车用锂电池组热流场特性数值模拟与优化设计

针对车用电池温升过高、电池组温差大的问题,开展电池包热流场分析与优化设计.根据Bernardi的生热速率方程式,建立由电池电解液、正负极柱和隔膜四部分组成的单体电池热耦合模型及成组电池传热模型;利用Fluent软件分析锂电池单体在自然对流环境下的温升特性,研究成组电池在强制对流条件下的热流场特性;通过增加导流板优化电池箱内流场结构,并评估导流板对电池组散热效率的作用.结果表明:单体锂电池在自然对流下温升明显,电池内核温度远高于正负极柱温度;电池箱进出风口位置及结构决定箱内空气的流向和成组电池的散热效果;通过对进、出风口位置的设计及增加导流板,可有效改进电池组热流场的均匀性,从而提高散热效果.

Numerical Simulation and Optimization Design of Thermal Flow Field Characteristics of Lithium-Ion Battery Pack for Vehicles

In order to solve the problem of temperature sharp rising and significant thermal difference among the battery modules of electric vehicles, a study of thermal flow analysis and optimization on battery pack was carried out. A thermal coupling model with four parts, namely a single cell electrolyte, a positive plate collector, a negative plate collector and a battery plate was established. A heating transferring model of individual battery was also established based on Bernardi heat generation rate model; then using Fluent software the heat generation characteristics of lithium battery monomer in natural convection environment was investigated and the effect of flow structure on the heat radiation was assessed with an optimized battery pack model. The re-sults indicate that the individual lithium battery temperature rises sharply under natural convection, while temperature increment of positive pole core is far higher than that of negative pole core; the inlet structure greatly influences the velocity field of cooling air and temperature distribution of the battery; and the uniformity of the battery thermal flow can be significantly improved by reasonably designing the air inlet and outlet positions and adding a guide plate, which can further enhance the cooling effect.