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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Performance Characterization and Simulation of Amine-Based Vacuum Swing Sorption Units for Spacesuit Carbon Dioxide and Humidity Control

Controlling carbon dioxide (CO2) and water (H2O) vapor concentrations in a space suit is critical to ensuring an astronauts safety, comfort, and capability to perform extra-vehicular activity (EVA) tasks. Historically, this has been accomplished using lithium hydroxide (LiOH) and metal oxide (MetOx) canisters. Lithium hydroxide is a consumable material that requires priming with water before it becomes effective at removing carbon dioxide. MetOx is regenerable through a power-intensive thermal cycle but is significantly heavier on a volume basis than LiOH. As an alternative, amine-based vacuum swing beds are under aggressive development for EVA applications. The vacuum swing units control atmospheric concentrations of both CO2 and H2O through fully-regenerative process. The current concept, referred to as the rapid cycle amine (RCA), has resulted in numerous laboratory prototypes. Performance of these prototypes have been assessed experimentally and documented in previous reports. To support developmental e orts, a first principles model has also been established for the vacuum swing sorption technology. For the first time in several decades, a major re-design of Portable Life Support System (PLSS) for the extra-vehicular mobility unit (EMU) is underway. NASA at Johnson Space Center built and tested an integrated PLSS test bed of all subsystems under a variety of simulated EVA conditions of which the RCA prototype played a significant role. The efforts documented herein summarize RCA test performance and simulation results for single and variable metabolic rate experiments in an integrated context. In addition, a variety of off-nominal tests were performed to assess the capability of the RCA to function under challenging circumstances. Tests included high water production experiments, degraded vacuum regeneration, and deliberate valve/power failure and recovery.

Swickrath, Michael J.↗
NASA NTRS2001

Buffer Gas Acquisition and Storage

The acquisition and storage of buffer gases (primarily argon and nitrogen) from the Mars atmosphere provides a valuable resource for blanketing and pressurizing fuel tanks and as a buffer gas for breathing air for manned missions. During the acquisition of carbon dioxide (CO2), whether by sorption bed or cryo-freezer, the accompanying buffer gases build up in the carbon dioxide acquisition system, reduce the flow of CO2 to the bed, and lower system efficiency. It is this build up of buffer gases that provide a convenient source, which must be removed, for efficient capture Of CO2 Removal of this buffer gas barrier greatly improves the charging rate of the CO2 acquisition bed and, thereby, maintains the fuel production rates required for a successful mission. Consequently, the acquisition, purification, and storage of these buffer gases are important goals of ISRU plans. Purity of the buffer gases is a concern e.g., if the CO, freezer operates at 140 K, the composition of the inert gas would be approximately 21 percent CO2, 50 percent nitrogen, and 29 percent argon. Although there are several approaches that could be used, this effort focused on a hollow-fiber membrane (HFM) separation method. This study measured the permeation rates of CO2, nitrogen (ND, and argon (Ar) through a multiple-membrane system and the individual membranes from room temperature to 193K and 10 kpa to 300 kPa. Concentrations were measured with a gas chromatograph that used a thermoconductivity (TCD) detector with helium (He) as the carrier gas. The general trend as the temperature was lowered was for the membranes to become more selective, In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar.

Parrish, Clyde F.↗
NASA NTRS1974

Interaction of gases with ablative composites. I - Ar, CO2, and N2

The sorption of argon, carbon dioxide, and nitrogen on two heat shield composites (SLA-561 and SLA-561V) and on the SLA components was measured over the pressure range of 0.001 to 760 torr and in the temperature range of 30 to 50 C. The sorption of the gases by both the composites and the components varied directly with pressure. The sorption of CO2 by the phenolic spheres and the silicone elastomer and of Ar by the silicone elastomer varied inversely with temperature. The mechanism involved in the gas sorption was primarily absorption.

King, C. A.↗
NASA NTRS2014

Carbon-Based Regenerable Sorbents for the Combined Carbon Dioxide and Ammonia Removal for the Primary Life Support System (PLSS)

Results are presented on the development of reversible sorbents for the combined carbon dioxide and trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs). Since ammonia is the most important TC to be captured, data on TC sorption presented in this paper are limited to ammonia, with results relevant to other TCs to be reported at a later time. The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Furthermore, the current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. The objective of this study was to demonstrate the feasibility of using carbon sorbents for the reversible, concurrent sorption of carbon dioxide and ammonia. Several carbon sorbents were fabricated and tested, and multiple adsorption/vacuum-regeneration cycles were demonstrated at room temperature, and also a carbon surface conditioning technique that enhances the combined carbon dioxide and ammonia sorption without impairing sorbent regeneration.

Wojtowicz, Marek A.↗
NASA NTRSDate not supplied

Novel Aprotic Heterocyclic Anion-based Ionic Liquids for Carbon Dioxide Capture

Ionic liquids (ILs), or organic salts with melting points at or below room temperature are an incredibly versatile class of materials with many possible applications for NASA’s exploration needs. In particular, appropriately designed ILs can have a high affinity for absorbing carbon dioxide, making them excellent candidates for use as liquid sorbents in cabin air revitalization systems. Unfortunately, many of these ILs have high viscosity, which is only exacerbated by carbon dioxide uptake. High viscosity limits the rate of carbon dioxide uptake. A new class of IL sorbent containing aprotic heterocyclic anions (AHA) has been shown to offer excellent carbon dioxide uptake without a corresponding increase in viscosity. However, there is a paucity of sorption data for these AHA ILs at low partial pressures of carbon dioxide. This paper reports on the characterization of sorption behavior for AHA ILs previously reported in the literature at low concentrations of carbon dioxide and the synthesis and characterization of new, water miscible AHA ILs. Characterization of the new ILs includes measurement of density, viscosity, thermal stability, carbon dioxide capacity, carbon dioxide absorption kinetics, and water-IL vapor liquid equilibrium. Overall, these news ILs are promising alternatives to many of the commonly used IL sorbents.

Eric Townsend Fox↗
NASA NTRS2015

Adsorption of Carbon Dioxide, Ammonia, Formaldehyde, and Water Vapor on Regenerable Carbon Sorbents

Results are presented on the development of reversible sorbents for the combined carbon dioxide, moisture, and trace‐contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long‐term objective is to replace the above three modules with a single one. Furthermore, the current TC‐control technology involves the use of a packed bed of acid‐impregnated granular charcoal, which is nonregenerable, and the carbon‐based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. In this study, several carbon sorbents were fabricated and tested for simultaneous carbon dioxide, ammonia, formaldehyde, and water sorption. Multiple adsorption/vacuum‐regeneration cycles were demonstrated at room temperature, and also the enhancement of formaldehyde sorption by the presence of ammonia in the gas mixture.

Wojtowicz, Marek A.↗
NASA NTRS2016

Long Duration Sorbent Testbed

The Long Duration Sorbent Testbed (LDST) is a flight experiment demonstration designed to expose current and future candidate carbon dioxide removal system sorbents to an actual crewed space cabin environment to assess and compare sorption working capacity degradation resulting from long term operation. An analysis of sorbent materials returned to Earth after approximately one year of operation in the International Space Station's (ISS) Carbon Dioxide Removal Assembly (CDRA) indicated as much as a 70% loss of working capacity of the silica gel desiccant material at the extreme system inlet location, with a gradient of capacity loss down the bed. The primary science objective is to assess the degradation of potential sorbents for exploration class missions and ISS upgrades when operated in a true crewed space cabin environment. A secondary objective is to compare degradation of flight test to a ground test unit with contaminant dosing to determine applicability of ground testing.

Howard, David F.↗
NASA NTRS2016

Long Duration Sorbent Testbed

The LDST is a flight experiment demonstration designed to expose current and future candidate carbon dioxide removal system sorbents to an actual crewed space cabin environment to assess and compare sorption working capacity degradation resulting from long term operation. An analysis of sorbent materials returned to earth after approximately one year of operation in the International Space Station's (ISS) Carbon Dioxide Removal Assembly (CDRA) indicated as much as a 70% loss of working capacity of the silica gel desiccant material at the extreme system inlet location, with a gradient of capacity loss down the bed. The primary science objective is to assess the degradation of potential sorbents for exploration class missions and ISS upgrades when operated in a true crewed space cabin environment. A secondary objective is to compare degradation of flight test to a ground test unit with contaminant dosing to determine applicability of ground testing.

Knox, James↗
NASA NTRS2013

Demonstration of Critical Systems for Propellant Production on Mars for Science and Exploration Missions

A Mars hopper has been proposed as a Mars mobility concept that will also demonstrate and advance in-situ resource utilization. The components needed in a Mars propellant production plant have been developed to various levels of technology maturity, but there is little experience with the systems in a Mars environment. Two systems for the acquisition and compression of the thin carbon dioxide atmosphere were designed, assembled, and tested in a Mars environment chamber. A microchannel sorption pump system was able to raise the pressure from 7 Torr to 450 Torr or from 12 Torr to over 700 Torr in two stages. This data now provides information needed to make additional improvements in the sorption pump technology to increase performance, although a system-level analysis might prove that some amount of pre- or post-compression may be a preferred solution. A mini cryofreezer system was also evaluated as an alternative method for carbon dioxide acquisition and compression. Finally, an electrolysis system was tested and successfully demonstrated start-up operation and thermal stability of all components during long-term operation in the chamber.

Linne, Diane L.↗
NASA NTRS1991

Physical/chemical closed-loop water-recycling

Water needs, water sources, and means for recycling water are examined in terms appropriate to the water quality requirements of a small crew and spacecraft intended for long duration exploration missions. Inorganic, organic, and biological hazards are estimated for waste water sources. Sensitivities to these hazards for human uses are estimated. The water recycling processes considered are humidity condensation, carbon dioxide reduction, waste oxidation, distillation, reverse osmosis, pervaporation, electrodialysis, ion exchange, carbon sorption, and electrochemical oxidation. Limitations and applications of these processes are evaluated in terms of water quality objectives. Computerized simulation of some of these chemical processes is examined. Recommendations are made for development of new water recycling technology and improvement of existing technology for near term application to life support systems for humans in space. The technological developments are equally applicable to water needs on Earth, in regions where extensive water recycling is needed or where advanced water treatment is essential to meet EPA health standards.

Herrmann, Cal C.↗
NASA NTRS1990

Physical/chemical closed-loop water-recycling for long-duration missions

Water needs, water sources, and means for recycling water are examined in terms appropriate to the water quality requirements of a small crew and spacecraft intended for long duration exploration missions. Inorganic, organic, and biological hazards are estimated for waste water sources. Sensitivities to these hazards for human uses are estimated. The water recycling processes considered are humidity condensation, carbon dioxide reduction, waste oxidation, distillation, reverse osmosis, pervaporation, electrodialysis, ion exchange, carbon sorption, and electrochemical oxidation. Limitations and applications of these processes are evaluated in terms of water quality objectives. Computerized simulation of some of these chemical processes is examined. Recommendations are made for development of new water recycling technology and improvement of existing technology for near term application to life support systems for humans in space. The technological developments are equally applicable to water needs on earth, in regions where extensive water ecycling is needed or where advanced water treatment is essential to meet EPA health standards.

Herrmann, Cal C.↗
NASA NTRS1992

Use of sorption technology for treatment of humidity condensate for potable water

This research focused on the testing of the original potable water processor aboard Space Station Freedom that was to produce potable water from the humidity condensate and additional water generated by carbon dioxide reduction. Humidity condensate was simulated by an influent water model 'Ersatz'. The humidity condensate was treated with multifiltration (MF) beds that consisted of a train of sorption beds (referred to as 'Unibed') designed to remove specific contaminants. For the complete simulated MF system runs tested for 100 bed volumes (BV) (volume processed/total column volume), 0.6 percent of the TOC was removed by the SAC/IRN 77 (Strong Acid Cation exchange resin), 39.6 percent of the total organic carbon (TOC) was removed by the WBA/IRA 68 (Weak Base Anion exchange resin), 13.2 percent of the TOC was removed by activated carbon adsorption (580-26), and the remaining sorbent media acted as polishing units to remove an additional 1.6 percent of the TOC at steady state. At steady state, 45 percent of the influent TOC passed through the MF bed.

Ajjarapu, Sundara R. M.↗
NASA NTRS2015

Adsorption of Ammonia on Regenerable Carbon Sorbents

Results are presented on the development of reversible sorbents for the combined carbon dioxide, moisture, and trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Data on sorption and desorption of ammonia, which is a major TC of concern, are presented in this paper. The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. In this study, several carbon sorbents were fabricated and tested for ammonia sorption. Ammonia-sorption capacity was related to carbon pore structure characteristics, and the temperature of oxidative carbon-surface treatment was optimized for enhanced ammonia-sorption performance.

Wójtowicz, Marek A.↗
NASA NTRS2000

Separation of Carbon Monoxide and Carbon Dioxide for Mars ISRU-Concepts

Solid oxide electrolyzers, such as electrolysis cells utilizing yttria-stabilized zirconia, can produce oxygen from Mars atmospheric carbon dioxide and reject carbon monoxide and unreacted carbon dioxide in a separate stream. The oxygen-production process has been shown to be far more efficient if the high-pressure, unreacted carbon dioxide can be separated and recycled back into the feed stream. Additionally, the mass of the adsorption compressor can be reduced. Also, the carbon monoxide by-product is a valuable fuel for space exploration and habitation, with applications from fuel cells to production of hydrocarbons and plastics. In our research, we will design, construct, and test an innovative, robust, low mass, low power separation device that can recover carbon dioxide and carbon monoxide for Mars ISRU. Such fundamental process technology, involving gas-solid phase separation in a reduced gravitational environment, will help to enable Human Exploration and Development of Space. The separation device will be scaled to operate with a CO2 sorption compressor and a zirconia electrolysis device built at the NASA Ames Research Center and the University of Arizona, respectively. In our research, we will design, construct, and test an innovative, robust, low mass, low power separation device that can recover carbon dioxide and carbon monoxide for Mars ISRU, Such fundamental process technology, involving gas-solid phase separation in a reduced gravitational environment, will help to enable Human Exploration and Development of Space. The separation device will be scaled to operate with a CO2 sorption compressor and a zirconia electrolysis device built at the NASA Ames Research Center and the University of Arizona, The separation device will be scaled to operate with a CO2 sorption compressor and a zirconia electrolysis device built at the NASA Ames Research Center and the University of Arizona, Research needs for the design shown are as follows: (1) The best adsorbent for the process must be determined. (2) Adsorption isotherms must be measured, both for pure components and mixtures. (3) Mathematical modeling must be performed to provide a solid framework for design. (4) The separation system must be constructed and tested. (5) System integration must be studied.

LeVan, M. Douglas↗
NASA NTRS1999

Experimental and Numerical Investigation of Adsorption/Desorption in Packed Sorption Beds Under Ideal and Non-Ideal Flows

The importance of the wall effect on packed beds in the adsorption and desorption of carbon dioxide, nitrogen, and water on molecular sieve 5A of 0.127 cm in radius is examined experimentally and with one-dimensional computer simulations. Experimental results are presented for a 22.5-cm long by 4.5-cm diameter cylindrical column with concentration measurements taken at various radial locations. The set of partial differential equations are solved using finite differences and Newman's method. Comparison of test data with the axial-dispersed, non-isothermal, linear driving force model suggests that a two-dimensional model (submitted to Separation Science and Technology) is required for accurate simulation of the average column breakthrough concentration. Additional comparisons of test data with the model provided information on the interactive effects of carrier gas coadsorption with CO2, as well as CO2-H2O interactions.

Mohamadinejad, H.↗
NASA NTRS2009

Engineered Structured Sorbents for the Adsorption of Carbon Dioxide and Water Vapor from Manned Spacecraft Atmospheres: Applications and Testing 2008/2009

This paper describes efforts to improve on typical packed beds of sorbent pellets by making use of structured sorbents and alternate bed configurations to improve system efficiency and reliability. The benefits of the alternate configurations include increased structural stability gained by eliminating clay bound zeolite pellets that tend to fluidize and erode, and better thermal control during sorption to increase process efficiency. Test results that demonstrate such improvements are described and presented.

Howard, David F.↗