Oxygen Extraction from Lunar Regolith via Free-Fall Induction Heating
Joel Meno, Peter Schubert

Progeny Systems

Packer Engineering, Chicago, IL

Extraction of oxygen from extraterrestrial minerals can be accomplished in several ways, one of which is a patented process regarding free-fall induction heating. This process would require pre-melted lunar regolith to be passed through induction heating coils operating at a specified resonant frequency (or within a specified band of frequencies) in order to further heat the molten regolith to 3000 K in order to liberate oxygen from the stream. This paper investigates what frequency band will be most efficient in providing the necessary heating rate for lunar regolith through analytical theory, experimental findings, and computational modeling. Closed-form analytical approaches to setting induction heating parameters do exist, but only under stringent assumptions including low frequencies and small work piece diameters. Experimentally, it was found that the closed-form approach began to break down at frequencies above 100 kHz and workpiece diameters greater than 13 mm. Further experimental results show that pure lunar regolith simulant JSC-1a was unable to be heated using frequencies of 104 kHz and 550 kHz with varying coil diameters and coil densities ranging from 6.2 cm to 10 cm and 78 turns/m and 129 turns/m, respectfully. However, when doped with iron filings (20% by mass), a steady-state condition of 723 K was reached using 550 kHz and a 30 kW induction unit. Computational modeling results confirmed analytical and experimental findings though further work needs to be done to determine feasibility. Overall, the analytical theory, experimental findings, and computational modeling allow for elimination of a broad range of designs for this application and will serve as a guide for future designs.

Presented at ISDC 2011 - Huntsville. Paper and presentation charts are not available.