Heat transfer-resistance coupling characteristics of recuperator in closed Brayton cycles for space reactors
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
Abstract：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 0.954 8 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.
马文魁, 杨小勇, 王捷. 空间堆闭式Brayton循环回热器传热-阻力耦合特性[J]. 清华大学学报（自然科学版）, 2022, 62(10): 1660-1667.
MA Wenkui, YANG Xiaoyong, WANG Jie. Heat transfer-resistance coupling characteristics of recuperator in closed Brayton cycles for space reactors. Journal of Tsinghua University(Science and Technology), 2022, 62(10): 1660-1667.
[1] ZHANG R, GUO K L, WANG C L, et al. Thermal-hydraulic analysis of gas-cooled space nuclear reactor power system with closed Brayton cycle[J]. International Journal of Energy Research, 2021, 45(8):11851-11867. [2] DAVIS J E. Design and fabrication of the Brayton rotating unit[R]. Washington DC, USA:NASA, 1972. [3] DOBLER F X. Analysis, design, fabrication and testing of the mini-Brayton rotating unit (MINI-BRU). Volume 2:Figures and drawings[R]. Washington DC, USA:NASA, 1978. [4] WAGANER L M, DRIEMEYER D E, LEE V D. Inertial fusion energy reactor design studies:Prometheus-L, Prometheus-H[R]. Hyannis, USA:McDonnell Douglas Corporation, 1992. [5] EL-GENK M S, TOURNIER J M. On the use of noble gases and binary mixtures as reactor coolants and CBC working fluids[J]. Energy Conversion and Management, 2008, 49(7):1882-1891. [6] 张秀.空间核能系统布雷顿循环性能评估及优化[D].哈尔滨:哈尔滨工业大学, 2019. ZHANG X. Performance analysis and optimization of space nuclear Brayton cycle system[D]. Harbin:Harbin Institute of Technology, 2019.(in Chinese) [7] LI Z, YANG X Y, WANG J, et al. Thermodynamic optimization and analysis of Brayton-cycle system for space power reactor[J]. Atomic Energy Science and Technology, 2017, 51(7):1173-1180. [8] 李智,杨小勇,王捷,等.空间反应堆Brayton循环的热力学特性[J].清华大学学报(自然科学版), 2017, 57(5):537-543, 549. LI Z, YANG X Y, WANG J, et al. Thermodynamic characteristics of Brayton cycle of space reactor[J]. Journal of Tsinghua University (Natural Science Edition), 2017, 57(5):537-543, 549.(in Chinese) [9] MA W K, YE P, ZHAO G, et al. Effect of cooling schemes on performance of MW-class space nuclear closed Brayton cycle[J]. Annals of Nuclear Energy, 2021, 162:108485. [10] EL-GENK M S, TOURNIER J M. Noble gas binary mixtures for gas-cooled reactor power plants[J]. Nuclear Engineering and Design, 2008, 238(6):1353-1372. [11] 李智.空间反应堆动态能量转换系统特性研究[D].北京:清华大学, 2017. LI Z. Research on the dynamic energy conversion system for space nuclear reactor[D]. Beijing:Tsinghua University, 2017.(in Chinese) [12] VON ARX A V, CEYHAN I. Laminar heat transfer for low Prandtl number gases[J]. AIP Conference Proceedings, 1991, 217(2):719-722. [13] 钱颂文.换热器设计手册[M].北京:化学工业出版社, 2002. QIAN S W. Heat exchanger design manual[M]. Beijing:Chemical Industry Press, 2002.(in Chinese) [14] GALLO B M, EL-GENK M S. Brayton rotating units for space reactor power systems[J]. Energy Conversion and Management, 2009, 50(9):2210-2232. [15] QU X H, YANG X Y, WANG J. A study on different thermodynamic cycle schemes coupled with a high temperature gas-cooled reactor[J]. Annals of Nuclear Energy, 2017, 106:185-194. [16] EL-GENK M S, GALLO B M. High-power Brayton rotating unit for reactor and solar dynamic power systems[J]. Journal of Propulsion and Power, 2010, 26(1):167-176. [17] EL-GENK M S, TOURNIER J M. On the use of noble gases and binary mixtures as reactor coolants and CBC working fluids[J]. Energy Conversion and Management, 2008, 49(7):1882-1891. [18] TOURNIER J M P, EL-GENK M S. Properties of noble gases and binary mixtures for closed Brayton cycle applications[J]. Energy Conversion and Management, 2008, 49(3):469-492. [19] TOURNIER J M, EL-GENK M, GALLO B. Best estimates of binary gas mixtures properties for closed Brayton cycle space applications[C]//4th International Energy Conversion Engineering Conference and Exhibit (IECEC). San Diego, USA:AIAA, 2006:4154.
2022, Vol. 62 
