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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Sensitivity Analysis of H 2 O Pulsed Neutron Die Away Experiments to the H-H 2 O Thermal Scattering Law

Lawrence Livermore National Laboratory is conducting new Pulsed-Neutron Die-Away (PNDA) benchmark experiments to validate neutron thermal scattering laws (TSLs). TSLs are important data for modeling thermal fission reactors, criticality safety scenarios, and radiation protection and detection, i.e. any application with thermal neutrons. These simulations require high-quality nuclear data, with confidence in their quality established through validation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Vegetation water sources in California's Sierra Nevada (USA) are young and change over time, a multi-isotope ( δ 18 O, δ 2 H, 3 H) tracer approach.

Sierra Nevada forests transpire a significant amount of California's water resources, sparking interest in applying forest management to improve California's water supply. Determining the source water of evapotranspiration enables forest managers to make informed decisions. To this end, a significant interest in critical zone science is to develop new methods to work across time scales to predict subsurface water storage and use. Here, forest vegetation accessed young water and switched sources depending on availability, suggesting that forest drought vulnerability may depend on the range of water sources available (rain, snowmelt and deeply stored water). This finding also suggests that changes in transpiration rates may have immediate effects on water sources in close proximity to vegetation, and delayed effects on storage and runoff. New δ 18 O, δ 2 H and 3 H data were used to track precipitation, runoff, evapotranspiration and storage through the critical zone seasonally, including seasons where evapotranspiration and snowmelt were in phase (winter snowmelt) and out of phase (seasonally dry summer). The main source of this headwater catchment's runoff is derived from its meadow saturated zone water, which was dominated by snowmelt. Water that originated as snowmelt contributed to transpiration, unless other sources, such as recent rain, became available. In cases where xylem δ 18 O and δ 2 H signatures matched those of deeper saturated zone water, 3 H data showed that xylem water was distinctly younger than the deep saturated zone water. During 2016, which experienced relatively normal snowpack in winter and seasonally dry summer conditions, mean summer saturated zone water and vegetation water were similar in δ 18 O, –12.4 ± 0.04 ‰ and – 12.5 ± 0.3 ‰, respectively, but were distinctly different in 3 H, 5.5 ± 0.2 pCi/L and 13.7 ± 1.1 pCi/L, respectively. While δ 18 O shows that vegetation and meadow saturated zone water have similar origins, 3 H shows they have dissimilar ages.

58 GEOSCIENCES↗
DOE OSTI2024

An experimental, theoretical and kinetic modeling study of the N 2 O-H 2 system: Implications for N 2 O + H

The reaction of N 2 O with His the key step in consumption of nitrous oxide in thermal processes. The major product channel is N 2 + OH, while NH + NO constitute minor products. In addition, a pathway involving HNNO, initiated by N 2 O + H (+M)$\rightleftarrows$HNNO (+M) (R3, R4), has been inferred from experiment and theory by Burke and coworkers. At longer reaction times, the reaction may reach partial equilibration, and in addition to k 3 and k 4 the importance of this channel depends on the thermodynamic properties of HNNO and its consumption reactions, mainly HNNO + H. In the present work, we re-examined the thermochemistry of HNNO and calculated rate constants and branching fractions for the HNNO + H reaction. Experiments on the N 2 O-H 2 system were conducted in a high-pressure flow reactor at 100 atm as a function of temperature (600-925 K) and stoichiometry and explained in terms of an updated chemical kinetic model. The results support the importance of the HNNO pathway, which results in inhibition of N 2 O consumption and formation of NH 3 . In addition, selected literature results on the N 2 O-H 2 system are re-examined and the implications for the other product channels of N 2 O + H, in particular NH + NO, are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

An all-oxide electrolysis cells for syngas production with tunable H 2 /CO yield via co-electrolysis of H 2 O and CO 2

High-rate production of syngas with tunable H 2 /CO and coke-free operation is achieved in a solid-oxide electrolysis cell (SOEC). Prior to operation, controlled pre-reduction of La 0.7 Sr 0.3 Fe 0.9 Ni 0.1 O 3-δ (LSFNi) cathode is used to trigger the in-situ exsolution of Ni-Fe alloy nanoparticles with an average size of ~45 nm uniformly distributed and socketed on LSFNi backbone, enabling efficient co-electrolysis of H 2 O and CO 2 to H 2 and CO. At 1.5 V, the current density reaches ~1.0 A cm-2 at 750 °C and ~2.4 A cm -2 at 850 °C with near 100% Faradaic Efficiency. We demonstrate the feasibility of tuning the output H 2 /CO ratio by nearly two orders of magnitude (from ~0.1 to ~7) by manipulating H 2 O/CO 2 ratio of feed gas, operating temperature, and current density. Finally, stable operation for >100 h is obtained without evidence of carbon deposition, although high current density operation leads to observable deterioration of anode/electrolyte interface due to the rapid oxygen evolution.

25 ENERGY STORAGE↗
DOE OSTI2021

The hydrogen-containing bronzes H 0.23 WO 3 and H 0.10 ReO 3 synthesized via a polymer route

We report the synthesis of two hydrogen-containing perovskite-type bronzes H 0.23 WO 3 and H 0.10 ReO 3 utilizing an unconventional solid-state synthetic approach, involving the use of the polymer Poly(vinylidene fluoride) (CH 2 CF 2 ) n. Powder neutron diffraction at ambient temperature shows that H 0.23 WO 3 crystallizes in a tetragonal symmetry distortion of the simple perovskite structure (space group P4/nmm), with lattice parameters a = 5.2279(2) Å, and c =3.8763(1) Å. H 0.10 ReO 3 , in contrast, crystallizes in a monoclinic distortion of a simple cubic perovskite (space group P2/m), with lattice parameters a = 5.3125(1) Å, b = 5.3155(3) Å, c = 3.7045(3) Å, and γ = 90.43(1)°. Both H 0.23 WO 3 and H 0.10 ReO 3 exhibit intrinsically diamagnetic behavior, with low temperature paramagnetic upturns and no signs of bulk superconductivity down to 0.35 K.

36 MATERIALS SCIENCE↗
DOE OSTI2020

An extended methodology for automated calculations of non-Boltzmann kinetic sequences: H + C 2 H 2 + X and combustion impact

It is generally assumed in phenomenological kinetic models that bimolecular reactions only occur between species whose rovibrational energy follows a Boltzmann (thermal) distribution. That is, any complexes initially formed in non-Boltzmann distributions are assumed to be thermalized by energy-transferring collisions prior to bimolecular reactions. Given the high mole fractions of reactive species, X, in combustion environments, reactive collisions of the complexes with X often occur on the same timescale as energy-transferring collisions – yielding sequences proceeding through non-Boltzmann intermediates across multiple potential energy surfaces. Recent studies have shown that such non-Boltzmann kinetic sequences can have substantial impact on the global reactivity in combustion systems. Simulations of these non-Boltzmann reaction sequences, which can be described in phenomenological kinetic models via chemically termolecular reactions, require that rovibrational excitation from one potential energy surface be carried over to the next. Here this paper presents an extended theoretical and computational methodology that couples multiple master equations and derives rate constants for phenomenological reactions describing the conversion of thermal reactants to thermal products for use in phenomenological kinetic schemes. The methodology is then implemented using in-house scripts for non-Boltzmann sequences involving C2H$^*_3$ + X (with X = O 2 , H, and OH) where C 2 H$^*_3$ is formed via H + C 2 H 2 association – which were identified as having strong potential for influencing combustion predictions in a recent study. The results reveal that non-Boltzmann reaction sequences for X = O 2 (the primary focus of this paper) significantly alters the total conversion rate from H + C 2 H 2 to products and product branching fractions from those of thermal sequential pathways. Furthermore, the present results demonstrate that non-Boltzmann reaction sequences have significant impact – as high as an order of magnitude – on predicted ignition delay times. Similarly, they yield significantly different dependence of ignition delay times with temperature and O 2 mole fraction – yielding signatures that are likely observable experimentally.

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

Crystal structure of indacaterol hydrogen maleate (C 24 H 29 N 2 O 3 )(HC 4 H 2 O 4 )

The crystal structure of indacaterol hydrogen maleate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Indacaterol hydrogen maleate crystallizes in space groupP-1 (#24) witha= 8.86616(9),b= 9.75866(21),c= 16.67848(36) Å,α= 102.6301(10), β = 94.1736(6),γ= 113.2644(2)°,V= 1273.095(7) Å 3 , andZ= 2 at 295 K. The crystal structure consists of layers of cations and anions parallel to theab-plane. Traditional N–H⋯O and O–H⋯O hydrogen bonds link the cations and anions into chains along thea-axis. There is a strong intramolecular charge-assisted O–H⋯O hydrogen bond in the non-planar hydrogen maleate anion. There are also two C–H⋯O hydrogen bonds between the anion and cation. The cation makes a strong N–H⋯O hydrogen bond to the anion, but also acts as a hydrogen bond donor to an aromatic C in another cation. The amino group makes bifurcated N–H⋯O hydrogen bonds, one intramolecular and the other intermolecular. The hydroxyl group acts as a donor to another cation. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

Materials Science↗
DOE OSTI2024

Crystal structure of brimonidine hydrogen tartrate, (C 11 H 11 BrN 5 )(HC 4 H 4 O 6 )

The crystal structure of brimonidine hydrogen tartrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Brimonidine hydrogen tartrate crystallizes in space groupP2 1 (#4) witha= 7.56032(2),b= 7.35278(2),c= 30.10149(9) Å,β= 90.1992(2)°,V= 1673.312(10) Å 3 , andZ= 4 at 295 K. The crystal structure consists of alternating layers of cations and anions parallel to theab-plane. Each of the hydrogen tartrate anions is linked to itself by very strong charge-assisted O–H⋯O hydrogen bonds into chains along thea-axis. Each hydroxyl group of each tartrate acts as a donor in an O–H⋯O or O–H⋯N hydrogen bond. One of these is intramolecular, but the other three are intermolecular. These hydrogen bonds link the hydrogen tartrate anions into layers parallel to theab-plane and also link the anion–cation layers. The protonated N atoms act as donors in N–H⋯O or N–H⋯N hydrogen bonds to the carboxyl groups of the tartrates and to a ring nitrogen atom. These link the cations and anions, as well as providing cation–cation links. The amino N atoms of the cations form N–H⋯O hydrogen bonds to hydroxyl groups of the anions. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®)

Materials Science↗
DOE OSTI2022

Manifesting Direction-Specific Complexation in [HFIP –H ·H 2 O 2 ] – : Exclusive Formation of a High-Lying Conformation

Size-selective, negative ion photoelectron spectroscopy in conjunction with quantum chemical calculations is employed to investigate the geometric and electronic structures of a protype system in catalytic olefin epoxidation research, i.e., deprotonated hexafluoroisopropanol ([HFIP -H ] - ) complexed with hydrogen peroxide (H 2 O 2 ). Spectral assignments and molecular electrostatic surface analyses unveil a surprising prevalent existence of a high-lying isomer with asymmetric dual hydrogenbonding configuration that is preferably formed driven by influential directionspecific electrostatic interactions upon H 2 O 2 approaching [HFIP -H ] - anion. Subsequent inspections of molecular orbitals, charge and spin density distributions indicate the occurrence of partial charge transfer from [HFIP -H ] - to H 2 O 2 upon hydrogen bonding interactions. Accompanying with electron detachment, a proton transfer occurs to form the neutral complex of [HFIP•HOO • ] structure. In conclusion, this work conspicuously illustrates the importance of directionality encoded in intermolecular interactions involving asymmetric and complex molecules, while the produced hydroperoxyl radical HOO • offers a possible new pathway in olefin epoxidation chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Cooled Gas Turbine and Combined Cycle Analysis for H 2 -CH 4 Fuel Mixes (Up to 100% H 2 )

In this study, a cooled gas turbine analysis was conducted for varying levels of hydrogen (H 2 ) blends with the natural gas. The ultimate goal is to have a gas turbine design that can be used for all the fuel blends (including 100% H 2 ) without any changes to the system. The technological developments in the cooling system, gas turbine design and materials that will be required for H 2 combustion were identified and analyzed in this study to develop an advanced gas turbine design for H 2 fuels. The study includes a combined cycle performance analysis with the H 2 fuel blends using the advanced gas turbine design developed in this study. A techno-economic analysis was conducted for analyzing the impact of the H 2 fuels on the levelized cost of electricity and cost sensitivities to fuel price and capacity factor.

03 NATURAL GAS↗
NASA NTRS1991

A measurement of the cosmic-ray H-2 and He-3 spectra and H-2/He-4 and He-3/He-4 ratios in 1989

The energy spectra of H-2 and H-3 nuclei up to energies of 450 and 800 MeV nucleon, respectively, were measured during a balloon flight of the NASA/NMSU Balloon Borne Magnet Facility on September 5, 1989. These isotopes were cleanly resolved from the more abundant H-1 and He-4 using a measurement of rigidity versus velocity as measured in a high-resolution scintillation counter. After correction for atmospheric secondaries the measured H-2/He-4 and He-3/He-4 ratios are both consistent with the production expected if H-1 and He-4 have the same path length in the galaxy as heavier cosmic-ray nuclei such as C and Fe, to within about 20 percent. Solar modulation effects play an important role in this uncertainty. This result favors a generally similar propagation history, along with similar types of sources for H-1 and He-4 and the heavier cosmic-ray nuclei.

Webber, W. R.↗
NASA NTRS1992

The molecular core in G34.3 + 0.2 - Millimeter interferometric observations of HCO(+), H(C-13)N, H(C-15)N, and SO

This study presents high-resolution observations of the molecular core in the star-forming region G34.3 + 0.2. Maps at 6-arcsec resolution of emission and absorption of the J = 1 - 0 transitions of HCO(+), H (C-13)N, H(C-15)N, and of the 2(2) - 1(1) transition of SO were obtained in addition to a map of the 3.4-mm continuum emission from the compact H II component. The HCL(+) emission toward G34.3 + 0.2 traces a warm molecular core about 0.9 pc in size. Emission from H (C-13)N is detected over about 0.3 pc. The cometary H II region lies near the edge of the molecular core. The blueshift of the radio recombination lines with respect to the molecular emission suggests that gas from the H II region is accelerated in a champagne flow caused by a steep gradient in the ambient gas density.

Carral, Patricia↗