Comparison Analysis and Optimization Research of Open and Closed Air Brayton Cycle

Abstract Microreactors have a significant impact on the strategy of energy safety. Due to the significant advantages of high security, compactness, high thermo-electric conversion efficiency, easy acquirement and supplement on working medium and so on, the air Brayton cycle system can serve as a reliable and dispatchable power conversion system of microreactor mobile nuclear power source in the remote islands or polar regions. Air Brayton cycle configuration adapted to different environments has a broad application prospect, which leads to comparison analysis and optimization work on open and closed air Brayton cycle systems. In the present study, a 5 MW thermal heat pipe microreactor combining a simple recuperated air Brayton cycle energy conversion system is designed for mobile power sources at remote sites. Using a system-component combined design method, the influences of open and closed cycle parameters on the system performance are investigated and compared. On this basis, optimization work is carried out by NSGA-II, in which cycle efficiency and system power density are considered. Finally, a comprehensive design-analysis-optimization strategy is established to adapt to different environmental assumptions. The results indicate that at the same power level, open and closed Brayton cycle systems reveal respective advantages. The closed cycle system shows higher cycle efficiency and system power density than the open cycle system. The open cycle system has more compact structures due to the lack of the cooler and indicates less estimated cost due to mature and advanced techniques of components, which demonstrate its advantages compared to the closed cycle system.