Cableizer ®

Heat transfer coefficient radiation cable—riser

Radiation heat transfer coefficient from cable surface to inner wall of the duct used for riser/J-tube.

Symbol
$h_{rad,int}$
Unit
W/(K.m$^2$)
Formulas
$\frac{\sigma K_{r} \left(\left(\theta_{e}+\theta_{abs}\right)^4-\left(\theta_{di}+\theta_{abs}\right)^4\right)}{\theta_{e}+\theta_{abs}-\theta_{di}+\theta_{abs}}$general
$\frac{\sigma \left(\theta_{e}+\theta_{abs}+\theta_{di}+\theta_{abs}\right) \left(\left(\theta_{e}+\theta_{abs}\right)^2+\left(\theta_{di}+\theta_{abs}\right)^2\right)}{1+\frac{1-\epsilon_{e}}{\epsilon_{e}}+\frac{D_{o} \left(1-\epsilon_{di}\right)}{D_{di} \epsilon_{di}}}$IEC 60287
Related
$D_{di}$
Inner diameter duct [m]
$D_{o}$
Outer diameter [m]
$\epsilon_{di}$
Emissivity duct surface (inner)
$\epsilon_{e}$
Emissivity cable
$K_{r}$
Radiation shape factor
$\sigma$
Stefan Boltzmann constant [W/m$^2$K$^4$]
$\theta_{abs}$
Absolute temperature [K]
$\theta_{di}$
Temperature duct inner surface [°C]
$\theta_{e}$
External temperature object [°C]
Used in
$T_{4i}$
Thermal resistance medium in the duct [K.m/W]