Pore-scale numerical simulation of the thermal performance for phase change material embedded in metal foam with cubic periodic cell structure

Abstract

Pore-scale numerical simulation is conducted to study the thermal performance of composite change phase material (PCM). The low melting point paraffin wax R56 is selected as PCM. Aluminum foam with cubic periodic cell structure is designed, which not only possesses high thermal conductivity, high porous structure and low relative density but also can be rapidly manufactured by the new manufacturing technology. Hence it is an excellent candidate used as metal matrix of composites. The pore-scale numerical method is used to calculate the temperature variation and trace the melting evolution of composite PCM. The effects of geometrical parameters of metal foam such as porosities and pore densities on the thermal behavior of composite PCM are numerically investigated. It is observed from numerical results that the effects of aluminum foam on the thermal performance of composite PCM are very pronounced. Compared with the pure paraffin, the melting time for composite PCM is greatly shortened to 24.1% of that of pure paraffin. Also the effective thermal conductivity of composite PCM is drastically improved, e.g., the effective thermal conductivity can be enhanced about 123 times as much as that of pure paraffin. By comparing with the different porosities and pore densities composite PCMs, the geometrical parameters of aluminum foam have the distinct effects on the thermal performance of composite PCMs, e.g., the melting rate for composite PCMs with the low porosity or high pore density is higher as compared to the composite PCMs with the high porosity or low pore density. By analyzing the temperature-time history, it is demonstrated that there is local thermal non-equilibrium phenomenon between aluminum skeleton and paraffin during the melting process and local thermal non-equilibrium gradually weakens as the reduction of temperature difference between aluminum skeleton and paraffin.