A comprehensive numerical study based on topology optimization for cooling plates thermal design of battery packs

Abstract

This article focuses on the problem of fluctuating cooling system flow caused by different working states such as acceleration and braking during the actual operation of electric vehicles, which prevents the system from effectively dissipating heat from the battery for a long time. In the past, liquid cooling heat dissipation schemes designed based on structural parameters often relied on the experience of CFD engineers. There is no in-depth study of the heat propagation characteristics. At present, research on the application of topology optimization method in cooling plate design mainly focuses on the relative positions of single inlet and outlet, objective functions, and constraint conditions. There are very few studies evaluating the adaptability of different cooling plate structures at different flow rates. In this perspective, this work proposes a two-dimensional topology optimization method for obtaining the cooling plates with different topological structures such as the series of cooling plate structures with dual entrances and exits. The method comprises of a comprehensive study on variations of the inlet flow rate under different average fluid volume fraction, outlet width, and temperature weight conditions. The results indicate that setting an excessive inlet flow rate can actually lead to an increase in the average temperature of the optimized cooling plate. Subsequently, the cooling plate structure obtained through topology optimization at inlet flow rates of 0.015 m/s, 0.02 m/s, and 0.025 m/s was selected, and a three-dimensional electrothermal fluid coupling model was established based on its two-dimensional channel structure. Its cooling performance, flow characteristics, and heat transfer characteristics were analyzed, and compared with two straight channel reference models. The results indicate that the optimized cooling plate structure under low flow conditions has better heat dissipation performance. At a flow rate of 0.56 × At 10-6m3/s, compared to traditional cooling plates(CASE D, CASE E), the highest temperature of the battery using topology optimized cooling plates (CASE A) decreased by 3.5 K and 1.79 K, respectively, and the standard deviation of temperature decreased by 48% and 14%, respectively. Under the same inlet flow velocity, the area of the fluid region increases with the increase of the mean fluid volume fraction, and the width of the flow channel increases gradually and the branches increase significantly, from the concentrated solid region to the dispersed isolated region. At a low flow rate, the normalized temperature of the cooling plate increases with the increase of the flow rate of the coolant inlet, and when the flow rate reaches a certain value, in order to reduce the power loss of the cooling plate, the flow path is gradually concentrated on both sides of the cooling plate. This leads to the decline of the normalized temperature of the cooling plate.