Critical Properties of Phase-Change Fluids
Material Properties Useful for the Real Gas Model

Critical-Point Properties
Substance

Formula

Molar Mass

Temperature

Pressure

Volume
. .

M

Tcr

Pcr

vcr
. .

kg/kmol

K

MPa

m^3/kmol
Air

--

28.97

132.5

3.77

0.0883
Ammonia

NH3

17.03

405.5

11.28

0.0724
Argon

Ar

39.948

151

4.86

0.0749
Benzene

C6H6

78.115

562

4.92

0.2603
n-Butane

C4H10

58.124

425.2

3.8

0.2547
Carbon Dioxide

CO2

44.01

304.2

7.39

0.0943
Carbon Monoxide

CO

28.011

133

3.5

0.093
Carbon Tetrachloride

CCl4

153.82

556.4

4.56

0.2759
Chlorine

Cl2

70.906

417

7.71

0.1242
Ethane

C2H6

30.07

305.5

4.48

0.148
Ethylene

C2H4

28.054

282.4

5.12

0.1242
Helium

He

4.003

5.3

0.23

0.0578
Hydrogen (normal)

H2

2.016

33.3

1.3

0.0649
Methane

CH4

16.043

191.1

4.64

0.0993
Neon

Ne

20.183

44.5

2.68

0.0419
Nitrogen

N2

28.013

126.2

3.39

0.0899
Oxygen

O2

31.999

154.8

5.08

0.078
Propane

C3H8

44.097

370

4.26

0.1998
Propylene

C3H6

42.081

365

4.62

0.181
Sulfur dioxide

SO2

64.063

430.7

7.88

0.1217
Tetrafluoroethane (R-134a)

CF3CH2F

102.03

374.3

4.067

0.1847
Water

H2O

18.015

647.1

22.064

0.0564

Note: The gas constant R can be calculated from R = Ru/M, where:

Ru is the Universal Gas Constant = 8.314 [kJ/kmol.K]
M is the Molar Mass [kg/kmol]

Adapted from TEST (The Expert System for Thermodynamics) <www.thermofluids.net> by S.Bhattacharjee, San Diego State University