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Load-following operation of supercritical CO2 power cycles under turbine speed control with different shaft configurations

Author

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  • Qin, Tianyang
  • Sun, Yuwei
  • Yan, Xinping
  • Yuan, Chengqing

Abstract

The supercritical CO2 power cycle offers high thermal efficiency and wide load-regulation capabilities, making it a promising technology for thermal power generation. Ensuring stable load-following operation requires an effective control strategy to regulate power output while maintaining key system parameters. This study develops and validates a dynamic model for a recompression supercritical CO2 power cycle based on an existing test bench, incorporating turbine speed control for output regulation. Various turbine and compressor shaft configurations are considered, including split-shaft arrangements, coaxial coupling of the main compressor and turbine, and a parallel two-turbine configuration with coaxial layouts for either the main compressor or recompressor (2-TAC). The results indicate that the 2-TAC configuration achieves the highest part-load thermal efficiency and operational stability while maintaining a compact shaft design, ideal for space-constrained applications such as transportation systems. Turbine speed control improves efficiency and stability compared to bypass and inventory control methods, requiring fewer control valves and reducing leakage points. However, it introduces overheating risks in the high-temperature recuperator, potentially affecting material integrity over prolonged operation. A modified control strategy is proposed to maintain a constant turbine outlet temperature through heat source power regulation, reducing thermal efficiency by 0.1 % and increasing recovery time by 221.2 s at 50 % load. This strategy enables stable operation down to 50 % load. Overall, the findings demonstrate the potential of turbine speed control under the 2-TAC design to enhance load-following performance and efficiency in supercritical CO2 power cycles, particularly for applications with spatial constraints.

Suggested Citation

  • Qin, Tianyang & Sun, Yuwei & Yan, Xinping & Yuan, Chengqing, 2025. "Load-following operation of supercritical CO2 power cycles under turbine speed control with different shaft configurations," Energy, Elsevier, vol. 328(C).
    • Handle: RePEc:eee:energy:v:328:y:2025:i:c:s0360544225021747
    DOI: 10.1016/j.energy.2025.136532
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