# Thermal resistance by convection, air to tunnel

Convection thermal resistance between air and inner wall of the tunnel.

Symbol
$T_{at}$
Unit
K.m/W
Formulae
 $\frac{1}{0.023\pi k_{air} {\mathrm{Re}_{air}}^{0.8} {\mathrm{Pr}_{air}}^{0.4}}$ ventilated tunnel $\frac{1}{2\alpha_{at} \left(w_t+h_t\right)}$ in channel (Heinhold)
Related
$h_t$
$k_{air}$
$\mathrm{Pr}_{air}$
$\mathrm{Re}_{air}$
$w_t$
Used in
$T_{4iii}$
$T_a$
$T_s$
$T_t$