Abstract Supercritical CO2 recompression Brayton cycle (S-CO2 RBC) can be used as waste heat recovery system in a ship because of the advantages of high efficiency, compact size and lower cost. This paper proposes a modified S-CO2 RBC system, namely the dual turbine-alternator-compressor (TAC) S-CO2 RBC system, which to be used to recover the waste heat from the main engine exhaust gas of an ocean-going 9000 TEU container ship. Mathematical and simulation models for the modified system are established to investigate the improvement in the performance. Parametric study is conducted to analyze the effects of key thermodynamic parameters on the system performance. The Imperialist Competitive Algorithm - based multi-objective optimization is carried out to get the modified system’s optimal operating parameters, aiming to maximize the system net power output, energetic efficiency and exergetic efficiency as well as to minimize the heat exchanger area per unit power and the levelized cost of energy. The results show that the performance of the modified system is strengthened significantly, whose highest net power output, energetic efficiency and exergy efficiency are 452.2 kW, 24.53% and 41.47%, approximately 26.58%, 16.67% and 16.90% higher than that of the S-CO2 RBC system. Compared with the S-CO2 RBC system, the modified system is more compact because its heat exchanger area per unit power decreased by 44.08%. The modified system can contribute to decreasing the ship auxiliary engine fuel consumption and the Energy Efficiency Design Index by about 1.01% and 1.02%, and improving the thermal efficiency of the ship main engine system by 3.23%. The results of this study can provide theoretical support for the application of the dual TAC S-CO2 RBC waste heat recover system on ships.

中文翻译：

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9000TEU远洋集装箱船S-CO2布雷顿循环余热回收系统热经济分析及多目标优化

摘要 超临界二氧化碳再压缩布雷顿循环（S-CO2 RBC）具有效率高、体积小、成本低等优点，可作为船舶余热回收系统。本文提出了一种改进的 S-CO2 RBC 系统，即双涡轮 - 交流发电机 - 压缩机（TAC）S-CO2 RBC 系统，用于回收远洋 9000 TEU 主机废气的余热。集装箱船。建立了改进系统的数学和仿真模型，以研究性能的改进。进行参数研究以分析关键热力学参数对系统性能的影响。进行基于帝国主义竞争算法的多目标优化，得到修改后系统的最优运行参数，旨在最大限度地提高系统净功率输出、能源效率和火用效率，以及最小化单位功率的换热面积和能源的平准化成本。结果表明，改进后的系统性能得到显着增强，其最高净功率输出、能量效率和火用效率分别为452.2 kW、24.53%和41.47%，比S提高了约26.58%、16.67%和16.90%。 -CO2 红细胞系统。与S-CO2 RBC系统相比，改进后的系统更加紧凑，单位功率换热面积减少了44.08%。改造后的系统有助于船舶辅机油耗和能效设计指标降低约1.01%和1.02%，船舶主机系统热效率提高3.23%。