Cableizer ®

Thermal resistance duct wall

Symbol
$T_{4ii}$
Unit
K.m/W
Formulas
$\frac{\rho_{d}}{2\pi} \ln\left(\frac{Do_{d}}{Di_{d}}\right)$Default
$F_{\alpha} T_{4ii}$buried inclined ducts
$\frac{\rho_{d}}{2\pi} \ln\left(\frac{Do_{d}}{Do_{d}-2t_{dp}}\right)$steel pipe with protective cover
Related
$Di_{d}$
Inner diameter duct [mm]
$Do_{d}$
Outer diameter duct [mm]
$F_{\alpha}$
Inclination derating factor [p.u.]
$\pi$
Archimedes' constant $\pi$
$\rho_{d}$
Thermal resistivity duct material [K.m/W]
$t_{dp}$
Thickness protective cover [mm]
Used in
$\Delta \theta_{c}$
Temperature rise conductor [K]
$\Delta \theta_{d}$
Temperature rise dielectric losses [K]
$\Delta \theta_{duct}$
Temperature rise duct (magnetic) [K]
$I_{c}$
Conductor current [A]
$Q_{B,ab}$
Thermal capacitance B transient thermal circuit, armour bedding [J/(m.K)]
$Q_{B,d}$
Thermal capacitance B transient thermal circuit, duct [J/(m.K)]
$Q_{B,f}$
Thermal capacitance B transient thermal circuit, filler [J/(m.K)]
$Q_{B,j}$
Thermal capacitance B transient thermal circuit, jacket [J/(m.K)]
$T_{4ss}$
Thermal resistance steady-state [K.m/W]
$T_{B}$
Thermal resistance B transient thermal circuit [K.m/W]
$T_{eq}$
Thermal resistance, equivalent [K.m/W]
$T_{r}$
Thermal resistance, total [K.m/W]
$\theta_{de}$
Temperature duct outer surface [°C]
$\theta_{di}$
Temperature duct inner surface [°C]
$U_{wall}$
OHTC pipe wall [W/(K.m$^2$)]