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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Toward Water Volume Fraction Calculation in Multiphase Flows Using Electrical Capacitance Tomography Sensors

Real-time monitoring of water volume fraction in multiphase flows is an important problem for a number of industrial applications. The water phase in the multiphase flows may correspond to either the dispersed phase or the continuous phase. In the past, several lowcost and nonintrusive techniques based on the electrical capacitance tomography (ECT) has been developed to image and monitor in real-time multiphase flows containing water. Furthermore, such monitoring becomes increasingly challenging for high salinity levels, and no reliable ECTbased method is presently available which could work for obtaining water volume fraction in multiphase flows for all water salinity levels. In this paper, we propose a new approach based on the Hanai’s formula for complex dielectric constant and taking advantage of the Maxwell- Wagner-Sillars effect to obtain, to a good approximation, water volume fractions in multiphase flows containing water as either dispersed or continuous phase.

02 PETROLEUM↗
DOE OSTI2020

Thermal and radiation response of 4H–SiC Schottky diodes with direct-write electrical contacts

In this work, a high-sensitivity 4H–SiC temperature sensor and an alpha detector have been fabricated using additively printed metal contacts. The surface morphology and electrical conductivity of the printed electrodes were established prior to Schottky diode development. 4H–SiC Schottky diodes with direct-write printed silver contacts on the 5 μ m-thick epilayer on 4H–SiC were characterized electrically in terms of the forward and reverse current–voltage and high-frequency capacitance–voltage characteristics. Furthermore, the turn-on voltage of the Schottky diodes, as established from the forward current–voltage characteristics measured up to a temperature of 400 °C, showed a linear temperature dependence. Schottky diodes with direct-write printed Ag electrodes were able to measure alpha particles emitted from Americium-241. The high temperature and radiation response of the Schottky diodes show their suitability for multi-modal sensor fusion on the 4H–SiC platform for harsh environment applications.

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DOE OSTI2020

Enabling Seamless Integration of EV Charging Infrastructure with Weak Electric Grids

Widespread adoption of Electric Vehicles (EVs) for light, medium, and heavy duty (LD, MD, and HD) applications has gained significant interest. Based on ownership and user preferences, LD and local delivery MD EVs are typically connected to grid distribution networks whereas larger MD and HD EVs will be connected to distribution or even sub-transmission networks. Challenges with at-scale EVs and charging infrastructure supporting it include interoperability, distribution network upgrades, demand charges, power quality, voltage stability, etc. Based on real-world data, steady-state and dynamic assessments of LD EV adoption for weak distribution grids is presented.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2012

An Evaluation of Molecular Dynamics Performance on the Hybrid Cray XK6 Supercomputer

For many years, the drive towards computational physics studies that match the size and time-scales of experiment has been fueled by increases in processor and interconnect performance that could be exploited with relatively little modification to existing codes. Engineering and electrical power constraints have disrupted this trend, requiring more drastic changes to both hardware and software solutions. Here, we present details of the Cray XK6 architecture that achieves increased performance with the use of GPU accelerators. We review software development efforts in the LAMMPS molecular dynamics package that have been implemented in order to utilize hybrid high performance computers. We present benchmark results for solid-state, biological, and mesoscopic systems and discuss some challenges for utilizing hybrid systems. We present some early work in improving application performance on the XK6 and performance results for the simulation of liquid copper nanostructures with the embedded atom method.

42 ENGINEERING↗
DOE OSTI2011

NGNP Project 2011 Status and Path Forward

High Temperature Gas Reactor (HTGR) technology can play an important role in the United States’ energy future by extending the use of nuclear energy for non-electricity energy production missions as well as continuing to provide a considerable base load electric power generation capability. Extending nuclear energy into the industrial and transportation sectors through the co-production of process heat and electricity provides safe and reliable energy for these sectors in an environmentally responsible manner. The safety case for the modular HTGR provides a substantial improvement in nuclear plant safety for the protection of the public and the environment, and supports collocation of the HTGR with major industrial facilities. The NGNP Project at the Idaho National Laboratory has been working toward an objective of commercializing the HTGR technology under DOE direction since 2006. The Project is undergoing a quantum shift in direction and scope as a result of recent DOE decisions. This paper summarizes where the Project has been, where it is at the time of this writing and what is needed in future activities to commercialize HTGR technology.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Review of Selected Advances in Electrical Capacitance Volume Tomography for Multiphase Flow Monitoring

Electrical Capacitance Volume Tomography (ECVT) has emerged as an attractive technology for addressing instrumentation requirements in various energy-related multiphase flow systems. ECVT can monitor multiple flow conditions and reconstruct real-time 3D images from capacitance measurements using a large set of electrode plates placed around the processes column enclosing the sensed flow system. ECVT is non-intrusive and allows the measurement of changes in mutual capacitance between all possible plate pair combinations. The objective of this paper is to provide a comprehensive review of recent advances in ECVT, enabling robust monitoring of multiphase flows, especially water-containing multiphase flows.

02 PETROLEUM↗
DOE OSTI2020

Environmental influence on cracking and debonding of electrically conductive adhesives

Electrically conductive adhesives (ECAs) are starting to replace metallic solders in recent designs of photovoltaic (PV) modules. This transition represents a significant material change, and a proper understanding of the durability and reliability of the new interconnect needs to be established. This paper presents our continued work on developing a degradation model for ECA interconnects in PV modules. Here, we characterize the fracture mechanics properties of an epoxy-based ECA, for both critical and subcritical, mode I and mode II loading conditions. Emphasis is on the influence of different environmental conditions such as temperature and humidity. We use the Finite Element Method to account for residual stresses, induced by temperature changes and moisture absorption, and correct the apparent fracture toughness. We found that high moisture levels not only can weaken the fracture resistance of the ECA interconnect, but can also promote subcritical debonding at significantly lower driving forces than in dry environments.

42 ENGINEERING↗
DOE OSTI2019

Vehicular Integration of Wireless Power Transfer Systems and Hardware Interoperability Case Studies

Several wireless charging methods are under development or available as an aftermarket option in the light-duty automotive market. However, there are not a sufficient number of studies detailing the vehicle integration methods, particularly a complete vehicle integration with higher power levels. This paper presents the design, development, implementation, and vehicle integration of wireless power transfer (WPT)-based electric vehicle (EV) charging systems for various test vehicles. Before having the standards effective, it is expected that WPT technology first will be integrated as an aftermarket retrofitting approach. Inclusion of this technology on production vehicles is contingent upon the release of the international standards. The power stages of the system are introduced with the design specifications and control systems including the active front-end rectifier with power factor correction, high frequency power inverter, high frequency isolation transformer, coupling coils, vehicle side full-bridge rectifier and filter, and the vehicle battery. The operating principles of the control, and communications, systems are presented. Aftermarket conversion approaches including the WPT on-board charger (OBC) integration, WPT CHAdeMO integration, and WPT direct battery connection scenarios are described. Furthermore, the experiments are carried out using the integrated vehicles and the results obtained to demonstrate the system performance including the stage-by-stage efficiencies.

42 ENGINEERING↗
DOE OSTI2022

Power quality disturbances diagnosis: A 2D densely connected convolutional network framework

The fast and accurate diagnosis of power quality disturbances (PQD) aids in avoiding shutdowns and unnecessary procedures, concerning electric energy distribution systems. As such, a number of techniques have been tested and applied in order to reach this objective. Majority of the techniques applied are two-step based. On the first step, power quality disturbances features are extracted. Second step, considering features extracted, disturbance classification is implemented. Recently, relevant literature has presented data-driven signal processing-based approaches, as deep convolutional neural networks (DCNN), which can implement both processing steps while providing automated recognition of patterns and outliers in data. However, not considered by state-of-art, power quality disturbances are evolving in nature, while all possible regularities might not be represented in the dataset. In this work a 2 Dimension Densely Connected Convolutional Network (2D-DenseNet) framework is presented. Further, a case study with synthetic disturbance events are analyzed. Easy-to-implement formulation, built on the 2D-DenseNet, without hard-to-design parameters, highlight potential aspects for real-life implementation.

42 ENGINEERING↗
NASA NTRS2007

Electric Propulsion Interactions Code (EPIC): Recent Enhancements and Goals for Future Capabilities

The Electric Propulsion Interactions Code (EPIC) is the leading interactive computer tool for assessing the effects of electric thruster plumes on spacecraft subsystems. EPIC, developed by SAIC under the sponsorship of the Space Environments and Effects (SEE) Program at the NASA Marshall Space Flight Center, has three primary modules. One is PlumeTool, which calculates plumes of electrostatic thrusters and Hall-effect thrusters by modeling the primary ion beam as well as elastic scattering and charge-exchange of beam ions with thruster-generated neutrals. ObjectToolkit is a 3-D object definition and spacecraft surface modeling tool developed for use with several SEE Program codes. The main EPIC interface integrates the thruster plume into the 3-D geometry of the spacecraft and calculates interactions and effects of the plume with the spacecraft. Effects modeled include erosion of surfaces due to sputtering, re-deposition of sputtered materials, surface heating, torque on the spacecraft, and changes in surface properties due to erosion and deposition. In support of Prometheus I (JIMO), a number of new capabilities and enhancements were made to existing EPIC models. Enhancements to EPIC include adding the ability to scale and view individual plume components, to import a neutral plume associated with a thruster (to model a grid erosion plume, for example), and to calculate the plume from new initial beam conditions. Unfortunately, changes in program direction have left a number of desired enhancements undone. Variable gridding over a surface and resputtering of deposited materials, including multiple bounces and sticking coefficients, would significantly enhance the erosion/deposition model. Other modifications such as improving the heating model and the PlumeTool neutral plume model, enabling time dependent surface interactions, and including EM1 and optical effects would enable EPIC to better serve the aerospace engineer and electric propulsion systems integrator. We review EPIC S overall capabilities and recent modifications, and discuss directions for future enhancements.

Gardner, Barbara M.↗
DOE OSTI2017

Korean Localization Program for Performance Verification Test of APR1400's RCP

The Korean government together with the Korean nuclear society completed the development of technologies for the design, manufacturing, and performance verification test of the APR1400's Reactor Coolant Pump (RCP) as one of the national programs for the localization of deficient nuclear technology. The RCP localization program was driven by KAERI, which was responsible for the development of the performance verification and evaluation technology, and by DOOSAN heavy industrial company, which was in charge of the design and manufacturing of the RCP. The test facility for the localized APR1400's RCP was constructed at the KAERI site at the end of 2012. The thermal hydraulic and electric capability of the RCP test facility (RCPTF) covers up to 18.5 MPa, 343 deg. C, 11.7 m{sup 3}/s, and 14.0 MW for the design pressure, temperature, flow rate, and maximum electric power, respectively. In 2013, a commissioning test was performed to verify its designed capability, followed by several modifications in the RCPTF including signal processing and control logic to enhance the verification and evaluation capability of the RCP performance. After finishing the commissioning and modification of the RCPTF, a type test for the new-type of RCP was performed successfully. In 2014 and 2015, eight production tests for the localized RCPs, which will be installed in a commercial nuclear power plant in Korea, were successfully completed. As a final stage of the localization program of the RCP, KAERI will perform a seal LOCA test to verify the leakage characteristics and produce experimental data on the localized seal assembly for a safety analysis during a station black out (SBO) condition. In this summary, several technical issues developed through a series of research processes for a performance verification test of the localized RCP are described.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1994

U.S. In-Space Electric Propulsion Experiments

Arcjet and ion propulsion offer potentially significant reductions in the mass of propulsion systems required for Earth orbiting satellites and planetary spacecraft. For this reason, they have been the subject of validation and demonstration programs. After examining the benefits of electric propulsion, this paper discusses the technology base for the Electric propulsion Space Experiment (ESEX) arcjet demonstration experiment and the NASA SEP Technology Application Readiness (NSTAR) ion propulsion validation program. As part of the Advanced Research and Global Observation Spacecraft (ARGOS), ESEX will perform ten 15-minute firings of a 30 kW ammonia arcjet. NASA's validation program, NSTAR, consists of two major elements: a ground-test element and an in-space experiment. The ground-test element will validate the life, intergrability, and performance of low-power ion propulsion. The in-space element will demonstrate the feasibility of integrating and flying an ion propulsion system. The experiment will measure the interactions among the ion propulsion system, the host spacecraft, and the surrounding space plasma; and it will provide a quantitative assessment of the ability of ground testing to replicate the in-space performance of ion thrusters. By involving industry in NSTAR, a commercial source for this technology will be ensured. Furthermore, the successful completion of the NSTAR validation program will stimulate commercial and government (both civilian and military) uses of this technology.

arcjet↗
DOE OSTI2020

High-speed imaging of transition from fluid breakup to phase explosion in electric explosion of tungsten wires in air

High-speed visible imaging of sub-microsecond electric explosion of wires at the low specific energy deposition threshold reveals three distinct modes of wire failure as capacitor charge voltage and energy deposition are increased. For 100 micron diameter gold-plated tungsten wires of 2 cm length, deposited energies of 1.9 eV/atom produces a liquid column that undergoes hydrodynamic breakup into droplets with radii of order of wire diameter on timescales of 200 μs. Instability growth, column breakup, and droplet coalescence follow classic Rayleigh-Plateau predictions for instability of viscous fluid column. Above 3.2 eV/atom of deposited energy, wires are seen to abruptly transition to an expanding mixture of micron scale liquid-droplets and vapor within one frame (less than 3.33 μs), which has been termed ‘phase explosion’ in literature. Between these two limits, at 2.5 eV/atom of deposited energy, wire radius is unchanged for the first 10 μs before the onset of a rapid expansion and disintegration that resembles homogenous nucleation of mechanically unstable bubbles. Here, thermodynamic calculations are presented that separate cases by temperature obtained during heating: below boiling point, near boiling point, and exceeding boiling point.

42 ENGINEERING↗
DOE OSTI2018

Metal Amorphous Nanocomposite Soft Magnetic Material-Enabled High Power Density, Rare Earth Free Rotational Machines [Metal Amorphous Nanocomposite (MANC) Soft Magnetic Material (SMM) Enabled High Power Density, Rare Earth Free Rotational Machines]

Metal amorphous nanocomposites (MANCs) are promising soft magnetic materials (SMMs) for power electronic applications offering low power loss at high frequency and maintaining a relatively high flux density. While applications in certain motor designs have been recently modeled, their widespread application awaits scaled manufacturing of MANC materials and proliferation of new higher speed motor designs. A hybrid motor design based on permanent magnets and doubly salient stator and rotor is reported here to develop a compact (a factor of 10 smaller than currently possible in Si steels), high-speed (>1 kHz, electrical), high-power (>2.5 kW) motor by incorporating low loss (<10 W/kg at 1 kHz) MANCs such as recently reported Fe-Ni-based alloys. A feature of this motor design is flux focusing from the permanent magnet allowing use of lower energy permanent magnet chosen from among non-rare earth containing compositions and attractive due to constraints posed by rare earth criticality. A 2-D finite element analysis model reported here indicates that a 2.5 kW hybrid motor may be built with a permanent magnet with a 0.4 T remanence at a rotor speed of 6000 rpm. At a magnetic switching frequency of 1.4 kHz, the core loss may be limited to <3 W by selecting an appropriate MANC SMM. The projected efficiency exceeds 96% not including power loss in the controller. Under full load conditions, the flux density distributions for the SMM stay predominantly <1.3 T, the saturation magnetization of optimized FeNi-based MANC alloys. As a result, the maximum demagnetizing field in the permanent magnet is less than 2.2 × 10 5 A/m sustainable, for example, with a high-grade hard ferrite magnet.

42 ENGINEERING↗
NASA NTRSDate not supplied

Utilizing Electrical Power Extraction for Stability Bleed Reduction within Gas Turbine Engines

This paper studies the role of power extraction in gas turbine stability and how an engine may be designed to utilize this extraction to replace engine stability bleed requirements with electrical system requirements. The considered engine architecture contains two engine spools and a power turbine spool. In the baseline, low-pressure compressor stall margin is maintained by bleed air from the back of the low-pressure compressor, which is then dumped to the bypass. Power extraction from the high-pressure and low-pressure shafts are then utilized as a replacement for this bleed. This study considers component performance, sizing, efficiency, and operability, but does not consider weight or cost. Analysis within this paper is general and the concepts could be applied to other dual spool engine types, including a turbofan. Results show it is possible to completely remove the stability bleed between the low pressure and high-pressure compressor by utilizing a 35% power extraction from the high-pressure shaft or a 1.5% power extraction from the low-pressure turbine.

Gas Turbine↗
NASA NTRSDate not supplied

Utilizing Electrical Power Extraction for Stability Bleed Reduction within Gas Turbine Engines

This paper studies the role of power extraction in gas turbine stability and how an engine may be designed to utilize this extraction to replace engine stability bleed requirements with electrical system requirements. The considered engine architecture contains two engine spools and a power turbine spool. In the baseline, low-pressure compressor stall margin is maintained by bleed air from the back of the low-pressure compressor, which is then dumped to the bypass. Power extraction from the high-pressure and low-pressure shafts are then utilized as a replacement for this bleed. This study considers component performance, sizing, efficiency, and operability, but does not consider weight or cost. Analysis within this paper is general and the concepts could be applied to other dual spool engine types, including a turbofan. Results show it is possible to completely remove the stability bleed between the low pressure and high-pressure compressor by utilizing a 35% power extraction from the high-pressure shaft or a 1.5% power extraction from the low-pressure turbine.

Gas Turbine↗
DOE OSTI2019

A 50-kW Three-Phase Wireless Power Transfer System Using Bipolar Windings and Series Resonant Networks for Rotating Magnetic Fields

The mass and volume of wireless power transfer (WPT) systems for charging electric vehicles are directly related to the rated power of the system. The difficulties of high-power wireless charging are exacerbated by the need to meet the same practical constraints associated with vehicle integration as lower power systems. Therefore, more advanced techniques are necessary to improve power density and specific power of wireless charging systems for high-power applications. This article presents theory and analysis of three-phase inductive WPT systems with bipolar phase windings. Magnetic coupler topologies and the theoretical and practical aspects of series three-phase resonant compensation networks are discussed. The systems under consideration are designed to utilize rotating magnetic fields to achieve a power transfer characteristic that is temporally smoother than single-phase systems. Other benefits associated with rotating magnetic field based WPT, including reduced ferrite mass, filter component requirements, and electromagnetic field emissions, are discussed. Experimental results of a prototype system are presented in both aligned and misaligned configurations. The system is demonstrated transferring 50 kW with 95% dc-to-dc efficiency over a 150-mm airgap in the aligned case. On a per-pad basis, the magnetic couplers achieve a power density of 195 kW/m 2 and a specific power of 3.65 kW/kg. Finally this article is accompanied by a video of the rotating magnetic field produced by a simulated three-phase WPT system.

42 ENGINEERING↗