An Experimental Study on the Heat Pump Water Heater System with Refrigerant Injection

Nowadays Heat pump water heater becomes a very hot topic in hot water industry. However it has many problems because of higher condensing temperature and large-scale operation conditions. Based on the problems, this paper presents a prototype which was assembled using a rotary compressor with refrigerant injection port. By making use of the liquid injection function of the compressor, the system can realize the quasi-dual compression in a single compressor, and thus it not only cools the compressor down, but also makes it possible for a simple heat pump system to operate in cold regions. The working principles and the basic features of the model are introduced in this paper. The operation performance was tested at different ambient temperatures, and defrosting was also discussed. According to the theoretic analyses and experiments, measures are taken to ensure the reliability and stability of the system. The results also indicated that the heat pump water heaters could be more reliable under large-scale operation conditions with high efficiency.