Mathematical modeling of heterogeneous metal foams for phase-change heat transfer enhancement of latent heat thermal energy storage units

Abstract

Embedding phase change material in metal foams improves the heat transfer characteristics of a thermal energy storage device. Here, the melting heat transfer of phase change materials embedded in a heterogeneous metal foam was addressed in a cavity heated from a side wall. The heterogeneity of the metal foam can be controlled through a heterogeneity parameter and heterogeneity angle. The thermal conductivity and permeability of the metal foam were introduced by tensors. The governing equations for the natural convection flow and phase change heat transfer, including anisotropic thermal conductivity and permeability, were introduced and solved by the finite element method. The impact of the heterogeneity parameter and angle on the melting time and isotherm and streamline patterns were investigated. The results showed an increase in heterogeneity could increase the heat transfer rate and shorten the melting time. A heterogeneity angle significantly changes the melting (thermal charging time) by 24% when the heterogeneity parameter was 0.2. Depending on the heterogeneity angle, the melting time could be significantly shortened or extended compared to a simple metal foam. For a fixed weight of foam, a heterogeneous metal foam could shorten the charging time by 11% compared to a simple foam.