为研究膨胀阀开度和压缩机频率对循环加热式CO2热泵制热性能的影响，采用实验的方法研究了阀开度35%，37%，40%和频率75，80，85 Hz工况下制热量和制热系数COP瞬时值和平均值以及加热时间的变化。结果表明：随着压缩机频率增加，平均制热量和最大瞬时制热量增加，平均COP和最大瞬时COP减小，加热时间缩短；随着阀开度增大，平均制热量和平均COP减小，最大瞬时制热量和COP增大，加热时间延长；当压缩机频率一定时，在不同的水箱温度范围采用合适的膨胀阀开度可以有效提高热泵的平均COP；以本文75 Hz工况为例，当水温小于25.9 ℃时采用40%开度，当水温在25.9~35.4 ℃之间时采用37%开度，当水温大于35.4 ℃时采用35%开度；合理匹配开度和频率可以最大程度提高平均制热量，同时抑制平均COP的减小。

In order to study the effect of the expansion valve opening and the compressor frequency on the performance of the circulating heating CO2 heat pump system, the variety of the instantaneous values and averages of heating and coefficient of performance (COP) and heating time under the valve opening degrees of 35, 37 and 40% and the frequencies of 75, 80 and 85 Hz was investigated by experiments. The results show that with the increase of compressor frequency, the averages and the maximum instantaneous values of the heating capacity increase, the averages and the maximum instantaneous values of COP and the heating time decrease; additionally, as the valve opening degree increases, the average heating capacity and COP decrease, the maximum instantaneous values of them increase, and the heating time increases; when the compressor frequency is constant, the average COP of heat pump can be improved with suitable expansion valve opening degree in the range of different water tank temperatures; taking the working condition of 75 Hz as an example, when the water temperature is less than 25.9 ℃, the valve opening degree should be 40%; when the water temperature is 25.9 to 35.4 ℃, the valve opening should be 37%; and when the water temperature is greater than 35.4 ℃, the valve opening should be 35%; meanwhile, reasonable matching of the opening degree and frequency can maximize the average heat capacity and suppress the reduction of the average COP.

TK221

上海市动力工程多相流动与传热重点实验室项目 (13DZ2260900)