Constants $C_1$ - $C_7$ of multi-layer backfill

Constants $C_{b1}$ to $C_{b7}$ to be used in equations to caculate the segmental thermal resistances of the three flow paths $\Phi_1$, $\Phi_2$, and $\Phi_3$ of the multi-layer backfill method.

By way of Montecarlo optimization method, the best fit of the numerical data derived for the overall thermal resistance $R_{CG}$ was obtained with the values of the empirical constants $C_{b1}$ to $C_{b7}$ as published in the papers by R. de Lieto Vollaro 'Experimental study of thermal field deriving from an underground electrical power cable buried in non-homogeneous soils', 2014 and 'Thermal analysis of underground electrical power cables buried in non-homogeneous soils', 2011.