Optimization and Efficiency Analysis of Lunar Water Vapor Condensation Collection Structure Devices

Abstract Aimed at the technical challenge of low water vapor collection efficiency in the in-situ thermal extraction of lunar polar water ice, this study, based on the heat and mass transfer characteristics of frost layer porous media, proposes a solution to enhance the gas-solid phase transition rate by optimizing the internal surface area of the water vapor collection unit. Through the establishment of a water vapor condensation dynamics model under vacuum and low-temperature conditions, the coupling effects of frost layer porosity and temperature field on the mass transfer process are revealed. A verification platform simulating the extreme lunar surface environment was constructed, and comparative experiments on different aluminum bead filling structures were conducted. The results indicate that the larger the internal surface area of the device, the higher the water vapor collection efficiency; the use of small-diameter aluminum beads significantly increases the internal surface area, but excessively small diameters may lead to pore blockage. The initial stage of water vapor collection is one of the key stages of mass transfer, where water vapor first comes into contact with the inner surface of the collection structure and undergoes a gas-solid phase change that affects the continued performance of the collection device. This research provides theoretical and experimental foundations for the design of water vapor collection units in in-situ lunar water ice extraction devices.