The physical model of phase change heat storage tank was established by using ICEM CFD and gridded.Based on Fluent's unique Solidification/Melting model,the heat storage process of a phase change heat storage tank based on spherical packaging was simulated under the conditions of initial temperature 35 ℃,inlet flow rate 0.11 m/s and inlet temperature 98 ℃.The temperature and liquid phase rate curves in the process of phase change heat storage were obtained.The heat storage properties of three different physical models were studied and the forms of heat storage in the process of phase transition were analyzed.It is concluded that under the same heat storage,the heat storage time of the water tank with three different sizes (50,65 and 80 mm respectively) is 2 220,2 750 and 3 540 s.The overall heat storage time of the water tank with 50 and 65 mm phase change heat storage sphere is 1 320 and 790 s less than that of the water tank with 80 mm heat storage ball respectively,and the heat storage efficiency of the overall model is increased by 37% and 22% respectively.It is obtained that in the process of practical application,the reasonable selection of the diameter of the energy storage ball can effectively improve the heat storage efficiency.