## 2 Experimental Setup and Procedure
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Density (at 20 \({}^{\circ}\)C) [kg/L]** & **0.8851** \\ \hline Heat source medium & Operating temperature range [\({}^{\circ}\)C] & \(-\)45–290 \\ (Texatherm HT22) & Kinematic viscosity [cSt] & 22 at 40 \({}^{\circ}\)C \\  & & 3.75 at 100 \({}^{\circ}\)C \\ \hline Electrical heaters (5 numbers) & Resistor power [kWel] & 4.5 \\ \hline Diathermic oil pump & Maximum flow rate [lpm] & 23.5 \\ (gear pump) & Maximum motor speed [rpm] & 1400 \\ \hline  & Number of plates & 50/60 \\ Evaporator/condenser & Dimension (L\({}^{\prime\prime}\)W) [mm\({}^{2}\)] & 304*124 \\  & Heat transfer area of one plate [m\({}^{2}\)] & 0.03 \\  & Space between two plates [mm] & 2.4 \\ \hline Organic fluid pump & Maximum flow rate [lpm] & 13.26 \\ (piston pump) & Maximum motor speed [rpm] & 1430 \\  & Nominal efficiency [\%] & 85 \\ \hline  & Model & Sanden TRS090 \\  & Nominal fluid & R134a \\ Scroll compressor & Swept volume [cc/rev] & 85.7 \\  & BVR [-] & 1.9 \\  & Oil charge (PAG) [cc] & 130 + 20 \\  & Maximum continuous speed [rpm] & 10,000 \\ \hline  & Nominal speed [rpm] & 1500 \\ Electric generator & Nominal power [kW] & 1.59 \\ (3-phase brushless servomotor) & Nominal Voltage [V] & 334 \\  & Maximum torque [N.m] & 10 \\ \hline  & Internal Volume [L] & 3 \\ Liquid receiver & Maximum pressure [bar] & 22.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of main components of the ORC unit. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Model** & **Resolution** & **Accuracy** & **Output Signal** \\ \hline Temperature & PT100 resistance & 0.1 \({}^{\circ}\)C & \(\pm\)(0.15 + 0.002*T) [\({}^{\circ}\)C] & 4–20 mA \\ Pressure & PMC131(A11E1A2T) & 2 mbar & \(<\)0.5\% of sensor \\  & \& A11E1A2R) & upper limit & 4–20 mA \\  & \& Gear flow meter, & \\ Flow rate & Cobold, & 702 pulse/L & 1\% of the read value & 4–20 mA \\  & DOM-S15 HR31 & & \\ Torque & DataFlex 16/30 & 360 pulse/rev & 0.1\% of the read value & \(-\)10 to +10 V \\ Shaft speed & DataFlex 16/30 & 360 pulse/rev & 1 deg. & 0–10 V \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics of the sensors of the ORC system. * The scroll expander always works in off-design conditions compared to the typical shaft speeds commonly reported in the literature due to the limited rotational speed of the electric generator. * To better illuminate the experimental constraints, the following aspects are noteworthy too:
* The maximum pressure was limited due to the pressure sensors that can measure up to 16 bar. The scroll expander nominal working pressure was around 14 bar and could not be extended much;
* Two pressure sensors were installed on the liquid receiver body to measure the liquid level. Their maximum threshold was 6 bar;
* The maximum thermal power was limited to around 22.5 kW using five electric heaters. However, the experimental data showed that around 20% of the available thermal power is wasted during the heat transfer from the resistors to the diathermic oil;
* The maximum refrigerant flow rate was limited due to the maximum pressure of the cycle;
* The maximum scroll expander speed was limited firstly due to the electric generator that can work at a maximum of 1500 rpm. It was also limited by the refrigerant flow rate delivered to the expander, which in turn was limited due to the maximum pressure of the system as described in the point above. * The water flow rate was fixed because the chiller turns off if the flow rate is reduced. Therefore, the subcooling degree could not be adjusted at the condenser outlet using the water flow rate; instead, it was affected by the initial mass charge of the system.