Thermodynamics (SI Units) Sie 6E_Cengel

Scilab Textbook Companion for Thermodynamics (SI Units) Sie 6E by Cengel1 Created by Karan Arora B-Tech Civil Engineering Indian Institute of Technology Roorkee College Teacher Not Applicable Cross-Checked by TechPassion October 4, 2013

1 Funded

by a grant from the National Mission on Education through ICT, http://spoken-tutorial.org/NMEICT-Intro. This Textbook Companion and Scilab codes written in it can be downloaded from the ”Textbook Companion Project” section at the website http://scilab.in

Book Description Title: Thermodynamics (SI Units) Sie 6E Author: Cengel Publisher: Tata McGraw - Hill Education Edition: 6 Year: 2008 ISBN: 0070262179

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Scilab numbering policy used in this document and the relation to the above book. Exa Example (Solved example) Eqn Equation (Particular equation of the above book) AP Appendix to Example(Scilab Code that is an Appednix to a particular Example of the above book) For example, Exa 3.51 means solved example 3.51 of this book. Sec 2.3 means a scilab code whose theory is explained in Section 2.3 of the book.

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Contents List of Scilab Codes

5

1 Introduction and Basic Concept

10

2 Energy Transfer and General Energy Analysis

15

3 Properties of Pure Substances

23

4 Energy Analysis of Closed Systems

32

5 Mass and Energy Analysis of Control Volumes

40

6 Mass and Energy Analysis of Control Volumes

52

7 Entropy

57

8 Exergy A Measure of Work Potential

74

9 Gas Power Cycle

86

10 Vapor and Combined Power Cycles

97

11 Refrigeration Cycles

108

12 Thermodynamic Property Relations

113

13 Gas Mixtures

117

14 Gas Vapour Mixtures and Air Conditioning

126

3

15 Chemical Reactions

134

16 Chemical and Phase Equilibrium

142

17 Compressible Flow

148

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List of Scilab Codes Exa Exa Exa Exa Exa Exa Exa

1.1 1.5 1.6 1.7 1.8 1.9 1.10

Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa

1.12 2.1 2.2 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.15 2.16 2.17 2.18 2.19 3.1 3.2 3.3 3.4 3.5

obtaining formulas for from unit considerations . . . . Absolute Pressure of a Vacuum Chamber . . . . . . . Measuring Pressure with nanometer . . . . . . . . . . Measuring pressure with multifluid manomete . . . . . Measuring Atmospheric Pressure with barometer . . . Effect of piston weight on Pressure of Cylinder . . . . Hydrostatic Pressure in a Solar Pond with Variable Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . Analyzing a Multifluid Manometer with EES . . . . . General energy analysis . . . . . . . . . . . . . . . . . Analysis of wind energy . . . . . . . . . . . . . . . . . Power Transmission by the Shaft of a Car . . . . . . . Power Needs of a Car to Climb a Hill . . . . . . . . . Power needs of a car to accelerate . . . . . . . . . . . Cooling of hot fluid in tank . . . . . . . . . . . . . . . Acceleration of air by fan . . . . . . . . . . . . . . . . Heating effect of a fan . . . . . . . . . . . . . . . . . . Annual lighting cost of a classroom . . . . . . . . . . . Cost of cooking with electric and gas charges . . . . . Performance of hydraulic turbine generator . . . . . . Cost Savings Associated with High Efficiency motors . Reducing air pollution by geothermal heating . . . . . Heat transfer from a person . . . . . . . . . . . . . . . Pressure of Saturated Liquid in a Tank . . . . . . . . . Temperature of Saturated Vapor in a Cylinder . . . . Volume and Energy Change during Evaporation . . . Pressure and Volume of a Saturated Mixture . . . . . Properties of Saturated Liquid Vapour Mixture . . . . 5

10 10 11 11 12 12 12 13 15 16 16 17 17 18 18 19 19 19 20 21 21 22 23 23 24 24 25

Exa 3.7 Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa

3.8 3.10 3.11 3.12 3.13 3.14 4.2 4.3 4.4 4.5 4.7 4.8 4.10 4.11 4.12 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8

Internal Energy of Superheated Vapor using linear interpolation . . . . . . . . . . . . . . . . . . . . . . . . Approximating Compressed Liquid as Saturated Liquid Mass of Air in a Room . . . . . . . . . . . . . . . . . . The Use of Generalized Charts . . . . . . . . . . . . . Using Generalized Charts to Determine Pressure . . . Different Methods of Evaluating Gas Pressure . . . . . Temperature Drop of a Lake Due to Evaporation . . . Boundary Work for a Constant Pressure Process . . . Isothermal Compression of an Ideal Gas . . . . . . . . Expansion of a Gas against a spring . . . . . . . . . . Electric Heating of a Gas at Constant Pressure . . . . Evaluation of the du of an Ideal Gas . . . . . . . . . . Heating of a Gas in a Tank by Stirring . . . . . . . . . Heating of a Gas at Constant Pressure . . . . . . . . . Enthalpy of Compressed Liquid . . . . . . . . . . . . . Cooling of an Iron Block by Water . . . . . . . . . . . water flow through garden hose nozzle . . . . . . . . . Discharge of water from a tank . . . . . . . . . . . . . Energy transport by mass . . . . . . . . . . . . . . . . Deceleration of air in diffuser . . . . . . . . . . . . . . Acceleration of steam in nozzle . . . . . . . . . . . . . Compressing air by compressor . . . . . . . . . . . . . Power generation by steam turbine . . . . . . . . . . . Expansion of refrigant 134a in refrigerator . . . . . . . Mixing of Hot and Cold Waters in a Shower . . . . . . Cooling of refrigant 134a by water . . . . . . . . . . . Electric heating of air in house . . . . . . . . . . . . . Charging of rigid tank by system . . . . . . . . . . . . Cooking with a pressure cooker . . . . . . . . . . . . . Net Power Production of a Heat Engine . . . . . . . . Fuel Consumption Rate of a Car . . . . . . . . . . . . Heat Rejection by a Refrigerator . . . . . . . . . . . . Heating a House by a Heat Pump . . . . . . . . . . . Analysis of a Carnot Heat Engine . . . . . . . . . . . A Questionable Claim for a Refrigerator . . . . . . . . Heating a House by a Carnot Heat Pump . . . . . . . Malfunction of a Refrigerator Light Switch . . . . . . 6

26 26 27 27 28 29 30 32 32 33 34 34 36 36 37 38 40 41 41 42 43 44 44 46 47 47 48 49 49 52 52 53 53 54 55 55 55

Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa

7.1 7.2 7.3 7.4 7.5 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14 7.15 7.16 7.17 7.18 7.19 7.21 7.22 7.23 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17

Entropy Change during an Isothermal Process . . . . . Entropy Generation during Heat Transfer Processes . Entropy Change of a Substance in a Tank . . . . . . . Entropy Change during a Constant Pressure Process . Isentropic Expansion of Steam in a Turbine . . . . . . Effect of Density of a Liquid on Entropy . . . . . . . . Economics of Replacing a Valve by a Turbine . . . . . Entropy Change of an Ideal Gas . . . . . . . . . . . . Isentropic Compression of Air in a Car Engine . . . . Isentropic Compression of an Ideal Gas . . . . . . . . Compressing a Substance in the Liquid versus Gas Phases Work Input for Various Compression Processes . . . . Isentropic Efficiency of a Steam Turbine . . . . . . . . Effect of Efficiency on Compressor Power Input . . . . Effect of Efficiency on Nozzle Exit Velocity . . . . . . Entropy Generation in a Wall . . . . . . . . . . . . . . Entropy Generation during a Throttling Process . . . Entropy Generated when a Hot Block Is Dropped in a Lake . . . . . . . . . . . . . . . . . . . . . . . . . . . . Entropy Generation Associated with Heat Transfer . . Energy and Cost Savings by Fixing Air Leaks . . . . . Reducing the Pressure Setting to Reduce Cost . . . . Maximum power generation by wind turbine . . . . . Exergy transfer from a furnace . . . . . . . . . . . . . The rate of irreversibility of a heat engine . . . . . . . Irreversibility during cooling of an iron block . . . . . Heating potential of a hot iron block . . . . . . . . . . Second law efficiency of resistance heaters . . . . . . . Work Potential of compressed air in tank . . . . . . . Exergy change during a compression process . . . . . . Exergy destruction during heat conduction . . . . . . Exergy destruction during expansion of steam . . . . . exergy destroyed during stirring of gas . . . . . . . . . Dropping of hot iron block in water . . . . . . . . . . Exergy destruction during heat transfer to a gas . . . second law analysis of steam turbine . . . . . . . . . . exergy destroyed during mixing of fluid streams . . . . Charging of compressed air storage system . . . . . . . 7

57 57 58 59 60 61 62 62 63 64 64 65 66 67 68 69 70 70 71 72 73 74 74 75 76 76 77 77 78 78 79 80 81 82 83 84 85

Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa

9.2 9.3 9.5 9.6 9.7 9.8 9.9 9.10 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 11.2 11.4 11.5 11.6

The Ideal Otto Cycle . . . . . . . . . . . . . . . . . . The Ideal Diesel Cycle . . . . . . . . . . . . . . . . . . The Simple Ideal Brayton Cycle . . . . . . . . . . . . An Actual Gas Turbine Cycle . . . . . . . . . . . . . . Actual Gas Turbine Cycle with Regeneration . . . . . A Gas Turbine with Reheating and Intercooling . . . . The Ideal Jet Propulsion Cycle . . . . . . . . . . . . . Second Law Analysis of an Otto Cycle . . . . . . . . . An Actual Steam Power Cycle . . . . . . . . . . . . . Effect of Boiler Pressure and Temperature on Efficiency The Ideal Reheat Rankine Cycle . . . . . . . . . . . . The Ideal Regenerative Rankine Cycle . . . . . . . . . The Ideal Reheat Regenerative Rankine Cycle . . . . . Second Law Analysis of an Ideal Rankine Cycle . . . . An Ideal Cogeneration Plant . . . . . . . . . . . . . . A Combined Gas Steam Power Cycle . . . . . . . . . . The Actual Vapor Compression Refrigeration Cycle . . A Two Stage Refrigeration Cycle with a Flash Chamber The Simple Ideal Gas Refrigeration Cycle . . . . . . . Cooling of a Canned Drink by a Thermoelectric Refrigerator . . . . . . . . . . . . . . . . . . . . . . . . . . . Exa 17.10 Estimation of the Mach Number from Mach Lines . . Exa 12.1 Approximating Differential Quantities by Differences . Exa 12.2 Total Differential versus Partial Differential . . . . . . Exa 12.5 Evaluating the hfg of a Substance from the PVT Data Exa 12.6 Extrapolating Tabular Data with the Clapeyron Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . Exa 12.11 dh and ds of oxygen at high pressure . . . . . . . . . . Exa 13.1 Mass and Mole Fractions of a Gas Mixture . . . . . . Exa 13.2 PVT Behavior of Nonideal Gas Mixtures . . . . . . . . Exa 13.3 Mixing Two Ideal Gases in a Tank . . . . . . . . . . . Exa 13.4 Exergy Destruction during Mixing of Ideal Gases . . . Exa 13.5 cooling of non ideal gas mixture . . . . . . . . . . . . Exa 13.6 obtaining fresh water from sea water . . . . . . . . . . Exa 14.1 The amonut of water vapour in room air . . . . . . . . Exa 14.2 Fogging of the windows in house . . . . . . . . . . . . Exa 14.3 The Specific and Relative Humidity of Air . . . . . . . Exa 14.4 The Use of the Psychrometric Chart . . . . . . . . . . 8

86 88 89 90 91 92 94 95 97 98 100 101 102 104 105 107 108 109 110 111 112 113 113 114 115 115 117 118 120 121 122 124 126 127 127 128

Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa Exa

14.5 14.6 14.8 14.9 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9 15.11 16.1 16.2 16.6 16.7 16.8 16.9 16.10 16.11 17.1 17.2 17.3 17.4 17.5 17.7 17.9 17.16

Heating and Humidification of Air . . . . . . . . . . Cooling and Dehumidification of Air . . . . . . . . . Mixing of Conditioned Air with Outdoor Air . . . . Cooling of a Power Plant by a Cooling Tower . . . . Balancing the Combustion Equation . . . . . . . . . Dew Point Temperature of Combustion Products . . Combustion of a Gaseous Fuel with Moist Air . . . . Reverse Combustion Analysis . . . . . . . . . . . . . Evaluation of the Enthalpy of Combustion . . . . . . First Law Analysis of Steady Flow Combustion . . . First law anlysis of combustion in bomb . . . . . . . Adiabatic Flame Temperature in Steady Combustion Reversible work associated with combustion process Second law analysis of isothermal combustion . . . . Equilibrium Constant of a Dissociation Process . . . Dissociation Temperature of Hydrogen . . . . . . . . Enthalpy of Reaction of a Combustion Process . . . Phase Equilibrium for a Saturated Mixture . . . . . Mole Fraction of Water Vapor Just over a Lake . . . The Amount of Dissolved Air in Water . . . . . . . . Diffusion of Hydrogen Gas into a Nickel Plate . . . . Composition of Different Phases of a Mixture . . . . Compression of High Speed Air in an Aircraft . . . . Mach Number of Air Entering a Diffuser . . . . . . . Gas Flow through a Converging Diverging Duct . . . Critical Temperature and Pressure in Gas Flow . . . Effect of Back Pressure on Mass Flow Rate . . . . . Airflow through a Converging Diverging Nozzle . . . Shock Wave in a Converging Diverging Nozzle . . . . Steam Flow through a Converging Diverging Nozzle

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

129 131 132 133 134 134 135 136 137 137 138 139 140 140 142 142 143 144 145 145 146 146 148 149 149 150 151 152 153 154

Chapter 1 Introduction and Basic Concept

Scilab code Exa 1.1 obtaining formulas for from unit considerations 1 2 3 4 5 6 7 8

// q u e s 1 // o b t a i n i n g f o r m u l a s f o r from u n i t c o n s i d e r a t i o n s clear clc d =850; // d e n s i t y mˆ3/ kg V =2; // volume mˆ3 m = d * V ; // mass Kg printf ( ” Mass o f t h e s a m p l e m =%. 0 f Kg” ,m ) ;

Scilab code Exa 1.5 Absolute Pressure of a Vacuum Chamber 1 // q u e s 5 2 // A b s o l u t e P r e s s u r e o f a Vacuum Chamber 3 clc 4 Patm =14.5; // A t m o s p h e r i c P r e s s u r e i n p s i 5 Pvac =5.8; // vaccum P r e s s u r e i n p s i 6 Pabs = Patm - Pvac ; // A b s o l u t e P r e s s u r e i n p s i 7 printf ( ” A b s o l u t e P r e s s u r e=A t m o s p h e r i c P r e s s u r e −

Vaccum P r e s s u r e=%0 . 1 f p s i ” , Pabs ) ; 10

Scilab code Exa 1.6 Measuring Pressure with nanometer 1 2 3 4 5 6 7 8 9

// q u e s 6 // M e a s u r i n g P r e s s u r e w i t h n a n o m e t e r clc Patm =96; // A t m o s p h e r i c P r e s s u r e i n kPa d =850; // d e n s i t y i n Kg/mˆ3 g =9.81; // g r a v i t a t i o n a l a c c e l a r a t i o n h =0.55; // h i e g h t i n m e t r e P = Patm + d * g * h /1000; // P r e s s u r e i n kPa printf ( ” P r e s u r e=Patm+ d∗ g ∗h=%. 1 f kPa ” ,P ) ;

Scilab code Exa 1.7 Measuring pressure with multifluid manomete 1 2 3 4 5 6 7 8 9 10 11 12 13 14

// q u e s 7 // M e a s u r i n g p r e s s u r e w i t h m u l t i f l u i d manometer clear clc Patm =85.6; // i n kPa dwater =1000; // d e n s i t y o f w a t e r i n Kg/mˆ3 dmercury =13600; // d e n s i t y o f m e r c u r y i n Kg/mˆ3 doil =850; // d e n s i t y o f o i l i n Kg/mˆ3 g =9.81; // a c c due t o g r a v i t y i n m/ s ˆ2 h1 =0.1; // h e i g h t o f w a t e r i n m e t r e h2 =0.2; // h e i g h t o f o i l i n m e t r e h3 =0.35; // h i e g h t o f m e r c u r y i n m e t r e P1 = Patm + g *( dmercury * h3 - dwater * h1 - doil * h2 ) /1000; printf ( ” P r e s s u r e P1 = %. 0 f kPa ” , P1 ) ;

11

Scilab code Exa 1.8 Measuring Atmospheric Pressure with barometer 1 2 3 4 5 6 7 8 9

// q u e s 8 // M e a s u r i n g A t m o s p h e r i c P r e s s u r e w i t h b a r o m e t e r clear clc g =9.81; // a c c due t o g r a v i t y i n m/ s ˆ2 h =0.74; // h e i g h t i n m e t r e d =13570; // d e n s i t y i n Kg/mˆ3 Patm = d * g * h /1000; // A t m o s p h e r i c p r e s s u r e i n kPa printf ( ” A t m o s p h e r i c p r e s s u r e from b a r o m e t e r i s = %. 1 f kPa ” , Patm ) ;

Scilab code Exa 1.9 Effect of piston weight on Pressure of Cylinder // q u e s 9 // E f f e c t o f p i s t o n w e i g h t on P r e s s u r e o f C y l i n d e r clear clc Patm =0.97; // A t m o s p h e r i c p r e s s u r e i n b a r m =60; // mass i n kg g =9.81; // a c c due t o g r a v i t y i n m/ s ˆ2 A =0.04; // a r e a i n mˆ2 P = Patm + m * g / A /10^5; // n e t p r e s s u r e a f t e r c o n s i d e r i n g t h e e f f e c t i n Bar 10 // d i v i d e d by 1 0 ˆ 5 t o c o n v e r t i t i n t o b a r s 11 printf ( ” P r e s s u r e = %. 2 f Bar ” ,P ) ; 1 2 3 4 5 6 7 8 9

Scilab code Exa 1.10 Hydrostatic Pressure in a Solar Pond with Variable Density 1

// q u e s 1 0 12

2 3 4 5 6 7 8 9 10 11

// H y d r o s t a t i c P r e s s u r e i n a S o l a r Pond w i t h V a r i a b l e Density clear clc d =1040; // d e n s i t y o f pond i n Kg/mˆ3 g =9.81; // a c c due t o g r a v i t y i n m/ s ˆ2 h1 =0.8; // h e i g h t o f l i q u i d i n m e t r e H =4; // h e i g h t o f l i q u i d o f v a r i a b l e d e n s i t y P1 = d * g * h1 /1000; // d i v i d e d by 1 0 0 0 t o c o n v e r t i t i n t o kPa P = P1 + integrate ( ’ d∗ g ∗ s q r t (1+ t a n ( %pi /4∗ z /H) ˆ 2 ) ’ , ’ z ’ ,0 ,4) /1000; printf ( ’ P r e s s u r e a t t h e bottom o f t h e g r a d i e n t z o n e = %. 1 f kPa ’ ,P ) ;

Scilab code Exa 1.12 Analyzing a Multifluid Manometer with EES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

// q u e s 1 2 // A n a l y z i n g a M u l t i f l u i d Manometer w i t h EES clc g =9.81; // a c c due t o g r a v i t y i n m/ s ˆ2 Patm =85600; // A t m o s p h e r i c p r e s s u r e i n Pa h1 =0.1; // h e i g h t o f w a t e r i n m e t r e h2 =0.2; // h e i g h t o f o i l i n m e t r e h3 =0.35; // h e i g h t o f m e r c u r y i n m e t r e dwater =1000; // d e n s i t y o f w a t e r i n Kg/mˆ3 doil =850; // d e n s i t y o f o i l i n Kg/mˆ3 dmercury =13600; // d e n s i t y o f m e r c u r y i n Kg/mˆ3 P1 = Patm -( dwater * g * h1 + doil * g * h2 - dmercury * g * h3 ) ; // i n Pa printf ( ’ P r e s s u r e a t p o i n t 1 = %. 0 f Pa ’ , P1 ) ; //Now t o f i n d h3 i f m e r c u r y i s r e p l a c e d by a n o t h e r oil dmercury =1030; // D e n s i t y o f new m e r c u r y i n Kg/mˆ3 h3 =( P1 - Patm + dwater * g * h1 + doil * g * h2 ) /( g * dmercury ) ; // i n 13

metre 17 printf ( ” \n New h e i g h t h3 = %. 2 f m e t r e s ” , h3 ) ;

14

Chapter 2 Energy Transfer and General Energy Analysis

Scilab code Exa 2.1 General energy analysis 1 // e x a m p l e 1 2 // g e n e r a l e n e r g y a n a l y s i s 3 clear 4 clc 5 d =0.75 // d e n s i t y o f g a s o l i n e i n kg / l 6 v =5 // a v e r a g e c o n s u m p t i o n o f g a s o l i n e by t h e c a r i n 7 8 9 10 11 12 13

l i t r e s / day h =44000 // h e a t i n g v a l u e o f g a s o l i n e i n kJ / kg disp ( ’ d a i l y c o n s u m p t i o n o f f u e l = c = d∗ v ’ ) c = d * v // a v e r a g e c o n s u m p t i o n o f g a s o l i n e i n kg / day e = c * h // d a i l y e n e r g y r e q u i r e m e n t o f c a r i n kJ / day E =0.1*6.73*10^10 // e n e r g y r e l e a s e d by c o m p l e t e f u s s i o n o f 0 . 1 kg o f uranium i n kJ x = E / e // no . o f d a y s f o r which E amount o f e n e r g y can meet t h e e n e r g y r e q u i r e m e n t s o f c a r printf ( ” \n Hence , t h e c a r w i l l r e q u i r e r e f i l l i n g a f t e r = %. 0 f y e a r s . \n ” ,x /365) ;

15

Scilab code Exa 2.2 Analysis of wind energy // e x a m p l e 2 // a n a l y s i s o f wind e n e r g y clear clc v =8.5 // v e l o c i t y o f wind i n m/ s e = v ^2/2 // wind e n e r g y p e r u n i t mass o f a i r i n j / kg m =10 // mass o f wind t o be c o n s i d e r e d i n kg E = m * e // e n e r g y i n j o u l e s o f wind o f mass m mf =1154 // mass f l o w r a t e i n kg / s Ef = mf * e // wind e n e r g y i n W f o r a mass f l o w r a t e o f mf 11 printf ( ” \n Hence , wind e n e r g y p e r u n i t mass i s = %. 1 f J / kg . \n ” ,e ) ; 12 printf ( ” \n The wind e n e r g y f o r a mass o f 10 kg i s = %. 0 f J . \n ” ,E ) ; 13 printf ( ” \n The wind e n e r g y f o r f l o w r a t e o f 1 1 5 4 kg / s i s = %. 1 f kW. \n ” , Ef /1000) ; 1 2 3 4 5 6 7 8 9 10

Scilab code Exa 2.7 Power Transmission by the Shaft of a Car 1 2 3 4 5 6 7 8 9

// e x a m p l e 7 // Power T r a n s m i s s i o n by t h e S h a f t o f a Car clear clc t =200 // t o r q u e a p p l i e d i n N .m rpm =4000 // r e v o l u t i o n s p e r m i n u t e o f s h a f t n = rpm /60 // r e v o l u t i o n s p e r s e c o n d o f s h a f t w =2* %pi * n * t // s h a f t power i n w a t t s printf ( ” \n Hence , power t r a n s m i t t e d by t h e s h a f t o f c a r i s = %. 1 f kW. \n ” ,w /1000) ; 16

Scilab code Exa 2.8 Power Needs of a Car to Climb a Hill // e x a m p l e 8 // Power Needs o f a Car t o Climb a H i l l clear clc m =1200 // mass o f c a r i n kg v1 =90 // v e l o c i t y o f c a r i n km/ h v2 =90*5/18 // v e l o c i t y o f c a r i n m/ s x =30 // s l o p e o f h i l l i n d e g r e e s g =9.8 // a c c . due t o g r a v i t y i n m/ s ˆ2 w = m * g * v2 * sin ( %pi *30/180) // a d d i t i o n a l power t o be d e l i v e r e d by e n g i n e i n w a t t s 11 printf ( ” \n Hence , a d d i t i o n a l power t o be d e l i v e r e d by e n g i n e i s = %. 0 f kW. \n ” ,w /1000) ;

1 2 3 4 5 6 7 8 9 10

Scilab code Exa 2.9 Power needs of a car to accelerate // e x a m p l e 9 // power n e e d s o f a c a r t o a c c e l e r a t e clear clc m =900 // mass o f c a r i n kg v1 =0 // i n i t i a l v e l o c i t y o f c a r v2 =80*5/18 // f i n a l v e l o c i t y o f c a r i n m/ s t =20 // t i m e i n which t h e c a r h a s t o r e a c h i t s d e s i r e d speed in seconds 9 w = m *( v2 ^2 - v1 ^2) /2 // work r e q u i r e d t o a c c o m p l i s h t h i s task in j o u l e s 10 p = w / t // power r e q u i r e d i n w a t t s 11 printf ( ” \n Hence , power r e q u i r e d t o a c c e l e r a t e i s = % . 1 f kW. \n ” ,p /1000) ; 1 2 3 4 5 6 7 8

17

Scilab code Exa 2.10 Cooling of hot fluid in tank 1 // e x a m p l e 10 2 // c o o l i n g o f h o t f l u i d i n t a n k 3 clear 4 clc 5 disp ( ’ s u p p o s e t h a t t h e r e i s no c h a n g e i n 6 7 8 9 10 11

k i n e t i c and p o t e n t i a l energy ’) u1 =800 // i n i t i a l i n t e r n a l e n e r g y i n 800 kJ win =100 // work done by p a d d l e on s y s t e m i n kJ qout =500 // l o s s o f e n e r g y from f l u i d disp ( ’ a p p l y i n g f i r s t law o f t h e r m o d y n a m i c s ’ ) u2 = u1 - qout + win // f i n a l i n t e r n a l e n e r g y i n kJ printf ( ” \n Hence , f i n a l i n t e r n a l e n e r g y o f t h e f l u i d i s = %. 1 f kJ . \n ” , u2 ) ;

Scilab code Exa 2.11 Acceleration of air by fan 1 2 3 4 5 6 7 8 9

// e x a m p l e 11 // a c c e l e r a t i o n o f a i r by f a n clear clc v =8 // d i s c h a r g e r a t e o f a i r i n m/ s m =0.25 // mass f l o w r a t e i n kg / s p = m * v ^2/2 // a c t u a l power consumed i n W P =20 // c l a i m e d power i n W disp ( ’ s i n c e , two p o w e r s a r e n o t e q u a l , t h i s c l a i m i s not r e a s o n a b l e ’ )

18

Scilab code Exa 2.12 Heating effect of a fan 1 2 3 4 5 6 7 8 9 10

// e x a m p l e 12 // h e a t i n g e f f e c t o f a f a n clear clc t1 =25 // i n i t i a l t e m p e r a t u r e o f room i n C p =200 // power c o n s u m p t i o n o f f a n i n w a t t s a =30 // e x p o s e d s u r f a c e a r e a i n mˆ2 u =6 // i n w/mˆ2 t2 = p /( u * a ) + t1 // f i n a l temp . o f room i n C printf ( ” \n Hence , t h e i n d o o r a i r t e m p e r a t u r e when steady operating conditions are established i s = %. 1 f C . \n ” , t2 ) ;

Scilab code Exa 2.13 Annual lighting cost of a classroom // e x a m p l e 13 // a n n u a l l i g h t i n g c o s t o f a c l a s s r o o m clear clc p =80 // power consumed by f l u o r o s c e n t lamp i n w a t t n =30 // no . o f lamps u s e d P = p * n /1000 // l i g h t i n g power i n kW t =250*12 // o p e r a t i n g h o u r s i n a y e a r E = P * t // l i g h t i n g e n e r g y / y e a r c = E *0.07 // c o s t o f l i g h t i n g a c l a s s r o o m f o r a y e a r in d o l l a r s 11 printf ( ” \n Hence , a n n u a l e n e r g y c o s t o f l i g h t i n g f o r t h e c l a s s r o o m i s = %. 0 f $ / y e a r . \n ” ,c ) ; 1 2 3 4 5 6 7 8 9 10

Scilab code Exa 2.15 Cost of cooking with electric and gas charges 19

1 2 3 4 5 6 7 8 9 10 11 12 13

// e x a m p l e 15 // c o s t o f c o o k i n g w i t h e l e c t r i c and g a s c h a r g e s clear clc e1 =73 // e f f i c i e n c y o f open b u r n e r f o r e l e c t r i c u n i t s e2 =38 // e f f i c i e n c y o f open b u r n e r f o r g a s u n i t s E1 =2 // E l e c t r i c a l e n e r g y i n p u t i n 2kW q1 = E1 * e1 /100 // a c t u a l l y u t i l i s e d e l e c t r i c a l e n e r g y i n kWh c =0.09/0.73 // c o s t o f u t i l i s e d e n e r g y p e r kWh q2 = q1 /( e2 /100) // e n e r g y i n p u t t o a g a s b u r n e r i n kW c =(0.55/29.3) /( e2 /100) // c o s t o f u t i l i s e d e n e r g y o f gas burner printf ( ” \n Hence , r a t e o f e n e r g y c o n s u m p t i o n by t h e b u r n e r i s = %. 2 f kW. \n ” , q2 ) ; printf ( ” \n The c o s t o f u t i l i s e d e n e r g y i s = $ %. 3 f / kWh . \n ” ,c ) ;

Scilab code Exa 2.16 Performance of hydraulic turbine generator 1 2 3 4 5 6 7 8 9 10 11 12 13 14

// e x a m p l e 16 // p e r f o r m a n c e o f h y d r a u l i c t u r b i n e g e n e r a t o r clear clc h =50 // d e p t h o f l a k e i n m e t r e s m =5000 // mass f l o w r a t e o f w a t e r i n kg / s g =9.81 // a c c . due t o g r a v i t y i n m/ s ˆ2 disp ( ’ c h a n g e i n m e c h a n i c a l e n e r g y= ’ ) e = g * h /1000 // c h a n g e i n mech . e n e r g y i n kJ / kg E1 = e * m // Rate a t which m e c h a n i c a l e n e r g y i s s u p p l i e d t o t h e t u r b i n e i n kW E2 =1862 // e l e c t r i c power g e n e r a t e d i n kW n1 = E2 / E1 // o v e r a l l e f f i c i e n c y n2 =0.95 // e f f i c i e n c y o f g e n e r a t o r n3 = n1 / n2 // e f f i c i e n c y o f t u r b i n e 20

15 W = n3 * E1 // s h a f t power o u t p u t i n kW 16 printf ( ” \n Hence , o v e r a l l e f f i c i e n c y

of turbine g e n e r a t o r i s = %. 2 f . \n ” , n1 ) ; 17 printf ( ” \n The m e c h a n i c a l e f f i c i e n c y o f t h e t u r b i n e i s = %. 2 f . \n ” , n3 ) ; 18 printf ( ” \n The s h a f t power s u p p l i e d by t h e t u r b i n e t o t h e g e n e r a t o r i s =%. 0 f kW. \ n ” ,W )

Scilab code Exa 2.17 Cost Savings Associated with High Efficiency motors 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

// e x a m p l e 17 // C o s t S a v i n g s A s s o c i a t e d w i t h High− E f f i c i e n c y motors clear clc n1 =89 // e f f i c i e n c y o f f i r s t motor n2 =93.2 // e f f i c i e n c y o f s e c o n d motor c =0.08 // c o s t o f e l e c t r i c i t y i n $ /kWh p =60*0.7457 // r a t e d power i n kW h =3500 // o p e r a t i n g h o u r s p e r y e a r e = p * h *(1/( n1 /100) -1/( n2 /100) ) // e n e r g y s a v i n g s s = e * c // c o s t s a v i n g s t =640/ s // s i m p l e payback p e r i o d i n y e a r printf ( ” \n Hence , t h e amount o f e n e r g y s a v e d i s = %. 0 f kWh/ y e a r . \n ” ,e ) ; printf ( ” \n The money s a v e d i s =%. 0 f $ / y e a r . \n ” ,s ) ; printf ( ” \n The payback p e r i o d i s =%. 2 f y e a r s . \ n ” ,t ) ;

Scilab code Exa 2.18 Reducing air pollution by geothermal heating 1 2

// e x a m p l e 18 // r e d u c i n g a i r p o l l u t i o n by g e o t h e r m a l h e a t i n g 21

3 clear 4 clc 5 s =18*10^6 // q u a n t i t y o f 6 7 8 9 10 11

n a t u r a l g a s t h a t w i l l be saved per year in therms nn =0.0047 // q u a n t i t y o f NOx i n kg / therm nc =6.4 // q u a n t i t y o f CO2 i n kg / therm sn = nn * s //NOx s a v i n g s p e r y e a r i n kg / y e a r sc = nc * s //CO2 s a v i n g s p e r y e a r i n kg / y e a r printf ( ” \n Hence , g e o t h e r m a l s y s t e m w i l l s a v e %. 1 f ∗ 1 0 ˆ 4 kg NOx/ y e a r . \n ” , sn /10^4) ; printf ( ” \n and = %. 1 f ∗ 1 0 ˆ 8 kg CO2/ y e a r . \n ” , sc /10^8) ;

Scilab code Exa 2.19 Heat transfer from a person 1 2 3 4 5 6 7 8 9 10 11 12

// e x a m p l e 19 // h e a t t r a n s f e r from a p e r s o n clear clc T1 =20 // room t e m p e r a t u r e i n c e l s i u s T2 =29 // body t e m p e r a t u r e o f p e r s o n i n c e l s i u s a =1.6 // e x p o s e d s u r f a c e a r e a i n mˆ2 h =6 // c o n v e c t i o n h e a t t r a n s f e r c o e f f i c i e n t i n W/mˆ2∗ C Qc = h * a *( T2 - T1 ) // h e a t l o s s due c o n v e c t i o n i n W Qr =0.95*5.67*10^ -8* a *(( T2 +273) ^4 -( T1 +273) ^4) // h e a t l o s s due t o r a d i a t i o n i n W Q = Qc + Qr // n e t h e a t l o s s from t h e p e r s o n i n W printf ( ” \n Hence , t h e t o t a l r a t e o f h e a t t r a n s f e r i s =%. 1 f W. \n ” ,Q )

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Chapter 3 Properties of Pure Substances

Scilab code Exa 3.1 Pressure of Saturated Liquid in a Tank 1 // e x 1 2 // P r e s s u r e o f S a t u r a t e d L i q u i d i n a Tank 3 clc 4 Psat =70.183; // s a t u r a t e d p r e s s u r e @90C u s i n g steam 5 6 7 8 9

t a b l e A−4 i n kPa printf ( ’ From steam t a b l e P s a t @ 90 C = %. 3 f kPa ’ , Psat ) ; vsat =0.001036; // s a t u r a t e d s p e c i f i c volume @90C i n m ˆ3/Kg m =50; // mass i n kg V = m * vsat ; // Volume o f t a n k i n mˆ3 printf ( ’ \n T o t a l Volume o f Tank = %. 4 f mˆ3 ’ ,V ) ;

Scilab code Exa 3.2 Temperature of Saturated Vapor in a Cylinder 1 // q u e s 2 2 // T e m p e r a t u r e o f S a t u r a t e d Vapor i n a C y l i n d e r 3 clc

23

4 5 6 7 8 9

Tsat =280.99; // S a t u r a t e d t e m p e r a t u r e i n F @ 50 p s i a from t a b l e A−5E printf ( ” S a t u r a t e d T e m p e r a t u r e = %. 2 f F \n ” , Tsat ) ; v =8.5175; // vg s a t u r a t e d volume o f v a p o r i n f t ˆ3/ lbm t a b l e A−5E V =2; // T o t a l Volume i n f t ˆ3 m = V / v ; // mass i n lbm printf ( ’ Mass o f t h e s a m p l e i s = %. 3 f lbm ’ ,m ) ;

Scilab code Exa 3.3 Volume and Energy Change during Evaporation 1 // q u e s 3 2 // Volume and Energy Change d u r i n g E v a p o r a t i o n 3 clc 4 vg =1.6941; // s a t u r a t e d v a p o r s p e c i f i c volume from 5 6 7 8 9 10 11 12 13 14

t a b l e A−5 @ 100 kPa i n mˆ3/Kg vf =0.001043; // s a t u r a t e d l i q u i d s p e c i f i c volume from t a b l e A−5 @ 100 kPa i n mˆ3/Kg vfg = vg - vf ; // i n mˆ3/Kg m =0.2; // i n kg // ( a ) Volume c h a n g e dV = m * vfg ; // Volume i n mˆ3 printf ( ’ ( a ) Volume c h a n g e = %. 4 f mˆ3 \n ’ , dV ) ; // ( b ) Amount o f e n e r g y T r a n s f e r t o w a t e r hfg =2257.5; // c h a n g e i n e n t h a l p y from t a b l e A−5 @ 100 kPa i n kJ /Kg E = m * hfg ; // I n kJ printf ( ’ ( b ) Energy T r a n s f e r r e d = %. 1 f kJ ’ ,E ) ;

Scilab code Exa 3.4 Pressure and Volume of a Saturated Mixture 1 2

// q u e s 4 // P r e s s u r e and Volume o f a S a t u r a t e d M i x t u r e 24

3 4 5 6 7 8 9 10 11

clc // ( a ) P r e s s u r e i n t h e t a n k P =70.183; // P s a t @ 90 C t a b l e A−4 i n kPa printf ( ” ( a ) P r e s s u r e i n t h e t a n k = %. 3 f kPa ” ,P ) ; // ( b ) volume o f t a n k disp ( ’ ( b )V = Vf+Vg = mf∗ v f+mg∗ vg ’ ) ; mf =8; // mass o f l i q u i d w a t e r i n kg mg =2 // mass o f v a p o r w a t e r i n kg vf =0.001036; // s a t u r a t e d s p e c i f i c volume o f l i q u i d w a t e r from t a b l e A−4 i n mˆ3/Kg 12 vg =2.3593; // s a t u r a t e d s p e c i f i c volume o f v a p o r w a t e r from T a b l e A−5 i n mˆ3/Kg 13 V = mf * vf + mg * vg ; // T o t a l Volume i n mˆ3 14 printf ( ’ Volume o f t a n k = %. 2 f mˆ3 ’ ,V ) ;

Scilab code Exa 3.5 Properties of Saturated Liquid Vapour Mixture 1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16

// q u e s 5 // P r o p e r t i e s o f S a t u r a t e d L i q u i d Vapour M i x t u r e clc V =0.080; // volume i n mˆ3 g i v e n m =4; // i n kg g i v e n v = V / m ; // i n mˆ3/ kg vf =0.0007437; // @160kPa from t a b l e A−4 i n mˆ3/ kg vg =0.12348; // @160kPa from t a b l e A−4 i n mˆ3/ kg // ( a ) T e m p e r a t u r e Tsat = -15.60; // i n C from t a b l e A−4 printf ( ’ \n ( a ) S i n c e v f