The recompression supercritical CO₂ (S-CO₂) Brayton cycle is regarded as one of the most promising energy conversion systems owing to its high efficiency and compactness. Because the recompressor impairs the performance of a system at low loads, the concept of multimode operation by switching the recompressor on or off is proposed to improve the part-load performance. In this study, a dynamic model of the recompression S-CO₂ cycle with reheating is developed, and three control strategies, including turbine throttle valve control, turbo-alternator-compressor (TAC) speed control, and inventory control, are selected to follow the part-load. Subsequently, the action mechanism of the multimode operation and the effects of different control strategies on the part-load performance of the system under multimode operation is investigated and compared. Simulation results indicate that the improved thermal efficiency by switching operation modes is due to improvement in the thermal match inside the high-temperature recuperator and reduced degradation of the recompressor. Moreover, switching the system to Mode 2 by switching off the recompressor at 20% load under TAC speed control, turbine throttle valve control, and inventory control can improve thermal efficiency by 1%, 3.5%, and 5.4%, respectively. This result can serve as a guideline for the efficient operation of the recompression cycle under part-load.

再压缩超临界CO ₂ (S-CO ₂ )布雷顿循环由于其高效率和紧凑性被认为是最有前途的能量转换系统之一。由于再压缩机会影响系统在低负载时的性能，因此提出了通过打开或关闭再压缩机来实现多模式运行的概念，以提高部分负载性能。_{在本研究中，再压缩 S-CO 2}的动力学模型开发了带再热的循环，选择了涡轮节流阀控制、涡轮-交流发电机-压缩机（TAC）速度控制和库存控制三种控制策略来跟踪部分负荷。随后，研究并比较了多模式运行的作用机制以及不同控制策略对系统在多模式运行下的部分负荷性能的影响。仿真结果表明，通过切换运行模式提高热效率是由于改善了高温同流换热器内部的热匹配并减少了再压缩机的退化。此外，在 TAC 速度控制、涡轮节流阀控制和库存控制下，通过在 20% 负载下关闭再压缩机将系统切换到模式 2 可以将热效率提高 1%、3.5%、和 5.4%。该结果可以作为在部分负荷下有效运行再压缩循环的指南。