Browsing by Author "Pitts, Ray"
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Item Capillary Provision of Water and Nutrients to Plants Grown in Microgravity(2020 International Conference on Environmental Systems, 2020-07-31) Nabity, James; Pitts, Ray; Rehmeier, Jacob; Weislogel, Mark; Escobar, Christine; Shaffer, Brett; Escobar, AdamPassive provision of water and nutrients for the growth of plants in microgravity environmental systems can effectively be accomplished through the exploitation of capillary forces in various geometries, such as a network of wetted open interior corners. Provided the Concus-Finn condition is satisfied, capillary flows may be established along conduits that consist of simple interior corners (or ‘wedges’). A numerical free surface solver tool was employed to predict capillary flow of water to inform the design and construction of test articles for use in drop tower experiments. In addition, single and parallel flow path configurations were investigated with consideration for harvesting duckweed, a micro-flowering plant, in a microgravity environment. We report the effects of material, surface conditions, and interior corner half-angle on capillary performance. Titanium, glass and polymeric materials with factory, machined, and shot peened surfaces were used in experiments with deionized water and duckweed. The results guided the advanced development of micro-plant growth beds.Item Investigating Waste Preparation Methods for Trash-to-Gas Technologies(51st International Conference on Environmental Systems, 7/10/2022) Shah, Malay; Pitts, Ray; Benson, Morgan; Gleeson, JonathanTrash-to-gas technologies show promise in addressing the need for a sustainable waste management system onboard long-duration space habitats. However, a clear understanding on how the initial preparation and transport of waste into the reaction zone can affect the overall conversion efficiency must be realized. Factors such as the waste size, moisture content, and packing density can have significant impacts on the reactor performance. The goal of this study was to leverage current state-of-the-art preparation and delivery mechanisms to develop a concept for a full-scale, microgravity compatible system that can prepare and deliver waste that enhances the overall solid-to-gas conversion of existing trash-to-gas technologies. An extensive literature review was conducted to select potential candidates for such a system. High-performing candidates were tested in the laboratory environment using a mixed waste stream (organics and inorganics) to determine how these methods affect the total syngas production in a combustion reactor. This work will help lay the framework for implementation in a full-scale trash-to-gas system on exploration class space missions.Item Plasma Abatement of Volatile Organic Compounds.(2023 International Conference on Environmental Systems, 2023-07-16) Olson, Joel; Gott, Ryan; Wilhelm, Shayla; Campbell, Caiden; Engeling, Kenneth; Pitts, RayOne difficulty with crewed space operations is the potential for the contamination of the spacecraft habitable volume from volatile organic compounds (VOCs) that may be present. One possible VOC abatement process is to apply a plasma to the contaminated gases. Plasmas provide high energy electrons and ions that are capable of breaking down gaseous organic species generally into smaller compounds. To explore plasma VOC abatement, the authors constructed a plasma gas system that recirculates a particular VOC-laden gas mixture through a plasma torch. This allows for the periodic collection of aliquots of gaseous samples for subsequent analyses via gas chromatography mass spectrometry, designed to quantify the remaining VOC materials. The VOCs evaluated included 100 ppm of acetone, benzene, ethanol, and pentane in a background of carbon dioxide. The plasma conversion of all analytes followed first-order rate kinetics, and VOC elimination was observed after 10 min or less of treatment for all analytes measured. Additionally, it was observed that the plasma caused the conversion of CO2 into oxygen and CO.Item Space Mission Waste Conversion Experiments at the Zero Gravity Facility(2020 International Conference on Environmental Systems, 2020-07-31) Meier, Anne; Shah, Malay; Toro Medina, Jaime; Rinderknecht, David; Pitts, RayHumans are required to increase sustainability and efficiency on missions, which can be done in part by effectively managing logistical waste. Repurposed waste can be safely vented in the form of an inert gas off of a spacecraft, or useful material can be recovered, such as syngas (propellant), air, water, raw material for construction and repair feedstocks or replacement parts. The NASA Orbital Syngas / Commodity Augmentation Reactor (OSCAR) project has completed a 2 and 5 second microgravity test campaign at the Glenn Research Center Drop Tower and Zero Gravity Facility to demonstrate combustion and steam reforming for waste to gas technologies. The project continues to investigate thermochemical conversion of logistical space mission trash to a gas for venting or reuse. This paper discusses the project advancements since the 2 second Drop Tower testing in 2018 and provides updated results from the 5 second Zero Gravity Facility experimentation in 2019. Trash injection, inlet reaction gas flow direction, heat transfer, ignition, combustion and mixed waste streams in a microgravity environment are investigated. Benchtop tests were performed to highlight the behavioral discrepancies of OSCAR within gravity and microgravity environments, which was the primary purpose of this work. Overall results are used to decide the appropriate method to model the system, help guide the design of how air, or other oxidant, should be introduced into the hearth zone for optimum material conversion, and assist in the next design phase for a suborbital flight demonstration. The work in this report presents the 5 second microgravity test campaign data with gravity data for space mission trash items, reactor design iterations, preheat temperature and trash ignition conditions.Item Suborbital Testing of the OSCAR Trash-to-Gas System(51st International Conference on Environmental Systems, 7/10/2022) Pitts, Ray; Meier, Anne; Olson, Joel; Shah, Malay; Rinderknecht, David; Toro Medina, JaimeWith the sustained human exploration of nearby celestial bodies on the horizon, a renewed outlook on waste management must be realized. Current waste management strategies aboard the International Space Station become impractical as we venture further away from low Earth orbit and the resources that can be extracted from waste streams are substantial. One method of combatting this issue is by thermally degrading solid and liquid crew waste items into a chemically inert, ventable gas stream, a process known as Trash-to-Gas. The Orbital Syngas/Commodity Augmentation Reactor (OSCAR) is the state-of-the-art Trash-to-Gas system which has been designed to explore microgravity Trash-to-Gas concepts for improved mass/volume reduction and resource recovery from waste. OSCAR is a subscale testbed design that supports the NASA Logistics Reduction (LR) project under the Advanced Exploration System (AES) Program and Space Technology Mission Directorate (STMD) Flight Opportunities Program to determine the feasibility of Trash-to-Gas technology for use on future long duration space missions. OSCAR has flown on two suborbital flight demonstrations aboard Blue Origin�s New Shepard launch vehicle. This paper presents an overarching comparative analysis of these microgravity test campaigns with 1g laboratory experimentation. Percent gasification, product gas composition, soot and water production, reactor temperature and pressure, trash injection methodology, and system automation are compared to highlight the operational discrepancies within the microgravity environment for future optimization. The OSCAR system design progression and up-to-date lessons learned are also discussed for consideration into follow-on human spaceflight mission architectures.