External heat losses effect on shell and tube latent heat thermal energy storages partially filled with metal foam

A vertical cylindrical shell and tube Latent Heat Thermal Energy Storage (LHTES) system with internal corrugated tube is numerically analyzed. The phase change material (PCM) is partially filled with aluminum foam. The corrugated surface is assumed at assigned temperature higher than the melting temperature of the considered PCM. Heat losses toward the external ambient are also considered. The governing equations are written considering the Brinkman-Darcy-Forchheimer model and local thermal equilibrium assumption. The numerical model is developed using the finite volume technique employing enthalpy-porosity method to solve the melting problem. The solutions are carried out by means of the commercial code Ansys-Fluent. Numerical simulations are conducted for different metal foam filling levels, considering various porosity values and corrugations, both with and without thermal losses. Melting time, stored enthalpy, and thermal losses derived from numerical simulations are provided. The findings highlight that the melting time decreases more significantly with the filling ratio and porosity with respect to the decreases due to the increase in wave number and decrease in wave amplitude. The increase in heat losses determines an increase in melting time. For the cases with heat losses, the decrease in stored enthalpy is the lowest for the thermal energy storage totally filled with metal foam and the highest wave number. However, these cases also present the highest heat losses.