空气的热力学性质

ρ kg m–3 957.6 0.1421 956.5 0.1504 948.2 0.2318 939.9 0.3460 931.5 0.5018 923.0 0.7089 914.4 0.9785 905.7 1.322 897.0 1.753 888.1 2.285 879.1 2.933 870.0 3.711 860.7 4.635 851.3 5.724 841.7 6.993 832.0 8.464
ρ kg m–3 822.0 10.16 811.8 12.09 801.4 14.29 790.7 16.78 779.7 19.60 768.4 22.76 756.7 26.32 744.6 30.31 732.1 34.78 719.1 39.79 705.5 45.41 691.2 51.73 676.2 58.84 660.3 66.88 643.4 76.04 625.1 86.55 605.3 98.76 583.3 113.2 558.3 130.6 528.3 152.6 488.3 182.7 411.2 235.4 302.6
Cv kJ kg–1 K–1
1.174 0.7184 1.173 0.7186 1.157 0.7198 1.143 0.7212 1.129 0.7230 1.115 0.7252 1.102 0.7277 1.090 0.7305 1.078 0.7338 1.067 0.7375 1.056 0.7416 1.045 0.7460 1.035 0.7510 1.025 0.7563 1.016 0.7620 1.007 0.7682
fied by the high densities in the liquid and the low densities in the vapor. Additional calculations at state points not listed below can be obtained by using the NIST program REFPROP (http://www. /srd/nist23.htm).
Thermophysical Properties of Air
Eric W. Lemmon
These tables summarize the thermophysical properties of air in the liquid and gaseous states as calculated from the pseudo-pure fluid equation of state of Lemmon et al. (2000). The first table refers to liquid and gaseous air at equilibrium as a function of temperature. The tabulated properties are the bubble-point pressure (i.e., pressure at which boiling begins as the pressure of the liquid is lowered); the dew-point pressure (i.e., pressure at which condensation begins as the pressure of the gas is raised); density (ρ); enthalpy (H); entropy (S); isochoric heat capacity (Cv); isobaric heat capacity (Cp); speed of sound (u); viscosity (η); and thermal conductivity (λ). The first line of identical temperatures is the bubble-point (liquid) and the second line is the dew point (vapor). The normal boiling point of air, i.e., the temperature at which the bubble-point pressure reaches 1 standard atmosphere (1.01325 bar), is 78.90 K (–194.25 °C).
Cp kJ kg–1 K–1
1.901 1.009 1.901 1.009 1.901 1.012 1.902 1.015 1.903 1.019 1.906 1.024 1.908 1.030 1.912 1.037 1.917 1.046 1.923 1.055 1.930 1.066 1.938 1.078 1.948 1.092 1.959 1.108 1.972 1.125 1.986 1.144
6-15
6-16
Thermophysical Properties of Air
T K 90 90 92 92 94 94 96 96 98 98 100 100 102 102 104 104 106 106 108 108 110 110 112 112 114 114 116 116 118 118 120 120 122 122 124 124 126 126 128 128 130 130 132 132 132.63
2. Lemmon, E.W. and Jacobsen, R.T, Viscosity and Thermal Conductivity Equations for Nitrogen, Oxygen, Argon, and Air, Int. J. Thermophys., 25, 21, 2004.
η µPa s 376.6 4.220 371.9 4.238 336.9 4.386 306.3 4.532 279.4 4.679 255.7 4.825 234.8 4.970 216.3 5.115 199.9 5.260 185.2 5.405 172.1 5.549 160.4 5.694 149.8 5.839 140.2 5.984 131.5 6.13mon, E.W., Jacobsen, R.T, Penoncello, S.G., and Friend, D.G., Thermodynamic Properties of Air and Mixtures of Nitrogen, Argon, and Oxygen from 60 to 2000 K at Pressures to 2000 MPa, J. Phys. Chem. Ref. Data, 29, 331, 2000.
Thermophysical Properties of Air along the Boiling and Condensation Curves
T K 59.75 59.75 60 60 62 62 64 64 66 66 68 68 70 70 72 72 74 74 76 76 78 78 80 80 82 82 84 84 86 86 88 88
S kJ kg–1 K–1 –0.5306 3.340 –0.5226 3.326 –0.4603 3.225 –0.3999 3.132 –0.3414 3.047 –0.2846 2.968 –0.2293 2.896 –0.1756 2.828 –0.1232 2.766 –0.07209 2.708 –0.02217 2.653 0.02665 2.602 0.07444 2.554 0.1213 2.509 0.1673 2.466 0.2125 2.425
H kJ kg–1 –36.66 185.5 –36.19 185.8 –32.38 187.7 –28.58 189.6 –24.77 191.5 –20.95 193.4 –17.13 195.2 –13.31 197.0 –9.468 198.7 –5.617 200.4 –1.751 202.0 2.132 203.6 6.036 205.1 9.962 206.5 13.91 207.8 17.90 209.1
u m s–1 1030. 154.8 1028. 155.1 1012. 157.6 995.8 160.0 979.1 162.3 962.2 164.5 945.1 166.7 927.7 168.7 910.0 170.6 892.1 172.5 873.9 174.2 855.4 175.8 836.7 177.4 817.6 178.8 798.2 180.0 778.6 181.2
P MPa 0.3048 0.2432 0.3609 0.2927 0.4243 0.3493 0.4954 0.4136 0.5749 0.4861 0.6631 0.5674 0.7608 0.6582 0.8684 0.7590 0.9864 0.8706 1.116 0.9934 1.256 1.128 1.409 1.276 1.575 1.437 1.755 1.612 1.948 1.801 2.156 2.007 2.379 2.229 2.617 2.468 2.872 2.727 3.143 3.006 3.429 3.308 3.723 3.646 3.785
λ mW m–1 K–1
171.4 5.294 171.0 5.320 167.8 5.529 164.5 5.739 161.3 5.950 158.0 6.162 154.7 6.376 151.4 6.592 148.1 6.810 144.8 7.031 141.5 7.256 138.2 7.485 134.8 7.719 131.4 7.959 128.1 8.206 124.8 8.461
The second table gives the properties of air along various isobars. An entry with non-integer temperatures in the isobar section indicates a phase transition (liquid–vapor) at these temperatures; property values are then given for both phases. These are identi-
P MPa 0.005265 0.002432 0.005546 0.002584 0.008270 0.004111 0.01200 0.006325 0.01699 0.009442 0.02352 0.01371 0.03191 0.01943 0.04250 0.02692 0.05566 0.03655 0.07179 0.04870 0.09129 0.06381 0.1146 0.08232 0.1422 0.1047 0.1745 0.1315 0.2121 0.1631 0.2553 0.2002
3. Lemmon, E.W., Huber, M.L., McLinden, M.O., NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP, Version 8.0, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, Maryland, 2007 (/srd/nist23.htm).