蜂窝状CPCM/水冷复合式圆柱型锂电池散热性能

Heat dissipation performance of honeycomb-like thermal management system combined CPCM with water cooling for lithium batteries

为了进一步减小圆柱型锂电池在高热负荷下的温升、最大温差及轴向温差,提出一种基于石蜡/膨胀石墨(EG)的蜂窝状相变材料(PCM)水冷复合式电池散热结构。通过数值模拟,研究了环境温度40℃时,冷却液流速、微型流道数量、CPCM厚度及EG的质量分数对该系统散热性能的影响。结果表明,当液体流速超过0.05 m/s时,流速的继续增加对该系统散热性能的提升不明显。与纯PCM相比,添加EG制备的复合相变材料(CPCM)对系统散热性能有显著提升。EG质量分数为12%时,在不同液体流速下既可以满足电池最大温差的要求,也可以保证电池的最高温度和CPCM的液相率最低,即系统的综合散热效果最佳;综合考虑电池温度分布均匀性、空间利用率及系统的额外能量消耗,确定了CPCM的最佳厚度为2 mm;微型流道数量为6时,在不同液体流速下电池的最大温差和轴向温差最小。特别在4 C放电倍率下,流速为0.01 m/s时,电池的最高温度、最大温差及轴向温差分别为45.8、1.7、0.04℃,可以保证锂电池工作在最佳温度范围之内。

In order to further reduce the temperature rise,maximum temperature difference and axial temperature difference of cylindrical lithium batteries under high thermal load,a honeycomb-like battery thermal management system combined paraffin/expanded graphite(EG)phase change material(PCM)with water-cooling was proposed.Through numerical simulation,the effects of the coolant flow rate,the number of micro-channels,the thickness of CPCM(composite phase change material)and the mass fraction of EG on the heat dissipation performance of the system was investigated at the ambient temperature of 40℃.The results show that when the liquid rate exceeds 0.05 m/s,the continued increase in flow rate does not significantly improve the heat dissipation performance of the system.Compared with pure PCM,the CPCM mixed EG can significantly improve the heat dissipation performance of the system.When the EG mass fraction is 12%,and at different liquid flow rates,the maximum temperature difference of the battery can be met,and the maximum temperature of the battery and the liquid phase ratio of CPCM can be ensured to be the lowest,namely,the system has the best heat dissipation effect;comprehensively considering the uniformity of battery temperature distribution,space utilization and the additional energy consumption of the system,the optimal thickness of CPCM is determined to be 2 mm.When the number of micro-channels is 6,maximum temperature difference and axial temperature difference of battery is the smallest at different liquid flow rates;Especially at a 4 C discharge rate,when the flow rate is 0.01 m/s,the maximum temperature,maximum temperature difference and axial temperature difference of the battery are 45.8℃,1.7℃,and 0.04℃respectively,which can ensure that the lithium battery works within the optimal temperature range.