Oil, lubricating and cooling the sliding parts of the compressorcomponents exposed to friction, could prevent refrigerant gas leakage in compressor chamber of vapor compression air conditioning system. For air condition heat pump system in electric vehicles, no oil circulating routes and oil separator are used to drive oil from system to compressor, making oil retainedmore difficult to control. Oil accumulated in heat exchanger and expansion valve would enhance pressure drops and reduce heat transfer capacity, leading to decrease of entire heating performance in cold climate. In this paper, a newly designed air conditioning heat pump system with R134a and PAG46 oil is introduced firstly, and oil circulation experiments were conducted on a full-scale electric vehicle. Typical heat transfer characteristics and system performance parameter were recorded and analyzed subsequently under different compressor oil charge conditions, including excessive charge and insufficient charge. Oil circulation rates in system were also measured and exhibited an increasing trend with compressor oil charge mass. Furthermore, heating performances of the system under different oil circulation rate were compared by various heating capacity and pressure drops. Results showed that both excessive and insufficient charge might decrease heating performance, i.e., determination of suitable oil charge is quite important for air condition heat pump system.

用油润滑和冷却压缩机部件的滑动部件并使其免受摩擦，可以防止制冷剂气体泄漏到蒸气压缩空调系统的压缩机室中。对于电动汽车的空调热泵系统，没有使用油循环路径和油分离器将油从系统驱动到压缩机，这使得滞留的油更加难以控制。积聚在热交换器和膨胀阀中的机油会增加压降并降低传热能力，从而导致在寒冷气候下整体加热性能下降。本文首先介绍了一种新设计的带有R134a和PAG46油的空调热泵系统，并在全尺寸电动汽车上进行了油循环实验。随后记录并分析了不同压缩机油加注条件下的典型传热特性和系统性能参数，包括过量加注和不足加注。还测量了系统中的机油循环速率，并显示出随着压缩机机油充气量的增加而增加的趋势。此外，通过各种加热能力和压降比较了在不同油循环速率下系统的加热性能。结果表明，充量过大和充量不足都会降低加热性能，即，确定合适的充油量对空调热泵系统非常重要。还测量了系统中的机油循环速率，并显示出随着压缩机机油充气量的增加而增加的趋势。此外，通过各种加热能力和压降比较了在不同油循环速率下系统的加热性能。结果表明，充量过大和充量不足都会降低加热性能，即，确定合适的充油量对空调热泵系统非常重要。还测量了系统中的机油循环速率，并显示出随着压缩机机油充气量的增加而增加的趋势。此外，通过各种加热能力和压降比较了在不同油循环速率下系统的加热性能。结果表明，充量过大和充量不足都会降低加热性能，即，确定合适的充油量对空调热泵系统非常重要。