Abstract: The small-scale vapor compression system based on a mini-channel heat sink was investigated in this work for battery thermal management. The single-factor experiment was carried out to determine the optimal refrigerant charge of the refrigerant cooling battery thermal management system. Based on the optimal refrigerant charge, the influence of different system parameters on thermal management performance was examined. Finally, the system problem was optimized, and the solution was proposed and verified by simulation software. Taking the coefficient of performance (COP) as the performance index, the optimum refrigerant charge of this system was 250 g, which was applied in the following experiments. Then the heating power of the battery module was fixed and the opening of the expansion valve (OEV) was adjusted to investigate the influence of OEV on cooling performance. The result showed that with the increase of OEV, the heat transfer coefficient of the mini-channel heat sink increased continuously, but the battery temperature decreased first and then increased. Thus, there was an optimal OEV to obtain the best cooling effect of the system. The heating power of the battery module was changed, and then the OEV was adjusted to make the temperature of the battery reach the minimum under different heating power conditions. The result indicated that with the increase of heating power of the battery module, the outlet dryness of the mini-channel heat sink continuously decreased, the heat transfer coefficient of the mini-channel increased, and the temperature of the battery also increased. The variation of ambient temperature was simulated by altering the indoor temperature with an air conditioner. The study showed that though the increase in ambient temperature had an impact on the cooling effect, the battery temperature can still achieve sub-ambient cooling even at the high ambient temperature of 35℃. A scheme of increasing condensation area to reduce compressor exhaust temperature was proposed, and the model was built based on AMEsim software for verification. The model analysis showed that the method of increasing the heat transfer area of the condenser can effectively reduce the exhaust temperature and improve the heat transfer effect.

Key words: refrigerant charge, OEV, heating power, ambient temperature, exhaust temperature

摘要： 本工作以基于微小槽道换热器的小型蒸气压缩系统为研究对象，对冷媒直冷电池热管理系统进行研究。确定了系统最佳冷媒充注量，总结了不同参数对系统热管理性能的影响规律，最后根据模型分析提出降低排气温度的改进方案。基于能效比(COP)最高的指标，确定系统冷媒最佳充注量为250 g。在固定加热功率条件下，随膨胀阀开度(OEV)的增加，微小槽道内的换热系数持续升高，而电池温度出现先降低后升高的趋势，因此存在最佳OEV使得电池温度最低；随电池模组加热功率增加，最佳OEV对应的蒸发器出口干度逐渐降低，虽然微小槽道换热系数有所升高，但是更快的加热功率增大速率使得电池温度升高；环境温度的升高对系统热管理性能产生不利影响，但是在35℃的高温环境下，电池温度依然能够被冷却至环境温度以下。基于AMEsim模型分析表明，增加冷凝器换热面积的方案，能够有效降低排气温度。

关键词: 冷媒充注量, OEV, 加热功率, 环境温度, 排气温度