In fluid thermodynamic calculations, the temperatures inside the convection boundary layer varies. An approximate average temperature is calculated, and this average temperature is used to read values from the table below. This average temperature is called the “film temperature”.
The formula for the film temperature is:
T_f = \frac {T_w + T_\infty} {2}
where:
Tf = film temperature
Tw = temperature at the surface of the solid boundary wall
T∞ = free-stream air temperature
| Temperature | Density | Specific Heat | Thermal Conductivity | Thermal Diffusivity | Dynamic Viscosity | Kinematic Viscosity | Prandtl Number |
| T (°C) | ρ (kg/m3) | Cp (J/kg.K) | k (W/m.K) | α (m2) | μ (kg/m.s) | γ (m2/s) | Pr |
| -20 | 1.3940 | 1005 | 0.02211 | 1.578 x 10-5 | 1.630 x 10-5 | 1.169 x 10-5 | 0.7408 |
| -10 | 1.3410 | 1006 | 0.02288 | 1.696 x 10-5 | 1.680 x 10-5 | 1.252 x 10-5 | 0.7387 |
| 0 | 1.2920 | 1006 | 0.02364 | 1.818 x 10-5 | 1.729 x 10-5 | 1.338 x 10-5 | 0.7362 |
| 5 | 1.2690 | 1006 | 0.02401 | 1.880 x 10-5 | 1.754 x 10-5 | 1.382 x 10-5 | 0.735 |
| 10 | 1.2460 | 1006 | 0.02439 | 1.944 x 10-5 | 1.778 x 10-5 | 1.426 x 10-5 | 0.7336 |
| 15 | 1.2250 | 1007 | 0.02476 | 2.009 x 10-5 | 1.802 x 10-5 | 1.470 x 10-5 | 0.7323 |
| 20 | 1.2040 | 1007 | 0.02514 | 2.074 x 10-5 | 1.825 x 10-5 | 1.516 x 10-5 | 0.7309 |
| 25 | 1.1840 | 1007 | 0.02551 | 2.141 x 10-5 | 1.849 x 10-5 | 1.562 x 10-5 | 0.7296 |
| 30 | 1.1640 | 1007 | 0.02588 | 2.208 x 10-5 | 1.872 x 10-5 | 1.608 x 10-5 | 0.7282 |
| 35 | 1.1450 | 1007 | 0.02625 | 2.277 x 10-5 | 1.895 x 10-5 | 1.655 x 10-5 | 0.7268 |
| 40 | 1.1270 | 1007 | 0.02662 | 2.346 x 10-5 | 1.918 x 10-5 | 1.702 x 10-5 | 0.7255 |
| 45 | 1.1090 | 1007 | 0.02699 | 2.416 x 10-5 | 1.941 x 10-5 | 1.750 x 10-5 | 0.7241 |
| 50 | 1.0920 | 1007 | 0.02735 | 2.487 x 10-5 | 1.963 x 10-5 | 1.798 x 10-5 | 0.7228 |
| 60 | 1.0590 | 1007 | 0.02808 | 2.632 x 10-5 | 2.008 x 10-5 | 1.896 x 10-5 | 0.7202 |
| 70 | 1.0280 | 1007 | 0.02881 | 2.780 x 10-5 | 2.052 x 10-5 | 1.995 x 10-5 | 0.7177 |
| 80 | 0.9994 | 1008 | 0.02953 | 2.931 x 10-5 | 2.096 x 10-5 | 2.097 x 10-5 | 0.7154 |
| 90 | 0.9718 | 1008 | 0.03024 | 3.086 x 10-5 | 2.139 x 10-5 | 2.201 x 10-5 | 0.7132 |
| 100 | 0.9458 | 1009 | 0.03095 | 3.243 x 10-5 | 2.181 x 10-5 | 2.306 x 10-5 | 0.7111 |
| 120 | 0.8977 | 1011 | 0.03235 | 3.565 x 10-5 | 2.264 x 10-5 | 2.522 x 10-5 | 0.7073 |
| 140 | 0.8542 | 1013 | 0.03374 | 3.898 x 10-5 | 2.345 x 10-5 | 2.745 x 10-5 | 0.7041 |
| 160 | 0.8148 | 1016 | 0.03511 | 4.241 x 10-5 | 2.42 x 10-5 | 2.975 x 10-5 | 0.7014 |
| 180 | 0.7788 | 1019 | 0.03646 | 4.593 x 10-5 | 2.504 x 10-5 | 3.212 x 10-5 | 0.6992 |
| 200 | 0.7459 | 1023 | 0.03779 | 4.954 x 10-5 | 2.577 x 10-5 | 3.455 x 10-5 | 0.6974 |
| 250 | 0.6746 | 1033 | 0.04104 | 5.890 x 10-5 | 2.760 x 10-5 | 4.091 x 10-5 | 0.6946 |
| 300 | 0.6158 | 1044 | 0.04418 | 6.871 x 10-5 | 2.934 x 10-5 | 4.765 x 10-5 | 0.6935 |
| 350 | 0.5664 | 1056 | 0.04721 | 7.892 x 10-5 | 3.101 x 10-5 | 5.475 x 10-5 | 0.6937 |
| 400 | 0.5243 | 1069 | 0.05015 | 8.951 x 10-5 | 3.261 x 10-5 | 6.219 x 10-5 | 0.6948 |
| 450 | 0.4880 | 1081 | 0.05298 | 1.004 x 10-4 | 3.415 x 10-5 | 6.997 x 10-5 | 0.6965 |
| 500 | 0.4565 | 1093 | 0.05572 | 1.117 x 10-4 | 3.563 x 10-5 | 7.806 x 10-5 | 0.6986 |
Reference: Heat and Mass Transfer, Fundamentals & Applications, Fifth Edition – by Yunus A. Çengel and Afshin J. Ghajar
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