# Radiation heat transfer coefficient, surface to air

Radiation heat transfer coefficient from surface of PAC/GIL to the surrounding air.

Symbol
$h_{rad,sa}$
Unit
W/(K.m$^2$)
Formulae
$4\sigma K_r \left(\frac{\theta_e+\theta_{film}}{2}+\theta_{abs}\right)^3$
Related
$\sigma$
$\theta_{abs}$
$\theta_e$
$\theta_{film}$
Used in
$W_{rad,sa}$