Numerical study on melting-solidification cycle of phase change energy storage unit: Role of fin and metal foam hybrid structure

Abstract

The low thermal conductivity inherent to phase change materials (PCMs) presents challenges for implementing phase change energy storage (PCES) technologies. In this study, the enhanced heat transfer properties of 9 fins, copper metal foam with 0.98 porosity-10 PPI, and fin-metal foam composite structures are compared with pure PCM structures in square PCES units. The charging and discharging process of four structures in a complete heat storage and release cycle is studied by numerical simulation. Firstly, feasibility analysis and experimental verification are carried out to verify the accuracy of the numerical model. Then, the liquid phase behavior, temperature gradient and energy storage/release performance of the four PCES structures are compared. The results show that the fin-metal foam composite structure can further improve the phase transition rate compared with a single enhanced heat transfer measure. During melting and solidification, the storage period and release period of PCM structure are shortened by 83.91 % and 96.38 % respectively. At the end of the charging and discharging process, the average heat storage and heat release rate of the composite structure are 466.40 % and 24.91 times higher than that of the pure PCM structure, respectively. However, due to the use of fin-metal foam, the amount of heat absorption and release in the phase change material is reduced by 9.08 % and 5.89 %.