Experimental investigation on matching a conventional water source heat pump with different refrigerants for supplying high temperature water

Abstract In this paper, the high temperature performance of an existing conventional water source heat pump was investigated, with independently developed refrigerants named as BY-5 and NBY-1. First, an experimental investigation on the effect of the four-way reversing valve on heat pump with BY-5 was executed at the evaporating temperature of 80°C and the condensing temperature of 120°C. The results showed that the heating capacity, COP, exergy efficiency of the system increased up to 31.86%, 33.59%, and 22.59% high, respectively, after removing four-way reversing valve. Then, the optimum performance of the system was explored by changing expansion valve opening, while outlet water temperature of condenser was in the range of 115°C-130°C. It could be found that the COP reached the highest value when the expansion valve opening was 220pulse. Moreover, a new refrigerant NBY-1 was proposed for the transformed system to push the limits of outlet water temperature of the condenser up to 130°C. It was obvious that heating capacity, COP and exergy efficiency was 15.36kW, 2.74 and 0.55, respectively, which were 12.42%, 19.93%, and 13.32% higher than those using BY-5. In summary, NBY-1 has apparently better working properties and is more compatible with existing heat pump.