The schematic of the test facility is shown in Figure 3. It is a heat pump system designed for R410A. The indoor unit is located in a closed psychrometric loop, and the air is driven by the blower of the air handling unit. The air flows through the nozzle, which measures the air volume flow rate, and then enters the indoor unit. Within the inlet and outlet of the indoor unit, two 9-thermocouple grids measure the temperatures of the inlet and outlet air. Relative humidity sensors were installed to measure the relative humidity of the inlet and outlet air. The outdoor unit is located inside of an environmental chamber, where temperature and humidity can be controlled. Thermocouples and dew point sensors were installed to measure the air-side inlet and outlet temperatures and dew points, respectively. Pressure transducers and in-stream thermocouples were installed in the vapor compression system to measure the refrigerant-side pressures and temperatures, respectively. Mass flow meters were installed to measure the refrigerant mass flow rates of the injected vapor and the condenser. A watt meter was installed to measure the compressor and outdoor fan motor power consumption. The compressor used in the experimental study is a vapor-injected scroll compressor. It has a constant speed of 3,500 RPM with a displacement of 29.5 cm3 . The system can be operated either with vapor injection or without vapor injection by controlling an injection control valve located in the vapor injection line. The specifications of the outdoor and indoor heat exchangers are shown in Table 3. The heat pump system can be operated for both cooling and heating modes. The uncertainties of instruments and calculated parameters are summarized in Table 4.