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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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15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Dataset for manuscript "Consequences of the failure of equipartition for the p-V behavior of liquid water and the hydration free energy components of a small protein"

Previously, we showed that in the molecular dynamics simulation of a rigid model of water it is necessary to use an integration time-step dt that is less than or equal to 0.5 fs to ensure equipartition between translational and rotational modes. We extended that study in the NVT ensemble to NpT conditions and to an aqueous protein. We study neat liquid water with the rigid, SPC/E model and the protein BBA (PDB ID: 1FME) solvated in the rigid, TIP3P model. We examined integration time-steps ranging from 0.5 fs to 4.0 fs for various thermostat plus barostat combinations. We find that a small time-step, dt, is necessary to ensure consistent prediction of the simulation volume. Hydrogen mass repartitioning alleviates the problem somewhat, but is ineffective for the typical time-step used with this approach. The compressibility, a measure of volume fluctuations, is seen to be sensitive to dt. Using the mean volume estimated from the NpT simulation, we examined the electrostatic and van der Waals contribution to the hydration free energy of the protein in the NVT ensemble. These contributions are also sensitive to dt. In going from a time-step of 2 fs to a time-step of 0.5 fs, the change in the net electrostatic plus van der Waals contribution to the hydration of BBA is already in excess of the folding free energy reported for this protein. The data-set contains the simulation metadata and log files that support the claims noted above.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Simultaneous compression of NaCl, Au, and ruby: toward mutually consistent pressure scales

Here, we evaluate pressure consistency of equations of state (EOS) for NaCl and Au at 300 K. The simultaneous measurements of unit-cell volumes (V) with ruby R1 line shifts (Δλ) in a helium (He) loaded diamond cell effectively remove potential systematic errors. Compression and decompression data were automatically collected at 1 sec interval, yielding a dense dataset with >8,000 (V, Δλ) pairs each for NaCl and Au. Solidification of He has noticeable effects on both V and Delta lambda (hence P). Only data up to similar to 14 GPa, or 6000 (V, P) pairs, can be considered hydrostatic within the resolution. The P-V data are fitted to the Rydberg-Vinet and the 3 rd order Birch-Murnaghan EOS. Predicted pressures of these EOSs agree with those given by the Ruby2020 ruby scale to within +/- 0.05 GPa. Overall, pressures predicted by the Rydberg-Vinet EOS are in better agreement with the average of commonly used NaCl and Au pressure scales.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

P-V-T equation of state of boron carbide

We report the P-V-T equation of state measurements of B 4 C to 50 GPa and approximately 2500 K in laser-heated diamond anvil cells. We obtain an ambient temperature, third-order Birch–Murnaghan fit to the P-V data that yields a bulk modulus K 0 of 221(2) GPa and derivative, (dK/dP) 0 of 3.3(1). These were used in fits with both a Mie–Grüneisen–Debye model and a temperature-dependent, Birch–Murnaghan equation of state that includes thermal pressure estimated by thermal expansion (α) and a temperature-dependent bulk modulus (dK 0 /dT). The ambient pressure thermal expansion coefficient (α 0 + α 1 T), Grüneisen γ(V) = γ 0 (V/V 0 ) q and volume-dependent Debye temperature, were used as input parameters for these fits and found to be sufficient to describe the data in the whole P-T range of this study.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Inverter Intensive Hybrid Power Plant Modeling with Small-Signal Stability Augmentation through Flexible Operation Mode Transition

Hybrid power plants (HPPs) prompt the penetration of inverter-based renewable energy sources (RES) in transmission systems; however, given their low-inertia nature, HPPs are dominated by power electronic inverters, so there are inevitable challenges in system stability when increasing numbers of HPPs are integrated into the modern power grids. To boost the penetration level of HPPs without jeopardizing system stability, it is desirable to equip them with operational characteristics (i.e., grid-forming capabilities) that are comparable to those of conventional power plants dominated by synchronous generators (SGs). In this paper, a holistic model of inverter intensive HPP is derived and a bi-level hierarchical control is developed to allow HPPs to flexibly switch among the designed operation modes (i.e., P-Q, P-V, and isochronous modes). Compared to SGs, which have limited controllability, the operation mode of each HPP could vary as requested. Such flexible mode transitions could be integrated into the secondary plant-level control and be leveraged as an additional control degree to further augment system stability. Further, the system small-signal stability margin is quantified with varying HPP operation modes. More importantly, modal analysis is thereby conducted to quantify the impacts of mode transition on the system oscillatory modes. The effectiveness of the proposed HPP bi-level hierarchical control is verified using extensive case studies based on the simplified real-world island power grid, and the results validate that the system small-signal stability margin can be enhanced with the additional degree of control flexibility enabled by HPP operation mode transition. The real-time hardware-in-the-loop (HIL) results are also provided to verify the proposed method.

grid-forming control↗
DOE OSTI2021

DC Arc Incident Energy in Photovoltaic Systems: Methods for Evaluation

Renewable energy systems continue to be one of the fastest growing segments of the energy industry. This article focuses on the understanding of how photovoltaic (PV) technology behaves under dc arc conditions. Emphasis is placed on the electrical safety aspect of dc arc-flash incident energy (IE) evaluation. Because of the fast proliferation of PV systems and lack of formal equivalent calculation guidelines, such as IEEE 1584 for ac systems, it has been necessary to rely on different equations and models presented by various researchers over the last few years. This article discusses the behavior of PV systems under arc conditions and presents the results of the available methods to estimate the dc arc-flash IE. It provides a comparative analysis of a proposed arc-flash IE calculation method against different laboratory tests, including those performed for this article at the National Renewable Energy Laboratory (NREL). Detailed explanations are provided regarding the effect of the PV module current-voltage (I-V) and power-voltage (P-V) curves under arcing conditions. Examples of the application of the proposed calculation method to the test measurements are included.

arc discharges↗
DOE OSTI2022

Thermoelastic properties of zircon: Implications for geothermobarometry

Abstract A thermal-pressure equation of state has been determined for zircon (ZrSiO4) that characterizes its thermoelastic behavior at metamorphic conditions. New pressure-volume (P-V) data from a “Mud Tank” zircon have been collected from 1 bar to 8.47(1) GPa using X-ray diffraction, and elastic moduli were measured from room temperature up to 1172 K by resonance ultrasound spectroscopy. These data were fitted simultaneously with temperature-volume (T-V) data from the literature in EosFit7c using a new scaling technique. The parameters of a third-order Birch-Murnaghan EoS with a Mie-Grüneisen-Debye model for thermal pressure have compressional EoS parameters K0T = 224.5(1.2) GPa, K0T' = 4.90(31) with a fixed initial molar volume V0 = 39.26 cm3/mol and thermal parameters γ0 = 0.868(15), q = 2.37(80), and ΘD = 848(38) K. EoS parameters that describe the variation of unit-cell parameters with pressure and temperature were determined using an isothermal-type EoS. This new EoS confirms that zircons are stiffer than garnets and exhibit a much lower thermal expansion. This results in steep isomekes between zircon and garnets, which makes zircon trapped as inclusions in garnets at metamorphic conditions a good piezothermometer.

Geochemistry & Geophysics↗
DOE OSTI2021

Methods for Evaluating DC Arc Incident Energy in PV Systems: Preprint

Renewable energy systems continue to be one of the fastest growing segments of the energy industry. This paper focuses on the understanding of how photovoltaic (PV) technology behaves under dc arc conditions. Emphasis is placed on the electrical safety aspect of DC arc flash incident energy evaluation. Because of the fast proliferation of PV systems and the lack of formal equivalent calculation guidelines such as IEEE 1584 for AC systems, it has been necessary to rely on different equations and models presented by various researchers over the last few years. This paper discusses the behavior of PV systems under arc conditions and presents the results of available methods to estimate the dc arc flash incident energy. This paper provides a comparative analysis of a proposed arc-flash incident energy calculation method against different laboratory tests including those performed by NREL. Detailed explanations are provided regarding the effect of PV module I-V and P-V curves under arcing conditions. Examples of the application of the proposed calculation method to the test measurements are included.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Materials Data on VP by Materials Project

VP1 is Tungsten Carbide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. V3+ is bonded to six equivalent P3- atoms to form a mixture of face, edge, and corner-sharing VP6 octahedra. The corner-sharing octahedral tilt angles are 45°. All V–P bond lengths are 2.40 Å. P3- is bonded to six equivalent V3+ atoms to form a mixture of distorted edge and corner-sharing PV6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V3P by Materials Project

V3P crystallizes in the tetragonal P4_2/n space group. The structure is three-dimensional. there are three inequivalent V sites. In the first V site, V is bonded in a 4-coordinate geometry to four equivalent P atoms. There are a spread of V–P bond distances ranging from 2.37–2.45 Å. In the second V site, V is bonded in a 2-coordinate geometry to three equivalent P atoms. There are a spread of V–P bond distances ranging from 2.37–2.68 Å. In the third V site, V is bonded in a 2-coordinate geometry to two equivalent P atoms. There are one shorter (2.38 Å) and one longer (2.41 Å) V–P bond lengths. P is bonded in a 9-coordinate geometry to nine V atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V2P by Materials Project

V2P is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent V sites. In the first V site, V is bonded in a 4-coordinate geometry to four equivalent P atoms. There are a spread of V–P bond distances ranging from 2.33–2.47 Å. In the second V site, V is bonded in a 5-coordinate geometry to five equivalent P atoms. There are a spread of V–P bond distances ranging from 2.44–2.67 Å. P is bonded in a 9-coordinate geometry to nine V atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VP by Materials Project

VP1 is Molybdenum Carbide MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. V3+ is bonded to six equivalent P3- atoms to form a mixture of distorted corner and edge-sharing VP6 pentagonal pyramids. All V–P bond lengths are 2.41 Å. P3- is bonded to six equivalent V3+ atoms to form a mixture of corner, edge, and face-sharing PV6 octahedra. The corner-sharing octahedral tilt angles are 47°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VP4 by Materials Project

VP4 is Sylvanite-derived structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. V4+ is bonded to six P1- atoms to form edge-sharing VP6 octahedra. There are a spread of V–P bond distances ranging from 2.35–2.42 Å. There are two inequivalent P1- sites. In the first P1- site, P1- is bonded in a 4-coordinate geometry to one V4+ and three P1- atoms. There are two shorter (2.23 Å) and one longer (2.25 Å) P–P bond lengths. In the second P1- site, P1- is bonded in a 4-coordinate geometry to two equivalent V4+ and two P1- atoms. The P–P bond length is 2.22 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VP2 by Materials Project

P2V crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. V5+ is bonded in a 8-coordinate geometry to eight P+2.50- atoms. There are a spread of V–P bond distances ranging from 2.43–2.49 Å. There are two inequivalent P+2.50- sites. In the first P+2.50- site, P+2.50- is bonded in a 4-coordinate geometry to three equivalent V5+ and three equivalent P+2.50- atoms. There are one shorter (2.23 Å) and two longer (2.58 Å) P–P bond lengths. In the second P+2.50- site, P+2.50- is bonded in a 5-coordinate geometry to five equivalent V5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V4P3 by Materials Project

V4P3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are five inequivalent V+2.25+ sites. In the first V+2.25+ site, V+2.25+ is bonded to six P3- atoms to form VP6 octahedra that share corners with six VP6 octahedra, corners with five equivalent VP5 square pyramids, corners with two equivalent VP5 trigonal bipyramids, edges with two equivalent VP6 octahedra, edges with three equivalent VP5 trigonal bipyramids, faces with two VP6 octahedra, and a faceface with one VP5 square pyramid. The corner-sharing octahedra tilt angles range from 43–53°. There are a spread of V–P bond distances ranging from 2.33–2.53 Å. In the second V+2.25+ site, V+2.25+ is bonded to five P3- atoms to form VP5 square pyramids that share corners with five equivalent VP6 octahedra, a cornercorner with one VP5 square pyramid, corners with six equivalent VP5 trigonal bipyramids, edges with two equivalent VP6 octahedra, edges with two equivalent VP5 square pyramids, edges with two equivalent VP5 trigonal bipyramids, and a faceface with one VP6 octahedra. The corner-sharing octahedra tilt angles range from 37–56°. There are a spread of V–P bond distances ranging from 2.35–2.42 Å. In the third V+2.25+ site, V+2.25+ is bonded to five P3- atoms to form VP5 trigonal bipyramids that share corners with four VP6 octahedra, corners with six equivalent VP5 square pyramids, edges with three equivalent VP6 octahedra, edges with two equivalent VP5 square pyramids, and edges with four equivalent VP5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 29–45°. There are a spread of V–P bond distances ranging from 2.42–2.46 Å. In the fourth V+2.25+ site, V+2.25+ is bonded in a square co-planar geometry to four P3- atoms. There are two shorter (2.40 Å) and two longer (2.49 Å) V–P bond lengths. In the fifth V+2.25+ site, V+2.25+ is bonded to six P3- atoms to form VP6 octahedra that share corners with eight equivalent VP6 octahedra, corners with four equivalent VP5 trigonal bipyramids, edges with two equivalent VP6 octahedra, edges with four equivalent VP5 square pyramids, and faces with two equivalent VP6 octahedra. The corner-sharing octahedra tilt angles range from 43–53°. There are a spread of V–P bond distances ranging from 2.35–2.48 Å. There are four inequivalent P3- sites. In the first P3- site, P3- is bonded in a 7-coordinate geometry to seven V+2.25+ atoms. In the second P3- site, P3- is bonded in a 8-coordinate geometry to eight V+2.25+ atoms. In the third P3- site, P3- is bonded to six V+2.25+ atoms to form distorted face-sharing PV6 pentagonal pyramids. In the fourth P3- site, P3- is bonded in a 6-coordinate geometry to six V+2.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V5P3 by Materials Project

V5P3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent V sites. In the first V site, V is bonded in a 6-coordinate geometry to six equivalent P atoms. All V–P bond lengths are 2.46 Å. In the second V site, V is bonded in a 5-coordinate geometry to five equivalent P atoms. There are a spread of V–P bond distances ranging from 2.37–2.57 Å. P is bonded in a 9-coordinate geometry to nine V atoms.

36 MATERIALS SCIENCE↗