Browsing by Author "Cmarik, Gregory"
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Item 4-Bed CO2 Scrubber – From Design to Build(2020 International Conference on Environmental Systems, 2020-07-31) Cmarik, Gregory; Knox, James; Peters, WarrenFour-bed technology is an International Space Station (ISS) mainstay for metabolic Carbon Dioxide (CO2) removal and crew life support. The current generation is known as the Carbon Dioxide Removal Assembly (CDRA) and has a long history of unplanned maintenance as well as obsolete core components. The 4-bed CO2 Scrubber was commissioned to operate with no unplanned maintenance for 3 years while removing 4 crew-equivalents of CO2 at a target inlet concentration of 2 torr CO2. This work goes into detail of the various design aspects which have been undertaken to ensure a successful project design and successful build leading to an upcoming flight. This work will discuss the compromises caught both early and late in the design cycle and the adaptations in response. Finally, the expected performance of the system once launched will be discussed based on summaries of data from the testbed.Item 4BCO2 EDU Performance(50th International Conference on Environmental Systems, 7/12/2021) Peters, Warren; Cmarik, Gregory; Knox, JamesNASA is reducing the power, volume and mass requirements on future CO2 (Carbon Dioxide) removal systems for exploration missions. To meet this goal, a 4BCO2 flight experiment based on 4BMS (Four Bed Molecular Sieve) technology is under construction and will fly to ISS (International Space Station) for on-orbit performance and reliability testing. The 4BCO2 flight experiment was based on the 4BMS-X EDU (Engineering Development Unit) design, which has been modified to incorporate elements of the flight system. This paper will present the operational performance of the 4BCO2 EDU.Item Analysis of Performance Degradation of Silica Gels after Extended use Onboard the ISS(48th International Conference on Environmental Systems, 2018-07-08) Cmarik, Gregory; Knox, James; Huff, TimothyThe disassembly of two flight desiccant beds from the Carbon Dioxide Removal Assembly (CDRA) revealed significant discoloration of the silica gel near the bed inlet as well as a coincidental performance loss. This material was analyzed for the presence of chemical contaminants, physical porosity changes, and adsorption performance. The material characteristics are compared against the location in the bed from which they were sampled in order to develop profiles through the bed. Additional testing of the beds prior to disassembly provided more data points. Possible mechanisms for the loss of capacity are provided though no root cause has been confirmed. Extrapolation of the performance loss is used to estimate the required oversizing of the silica gel layer for long-term operation.Item Co-Adsorption of Carbon Dioxide on Zeolite 13X in the Presence of Preloaded Water(48th International Conference on Environmental Systems, 2018-07-08) Cmarik, Gregory; Knox, JamesEnvironmental Control and Life Support requires highly effective CO2 removal systems. The current system onboard the International Space Station is known as Carbon Dioxide Removal Assembly. Recent high-fidelity simulation of this system predicted a major efficiency gain via reduction of desiccant zeolite. Commercial beaded 13X zeolite is used in the desiccant bed to scrub water below 1 ppm but is also a highly active CO2 sorbent. The simultaneous adsorption of water vapor and CO2 is known to strongly favor water, but more accurate measurements are needed. This work details the characterization of the zeolite to be used in the next-generation CO2 removal system for co-adsorption of water and CO2.Item CO2 Removal for the International Space Station – 4-Bed Molecular Sieve Material Selection and System Design(49th International Conference on Environmental Systems, 2019-07-07) Cmarik, Gregory; Knox, JamesEfforts over the past three years have focused on the study of candidate sorbent materials for use in a 4BMS molecular sieve system. The accumulation of knowledge has been invaluable for further decisions and for reflecting on the conclusions of past decisions. The goal of the next generation CO2 removal system is continuous, failure-free operation for nearly 20,000 hours, but no complex life support system has yet reached this lofty goal. In addition to reliability, CO2 removal performance improvements have been intensively studied. The achievements toward this end include highly detailed isotherm measurements which drive system simulations as well as testing physical design improvements. Looking back on the successes and failures of past systems, correlating data from long-duration tests, and carefully projecting future results are all needed for the success of the next system. This work intends to reveal the path we have taken and illuminate the steps to come for CO2 removal life support with the 4BCO2 flight demonstration.Item Development of Carbon Dioxide Removal Systems for Advanced Exploration Systems 2015-2016(46th International Conference on Environmental Systems, 2016-07-10) Knox, James; Coker, Robert; Howard, David; Peters, Warren; Watson, David; Cmarik, Gregory; Miller, LeeA long-term goal for NASA is to enable crewed missions to Mars: first to the vicinity of Mars, and then to the Mars surface. These missions present new challenges for all aspects of spacecraft design in comparison with the International Space Station, as resupply is unavailable in the transit phase, and early return is not possible. Additionally, mass, power, and volume must be minimized for all phases to reduce propulsion needs. Mass reduction is particularly crucial for Mars surface landing and liftoff due to the challenges inherent in these operations for even much smaller payloads. In this paper we describe current and planned developments in the area of carbon dioxide removal to support future crewed Mars missions. Activities are also described that apply to both the resolution of anomalies observed in the ISS CDRA and the design of life support systems for future missions.Item Four Bed Carbon Dioxide Scrubber Engineering Development Unit Cabin Air Inlet Testing(2023 International Conference on Environmental Systems, 2023-07-16) Knox, James; Cmarik, Gregory; Garr, JohnItem Investigation of desiccants and CO2 sorbents for advanced exploration systems 2015-2016(46th International Conference on Environmental Systems, 2016-07-10) Knox, James; Cmarik, Gregory; Watson, David; Miller, Lee; West, Philip; Wingard, CharlesDesign of advanced carbon dioxide removal systems begins with the study of sorbents. Specifically, new CO2 sorbents and desiccants need to be studied to enable greater productivity from existing and future spaceflight systems. This presentation will discuss the studies used as input for selecting future CO2 sorbent materials. Also, the adjoining issues of understanding the effects of water co-adsorption and material selection for desiccant beds will be discussed. Current sorbents for CO2 removal are based on 5A zeolites, but a transition to sorbents derived from 13X will be necessary as CO2 levels in cabin air become leaner. Unfortunately, these 13X zeolites are more susceptible to long-term performance loss due to water co-adsorption than 5A due at achievable regeneration temperatures. A study on how impactful the presence of trace water will be to the cyclic operation of small-scale beds will be discussed. Also, methods to recover the performance of beds in a space environment after a major moisture adsorption event will be discussed. The information obtained from the water co-adsorption studies will play a major part in selecting a CO2 sorbent for advanced removal systems. Pellet structural properties play another major role in the selection process. One factor for long-term, hands-off operation of a system is pellet integrity. Maintaining integrity means preventing pellet fracture and the generation of fines due to various thermal and mechanical means which would eventually clog filters or damage downstream systems. Either of these problems require significant shutdowns and maintenance operations and must be avoided. Therefore, study of high-integrity pellets and design of new pellets will be discussed.Item Investigation of Desiccants and CO2 Sorbents for Exploration Systems 2016-2017(47th International Conference on Environmental Systems, 2017-07-16) Knox, James; Cmarik, Gregory; Watson, David; Miller, Lee; Giesy, TimothyNASA has embarked on the mission to enable humans to explore deep space, including the goal of sending humans to Mars. This journey will require significant developments in a wide range of technical areas as resupply and early return are not possible. Additionally, mass, power, and volume must be minimized for all phases to maximize propulsion availability. Among the critical areas identified for development are life support systems, which will require increases in reliability as well as reduce resource usage. Two primary points for reliability are the mechanical stability of sorbent pellets and recovery of CO2 sorbent productivity after off-nominal events. In this paper, we discuss the present efforts towards screening and characterizing commercially-available sorbents for extended operation in desiccant and CO2 removal beds. With minimized dusting as the primary criteria, a commercial 13X zeolite was selected and tested for performance and risk.Item Optimization of the 4-Bed CO2 Scrubber Performance Based on Ground Tests(50th International Conference on Environmental Systems, 7/12/2021) Knox, James; Peters, Warren; Cmarik, GregoryTesting of ground hardware closely matching the flight design for the 4-Bed CO2 Scrubber (4BCO2) has provided a wealth of information about the complex and highly coupled batch process. The 4BCO2 process is a Thermal and Vacuum Swing Adsorption (TVSA) cycle with recirculating flows. The ability to measure CO2 concentration at intermediate points in this architecture is new to this ground test system and has revealed a better understanding of system performance and its dependence on system design, operational parameters, and boundary conditions. This paper will discuss a statistical analysis performed to identify significant correlations between performance factors and operational parameters. Using these new insights on the highly coupled system physics, means for improvements to system performance are proposed.Item Performance of the Four Bed Carbon Dioxide Scrubber ISS Technology Demonstration(51st International Conference on Environmental Systems, 7/10/2022) Knox, James; Cmarik, Gregory; Garr, JohnThe Four Bed Carbon Dioxide Scrubber technology demonstration is presently operating onboard the International Space Station after being launched in August of 2021 and activated in October. This work describes the ground and flight performance of the 4BCO2 and the methods used to determine performance on the ISS where limited sensor data is available.Item Progress of Four Bed Carbon Dioxide Scrubber(51st International Conference on Environmental Systems, 7/10/2022) Cmarik, Gregory; Knox, James; Garr, JohnThe Four Bed Carbon Dioxide Scrubber flight demonstration is presently operating onboard the International Space Station. After being launched in August of 2021 and installed in October, the system has been removing metabolic CO2 from the cabin as a supplement and replacement for other CO2 systems, specifically the two Carbon Dioxide Removal Assemblies. This work describes the conclusion of the ground integration and testing campaign and the start of on orbit operations. Additionally, performance, reliability, and forward works will be summarized. Interactions of the software with off-nominal events will be discussed and how the system will be reconfigured to sustain operations.Item Status of the Four Bed Carbon Dioxide Scrubber ISS Technology Demonstration 2022-2023(2023 International Conference on Environmental Systems, 2023-07-16) Knox, James; Cmarik, Gregory; Garr, JohnThe Four Bed Carbon Dioxide Scrubber flight demonstration is presently operating onboard the International Space Station. After being launched in August and activated in September 2021, the system has been removing metabolic CO2 from the cabin as a supplement and replacement for other CO2 removal systems, specifically the two Carbon Dioxide Removal Assemblies. This paper describes on-orbit operations and changes (including installation of the Calnetix blower) during 2022 and early 2023. Performance of the system especially as affected by changes in the on-orbit configuration will be described. System reliability, software changes, and ongoing efforts will be summarized.