Effect of foam geometry on heat absorption characteristics of PCM-metal foam composite thermal energy storage systems

This paper presents a numerical study of the energy absorption characteristics of phase change material (PCM) based energy storage systems enhanced with metal foam structure. In particular, the effect of metal foam geometry on total energy absorption and melting of PCM is analyzed. A generalized geometry creation model is developed to create the foam geometry by using random distribution of overlapping spheres of constant or variable sizes. Different foam geometries are created by varying parameters such as pore radius, pore overlap distance and overall porosity. The main feature of the model is that instead of considering volume-averaged PCM-metal foam composite structure, individual pores of the metal foam are resolved, thus leading to more accurate representation of the heat transfer between the PCM and metal foam. The model is coupled with an enthalpy-based phase change model to simulate the effect of high temperature boundary condition on melting and heat absorption. Parametric studies reveal that smaller pore size is always preferable irrespective of the heat transfer duration. However, the optimum overlap and porosity is dependent on the heat transfer duration. Thus for developing an optimized system, these parameters should be judiciously selected based on the transient characteristics of the overall system. (C) 2019 Elsevier Ltd. All rights reserved.