Study on melting and solidification performances improvement of phase change material using novel branch fin structure

A novel fin structure was proposed to improve the heat transfer characteristics of triple-tube latent heat storage system (TTLHSS). Ansys Fluent software is used for two-dimensional numerical calculation, and the model adopts melting/solidification model. The innovation of this paper is to develop a new type of fin that can simultaneously improve the solidification and melting process of PCM and optimize the structure of the new fin so that it can significantly shorten the time required to complete a heat storage and release cycle. Initially, the melting process of the case without fins and the case with new fins were compared. It was observed that compared with the case without fins, the melting and solidification time was shortened by 67.7 % and 74.8 %, respectively. Then the effects of the thickness, the length ratio, and the angle of the new fins on the melting and solidification process of PCM were studied. The liquid fraction contour of PCM in different cases and the liquid fraction curve of PCM with time were analyzed. The results show that the addition of new fins can significantly improve the heat storage and release rate of PCM in TTLHSS. Compared with rectangular fins, melting time and solidification time are reduced by 32.7 % and 52.9 % respectively. The new fins distribute the fin volume in the central area of the PCM which is difficult to melt, which improves the melting and solidification speed of the PCM and makes the overall rate more uniform. Finally, the geometric parameters of the fins are optimized by the response surface method (RSM), and the fin configuration with the cross fin thickness of 0.8 mm, the fin length ratio of 1, and the fin angle of 63.1 degrees is optimal for shortening the total time. At this time, the time required to complete a heat storage and release cycle is reduced by 84.5 % compared with the case without adding fins. The corresponding regression equation is also obtained, which provides a basis for the design of fins.