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At least 109 records · Page 6

All sources NASA NTRS DOE OSTI

NASA NTRS1977

Skylab water balance analysis

The water balance of the Skylab crew was analyzed. Evaporative water loss using a whole body input/output balance equation, water, body tissue, and energy balance was analyzed. The approach utilizes the results of several major Skylab medical experiments. Subsystems were designed for the use of the software necessary for the analysis. A partitional water balance that graphically depicts the changes due to water intake is presented. The energy balance analysis determines the net available energy to the individual crewman during any period. The balances produce a visual description of the total change of a particular body component during the course of the mission. The information is salvaged from metabolic balance data if certain techniques are used to reduce errors inherent in the balance method.

Leonard, J. I.↗

NASA NTRS1995

Electron energy transport in the solar wind: Ulysses observations

The electron heat flux in the solar wind has been measured by the Ulysses solar wind plasma experiment in the ecliptic from 1 to 5 AU and out of the ecliptic during the recently completed pass over the solar south pole and the ongoing pass over the solar north pole. Although the electron heat flux contains only a fraction of the kinetic energy of the solar wind. the available energy is sufficient to account for the non-adiabatic expansion of the solar wind electrons. The Ulysses measurements indicate that the electron heat flux is actively dissipated in the solar wind. The exact mechanism or mechanisms is unknown. but a model based on the whistler heat flux instability predicts radial gradients for the electron heat flux in good agreement with the data. We will present measurements of the correlation between wave activity measured by the unified radio and plasma experiment (URAP) and the electron heat flux throughout the Ulysses mission. The goal is to determine if whistler waves are a good candidate for the observed electron heat flux dissipation. The latitudinal gradients of the electron heat flux. wave activity. and electron pressure will be discussed in light of the changes in the magnetic field geometry from equator to poles.

Scime, Earl↗

DOE OSTI2024

Research Highlight - Dispatch Optimization, System Design and Cost Benefit Analysis of a Nuclear Reactor with Molten Salt Thermal Storage

We highlight our work from our previous publication titled "Dispatch Optimization, System Design, and Cost Benefit Analysis of a Nuclear Reactor with Molten Salt Thermal Storage" published in MDPI Energies 2022 (doi.org/10.3390/en15103599). Variable renewable energy availability has increased the volatility in energy prices in most markets. Nuclear power plants, with a large ratio of capital to variable costs, have historically operated as base load energy suppliers but the need for more flexible operation is increasing. We simulate the techno-economic performance of a 950 MWt nuclear power plant, based on the Westinghouse lead-cooled fast reactor, coupled with molten salt thermal storage as a method for flexible energy dispatch. We use the System Advisor Model to model the nuclear reactor thermal power input and power cycle operating modes. We combine this robust engineering model with a mixed-integer linear program model for optimized dispatch scheduling. We then simulate the coupled nuclear and thermal storage system under different market scenarios with varying price volatility. We find that the coupled plant outperforms the base plant under markets where energy price peaks fluctuate by a factor of two or more about the mean price. We show that a calculated power purchase agreement price for the plant improves by up to 10% when operating under California energy market conditions. Sensitivity analysis on the thermal storage cost shows that the optimal design remains unchanged even when doubling costs.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2026

First inclusive triple-differential measurement of the muon-antineutrino charged-current cross section using the NOvA Near Detector

We present the first measurement of the triple-differential muon antineutrino charged-current inclusive cross section, using the NOvA Near Detector and $12.5 \times 10^{20}$ protons on target in the NuMI beam. This sample of muon antineutrino interactions is the largest ever published, with approximately 1 million selected muon antineutrino events. The triple-differential cross section is measured in the final-state kinetic energy, the scattering angle, and the available energy of the interaction. The measurement enables phase-space regions populated by differing neutrino reaction processes to be isolated and the transition regions between them to be defined. The results are compared with the predictions of the main event generators used in the neutrino community and we observe energy- and angle-dependent discrepancies across a broad range of energies and interaction types

Abubakar, S. [Erciyes U.]↗

NASA NTRS1986

Example of Second-Law efficiency of solar-thermal cavity receivers

Properly quantified performance of a solar-thermal cavity receiver must not only account for the energy gains and losses as dictated by the First Law of thermodynamics, but it must also account for the quality of the energy. Energy quality can only be determined from the Second Law. In this paper, an equation developed for the Second-Law efficiency of a cavity receiver is presented as an evolution from the definition of available energy or availability (occasionally called exergy). The variables required are all either known or readily determined. The importance of considering the Second-Law is emphasized by a comparison of the First- and Second-Law efficiencies around an example of data collected from two receivers that were designed for different purposes, where the attempt was made to demonstrate that a Second-Law approach to quantifying the performance of a solar-thermal cavity receiver lends more complete insight than does the conventional solely applied First-Law approach.

Moynihan, P. I.↗

NASA NTRS1990

Auroral precipitation flux of ions and electrons in Saturn's outer magnetosphere

This paper examines particles and fields data obtained by Voyager in Saturn's outer magnetosphere with a view toward assessing the role that medium-energy ions and electrons have in stimulating the UV aurora. The magnetic field displays a high level of fluctuation of two characteristic types: large-scale coherent depressions in the field strength associated with the plumes of Titan and a small-scale incoherent turbulence presumed to be a consequence of the high-beta plasma environment. Electrons are assumed to interact strongly with lower hybrid waves and are accelerated to energies of a few kiloelectron volts. The available energy input to the aurora by protons is 5 x 10 to the 9th W, while an upper bound to that of N(+) ions is about 2 x 10 to the 10th W. Electrons in the range 1-10 keV can contribute upward of 5 x 10 to the 10th W and perhaps more if a field-aligned potential drop above the aurora is present. It is concluded that electrons are most likely the primary precipitation energy source for the aurora as a result of energy transfer from Titanogenic N(+) pickup ions in a corotation-dominated magnetosphere.

Barbosa, D. D.↗

NASA NTRS2017

Estimating Evaporative Fraction From Readily Obtainable Variables in Mangrove Forests of the Everglades, U.S.A.

A remote-sensing-based model to estimate evaporative fraction (EF) the ratio of latent heat (LE; energy equivalent of evapotranspiration -ET-) to total available energy from easily obtainable remotely-sensed and meteorological parameters is presented. This research specifically addresses the shortcomings of existing ET retrieval methods such as calibration requirements of extensive accurate in situ micro-meteorological and flux tower observations, or of a large set of coarse-resolution or model-derived input datasets. The trapezoid model is capable of generating spatially varying EF maps from standard products such as land surface temperature [T(sub s)] normalized difference vegetation index (NDVI)and daily maximum air temperature [T(sub a)]. The 2009 model results were validated at an eddy-covariance tower (Fluxnet ID: US-Skr) in the Everglades using T(sub s) and NDVI products from Landsat as well as the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors. Results indicate that the model accuracy is within the range of instrument uncertainty, and is dependent on the spatial resolution and selection of end-members (i.e. wet/dry edge). The most accurate results were achieved with the T(sub s) from Landsat relative to the T(sub s) from the MODIS flown on the Terra and Aqua platforms due to the fine spatial resolution of Landsat (30 m). The bias, mean absolute percentage error and root mean square percentage error were as low as 2.9% (3.0%), 9.8% (13.3%), and 12.1% (16.1%) for Landsat-based (MODIS-based) EF estimates, respectively. Overall, this methodology shows promise for bridging the gap between temporally limited ET estimates at Landsat scales and more complex and difficult to constrain global ET remote-sensing models.

trapezoid↗

NASA NTRS1980

Deep space network energy program

If the Deep Space Network is to exist in a cost effective and reliable manner in the next decade, the problems presented by international energy cost increases and energy availability must be addressed. The Deep Space Network Energy Program was established to implement solutions compatible with the ongoing development of the total network.

Friesema, S. E.↗

NASA NTRS1989

Surface energy and radiation balance systems - General description and improvements

Surface evaluation of sensible and latent heat flux densities and the components of the radiation balance were desired for various vegetative surfaces during the ASCOT84 experiment to compare with modeled results and to relate these values to drainage winds. Five battery operated data systems equipped with sensors to determine the above values were operated for 105 station days during the ASCOT84 experiment. The Bowen ratio energy balance technique was used to partition the available energy into the sensible and latent heat flux densities. A description of the sensors and battery operated equipment used to collect and process the data is presented. In addition, improvements and modifications made since the 1984 experiment are given. Details of calculations of soil heat flow at the surface and an alternate method to calculate sensible and latent heat flux densities are provided.

Fritschen, Leo J.↗

NASA NTRS1991

Inelastic and reactive scattering of hyperthermal atomic oxygen from amorphous carbon

The reaction of hyperthermal oxygen atoms with an amorphous carbon-13 surface was studied using a modified universal crossed molecular beams apparatus. Time-of-flight distributions of inelastically scattered O-atoms and reactively scattered CO-13 and CO2-13 were measured with a rotatable mass spectrometer detector. Two inelastic scattering channels were observed, corresponding to a direct inelastic process in which the scattered O-atoms retain 20 to 30 percent of their initial kinetic energy and to a trapping desorption process whereby O-atoms emerge from the surface at thermal velocities. Reactive scattering data imply the formation of two kinds of CO products, slow products whose translational energies are determined by the surface temperature and hyperthermal (Approx. 3 eV) products with translational energies comprising roughly 30 percent of the total available energy (E sub avl), where E sub avl is the sum of the collision energy and the reaction exothermicity. Angular data show that the hyperthermal CO is scattered preferentially in the specular direction. CO2 product was also observed, but at much lower intensities than CO and with only thermal velocities.

Minton, Timothy K.↗

NASA NTRS1982

Middle infrared remote sensing for geology

The middle infrared portion of the spectrum available for geologic remote sensing extends from approximately 3 to 25 micrometers. The source of energy is thermal radiation from surface materials and ambient terrestrial temperatures. The spectral range of usefulness is limited by both the amount of energy available and by transmission of energy through the atmosphere. The best atmospheric window lies between about 8 and 14 micrometers. Remote sensing of the Earth in the infrared is just on the threshold of becoming a valuable geologic tool. Topics which need study include: (1) the used and limitations of the 8 to 14 micrometer region for distinguishing between silicates and nonsilicates; (2) theoretical and experimental understanding of laboratory spectra of rocks and minerals and their relationship to remotely sensed emission spectra; and (3) the possible use of the 3 to 5 and 17 to 25 micrometer portions of the spectrum for remote sensing.

Kahle, A. B.↗

DOE OSTI2025

A Comparison of Electronic Structure Methods for Predicting the Hydrogenation Energies of Candidate Molecules for Hydrogen Storage

The development of novel energy materials and fuels is required to expand current available energy sources. Aiming to reach this goal, there is growing interest in using molecular hydrogen as an energy carrier due to its abundance and high energy density. Liquid organic hydrogen carriers (LOHCs) are a promising route to the large-scale storage and transport of hydrogen for use in the energy economy. The search for thermodynamically viable LOHC molecules for real world use has led to a set of constraints on the dehydrogenation enthalpy and the minimum gravimetric hydrogen capacity. These constraints allow one to formulate the search for an ideal LOHC candidate molecule as an optimization problem well suited to the strengths of machine learning and artificial intelligence computational approaches. A critical barrier to a large-scale, high-throughput screening of LOHC candidate molecules is the lack of reliable training data. Computational electronic structure methods including density functional theory, coupled cluster approximations, and diffusion Monte Carlo can be used to provide training data where experimental data are either unreliable or do not exist. In this work, we use these methods to calculate the dehydrogenation energies and enthalpies of candidate LOHC molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Demonstration of 10+ hour energy storage with Φ1" laboratory size solid oxide iron–air batteries

Long duration electricity storage (LDES) with 10+ hour cycle duration is an economically competitive strategy to accelerate the penetration of renewable energy into the utility market. Unfortunately, none of the available energy storage technologies can meet the LDES requirements in terms of duration and cost. The newly emerged solid-oxide iron–air batteries (SOIABs) with energy-dense solid iron as an energy storage material have inherent advantages for LDES applications. Herein, we report for the first time the LDES capability of SOIABs even at a laboratory scale. We show that SOIABs with an Ir-catalyzed Fe-bed can achieve excellent energy density (625 W h kg –1 ), long cycle duration (12.5 h) and high round-trip efficiency (~90%) under LDES-related working conditions. Finally, given the excellent low-rate performance and the use of earth-abundant, low-cost Fe as an energy storage material, we conclude that the SOIAB is a well-suited battery technology for LDES applications.

25 ENERGY STORAGE↗

NASA NTRS1986

Acceleration of charged particles in magnetic reconnection Solar flares, the magnetosphere, and solar wind

A possible source of free energy available for accelerating charged particles is conversion of magnetic energy to particle energy in reconnecting magnetic fields. Recent simulations using test particles suggests that reconnection may efficiently accelerate particles to the maximum energies that are observed in several astrophysical contexts. A simple analytic formula is used in conjunction with the simulation results to predict the maximum energy achievable in a particular plasma environment with the result that in solar flares reconnection is capable of accelerating particles to several GeV. In magnetospheric substorms the predicted maximum can reach several hundred keV, and near magnetic sector crossings in the solar wind the maximum energy can approach 100 keV.

Goldstein, M. L.↗

NASA NTRS2017

Inter-Relationship Between Subtropical Pacific Sea Surface Temperature, Arctic Sea Ice Concentration, and the North Atlantic Oscillation in Recent Summers and Winters

The inter-relationship between subtropical western-central Pacific sea surface temperatures (STWCPSST), sea ice concentration in the Beaufort Sea (SICBS), and the North Atlantic Oscillation (NAO) are investigated for the last 37 summers and winters (1980-2016). Lag-correlation of the STWCPSST×(-1) in spring with the NAO phase and SICBS in summer increases over the last two decades, reaching r = 0.4-0.5 with significance at 5 percent, while winter has strong correlations in approximately 1985-2005. Observational analysis and the atmospheric general circulation model experiments both suggest that STWCPSST warming acts to increase the Arctic geopotential height and temperature in the following season. This atmospheric response extends to Greenland, providing favorable conditions for developing the negative phase of the NAO. SIC and surface albedo tend to decrease over the Beaufort Sea in summer, linked to the positive surface net shortwave flux. Energy balance considering radiative and turbulent fluxes reveal that available energy that can heat surface is larger over the Arctic and Greenland and smaller over the south of Greenland, in response to the STWCPSST warming in spring. XXXX Arctic & Atlantic: Positive upper-level height/T anomaly over the Arctic and Greenland, and a negative anomaly over the central-eastern Atlantic, resembling the (-) phase of the NAO. Pacific: The negative height/T anomaly over the mid-latitudes, along with the positive anomaly over the STWCP, where 1degC warming above climatology is prescribed. Discussion: It is likely that the Arctic gets warm and the NAO is in the negative phase in response to the STWCP warming. But, there are other factors (e.g., internal variability) that contribute to determination of the NAO phase: not always the negative phase of the NAO in the event of STWCP warming (e.g.: recent winters and near neutral NAO in 2017 summer).

Lim, Young-Kwon↗

NASA NTRS2001

Solar-Powered Refrigeration System

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure. and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

Ewert, Michael K.↗

NASA NTRS2002

Solar Powered Refrigeration System

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

Michael K Ewert↗

NASA NTRS2002

Solar-Powered Refrigeration System

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

Michael K Ewert↗