Investigation of novel type of cylindrical lithium-ion battery heat exchangers based on topology optimization

The in-depth research on the heat exchanger for lithium-ion batteries is of significant importance due to its crucial role in ensuring the safe operation of electric vehicle (EV) power systems. To enhance the thermal and flow characteristic of the heat exchangers, the novel heat exchangers for 18650-cylinderical lithium-ion batteries have been proposed by topology optimization with the minimization of pressure drop and the lowest average temperature (∏1) and the minimization of pressure drop and the lowest temperature difference (∏2) as two different optimal goals. The topology optimization based on the variable density method is utilized to get two-dimensional (2D) optimal channels, and then the optimized results are extended to three-dimensional (3D) heat exchangers. The 3D heat exchangers are named TOHE-1 which is gotten by stretching the topology channels with ∏1 as optimal goal and TOHE-2 which is gotten by that with ∏2 as optimal goal. Subsequently, a detailed thermodynamic analysis is performed to assess the effect of the type of heat exchangers, channel heights, weight factor of topology optimization function, mass flow rates and discharge rates on the cooling effect of the batteries. The results show that compared with the traditional channel heat exchangers, the heat transfer coefficient of topological heat exchangers have increased by 49.92%, while reducing pressure drop by 27.81%. Meanwhile, compared to TOHE-1, heat transfer coefficient of TOHE-2 is increased by 9.70%, while pressure drop is saved by 4.70%. Other studies have indicated that for a 4 C discharge of the battery, a topological heat exchanger with a channel height of 1.5 mm, a thermal performance weight factor of 0.1, and a mass flow with 3.3 × 10−3 kg s−1 is the optimum heat dissipation scheme. Finally, the numerical studies are verified by conducting the convective heat transfer experimental tests.