Study of cascade air-source heat pump of high temperature hot water unit under different environment temperature

Aiming at the high compression ratio of an air-source heat pump heating system long running in low temperature conditions, studies the feasibility, operation characteristics and energy saving of the cascade air-source heat pump when producing high temperature water under different environment temperature. The results show that the performance coefficient of producing high temperature water increases, the suction and discharge of high level compressor increases slightly, the discharge temperature of low level compressor increases, and the suction and discharge pressures of high level compressor remains constant when the outdoor environment temperature increases, and that the system power consumption increases and the system COP decreases when the water temperature increases.