Highly Efficient Recuperated Brayton Convertor for Lunar Power Applications: Cycle and Conceptual Turbomachinery Design

Abstract This paper focuses on the conceptual design of an Advanced Closed Brayton Convertor (ACBC) with high temperatures for efficient power generation in space using Helium-Xenon (He-Xe) mixture as the working fluid. As we aim to return to the Moon for sustained exploration and prepare for human presence on Mars, there is a need for a stable and scalable supply of electrical power. While nuclear fission power addresses the limitations of photovoltaics, fuel cells, and radioisotope thermoelectric generators by providing a stable, efficient, and power-dense energy source, there is an eminent need to develop efficient thermoelectric Brayton power convertors. The current study intends to advance the state of the art of Brayton converters by targeting a high turbine inlet temperature of 1427°C, a power output of 25 KWe at a specific power lower than 10 kg/kWe, an exergy efficiency surpassing 35%, and a maintenance-free service life of at least 10 years. Based on these system level requirements, optimal cycle operating conditions were identified which informed the conceptual design of the turbomachine, alternator, heat exchangers, and piping. The proposed ACBC design leverages several novel technologies to achieve its aggressive performance targets, including advanced actively cooled turbine blades, high-temperature materials, and additive manufacturing of superalloys. This work lays the foundation for future advanced power generation systems which would enable exploration of the Moon, Mars, and deep space.