空间堆闭式Brayton循环回热器传热-阻力耦合特性  

Heat transfer-resistance coupling characteristics of recuperator in closed Brayton cycles for space reactors

作　　者：马文魁 杨小勇 王捷 MA Wenkui;YANG Xiaoyong;WANG Jie(Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education,Collaborative Innovation Center of Advanced Nuclear Energy Technology,Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学核能与新能源技术研究院,先进核能技术协同创新中心,先进反应堆工程与安全教育部重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2022年第10期1660-1667,共8页Journal of Tsinghua University(Science and Technology)

基　　金：国家原子能机构核能开发项目;中核集团领创项目;国家科技重大专项(ZX069)。

摘　　要：空间堆Brayton循环动力系统具有能量密度高、寿命长、运行稳定等优点,能满足未来大功率航天器的电力需求。回热器通过回收涡轮排气废热减小堆芯吸热量,是提高闭式Brayton循环性能的关键设备。该文基于Reynolds比拟理论,建立回热器传热和压损关联的空间Brayton循环热力学模型,分析了回热度对循环性能和关键参数的影响,并优化得到了循环最佳方案。结果表明:回热器传热和压损存在内在联系,压损随回热度的增大而增大。当回热度较低时,循环电效率随回热度单调增加;当回热度增加至接近1,压损增加导致涡轮膨胀比下降。闭式Brayton循环电效率先增加后减小,存在最佳回热度0.9548和最大循环电效率30.23%。分析了温比、压比、氦氙工质组分等参数对系统最佳回热度的影响机理。以循环电效率和比功为目标,优化得到循环的理论边界,最佳电效率方案电效率为32.92%,最佳比功方案比功为65.78kJ·kg^(-1)。Brayton cycle based space reactors have high energy densities,long lifetimes and stable operations,so they are recommended for future high-powered spacecraft.The recuperator is the key component for improving the closed Brayton cycle efficiency by recovering waste heat from the turbine exhaust to reduce the required reactor power.Reynolds analogy was used to develop a thermodynamic model for the recuperator heat and pressure losses in a space-based Brayton cycle to investigate the influence of the recuperator effectiveness on the cycle electrical efficiency and to optimize the cycle design.The results indicate that the heat transfer and pressure losses are related,with the pressure losses increasing as the recuperator effectiveness increases.When the effectiveness is low,the cycle electrical efficiency increases as the recuperator effectiveness increases.When the recuperator effectiveness increases to close to 1,increased pressure losses reduces the expansion ratio of the turbine,so the cycle electrical efficiency reaches a maximum and then decreases.Therefore,each cycle has a best recuperator effectiveness of 0.9548 that gives the maximum cycle electrical efficiency of 30.23%.This study also analyzed the influence of the temperature ratio,the pressure ratio and the helium-xenon composition on the optimal recuperator effectiveness.This study gives the optimal operation conditions for the best cycle electrical efficiency of 32.92%and the optimal specific work of 65.78 kJ·kg^(-1)for the given space-based closed Brayton cycle.

关 键 词：空间堆 闭式Brayton循环 回热器 最佳回热度 

分 类 号：TL424[核科学技术—核技术及应用]