Experimental study of a R407C liquid-to-water heat pump with domestic hot water production

Abstract

Currently, a number of companies manufacture liquid-to-water heat pumps for geothermal applications, based on the scroll compressor technology and using refrigerant R407C. The performance of this kind of machines depends greatly on the operating conditions, basically on the temperature levels of the liquid and water fluids. This paper presents an experimental study of a liquid-to-water heat pump with the possibility of domestic hot water (DHW) production. The refrigerant used is R407C. The main components of the heat pump are a scroll type compressor, a desuperheater for hot water production, two brazed plate heat exchangers (condenser and evaporator) and a thermostatic expansion valve with external equalizer. A liquid-vapor heat exchanger (LVHEx) has been included to check the effect of this heat exchanger on the heat pump performance. Experimental results for typical operating conditions of liquid-to-water heat pumps (EN 14511-2, 2013) in the heating mode of operation (low and medium temperature applications) are presented and discussed. Additional tests were performed to check the performance of the heat pump with DHW production at different water temperature values. From the experimental measurements, parameters such as the COP, heating powers or compressor electric power consumption were obtained and analyzed. The final goal of the paper is to characterize and to explain from a thermodynamic perspective the performance of the heat pump under different operating conditions.