CF{APTER 8. APPLIED PSYCHROMETRICS
1-149
ABBREVIATIONS
adp
SYMBOLS
apparatu.sdewpoint
BF
(tsF)(OALH)
(BF) (oAsH)
(BF) (OATH)
Btu/hr
bypassfactor
bypassedoutdoor air
. bypassedourdoor air
bypassedoutdoor air
'tsritiih
thermal units
clm6o
clm6o
cfntoo
cfmro
cfm"o
latent heat
sensibleheat
total heat
per hour
cfm
cubic feet per minute
db
dp
div-bulb
dewpoint
ERLH
ERSH
ERTH
ESHF
effective room latent heat
effective room sensibleheat
efiective room total heat
effective sensibleheat factor
F
fp*
Fahrenheit degrees
feet per minute
gPm
gr/lb
GSHF
GTH
GTHS
g a l l o n sp e r m i n u t e
grains per pound
grand sensibleheat factor
grand total heat
grand total heat supplement
OALH
OASH
OATH
outdoor air latent heat
outdoor air sensiblehear
outdoor air total heat
rh
RLH
RLHS
RSH
RSHF
RSHS
RTH
r-elativehumidity
room Iatent heat
room lateirt heat supplement
room sensibleheat
room sensitrleheat lactor
room sensibleheat supplement
room total heat
SatEfi
SHF
saturation efficiencyof sprays
sensibleheat factor
TLH
TSH
total latent heat
total sensibleheat
wb
wet-bulb
h
hoap
h",
h",,
h,o
h*
hou
h,,,,
L"o
L
toap
tedh
t
"ru
t erob
ttat
Llw
@
Atu condiliotiesr
Goal,a,.y
ttub
tin
too
t,,,
t"o
W
W*b
Woo
W""
Wto
w*
Woo
wr;*
W"o
bypassedair quantity around appararus
dehumidified air quantity
outdoor air quantity
return air ouantity
sirpply air quantity
specificenthalpy
apparatus dewpoint enlhalpy
effective surface temperature enthalpy
entering air enthalpy
leaving air enthalpy
rnixtrrreof outdoor and return air
enthalpy
outdoor air enthalpy
t'oom air enthalpy
s u p p l ya i r e n t h a l p y
temperature
apparatusdewpoint temPeratu re
cn tering dry-bu lb temperature
effectivesurface temperature
entering water temperature
entering wet-bulb.temperature
leaving dry-bulb remperarure
leaving water temperature
leaving wet-bulb temperature
mixture of outdoor and return air
dry-bulb temperature
outdoor air dry.trulb temperature
room dry-bulb temperature
supply air dry-bulb temperarure
moisture content or specifichumidity
apparatus dewpoint moisture content
entering air moisture content
effectivesurface temperature moisture
content
leaving air moisture content
mixture of outdoor and return air
moisture content
outdoor air moisture content
room moisture content
supply air moisture content
PART I.:.LOA,D
PSYCHROMETRIC
FORMULAS
(Outdoorond ReturnAir)
A. AIRM|XINGEQUAflONS
te m
-
(tf*o"X
to) + (cfrnrnX t*)
clm""
(itt,*x
h^ _
hou)+ (cfmnax h,;)
cfm""
(4
(2)
W*)
v v_n Gf*o,X.
= f f i Woo)
, ( 3* (cfm.,ox
)
rrt
RTH
OASH
OAI,H
OATH
(t0)
(ll)
=4;45f x cJm,6X(h--h,,o)
=RSH+RI-H
(12)
(l3)
= 1.08 x cftnoa(tqa- t*),
= .68 X cfmoo(Woo- Wr*)
- 4.45 x cfmoo(hoo- h,^)
(14)
(15)
RSH + RLH
ERSFI]
E.RSH+ ERLH
TSI-I
GSHF =
F :
TSH + TLH
,TSif,,,a
GTH ;
: : ::r::,
D. BYPASS
FACTOR
EQUATIONS r: '
gp =
tno- toap
teau -
taitp
t"uo-'
; 0 - BF) =
teao -
sp= !flw-;,(l-BF),n'
Wro-
-
Wo6p
haitp
; (l - BF)'=
Wr*
h
h"a
.(ro)
(17)
(BF)(oATH) = (BF)(oAsH) + (Br) (OALH)
(18)
ERSH = 1.08x cfm6o[x(t,*: t"il(l - Bf)
OATH
RSH
ESI{F =
ERSH = RSH + (BF) (oAsI{) + RSHS* (4}
ERLrr - RLH + (BF) (OALrr) + RLHS* (5)
E.RTH _ERL.H+ERSH
(6)
-RSH+OASH+RSHS*
TSH
(7)
= RLH + OALH +'RLHS*
TLH
(8)
GTH -TSH+TLH+GTHS*
(e)
RTH
SENSIBLE
HEATFACTOR
RSHF =
B. COOTINGTOADEQUATTONS
-: 1.08tx 4m*x (t*- tse)
RSH
RLH .- .68tx,gfm,nx(W*-W,o)
= 1.08X cfrnuolX(t"uu: .68x cfmu,! x (Weo- Wl
= 4.45x cfm*lX,(huo-
TSH
TLH
GTH
=OASH+OALH
ERLH = .68xc rndalx(W,--*,rr)A-g?)
(?o)
,
ERTH = 4.45x$md"tx(h,*- hoo)U -.B,Ti
*RSHS, RLHS and GTHS aie ,supplementary loads due to
duct heat gain, duct leakageloss,fan and pump.horsqpower
gains, etc. To simplify the various examples, these sup.
plementar,y loads have not been used in the calculations.
Hofiever, in aitual. practice, thesesupplementary loads should
be ubedwhere appropriate. Chabter 7 gives the valuesfor the
various supplementary loads.Frg. l,Chapter 1, illustiates the
method of accounting for these supplementary loads on the
air conditioning load estimate.
lltern H, page .151,gives the derivation of these air constants.
fWhen no air is to be physically bypassedaround the conditioning apparalus, cf moo = ctfr
u.
E. TEMPERATURE
EQUATIONSAT APP.ARA
tudb** =
(fimo"x too)+ (cfn,ax t*)',:
4m*I
tuv
= ta6p * BF (t"db -
toap)
t"r6 and troDcorrespond t6 the calcu
of.ho,and h1non the psychrometric
'L
'ea
r** _ (cfrno"x hoo)+ (cf.mrox h,^)
4m"oI
hu
= hadp+ BE (h"r-
hoao)
"::
F. TEMPERATURE
EQUATIONS
FORSUPPIY
tao= I'^-
RSH
LogGf*-t)
**When tm, Wiltand h* are equal to the enterin$;,C.-a
rat the cooling apparatus, they may be substituted:
'll
.,1,
roand.h*respectively.
CHAPTER g, Rpp,rrEo,P.sIcHI(oMETRIcs
r-151
. 4 . . : . .
G. AIR QUANTITY
EQUATIONS
cfmao =cfffiro-
cfrnao
Note:
be less than
1.08x (,1"
Cfin6o, =
cfu*l=
cf.tnul
ERTH
4.48x (l : BF) ('k*TSH
L08(t"r- t")
TLH
,: .68(W"o - Wt)
cfm*l=
GTH
4'.45(h:*- hrn)
l1 '
l'.08,X.flr,i - f*o)
Cllll,"n
-
cftn"o
:
RLH
'.68
x (wr,,,-:wro)
(37)
huon)
(38)
(3e)
(40)
1.08= .Z++x 90
r3.5
'
where
i
E:
*
*.
F
f
}
"60 = *i,,'7'iir'" "
1'3,5.,=
specificvolumeof moistair
at70Fdb
and50l"gh
,
6q
1076
.68=
x
r3.5
7000
(4.t)
(43)
,244,=.s.pSqlfig
t1eatoJ moist air at
70 F db and 6|Toth,
: :
where
(44
hoo)
(44)
(46)
H. DERTVATION
Or IiN CONSTANTS
60 = rnin/h1
l3:5 : spec.ificvolume of rnoist air
*t,'r.0 Fdb,and b0l6nt.
1076 =:averag,G heat tenrsval re',.,
q u i r e d t o c o n d e n s eo n e
,,
pound of water vapor from
4.45=9.13.5
where,
RTH
4.45 x (h,,,-
cJ.rn"o only when
,efftL"o+.qfmon* cfrnro
,
RSIT
,
w.ill
conditioning apparatus.
ERIII
1!y7'-'
W
efm*
(45)
6{ = min/hr
13.5:. specificvolumg of moist air
at 70 F db and \tforh
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