Search NASA⌕ Search

SEARCH · Search NASA

Results for “energy efficiency measures”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Numerical performance estimates for a generic hypersonic forebody

The computation of a hypersonic flow past the forebody of a hypersonic vehicle is analyzed for two sets of flow conditions: the first represents flow conditions of an experimental test of the model in the Calspan 96-inch shock tunnel, and the second set is chosen to represent actual flight conditions. Solutions are derived for sharp- and blunt-nose versions of the geometry in order to understand the effects of the entropy layer on the forebody pressure and heat transfer rates. Some sensitivity of predicted heating rates to grid refinement is observed, but it is found to be small compared to the effects of bluntness. Real-gas effects are studied for the blunt-nose version at flight-like conditions, and these effects are found to have a significant effect on inlet-face performance measures such as mass capture and kinetic energy efficiency.

Lawrence, Scott L.↗
NASA NTRS1999

On the Unusually High Temperature of the Cluster of Galaxies 1E 0657-56

A recent X-ray observation of the cluster 1E 0657-56 (z = 0.296) with ASC,4 implied an unusually high temperature of approx. 17 keV. Such a high temperature would make it the hottest known cluster and severely constrain cosmological models since, in a Universe with critical density (Omega = 1) the probability of observing such a cluster is only approx. 4 x 10(exp -5). Here we test the robustness of this observational result since it has such important implications. We analysed the data using a variety of different data analysis methods and spectral analysis assumptions and find a temperature of approx. 11 - 12 keV in all cases, except for one class of spectral fits. These are fits in which the absorbing column density is fixed at the Galactic value. Using simulated data for a 12 keV cluster, we show that a high temperature of approx. 17 keV is artificially obtained if the true spectrum has a stronger low-energy cut-off than that for Galactic absorption only. The apparent extra absorption may be astrophysical in origin, (either intrinsic or line-of-sight), or it may be a problem with the low-energy CCD efficiency. Although significantly lower than previous measurements, this temperature of kT approx. 11 - 12 keV is still relatively high since only a few clusters have been found to have temperatures higher than 10 keV and the data therefore still present some difficulty for an Omega = 1 Universe. Our results will also be useful to anyone who wants to estimate the systematic errors involved in different methods of background subtraction of ASCA data for sources with similar signal-to-noise to that of the IE 0657-56 data reported here.

Yaqoob, Tahir↗
NASA NTRS1979

An Energy Saver Called NECAP

One of the most comprehensive and most effective programs is NECAP, an acronym for NASA Energy Cost Analysis Program. Developed by Langley Research Center, NECAP operates according to heating/cooling calculation procedures formulated by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE). The program enables examination of a multitude of influences on heat flow into and out of buildings. For example, NECAP considers traditional weather patterns for a given locale and predicts the effects on a particular building design of sun, rain, wind, even shadows from other buildings. It takes into account the mass of structural materials, insulating values, the type of equipment the building will house, equipment operating schedules, heat by people and machinery, heat loss or gain through windows and other openings and a variety of additional details. NECAP ascertains how much energy the building should require ideally, aids selection of the most economical and most efficient energy systems and suggests design and operational measures for reducing the building's energy needs. Most importantly, NECAP determines cost effectiveness- whether an energy-saving measure will pay back its installation cost through monetary savings in energy bills. thrown off

Source record↗
NASA NTRS2010

Heating-Rate-Coupled Model for Hydrogen Reduction of JSC-1A

A previously developed and validated model for hydrogen reduction of JSC-1A for a constant reaction-bed temperature is extended to account for reaction during the bed heat-up period. A quasisteady approximation is used wherein an expression is derived for a single average temperature of reaction during the heat-up process by employing an Arrhenius expression for regolith conversion. Subsequently, the regolith conversion during the heat-up period is obtained by using this representative temperature. Accounting for the reaction during heat-up provides a better estimate of the reaction time needed at the desired regolith-bed operating temperature. Implications for the efficiency of the process, as measured by the energy required per unit mass of oxygen produced, are also indicated.

Hegde, U.↗
NASA NTRS2001

Quantitative Detection of Combustion Species using Ultra-Violet Diode Lasers

Southwest Sciences is developing a new microgravity combustion diagnostic based on UV diode lasers. The instrument will allow absolute concentration measurements of combustion species on a variety of microgravity combustion platforms including the Space Station. Our approach uses newly available room temperature UV diode lasers, thereby keeping the instrument compact, rugged and energy efficient. The feasibility of the technique was demonstrated by measurement of CH radicals in laboratory flames. Further progress in fabrication technology of UV diode lasers at shorter wavelengths and higher power will result in detection of transient species in the deeper UV. High sensitivity detection of combustion radicals is provided with wavelength modulation absorption spectroscopy.

Pilgrim, J. S.↗
NASA NTRS2002

Experimental Test Results of the Energy Efficient Transport (EET) Flap-Edge Vortex Model in the Langley Low-Turbulence Pressure Tunnel

This report presents the results of a test conducted in the Langley Low-Turbulence Pressure Tunnel to measure the flow field properties of a flap-edge vortex. The model was the EET (Energy Efficient Transport) Flap-Edge Vortex Model, which consists of a main element and a part-span, single-slotted trailing-edge flap. The model surface was instrumented with several chordwise and spanwise rows of pressure taps on each element. The off-body flow field velocities were to be measured in several planes perpendicular to the flap edge with a laser velocimetry system capable of measuring all three components in coincidence. However, due to seeding difficulties, the preliminary laser data did not have sufficient accuracy to be suitable for presentation; therefore, this report presents only the tabulated and plotted surface pressure data. In addition, the report contains a detail description of the model which can be used to generate accurate CFD grid structures.

Morgan, Harry L., Jr.↗
NASA NTRS1999

High Efficiency End-Pumped Ho:Tm:YLF Disk Amplifier

Space based coherent lidar for global wind measurement requires an all solid state laser system with high energy, high efficiency and narrow linewidth that operates in the eye safe region. A Q-switched, diode pumped Ho:Tm:YLF 2 micrometer laser with output energy of as much as 125 mJ at 6 Hz with an optical-to-optical efficiency of 3% has been reported. Single frequency operation of the laser was achieved by injection seeding. The design of this laser is being incorporated into NASA's SPARCLE (SPAce Readiness Coherent Lidar Experiment) wind lidar mission. Laser output energy ranging from 500 mJ to 2 J is required for an operational space coherent lidar. We previously developed a high energy Ho:Tm:YLF master oscillator and side pumped power amplifier system and demonstrated a 600-mJ single frequency pulse at a repetition rate of 10 Hz. Although the output energy is high, the optical-to-optical efficiency is only about 2%. Designing a high energy, highly efficient, conductively cooled 2-micrometer laser remains a challenge. In this paper, the preliminary result of an end-pumped amplifier that has a potential to provide a factor 3 of improvement in the system efficiency is reported.

Yu, Jirong↗
NASA NTRS1999

The Near-Earth Asteroid Rendezvous (NEAR) Mission, the Mars Surveyor 2001 (MS01) Mission, and the Planetary Instrument Definition and Development Program (PIDDP)

The NEAR Mission was launched on February 17, 1996 for a three year cruise to the asteroid 433 Eros. During October, November, and December 1998 cruise measurements with the gamma-ray spectrometer were made at three different escape-window-width settings. These were done in order to understand how the count rate and peak width change as the window width settings change. Analysis of these spectra was completed using the latest version of the spectral analysis program, RobWin. Results as a function of energy were combined with the results from the Schlumberger-Doll Research experiments (described below). Laboratory measurements were needed to confirm efficiency calculations above 6 MeV and to understand the relationship between the full energy peak areas and the areas of the first and second escape peaks as a function of the escape peak widths. A week of measurements was made at Schlumberger-Doll Research using their 14-MeV pulsed neutron generator and large soil samples. Data were collected after adding iron and nickel to the sample to increase the emission of high-energy lines. Approximately 24 hours of data were accumulated at each of three escape peak window widths. These data were analyzed with RobWin. Combining results from the cruise measurements and the laboratory measurements indicated that both data sets had similar energy dependence and that this energy dependence was different from that obtained using standard Monte Carlo calculations. Alternate methods of simulating the response of the detector to changes in the escape window widths are being investigated.

Source record↗
NASA NTRS1986

Development of high-efficiency solar cells on silicon web

Work is reported aimed at identifying and reducing sources of carrier recombination both in the starting web silicon material and in the processed cells. Cross-sectional transmission electron microscopy measurements of several web cells were made and analyzed. The effect of the heavily twinned region on cell efficiency was modeled, and the modeling results compared to measured values for processed cells. The effects of low energy, high dose hydrogen ion implantation on cell efficiency and diffusion length were examined. Cells were fabricated from web silicon known to have a high diffusion length, with a new double layer antireflection coating being applied to these cells. A new contact system, to be used with oxide passivated cells and which greatly reduces the area of contact between metal and silicon, was designed. The application of DLTS measurements to beveled samples was further investigated.

Meier, D. L.↗
NASA NTRS1986

The cosmic ray spectrum above 10(19) EV at Volcano Ranch and Haverah Park

The cosmic ray energy per particle spectrum above 10 to the 19th power eV is measured the same way that energy spectra are measured at much lower energies, by counting all of the particles in a specified energy range that are incident per unit time with trajectories within specified geometrical limits. Difficulties with background or poorly known detection efficiency are markedly less than in some other cosmic ray measurements. The fraction of primary energy given to muons, neutrinos, and slow hadrons is less than 10% in this region, so the primary energy equals the track length integral of the secondary electrons with only a small correction for the energy given to other kinds of particles. Results from Volcano Ranch and Haverah Park are compared with results from the Yakutsk experiment.

Linsley, J.↗
NASA NTRS1987

Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. I - Measurement and analysis technique

This two-part paper presents laser anemometer measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan. The objective is to provide additional insight into unsteady blade-row interactions within highspeed compressors which affect stage efficiency, energy transfer, and other design considerations. Part 1 describes the measurement and analysis techniques used for resolving the unsteady flow field features. The ensemble-average and variance of the measured velocities are used to identify the rotor wake generated and unresolved unsteadiness, respectively. (Rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and the term unresolved unsteadiness refers to all remaining contributions to unsteadiness such as vortex shedding, turbulence, mass flow fluctutions, etc.). A procedure for calculating auto and cross correlations of the rotor wake generated and unresolved unsteady velocity fluctuations is described. These unsteady-velocity correlations have significance since they also result from a decomposition of the Navier-Stokes equations. This decomposition of the Navier-Stokes equations resulting in the velocity correlations used to describe the unsteady velocity field will also be outlined in this paper.

Suder, K. L.↗
NASA NTRS1987

Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. 1: Measurement and analysis technique

This two-part paper presents laser anemometer measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan. The objective is to provide additional insight into unsteady blade-row interactions within high speed compressors which affect stage efficiency, energy transfer, and other design considerations. Part 1 describes the measurement and analysis techniques used for resolving the unsteady flow field features. The ensemble-average and variance of the measured velocities are used to identify the rotor wake generated and unresolved unsteadiness, respectively. (Rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and the term unresolved unsteadiness refers to all remaining contributions to unsteadiness such as vortex shedding, turbulence, mass flow fluctuations, etc.). A procedure for calculating auto and cross correlations of the rotor wake generated and unresolved unsteady velocity fluctuations is described. These unsteady-velocity correlations have significance since they also result from a decomposition of the Navier-Stokes equations. This decomposition of the Navier-Stokes equations resulting in the velocity correlations used to describe the unsteady velocity field will also be outlined in this paper.

Suder, K. L.↗
NASA NTRS2003

Development of High Resolution Hard X-Ray Telescope with Multilayer Coatings

The activities that occurred during the first year of the grant were: a) completed construction of the large multilayer deposition facility; b) Coated a large number of flat substrates and the interiors of cylindrical X-ray telescope shell substrates with uniform period and depth graded periods of tungsten-silicon (W/Is) bi-layers and other coatings; c) studied the influence of various factors affecting the quality of the multilayer coatings by measuring their reflection efficiency at 8 keV and higher energy X-rays.

Gorenstein, Paul↗
NASA NTRSDate not supplied

A GeV to TeV view of shell-type SNRs

Shock acceleration by the shells of supernova remnants (SNRs) has been hypothesized to be the mechanism that produces the bulk of Galactic Cosmic Rays, possibly up to PeV energies. SomeSNRs have been shown to accelerate cosmic rays to TeV energies and above. But which SNRs are indeed efficient accelerators of protons and nuclei? And what is the maximum energy up to which they can efficiently accelerate particles? Measurements of non-thermal emission, especially in the gamma-ray regime, are essential to answer these questions.

A. U. Abeysekara↗
NASA NTRS1989

Laboratory investigations involving high-velocity oxygen atoms

Facilities for measuring material reactive characteristics have been under development for several years and span the atom energy range from thermal to 5 eV, the orbital collision energy. One of the high-atom energy facilities (The High Intensity/Energy Atomic Oxygen Source) capable of simulating the reactive part of LEO is described, along with results of beam characterization and preliminary material studies. The oxygen atom beam source was a continuous wave plasma produced by focusing a high-power CO2 laser through a lens system into a rare gas/molecular oxygen mixture chamber at elevated temperature. Material samples were exposed to the high velocity beam through an external feedthrough. The facility showed good stability in continued operation for more than 100 hours, producing fluences of 10 to the 21st to 10 to the 22nd atoms/sq cm. Reaction efficiencies and surface morphology have been measured for several materials at energies of 1.5 and 2.8 eV, matching with data generated from previous space flights. Activation energies for carbon and Kapton as measured in this facility were 800 cal/mole.

Leger, Lubert J.↗
NASA NTRS2000

Percussive Force Magnitude in Permafrost

An in-depth look at percussive drilling shows that the transmission efficiency is very important; however, data for percussive drilling in hard rock or permafrost is rarely available or the existing data are very old. Transmission efficiency can be used as a measurement of the transmission of the energy in the piston to the drill steel or bit and from the bit to the rock. Having a plane and centralized impact of the piston on the drill steel can optimize the transmission efficiency from the piston to the drill steel. A transmission efficiency of near 100% between piston and drill steel is possible. The transmission efficiency between bit and rock is dependent upon the interaction within the entire system. The main factors influencing this transmission efficiency are the contact area between cutting structure and surrounding rock (energy loss due to friction heat), damping characteristics of the surrounding rock (energy dampening), and cuttings transport. Some of these parameters are not controllable. To solve the existing void regarding available drilling data, an experiment for gathering energy data in permafrost for percussive drilling was designed. Fifteen artificial permafrost samples were prepared. The samples differed in the grain size distribution to observe a possible influence of the grain size distribution on the drilling performance. The samples were then manually penetrated (with a sledge-hammer) with two different spikes.

Eustes, A. W., III↗
NASA NTRS2017

Lightning Imaging Sensor (LIS) on the International Space Station (ISS): Launch, Installation, Activation and First Results

Mission: Fly a flight-spare LIS (Lightning Imaging Sensor) on ISS to take advantage of unique capabilities provided by the ISS (e.g., high inclination, real time data); Integrate LIS as a hosted payload on the DoD Space Test Program-Houston 5 (STP-H5) mission and launch on a Space X rocket for a minimum 2 year mission. Measurement: NASA and its partners developed and demonstrated effectiveness and value of using space-based lightning observations as a remote sensing tool; LIS measures lightning (amount, rate, radiant energy) with storm scale resolution, millisecond timing, and high detection efficiency, with no land-ocean bias. Benefit: LIS on ISS will extend TRMM (Tropical Rainfall Measuring Mission) time series observations, expand latitudinal coverage, provide real time data to operational users, and enable cross-sensor calibration.

LIS↗
NASA NTRS1979

Quantitative energy extraction measurements in a photoionization-stabilized self-sustained XeF laser

Detailed time-correlated gain, fluorescence, and laser energy measurements were used to obtain quantitative data on energy extraction efficiencies for a photoionization-stabilized self-sustained XeF laser. A current pulse of 25 ns full width at half-maximum produced an 80-cu-cm XeF plasma in NF3:Xe:He gas mixtures with a maximum output energy of 80 mJ. The results show that the maximum small-signal gain and the maximum specific output energy is proportional to the NF3 content of the gas mixture. This suggests that there is an optimum fractional utilization of the NF3 molecules in the discharge. Under high-gain conditions, 30-40% of the energy stored in XeF(asterisk) can be extracted in a gain-switched pulse. The output energy represents less than 1% of the input energy.

Lee, C. M.↗