Refrigerant-based measurement method of heat pump seasonal performances

There is no reliable measurement method of air-to-air heat pump seasonal performances. In this paper, we tested a method based on intrusive measurements on the refrigerant side. The method proposed uses two Coriolis mass flow meters for the measurement of the refrigerant flow rate and of the vapor quality at the indoor heat exchanger outlet. The method is validated by testing an air-to-water heat pump in laboratory conditions and by using the water enthalpy method as a reference. Results confirm that the refrigerant density measurement with a Coriolis flow meter can help to predict the refrigerant vapor quality with satisfactory accuracy if the quality is not too high. The method is also reliable in dynamic conditions (including for defrosting periods). It will then be used as a reference to check the accuracy of different in situ measurement methods for air-to-air heat pumps.

► We propose a refrigerant enthalpy method to measure the heating power of heat pumps.
► A measurement of the refrigerant density is used to determine the refrigerant vapor quality at the condenser exhaust.
► The method is validated both in steady state conditions and in dynamic conditions (including for defrosting phases).
► The periods of time with the biphasic refrigerant phenomenon at the condenser exhaust were observed with a non-negligible frequency.
► The method is fully applicable for air-to-air heat pumps.