Numerical study on latent heat thermal energy storage system with PCM partially filled with aluminum foam in local thermal equilibrium

Abstract

The effects of metal foams on Latent Heat Thermal Energy Storage System, LHTESS, based on a phase change material, PCM, is numerically investigated. The geometry of the system is a vertical shell and tube LHTESS made of two concentric tubes. A constant temperature above the melting temperature of the PCM on the internal surface of the hollow cylinder is assumed to simulate the heat transfer from a hot fluid. The external surfaces are adiabatic. The PCM is completely embedded in the volume between the two coaxial cylinders. An aluminum metal foam is chosen, and it partially fills the volume starting from the internal cylinder. The enthalpy-porosity theory and the Darcy-Brinkman-extended model are employed to simulate, respectively, the phase change of the PCM and the metal foam which is modelled in local thermal equilibrium. Ansys-Fluent code is adopted to solve the governing equations. The results are rendered in terms of melting time, liquid fraction, temperature, and stored thermal energy as a function of time and for different metal foam thickness values. The results indicate that the melting time reduces with increase in the thickness of the metal foam. The partially filled thermal storage system exhibits varying characteristics at the initiation and at the sustenance periods of the heating process. A scale analysis is performed to estimate the melting time and the values are in tandem with the numerical model evaluation.