以跨临界二氧化碳空气源热泵系统为研究对象，研究了电子膨胀阀开度、压缩机频率对系统COP以及制热量的影响，并提出更高效的热泵运行方案。实验结果表明:在不同的阀开度下，系统COP均出现先上升后下降的趋势，随着加热过程进行，阀开度越大COP下降的幅度越大；压缩机频率的提升会使系统最大COP下降；系统在75 Hz下加热水箱温度至38 ℃后，将系统频率调节至85 Hz可以使系统在保持高COP运行的同时减少加热时长，加热速率提升约18%。

The transcritical carbon dioxide air source heat pump system was taken as the research target,to research the impact of different adjustment methods on system performance and heating capacity by changing the openings of the electronic expansion valve (EEV) and the frequency of the compressor,and propose a operation plan for optimizing the heat pump. The experimental results show that as the heating process progresses,the COP and heating capacity of the system under different EEV openings both increase first and then decrease.The larger the openings of EEV is,the greater the decrease of COP is. The increase of the compressor frequency will reduce the maximum COP of the system.After the system heats the water tank temperature to 38 ℃ at 75 Hz,adjusting the system frequency to 85 Hz can reduce the heating time and increase the heating rate by about 18% while maintaining high COP operation of the system.

TK221