Superstructure design and optimization on closed Brayton cycle system of fluoride-salt-cooled high-temperature advanced reactor

To exploit the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactors (FuSTAR) such as high temperature, inherent safety, compact structure, and modularization, an energy conversion system based on a closed Brayton cycle was adopted, and the superstructure design was optimized to attain the best parameters and configuration. To enhance the convergence rate of a single computation, the simultaneous equation method was employed, while the particle swarm method was utilized to prevent local optimality. Irreversible analysis and sensitivity analysis were performed to evaluate the system's performance. The findings demonstrate that thermal efficiency can be significantly enhanced by incorporating reheating into the system. Furthermore, for air and Ar, the recompression intercooling configuration proved effective in reducing the heat transfer temperature difference and enhancing thermal efficiency. For CO2 and Xe, the incorporation of reheating, recompression, and intercooling significantly improved thermal efficiencies beyond 53%, indicating their immense potential for further development. Introducing reheating into the Xe cycle led to a substantial increase in both thermal efficiency and the area of the temperature-entropy graph. The irreversible analysis revealed that for CO2 and SF6, the predominant loss occurred in the cooler and recuperator. In contrast, for the Xe cycle, all kinds of irreversible losses were evenly distributed across each device. Sensitivity analysis indicated that the thermal efficiency of near-critical fluids was more sensitive to the lowest pressure than that of far-critical fluids. Both the near-critical split ratio and the far-critical minimum pressure had a significant impact on the mass flow rate. The design results of this method can guide the selection of the optimal power cycle system configuration for FuSTAR.