Cableizer ®

Thermal resistance radiation object—tunnel

Radiation thermal resistance between cable surface and inner wall of the tunnel.

Symbol
$T_{st}$
Unit
K.m/W
Formulas
$\frac{1}{\pi D_{o} K_{r} K_{t} \sigma \left(\left(\theta_{de}+\theta_{abs}\right)^2+\left(\theta_{t}+\theta_{abs}\right)^2\right) \left(\theta_{de}+\theta_{t}+2\theta_{abs}\right)}$ventilated tunnel (multi-system)
$\frac{1}{\pi D_{o} K_{r} K_{t} \sigma \left(\left(\theta_{o,L}+\theta_{abs}\right)^2+\left(\theta_{t,L}+\theta_{abs}\right)^2\right) \left(\theta_{o,L}+\theta_{t,L}+2\theta_{abs}\right)}$ventilated tunnel (IEC 60287-2-3)
$\frac{1}{\pi D_{o} K_{r} \alpha_{st}}$in channel (Heinhold)
Related
$\alpha_{st}$
Heat transfer coefficient radiation [W/(K.m$^2$)]
$D_{o}$
Outer diameter [m]
$K_{r}$
Radiation shape factor
$K_{t}$
Effective emissivity object surface
$\pi$
Archimedes' constant $\pi$
$\sigma$
Stefan Boltzmann constant [W/m$^2$K$^4$]
$\theta_{abs}$
Absolute temperature [K]
$\theta_{de}$
Temperature duct outer surface [°C]
$\theta_{o,L}$
Temperature object surface at outlet [°C]
$\theta_{t}$
Temperature wall (inner) [°C]
$\theta_{t,L}$
Temperature wall at outlet [°C]
Used in
$\Delta \theta_{s}$
Temperature difference surface—ambient [K]
$T_{4iii}$
Thermal resistance ambient [K.m/W]
$T_{a}$
Star thermal resistance air [K.m/W]
$T_{s}$
Star thermal resistance object [K.m/W]
$T_{sa}$
Thermal resistance convection object—air [K.m/W]
$T_{t}$
Star thermal resistance tunnel [K.m/W]
$\theta_{de}$
Temperature duct outer surface [°C]
$\theta_{fo}$
Temperature optical fiber [°C]
$\theta_{hsj}$
Temperature protective jacket [°C]
$W_{fo}$
Heat fiber optic cable [W/m]
$W_{hs}$
Heat dissipation heat source [W/m]