This document contains two psychrometric charts that illustrate the thermodynamic properties involving temperature and humidity of air, such as enthalpy, humidity ratio, and sensible and total heat. The charts were prepared by the Center for Applied Thermodynamic Studies at the University of Idaho and show lines representing saturation temperature, relative humidity, and enthalpy. They can be used to determine thermodynamic values like sensible and total heat of air at different dry bulb temperatures, wet bulb temperatures, and humidity ratios.

1. Appendix 1 | 929
•
5.0
1.0 1.5
0.8
0.7
Prepared by Center for Applied Thermodynamic Studies, University of Idaho.
0.36
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.0
Enthalpy
——————
Humidity ratio
Δh
—— Δ
=
ΔHS —— ΔHT
=
—Se—nsi—bl—e h—ea–t
Total heat
120
110
100
90
80
60
25 wet bulb temperature °C
20 30 40 50
Dry bulb temperature °C
0 10
70
—Se—nsi—bl—e h—ea–t
Total heat
ΔHS —— ΔHT
=
1.0 –•
–5.0
–2.0
0.0
2.0
4.0
–1.0
– 0.5
1.0
2.5
2.0
0.1
0.2
0.3
0.4
0.5
0.6
3.0
4.0
10.0
–0.2
•
–4.0
–2.0
0
Enthalpy (h) kilojoules per kilogram dry air
20
30
40
50
60
70
80
90
100
Saturation temperature °C
5
10
15
20
25
30
30
0.94
30
20
15
10
5
0
0.90
0.88
0.86
0.84
0.82
0.80
0.78
28
90%
80%
70%
60%
50%
40%
30%
20%
26
24
22
20
18
16
14
12
10
8
10% relative humidity
0.92 volume cubic meter per kilogram dry air
Humidity ratio () grams moisture per kilogram dry air
6
4
2
ASHRAE Psychrometric Chart No. 1
Normal Temperature
Barometric Pressure: 101.325 kPa
©1992 American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc.
Sea Level
FIGURE A–31
Psychrometric chart at 1 atm total pressure.
Reprinted by permission of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA; used with permission.
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