Multi-stage ejector based low-pressure leaking gas recirculation system for supercritical CO2 Brayton cycle

Meihong Yu, Chen Wang, Tang Yu, Le Ma, Xiuting Liu, Houjun Gong, Lei Wang, Minyun Liu, Yanping Huang and Xinli Wang

Energy, 2025, vol. 316, issue C

Abstract: The supercritical carbon dioxide Brayton cycle (SCBC) is an appealing power system for its high compactness and efficiency. The ultra-high rotational speeds of mechanical components and the large pressure difference in turbomachinery lead to the supercritical CO2 (S-CO2) leakage affecting overall efficiency and stability. This study presents a four-stage ejector based leakage gas recovery system to reuse the leaking S-CO2 and enhance the system performance. This work proposes a design methodology for the four-stage ejector and then investigates its operating characteristics under different working conditions through a verified numerical simulation model. The findings indicate that the working conditions of the multi-stage ejector affect the number of ejectors in critical mode and then its entrainment performance. Increasing primary flow pressure improves the pressure lift performance of the multi-stage ejector, while variations in secondary fluid pressure have minimal impact. Besides, the final-stage ejector design is critical for maximizing pressure lift capacity of multi-stage ejectors, while the first-stage design highly influences their entrainment performance. Finally, compared to the compressor-based SCBC and the single-ejector-based SCBC, the proposed system can recycle 5.0 g/s of leaking S-CO2 and achieve a pressure lift of 7.5 MPa with a more compact geometric structure, thereby facilitating the miniaturization of SCBCs.

Keywords: Supercritical carbon dioxide Brayton cycle; Recirculation system for leaking gas; Ejector; Four-stage ejector; Operating characteristics (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:316:y:2025:i:c:s0360544225001628

DOI: 10.1016/j.energy.2025.134520

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