Development of an improved part-load operation strategy for the recompression semi-closed CO2 cycle

Hongyu Xu, Cheng Xu, Shuo Chen, Tianle Dai, Tuantuan Xin and Yongping Yang

Energy, 2025, vol. 334, issue C

Abstract: The semi-closed CO2 cycle has attracted considerable attention due to the high efficiency and near-zero emissions. However, research on its off-design performance is still insufficient, as the operational flexibility is constrained by the low ramp rate of the air separation unit (ASU), with limited exploration of alternative cycle configurations. In this study, a recompression semi-closed CO2 cycle is introduced to decouple the ASU. Off-design models for the recompression semi-closed CO2 cycle and the reference cycle with the ASU thermal integration are developed in Aspen Plus software to investigate and compare their off-design performance. The results indicate that the recompression system achieves maximum net efficiency under design conditions with a recompression split ratio (SR) of 0.325. Additionally, it exhibits enhanced off-design performance, with net efficiency ranging from 40.0 % to 54.5 %. Furthermore, an improved part-load operation strategy is introduced by adjusting the recompression split ratio (SR), leading to an additional net efficiency increase of 0.3–5.1 percentage points in the 20 %–60 % load range. These findings highlight the benefits of the recompression semi-closed CO2 cycle under varying load conditions and offer valuable insights into enhancing off-design performance through the implementation of a variable SR operation strategy.

Keywords: Off-design performance; Operation strategy; Recompression; Semi-closed CO2 cycle; Split ratio (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:334:y:2025:i:c:s0360544225033882

DOI: 10.1016/j.energy.2025.137746

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