Temperature of duct outer wall

This is the temperature of the outer surface of a duct or a riser/J-tube.

With crossing heat sources, a temperature rise of $\Delta\theta_{0x}$ applies at the hottest point.

$\theta_{di}-T_{4ii} n_{cc} W_t+\frac{T_{4ii} W_{duct}}{2} n_{cc}$Cables in duct
$\frac{W_{tot} T_{st} T_{sa}+\theta_t T_{sa}+\theta_{at} T_{st}}{T_{sa}+T_{st}}$Cables,Heat sources or PAC/GIL in ventilated tunnel
$\theta_{di}-T_{4ii} n_{cc} W_t$Cables in trough
$\theta_{di}-T_{4ii} n_{cc} W_t$Cables in riser
$\theta_{di}-T_{4ii} W_{hs}$Heat sources in duct
$\theta_a+v_4 \Delta \theta_p+\left(1-v_4\right) \Delta \theta_x+n_{cc} W_{tot} v_4 T_{4\mu}$PAC/GIL buried in duct
$\theta_{di}-T_{4ii} W_{sum}$Air-filled pipe with ducts