Numerical investigation of a dual-PCM heat sink using low melting point alloy and paraffin

Abstract For the purpose of reducing the weight and cost of low melting point alloy (LMPA) heat sink, a novel dual-phase change material (PCM) heat sink by using both LMPA and paraffin was proposed in this paper. A numerical model was developed by considering the conduction and natural convection in paraffin and the pure conduction in LMPA. The semi-implicit pressure-linked equation algorithm was adopted to obtain the flow field of liquid paraffin. The effects of volume fraction of LMPA, fin structure and heating power on the performance of dual-PCM heat sink were studied. The performance of dual-PCM heat sink was evaluated by the managed time and melting temperature interval. The results show that, the melting processes of the two PCMs are asynchronous due to the deference of thermophysical properties. The performance of dual-PCM heat sink is comparable with LMPA heat sink during the second melting stage. However, when the third melting stage is dominated by paraffin, the temperature management ability of heat sink deteriorates rapidly during the third melting stage. Moreover, by optimizing the fin structure and the LMPA volume fraction, we can effectively extend the second melting stage and improve the synchronization of the melting processes. With proper fin structure and LMPA volume fraction, the two PCMs can finish melting at the same time, then the third melting stage is eliminated and the melting temperature interval is minimized.