Air - Properties at Gas-Liquid Equilibrium Conditions
At standard conditions, air is a mixture of gases. However, at low temperature and high pressures the gas mixture becomes a liquid. The air phase diagram shows the phase behavior with changes in temperature and pressure. The curve between the triple point and the critical point shows the air boiling point with changes in pressure.
Critical point: The end point of the pressure-temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas cannot be liquefied by pressure alone. At the critical point, defined by the critical temperature T c and the critical pressure P c , phase boundaries vanish.
Critical temperature of air: 132.63 K = -140.52 °C = -220.94 °F
Critical pressure of air: 37.363 atm = 37.858 bar = 3.7858 MPa (MN/m2) = 549.08 psi (=lbf /in2)
Triple point: The temperature and pressure at which the three phases (gas, liquid, and solid) of a substance coexist in thermodynamic equilibrium
Triple point pressure of air: 0.05196 atm = 0.05265 bar = 5265 Pa = 0.7636 psi (=lbf /in2)
Triple point temperature of air: 59.75 K = -213.40 °C = -352.12 °F
The figures below show the changes in thermophysical properties along the air boiling and condensation curves: Vapour pressure , density , viscosity , heat capacity , thermal conductivity .
Tabulated values given in SI and imperial units, and unit converters are given below the figures.
See also properties of Air at varying temperature and pressure: Density and specific weight at varying temperature , Density at varying pressure , Diffusion Coefficients for Gases in Air , Prandtl Number , Specific heat at varying temperature and Specific heat at varying pressure , Thermal Conductivity , Thermal Diffusivity , and Air thermophysical properties at standard conditions and Composition and molecular weight ,
The following figures show how the properties of air changes along the boiling and condensation curves (shown in the figure above) - SI units:
Properties of air along the boiling and condensation curves - SI units:
For full table with thermal conductivity, dynamic and kinematic viscosity - rotate the screen!
Temperature | Pressure | Density | Heat capacity CV | Heat capacity CP | Thermal conductivity | Dynamic Viscosity | Kinematic viscosity | ||
---|---|---|---|---|---|---|---|---|---|
[K] | [°C] | [bara] | [g/l], [kg/m3 ] | [kJ/kg K] | [kJ/kg K] | [mW/m K] | [kcal(IT)/(h m K)] | [μPa s] | [cSt], [m2/s*10-6 ] |
Liquid | |||||||||
59.75 | -213.40 | 0.05265 | 957.6 | 1.174 | 1.901 | 171.4 | 0.1474 | 376.6 | 0.3933 |
65 | -208.2 | 0.1432 | 935.9 | 1.118 | 1.902 | 162.9 | 0.1401 | 292.4 | 0.3124 |
70 | -203.2 | 0.31908 | 914.6 | 1.102 | 1.908 | 154.7 | 0.1330 | 234.8 | 0.2567 |
75 | -198.2 | 0.63326 | 892.7 | 1.072 | 1.919 | 146.5 | 0.1260 | 192.4 | 0.2155 |
80 | -193.2 | 1.1462 | 870.2 | 1.045 | 1.938 | 138.2 | 0.1188 | 160.4 | 0.1843 |
85 | -188.2 | 1.9262 | 846.7 | 1.020 | 1.964 | 129.8 | 0.1116 | 135.8 | 0.1604 |
90 | -183.2 | 3.0475 | 822.2 | 0.9981 | 2.003 | 121.4 | 0.1044 | 116.4 | 0.1415 |
95 | -178.2 | 4.5886 | 796.2 | 0.9786 | 2.056 | 112.9 | 0.09709 | 100.7 | 0.1264 |
100 | -173.2 | 6.6313 | 768.5 | 0.9617 | 2.130 | 104.4 | 0.08978 | 87.61 | 0.1140 |
105 | -168.2 | 9.2606 | 738.6 | 0.9477 | 2.236 | 95.93 | 0.08249 | 76.41 | 0.1035 |
110 | -163.2 | 12.564 | 705.6 | 0.9373 | 2.389 | 87.55 | 0.07528 | 66.54 | 0.0943 |
115 | -158.2 | 16.633 | 668.5 | 0.9314 | 2.628 | 79.34 | 0.06822 | 57.57 | 0.0861 |
120 | -153.2 | 21.557 | 625.3 | 0.9325 | 3.048 | 71.36 | 0.06136 | 49.13 | 0.0786 |
125 | -148.2 | 27.427 | 571.4 | 0.9473 | 4.001 | 63.66 | 0.05474 | 40.76 | 0.0713 |
130 | -143.2 | 34.295 | 488.4 | 1.010 | 8.846 | 58.05 | 0.04992 | 31.07 | 0.0636 |
132.63 | -140.52 | 37.858 | 302.6 | 17.83 | 0.0589 | ||||
Gas | |||||||||
59.75 | -213.40 | 0.02432 | 0.1421 | 0.7183 | 1.009 | 5.294 | 0.004552 | 4.220 | 29.69 |
65 | -208.2 | 0.07756 | 0.4182 | 0.7219 | 1.017 | 5.844 | 0.005025 | 4.606 | 11.01 |
70 | -203.2 | 0.19431 | 0.9787 | 0.7275 | 1.030 | 6.376 | 0.005482 | 4.970 | 5.078 |
75 | -198.2 | 0.42282 | 2.006 | 0.7354 | 1.050 | 6.920 | 0.005950 | 5.333 | 2.658 |
80 | -193.2 | 0.82321 | 3.711 | 0.7459 | 1.078 | 7.485 | 0.006436 | 5.694 | 1.534 |
85 | -188.2 | 1.4665 | 6.336 | 0.7589 | 1.116 | 8.082 | 0.006949 | 6.057 | 0.9560 |
90 | -183.2 | 2.4320 | 10.16 | 0.7746 | 1.166 | 8.725 | 0.007502 | 6.427 | 0.6327 |
95 | -178.2 | 3.8047 | 15.50 | 0.7928 | 1.232 | 9.439 | 0.008116 | 6.810 | 0.4393 |
100 | -173.2 | 5.6742 | 22.77 | 0.8137 | 1.320 | 10.26 | 0.008819 | 7.215 | 0.3169 |
105 | -168.2 | 8.1341 | 32.49 | 0.8375 | 1.440 | 11.24 | 0.009662 | 7.659 | 0.2357 |
110 | -163.2 | 11.282 | 45.42 | 0.8651 | 1.614 | 12.47 | 0.01072 | 8.163 | 0.1797 |
115 | -158.2 | 15.223 | 62.75 | 0.8981 | 1.887 | 14.15 | 0.01216 | 8.770 | 0.1398 |
120 | -153.2 | 20.067 | 86.57 | 0.9399 | 2.373 | 16.64 | 0.01430 | 9.552 | 0.1103 |
125 | -148.2 | 25.949 | 121.5 | 0.9981 | 3.474 | 20.97 | 0.01803 | 10.68 | 0.0879 |
130 | -143.2 | 33.084 | 182.7 | 1.095 | 8.031 | 31.81 | 0.02735 | 12.78 | 0.0699 |
132.63 | -140.52 | 37.858 | 302.6 | 17.83 | 0.0589 |
Properties of air along the boiling and condensation curves - Imperial units:
For full table with thermal conductivity, dynamic and kinematic viscosity - rotate the screen!
Temperature | Pressure | Density | Heat capacity CV | Heat capacity CP | Thermal conductivity | Dynamic viscosity | Kinematic viscosity | |||
---|---|---|---|---|---|---|---|---|---|---|
[K] | [°F] | [psia] | [lb/ft3 ] | [sl/ft3 ] | [Btu(IT)/lb °F] | [Btu(IT)/lb °F] | [Btu(IT)/(h ft °F)] | [lbf s/ft2 *10-6] | [lbm /ft s*10-6 ] | [ft2/s*10-6 ] |
Liquid | ||||||||||
59.75 | -352.12 | 0.76363 | 59.79 | 1.858 | 0.2805 | 0.4541 | 0.09905 | 7.866 | 253.1 | 4.233 |
65 | -343.7 | 2.077 | 58.43 | 1.816 | 0.2671 | 0.4543 | 0.09413 | 6.107 | 196.5 | 3.363 |
70 | -334.7 | 4.6279 | 57.10 | 1.775 | 0.2632 | 0.4557 | 0.08940 | 4.904 | 157.8 | 2.763 |
75 | -325.7 | 9.1847 | 55.73 | 1.732 | 0.2560 | 0.4584 | 0.08464 | 4.017 | 129.3 | 2.319 |
80 | -316.7 | 16.624 | 54.32 | 1.688 | 0.2495 | 0.4628 | 0.07982 | 3.350 | 107.8 | 1.984 |
85 | -307.7 | 27.937 | 52.86 | 1.643 | 0.2437 | 0.4692 | 0.07499 | 2.836 | 91.24 | 1.726 |
90 | -298.7 | 44.200 | 51.33 | 1.595 | 0.2384 | 0.4783 | 0.07013 | 2.431 | 78.20 | 1.524 |
95 | -289.7 | 66.552 | 49.71 | 1.545 | 0.2337 | 0.4911 | 0.06524 | 2.103 | 67.65 | 1.361 |
100 | -280.7 | 96.179 | 47.98 | 1.491 | 0.2297 | 0.5088 | 0.06033 | 1.830 | 58.87 | 1.227 |
105 | -271.7 | 134.31 | 46.11 | 1.433 | 0.2264 | 0.5339 | 0.05543 | 1.596 | 51.35 | 1.114 |
110 | -262.7 | 182.23 | 44.05 | 1.369 | 0.2239 | 0.5707 | 0.05059 | 1.390 | 44.71 | 1.015 |
115 | -253.7 | 241.24 | 41.73 | 1.297 | 0.2225 | 0.6278 | 0.04584 | 1.202 | 38.69 | 0.927 |
120 | -244.7 | 312.66 | 39.04 | 1.213 | 0.2227 | 0.7279 | 0.04123 | 1.026 | 33.01 | 0.846 |
125 | -235.7 | 397.80 | 35.67 | 1.109 | 0.2263 | 0.9556 | 0.03678 | 0.8512 | 27.39 | 0.768 |
130 | -226.7 | 497.41 | 30.49 | 0.9477 | 0.2411 | 2.113 | 0.03354 | 0.6490 | 20.88 | 0.685 |
132.63 | -220.94 | 549.08 | 18.89 | 0.5872 | 0.3724 | 11.98 | 0.634 | |||
Gas | ||||||||||
59.75 | -352.12 | 0.3527 | 0.00887 | 0.000276 | 0.1716 | 0.2409 | 0.003059 | 0.0881 | 2.836 | 319.562 |
65 | -342.7 | 1.1249 | 0.02611 | 0.000811 | 0.1724 | 0.2429 | 0.003377 | 0.0962 | 3.095 | 118.544 |
70 | -333.7 | 2.8182 | 0.06110 | 0.001899 | 0.1738 | 0.2460 | 0.003684 | 0.1038 | 3.340 | 54.663 |
75 | -324.7 | 6.1325 | 0.1253 | 0.003893 | 0.1757 | 0.2508 | 0.003998 | 0.1114 | 3.583 | 28.608 |
80 | -315.7 | 11.940 | 0.2317 | 0.00720 | 0.1782 | 0.2574 | 0.004325 | 0.1189 | 3.826 | 16.514 |
85 | -306.7 | 21.270 | 0.3956 | 0.01229 | 0.1813 | 0.2665 | 0.004670 | 0.1265 | 4.070 | 10.290 |
90 | -297.7 | 35.273 | 0.6341 | 0.01971 | 0.1850 | 0.2785 | 0.005041 | 0.1342 | 4.319 | 6.811 |
95 | -288.7 | 55.183 | 0.9677 | 0.03008 | 0.1894 | 0.2942 | 0.005454 | 0.1422 | 4.576 | 4.729 |
100 | -279.7 | 82.297 | 1.421 | 0.04418 | 0.1943 | 0.3152 | 0.005926 | 0.0119 | 0.381 | 3.411 |
105 | -270.7 | 117.98 | 2.028 | 0.06304 | 0.2000 | 0.3440 | 0.006493 | 0.1600 | 5.146 | 2.537 |
110 | -261.7 | 163.63 | 2.836 | 0.08814 | 0.2066 | 0.3855 | 0.007207 | 0.1705 | 5.486 | 1.934 |
115 | -252.7 | 220.79 | 3.917 | 0.1218 | 0.2145 | 0.4506 | 0.008173 | 0.1832 | 5.893 | 1.504 |
120 | -243.7 | 291.05 | 5.405 | 0.1680 | 0.2245 | 0.5668 | 0.009612 | 0.1995 | 6.419 | 1.188 |
125 | -234.7 | 376.36 | 7.583 | 0.2357 | 0.2384 | 0.8298 | 0.01212 | 0.2231 | 7.177 | 0.947 |
130 | -225.7 | 479.84 | 11.41 | 0.3545 | 0.2616 | 1.918 | 0.01838 | 0.2668 | 8.584 | 0.753 |
132.63 | -220.94 | 549.08 | 18.89 | 0.5872 | 0.3724 | 11.98 | 0.634 |
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