Figure 1.
The photo of the organic Rankine cycle (ORC) test bench (a), the system schematic (b), and the temperature-entropy (T-S) diagram for a given operating condition during the tests (c).
Figure 1.
The photo of the organic Rankine cycle (ORC) test bench (a), the system schematic (b), and the temperature-entropy (T-S) diagram for a given operating condition during the tests (c).
Figure 2.
Range of the parameters constituting the experimental database: expander suction pressure vs flow rate (a), expander suction temperature vs flow rate (b), hot fluid inlet temperature to the evaporator vs flow rate (c), expander pressure ratio vs flow rate (d), expander pressure ratio vs expander shaft speed (e), hot fluid flow rate vs refrigerant flow rate in the evaporator (f), superheating degree vs refrigerant flow rate in the evaporator (h), and subcooling degree vs refrigerant flow rate in the condenser (i).
Figure 2.
Range of the parameters constituting the experimental database: expander suction pressure vs flow rate (a), expander suction temperature vs flow rate (b), hot fluid inlet temperature to the evaporator vs flow rate (c), expander pressure ratio vs flow rate (d), expander pressure ratio vs expander shaft speed (e), hot fluid flow rate vs refrigerant flow rate in the evaporator (f), superheating degree vs refrigerant flow rate in the evaporator (h), and subcooling degree vs refrigerant flow rate in the condenser (i).
Figure 3.
Reported pump maximum efficiency and hydraulic power in the literature up to 2017 based on data from [
11].
Figure 3.
Reported pump maximum efficiency and hydraulic power in the literature up to 2017 based on data from [
11].
Figure 4.
The refrigerant pump isentropic efficiency with pressure ratio (PR) (left), and with flow rate (right).
Figure 4.
The refrigerant pump isentropic efficiency with pressure ratio (PR) (left), and with flow rate (right).
Figure 5.
Refrigerant pump volumetric efficiency with the flow rate.
Figure 5.
Refrigerant pump volumetric efficiency with the flow rate.
Figure 6.
Scroll expander isentropic efficiency with pressure ratio (PR) (left), and with shaft speed (right).
Figure 6.
Scroll expander isentropic efficiency with pressure ratio (PR) (left), and with shaft speed (right).
Figure 7.
Scroll expander shaft power with flow rate.
Figure 7.
Scroll expander shaft power with flow rate.
Figure 8.
Scroll expander filling factor with shaft speed (left), and with pressure ratio (PR) (right).
Figure 8.
Scroll expander filling factor with shaft speed (left), and with pressure ratio (PR) (right).
Figure 9.
ORC system net electric efficiency (left), and net electric power with flow rate (right).
Figure 9.
ORC system net electric efficiency (left), and net electric power with flow rate (right).
Figure 10.
Pump back-work ratio (BWR) with expander produced electric power (left), and ORC system gross efficiency with flow rate (right).
Figure 10.
Pump back-work ratio (BWR) with expander produced electric power (left), and ORC system gross efficiency with flow rate (right).
Figure 11.
Volumetric efficiency of the oil gear pump for a given pump speed and pressure for different oil temperatures (20–150 °C).
Figure 11.
Volumetric efficiency of the oil gear pump for a given pump speed and pressure for different oil temperatures (20–150 °C).
Figure 12.
Volumetric efficiency of the oil pump for all experimental data points.
Figure 12.
Volumetric efficiency of the oil pump for all experimental data points.
Figure 13.
Measured and calculated pump volumetric efficiency (left) and pump mass flow rate (right).
Figure 13.
Measured and calculated pump volumetric efficiency (left) and pump mass flow rate (right).
Figure 14.
Measured and calculated pump isentropic efficiency (left) and discharge temperatures (right).
Figure 14.
Measured and calculated pump isentropic efficiency (left) and discharge temperatures (right).
Figure 15.
Measured and calculated pump electric power (left)and electromechanical efficiency (right).
Figure 15.
Measured and calculated pump electric power (left)and electromechanical efficiency (right).
Figure 16.
Calculated and measured pressure drop of the condenser (left) and pressure drop resolution in different heat transfer zones in the condenser (right).
Figure 16.
Calculated and measured pressure drop of the condenser (left) and pressure drop resolution in different heat transfer zones in the condenser (right).
Figure 17.
The calculated and measured pressure drop of the evaporator (left) and pressure resolution in different heat transfer zones in the evaporator (right).
Figure 17.
The calculated and measured pressure drop of the evaporator (left) and pressure resolution in different heat transfer zones in the evaporator (right).
Figure 18.
The possible distribution of heat transfer zones in a heat exchanger when both streams change the phase.
Figure 18.
The possible distribution of heat transfer zones in a heat exchanger when both streams change the phase.
Figure 19.
Results of the condenser hydrothermal model vs. experimental data: refrigerant discharge temperature (top-left), water discharge temperature (top-right), thermal load in the refrigerant side (bottom-left), and temperature profile for one of the experimental points (bottom-right).
Figure 19.
Results of the condenser hydrothermal model vs. experimental data: refrigerant discharge temperature (top-left), water discharge temperature (top-right), thermal load in the refrigerant side (bottom-left), and temperature profile for one of the experimental points (bottom-right).
Figure 20.
Results of the evaporator hydrothermal model vs. experimental data: refrigerant discharge temperature (top-left), diathermic oil discharge temperature (top-right), thermal load in the refrigerant side (bottom-left), and temperature profile for one of the experimental points (bottom-right).
Figure 20.
Results of the evaporator hydrothermal model vs. experimental data: refrigerant discharge temperature (top-left), diathermic oil discharge temperature (top-right), thermal load in the refrigerant side (bottom-left), and temperature profile for one of the experimental points (bottom-right).
Figure 21.
Expander shaft power (left) and isentropic efficiency (right) with expander pressure ratio (PR) and shaft speed (Tsu,exp = 65°C, Psu,exp = 15 bar, Tamb = 15°C).
Figure 21.
Expander shaft power (left) and isentropic efficiency (right) with expander pressure ratio (PR) and shaft speed (Tsu,exp = 65°C, Psu,exp = 15 bar, Tamb = 15°C).
Figure 22.
Inputs and outputs of the ORC object-oriented model.
Figure 22.
Inputs and outputs of the ORC object-oriented model.
Figure 23.
Flow chart of the object-oriented solver of the ORC system.
Figure 23.
Flow chart of the object-oriented solver of the ORC system.
Figure 24.
Net electric work (left) and net electric efficiency (right) maps of the ORC system with the heat source temperature and the expander shaft speed (Np,HF = 1400 rpm, SH = 5 K, SC = 5 K, Tin,CF = 15°C, Tamb = 15°C).
Figure 24.
Net electric work (left) and net electric efficiency (right) maps of the ORC system with the heat source temperature and the expander shaft speed (Np,HF = 1400 rpm, SH = 5 K, SC = 5 K, Tin,CF = 15°C, Tamb = 15°C).
Figure 25.
The expander shaft work with the expander shaft speed colored according to the cold fluid inlet temperature in the condenser.
Figure 25.
The expander shaft work with the expander shaft speed colored according to the cold fluid inlet temperature in the condenser.
Table 1.
Characteristics of main components of the ORC unit.
Table 1.
Characteristics of main components of the ORC unit.
| Density (at 20 °C) [kg/L] | 0.8851 |
---|
Heat source medium (Texatherm HT22) | Operating temperature range [°C] | −45–290 |
| Kinematic viscosity [cSt] | 22 at 40 °C 3.75 at 100 °C |
Electrical heaters (5 numbers) | Resistor power [kWel] | 4.5 |
Diathermic oil pump (gear pump) | Maximum flow rate [lpm] | 23.5 |
Maximum motor speed [rpm] | 1400 |
Evaporator/condenser | Number of plates | 50/60 |
Dimension (L*W) [mm2] | 304*124 |
Heat transfer area of one plate [m2] | 0.03 |
Space between two plates [mm] | 2.4 |
Organic fluid pump (piston pump) | Maximum flow rate [lpm] | 13.26 |
Maximum motor speed [rpm] | 1430 |
Nominal efficiency [%] | 85 |
Scroll compressor | Model | Sanden TRS090 |
Nominal fluid | R134a |
Swept volume [cc/rev] | 85.7 |
BVR [-] | 1.9 |
Oil charge (PAG) [cc] | 130 + 20 |
Maximum continuous speed [rpm] | 10,000 |
Electric generator (3-phase brushless servomotor) | Nominal speed [rpm] | 1500 |
Nominal power [kW] | 1.59 |
Nominal Voltage [V] | 334 |
Maximum torque [N.m] | 10 |
Liquid receiver | Internal Volume [l] | 3 |
Maximum pressure [bar] | 22.5 |
Table 2.
Characteristics of the sensors of the ORC system.
Table 2.
Characteristics of the sensors of the ORC system.
Parameter | Model | Resolution | Accuracy | Output Signal |
---|
Temperature | PT100 resistance | 0.1 °C | (0.15 + 0.002∗T) [°C] | 4–20 mA |
Pressure | PMC131(A11E1A2T & A11E1A2R) | 2 mbar | <0.5% of sensor upper limit | 4–20 mA |
Flow rate | Gear flow meter, Cobold, DOM-S15HR31 | 702 pulse/l | 1% of the read value | 4–20 mA |
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 |
Table 3.
Range of working conditions during the experimental tests campaign.
Table 3.
Range of working conditions during the experimental tests campaign.
[kg/h] | | | | | | SH [K] | SC [K] |
---|
195–176 | 753–1416 | 11.2–15.4 | 4.7–7.1 | 119.7–150.7 | 8.7–19.6 | 2–24 | 3.7–7.9 |