Study on inherent mechanism between thermodynamic performance and mass evaluation of MW-class nuclear powered spacecraft

Nuclear powered spacecraft (NPS) with multiple Brayton loops (NPS-MBL) exhibit high efficiency, compact size, low weight, and operational stability, making them promising candidates for future deep space exploration and planetary bases. Optimizing NPS design requires an in-depth understanding of the relationship between thermodynamic performance and mass. In this study, comprehensive models were developed to evaluate the thermodynamic performance and mass of NPS-MBL. The influences of key parameters on thermodynamic performance and mass were analyzed. The results indicated that increasing the turbine inlet temperature and turbomachine efficiency enhanced the thermodynamic performance and reduced the total mass of NPS. The optimal specific mass was achieved by increasing the compressor inlet temperature, recuperator effectiveness, pressure ratio, and helium molar fraction. Additionally, theoretical upper limits for power generation and specific mass of NPS-MBL were obtained. For an NPS with quadruple Brayton loops and a reactor power of 5 MW, schemes maximizing power generation at 1.6 MW with a specific mass of 10.91 t∙MW-1 and minimizing specific mass at 5.52 t∙MW-1 with a power generation of 1.32 MW were identified. This study serves as a valuable reference for NPS design and optimization.