Nuclear power system based on open Brayton cycle for Mars base: configuration comparison and performance assessment

Given the high launch costs, efficient and compact power systems are crucial for Mars bases. A novel Mars nuclear power system based on open Brayton cycle (Mars-OBC) is proposed, utilizing Martian air as the working fluid to significantly reduce system mass and mitigate leakage risks. Thermodynamic and mass prediction models for a 1 MWt Mars-OBC were established, and performance assessments and comparisons of different configurations were conducted. The impact of key thermodynamic parameters on system specific mass was investigated to identify pathways for optimizing efficiency and mass. Results indicate that, compared to simple recuperated cycle (SRC), the simple cycle (SC) and intercooled cycle (IC) are viable options for Mars-OBC. Preliminary optimization shows that the SC configuration achieved the lowest specific mass of 15.68 kg∙kW⁻¹ (31 % efficiency, 4473.5 kg total mass). The IC configuration exhibited a specific mass of 17.55 kg∙kW⁻¹ (30.87 % efficiency, 4756.2 kg total mass). Further comparison between the SC configuration with closed Brayton cycle (CBC) concepts reveals Mars-OBC's significant simplification due to radiator absence. Its specific mass is considerably lower at equivalent thermal power, with non-nuclear components reduced to just 21.8 %. Direct Martian air utilization eliminates fluid leakage and replenishment mass inherent in CBCs, warranting further investigation.