Browsing by Author "Hintze, Paul"
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Item Development of a Micro-Scale Plasma Arc Gasification System for Long Duration Space Mission Waste Processing(47th International Conference on Environmental Systems, 2017-07-16) Meier, Anne; Thakrar, Prital; Shah, Malay; Johnson, Thad; Bayliss, Jon; Hintze, Paul; Gibson, Tracy; Captain, JamesThe NASA Space Technology Mission Directorate Center Innovation Fund at Kennedy Space Center (KSC) funded a one year investigation for the development of a micro-scale plasma arc gasification system for waste repurposing on long duration space missions. The reuse of discarded materials on a long duration or planetary mission is a critical component in reducing overall mission mass and creating useful commodities like fuel, water and repurposed construction materials. Plasma arc gasification converts the majority of organic waste into a synthesis gas (syngas), consisting primarily of hydrogen, carbon monoxide and carbon dioxide, and inorganic waste into a solid slag material that can be used as a construction aggregate. Plasma arc gasification had not been previously investigated for space applications, and potentially provides a cleaner product than other waste processing methods. The micro-scale plasma arc gasification system was designed, fabricated, and tested at KSC with a commercial plasma torch. This paper will discuss the project development and results regarding the use of plasma at low power and the challenges of plasma arc gasification for small scale waste conversion. Designing the power supply was the main challenge in this project. Although this plasma torch was successfully operated for short periods of time, the power supplies did not allow for low power operations over long periods of time.Item Evaluation of Low-Pressure Cold Plasma for Disinfection of ISS Grown Produce and Metallic Instrumentation(47th International Conference on Environmental Systems, 2017-07-16) Hintze, Paul; Franco, Carolina; Hummerick, Mary; Maloney, Phillip; Spencer, LashelleCold plasma (CP) cleaning is a dry, non-thermal process, which can provide broad-spectrum antimicrobial activity yet reportedly causes little to no damage to the object being sanitized. Since cold plasma uses no liquids, it has the distinct advantage when used in microgravity of not having to separate liquids from the item being cleaned. This paper will present results on an effort to use low pressure CP to disinfect or sterilize materials for in space applications. Exposure times from 0 to 60 minutes and pressures ranging from 0.10 to 1.0 mbar were used to optimize plasma parameters. Tests were done on produce and metal coupons to simulate medical equipment. Escherichia coli was used as the challenge organism on produce and Bacillus pumilus SAFR-32 was used on metal surfaces. Produce testing was not successful, with unacceptable kill rates and the produce being negatively impacted by exposure to the plasma. The plasma caused a 5 log reduction in the number of viable bacteria on metal coupon tests, which placed the number of viable bacteria below the detection limit. This is a very promising result showing that sterilization of medical equipment with cold plasma is feasible. Scanning Electron Microscope images were taken before and after exposure. The images after plasma exposure show that the bacteria spores have been physically affected, as their size has gotten smaller and their appearance has changed.Item Extraterrestrial Mining Via Two Coupled Thermal-Driven Phenomena(2023 International Conference on Environmental Systems, 2023-07-16) Dominguez, Jesus; Mccall, Shannon; Crawford, Kagen; Hintze, Paul; Black, Cara; Brown, BrittanyTwo-coupled thermal-driven phenomena, the Marangoni effect and thermal fractional decomposition under high vacuum, observed by the authors could lead to an extraterrestrial mining operation that would significantly reduce mechanical operation and allow in-situ product extraction directly from the mineral without the necessity of either mineral beneficiation or use of terrestrial precursors. Thermal Marangoni effect alone and coupled with fractional decomposition have been corroborated through paths of 10 and 13 inches respectively on molten JSC-1A lunar regolith simulant. These two coupled phenomena (self-transportation via the Marangoni effect and fractional decomposition at a higher temperature) present a novel and valuable potential for extraterrestrial mining as the observed outcome will be more prominent on extraterrestrial surfaces under higher vacuum and reduced gravity. A comprehensive 3D model built by the authors demonstrated to be a crucial tool to determine the right location of the sample to optimize the gradient temperature along the wall of a long tubular crucible enhancing the Marangoni effect as surface tension (the driving force for the thermal Marangoni effect) depends on the temperature gradient.Item Instrument for Solvent Extraction and Analysis (ISEE) of Organics from Regolith Simulant Using Supercritical Fluid Extraction and Chromatography(47th International Conference on Environmental Systems, 2017-07-16) Franco, Carolina; Hintze, PaulISEE is an instrument with the potential to do extractions of regolith found on the surface of asteroids and planets, followed by characterization and quantitation of the extracts. Supercritical fluid extraction (SFE) is a developed technique proven to extract a wide range of organic compounds. Supercritical CO2 will be the solvent utilized for these techniques as it is readily available in the Mars atmosphere composed of about 95% CO2. ISEE will capture CO2 from the environment, which will be pressurized and heated inside an extraction vessel, becoming a great solvent with high penetration properties. The same solvent will be then taken to supercritical fluid the chromatography (SFC) for analysis. This paper will present results on a preliminary, proof-of-principle effort to use SFE and SFC to extract and analyze lunar regolith simulant previously spiked with four organic compounds (naphthalene, stearic acid, L-tryptophan, and polystyrene) representing a full range of organics that ISEE will expect to characterize. Moreover, three columns were selected to analyze multiple samples at a time; two of them are Viridis HSS C18 SB and Torus DIOL, and the third column, not selected yet, must have the ability to perform chiral separations of amino acids. An optimization of variables for the extraction of the organics from the spiked regolith was successfully developed, using 138 bar pressure and 40 ˚C temperature. The extraction flow rate was optimized at 2 SLPM with 30% methanol modifier. The extractions were successful with a value of 77.3% ± 0.9 of organics extracted. However, the recovery of organics after the extraction was very low with only 48.5% ± 14.2.Item Mars Atmospheric Conversion to Methane and Water: An Engineering Model of the Sabatier Reactor with Characterization of Ru/Al2O3 for Long Duration Use on Mars(47th International Conference on Environmental Systems, 2017-07-16) Meier, Anne; Shah, Malay; Hintze, Paul; Petersen, Elspeth; Muscatello, AnthonyThe Atmospheric Processing Module (APM) is a Mars In-Situ Resource Utilization (ISRU) technology designed to demonstrate conversion of the Martian atmosphere into methane and water. The Martian atmosphere consists of approximately 95% carbon dioxide (CO2) and residual argon and nitrogen. APM utilizes cryocoolers for CO2 acquisition from a simulated Martian atmosphere and pressure. The captured CO2 is sublimated and pressurized as a feedstock into the Sabatier reactor, which converts CO2 and hydrogen to methane and water. The Sabatier reaction occurs over a packed bed reactor filled with Ru/Al2O3 pellets. The long duration use of the APM system and catalyst was investigated for future scaling and failure limits. Failure of the catalyst was detected by gas chromatography and temperature sensors on the system. Following this, characterization and experimentation with the catalyst was carried out with analysis including x-ray photoelectron spectroscopy and scanning electron microscopy with elemental dispersive spectroscopy. This paper will discuss results of the catalyst performance, the overall APM Sabatier approach, as well as intrinsic catalyst considerations of the Sabatier reactor performance incorporated into a chemical model.Item Sabatier System Design Study for a Mars ISRU Propellant Production Plant(48th International Conference on Environmental Systems, 2018-07-08) Hintze, Paul; Meier, Anne; Shah, MalayAs NASA looks towards human missions to Mars, an effort has started to advance the technology of a Mars ISRU Propellant Production Plant for a flight demonstration. This paper will present a design study of the Sabatier subsystem. The Sabatier subsystem receives CO2 and H2 and converts them to CH4 and H2O. The subsystem includes the Sabatier reactor, condenser, thermal management, and recycling system if required. This design study will look at how the choice of reactor thermal management and recycling system affect the performance of the overall Sabatier system. Different schemes from the literature involving single or cascading reactors will be investigated to see if any provide distinct advantages for a Mars propellant production plant.Item Study of Sabatier Catalyst Performance for a Mars ISRU Propellant Production Plant(49th International Conference on Environmental Systems, 2019-07-07) Franco, Carolina; Devor, Robert; Snyder, Sarah J.; Petersen, Elspeth M.; Hintze, PaulNASA is currently developing technologies for use in the field of in-situ resource utilization (ISRU). One of the technologies being advanced is the Sabatier, or methanation, reactor which converts carbon dioxide and hydrogen into methane gas and water at high temperatures. This paper discusses the catalyst life and performance issues for these reactors that would be expected on Mars and describes the test methods employed and observed results. The various catalysts were tested in their capacity for the continuous production of methane gas via the Sabatier reaction and the possible effects of launch vibration loads, exposure to liquid water, particulate contamination, and chemical contamination to the overall observed reaction efficacy of the catalysts evaluated.Item Visible-Light-Responsive Photocatalysis: Ag-Doped TiO2 Catalyst Development and Reactor Design Testing(46th International Conference on Environmental Systems, 2016-07-10) Coutts, Janelle; Hintze, Paul; Meier, Anne; Devor, Robert; Surma, Jan; Maloney, Phillip; Bauer, Brint; Shah, Malay; Mazyck, DavidIn recent years, the alteration of titanium dioxide to become visible-light-responsive (VLR) has been a major focus in the field of photocatalysis. Currently, bare titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Hg-vapor fluorescent light sources are used in photocatalytic oxidation (PCO) reactors to provide adequate levels of ultraviolet light for catalyst activation; these mercury-containing lamps, however, hinder the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. VLR-TiO2 would allow for use of ambient visible solar radiation or highly efficient visible wavelength LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Over the past three years, Kennedy Space Center has developed a VLR Ag-doped TiO2 catalyst with a band gap of 2.72 eV and promising photocatalytic activity. Catalyst immobilization techniques, including incorporation of the catalyst into a sorbent material, were examined. Extensive modeling of a reactor test bed mimicking air duct work with throughput similar to that seen on the International Space Station was completed to determine optimal reactor design. A bench-scale reactor with the novel catalyst and high-efficiency blue LEDs was challenged with several common volatile organic compounds (VOCs) found in ISS cabin air to evaluate the system’s ability to perform high-throughput trace contaminant removal. The ultimate goal for this testing was to determine if the unit would be useful pre-heat exchanger operations to lessen condensed VOCs in recovered water and lowering the burden of VOC removal for water purification systems.Item Wastewater Brine Purification and Recovery through Electrodialysis Ion Exchange(50th International Conference on Environmental Systems, 7/12/2021) Hancock, Matthew; Snyder, Sarah; Hintze, PaulReutilizing resources onboard the International Space Station (ISS) and for future deep space missions are critical for mission longevity and sustainability. Wastewater brine produced from water recovery systems contain chemical species that could be processed into a potential fertilizer for future plant systems. This can be achieved through a process called electrodialysis ion exchange. Wastewater containing inorganic salt components are fed through a series of ion exchange membranes to produce fertilizer (a phosphate rich stream), electrolysis-grade water, and other useful commodities. Electrodialysis cells consisting of anion and cation exchange membranes, monovalent anion exchange membranes, and bipolar membranes were utilized to achieve selective ion exchange. The use of the electrodialysis cells were effective for both water extraction and ion separation. Ions successfully diffused across their respective membranes into the concentrate, acid, and base streams. This resulted in pure water, a phosphate rich stream, and a separate anion/hydrogen and cation/hydroxide stream. However, sulfate and some phosphate ions were able to diffuse through the monovalent anion exchange membrane into the acid stream. This resulted in predominantly phosphate ions remaining in the concentrate. Optimization of the process was accomplished by altering flowrates of each stream and initial volumes, adjusting the power input and resulting current through each cell, and varying the starting parameters by splitting the inorganic waste input into the diluate and the concentrate. As expected, increasing the flowrate and the power input to each cell reduced the overall time of the process. However, mission constraints may require a longer duration process in order to reduce the power consumption. Further analysis will be required to determine the power input necessary to achieve ion diffusion effectively and in a timely manner.