One of barriers for the present heat pump system’s application in an electric vehicle was decreased performance under cold ambient conditions due to the lack of evaporating heat source. In order to improve the heat pump’s performance, a high-pressure side chiller was additionally installed, and the tested heat pump system was modified with respect to refrigerant flow direction along with operating modes. In the present work, the performance characteristics of the heat pump system with a high-pressure side chiller for light-duty commercial electric vehicles were studied experimentally under hot and cold ambient conditions, reflecting real road driving. The high-pressure side chiller was located after the electric compressor so that the highest refrigerant temperature transferred the heat to the coolant. The controlled coolant with discharged refrigerant from the electric compressor was used to heat up the cabin, transferring heat to the inlet air like the internal combustion engine vehicle’s heating system, except with unused engine waste heat. In the cooling mode, for the exterior air temperature of 35 °C and interior air temperature of 25 °C, cooling performance along with the compressor speed showed that the system efficiency decreased by 16.4% on average, the cooling capacity increased by 8.0% on average and the compressor work increased by 27% on average. In heating mode, at the exterior and interior air temperature of −6.7 °C, compressor speed and coolant temperature variation with steady conditions were tested with respect to heating performance. In transient mode, to increase coolant temperature with a closed loop from −6.7 °C, tested system characteristics were studied along the compressor speed with respect to heating up the cabin. As the inlet air of the HVAC was maintained at −6.7 °C, even though the heat-up rate of the cabin room was a little slow, the cabin temperature reached 20 °C within 50 min and the temperature difference with the ambient air attained 28.7 °C.

中文翻译：

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轻型商用电动汽车高压侧冷机热泵系统性能特性研究

由于缺乏蒸发热源，本热泵系统在电动汽车中的应用的障碍之一是在寒冷环境条件下的性能下降。为了提高热泵的性能，增设了一台高压侧冷水机，并对测试的热泵系统进行了制冷剂流动方向和运行模式的修改。在目前的工作中，用于轻型商用电动汽车的带有高压侧冷却器的热泵系统在冷热环境条件下进行了实验研究，反映了真实的道路驾驶。高压侧冷却器位于电动压缩机之后，以便最高的制冷剂温度将热量传递给冷却剂。带有从电动压缩机排出的制冷剂的受控冷却剂用于加热座舱，将热量传递到进气口，就像内燃机车辆的加热系统一样，但未使用的发动机废热除外。制冷模式下，室外气温35℃，室内气温25℃，制冷性能随压缩机转速的变化，系统效率平均下降16.4%，制冷量提高8.0%。平均，压缩机工作平均增加 27%。在加热模式下，在-6.7°C的外部和内部空气温度下，测试压缩机速度和冷却剂温度在稳定条件下的加热性能。在瞬态模式下，通过闭环将冷却液温度从 -6.7 °C 提高，测试的系统特性沿着压缩机速度与加热机舱有关。由于暖通空调的进风维持在-6.7℃，即使舱室升温速度稍慢，舱内温度在50分钟内达到20℃，与周围空气的温差达到28.7℃。