Numerical simulation of heat transfer for Al-Si@Al2O3 composite phase change heat storage particles

Composite phase change heat storage particles (CPCHSPs) parpered using metals and alloys with excellent thermal properties can be used in different fields such as solar thermal energy management, industrial waste heat recovery. Acquiring their heat transfer behavior in the thermal cycle process is the necessary for their utilization. Previous studies have focused mainly on low-temperature phase change heat storage materials, and the effect of thermal radiation has not been considered in their mathematical models. In this study, the combined effect of heat conduction, convective heat transfer, and thermal radiation was considered to simulate the heat transfer behavior during the melting/solidification of a CPCHSP. To ensure accurate simulations, a suitable value of the mushy zone parameter was selected (Amush = 107), and the results were verified experimentally. The results showed that when the thermal conductivity of the PCM remained lower than 20 W·m−1·K−1, the effect of radiation on the thermal storage time was greater than 10%. In the thermal cycle process, the Al-Si alloy melts from the bottom and moves upwards along the inner wall till completely melts, and then solidifies to form a “V” shape. An unstable position of the instant maximum value was observed during the melting/solidification process, and the overall maximum static pressure (Pmax, t) reached a peak value of 23 MPa after the Al-Si alloy had melted completely. Based on the Pmax, t observed, an air volume fraction of 18% is recommended in the optimized structural design of the CPCHSPs to maintain a low overall maximum static pressure for high heat storage.