LAUSR

Abstract In order to achieve a COP of compression heat pumps greater than 6 with the temperature lift of at least 30 °C, a two-cycle parallel connected heat pump system is proposed in this paper. The theoretical simulation of the two-cycle parallel heat pump system is performed and the system performances under different condenser outlet water temperature are assessed. A heat pump prototype using the two-cycle parallel system with a heating capacity of 9000 kW is developed and an experimental study on the system performance is conducted. The results show that the COP of the two-cycle parallel system is 6.93 when the evaporator inlet/outlet water temperature is 30/25 °C and the condenser outlet water temperature is 60 °C. As the condenser outlet water increases from 60 °C to 68 °C, the heating capacity decreases by 6.8% and the power consumption increases by 11.6%. The two-cycle parallel heat pump system is able to lower the condensing pressure and power consumption, resulting in the improvement of the system COP. All the results indicate that the heat pump using two-cycle parallel system with gradual water heating has a good prospect in industrial heating applications for its high efficiency and great capacity.