## 3 Experimental Setup and Data Processing
### Data Processing  
The compressor was tested using an R290 refrigerant according to the conditions listed in Table 1. The compressor's suction and discharge temperature, pressure, and mass flow rate were tested by adjusting the compressor speed. During the experiment, the calorimeter maintained a dual-sided thermal balance, meaning the error of the cooling capacity on the refrigerant side and the electric heating power on the secondary refrigerant side was kept within 5%, indicating that the test setup met the requirements for thermal loss. Figure 2 is the pressure-enthalpy diagram of the test system. Points 1 to 2 represent the actual compression process, point 2s represents the ideal isentropic compression process, point 3 is the state at the outlet of the condenser, and point 3s is the state at the outlet of the subcooler. As shown in the figure, the enthalpy value remains constant from point 3s to point 4, so the process from point 3s to point 1 is considered as a whole. The evaporator outlet state at point 1 consists of the evaporated gaseous refrigerant, lubricating oil, and liquid refrigerant dissolved in the lubricating oil. The amount of liquid refrigerant dissolved in the lubricating oil can be determined by consulting the solubility characteristic curve:  
Therefore, the flow expression at the evaporator outlet state at point 1 is as follows:  
\[m_{mix}=m_{1,rG}+m_{o}+m_{1,rL} \tag{10}\]  
where \(m_{1,rG}\) is the mass flow rate of vapor refrigerant at the outlet of the evaporator (compressor suction), kg/s; \(m_{1,rL}\) is the mass flow rate of liquid refrigerant dissolved in the oil at the outlet of the evaporator (compressor suction), kg/s. The formula for calculating the nominal cooling capacity of the system is as follows:  
\[Q=m_{1,rG}\times(h_{1}-h_{3,sub}) \tag{11}\]  
where \(Q\) is the nominal cooling capacity, kw; \(h_{3,sub}\) is the enthalpy at the outlet of the subcooler, kJ/kg. Due to the superheat at the outlet of the evaporator, the temperature and enthalpy of the lubricating oil at the inlet of the evaporator and inlet of the expansion valve differ, and the enthalpy of the liquid refrigerant dissolved in the lubricating oil also changes. Therefore, the heat exchange in the evaporator includes the heat released by the lubricating oil and the liquid refrigerant. The heat balance is achieved using electric heating in the calorimeter; thus, the heat balance equation is as follows: \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multirow{2}{*}{\begin{tabular}{c} **Base Circle** \\ **Radius/mm** \\ \end{tabular} } & \begin{tabular}{c} **Involute** \\ **Starting** \\ **Angle/(\({}^{\circ}\))** \\ \end{tabular} & \begin{tabular}{c} **Maximum Angle of** \\ **Intermediate Scroll** \\ **Profile/(\({}^{\circ}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Suction** \\ **Volume/cm\({}^{3}\)** \\ \end{tabular} &
\begin{tabular}{c} **Scroll Wrap** \\ **Height/mm** \\ \end{tabular} \\ \hline Values & 2.8 & 40.5 & 810 & 35 & 22.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameters of EVS36 scroll compressor. Figure 2: Thermodynamic cycle. \[Q_{e}=W_{e}+m_{o}\times(h_{in,oil}-h_{out,oil})+m_{1,rL}\times(h_{in,rL}-h_{out,rL}) \tag{12}\]  
where \(h_{out,oil}\), \(h_{in,oil}\) are the enthalpies of the lubricating oil at the outlet of the evaporator and before the expansion valve, respectively, kJ/kg; \(h_{out,rL}\), \(h_{in,rL}\) are the enthalpies of the liquid refrigerant dissolved in the lubricating oil at the outlet of the evaporator and before the expansion valve, respectively, kJ/kg; \(W_{e}\) is the electric power measured by the calorimeter, representing the actual cooling capacity of the system, kW.