Numerical investigation of lattice structured samplers for thermal extraction of icy lunar regolith: Heat and mass transfer analysis

The extraction of water ice from lunar permanently shadowed regions(PSRs) is a cornerstone of in situ resource utilization (ISRU) for sustainable lunar exploration. However, the extremely low thermal conductivity of lunar regolith poses a significant challenge to efficient thermal extraction. In this study, a comprehensive numerical model coupling heat and mass transfer was established. The model took into account the formation and morphology of icy lunar regolith (ILR) to investigate the sublimation and transport processes within it. To enhance temperature uniformity and water extraction efficiency, four innovative lattice structure samplers were proposed and compared to a cavity sampler. Results demonstrated that the hexagonal lattice structure excelled in both sampling performance and extraction efficiency. Based on the hexagonal sampler, the effects of input power, initial water content, and ice particle radius within ILR were analyzed. A critical finding was that while increasing input power boosted the initial extraction rate, it did not proportionally reduce the total extraction time. The research also revealed that there was an optimal input power value under different conditions. With higher initial water content, the temperature standard deviation decreases, and the additional extraction time increases linearly. The radius of ice particles within the ILR affects the temperature standard deviation; as the radius increases, the deviation rises, also influencing water extraction. These findings provide a theoretical foundation and design guidelines for the development of high-performance thermal extraction payloads for future lunar ISRU missions.