Efficient integrated thermal management scheme is crucial for improving the driving range, thermal comfort, and safety of electric vehicles. Compared with the synthetic refrigerant heat pump indirect cooling/heating on the vehicle electrical system, the natural refrigerant CO heat pump direct thermal controlling integrated into the thermal management system has advantages in the thermal cycle performance and environmental friendliness. The present study proposed a thermal management system based on CO heat hump with multiple working modes for enhancing vehicle energy utilization coefficient. The system thermal performance under the World Light Vehicle Test Cycle was investigated via energy and exergy analyses. The operational control strategies of the thermal management system were optimized for the thermal controls of the cabin, battery and motor. The results show that the minimum exergy destruction of the thermal system occurs at the optimal discharge pressure corresponding to the highest coefficient of performance. Ensuring two-phase latent heat transfer for battery cooling is the most effective measure to maintain battery temperature uniformity via dynamic collaborative regulation of expansion valves’ openings and compressor speed. Compared with constant expansion valve’s opening, the coefficient of performance of the system can be improved by a maximum of 10% with the saturated CO vapor at the outlet of battery cooling plate. Due to the low thermal capacitance and minimal thermal inertia of driving motor, its cooling performance is significantly influenced by the heat generation rate and refrigerant flow. Optimal motor cooling efficiency is achieved when controlling the refrigerant quality to 0.85 at the cooling passage outlet. Under the World Light Vehicle Test Cycle, the thermal management system effectively regulated the temperatures across different operating modes while operating at optimal discharge pressures.

中文翻译：

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电动汽车CO2热泵热管理系统的冷却性能及优化

高效的集成热管理方案对于提高电动汽车的续驶里程、热舒适性和安全性至关重要。与车辆电气系统上的合成工质热泵间接冷却/加热相比，集成到热管理系统中的自然工质CO热泵直接热控制在热循环性能和环境友好性方面具有优势。本研究提出了一种基于CO热驼峰的具有多种工作模式的热管理系统，以提高车辆的能量利用率。通过能量和火用分析研究了世界轻型车辆测试循环下的系统热性能。热管理系统的运行控制策略针对座舱、电池和电机的热控制进行了优化。结果表明，在对应于最高性能系数的最佳排气压力下，热系统的火用破坏最小。通过动态协同调节膨胀阀开度和压缩机速度，确保电池冷却的两相潜热传递是保持电池温度均匀性的最有效措施。与恒定膨胀阀开度相比，电池冷却板出口处有饱和CO蒸气，系统的性能系数最多可提高10%。由于驱动电机热容低、热惯性极小，其冷却性能受发热率和制冷剂流量的影响较大。当冷却通道出口制冷剂质量控制在0.85时，可获得最佳的电机冷却效率。在世界轻型汽车测试循环中，热管理系统有效调节了不同运行模式下的温度，同时在最佳排气压力下运行。