psychrometric equations: standards & conversions info/psychrometric chart...-10 -5 0 5 10 15 20...
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-10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
DRY BULB TEMPERATURE - °F
0 5 10 15 20 25 30
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EN
THA
LPY
- B
TU P
ER
PO
UN
D O
F D
RY
AIR
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ENTH
ALPY
- BT
U P
ER P
OU
ND
OF
DR
Y AI
R
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VA
PO
R P
RE
SS
UR
E -
INC
HE
S O
F M
ER
CU
RY
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DE
W P
OIN
T TE
MP
ER
ATU
RE
- °F
Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com
1.00
0.95
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0.400.350.300.250.20SENSIBLE HEAT RATIO = Qs / Qt
SE
NS
IBLE
HE
AT
RA
TIO
= Q
s / Q
t
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15%
25%
2%
4%
6%
8% RELATIVE HUMIDITY
10% RELATIVE HUMIDITY20%
30%
40%
50%
60%
70%
80%
90%
-50
05
510
1015
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65 70
7075
7580 WET BULB TEMPERATURE - °F
80
85
12.0
13.0
14.0 VO
LUM
E- C
U.FT. P
ER
LB. D
RY
AIR
15.0
HU
MID
ITY
RA
TIO
- G
RA
INS
OF
MO
ISTU
RE
PE
R P
OU
ND
OF
DR
Y A
IR
Wet
Bul
b, S
atur
atio
n Te
mp
- °F
Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com
Psychrometric Equations:HT = CFM x 4.5 x ∆h HS = CFM x 1.085 x ∆THL = CFM x 0.68 x ∆WGR
HT = HS + HL
Where:HT = Total Heat (BTU/Hr)HS = Sensible Heat (BTU/Hr)HL = Latent Heat (BTU/Hr)∆T = Dry Bulb Temp Diff. (OF)∆h = Enthalpy Diff. (BTU/lb)∆WGR = Humidity Ratio Diff. (Grains/lb of Dry Air)
Standards & Conversions:1 lb moisture = 7000 GrainsDensity of Water = 8.34 lbs/galDensity of Air (Dry) = 0.075 lbs/ft3 (60OF, 14.7 psi)Latent Heat of Vaporization (Water) = 970 BTU/lb
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Dry Bulb (OF)
Humidity Ratio(Grains of Moisture/lb of Dry Air)
Enthalpy (BTU/lb) & Wet Bulb (OF)
RH
Satura
tion