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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

High-Energy and Stable Subfreezing Aqueous Zn–MnO 2 Batteries with Selective and Pseudocapacitive Zn-Ion Insertion in MnO 2

One major challenge of aqueous Zn–MnO 2 batteries for practical applications is their unacceptable performance below freezing temperatures. Here, in this study, the use of simple Zn(ClO 4 ) 2 aqueous electrolytes is described for all-weather Zn–MnO 2 batteries even down to -60 °C. The symmetric, bulky ClO 4 - anion effectively disrupts hydrogen bonds between water molecules and provides intrinsic ion diffusion even while frozen, and enables ≈260 mAh g -1 on MnO 2 cathodes at -30 °C . It is identified that subfreezing cycling shifts the reaction mechanism on the MnO 2 cathode from unstable H+ insertion to predominantly pseudocapacitive Zn 2+ insertion, which converts MnO 2 nanofibers into complicated zincated MnO x that are largely disordered and appeared as crumpled paper sheets. The Zn 2+ insertion at -30 °C is faster and much more stable than at 20 °C, and delivers ≈80% capacity retention for 1000 cycles without Mn 2+ additives. In addition, simple Zn(ClO 4 ) 2 electrolyte also enables a nearly fully reversible and dendrite-free Zn anode at -30 °C with ≈98% Coulombic efficiency. Zn–MnO 2 prototypes with an experimentally verified unit energy density of 148 Wh kg -1 at a negative-to-positive ratio of 1.5 and an electrolyte-to-capacity ratio of 2.0 are further demonstrated.

25 ENERGY STORAGE↗
DOE OSTI2021

Visible-Light-Enhanced Cobalt-Catalyzed Hydrogenation: Switchable Catalysis Enabled by Divergence between Thermal and Photochemical Pathways

The catalytic hydrogenation activity of the readily-prepared, coordinatively saturated cobalt(I) precatalyst, (R,R)-( iPr DuPhos)Co(CO) 2 H ((R,R)- iPr DuPhos = (+)-1,2-bis[(2R,5R)-2,5-diisopropylphospholano]benzene) is described. While efficient turnover was observed with a range of alkenes upon heating to 100 ºC, the catalytic performance of the cobalt catalyst was markedly enhanced upon irradiation with blue light at 35 °C. Here, this improved reactivity enabled hydrogenation of terminal, di- and trisubstituted alkenes, alkynes, and carbonyl compounds. A combination of deuterium labeling studies, hydrogenation of alkenes containing radical clocks and experiments probing relative rates support a hydrogen atom transfer pathway under thermal conditions that is enabled by a relatively weak cobalt–hydrogen bond of 56 kcal/mol. In contrast, data for the photocatalytic reactions support light-induced dissociation of a carbonyl ligand followed by a coordination-insertion sequence where the product is released by combination of a cobalt alkyl intermediate with the starting hy-dride, (R,R)-( iPr DuPhos)Co(CO) 2 H. These results demonstrate the versatility with catalysis with Earth-abundant metals as pathways involving open- versus closed-shell intermediates can be switched by the energy source.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1977

Nickel-hydrogen

Because of the disintegration of LaNi5 as the lattice expands on absorbing hydrogen, a nickel hydrogen cell similar to a nickel cadmium cell was designed. The positive electrode is wrapped in a microporous separator and the leads are insulated. A negative conducting grid is inserted and welded to the top of the can into an open ended container which is then turned upside down and filled so that LiNa5 powder occupies all the space not used by the rest of the components. The bottom of the can is then welded on. A fill tube is located either on the bottom or on the top of the can. When welded shut, the cell is put into a pressure bomb and the lanthanum nickel is activated at about 1,000 pounds of hydrogen. Electrolytes are added to the cell as well as whatever amount of hydrogen precharge desired, and the cell is sealed. Advantages and disadvantages of the cell are discussed.

Mchenry, E. J.↗
DOE OSTI2023

Triphenylborane in Metal-Free Catalysis

The development and application of new organoboron reagents as Lewis acids in synthesis and metal-free catalysis have dramatically expanded over the past 20 years. In this context, we will show the recent uses of the simple and relatively weak Lewis acid BPh 3 —discovered 100 years ago—as a metal-free catalyst for various organic transformations. The first part will highlight catalytic applications in polymer synthesis such as the copolymerization of epoxides with CO 2 , isocyanate, and organic anhydrides to various polycarbonate copolymers and controlled diblock copolymers as well as alternating polyurethanes. This is followed by a discussion of BPh 3 as a Lewis acid component in the frustrated Lewis pair (FLP) mediated cleavage of hydrogen and hydrogenation catalysis. In addition, BPh 3 -catalyzed reductive N-methylations and C-methylations with CO 2 and silane to value-added organic products will be covered as well along with BPh 3 -catalyzed cycloadditions and insertion reactions. Collectively, this mini-review showcases the underexplored potential of commercially available BPh3 in metal-free catalysis.

Lewis acid↗
NASA NTRS1982

Observations of structuring in the downstream region of a large spherical model in a laboratory simulated solar wind plasma

The effects of inserting a spherical conducting model, large in comparison with the Debye length, into a free streaming high-energy 1 kV) unmagnetized hydrogen plasma are investigated in order to measure energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. Holding the incident plasma parameters constant, transverse profiles of the net Langmuir probe current are plotted at various locations downstream in the model wake and are divided into three regions (the shadow, transition, and boundary). Results attributable to the use of a high-energy plasma show that enhancements in the shadow exist at downstream locations where the Mach ratio is less than one, and turbulence exists in the transition region on the shadow edges and outside in the boundary region. In addition, a small current enhancement is found in the boundary and can be attributed to the plasma/model interaction. It is concluded that many similar features observed by spacecraft downstream from planetary bodies are relatively permanent and are due to the intrinsic nature of the interaction between the solar wind plasma and the obstacle.

Intriligator, D. S.↗
NASA NTRS1991

Simulation of brush insert for leading-edge-passage convective heat transfer

Current and proposed high speed aircraft have high leading edge heat transfer (to 160 MW/sq m, 100 Btu/sq in/sec) and surface temperatures to 1370 K (2000 F). Without cooling, these surfaces could not survive. In one proposal the coolant hydrogen is circulated to the leading edge through a passage and returned to be consumed by the propulsion system. Simulated flow studies and visualizations have shown flow separation within the passage with a stagnation locus that isolates a zone of recirculation at the most critical portion of the passage, namely the leading edge itself. A novel method is described for mitigating the flow separation and the isolated recirculation zones by using a brush insert in the flow passage near the leading edge zone, thus providing a significant increase in heat transfer.

Hendricks, R. C.↗
DOE OSTI2022

Fusion Fuel Cycle Inventory Reduction Studies Using a Processing-Time–Based Discrete-Time Interval Model

Developing a Fusion Pilot Plant (FPP) design that minimizes risks due to tritium in-process inventory (IPI) is an important concern for the operation of commercial devices. This becomes even more of concern since an FPP will be breeding more tritium than is burned in the reactor for sustainability. The IPI is the tritium moving through the system that is not in the storage and delivery subsystem. Here a process model that solves time-dependent differential equations based on processing times was used to investigate the reduction of the IPI of a potential fuel cycle design. The impact of new and more efficient technologies such as direct internal recycling (DIR), metal foil pumps, continuous pumping, improved isotope separation, and hydrogen separating continuous pumps on IPI was investigated by adjusting subsystem processing times and material flow streams. It was shown that any of the insertions of DIR studied in this paper caused a reduction in the total IPI of the system and proved to be the optimal way to reduce the IPI in the system. Fuel cycle modifications near the torus, such as a coupled DIR and improved pumping systems, produced the largest reductions in tritium inventory.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1986

Growth of crystals of several boron-carbon compositions by chemical vapor deposition

Boron-carbon compounds have been deposited by the flow of carbon tetrachloride and boron trichloride, in the presence of a large excess of hydrogen, over a graphite surface maintained at 1000-1300 C. Deposits were formed on either an RF-heated disc or a tube or insert heated by a resistance furnace. Crystalline materials ranging in composition from B2C to B17C have been obtained.

Kevill, D. N.↗
DOE OSTI2023

Hydrogen and Deuterium Reactivity with Carbon Surface Impurities on the TPBAR Getter Ni Plate Studied in situ with Environmental XPS

Tritium for the U.S. Department of Energy’s Tritium Readiness Program is produced in tritium-producing burnable absorber rods (TPBARs) inserted into light-water nuclear reactors. The rods are stainless-steel-clad tubes with a permeation barrier coating and internal components. The internal components have been designed and selected to produce and retain tritium. The TPBAR incorporates a Ni-plated Zircaloy-4 getter tube to capture tritium and prevent it from reaching the rod cladding and permeating into the environment. The role of the Ni coating is to protect the Zircaloy-4 getter from oxidation while allowing for maximum tritium permeability. Ubiquitous surface impurities on the Ni, such as carbon, could limit its protective functionality and permeability if they exist in relatively large concentrations. The reactivity of impurity carbon with permeating tritium can also result in tritiated hydrocarbon impurities on the gas phase. The goal of this work is to determine quantitatively the chemical state and reactivity of potential Ni coating impurities in actual TPBAR getter samples. Using Environmental X-ray Photoelectron Spectroscopy (eXPS), a very sensitive gas/surface chemistry diagnostic, we reveal in situ the source and evolution of carbon on the Ni surface at different hydrogen and deuterium pressure conditions, and how carbon reactivity may result in hydrocarbon gas-evolution at application-relevant temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2025

The effect of ICRH and NBI on tungsten transport in neon edge radiation cooled discharges in TEXTOR

Tungsten is planned to be the plasma-facing material for the main chamber and divertor in future devices like ITER, SPARC, and DTT. To address risks associated with tungsten, R&D is being carried out on various toroidal confinement devices. One particular research question is related to the optimum heating mix for ITER. To investigate the influence of the heating scheme on the release and transport of tungsten, a comparison of neutral beam injection (NBI) and ion cyclotron resonance frequency (ICRF) heating was carried out in TEXTOR tungsten test limiter experiments. The experiments were performed under standard L-mode conditions and in radiative improved-mode operation with neon seeding and boronized walls covering the graphite plasma-facing components. The plasma was heated with hydrogen or deuterium NBI alone or with deuterium NBI in combination with H-minority, ion cyclotron resonance heating. A movable solid tungsten limiter was inserted through a limiter lock system into the edge plasma. The impurity release from this limiter was evaluated from visible spectroscopy. The tungsten concentrations in the plasma core were determined by extreme ultraviolet spectroscopy and bolometry. With deuterium NBI alone, strong central radiation and accumulation of W was observed. This can, however, be avoided by adding ICRF heating.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRSDate not supplied

Guidance and Control Techniques for Titan Aerogravity Assist for Enceladus Observation

Enceladus is a prime scientific target due active geological features and evidence that liquid water might be present on this Saturnian moon. The surface of Enceladus is covered in active fissures known as “Tiger Stripes”. The plumes coming from these rifts were sampled by the Cassini mission, which detected carbon, hydrogen, oxygen, and nitrogen – all key signatures where life could exit. In order to access this moon, mission design using traditional fully-propulsive orbit insertion maneuvers is fuel expensive and time consuming, leading a prior study to rule traditional chemical and solar electric propulsion based missions infeasible. One alternative that enables this mission is Titan aerogravity assist, which is an aeroassist maneuver that combines atmospheric flight and gravity assist of Titan to allow a spacecraft to enter a planetary capture orbit about Saturn. This poster will look at the guidance and control techniques that are required to allow aerogravity assist to take place within Titan’s atmosphere.

Soumyo Dutta↗
NASA NTRS1994

Coaxial microwave electrothermal thruster performance in hydrogen

The microwave electro thermal thruster (MET) is an electric propulsion concept that offers the promise of high performance combined with a long lifetime. A unique feature of this electric propulsion concept is its ability to create a microwave plasma discharge separated or floating away from any electrodes or enclosing walls. This allows propellant temperatures that are higher than those in resistojets and reduces electrode and wall erosion. It has been demonstrated that microwave energy is coupled into discharges very efficiently at high input power levels. As a result of these advantages, the MET concept has been identified as a future high power electric propulsion possibility. Recently, two additional improvements have been made to the coaxial MET. The first was concerned with improving the microwave matching. Previous experiments were conducted with 10-30 percent reflected power when incident power was in excess of 600 W(exp 6). Power was reflected back to the generator because the impedance of the MET did not match the 50 ohm impedance of the microwave circuit. To solve this problem, a double stub tuning system has been inserted between the MET and the microwave power supply. The addition of the double stub tuners reduces the reflected power below 1 percent. The other improvement has prepared the coaxial MET for hydrogen experiments. To operate with hydrogen, the vacuum window which separates the coaxial line from the discharge chamber has been changed from teflon to boron nitride. All the microwave energy delivered to the plasma discharge passes through this vacuum window. This material change had caused problems in the past because of the increased microwave reflection coefficients associated with the electrical properties of boron nitride. However, by making the boron nitride window electrically one-half of a wavelength long, power reflection in the window has been eliminated. This technical note summarizes the experimental performance of the improved coaxial MET when operating in nitrogen, helium, and hydrogen gases.

Richardson, W.↗
DOE OSTI2022

Conceptual Design of a Scintillator-Based Fast-Ion Loss Detector for the Wendelstein 7-X Stellarator

Here, a conceptual design of a scintillator-based fast-ion loss detector (FILD) has been developed for the Wendelstein 7-X stellarator (W7-X). Simulations using the Monte Carlo codes ASCOT5 and BEAMS3D have been performed to calculate the expected flux of neutral beam injection (NBI)-generated fast hydrogen ions onto the conceptual detector probe head. These fast-ion loss fluxes have been calculated for several magnetic field configurations as well as probe insertion positions. At the maximum insertion position, both co-and counter-going losses with high incident pitch angles are observed; however, at retracted positions, only co-going fast ions reach the probe head. The FILDSIM code has been used to optimize the geometry of the detector entrance and collimating elements to achieve a wide velocity space coverage as well as a high velocity–space resolution. A synthetic FILD signal is calculated for the expected loss distribution via forward modeling using the instrument response function. The synthetic signal is found to largely retain the velocity space features of the loss distribution.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1998

Preliminary Assessment of Using Gelled and Hybrid Propellant Propulsion for VTOL/SSTO Launch Systems

A novel, reusable, Vertical-Takeoff-and-Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit (VTOL/SSTO) launch system concept, named AUGMENT-SSTO, is presented in this paper to help quantify the advantages of employing gelled and hybrid propellant propulsion system options for such applications. The launch vehicle system concept considered uses a highly coupled, main high performance liquid oxygen/liquid hydrogen (LO2/LH2) propulsion system, that is used only for launch, while a gelled or hybrid propellant propulsion system auxiliary propulsion system is used during final orbit insertion, major orbit maneuvering, and landing propulsive burn phases of flight. Using a gelled or hybrid propellant propulsion system for major orbit maneuver burns and landing has many advantages over conventional VTOL/SSTO concepts that use LO2/LH2 propulsion system(s) burns for all phases of flight. The applicability of three gelled propellant systems, O2/H2/Al, O2/RP-1/Al, and NTO/MMH/Al, and a state-of-the-art (SOA) hybrid propulsion system are examined in this study. Additionally, this paper addresses the applicability of a high performance gelled O2/H2 propulsion system to perform the primary, as well as the auxiliary propulsion system functions of the vehicle.

Palaszewski, Bryan↗
NASA NTRS1998

Folding and translocation of the undecamer of poly-L-leucine across the water-hexane interface. A molecular dynamics study

The undecamer of poly-L-leucine at the water-hexane interface is studied by molecular dynamics simulations. This represents a simple model relevant to folding and insertion of hydrophobic peptides into membranes. The peptide, initially placed in a random coil conformation on the aqueous side of the system, rapidly translocates toward the hexane phase and undergoes interfacial folding into an alpha-helix in the subsequent 36 ns. Folding is nonsequential and highly dynamic. The initially formed helical segment at the N-terminus of the undecamer becomes transiently broken and, subsequently, reforms before the remainder of the peptide folds from the C-terminus. The formation of intramolecular hydrogen bonds during the folding of the peptide is preceded by a dehydration of the participating polar groups, as they become immersed in hexane. Folding proceeds through a short-lived intermediate, a 3(10)-helix, which rapidly interconverts to an alpha-helix. Both helices contribute to the equilibrium ensemble of folded structures. The helical peptide is largely buried in hexane, yet remains adsorbed at the interface. Its preferred orientation is parallel to the interface, although the perpendicular arrangement with the N-terminus immersed in hexane is only slightly less favorable. In contrast, the reversed orientation is highly unfavorable, because it would require dehydration of C-terminus carbonyl groups that do not participate in intramolecular hydrogen bonding. For the same reason, the transfer of the undecamer from the interface to the bulk hexane is also unfavorable. The results suggest that hydrophobic peptides fold in the interfacial region and, simultaneously, translocate into the nonpolar side of the interface. It is further implied that peptide insertion into the membrane is accomplished by rotating from the parallel to the perpendicular orientation, most likely in such a way that the N-terminus penetrates the bilayer.

NASA Discipline Exobiology↗
DOE OSTI2021

Chemical upgrade of carbon monoxide to acetate on an atomically dispersed copper catalyst via CO-insertion

Electrochemical conversion of small molecules such as carbon dioxide (CO 2 ) and carbon monoxide (CO) to high-value multi-carbon products (C 2+ ) offers a chemical upgrade approach for fuels and chemical feedstock production using renewable energy, in the possible absence of the petrochemical industry under the new energy system such as hydrogen economy. Identifying robust and efficient electrocatalysts to selectively produce C 2+ products remains a challenge. In this study, we report a synthetic strategy of atomically dispersing copper atoms on nitrogen-rich porous carbon (Cu–N–C) through pyrolysis of a supramolecular assembly. Benefitting from the unsaturated coordination structure, in KOH electrolyte, the Cu–N–C with a Cu content of 6.9 wt% exhibits a maximum acetate Faradaic efficiency (FE) of 30% with an acetate partial current density as high as 48 mA cm –2 in electrochemical CO reduction. Different from the C–C coupling mechanism on metallic copper, we propose a CO insertion mechanism for the acetate production on the single site copper catalyst.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Search for active and inactive ion insertion sites in organic crystalline materials

The position of mobile active and inactive ions, specifically ion insertion sites, within organic crystals, significantly affects the properties of organic materials used for energy storage and ionic transport. Identifying the positions of these atomic (and ionic) sites in an organic crystal is challenging, especially when the element has low X-ray scattering power, such as lithium (Li) and hydrogen, which are difficult to detect by powder X-ray diffraction. First-principles calculations, exemplified by density functional theory (DFT), are very practical for confirming the relative stability of ion positions in materials. However, the lack of effective strategies to identify ion sites in these organic crystalline frameworks renders this task extremely challenging. This work presents two algorithms: the (i) efficient location of ion insertion sites from extrema in electrostatic local potential and charge density (ELIISE), and the (ii) ElectRostatic InsertioN (ERIN), which leverage charge density and electrostatic potential fields accessed from first-principles calculations, combined with the Simultaneous Ion Insertion and Evaluation (SIIE) workflow. SIIE inserts all ions simultaneously—to determine ion positions in organic crystals. We demonstrate that these methods accurately reproduce known ion positions in 16 organic materials and identify previously overlooked low-energy sites in tetralithium 2,6-naphthalenedicarboxylate (Li4NDC), an organic electrode material, highlighting the importance of inserting all ions simultaneously, as in the SIIE workflow. These algorithms are also integrated with off-the-shelf machine learning potentials, yielding promising results comparable to first-principles findings.

Gopidi, Harshan Reddy [Argonne National Laboratory↗
NASA NTRS1979

Electrochemical cell for rebalancing REDOX flow system

An electrically rechargeable REDOX cell or battery system including one of more rebalancing cells is described. Each rebalancing cell is divided into two chambers by an ion permeable membrane. The first chamber is fed with gaseous hydrogen and a cathode fluid which is circulated through the cathode chamber of the REDOX cell is also passed through the second chamber of the rebalancing cell. Electrochemical reactions take place on the surface of insert electrodes in the first and second chambers to rebalance the electrochemical capacity of the anode and cathode fluids of the REDOX system.

Thaller, L. H.↗