Browsing by Author "Greenwood, Zachary W."
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Item Evaluation of an Atmosphere Revitalization Subsystem for Deep Space Exploration Missions(45th International Conference on Environmental Systems, 2015-07-12) Perry, Jay L.; Abney, Morgan B.; Conrad, Ruth E.; Frederick, Kenneth R.; Greenwood, Zachary W.; Kayatin, Matthew J.; Knox, James C.; Newton, Robert L.; Parrish, Keith J.; Takada, Kevin C.; Miller, Lee A.; Scott, Joseph P.; Stanley, Christine M.An Atmosphere Revitalization Subsystem (ARS) suitable for deployment aboard deep space exploration mission vehicles has been developed and functionally demonstrated. This modified ARS process design architecture was derived from the International Space Station’s (ISS) basic ARS. Primary functions considered in the architecture include trace contaminant control, carbon dioxide removal, carbon dioxide reduction, and oxygen generation. Candidate environmental monitoring instruments were also evaluated. The process architecture rearranges unit operations and employs equipment operational changes to reduce mass, simplify, and improve the functional performance for trace contaminant control, carbon dioxide removal, and oxygen generation. Results from integrated functional demonstration are summarized and compared to the performance observed during previous testing conducted on an ISS-like subsystem architecture and a similarly evolved process architecture. Considerations for further subsystem architecture and process technology development are discussed.Item Hydrogen Purification in Support of Plasma Pyrolysis of Sabatier Derived Methane(45th International Conference on Environmental Systems, 2015-07-12) Holtsnider, John T.; Wheeler, Richard R.; Dewberry, Ross H.; Abney, Morgan B.; Greenwood, Zachary W.The use of microwave regenerative sorption media for purification of hydrogen has been studied. The Sabatier Assembly recovers oxygen from carbon dioxide while consuming hydrogen and producing methane and water. The Plasma Pyrolysis Assembly (PPA) is being developed to recover most of the hydrogen from the methane. Acetylene and smaller amounts of other hydrocarbons are produced as byproducts of PPA operation. The present project is directed toward purifying the hydrogen product gas using sorption media and subsequently thermally regenerating the media using microwave power. The penetrative nature of microwave heating is utilized to efficiently drive gas desorption from the physical sorbents. Microwave heating drives off captured contaminants from a sorbent bed (which is held at relative vacuum) during regeneration. A series of molecular sieves, activated carbons and high surface area forms of alumina and silica were evaluated as candidate sorbent materials. Additionally, water vapor removal with the use of silica gel was evaluated. As a result of this research, hydrogen recovery from Sabatier methane is improved, thereby further closing the air-loop. Such increases in efficiency are necessary for crewed deep space exploration missions.Item Increased Oxygen Recovery from Sabatier Systems Using Plasma Pyrolysis Technology and Metal Hydride Separation(45th International Conference on Environmental Systems, 2015-07-12) Greenwood, Zachary W.; Abney, Morgan B.; Perry, Jay L.; Miller, Lee A.; Dahl, Roger W.; Hadley, Neal M.; Wambolt, Spencer R.; Wheeler, Richard R.State-of-the-art life support carbon dioxide (CO2) reduction technology is based on the Sabatier reaction where less than 50% of the oxygen required for the crew is recovered from metabolic CO2. The reaction produces water as the primary product and methane as a byproduct. Oxygen recovery is constrained by the limited availability of reactant hydrogen. This is further exacerbated when Sabatier methane (CH4) is vented as a waste product resulting in a continuous loss of reactant hydrogen. Post-processing methane with the Plasma Pyrolysis Assembly (PPA) to recover hydrogen has the potential to dramatically increase oxygen recovery and thus drastically reduce the logistical challenges associated with oxygen resupply. The PPA decomposes methane into predominantly hydrogen and acetylene. Due to the highly unstable nature of acetylene, a separation system is necessary to purify hydrogen before it is recycled back to the Sabatier reactor. Testing and evaluation of a full-scale Third Generation PPA is reported and investigations into metal hydride hydrogen separation technology is discussed.