Browsing by Author "Barrett, Lawrence"
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Item Analysis Framework for the Evaluation of Media Beds in the Orion Smoke Eater Filter(50th International Conference on Environmental Systems, 7/12/2021) Barrett, Lawrence; Carrillo, Richard; Martinez, MariaIn the event of a fire onboard the Orion Multi-Purpose Crew Vehicle (MPCV), the Orion Smoke Eater Filter (OSEF) will be used to clean the cabin atmosphere via removal of particulates and potentially harmful gases. To facilitate this, the OSEF contains a bed of impregnated activated carbon to remove hydrocarbons, acid gases, and NH3 and a supported catalyst bed to oxidize CO to CO2. The analyses described herein were motivated by computerized tomography (CT) scans of an OSEF build and the packed beds of a similar technology which found potential channel formation and breakdown of the catalyst materials. In this work, we examined the potential adverse effects of these anomalies in bed packing. A model was generated to calculate the scrubbing rate of CO in the cabin. Next, the influence of channeling in the catalyst bed was examined; the Fanning and Colebrook equations were used to determine the amount of flow bypassing the catalyst bed due to the presence of channels and the size and number of channels allowable for appropriate scrubbing of the cabin. When the catalyst support in the CO catalyst bed breaks down, dusting occurs, affecting the flow across the particle bed and thereby reducing the catalyst bed utilization. We determined the effects of dusting on the scrubbing time using the scrubbing model and its impact on the pressure differential via a modified form of the Ergun equation; based on these analyses, requirements for the maximum allowable dusting concentrations were derived. The procedures and results described herein provide a framework for future examinations of the efficacy of bed packing procedures and the influence that they may have on contaminant removal applications.Item Chemical Challenge Tests on ISS Fire Cartridges(2023 International Conference on Environmental Systems, 2023-07-16) Muko, Cristina; Beck, Steven; Wallace, William; Hudson, Edgar; Barrett, Lawrence; Korona, Adam; Williams, Spencer; Gazda, Daniel; Rabel, EmilyFollowing a confirmed combustion event onboard the International Space Station (ISS), crew members will don Emergency Masks, each fitted with 2 ISS fire cartridge filters. As the crew member breathes through the filters, combustion products in the cabin air are either filtered or catalyzed by the fire cartridge media to minimize crew exposure to harmful levels of contaminants. Rigorous certification, acceptance, and surveillance programs for the fire cartridges ensure that each lot meets stringent performance requirements throughout the service life of the cartridges. In accordance with the Quality/Acceptance Test Plan, multiple fire cartridges from each lot undergo chemical challenge tests involving one or more chemicals at specified concentrations. These tests are conducted at specific temperatures, humidity levels, and gas flow rates intended to mimic the worst-case conditions for fire cartridge performance. These challenge tests are conducted by the Environmental Chemistry Laboratory at the NASA Lyndon B. Johnson Space Center. Many of the challenge tests focus on carbon monoxide (CO), but other gases include hydrogen cyanide (HCN), hydrogen chloride (HCl), cyclohexane, acrolein, ammonia (NH3), and acetaldehyde. A fire cartridge is exposed to the test gas in a chamber at the specified conditions, and the outlet is monitored for breakthrough during the 2.5-hour test. This paper will briefly introduce fire cartridges and how they work and will then discuss details of the challenge gas delivery and exposure system, breakthrough monitoring methods, and discussion of issues that have arisen during the course of the test program. Although the focus of this paper will be on the challenge tests, a general summary of the performance of the fire cartridges will also be provided.Item Evaluation of a New Commercial Catalyst for CO Oxidation for Environmental Control and Life Support Applications(2023 International Conference on Environmental Systems, 2023-07-16) Yaparatne, Sudheera; McCarthy, Madison; Nicoloro, Louis; Fisher, Neil; Apul, Onur; Graf, John; Barrett, Lawrence; George, OagengThe Contingency Breathing Apparatus (CBA) and Orion Smoke Eater Filter (OSEF) are equipment designed to clean up particulates and harmful gases released during a fire event onboard the Orion Multi-Purpose Crew Vehicle (MPCV). CO oxidation catalyst currently used in CBA and OSEF is developed by TDA research. In this study, a commercially available Au-Titania-based catalyst was evaluated for its CO oxidation ability. The possibilities of using Au-Ti catalyst for CO oxidation and comparison to TDA catalyst are expected in this study. The experimental setup was designed to measure the CO concentration accurately and control the gas flow rates, relative humidity (RH), and temperature at desired levels. The CO oxidation efficiency was measured in a fixed-bed reactor under different gas hourly space velocities (GHSVs), i.e., 1.1×10^4 h^-1 -1.1×10^5 h^-1. The catalyst performance was tested at 0 °C, 12 °C, 22 °C, 25 °C, and 35°C temperatures and 15%, 50%, and 85% RH levels at an initial CO concentration of 1000 ppm. At lower GHSVs (1.1×10^4 h^-1 and 2.7×10^4 h^-1), more than 97% CO removal was achieved at 0 °C near the catalyst. Higher GHSVs (1.1×10^5 h^-1) drastically diminished the CO oxidation percentage to ?66% due to less contact time of reactants with the catalyst. Increasing temperature near the catalysts demonstrated increased activity of the catalysts, and this change was more apparent at higher flow rates. The reaction kinetics confirmed the Arrhenius relationship with respect to the temperature dependence on reaction rates. At low GHSVs, a significant difference was not shown in the CO removals for different RHs. Higher GHSVs reduced the CO removal percentage from 79.7% to 66.4% when RH was changed from 15% to 85%, respectively. Temperature fluctuation near the catalyst, catalyst poisoning, and catalyst regeneration were also monitored in this study.Item High-Pressure Oxygen Dryer (HPOD) FY 2023 Trade Study and Market Survey(2024 International Conference on Environmnetal Systems, 2024-07-21) Rini,Emily; Barrett, Lawrence; Sweterlitsch, Jeffrey J.Item Modeling of Gateway Environment Control and Life Support Systems as a Means to Investigate the Subsystem and Integrated Architecture Performance(2023 International Conference on Environmental Systems, 2023-07-16) Barrett, Lawrence; Sturtz, Rachel; Hutchinson, MadelynAs human spaceflight evolves and develops, the technology the crew relies on for life support must become more advanced than at any point in NASA's history. Nowhere is this more apparent than the Gateway, where lessons learned from ISS are being applied in the design and production. Some of these technological improvements are proven in flight configuration, or have a heritage of proven flight hardware, but many are of a lower technology readiness level. Due to the unpredictable nature of the metabolic byproducts (CO2, H2O, and heat), even proven technologies can fail to meet requirements for crew safety. Detailed modeling of individual components excels in proving component level requirements are met, but fails to verify system or architecture level requirements. This paper expounds upon an effort to take a number of detailed component level models of the Gateway ECLSS and integrate them into a larger architecture model known as the Gateway Integrated ECLSS Model (GIEM). The GIEM is then used to study how the subsystems work synergistically to meet environmental requirements, as well as investigate how changes at the component level effect the Gateway stack as a whole.Item A Study of the Kinetics of the CO Oxidation Catalyst in a Human Spaceflight Fire Cartridges as a Method to Understand and Predict Performance(2023 International Conference on Environmental Systems, 2023-07-16) Barrett, Lawrence; Korona, Adam; Rabel, Emily; Muko, Cristina; Beck, Steven; Hudson, EdgarFire Cartridges (FC) are an integral part of fire response on ISS, Orion and Gateway. When a pair of FCs are integrated with an Emergency Mask, they can be used to provide safe breathing air on these vehicles in a post-fire environment. The FCs have two primary mechanisms for removing contaminants from the air, an activated carbon (AC) bed which adsorbs the majority of fire byproducts, and a catalyst bed consisting of gold nanoparticles supported on iron oxide which oxidized CO to CO2 under near ambient conditions. While the FC catalyst has proven its ability to convert CO under relevant conditions, this paper attempts to address the apparent inconsistent performance of the catalyst seen in testing. Numerous variables effect the performance of the catalyst, including but not limited to: reaction environment, reactant gas composition, inert gas composition, catalyst age, and catalyst lot. This paper discusses the importance of these variables and attempts a fundamental mechanistic explanation for the effects of each variable. The fundamental mechanisms are then used to establish the magnitude of expected performance variability, which were validated against real test data of flight quality FCs.Item Update of the Ground-Based Liquid Amine Horizontal Contactor Test System(2023 International Conference on Environmental Systems, 2023-07-16) Costa, Tiago; Chu, Lisa; Belancik, Grace; Samson, Jason; Barrett, LawrenceAs NASA continues to pursue longer durations of crewed space flight missions, the importance of a robust carbon-capture system is becoming more evident. Currently, NASA relies on a packed bed of zeolite pellets to remove carbon dioxide from the International Space Station cabin air. While this is a proven technique, NASA and the Environmental and Life Support System community are continuously looking for alternatives that are lighter, take up less volume, draw less power, and are more reliable. One method being investigated is a system using a liquid amine to absorb carbon dioxide from the cabin air stream. Because the liquid must be in contact with cabin air in a microgravity environment, possible exposure to crew must be mitigated. This can be achieved with the use of V-shaped channels which use capillary action to keep the liquid contained within the channel. Since amount of CO2 removed is a function of sorbent surface area, the contactor liquid surface area will need to be designed and sized to account for the CO2 removal requirements per crew member. Ground-based test data to date has evaluated vertical contactor channels, which have a delta from microgravity performance due to the gravity effect in the vertical orientation. Therefore, a new horizontal channel contactor design, operable in any gravity or absence thereof, was built and tested. An analytical model of this new design was also developed in Aspen Custom Modeler. Both tools will be used to further understand the fluid characteristics, CO2 absorption, and scale up requirements for the overall liquid amines CO2 removal system.