Radiation heat transfer, object to duct

Radiation heat transfer from envelope around cables to inner wall of the duct used for riser/J-tube.

Symbol
$W_{rad_{od}}$
Unit
W/m
Formulae
$D_{o} K_{r} \pi \sigma \left(- \left(\theta_{di} + 273\right)^{4} + \left(\theta_{e} + 273\right)^{4}\right)$
Related
$D_{o}$
$\sigma$