No abstract

Hydrothermal performances of two water-cooled thermal management systems (TMSs) for cooling lithium-ion batteries (LIBs) are compared through three-dimensional simulations of laminar flow and heat transfer in TMSs, as well as conduction heat transfer with volumetric heat generation inside the battery cell. Maximum cell temperature and temperature variation across the cell are used to evaluate thermal performances of TMSs. The TMSs are different from each other by location of outlet manifold. In the bottom outlet (BO) design, the outlet is located at the bottom of the TMS's case, while in the middle outlet (MO) design, the outlet manifold is located at the middle of the TMS's case. Both designs provide safe operational temperature for LIBs, although the thermal performance of BO design is slightly higher than that of the MO design. This is due to distribution of water over a larger surface area in the BO TMS compared with the MO TMS. To provide a better insight on practical applications of TMSs, their thermal performances are described based on pumping power. Due to a shorter path from the inlet to the outlet in the MO design, compared with the BO design, the pressure drop is lower in the MO TMS. As a result, at a given flow rate, the MO TMS operates with a lower pumping power compared with the BO TMS. The present study suggests that selecting an appropriate TMS highly depends on design priorities. If the main goal is to maintain the cell temperature as low as possible, the BO design is an effective TMS. If the design goal is to minimize the pumping power, the MO TMS is an effective cooling system.

Heat transfer and pumping power of water-cooled thermal management systems (TMSs) for lithium-ion batteries (LIBs) in electric vehicles (EVs) are investigated through a three-dimensional computational approach. TMSs are cylindrical shells that cover LIBs. Water flows through the shell and removes heat from LIBs. The focus of this study is to provide practical insights on the effects of number of inlets on the thermal performance and pumping power of TMSs. Two TMSs with one and four inlets at the top of the TMS's case are considered. Both TMSs include one outlet, which is located at the bottom of the case. The thermal performance of individual TMSs is evaluated by the maximum temperature of the battery cell and the temperature difference across the cell. The thermal performances are described based on the pumping power. Simulations are performed at different flow rates within a laminar regime. Results indicate that both TMSs provide safe operational temperatures for LIBs. However, compared to the one-inlet design, the four-inlet TMS archives the same thermal performance but at a lower pumping power. The lower pumping power is due to lower pressure drop in the four-inlet TMS resulting from flowing water with lower flow rate at individual inlets, and through a shorter path from individual inlets to the outlet, compared with the one-inlet TMS. Minimizing pumping power without any penalty in the thermal performance is significantly beneficial, especially when the TMS is used for a pack of LIBs in EVs.