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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Impact of Biofilms on the Design and Operation of ISS Life Support Systems

Biofilm growth has been an ongoing issue for US and Russian water systems on the International Space Station, and is a critical issue for exploration missions in which water systems must be designed to accommodate dormant periods of up to one year. On ISS, Russian condensate plumbing has previously clogged with biomass, requiring condensate plumbing to now be regularly replaced. In the US Segment, the release of biofilm from the Water Processor waste tank has clogged a solenoid valve downstream of the tank, resulting in the costly replacement of the inlet separator and process pump. Subsequent management of the biofilm in the waste tank involves restrictions on tank cycles to limit the release of biomass and an additional filter to protect downstream components. Engineering personnel are now evaluating concepts to better manage the biomass, including the use of microbial inhibitors and UV LEDs. Though current ISS operations could likely be sustained for the duration of ISS, a more effective method must be developed for managing the growth and release of biomass in future exploration vehicles. Biofilm management for future missions is complicated by the requirement to accommodate extended periods of dormancy during which time the water system will be stagnant. The current approach under consideration is to flush the waste water with product water to reduce the organic content followed by use of microbial inhibitors or UV. However, other concepts may also be developed based on ongoing research.

Carter, Donald Layne↗
NASA NTRS2018

The Role of System Compatibility and Cabin Environmental Impact Assessment in Environmental Control and Life Support System Design and Flight Operations

Contamination of a crewed spacecraft's cabin environment leading to ECLS system functional capability and operational margin degradation or loss can have an adverse effect on NASA's space exploration mission figures of merit-safety, mission success, effectiveness, and affordability. Experience gained during the International Space Station program has shown the vital role that evaluating ECLS system compatibility and cabin environmental impact serves as a passive trace contaminant control tool which can provide guidance to crewed spacecraft system and payload developers relative to designing for minimum risk. As well, such evaluations can aid in guiding containment design, developing flight rules and procedures suitable for protecting the ECLS system and cabin environment, and defining contamination event remediation approaches. The approach to evaluating ECLS system compatibility and cabin environmental impact developed during the ISS program is presented and its role in future exploration spacecraft design is discussed.

Peery, Jay L.↗
NASA NTRS2020

Modeling Electrolytic Conversion of Metabolic CO2 and Optimizing a Macrofluidic Electrochemical Reactor for Advanced Closed Loop Life Support Systems

The International Space Station (ISS) is currently equipped with a complex, heavy, and power consuming system that recovers approximately 50% of O2 from metabolic CO2. Future long duration missions will require a sustainable and highly efficient system capable of yielding a minimum of 75% O2 recovery. A Macrofluidic Electrochemical Reactor (MFECR) technology development effort is currently underway at NASA Marshall Space Flight Center (MSFC) to significantly increase current O2 recovery efficiency and reduce complexity of the system. This paper presents a comprehensive multi-physic 3D model developed at MSFC on CO2 conversion to O2 and C2H4 at standard conditions via MFECR. The 3D spatial domain of the model is a replica of the actual MFECR’s 3D drawing generated for the MFECR fabrication and operated to recover O2 from CO2 yielding C2H4 as byproduct. Electrochemical (EC) physics that includes EC multicomponent reaction mechanisms, mass transport, and current density distributions is coupled in the model with all the other physics phenomena involved in the process, such as free and porous fluid flow, multicomponent mass transfer, heat transfer, and DC electrical current generation along with Joule heating effect. The authors plan to use experimental results to validate this comprehensive and rigorous model and build a reliable simulator that will not only assist the authors on the MFECR design but also optimize its operation.

Dominguez, Jesus A.↗
NASA NTRSDate not supplied

Modeling Electrolytic O2 Recovery from Metabolic CO2 for Advanced Closed Loop Life Support Systems in Extraterrestrial Human Missions

The International Space Station (ISS) is currently equipped with a complex, heavy, and power consuming system that recovers approximately 50% of O2 from metabolic CO2. Future long duration human missions to the Moon and Mars will necessitate a sustainable and highly efficient metabolic oxygen recovery system capable of yielding a minimum of 75% O2 recovery. A Macrofluidic Electrochemical Reactor (MFECR) technology development effort is currently underway at NASA Marshall Space Flight Center (MSFC) to significantly increase current metabolic O2 recovery efficiency, expand mission sustainability, and reduce complexity of the system. The novel design combines CO2 conversion to O2 along with C2H4 as byproduct and water electrolysis (currently conducted in two separate units) into a single compact unit that runs at standard conditions and is theoretically capable of generating O2 with a theoretical maximum metabolic CO2 conversion of 73% while consuming less than metabolic water. This paper presents a comprehensive multi-physic 3D model developed at MSFC on CO2 conversion to O2 and C2H4 at standard conditions via MFECR. The 3D spatial domain of the model is a replica of the actual MFECR’s 3D drawing generated for the MFECR fabrication and operated to recover O2 from CO2 yielding C2H4 as byproduct. Electrochemical (EC) physics that includes EC multicomponent reaction mechanisms, mass transport, and electrical current density distributions is coupled in the model with all the other physics phenomena involved in the MFECR’s process, such as two-phase flow, free and porous fluid regimes, multicomponent mass transfer, heat transfer, and DC electrical current generation along with Joule heating effect. The EC reaction sections of the MFECR consists of two porous gas diffusion electrodes (GDE) and an electrolyte serpentine channel sandwiched in the middle. The CO2 feeds the cathode serpentine channel and part of the O2 product is fed back to the anode serpentine chamber. An alkaline solution feeds the electrolyte serpentine chamber wetting the GDEs of both, the anode and cathode allowing the OH- ionic transport between them. The EC reactions in the cathode’s GDE yield C2H4 from CO2 and H2 from water while the EC reaction in the anode’s GDE yields O2. The authors will present in this paper the validation of the model using experimental data and the utilization of the validated model in building a reliable simulator that will not only assist the authors on the MFECR design but also the optimization of its operation in the ISS and future spatial human missions.

Jesus A Dominguez↗
NASA NTRSDate not supplied

Development of Electrolytic Oxygen Recovery System for Advanced Life Support

The oxygen (O2) recovery system for the International Space Station (ISS) can recover approximately 50 percent of O2 from metabolic carbon dioxide (CO2). Increasing the O2 recovery rate and closing the open loop for future long duration crewed missions in space beyond Low Earth Orbit (LEO) is essential. There are several developmental efforts underway to increase the recovery rate. However, most of these technologies result in a complex, heavy, and power consuming system. The desired exploration O2 recovery system would be reliable and efficient with maximum O2 recovery. Marshall Space Flight Center (MSFC) is currently investigating an electrolytic O2 recovery approach that will increase the O2 recovery to greater than 70 percent as well as lowering the complexity, mass, and power consumption than most other technologies currently under development. The electrolytic O2 recovery system consists of a Microfluidic Electrochemical Reactor (MFECR) that is based on the electrochemical reduction of CO2 to O2 and ethylene (C2H4) using water (H2O) as precursor and operates at standard condition with a theoretical recovery rate of 73 percent. In 2016, NASA’s Game Changing Development Program awarded the University of Texas Arlington (UTA) a grant to initiate the development of the MFECR. Since 2019, MSFC and UTA have been collaborating with the current goals of increasing the O2 recovery efficiency, advancing the technology readiness to a Technology Readiness Level (TRL) 4, and maturing the system to process CO2 of one crew-member. Based on the results from UTA’s initial efforts, the following were identified as key areas of improvement in order to maximize O2 recovery for the system: further development of the anode material and cathode catalyst, model-based cell design optimization, and the addition of a separation system and fuel cell. This paper will present the current developmental efforts of the electrolytic system including MFECR design and overall system enhancements as well as results from single cell stack testing.

Brittany R Brown↗
NASA NTRSDate not supplied

Going Beyond Reliability to Robustness and Resilience in Space Life Support Systems

The words reliability, robustness, and resilience are often used interchangeably to describe tough and dependable systems but the distinctions between them suggest how to design more serviceable space systems. Reliability is simply the quality of consistently performing well. A system that dependably meets its design requirements in the specified environment is reliable. The designers may not consider themselves responsible for failures under unanticipated conditions. Robustness is the capability of performing without failure under a wide range of conditions, which can go beyond the expected range to include possible off-nominal conditions. Resilience is the ability to recover from or adapt to unanticipated damaging events, such as failures, accidents, external disruptions, and repurposing. Such changes can invalidate the usual operating assumptions and cause system failure. Reliability, robustness, and resilience describe dependable performance under increasingly difficult conditions, first the specified environment, then a wider possible environment, and finally unanticipated damaging conditions. These three qualities are increasingly desirable and increasingly difficult to achieve. Engineering for resilience would design systems that can ignore or repair failures, survive accidents, and recover from unanticipated disruptions. Increasing the resilience of space systems would greatly increase space crew safety. Improving reliability and robustness requires dealing with known problems, but improving resilience requires implementing a general approach to reducing the impact of unknown future events. The need for robustness and resilience has been stated for decades but little has been done. Systems designers often assume that they understand everything they need to know. The potential failures caused by changes, failures, accidents, unknown environments, and unknown unknowns can be ignored. Such overconfidence can lead to neglect of reliability, robustness, and resilience.

Harry W. Jones↗