Cableizer ®

Thermal resistance pipe wall

Symbol
$T_{4pii}$
Unit
K.m/W
Formulas
$\frac{\rho_{p}}{2\pi} \ln\left(\frac{Do_{p}}{Di_{p}}\right)$air-filled pipe
$\frac{\rho_{p}}{2\pi} \ln\left(\frac{r_{b}+t_{p}}{r_{b}}\right)$otherwise
Related
$Di_{p}$
Inner diameter enclosing pipe [m]
$Do_{p}$
Outer diameter enclosing pipe [m]
$\pi$
Archimedes' constant $\pi$
$r_{b}$
Equivalent radius backfill [mm]
$\rho_{p}$
Thermal resistivity pipe material [K.m/W]
$t_{p}$
Thickness enclosing pipe [mm]
Used in
$\Delta \theta_{air}$
Temperature increase air [K]
$T_{4db}$
Thermal resistance backfill correction [K.m/W]
$T_{4ss}$
Thermal resistance steady-state [K.m/W]
$\theta_{de}$
Temperature duct outer surface [°C]