geometrical considerations. If Random Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges Macropore Porosity

Determines the porosity (= gas void fraction) of the macro pores.

0-1 (-)

Micropore Porosity

The value of the micropore porosity is not entered, but calculated out of the above macropore porosity and the washcoat layer page [196] porosity specified at My_Layer according to .

0-1 (-)

Macropore Diameter

Determines the mean diameter of the macro pores.

10 -10 (m)

Micropore Diameter

Determines the mean diameter of the micro pores.

10 -10 (m)

Diffusion Scaling Factors

Determines the scaling factors multiplied to the calculated effective diffusion coefficient Dk,eff of every species in the washcoat layer.

0-100 (-)

-8

-4

-9

-5

5.1.3.8.3.4. Parallel Pore Diffusion The model combines the transport effects of the pure gas phase and Knudsen diffusion assuming both transport effects are taking place in parallel. If Parallel Pore Diffusion is selected, the following input data has to be specified: Typical Values and Ranges

220

Tortuosity

Determines the tortuosity layer.

Pore Diameter

Determines the mean pore diameter of washcoat layer.

wcl

of the washcoat

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1-5 (-) -9

-3

10 -10 (m)

5. BOOST Aftertreatment Diffusion Scaling Factors

Determines the scaling factors multiplied to the calculated effective diffusion coefficient Dk,eff of every species in the washcoat layer.

0-100 (-)

5.1.3.8.3.5. User Defined Pore Diffusion This is an interface to load pore diffusion models designed using AUCI Transfer Models. Details on the usage of AUCI can be found in the related documentation. If User Defined Pore Diffusion is selected, the following input data can be specified: Typical Values and Ranges User Coding Archive

Path and filename of the AUCI Transfer Model. Click on Select Archive to choose an exsting AUCI model. Click on Edit Archive to open AUCI Transfer Model and design a user defined pore diffusion models.

ucp or uca file

5.1.3.8.4. Washcoat Properties from AUCI Custom Models In order to respect proprietary information, washcoat properties may also be provided by a custom model. Note: Details on the handling of washcoat properties before the BOOST v2014.1 release can be found in the FAQ section of the BOOST Aftertreatment Application Examples Guide. Loading a washcoat property from an AUCI custom model For some of the washcoat properties it is possible to load the respective property's value from an AUCI custom model instead of entering the value directly in the component's mask in the BOOST GUI; the related selection and input looks for example like that: Figure 57. Example: Washcoat Layer Thickness Value provided via BOOST GUI.

The washcoat property – in the above example the washcoat layer thickness – can be either: 1. typed in directly in the BOOST GUI, 2. loaded from the indicated AUCI Catalytic Reaction Mechanism, 3. loaded from an AUCI Transfer Model. In the latter two cases only AUCI models loaded in the same washcoat layer can be referred to. In the below example, the second option, i.e. From AUCI Catalytic Reaction Mechanism has been chosen as source for the washcoat layer thickness and the index of the AUCI model is 1: Figure 58. Example: Washcoat Layer Thickness Value loaded from an AUCI Catalytic Reaction Mechan

Hence, the custom kinetic model number 1 at the related subnode My_Reaction to be considered:

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page [197]

is going

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5. BOOST Aftertreatment

Note: Only if washcoat properties are provided with the AUCI Catalytic Reaction Mechanism the input will actually be taken from the custom model. Detailed information on how to specify washcoat properties in AUCI can be found in the related AVL User Coding Interface documentation.

In the next example, the washcoat layer thickness is taken From AUCI Transfer Model: Figure 59. Example: Washcoat Layer Thickness Value loaded from an AUCI Transfer Model (Pore Diffu

page [219]

This requires that the Transport Model at the related subnode My_Transport is set to User Defined Pore Diffusion and that an AUCI model comprising a pore diffusion model is loaded:

Note: ucp as well as uca files can be loaded as AUCI models. Affected simulation variables The different washcoat layer properties are used in the different parts of the entire washcoat and kinetic modeling. The below table gives an overview on what is actually used when.

222

Simulation Submodel

Required Washcoat Property

Surface Reaction Model

Washcoat Layer Model

Flow

WCL Thickness

As indicated in BOOST GUI.(*)

As indicated in BOOST GUI.(*)

Solid Enthalpy Balance

WCL Bulk Density

Washcoat Property not required

As indicated in BOOST GUI.(*)

Species Balance in the Reaction Layer

WCL Porosity, WCL Thickness

Washcoat Property not required

As indicated in BOOST GUI.(*)

Transport Model in the WCL

WCL Porosity

-

As indicated in BOOST GUI.(*)

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5. BOOST Aftertreatment Simulation Submodel

Required Washcoat Property

Surface Reaction Model

Washcoat Layer Model

Reaction Rate Evaluation (**)

WCL Bulk Density

The value included in the AUCI model is considered.

As indicated in BOOST GUI.(*)

(*): This can be the BOOST GUI input or the value included in the indicated AUCI model. (**): Affects the conversion from unit group "Washcoat Mass Based" only. 5.1.3.9. Homogenous Gas Phase Reactions Within a catalyst homogenous gas phase reactions can be taken into account. If activated, a chemistry set has to be referred through its key. 5.1.3.10. Result Specification Typical Values and Ranges Spatial Position

The following options are available: • Use Grid: All results are written at all the points of the computational grid. • Set Grid: All results are written at a user-defined equally spaced grid. • Use 5 Points: All results are written at an equally spaced grid of five points in both axial and radial (for the case of 2D simulations) direction. • User Defined: All results are written at user-defined dimensionless coordinates in axial and radial (for the case of 2D simulations) direction.

Axial Output Points

Determines the number of equally spaced axial positions in the element at which all transient simulation results are written.

5-30 (-)

Radial Output Points

Determines the number of equally spaced radial positions in the element at which all transient simulation results are written. In the case of 1D simulation this value is set to 1. In the case of 2D simulation all the results are given on a mesh of (Axial Output Points x Radial Output Points).

5-30 (-)

User Defined Axial, Radial

Determines dimensionless coordinates at which all transient simulation results are written. In 1D simulations the radial coordinate is set to 0.

(0-1, 0-1) (-)

Type of Results

The following options are available: • Reduced: A reduced set of mean and outlet values is written. • Standard: A standard set of results (temperatures, pressures, conversions,...) is written. • Standard, Properties:

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5. BOOST Aftertreatment The standard set of results is extended by properties such as heat capacities, conductivities, transfer coefficients. • Standard, Fluxes: The standard set of results is extended by mass and heat fluxes. • Standard, Sources: The standard set of results is extended by sources from the individual chemical reactions. • All: All results, the standard set, properties, fluxes and sources are written. General information on how to use the BOOST post-processor and how to graphically display all the simulation results is available in the BOOST Users Guide and the GUI Users Guide.

5.1.4. Particulate Filter For the simulation of particulate filters, the same input procedure is required as described for the page [181] page [187] catalytic converter (see Section Run Information to Section Catalyst ). This means that run information, definitions of the gas and also solid species and boundary conditions have to be supplied by the user. The specification of the particulate filter itself also follows the input page [187] concept of the catalytic converter presented in Section Catalyst . Thus, in the following section, only filter specific input data is explained. 5.1.4.1. General Two different approaches are available to apply chemical reactions within Particulate Filters. If the Chemical Reactions toggle switch is activated, the user has access to several predefined page regeneration and catalytic reaction models which are described in Chemical Reactions [151] . By activating the Chemical Reactions with Archive toggle switch user-defined reaction mechanisms developed by using the AVL User Coding Interface can be applied. If the No Chemical Reactions toggle switch is activated, no chemical reactions can be modeled and default values will be considered for the numerical and physical properties for the singlechannel converter model as well as the filter flow model. Select to Couple to upstream element to thermally couple the particulate filter to an upstream page [75] element via wall heat conduction (see Thermal Coupling for details). When Consider Air Gap between the Substrates is deselected, thermal coupling to an upstream element's substrate (e.g. another particulate filter or a catalyst) is active. Select it to suppress this thermal coupling (notice that this is only relevant Couple to upstream element is selected. See Thermal page [76] Coupling (Substrates) for details). 5.1.4.2. Type Specification 5.1.4.2.1. Channel Structure This section summarizes the different channel geometries which can be chosen for the Filter Substrate. 5.1.4.2.1.1. Square Cell + Asymmetrical Cell PF Click on Square + Asymmetrical Cell PF to obtain the parameter specification of the square cell PF. Typical Values and Ranges Cell density (CPSI) Determines the type of monolith: Number of channels 2 per in . 224

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2

100-900 (1/in )

5. BOOST Aftertreatment Wall thickness

Determines the thickness of the monolith's walls = Wall.

0.006-0.015 (in)

Enable Enables the calculation for asymmetrical channel Asymmetrical diameters. Channel Diameters

Off (default)

Ratio of Channel Diameters

1-1.4 (-)

Determines the ratio of the channel diameters (d1/d2, page [144] see Fig. 46 ).

5.1.4.2.1.2. Simplified Square Cell PF Click on Simplified Square Cell PF to obtain the parameter specification of the square cell PF with equal inlet and outlet channel diameter. The simplified square cell PF corresponds to a Square + Asymmetrical Cell PF with diameter ratio of 1. Typical Values and Ranges Open frontal area (OFA)

Determines the open frontal area (= fluid volume fraction) of monolith ( g).

0.5-0.75 (-)

Hydraulic diameter

Determines the hydraulic diameter of the monolith (d). 0.001-0.005 (m)

5.1.4.2.1.3. Hexahex Click on Hexahex to obtain the following parameter specification. Typical Values and Ranges 2

Cell density (CPSI) Determines the total number of inlet and outlet 2 channels per in .

200-500 (1/in )

Wall thickness

Determines the thickness of the monolith's walls = Wall.

0.004-0.015 (in)

Inlet Channel Side Ratio (a/b)

Determines the ratio between the side lengths a and b of the hexagonal inlet channel.

0.666 (-) (default)

Perimeter Efficiency (a)

Since the side length a is located adjacent to another inlet channel wall of side length a, it is expected that there is reduced filtration along this wall. The Perimeter Efficiency determines the fraction of the side length used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall

0.0-1.0 (-)

5.1.4.2.1.4. Hex3 Click on Hex3 to obtain the following parameter specification. Typical Values and Ranges 2

Cell density (CPSI) Determines the total number of inlet and outlet 2 channels per in .

200-500 (1/in )

Wall thickness

0.004-0.015 (in)

Determines the thickness of the monolith's walls = Wall.

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5. BOOST Aftertreatment Inlet Channel Side Ratio (a/b)

Determines the ratio between the side lengths a and b of the hexagonal inlet channel.

0.81 (-) (default)

Perimeter Efficiency (a)

Since the side length a is located adjacent to another inlet channel wall of side length a, it is expected that there is reduced filtration along this wall. The Perimeter Efficiency determines the fraction of the side length used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall

0.0-1.0 (-)

5.1.4.2.1.5. General Cell PF Click on General Cell PF to obtain the parameter specification of any arbitrary inlet channel geometry which can be reproduced by multiple reflection of the general symmetry element (GSE). Note, the GSE is the geometrical base of the PF inlet channel geometries in BOOST/ FIRE since it determines the formation and structure of the soot and ash layer. The Unity Cell represents the smallest repetitive element for reflection to represent the PF geometry consisting of inlet and outlet channels. Typical Values and Ranges 100-900 (1/in )

Nr of Inlet Determines the number of inlet channels per unity Channels per Unity cell. Cell

1-3 (-)

Nr of Outlet Determines the number of outlet channels per unity Channels per Unity cell. Cell

1 (-)

Nr of GSEs per Inlet Channel

Determines the number of general symmetry elements per single inlet channel.

1-12 (-)

Wall thickness

Determines the thickness of the monolith's walls = wall.

0.004-0.015 (-)

Center Corner Determines the sum of the angles Angle (alpha+beta) general symmetry element.

226

2

Cell density (CPSI) Determines the total number of inlet and outlet 2 channels per in .

and

of the

45-90 (deg)

Right Corner Angle (gamma)

Determines the angle

of the GSE.

45-90 (deg)

Left Corner Angle (phi)

Determines the angle

of the GSE.

45-90 (deg)

Side length (l1)

Determines the length of the first side along the channel wall of the GSE.

0.1-1 (mm)

Side length (l2)

Determines the length of the second side along the channel wall of the GSE.

0.1-1 (mm)

Filtration Efficiency at l1

The Filtration Efficiency determines the faction of the side length l1 used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall.

0-1 (-)

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment Filtration Efficiency at l2

The Filtration Efficiency determines the fraction of 0-1 (-) the side length l2 used for filtration and is in the range between 0. and 1. 1. soot deposition along the entire wall 0. no soot deposition along this wall.

Channel Shape Factor

Determines the difference of the pressure drop due to the gas flow in the channels between the present channel and a channel of circular shape. The shape factor is 0.89 for squared channels 0.95 for hexagonal channels 0.98 for octagonal channels, and 1.0 for channels with circular cross-section.

Outlet Channel Perimeter

Determines the perimeter of the single outlet channel. 1-10 (mm)

Outlet Channel Cross Section

Determines the cross-section of the single outlet channel.

0.5-1 (-)

2

0.5-5 (mm )

5.1.4.2.2. Filter Type At this page information about the position of the Channel Plugs has to be given. Two Filter Types with different Channel Plugging are available: Activate Wall Flow Filter to chose the standard Particulate Filter plugged at the front (outlet channels) and at the rear (inlet channels). Activate Partial Wall Flow Filter to chose a Particulate Filter plugged only at the front (i.e. with page [57] removed inlet channel plugs) . For more info see Modelling a Partial Wall Flow Filter . 5.1.4.3. Soot and Filter Properties Select Soot and Filter Properties in the parameter tree to access the following input fields. The soot and filter properties comprise thermodynamic data of the soot and fluid mechanic information of the soot and the filter. Additionally a particle mass can be specified that is used as initial condition for all soot mass balances. 5.1.4.3.1. Soot Layer Properties Typical Values and Ranges 3

Layer Packing Density

Determines the packing density of the soot.

5-30 (kg/m )

Migration Constant

Determines the impact of soot migration due to a convective transport.

1E-15-1E-5 (-)

5.1.4.3.2. Pressure Drop Typical Values and Ranges 2

Wall Permeability

Determines the permeability of the filter wall.

1E-15-1E-12 (m )

Soot Permeability

Determines the permeability of the soot bed. This property may be specified as one of: • Constant • Table (dependent on temperature or wall velocity)

1E-16-1E-13 (m )

FIRE BOOST Aftertreatment

2

227

5. BOOST Aftertreatment • Map (dependent on both, temperature and wall velocity) • Formula (see. Soot Permeability page [50]) Enable Depth Filtration

Enables the application of a depth filtration layer in addition to a cake filtration layer

Off (default)

Sublayer Thickness

Determines the thickness of the depth flirtation layer.

10-100 (micron)

Depth Filtration Threshold

Determines the maximum soot loading that can be deposited within the depth filtration layer

0-3 (g/l)

Depth Filtration Permeability

Determines the permeability of the soot depth filtration layer

1E-16-1E-13 (m )

Inlet Loss Coefficient

Friction factor for pressure losses at the inlet.

0.5-10 (-)

Outlet Loss Coefficient

Friction factor for pressure losses at the outlet.

0.5-10 (-)

Consider Inlet/ Outlet Plugs

Enables the specification of inlet and outlet plugs closing the inlet and outlet channel at one site.

Off (default)

Length of PF Inlet- Determines the length of the inlet and outlet plugs. Outlet Plugs

2

0-20 (mm)

5.1.4.3.3. Filter Efficiency Typical Values and Ranges Soot Deposition Ratio

Determines the ratio between inlet soot mass and soot mass trapped in the Particulate Filter

0-1 (-)

5.1.4.3.4. Soot Mass Initialization Typical Values and Ranges 3

Soot Mass

Determines the Initial Soot Mass per Filter Volume. This property may be defined as • constant • table (dependent on the filter length)

5-30 (kg/m )

Max. fraction going to depth layer

The initial soot loading is partitioned proportionally between the depth and the cake layer, where 1.0 means all soot goes to the depth layer while 0.0 means all soot goes to the cake layer. Once the page [149] depth filtration threshold is reached, the remaining soot goes to the cake layer.

0-1(-)

5.1.4.4. Ash Properties Select Ash Properties in the parameter tree to access the following input fields. Typical Values and Ranges Enable Ash Model 228

If On/Off is selected, the ash model is activated.

FIRE BOOST Aftertreatment

Off (default)

5. BOOST Aftertreatment 3

Ash Packing Density

Determines the packing density of the ash layer.

100-500 (kg/m )

Ash Permeability

Determines the permeability of the ash layer.

1E-15-1E-13 (m )

Specify Ash Plug Fraction

Enables the distribution of the ash mass into a Layer and a Plug fraction

Off (default)

2

Ash Layer/Plug Determines the ratio of ash that is stored in the Distribution Factor ash layer to ash stored in the ash plug. A factor of 1 means all the ash is stored in the layer. A factor of 0 means all the ash is stored in the ash plug. If the ash loading is not specified as constant value but as function of the filter length, the shape of the axial profile is kept but scaled down by the ashdistribution factor.

(0-1) (-)

Ash Mass

0-100 (g/l)

Determines the initial ash loading in the filter. This property can be specified as a constant value, as a function of the filter length or as a formula. Click on

to define table or formula data.

5.1.4.5. Chemical Reactions BOOST has four different pre-defined reaction models for the simulation of soot regeneration. The reaction model can be applied to two different reaction zones, an upper and a catalytic sub-layer. For both layers one and the same reaction approach is applied, where the user has access to all reaction parameters. The reaction scheme in the sub layer can only be activated if the Depth Filtration Model is also enabled. The parameters can be defined separately for each reaction layer. Additionally the user can specify an arbitrary number of coating zones which are applied to all catalytically supported reactions (depth filtration layer, filter wall and outlet channel). Each kinetic parameter of a chosen catalytically supported reaction can be individually specified for each Coating Zone. Together with the O2-thermal and O2-fuel-additive Soot Regeneration Mode the Oxygen diffusion into the soot layer can be considered. Therefore a lumped diffusion coefficient has to be specified. In the catalytic wall layer, a pre-defined reaction model is available with full access to all reaction parameters. Furthermore there is the possibility for the user to define a kinetic model with an page [132] arbitrary number of catalytic reactions (see section Stoichiometry Specification and section page [133] Kinetic Parameters Specification ). Note that all reaction parameters were chosen for one type of regeneration simulation. For other filter applications these reaction parameters may change and therefore have to be supplied by the user. Enable O2 Diffusion into Soot Layer Lumped DiffusionCoefficient

On /Off -6

-5

2

Coefficient for the concentration gradient driven O2 10 -10 (m /s) diffusion from the inlet channel into the soot layer.

Soot Regeneration Mode None

No reactions are taken into account. In this case sub-layer reactions cannot be specified.

O2-thermal

A reaction mechanism (see Section Filter Regeneration with Oxygen [90] ) consisting of two reactions is applied. Soot is oxidized depending on the temperature range either to CO or to CO2.

page

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5. BOOST Aftertreatment O2-fuel-additive

The same reaction mechanism as given by O2-thermal is set up.

O2-NO2

In addition to the reaction mechanism of O2-thermal, a soot oxidation reaction in presence of NO2 can be used and specified. Details of this NO2 reaction are explained in Section Filter Regeneration with Oxygen page [91] and Nitric Dioxide .

O2-NO2-NO2catalytic

In addition to the reaction mechanism of O2-NO2 the reversible oxidation of NO to NO2 is taken into account. As explained in Section page [92] Filter CSF Catalytic Reactions , this reaction is catalytically supported and takes place in the sub-layer that can be specified. In the upper layer the reaction can be switched off by setting the appropriate reaction constants.

User Defined

This enables the possibility to supply user-defined soot regeneration models. The specification of these models is described in section page [132] Stoichiometry Specification and section Kinetic Parameters page [133] Specification .

PF Zone Coating Table

An arbitrary number of Coating Zones can be inserted for which dimensionless section lengths have to be defined. The sum of all section lengths has to be one.

Regeneration Mode Sublayer Toggle switch

This enables or disables the application of soot sub-layer reactions. The switch only can be activated if the Depth Filtration Model is also enabled.

Catalytic Wall Reactions None

No catalytic wall reactions are taken into account.

CO-HC-NOConversion

A pre-defined reaction mechanism for the catalytically supported conversion of CO, C3H6, C3H8 and NO is enabled.

Selective Catalytic Reduction

A predefined reaction mechanism for the catalytically supported SCR reactions is enabled.

User Defined

This enables the possibility to supply user-defined wall reaction models. The specification of these models is described in section Stoichiometry page [132] page [133] Specification and section Kinetic Parameters Specification .

Fraction of Catalytic Wall Height

Determines a fraction of the entire wall height that is catalytically active. A fraction of 1 comprises the entire wall height.

0-1 (-)

Catalytic Reactions Outlet Channel Enable Outlet Channel Reactions Mass Transfer Scaling Factor

This specifies a factor for the linear scaling of the mass transfer from the outlet channel bulk to the catalytic filter wall.

On/Off

Note: The activation of Regeneration Mode Sublayer is only possible if depth filtration is activated (Enable Depth Filtration at Soot and Filter Properties). 230

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment 5.1.4.5.1. Soot Regeneration Mode O2 - Thermal

O2 - Fuel Additive

K

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

Ef

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

K

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user

FIRE BOOST Aftertreatment

231

5. BOOST Aftertreatment can choose the table option to specify individual values for each coating section. Ef

O2 - NO2

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

O2 K1

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E1

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

Ef

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

NO2

232

K3

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E3

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment O2 - NO2-NO2-Catalytic O2 K1

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E1

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

kf

Determines a frequency factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

qf

Determines an exponential factor in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

Ef

Determines an activation energy in the CO/CO2 shift reaction (see Section Filter Regeneration with page [90] Oxygen ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

NO2 K3-K4

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

E3-E4

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

NO2- Catalytic K5

Determines a frequency factor used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table

FIRE BOOST Aftertreatment

233

5. BOOST Aftertreatment option to specify individual values for each coating section. E5

Determines an activation energy used in the predefined regeneration mechanism (see Section page [92] Filter CSF Catalytic Reactions ). In the catalytic sublayer the user can choose the table option to specify individual values for each coating section.

5.1.4.5.2. Catalytic Wall Reactions The different reactions can be enabled/disabled individually by clicking the corresponding check boxes. This enables sub-pages for the detailed specification of the reaction parameters. The string "all" means that a certain reaction is activated in all PF Coating Sections, but it is also possible to replace "all" with specific coating section numbers separated by commas (e.g. "1,3,4"). 5.1.4.5.2.1. CO, HC and NO Oxidation R1: CO Oxidation

R2: C3H6 Oxidation

R3: C3H8 Oxidation

234

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

K1 - K5

Determine the frequency factors used in the pre-defined Langmuir-Hinshelwood conversion mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section.

E1 - E5

Determine the activation temperatures used in the pre-defined Langmuir-Hinshelwood conversion

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment mechanism (see Section Filter CSF Catalytic page [92] Reactions ). The user can choose the table option to specify individual values for each coating section. R4: NO Oxidation

K

Determines the frequency factor used in the pre-defined reversible power-law conversion mechanism (see Section TWC Catalyst Reactions page [78] ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined reversible power-law conversion mechanism (see Section TWC Catalyst Reactions page [78] ). The user can choose the table option to specify individual values for each coating section.

5.1.4.5.2.2. Selective Catalytic Reduction R1-R2: NH3 Adsoprtion, Desorption

NH3 Storage Capacity

Determines the maximum amount of ammonia that can be stored at the solid surface site (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

Initial Surface Coverage Fraction of NH3

Determines the coverage fraction of NH3 at the solid surface. This property can be specified as constant value or as function of the catalyst length. The user can choose the table option to specify individual values for each coating section. Typical Values & Ranges: 0-1[-]

Coverage Determines a surface coverage dependency in Dependency the pre-defined ad-/desorption mechanisms (see (epsilon) Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section. Typical Values & Ranges: 0-1[-] Max Surface Coverage Fraction of NH3

Determines the maximum surface coverage fraction of NH3 at the solid surface. This property can be specified as constant value or as function of temperature. The user can choose the table option to specify individual values for each coating section.

NH3 Surface Coverage Fraction Dependency m

Determines the adsorption rate dependence of the NH3 surface coverage fraction. The user can choose the table option to specify individual values for each coating section.

K1 - K2

Determine frequency factors used in the predefined ad/desorption mechanisms (see Section HSO-SCR Catalyst Reactions, Transient Approach

FIRE BOOST Aftertreatment

235

5. BOOST Aftertreatment page [83]

). The user can choose the table option to specify individual values for each coating section.

R3: NO Reduction

R4: NOx Reduction

R5: NO2 Reduction

236

E1 - E2

Determine the activation temperatures used in the pre-defined ad-/desorption mechanisms (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

Critical Surface Coverage

Determines a tuning factor that slows down the reaction rate above a critical surface coverage (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the predefined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

Critical Surface Coverage

Determines a tuning factor that slows down the reaction rate above a critical surface coverage (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the predefined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

Critical Surface Coverage

Determines a tuning factor that slows down the reaction rate above a critical surface coverage (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment option to specify individual values for each coating section.

R6: NH3 Oxidation (Transient Approach)

K

Determines the frequency factor used in the predefined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the pre-defined transient oxidation mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient oxidation (see Section HSOpage SCR Catalyst Reactions, Transient Approach [83] ). The user can choose the table option to specify individual values for each coating section.

R7: NH3 Oxidation K (Steady-State Approach)

Determines the frequency factor used in the predefined power-law oxidation mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-power-law transient oxidation (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

R8: NO Oxidation

Rate Approach 1 K

Determines the frequency factor used in the pre-defined transient and reversible power-law conversion mechanism (see Section HSO-SCR page [83] Catalyst Reactions, Transient Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined transient and reversible power-law conversion mechanism (see Section HSO-SCR page [83] Catalyst Reactions, Transient Approach ).

FIRE BOOST Aftertreatment

237

5. BOOST Aftertreatment The user can choose the table option to specify individual values for each coating section. A

Determines the temperature dependency used in the pre-defined reversible power-law conversion mechanism see Section HSO-SCR Catalyst page [83] Reactions, Transient Approach ). The user can choose the table option to specify individual values for each coating section.

Rate Approach 2

R9: NO2 Formation

K, KR

Determine the frequency factors used in the pre-defined transient and reversible power-law conversion mechanism, respectively (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

E, ER

Determine the activation temperatures used in the pre-defined transient and reversible power-law conversion mechanism, respectively (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

A, AR

Determine the temperature dependencies used in the pre-defined transient and reversible power-law conversion mechanism, respectively (see Section HSO-SCR Catalyst Reactions, Transient Approach page [83] ). The user can choose the table option to specify individual values for each coating section.

m

Modifies the NH3 dependency. The user can choose the table option to specify individual values for each coating section.

K

Determines the frequency factor used in the predefined power-law conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

E

Determines the activation temperature used in the pre-defined power-law conversion mechanism (see Section HSO-SCR Catalyst Reactions, Transient page [83] Approach ). The user can choose the table option to specify individual values for each coating section.

5.1.4.5.2.3. Catalytic Outlet Channel Reactions page [156] The same reaction set as defined in the Catalytic Wall Reactions Model is selected. Sub-pages for the detailed specification of the reaction parameters appear. The user can choose the table option to specify individual values for each coating section.

238

FIRE BOOST Aftertreatment

5. BOOST Aftertreatment 5.1.4.6. Chemical Reactions with Archive The user has the possibility to specify an arbitrary number of different particulate filter coating zones with specific dimensionless zone lengths. For each inserted Zone Soot Regeneration and Catalytic Gas Reaction mechanisms, developed by using the AVL User Coding Interface, have to be applied separately. Typical Values and Ranges Zone Name

User-given name for each PF Coating Zone

Zone_1 (default)

Zone length

Determines the dimensionless length for every PF Coating Zone. The sum over all zone lengths must be 1.0. The dimensioned zone length is determined by multiplication with the Length of Monolith.

0-1(-)

Regeneration

User-given name of the Regeneration model for each Coating Zone.

My_Regeneration1 (default)

Catalytic Gas Reactions

User-given name of the Catalytic Gas Reaction model for each Coating Zone.

My_Cat_Reaction1 (default)

5.1.4.6.1. Soot Regeneration Reactions An arbitrary number of different soot regeneration reaction models can be applied to two different reaction zones, a soot cake and a catalytic sub-layer (depth filtration layer). The reaction schemes in the sub-layer can only be activated if the Depth Filtration Model is also enabled. Note: The activation of Regeneration Mode Sublayer is only possible if depth filtration is activated (Enable Depth Filtration at Soot and Filter Properties). The soot regeneration reaction mechanisms can be developed using the AVL User Coding Interface. The result is a shared object (.so)/dynamic link library (DLL) that is linked to FIRE/ BOOST during run-time. The .so(s)/DLL(s) and public model parameters are stored in an .ucp and .uca file respectively, that needs to be specified in the file browser dialog for an inserted model by clicking Select Archive. After the .ucp/.uca file has been selected the public model parameters (e.g. kinetic parameters, reaction switches, ...) are loaded and can be edited by clicking Model Parameters. Clicking Reload Archive reloads the Archive from the selected row. In order to reset the Model Parameters with the default values from the AUCI model click "No" in the pop-up box "Keep current parameter values?". In order to create a soot regeneration reaction mechanism in the first place, the AVL User Coding Interface can be launched by clicking the button Edit Archive. 5.1.4.6.2. Catalytic Gas Reactions An arbitrary number of different catalytic gas reaction models can be applied to each particulate filter coating zone. The catalytic gas reaction mechanisms can be developed using the AVL User Coding Interface. The result is a shared object (.so)/dynamic link library (DLL) that is linked to FIRE/BOOST during run-time. The .so(s)/DLL(s) and public model parameters are stored in an .ucp and .uca file respectively, that needs to be specified in the file browser dialog for an inserted model by clicking Select Archive. After the .ucp/.uca file has been selected the public model parameters (e.g. kinetic parameters, reaction switches, ...) are loaded and can be edited separately for inlet channels, wall and outlet channels by clicking Wall, Inlet or Outlet Channel Model Parameters. Clicking Reload Archive reloads the Archive from the selected row. In order to reset the Model Parameters with the default values from the AUCI model click "No" in the pop-up box "Keep current parameter values?". In order to create a catalytic gas

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5. BOOST Aftertreatment reaction mechanism in the first place, the AVL User Coding Interface can be launched by clicking the button Edit Archive. Wall Reactions Enable Wall Reactions

On /Off

Catalytic Wall Fraction

0-1 (-)

Determines a fraction of the entire wall height that is catalytically active. A fraction of 1 comprises the entire wall height.

Inlet and Outlet Channel Reactions Enable Inlet Channel Reactions

On/Off

Mass Transfer Scaling Factor

1

This specifies a factor for the linear scaling of the mass transfer from the inlet channel bulk to the catalytic filter wall.

Enable Outlet Channel Reactions

On/Off

Mass Transfer Scaling Factor

1

This specifies a factor for the linear scaling of the mass transfer from the Outlet channel bulk to the catalytic filter wall.

Enable User Defined Mass Transfer Model

On/Off

User Coding Mass Transfer Model

A user Coding Mass Transfer Model needs to be specified by clicking Select Archive. In order to create a mass transfer mechanism in the first place, the AVL User Coding Interface can be launched by clicking the button Edit Archive.

Empty (default)

Effective Catalyst Loading

This specifies a factor for the linear scaling of the 1 reaction rates of the catalytic conversion reactions.

5.1.5. Aftertreatment Pipe For the simulation of pipes, a similar input procedure is required as described for the catalytic page [181] page [187] converter (see Section Run Information to Section Catalyst ). This means that run information, definitions of the gas and also solid species and boundary conditions have to be supplied by the user. The specification of the pipe itself also follows the input concept of the page [187] catalytic converter presented in Section Catalyst . 5.1.5.1. General Typical Values and Ranges

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Pipe Length

Determines the length of the pipe.

10-3000 (mm)

Number of Grid points

Determines the numerical discretization of the pipe.

5-50 (-)

Diameter

Determines the inner diameter of the pipe. This value can be set as constant or as function of pipe length.

10-300 (mm)

Bend Pipe

Enables the input of a pipe bending radius

Bending Radius

Determines the bending radius of the pipe. This value can be set as constant or as function of pipe length.

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5. BOOST Aftertreatment Laminar Friction Coeff

Determines a friction coefficient in the regime of 10-300 (-) laminar flow. This value can be set as constant or as function of pipe length.

Turbulent Friction

Switch to decide how the turbulent friction is specified. Either via a turbulent friction coefficient or a surface roughness

Friction Coefficient

Determines a friction coefficient in the regime of turbulent flow. This value can be set as constant or as function of pipe length.

Surface Roughness

Determines the surface roughness of the inner side 0.05-1 (mm) of the pipe wall. This value can be set as constant or as function of pipe length.

Friction Multiplyer

Determines a multiplier applied to the friction coefficient evaluated for the given surface roughness.

Gas-Wall Heat Transfer

Determines a heat transfer law applied for the heat exchange between the gas phase and the solid pipe wall

Heat Transfer Coefficient

Determines a constant heat transfer coefficient for the heat exchange between the gas phase and the solid pipe wall

10-500 (W/(m ·K))

Heat Transfer Factor

Determines a scaling factor that is applied to the chosen heat transfer model. This value can be set as constant or as function of pipe length.

0.1-10 (-)

Wall Temperature

Determines an initial wall temperature. This value can be set as constant or as function of pipe length.

273-1000 (K)

Variable Wall Temperature

Enables the transient simulation of the pipe wall. If not enabled, a constant pipe wall temperature is used in the model.

Chemistry

Within a pipe, homogeneous gas phase reactions can be taken into account. If activated, a chemistry set has to be referred through its key.

Couple to upstream element

Select to couple the pipe to an upstream element page via wall heat conduction (see Thermal Coupling [75] for details).

0.019 (-)

0.1-10 (-)

2

5.1.5.2. Variable Wall Temperature Typical Values and Ranges Solid Material Table

Add a solid wall layer by clicking on Insert.

Solid Material

Determines a solid material for a given wall layer. Click in the input field and select a material from the selection field. The properties of the solid material can be specified in the pull-down menu . The first line in the table

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5. BOOST Aftertreatment represents the innermost wall layer and the last line the outermost wall layer. Layer Thickness

Determines the thickness of each individual wall layer.

No. of Grid Points

Determines the numerical discretization of each wall 3-10(-) layer in radial direction.

Ambient Temperature

Determines the temperature of the ambient. This value is constant or a function of simulation time.

Radiation Sink Temperature

Determines the temperature used for the evaluation 273-1000 (K) of radiative heat transfer. This value is a constant or a function of simulation time.

Convection Model

Enables the application of a convection model for the external heat transfer from the pipe surface to the ambient.

Convection Coefficient

Enables the application of a convection coefficient for the external heat transfer from the pipe surface to the ambient.

Coolant

Determines a fluid which is assumed to flow around the pipe. Fluid properties of air and water are available.

Characteristic Determines the velocity of the coolant flowing Velocity of Coolant around the pipe. A cross-flow regime is assumed. Convection Coefficient

0.1-30 (mm)

273-1000 (K)

0.1-30(m/s) 2

Determines a convective heat transfer coefficient for 7-100 (W/(m ·K)) the external heat transfer. This value is constant or a function of simulation time.

5.1.5.3. Result Specification The following options are available: • Use Grid: All results are written at all the points of the computational grid. • Set Grid: All results are written at a user-defined equally spaced grid. • Use 5 Points: All results are written at an equally spaced grid of five points in both axial and radial (for the case of 2D simulations) direction. • User Defined: All results are written at the user-defined dimensionless coordinates in axial and radial (for the case of 2D simulations) direction. The following input data can be specified: Typical Values and Ranges

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Axial Output Points

Determines the number of equally spaced axial positions in the element at which all transient simulation results are written.

5-30 (-)

Radial Output Points

Determines the number of equally spaced radial positions in the element at which all transient simulation results are written. For a 1D simulation this value is set to 1. For a 2D simulation, all the

5-30 (-)

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5. BOOST Aftertreatment results are given on a mesh of (Axial Output Points x Radial Output Points). User Defined Axial, Radial

Determines dimensionless coordinates at which all transient simulation results are written. In 1D simulations, the radial coordinate is set to 0.

(0-1, 0-1) (-)

The Type of Results of all the transient results can be specified by the user as follows. • Reduced: A reduced set of mean and outlet values is written. • Standard: A standard set of results (temperatures, pressures, conversions, …) is written. • Standard, Properties: The standard set of results is extended by properties such as heat capacities, conductivities, transfer coefficients. • Standard, Fluxes: The standard set of results is extended by mass and heat fluxes. • Standard, Sources: The standard set of results is extended by sources from the individual chemical reactions. • All: All results, the standard set, properties, fluxes and sources are written. General information on how to use the BOOST post-processor and how to graphically display all the simulation results is available in the BOOST Users Guide and the IMPRESS Chart Users Guide.

5.1.6. Aftertreatment Injector The Aftertreatment Injector ( ) offers the possibility to introduce mass into the exhaust aftertreatment line downstream of the inlet boundary at a certain user-defined position. Injection of gases and liquids is possible. 5.1.6.1. General Specify the state of aggregation of the injected fluid: choose between gaseous and liquid. In case of liquid, the partitioning of the total injected mass between the various phases (gas phase, droplet, and wallfilm) may be set. Typical Values and Ranges General Injection Mass Flow

Determines the injected mass flow. This value can be set as constant or as a function of time.

Injection Temperature

Determines the temperature of the injected mass.

Injected fluid specification

Choose between gaseous and liquid.

Liquid Injected Fluid phase partitioning Note: All of the settings in this block are only relevant/enabled when liquid is chosen at the Injected fluid specification radio button group above. Injected fluid

Choose between • 1. to Gas Phase only (instantaneous decomp./evap)

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5. BOOST Aftertreatment • 2. to Liquid Phase only • 3. partition among Gas/Liquid Phases Choosing cases 2 and 3 invokes a Liquid Phase. For case 3, the Fraction of Injected Fluid to Gas Phase may be chosen. This determines the part of the total injected mass going to the Gas Phase, while the rest of the mass goes to the Liquid Phase. Liquid Phase

Choose between • 4. Droplets only • 5. Wallfilm only • 6. partition among Droplets/Wallfilm Choosing cases 5 and 6 enables the Wallfilm. For case 6, the Fraction of Liquid Phase to Wallfilm may be entered. This determines the portion of the liquid phase mass that goes to the Wallfilm; the rest of the mass is transported as a separate droplet phase (see Liquid Species page [75] Transport ).

Partitioning summary

This read-only block gives an overview about the fractions of the total injected mass which go to the gas phase, the droplet phase, and the wallfilm phase, respectively.

Liquid Injected Fluid Phase Partitioning The following scheme illustrates the possibilities of partitioning an injected liquid among the various phases:

The decisions how to partition the injected mass are done via the radio buttons 1-6. Radio buttons 1-3 decide the first level (gas vs. liquid phase), while buttons 4-6 decide the second level (wallfilm vs. droplets). 5.1.6.2. Gaseous Injected Fluid Specify the composition of the gaseous injected fluid. Select the species fraction unit from the pull-down menu Unit of Species; possible options are 'Mass Fraction (kg/kg)' and 'Mole Fraction (mol/mol)'. Add/remove species with Insert/Remove. Click on a Species input field to open a list of possible species that have been specified previously in Simulation | Control | Aftertreatment Analysis in the Gas Composition table. Enter a mass fraction; possible values are 0-1 (-). The total sum of mass fractions has to be 1, the font color will be red when this criterion is not fulfilled; it can be corrected by choosing a row and clicking Correct; the correction will be applied to the selected row. Load and store tables by clicking the corresponding buttons. 244

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5. BOOST Aftertreatment 5.1.6.3. Liquid Injected Fluid Specify the composition of the liquid injected fluid. Add/remove liquids with Insert Liquid/Remove Liquid. Click on a Liquid input field to open a list of possible liquids that have been specified beforehand in Model | Liquid Materials. Enter a mass fraction; possible values are 0-1 (-). Note: The total sum of mass fractions has to be 1. For each of the liquids in the table, a new sub page [n] Composition of is available. On each of these pages, there are two input tables in which you may enter: 1. the gas species the liquid is mapped to upon decomposition/evaporation (e.g. WATER may evaporate to H2O, or UREA may decompose into HNCO and NH3). 2. possible liquid sub-species the liquid may consist of (e.g. ADBLUE may be mapped onto the liquid species UREA and WATER) page [243] The tables are active (and need input) depending on the settings done on the General page. Table 1 is inactive when radio button 4 is selected, Table 2 is inactive when radio button 1 is selected. 5.1.6.3.1. Composition of Injected Liquid For each specified liquid at the Liquid Injected Fluid Window a 'Composition of Injected Liquid' page will be enabled. Here, specify the stoichiometric composition of the liquid, i.e. onto which gas species the liquid will be mapped. The procedure works the same as for the 'Gaseous Injected Fluid'. The only difference is that mass fractions can be negative too, which refers to consumption of a certain gas species; still, the total sum of mass fractions has to be 1. Below that table, some examples of how to map a liquid onto gas species are displayed. 5.1.6.4. Wallfilm Modeling This is activated if Liquid is specified as the injected fluid. Select Enable Wallfilm Modeling to access the options. Typical Values and Ranges Wallfilm Thickness

Determines the thickness of the wallfilm.

Fraction of Liquid to Wallfilm

Determines the fraction of liquid mass directly stored in the wallfilm after injection.

Evaporation Rate Multiplier

Determines a multiplier for the evaporation rate.

5.1.6.5. Result Specification The following options are available: • Use Grid: All results are written at all the points of the computational grid. • Set Grid: All results are written at a user-defined equally spaced grid. • Use 5 Points: All results are written at an equally spaced grid of five points in both axial and radial (for the case of 2D simulations) direction. • User Defined: All results are written at the user defined dimensionless coordinates in axial and radial (for the case of 2D simulations) direction. The following input data can be specified:

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5. BOOST Aftertreatment Typical Values and Ranges Axial Output Points

Determines the number of equally spaced axial positions in the element at which all transient simulation results are written.

5-30 (-)

Radial Output Points

Determines the number of equally spaced radial 5-30 (-) positions in the element at which all transient simulation results are written. For a 1D simulation, this value is set to 1. For a 2D simulation, all the results are given on a mesh of (Axial Output Points x Radial Output Points).

User Defined Axial, Radial

Determines dimensionless coordinates at which all transient simulation results are written. In 1D simulations, the radial coordinate is set to 0.

(0-1, 0-1) (-)

The Type of Results of all the transient results can be specified by the user as follows. • Reduced: A reduced set of mean and outlet values is written. • Standard: A standard set of results (temperatures, pressures, conversions, …) is written. • Standard, Properties: The standard set of results is extended by properties such as heat capacities, conductivities, transfer coefficients. • Standard, Fluxes: The standard set of results is extended by mass and heat fluxes. • Standard, Sources: The standard set of results is extended by sources from the individual chemical reactions. • All: All results, the standard set, properties, fluxes and sources are written. General information on how to use the BOOST post-processor and how to graphically display all the simulation results is available in the BOOST Users Guide and the IMPRESS Chart Users Guide.

5.1.7. Control Elements 5.1.7.1. Temperature Sensor The Temperature Sensor component can be used to sense gas temperatures from different components (Aftertreatment Pipe, Catalyst, Particulate Filter). For the simulation of the temperature sensor model, the below input is required and described. page [73] Details of the physical model are explained in section Temperature Sensor Model . General Typical Values and Ranges

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Length

Determines the length of the thermocouple.

5-100 (mm)

Diameter

Determines the diameter of the thermocouple.

0.1-1 (mm)

Number of grid points

Determines the numerical discretization of the thermocouple with respect to spatial dimension x.

5-50 (-)

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Determines whether heat radiation between the thermocouple and the wall is considered in the calculation of the thermocouple temperature.

Initial Temperature Determines the initial temperature of the thermocouple. Material

Determines a solid material for the thermocouple. Click in the input field and select a material from the selection field. The properties of the solid material can be specified in the pull-down menu .

Sampling Rate

Determines a sampling rate with which the thermocouple signal is sampled.

273-1000 (K)

1 - 1000 (Hz)

Sensor Channels Variable

Specify a name for the sensor channel.

Element

Select an element to with which the Temperature Sensor shall be connected.

Sensor Channel

Select a sensor channel out of the list of available sensor channels of the connected element. Note: The Temperature Sensor can process only gas temperatures. Therefore select only those sensor channels which refer to a gas temperature. The BOOST calculation kernel will stop with an appropriate error message if a sensor channel other than a gas temperature has been selected.

Output Channels Tip: For every sensor channel in the Temperature Sensor element a corresponding output channel will be generated that can be sensed by another Control Element, for example when considering the Temperature Sensor in a control unit. 5.1.7.2. Formula Interpreter The Formula Interpreter Element ( ) can be used to 1. sense values (i.e. maximum temperatures, conversion rates, …) from different components (Catalyst, Particulate Filter, Pipe, Aftertreatment Injector) 2. perform calculations with these values (C-code that is interpreted by BOOST and executed after each calculation step (the time step is taken from the input field 'Result Output Interval' on the page the Global | Aftertreatment Analysis) 3. actuate values (mass flow, temperature, …) at different components (Aftertreatment Boundary) For a detailed description on how to handle the Formula Interpreter Element please refer to section 4.16.6 of the BOOST Users Guide. BOOST Aftertreatment offers the following pre-defined function to be used in the Formula Interpreter: • bst_terminate_atm() is terminating the current simulation run.

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5. BOOST Aftertreatment Figure 60. Formula Interpreter - Formula Specification

5.1.7.3. Engine Interface For a detailed description of how to handle the Engine Interface Element ( section 4.16.4 of the BOOST Users Guide.

) please refer to

5.1.7.4. PID Controller For a detailed description of how to handle the PID Controller Element ( section 4.16.5 of the BOOST Users Guide.

) please refer to

5.1.7.5. Monitor The Monitor Element ( ) can be used to sense values (i.e. maximum temperatures, conversion rates, …) from different components (Catalyst, Particulate Filter, Pipe, Formula Interpreter). The monitored values are shown in the Online Monitor (accessed from the Simulation Status dialog, Monitor button) and in an individual section of the results-tree in IMPRESS Chart. For a detailed description on how to handle the Monitor Element please refer to section 4.16.7 of the BOOST Users Guide. Figure 61. Monitor - Sensor Specification

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5. BOOST Aftertreatment 5.1.8. Solid Materials An arbitrary list of solid materials can be specified on the input page 'Solid Material'. The page can be accessed from the pull-down menu item 'Model'. By right-clicking on the entry 'Material' in the tree at the left side of the page, new material pages can be added. Currently the properties of steel and air are supplied with default values. Typical Values and Ranges Material Name

Determines a name for the material. Via this name the material properties can be accessed from the page 'Pipe-Variable Wall Temperature'.

Density

Determines the density of the material.

1-6000 (kg/m )

Thermal Conductivity

Determines the thermal conductivity of the material. This value can be set constant or as function of temperature.

0.01-50 (W/(m·K))

Specific Heat

Determines the specific heat of the material. This value can be set constant or as function of temperature.

500-2000 (J/ (kg·K))

Opaque

Enable the input of emissivities of the inner and outer surface of opaque (non-transparent) materials.

Emissivity inner

Determines an emissivity at the inner surface of an opaque material.

0-1 (-)

Emissivity outer

Determines an emissivity at the outer surface of an opaque material.

0-1 (-)

3

5.1.9. Liquid Materials An arbitrary list of liquid materials can be specified under Model | Liquid Materials. To add a new material, right-click on Material in the tree and select Material : Add from the sub-menu. Currently, properties of the following liquid materials are supplied with default values: Water, UREA, AdBlue and Diesel. Note that UREA is not treated as a liquid by BOOST, but dummy values (e.g. from water) have to be specified for all properties except 'Molar Weight'. Typical Values and Ranges Material Name

Determines a name for the material. Via this name the material properties can be accessed from Aftertreatment Injector - Liquid Injected Fluid.

Molar Weight

Determines the molar weight of the liquid.

Liquid Density

Determines the density of the liquid. This value can be set constant or as a function of temperature.

Specific Heat

Determines the specific heat of the liquid. This value can be set constant or as a function of temperature.

Thermal Conductivity

Determines the thermal conductivity of the liquid. This value can be set constant or as a function of temperature.

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5. BOOST Aftertreatment Heat of Evaporation

Determines the heat of evaporation of the liquid. This value can be set constant or as a function of temperature.

Vapor Pressure

Determines the vapor pressure of the liquid. This value can be set constant or as a function of temperature.

5.1.10. Homogenous Gas Phase Reactions - Input data The Homogenous Gas Phase Reactions chemistry interpreter needs a text based chemistry input file with an arbitrary name, where the stoichiometries of the reactions, the kinetic Parameters (A, b and E) and – optionally – auxiliary data are defined. The reaction specification part begins with 'REACTIONS' and ends with 'END'. The number of blanks or empty lines between specification blocks/lines is arbitrary. Comment lines beginning with '!' are allowed. Example for such a chemistry input file:

REACTIONS 2O+MO2+M 1.200E+17 -1.000 .00 H2/2.40/ H2O/15.40/ CH4/2.00/ CO/1.75/ CO2/3.60/ C2H6/3.00/ AR/ .83/ O+H+MOH+M 5.000E+17 -1.000 .00 H2/2.00/ H2O/6.00/ CH4/2.00/ CO/1.50/ CO2/2.00/ C2H6/3.00/ AR/ .70/ O+H2H+OH 3.870E+04 2.700 6260.00 END The chemistry interpreter reads this input file during the preprocessing and creates an Info file ('input_file_name'_out.dat in the input file directory) with the specified chemistry. Currently about 95% of the auxiliary-keywords known by the CHEMKIN-II Version 4.9, April 1994, DOUBLE PRECISION are considered by the interpreter. Therefore it is capable of reading and interpreting the corresponding chem.inp files.

5.1.11. Input Data Checklist: Catalytic Converter and Particulate Filter The purpose of the following checklist is to give a brief overview of which input data has to be supplied and specified by the user in order to run BOOST aftertreatment simulations. CAT/PF Start Time Global Information End Time

CAT/PF Inlet/Outlet Conditions

Determines the beginning of the simulation, i.e. the start time of the integration Determines the end of the simulation, i.e. the end time of the integration

Gas Composition

Determines the number and type of gas species transported through the system

Solid Species

Determines the number and type of solid components transported by the gas flux

Inlet Mass Flux

Determines the mass entering the aftertreatment element

Inlet Gas Temperature

Determines the temperature of the gas flux entering the aftertreatment element.

Inlet Gas Fractions Determines the mass (or mole) fractions of all the gas species defined Inlet Solid Mass Fractions 250

Determines the mass flux of the solid species as a fraction of the gas mass flux

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CAT/PF Monolith Geometry

CAT/PF Friction

CAT/PF Solid Properties

CAT/PF Radial Heat Loss Conditions

Outlet Pressure

Determines the pressure at the outlet of the aftertreatment element

Monolith Volume

Determines the volume of the monolith comprising both, the volume of the gas phase and the volume of the solid substrate

Monolith Length

Determines the length of the monolith

Cell density (CPSI)

Determines the cell structure using the number of 2 channels per in

Wall thickness

Determines the thickness of the monolith's walls

Washcoat thickness

Determines the thickness of the washcoat

Friction Coefficient Determines a friction coefficient in the case of turbulent flow Friction Multiplier

Determines a dimensionless factor that considers the influence of the channel shape in the case of laminar flow

Density

Determines the density of the monolith material

Thermal Conductivity

Determines the thermal conductivity of the monolith material

Specific Heat

Determines the specific heat of the monolith material

External Heat Transfer Coefficient

Determines the heat transfer between the shell and the environment

Thickness, Shell, Insulation Mat

Determines the thickness of the shell

Thermal Determines the thermal conductivity of the shell Conductivity, Shell, Insulation Mat

CAT Reactions

PF Physical Properties

Environment Temperature

Determines the temperature of the environment

Conversion Reactions

Determines the application of conversion model. Predefined reaction models can be chosen and adapted.

Surface Storage

Determines the application of surface storage mechanisms. Pre-defined reactions can be chosen and adapted by the user.

Density, Soot

Determines the packing density of the soot

Migration Constant Determines the impact of soot migration due to convective transport Wall Permeability

Determines the permeability of the filter wall

Soot Permeability

Determines the permeability of the soot bed

Soot Mass

Determines a volume specific soot mass that is used as initial conditions for all soot balances

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5. BOOST Aftertreatment PF Reactions

Regeneration Modes

Determines the application of pre-defined regeneration modes. It can be chosen between bare-trap, fuel additive, NO2 and catalytically supported NO2 regeneration.

5.1.12. Best Practice In general, speed-up and stability of simulations are antagonists. Speed-up is often reached through model reduction and simplification, while at the same time stability is lost when the resulting model is not capable anymore to handle the applied boundary conditions and transience resulting from model physics and chemistry. Both aspects – the simulation time and the model stability – are influenced by the simulation model set-up on the one hand and the solver settings on the other hand. In the below sections selected model and solver input is presented, that definitely influences speed-up and stability. 5.1.12.1. Simulation Model Set-up In order to ensure fast and at the same time stable simulations there are certain things to be considered during set-up of the BOOST Aftertreatment simulation model that are comprised in this section. The sections for the input data regarding the Aftertreatment components offer typical values and ranges for most of the input data. Dependent on the actual simulation model some inputs need to get special attention and are to be chosen thoroughly. General Remarks • A smaller number of grid points speeds up the simulation, whereas increasing the number of grid points leads to higher stability. • For multi-component systems, i.e. simulation models with more than one exhaust aftertreatment component, the most stable flow solution has been detected for homogeneous axial discretization cell length. This means that the mean axial discretization cell lengths of all components have the same order of magnitude. The reason is of numerical nature: the BOOST Aftertreatment solver makes use of matrix inversion techniques. The subject matrix is the so called Jacobian, which is the first derivative of the system state with respect to the system solution state (temperature, pressure, species concentrations). As the single components are discretized in axial direction, the system state comprises all the states of the different axial discretization cells, and eventually the Jacobian contains entries for each axial discretization cell and their numerical relationship. The latter one simply reflects the physical processes between two axial discretization cells. As a matter of fact, the geometrical information of the system is also considered in the calculation of the Jacobian. Strongly inhomogeneous discretization now can lead to an illconditioned Jacobian, especially when the system is experiencing high transience and stiff kinetics. Such an ill-conditioned system is hard to solve, if at all. In contrast to that more or less homogeneous axial discretization improves the Jacobians conditioning and therefore stabilizes the entire simulation. As a side effect, the computation time is decreased as well, because the solver is not forced to do so many steps in order to converge. • If transient inlet/outlet boundary conditions are applied that result from experimental data, it if very useful to pre-process these data before loading them in the BOOST Aftertreatment model. Usually experimental data show “noise” which superposes the main effect, for example a temperature rise. This noise can be eliminated by applying the running average method to the experimental data. • It is also very helpful to specify the initial solid temperatures of the various components as the inlet gas temperature at simulation start time. Of course, this is obsolete if this heat-up/ cool-down is really intended to be modeled. Catalyst • In order to decrease computation time, it is always helpful to decrease the number of grid points. Anyhow due to experience a number of 10 to 15 works best in most of the cases. For non-reactive catalysts this number can even by decreased. If instability is detected it should be increased, especially when for example nearly all of the conversion occurs at the catalyst 252

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5. BOOST Aftertreatment front and/or when the reaction mechanism also contains surface storage reactions which lead to higher transience in the conversion behavior it is good to increase the number of grid points and choose a grid shape factor smaller 1.0 (for example 0.8). • The presented pre-defined reaction mechanisms with their default parametrization have been validated for specific washcoats as presented in the mentioned references. Particulate Filter (PF) • If the PF element is used as a simple pressure drop element only the number of grid points that typically leads to stable simulation is around 20-25. As soon as kinetics is enabled in the PF the number of grid points should be increased and experience shows that 50 is a good value. A larger number than 80 is known to be unsuitable due to very high computational effort and increasing instability resulting in multi-component systems from inhomogenous axial discretization lengths leading to an ill conditioned Jacobian matrix. • A grid shape factor of 1.0 has been experienced as to give the most stable solution. 5.1.12.2. Aftertreatment Solver Settings There are several possibilities to influence the solver performance. The below section summarizes recommendations how some solver characteristics can be set in order to decrease simulation time and increase stability. General Remarks • The smaller the time step the slower the simulation due to more post-processing calls (i.e. calculation and storage of results), whereas a larger time step can lead to instabilities, especially when a. the kinetics is very stiff, b. highly transient inlet conditions challenge the PF flow solver. • For very stiff problems the solver option “Enable High-Robustness Option” at Simulation | Control | Aftertreatment Analysis might lead to more stability. The main problems targeted with that option are a. “Freezing”: the solver seems to do nothing, but actually the solver is using very small time steps, that are far below the provided User time step (Simulation | Control | Aftertreatment Analysis) or DLL time step (set in external application SimuLink, NI Veristand, ...), b. Convergence Failure: the solver diverged, for example due to very stiff system. Note: An ill-conditioned Jacobian cannot be solved easier using the “HighRobustness” option. c. The applied solver tolerances of the BOOST Aftertreatment solution variables (temperature, pressure, species concentrations) have been chosen with high care. If for whatsoever reason the tolerances need to be adjusted, this can be done at Simulation | Control | Aftertreatment Analysis | Solver Options. The pre-defined tolerances are divided by the entered value; therefore values smaller 1.0 lead to more loose tolerances, whereas values larger 1.0 lead to stricter tolerances. User Defined Parameter The below table summarizes User Defined Parameters that allow additionally to the GUI input to influence the solver configuration and adjust other component parameter. The User Defined Parameters are grouped by component. Parameter Key

Value

Description

ATM Solver ATM_DISABLE_NAN_CHECK YES / NO

FIRE BOOST Aftertreatment

After each successful solver time step the solution vector is checked for NaN. In order 253

5. BOOST Aftertreatment Parameter Key

Value

Description save computation time this check might be disabled.

ATM_SET_NR_FAILSKIP

number

Change the number of allowed solver failure. Some failure are repairable, that’s why a number > 1 is suggested. Default is 20.

ATM_SOLVER_DFLT_OPT

ON / OFF

With BOOST v2009.1 enhancements in the solver performance have been introduced that led to significant speed-up. However in some cases lower stability might occur. By enabling the solver configuration (ON) before v2009.1 the simulation time will be in general significantly slower, but might be more stable on the other side.

ATM_DLL_SOLVER_OSETTINGS YES / NO

With BOOST v2011.1 enhancements in the solver performance regarding DLL applications have been introduced that led to significant speed-up. However in some cases lower stability might occur. By enabling the solver configuration (YES) before v2011.1 the simulation time will be in general slower, but might be more stable on the other side.

ATM_CONG_TOLFACTOR* >1.0: stricter