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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Transformer Analysis with ANSYS Maxwell and COMSOL

This is an extension of work described by Rodriguez et al . (2021). It continues analyses of a generic transformer design by Wes Greenwood. In this report, we summarize that work and add comparable results using the ANSYS Maxwell software (henceforward, “ANSYS”), and with COMSOL . We found the ANSYS and COMSOL calculations of inductance agreed well with previous results for simplified coils in air, and with a ferromagnetic core. We then describe the ANSYS and COMSOL approach and show results for a full transformer model based on magnetic field analyses. Finally, we present electrostatic analyses of E field enhancement, once again resolving individual wires. The purpose is to assess the electrostatic fields in order to locate where electric breakdown is likely to originate. We found the maximum enhancement between the secondary and either the primary or the tertiary at the end of the windings with a large potential difference.

42 ENGINEERING↗
DOE OSTI2020

In Situ Structural and Electrical Conductivity Characterization of Sr2MMoO6-δ Double Perovskite Solid Oxide Fuel Cell Anode Materials

In this study, a series of Sr 2 MMoO 6-δ double perovskite solid oxide fuel cell (SOFC) anode materials (where 0 <= δ <= 0.041 and M = Fe, Co, or Ni) were synthesized, and the changes in their morphologies under relevant SOFC operating conditions were explored. Ultra-small-angle X-ray scattering (USAXS), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) were used to determine changes in the microstructures and phase compositions of the anode materials at high temperatures and under a reducing atmosphere. The stability of the double perovskite structure was found to be highly dependent on the identity of the cation M, such that when M = Fe, the material remained stable over the course of the experiments. However, when M = Co or Ni, significant changes in the microstructure and phase composition were observed. An in situ study of the M = Co sample, in which electrical conductivity and USAXS/SAXS/WAXS measurements were conducted simultaneously, revealed the structural degradation mechanisms and electrical conductivity changes over a range of temperatures. To conduct these measurements, a cell was developed that allowed for a sample mounted on Pt wires to be placed in the X-ray beam and heated under gas flow comprising 4% mass H 2 and 96% mass N 2 . The resulting measurements allowed for the direct comparison of the electrical and morphological changes occurring in the material under operating conditions, such that increases in conductivity could be attributed to the growth of new phases.

25 ENERGY STORAGE↗
DOE OSTI2024

Thermal aging effects on crosslinked polyethylene cable insulation with decabromodiphenyl ether flame retardant alternative

Decabromodiphenyl ether (decaBDE) has been extensively used as a flame retardant in several applications, including nuclear electrical cable insulation. However, decaBDE has been identified as a persistent, bioaccumulative and toxic (PBT) substance, leading to regulatory scrutiny. The Environmental Protection Agency (EPA) published a regulation on January 6, 2021, aimed at phasing out the manufacturing, processing, and distribution of decaBDE. This rule set a compliance deadline of March 8, 2021, for the manufacture and processing of decaBDE, and an extended deadline of January 6, 2023, for specific applications including wire and cable insulation in nuclear power generation facilities. In response to such regulations, RSCC, a major supplier of safety-related electrical cables and associated products to the U.S. nuclear industry updated the formula of their crosslinked polyethylene (XLPE) insulation to replace the historically used decaBDE flame retardant with an acceptable alternative. This change from the previous decaBDE-containing XLPE prompted interest in comparative performance of the two material formulations, especially with respect to characteristics relevant to safety-related function such as thermal and radiation resistance. RSCC graciously provided samples of wire insulated with the decaBDE-containing XLPE formulation and corresponding wire insulated with XLPE of the new formulation, containing a decaBDE alternative. In this work we compare characteristics of the two formulations and a previously produced commercial version of the RSCC decaBDE-containing XLPE insulation subjected to thermal aging at 150 °C and 165 °C. The comparison was focused on mechanical durability, thermal stability in the oxidative environment, and chemical structures. Briefly, • Tensile elongation at break (EAB) results showed loss of mechanical elasticity with longer aging time, as expected. Aging time dependence of EAB did not differ between the decaBDE-containing and decaBDE-alternative samples. • Subtle differences between the two materials can be detected from Fourier-transform infrared spectroscopy (FTIR) absorbance spectra in the range below 1700 cm -1 , are assumed to be related to decomposition of flame retardant additives during thermal aging. • The oxidation induction time (OIT) data seemed to show that the unaged decaBDE-containing XLPE material is more thermally stable than the unaged decaBDE-alternative material, but the discrepancy in OIT decreased with aging time and the OIT values of the two materials became similar starting with the 4 th day of aging at 165 °C. This thermal aging investigation confirmed that the mechanical durability, a key property monitored for cable qualification, was not significantly affected by the modification of the formulation with a decaBDE alternative flame-retardant system in the investigated thermal aging conditions. Further studies on the same sets of materials exposed to thermal and gamma radiation aging would further inform comparison of the materials safety-related function.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Modulation and Modeling of Three-Dimensional Nanowire Assemblies Targeting Gas Sensors with High Response and Reliability

Despite improved sensitivity, simple downsizing of gas-sensing components to randomly arranged nanostructures often faces challenges associated with unpredictable electrical conduction pathways. In the present study, controlled fabrication of three-dimensional (3D) metal oxide nanowire networks is demonstrated that can greatly improve both signal stability and sensor response compared to random nanowire arrays. For example, the highest ever reported H 2 S gas response value, and a 5 times lower relative standard deviation of baseline resistance than that of random nanowires assemblies, are achieved with the ordered 3D nanowire network. Systematic engineering of 3D geometries and their modeling, utilizing equivalent circuit components, provide additional insights into the electrical conduction and gas-sensing response of 3D assemblies, revealing the critical importance of wire-to-wire junction points and their arrangement. Here these findings suggest new design rules for both enhanced performance and reliability of chemical sensors, which may also be extended to other devices based on nanoscale building blocks.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Apparatus and methods for manufacturing high-density coil with formed cooling channels

A conductive coil for an electric application having a cooling channel for a coolant liquid or gas. The coil includes a wire winding of a plurality of wire turns. The wire winding is compressed about a cooling channel which is disposed between adjacent turn segments of the plurality of wire turns. The wire winding is formed and pressed against a shaping element to form the coolant channel within the compressed winding.

Brown, Ian Patrick↗
DOE OSTI2022

Development of an Integrated Electro-Hydraulic Machine to Electrify Off-highway Vehicles

Electrification of off-highway vehicles is notoriously challenging due to extreme power density requirements. This paper proposes and develops an axial flux machine integrated with a hydraulic pump to realize a single modular, electro-hydraulic machine to electrify off-highway vehicle implements. This integrated machine eliminates redundant bearings, couplings, and shaft seals, re-uses surfaces, and enables direct cooling of the electric machine with the hydraulic fluid, to significantly increase power density. Three popular axial flux machine variants are first compared using an FEA-based design optimization approach. The single rotor, single stator variant is identified to be the most promising for integration with the hydraulic pump. Next, a multi-physics framework of the complete integrated hydraulic pump and axial flux machine is developed to characterize the design space. The results indicate promising potential for this concept to realize efficiency over 85% and power density over 5kW/kg for the complete machine (electric machine, hydraulic pump, and thermal management system), while utilizing conventional materials (thin gauge silicon steel, N45 magnets, and enamelled copper wire). Furthermore, a prototype axial flux machine has been experimentally characterized and integrated with a hydraulic pump to demonstrate the integrated electro-hydraulic machine concept.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Cracked Film Lithography with CuGaO x Buffers for Bifacial CdTe Photovoltaics

Abstract Bifacial CdTe solar cells with greater power density than the monofacial baselines are demonstrated by using a CuGaO x rear interface buffer that passivates while reducing sheet resistance and contact resistance. Inserting CuGaO x between the CdTe and Au increases mean power density from 18.0 ± 0.5 to 19.8 ± 0.4 mW cm −2 for one sun front illumination. However, coupling CuGaO x with a transparent conductive oxide leads to an electrical barrier. Instead, CuGaO x is integrated with cracked film lithography (CFL)‐patterned metal grids. CFL grid wires are spaced narrowly enough (≈10 µm) to alleviate semiconductor resistance while retaining enough passivation and transmittance for a bifacial power gain: bifacial CuGaO x /CFL grids generate 19.1 ± 0.6 mW cm −2 for 1 sun front + 0.08 sun rear illumination and 20.0 ± 0.6 mW cm −2 at 1 sun front + 0.52 sun rear—the highest reported power density at field albedo conditions for a scaled polycrystalline absorber.

14 SOLAR ENERGY↗
DOE OSTI2024

Catalytic Reduction of Carbon Monoxide to Liquid Fuels with Recyclable Hydride Donors

Solar light absorption and catalysis are physically separated processes in natural photosynthesis. Natural cofactors, such as nicotinamide adenine dinucleotides (NADH), transport electrons and hydrogen to regulate and activate enzymes at remote locations. The physical separation of light absorption from catalysis provides some inspiration for artificial photosynthesis. One rather extreme implementation is to use copper wires to transport carriers from photovoltaic cells to dark electrodes, where catalysis occurs. Indeed, with a futuristic electrical grid powered solely by photovoltaics, solar capture could be separated from catalysis by hundreds of miles. An alternative approach, that bares more similarity to natural photosynthesis, employs mobile NADH/NAD + -like species that shuttle between the light absorber and a proximate, yet unilluminated, location where catalysis occurs. Additionally, such a remote approach to solar photocatalysis was recently proposed for the reduction of carbon oxides, CO 2 and CO, to methanol by cascade catalysis. This developing artificial photosynthetic approach offers the promise of catalytic generation of methanol and oxygen gas with sunlight as the sole energy source and CO 2 and water as the only chemical feedstocks. This Viewpoint evaluates the strengths and weaknesses of this approach with an emphasis on CO reduction catalysis with photorecyclable hydride donors while looking forward to what might reasonably be achieved with continued research.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Mitigating Electrochemical Impedance Spectroscopy Artifacts in PEMWE Reference Electrode Measurements

This study investigates strategies to improve the quality of electrochemical impedance spectroscopy (EIS) measurements using reference electrodes (RE) in proton exchange membrane water electrolyzers (PEMWE). We demonstrate that adding a low impedance wire in parallel to the RE significantly enhances signal accuracy, especially at high frequencies. Additionally, we identify electrical pad heaters as a source of measurement noise. EIS measurements fulfilling Kramers–Kronig validity criteria were only achieved in their absence. These insights advance the diagnostic capabilities of REs in water electrolyzers and support more reliable, spatially resolved analysis of electrochemical losses within the cell.

08 HYDROGEN↗
DOE OSTI2023

Effects of Field Strength and Silver Nanowire Size on Plasmon-Enhanced N 2 Dissociation

Dissociation of the nitrogen molecule via plasmon-enhanced catalysis using noble metal nanoparticles has been investigated both experimentally and computationally in recent years. However, the mechanism of plasmon-enhanced nitrogen dissociation is still not very clear. In this work, we apply theoretical approaches to examine the dissociation of a nitrogen molecule on atomically-thin Ag n nanowires (n = 6, 8, 10, 12) and a Ag 19 + nanorod. Ehrenfest dynamics provides information about the motion of nuclei during the dynamics process and real-time TDDFT calculations show the electronic transitions and population of electrons over the first 10s of fs time scale. The activation and dissociation of nitrogen is typically enhanced when the electric field strength increases. However, the enhancement is not always monotonic with field strength. As the length of the Ag wire increases, nitrogen is typically easier to dissociate and thus requires lower field strengths, even though the plasmon frequency is lower. The Ag 19 + nanorod leads to faster dissociation of N 2 than the atomically-thin nanowires. Altogether, our detailed study yields insights into the mechanisms involved in plasmon-enhanced N 2 dissociation, as well as provides information about factors that can be used to improve adsorbate activation.

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

Analysis of WIRE-21 SPND and Optical Fiber Sensor Measurements

The Wireless Instrumented RB Experiment 2021 (WIRE-21) was a highly instrumented experiment designed to test prototype wireless temperature and pressure sensors developed by Westinghouse Electric Corporation (WEC) in the High Flux Isotope Reactor (HFIR). In addition to these sensors, a suite of other sensors was also integrated into the experiment capsule, including various types of distributed optical fiber sensors and self-powered neutron detectors (SPNDs). This report presents an analysis of the data generated by the SPNDs and optical fiber sensors that were tested under the highest reported neutron flux. The distributed optical fiber sensor results demonstrate that F-doped optical fibers, particularly those inscribed with fs fiber Bragg gratings (FBGs), are capable of surviving fast neutron fluences on the order of 1021 n fast /cm 2 at temperatures relevant to light-water reactors (between 200 and 400°C). However, a significant blue-shift in the optical spectra of these sensors was observed over the course of irradiation which cannot be explained based on the current understanding of radiation-induced compaction in fused silica glass. A mechanistic understanding of this drift has not yet been developed and is proposed as future scope under the Advanced Sensors and Instrumentation program. Of the four SPNDs, only one appeared to operate normally during three cycles of irradiation. A radiation transport model of the experiment in HFIR was used to determine time-dependent neutron flux in this SPND and to calculate the neutron sensitivity of the device. Results showed a cycle averaged sensitivity of 1.5 ×10 -22 and 1.4 ×10 -22 A/nν for the first and third cycles of irradiation, respectively. Additional details pertaining to the optical fibers and SPNDs are included herein.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Critical current and stability tests of Nb 3 Sn for LBNL CCT magnet project

The Nb 3 Sn wires received from LBNL include the original round wires as well as the extracted wires from Rutherford cables. Total of 12 samples were prepared and heat treated. Five of them were tested for electric field versus current (E-I), among them 4 samples were further tested for electric field versus magnetic field (E-H). E-I traces were measured in magnetic field between 5 T and 8 T at 4.2 K. The critical currents of these sample are between 924 A and 993 A at 5 T. E-H measurements were performed at currents between 900 and 1500 A at 4.2 K. The stability currents, which is defined as the maximum current without quench during the E-H test, are determined to be between 1100 A and 1400 A. A separate Excel file presenting all the critical current and E-H curves is attached.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Formation and Evolution of Metallocene Single-Molecule Circuits with Direct Gold-π Links

Single molecule circuits with group 8 metallocenes are formed without additional linker groups in Scanning Tunnelling Microscope-based break junction (STMBJ) measurements at cryogenic and room temperature conditions with gold (Au) electrodes. We investigate the nature of this direct gold-π binding motif and its affect on molecular conductance and persistence characteristics during junction evolution. The measurement technique under cryogenic conditions tracks molecular plateaus through the full cycle of extension and compression. Analysis reveals that junction persistence when the metal electrodes are pushed together correlates with whether electrodes are locally sharp or blunt, suggesting distinct scenarios for metallocene junction formation and evolution. The top and bottom surfaces of the "barrel" shaped metallocenes present the electron-rich π system of cyclopentadienyl rings which interacts with the gold electrodes in two distinct ways. An undercoordinated gold atom on a sharp tip forms a donor-acceptor bond to a specific carbon atom in the ring. However, a small, flat patch on a dull tip can bind more strongly to the ring as a whole through Van der Waals interactions. Density functional theory (DFT) based calculations of model electrode structures provide an atomic-scale picture of these scenarios, demonstrating the role of these bonding motifs during junction evolution and showing that the conductance is relatively independent of tip atomic-scale structure. Furthermore, the non-specific interaction of the cyclopentadienyl rings with the electrodes enables extended conductance plateaus, a mechanism distinct from that identified for the more commonly studied, rod-shaped organic molecular wires.

25 ENERGY STORAGE↗
DOE OSTI2025

EV-EVSE Fault Study: An Analysis of Thermal Events Caused by Electrical Faults during DC Charging

This report outlines multiple avenues of analysis of electrical faults associated with electric vehicles (EVs) during charging, focusing specifically on the interactions between EVs and EV supply equipment (EVSE). Key concerns include the identification and mitigation of overtemperature events that can result in fires, which are commonly initiated by localized heating of connectors, wiring, or high-impedance fault current paths.

42 - ENGINEERING↗
DOE OSTI2020

Design of an Axial Flux Machine With an Integrated Hydraulic Pump for Off-Highway Vehicle Electrification

Axial flux machines offer an inherent torque density advantage over conventional radial flux machines and are increasingly being considered for transportation electrification applications. Electrification of off-highway vehicles is notoriously challenging due to extreme power density requirements. This paper investigates the use of axial flux machines for off-highway vehicle electrification. To maximize the power density, a hydraulic pump is integrated with the axial flux machine, resulting in a single modular, electric/hydraulic machine. This paper first compares three popular axial flux machine variants using an FEA-based design optimization approach. The single rotor, single stator variant is identified to be the most promising for integration with the hydraulic pump. Next, a multi-physics framework of the complete integrated hydraulic pump and axial flux machine is developed to search the design space. The results indicate promising potential for this concept to realize efficiency over 85% and power density over 5kW/kg for the complete machine (electric machine, hydraulic pump, and thermal management system), while utilizing conventional materials (thin gauge silicon steel, N45 magnets, and magnet wire)

Off-highway vehicles, Axial flux machines, Multi-p↗
DOE OSTI2021

Status of the Optical Dilatometer Method of Evaluating the Peak Irradiation Temperatures of SiC Passive Monitors

The main objective of this project was to conduct a comparative assessment between the optical dilatometer method and resistivity method, using all 10 SiC temperature monitors provided by two Nuclear Science User Facility experiments: BSU-8242 and General Electric Hitachi. Unfortunately, due to multiple delays in acquiring, shipping, and cleaning the SiC temperature monitors, the project was only able to process one (1) SiC temperature monitor during this period. SiC temperature monitor KGT-3357 was evaluated via the optical dilatometer method to determine its peak irradiation temperature. The KGT-3357 sample was from the BSU-8242 experiment and designed for a temperature of 300°C and an exposure of 1 dpa. The optical dilatometer measurements indicated that the KGT-3357 SiC temperature monitor’s peak irradiation temperature range was 240–267°C, with sensitivity of approximately ±20°C. Additionally, this temperature range falls within the evaluated melt wire temperature range of 238.6–271.5 °C. The remaining six (6) SiC temperature monitors from the BSU-8242 experiment and three (3) from the General Electric Hitachi experiment will be used in the future work to further validate the optical dilatometer method for measuring SiC peak irradiation temperatures.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Multi-Gigawatt Electric Highway

Ultra-Compact Electrical Transmission Lines are a new transmission line technology that uses large, hollow, aluminum beams to carry current instead of thin wires. Capacity is 4.5 times higher, power losses are 3 times lower, and cost per mile is a little lower than conventional lines. Resilience and reliability are higher. The beams are enclosed within concrete walls and out of the weather, protected from high winds, ice storms, fires, and lightning. The 230 kV version is 9 feet high x 11 feet wide and can use existing rights of way next to existing transmission lines or highways. With a little landscaping, these transmission lines are not an eyesore and will be much easier to permit on existing rights of way.

24 POWER TRANSMISSION AND DISTRIBUTION↗