4680型锂电池复合热管理系统换热特性研究

Study on the Heat Transfer Characteristics of a Composite Thermal Management System for 4680 Lithium-Ion Batteries

摘要: 4680型锂离子电池具有容量大和能量密度高等优点，但其尺寸大，产热量高，易产生严重温升，面临安全性与性能退化等挑战。本文针对4680型锂离子动力电池设计了一种热管–间接液冷复合热管理系统，通过电池单体产热试验对电池产热模型进行了验证，并利用数值模拟探究了复合热管理系统换热特性与放电倍率、环境温度和冷却液流速之间的关系，讨论了冷却液流速对热管理系统经济性的影响。结果表明，在各种模拟工况下复合热管理系统均能将电池组温度有效控制在40˚C以下，但在高放电倍率下电池组内部无法保持良好的温度均匀性。提高冷却液流速有利于增强电池组整体换热能力，但受到电池内温度梯度影响，提升效果存在上限，而且高流速会导致泵功需求增加，影响系统经济性，综合考虑热管理性能与能耗成本，冷却液最佳流速为0.5  m/s。

Abstract: The 4680-type lithium-ion battery offers advantages such as high capacity and high energy density. However, due to its large size and high heat generation rate, it is prone to significant temperature rise, posing challenges in safety and performance degradation. Therefore, a hybrid thermal management system combining heat pipes and indirect liquid cooling is designed for 4680-type lithium-ion power batteries. The heat generation model of the battery is validated through experimental measurements on the battery cell. Numerical simulations are conducted to investigate the relationship between the heat transfer performance of the hybrid system and discharge rate, ambient temperature, and coolant velocity. Additionally, the effect of coolant velocity on the economic performance of the thermal management system is analyzed. The results indicate that the hybrid thermal management system can effectively maintain the battery pack temperature below 40˚C under all simulated conditions. However, at high discharge rates, the battery pack fails to maintain good temperature uniformity. Moreover, although increasing coolant velocity enhances the heat dissipation capacity of the pack, the benefit is constrained by internal temperature gradients within the battery cell. Additionally, higher flow velocity leads to increased pump power consumption, affecting economic efficiency. Considering both thermal performance and energy cost, a flow rate of 0.5 m/s is determined to be optimal.