Numerical simulation on thermal stratification performance in thermocline water storage tank with multi-stage middle perforated obstacles

Abstract

• Three 3D geometric models of thermocline water storage tanks with different numbers of obstacles were established. • The effects of inlet velocities on the tank were analyzed. • The variations of obstacle numbers affect seriously the thermal stratification. Water storage tank is a critical part of the thermal storage system. This paper established three 3D geometric models of cylindrical thermocline water storage tanks with different numbers of middle perforated obstacles to enhance the thermal storage performance of the water storage tank. The numerical simulation method was used to investigate the influence of the number of middle perforated obstacles and inlet velocity on the thermal stratification degree of the tank. Results showed that the increase in the middle perforated obstacle number could optimize the thermal stratification of the thermocline water storage tank. In addition, when v i increases from 0.15 m/s to 0.30 m/s, and the charging dimensionless time t* changes from 0.2 to 1, the value of the thermal stratification number Str of the one obstacle tank decreases, while the changing trend of the tank with two is opposite, and the Str of the tank with three is always close to 1. The thermocline thickness of the tank with different numbers of obstacles is quite different. An increase of the number of obstacles can effectively suppress the increase of the thermocline thickness at high v i in the tank, which means a superior thermal performance was achieved for the tank.