Thermal storage performance of a novel spiral shell-tube phase change heat energy storage system

The conical spiral shell-tube phase change thermal storage system has the advantages of large heat transfer area and high thermal storage efficiency, but it is still limited by the low thermal conductivity of phase change materials and the problem of the “melting dead zone”. Therefore, the influence of spiral tube diameter, spiral pitch, and spiral taper on the melting process of the novel conical spiral shell phase change heat storage system is numerically analyzed using the enthalpy-porosity method, and the superiority of the novel conical tube is verified by comparing it with the traditional cylindrical spiral tube. The results indicate that the tube diameter has an optimal threshold value. Under the condition of optimal tube diameter, the system melting time can be shortened by 18.9 %. In addition, the spiral pitch and lower taper have a significant effect on the thermal storage performance. Compared with the traditional cylindrical spiral tube, the average thermal storage efficiency of the novel spiral tube is increased by 36.4 %, and the exergy efficiency of the system is increased by 6.4 %. This study provides theoretical support for the design of spiral shell-tube phase change thermal storage system, promoting the efficient utilization of renewable energy sources, particularly solar energy.