Heat transfer enhancement in thermal energy storage using phase change material by optimal arrangement

Abstract

The heat transfer rate of thermal energy storage (TES) applying phase change material (PCM) will be reduced in the last stage since the heat is transferred to the top of the enclosure by natural convection. One of the effective method to enhance the heat transfer is to heat the PCM at the bottom directly. Consequently, the optimal arrangement of the TES with eight heat transfer channels in melting and solidification processes is investigated in this paper. Ten kinds of arrangements are considered and five ones are set randomly. The effects of Rayleigh number are studied. The results show that the heat transfer rate increases firstly and then decreases with the rise of distance between centers of enclosure and heat sources. The heat source at the bottom will heat the bottom PCM directly and the total melting time can be reduced by 50% when the Rayleigh number is 105. In the solidification process, the heat transfer can be enhanced by increasing the distance between heat sources. Besides, the heat source absorbs heat from latent heat and the faster rate of solidification gets the temperature more uniform.