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.
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