Strengthening of melting-solidification process in latent heat storage through sine wave shaped fins

Phase change materials (PCMs) offer an effective way to store thermal energy and balance the supply-demand mismatch in time and space. The melting-solidification process in PCMs is of main importance for the performance of the storage. To improve this process, numerical analyses are performed with PCM in a 2-D square-form cavity with two discrete heat sources and wavy sinusoidal shaped fins. The influence of different period and amplitude is analyzed to find the better fins arrangement. For the melting process, when the fin period is 20 and the amplitude is 2, the complete melting time of PCM is the shortest. In addition, fins with larger heat transfer area do not show better performance. For the solidification process, the optimal arrangement of fins is fins with period of 10 and amplitude of 5. The complete melting time can be shortened by more than 20.8 % and the complete solidification time could be shortened by more than 19 % compared to the case without any fins. Furthermore, in this study, the natural convection in the melting process is greatly affected by the fin area. When the fin area is large, the average value of natural convection is small, resulting in the maximum and minimum shortening of PCM melting time of 35.6 % and 20.8 %, respectively. The increase of fin area shows good heat transfer enhancement at the beginning of both melting and solidification process, but this strong strengthening effect does not continue throughout the melting/solidification process.