Thermal resistance 13 of multi-layer backfill

Thermal resistance of 3rd segment along flow path $\Phi_1$ of the multi-layer backfill method.

Symbol
$R_{q13}$
Unit
K.m/W
Formulae
$\rho_{b1} \left(\frac{s_{b1}}{w_{b4}}+d_{im}\right)$Including a top layer
$\rho_{b2} d_{im}$Without top layer