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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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136 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Indicator Devices for Detection of Trace Gaseous Hydrazines

The relatively recent decrease in the acceptable time-weighted-average for hydrazines from 100 parts-per-billion (ppb) to 10 ppb rendered many trace hydrazine detectors either insensitive or inaccurate. Development of a rapid detection method for hydrazines at the new 10-ppb concentration was necessary so that test area personnel could reliably assess airborne hydrazines concentrations of a potentially contaminated area prior to entry. The reduction of Au(III) to Au(0) by hydrazines is a well characterized reaction and application of the corresponding yellow to purple color change was selected as a potentially useful means for detection of trace hydrazines in air. Tests with small quantities of KAuCl4 deposited on a variety of substrates were conducted using verified sources of 1,1-dimethylhydrazine, methylhydrazine, and hydrazine at approximately 10 ppb in air. Substrates tested were glass fiber filter paper, glass beads, anion exchange resin (AuCl4- form), and diatomaceous earth. The most successful of these substrates were glass fiber filter paper and diatomaceous earth. The KAuC14 impregnated glass fiber filter paper appeared to be somewhat light sensitive so further tests were conducted using the diatomaceous earth substrate. KAuCl4 concentration, substrate particle size, and sampler configuration were evaluated. Based on these tests, the device selected for further evaluation was a 5mm OD by 50mm glass tube containing 0.02-0.03g of 45/60 mesh diatomaceous earth coated with 2 percent KAuCl4. When connected to a sampling pump, response of the device to changes in relative humidity, ambient light, and high levels of other fluids, which might also be found in a propellant test area, was evaluated. False positive responses were not detected for exposures to relative humidity changes from 10 to 80 percent, sunlight for greater than 10 minutes, or percent levels of ammonia, isopropyl alcohol, nitrogen dioxide, and hydrogen. In addition, body emissions did not produce a false positive response in view of potential application for use inside protective clothing. The device was shown to reliably detect less than 10 ppb of the hydrazines tested using a 10 to 20L sample followed by a 2 to 5 minute color development time. Some field tests were conducted in parallel with conventional acidic firebrick sorbent tubes. There was generally very good agreement between the devices and firebrick sorbent tubes when greater than 10 ppb of a hydrazine was present.

Dee, Lou A.↗
DOE OSTI2023

Organic Vacuum Pump Fluids for the Vacuum Pumping of Fusion Power Plants

Vacuum pumps are the heart of the fusion fuel cycle, but most currently proposed pumping technologies are not capable of handling the required flow rates and vacuum pressures. Oil-containing vacuum pumps can readily meet the flow requirements, but vacuum fluids will degrade in fusion-relevant environments due to contact with tritium and exposure to high-energy radiation. Here, in this study, we describe a methodology to screen vacuum fluid candidates and purify these candidate fluids post oxidation, post exposure to deuterium, and post exposure to gamma radiation (<7.5 MGy) to simulate a process in which vacuum fluids can be recovered and regenerated during the fusion fuel cycle. A series of oils, including a highly purified mineral oil, phenyl silicone oil, and a polyphenyl ether, are shown to be suitable candidates for vacuum pumping. Additionally, we describe a simple purification methodology to remove oxidized functionalities and the associated isotopologues induced by contact with deuterium from the candidate vacuum fluids This purification methodology can also be applied to radiological damage with moderate effect. Finally, we demonstrate that the sorbents can be regenerated through electromagnetic microwave digestion.

oxidation↗
DOE OSTI2025

Iodine Capture Studies of Copper- and Bismuth-Based Sorbents

The release of radioiodine, one of several radionuclides of concern when recycling used nuclear fuel (UNF), is an important consideration in the fuel cycle. In this study, two sorbent materials, Cu 0 -polyacrylonitrile (PAN) and Bi 0 -PAN, were tested as solid sorbent candidates for iodine capture. Experiments using a thin bed of sorbent material were exposed to vaporized iodine for over 300 hours (~2 weeks) under varied conditions in a dynamic flow environment. The overall performance was monitored in real-time using thermogravimetric analysis, and the materials were subsequently characterized for surface and bulk analysis using scanning electron microscopy – energy-dispersive spectroscopy (SEM-EDS) and powder x-ray diffraction (pXRD), respectively. Iodine (in the form of I 2 ) is expected to be released primarily in the dissolver off-gas (DOG) stream; therefore, this study demonstrates the effects of elemental iodine (I 2 ), water vapor (H 2 O), and nitrogen dioxide (NO 2 ). When exposed to ‘ideal’ conditions (in which I 2 is carried by dry air), Cu 0 -PAN and Bi 0 -PAN behave differently, with TGA analysis indicating that Cu 0 sorption performance is higher than that of Bi 0 , as evidenced by a larger mass change. Under ‘harsh’ conditions—such as a gaseous feed containing I 2 , H 2 O, and NO 2 vapors carried by air,—iodine capture performance for both Cu 0 - and Bi 0 -PAN are affected. SEM-EDS and pXRD analysis of these materials is discussed herein.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Data-Driven Discovery of Linear Molecular Probes with Optimal Selective Affinity for PFAS in Water

Approaches to tackle the wide and growing variety of highly persistent per- and polyfluoroalkyl substances (PFAS) are of pressing global need because of their detrimental human health effects, such as cancer, birth defects, and hormone imbalance. Sensitive, selective, and easy-to-use real-time sensors to monitor and detect PFAS and sorbents to extract them are critical to meeting government-mandated environmental concentrations. In this work, we combine all-atom molecular dynamics simulations, enhanced sampling, deep representational learning, and Bayesian optimization to perform high-throughput virtual screening for highly sensitive and selective molecular probes. Our molecular design space consists of 3850 linear hydrocarbon chains with varying degrees of halogenation with and without amine- and phosphine-based headgroups. By employing a data-driven search process, we efficiently explore the molecular design space to optimize the sensitivity to perfluorooctanesulfonic acid (PFOS) as a prototypical PFAS analyte and selectivity relative to a sodium dodecyl sulfate (SDS) interferent. We calculate 504 Gibbs free energies of probe-analyte and probe-interferent interactions and identify probes with PFOS association free energies of up to (-ΔG PFOS ) = 9.8 ± 0.2 kJ/mol and selectivities relative to SDS of (-ΔΔG PFOS–SDS ) = 3.1 ± 1.5 kJ/mol. A C 11 Br 23 P(CH 3 ) 2 probe containing 11 backbone brominated carbons and a tertiary phosphine headgroup possesses the most sensitive binding constant to PFOS within the defined search space of K b PFOS = 177.4 ± 12.7, and a semibrominated probe C 5 H 11 C 7 Br 14 N(CH 3 ) 2 containing 12 backbone carbons and a tertiary amine headgroup possesses the highest selectivity relative to SDS of K b PFOS /K b SDS = 4.6 ± 1.7. A retrospective analysis of our data to extract interpretable design rules reveals that the sensitivity of linear hydrogenated probes increases by approximately 1 kJ/mol per C–C bond. The addition or removal of halogen atoms and amine or phosphine headgroups produces nonmonotonic changes in both sensitivity and selectivity with changes to the sensitivity of up to 2.5 kJ/mol. Finally, this work places empirical limitations on the performance of a wide range of linear probes for PFOS detection and offers a generic strategy for high-throughput computational screening to promote selective and sensitive binding.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2014

Evaluating the Adsorptive Capabilites of Chemsorb 1000 and Chemsorb 1425

The removal of trace contaminants from spacecraft cabin air is necessary for crew health and comfort during long duration space exploration missions. The air revitalization technologies used in these future exploration missions will evolve from current ISS ISS State-of-Art (SOA) and is being designed and tested by the Advanced Exploration Systems (AES) Program's Atmosphere Resource Recovery and Environmental Monitoring (ARREM) project. The ARREM project is working to mature optimum atmosphere revitalization and environmental monitoring system architectures to enable exploration beyond Lower Earth Orbit (LEO). The Air Revitalization Lab at KSC is one of six NASA field centers participating in the ARREM that specializes in adsorbent and catalyst characterization with simulated spacecraft gas streams using combinations of pressure, O2 partial pressure, CO2 partial pressure, and humidity that are representative of a range of anticipated cabin atmospheric conditions and loads. On board ISS, the Trace Contaminant Control Subassembly (TCCS) provides active control of trace contaminants from the cabin atmosphere utilizing physical adsorption, thermal catalytic oxidation, and chemical adsorption processes. High molecular weight contaminants and ammonia (NH3) are removed a granular activated carbon treated with approx. 10% by weight phosphoric acid (H3PO4) (B-S Type 3032 4×6 mesh), which is expendable and is periodically refurbished. The Type 3032 granular activated carbon bed is no longer commercially available and therefore it is important to characterize the efficiency and capacity of commercially available NH3 sorbents. This paper describes the characterization of two Molecular Products LTD activated carbons: Chemsorb 1000 and Chemsorb 1425. Untreated activated carbons (e.g. Chemsorb 1000) remove contaminants by physisorption, which concentrates the contaminant within the pores of the carbon while letting air to pass through the sorbent4. Low molecular weight or polar gases (e.g. HCl, SO2, formaldehyde, and NH3) are not removed by physisorption and typically require chemisorption for removal. Treated activated carbons (e.g. Chemsorb 1425) are impregnated with a a chemical agent (e.g. phosphoric acid) that reacts with those gases, converting them to solids or salts within the carbon and removes them from the air stream. This process occurs via neutralization or catalysis reactions and adsorption capacity is exhaustedwhen the available impregnated chemicals are consumed. Moisture affects removal performance since adsorption sites within the pores are filled with water. The performance of impregnated carbons may be enhanced by moisture content because the mechanisms of contaminant removal are chemical reactions that occur in reagents contained within the pores. The adsorptive capacity data (mol/kg) of Chemsorb 1000 and 1425 for gas mixtures (ethanol, acetone, toluene, acetaldehyde, dichloromethane, and xylene) was measured with 40% relative humidity at 23 deg C air temperature. The adsorptive capacity data (mol/kg) of Chemsorb 1425 was measured using NH3 gas streams.

adsorptive capacities↗
DOE OSTI2021

Modulation of CO 2 adsorption in novel pillar-layered MOFs based on carboxylate–pyrazole flexible linker

Metal–organic frameworks (MOFs) have attracted significant attention as sorbents due to their high surface area, tunable pore volume and pore size, coordinatively unsaturated metal sites, and ability to install desired functional groups by post-synthetic modification. Herein, we report three new MOFs with pillar–paddlewheel structures that have been synthesized solvothermally from the mixture of the carboxylate–pyrazole flexible linker (H 2 L), 4,4-bipyridine (BPY)/triethylenediamine (DABCO), and Zn(II)/Cu(II) ions. The MOFs obtained, namely [Zn II (L)BPY], [Cu II (L)BPY], and [Cu II (L)DABCO], exhibit two-fold interpenetration and dinuclear paddle–wheel nodes. The Zn(II)/Cu(II) cations are coordinated by two equatorial L linkers that result in two-dimensional sheets which in turn are pillared by BPY or DABCO in the perpendicular direction to obtain a neutral three-dimensional framework that shows one-dimensional square channels. The three pillar-layered MOFs were characterized as microporous materials showing high crystalline stability after activation at 120 °C and CO 2 adsorption. All MOFs contain uncoordinated Lewis basic pyrazole nitrogen atoms in the framework which have an affinity toward CO 2 and hence could potentially serve as CO 2 adsorption material. The CO 2 uptake capacity was initially enhanced by replacing Zn with Cu and then replacing the pillar, going from BPY to DABCO. Overall, all the MOFs exhibit low isosteric heat (Q st ) of adsorption which signifies an advantage due to the energy required for the adsorption and regeneration processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Polydiallylammonium-Polysulfone Multiblock Copolymers for Moisture-Swing Direct Air Capture of Carbon Dioxide

Polysulfones are an important class of materials for a variety of applications due to their excellent strength and thermal stability. Quaternary ammonium polymers are also useful materials due to their ion exchange properties, and such materials with alkaline counterions have been used to capture carbon dioxide (CO 2 ) from ambient air through a moisture-driven mechanism. Herein, we design sulfone-based multiblock copolymers containing ammonium functionalities and demonstrate their potential for CO 2 capture. Specifically, a series of multiblock copolymers containing both polydiallyldimethylammonium (PDADMA) and polysulfone (PSf) blocks were synthesized. PSf blocks provide mechanical integrity, while the PDADMA blocks enable the direct air capture of CO 2 . Multiblock copolymers were synthesized at high yield, and PDADMA(OH)-PSf copolymer films with good flexibility and strength were formed with IECs of 424 μmol/g (17 mol % PDADMA(OH)), 1407 μmol/g (44 mol % PDADMA(OH)), and 1726 μmol/g (50 mol % PDADMA(OH)). Thermogravimetric analysis was used to determine that all films are thermally stable up to 345 °C. Differential scanning calorimetry revealed that the 17 and 44 mol % functionalized PDADMA(OH)-PSf multiblock copolymers showed one T g at 185 °C and 50 mol % PDADMA(OH)-PSf polymer showed a T g at 183 °C and a second T g at 16 °C. Atomic force microscopy showed that the multiblock polymers exhibit disordered phase separation. Furthermore, the copolymer materials displayed moisture-swing direct air capture of CO 2 , opening up pathways to utilize polymer architecture and chemistry to tailor the properties of promising sorbents.

42 ENGINEERING↗
DOE OSTI2023

Evaluation of Technologies for Destruction of LDR Organics in Hanford Tank Waste

Aqueous Hanford tank wastes contain soluble organics and some tanks contain small amounts (<100 mg/L) of organics that are regulated under the Land Disposal Restrictions (LDR) portions of the Resource Conservation and Recovery Act (RCRA). Most of these organics can be removed by evaporation, but some are not. Methods to destroy/remove organics that are regulated by the LDR section of the RCRA and that are not removed by evaporation may be needed if ambient temperature waste treatment processes are used to immobilize aqueous Hanford tank wastes. To identify viable and compatible organic removal or destruction pretreatment methods an evaluation was performed by a team of researchers. The team utilized a Systems Engineering Approach that examines all aspects of the technology, based on information available in the literature and the experience of the team members. That evaluation led to recommendations by the team to perform testing on technologies to determine efficacy in destroying organics in Hanford tank waste liquids. The primary technologies recommended are chemical oxidants, including permanganate, peroxymonosulfate or peroxydisulfate (PMS/PDS), hydrogen peroxide, and ozone. Ultraviolet light irradiation of the stream with a solid catalyst sorbent is also recommended for testing. A generalized description of the test program is also included.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

All-Inorganic Open-Framework Chalcogenides, A 3 Ga 5 S 9 · x H 2 O ( A = Rb and Cs), Exhibiting Ultrafast Uranyl Remediation and Illustrating a Novel Post-Synthetic Preparation of Open-Framework Oxychalcogenides

Fast and effective uranyl sequestration is of interest to the nuclear industry. Recently layered chalcogenide materials have demonstrated fast, selective, and efficient sorption properties towards uranyl cations and the development and investigation of new types of chalcogenide materials continues to be of interest and represents an intriguing option for uranyl remediation. Three new all-inorganic A 3 Ga 5 S 9 ·xH 2 O (A = Rb, Rb/Cs, and Cs) open-framework chalcogenides were obtained via an in-situ alkali carbonate to alkali sulfide conversion process achieved under mild hydrothermal conditions. The structures of the all-inorganic open framework chalcogenides consist of a 2-fold interpenetrated diamond-like 3D framework containing pseudo-T 3 [Ga 10 S 20 ] 10– supertetrahedra. 48% of the structural volume is occupied by A + cations and water species, as established by single-crystal X-ray diffraction (SCXRD), infrared (IR) and energy-dispersive (EDS) spectroscopies. The dynamic nature of the A + cations and water molecules within the pores was investigated via single crystal X-ray diffraction as well as by IR spectroscopy monitored H 2 O to D 2 O exchange experiments. Framework stability was probed with post-synthetic treatment of A 3 Ga 5 S 9 ·xH 2 O (A = Rb and Cs) samples in acidic solutions that resulted in the formation of the oxysulfide (A/H) 3 Ga 5 S 9–y O y ·xH 2 O (A = Rb and Cs; y = 0–1), as shown by SCXRD and IR. Ion-exchange studies on A 3 Ga 5 S 9 ·xH 2 O (A = Rb and Cs) samples were carried out utilizing a uranyl acetate solution. The presence of the UO 2 2+ species in the ion-exchanged product was supported by IR and EDS spectroscopies. Batch method ion-exchange experiments on Cs 3 Ga 5 S 9 ·xH 2 O powder demonstrated fast kinetics with 95% uranyl removal from the uranyl acetate solution during the first minute, a maximum uranyl uptake capacity of 15mg/g, and the subsequent elution of uranyl species with KCl solution. Furthermore, the porous and dynamic nature of the A 3 Ga 5 S 9 ·xH 2 O framework coupled with effective UO 2 2+ ···S 2– bonding interactions makes it a good potential sorbent for uranyl remediation from aqueous media.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRSDate not supplied

Integrated Bosch Process System Models for In-Situ Oxygen and Carbon Production

In-Situ Resource Utilization (ISRU) technology is a vital component to NASA’s mission of a sustainable presence on the Moon and Mars. Local resources can be leveraged to reduce resupply frequency and mass. Elements of the Bosch process, combined with the carbothermal reduction process, can produce oxygen on the lunar surface with minimal consumables. The Bosch process can also produce oxygen on the Martian surface by using the CO 2 -rich environment. Between both systems, adsorption pump, solar thermal energy, carbon formation reactor, and water recovery subsystems are modeled and integrated to create a functional model in MATLAB software. The model is used to simulate performance of the system and reduce mass, power, and volume requirements. This integrated system model provides a tool to scale ISRU technologies for oxygen and carbon production. The MATLAB model is created by developing a system of independent subsystem models that are solved for their quasi-steady state values which can be integrated with respect to time to determine the change in current states. A flexible time stepping method is used to ensure a high level of accuracy during periods of rapid change while still making use of a simple explicit integration method. The flexible time step is calculated for each independent subsystem and the minimum value from those is used as the overall time step. A flexible time step is calculated by dividing a resolution value, or the maximum change per time step, by the variables current rate of change. The maximum value from all points in space is used for subsystem models that contain multiple values. The process is done for every variable that is being monitored in each subsystem and the global minimum is used as that iteration’s timestep. Several assumptions used in the MATLAB model for fluid flow dynamics, such as 1-D gas flow through the sorption pump, are supported by modeling in Ansys Fluent software. The Lunar oxygen production system is outlined in Fig. 1. The carbothermal reduction subsystem uses solar energy to heat a mixture of lunar regolith and carbon powder to produce carbon monoxide. To begin, the carbon monoxide feeds to the modified Bosch subsystem along with hydrogen gas. The reactants then enter the carbon formation reactor where water and carbon powder are produced. Solar thermal energy is used to add energy to the reactor, but waste heat from the carbothermal process is another potential heat source. The water is collected and electrolyzed to produce hydrogen which reenters the Bosch subsystem, and the oxygen is stored for downstream use. The carbon powder is collected and feeds back into the carbothermal subsystem. The Martian oxygen production system uses the full Bosch process and is outlined in Fig 2. A CO 2 adsorption pump thermally cycles to scrub and pressurize CO 2 from the environment. Along with an initial supply of hydrogen, the reactants enter the Reverse Water Gas Shift Reactor (RWGSR) which produces carbon monoxide and water. Carbon monoxide and unreacted hydrogen enter the carbon formation reactor to produce water and carbon powder. The water is collected from both reactors and electrolyzed to reintroduce hydrogen and store oxygen for propellant production or life support. Carbon is removed from the carbon formation reactor and stored. The adsorption pump utilizes rapid cycle temperature swings within a stack of zeolite coated surfaces. The subsystem model solves 1-D quasi-steady conservation laws of the quasi-steady form, shown in Eq. 1, for the gas stream and heat exchange liquid to predict performance parameters such as breakthrough capacity and optimum cycle time. The source term S is used to capture interactions between the fluid flows and the sorbent. A quasi-steady-state scheme is used where no time derivatives appear in the governing equations, except for those in the source terms. This results in an autonomous system, where ∂F/∂x = ƒ(F). The fluxes F are provided at the inlet, and an explicit method is used to solve for the spatial distribution of F. The heat and mass flows to the sorbent are then extracted from the source terms. These flows are numerically integrated to produce a 1-D solution for the system’s state as a function of both time and space. The body of the adsorption pump is separated into two semi-independent models: the heat exchanger fluid flow and gas flow through the zeolite coated surfaces. Both models are solved using the above-described method to find a 1-D solution as a function of space and interact only once a timestep is taken. The interaction point is the sorbent through which all heat transfer between the two models must occur. Sorbent mass adsorption is calculated using the Lagergren model, shown in Eq. 2, where the transfer coefficient, λ D , is found by solving a system of nondimensionalized equations derived by using the heat and mass transfer analogy for transport phenomena. Using Grade 544 Type 13X zeolite as the sorbent material, the equilibrium concentration, θ eq , is calculated using the k-site Langmuir isotherm and fit parameters. Additionally, the enthalpy of adsorption used in the model is computed by interpolation of available data [1]. The subsystem model was validated using the Rapid Cycle Temperature Swing Adsorption (RC-TSA) pump. The solar thermal energy subsystem focuses on a solar concentrator concept with a heat exchanger to heat the reactants before entering the carbon formation reactor. The subsystem model assumes a fixed solar flux and reflector efficiency to calculate the reactant temperature given the incoming temperature, pressure, and exchanger geometry. The receiver is a custom manufactured series of copper blocks with serpentine channels to increase its surface area and the residence time of the reactants to heat up to 550 °C. The subsystem model was validated using a heat exchanger developed at NASA Glenn Research Center (GRC). The solar thermal energy subsystem focuses on a solar concentrator concept with a heat exchanger to heat the reactants before entering the carbon formation reactor. The subsystem model assumes a fixed solar flux and reflector efficiency to calculate the reactant temperature given the incoming temperature, pressure, and exchanger geometry. The receiver is a custom manufactured series of copper blocks with serpentine channels to increase its surface area and the residence time of the reactants to heat up to 550 °C. The subsystem model was validated using a heat exchanger developed at NASA Glenn Research Center (GRC).

In situ Resource Utilization↗