Field performance of air-source heat pump in low-temperature region of north China

As the rapid development of economics and the deterioration of environment, development of sustainable energy is of vital importance. In north China, the traditional heating form in winter is boiler which has resulted in severe air pollution. The air-source heat pump, as a clean and efficient form of heating source, could be used as a new form of heating source. However, the running performance drops sharply as the outdoor temperature decreases, especially in winter of north China. As the development of compressor technology, several technologies have been utilized to solve this problem. The quasi two-stage compression with refrigerant injection is an effective method, which can decrease the discharge temperature and increase the coefficient of performance. Several site tests have been conducted during a long period in this paper. To investigate the operating performance of air-source heat pump applied in low-temperature region, several parameters were measured, including the energy consumption, the heating capacity and the outdoor temperature. Thus, the running performance is analyzed. The testing result shows that the coefficient of performance maintains above 2.8kW/kW when the outdoor temperature is -8℃ in Beijing. In Taiyuan of Shanxi province, the average heating capacity of an air-source heat pump water heater during the coldest month is 24.5kW, which is close to 75% of the rated heating capacity under much mild 7/6℃ working condition. The average hourly heating performance is 2.71kWh/kWh. The average hot water temperature is about 45.5℃.The testing data above proves that the air-source heat pump with scroll compressor of quasi two-stage compression shows great running performance in the cold region of north China, which could be a reasonable choice of heating device applied in north China.