# Thermal conductivity of air

The first formula for air in tunnel at atmospheric pressure is taken from IEC 60287-2-3.

The formulas for dry air at different pressures ate taken from paper by Daniel L. Carrol at al: 'Thermal Conductivity of Gaseous Air at Moderate and High Pressures', 1968

Symbol
$k_{air}$
Unit
W/(m.K)
Formulae
 $2.42{\cdot}{10}^{-2}+7.2{\cdot}{10}^{-5} \theta_{at}$ IEC 60287-2-3 @ 1 atm. $24.545+0.0765\theta_{gas}-5{\cdot}{10}^{-5} {\theta_{gas}}^2$ dry air @ 1 bar (Carroll1968) $24.762+0.075\theta_{gas}-4{\cdot}{10}^{-5} {\theta_{gas}}^2$ dry air @ 5 bar (Carroll1968, interpolated) $24.979+0.0734\theta_{gas}-3{\cdot}{10}^{-5} {\theta_{gas}}^2$ dry air @ 10 bar (Carroll1968, interpolated) $25.586+0.0692\theta_{gas}-4{\cdot}{10}^{-6} {\theta_{gas}}^2$ dry air @ 25 bar (Carroll1968) $27.222+0.0635\theta_{gas}-4{\cdot}{10}^{-5} {\theta_{gas}}^2-5{\cdot}{10}^{-7} {\theta_{gas}}^3+{10}^{-8}{\theta_{gas}}^4$ dry air @ 50 bar (Carroll1968)
Related
$k_{gas}$
$\theta_{at}$
$\theta_{gas}$
Used in
$C_{vair}$
$T_{at}$
$T_{sa}$
Choices
GasPressure0°C15°C25°C50°C75°C100°C
Air1 bar0.0245450.0256810.0264260.0282450.0300010.031695
Air5 bar0.0247620.0258780.0266120.0284120.0301620.031862
Air10 bar0.0249790.0260730.0267950.0285740.0303150.032019
Air25 bar0.0255860.0266230.0273140.0290360.0307540.032466
Air50 bar0.0272220.0281640.0287810.0302970.0318650.033672