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At least 271 records · Page 15

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NASA NTRS1975

Survey of hydrogen production and utilization methods. Volume 1: Executive summary

The use of hydrogen as a synthetic fuel is considered. Processes for the production of hydrogen are described along with the present and future industrial uses of hydrogen as a fuel and as a chemical feedstock. Novel and unconventional hydrogen-production techniques are evaluated, with emphasis placed on thermochemical and electrolytic processes. Potential uses for hydrogen as a fuel in industrial and residential applications are identified and reviewed in the context of anticipated U.S. energy supplies and demands. A detailed plan for the period from 1975 to 1980 prepared for research on and development of hydrogen as an energy carrier is included.

Gregory, D. P.↗

NASA NTRS1975

Hydrogen production

The state of hydrogen production technology is evaluated. Specific areas discussed include: hydrogen production fossil fuels; coal gasification processes; electrolysis of water; thermochemical production of hydrogen; production of hydrogen by solar energy; and biological production of hydrogen. Supply options are considered along with costs of hydrogen production.

England, C.↗

NASA NTRS1974

The use of the ion probe mass spectrometer in the measurement of hydrogen concentration gradients in Monel K 500

The ion probe mass spectrometer was used to measure hydrogen concentration gradients in cathodically charged Monel K 500. Initial work with the ion probe involved the calibration of the instrument and the establishment of a suitable experimental procedure for this application. Samples of Monel K 500 were cathodically charged in a weak sulfuric acid solution. By varying the current density, different levels of hydrogen were introduced into the samples. Hydrogen concentration gradients were taken by ion sputtering on the surface of these samples and monitoring the behavior of the hydrogen mass peak as a function of time. An attempt was made to determine the relative amounts of hydrogen in the bulk and grain boundaries by analyzing a fresh fracture surface with a higher proportion of grain boundary area. It was found that substantially more hydrogen was detected in the grain boundaries than in the bulk, confirming the predictions of previous workers. A sputter rate determination was made in order to establish the rate of erosion.

Truhan, J. J., Jr.↗

NASA NTRS1976

Generation of atomic H in a hydrogen matrix by tritium decay

Webeler's (1976) experimental results for the generation of atomic hydrogen in a hydrogen matrix by tritium decay are reexamined with a variant of Rosen's (1976) mathematical treatment. The analysis retains Rosen's equations for the number densities of trapped and mobile hydrogen atoms, but replaces his enthalpy equation with an equation for the directly measured temperature. Theoretical expressions are derived for the dependence of storage time, recombination time, and maximum density of trapped hydrogen atoms as a function of temperature for a given tritium concentration. A comparison of predictions for the maximum trapped atomic hydrogen number density as a function of storage time reveals that Rosen's estimate for the maximum number density of hydrogen atoms for the zero magnetic field case is a little more optimistic than the estimate obtained in the paper.

Zeleznik, F. J.↗

NASA NTRS1976

Prospects for pipeline delivery of hydrogen as a fuel and as a chemical feedstock

The possibility of using hydrogen for storing and carrying energy obtained from nonfossil sources such as nuclear and solar energy is examined. According to the method proposed, these nonfossil raw energy sources will be used to obtain hydrogen from water by three basically distinct routes: (1) electrical generation followed by electrolysis; (2) thermochemical decomposition; and (3) direct neutron or ultraviolet irradiation of hydrogen bearing molecules. The hydrogen obtained will be transmitted in long-distance pipelines, and distributed to all energy-consuming sectors. As a fuel gas, hydrogen has many qualities similar to natural gas and with only minor modifications, it can be transmitted and distributed in the same equipment, and can be burned in the same appliances as natural gas. Hydrogen can also be used as a clean fuel (water is the only combustion product) for automobiles, fleet vehicles, and aircraft.

Gregory, D. P.↗

NASA NTRS1976

Potential structural material problems in a hydrogen energy system

Potential structural material problems that may be encountered in the three components of a hydrogen energy system - production, transmission/storage, and utilization - have been identified. Hydrogen embrittlement, corrosion, oxidation, and erosion may occur during the production of hydrogen. Hydrogen embrittlement is of major concern during both transmission and utilization of hydrogen. Specific materials research and development programs necessary to support a hydrogen energy system are described. An awareness of probable shortages of strategic materials has been maintained in these suggested programs.

Gray, H. R.↗

NASA NTRS1976

New potentials for conventional aircraft when powered by hydrogen-enriched gasoline

Hydrogen enrichment for aircraft piston engines is under study in a new NASA program. The objective of the program is to determine the feasibility of inflight injection of hydrogen in general aviation aircraft engines to reduce fuel consumption and to lower emission levels. A catalytic hydrogen generator will be incorporated as part of the air induction system of a Lycoming turbocharged engine and will generate hydrogen by breaking down small amounts of the aviation gasoline used in the normal propulsion system. This hydrogen will then be mixed with gasoline and compressed air from the turbocharger before entering the engine combustion chamber. The paper summarizes the results of a systems analysis study. Calculations assuming a Beech Duke aircraft indicate that fuel savings on the order of 20% are possible. An estimate of the potential for the utilization of hydrogen enrichment to control exhaust emissions indicates that it may be possible to meet the 1979 Federal emission standards.

Menard, W. A.↗

NASA NTRS1977

A survey of interstellar molecular hydrogen. I

Data from the Copernicus satellite's ultraviolet telescope were used to survey column densities of atomic and molecular hydrogen from a large sample of early-type stars; these data have bearing on an eventual understanding of diffuse and dense interstellar clouds. Column densities are derived by fitting damping profiles to the observed spectra, most of which exhibit strong damping lines in the lower rotational levels surveyed. Plots of dust column density, fractional abundance of molecular hydrogen, and the logarithm of fractional abundance versus total gas column density are given for many of the stars; stars with abnormally large or small hydrogen column densities, as well as some distant stars at high galactic latitudes, are considered. Equilibrium and nonequilibrium theories accounting for the abundance of interstellar hydrogen are compared, and support is found in the data for an account which balances hydrogen formation on interstellar grains with destruction through photodissociation. Overall averages for atomic and molecular hydrogen levels in the galactic plane are also calculated.

Savage, B. D.↗

NASA NTRS1977

The liquid hydrogen option for the subsonic transport - A status report

Studies dealing with the use of liquid hydrogen for fuel in subsonic air transport systems are reviewed. Topics of the studies include the possibility for economical production of hydrogen, the problems associated with the efficient liquefaction of the gas, the development of insulation materials and materials for long-lasting liquid hydrogen fuel tanks, the difficulties related to fueling processes and the installation of liquid hydrogen fuel stations at major air terminals, an assessment of the hazards connected with liquid hydrogen fuels, and the engineering and design problems involved in incorporating liquid hydrogen fuel systems into large subsonic passenger aircraft.

Korycinski, P. F.↗

NASA NTRS1978

Diffusion of hydrogen through platinum membranes at high pressures and temperatures

The diffusion of hydrogen through platinum membranes has been measured at 450, 500, 550 and 600 C at 2000 bar pressure, using the hydrogen sensor technique. Ag + AgCl + 3M HCl was the starting solution inside the platinum tube. Hydrogen diffuses out of the platinum tube into a system containing Fe2O3 + Fe3O4 + H2O; that is, a solution with a fixed hydrogen fugacity. After quench, the drop in hydrogen fugacity inside the platinum tube was calculated from measurements of pH and chloride molality. The hydrogen fugacity is initially roughly proportional to the square root of time. Diffusion constants were calculated from these data by numerical integration.

Chou, I.-M.↗

NASA NTRS1980

Ground cloud hydrogen chloride measurements from three Titan launches at the Kennedy Space Center during 1978 and 1979

Total hydrogen chloride and gaseous hydrogen chloride concentrations were measured in the exhaust cloud produced at three Titan 3 launches at the Kennedy Space Center in March 1978, December 1978, and November 1979 to determine the degree of hydrogen chloride partitioning in a solid rocket exhaust cloud between gaseous hydrogen chloride and hydrochloric acid aerosol as a function of ambient relative humidity. Moderately low relative humidity conditions were present during a daytime launch on Mar 25, 1978, and high relative humidity conditions were present during a nighttime launch on December 13, 1978. Gaseous hydrogen chloride concentrations and meteorological data, as a function of time after launch, are presented. Hydrogen chloride is present in both the gaseous and aerosol phase in the exhaust cloud. Total HCl concentrations ranged from 18 parts per million by volume (ppm) several minutes after launch down to 1 ppm after the cloud stabilization period, depending on the meteorological conditions. Gaseous HCl concentrations ranged from 2 to 3 ppm several minutes after launch to less than 1 ppm after cloud stabilization. These measured concentrations indicated significant HCl aerosol formation.

Seabacher, D. I.↗

NASA NTRS1980

Assessment of potential future hydrogen markets in the U.S.

Potential future hydrogen markets in the United States are assessed. Future hydrogen markets for various use sectors are projected, the probable range of hydrogen production costs from various alternatives is estimated, stimuli and barriers to the development of hydrogen markets are discussed, an overview of the status of technologies for the production and utilization of hydrogen is presented, and, finally, societal aspects of hydrogen production and utilization are discussed.

Kashani, A. K.↗

NASA NTRS1981

Hydrogen partitioning in pure cast aluminum as determined by dynamic evolution rate measurements

Hydrogen in pure aluminum can be found in two different states. One is related to a presence in gas-filled pores, while the other state involves the formation of a solid solution between hydrogen and aluminum. The considered investigation is concerned with the distribution of the hydrogen between various states. A dynamic technique is employed to measure the evolution of hydrogen from commercially available samples of polycrystalline pure aluminum under ultrahigh vacuum conditions. The obtained data are compared with the results of a statistical analysis concerning the porosity in the cast aluminum. It was found that more than 99 pct of the hydrogen in the aluminum is located in large pores. Less than 1 pct of the hydrogen is partitioned between the solid solution and the small pores.

Outlaw, R. A.↗

NASA NTRS1983

Investigation of a para-ortho hydrogen reactor for application to spacecraft sensor cooling

The utilization of solid hydrogen in space for sensor and instrument cooling is a very efficient technique for long term cooling or for cooling at high heat rates. The solid hydrogen can provide temperatures as low as 7 to 8 K to instruments. Vapor cooling is utilized to reduce parasitic heat inputs to the 7 to 8 K stage and is effective in providing intermediate cooling for instrument components operating at higher temperatures. The use of solid hydrogen in place of helium may lead to weight reductions as large as a factor of ten and an attendent reduction in system volume. The results of an investigation of a catalytic reactor for use with a solid hydrogen cooling system is presented. Trade studies were performed on several configurations of reactor to meet the requirements of high reactor efficiency with low pressure drop. Results for the selected reactor design are presented for both liquid hydrogen systems operating at near atmospheric pressure and the solid hydrogen cooler operating as low as 1 torr.

Nast, T. C.↗

NASA NTRS1986

Characterization of hydrogen embrittlement in nickel base superalloy single crystals

In order to study the role of CMSX2 single crystal microstructure on the combined stress-hydrogen environment effects, hydrogen was introduced by cathodic charging. Concentration measurements were carried out to investigate the dependence of hydrogen solubility and trapping on microstructure. Mechanical properties were measured at room temperature on smooth tensile specimens as a function of heat treatment, crystal orientation and H charging conditions. SEM and TEM allow to study H induced cracks initiation and propagation. A large amount of hydrogen can be dissolved and trapped in CMSX2 single crystals when exposed to a high hydrogen fugacity environment. The strong H trapping evidenced in voids explains the predominant role of these defects as crack initiation sites. The strong detrimental effect of hydrogen on the material tenacity is discussed.

Chene, J.↗

NASA NTRS1988

Diffusion Analysis Of Hydrogen-Desorption Measurements

Distribution of hydrogen in metal explains observed desorption rate. Report describes application of diffusion theory to anaylsis of experimental data on uptake and elimination of hydrogen in high-strength alloys of 25 degree C. Study part of program aimed at understanding embrittlement of metals by hydrogen. Two nickel-base alloys, Rene 41 and Waspaloy, and one ferrous alloy, 4340 steel, studied. Desorption of hydrogen explained by distribution of hydrogen in metal. "Fast" hydrogen apparently not due to formation of hydrides on and below surface as proposed.

Danford, Merlin D.↗

NASA NTRS1988

Hydrogen effects in 001-line oriented nickel-base superalloy single crystals

The entry and subsequent interaction of hydrogen on the mechanical properties of the single crystal nickel-base superalloy CMSX-2 has been studied. Significant amounts of hydrogen were introduced by high temperature hydrogen charging in molten salts which led to an increased lattice parameter and microhardness and to a degradation in tensile elongation to failure whose extent scales with the depth of the hydrogenated zone. In this region a fracture mode change from a 111 to a 100 plane type also occurred. The values of the binding energy of hydrogen to solidification voids and the effective hydrogen pressure in the voids were estimated.

Baker, C. L.↗

NASA NTRS1989

Photovoltaic Hydrogen Sensor

Photovoltaic device senses hydrogen developed to test degradation of diodes with platinum flash gates on backs. Sensing element is p/n junction rather than conventional Schottky barrier or metal oxide/silicon field-effect transistor. Hydrogen-indicating electrical signal modulated optically rather than electrically. Layered structure of hydrogen detector and principle of operation resemble silicon solar photovoltaic cell. Hydrogen detector responds to hydrogen in atmosphere within minutes and recovers quickly when hydrogen removed.

Daud, Taher↗