Psych Process

This Psychrometric Processes Program follows equations provided in the 2005 ASHRAE Handbook of Fundamentals, Chapter 6. The program can replace the Psychrometric chart and users are encouraged to compare values. It permits the quick calculation of basic HVAC air mixing, cooling, heating and heat recovery processes. Thanks are extended to Dr. Jim Richardson (CE Department @ UA) and Barbara McCrary of Johnson Spellman Associates in Atlanta for assistance in learning the use of Visual Basic macros in Excel that permit the calculation of psychrometric values using functions.

The Psychrometric Chart 90 .0 2 8

100 88 11 14.69 29.91

°F °F ft. psia in Hg

Tdb2 Twb2

.0 2 4

45 80

.0 2 0

40

75

35

HRatio1 RelHum1 SpHt1 Enal1 SpVol1 DewPt1 lbpCuFt

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F 3 #VALUE! lbw/ft

HRatio2 RelHum2 SpHt2 Enal2 SpVol2 DewPt2 lbpCuFt

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F 3 #VALUE! lbw/ft

Note 2: If Macro security level is set at high, this program will result in errors in the cells [NAME?]. To reset the security level, 1. Close the PsychProcess program. 2. Click on "Tools" on the main tool bar, select "Macro", select "Security. 3. Reset security level to Medium (recommended) or Low 4. Exit Excel 5. Re-Open Excel 6. Run program

.0 1 6

70

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

30

65

25 20 15

.0 1 2

60

50

.0 0 8

40 .0 0 4

32

40

50

60

70 80 90 D R Y BU LB T E M P ER AT U R E (F )

100

110

120

H U M I D I T Y R A T I O (L b v / L b a )

Tdb1 Twb1 Elevation AtmPress APinHg

50

Note 1: In these programs, 72 °F required input values are in 65 °F yellow cells. Output values are in blue or green.

Mixing - This Worksheet computes the resulting properties of air (stream 3) when streams 1 and 2 are mixed. Flow rates are entered below but properties for streams 1 and 2 are entered on the "Properties" Worksheet. Qair1 QSair1

5000 cfm #VALUE! scfm

Qair2 QSair2

1000 cfm #VALUE! scfm

mflow1

Stream 1 #VALUE! lb/hr

mflow2

Stream 2 #VALUE! lb/hr

Stream 3 mflow3 #VALUE! Qair3 #VALUE! Tdb3 #VALUE! HRatio3 #VALUE! #VALUE! Twb3 #VALUE! RelHum3 #VALUE! SpHt3 #VALUE! Enal3 #VALUE! SpVol3 #VALUE! DewPt3 #VALUE!

(mixed) lb/hr cfm °F lbw/lba Grains °F % Btu/lb-°F Btu/lb cu.ft./lb °F

Note: Input values (Qair1 and Qair2) are in cubic feet per minute. For additional information purposes, these values are corrected to air at standard conditions of ρ=0.075 lb/cu.ft. (QSair1 and QSair2).

Stream 1 @ Qair1(cfm), Tdb1(°F), & Twb1(°F)

Stream 3 @ Qair3(cfm), Tdb3(°F), & Twb3(°F)

Stream 2 @ Qair2(cfm), Tdb2(°F), & Twb2(°F) 2 1

3

This Worksheet computes the properties of air leaving Heat Recovery Units (HRU) used to adsorb or remove heat (and in so moisture) from room air that is being exhausted. The heat and moisture are transfered to or from the fresh outdoor air make-u capacity of the HRU is also computed. The effects of the HRU supply fan heat are considered. HRU Effectiveness 75 % 72 % Outdoor QairOut 2000 cfm QSairOut #VALUE! scfm mflowOut #VALUE! lb/hr SupFankW 1.86 kW ExFankW 1.47 kW Exhaust (not req'd) QairEx 2000 cfm QSairEx #VALUE! scfm Room Air HRatioRm #VALUE! lbw/lba #VALUE! Grains RelHumRm #VALUE! % SpHtRm #VALUE! Btu/lb-°F EnalRm #VALUE! Btu/lb SpVolRm #VALUE! cu.ft./lb DewPtRm #VALUE! °F

Room Air TdbRm TwbRm Outdoor Air TdbOut TwbOut Elev.

SenEff LatEff

Capacities #VALUE! #VALUE! #VALUE! Outdoor Air HRatioOut #VALUE! #VALUE! RelHumOut #VALUE! SpHtOut #VALUE! EnalOut #VALUE! SpVolOut #VALUE! DewPtOut #VALUE! qTotalHru qSenHru SHRHru

75 63 °F °F 92 74.4 °F 591 ft. HRU Outlet MBtu/h MBtu/h

TdbHru TwbHru

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

HRatioHru

Exhaust Air

HRU Outdoor Air

Temps. #VALUE! °F #VALUE! °F

HRU Outlet #VALUE! #VALUE! RelHumHru #VALUE! SpHtHru #VALUE! EnalHru #VALUE! SpVolHru #VALUE! DewPtHru #VALUE!

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

or remove heat (and in some units e fresh outdoor air make-up air. The

Room Air

HRU HRU Outlet Air to room or HVAC Unit OALoads #VALUE! MBtu/h #VALUE! MBtu/h

t(o) t(r)

DWinter

DD

t(hru)

Summer

Inlet Conditions QairHin qFurn QSairHin mflowHin TdbHin TwbHin ElevH APpsia APHg

HRatioHin RelHumHin SpHtHin EnalHin SpVolHin DewPtHin

2000 75 #VALUE! #VALUE! 68 56 0 14.70 29.92

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

Outlet Conditions Without Humidification cfm MBtu/h scfm lb/hr °F °F ft. psia in Hg

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

TdbHout TwbHout

#VALUE! °F #VALUE! °F

HRatioHout

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

RelHumHout SpHtHout EnalHout SpVolHout DewPtHout

t(in)

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

t(out)

Outlet Conditions With Humidification* TdbOutAir 20 °F TwbOutAir 15 °F OAVentInfil 20 % of supply HRatioOA #VALUE! lbw/lba #VALUE! Grains *Assumption: RelHumOA #VALUE! % SpHtOA #VALUE! Btu/lb-°F Sufficient moisture is added in the form of EnalOA #VALUE! Btu/lb water or saturated steam SpVolOA #VALUE! cu.ft./lb to replace the moisture DewPtOA #VALUE! °F lost via the exhaust air, which is replace with dryer outdoor air. FluidType Sat Steam FluidTemp 212 °F EnalFluid 1150 Btu/lb mfluid #VALUE! lb/hr qHumid #VALUE! MBtu/h TdbHumOut #VALUE! °F qNet #VALUE! MBtu/h t(out) Water

t(in)

Steam

Inlet Air Conditions QairIn 4000 cfm TC 120 MBtu/h SC 100 MBtu/h QSairIn #VALUE! scfm SHR 0.83 TdbIn 75 °F TwbIn 63 °F ElevIn 0 ft. AtmPressI 14.70 psia APinHgIn 29.92 in Hg

HRatioIn RelHumIn SpHtIn EnalIn SpVolIn DewPtIn

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

Fan Heat Neglected

mflowIn QairOut QSairOut

#VALUE! lb/hr #VALUE! cfm #VALUE! scfm

Fan Heat TotalPress FanEff MotorEff BHP qFan qTotNet qSenNet SHRNet

TdbOut TwbOut

#VALUE! °F #VALUE! °F

TdbNet TwbNet

HRatioOut

#VALUE! #VALUE! RelHumOut #VALUE! SpHtOut #VALUE! EnalOut #VALUE! SpVolOut #VALUE! DewPtOut #VALUE!

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

HRatioNet

Included 2 65 82 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

#VALUE! #VALUE! RelHumNet #VALUE! SpHtNet #VALUE! EnalNet #VALUE! SpVolNet #VALUE! DewPtNet #VALUE!

In. of Water % % hp In

MBtu/h MBtu/h Out °F °F lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

Fan Heat Neglected

Net Fan Heat Included

By-Pass (BP) Factor Method QairRet 4000 cfm Tadp 47 °F BPFactor 0.1 QSairRet #VALUE! scfm TdbRet TwbRet Elev AtmPress APinHg

79.8 67.1 0 14.70 29.91

HRatioRet

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

RelHumRet SpHtRet EnalRet SpVolRet DewPtRet

°F °F ft. psia in Hg

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

mflowRet QairSup QAairSup

#VALUE! lb/hr #VALUE! cfm #VALUE! scfm

TdbSup TwbSup HRatioadp

50.3 °F #VALUE! °F #VALUE! lbw/lba

qTotal qSensible SHRcoil

#VALUE! MBtu/h #VALUE! MBtu/h #VALUE!

HRatioSup

#VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

RelHumSup SpHtSup EnalSup SpVolSup DewPtSup

lbw/lba Grains % Btu/lb-°F Btu/lb cu.ft./lb °F

BPFactor = 1-(TdbRet-TdbSup)/(TdbRet-Tadp) T(adp) Q(airSup)

Q(airRet)

T(dbSup) T(wbSup)

T(dbRet) T(wbRet)

t(ret) t(adp)

t(sup)