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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 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Arterial gas occlusions in operating heat pipes

The effect of noncondensable gases on high performance arterial heat pipes has been investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, have been used to postulate stability criteria for arterial heat pipes. Experimental observations of gas occlusions were made using a stainless steel heat pipe equipped with viewing ports, and the working fluids methanol and ammonia with the gas additives helium, argon, and xenon. Observations were related to gas transport models.

Saaski, E. W.↗
NASA NTRS1975

Investigation of low-latitude hydrogen emission in terms of a two-component interstellar gas model

High-resolution 21-cm hydrogen line observations at low galactic latitude are analyzed to determine the large-scale distribution of galactic hydrogen. Distribution parameters are found by model fitting, optical depth effects are computed using a two-component gas model suggested by the observations, and calculations are made for a one-component uniform spin-temperature gas model to show the systematic departures between this model and data obtained by incorrect treatment of the optical depth effects. Synthetic 21-cm line profiles are computed from the two-component model, and the large-scale trends of the observed emission profiles are reproduced together with the magnitude of the small-scale emission irregularities. Values are determined for the thickness of the galactic hydrogen disk between half density points, the total observed neutral hydrogen mass of the galaxy, and the central number density of the intercloud hydrogen atoms. It is shown that typical hydrogen clouds must be between 1 and 13 pc in diameter and that optical thinness exists on large-scale despite the presence of optically thin gas.

Baker, P. L.↗
NASA NTRS1975

Observations of the interstellar gas with the Copernicus satellite

Results are reviewed for Copernicus far-UV measurements of the absorption lines of H I, D I, H2, and heavier elements in the interstellar gas. Column densities along several lines of sight, as estimated from Ly-alpha absorption-line profiles, confirm that wide differences in the gas density are present in various directions. The measurement of interstellar D I implies an open universe unless alternate sources for this nuclide are found. Analysis of reddened stars for which the line of sight passes through one or more interstellar clouds indicates a depletion of several heavy elements in the gas. It is suggested that the depleted elements may be present in grains rather than molecules and that the intercloud medium may consist primarily of H II with a few small H I clouds.

Morton, D. C.↗
NASA NTRS1976

Heat pipe temperature control utilizing a soluble gas absorption reservior

A new gas-controlled heat pipe design is described which uses a liquid matrix reservior, or sponge, to replace the standard gas reservior. Reservior volume may be reduced by a factor of five to ten for certain gas-liquid combinations, while retaining the same level of temperature control. Experiments with ammonia, butane, and carbon dioxide control gases with methanol working fluid are discussed.

Saaski, E. W.↗
NASA NTRS1976

Conversion of laser energy to gas kinetic energy

Techniques for the gas phase absorption of laser radiation for ultimate conversion to gas kinetic energy are discussed. Particular emphasis is placed on absorption by the vibration rotation bands of diatomic molecules at high pressures. This high pressure absorption appears to offer efficient conversion of laser energy to gas translational energy. Bleaching and chemical effects are minimized and the variation of the total absorption coefficient with temperature is minimal.

Caledonia, G. E.↗
NASA NTRS1976

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 4: Open recuperated and bottomed gas turbine cycles

Open-cycle recuperated gas turbine plant with inlet temperatures of 1255 to 1644 K (1800 to 2500 F) and recuperators with effectiveness values of 0, 70, 80 and 90% are considered. A 1644 K (2500 F) gas turbine would have a 33.5% plant efficiency in a simple cycle, 37.6% in a recuperated cycle and 47.6% when combined with a sulfur dioxide bottomer. The distillate burning recuperated plant was calculated to produce electricity at a cost of 8.19 mills/MJ (29.5 mills/kWh). Due to their low capital cost $170 to 200 $/kW, the open cycle gas turbine plant should see duty for peaking and intermediate load duty.

Amos, D. J.↗
NASA NTRS1976

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 6: Closed-cycle gas turbine systems

Both recuperated and bottomed closed cycle gas turbine systems in electric power plants were studied. All systems used a pressurizing gas turbine coupled with a pressurized furnace to heat the helium for the closed cycle gas turbine. Steam and organic vapors are used as Rankine bottoming fluids. Although plant efficiencies of over 40% are calculated for some plants, the resultant cost of electricity was found to be 8.75 mills/MJ (31.5 mills/kWh). These plants do not appear practical for coal or oil fired plants.

Amos, D. J.↗
NASA NTRS1976

Hydrogen rich gas generator

A process and apparatus is described for producing a hydrogen rich gas by injecting air and hydrocarbon fuel at one end of a cylindrically shaped chamber to form a mixture and igniting the mixture to provide hot combustion gases by partial oxidation of the hydrocarbon fuel. The combustion gases move away from the ignition region to another region where water is injected to be turned into steam by the hot combustion gases. The steam which is formed mixes with the hot gases to yield a uniform hot gas whereby a steam reforming reaction with the hydrocarbon fuel takes place to produce a hydrogen rich gas.

Houseman, J.↗
NASA NTRS1976

Hydrogen rich gas generator

A process and apparatus is described for producing a hydrogen rich gas by introducing a liquid hydrocarbon fuel in the form of a spray into a partial oxidation region and mixing with a mixture of steam and air that is preheated by indirect heat exchange with the formed hydrogen rich gas, igniting the hydrocarbon fuel spray mixed with the preheated mixture of steam and air within the partial oxidation region to form a hydrogen rich gas.

Houseman, J.↗
NASA NTRS1975

On the equilibrium distribution of gas in clusters of galaxies

The hydrostatic-equilibrium solution for a polytropic gas in a cluster of galaxies has been calculated. The gas has a wider distribution than the galaxies. If the central gas density is 0.0008 particles/cu cm for gamma = 5/3 or 0.002 per cu cm for gamma = 1.35, the total X-ray emission from a model Coma cluster is equal to the observed emission. The spatial extent and spectrum for the source are also well-represented by the model if gamma = 1.35.

Lea, S. M.↗
NASA NTRS1976

Real gas scale effects on hypersonic laminar boundary-layer parameters including effects of entropy-layer swallowing

Inviscid and viscous (laminar boundary-layer) flow-field calculations under perfect gas hypersonic wind tunnel and equilibrium real gas flight conditions are presented for the windward centerline of the Rockwell International 139 Space Shuttle Orbiter at a 30-deg angle of attack. Correlation parameters for laminar boundary-layer edge quantities and surface heat transfer are developed which properly account for entropy-layer-swallowing effects under both real and perfect gas conditions. Some implications of the proposed correlation parameters on boundary-layer transition are discussed.

Adams, J. C., Jr.↗
NASA NTRS1976

An investigation of condensation heat transfer in a closed tube containing a soluble noncondensable gas

A more exact one-dimensional condensation heat transfer model for insoluble gases was developed and compared with experimental data. Modifications to this model to accommodate soluble gas behavior were also accomplished, and the effects on gas front behavior demonstrated. Analytical models for condensation heat transfer are documented, and an optical method used for measuring gas concentration profiles is outlined. Experimental data is then presented and interpreted.

Saaski, E. W.↗
NASA NTRS1976

An investigation of condensation heat transfer in a closed tube containing a soluble noncondensable gas

An exact one-dimensional condensation heat transfer model for insoluble gases has been developed and compared with experimental data. Modifications to this model to accommodate soluble gas behavior have also been accomplished, and the effects on gas front behavior demonstrated. Analytical models for condensation heat transfer are documented, and a novel optical method used for measuring gas concentration profiles is outlined.

Saaski, E. W.↗
NASA NTRS1976

The search for life on Mars - Viking 1976 gas changes as indicators of biological activity

The objective of the gas exchange experiment (GEX) in the Viking lander biology instrument package is to determine whether life exists in a 1-cc Martian soil sample delivered to it. The GEX is capable of maximum flexibility while protecting the indigenous organisms from exposure to physiologically incompatible medium. The discussion covers the biological premises implemented in the GEX, the requirements for the GEX M4 medium, the operational aspects of the incubation chamber, nonbiological and biological changes, and Antarctica soil experiment. Sources of biological gas changes are examined along with ways of differentiating biological gas changes from nonbiological ones. From cold incubation of low-frequency soils, it is concluded that decisive negative tests of GEX may require extended incubations beyond the nominal mission plan of 60 days, barring any outright information that negates the presence of life on Mars.

Oyama, V. I.↗
NASA NTRS1976

Gas interaction effects on lunar bonded particles and their implications

Results are reported for an experimental investigation of gas-interaction effects on different Apollo 11 and Apollo 12 lunar-soil samples containing bonded particles. In the experiments, lunar fines were exposed to pure O2, pure water vapor, HCl, NH3, N2, HCOOH, and CH3NH2, in order to observe whether bonded particles would separate. In addition, repeated gas adsorption/desorption measurements were performed to determine the nature and reactive properties of the particle surfaces, and surface areas were measured for comparison with analogous terrestrial samples to determine whether the surface areas of highly radiation-damaged particles were larger or smaller. It is found that N2 is apparently ineffective in separating bonded particles and that the ratio of Apollo 11 to Apollo 12 bonded particles separated by a particular gas exposure ranges from 2.5 to 3.0. Possible reasons for differences in material surface properties at the two Apollo sites are considered, and it is concluded that material from a certain depth at some other site was transported to the Apollo 12 site and mixed with the original material in recent years (considerably less than 2000 years ago).

Mukherjee, N. R.↗
NASA NTRS1977

Conversion of laser energy to gas kinetic energy

Techniques for the gas-phase absorption of laser energy with ultimate conversion to heat or directed kinetic energy are reviewed. It is shown that the efficiency of resonance absorption by the vibration/rotation bands of the working gas can be enhanced by operating at sufficiently high pressures so that the linewidths of the absorbing transition exceed the line spacing. Within this limit, the gas can absorb continuously over the full spectral region of the band, and bleaching can be minimized since the manifold of molecular vibrational levels can simultaneously absorb the laser radiation.

Caledonia, G. E.↗
NASA NTRS1977

Development of an in situ calibration technique for combustible gas detectors

This paper describes the development of an in situ calibration procedure for combustible gas detectors (CGD). The CGD will be a necessary device for future space vehicles as many subsystems in the Environmental Control/Life Support System utilize or produce hydrogen (H2) gas. Existing calibration techniques are time-consuming and require support equipment such as an environmental chamber and calibration gas supply. The in situ calibration procedure involves utilization of a water vapor electrolysis cell for the automatic in situ generation of a H2/air calibration mixture within the flame arrestor of the CGD. The development effort concluded with the successful demonstration of in situ span calibrations of a CGD.

Shumar, J. W.↗
NASA NTRS1979

Improved gas thrust bearings

Two variations of gas-lubricated thrust bearings extend substantially load-carrying range over existing gas bearings. Dual-Action Gas Thrust Bearing's load-carrying capacity is more than ninety percent greater than that of single-action bearing over range of compressibility numbers. Advantages of Cantilever-mounted Thrust Bearing are greater tolerance to dirt ingestion, good initial lift-off characteristics, and operational capability over wide temperature range.

Anderson, W. J.↗