Conceptualization, Y.Z.; methodology, Y.Z.; software, Y.Z.; validation, Y.Z.; formal analysis, Y.Z.; investigation, Y.Z.; resources, X.G.; data curation, X.G.; writing—original draft preparation, Y.Z.; writing—review and editing, S.L., C.G.,Y.G. and Z.L.; visualization, Y.Z.; supervision, Y.J. and C.G.; project administration, Y.G.; funding acquisition, S.L. All authors have read and agreed to the published version of the manuscript.

Figure 1. The simple reheat cycle.

Figure 1. The simple reheat cycle.

Figure 2. Distribution of the semi-open impeller. (a) Beta distribution, (b) Thickness distribution.

Figure 2. Distribution of the semi-open impeller. (a) Beta distribution, (b) Thickness distribution.

Figure 3. Performance curve of the single-stage compressor (@ 40,000 RPM).

Figure 3. Performance curve of the single-stage compressor (@ 40,000 RPM).

Figure 4. Schematic layout of the single-stage compressor.

Figure 4. Schematic layout of the single-stage compressor.

Figure 5. Schematic figure of the rotor (left) and impeller (right).

Figure 5. Schematic figure of the rotor (left) and impeller (right).

Figure 6. General experimental platform for the MWe sCO2 compressor.

Figure 6. General experimental platform for the MWe sCO2 compressor.

Figure 7. 3-D graphic model of the general experimental platform.

Figure 7. 3-D graphic model of the general experimental platform.

Figure 8. Circle diagram of the general experimental platform.

Figure 8. Circle diagram of the general experimental platform.

Figure 9. Original experimental data and historical curves.

Figure 9. Original experimental data and historical curves.

Figure 10. Pressure ratio performance curve (@ 31,000 ± 1000 RPM).

Figure 10. Pressure ratio performance curve (@ 31,000 ± 1000 RPM).

Figure 11. Isentropic efficiency performance curve (@ 31,000 ± 1000 RPM).

Figure 11. Isentropic efficiency performance curve (@ 31,000 ± 1000 RPM).

Figure 12. The compressor inlet conditions in the test (@ 31,000 ± 1000 RPM).

Figure 12. The compressor inlet conditions in the test (@ 31,000 ± 1000 RPM).

Figure 13. Dimensionless isentropic head coefficient performance curve (@ 31,000 ± 1000 RPM).

Figure 13. Dimensionless isentropic head coefficient performance curve (@ 31,000 ± 1000 RPM).

Figure 14. Dimensionless isentropic efficiency performance curve (@ 31,000 ± 1000 RPM).

Figure 14. Dimensionless isentropic efficiency performance curve (@ 31,000 ± 1000 RPM).

Figure 15. Comparison of dimensionless isentropic head coefficient performance curve.

Figure 15. Comparison of dimensionless isentropic head coefficient performance curve.

Figure 16. Comparison of dimensionless isentropic efficiency performance curve.

Figure 16. Comparison of dimensionless isentropic efficiency performance curve.

Figure 17. The condensation acceleration velocity of inlet condition (@ 31,000 ± 1000 RPM).

Figure 17. The condensation acceleration velocity of inlet condition (@ 31,000 ± 1000 RPM).

Figure 18. Dryness distribution of test point near the choke boundary and surge boundary.

Figure 18. Dryness distribution of test point near the choke boundary and surge boundary.

Figure 19. Curve of density with change of outlet pressure and inlet temperature.

Figure 19. Curve of density with change of outlet pressure and inlet temperature.

Figure 20. The impeller of single-stage compressor after tests.

Figure 20. The impeller of single-stage compressor after tests.

Table 1. The main parameters of MWe sCO2 power cycle.

Table 1. The main parameters of MWe sCO2 power cycle.

ParameterValueBoiler thermal power>5 MWthCycle efficiency>21%Turbine inlet pressure20 MPaTurbine inlet temperature550 °CCompressor inlet pressure8 MPaCompressor inlet temperature35 °C

Table 2. Main design parameters of the single-stage centrifugal compressor.

Table 2. Main design parameters of the single-stage centrifugal compressor.

Inlet
PressureInlet
TemperatureMass Flow RatePressure RatioPowerIsentropic Efficiency8 MPa35 °C16.3 kg/s2.5~500 kW>80%

Table 3. Main structural parameters of the semi-open impeller.

Table 3. Main structural parameters of the semi-open impeller.

ParameterValueParameterValueHub radius/mm10 mmBlade angle (leading-edge)60°/54°/48°Impler radius/mm48 mmBlade angle (training-edge)55°Blade number15Blade height (leading-edge)7.5 mmTip clearance0.25 mmBlade height (training-edge)3.5 mmBlade inclination angle60°Thickness (leading-edge)0.3–0.6 mm

Table 4. Main performance of experimental platform for MWe sCO2 compressor.

Table 4. Main performance of experimental platform for MWe sCO2 compressor.

Performance IndexTest CapabilityExperimental speed0~40,000RPMExperimental mass flow0~25kg/sExperimental power0~800kWCompressor inlet pressure0~10MPaCompressor outlet pressure0~22MPaCompressor inlet temperature0~50°CCompressor outlet temperature0~100°C

Table 5. The parameters of temperature and pressure sensor.

Table 5. The parameters of temperature and pressure sensor.

RangeUncertaintyTypeInlet pressure0–10 MPa<±0.075% FSMonocrystalline SiliconOutlet pressure0–25 MPa<±0.075% FSMonocrystalline SiliconInlet temperature0–50 °C<±0.15 °CPT100oulet temperature0–100 °C<±0.15 °CPT100

Table 6. The parameters of Coriolis force mass flowmeter.

Table 6. The parameters of Coriolis force mass flowmeter.

PositionMass Flow
RangeDensity
RangeMass Flow UncertaintyDensity
Uncertainty-kg/sg/cm3%FSg/cm3Upstream2.5~25 400~1000<±0.2<±0.002

Table 7. Dimensionless experimental performance parameters of compressor.

Table 7. Dimensionless experimental performance parameters of compressor.

Dimensionless ParametersFormulaM*M/MrefN*N/NrefT01*(T01-273.13)/(Tref -273.13)T02*(T02-273.13)/(Tref -273.13)P01*P01/PrefP02*P02/Pref

Table 8. The tip clearance of the experimental impeller.

Table 8. The tip clearance of the experimental impeller.

DesignLeading Edge (Exp)Training Edge (Exp)Tip clearance0.25 mm0.43 mm0.45 mm