Radiation shape factor cable-tube

Radiation shape factor for concentric cylindrical annuli (cable to duct) such as for cables in j-tube/riser.

Symbol
$K_{int}$
Formulae
$\frac{1}{\frac{A_{cable} \rho_{di}}{D_{di} \epsilon_{di}} + 1 + \frac{\rho_{cable}}{\epsilon_{cable}}}$
Related
$\epsilon_{cable}$