Where _W is the total power consumption of the heat pump system. For the refrigerant side, the capacity is calculated in Equation (3):
Where m_ ref is the refrigerant mass flow rate; href(out) is the refrigerant enthalpy at the indoor heat exchanger outlet, and href(in) is the refrigerant enthalpy at the indoor heat exchanger inlet. The system cooling and heating COP is defined in Equation (4):
Energy balance between air side and refrigerant side is calculated in Equation (5):