Multivariate analysis of heat transfer enhancement of large capacity prismatic battery thermal management system based on reflux box

In order to ensure the normal operation of power batteries in very high temperature environment (T0 = 35 degrees C), a new battery thermal management system (BTMS) is developed in this paper. An innovative combination of nonisometric flow channels and a bottom return box is used to simultaneously enhance the heat transfer in the dense heat-producing zone at the top of the cell and to strengthen the temperature uniformity of the BTMS. Comparative studies of coolant input, isometric and non-isometric flow channels were designed, and orthogonal experimental designs for multi-objective optimization of the BTMS were conducted with maximum temperature (Tmax), mean temperature (Tave), maximum temperature difference (dTmax), flow loss (dP) and entropy generation (sg) as the objective functions, respectively. The results show that the BTMS with return flow has an enhanced cooling performance and temperature uniformity compared with the pure liquid cooling system. The Tmax and Tave of the BTMS at the optimal working point are 30.28 degrees C and 29.17 degrees C, respectively. Compared with the pure liquid cooling BTMS at the same flow rate, they are reduced by 1.72 degrees C and 1.69 degrees C, respectively, and the dTmax is reduced by 20.8 %. Compared with the BTMS with the strongest cooling performance operating point, the dTmax of the BTMS at the optimal operating point increased by about 0.24 degrees C, but the dP decreased from 62.86 Pa to 36.22 Pa, decreasing by 42.38 %.