Experimental study on an inverter heat pump with HFC125 operating near the refrigerant critical point

An experimental study on an inverter heat pump with HFC125 operating near the refrigerant critical point was carried out. The coefficient of performance (COP) and exergy efficiency of the system were investigated under different compressor speed, water flow rate and different hot water temperatures of the condenser. The exergy defect in each component was determined. The results show that the exergy efficiency of the system increases initially and then decreases while the COP constantly decreases with the increase of the temperature of hot water. The results of this study can provide useful guidelines for optimal design and operation of this type of heat pump system in its present or future applications.