Performance Analysis of Closed Brayton Cycle System for Small Modular Reactor

Small modular reactors have potential applications in remote or underdeveloped areas for their compact configurations, low maintenance requirements, flexible deployments, and long lifetimes, etc. A small high temperature gas cooled reactor coupled with closed Brayton cycle is presented in this paper. The modular reactor has inherent safety and closed Brayton cycle has high energy conversion efficiency and compact configuration, they can even be integrated into a mobile power plant. A thermodynamic model is established to analyze the effect of parameters, like pressure ratio and ambient temperature, on optimization of design and the system’s performance. The results show that in design condition, temperature ratio, which is effected by ambient temperature and cooling method, is a key parameter. High temperature ratio leads to high cycle efficiency. Compression ratio and effectiveness of recuperator also influence cycle’s efficiency and reactor inlet temperature. As compression ratio increasing, efficiency would decrease after reaching a maximum. In operating condition, changes of ambient temperature would not only affect the temperature ratio, but also cause a deviation of compressor and turbine from their design points, which would lead to a further effect on compression ratio and efficiency. A comparison is made between the operating condition and the design condition to show the effect of temperature ratio variation on compressor, turbine and cycle’s efficiency. It will be helpful to evaluate the performance of small modular reactor in different areas and seasons. The results will be helpful to understand and design the small modular reactor.