Simulation of spherical encapsulated ice of thermal energy storage system during freezing

Freezing characteristics of spherical encapsulated ice for thermal energy storage (TES) system are analyzed and important factors such as behavior of temperature inside spherical encapsulated ice is identified. An ice ball model was developed considering the heat transfer fluid (HTF) that flow across the ice ball containing phase change material (PCM). The model was simplified and the numerical simulations were validated by comparison with experimental results from previous study. The study shows that the rate of complete freezing of the ice ball is roughly three times the rate of diameter increment. The study also shows that it is critical to control the flow of the HTF inside the storage tank. The formation of ice was estimated based on the volume of ice formed at certain increment of time. The formation of ice for 94 mm ice ball is 4% faster than that of 103 mm ice ball.