Third Generation Advanced PPA Development
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Abstract
A Phase 3 advanced development project has culminated in the design and fabrication of a third generation Plasma Pyrolysis Assembly (PPA), recovering up to 75% of the hydrogen currently lost as methane in Sabatier reactor effluent. By doing so, the PPA helps to minimize life support resupply costs for extended duration missions. The 3-year development effort, completed as part of NASA’s Atmosphere Revitalization Resource Recovery task, has resulted in a fully functional stand-alone 5-CM (crew member) capacity PPA prototype. This device, recently delivered to NASA-MSFC, embodies the current state of the art in microwave methane plasma pyrolysis. At 90% single pass conversion the third generation PPA shows a ten-fold increase in processing rate capability over the first generation PPA, improves microwave to chemical energy conversion efficiency by three-fold (to 22%), and maintains a low residual carbon production rate at 0.20% of carbon from converted methane. Additional third generation technology advancements include increased process autonomy, incorporation of a regenerative residual carbon trap and in-situ reactor cleaning using CO2 plasma oxidation. Future development work must focus on fully autonomous operation, increased carbon trap capacity, more complete regeneration and improved process energy efficiency.