Optimal design of liquid cooling structure with bionic leaf vein branch channel for power battery

Effective thermal management is crucial for the thermal safety and uniformity of lithium-ion (Li-ion) batteries caused by high temperature. However, it is challenging for structural design and optimization method of cooling system especially considering dynamic heat generation of the battery. The liquid cooling plate with the bionic leaf vein branch (BLVB) channel which is sandwiched with a pouch Li-ion battery was proposed. The effects of multi-parameter coupling with inlet flow rate(M), channel width(D), channel angle(alpha) and channel number(N) of the cooling plate on the maximum temperature (T-max), the maximum temperature difference (Delta T-max) of battery and the average pressure drop of coolant (Delta P-avg) were investigated by using the orthogonal test range method. Based on the non-dominated sorting genetic algorithm-II (NSGA-II), the solution sets were optimized. Results show that the proposed BLVB channel is efficient for battery cooling. Even at 3 C discharge, T-max can be controlled within 33.34 degrees C. Meanwhile, M and D are the main factors affecting the cooling performance, alpha and N are the secondary factors. However, with the increasing of a or the decreasing of N, T-max and Delta T-max are decreased due to the enhancement of backflow or vortexes near the outlet. The optimal results are T-max = 30.31 degrees C, Delta T-max = 2.78 degrees C and Delta P-avg = 0.50 kPa; while the optimal parameters are M = 0.10 m/s, alpha = 159 degrees, N = 15 and D = 2.60 mm. Compared with the initial BLVB channel and the traditional parallel straight channel, T-max with the optimum BLVB channel can be reduced by 0.23 degrees C and 1.12 degrees C respectively when M = 0.10 m/s. The corresponding Delta T-max is declined by 0.28 degrees C and 1.64 degrees C, and Delta P-avg is decreased by 65.56 % and 8.77 % respectively. The proposed BLVB channel can be used to provide a certain reference for the thermal design of battery liquid cooling system.