Indirect solar receiver development for the thermal extraction of H2O(v) from lunar regolith: Heat and mass transfer modeling

A novel indirect solar receiver/volatile extractor concept was considered for thermally extracting H2O(s) from lunar regolith in the permanently shadowed regions on the Moon. The modeled indirect solar receiver/H2O(s) extractor consisted of a rigid, highly conductive chamber that was partially embedded in the lunar surface. Solar selective and non-selective absorbers were examined to efficiently capture concentrated solar irradiation and effectively transfer heat to icy regolith to drive H2O sublimation. A detailed heat and mass transfer model was developed in ANSYS Fluent to assess the feasibility of thermal extraction from permanently shadowed regions near the lunar poles with 5 wt% of H2O(s). The maximum H2O(v) collected after 10 terrestrial h of simulation time was 2789 g for the solar selective coated receiver and 1035 g for the non-selective receiver. The addition of a solar selective coating was observed to significantly enhance H2O(s) thermal extraction. The low lunar regolith thermal conductivity was shown as the major bottleneck for thermal extraction.