Coupling supercritical carbon dioxide (S-CO₂) Brayton cycle with Gen-IV reactor concepts could bring advantages of high compactness and efficiency. This study aims to design proper simple and recompression S-CO₂ Brayton cycles working as the indirect cooling system for a mediate-temperature lead fast reactor and quantify the Brayton cycle performance with different heat rejection temperatures (from 32°C to 55°C) to investigate its potential use in different scenarios, like arid desert areas or areas with abundant water supply. High-efficiency S-CO₂ Brayton cycle could offset the power conversion efficiency decrease caused by low core outlet temperature (which is 480°C in this study) and high compressor inlet temperature (which varies from 32°C to 55°C in this study). A thermodynamic analysis solver is developed to provide the analysis tool. The solver includes turbomachinery models for compressor and turbine and heat exchanger models for recuperator and precooler. The optimal design of simple Brayton cycle and recompression Brayton cycle for the lead fast reactor under water-cooled and dry-cooled conditions are carried out with consideration of recuperator temperature difference constraints and cycle efficiency. Optimal cycle efficiencies of 40.48% and 35.9% can be achieved for the recompression Brayton cycle and simple Brayton cycle under water-cooled condition. Optimal cycle efficiencies of 34.36% and 32.6% can be achieved for the recompression Brayton cycle and simple Brayton cycle under dry-cooled condition (compressor inlet temperature equals to 55°C). Increasing the dry cooling flow rate will be helpful to decrease the compressor inlet temperature. Every 5°C decrease in the compressor inlet temperature will bring 1.2% cycle efficiency increase for the recompression Brayton cycle and 0.7% cycle efficiency increase for the simple Brayton cycle. Helpful conclusions and advises are proposed for designing the Brayton cycle for mediate-temperature nuclear applications in this paper.

中文翻译：

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具有热力学分析求解器的小型模块化反应堆超临界CO2布雷顿循环设计

Gen-IV反应器概念将超临界二氧化碳（S-CO ₂）布雷顿循环耦合可以带来高紧凑性和效率的优势。这项研究旨在设计适当的简单和再压缩S-CO ₂布雷顿循环，作为中温铅快堆的间接冷却系统，并量化不同排热温度（从32°C到55°C）下的布雷顿循环性能。调查其在不同情况下的潜在用途，例如干旱沙漠地区或水源充足的地区。高效S-CO ₂布雷顿循环可以抵消由低铁心出口温度（本研究中为480°C）和高压缩机入口温度（本研究中从32°C至55°C）引起的功率转换效率下降。开发了热力学分析求解器以提供分析工具。该求解器包括用于压缩机和涡轮机的涡轮机械模型以及用于换热器和预冷器的热交换器模型。考虑到换热器温差约束和循环效率，对铅快反应堆在水冷和干冷条件下的简单布雷顿循环和再压缩布雷顿循环进行了优化设计。在水冷条件下，再压缩布雷顿循环和简单布雷顿循环的最佳循环效率可达到40.48％和35.9％。在干冷条件下（压缩机入口温度等于55°C），再压缩布雷顿循环和简单布雷顿循环的最佳循环效率可达到34.36％和32.6％。增加干冷流量将有助于降低压缩机入口温度。压缩机入口温度每降低5°C，再压缩布雷顿循环的循环效率将提高1.2％，简单布雷顿循环的循环效率将提高0.7％。本文针对中温核应用的布雷顿循环设计提出了有益的结论和建议。增加干冷流量将有助于降低压缩机入口温度。压缩机入口温度每降低5°C，再压缩布雷顿循环的循环效率将提高1.2％，简单布雷顿循环的循环效率将提高0.7％。本文针对中温核应用的布雷顿循环设计提出了有益的结论和建议。增加干冷流量将有助于降低压缩机入口温度。压缩机入口温度每降低5°C，再压缩布雷顿循环的循环效率将提高1.2％，简单布雷顿循环的循环效率将提高0.7％。本文针对中温核应用的布雷顿循环设计提出了有益的结论和建议。