Experimental results of a high efficient booster prototype system for sanitary hot water production using propane as refrigerant.

CO2 heat pumps has been used for sanitary hot water production due to its good performance working with high water temperature glides. Traditionally, it has been considered that these kind of systems are able to work in these conditions with a higher efficiency because they can match refrigerant temperature profile in the gas cooler to the water temperature in a better way than subcritical systems. This paper presents the experimental results obtained from a new heat pump booster prototype for sanitary hot water production up to 60ºC using propane as refrigerant and working in subcritical conditions. The system configuration is able to overcome the high water temperature glide (10ºC to 60ºC) using a system configuration in which the condenser is able to work at high subcooling without increasing significantly the condensing temperature. The obtained results present a high COP (5.4 in nominal conditions) which is quite competitive with most of the systems available in the market for these application.