Numerical study on latent heat thermal energy storage with phase change material and metal foam in shell and corrugated tube with external heat losses

Abstract

In the present work, a numerical investigation of the Latent Heat Thermal Energy Storage system (LHTESs) is performed on a vertical shell and tube geometry, made of a porous medium filled with a phase change material (PCM). The LHTESs is a cylinder with a corrugated inner surface at a constant temperature above the PCM melting temperature; on the external surface there are heat losses to the outside and the top and bottom surfaces are adiabatic. The PCM used is a pure paraffin wax, the metal foam, instead, is made of aluminum. The phase change process is modelled with the enthalpy-porosity theory, while the Local Thermal Non-Equilibrium (LTNE) and the Darcy-Forchheimer models are adopted to analyse the heat transfer between the paraffin and the metal foam. The solutions of the governing equations are computed with Ansys-Fluent commercial code. The survey considers different conductivity variations on the external wall and distinct corrugated wall geometric parameters, with different wavelengths and wave amplitudes. The results of the numerical simulations, concerning the LHTESs charging phase, are reported as a function of time and compared in terms of melting time, enthalpy stored, and energy loss.