Abstract: The suitable operating temperature for lithium batteries should not be too high, and effectively controlling the temperature of the battery pack is one of the most important tasks in the new energy vehicle industry. A three-dimensional model of a bottom-to-top liquid-cooled battery pack was established, and the effects of coolant flow direction, type, velocity, flow channel structure, and heat-conducting ribbed plates on the cooling performance of the battery pack under a 2C discharge rate were studied through Fluent numerical simulation. The results show that: counter-current arrangement is better than co-current arrangement for heat dissipation; water and PG20 have better cooling effects, followed by fluorinated fluids, and then silicone oil. Within 100 ℃, PG20 still maintains good thermal stability and insulation, and its freezing point is lower than that of water, making it the best choice for a coolant. As the coolant flow rate increases, the maximum temperature,average temperature, and maximum temperature difference of the battery pack decrease, and the flow rate tends to stabilize after reaching a certain value. The leaf vein cooling channel battery pack has the lowest maximum temperature, average temperature, and maximum temperature difference. As the number of heat-conducting ribbed plates increases, the average temperature of the battery pack decreases,and the amplitude reduces, with the maximum temperature and maximum temperature difference no longer changing after the number of heat-conducting ribbed plates reaches a certain value.

    Key words: lithium battery pack; new energy vehicle; liquid cooling; thermal stability; runner structure; heat-conducting ribbed plate