Browsing by Author "Vijayakumar, R."
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Item Characterization of a Regenerable Impactor Filter for Spacecraft Cabin Applications(45th International Conference on Environmental Systems, 2015-07-12) Agui, Juan H.; Vijayakumar, R.Regenerable filters will play an important role in human exploration beyond low-Earth orbit. Life Support Systems aboard crewed spacecrafts will have to operate reliably and with little maintenance over periods of more than a year, even multiple years. Air filters are a key component of spacecraft life support systems, but they often require frequent routine maintenance. Bacterial filters aboard the International Space Station require almost weekly cleaning of the pre-filter screen to remove large lint debris captured in the microgravity environment. The source of the airborne matter which is collected on the filter screen is typically from clothing fibers, biological matter (hair, skin, nails, etc.) and material wear. Clearly a need for low maintenance filters requiring little to no crew intervention will be vital to the success of the mission. An impactor filter is being developed and tested to address this need. This filter captures large particle matter through inertial separation and impaction methods on collection surfaces, which can be automatically cleaned after they become heavily loaded. The impactor filter can serve as a pre-filter to augment the life of higher efficiency filters that capture fine and ultrafine particles. A prototype of the filter is being tested at the Particulate Filtration Laboratory at NASA Glenn Research Center to determine performance characteristics, including particle cut size and overall efficiency. Model results are presented for the flow characteristics near the orifice plate through which the particle-laden flow is accelerated as well as around the collection bands.Item Characterization of carbon particulates in the exit flow of a Plasma Pyrolysis Assembly (PPA) reactor(45th International Conference on Environmental Systems, 2015-07-12) Green, Robert D.; Meyer, Marit E.; Agui, Juan H.; Berger, Gordon M.; Vijayakumar, R.; Abney, Morgan B.; Greenwood, ZacharyThe ISS presently recovers oxygen from crew respiration via a Carbon Dioxide Reduction Assembly (CRA) that utilizes the Sabatier chemical process to reduce captured carbon dioxide to methane (CH4) and water. In order to recover more of the hydrogen from the methane and increase oxygen recovery, NASA Marshall Space Flight Center (MSFC) is investigating a technology, plasma pyrolysis, to convert the methane to acetylene. The Plasma Pyrolysis Assembly (or PPA), achieves 90% or greater conversion efficiency, but a small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. In this work, we present the experimental results of an initial characterization of the carbon particulates in the PPA exit gas stream. We also present several potential options to remove these carbon particulates via carbon traps and filters to minimize resupply mass and required downtime for regeneration.Item Commercial Contamination Control Practices Applicable for Protecting Crew and Environment(47th International Conference on Environmental Systems, 2017) Vijayakumar, R.Crewed space exploration poses several challenges for protecting the crew’s environment over a long period, as well as protecting the local extra terrestrial environment. Although some of the design challenges are unique to space exploration, the underlying technology and practice of maintaining the cleanliness of the air the crew breathes are commercially well established. This paper will survey commercial best practices in controlling and maintaining the desirable air quality in the crew cabins, mainly with respect to particulate matter in the cabin air. Commonly accepted industry practices for testing and specifying air filter products for these applications will also be addressed. The goal of the paper is to help with fluency in commercial contamination control practices and hence ensure effective designs of air quality systems for crewed habitats.Item Development of Challenge Aerosols for Testing Filters in Spacecraft Air Revitalization Systems(2023 International Conference on Environmental Systems, 2023-07-16) Green, Robert; Berger, Gordon; Sumlin, Benjamin; Vijayakumar, R.; Agui, JuanThe common means for reducing particle concentrations in air in enclosed spaces, including in space habitats, are source prevention and particle removal by air filters. While air filtration and testing is a well-established discipline and industry, testing and classifying filters according to commonly used standards rely on a test aerosol that is often arbitrary and chosen for the convenience of the test method. In space habitats, the particle size distributions are expected to be quite different than the particle size distributions prescribed in test standards, due to the partial or low gravity environment affecting sedimentation of large particulates like hair or cloth fibers, or the introduction of planetary dust to the pressurized volume. This means that the efficacy of the filter will be quite different in the space habitat than specified according to a prevailing standard. This paper will present some initial work in development of a “composite” challenge aerosol to bound the measured and reported particle sizes reported for the International Space Station (ISS), and for expected particulate matter in a Lunar lander, habitat, or orbiting platform susceptible to the intrusion of Lunar dust. Application of this test aerosol is expected to yield filter efficiencies and loading effects closer to what one can expect on these spacecraft and be useful in determining filter lifetime and replacement cycles.Item Development of test protocols for International Space Station particulate filters(44th International Conference on Environmental Systems, 2014-07-13) Green, Robert D.; Vijayakumar, R.; Agui, Juan H.Air quality control on the International Space Station (ISS) is a vital requirement for maintaining a clean environment for the crew and the hardware. This becomes a serious challenge in pressurized space compartments since no outside air ventilation is possible, and a larger particulate load is imposed on the filtration system due to lack of gravitational settling . The ISS Environmental Control and Life Support System (ECLSS) uses a filtration system that has been in use for over 14 years and has proven to meet this challenge. The heart of this system is a traditional High- Efficiency Particulate Air (HEPA) filter configured to interface with the rest of the life support elements and provide effective cabin filtration. Over the years, the service life of these filters has been re-evaluated based on limited post-flight tests of returned filters and risk factors. On earth, a well designed and installed HEPA filter will last for several years, e.g. in industrial and research clean room applications. Test methods for evaluating these filters are being developed on the basis of established test protocols used by the industry and the military. This paper will discuss the test methods adopted and test results on prototypes of the ISS filters. The results will assist in establishing whether the service life can be extended for these filters. Results from unused filters that have been in storage will also be presented to ascertain the shelf life and performance deterioration, if any and determine if the shelf life may be extended.Item Exploration Mission Particulate Matter Filtration Technology Performance Testing in a Simulated Spacecraft Cabin Ventilation System(47th International Conference on Environmental Systems, 2017-07-16) Agui, Juan; Vijayakumar, R.; Perry, Jay; McCormick, Robert; Frederick, KennethHuman deep space exploration missions will require advances in long-life, low maintenance airborne particulate matter filtration technology. As one of the National Aeronautics and Space Administration’s (NASA) developments in this area, a prototype of a new regenerable, multi-stage particulate matter filtration technology was tested in an International Space Station (ISS) module simulation facility. As previously reported, the key features of the filter system include inertial and media filtration with the ability to regenerate the working life of the filter system through in-situ inertial collector cleaning and on-the-fly media replacement. The testing facility can simulate aspects of the cabin environment aboard the ISS and contains flight-like cabin ventilation system components. The filtration technology test article was installed at the inlet of the central ventilation system duct and instrumented to provide performance data under nominal flow conditions. In-place regeneration operations were also evaluated. The real-time data included pressure drop across the filter stages, process air flow rate, ambient pressure, humidity and temperature. In addition, two video cameras positioned at the filtration technology test article’s inlet and outlet were used to capture the mechanical performance of the filter media indexing operation under varying air flow rates. Recent test results are presented and future design recommendations are discussed.Item Filter Efficiency and Pressure Drop Testing of Returned ISS Bacteria Filter Elements (BFEs)(47th International Conference on Environmental Systems, 2017-07-16) Green, Robert; Agui, Juan; Vijayakumar, R.; Berger, Gordon; Perry, JayThe air quality control equipment aboard the International Space Station (ISS) and future deep space exploration vehicles provide the vital function of maintaining a clean cabin environment for the crew and the hardware. This becomes a serious challenge in pressurized space compartments since no outside air ventilation is possible, and a larger particulate load is imposed on the filtration system due to lack of sedimentation. The ISS Environmental Control and Life Support (ECLS) system architecture in the U.S. Segment uses a distributed particulate filtration approach consisting of traditional High-Efficiency Particulate Air (HEPA) filters deployed at multiple locations in each U.S. Seg-ment module; these filters are referred to as Bacterial Filter Elements, or BFEs. In our previous work, we presented results of efficiency and pressure drop measurements for a sample set of two returned BFEs with a service life of 2.5 years. In this follow-on work, we present similar efficiency, pressure drop, and leak tests results for a larger sample set of six returned BFEs. The results of this work can aid the ISS Program in managing BFE logistics inventory through the station’s planned lifetime as well as provide insight for managing filter element logistics for future exploration missions. These results also can provide meaningful guidance for particulate filter designs under consideration for future deep space exploration missions.Item Filtration of carbon particulate emissions from a Plasma Pyrolysis Assembly Reactor(46th International Conference on Environmental Systems, 2016-07-10) Agui, Juan; Green, Robert; Vijayakumar, R.; Berger, Gordon; Greenwood, Zach; Abney, Morgan; Peterson, ElspethThe ISS presently recovers oxygen from crew respiration via a Carbon Dioxide Reduction Assembly (CRA) that utilizes the Sabatier chemical process to reduce captured carbon dioxide to methane (CH4) and water. In order to recover more of the hydrogen from the methane and increase oxygen recovery, NASA Marshall Space Flight Center (MSFC) is investigating a technology, plasma pyrolysis, to convert the methane to acetylene. The Plasma Pyrolysis Assembly (or PPA), achieves 90% or greater conversion efficiency, but a small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. We discuss developmental work on several options for filtering out the carbon particulate emissions from the PPA exit gas stream. We also present supporting characterization results of the carbon particulates that help to define filter requirements.Item Particulate Filtration Design Considerations for Crewed Spacecraft Life Support Systems(46th International Conference on Environmental Systems, 2016-07-10) Agui, Juan; Vijayakumar, R.; Perry, JayParticulate filtration is a key component of crewed spacecraft cabin ventilation and life support system (LSS) architectures. The various particulate filtration needs in an exploration vehicle LSS architecture are presented. Particulate filtration concepts are reviewed and design considerations are discussed. Testing results for media filter concepts are presented. Observations from these results that emphasize key design considerations for integrating particulate filtration into an LSS architecture are discussed. A recommended particulate filtration architecture based on testing results and best practice design considerations is proposed.Item Particulate Filtration from Emissions of a Plasma Pyrolysis Assembly Reactor Using Regenerable Porous Metal Filters(47th International Conference on Environmental Systems, 2017-07-16) Agui, Juan; Berger, Gordon; Vijayakumar, R.; West, Philip; Mitchell, Karen; Abney, Morgan; Greenwood, ZachMicrowave-based plasma pyrolysis technology is being studied as a means of supporting oxygen recovery in future spacecraft life support systems. The process involves the conversion of methane produced from a Sabatier reactor to acetylene and hydrogen, with a small amount of solid carbon particulates generated as a side product. The particles must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. We discuss developmental work on porous metal media filters for removing the carbon particulate emissions from the PPA exit gas stream and to provide in situ media regeneration capability. Because of the high temperatures involved in oxidizing the deposited carbon during regeneration, there was particular focus in this development on the materials that could be used, the housing design, and heating methods. This paper describes the design and operation of the filter and characterizes their performance from integrated testing at the Environmental Chamber (E-Chamber) at MSFC.