Simulation study on heat transfer characteristics of a shell-and-tube phase change heat storage heat exchanger

This paper designs a cylindrical shell-and-tube phase change heat storage heat exchanger with paraffin as the phase change material. A numerical simulation of heat transfer is carried out based on the three-dimensional unit phase change heat storage model. The variation rules of the liquid phase ratio, temperature field, average temperature of the phase change material and the outlet temperature of the heat transfer medium are analysed, and the heat transfer characteristics of the shell-and-tube phase change heat storage heat exchanger during heat storage and release are studied. The results show that the natural convection of liquid paraffin can enhance the heat transfer between the phase change material and the heat transfer medium, and accelerate the melting and solidification rate of the paraffin. The effect of natural convective heat transfer is gradually evident after the liquid phase ratio reaches 18.6% in the heat storage phase. In the initial phase of heat release, the liquid phase ratio decreases by 63% within 80 s. The natural convective heat transfer is the strongest before the solid paraffin layer completely wrapped around the heat transfer tube bundle, and then gradually weakens.