WorldWideScience

Sample records for psia hydrogen pressure

  1. Metal vapor condensation under high pressure (mercury vapor to 500 psia). [Heat transfer coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, S.; Bonilla, C.F.

    1975-01-01

    Mercury vapor up to 500 psia was condensed outside a cylindrical tube in both horizontal and vertical positions. Results show consistently low heat transfer coefficients compared to Nusselt's theory. Two auxiliary mercury vapor condensers downstream of the boiler vent were used to control and safeguard the system. Constantan wires were spot welded on the surface inside the test condenser tube. The heat flux ranged from 20,000 to 45,000 Btu/h-ft/sup 2/ and the temperature differences between vapor and condensing wall from 6 to 50/sup 0/F. The condensation heat transfer coefficients, ranging from 850 to 3,500 Btu/h-/sup 0/F-ft/sup 2/, are only about 3 to 9 percent of those predicted by Nusselt's theory. Due to the positive pressure in the system for most test runs, the chance of any in-leakage of noncondensable gases into the boiler is extremely small. Since no substantial change of heat transfer rate resulted from wide variations in the heat load on the reflux condenser at some specific heat flux on the test condenser tube, the low heat transfer rate of mercury vapor condensation was not due to the presence of any non-condensable gas. The test data for high vapor pressure up to 500 psia reveal that the heat transfer coefficient is independent of the vapor pressure level. The condensation coefficients calculated based on kinetic theory are much smaller than unity and decreasewith vapor pressure. It is hypothesized that dimer content in the metal vapor phase might behave as non-condensable or semi-condensable gas and create a diffusional barrier at the vapor-liquid interface near the condensate film. This dimer vapor could be the main cause of interfacial resistance during metal vapor condensation process. 41 figures, 7 tables, 58 references. (DLC)

  2. Safety of hydrogen pressure gauges.

    Science.gov (United States)

    Voth, R. O.

    1972-01-01

    Study of the relative safety afforded an operator by various hydrogen-pressure gauge case designs. It is shown that assurance of personnel safety, should a failure occur, requires careful selection of available gauge designs, together with proper mounting. Specific gauge case features and mounting requirements are recommended.

  3. Pressurized hydrogen and methane releases

    Energy Technology Data Exchange (ETDEWEB)

    Ruffin, E.; Mouilleau, Y.; Chaineaux, J.

    1996-07-01

    This paper reports on an experimental investigation of the concentration field of supercritical jets of methane and hydrogen. The jets were produced by venting a tank containing gas at a pressure of 40 bars (568 psi) to atmosphere through orifices whose diameters ranged from 25 to 150 mm. The investigation was designed with experiments on a scale typical of that encountered in industry during accidental discharges of pressurised gas, a scale much larger that that normally used in a laboratory. The concentration measurements were made in the subsonic zone of the jets using an original technique. This technique employs a sensor using the catalytic oxidation effects and can measure the concentration of combustible gas in highly reactive environments with no risk of ignition. Ignition tests of the flammable atmospheres and measurements of the aerial pressures had also been performed. The results show that concentration fields of supercritical and subsonic jets are equal if they are weighted by a properly chosen equivalent diameter. Explosion tests show that the over pressures produced by the deflagrations are highly dependent of the ignition point. (author). 6 figs.

  4. Hydrogen storage in insulated pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S.M.; Garcia-Villazana, O. [Lawrence Livermore National Lab., CA (United States)

    1998-08-01

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). This paper shows an evaluation of the applicability of the insulated pressure vessels for light-duty vehicles. The paper shows an evaluation of evaporative losses and insulation requirements and a description of the current analysis and experimental plans for testing insulated pressure vessels. The results show significant advantages to the use of insulated pressure vessels for light-duty vehicles.

  5. Modeling the effects of dissolved helium pressurant on a liquid hydrogen rocket propellant tank

    Science.gov (United States)

    Richardson, I. A.; Leachman, J. W.

    2017-12-01

    A model was developed using NASA’s Generalized Fluid System Simulation Program (GFSSP) for the self-pressurization of a liquid hydrogen propellant tank due to boil-off to determine the significance of mixture non-idealities. The GFSSP model compared the tank performance for the traditional model that assumes no helium pressurant dissolves into the liquid hydrogen propellant to an updated model that accounts for dissolved helium pressurant. Traditional NASA models have been unable to account for this dissolved helium due to a lack of fundamental property information. Recent measurements of parahydrogen-helium mixtures enabled the development of the first multi-phase Equation Of State (EOS) for parahydrogen-helium mixtures. The self-pressurization GFSSP model was run assuming that the liquid propellant was pure liquid hydrogen and assuming helium dissolved into the liquid utilizing the new helium-hydrogen EOS. The analysis shows that having dissolved helium in the propellant does not have a significant effect on the tank pressurization rate for typical tank conditions (-423 °F and 30 psia).

  6. Hydrogen and its compounds under extreme pressure

    Science.gov (United States)

    Utyuzh, A. N.; Mikheyenkov, A. V.

    2017-12-01

    In the last two or three years, significant advances in the study of hydrogen and its compounds under extreme conditions (ultrahigh pressures over a wide temperature range) have notably changed the hydrogen phase diagram, provided a break-through in understanding hydrides’ behavior under pressure (as exemplified by the discovery of high-temperature superconductivity in hydrogen sulfide), and, finally, enabled achieving cold metallization of hydrogen. The situation prior to the 2010s is reviewed in brief and more recent work is examined in detail. While the primary focus is on experimental research, mention is also made of the theoretical and numerical work it stimulates. This review presents an extension of the talk by the authors for the scientific session of the Physical Sciences Division of the Russian Academy of Sciences, “Old and new ideas in phase transition physics,” which was held on December 21, 2016 (see Phys. Usp. 60 948–957 (2017); Usp. Fiz. Nauk 187 1021 (2017)). (Editor’s note.)

  7. High Pressure Hydrogen from First Principles

    Science.gov (United States)

    Morales, M. A.

    2014-12-01

    Typical approximations employed in first-principles simulations of high-pressure hydrogen involve the neglect of nuclear quantum effects (NQE) and the approximate treatment of electronic exchange and correlation, typically through a density functional theory (DFT) formulation. In this talk I'll present a detailed analysis of the influence of these approximations on the phase diagram of high-pressure hydrogen, with the goal of identifying the predictive capabilities of current methods and, at the same time, making accurate predictions in this important regime. We use a path integral formulation combined with density functional theory, which allows us to incorporate NQEs in a direct and controllable way. In addition, we use state-of-the-art quantum Monte Carlo calculations to benchmark the accuracy of more approximate mean-field electronic structure calculations based on DFT, and we use GW and hybrid DFT to calculate the optical properties of the solid and liquid phases near metallization. We present accurate predictions of the metal-insulator transition on the solid, including structural and optical properties of the molecular phase. This work was supported by the U.S. Department of Energy at the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and by LDRD Grant No. 13-LW-004.

  8. Confinement of hydrogen at high pressure in carbon nanotubes

    Science.gov (United States)

    Lassila, David H [Aptos, CA; Bonner, Brian P [Livermore, CA

    2011-12-13

    A high pressure hydrogen confinement apparatus according to one embodiment includes carbon nanotubes capped at one or both ends thereof with a hydrogen-permeable membrane to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough. A hydrogen confinement apparatus according to another embodiment includes an array of multi-walled carbon nanotubes each having first and second ends, the second ends being capped with palladium (Pd) to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough as a function of palladium temperature, wherein the array of carbon nanotubes is capable of storing hydrogen gas at a pressure of at least 1 GPa for greater than 24 hours. Additional apparatuses and methods are also presented.

  9. Mixture including hydrogen and hydrocarbon having pressure-temperature stability

    Science.gov (United States)

    Mao, Wendy L. (Inventor); Mao, Ho-Kwang (Inventor)

    2009-01-01

    The invention relates to a method of storing hydrogen that employs a mixture of hydrogen and a hydrocarbon that can both be used as fuel. In one embodiment, the method involves maintaining a mixture including hydrogen and a hydrocarbon in the solid state at ambient pressure and a temperature in excess of about 10 K.

  10. NASA Lewis advanced individual pressure vessel (IPV) nickel/hydrogen technology

    Science.gov (United States)

    Smithrick, John J.; Britton, Doris L.

    Individual pressure vessel (IPV) nickel/hydrogen technology was advanced at NASA Lewis and under Lewis contracts. Some of the advancements are as follows: (1) to use 26% KOH electrolyte to improve cycle life and performance; (ii) to modify the state-of-the-art cell design to eliminate identified failure modes and further improve cycle life, and (iii) to develop a lightweight nickel electrode to reduce battery mass, hence reduce launch and/ or increase satellite payload. A breakthrough in the Low-Earth-Orbit (LEO) cycle life of individual pressure vessel nickel/hydrogen battery cells was reported. The cycle life of boiler plate cells containing 26% KOH electrolyte was about 40 000 accelerated LEO cycles at 80% depth-of-discharge (DOD) compared with 3500 cycles for cells containing 31% KOH. Results of the boiler plate cells tests have been validated at Naval Weapons Support Center, Crane, IN. Forty-eight Ah flight cells containing 26 and 31% KOH have undergone real time LEO cycle life testing at an 80% DOD, in 10 °C. The three cells containing 26% KOH failed on the average at cycle 19 500. The three cells containing 31% KOH failed on the average at cycle 6400. Validation testing of NASA Lewis 125 Ah advanced design IPV nickel/hydrogen flight cells is also being conducted at Naval Weapons Support Center, Crane, IN under a NASA Lewis contract. This consists of characterization, storage, and cycle-life testing. There was no capacity degradation after 52 days of storage with the cells in the discharged state, on open circuit, 0 °C, and a hydrogen pressure of 14.5 psia (1 atm). The catalyzed wall wick cells have been cycled for over 22 694 cycles with no cell failures in the continuing test. All three of the noncatalyzed wall wick cells failed (cycles 9588, 13 900 and 20 575). Cycle-life test results of the Fibrex nickel electrode has demonstrated the feasibility of an improved nickel electrode giving a higher specific energy nickel/hydrogen cell. A nickel/hydrogen

  11. Test results from a simple, low-cost, pressure-fed liquid hydrogen/liquid oxygen rocket combustor

    Science.gov (United States)

    Dressler, G. A.; Stoddard, F. J.; Gavitt, K. R.; Klem, M. D.

    1993-01-01

    A simple, low-cost rocket engine was designed, fabricated, and successfully hot fire tested over a wide range of interface conditions and operating parameters. The engine used low enthalpy hydrogen (45 to 70 R, 200 to 390 psia) and oxygen (139 to 163 R, 210 to 480 psia) propellants pressure-fed directly from facility cryogenic tanks. The engine demonstrated excellent performance, with 97% average combustion efficiency, and absence of combustion instabilities. Engine design chamber pressure was 300 psia, yielding about 16,500 pounds thrust at sea level with a 3:1 expansion ration test nozzle. The engine used a fixed-element injector based on TRW's unique coaxial pintle design, but was operated at 60%, 80%, and 100% thrust levels by throttling facility propellant valves. The engine was tested at propellant mixture ratios (O/F) from 5.8 to 8.4; design O/F was 6.6. To document combustion stability, in five tests RDX explosive pulse guns were detonated in radial and tangential directions across the combustion chamber during steady-state operation. The largest disturbance consisted of simultaneous detonation of a 20-grain radial gun and a 40-grain tangential gun. In no case was an instability, either feed system mode or chamber acoustic mode, excited. High-frequency piezoelectric pressure transducers documented stable recovery from disturbance overpressures within 40 milliseconds of peak pressure. A total of 67 firing tests, accumulating 149 seconds of firing time above 10% P(sub c), were performed. Since parametric testing required run durations of only 2 to 3 seconds, a heat sink combustion chamber was employed for most runs. To evaluate the feasibility of a low-cost ablative system for a flight engine design, one 20-second continuous firing was conducted with a silicone rubber chamber/throat/nozzle liner cast in one piece directly into the engine. The ablative engine operated at the equivalent of 309 seconds sea level specific impulse, when adjusted to a 98% efficient

  12. Test results from a simple, low-cost, pressure-fed liquid hydrogen/liquid oxygen rocket combustor

    Science.gov (United States)

    Dressler, G. A.; Stoddard, F. J.; Gavitt, K. R.; Klem, M. D.

    1993-11-01

    A simple, low-cost rocket engine was designed, fabricated, and successfully hot fire tested over a wide range of interface conditions and operating parameters. The engine used low enthalpy hydrogen (45 to 70 R, 200 to 390 psia) and oxygen (139 to 163 R, 210 to 480 psia) propellants pressure-fed directly from facility cryogenic tanks. The engine demonstrated excellent performance, with 97% average combustion efficiency, and absence of combustion instabilities. Engine design chamber pressure was 300 psia, yielding about 16,500 pounds thrust at sea level with a 3:1 expansion ration test nozzle. The engine used a fixed-element injector based on TRW's unique coaxial pintle design, but was operated at 60%, 80%, and 100% thrust levels by throttling facility propellant valves. The engine was tested at propellant mixture ratios (O/F) from 5.8 to 8.4; design O/F was 6.6. To document combustion stability, in five tests RDX explosive pulse guns were detonated in radial and tangential directions across the combustion chamber during steady-state operation. The largest disturbance consisted of simultaneous detonation of a 20-grain radial gun and a 40-grain tangential gun. In no case was an instability, either feed system mode or chamber acoustic mode, excited. High-frequency piezoelectric pressure transducers documented stable recovery from disturbance overpressures within 40 milliseconds of peak pressure. A total of 67 firing tests, accumulating 149 seconds of firing time above 10% P(sub c), were performed. Since parametric testing required run durations of only 2 to 3 seconds, a heat sink combustion chamber was employed for most runs. To evaluate the feasibility of a low-cost ablative system for a flight engine design, one 20-second continuous firing was conducted with a silicone rubber chamber/throat/nozzle liner cast in one piece directly into the engine. The ablative engine operated at the equivalent of 309 seconds sea level specific impulse, when adjusted to a 98% efficient

  13. Synthesis of hydrogen-carbon clathrate material and hydrogen evolution therefrom at moderate temperatures and pressures

    Science.gov (United States)

    Lueking, Angela [State College, PA; Narayanan, Deepa [Redmond, WA

    2011-03-08

    A process for making a hydrogenated carbon material is provided which includes forming a mixture of a carbon source, particularly a carbonaceous material, and a hydrogen source. The mixture is reacted under reaction conditions such that hydrogen is generated and/or released from the hydrogen source, an amorphous diamond-like carbon is formed, and at least a portion of the generated and/or released hydrogen associates with the amorphous diamond-like carbon, thereby forming a hydrogenated carbon material. A hydrogenated carbon material including a hydrogen carbon clathrate is characterized by evolution of molecular hydrogen at room temperature at atmospheric pressure in particular embodiments of methods and compositions according to the present invention.

  14. Low Pressure Adsorbent for Recovery & Storage Vented Hydrogen Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high performance fullerene-based adsorbent is proposed for recovery and storage hydrogen and separating helium via pressure-swing-adsorption (PSA) process....

  15. New perspectives on potential hydrogen storage materials using high pressure.

    Science.gov (United States)

    Song, Yang

    2013-09-21

    In addressing the global demand for clean and renewable energy, hydrogen stands out as the most suitable candidate for many fuel applications that require practical and efficient storage of hydrogen. Supplementary to the traditional hydrogen storage methods and materials, the high-pressure technique has emerged as a novel and unique approach to developing new potential hydrogen storage materials. Static compression of materials may result in significant changes in the structures, properties and performance that are important for hydrogen storage applications, and often lead to the formation of unprecedented phases or complexes that have profound implications for hydrogen storage. In this perspective article, 22 types of representative potential hydrogen storage materials that belong to four major classes--simple hydride, complex hydride, chemical hydride and hydrogen containing materials--were reviewed. In particular, their structures, stabilities, and pressure-induced transformations, which were reported in recent experimental works together with supporting theoretical studies, were provided. The important contextual aspects pertinent to hydrogen storage associated with novel structures and transitions were discussed. Finally, the summary of the recent advances reviewed and the insight into the future research in this direction were given.

  16. Fabrication of Bulk Glassy Alloy Foams by High Pressure Hydrogen

    Science.gov (United States)

    Wada, Takeshi; Inoue, Akihisa

    Porous Pd42.5Cu30Ni7.5P20 bulk glassy alloy rods with porosities of up to 70% were successfully prepared by high pressure hydrogen of 15 MPa. The melt of Pd42.5Cu30Ni7.5P20 alloy kept under high pressure hydrogen absorbs hydrogen and subsequent water quenching of the melt causes the homogeneous dispersion of hydrogen bubbles, which was resulted from the decrease of hydrogen solubility with decrease of pressure. Annealing the hydrogen bubble containing sample at a supercooled liquid state under vacuum, the bubbles are allowed to expand due to the decrease of viscosity of metallic glass matrix. Pores expansion continues until glassy matrix crystallizes or the equilibration among pressure of the pores, pressure of the atmosphere and surface tension is achieved. By utilizing these phenomena, pores up to 80 m in diameters are homogeneously distributed over the whole cross-sectional area of a fully glassy matrix. Under compressive deformation, the porous alloys with porosities exceeding 40% did not show macroscopic fracture in a wide compressive strain range up to 0.6 whereas the non-porous alloy fractures instantly after elastic limit of about 0.02. Porous bulk glassy alloys exhibit higher plateau stress, lower Young‧s modulus and higher energy absorption capacity compared with the conventional crystalline metal foams.

  17. ASU nitrogen sweep gas in hydrogen separation membrane for production of HRSG duct burner fuel

    Science.gov (United States)

    Panuccio, Gregory J.; Raybold, Troy M.; Jamal, Agil; Drnevich, Raymond Francis

    2013-04-02

    The present invention relates to the use of low pressure N2 from an air separation unit (ASU) for use as a sweep gas in a hydrogen transport membrane (HTM) to increase syngas H2 recovery and make a near-atmospheric pressure (less than or equal to about 25 psia) fuel for supplemental firing in the heat recovery steam generator (HRSG) duct burner.

  18. Public debate on metallic hydrogen to boost high pressure research

    Directory of Open Access Journals (Sweden)

    Hua Y. Geng

    2017-11-01

    Full Text Available Instead of praises from colleagues, the claim of observation of metallic hydrogen at 495 GPa by Dias and Silvera met much skepticism, and grew into a public debate at the International Conference on High-Pressure Science and Technology, AIRAPT26. We briefly review this debate, and extend the topic to show that this disputation could be an opportunity to benefit the whole high pressure community. Keywords: High pressure, Metallic hydrogen, Quantum solid and liquid, Phase stability, Superconductivity, PACS codes: 61.50.Ks, 67.63.-r, 67.80.-s, 71.30.+h, 74.62.Fj

  19. Pressure loss reduction in hydrogen pipelines by surface restructuring

    Energy Technology Data Exchange (ETDEWEB)

    Peet, Y.; Sagaut, P. [Insitut Jean Le Rond d' Alembert, UMR CNRS 7190, Universite Pierre et Marie Curie - Paris 6, 4 place Jussieu - case 162, F-75252 Paris Cedex 5 (France); Charron, Y. [IFP- Institut Francais du Petrole, Rueil Malmaison Cedex, 92852 (France)

    2009-11-15

    This paper concerns the reduction of pressure losses during pipeline hydrogen transportation, as the cost of hydrogen compression is a significant obstacle for efficient hydrogen pumping on a large-scale basis. The use of organized micro-structures on pipeline walls is proposed to obtain lower values of pressure losses with respect to smooth walls. Three-dimensional micro-structures of a sinusoidal shape are investigated as potentially more efficient counterparts to conventional two-dimensional structures (riblets) developed in aerospace industry. Aerodynamic performance of three-dimensional structures is investigated computationally in terms of both skin friction and pressure drag, two constituents of the total drag. Three-dimensional structures are shown to provide larger total drag reduction than two-dimensional structures for some range of geometrical parameters (14.5% versus 11%). Parametric dependence of both pressure and skin friction drag on structure geometry is analyzed, and an optimum configuration maximizing the total drag reduction is proposed. (author)

  20. Warm Pressurant Gas Effects on the Liquid Hydrogen Bubble Point

    Science.gov (United States)

    Hartwig, Jason W.; McQuillen, John B.; Chato, David J.

    2013-01-01

    This paper presents experimental results for the liquid hydrogen bubble point tests using warm pressurant gases conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine mesh screen samples (325 x 2300, 450 x 2750, 510 x 3600) were tested in liquid hydrogen using cold and warm noncondensible (gaseous helium) and condensable (gaseous hydrogen) pressurization schemes. Gases were conditioned from 0 to 90 K above the liquid temperature. Results clearly indicate a degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensible pressurization. Degradation in the bubble point pressure is inversely proportional to screen porosity, as the coarsest mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.

  1. The Effect of Hydrogen Partial Pressure on Methylcyclopentane Ring Opening.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Vaarkamp, M.; Dijkstra, P.; Grondelle, J. van; Miller, J.T.; Modica, F.S.; Sante, R.A. van

    1995-01-01

    The ring opening of methylcyclopentane (MCP) over well-characterized Pt/SiO{2}(EUROPT-1), Pt/@c-Al{2}O{3}, and Pt/K-LTL catalysts was studied as a function of hydrogen partial pressure and reduction temperature. The MCP ring opening selectivity did not change in the range of H{2}:MCP ratios studied

  2. LOX vaporization in high-pressure, hydrogen-rich gas

    Science.gov (United States)

    Litchford, Ron J.; Jeng, San-Mou

    1990-01-01

    LOX droplet vaporization in high-pressure hydrogen-rich gas is analyzed, with special attention to thermodynamic effects which compel the surface to heat to the critical state and to supercritical vaporization processes on heating to criticality. Subcritical vaporization is modeled using a quasi-steady diffusion-controlled gas-phase transport formulation coupled to an effective-conductivity internal-energy-transport model accounting for circulation effects. It is demonstrated how the droplet surface might heat to the critical state, for ambient pressures slightly greater than the critical pressure of oxygen, such that the bulk of propellant within the droplet remains substantially below the critical mixing temperature.

  3. Synthesis and stability of hydrogen selenide compounds at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Pace, Edward J.; Binns, Jack; Alvarez, Miriam Pena; Dalladay-Simpson, Philip; Gregoryanz, Eugene; Howie, Ross T. (Edinburgh); (CHPSTAR- China)

    2017-11-14

    The observation of high-temperature superconductivity in hydride sulfide (H2S) at high pressures has generated considerable interest in compressed hydrogen-rich compounds. High-pressure hydrogen selenide (H2Se) has also been predicted to be superconducting at high temperatures; however, its behaviour and stability upon compression remains unknown. In this study, we synthesize H2Se in situ from elemental Se and molecular H2 at pressures of 0.4 GPa and temperatures of 473 K. On compression at 300 K, we observe the high-pressure solid phase sequence (I-I'-IV) of H2Se through Raman spectroscopy and x-ray diffraction measurements, before dissociation into its constituent elements. Through the compression of H2Se in H2 media, we also observe the formation of a host-guest structure, (H2Se)2H2, which is stable at the same conditions as H2Se, with respect to decomposition. These measurements show that the behaviour of H2Se is remarkably similar to that of H2S and provides further understanding of the hydrogen chalcogenides under pressure.

  4. Pressure Relief Devices for High-Pressure Gaseous Storage Systems: Applicability to Hydrogen Technology

    Energy Technology Data Exchange (ETDEWEB)

    Kostival, A.; Rivkin, C.; Buttner, W.; Burgess, R.

    2013-11-01

    Pressure relief devices (PRDs) are viewed as essential safety measures for high-pressure gas storage and distribution systems. These devices are used to prevent the over-pressurization of gas storage vessels and distribution equipment, except in the application of certain toxic gases. PRDs play a critical role in the implementation of most high-pressure gas storage systems and anyone working with these devices should understand their function so they can be designed, installed, and maintained properly to prevent any potentially dangerous or fatal incidents. As such, the intention of this report is to introduce the reader to the function of the common types of PRDs currently used in industry. Since high-pressure hydrogen gas storage systems are being developed to support the growing hydrogen energy infrastructure, several recent failure incidents, specifically involving hydrogen, will be examined to demonstrate the results and possible mechanisms of a device failure. The applicable codes and standards, developed to minimize the risk of failure for PRDs, will also be reviewed. Finally, because PRDs are a critical component for the development of a successful hydrogen energy infrastructure, important considerations for pressure relief devices applied in a hydrogen gas environment will be explored.

  5. Low Temperature and High Pressure Evaluation of Insulated Pressure Vessels for Cryogenic Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S.; Martinez-Frias, J.; Garcia-Villazana, O.

    2000-06-25

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (fuel flexibility, lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The work described here is directed at verifying that commercially available pressure vessels can be safely used to store liquid hydrogen. The use of commercially available pressure vessels significantly reduces the cost and complexity of the insulated pressure vessel development effort. This paper describes a series of tests that have been done with aluminum-lined, fiber-wrapped vessels to evaluate the damage caused by low temperature operation. All analysis and experiments to date indicate that no significant damage has resulted. Required future tests are described that will prove that no technical barriers exist to the safe use of aluminum-fiber vessels at cryogenic temperatures.

  6. Vapor pressure and intramolecular hydrogen bonding in fluorotelomer alcohols.

    Science.gov (United States)

    Krusic, Paul J; Marchione, Alexander A; Davidson, Fredric; Kaiser, Mary A; Kao, Chien-Ping C; Richardson, Raymond E; Botelho, Miguel; Waterland, Robert L; Buck, Robert C

    2005-07-21

    Vapor pressure and aqueous solubility are important parameters used to estimate the potential for transport of chemical substances in the atmosphere. For fluorotelomer alcohols (FTOHs), currently under scrutiny by environmental scientists as potential precursors of persistent perfluorocarboxylates (PFCAs), vapor pressure is the more significant property since these compounds are only very sparingly soluble in water. We have measured the vapor pressures of a homologous series of fluorotelomer alcohols, F(CF2CF2)nCH2CH2OH (n = 2-5), in the temperature range 21-250 degrees C by three independent methods: (a) a method suitable for very low vapor pressures at ambient temperatures (gas-saturation method), (b) an improved boiling point method at controlled pressures (Scott method), and (c) a novel method, requiring milligram quantities of substance, based on gas-phase NMR, a technique largely unfamiliar to chemists and holding promise for studies of relevance to environmental chemistry. The concordant values obtained indicate that recently published vapor pressure data overestimate the vapor pressure at ambient temperature, and therefore the volatility, of this series of fluorinated compounds. It was suggested that substantial intramolecular -O-H...F- hydrogen bonding between the hydroxylic proton and the two fluorines next to the ethanol moiety was responsible for their putative high volatility. Therefore, we have used gas-phase NMR, gas-phase FTIR, 2D NMR heteronuclear Overhauser effect measurements, and high-level ab initio computations to investigate the intramolecular hydrogen bonding in fluorotelomer alcohols. Our studies unequivocally show that hydrogen bonding of this type is not significant and cannot contribute to and cause unusual volatility. The substantially lower vapor pressure at ambient temperatures than previously reported resulting from our work is important in developing a valid understanding of the environmental transport behavior of this class of

  7. High pressure CO hydrogenation over bimetallic Pt-Co catalysts

    DEFF Research Database (Denmark)

    Christensen, Jakob Munkholt; Medford, Andrew James; Studt, Felix

    2014-01-01

    The potential of bimetallic Pt-Co catalysts for production of higher alcohols in high pressure CO hydrogenation has been assessed. Two catalysts (Pt3Co/SiO2 and PtCo/SiO2) were tested, and the existing literature on CO hydrogenation over Pt-Co catalysts was reviewed. It is found that the catalysts...... produce mainly methanol in the Pt-rich composition range andmainly hydrocarbons (and to a modest extent higher alcohols) in the Co-rich composition range. The transition between the two types of behavior occurs in a narrow composition range around a molar Pt:Co ratio of 1:1....

  8. Fracture Analysis of Rubber Sealing Material for High Pressure Hydrogen Vessel

    National Research Council Canada - National Science Library

    YAMABE, Junichiro; FUJIWARA, Hirotada; NISHIMURA, Shin

    2011-01-01

    In order to clarify the influence of high pressure hydrogen gas on mechanical damage in a rubber O-ring, the fracture analysis of the O-ring used for a sealing material of a pressure hydrogen vessel was conducted...

  9. Low-Cost High-Pressure Hydrogen Generator

    Energy Technology Data Exchange (ETDEWEB)

    Cropley, Cecelia C.; Norman, Timothy J.

    2008-04-02

    Electrolysis of water, particularly in conjunction with renewable energy sources, is potentially a cost-effective and environmentally friendly method of producing hydrogen at dispersed forecourt sites, such as automotive fueling stations. The primary feedstock for an electrolyzer is electricity, which could be produced by renewable sources such as wind or solar that do not produce carbon dioxide or other greenhouse gas emissions. However, state-of-the-art electrolyzer systems are not economically competitive for forecourt hydrogen production due to their high capital and operating costs, particularly the cost of the electricity used by the electrolyzer stack. In this project, Giner Electrochemical Systems, LLC (GES) developed a low cost, high efficiency proton-exchange membrane (PEM) electrolysis system for hydrogen production at moderate pressure (300 to 400 psig). The electrolyzer stack operates at differential pressure, with hydrogen produced at moderate pressure while oxygen is evolved at near-atmospheric pressure, reducing the cost of the water feed and oxygen handling subsystems. The project included basic research on catalysts and membranes to improve the efficiency of the electrolysis reaction as well as development of advanced materials and component fabrication methods to reduce the capital cost of the electrolyzer stack and system. The project culminated in delivery of a prototype electrolyzer module to the National Renewable Energy Laboratory for testing at the National Wind Technology Center. Electrolysis cell efficiency of 72% (based on the lower heating value of hydrogen) was demonstrated using an advanced high-strength membrane developed in this project. This membrane would enable the electrolyzer system to exceed the DOE 2012 efficiency target of 69%. GES significantly reduced the capital cost of a PEM electrolyzer stack through development of low cost components and fabrication methods, including a 60% reduction in stack parts count. Economic

  10. Low Cost, High Efficiency, High Pressure Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Mark Leavitt

    2010-03-31

    A technical and design evaluation was carried out to meet DOE hydrogen fuel targets for 2010. These targets consisted of a system gravimetric capacity of 2.0 kWh/kg, a system volumetric capacity of 1.5 kWh/L and a system cost of $4/kWh. In compressed hydrogen storage systems, the vast majority of the weight and volume is associated with the hydrogen storage tank. In order to meet gravimetric targets for compressed hydrogen tanks, 10,000 psi carbon resin composites were used to provide the high strength required as well as low weight. For the 10,000 psi tanks, carbon fiber is the largest portion of their cost. Quantum Technologies is a tier one hydrogen system supplier for automotive companies around the world. Over the course of the program Quantum focused on development of technology to allow the compressed hydrogen storage tank to meet DOE goals. At the start of the program in 2004 Quantum was supplying systems with a specific energy of 1.1-1.6 kWh/kg, a volumetric capacity of 1.3 kWh/L and a cost of $73/kWh. Based on the inequities between DOE targets and Quantum’s then current capabilities, focus was placed first on cost reduction and second on weight reduction. Both of these were to be accomplished without reduction of the fuel system’s performance or reliability. Three distinct areas were investigated; optimization of composite structures, development of “smart tanks” that could monitor health of tank thus allowing for lower design safety factor, and the development of “Cool Fuel” technology to allow higher density gas to be stored, thus allowing smaller/lower pressure tanks that would hold the required fuel supply. The second phase of the project deals with three additional distinct tasks focusing on composite structure optimization, liner optimization, and metal.

  11. Hydrogen-Bonding Modification in Biuret Under Pressure.

    Science.gov (United States)

    Borstad, Gustav M; Ciezak-Jenkins, Jennifer A

    2017-02-02

    Biuret (C2H5N3O2) has been studied to 30 GPa by Raman spectroscopy and 50 GPa by X-ray diffraction. Raman peaks exhibit shoulders and splitting that suggests that the molecules undergo reorientation in response to compression. These are observed in three pressure ranges: the first from 3-5 GPa, the second from 8-12 GPa, and finally from 16-20 GPa. The particular modes in the sample that are observed to change in the Raman are strongly linked to the molecular vibrations involving the N-H and the C═O bond, which are most strongly coupled to the hydrogen-bonded lattice structure. The X-ray diffraction suggests that the crystal maintains a monoclinic structure to the highest pressures studied. Although there was a considerable degree of hysteresis observed in some X-ray runs, all the changes observed under pressure are reversible.

  12. High Pressure Hydrogen Pressure Relief Devices: Accelerated Life Testing and Application Best Practices

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, Robert M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Post, Matthew B. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Buttner, William J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rivkin, Carl H. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-06

    Pressure relief devices (PRDs ) are used to protect high pressure systems from burst failure caused by overpressurization. Codes and standards require the use of PRDs for the safe design of many pressurized systems. These systems require high reliability due to the risks associated with a burst failure. Hydrogen service can increase the risk of PRD failure due to material property degradation caused by hydrogen attack. The National Renewable Energy Laboratory (NREL) has conducted an accelerated life test on a conventional spring loaded PRD. Based on previous failures in the field, the nozzles specific to these PRDs are of particular interest. A nozzle in a PRD is a small part that directs the flow of fluid toward the sealing surface to maintain the open state of the valve once the spring force is overcome. The nozzle in this specific PRD is subjected to the full tensile force of the fluid pressure. These nozzles are made from 440C material, which is a type of hardened steel that is commonly chosen for high pressure applications because of its high strength properties. In a hydrogen environment, however, 440C is considered a worst case material since hydrogen attack results in a loss of almost all ductility and thus 440C is prone to fatigue and material failure. Accordingly, 440C is not recommended for hydrogen service. Conducting an accelerated life test on a PRD with 440C material provides information on necessary and sufficient conditions required to produce crack initiation and failure. The accelerated life test also provides information on other PRD failure modes that are somewhat statistically random in nature.

  13. Superconductivity in hydrogen-rich materials at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Drozdov, Alexander

    2016-07-01

    A room temperature superconductor is probably one of the most desired systems in solid state physics. The highest critical temperature (T{sub c}) that has been achieved so far is in the copper oxide system: 133 kelvin (K) at ambient pressure ([82]Schilling et al. 1993) and 160 K under pressure ([42]Gao et al. 1994). The nature of superconductivity in the cuprates and in the recently discovered iron-based superconductor family (T{sub c}=57 K) is still not fully understood. In contrast, there is a class of superconductors which is well-described by the Bardeen, Cooper, Schrieffer (BCS) theory - conventional superconductors. Great efforts were spent in searching for high-temperature (T{sub c} > 77 K) conventional superconductor but only T{sub c} = 39 K has been reached in MgB2 ([68]Nagamatsu et al. 2001). BCS theory puts no bounds for T{sub c} as follows from Eliashberg's formulation of BCS theory. T{sub c} can be high, if there is a favorable combination of high-frequency phonons, strong electron-phonon coupling, and a high density of states. It does not predict however in which materials all three parameters are large. At least it gives a clear indication that materials with light elements are favorable as light elements provide high frequencies in the phonon spectrum. The lightest element is hydrogen, and Ashcroft made a first prediction that metallic hydrogen will be a high-temperature superconductor ([6]Ashcroft 1968). As pressure of hydrogen metallization was too high (about 400-500 GPa) for experimental techniques then he proposed that compounds dominated by hydrogen (hydrides) also might be good high temperature superconductors ([6]Ashcroft 1968; [7]Ashcroft 2004). A lot of the followed calculations supported this idea. T{sub c} in the range of 50-235 kelvin was predicted for many hydrides. Unfortunately, only a moderate T{sub c} of 17 kelvin has been observed experimentally ([27]Eremets et al. 2008) so far. A goal of the present work is to find a

  14. Thermally moderated hollow fiber sorbent modules in rapidly cycled pressure swing adsorption mode for hydrogen purification

    KAUST Repository

    Lively, Ryan P.

    2012-10-01

    We describe thermally moderated multi-layered pseudo-monolithic hollow fiber sorbents entities, which can be packed into compact modules to provide small-footprint, efficient H2 purification/CO2 removal systems for use in on-site steam methane reformer product gas separations. Dual-layer hollow fibers are created via dry-jet, wet-quench spinning with an inner "active" core of cellulose acetate (porous binder) and zeolite NaY (69 wt% zeolite NaY) and an external sheath layer of pure cellulose acetate. The co-spun sheath layer reduces the surface porosity of the fiber and was used as a smooth coating surface for a poly(vinyl-alcohol) post-treatment, which reduced the gas permeance through the fiber sorbent by at least 7 orders of magnitude, essentially creating an impermeable sheath layer. The interstitial volume between the individual fibers was filled with a thermally-moderating paraffin wax. CO2 breakthrough experiments on the hollow fiber sorbent modules with and without paraffin wax revealed that the "passively" cooled paraffin wax module had 12.5% longer breakthrough times than the "non-isothermal" module. The latent heat of fusion/melting of the wax offsets the released latent heat of sorption/desorption of the zeolites. One-hundred rapidly cycled pressure swing adsorption cycles were performed on the "passively" cooled hollow fiber sorbents using 25 vol% CO2/75 vol% He (H2 surrogate) at 60 °C and 113 psia, resulting in a product purity of 99.2% and a product recovery of 88.1% thus achieving process conditions and product quality comparable to conventional pellet processes. Isothermal and non-isothermal dynamic modeling of the hollow fiber sorbent module and a traditional packed bed using gPROMS® indicated that the fiber sorbents have sharper fronts (232% sharper) and longer adsorbate breakthrough times (66% longer), further confirming the applicability of the new fiber sorbent approach for H2 purification. © 2012, Hydrogen Energy Publications, LLC

  15. Transport properties of liquid metal hydrogen under high pressures

    Science.gov (United States)

    Brown, R. C.; March, N. H.

    1972-01-01

    A theory is developed for the compressibility and transport properties of liquid metallic hydrogen, near to its melting point and under high pressure. The interionic force law is assumed to be of the screened Coulomb type, because hydrogen has no core electrons. The random phase approximation is used to obtain the structure factor S(k) of the system in terms of the Fourier transform of this force law. The long wavelenth limit of the structure factor S(o) is related to the compressibility, which is much lower than that of alkali metals at their melting points. The diffusion constant at the melting point is obtained in terms of the Debye frequency, using a frequency spectrum analogous with the phonon spectrum of a solid. A similar argument is used to obtain the combined shear and bulk viscosities, but these depend also on S(o). The transport coefficients are found to be about the same size as those of alkali metals at their melting points.

  16. Experimental verification of hydrogen isotope separation by pressure swing adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Kotoh, K. [Faculty of Eng., Kyushu Univ., 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Tanaka, M. [National Inst. for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu 509-5292 (Japan); Nakamura, Y.; Sakamoto, T. [Faculty of Eng., Kyushu Univ., 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Asakura, Y.; Uda, T. [National Inst. for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu 509-5292 (Japan); Sugiyama, T. [Faculty of Eng., Nagoya Univ., Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2008-07-15

    Focusing on synthetic zeolites that adsorb hydrogen isotopes at liquid N{sub 2} temperature with priority in the order of T{sub 2}, DT, D{sub 2}, HT, HD and H{sub 2}, we have been developing a pressure swing adsorption process system for hydrogen isotope separation. For this purpose, we carried out fundamental experiments of adsorption and desorption of a tracer D{sub 2} in bulk H{sub 2} with zeolite packed-bed columns. In this paper, the results are reported that D{sub 2} is enriched in the adsorbed phase at separation factors near 2.0, flowing through zeolite 5A and 13X packed-beds at 77.4 K. These are in agreement with values predicted from the multi-component equilibrium characteristics. In the gas samples recovered by evacuating the packed-beds, however, D{sub 2} was detected at a relative concentration of 1.20 or 1.32 to that in the feed gas. This lower range results from the isotopic mass effect in kinetic process. That suggests a highly D{sub 2}-enriched residual left during evacuation. This is verified with an unusually high enrichment factor of 6.68 or 9.21 for zeolite 5A or 13X measured in the residual sample desorbed from the packed-bed by heating up to room temperature. (authors)

  17. Development of Improved Composite Pressure Vessels for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Newhouse, Norman L. [Hexagon Lincoln, Lincoln, NE (United States)

    2016-04-29

    Hexagon Lincoln started this DOE project as part of the Hydrogen Storage Engineering Center of Excellence (HSECoE) contract on 1 February 2009. The purpose of the HSECoE was the research and development of viable material based hydrogen storage systems for on-board vehicular applications to meet DOE performance and cost targets. A baseline design was established in Phase 1. Studies were then conducted to evaluate potential improvements, such as alternate fiber, resin, and boss materials. The most promising concepts were selected such that potential improvements, compared with the baseline Hexagon Lincoln tank, resulted in a projected weight reduction of 11 percent, volume increase of 4 percent, and cost reduction of 10 percent. The baseline design was updated in Phase 2 to reflect design improvements and changes in operating conditions specified by HSECoE Partners. Evaluation of potential improvements continued during Phase 2. Subscale prototype cylinders were designed and fabricated for HSECoE Partners’ use in demonstrating their components and systems. Risk mitigation studies were conducted in Phase 3 that focused on damage tolerance of the composite reinforcement. Updated subscale prototype cylinders were designed and manufactured to better address the HSECoE Partners’ requirements for system demonstration. Subscale Type 1, Type 3, and Type 4 tanks were designed, fabricated and tested. Laboratory tests were conducted to evaluate vacuum insulated systems for cooling the tanks during fill, and maintaining low temperatures during service. Full scale designs were prepared based on results from the studies of this program. The operating conditions that developed during the program addressed adsorbent systems operating at cold temperatures. A Type 4 tank would provide the lowest cost and lightest weight, particularly at higher pressures, as long as issues with liner compatibility and damage tolerance could be resolved. A Type 1 tank might be the choice if the

  18. Neutron and high-pressure X-ray diffraction study of hydrogen-bonded ferroelectric rubidium hydrogen sulfate.

    Science.gov (United States)

    Binns, Jack; McIntyre, Garry J; Parsons, Simon

    2016-12-01

    The pressure- and temperature-dependent phase transitions in the ferroelectric material rubidium hydrogen sulfate (RbHSO4) are investigated by a combination of neutron Laue diffraction and high-pressure X-ray diffraction. The observation of disordered O-atom positions in the hydrogen sulfate anions is in agreement with previous spectroscopic measurements in the literature. Contrary to the mechanism observed in other hydrogen-bonded ferroelectric materials, H-atom positions are well defined and ordered in the paraelectric phase. Under applied pressure RbHSO4 undergoes a ferroelectric transition before transforming to a third, high-pressure phase. The symmetry of this phase is revised to the centrosymmetric space group P21/c, resulting in the suppression of ferroelectricity at high pressure.

  19. Performance Evaluation Tests of Insulated Pressure Vessels for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Martinez-Frias, J; Espinoza-Loza, F

    2002-03-01

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen or ambient-temperature compressed hydrogen. This flexibility results in multiple advantages with respect to compressed hydrogen tanks or low-pressure liquid hydrogen tanks. Our work is directed at verifying that commercially available aluminum-lined, fiber-wrapped pressure vessels can be safely used to store liquid hydrogen. A series of tests have been conducted, and the results indicate that no significant vessel damage has resulted from cryogenic operation. Future activities include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for certification of insulated pressure vessels.

  20. Potential hydrogen and oxygen partial pressures in legacy plutonium oxide packages at Oak Ridge

    Energy Technology Data Exchange (ETDEWEB)

    Veirs, Douglas K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-07

    An approach to estimate the maximum hydrogen and oxygen partial pressures within sealed containers is described and applied to a set of packages containing high-purity plutonium dioxide. The approach uses experimentally determined maximum hydrogen and oxygen partial pressures and scales the experimentally determined pressures to the relevant packaged material properties. The important material properties are the specific wattage and specific surface area (SSA). Important results from the experimental determination of maximum partial pressures are (1) the ratio of hydrogen to oxygen is stoichiometric, and (2) the maximum pressures increase with increasing initial rates of production. The material properties that influence the rates are the material specific wattage and the SSA. The unusual properties of these materials, high specific wattage and high SSA, result in higher predicted maximum pressures than typical plutonium dioxide in storage. The pressures are well within the deflagration range for mixtures of hydrogen and oxygen.

  1. Can hydrogen be stored inside carbon nanotubes under pressure in gigapascal range?

    OpenAIRE

    Zhang, X.H.; Gong, X. G.; Liu, Z. F.

    2006-01-01

    By using a newly fitted multi-parameter potential to describe the van der Waals interaction between carbon and molecular hydrogen, we study the hydrogen storage inside carbon nanotubes (CNT's) under pressure in gigapascal range. Comparing with the results of graphite, we find that the shape change of the nanotubes (the curvature effect) provides a different storage mechanism for hydrogen. The negative free energy change for hydrogen storage inside CNT's makes it possible to use CNT's as the n...

  2. Hydrogen Pressurization of LOX: High Risk/High Reward (Preprint)

    National Research Council Canada - National Science Library

    Turner, Andrew E; Leichner, Aaron

    2006-01-01

    ... filled with hydrogen gas. Airship commercial service, enabled by relatively low-cost hydrogen, died along with the longest vehicle ever to fly, even though thousands of passengers had been transported without incident prior to that time...

  3. Combined Solid State and High Pressure Hydrogen Storage

    DEFF Research Database (Denmark)

    Grube, Elisabeth; Jensen, Torben René

    Presented at The First European Early Stage Researcher's Conference on Hydrogen Storage in Belgrade, Serbia.......Presented at The First European Early Stage Researcher's Conference on Hydrogen Storage in Belgrade, Serbia....

  4. Hydrogen storage using a hot pressure swing reactor

    OpenAIRE

    Preuster, P.; Dürr, S.; Seidel, A.; Müller, K.; Bösmann, A.; Jorschick, Holger; Wasserscheid, Peter

    2017-01-01

    Our contribution demonstrates that hydrogen storage in stationary Liquid Organic Hydrogen Carrier (LOHC) systems becomes much simpler and significantly more efficient if both, the LOHC hydrogenation and the LOHC dehydrogenation reaction are carried out in the same reactor using the same catalyst. The finding that the typical dehydrogenation catalyst for hydrogen release from perhydro dibenzyltoluene (H18-DBT), Pt on alumina, turns into a highly active and very selective dibenzyltoluene hydrog...

  5. Hafnium - an optical hydrogen sensor spanning six orders in pressure

    NARCIS (Netherlands)

    Boelsma, C.; Bannenberg, L.J.; Van Setten, M. J.; Steinke, N.J.; van Well, A.A.; Dam, B.

    2017-01-01

    Hydrogen detection is essential for its implementation as an energy vector. So far, palladium is considered to be the most effective hydrogen sensing material. Here we show that palladium-capped hafnium thin films show a highly reproducible change in optical transmission in response to a hydrogen

  6. Solar Thermal Upper Stage Liquid Hydrogen Pressure Control Testing

    Science.gov (United States)

    Moore, J. D.; Otto, J. M.; Cody, J. C.; Hastings, L. J.; Bryant, C. B.; Gautney, T. T.

    2015-01-01

    High-energy cryogenic propellant is an essential element in future space exploration programs. Therefore, NASA and its industrial partners are committed to an advanced development/technology program that will broaden the experience base for the entire cryogenic fluid management community. Furthermore, the high cost of microgravity experiments has motivated NASA to establish government/aerospace industry teams to aggressively explore combinations of ground testing and analytical modeling to the greatest extent possible, thereby benefitting both industry and government entities. One such team consisting of ManTech SRS, Inc., Edwards Air Force Base, and Marshall Space Flight Center (MSFC) was formed to pursue a technology project designed to demonstrate technology readiness for an SRS liquid hydrogen (LH2) in-space propellant management concept. The subject testing was cooperatively performed June 21-30, 2000, through a partially reimbursable Space Act Agreement between SRS, MSFC, and the Air Force Research Laboratory. The joint statement of work used to guide the technical activity is presented in appendix A. The key elements of the SRS concept consisted of an LH2 storage and supply system that used all of the vented H2 for solar engine thrusting, accommodated pressure control without a thermodynamic vent system (TVS), and minimized or eliminated the need for a capillary liquid acquisition device (LAD). The strategy was to balance the LH2 storage tank pressure control requirements with the engine thrusting requirements to selectively provide either liquid or vapor H2 at a controlled rate to a solar thermal engine in the low-gravity environment of space operations. The overall test objective was to verify that the proposed concept could enable simultaneous control of LH2 tank pressure and feed system flow to the thruster without necessitating a TVS and a capillary LAD. The primary program objectives were designed to demonstrate technology readiness of the SRS concept

  7. Intracolonic hydrogen sulfide lowers blood pressure in rats.

    Science.gov (United States)

    Tomasova, Lenka; Dobrowolski, Leszek; Jurkowska, Halina; Wróbel, Maria; Huc, Tomasz; Ondrias, Karol; Ostaszewski, Ryszard; Ufnal, Marcin

    2016-11-30

    Research suggests that hydrogen sulfide (H2S) is an important biological mediator involved in various physiological processes including the regulation of arterial blood pressure (BP). Although H2S is abundant in the colon, the effects of gut-derived H2S on the circulatory system have not yet been investigated. We studied the effects of intracolonic administration of Na2S, a H2S donor, on systemic hemodynamics. Hemodynamics were recorded in anesthetized, normotensive Wistar Kyoto and spontaneously hypertensive rats at baseline and after intracolonic injection of either saline (controls) or Na2S·9H2O saline solution at a dose range of 10-300 mg/kg of BW. The H2S donor produced a significant, dose-dependent decrease in mean arterial blood pressure (MABP), which lasted several times longer than previously reported after parenteral infusions (>90 min). The effect was more pronounced in hypertensive than in normotensive rats. The Na2S-induced decrease in MABP was reduced by pretreatment with glibenclamide, an inhibitor of ATP-sensitive potassium-channels. Na2S did not affect mesenteric vein blood flow. Rats treated with Na2S showed increased portal blood levels of thiosulfate and sulfane sulfur, products of H2S oxidation. In contrast, rats treated with neomycin, an antibiotic, showed significantly decreased levels of thiosulfate and sulfane sulfur, and a tendency for greater hypotensive response to Na2S. The H2S donor decreased heart rate but did not affect ECG morphology and QTc interval. In conclusion the gut-derived H2S may contribute to the control of BP and may be one of the links between gut microbiota and hypertension. Furthermore, gut-derived H2S may be a therapeutic target in hypertension. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Characterization of the {beta}-phase of the palladium-hydrogen equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, K.J.

    1998-07-01

    The {beta}-phase of the P-C-T curves of the palladium-hydrogen system is encountered at high pressures of gaseous hydrogen and low temperatures of this system. The {beta}-phase is characterized by an increase in the concentration of hydrogen in the palladium lattice with an increase in pressure of the free hydrogen gas surrounding the palladium. The P-C-T curves in this study are determined by gravimetric measurements of the hydrided palladium sample to determine the amount of hydrogen within the palladium lattice. The amount of hydrogen is kept constant within the experimental system and the temperature is varied which changes the pressures. The objective of this experimental thesis is to accurately determine the P-C-T curves of palladium in the {beta}-phase region to pressures of 20,000 psia and medium to low temperature region of {minus}60 C to 100 C.

  9. Postadsorption Work Function Tuning via Hydrogen Pressure Control.

    Science.gov (United States)

    Edlbauer, Hermann; Zojer, Egbert; Hofmann, Oliver T

    2015-12-03

    The work function of metal substrates can be easily tuned, for instance, by adsorbing layers of molecular electron donors and acceptors. In this work, we discuss the possibility of changing the donor/acceptor mixing ratio reversibly after adsorption by choosing a donor/acceptor pair that is coupled via a redox reaction and that is in equilibrium with a surrounding gas phase. We discuss such a situation for the example of tetrafluoro-1,4-benzenediol (TFBD)/tetrafluoro-1,4-benzoquinone (TFBQ), adsorbed on Cu(111) and Ag(111) surfaces. We use density functional theory and ab initio thermodynamics to show that arbitrary TFBD/TFBQ mixing ratios can be set using hydrogen pressures attainable in low to ultrahigh vacuum. Adjusting the mixing ratio allows modifying the work function over a range of about 1 eV. Finally, we contrast single-species submonolayers with mixed layers to discuss why the resulting inhomogeneities in the electrostatic energy above the surface have different impacts on the interfacial level alignment and the work function.

  10. Effect of high pressure hydrogen on the mechanical characteristics of single carbon fiber

    Science.gov (United States)

    Jeon, Sang Koo; Kwon, Oh Heon; Jang, Hoon-Sik; Ryu, Kwon Sang; Nahm, Seung Hoon

    2018-02-01

    In this study, carbon fiber was exposed to a pressure of 7 MPa for 24 h in high pressure chamber. The tensile test for carbon fiber was conducted to estimate the effect on the high pressure hydrogen in the atmosphere. To determine the tensile strength and Weibull modulus, approximately thirty carbon fiber samples were measured in all cases, and carbon fiber exposed to high pressure argon was evaluated to verify only the effect of hydrogen. Additionally, carbon fiber samples were annealed at 1950 °C for 1 h for a comparison with normal carbon fiber and then tested under identical conditions. The results showed that the tensile strength scatter of normal carbon fiber exposed to hydrogen was relatively wider and the Weibull modulus was decreased. Moreover, the tensile strength of the annealed carbon fiber exposed to hydrogen was increased, and these samples indicated a complex Weibull modulus because the hydrogen stored in the carbon fiber influenced the mechanical characteristic.

  11. Empirical Method to Estimate Hydrogen Embrittlement of Metals as a Function of Hydrogen Gas Pressure at Constant Temperature

    Science.gov (United States)

    Lee, Jonathan A.

    2010-01-01

    High pressure Hydrogen (H) gas has been known to have a deleterious effect on the mechanical properties of certain metals, particularly, the notched tensile strength, fracture toughness and ductility. The ratio of these properties in Hydrogen as compared to Helium or Air is called the Hydrogen Environment Embrittlement (HEE) Index, which is a useful method to classify the severity of H embrittlement and to aid in the material screening and selection for safety usage H gas environment. A comprehensive world-wide database compilation, in the past 50 years, has shown that the HEE index is mostly collected at two conveniently high H pressure points of 5 ksi and 10 ksi near room temperature. Since H embrittlement is directly related to pressure, the lack of HEE index at other pressure points has posed a technical problem for the designers to select appropriate materials at a specific H pressure for various applications in aerospace, alternate and renewable energy sectors for an emerging hydrogen economy. Based on the Power-Law mathematical relationship, an empirical method to accurately predict the HEE index, as a function of H pressure at constant temperature, is presented with a brief review on Sievert's law for gas-metal absorption.

  12. Inspection of the hydrogen gas pressure with metal shield by cold neutron radiography at CMRR

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hang; Cao, Chao; Huo, Heyong; Wang, Sheng; Wu, Yang; Yin, Wei; Sun, Yong; Liu, Bin; Tang, Bin [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China)

    2017-04-11

    The inspection of the process of gas pressure change is important for some applications (e.g. gas tank stockpile or two phase fluid model) which need quantitative and non-touchable measurement. Neutron radiography provides a suitable tool for such investigations with nice resolution. The quantitative cold neutron radiography (CNR) is developed at China Mianyang Research Reactor (CMRR) to measure the hydrogen gas pressure with metal shield. Because of the high sensitivity to hydrogen, even small change of the hydrogen pressure can be inspected by CNR. The dark background and scattering neutron effect are both corrected to promote measurement precision. The results show that CNR can measure the hydrogen gas pressure exactly and the pressure value average relative error between CNR and barometer is almost 1.9%.

  13. Inspection of the hydrogen gas pressure with metal shield by cold neutron radiography at CMRR

    Science.gov (United States)

    Li, Hang; Cao, Chao; Huo, Heyong; Wang, Sheng; Wu, Yang; Yin, Wei; Sun, Yong; Liu, Bin; Tang, Bin

    2017-04-01

    The inspection of the process of gas pressure change is important for some applications (e.g. gas tank stockpile or two phase fluid model) which need quantitative and non-touchable measurement. Neutron radiography provides a suitable tool for such investigations with nice resolution. The quantitative cold neutron radiography (CNR) is developed at China Mianyang Research Reactor (CMRR) to measure the hydrogen gas pressure with metal shield. Because of the high sensitivity to hydrogen, even small change of the hydrogen pressure can be inspected by CNR. The dark background and scattering neutron effect are both corrected to promote measurement precision. The results show that CNR can measure the hydrogen gas pressure exactly and the pressure value average relative error between CNR and barometer is almost 1.9%.

  14. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa.

    Science.gov (United States)

    Borysow, Jacek; del Rosso, Leonardo; Celli, Milva; Moraldi, Massimo; Ulivi, Lorenzo

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  15. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Borysow, Jacek, E-mail: jborysow@mtu.edu; Rosso, Leonardo del; Celli, Milva; Ulivi, Lorenzo, E-mail: lorenzo.ulivi@isc.cnr.it [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del piano 10, I-50019 Sesto Fiorentino (Italy); Moraldi, Massimo [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino (Italy)

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  16. Effect of pressure on the solution structure and hydrogen bond properties of aqueous N-methylacetamide

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Rahul [Department of Chemistry, Indian Institute of Technology, Guwahati, Guwahati 781 039, Assam (India); Paul, Sandip, E-mail: sandipp@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology, Guwahati, Guwahati 781 039, Assam (India)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer NMA molecules are associated mostly through their hydrophobic methyl groups. Black-Right-Pointing-Pointer High pressure reduces association propensity causing dispersion of these moieties. Black-Right-Pointing-Pointer Orientational polarization of vicinal water molecules near O and H atoms of NMA. Black-Right-Pointing-Pointer NMA prefers to be a H-bond acceptor rather than a donor in interaction with water. Black-Right-Pointing-Pointer Energy of these hydrogen bonds reduces slightly at high pressure. -- Abstract: Effects of high pressure on hydrophobic and hydrogen bonding interactions are investigated by employing molecular dynamics (MD) simulations of aqueous N-methylacetamide (NMA) solutions. Such systems are of interest mainly because high pressure causes protein denaturation and NMA is a computationally effective model to understand the atomic-level picture of pressure-induced structural transitions of protein. Simulations are performed for five different pressure values ranging from 1 atm to 8000 atm. We find that NMA molecules are associated mostly through their hydrophobic methyl groups and high pressure reduces this association propensity, causing dispersion of these moieties. At high pressure, structural void decreases and the packing efficiency of water molecules around NMA molecules increases. Hydrogen bond properties calculations show favorable NMA-NMA hydrogen bonds as compared to those of NMA-water hydrogen bonds and preference of NMA to be a hydrogen bond acceptor rather than a donor in interaction with water.

  17. Liquid Hydrogen Regulated Low Pressure High Flow Pneumatic Panel AFT Arrow Analysis

    Science.gov (United States)

    Jones, Kelley, M.

    2013-01-01

    Project Definition: Design a high flow pneumatic regulation panel to be used with helium and hydrogen. The panel will have two circuits, one for gaseous helium (GHe) supplied from the GHe Movable Storage Units (MSUs) and one for gaseous hydrogen (GH2) supplied from an existing GH2 Fill Panel. The helium will supply three legs; to existing panels and on the higher pressure leg and Simulated Flight Tanks (SFTs) for the lower pressure legs. The hydrogen line will pressurize a 33,000 gallon vacuum jacketed vessel.

  18. Closing the pressure gap in x-ray photoelectron spectroscopy by membrane hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Delmelle, Renaud; Borgschulte, Andreas, E-mail: andreas.borgschulte@empa.ch [Laboratory for Advanced Analytical Technologies, Swiss Federal Laboratories for Materials Science and Technology (Empa), Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Laboratory for Hydrogen and Energy, Swiss Federal Laboratories for Materials Science and Technology (Empa), Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Probst, Benjamin; Alberto, Roger [Department of Chemistry, University of Zürich (UZH), CH-8057 Zürich (Switzerland); Züttel, Andreas [Laboratory for Hydrogen and Energy, Swiss Federal Laboratories for Materials Science and Technology (Empa), Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Ecole Polytechnique Fédérale de Lausanne (EPFL), SB, ISIC, LMER, CH-1015 Lausanne (Switzerland); Bleiner, Davide [Laboratory for Advanced Analytical Technologies, Swiss Federal Laboratories for Materials Science and Technology (Empa), Überlandstrasse 129, CH-8600 Dübendorf (Switzerland)

    2015-05-15

    Comprehensive studies of gas-solid reactions require the in-situ interaction of the gas at a pressure beyond the operating pressure of ultrahigh vacuum (UHV) X-ray photoelectron spectroscopy (XPS). The recent progress of near ambient pressure XPS allows to dose gases to the sample up to a pressure of 20 mbar. The present work describes an alternative to this experimental challenge, with a focus on H{sub 2} as the interacting gas. Instead of exposing the sample under investigation to gaseous hydrogen, the sample is in contact with a hydrogen permeation membrane, through which hydrogen is transported from the outside to the sample as atomic hydrogen. Thereby, we can reach local hydrogen concentrations at the sample inside an UHV chamber, which is equipped with surface science tools, and this corresponds to a hydrogen pressure up to 1 bar without affecting the sensitivity or energy resolution of the spectrometer. This experimental approach is validated by two examples, that is, the reduction of a catalyst precursor for CO{sub 2} hydrogenation and the hydrogenation of a water reduction catalyst for photocatalytic H{sub 2} production, but it opens the possibility of the new in situ characterisation of energy materials and catalysts.

  19. Storage of hydrogen by high pressure microencapsulation in glass

    Science.gov (United States)

    Yan, K. L.; Sellars, B. G.; Lo, J.; Johar, S.; Murthy, M. K.

    The storage of compressed hydrogen gas in cylindrical glass microcapsules is a new concept that offers potential merits of lightweight, low cost, and simplicity in system design. The strongly temperature dependent permeability of candidate glass materials to hydrogen gas allows compressed hydrogen gas to be stored and retrieved from microcapsules at required rates by appropriate temperature adjustments. The major emphasis of work has been placed on developing the processes and techniques for hollow fibre drawing, fabrication of microcapsules and test modules, evaluation of microcapsule properties, and laboratory-scale hydrogen charge and discharge trials. These development efforts were followed by those for refinement and optimization, with particular interest in improving microcapsule strength and dimensional consistency. Recently, axial tensile strengths of over 700 MPa were achieved for microcapsules with aspect ratios higher than 25:1. Hydrogen storage capacity of over 2 wt percent has been demonstrated in laboratory trials.

  20. Development of a high-pressure microbalance for hydrogen storage materials

    DEFF Research Database (Denmark)

    Vestbø, Andreas Peter; Jensen, Jens Oluf; Bjerrum, Niels

    2007-01-01

    Pressure-composition isotherms (PCI's) help to determine thermodynamic properties related to hydrogen uptake of materials. PCI's are normally obtained volumetrically with a Sieverts type apparatus or gravimetrically with a microbalance. A potential problem with the gravimetric technique...

  1. Hafnium-an optical hydrogen sensor spanning six orders in pressure.

    Science.gov (United States)

    Boelsma, C; Bannenberg, L J; van Setten, M J; Steinke, N-J; van Well, A A; Dam, B

    2017-06-05

    Hydrogen detection is essential for its implementation as an energy vector. So far, palladium is considered to be the most effective hydrogen sensing material. Here we show that palladium-capped hafnium thin films show a highly reproducible change in optical transmission in response to a hydrogen exposure ranging over six orders of magnitude in pressure. The optical signal is hysteresis-free within this range, which includes a transition between two structural phases. A temperature change results in a uniform shift of the optical signal. This, to our knowledge unique, feature facilitates the sensor calibration and suggests a constant hydrogenation enthalpy. In addition, it suggests an anomalously steep increase of the entropy with the hydrogen/metal ratio that cannot be explained on the basis of a classical solid solution model. The optical behaviour as a function of its hydrogen content makes hafnium well-suited for use as a hydrogen detection material.

  2. Hafnium—an optical hydrogen sensor spanning six orders in pressure

    Science.gov (United States)

    Boelsma, C.; Bannenberg, L. J.; van Setten, M. J.; Steinke, N.-J.; van Well, A. A.; Dam, B.

    2017-01-01

    Hydrogen detection is essential for its implementation as an energy vector. So far, palladium is considered to be the most effective hydrogen sensing material. Here we show that palladium-capped hafnium thin films show a highly reproducible change in optical transmission in response to a hydrogen exposure ranging over six orders of magnitude in pressure. The optical signal is hysteresis-free within this range, which includes a transition between two structural phases. A temperature change results in a uniform shift of the optical signal. This, to our knowledge unique, feature facilitates the sensor calibration and suggests a constant hydrogenation enthalpy. In addition, it suggests an anomalously steep increase of the entropy with the hydrogen/metal ratio that cannot be explained on the basis of a classical solid solution model. The optical behaviour as a function of its hydrogen content makes hafnium well-suited for use as a hydrogen detection material. PMID:28580959

  3. Insulated Pressure Vessels for Vehicular Hydrogen Storage: Analysis and Performance Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Martinez-Frias, J; Garcia-Villazana, O; Espinosa-Loza, F

    2001-06-26

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (fuel flexibility, lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The work described here is directed at verifying that commercially available pressure vessels can be safely used to store liquid hydrogen. The use of commercially available pressure vessels significantly reduces the cost and complexity of the insulated pressure vessel development effort. This paper describes a series of tests that have been done with aluminum-lined, fiber-wrapped vessels to evaluate the damage caused by low temperature operation. All analysis and experiments to date indicate that no significant damage has resulted. Required future tests are described that will prove that no technical barriers exist to the safe use of aluminum-fiber vessels at cryogenic temperatures. Future activities also include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for obtaining certification for insulated pressure vessels.

  4. Performance and Certification Testing of Insulated Pressure Vessels for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Martinez-Frias, J; Garcia-Villazana, O; Espinosa-Loza, F

    2001-06-03

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH2) or ambient-temperature compressed hydrogen (CH2). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (fuel flexibility, lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The work described here is directed at verifying that commercially available pressure vessels can be safely used to store liquid hydrogen. The use of commercially available pressure vessels significantly reduces the cost and complexity of the insulated pressure vessel development effort. This paper describes a series of tests that have been done with aluminum-lined, fiber-wrapped vessels to evaluate the damage caused by low temperature operation. All analysis and experiments to date indicate that no significant damage has resulted. Required future tests are described that will prove that no technical barriers exist to the safe use of aluminum-fiber vessels at cryogenic temperatures. Future activities also include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for obtaining certification for insulated pressure vessels.

  5. Hydrogen bonds and van der waals forces in ice at ambient and high pressures.

    Science.gov (United States)

    Santra, Biswajit; Klimeš, Jiří; Alfè, Dario; Tkatchenko, Alexandre; Slater, Ben; Michaelides, Angelos; Car, Roberto; Scheffler, Matthias

    2011-10-28

    The first principles methods, density-functional theory and quantum Monte Carlo, have been used to examine the balance between van der Waals (vdW) forces and hydrogen bonding in ambient and high-pressure phases of ice. At higher pressure, the contribution to the lattice energy from vdW increases and that from hydrogen bonding decreases, leading vdW to have a substantial effect on the transition pressures between the crystalline ice phases. An important consequence, likely to be of relevance to molecular crystals in general, is that transition pressures obtained from density-functional theory exchange-correlation functionals which neglect vdW forces are greatly overestimated.

  6. MICROSTRUCTURE AND MECHANICAL PROPERTY PERFORMANCE OF COMMERCIAL GRADE API PIPELINE STEELS IN HIGH PRESSURE GASEOUS HYDROGEN

    Energy Technology Data Exchange (ETDEWEB)

    Stalheim, Mr. Douglas [DGS Metallurgical Solutions Inc; Boggess, Todd [Secat; San Marchi, Chris [Sandia National Laboratories (SNL); Jansto, Steven [Reference Metals Company; Somerday, Dr. B [Sandia National Laboratories (SNL); Muralidharan, Govindarajan [ORNL; Sofronis, Prof. Petros [University of Illinois

    2010-01-01

    The continued growth of the world s developing countries has placed an ever increasing demand on traditional fossil fuel energy sources. This development has lead to increasing research and development of alternative energy sources. Hydrogen gas is one of the potential alternative energy sources under development. Currently the most economical method of transporting large quantities of hydrogen gas is through steel pipelines. It is well known that hydrogen embrittlement has the potential to degrade steel s mechanical properties when hydrogen migrates into the steel matrix. Consequently, the current pipeline infrastructure used in hydrogen transport is typically operated in a conservative fashion. This operational practice is not conducive to economical movement of significant volumes of hydrogen gas as an alternative to fossil fuels. The degradation of the mechanical properties of steels in hydrogen service is known to depend on the microstructure of the steel. Understanding the levels of mechanical property degradation of a given microstructure when exposed to hydrogen gas under pressure can be used to evaluate the suitability of the existing pipeline infrastructure for hydrogen service and guide alloy and microstructure design for new hydrogen pipeline infrastructure. To this end, the 2 Copyright 2010 by ASME microstructures of relevant steels and their mechanical properties in relevant gaseous hydrogen environments must be fully characterized to establish suitability for transporting hydrogen. A project to evaluate four commercially available pipeline steels alloy/microstructure performance in the presences of gaseous hydrogen has been funded by the US Department of Energy along with the private sector. The microstructures of four pipeline steels were characterized and then tensile testing was conducted in gaseous hydrogen and helium at pressures of 800, 1600 and 3000 psi. Based on measurements of reduction of area, two of the four steels that performed the best

  7. Sensor for measuring hydrogen partial pressure in parabolic trough power plant expansion tanks

    Science.gov (United States)

    Glatzmaier, Greg C.; Cooney, Daniel A.

    2017-06-01

    The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative work consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.

  8. Sensor for Measuring Hydrogen Partial Pressure in Parabolic Trough Power Plant Expansion Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, Greg C.; Cooney, Daniel A.

    2017-06-27

    The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative work consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.

  9. Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

    Science.gov (United States)

    Sasmal, G. P.; Hochstein, J. I.; Hardy, T. L.

    1993-01-01

    A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.

  10. Exergoeconomic optimization of coaxial tube evaporators for cooling of high pressure gaseous hydrogen during vehicle fuelling

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Rothuizen, Erasmus Damgaard; Markussen, Wiebke Brix

    2014-01-01

    Gaseous hydrogen as an automotive fuel is reaching the point of commercial introduction. Development of hydrogen fuelling stations considering an acceptable fuelling time by cooling the hydrogen to -40 C has started. This paper presents a design study of coaxial tube ammonia evaporators for three...... different concepts of hydrogen cooling, one onestage and two two-stage processes. An exergoeconomic optimization is imposed to all three concepts to minimize the total cost. A numerical heat transfer model is developed in Engineer Equation Solver, using heat transfer and pressure drop correlations from...

  11. Microstructure and mechanical property performance of commercial grade API pipeline steels in high pressure gaseous hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Stalheim, Douglas G. [DGS Metallurgical Solutions, Inc., Vancouver, WA, (United States); Boggess, Todd [Secat Inc., Lexington, KY, (United States); San Marchi, Chris; Somerday, Brian [Sandia National Laboratory, Livermore, CA, (United States); Jansto, Steve [Reference Metals Company, Bridgeville, PA, (United States); Muralidharan, Govindarajan [Oak Ridge National Laboratory, Oak Ridge, TN, (United States)

    2010-07-01

    The transportation of hydrogen by pipeline steels raises questions of the degradation of the mechanical properties of the steel. This study investigated the microstructure and mechanical property performance of pipeline steels in high pressure gaseous hydrogen. The performance of four commercially available pipeline steels have been tested in the presence of pressurized hydrogen gas at different pressures in the range of 5.5 MPa and 20.7 MPa. Microstructural characterizations, tensile testing, fracture testing and fatigue testing have been performed for each alloy. The results showed that the four pipeline steels perform differently in gaseous hydrogen. Yield strength does not seem to have a relevant effect on performance, which highlights the importance of the microstructure in determining the resistance of pipeline steels. Of the four microstructures, the polygonal ferrite/10% coarse acicular ferrite microstructure gave the best performance.

  12. A continuum damage analysis of hydrogen attack in a 2.25Cr–1Mo pressure vessel

    NARCIS (Netherlands)

    Burg, M.W.D. van der; Giessen, E. van der; Tvergaard, V.

    1998-01-01

    A micromechanically based continuum damage model is presented to analyze the stress, temperature and hydrogen pressure dependent material degradation process termed hydrogen attack, inside a pressure vessel. Hydrogen attack (HA) is the damage process of grain boundary facets due to a chemical

  13. Hydrogen Absorption in Weldments of Overlaid Claded Pressure Vessel

    Directory of Open Access Journals (Sweden)

    Ronnie Rusli

    2010-10-01

    Full Text Available Cracks was found in type 347 stainless steel internal attachment welds of a reactor for a high temperature, and highpressure hydrogen service. One of the possible causes of cracking is low cycle fatigue cracking induced by repetition ofthermal stress to embrittled weld metal. Type 347 weld metal loses its ductility by presence of sigma phase andhydrogen.

  14. Hydrogen Absorption in Weldments of Overlaid Claded Pressure Vessel

    OpenAIRE

    Ronnie Rusli

    2010-01-01

    Cracks was found in type 347 stainless steel internal attachment welds of a reactor for a high temperature, and highpressure hydrogen service. One of the possible causes of cracking is low cycle fatigue cracking induced by repetition ofthermal stress to embrittled weld metal. Type 347 weld metal loses its ductility by presence of sigma phase andhydrogen.

  15. Hydrogen Absorption in Weldments of Overlaid Claded Pressure Vessel

    OpenAIRE

    Ronnie Higuchi Rusli

    2008-01-01

    Cracks was found in type 347 stainless steel internal attachment welds of a reactor for a high temperature, and highpressure hydrogen service. One of the possible causes of cracking is low cycle fatigue cracking induced by repetition ofthermal stress to embrittled weld metal. Type 347 weld metal loses its ductility by presence of sigma phase andhydrogen.

  16. Approaches for reducing the insulator-metal transition pressure in hydrogen

    Science.gov (United States)

    Carlsson, A. E.; Ashcroft, N. W.

    1983-01-01

    Two possible techniques for reducing the external pressure required to induce the insulator-metal transition in solid hydrogen are described. One uses impurities to lower the energy of the metallic phase relative to that of the insulating phase. The other utilizes a negative pressure induced in the insulating phase by electron-hole pairs, created either with laser irradiation or pulsed synchrotron sources.

  17. Uncertainties in risk assessment of hydrogen discharges from pressurized storage vessels at low temperatures

    DEFF Research Database (Denmark)

    Markert, Frank; Melideo, D.; Baraldi, D.

    2013-01-01

    20K) e.g. the cryogenic compressed gas storage covers pressures up to 35 MPa and temperatures between 33K and 338 K. Accurate calculations of high pressure releases require real gas EOS. This paper compares a number of EOS to predict hydrogen properties typical in different storage types. The vessel...

  18. Numerical analysis of accidental hydrogen releases from high pressure storage at low temperatures

    DEFF Research Database (Denmark)

    Markert, Frank; Melideo, Daniele; Baraldi, Daniele

    2014-01-01

    ) and temperatures (down to 20 K), e.g. cryogenic compressed gas storage covers pressures up to 35 MPa and temperatures between 33 K and 338 K. Accurate calculations of high pressure releases require real gas EOS. This paper compares a number of EOS to predict hydrogen properties typical in different storage types...

  19. Hydrogen oxidation at high pressure and intermediate temperatures: experiments and kinetic modeling

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

    2015-01-01

    Hydrogen oxidation at 50 bar and temperatures of 700–900 K was investigated in a high pressure laminar flow reactor under highly diluted conditions. The experiments provided information about H 2 oxidation at pressures above the third explosion limit. The fuel–air equivalence ratio of the reactants...

  20. Analysis and Design of Cryogenic Pressure Vessels for Automotive Hydrogen Storage

    Science.gov (United States)

    Espinosa-Loza, Francisco Javier

    Cryogenic pressure vessels maximize hydrogen storage density by combining the high pressure (350-700 bar) typical of today's composite pressure vessels with the cryogenic temperature (as low as 25 K) typical of low pressure liquid hydrogen vessels. Cryogenic pressure vessels comprise a high-pressure inner vessel made of carbon fiber-coated metal (similar to those used for storage of compressed gas), a vacuum space filled with numerous sheets of highly reflective metalized plastic (for high performance thermal insulation), and a metallic outer jacket. High density of hydrogen storage is key to practical hydrogen-fueled transportation by enabling (1) long-range (500+ km) transportation with high capacity vessels that fit within available spaces in the vehicle, and (2) reduced cost per kilogram of hydrogen stored through reduced need for expensive structural material (carbon fiber composite) necessary to make the vessel. Low temperature of storage also leads to reduced expansion energy (by an order of magnitude or more vs. ambient temperature compressed gas storage), potentially providing important safety advantages. All this is accomplished while simultaneously avoiding fuel venting typical of cryogenic vessels for all practical use scenarios. This dissertation describes the work necessary for developing and demonstrating successive generations of cryogenic pressure vessels demonstrated at Lawrence Livermore National Laboratory. The work included (1) conceptual design, (2) detailed system design (3) structural analysis of cryogenic pressure vessels, (4) thermal analysis of heat transfer through cryogenic supports and vacuum multilayer insulation, and (5) experimental demonstration. Aside from succeeding in demonstrating a hydrogen storage approach that has established all the world records for hydrogen storage on vehicles (longest driving range, maximum hydrogen storage density, and maximum containment of cryogenic hydrogen without venting), the work also

  1. Peak pressures from hydrogen deflagrations in the PFP thermal stabilization glovebox

    Energy Technology Data Exchange (ETDEWEB)

    Van Keuren, J.C.

    1998-08-11

    This document describes the calculations of the peak pressures due to hydrogen deflagrations in the glovebox used for thermal stabilization (glovebox HC-21A) in PFP. Two calculations were performed. The first considered the burning of hydrogen released from a 7 inch Pu can in the Inert Atmosphere Confinement (IAC) section of the glovebox. The peak pressure increase was 12400 Pa (1.8 psi). The second calculation considered burning of the hydrogen from 25 g of plutonium hydride in the airlock leading to the main portion of the glovebox. Since the glovebox door exposes most of the airlock when open, the deflagration was assumed to pressurize the entire glovebox. The peak pressure increase was 3860 Pa (0.56 psi).

  2. Compressed hydrogen-bond effects in the pressure-frozen chloroacetic acid.

    Science.gov (United States)

    Gajda, Roman; Katrusiak, Andrzej

    2007-12-01

    The competing effects of squeezed OH...O bonds, destabilizing the H-atom position, and of displaced hydrogen donor and acceptor groups, favouring the ordered H-atom sites, have been tuned by pressure in the pressure-frozen dichloroacetic acid. Its structure has been determined at 0.1, 0.7, 0.9 and 1.4 GPa: in this pressure range the crystals are stable in the monoclinic space group P2(1)/n. The molecules are O-H...O hydrogen bonded into dimers, which in turn interact via a unique pattern of halogen...halogen contacts. Between 0.1 and 1.4 GPa the OH...O bond is squeezed from 2.674 (13) to 2.632 (9) A. Within the pressure range investigated the hydrogen bonds are squeezed and the shear displacement of the molecules compensate, and the H atoms remain ordered.

  3. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Mohsen (University of Illinois at Urbana-Champaign, Urbana, IL); Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros (University of Illinois at Urbana-Champaign, Urbana, IL); Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A. (CP Industries, McKeesport, PA)

    2010-07-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  4. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Surrey, Alexander, E-mail: a.surrey@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Schultz, Ludwig [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Rellinghaus, Bernd, E-mail: b.rellinghaus@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)

    2017-04-15

    Highlights: • Multislice HRTEM contrast simulations of a windowed environmental cell. • Study of Mg and MgH2 nanocrystals as model system in hydrogen at ambient pressure. • Investigation of spatial resolution and contrast depending on specimen thickness, defocus, and hydrogen pressure. • Atomic resolution is expected for specimens as thin as 5  nm. - Abstract: The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a “nanoreactor” is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH{sub 2}, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  5. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    Science.gov (United States)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  6. The pipeline fracture behavior and pressure assessment under HIC (Hydrogen induced cracking) environment

    Energy Technology Data Exchange (ETDEWEB)

    Shaohua, Dong [China National Petroleum Corporation (CNPC), Beijing (China); Lianwei, Wang [University of Science and Technology Beijing (USTB), Beijing (China)

    2009-07-01

    As Hydrogen's transmit and diffuse, after gestating for a while, the density of hydrogen around crack tip of pipeline will get to the critical density, and the pipeline material will descend, make critical stress factor, the reason of pipeline Hydrogen Induced Cracking is Hydrogen's transmit and diffuse. The stress factor of Hydrogen Induced Cracking under surroundings-condition of stress is the key that estimate material's rupture behavior. The paper study the relationship among hydrogen concentrate, crack tip stress, stain field, hydrogen diffusion and inner pressure for crack tip process zone, then determined the length of HIC (hydrogen induced cracking) process zone. Based on the theory of propagation which reason micro-crack making core, dislocation model is produced for fracture criteria of HIC, the influence between material and environments under the HIC is analyzed, step by step pipeline maximum load pressure and threshold of J-integrity ( J{sub ISCC} ) is calculated, which is very significant for pipeline safety operation. (author)

  7. Continuous process for the pressure hydrogenation of coals, tars, and mineral oils in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    1943-05-25

    In the continuous pressure hydrogenation of coals, tars, and mineral oils in liquid phase as, for example, of coal or oil pastes, the liquid together with the hydrogen required for the reaction was, at the time of this report, preheated under pressure in a special preheater and brought to the reaction temperature. At this temperature, the mixture then entered the reaction vessel. Here, due to the absorption of hydrogen by the hydrogenation feed, so much heat was generated that in practical operations, cooling had to be provided for. This report dealt with an investigation that solved this problem. In this process hydrogenation feed, together with hydrogen, entered at the bottom of one section of a reaction vessel which was divided by separating walls into two vertical sections, which were connected with each other at the top and the bottom, so that hydrogenation feed was given a circulating motion between the two sections of the vessel, whereby the greatest part of the hydrogen mass, together with the vaporous mass, and as a rule, also a part of the liquid, was drawn off at the top. A description of the operation and the equipment involved was given. A sketch containing six figures was also included showing the flow of the materials.

  8. The Sticking Probability for Hydrogen on Ni, Pd, and Pt at a Hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2007-01-01

    are extracted from measurements of the local gas composition over the catalytic surface, with the help of a model for the H-D exchange reaction. The sticking probability is lowest for Ni and similar for Pd and Pt. The apparent energies of desorption derived from the adsorption rates decrease in the order Ni, Pd......A technique for measurements of the sticking probability of hydrogen on metal surfaces at high (ambient) pressure is described. As an example, measurements for Ni, Pd and Pt at a hydrogen pressure of 1 bar and temperatures between 40 and 200 degrees C are presented. The sticking probabilities......, Pt. The transition between beta- and alpha-phase in the H-Pd system has a significant effect on the activity for Pd....

  9. The role of hydrogen partial pressure on the annealing of copper substrates for graphene CVD synthesis

    Science.gov (United States)

    Ramos, Welyson T. S.; Cunha, Thiago H. R.; Barcelos, Ingrid D.; Miquita, Douglas R.; Ferrari, Gustavo A.; de Oliveira, Sergio; Seara, Luciana M.; Silva Neto, Eliel G.; Ferlauto, Andre S.; Lacerda, Rodrigo G.

    2016-04-01

    The influence of hydrogen utilized during the thermal treatment of copper substrates on the subsequent graphene growth is investigated. It is known that various parameters such as nature of the carbon precursor, temperature and pressure strongly affect the quality of the graphene grown by chemical vapor deposition. Another important parameter is the hydrogen partial pressure adjusted during the growth stage and in the pre-growth annealing of the substrate. In attempts to elucidate the role of hydrogen assisted thermal annealing on the copper substrate morphology and on the subsequent graphene growth, we subjected Cu foils to thermal annealing under H2 atmosphere at different pressures. The copper surface was characterized by scanning electronic microscopy (SEM) and atomic force microscopy whereas graphene films and grains were characterized by Raman spectroscopy and SEM. Our findings suggest that hydrogen not only affect the Cu surface but also diffuses into the substrate, being stored in the bulk material during the thermal treatment of the substrate. The release of hydrogen species in the subsequent stages of growth can result in damage to the graphene layer or induce the nucleation of additional layers depending on the growth and pre-growth conditions. Therefore, the use of hydrogen during the annealing of ‘low purity Cu foils’ should be carefully planned in order to obtain high quality graphene via LPCVD.

  10. Unexpectedly high pressure for molecular dissociation in liquid hydrogen by electronic simulation.

    Science.gov (United States)

    Mazzola, Guglielmo; Yunoki, Seiji; Sorella, Sandro

    2014-03-19

    The study of the high pressure phase diagram of hydrogen has continued with renewed effort for about one century as it remains a fundamental challenge for experimental and theoretical techniques. Here we employ an efficient molecular dynamics based on the quantum Monte Carlo method, which can describe accurately the electronic correlation and treat a large number of hydrogen atoms, allowing a realistic and reliable prediction of thermodynamic properties. We find that the molecular liquid phase is unexpectedly stable, and the transition towards a fully atomic liquid phase occurs at much higher pressure than previously believed. The old standing problem of low-temperature atomization is, therefore, still far from experimental reach.

  11. Screening of hydrogen storage media applying high pressure thermogravimetry

    DEFF Research Database (Denmark)

    Bentzen, J.J.; Pedersen, Allan Schrøder; Kjøller, J.

    2001-01-01

    A number of commercially available hydride-forming alloys of the MmNi5–xSnx (Mm=mischmetal, a mixture of lanthanides) type were examined using a high pressure, high temperature microbalance,scanning electron microscopy and X-ray diffraction. Activation conditions, reversible storage capacity, wor...

  12. Quantum theoretical study of hydrogen under high pressure

    CERN Document Server

    Biermann, S

    2001-01-01

    In the first chapter we will review our knowledge of the phase diagram of hydrogen. Chapter 2 is a summary of the standard density functional and molecular dynamics methods and shows how these are combined in the Car-Parrinello method. Here the nuclei are still treated as classical particles obeying Newtonian mechanics. In chapter 3 we drop this approximation. The path integral description of quantum statistics is added on top of the classical Car-Parrinello method and yields a formalism that includes quantum effects due to the finite de Broglie wavelength of the nuclei. Some technical aspects, namely the parallel implementation of the Path Integral Car-Parrinello (PICP) method, are discussed in chapter 4. In chapter 5 we present the results of our PICP calculations and compare them with prior calculations using the classical Car-Parrinello method as described in chapter 2.

  13. Polymeric hydrogen diffusion barrier, high-pressure storage tank so equipped, method of fabricating a storage tank and method of preventing hydrogen diffusion

    Science.gov (United States)

    Lessing, Paul A [Idaho Falls, ID

    2008-07-22

    An electrochemically active hydrogen diffusion barrier which comprises an anode layer, a cathode layer, and an intermediate electrolyte layer, which is conductive to protons and substantially impermeable to hydrogen. A catalytic metal present in or adjacent to the anode layer catalyzes an electrochemical reaction that converts any hydrogen that diffuses through the electrolyte layer to protons and electrons. The protons and electrons are transported to the cathode layer and reacted to form hydrogen. The hydrogen diffusion barrier is applied to a polymeric substrate used in a storage tank to store hydrogen under high pressure. A storage tank equipped with the electrochemically active hydrogen diffusion barrier, a method of fabricating the storage tank, and a method of preventing hydrogen from diffusing out of a storage tank are also disclosed.

  14. Polymeric hydrogen diffusion barrier, high-pressure storage tank so equipped, method of fabricating a storage tank and method of preventing hydrogen diffusion

    Science.gov (United States)

    Lessing, Paul A.

    2004-09-07

    An electrochemically active hydrogen diffusion barrier which comprises an anode layer, a cathode layer, and an intermediate electrolyte layer, which is conductive to protons and substantially impermeable to hydrogen. A catalytic metal present in or adjacent to the anode layer catalyzes an electrochemical reaction that converts any hydrogen that diffuses through the electrolyte layer to protons and electrons. The protons and electrons are transported to the cathode layer and reacted to form hydrogen. The hydrogen diffusion barrier is applied to a polymeric substrate used in a storage tank to store hydrogen under high pressure. A storage tank equipped with the electrochemically active hydrogen diffusion barrier, a method of fabricating the storage tank, and a method of preventing hydrogen from diffusing out of a storage tank are also disclosed.

  15. Catalytic pressurization of liquid hydrogen fuel tanks for unmanned aerial vehicles

    Science.gov (United States)

    Leachman, Jacob; Street, Melissa Jean; Graham, Teira

    2012-06-01

    As the use and applications of Unmanned Aerial Vehicles (UAV) expand, the need for a lighter weight fuel allowing for longer duration flights has become the primary limiting factor in the advancement of these vehicles. To extend the operational envelope of UAV, onboard condensed hydrogen storage for missions exceeding one week is necessary. Currently, large spherical liquid hydrogen tanks that are pressurized with external helium tanks or electronic heating elements are utilized for this purpose. However, the mass, size, and power consumption of the fuel storage tank and fuel pressurization system significantly limit the flight envelope of UAV. In an effort to alleviate these issues, this paper investigates the technological feasibility of orthohydrogen-parahydrogen catalysis as a method of fuel pressurization. Typical pressurization requirements for takeoff, cruise, and landing are reviewed. Calculations of the catalyst system mass and response time are presented.

  16. Enthalpy measurement of coal-derived liquids. Final technical progress report. [200 to 740/sup 0/F and 200 to 1500 psia

    Energy Technology Data Exchange (ETDEWEB)

    Kidnay, A.J.; Yesavage, V.F.

    1981-05-01

    This final report presents the results of the enthalpy measurements on the model compound m-cresol. The measurements cover the temperature range 200 to 740/sup 0/F and the pressure range 200 to 1500 psia. These data are compared with earlier data taken on m-cresol and with other thermophysical properties taken from the literature.

  17. Numerical simulation of premixed Hydrogen/air combustion pressure in a spherical vessel

    OpenAIRE

    Guo Han-yu; Tao Gang; Zhang Li-jing

    2016-01-01

    In order to study the development process of hydrogen combustion in a closed vessel, an on-line chemical equilibrium calculator and a numerical simulation method would be used to analysis the combustion pressure and flame front of mixed gas, which based on 20L H2/air explosion experiments in spherical vessel (Crowl and Jo,2009). The results showed that, the turbulent model could reflect the process of combustion, and the error of combustion pressure by simulation is smaller than the Chemical ...

  18. Porous-like structures prepared by temperature-pressure treatment of heavily hydrogenated silicon

    Energy Technology Data Exchange (ETDEWEB)

    Misiuk, A. [Institute of Electron Technology, Al. Lotnikow 46, 02-668 Warsaw (Poland); Shalimov, A.; Bak-Misiuk, J. [Institute of Physics, PAS, Al. Lotnikow 32, 02-668 Warsaw (Poland); Surma, B. [Institute of Electron Technology, Al. Lotnikow 46, 02-668 Warsaw (Poland); Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Wnuk, A. [Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Antonova, I.V. [Institute of Semiconductor Physics, SB RAS, Lavrentieva 13, 630090 Novosibirsk (Russian Federation); Zavodinsky, V.G.; Gnidenko, A.A. [Institute of Materials Science, RAS, Tikhookeanskaya 153, 680042 Khabarovsk (Russian Federation)

    2005-06-01

    Microstructure and related properties of Czochralski silicon heavily doped with hydrogen by implantation (hydrogen dose 2.7 x 10{sup 17} cm{sup -2}, at 24 keV) or by hydrogen plasma etching (reference samples) and treated at up to 1270 K (HT) under argon pressure up to 1.1 GPa (HP) are investigated. The structure of HT-HP treated Cz-Si:H is similar to that of porous (spongy) Si. Visible photoluminescence at 2.0-2.8 eV originates from accumulation of hydrogen and oxygen atoms near the sample surface. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Tank designs for combined high pressure gas and solid state hydrogen storage

    DEFF Research Database (Denmark)

    Mazzucco, Andrea

    Many challenges have still to be overcome in order to establish a solid ground for significant market penetration of fuel cell hydrogen vehicles. The development of an effective solution for on-board hydrogen storage is one of the main technical tasks that need to be tackled. The present thesis...... for each storage solution investigated in this work. Attention is given to solutions that involve high-pressure solid-state and gas hydrogen storage with an integrated passive cooling system. A set of libraries is implemented in the modeling platform to select among different material compositions, kinetic...... compressed-hydrogen vessel respectively. For the former, these models are used to quantify the main design parameter, being the critical metal hydride thickness, for the tank/heat-exchanger system. For the metal hydride tank, the tubular layout in a shell and tube configuration with 2 mm inner diameter tubes...

  20. Transient flow in pipelines of high-pressure hydrogen-natural gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Elaoud, Sami; Hadj-Taieb, Ezzeddine [Unit of Applied Fluid Mechanics and Modeling, ENIS, Sokra Road Km 4, P.O. Box W, Sfax 3038 (Tunisia)

    2008-09-15

    The purpose of this study is the numerical modeling of high-pressure transient flow of hydrogen-natural gas mixtures in rigid pipelines. The governing equations for such flows are two coupled, non-linear, hyperbolic, partial differential equations. The fluid pressure and velocity are considered as two principal dependent variables. The fluid is a homogeneous hydrogen-natural gas mixture for which the density is defined by an expression averaging the two gas densities where a polytropic process is admitted for the two components. The hydrogen-mixture mass ratio (or quality), assumed to be constant, is used in the mathematical formulation, instead of the void fraction which varies with pressure. The problem has been solved by the non-linear method of characteristics and the finite difference conservative method. To verify their validity, the computed results of the two numerical methods are compared for different values of the quality. The occurrence of pressure oscillations in hydrogen-natural gas mixture pipelines was studied as a result of the compression wave created by a rapid closure of downstream shut-off valve. (author)

  1. Characteristics of the absorption and the emission of hydrogen in palladium nanoparticles encapsulated into graphite at 1.0 MPa hydrogen pressure

    OpenAIRE

    Tanaka, Toshihiro; Hara, Shigeta; Hirai, Nobumitsu; Takashima, Masayuki

    2004-01-01

    Palladium nanoparticles encapsulated into graphite (Pd–graphite intercalation compound: Pd–GIC) were produced from two kinds of graphite, natural graphite (average flake size: 270 mm) and kish graphite (average flake size: 15 mm). Hydrogen storage properties of Pd– GIC have been investigated by means of differential scanning calorimetry (DSC) between 473 and 573 K at 1.0 MPa hydrogen pressure. It is found from the DSC measurement that Pd–GIC can absorb and emit hydrogen.

  2. Pressure-induced chemistry in a nitrogen-hydrogen host-guest structure.

    Science.gov (United States)

    Spaulding, Dylan K; Weck, Gunnar; Loubeyre, Paul; Datchi, Fréderic; Dumas, Paul; Hanfland, Michael

    2014-12-08

    New topochemistry in simple molecular systems can be explored at high pressure. Here we examine the binary nitrogen/hydrogen system using Raman spectroscopy, synchrotron X-ray diffraction, synchrotron infrared microspectroscopy and visual observation. We find a eutectic-type binary phase diagram with two stable high-pressure van der Waals compounds, which we identify as (N2)6(H2)7 and N2(H2)2. The former represents a new type of van der Waals host-guest compound in which hydrogen molecules are contained within channels in a nitrogen lattice. This compound shows evidence for a gradual, pressure-induced change in bonding from van der Waals to ionic interactions near 50 GPa, forming an amorphous dinitrogen network containing ionized ammonia in a room-temperature analogue of the Haber-Bosch process. Hydrazine is recovered on decompression. The nitrogen-hydrogen system demonstrates the potential for new pressure-driven chemistry in high-pressure structures and the promise of tailoring molecular interactions for materials synthesis.

  3. A topological study of chemical bonds under pressure: solid hydrogen as a model case.

    Science.gov (United States)

    Riffet, Vanessa; Labet, Vanessa; Contreras-García, Julia

    2017-10-04

    It is now well recognized that a fundamental understanding of the rules that govern chemistry under pressure is still lacking. Hydrogen being the "simplest" element as well as a central core to high pressure physics, we undertake a general study of the changes in the chemical bonding under pressure. We start from a simple trimer unit that has been found in high pressure phases, whose behavior has been found to reveal the basics of hydrogen polymerization under pressure. Making use of bond analysis tools, mainly the NCI (noncovalent interactions) index, we show that polymerization takes place in three steps: dipolar attraction, repulsion and bond formation. The use of a 1D Wigner-Seitz radius allowed us to extend the conclusions to 3D networks and to analyze their degree of polymerization. On the one hand, this approach provides new insight into the polymerization of hydrogen. On the other hand, it shows that complicated molecular solids can be understood from cluster models, where correlated methods can be applied, main differences in solid state arising at the transition points, where breaking/forming of bonds happens at once instead of continuously like in the cluster model.

  4. Pressure-induced chemistry in a nitrogen-hydrogen host-guest structure

    Science.gov (United States)

    Spaulding, Dylan K.; Weck, Gunnar; Loubeyre, Paul; Datchi, Fréderic; Dumas, Paul; Hanfland, Michael

    2014-12-01

    New topochemistry in simple molecular systems can be explored at high pressure. Here we examine the binary nitrogen/hydrogen system using Raman spectroscopy, synchrotron X-ray diffraction, synchrotron infrared microspectroscopy and visual observation. We find a eutectic-type binary phase diagram with two stable high-pressure van der Waals compounds, which we identify as (N2)6(H2)7 and N2(H2)2. The former represents a new type of van der Waals host-guest compound in which hydrogen molecules are contained within channels in a nitrogen lattice. This compound shows evidence for a gradual, pressure-induced change in bonding from van der Waals to ionic interactions near 50 GPa, forming an amorphous dinitrogen network containing ionized ammonia in a room-temperature analogue of the Haber-Bosch process. Hydrazine is recovered on decompression. The nitrogen-hydrogen system demonstrates the potential for new pressure-driven chemistry in high-pressure structures and the promise of tailoring molecular interactions for materials synthesis.

  5. New nitrogen-containing materials for hydrogen storage and their characterization by high-pressure microbalance

    DEFF Research Database (Denmark)

    Vestbø, Andreas Peter

    or liquid form, technologies that are well developed and usable, but not energy efficient. Certain metals and alloys are able to contain hydrogen within practical pressure and temperature ranges very efficient volume-wise, but they are too heavy for use in cars. Recently, attention has turned to the so......-called complex hydrides, which contain hydrogen bound covalently often in very light materials involving elements such as lithium, sodium, nitrogen and aluminum. While these materials typically have high decomposition temperatures, the combination with other compounds helps to destabilize the material resulting...

  6. Protein kinase G Iα oxidation paradoxically underlies blood pressure lowering by the reductant hydrogen sulfide.

    Science.gov (United States)

    Stubbert, Daniel; Prysyazhna, Oleksandra; Rudyk, Olena; Scotcher, Jenna; Burgoyne, Joseph R; Eaton, Philip

    2014-12-01

    Dysregulated blood pressure control leading to hypertension is prevalent and is a risk factor for several common diseases. Fully understanding blood pressure regulation offers the possibility of developing rationale therapies to alleviate hypertension and associated disease risks. Although hydrogen sulfide (H2S) is a well-established endogenous vasodilator, the molecular basis of its blood-pressure lowering action is incompletely understood. H2S-dependent vasodilation and blood pressure lowering in vivo was mediated by it catalyzing formation of an activating interprotein disulfide within protein kinase G (PKG) Iα. However, this oxidative activation of PKG Iα is counterintuitive because H2S is a thiol-reducing molecule that breaks disulfides, and so it is not generally anticipated to induce their formation. This apparent paradox was explained by H2S in the presence of molecular oxygen or hydrogen peroxide rapidly converting to polysulfides, which have oxidant properties that in turn activate PKG by inducing the disulfide. These observations are relevant in vivo because transgenic knockin mice in which the cysteine 42 redox sensor within PKG has been systemically replaced with a redox-dead serine residue are resistant to H2S-induced blood pressure lowering. Thus, a primary mechanism by which the reductant molecule H2S lowers blood pressure is mediated somewhat paradoxically by the oxidative activation of PKG. © 2014 American Heart Association, Inc.

  7. DEVELOPMENT OF ASME SECTION X CODE RULES FOR HIGH PRESSURE COMPOSITE HYDROGEN PRESSURE VESSELS WITH NON-LOAD SHARING LINERS

    Energy Technology Data Exchange (ETDEWEB)

    Rawls, G.; Newhouse, N.; Rana, M.; Shelley, B.; Gorman, M.

    2010-04-13

    The Boiler and Pressure Vessel Project Team on Hydrogen Tanks was formed in 2004 to develop Code rules to address the various needs that had been identified for the design and construction of up to 15000 psi hydrogen storage vessel. One of these needs was the development of Code rules for high pressure composite vessels with non-load sharing liners for stationary applications. In 2009, ASME approved new Appendix 8, for Section X Code which contains the rules for these vessels. These vessels are designated as Class III vessels with design pressure ranging from 20.7 MPa (3,000 ps)i to 103.4 MPa (15,000 psi) and maximum allowable outside liner diameter of 2.54 m (100 inches). The maximum design life of these vessels is limited to 20 years. Design, fabrication, and examination requirements have been specified, included Acoustic Emission testing at time of manufacture. The Code rules include the design qualification testing of prototype vessels. Qualification includes proof, expansion, burst, cyclic fatigue, creep, flaw, permeability, torque, penetration, and environmental testing.

  8. Superconducting phases of phosphorus hydride under pressure. Stabilization by mobile molecular hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Tiange; Miller, Daniel P.; Shamp, Andrew; Zurek, Eva [Department of Chemistry, State University of New York, Buffalo, NY (United States)

    2017-08-14

    At 80 GPa, phases with the PH{sub 2} stoichiometry, which are composed of simple cubic like phosphorus layers capped with hydrogen atoms and layers of H{sub 2} molecules, are predicted to be important species contributing to the recently observed superconductivity in compressed phosphine. The electron-phonon coupling in these phases results from the motions of the phosphorus atoms and the hydrogen atoms bound to them. The role of the mobile H{sub 2} layers is to decrease the Coulomb repulsion between the negatively charged hydrogen atoms capping the phosphorus layers. An insulating PH{sub 5} phase, the structure and bonding of which is reminiscent of diborane, is also predicted to be metastable at this pressure. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Effect of the initial pressure and temperature on the combustion characteristics of hydrogen-containing mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Shebeko, IU.N.; Korol' chenko, A.IA.; Tsarichenko, S.G.; Navtsenia, V.IU.; Malkin, V.L.

    1989-06-01

    Experiments were carried out to investigate the effect of initial pressure and temperature on the normal combustion velocity of stoichiometric hydrogen-containing mixtures with additions of steam and on the lower concentration limit of flame propagation of oxyhydrogen gas ({sup 2}H{sub 2}-O{sub 2}) in steam. It is shown that the baric index of the normal combustion velocity is positive for hydrogen-air mixtures containing no steam and negative for mixtures with a steam content greater than 5 percent. In oxyhydrogen gas mixtures with saturated and superheated steam, the initial pressure is found to have little effect on the lower concentration limit of flame propagation. 18 refs.

  10. Thermodynamics of the hydrogen dominant potassium hydride superconductor at high pressure

    OpenAIRE

    Szczȩśniak, D.; Szczȩśniak, R.

    2015-01-01

    In the present paper we report comprehensive analysis of the thermodynamic properties of novel hydrogen dominant potassium hydride superconductor (KH$_{6}$). Our computations are conducted within the Eliashberg theory which yields quantitative estimations of the most important thermodynamic properties of superconducting phase. In particular, we observe, that together with the increasing pressure all the thermodynamic properties decrease, e.g. $T_{C} \\in \\left$ K for $p ...

  11. Quasi-two-dimensional metallic hydrogen inside di-phosphide at high pressure

    OpenAIRE

    Degtyarenko, Nikolay; Mazur, Evgeny

    2016-01-01

    The method of mathematical modeling was used for the calculation of the structural, electronic, phonon, and other characteristics of various normal phases of phosphorus hydrides with stoichiometry PHk. It was shown that the di-phosphine may form 2D lattice of the metallic hydrogen, stabilized by phosphorus atoms under high hydrostatic compressive pressure. The resulting structure with the elements of H-P-H is a locally stable one in the phonon spectrum (or metastable). The properties of di-ph...

  12. High pressure in situ diffraction studies of metal-hydrogen systems

    Energy Technology Data Exchange (ETDEWEB)

    Yartys, V.A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, Kjeller NO 2027 (Norway); Norwegian University of Science and Technology, Trondheim NO 7491 (Norway); Denys, R.V. [Institute for Energy Technology, Kjeller NO 2027 (Norway); Karpenko Physico-Mechanical Institute, NAS of Ukraine, Lviv 79601 (Ukraine); Webb, C.J. [Queensland Micro- and Nanotechnology Centre, Griffith University (Australia); Maehlen, J.P. [Institute for Energy Technology, Kjeller NO 2027 (Norway); Gray, E. MacA.; Blach, T. [Queensland Micro- and Nanotechnology Centre, Griffith University (Australia); Isnard, O. [Institute Neel, CNRS/UJF, 38042 Grenoble (France); Barnsley, L.C. [Queensland Micro- and Nanotechnology Centre, Griffith University (Australia)

    2011-09-15

    Research highlights: > CeNi{sub 5}-D{sub 2} and Zr(Fe,Al){sub 2}-D{sub 2} systems were studied by in situ NPD at P up to 1000 bar. > In the hexagonal CeNi{sub 5}D{sub 6.3} deuterium atoms fill three types of interstices. > In the Zr(Fe,Al){sub 2}-based deuterides D atoms occupy the Zr(Fe,Al){sub 2} tetrahedra only D/Zr(Fe,Al){sub 2}, hysteresis and hydrides stability systematically change with Al content. - Abstract: 'Hybrid' hydrogen storage, where hydrogen is stored in both the solid material and as a high pressure gas in the void volume of the tank can improve overall system efficiency by up to 50% compared to either compressed hydrogen or solid materials alone. Thermodynamically, high equilibrium hydrogen pressures in metal-hydrogen systems correspond to low enthalpies of hydrogen absorption-desorption. This decreases the calorimetric effects of the hydride formation-decomposition processes which can assist in achieving high rates of heat exchange during hydrogen loading-removing the bottleneck in achieving low charging times and improving overall hydrogen storage efficiency of large hydrogen stores. Two systems with hydrogenation enthalpies close to -20 kJ/mol H{sub 2} were studied to investigate the hydrogenation mechanism and kinetics: CeNi{sub 5}-D{sub 2} and ZrFe{sub 2-x}Al{sub x} (x = 0.02; 0.04; 0.20)-D{sub 2}. The structure of the intermetallics and their hydrides were studied by in situ neutron powder diffraction at pressures up to 1000 bar and complementary X-ray diffraction. The deuteration of the hexagonal CeNi{sub 5} intermetallic resulted in CeNi{sub 5}D{sub 6.3} with a volume expansion of 30.1%. Deuterium absorption filled three different types of interstices, Ce{sub 2}Ni{sub 2} and Ni{sub 4} tetrahedra, and Ce{sub 2}Ni{sub 3} half-octahedra and was accompanied by a valence change for Ce. Significant hysteresis was observed between deuterium absorption and desorption which profoundly decreased on a second absorption cycle. For the Al

  13. An in situ tribometer for measuring friction and wear of polymers in a high pressure hydrogen environment

    Science.gov (United States)

    Duranty, Edward R.; Roosendaal, Timothy J.; Pitman, Stan G.; Tucker, Joseph C.; Owsley, Stanley L.; Suter, Jonathan D.; Alvine, Kyle J.

    2017-09-01

    High pressure hydrogen effects on the friction and wear of polymers are of importance to myriad applications. Of special concern are those used in the infrastructure for hydrogen vehicle refueling stations, including compressor sliding seals, valves, and actuators. While much is known about potentially damaging embrittlement effects of hydrogen on metals, relatively little is known about the effects of high pressure hydrogen on polymers. However, based on the limited results that are published in the literature, polymers also apparently exhibit compatibility issues with hydrogen. An additional study is needed to elucidate these effects to avoid incompatibilities either through design or material selection. As part of this effort, we present here in situ high pressure hydrogen studies of the friction and wear on example polymers. To this end, we have built and demonstrated a custom-built pin-on-flat linear reciprocating tribometer and demonstrated its use with in situ studies of friction and wear behavior of nitrile butadiene rubber polymer samples in 28 MPa hydrogen. Tribology results indicate that friction and wear is increased in high pressure hydrogen as compared both with values measured in high pressure argon and ambient air conditions.

  14. Liquid Hydrogen Propellant Tank Sub-Surface Pressurization with Gaseous Helium

    Science.gov (United States)

    Stephens, J. R.; Cartagena, W.

    2015-01-01

    A series of tests were conducted to evaluate the performance of a propellant tank pressurization system with the pressurant diffuser intentionally submerged beneath the surface of the liquid. Propellant tanks and pressurization systems are typically designed with the diffuser positioned to apply pressurant gas directly into the tank ullage space when the liquid propellant is settled. Space vehicles, and potentially propellant depots, may need to conduct tank pressurization operations in micro-gravity environments where the exact location of the liquid relative to the diffuser is not well understood. If the diffuser is positioned to supply pressurant gas directly to the tank ullage space when the propellant is settled, then it may become partially or completely submerged when the liquid becomes unsettled in a microgravity environment. In such case, the pressurization system performance will be adversely affected requiring additional pressurant mass and longer pressurization times. This series of tests compares and evaluates pressurization system performance using the conventional method of supplying pressurant gas directly to the propellant tank ullage, and then supplying pressurant gas beneath the liquid surface. The pressurization tests were conducted on the Engineering Development Unit (EDU) located at Test Stand 300 at NASA Marshall Space Flight Center (MSFC). EDU is a ground based Cryogenic Fluid Management (CFM) test article supported by Glenn Research Center (GRC) and MSFC. A 150 ft3 propellant tank was filled with liquid hydrogen (LH2). The pressurization system used regulated ambient helium (GHe) as a pressurant, a variable position valve to maintain flow rate, and two identical independent pressurant diffusers. The ullage diffuser was located in the forward end of the tank and was completely exposed to the tank ullage. The submerged diffuser was located in the aft end of the tank and was completely submerged when the tank liquid level was 10% or greater

  15. Hydro-isomerization of n-hexane on bi-functional catalyst: Effect of total and hydrogen partial pressures

    Science.gov (United States)

    Thoa, Dao Thi Kim; Loc, Luu Cam

    2017-09-01

    The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.

  16. Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal)

    2010-09-15

    The present study is related with the production of hydrogen gas (H{sub 2}), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH{sub 4}) was mixed with a proper amount of a powder reused nickel-ruthenium based catalyst (Ni-Ru based/NaBH{sub 4}: 0.2 and 0.4 g/g; {approx}150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H{sub 2}O/NaBH{sub 4}: 2-8 mol/mol) was added and the catalyzed NaBH{sub 4} hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH{sub 4} for H{sub 2} generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm{sup 3}, and having different bottom geometries (flat and conical shapes). The H{sub 2} generated was a function of the added water and completion was achieved with H{sub 2}O/NaBH{sub 4} = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H{sub 2} generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m{sup -3}, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications. (author)

  17. A continuum damage analysis of hydrogen attack in a 2.25Cr-1Mo pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Burg, M.W.D. van der; Giessen, E. van der [Technische Univ. Delft (Netherlands). Dept. of Mechanical Engineering; Tvergaard, V. [Danmarks Tekniske Hoejskole, Lyngby (Denmark). Dept. of Solid Mechanics

    1998-01-30

    A micromechanically based continuum damage model is presented to analyze the stress, temperature and hydrogen pressure dependent material degradation process termed hydrogen attack, inside a pressure vessel. Hydrogen attack (HA) is the damage process of grain boundary facets due to a chemical reaction of carbides with hydrogen, thus forming cavities with high pressure methane gas. Driven by the methane gas pressure, the cavities grow, while remote tensile stresses can significantly enhance the cavitation rate. The damage model gives the strain-rate and damage rate as a function of the temperature, hydrogen pressure and applied stresses. The model is applied to study HA in a vessel wall, where nonuniform distributions lf hydrogen pressure, temperature and stresses result in a nonuniform damage distribution over the vessel wall. Stresses inside the vessel wall first tend to accelerate and later decelerate the cavitation rate significantly. Numerical studies for different material parameters and different stress conditions demonstrate the HA process inside a vessel in time. Also, the lifetime of the pressure vessel is determined. The analyses underline that the general applicability of the Nelson curve is questionable. (orig.) 30 refs.

  18. GOZCARDS Source Data for Hydrogen Chloride Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOZCARDS Source Data for Hydrogen Chloride Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpHCl) contains zonal means and related...

  19. GOZCARDS Merged Data for Hydrogen Chloride Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOZCARDS Merged Data for Hydrogen Chloride Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpHCl) contains zonal means and related...

  20. In situ TEM studies of the shape evolution of Pd nanocrystals under oxygen and hydrogen environments at atmospheric pressure.

    Science.gov (United States)

    Zhang, Xun; Meng, Jun; Zhu, Beien; Yu, Jian; Zou, Shihui; Zhang, Ze; Gao, Yi; Wang, Yong

    2017-12-12

    We demonstrate an atomic scale TEM observation of shape evolutions of Pd nanocrystals under oxygen and hydrogen environments at atmospheric pressure. Combined with multi-scale structure reconstruction model calculations, the reshaping mechanism is fully understood.

  1. Hydrogen Cracking and Stress Corrosion of Pressure Vessel Steel ASTM A543

    Science.gov (United States)

    AlShawaf, Ali Hamad

    The purpose of conducting this research is to develop fundamental understanding of the weldability of the modern Quenched and Tempered High Strength Low Alloy (Q&T HSLA) steel, regarding the cracking behavior and susceptibility to environmental cracking in the base metal and in the heat affected zone (HAZ) when welded. A number of leaking cracks developed in the girth welds of the pressure vessel after a short time of upgrading the material from plain carbon steel to Q&T HSLA steel. The new vessels were constructed to increase the production of the plant and also to save weight for the larger pressure vessel. The results of this research study will be used to identify safe welding procedure and design more weldable material. A standardized weldability test known as implant test was constructed and used to study the susceptibility of the Q&T HSLA steel to hydrogen cracking. The charged hydrogen content for each weld was recorded against the applied load during weldability testing. The lack of understanding in detail of the interaction between hydrogen and each HAZ subzone in implant testing led to the need of developing the test to obtain more data about the weldability. The HAZ subzones were produced using two techniques: standard furnace and GleebleRTM machine. These produced subzones were pre-charged with hydrogen to different levels of concentration. The hydrogen charging on the samples simulates prior exposure of the material to high humidity environment during welding process. Fractographical and microstructural characterization of the HAZ subzones were conducted using techniques such as SEM (Scanning Electron Microscopy). A modified implant test using the mechanical tensile machine was also used to observe the effects of the hydrogen on the cracking behavior of each HAZ subzone. All the experimental weldability works were simulated and validated using a commercial computational software, SYSWELD. The computational simulation of implant testing of Q&T HSLA

  2. Fibre composite pressure vessel with polymer liner. Tightness against hydrogen; Fiberforstaerket trykbeholder med polymerliner - Taethed over for brint

    Energy Technology Data Exchange (ETDEWEB)

    Lystrup, Aage

    2005-10-01

    Pressure vessels are used as hydrogen storage on-board the car in a Danish hydrogen car project. To save energy the pressure vessels should have low weight, and carbon fibre composite pressure vessels were used. To ensure complete tightness against hydrogen, the vessels have an internal liner of aluminium. For structural reason the liner is relatively thick and the liner constitutes half of the weight of the complete pressure vessel. Further weight reduction can be obtained if the metal liner is replaced by a polymer liner, but this also means that the vessel no longer will be 100 % tight, as hydrogen will diffuse through the polymer liner. The diffusion of hydrogen can be reduced if the polymer liner is coated with a thin metal layer. Small 0.4-litre fibre composite pressure vessels with polymer liner and metal coated polymer liner were manufactured and the hydrogen tightness of the vessels were determined by measuring the weight loss during a period of 6 years of vessels pressurised by hydrogen to 10 MPa, equivalent to a hydrogen content of about 3.3 g. The loss of hydrogen during the first 3 years from vessels with pure polymer liner occurred linearly with an average loss of 0.055 g per month, or about 1.8 % per month. The loss of hydrogen from the vessels with metal coated liner occurred almost linear in the whole 6-years period. The average loss was 0.028 g per month for a vessel with a liner coated with a layer of a combination of Cu and Ag by vacuum deposition. The average loss was 0.017 g per month for a vessel with a liner coated with a plasma sprayed layer of Cu. This means that the metal coated liners are 2-3 times tighter than the pure polymer liner. The relative loss of hydrogen would be less for a larger pressure vessel with a larger ratio between volume and surface area. As an example, the relative loss for the 9-litre pressure vessel used in the Danish hydrogen car project would be 3.3 times less than the relative loss for the small 0.4 litre vessel

  3. Electric and spectroscopic properties of argon-hydrogen RF microplasma jets at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Souza-Correa, J A; Oliveira, C; Amorim, J [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol-CTBE, Caixa Postal 6170, 13083-970, Campinas, Sao Paulo (Brazil); Gomes, M P, E-mail: jorge.correa@bioetanol.org.b, E-mail: carlos.filho@bioetanol.org.b, E-mail: gomesmp@ita.b, E-mail: jayr.amorim@bioetanol.org.b [Departamento de Fisica, Instituto Tecnologico de Aeronautica-ITA, Praca Marechal Eduardo Gomes 50, 12.228-900, Sao Jose dos Campos, Sao Paulo (Brazil)

    2010-10-06

    Microplasma jets of argon-hydrogen (Ar-H{sub 2}) gas mixture were generated by 144.0 MHz radio-frequency (RF) waves at powers of 5 W, 10 W, 20 W and 50 W. The experimental setup employed creates stable microplasmas at atmospheric pressure from 5.0 mm up to 20.0 mm visual glow lengths. We have determined the rms voltages, the rms electric currents and the power absorptions of these microplasma jets. By making use of optical spectroscopy, the emission spectra of Ar-H{sub 2} microplasma jets were recorded in the range 3060-8200 A, in order to estimate the axial distribution profiles of electron density, rotational temperature, excitation temperature and hydrogen atomic temperature.

  4. LiBH4/SBA-15 Nanocomposites Prepared by Melt Infiltration under Hydrogen Pressure: Synthesis and Hydrogen Sorption Properties

    NARCIS (Netherlands)

    Ngene, P.; Adelhelm, P.A.; Beale, A.M.; de Jong, K.P.; de Jongh, P.E.

    2013-01-01

    Lithium borohydride (LiBH4) is a promising material for hydrogen storage, with a gravimetric hydrogen content of 18.5%. However, the thermodynamics and kinetics of its hydrogen release and uptake need to be improved before it can meet the requirements for mobile applications. In this study, we

  5. Surface passivation of c-Si for silicon heterojunction solar cells using high-pressure hydrogen diluted plasmas

    Directory of Open Access Journals (Sweden)

    Dimitrios Deligiannis

    2015-09-01

    Full Text Available In this work we demonstrate excellent c-Si surface passivation by depositing a-Si:H in the high-pressure and high hydrogen dilution regime. By using high hydrogen dilution of the precursor gases during deposition the hydrogen content of the layers is sufficiently increased, while the void fraction is reduced, resulting in dense material. Results show a strong dependence of the lifetime on the substrate temperature and a weaker dependence on the hydrogen dilution. After applying a post-deposition annealing step on the samples equilibration of the lifetime occurs independent of the initial nanostructure.

  6. Evidence for plasma phase transition in high pressure hydrogen from ab-initio simulations

    Energy Technology Data Exchange (ETDEWEB)

    Morales, M; Pierleoni, C; Schwegler, E; Ceperley, D

    2010-02-08

    We have performed a detailed study of molecular dissociation in liquid hydrogen using both Born-Oppenheimer molecular dynamics with Density Functional Theory and Coupled Electron-Ion Monte Carlo simulations. We observe a range of densities where (dP/d{rho}){sub T} = 0 that coincides with sharp discontinuities in the electronic conductivity, which is clear evidence of the plasma phase transition for temperatures 600K {le} T {le} 1500K. Both levels of theory exhibit the transition, although Quantum Monte Carlo predicts higher transition pressures. Based on the temperature dependence of the discontinuity in the electronic conductivity, we estimate the critical point of the transition at temperatures slightly below 2000 K. We examine the influence of proton zero point motion by using Path Integral Molecular Dynamics with Density Functional Theory; the main effect is to shift the transition to lower pressures. Furthermore, we calculate the melting curve of molecular hydrogen up to pressures of 200 GPa, finding a reentrant melting line in good agreement with previous calculations. The melting line crosses the metalization line at 700 K and 220 GPa using density functional energetics and at 550 K and 290 GPa using Quantum Monte Carlo energetics.

  7. Storage of hydrogen in advanced high pressure container. Appendices; Lagring af brint i avancerede hoejtryksbeholdere. Appendiks 1

    Energy Technology Data Exchange (ETDEWEB)

    Bentzen, J.J.; Lystrup, A. [Forskningscenter Risoe, Roskilde (Denmark)

    2005-07-15

    The objective of the project has been to study barriers for a production of advanced high pressure containers especially suitable for hydrogen, in order to create a basis for a container production in Denmark. The project has primarily focused on future Danish need for hydrogen storage in the MWh area. One task has been to examine requirement specifications for pressure tanks that can be expected in connection with these stores. Six potential storage needs have been identified: (1) Buffer in connection with start-up/regulation on the power grid. (2) Hydrogen and oxygen production. (3) Buffer store in connection with VEnzin vision. (4) Storage tanks on hydrogen filling stations. (5) Hydrogen for the transport sector from 1 TWh surplus power. (6) Tanker transport of hydrogen. Requirements for pressure containers for the above mentioned use have been examined. The connection between stored energy amount, pressure and volume compared to liquid hydrogen and oil has been stated in tables. As starting point for production technological considerations and economic calculations of various container concepts, an estimation of laminate thickness in glass-fibre reinforced containers with different diameters and design print has been made, for a 'pure' fibre composite container and a metal/fibre composite container respectively. (BA)

  8. Calibrating the Helium Pressurization System for the Space Shuttle Liquid-Hydrogen Tank

    Science.gov (United States)

    2008-01-01

    Analysis of the results from the STS-114 tanking tests and subsequent launch called into question existing thermal and mass models of helium pressurization of the liquid hydrogen tank. This hydrogen tank, which makes up the bottom two-thirds of the External Tank, is pressurized prior to launch to avoid cavitation in the Shuttle Main Engine pumps. At about 2 minutes prior to launch, the main vent valve is closed, and pressurized helium flows into the tank ullage space to achieve set point pressure. As the helium gas cools, its pressure drops, calling for additional helium. Subsequent helium flows are provided in short, timed pulses. The number of pulses is taken as a rough leak indicator. An analysis of thermal models by Marshall Space Flight Center showed considerable uncertainty in the pressure-versus-time behavior of the helium ullage space and the ability to predict the number of pulses normally expected. Kennedy Space Center proposed to calibrate the dime-sized orifice, which together with valves, controls the helium flow quantity (Figure 1). Pressure and temperature sensors were installed to provide upstream and downstream measurements necessary to compute flow rate based on the orifice discharge coefficient. An assessment of flow testing with helium indicated an extremely costly use of this critical resource. In order to reduce costs, we proposed removing the orifices from each Mobile Launcher Platform (MLP) and asking Colorado Engineering Experiment Station Inc. (CEESI) to calibrate the flow. CEESI has a high-pressure air flow system with traceable flow meters capable of handling the large flow rates. However, literature research indicated that square-edged orifices of small diameters often exhibit significant hysteresis and nonrepeatability in the vicinity of choked or sonic flow. Fortunately, the MLP orifices behaved relatively well in testing (Figure 2). Using curve fitting of the air-flow data, in conjunction with ASME orifice modeling equations, a

  9. Reactor Design for CO2 Photo-Hydrogenation toward Solar Fuels under Ambient Temperature and Pressure

    Directory of Open Access Journals (Sweden)

    Chun-Ying Chen

    2017-02-01

    Full Text Available Photo-hydrogenation of carbon dioxide (CO2 is a green and promising technology and has received much attention recently. This technique could convert solar energy under ambient temperature and pressure into desirable and sustainable solar fuels, such as methanol (CH3OH, methane (CH4, and formic acid (HCOOH. It is worthwhile to mention that this direction can not only potentially depress atmospheric CO2, but also weaken dependence on fossil fuel. Herein, 1 wt % Pt/CuAlGaO4 photocatalyst was successfully synthesized and fully characterized by ultraviolet-visible light (UV-vis spectroscopy, X-ray diffraction (XRD, Field emission scanning electron microscopy using energy dispersive spectroscopy analysis (FE-SEM/EDS, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and Brunauer-Emmett-Teller (BET, respectively. Three kinds of experimental photo-hydrogenation of CO2 in the gas phase, liquid phase, and gas-liquid phase, correspondingly, were conducted under different H2 partial pressures. The remarkable result has been observed in the gas-liquid phase. Additionally, increasing the partial pressure of H2 would enhance the yield of product. However, when an extra amount of H2 is supplied, it might compete with CO2 for occupying the active sites, resulting in a negative effect on CO2 photo-hydrogenation. For liquid and gas-liquid phases, CH3OH is the major product. Maximum total hydrocarbons 8.302 µmol·g−1 is achieved in the gas-liquid phase.

  10. Phase-equilibrium properties of coal-derived liquids. Technical progress report, January-July 1983. [70 to 700/sup 0/F; up to 2000 psia

    Energy Technology Data Exchange (ETDEWEB)

    Yesavage, V.F.; Kidnay, A.J.

    1983-07-01

    Thermodynamic property research is justly recognized as invaluable by process and design engineers in the petroleum, chemical, and allied industries. Thermodynamic data for pure fluids or complex mixtures are essential in the optimum design of both physical and chemical processing units. Coal-derived liquids are a new and vital class of industrial compounds for which there are limited thermodynamic data. Programs have been undertaken to measure volumetric properties and K values of light gas-model compound systems and to measure dew points, vapor pressures, and hydrogen solubilities in model compound and coal-derived liquid systems. The objective of the present study is to measure equilibrium K values of coal-derived liquids and model compounds representative of coal liquids, and to use the results in the development of engineering correlations. The program is divided into three major areas: design, construction, and evaluation of an equilibrium flash vaporization system for temperatures between 70 and 700/sup 0/F and pressures up to 2000 psia; measurements on samples of both coal-derived liquids and mixtures of model compounds; and preparation of engineering correlations for the measured K values and vapor liquid equilibria. Due to continued leaks of potentially harmful cresol and quinoline in the flash-vaporization cell it became necessary for us to shut down the equipment for reasons of safety. Efforts to seal the original cell over the large temperature cycles required proved ineffective. Thus, the major effort during the past six months was the design, construction, and development of a new equilibrium cell that would maintain the seal between the cell and the sight window over many temperature cycles. The final design which accomplishes this objective uses a custom-fabricated sapphire window with custom gold o-rings used for the seals. Due to the unanticipated equipment development, the data-collection effort has been delayed.

  11. Dual temperature dual pressure water-hydrogen chemical exchange for water detritiation

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Takahiko, E-mail: t-sugiyama@nucl.nagoya-u.ac.jp [Faculty of Engineering, Nagoya University, Fro-cho 1, Chikusa-ku, Nagoya 464-8603 (Japan); Takada, Akito; Morita, Youhei [Faculty of Engineering, Nagoya University, Fro-cho 1, Chikusa-ku, Nagoya 464-8603 (Japan); Kotoh, Kenji [Graduate School of Engineering, Kyushu University, Moto-oka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Munakata, Kenzo [Faculty of Engineering and Resource Science, Akita University, Tegata-gakuen-machi 1-1, Akita 010-8502 (Japan); Taguchi, Akira [Hydrogen Isotope Research Center, University of Toyama, Gofuku 3190, Toyama 930-8555 (Japan); Kawano, Takao; Tanaka, Masahiro; Akata, Naofumi [National Institute for Fusion Science, Oroshi-cho 322-6, Toki, Gifu 509-5292 (Japan)

    2015-10-15

    Experimental and analytical studies on hydrogen-tritium isotope separation by a dual temperature dual pressure catalytic exchange (DTDP-CE) with liquid phase chemical exchange columns were carried out in order to apply it to a part of the water detritiation system for DEMO fuel cycle. A prototype DTDP-CE apparatus was successfully operated and it was confirmed that tritium was separated by the apparatus as significantly distinguishable. A calculation code was developed based on the channeling stage model. The values of separation factors and the effects of some operating parameters were well predicted by the separative analyses with the code.

  12. Influence of pressure on ion energy distribution functions in EUV-induced hydrogen plasmas

    Science.gov (United States)

    van de Ven, T. H. M.; Reefman, P.; de Meijere, C. A.; Banine, V. Y.; Beckers, J.

    2016-09-01

    Next-generation lithography tools currently use Extreme Ultraviolet (EUV) radiation to create even smaller features on computer chips. The high energy photons (92 eV) induce a plasma in the low pressure background gas by photoionization. Industries have realized that these plasmas are of significant importance with respect to machine lifetime because impacting ions affect exposed surfaces. The mass resolved ion energy distribution function (IEDF) is therefore one of the main plasma parameters of interest. In this research an ion mass spectrometer is used to investigate IEDFs of ions impacting on surfaces in EUV-induced plasmas. EUV radiation is focused into a vessel with a low pressure hydrogen environment. Here, photoionization creates free electrons with energies up to 76 eV, which further ionize the background gas. The influence of the pressure on plasma composition and IEDFs has been investigated in the range 0.1-10 Pa. In general the ion fluxes towards the surface increase with pressure. However, above 5 Pa the flux of H2+ is not affected by the increase in pressure due to the balance between the creation of H2+ and the conversion of H2+ to H3+. These results will be used to benchmark plasma scaling models and verify numerical simulations.

  13. Self-pressurization of a flightweight liquid hydrogen storage tank subjected to low heat flux

    Science.gov (United States)

    Hasan, M. M.; Lin, C. S.; Vandresar, N. T.

    1991-01-01

    Results are presented for an experimental investigation of self-pressurization and thermal stratification of a 4.89 cu m liquid hydrogen (LH2) storage tank subjected to low heat flux (0.35, 2.0, and 3.5 W/sq m) under normal gravity conditions. Tests were performed at fill levels of 83 to 84 percent (by volume). The LH2 tank was representative of future spacecraft tankage, having a low mass-to-volume ratio and high performance multilayer thermal insulation. Results show that the pressure rise rate and thermal stratification increase with increasing heat flux. At the lowest heat flux, the pressure rise rate is comparable to the homogenous rate, while at the highest heat flux, the rate is more than three times the homogeneous rate. It was found that initial conditions have a significant impact on the initial pressure rise rate. The quasi-steady pressure rise rates are nearly independent of the initial condition after an initial transient period has passed.

  14. Enthalpy measurement of coal-derived liquids. Quarterly technical progress report, July-September, 1978. [148 to 459/sup 0/F; 100 to 300 psia

    Energy Technology Data Exchange (ETDEWEB)

    Kidnay, A.J.; Yesavage, V.F.

    1978-12-01

    Experimental measurements were completed on a naphtha sample (1046) furnished by the Pittsburg and Midway Coal Mining Company. A total of 38 measurements were made in the temperature region 148 to 459/sup 0/F, and at pressures of 100 and 300 psia. Additional analytical work was also completed on the SRC-I naphtha whose enthalpy measurements were reported in previous progress reports. Comparisons are given between the experimental SRC-I naphtha enthalpies and the available petroleum enthalpy correlations.

  15. Pressure-concentration-temperature characterization of St909 getter alloy with hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ghezzi, F. [Consiglio Nazionale delle Ricerche, Milan (Italy). Lab. di Fisica del Plasma; Boffito, C. [SAES Getters S.p.A., Milan (Italy)

    1996-06-01

    One of the major issues related to the next generation of fusion reactors is tritium recovery and recycling from tritiated water. Among the various approaches proposed, chemical dissociation of tritiated water over active beds based on reactive alloys appears to be a promising solution. It enables, in fact, safe recovery of tritium by exploiting the relatively high equilibrium pressures, even at low concentrations and operating temperature, of selected alloys. This paper presents the results of pressure-temperature-composition measurements carried out on a Zr-Mn-Fe alloy, named St909, candidate for such an application. Equilibrium isotherms have been determined between room temperature and 400{sup o}C for low hydrogen concentrations, and at room temperature for higher concentrations, exploring the bi-phasic region. Sieverts` law appears to be obeyed in the low concentration range, at H/A ratios of less than 0.03. (Author).

  16. Appraisal of the realistic accuracy of molecular dynamics of high-pressure hydrogen

    Directory of Open Access Journals (Sweden)

    Graeme J. Ackland

    2015-12-01

    Full Text Available Molecular dynamics (MD is a powerful method for studying the behaviour of materials at high temperature. In practice, however, its effectiveness in representing real systems is limited by the accuracy of the forces, finite size effects, quantization and equilibration methods. In this paper, we report and discuss some calculations carried out using MD on high-pressure hydrogen, reviewing a number of sources of error, of which the neglect of zero-point vibrations is quantitatively the largest. We show that simulations using ab initio MD with the PBE functional predict a large stability field for the molecular Cmca4 structure at pressures just above those achieved in current experiments above the stability range of the mixed molecular layered Phase IV. However, the various errors in the simulation all point towards a much smaller stability range, and the likelihood of a non-molecular phase based on low-coordination networks or chains of atoms.

  17. High-pressure, ambient temperature hydrogen storage in metal-organic frameworks and porous carbon

    Science.gov (United States)

    Beckner, Matthew; Dailly, Anne

    2014-03-01

    We investigated hydrogen storage in micro-porous adsorbents at ambient temperature and pressures up to 320 bar. We measured three benchmark adsorbents: two metal-organic frameworks, Cu3(1,3,5-benzenetricarboxylate)2 [Cu3(btc)2; HKUST-1] and Zn4O(1,3,5-benzenetribenzoate)2 [Zn4O(btb)2; MOF-177], and the activated carbon MSC-30. In this talk, we focus on adsorption enthalpy calculations using a single adsorption isotherm. We use the differential form of the Claussius-Clapeyron equation applied to the Dubinin-Astakhov adsorption model to calculate adsorption enthalpies. Calculation of the adsorption enthalpy in this way gives a temperature independent enthalpy of 5-7 kJ/mol at the lowest coverage for the three materials investigated. Additionally, we discuss the assumptions and corrections that must be made when calculating adsorption isotherms at high-pressure and adsorption enthalpies.

  18. Optimal design of high pressure hydrogen storage vessel using an adaptive genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ping [Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027 (China); Zheng, Jinyang; Chen, Honggang; Liu, Pengfei [Institute of Chemical Machinery and Process Equipment, Zhejiang University, Hangzhou 310027 (China)

    2010-04-15

    The weight minimum optimization of composite hydrogen storage vessel under the burst pressure constraint is considered. An adaptive genetic algorithm is proposed to perform the optimal design of composite vessels. The proposed optimization algorithm considers the adaptive probabilities of crossover and mutation which change with the fitness values of individuals and proposes a penalty function to deal with the burst pressure constraint. The winding thickness and angles of composite layers are chosen as the design variables. Effects of the population size and the number of generations on the optimal results are explored. The results using the adaptive genetic algorithm are also compared with those using the simple genetic algorithm and the Monte Carlo optimization method. (author)

  19. Design of hydroforming processes for metallic liners used in high pressure hydrogen storage

    Science.gov (United States)

    Gelin, J. C.; Labergere, C.; Thibaud, S.; Boudeau, N.

    2005-08-01

    Within the framework of an European project concerning hydrogen storage, one analyze the way to manufacture high pressure tanks (700bars) for hydrogen storage, intended to be embarked for using in motor vehicles. These tanks consist of a metallic liner, which ensure a barrier role compared to the hydrogen atoms as well as a part of the mechanical resistance, and of a composite envelope built by filament rolling up which ensures the complementary part of the mechanical resistance. The paper describes the work completed within this framework, on the basis of the simulation of the hydroforming process thanks to the complete control of the process, in volume of fluid injected. One was thus brought to develop an optimization module based on finite element calculations. This optimization module includes MPI library in order to launch several calculations in parallel on a Linux cluster. It consists in seeking the optimal evolution of the fluid volume injected vs. time to obtain a good quality component. In our case, the optimization criterion is based on the variation thickness of the tube and the possible appearance of necking. It is shown that such a way for controlling the process provide the way to get minimal thickness variation, comparatively to standard optimization approaches where the process parameters are discretized through processing time in a more standard way.

  20. Hydrogen bond-promoted metallic state in a purely organic single-component conductor under pressure.

    Science.gov (United States)

    Isono, Takayuki; Kamo, Hiromichi; Ueda, Akira; Takahashi, Kazuyuki; Nakao, Akiko; Kumai, Reiji; Nakao, Hironori; Kobayashi, Kensuke; Murakami, Youichi; Mori, Hatsumi

    2013-01-01

    Purely organic materials are generally insulating. Some charge-carrier generation, however, can provide them with electrical conductivity. In multi-component organic systems, carrier generation by intermolecular charge transfer has given many molecular metals. By contrast, in purely organic single-component systems, metallic states have rarely been realized although some neutral-radical semiconductors have been reported. Here we uncover a new type of purely organic single-component molecular conductor by utilizing strong hydrogen-bonding interactions between tetrathiafulvalene-based electron-donor molecules. These conductors are composed of highly symmetric molecular units constructed by the strong intra-unit hydrogen bond. Moreover, we demonstrate that, in this system, charge carriers are produced by the partial oxidation of the donor molecules and delocalized through the formation of the symmetric intra-unit hydrogen bonds. As a result, our conductors show the highest room-temperature electrical conductivity and the metallic state under the lowest physical pressure among the purely organic single-component systems, to our knowledge.

  1. Zeolite-templated carbon materials for high-pressure hydrogen storage.

    Science.gov (United States)

    Stadie, Nicholas P; Vajo, John J; Cumberland, Robert W; Wilson, Andrew A; Ahn, Channing C; Fultz, Brent

    2012-07-03

    Zeolite-templated carbon (ZTC) materials were synthesized, characterized, and evaluated as potential hydrogen storage materials between 77 and 298 K up to 30 MPa. Successful synthesis of high template fidelity ZTCs was confirmed by X-ray diffraction and nitrogen adsorption at 77 K; BET surface areas up to ~3600 m(2) g(-1) were achieved. Equilibrium hydrogen adsorption capacity in ZTCs is higher than all other materials studied, including superactivated carbon MSC-30. The ZTCs showed a maximum in Gibbs surface excess uptake of 28.6 mmol g(-1) (5.5 wt %) at 77 K, with hydrogen uptake capacity at 300 K linearly proportional to BET surface area: 2.3 mmol g(-1) (0.46 wt %) uptake per 1000 m(2) g(-1) at 30 MPa. This is the same trend as for other carbonaceous materials, implying that the nature of high-pressure adsorption in ZTCs is not unique despite their narrow microporosity and significantly lower skeletal densities. Isoexcess enthalpies of adsorption are calculated between 77 and 298 K and found to be 6.5-6.6 kJ mol(-1) in the Henry's law limit.

  2. Probing the Hydrogen Sublattice of FeHx with High-Pressure Neutron Diffraction

    Science.gov (United States)

    Murphy, C. A.; Guthrie, M.; Boehler, R.; Somayazulu, M.; Fei, Y.; Molaison, J.; dos Santos, A. M.

    2013-12-01

    The combination of seismic, cosmochemical, and mineral physics observations have revealed that Earth's iron-rich core must contain some light elements, such as hydrogen, carbon, oxygen, silicon, and/or sulfur. Therefore, understanding the influence of these light elements on the structural, thermoelastic, and electronic properties of iron is important for constraining the composition of this remote layer of the Earth and, in turn, providing constraints on planetary differentiation and core formation models. The high-pressure structural and magnetic properties of iron hydride (FeHx) have previously been studied using synchrotron x-ray diffraction and Mössbauer spectroscopy. Such experiments revealed that the double hexagonal close-packed (dhcp) structure of FeHx is stable above a pressure of ~5 GPa and up to at least 80 GPa at 300 K [1]. In addition, dhcp-FeHx is ferromagnetic at low-pressures, but undergoes a magnetic collapse around 22 GPa [2]. X-ray experiments provide valuable insight into the properties of FeHx, but such techniques are largely sensitive to the iron component because it is difficult to detect the hydrogen sublattice with x-rays. Therefore, neutron diffraction has been used to investigate metastable FeHx, which is formed by quenching the high-pressure phase to liquid nitrogen temperatures and probing the sample at ambient pressure [3]. However, such neutron experiments have been limited to formation pressures below 10 GPa, and cannot be performed at ambient temperature. Here we present the first in-situ investigation of FeHx at 300 K using high-pressure neutron diffraction experiments performed at the Spallation Neutrons and Pressure Diffractometer (SNAP) instrument at the Spallation Neutron Source, Oak Ridge National Laboratory. In order to achieve pressures of ~50 GPa, we loaded iron samples with a hydrogen gas pressure medium into newly designed large-volume panoramic diamond-anvil cells (DACs) for neutron diffraction experiments [4; 5]. We

  3. Hydroformylation of Cyclohexene with Carbon Dioxide and Hydrogen Using Ruthenium Carbonyl Catalyst: Influence of Pressures of Gaseous Components

    Directory of Open Access Journals (Sweden)

    Masahiko Arai

    2007-08-01

    Full Text Available Hydroformylation of cyclohexene was studied with a catalyst system ofRu3(CO12 and LiCl using H2 and CO2 instead of CO in NMP. The influence of H2 andCO2 pressures on the total conversion and the product distribution was examined. It wasshown that increasing total pressure of H2 and CO2 promoted the reverse water gas shiftreaction and increased the yield of cyclohexanecarboxaldehyde. Its hydrogenation tocyclohexanemethanol was promoted with increasing H2 pressure but suppressed withincreasing CO2 pressure. Cyclohexane was also formed along with those products and thisdirect hydrogenation was suppressed with increasing CO2 pressure. The roles of CO2 as apromoter as well as a reactant were further examined by phase behavior observations andhigh pressure FTIR measurements.

  4. Pressure induced optical absorption and refractive index changes of a shallow hydrogenic impurity in a quantum wire

    Science.gov (United States)

    Arunachalam, N.; John Peter, A.; Woo Lee, Chang

    2011-10-01

    Pressure induced binding energy of a hydrogenic impurity in an InAs/GaAs quantum wire is investigated. Calculations are performed using Bessel functions as an orthonormal basis within a single band effective mass approximation using variational method. Photoionization cross-section of the hydrogenic impurity in the influence of pressure is studied. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of pressure are analyzed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and pressure. The occurred blue shift of the resonant peak due to the pressure gives the information about the variation of two energy levels in the quantum well wire. The optical absorption coefficients and the refractive index changes are strongly dependent on the incident optical intensity and the pressure.

  5. FINAL REPORT - Development of High Pressure Hydrogen Storage Tank for Storage and Gaseous Truck Delivery

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, Donald [Hexagon Lincoln LLC, Lincoln, NE (United States)

    2017-08-04

    The “Development of High Pressure Hydrogen Storage Tanks for Storage and Gaseous Truck Delivery” project [DE-FG36-08GO18062] was initiated on 01 July 2008. Hexagon Lincoln (then Lincoln Composites) received grant funding from the U.S. Department of Energy to support the design and development of an improved bulk hauling and storage solution for hydrogen in terms of cost, safety, weight and volumetric efficiency. The development of this capability required parallel development and qualification of large all-composites pressure vessels, a custom ISO container to transport and store said tanks, and performance of trade studies to identify optimal operating pressure for the system. Qualification of the 250 bar TITAN® module was completed in 2009 with supervision from the American Bureau of Shipping [ABS], and the equipment has been used internationally for bulk transportation of fuel gases since 2010. Phase 1 of the project was successfully completed in 2012 with the issuance of USDOT SP 14951, the special permit authorizing the manufacture, marking, sale and use of TITAN® Mobile Pipeline® equipment in the United States. The introduction of tube trailers with light weight composite tankage has meant that 2 to 3 times as much gaseous fuel can be transported with each trip. This increased hauling efficiency offers dramatically reduced operating costs and has enabled a profitable business model for over-the-road compressed natural gas delivery. The economic drivers of this business opportunity vary from country to country and region to region, but in many places gas distribution companies have realized profitable operations. Additional testing was performed in 2015 to characterize hydrogen-specific operating protocols for use of TITAN® systems in CHG service at 250 bar. This program demonstrated that existing compression and decompression methodologies can efficiently and safely fill and unload lightweight bulk hauling systems. Hexagon Lincoln and U.S. DOE agreed

  6. Gallium Arsenate Dihydrate under Pressure: Elastic Properties, Compression Mechanism, and Hydrogen Bonding.

    Science.gov (United States)

    Spencer, Elinor C; Soghomonian, Victoria; Ross, Nancy L

    2015-08-03

    Gallium arsenate dihydrate is a member of a class of isostructural compounds, with the general formula M(3+)AsO4·2H2O (M(3+) = Fe, Al, In, or Ga), which are being considered as potential solid-state storage media for the sequestration of toxic arsenic cations. We report the first high-pressure structural analysis of a metal arsenate dihydrate, namely, GaAsO4·2H2O. This compound crystallizes in the orthorhombic space group Pbca with Z = 8. Accurate unit cell parameters as a function of pressure were obtained by high-pressure single-crystal X-ray diffraction, and a bulk modulus of 51.1(3) GPa for GaAsO4·2H2O was determined from a third-order Birch-Murnaghan equation of state fit to the P-V data. Assessment of the pressure dependencies of the unit cell lengths showed that the compressibility of the structure along the axial directions increases in the order of [010] < [100] < [001]. This order was found to correlate well with the proposed compression mechanism for GaAsO4·2H2O, which involves deformation of the internal channel void spaces of the polyhedral helices that lie parallel to the [010] direction, and increased distortion of the GaO6 octahedra. The findings of the high-pressure diffraction experiment were further supported by the results from variable-pressure Raman analysis of GaAsO4·2H2O. Moreover, we propose a revised and more complex model for the hydrogen-bonding scheme in GaAsO4·2H2O, and on the basis of this revision, we reassigned the peaks in the OH stretching regions of previously published Raman spectra of this compound.

  7. Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Pier, M.

    1943-02-19

    A transcript is presented of a speech on the history of the development of hydrogenation of coal and tar. Apparently the talk had been accompanied by the showing of photographic slides, but none of the pictures were included with the report. In giving the history, Dr. Pier mentioned the dependence of much of the development of hydrogenation upon previous development in the related areas of ammonia and methanol syntheses, but he also pointed out several ways in which equipment appropriate for hydrogenation differed considerably from that used for ammonia and methanol. Dr. Pier discussed the difficulties encountered with residue processing, design of the reaction ovens, manufacture of ovens and preheaters, heating of reaction mixtures, development of steels, and development of compressor pumps. He described in some detail his own involvement in the development of the process. In addition, he discussed the development of methods of testing gasolines and other fuels. Also he listed some important byproducts of hydrogenation, such as phenols and polycyclic aromatics, and he discussed the formation of iso-octane fuel from the butanes arising from hydrogenation. In connection with several kinds of equipment used in hydrogenation (whose pictures were being shown), Dr. Pier gave some of the design and operating data.

  8. Low pressure adsorption of hydrogen on carbon nanostructures; Adsorption d'hydrogene a basse pression sur des nanostructures de carbone

    Energy Technology Data Exchange (ETDEWEB)

    Melancon, E.; Benard, P. [Universite du Quebec a Trois-Rivieres, Institut de recherche sur l' hydrogene, Trois-Rivieres, Quebec (Canada)

    2000-05-01

    Although hydrogen is one of the most efficient fuel per unit of mass, its low density per unit volume requires high pressure gaseous storage or cyrogenic storage in liquid form for practical applications. A promising technique to reduce the pressure requirements for gaseous storage is to use the adsorption properties of carbon materials. However, physisorption of hydrogen on activated carbon requires operating temperatures of the order of 77K and a proper densification of the carbon to exhibit appreciable gains over compression. Large absorbed densities of hydrogen have been reported on carbon nanostructures such as nanotubes and nanofibers, at or near room temperature. Adsorption storage of hydrogen using such carbon materials may therefore be possible at much higher temperatures than activated carbon. The precise mechanisms that could explain the large adsorbed densities is still not understood. Although physiosorption does not appear to be sufficient to explain by itself the large reported values of the adsorption density of nanotubes and nanofibers, it is interesting to study its contribution to the absorbed density and to compare it to other carbon structures such as activated carbon, particularly in view of the controversy surrounding the actual values of the absorbed density in carbon nanostructures. In this work, we will study the adsorption isotherms of hydrogen on caped and uncaped carbon nanotubes and nanotube ropes in the limit of Henry's Law by calculating the second virial coefficient for gas solid interaction and compare them to layered carbon structures.

  9. The sticking probability for H-2 on some transition metals at a hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2008-01-01

    The sticking probability for hydrogen on films of Co, Ni, Cu, Ru, Rh, Pd, Ir, and Pt supported on graphite has been measured at a hydrogen pressure of 1 bar in the temperature range 40–200 °C. The sticking probability is found to increase in the order Ni, Co, Ir, Pd, Pt, Rh, and Ru at temperatures...... below 150 °C, whereas at higher temperatures, the sticking probability for Pd is higher than for Pt. The sticking probability for Cu is below the detection limit of the measurement. The measured sticking probabilities are slightly lower than those obtained at high hydrogen coverage under ultrahigh...... vacuum conditions. This could be a consequence of the higher hydrogen pressure used here. The apparent desorption energies extracted from the steady-state desorption rate are found to agree reasonably well with published values for the heat of adsorption at high coverage. However, the sticking...

  10. Simulation of Liquid Level, Temperature and Pressure Inside a 2000 Liter Liquid Hydrogen Tank During Truck Transportation

    Science.gov (United States)

    Takeda, Minoru; Nara, Hiroyuki; Maekawa, Kazuma; Fujikawa, Shizuichi; Matsuno, Yu; Kuroda, Tsuneo; Kumakura, Hiroaki

    Hydrogen is an ultimate energy source because only water is produced after the chemical reaction of hydrogen and oxygen. In the near future, a large amount of hydrogen, produced using sustainable/renewable energy, is expected to be consumed. Since liquid hydrogen (LH2) has the advantage of high storage efficiency, it is expected to be the ultimate medium for the worldwide storage and transportation of large amounts of hydrogen. To make a simulation model of the sloshing of LH2 inside a 2000 liter tank, simulation analyses of LH2 surface oscillation, temperature and pressure inside the tank during a truck transportation have been carried out using a multipurpose software ANSYS CFX. Numerical results are discussed in comparison with experimental results.

  11. Syntheses and properties of several metastable and stable hydrides derived from intermetallic compounds under high hydrogen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Filipek, S.M., E-mail: sfilipek@unipress.waw.pl [Institute of High Pressure Physics PAS, ul. Sokolowska 29, 01-142 Warsaw (Poland); Paul-Boncour, V. [ICMPE-CMTR, CNRS-UPEC, 2-8 rue Henri Dunant, 94320 Thiais (France); Liu, R.S. [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Jacob, I. [Unit Nuclear Eng., Ben Gurion University of the Negev, Beer-Sheva (Israel); Tsutaoka, T. [Dept. of Sci. Educ., Grad. School of Educ., Hiroshima University, Hiroshima (Japan); Budziak, A. [Institute of Nuclear Physics PAS, 31-342 Kraków (Poland); Morawski, A. [Institute of High Pressure Physics PAS, ul. Sokolowska 29, 01-142 Warsaw (Poland); Sugiura, H. [Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027 (Japan); Zachariasz, P. [Institute of Electron Technology Cracow Division, ul. Zablocie 39, 30-701 Krakow (Poland); Dybko, K. [Institute of Physics, PAS, 02-668 Warsaw (Poland); Diduszko, R. [Tele and Radio Research Institute, ul. Ratuszowa 11, Warsaw (Poland)

    2016-12-01

    Brief summary of our former work on high hydrogen pressure syntheses of novel hydrides and studies of their properties is supplemented with new results. Syntheses and properties of a number of hydrides (unstable, metastable or stable in ambient conditions) derived under high hydrogen pressure from intermetallic compounds, like MeT{sub 2}, MeNi{sub 5}, Me{sub 7}T{sub 3}, Y{sub 6}Mn{sub 23} and YMn{sub 12} (where Me = zirconium, yttrium or rare earth; T = transition metal) are presented. Stabilization of ZrFe{sub 2}H{sub 4} due to surface phenomena was revealed. Unusual role of manganese in hydride forming processes is pointed out. Hydrogen induced phase transitions, suppression of magnetism, antiferromagnetic-ferromagnetic and metal-insulator or semimetal-metal transitions are described. Equations of state (EOS) of hydrides submitted to hydrostatic pressures up to 30 GPa are presented and discussed.

  12. Equilibrium based analytical model for estimation of pressure magnification during deflagration of hydrogen air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Karanam, Aditya; Sharma, Pavan K.; Ganju, Sunil; Singh, Ram Kumar [Bhabha Atomic Research Centre (BARC), Mumbai (India). Reactor Safety Div.

    2016-12-15

    During postulated accident sequences in nuclear reactors, hydrogen may get released from the core and form a flammable mixture in the surrounding containment structure. Ignition of such mixtures and the subsequent pressure rise are an imminent threat for safe and sustainable operation of nuclear reactors. Methods for evaluating post ignition characteristics are important for determining the design safety margins in such scenarios. This study presents two thermo-chemical models for determining the post ignition state. The first model is based on internal energy balance while the second model uses the concept of element potentials to minimize the free energy of the system with internal energy imposed as a constraint. Predictions from both the models have been compared against published data over a wide range of mixture compositions. Important differences in the regions close to flammability limits and for stoichiometric mixtures have been identified and explained. The equilibrium model has been validated for varied temperatures and pressures representative of initial conditions that may be present in the containment during accidents. Special emphasis has been given to the understanding of the role of dissociation and its effect on equilibrium pressure, temperature and species concentrations.

  13. Hydrogen and carbon vapour pressure isotope effects in liquid fluoroform studied by density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Oi, Takao; Mitome, Ryota; Yanase, Satoshi [Sophia Univ., Tokyo (Japan). Faculty of Science and Technology

    2017-06-01

    H/D and {sup 12}C/{sup 13}C vapour pressure isotope effects (VPIEs) in liquid fluoroform (CHF{sub 3}) were studied at the MPW1PW91/6-31 ++ G(d) level of theory. The CHF{sub 3} monomer and CHF{sub 3} molecules surrounded by other CHF{sub 3} molecules in every direction in CHF{sub 3} clusters were used as model molecules of vapour and liquid CHF{sub 3}. Although experimental results in which the vapour pressure of liquid {sup 12}CHF{sub 3} is higher than that of liquid {sup 12}CDF{sub 3} and the vapour pressure of liquid {sup 13}CHF{sub 3} is higher than that of liquid {sup 12}CHF{sub 3} between 125 and 212 K were qualitatively reproduced, the present calculations overestimated the H/D VPIE and underestimated the {sup 12}C/{sup 13}C VPIE. Temperature-dependent intermolecular interactions between hydrogen and fluorine atoms of neighbouring molecules were required to explain the temperature dependences of both H/D and {sup 12}C/{sup 13}C VPIEs.

  14. Hydrogen.

    Science.gov (United States)

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  15. Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture

    Science.gov (United States)

    Agaie, Baba G.; Khan, Ilyas; Alshomrani, Ali Saleh; Alqahtani, Aisha M.

    2017-05-01

    In this paper the transient flow of hydrogen compressed-natural gas (HCNG) mixture which is also referred to as hydrogen-natural gas mixture in a pipeline is numerically computed using the reduced-order modelling technique. The study on transient conditions is important because the pipeline flows are normally in the unsteady state due to the sudden opening and closure of control valves, but most of the existing studies only analyse the flow in the steady-state conditions. The mathematical model consists in a set of non-linear conservation forms of partial differential equations. The objective of this paper is to improve the accuracy in the prediction of the HCNG transient flow parameters using the Reduced-Order Modelling (ROM). The ROM technique has been successfully used in single-gas and aerodynamic flow problems, the gas mixture has not been done using the ROM. The study is based on the velocity change created by the operation of the valves upstream and downstream the pipeline. Results on the flow characteristics, namely the pressure, density, celerity and mass flux are based on variations of the mixing ratio and valve reaction and actuation time; the ROM computational time cost advantage are also presented.

  16. Methane conversion using a dielectric barrier discharge reactor at atmospheric pressure for hydrogen production

    Science.gov (United States)

    Khadir, N.; Khodja, K.; Belasri, A.

    2017-09-01

    In the present paper, we carried out a theoretical study of dielectric barrier discharge (DBD) filled with pure methane gas. The homogeneous discharge model used in this work includes a plasma chemistry unit, an electrical circuit, and the Boltzmann equation. The model was applied to the case of a sinusoidal voltage at a period frequency of 50 kHz and under a gas pressure of 600 Torr. We investigated the temporal variation of electrical and kinetic discharge parameters such as plasma and dielectric voltages, the discharge current density, electric field, deposited power density, and the species concentration. We also checked the physical model validity by comparing its results with experimental work. According to the results discussed herein, the dielectric capacitance is the parameter that has the greatest effect on the methane conversion and H2/CH4 ratio. This work enriches the knowledge for the improvement of DBD for CH4 conversion and hydrogen production.

  17. Molecular hydrogen ameliorates several characteristics of preeclampsia in the Reduced Uterine Perfusion Pressure (RUPP) rat model.

    Science.gov (United States)

    Ushida, Takafumi; Kotani, Tomomi; Tsuda, Hiroyuki; Imai, Kenji; Nakano, Tomoko; Hirako, Shima; Ito, Yumiko; Li, Hua; Mano, Yukio; Wang, Jingwen; Miki, Rika; Yamamoto, Eiko; Iwase, Akira; Bando, Yasuko K; Hirayama, Masaaki; Ohno, Kinji; Toyokuni, Shinya; Kikkawa, Fumitaka

    2016-12-01

    Oxidative stress plays an important role in the pathogenesis of preeclampsia. Recently, molecular hydrogen (H 2 ) has been shown to have therapeutic potential in various oxidative stress-related diseases. The aim of this study is to investigate the effect of H 2 on preeclampsia. We used the reduced utero-placental perfusion pressure (RUPP) rat model, which has been widely used as a model of preeclampsia. H 2 water (HW) was administered orally ad libitum in RUPP rats from gestational day (GD) 12-19, starting 2 days before RUPP procedure. On GD19, mean arterial pressure (MAP) was measured, and samples were collected. Maternal administration of HW significantly decreased MAP, and increased fetal and placental weight in RUPP rats. The increased levels of soluble fms-like tyrosine kinase-1 (sFlt-1) and diacron reactive oxygen metabolites as a biomarker of reactive oxygen species in maternal blood were decreased by HW administration. However, vascular endothelial growth factor level in maternal blood was increased by HW administration. Proteinuria, and histological findings in kidney were improved by HW administration. In addition, the effects of H 2 on placental villi were examined by using a trophoblast cell line (BeWo) and villous explants from the placental tissue of women with or without preeclampsia. H 2 significantly attenuated hydrogen peroxide-induced sFlt-1 expression, but could not reduce the expression induced by hypoxia in BeWo cells. H 2 significantly attenuated sFlt-1 expression in villous explants from women with preeclampsia, but not affected them from normotensive pregnancy. The prophylactic administration of H 2 attenuated placental ischemia-induced hypertension, angiogenic imbalance, and oxidative stress. These results support the theory that H 2 has a potential benefit in the prevention of preeclampsia. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. SOLAR RADIATION PRESSURE AND LOCAL INTERSTELLAR MEDIUM FLOW PARAMETERS FROM INTERSTELLAR BOUNDARY EXPLORER LOW ENERGY HYDROGEN MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Schwadron, N. A.; Moebius, E.; Kucharek, H.; Lee, M. A.; French, J. [University of New Hampshire, Durham, NH 03824 (United States); Saul, L.; Wurz, P. [University of Bern, 3012 Bern (Switzerland); Bzowski, M. [Space Research Centre of the Polish Academy of Sciences, Warsaw (Poland); Fuselier, S. A.; Livadiotis, G.; McComas, D. J. [Southwest Research Institute, San Antonio, TX 78228 (United States); Frisch, P. [University of Chicago, Chicago, IL 60637 (United States); Gruntman, M. [University of Southern California, Los Angeles, CA 90089 (United States); Mueller, H. R. [Dartmouth College, Hanover, NH 03755 (United States)

    2013-10-01

    Neutral hydrogen atoms that travel into the heliosphere from the local interstellar medium (LISM) experience strong effects due to charge exchange and radiation pressure from resonant absorption and re-emission of Lyα. The radiation pressure roughly compensates for the solar gravity. As a result, interstellar hydrogen atoms move along trajectories that are quite different than those of heavier interstellar species such as helium and oxygen, which experience relatively weak radiation pressure. Charge exchange leads to the loss of primary neutrals from the LISM and the addition of new secondary neutrals from the heliosheath. IBEX observations show clear effects of radiation pressure in a large longitudinal shift in the peak of interstellar hydrogen compared with that of interstellar helium. Here, we compare results from the Lee et al. interstellar neutral model with IBEX-Lo hydrogen observations to describe the distribution of hydrogen near 1 AU and provide new estimates of the solar radiation pressure. We find over the period analyzed from 2009 to 2011 that radiation pressure divided by the gravitational force (μ) has increased slightly from μ = 0.94 ± 0.04 in 2009 to μ = 1.01 ± 0.05 in 2011. We have also derived the speed, temperature, source longitude, and latitude of the neutral H atoms and find that these parameters are roughly consistent with those of interstellar He, particularly when considering the filtration effects that act on H in the outer heliosheath. Thus, our analysis shows that over the period from 2009 to 2011, we observe signatures of neutral H consistent with the primary distribution of atoms from the LISM and a radiation pressure that increases in the early rise of solar activity.

  19. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  20. Self-pressurization of a spherical liquid hydrogen storage tank in a microgravity environment

    Science.gov (United States)

    Lin, C. S.; Hasan, M. M.

    1992-01-01

    Thermal stratification and self-pressurization of partially filled liquid hydrogen (LH2) storage tanks under microgravity condition is studied theoretically. A spherical tank is subjected to a uniform and constant wall heat flux. It is assumed that a vapor bubble is located in the tank center such that the liquid-vapor interface and tank wall form two concentric spheres. This vapor bubble represents an idealized configuration of a wetting fluid in microgravity conditions. Dimensionless mass and energy conservation equations for both vapor and liquid regions are numerically solved. Coordinate transformation is used to capture the interface location which changes due to liquid thermal expansion, vapor compression, and mass transfer at liquid-vapor interface. The effects of tank size, liquid fill level, and wall heat flux on the pressure rise and thermal stratification are studied. Liquid thermal expansion tends to cause vapor condensation and wall heat flux tends to cause liquid evaporation at the interface. The combined effects determine the direction of mass transfer at the interface. Liquid superheat increases with increasing wall heat flux and liquid fill level and approaches an asymptotic value.

  1. Effect of pressure on high Karlovitz number lean turbulent premixed hydrogen-enriched methane-air flames using LES

    Science.gov (United States)

    Cicoria, David; Chan, C. K.

    2017-07-01

    Large eddy simulation (LES) is employed to investigate the effect of pressure on lean CH4-H2-air turbulent premixed flames at high Karlovitz number for mixtures up to 60% of hydrogen in volume. The subfilter combustion term representing the interaction between turbulence and chemistry is modelled using the PaSR model, along with complex chemistry using a skeletal mechanism based on GRI-MECH3.0. The influence of pressure at high turbulence levels is studied by means of the local flame structure, and the assessment of species formation inside the flame. Results show that the ratio of turbulent flame thickness to laminar flame thickness δt/δu increases faster with pressure, and increases with the fraction of hydrogen in the mixture, leading to higher ratio of turbulent to laminar flame speed. The flame displays smaller structures and higher degree of wrinkling at higher pressure. Final species of CO2 and H2O formation is almost independent of pressure. For intermediate species CO and OH, an increase in pressure at constant volume fraction of hydrogen β leads to a decrease of emission of these species.

  2. Technology update: Nickel-hydrogen Common Pressure Vessel (CPV) 2.5V twin stack cell designs

    Science.gov (United States)

    Harvey, Tim; Miller, Lee

    1992-01-01

    Information is given in viewgraph form on the nickel hydrogen common pressure vessel (CPV) 2.5V twin stack cell designs. Information given includes an energy analysis, a CPV design comparison, a summary of CPV characterization testing, a comparison of discharge voltage among designs, and life test performance summaries.

  3. Measurement of absolute yields of lyman transitions in pionic hydrogen and deuterium as a function of pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rusi El Hassani, A.J. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Beer, W. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Gilot, J.F. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Goudsmit, P.F.A. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Leisi, H.J. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Thomann, S. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Volken, W. [Eidgenoessische Technische Hochschule, Villigen (Switzerland). Inst. fuer Teilchenphysik; Aschenauer, E.C. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Gabathuler, K. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Simons, L.M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Bovet, E. [Neuchatel Univ. (Switzerland). Inst. de Physique; Egger, J.P. [Neuchatel Univ. (Switzerland). Inst. de Physique; Fiorucci, G. [Neuchatel Univ. (Switzerland). Inst. de Physique; Markushin, V.E. [Kurchatov Inst. (RKI), Moscow (Russian Federation)

    1995-02-01

    Absolute yields of K X-ray transitions in pionic hydrogen and deuterium were determined with accuracies of typically {+-}10% at target pressures of 2.8, 15 and 40 bar and compared with the results of a recently developed cascade code. (orig.)

  4. Combined effects of high pressure and sodium hydrogen carbonate treatment on pork ham: improvement of texture and palatability

    Science.gov (United States)

    Kim, Yun-Jung; Nishiumi, Tadayuki; Fujimura, Shinobu; Ogoshi, Hiro; Suzuki, Atsushi

    2013-06-01

    In this study, the combined effects of high pressure and sodium hydrogen carbonate (NaHCO3) treatment on the physical and chemical properties, and palatability of pork ham, a tough and under-utilized meat, were investigated. Assessment of meat properties with heat treatment, after exposure to NaHCO3 and high pressure treatment, revealed an increase in water content, and decreased weight reduction and rupture stress. The free amino acid content of meat samples increased with NaHCO3 and high pressure treatment. The effect of high pressure processing was especially notable at a pressure of 300 MPa. Sensory evaluation showed that meat subjected to high pressure processing after NaHCO3 treatment was tender and juicy. In addition, the sample produced minimal residue in the mouth and was characterized by a good taste.

  5. The thermodynamic properties of the high-pressure superconducting state in the hydrogen-rich compounds

    Science.gov (United States)

    Szcz&şacute; niak, Radosław; Durajski, Artur P.

    2013-11-01

    The ab initio calculations suggest that the superconducting state in CaH6 under the pressure (p) at 150 GPa has the highest critical temperature among the examined hydrogen-rich compounds. For this reason, the relevant thermodynamic parameters of the superconducting state in CaH6 have been determined; a wide range of the Coulomb pseudopotential has been assumed: μ⋆∈. It has been found that: (i) The critical temperature (TC) changes in the range from 243 K to 180 K (ii) The values of the ratio of the energy gap to the critical temperature (RΔ ≡ 2Δ(0)/kBTC) can be found in the range from 5.42 to 5.02. (iii) The ratio of the specific heat jump (ΔC(TC)) to the value of the specific heat in the normal state (CN(TC)), which has been represented by the symbol RC, takes the values from 3.30 to 3.18. (iv) The ratio R≡TC(T)/HC2(0), where HC(0) denotes the critical thermodynamic field, changes from 0.122 to 0.125. The above results mean that even for the strong electron depairing correlations the superconducting state in CaH6 is characterized by a very high value of TC, and the remaining thermodynamic parameters significantly deviate from the predictions of the BCS theory. The study has brought out the expressions that correctly predict the values of the thermodynamic parameters for the superconducting state in CaH6 and for the compounds: SiH4(H2)2, Si2H6, B2H6, SiH4, GeH4, and PtH. Next, in the whole family of the hydrogen-rich compounds, the possible ranges of the values have been determined for TC, RΔ, RC, and RH. It has been found that the maximum value of the critical temperature can be equal to 764 K, which very well correlates with TC for metallic hydrogen (p = 2 TPa). Other parameters (RΔ, RC, and RH) should not deviate from the predictions of the BCS theory more than the analogous parameters for CaH6.

  6. Flexible Electronics: High Pressure Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Films and Solar Cells (Adv. Mater. 28/2016).

    Science.gov (United States)

    He, Rongrui; Day, Todd D; Sparks, Justin R; Sullivan, Nichole F; Badding, John V

    2016-07-01

    On page 5939, J. V. Badding and co-workers describe the unrolling of a flexible hydrogenated amorphous silicon solar cell, deposited by high-pressure chemical vapor deposition. The high-pressure deposition process is represented by the molecules of silane infiltrating the small voids between the rolled up substrate, facilitating plasma-free deposition over a very large area. The high-pressure approach is expected to also find application for 3D nanoarchitectures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Manufacturing Cost Analysis of Novel Steel/Concrete Composite Vessel for Stationary Storage of High-Pressure Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Zhang, Wei [ORNL; Wang, Jy-An John [ORNL; Ren, Fei [ORNL

    2012-09-01

    A novel, low-cost, high-pressure, steel/concrete composite vessel (SCCV) technology for stationary storage of compressed gaseous hydrogen (CGH2) is currently under development at Oak Ridge National Laboratory (ORNL) sponsored by DOE s Fuel Cell Technologies (FCT) Program. The SCCV technology uses commodity materials including structural steels and concretes for achieving cost, durability and safety requirements. In particular, the hydrogen embrittlement of high-strength low-alloy steels, a major safety and durability issue for current industry-standard pressure vessel technology, is mitigated through the use of a unique layered steel shell structure. This report presents the cost analysis results of the novel SCCV technology. A high-fidelity cost analysis tool is developed, based on a detailed, bottom-up approach which takes into account the material and labor costs involved in each of the vessel manufacturing steps. A thorough cost study is performed to understand the SCCV cost as a function of the key vessel design parameters, including hydrogen pressure, vessel dimensions, and load-carrying ratio. The major conclusions include: The SCCV technology can meet the technical/cost targets set forth by DOE s FCT Program for FY2015 and FY2020 for all three pressure levels (i.e., 160, 430 and 860 bar) relevant to the hydrogen production and delivery infrastructure. Further vessel cost reduction can benefit from the development of advanced vessel fabrication technologies such as the highly automated friction stir welding (FSW). The ORNL-patented multi-layer, multi-pass FSW can not only reduce the amount of labor needed for assembling and welding the layered steel vessel, but also make it possible to use even higher strength steels for further cost reductions and improvement of vessel structural integrity. It is noted the cost analysis results demonstrate the significant cost advantage attainable by the SCCV technology for different pressure levels when compared to the

  8. Simulation of Oxygen Disintegration and Mixing With Hydrogen or Helium at Supercritical Pressure

    Science.gov (United States)

    Bellan, Josette; Taskinoglu, Ezgi

    2012-01-01

    The simulation of high-pressure turbulent flows, where the pressure, p, is larger than the critical value, p(sub c), for the species under consideration, is relevant to a wide array of propulsion systems, e.g. gas turbine, diesel, and liquid rocket engines. Most turbulence models, however, have been developed for atmospheric-p turbulent flows. The difference between atmospheric-p and supercritical-p turbulence is that, in the former situation, the coupling between dynamics and thermodynamics is moderate to negligible, but for the latter it is very significant, and can dominate the flow characteristics. The reason for this stems from the mathematical form of the equation of state (EOS), which is the perfect-gas EOS in the former case, and the real-gas EOS in the latter case. For flows at supercritical pressure, p, the large eddy simulation (LES) equations consist of the differential conservation equations coupled with a real-gas EOS. The equations use transport properties that depend on the thermodynamic variables. Compared to previous LES models, the differential equations contain not only the subgrid scale (SGS) fluxes, but also new SGS terms, each denoted as a correction. These additional terms, typically assumed null for atmospheric pressure flows, stem from filtering the differential governing equations, and represent differences between a filtered term and the same term computed as a function of the filtered flow field. In particular, the energy equation contains a heat-flux correction (q-correction) that is the difference between the filtered divergence of the heat flux and the divergence of the heat flux computed as a function of the filtered flow field. In a previous study, there was only partial success in modeling the q-correction term, but in this innovation, success has been achieved by using a different modeling approach. This analysis, based on a temporal mixing layer Direct Numerical Simulation database, shows that the focus in modeling the q

  9. Hydrogen bond symmetrization and superconducting phase of HBr and HCl under high pressure: An ab initio study.

    Science.gov (United States)

    Duan, Defang; Tian, Fubo; He, Zhi; Meng, Xing; Wang, Liancheng; Chen, Changbo; Zhao, Xiusong; Liu, Bingbing; Cui, Tian

    2010-08-21

    Ab initio calculations are performed to probe the hydrogen bonding, structural, and superconducting behaviors of HBr and HCl under high pressure. The calculated results show that the hydrogen bond symmetrization (Cmc2(1)-->Cmcm transition) of HBr and HCl occurs at 25 and 40 GPa, respectively, which can be attributed to the symmetry stretching A(1) mode softening. After hydrogen bond symmetrization, a pressure-induced soft transverse acoustic phonon mode of Cmcm phase is identified and a unique metallic phase with monoclinic structure of P2(1)/m (4 molecules/cell) for both compounds is revealed by ab initio phonon calculations. This phase preserves the symmetric hydrogen bond and is stable in the pressure range from 134 to 196 GPa for HBr and above 233 GPa for HCl, while HBr is predicted to decompose into Br(2)+H(2) above 196 GPa. Perturbative linear-response calculations predict that the phase P2(1)/m is a superconductor with T(c) of 27-34 K for HBr at 160 GPa and 9-14 K for HCl at 280 GPa.

  10. Enthalpy measurement of coal-derived liquids. Quarterly technical progress report, July--September 1978. [148 to 459/sup 0/F and 100 to 300 psia

    Energy Technology Data Exchange (ETDEWEB)

    Kidnay, A.J.; Yesavage, V.F.

    1978-12-01

    Experimental measurements were completed on a naphtha sample (1046) furnished by the Pittsburgh and Midway Coal Mining Company. A total of 38 measurements were made in the temperature region 148 to 459/sup 0/F, and at pressures of 100 and 300 psia. Additional analytical work was completed on the SRC-I naphtha whose enthalpy measurements were reported previously. Comparisons are given between the experimental SRC-I naphtha enthalpies and the available enthalpy data on petroleum fractions, including Kesler and Lee's correlation of these data. (LTN)

  11. Using a Potassium Acetate Solution for Cooling High Pressure Hydrogen in a Prototype Heat Exchanger

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Abel, M.; Rokni, Masoud

    2011-01-01

    A statement of intent assures more than 100.000 hydrogen vehicles will enter the market by 2015. A uniform approach for filling the vehicles has been developed and it states that cooling of the hydrogen is needed. For this purpose a test refrigeration facility was build. As the hydrogen...... was the most accurate of the methods compared. At low mass flows the calculated result was larger than the measured and at large mass flows the calculated results was lower than the measured. The used approach gives a reasonably accurate calculation for further investigations of cooling hydrogen....

  12. Hydrogen-Bond Symmetrization Breakdown and Dehydrogenation Mechanism of FeO2H at High Pressure.

    Science.gov (United States)

    Zhu, Sheng-Cai; Hu, Qingyang; Mao, Wendy L; Mao, Ho-Kwang; Sheng, Hongwei

    2017-09-06

    The cycling of hydrogen plays an important role in the geochemical evolution of our planet. Under high-pressure conditions, asymmetric hydroxyl bonds tend to form a symmetric O-H-O configuration in which H is positioned at the center of two O atoms. The symmetrization of O-H bonds improves their thermal stability and as such, water-bearing minerals can be present deeper in the Earth's lower mantle. However, how exactly H is recycled from the deep mantle remains unclear. Here, we employ first-principles free-energy landscape sampling methods together with high pressure-high temperature experiments to reveal the dehydrogenation mechanism of a water-bearing mineral, FeO2H, at deep mantle conditions. Experimentally, we show that ∼50% H is released from symmetrically hydrogen-bonded ε-FeO2H upon transforming to a pyrite-type phase (Py-phase). By resolving the lowest-energy transition pathway from ε-FeO2H to the Py-phase, we demonstrate that half of the O-H bonds in the mineral rupture during the structural transition, leading toward the breakdown of symmetrized hydrogen bonds and eventual dehydrogenation. Our study sheds new light on the stability of symmetric hydrogen bonds during structural transitions and provides a dehydrogenation mechanism for hydrous minerals existing in the deep mantle.

  13. Effect of a DC external electric field on the properties of a nonuniform microwave discharge in hydrogen at reduced pressures

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Yu. A., E-mail: lebedev@ips.ac.ru; Krashevskaya, G. V.; Tatarinov, A. V.; Titov, A. Yu.; Epshtein, I. L. [Russian Academy of Sciences, Topchiev Institute of Petrochemical Synthesis (Russian Federation)

    2017-01-15

    The effect of a dc external electrical field on the properties of a highly nonuniform electrode microwave discharge in hydrogen at a pressure of 1 Torr was studied using optical emission spectroscopy and selfconsistent two-dimensional simulations. It is shown that the negative voltage applied to the antenna electrode with respect to the grounded chamber increases the discharge radiation intensity, while the positive voltage does not affect the discharge properties. The simulation results agree well with the experimental data.

  14. Self-Pressurization and Spray Cooling Simulations of the Multipurpose Hydrogen Test Bed (MHTB) Ground-Based Experiment

    Science.gov (United States)

    Kartuzova, O.; Kassemi, M.; Agui, J.; Moder, J.

    2014-01-01

    This paper presents a CFD (computational fluid dynamics) model for simulating the self-pressurization of a large scale liquid hydrogen storage tank. In this model, the kinetics-based Schrage equation is used to account for the evaporative and condensing interfacial mass flows. Laminar and turbulent approaches to modeling natural convection in the tank and heat and mass transfer at the interface are compared. The flow, temperature, and interfacial mass fluxes predicted by these two approaches during tank self-pressurization are compared against each other. The ullage pressure and vapor temperature evolutions are also compared against experimental data obtained from the MHTB (Multipuprpose Hydrogen Test Bed) self-pressurization experiment. A CFD model for cooling cryogenic storage tanks by spraying cold liquid in the ullage is also presented. The Euler- Lagrange approach is utilized for tracking the spray droplets and for modeling interaction between the droplets and the continuous phase (ullage). The spray model is coupled with the VOF (volume of fluid) model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. Droplet ullage heat and mass transfer are modeled. The flow, temperature, and interfacial mass flux predicted by the model are presented. The ullage pressure is compared with experimental data obtained from the MHTB spray bar mixing experiment. The results of the models with only droplet/ullage heat transfer and with heat and mass transfer between the droplets and ullage are compared.

  15. Special structures and properties of hydrogen nanowire confined in a single walled carbon nanotube at extreme high pressure

    Directory of Open Access Journals (Sweden)

    Yueyuan Xia

    2012-06-01

    Full Text Available Extensive ab initio molecular dynamics simulations indicate that hydrogen can be confined in single walled carbon nanotubes to form high density and high pressure H2 molecular lattice, which has peculiar shell and axial structures depending on the density or pressure. The band gap of the confined H2 lattice is sensitive to the pressure. Heating the system at 2000K, the H2 lattice is firstly melted to form H2 molecular liquid, and then some of the H2 molecules dissociate accompanied by drastic molecular and atomic reactions, which have essential effect on the electronic structure of the hydrogen system. The liquid hydrogen system at 2000K is found to be a particular mixed liquid, which consists of H2 molecules, H atoms, and H-H-H trimers. The dissociated H atoms and the trimers in the liquid contribute resonance electron states at the Fermi energy to change the material properties substantially. Rapidly cooling the system from 2000K to 0.01 K, the mixed liquid is frozen to form a mixed solid melt with a clear trend of band gap closure. It indicates that this solid melt may become a superconducting nanowire when it is further compressed.

  16. Effect of Soret diffusion on lean hydrogen/air flames at normal and elevated pressure and temperature

    KAUST Repository

    Zhou, Zhen

    2017-04-12

    The influence of Soret diffusion on lean premixed flames propagating in hydrogen/air mixtures is numerically investigated with a detailed chemical and transport models at normal and elevated pressure and temperature. The Soret diffusion influence on the one-dimensional (1D) flame mass burning rate and two-dimensional (2D) flame propagating characteristics is analysed, revealing a strong dependency on flame stretch rate, pressure and temperature. For 1D flames, at normal pressure and temperature, with an increase of Karlovitz number from 0 to 0.4, the mass burning rate is first reduced and then enhanced by Soret diffusion of H2 while it is reduced by Soret diffusion of H. The influence of Soret diffusion of H2 is enhanced by pressure and reduced by temperature. On the contrary, the influence of Soret diffusion of H is reduced by pressure and enhanced by temperature. For 2D flames, at normal pressure and temperature, during the early phase of flame evolution, flames with Soret diffusion display more curved flame cells. Pressure enhances this effect, while temperature reduces it. The influence of Soret diffusion of H2 on the global consumption speed is enhanced at elevated pressure. The influence of Soret diffusion of H on the global consumption speed is enhanced at elevated temperature. The flame evolution is more affected by Soret diffusion in the early phase of propagation than in the long run due to the local enrichment of H2 caused by flame curvature effects. The present study provides new insights into the Soret diffusion effect on the characteristics of lean hydrogen/air flames at conditions that are relevant to practical applications, e.g. gas engines and turbines.

  17. Hydrogen Selective Inorganic membranes for Gas Separations under High Pressure Intermediate Temperature Hydrocarbonic Envrionment

    Energy Technology Data Exchange (ETDEWEB)

    Rich Ciora; Paul KT Liu

    2012-06-27

    In this project, we have successfully developed a full scale commercially ready carbon molecular sieve (CMS) based membrane for applications in H{sub 2} recovery from refinery waste and other aggressive gas streams. Field tests at a refinery pilot plant and a coal gasification facility have successfully demonstrated its ability to recovery hydrogen from hydrotreating and raw syngas respectively. High purity H{sub 2} and excellent stability of the membrane permeance and selectivity were obtained in testing conducted over >500 hours at each site. The results from these field tests as well as laboratory testing conclude that the membranes can be operated at high pressures (up to 1,000 psig) and temperatures (up to 300 C) in presence of aggressive contaminants, such as sulfur and nitrogen containing species (H{sub 2}S, CO{sub 2}, NH{sub 3}, etc), condensable hydrocarbons, tar-like species, heavy metals, etc. with no observable effect on membrane performance. By comparison, similar operating conditions and/or environments would rapidly destroy competing membranes, such as polymeric, palladium, zeolitic, etc. Significant cost savings can be achieved through recovering H{sub 2} from refinery waste gas using this newly developed CMS membrane. Annual savings of $2 to 4MM/year (per 20,000 scfd of waste gas) can be realized by recovering the H{sub 2} for reuse (versus fuel). Projecting these values over the entire US market, potential H{sub 2} savings from refinery waste gases on the order of 750 to 1,000MM scfd and $750 to $1,000MM per year are possible. In addition to the cost savings, potential energy savings are projected to be ca. 150 to 220 tBTU/yr and CO{sub 2} gas emission reductions are projected to be ca. 5,000 to 6,500MMtons/year. The full scale membrane bundle developed as part of this project, i.e., 85 x 30 inch ceramic membrane tubes packaged into a full ceramic potting, is an important accomplishment. No comparable commercial scale product exists in the

  18. Pressure of a partially ionized hydrogen gas : numerical results from exact low temperature expansions

    OpenAIRE

    Alastuey, Angel; Ballenegger, Vincent

    2010-01-01

    8 pages; International audience; We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first five leading corrections to the ideal Saha equation ...

  19. Hydrostatic pressure on optical absorption and refractive index changes of a shallow hydrogenic impurity in a GaAs/GaAlAs quantum wire

    Science.gov (United States)

    Santhi, M.; John Peter, A.; Yoo, ChangKyoo

    2012-08-01

    The effect of hydrostatic pressure on the binding energy of a hydrogenic impurity in a GaAs/GaAlAs quantum wire is discussed. Calculations have been performed using Bessel functions as an orthonormal basis within a single band effective mass approximation. Pressure induced photoionization cross section of the hydrogenic impurity is investigated. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of pressure are analysed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and the pressure.

  20. DOE Hydrogen, Fuel Cells and Infrastructure Technologies Program Integrated Hydrogen Production, Purification and Compression System

    Energy Technology Data Exchange (ETDEWEB)

    Tamhankar, Satish; Gulamhusein, Ali; Boyd, Tony; DaCosta, David; Golben, Mark

    2011-06-30

    The project was started in April 2005 with the objective to meet the DOE target of delivered hydrogen of <$1.50/gge, which was later revised by DOE to $2-$3/gge range for hydrogen to be competitive with gasoline as a fuel for vehicles. For small, on-site hydrogen plants being evaluated at the time for refueling stations (the 'forecourt'), it was determined that capital cost is the main contributor to the high cost of delivered hydrogen. The concept of this project was to reduce the cost by combining unit operations for the entire generation, purification, and compression system (refer to Figure 1). To accomplish this, the Fluid Bed Membrane Reactor (FBMR) developed by MRT was used. The FBMR has hydrogen selective, palladium-alloy membrane modules immersed in the reformer vessel, thereby directly producing high purity hydrogen in a single step. The continuous removal of pure hydrogen from the reformer pushes the equilibrium 'forward', thereby maximizing the productivity with an associated reduction in the cost of product hydrogen. Additional gains were envisaged by the integration of the novel Metal Hydride Hydrogen Compressor (MHC) developed by Ergenics, which compresses hydrogen from 0.5 bar (7 psia) to 350 bar (5,076 psia) or higher in a single unit using thermal energy. Excess energy from the reformer provides up to 25% of the power used for driving the hydride compressor so that system integration improved efficiency. Hydrogen from the membrane reformer is of very high, fuel cell vehicle (FCV) quality (purity over 99.99%), eliminating the need for a separate purification step. The hydride compressor maintains hydrogen purity because it does not have dynamic seals or lubricating oil. The project team set out to integrate the membrane reformer developed by MRT and the hydride compression system developed by Ergenics in a single package. This was expected to result in lower cost and higher efficiency compared to conventional hydrogen production

  1. Bioelectrochemical production of hydrogen in an innovative pressure-retarded osmosis/microbial electrolysis cell system: experiments and modeling.

    Science.gov (United States)

    Yuan, Heyang; Lu, Yaobin; Abu-Reesh, Ibrahim M; He, Zhen

    2015-01-01

    While microbial electrolysis cells (MECs) can simultaneously produce bioelectrochemical hydrogen and treat wastewater, they consume considerable energy to overcome the unfavorable thermodynamics, which is not sustainable and economically feasible in practical applications. This study presents a proof-of-concept system in which hydrogen can be produced in an MEC powered by theoretically predicated energy from pressure-retarded osmosis (PRO). The system consists of a PRO unit that extracts high-quality water and generates electricity from water osmosis, and an MEC for organic removal and hydrogen production. The feasibility of the system was demonstrated using simulated PRO performance (in terms of energy production and effluent quality) and experimental MEC results (e.g., hydrogen production and organic removal). The PRO and MEC models were proven to be valid. The model predicted that the PRO unit could produce 485 mL of clean water and 579 J of energy with 600 mL of draw solution (0.8 M of NaCl). The amount of the predicated energy was applied to the MEC by a power supply, which drove the MEC to remove 93.7 % of the organic compounds and produce 32.8 mL of H2 experimentally. Increasing the PRO influent volume and draw concentration could produce more energy for the MEC operation, and correspondingly increase the MEC hydraulic retention time (HRT) and total hydrogen production. The models predicted that at an external voltage of 0.9 V, the MEC energy consumption reached the maximum PRO energy production. With a higher external voltage, the MEC energy consumption would exceed the PRO energy production, leading to negative effects on both organic removal and hydrogen production. The PRO-MEC system holds great promise in addressing water-energy nexus through organic removal, hydrogen production, and water recovery: (1) the PRO unit can reduce the volume of wastewater and extract clean water; (2) the PRO effluents can be further treated by the MEC; and (3) the

  2. Development of a nuclear magnetic resonance system for in situ analysis of hydrogen storage materials under high pressures and temperatures.

    Science.gov (United States)

    Hashimoto, S; Noda, Y; Maekawa, H; Takamura, H; Fujito, T; Moriya, J; Ikeda, T

    2010-10-01

    A NMR system for in situ analysis of hydrogen storage materials under high pressure and temperature conditions was developed. The system consists of a gas pressure and flow rate controlling unit, a temperature controller, a high temperature NMR probe tunable for both (1)H and other nuclei, and a sample tube holder. Sample temperature can be controlled up to 623 K by heated N(2) gas flow. Sample tube atmosphere can be substituted by either H(2) or Ar and can be pressurized up to 1 MPa under constant flow rate up to 100 ml/min. During the NMR measurement, the pressure can be adjusted easily by just handle a back pressure valve. On the blank NMR measurement, (1)H background noise was confirmed to be very low. (1)H and (11)B NMR spectrum of LiBH(4) were successfully observed at high temperature for the demonstration of the system. The intensity of the (1)H NMR spectra of H(2) gas was also confirmed to be proportional to the applied pressure.

  3. Salt effect in the solubility of hydrogen in n-alcohols at pressures up to 10 MPa and temperatures up to 498.15 K

    Directory of Open Access Journals (Sweden)

    J. V.H. d’Angelo

    2000-12-01

    Full Text Available Gas-liquid solubility of hydrogen in methanol and ethanol systems with electrolytes was studied in the temperature range from 305.15 K to 498.15 K and pressures from 4 to 10 MPa. The experimental method used was the Total Pressure Method, which eliminates sampling and analysis of the phases, determining their composition at equilibrium using the following experimental data: moles of solute and solvent in the system; pressure, temperature and volume of the system at equilibrium; together with thermodynamic equations for fluid-phase equilibria. The salts used were lithium chloride and potassium acetate. The solubility of hydrogen increases with increasing temperature and pressure and the presence of salts causes a decrease in the solubility of hydrogen, when compared with the results of systems without salts, characterizing a "salting-out" effect, which is greater in conditions of lower temperature and pressure, specially for potassium acetate.

  4. Optical cell for combinatorial in situ Raman spectroscopic measurements of hydrogen storage materials at high pressures and temperatures.

    Science.gov (United States)

    Hattrick-Simpers, Jason R; Hurst, Wilbur S; Srinivasan, Sesha S; Maslar, James E

    2011-03-01

    An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storage materials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element lenses. For combinatorial investigations, up to 19 individual powder samples can be loaded into the optical cell at one time. This cell design is also compatible with thin-film samples. To demonstrate the capabilities of the cell, in situ measurements of the Ca(BH(4))(2) and nano-LiBH(4)-LiNH(2)-MgH(2) hydrogen storage systems at elevated temperatures and pressures are reported.

  5. Optical cell for combinatorial in situ Raman spectroscopic measurements of hydrogen storage materials at high pressures and temperatures

    Science.gov (United States)

    Hattrick-Simpers, Jason R.; Hurst, Wilbur S.; Srinivasan, Sesha S.; Maslar, James E.

    2011-03-01

    An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storage materials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element lenses. For combinatorial investigations, up to 19 individual powder samples can be loaded into the optical cell at one time. This cell design is also compatible with thin-film samples. To demonstrate the capabilities of the cell, in situ measurements of the Ca(BH4)2 and nano-LiBH4-LiNH2-MgH2 hydrogen storage systems at elevated temperatures and pressures are reported.

  6. Accurate evaluation of pressure effects on the electronic stopping cross section and mean excitation energy of atomic hydrogen beyond the Bethe approximation

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Trujillo, R., E-mail: trujillo@fis.unam.mx [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Ap. Postal 48-3, Cuernavaca, Morelos 62251 (Mexico); Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Ap. Postal 55-534, 09340 México, D.F. (Mexico); Cruz, S.A., E-mail: cruz@xanum.uam.mx [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Ap. Postal 55-534, 09340 México, D.F. (Mexico)

    2014-02-01

    Atomic hydrogen is used as a fundamental reference target system to explore pressure effects on the electronic stopping cross section, S{sub e}, of swift bare ions such as protons and α-particles. This is achieved by considering the hydrogen atom under pressure as a padded spherically-confined quantum system. Within this scheme, S{sub e} is calculated rigorously in the first Born approximation taking into account the full target excitation spectrum and momentum transfer distribution for different confinement conditions (pressures) and fixed projectile charge states. Pressure effects on the target mean excitation energy, I, are also formally calculated and compared with corresponding accurate calculations based on the Local Plasma Approximation (LPA). Even though atomic hydrogen is the simplest target system, its accurate treatment to account for the role of pressure in the stopping dynamics is found to provide useful means to understand the behavior of more complex systems under similar conditions. It is found that: (i) the region of projectile velocities for which the Bethe approximation remains valid is shifted towards higher values as pressure increases; (ii) shell corrections are enhanced relative to the free-atom case as pressure increases, and (iii) the LPA seems to underestimate I as pressure is increased. The results of this work for atomic hydrogen may serve as accurate benchmark reference values for studies of pressure effects on S{sub e} and I using different methodologies.

  7. Storage of hydrogen in advanced high pressure container. Final report for PSO projekt; Lagring af brint i avancerede hoejtryksbeholdere. Slutrapport for PSO-projekt

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, Jens

    2006-04-15

    The objective of the project has been to study barriers for a production of advanced high pressure containers especially suitable for hydrogen, in order to create a basis for a container production in Denmark. The project has primarily focused on future Danish need for hydrogen storage in the MWh area. One task has been to examine requirement specifications for pressure tanks that can be expected in connection with these stores. Six potential storage needs have been identified: (1) Buffer in connection with start-up/regulation on the power grid. (2) Hydrogen and oxygen production. (3) Buffer store in connection with VEnzin vision. (4) Storage tanks on hydrogen filling stations. (5) Hydrogen for the transport sector from 1 TWh surplus power. (6) Tanker transport of hydrogen. Requirements for pressure containers for the above mentioned use have been examined. The connection between stored energy amount, pressure and volume compared to liquid hydrogen and oil has been stated in tables. As starting point for production technological considerations and economic calculations of various container concepts, an estimation of laminate thickness in glass-fibre reinforced containers with different diameters and design print has been made, for a 'pure' fibre composite container and a metal/fibre composite container respectively. (BA)

  8. Benchmarking exchange-correlation functionals for hydrogen at high pressures using quantum Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Clay, Raymond C. [Univ. of Illinois, Urbana, IL (United States); Mcminis, Jeremy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McMahon, Jeffrey M. [Univ. of Illinois, Urbana, IL (United States); Pierleoni, Carlo [Istituto Nazionale di Fisica Nucleare (INFN), L' aquila (Italy). Lab. Nazionali del Gran Sasso (INFN-LNGS); Ceperley, David M. [Univ. of Illinois, Urbana, IL (United States); Morales, Miguel A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-05-01

    The ab initio phase diagram of dense hydrogen is very sensitive to errors in the treatment of electronic correlation. Recently, it has been shown that the choice of the density functional has a large effect on the predicted location of both the liquid-liquid phase transition and the solid insulator-to-metal transition in dense hydrogen. To identify the most accurate functional for dense hydrogen applications, we systematically benchmark some of the most commonly used functionals using quantum Monte Carlo. By considering several measures of functional accuracy, we conclude that the van der Waals and hybrid functionals significantly outperform local density approximation and Perdew-Burke-Ernzerhof. We support these conclusions by analyzing the impact of functional choice on structural optimization in the molecular solid, and on the location of the liquid-liquid phase transition.

  9. Study of Thermodynamic Vent and Screen Baffle Integration for Orbital Storage and Transfer of Liquid Hydrogen

    Science.gov (United States)

    Cady, E. C.

    1973-01-01

    A comprehensive analytical and experimental program was performed to determine the feasibility of integrating an internal thermodynamic vent system and a full wall-screen liner for the orbital storage and transfer of liquid hydrogen (LH2). Ten screens were selected from a comprehensive screen survey. The experimental study determined the screen bubble point, flow-through pressure loss, and pressure loss along rectangular channels lined with screen on one side, for the 10 screens using LH2 saturated at 34.5 N/cm2 (50 psia). The correlated experimental data were used in an analysis to determine the optimum system characteristics in terms of minimum weight for 6 tanks ranging from 141.6 m3 (5,000 ft3) to 1.416 m3 (50 ft3) for orbital storage times of 30 and 300 days.

  10. Morbidade da biópsia da próstata transretal guiada por ultrassonografia

    Directory of Open Access Journals (Sweden)

    Raphael Sandes Solha

    2013-04-01

    Full Text Available OBJETIVO: Avaliar a incidência de complicações pós-procedimento nos pacientes submetidos a biópsia prostática transretal guiada por ultrassom no setor de intervenção do Departamento de Diagnóstico por Imagem da Escola Paulista de Medicina - Universidade Federal de São Paulo. MATERIAIS E MÉTODOS: Foram avaliados, via contato telefônico, 132 pacientes submetidos a biópsia de próstata transretal guiada por ultrassom no período de abril/2011 a junho/2011, seguindo o protocolo padrão do nosso setor. RESULTADOS: As complicações pós-biópsia foram categorizadas em maiores e menores de acordo com a necessidade de avaliação médica adicional. Cinquenta e nove pacientes (61,8% apresentaram complicações, e desses, grande parte (86,4% apresentou sintomas leves e autolimitados, considerados menores. Oito pacientes (8,2% apresentaram complicações maiores, sendo que apenas um deles necessitou de tratamento sob regime de internação hospitalar. A retenção urinária foi a complicação maior mais incidente no nosso estudo. CONCLUSÃO: Corroborando outros estudos da literatura, nosso trabalho demonstrou baixa prevalência de complicações maiores após a biópsia prostática transretal.

  11. Hydrogen Absorption Induced Slow Crack Growth in Austenitic Stainless Steels for Petrochemical Pressure Vessel Industries

    Directory of Open Access Journals (Sweden)

    Ronnie Rusli

    2011-05-01

    Full Text Available Type 304Land type 309 austenitic stainless steels were tested either by exposed to gaseous hydrogen or undergoing polarized cathodic charging. Slow crack growth by straining was observed in type 304L, and the formation of α‘ martensite was indicated to be precursor for such cracking. Gross plastic deformation was observed at the tip of the notch, and a single crack grew slowly from this region in a direction approximately perpendicular to the tensile axis. Martensite formation is not a necessary condition for hydrogen embrittlement in the austenitic phase.

  12. Numerical Determination and Experimental Validation of a Technological Specimen Representative of High-Pressure Hydrogen Storage Vessels

    Science.gov (United States)

    Gentilleau, B.; Touchard, F.; Grandidier, J.-C.; Mellier, D.

    2015-09-01

    A technological specimen representative of type IV high-pressure hydrogen storage vessels is developed. An analytical model is used to compute fiber orientations in the specimen in order to be as representative as possible of the stress level reached in a tank during pressurization. A three-dimensional finite-element model is used to determine the best stacking sequence with these fiber orientations. A validation is done by performing tests with digital image correlation in order to measure displacements on the lateral side of the specimen. A comparison between the calculated and experimentally found strain fields is made. The results obtained highlight the influence of stacking sequence on the development of damage and the difficulty arising in designing representative specimens.

  13. Suppression of Graphene Nucleation by Turning Off Hydrogen Supply Just before Atmospheric Pressure Chemical Vapor Deposition Growth

    Directory of Open Access Journals (Sweden)

    Seiya Suzuki

    2017-11-01

    Full Text Available To exploit the extraordinary property of graphene in practical electrical and optical devices, it is necessary to produce large-sized, single-crystal graphene. Atmospheric pressure chemical vapor deposition (APCVD on polycrystalline Cu surface is a promising scalable route of graphene synthesis but the unavoidable multiple nucleation limits their reachable domain size. Here, we report that effective suppression of nucleation was achieved by only turning off hydrogen supply before introduction of the carbon source for graphene growth. The density of graphene decreased from 72.0 to 2.2 domains/cm2 by turning off hydrogen for 15 min. X-ray photoelectron spectroscopy and Raman spectroscopy studies show that the Cu surface was covered with 3–4 nm thick highly crystalline Cu2O, which would be caused by oxidation by residual oxidative gasses in the chamber during the turning off period. It was also revealed that elevating the temperature in Ar followed by annealing in H2/Ar before turning off hydrogen led to the enlargement of the Cu domain, resulting in the further suppression of nucleation. By optimizing such growth parameters in the CVD process, a single-crystal graphene with ~2.6 mm in diameter was successfully obtained.

  14. Water-Gas-Shift Membrane Reactor for High-Pressure Hydrogen Production. A comprehensive project report (FY2010 - FY2012)

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); Peterson, Eric [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, New York (United States); Miller, Scott [General Electric Global Research, Niskayuna, New York (United States); Ku, Anthony [General Electric Global Research, Niskayuna, New York (United States); Polishchuk, Kimberly [General Electric Global Research, Niskayuna, New York (United States); Narang, Kristi [General Electric Global Research, Niskayuna, New York (United States); Singh, Surinder [General Electric Global Research, Niskayuna, New York (United States); Wei, Wei [General Electric Global Research, Niskayuna, New York (United States); Shisler, Roger [General Electric Global Research, Niskayuna, New York (United States); Wickersham, Paul [General Electric Global Research, Niskayuna, New York (United States); McEvoy, Kevin [General Electric Global Research, Niskayuna, New York (United States); Alberts, William [General Electric Global Research, Niskayuna, New York (United States); Howson, Paul [General Electric Global Research, Niskayuna, New York (United States); Barton, Thomas [Western Research inst., Laramie, WY (United States); Sethi, Vijay [Western Research inst., Laramie, WY (United States)

    2013-01-01

    Idaho National Laboratory (INL), GE Global Research (GEGR), and Western Research Institute (WRI) have successfully produced hydrogen-selective membranes for water-gas-shift (WGS) modules that enable high-pressure hydrogen product streams. Several high performance (HP) polymer membranes were investigated for their gas separation performance under simulated (mixed gas) and actual syngas conditions. To enable optimal module performance, membranes with high hydrogen (H2) selectivity, permeance, and stability under WGS conditions are required. The team determined that the VTEC PI 80-051 and VTEC PI 1388 (polyimide from Richard Blaine International, Inc.) are prime candidates for the H2 gas separations at operating temperatures (~200°C). VTEC PI 80-051 was thoroughly analyzed for its H2 separations under syngas processing conditions using more-complex membrane configurations, such as tube modules and hollow fibers. These membrane formats have demonstrated that the selected VTEC membrane is capable of providing highly selective H2/CO2 separation (α = 7-9) and H2/CO separation (α = 40-80) in humidified syngas streams. In addition, the VTEC polymer membranes are resilient within the syngas environment (WRI coal gasification) at 200°C for over 1000 hours. The information within this report conveys current developments of VTEC PI 80-051 as an effective H2 gas separations membrane for high-temperature syngas streams.

  15. Enthalpy measurement of coal-derived liquids. Quarterly technical progress report, July--September 1977. [155 to 742 degrees F and 150, 200, 500, 1000 and 1500 psia

    Energy Technology Data Exchange (ETDEWEB)

    Kidnay, A.J.; Yesavage, V.F.

    1977-10-15

    Coal-derived liquids are a new and vital class of industrial compounds, but have thermodynamic properties that are largely unknown and, presently, unpredictable. The objective of this research is to measure one of the most important thermodynamic properties, the enthalpy, for representative coal-derived liquids over the pressure and temperature regions most likely to be encountered in both liquefaction and processing systems. Experimental measurements were made on a distillate from a coal-derived liquid sample produced with the Synthoil process. The measurements extend from 155 to 742/sup 0/F at pressures of 150, 200, 500, 1000, and 1500 psia. Enthalpy measurements were also started on a naphtha cut from a coal-derived liquid produced by the SRC-I process. These naphtha measurements are approximately 60 percent complete.

  16. Depolymerization of lignin at low pressure using Lewis acid catalysts and under high pressure using hydrogen donor solvents

    Energy Technology Data Exchange (ETDEWEB)

    Davoudzadeh, F.; Coughlin, R.W.; Avni, E.; Smith, B.

    1985-06-01

    Adding phenol or guaiacol to the reaction mixture increased liquefaction of lignin from steam-exploded wood in tetralin at about 140 kg/cm/sup 2/ pressure and 300/sup 0/C. Phenol increased yields of filterable products from about 40 to 63%, guaiacol from about 30% to 50%. At one atmosphere and 110 to 200/sup 0/C only about 25% of the lignin could be converted to liquid regardless of whether phenol, tetralin or Lewis acid catalysts were employed. Of a variety of catalysts investigated at higher pressures NiO-MoO/sub 3/ supported on alumina gave the best results. Raising the temperature from 300 to 400/sup 0/C increased filtrate yields from the 30% to the 90% range at about 140 kg/cm/sup 2/ in H/sub 2/. The lower molecular weight lignin from steam-exploded wood (Iotech) gave somewhat larger conversions than Indulin, a Kraft lignin from Westvaco. The reaction products detected include methoxyphenols, cresols, alkyl cresols, guaiacol, toluenes, anisole, cinnamaldehyde and cumene.

  17. Solubility of hydrogen sulfide in aqueous solutions of N-methyldiethanolamine at high pressures

    DEFF Research Database (Denmark)

    Sadegh, Negar; Thomsen, Kaj; Solbraa, Even

    2015-01-01

    A static-analytic method was used to measure the H2S solubility in 50 wt% MDEA and in presence of methane as a makeup gas. The solubility was measured at 7000 kPa total pressure, and at 50 and 70 degrees C, for H2S partial pressures from 31 to 974 kPa. Measurements were also performed at 1500 k......Pa total pressure and 50 degrees C for H2S partial pressure span of 53-386 kPa. The measured data were compared to predictions using the Extended UNIQUAC model. The experimental data showed that the total pressure has a significant effect on H2S solubility in aqueous MDEA. The observed effect is shown...

  18. Lattice stability and high pressure melting mechanism of dense hydrogen up to 1.5 TPa

    CERN Document Server

    Geng, Hua Y; Wu, Q

    2016-01-01

    Lattice stability and metastability, as well as melting, are important features of the physics and chemistry of dense hydrogen. Using ab initio molecular dynamics (AIMD), the classical superheating limit and melting line of metallic hydrogen are investigated up to 1.5 TPa. The computations show that the classical superheating degree is about 100 K, and the classical melting curve becomes flat at a level of 350 K when beyond 500 GPa. This information allows us to estimate the well depth and the potential barriers that must be overcome when the crystal melts. Inclusion of nuclear quantum effects (NQE) using path integral molecular dynamics (PIMD) predicts that both superheating limit and melting temperature are lowered to below room temperature, but the latter never reach absolute zero. Detailed analysis indicates that the melting is thermally activated, rather than driven by pure zero-point motion (ZPM). This argument was further supported by extensive PIMD simulations, demonstrating the stability of Fddd stru...

  19. Manyparticle interactions and local structure of the metallic hydrogen at zero pressure

    OpenAIRE

    Kaim, S. D.; Kovalenko, N. P.; Vasiliu, E. V.

    2000-01-01

    On the basis of the perturbation expansion for electron gas energy in the third order to the electron-ion potential the pair and irreducible three-ion interaction potentials in metallic hydrogen are calculated. The irreducible potential of three-ion interaction has attractive nature at short interionic separation and oscillates at large ones. The anisotropic character of the three-ion interaction is shown. The potential relief of the pair ions relative to the third ion is constructed. This re...

  20. Hydrogen and synthetic fuel production using pressurized solid oxide electrolysis cells

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Sun, Xiufu; Ebbesen, Sune

    2010-01-01

    Wind and solar power is troubled by large fluctuations in delivery due to changing weather. The surplus electricity can be used in a Solid Oxide Electrolyzer Cell (SOEC) to split CO2 + H2O into CO + H2 (+O2). The synthesis gas (CO + H2) can subsequently be catalyzed into various types of synthetic...... fuels using a suitable catalyst. As the catalyst operates at elevated pressure the fuel production system can be simplified by operating the SOEC at elevated pressure. Here we present the results of a cell test with pressures ranging from 0.4 bar to 10 bar. The cell was tested both as an SOEC...

  1. Effect of Coexistent Hydrogen on the Selective Production of Ethane by Dehydrogenative Methane Coupling through Dielectric-Barrier Discharge under Ordinary Pressure at an Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Katsuya Konno

    2014-01-01

    Full Text Available The effect of coexistence of hydrogen on the product selectivity to ethane from methane by dielectric-barrier discharge (DBD reactor was examined experimentally under ordinary pressure without use of catalyst and external heating. By the dilution of methane with hydrogen, both the increase of methane conversion and the decrease of alkene production were observed, improving the selectivities to ethane by ca. 70%.

  2. Effect of Hydrogen Exposure on Mechanical and Tribological Behavior of CrxN Coatings Deposited at Different Pressures on IN718

    Directory of Open Access Journals (Sweden)

    Aleksei Obrosov

    2017-05-01

    Full Text Available In the current study, the properties of the CrxN coatings deposited on the Inconel 718 superalloy using direct current reactive magnetron sputtering are investigated. The influence of working pressure on the microstructure, mechanical, and tribological properties of the CrxN coatings before and after high-temperature hydrogen exposure is studied. The cross-sectional scanning electron micrographs indicate the columnar structure of the coatings, which changes from dense and compact columns to large columns with increasing working pressure. The Cr/N ratio increases from 1.4 to 1.9 with increasing working pressure from 300 to 900 mPa, respectively. X-ray diffraction analysis reveals a change from mixed hcp-Cr2N and fcc-CrN structure to approximately stoichiometric Cr2N phase. After gas-phase hydrogenation, the coating deposited at 300 mPa exhibits the lowest hydrogen absorption at 600 °C of all investigated coatings. The results indicate that the dense mixed cubic and hexagonal structure is preferential for hydrogen permeation resistance due to the presence of cubic phase with higher packing density in comparison to the hexagonal structure. After hydrogenation, no changes in phase composition were observed; however, a small amount of hydrogen is accumulated in the coatings. An increase of coating hardness and elastic modulus was observed after hydrogen exposure. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient up to 20%–30%. The best value of 0.25 was reached for hydrogen exposed CrxN coating deposited at 300 mPa.

  3. Effect of hydrogen pressure on free radicals in direct coal liquefaction/coprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Seehra, M.S.; Ibrahim, M.M. [West Virginia Univ., Morgantown, WV (United States)

    1995-12-31

    The objective of this study was to investigate the coprocessing of coal with waste tires and commingled plastics and to characterize the relevant catalysts, using high pressure/high temperature in-situ ESR (Electron Spin Resonance) spectroscopy. The recent results from high pressure ESR spectroscopy are emphasized. During this period, considerable progress was made in developing the high pressure capabilities in in-situ ESR spectroscopy and new results carried out in 1000 psi of H{sub 2}gas are presented. In these experiments, sapphire tubes were used to contain the high pressures at temperatures up to 500{degrees}C. Results of the experiments carried out under 1000 psi of H{sub 2} are compared with those under 1000 psi of non-interacting argon and with the earlier experiments in flowing H{sub 2} gas where the volatiles are removed by the flowing gas. In these experiments, the free radical density N of the Blind Canyon coal was measured at each temperature and pressure by double integration of the ESR signal and calibrating it against a standard. The details of the experimental apparatus and procedures have been described in earlier publications.

  4. Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements.

    Science.gov (United States)

    Flesch, K; Kremeyer, T; Schmitz, O; Soukhanovskii, V; Wenzel, U

    2016-11-01

    Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D2 molecules and the He ash which will be produced by deuterium-tritium fusion. To study He exhaust, an in situ Penning gauge system is being developed at UW-Madison that is optimized for good pressure and high spectroscopic sensitivity. Three different anode geometries have been studied regarding their vacuum electrostatic fields, light output, and ion current. The light output of the two new anode configurations are at least one order of magnitude above the currently available designs, hence improving the spectroscopic sensitivity at similar total neutral pressure resolution.

  5. NHETS - Estudo de Necrópsias de Pacientes Submetidos a Transplante Cardíaco

    Directory of Open Access Journals (Sweden)

    Thiago Ninck Valette

    2014-06-01

    Full Text Available Fundamento: Discordâncias entre diagnóstico pre e post-mortem são relatadas na literatura, podendo variar de 4,1 a 49,8% dentre os casos encaminhados para exame necroscópico, com importante repercussão no tratamento dos pacientes. Objetivo: Analisar pacientes com óbito após o transplante cardíaco e confrontar os diagnósticos pre e post-mortem. Métodos: Por meio da revisão de prontuários, foram analisados dados clínicos, presença de comorbidades, esquema de imunossupressão, exames laboratoriais, causa clínica do óbito e causa do óbito à necrópsia. Foram confrontadas, então, a causa clínica e a causa necroscópica do óbito de cada paciente. Resultados: Foram analisados 48 óbitos submetidos à necrópsia no período de 2000 a 2010; 29 (60,4% tiveram diagnósticos clínico e necroscópico concordantes, 16 (33,3% tiveram diagnósticos discordantes e três (6,3% tiveram diagnóstico não esclarecido. Entre os discordantes, 15 (31,3% apresentaram possível impacto na sobrevida e um (2,1% não apresentou impacto na sobrevida. O principal diagnóstico clínico feito equivocadamente foi o de infecção, com cinco casos (26,7% dos discordantes, seguido por rejeição hiperaguda, com quatro casos (20% dos discordantes, e tromboembolismo pulmonar, com três casos (13,3% dos discordantes. Conclusão: Discordâncias entre o diagnóstico clínico e achados da necrópsia são comumente encontradas no transplante cardíaco. Novas estratégias no aperfeiçoamento do diagnóstico clínico devem ser introduzidas, considerando-se os resultados da necrópsia para melhoria do tratamento da insuficiência cardíaca por meio do transplante cardíaco.

  6. Hydrogen transfer hydrocracking of C. procera latex under ambient pressure conditions to get value added chemicals and fuels

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, D.K.; Behera, B.K.; Arora, M. (Indian Institute of Technology, New Delhi (India). Fuels and Biofuels Engineering Lab.)

    1994-01-01

    Biomass is renewable source of energy while the reserves of petroleum are being depleted. The latex of a potential petrocrop, Calotropis procera, a laticifer, arid-plant which is rich in hydrocarbon type triterpene compounds etc. was found to be a better feed stock for thermal hydrocracking as compared to whole plant biomass in terms of liquid product yield. Studies of chemical reaction dynamics of the thermal cracking of latex at 200-400[degree]C showed that the process should be termed as hydrogen-transfer (H-T) hydrocracking of latex under ambient pressure conditions. The hydrogen rich cracked triterpenoids act as the H-donors in this process, where nascent hydrogen atoms and free radicals chemically plug the cracked moieties to stabilise these. Latex was also coagulated and the H-T hydrocracking of the feedstock coagulum gave a higher yield of cracked oil in comparison to that from the dried latex. The temperature for hydrocracking of latex has been optimized to 350[degree]C and molecular sieve was found to catalyse the H-T hydrocracking process to yield more liquid product. The distillation range of cracked latex oil (CLO) obtained from H-T hydrocracking of C. procera latex indicated that it can be used as fuel oil or substitute for diesel fuel. Moreover, CLO resembled diesel fuels and was predominantly paraffinic in nature as characterised by NMR and FTIR spectral analysis. A process has been recommended for getting value added fuels and chemicals from C. procera latex. 29 refs., 5 figs., 3 tabs.

  7. Pressure dependent deuterium fractionation in the formation of molecular hydrogen in formaldehyde photolysis

    DEFF Research Database (Denmark)

    Nilsson, Elna Johanna Kristina; Andersen, Vibeke Friis; Skov, Henrik

    2009-01-01

    and 1030 mbar. The relative dissociation rate kHCHO/kHCDO was found to depend strongly on pressure, varying from 1.1±0.1 at 50 mbar to 1.75±0.10 at 1030 mbar. The products of formaldehyde photodissociation are either H2+CO (molecular channel) or HCO+H (radical channel). The partitioning between...

  8. Electrochemical Separation, Pumping, and Storage of Hydrogen or Oxygen into Nanocapillaries Via High Pressure MEA Seals

    Science.gov (United States)

    2015-10-13

    with a membrane electrode assembly (MEA). Hoop stress calculations show that the pressure tolerances of cylinders are inversely proportional to the...will be discussed. A discussion of the electrochemistry within nanocapillaries compared to planar MEAs will be given including the charge transport... electrode assembly 16. SECURITY CLASSIFICATION OF: Unclassified 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON

  9. Intermetallic GaPd2 Nanoparticles on SiO2 for Low-Pressure CO2 Hydrogenation to Methanol

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Sharafutdinov, Irek; Carvalho, Hudson W. P.

    2015-01-01

    A nanodispersed intermetallic GaPd2/SiO2 catalyst is prepared by simple impregnation of industrially relevant high-surface-area SiO2 with Pd and Ga nitrates, followed by drying, calcination, and reduction in hydrogen. The catalyst is tested for CO2 hydrogenation to methanol at ambient pressure......, revealing that the intrinsic activity of the GaPd2/SiO2 is higher than that of the conventional Cu/ZnO/Al2O3, while the production of the undesired CO is lower. A combination of complementary in situ and ex situ techniques are used to investigate the GaPd2/SiO2 catalyst. In situ X-ray diffraction...... of exactly the same catalyst area recorded at the different steps of activation and reaction procedure) show that nanoparticle size and dispersion are defined upon calcination with no significant changes observed after reduction and methanol synthesis. Similar conclusions can be drawn from electron...

  10. Ordering of hydrogen bonds in high-pressure low-temperature H2O.

    Science.gov (United States)

    Cai, Y Q; Mao, H-K; Chow, P C; Tse, J S; Ma, Y; Patchkovskii, S; Shu, J F; Struzhkin, V; Hemley, R J; Ishii, H; Chen, C C; Jarrige, I; Chen, C T; Shieh, S R; Huang, E P; Kao, C C

    2005-01-21

    The near K-edge structure of oxygen in liquid water and ices III, II, and IX at 0.25 GPa and several low temperatures down to 4 K has been studied using inelastic x-ray scattering at 9884.7 eV with a total energy resolution of 305 and 175 meV. A marked decrease of the preedge intensity from the liquid phase and ice III to ices II and IX is attributed to ordering of the hydrogen bonds in the proton-ordered lattice of the latter phases. Density functional theory calculations including the influence of the Madelung potential of the ice IX crystal correctly account for the remaining preedge feature. Furthermore, we obtain spectroscopic evidence suggesting a possible new phase of ice at temperatures between 4 and 50 K.

  11. Solar Thermal Upper Stage Liquid Hydrogen Pressure Control Testing and Analytical Modeling

    Science.gov (United States)

    Olsen, A. D.; Cady, E. C.; Jenkins, D. S.; Chandler, F. O.; Grayson, G. D.; Lopez, A.; Hastings, L. J.; Flachbart, R. H.; Pedersen, K. W.

    2012-01-01

    The demonstration of a unique liquid hydrogen (LH2) storage and feed system concept for solar thermal upper stage was cooperatively accomplished by a Boeing/NASA Marshall Space Flight Center team. The strategy was to balance thermodynamic venting with the engine thrusting timeline during a representative 30-day mission, thereby, assuring no vent losses. Using a 2 cubic m (71 cubic ft) LH2 tank, proof-of-concept testing consisted of an engineering checkout followed by a 30-day mission simulation. The data were used to anchor a combination of standard analyses and computational fluid dynamics (CFD) modeling. Dependence on orbital testing has been incrementally reduced as CFD codes, combined with standard modeling, continue to be challenged with test data such as this.

  12. Hydrodynamic analysis of a three-fluidized bed reactor cold flow model for chemical looping hydrogen generation. Pressure characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhipeng; Xiang, Wenguo; Chen, Shiyi; Wang, Dong [Southeast Univ., Nanjing (China). School of Energy and Environment

    2013-07-01

    Chemical looping hydrogen generation (CLHG) can produce pure hydrogen with inherent separation of CO{sub 2} from fossils fuel. The process involves a metal oxide, as an oxygen carrier, such as iron oxide. The CLHG system consists of three reactors: a fuel reactor (FR), a steam reactor (SR) and an air reactor (AR). In the FR, the fuel gases react with iron oxides (hematite Fe{sub 2}O{sub 3}, magnetite Fe{sub 3}O{sub 4}, wuestite FeO), generating reduced iron oxides (FeO or even Fe), and with full conversion of gaseous fuels, pure CO{sub 2} can be obtained after cooling the flue gas from the fuel reactor; in the SR, FeO and Fe reacts with steam to generate magnetite (Fe{sub 3}O{sub 4}) and H{sub 2}, the latter representing the final target product of the process; in the AR, the magnetite is oxidized back to hematite which is used in another cycle. A cold flow model of three-fluidized bed for CLHG corresponding to 50 KW hot units has been built. A major novelty of this facility is the compact fuel reactor, which integrates a bubble and a fast fluidized bed to avoid the incomplete conversion of the fuel gas caused by the thermodynamics equilibrium. In order to study the pressure characteristics and the solids concentration of the system, especially in the fuel reactor, the gas velocity of three reactors, gas flow of L-type value, total solids inventory (TSI) and the secondary air of fuel reactor were varied. Results show that the pressure and the solids concentration are strongly influenced by the fluidizing-gas velocity of three reactors. Moreover, the entrainment of the upper part of fuel reactor increases as the total solids inventory increases, and the operating range of the FR can be changed by introducing secondary air or increasing the total solids inventory.

  13. Pressure Drop Experiments on a Flow Channel Filled with Catalysts for Nuclear Hydrogen Production System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sungdeok; Kim, C. S.; Kim, M. H.; Kim, Y. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seo, D. U.; Park, G. C. [Seoul National Univ., Seoul (Korea, Republic of)

    2014-05-15

    The Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand severe operating conditions. Hong and Seo have been studying a two-dimensional numerical analysis for a catalyst channel line-up with a 3mm ball shaped catalyst. They compared their CFD results to many widespread correlations developed for porous media such as those by Carman, Ergun, and Zhavoronkov as well as Susskind and Becker and Reichelt including a pebble-bed nuclear reactor design correlation. They concluded that the validation should be accomplished by the experiments for a catalyst channel simulating the channel of the PHE. In this paper, we discuss the pressure drop experiments on a flow channel filled with ball shaped catalysts. The test section simulates a single channel of the PHE secondary side plate-fin channel. The experimental results compared well with the known pressure drop correlations and a numerical analysis, respectively. We discussed an experimental validation of a pressure drop correlations and 2D CFD analysis on a flow channel filled with catalysts in the channel. The results of the pressure drop measurements are compared with the results obtained using well-known empirical correlations and 2D CFD analysis. From the comparison results, the validity of all the correlations and 2D numerical analysis is not satisfactory. There are two kind of reasons are presumed. While the general packed channel has radially infinite and complete circular cross section, the catalyst channel has radially finite with a very narrow width and irregular wavy cross section. Another reason is presumed to be because the inordinate large void fraction in the catalyst channel which is beyond the application range on void fraction in the empirical correlations.

  14. Leptospirose de evolução fulminante: um caso de autópsia

    Directory of Open Access Journals (Sweden)

    Fernando Peixoto Ferraz de Campos

    2012-08-01

    Full Text Available A leptospirose é uma doença febril aguda septicêmica que afeta humanos e/ou animais com alta incidência mundial principalmente em países tropicais em desenvolvimento.É uma doença de ocorrência na zona rural e urbana com algumas características próprias ocupacionais ou recreativas. Os indivíduos mais acometidos na grande maioria das vezes são jovens ou adultos jovens. Aproximadamente 5% - 15% dospacientes apresentam a forma grave da doença conhecida como doença de Weill que pode se associar a síndrome da hemorragia pulmonar da leptospirose. Apresentamosum relato de autópsia de uma paciente octogenária, residente na zona urbana do município de São Paulo, internada no Hospital Universitário da Universidade de São Paulo, que apresentou quadro de evolução fulminante. A autópsia revelou comprometimento dos pulmões com hemorragia alveolar difusa e infiltração mononuclear dos septos alveolares. A histologia do fígado apresentava destrabeculação dos hepatócitos, alargamento dos sinusóides e hiperplasia das células de Kupfer. Necrose tubular aguda e nefrite intersticial caracterizaram a histologia dos rins.

  15. Influence of loading rate and hydrogen content on fracture toughness of Zr-2.5Nb pressure tube material

    Energy Technology Data Exchange (ETDEWEB)

    Bind, A.K. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Singh, R.N., E-mail: rnsingh@barc.gov.in [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Division of Solid Mechanics, Lund University, SE22100 (Sweden); Khandelwal, H.K. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Sunil, S.; Avinash, G.; Chakravartty, J.K. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Ståhle, P. [Division of Solid Mechanics, Lund University, SE22100 (Sweden)

    2015-10-15

    For the safety assessment of PHWR, it is required to study the flaw tolerance capacity of the pressure tubes as a function of the loading rate. In this work, the effect of loading rate and hydrogen content on the fracture behaviour of a Zr-2.5Nb alloy pressure tube was investigated between 25 and 300 °C. For the as received material, the pulling rate only had an effect on fracture toughness at 25 °C whereas for hydrided material the pulling rate affected fracture toughness in the transition regime. For all pulling rates, hydrided materials showed typical S curve behavior with an increase in lower shelf, upper shelf and transition temperature with pulling rate. The number of axial splits on fracture surfaces increased with an increase in the pulling rate and a decrease in temperature and fracture toughness was found to decrease with an increase in the number of axial splits. The reduction in fracture toughness is attributed to a localised deformation between axial splits.

  16. Straightforward high-pressure synthesis and characterization of indium-based thiospinels: photocatalytic potential for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Falcon, Horacio [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco (Spain); NANOTEC (Centro de Investigacion en Nanociencia y Nanotecnologia), Universidad Tecnologica Nacional-Facultad Regional Cordoba, Cordoba (Argentina); Tartaj, Pedro; Alonso, Jose Antonio [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco (Spain); Vaquero, Fernando; Navarro, Rufino M.; Fierro, Jose Luis G. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, Madrid (Spain); Bolletta, Juan P.; Paoli, Juan M. de; Carbonio, Raul E. [INFIQC - CONICET, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba (Argentina); Fernandez-Diaz, Maria Teresa [Institut Laue Langevin, Grenoble (France)

    2016-04-15

    Ternary chalcogenides (AB{sub 2}X{sub 4}) based on the spinel structure are gaining a great deal of attention because of the possibility of tuning their magnetic and optoelectronic properties not only by changing chemical composition but also by altering their degree of inversion. Here we report a rapid high-pressure synthetic method for the synthesis of MIn{sub 2}S{sub 4} powders starting from commercially available solid sulfides. We prove the versatility of our method by reporting the synthesis of six members of the MIn{sub 2}S{sub 4} family (M = Mn, Fe, Co, Ni, Zn, and Cd) under high-pressure conditions (3.5 GPa); these compounds show complete to moderate degrees of inversion. Furthermore, this family covers a spectral region that includes visible band gaps. Interestingly, the structural refinement carried out by X-ray and neutron diffraction allows one to establish positive correlations between the gap and different parameters, including the degree of inversion. Finally, as a proof-of-concept, these ternary chalcogenides show moderate photocatalytic hydrogen production from aqueous solutions. (Copyright copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Effect of high-temperature water and hydrogen on the fracture behavior of a low-alloy reactor pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Roychowdhury, S., E-mail: sroy27@gmail.com [Paul Scherrer Institut, Nuclear Energy and Safety Research Department, Laboratory for Nuclear Materials, 5232 Villigen, PSI (Switzerland); Materials Processing & Corrosion Engineering Division, Mod-Lab, D-Block, Bhabha Atomic Research Centre, Mumbai 400085 (India); Seifert, H.-P.; Spätig, P.; Que, Z. [Paul Scherrer Institut, Nuclear Energy and Safety Research Department, Laboratory for Nuclear Materials, 5232 Villigen, PSI (Switzerland)

    2016-09-15

    Structural integrity of reactor pressure vessels (RPV) is critical for safety and lifetime. Possible degradation of fracture resistance of RPV steel due to exposure to coolant and hydrogen is a concern. In this study tensile and elastic-plastic fracture mechanics (EPFM) tests in air (hydrogen pre-charged) and EFPM tests in hydrogenated/oxygenated high-temperature water (HTW) was done, using a low-alloy RPV steel. 2–5 wppm hydrogen caused embrittlement in air tensile tests at room temperature (25 °C) and at 288 °C, effects being more significant at 25 °C and in simulated weld coarse grain heat affected zone material. Embrittlement at 288 °C is strain rate dependent and is due to localized plastic deformation. Hydrogen pre-charging/HTW exposure did not deteriorate the fracture resistance at 288 °C in base metal, for investigated loading rate range. Clear change in fracture morphology and deformation structures was observed, similar to that after air tests with hydrogen. - Highlights: • Hydrogen content, microstructure of LAS, and strain rate affects tensile properties at 288 °C. • Strength affects hydrogen embrittlement susceptibility to a greater extent than grain size. • Hydrogen in LAS leads to strain localization and restricts cross-slip at 288 °C. • Possible hydrogen pickup due to exposure to 288 °C water alters fracture surface appearance without affecting fracture toughness in bainitic base material. • Simulated weld heat affected zone microstructure shows unstable crack propagation in 288 °C water.

  18. Reversible hydrogen storage using CO2 and a proton-switchable iridium catalyst in aqueous media under mild temperatures and pressures.

    Science.gov (United States)

    Hull, Jonathan F; Himeda, Yuichiro; Wang, Wan-Hui; Hashiguchi, Brian; Periana, Roy; Szalda, David J; Muckerman, James T; Fujita, Etsuko

    2012-03-18

    Green plants convert CO(2) to sugar for energy storage via photosynthesis. We report a novel catalyst that uses CO(2) and hydrogen to store energy in formic acid. Using a homogeneous iridium catalyst with a proton-responsive ligand, we show the first reversible and recyclable hydrogen storage system that operates under mild conditions using CO(2), formate and formic acid. This system is energy-efficient and green because it operates near ambient conditions, uses water as a solvent, produces high-pressure CO-free hydrogen, and uses pH to control hydrogen production or consumption. The extraordinary and switchable catalytic activity is attributed to the multifunctional ligand, which acts as a proton-relay and strong π-donor, and is rationalized by theoretical and experimental studies.

  19. Impact of the carbon pore size and topology on the equilibrium quantum sieving of hydrogen isotopes at zero coverage and finite pressures

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, Piotr [Applied Physics, RMIT University, GPO Box 2476V, Victoria 3001 (Australia); Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester [Department of Chemistry, Physicochemistry of Carbon Materials Research Group, Nicholas Copernicus University, Gagarin Street 7, 87-100 Torun (Poland)], E-mail: E72231@ems.rmit.edu.au, E-mail: aterzyk@chem.uni.torun.pl

    2009-04-08

    Carbonaceous slit-shaped and square-shaped pores efficiently differentiate adsorbed hydrogen isotopes at 77 and 33 K. Extensive path integral Monte Carlo simulations revealed that the square-shaped carbon pores enhanced the selectivity of deuterium over hydrogen in comparison to equivalent slit-shaped carbon pores at zero coverage as well as at finite pressures (i.e. quantum sieving of hydrogen isotopes is pore-topology-dependent). We show that this enhancement of the D{sub 2}/H{sub 2} equilibrium selectivity results from larger localization of hydrogen isotopes in square-shaped pores. The operating pressures for efficient quantum sieving of hydrogen isotopes are strongly dependent on the topology as well as on the size of the carbon pores. However, for both considered carbon pore topologies the highest D{sub 2}/H{sub 2} separation factor is observed at zero-coverage limit. Depending on carbon pore size and topology we predicted monotonic decreasing and non-monotonic shape of the D{sub 2}/H{sub 2} equilibrium selectivity at finite pressures. For both kinds of carbonaceous pores of molecular sizes we predict high compression of hydrogen isotopes at 77 and 33 K (for example, the pore density of compressed hydrogen isotopes at 77 K and 0.25 MPa in a square-shaped carbon pore of size 2.6 A exceeds 60 mmol cm{sup -3}; for comparison, the liquid density of para-H{sub 2} at 30 K and 30 MPa is 42 mmol cm{sup -3}). Finally, by direct comparison of simulation results with experimental data it is explained why 'ordinary' carbonaceous materials are not efficient quantum sieves.

  20. Impact of the carbon pore size and topology on the equilibrium quantum sieving of hydrogen isotopes at zero coverage and finite pressures.

    Science.gov (United States)

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester

    2009-04-08

    Carbonaceous slit-shaped and square-shaped pores efficiently differentiate adsorbed hydrogen isotopes at 77 and 33 K. Extensive path integral Monte Carlo simulations revealed that the square-shaped carbon pores enhanced the selectivity of deuterium over hydrogen in comparison to equivalent slit-shaped carbon pores at zero coverage as well as at finite pressures (i.e. quantum sieving of hydrogen isotopes is pore-topology-dependent). We show that this enhancement of the D(2)/H(2) equilibrium selectivity results from larger localization of hydrogen isotopes in square-shaped pores. The operating pressures for efficient quantum sieving of hydrogen isotopes are strongly dependent on the topology as well as on the size of the carbon pores. However, for both considered carbon pore topologies the highest D(2)/H(2) separation factor is observed at zero-coverage limit. Depending on carbon pore size and topology we predicted monotonic decreasing and non-monotonic shape of the D(2)/H(2) equilibrium selectivity at finite pressures. For both kinds of carbonaceous pores of molecular sizes we predict high compression of hydrogen isotopes at 77 and 33 K (for example, the pore density of compressed hydrogen isotopes at 77 K and 0.25 MPa in a square-shaped carbon pore of size 2.6 Å exceeds 60 mmol cm(-3); for comparison, the liquid density of para-H(2) at 30 K and 30 MPa is 42 mmol cm(-3)). Finally, by direct comparison of simulation results with experimental data it is explained why 'ordinary' carbonaceous materials are not efficient quantum sieves.

  1. The effects of hydrogen addition on Fenimore NO formation in low-pressure, fuel-rich-premixed, burner-stabilized CH4/O-2/N-2 flames

    NARCIS (Netherlands)

    Sepman, A. V.; van Essen, V. M.; Mokhov, A. V.; Levinsky, H. B.

    2008-01-01

    We investigate the effects of hydrogen addition on Fenimore NO formation in fuel-rich, low-pressure burner-stabilized CH4/O-2/N-2 flames. Towards this end, axial profiles of temperature and mole fractions of CH and NO are measured using laser-induced fluorescence (LIF). The experiments are performed

  2. The sticking probability for H-2 in presence of CO on some transition metals at a hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2008-01-01

    The sticking probability for H-2 on Ni, Co, Cu, Rh, Ru, Pd, it and Pt metal films supported on graphite has been investigated in a gas mixture consisting of 10 ppm carbon monoxide in hydrogen at a total pressure of 1 bar in the temperature range 40-200 degrees C. Carbon monoxide inhibits...

  3. A three-site Langmuir adsorption model to elucidate the temperature, pressure, and support dependence of the hydrogen coverage on supported Pt particles

    NARCIS (Netherlands)

    Ji, Y.; Koot, V.; van der Eerden, A.M.J.; Weckhuysen, B.M.; Koningsberger, D.C.; Ramaker, D.E.

    2007-01-01

    The three-site adsorption model, previously developed to describe H adsorption on small Pt particles, was used to gain insight into dependence of hydrogen coverage on temperature, pressure, and support ionicity. The three sites, in order of decreasing PtH bond strength, involve H in an atop, a

  4. Hydrogen/Air Fuel Nozzle Emissions Experiments

    Science.gov (United States)

    Smith, Timothy D.

    2001-01-01

    The use of hydrogen combustion for aircraft gas turbine engines provides significant opportunities to reduce harmful exhaust emissions. Hydrogen has many advantages (no CO2 production, high reaction rates, high heating value, and future availability), along with some disadvantages (high current cost of production and storage, high volume per BTU, and an unknown safety profile when in wide use). One of the primary reasons for switching to hydrogen is the elimination of CO2 emissions. Also, with hydrogen, design challenges such as fuel coking in the fuel nozzle and particulate emissions are no longer an issue. However, because it takes place at high temperatures, hydrogen-air combustion can still produce significant levels of NOx emissions. Much of the current research into conventional hydrocarbon-fueled aircraft gas turbine combustors is focused on NOx reduction methods. The Zero CO2 Emission Technology (ZCET) hydrogen combustion project will focus on meeting the Office of Aerospace Technology goal 2 within pillar one for Global Civil Aviation reducing the emissions of future aircraft by a factor of 3 within 10 years and by a factor of 5 within 25 years. Recent advances in hydrocarbon-based gas turbine combustion components have expanded the horizons for fuel nozzle development. Both new fluid designs and manufacturing technologies have led to the development of fuel nozzles that significantly reduce aircraft emissions. The goal of the ZCET program is to mesh the current technology of Lean Direct Injection and rocket injectors to provide quick mixing, low emissions, and high-performance fuel nozzle designs. An experimental program is planned to investigate the fuel nozzle concepts in a flametube test rig. Currently, a hydrogen system is being installed in cell 23 at NASA Glenn Research Center's Research Combustion Laboratory. Testing will be conducted on a variety of fuel nozzle concepts up to combustion pressures of 350 psia and inlet air temperatures of 1200 F

  5. Numerical Analysis of the Pressure Drop on a Flow Channel Filled with Catalysts for Nuclear Hydrogen Production System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Kim, C. S.; Kim, M. H.; Kim, Y. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seo, D. U.; Park, G. C. [Seoul National Univ., Seoul (Korea, Republic of)

    2013-10-15

    Designing a process heat exchanger (PHE) is one of the main technical challenges in the development of a nuclear hydrogen production system. The PHE provides an interface between the helium gas and the sulfuric acid gas. The SO3 gas is heated and decomposed into SO2 and O2 in the PHE. For this reason, PHE is also called a sulfur trioxide decomposer. The Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand severe operating conditions. Figure 1 shows the layout of the PHE which has a hybrid form of its flow channel geometry; there is a printed-circuit form on the primary helium side and a plate-fin form on the secondary SO3 side. There are many widespread correlations for the porous media such as the Carman, Ergun, Zhavoronkov et al., Susskind and Becker and Reichelt correlation. In the nuclear field, the KTA correlation was developed for a reactor core design for a high-temperature gas-cooled reactor. In this paper, we discussed a numerical analysis and validation of a pressure drop on a SO3 flow channel filled with various sized catalysts. We discussed a numerical analysis and validation of a pressure drop on a flow channel filled with catalysts in the channel. The results of the pressure drop simulation are compared with the results obtained using well-known empirical correlations. From the comparison results, the validity of the two-dimensional numerical analysis is not shown. The main reason may be due to a discord of the channel geometry and the extreme irregularity in the size of the catalyst. It should be accomplished by comparing its results with the experimental data, yet there are no experimental data available up to now.

  6. Pressurization of a Flightweight, Liquid Hydrogen Tank: Evaporation & Condensation at a Liquid/Vapor Interface

    Science.gov (United States)

    Stewart, Mark E. M.

    2017-01-01

    This paper presents an analysis and simulation of evaporation and condensation at a motionless liquid/vapor interface. A 1-D model equation, emphasizing heat and mass transfer at the interface, is solved in two ways, and incorporated into a subgrid interface model within a CFD simulation. Simulation predictions are compared with experimental data from the CPST Engineering Design Unit tank, a cryogenic fluid management test tank in 1-g. The numerical challenge here is the physics of the liquid/vapor interface; pressurizing the ullage heats it by several degrees, and sets up an interfacial temperature gradient that transfers heat to the liquid phase-the rate limiting step of condensation is heat conducted through the liquid and vapor. This physics occurs in thin thermal layers O(1 mm) on either side of the interface which is resolved by the subgrid interface model. An accommodation coefficient of 1.0 is used in the simulations which is consistent with theory and measurements. This model is predictive of evaporation/condensation rates, that is, there is no parameter tuning.

  7. Anharmonic enhancement of superconductivity in metallic molecular Cmca  -  4 hydrogen at high pressure: a first-principles study.

    Science.gov (United States)

    Borinaga, Miguel; Riego, P; Leonardo, A; Calandra, Matteo; Mauri, Francesco; Bergara, Aitor; Errea, Ion

    2016-12-14

    First-principles calculations based on density-functional theory including anharmonicity within the variational stochastic self-consistent harmonic approximation are applied to understand how the quantum character of the proton affects the candidate metallic molecular Cmca  -  4 structure of hydrogen in the 400-450 GPa pressure range, where metallization of hydrogen is expected to occur. Anharmonic effects, which become crucial due to the zero-point motion, have a large impact on the hydrogen molecules by increasing the intramolecular distance by approximately a 6%. This induces two new electron pockets at the Fermi surface opening new scattering channels for the electron-phonon interaction. Consequently, the electron-phonon coupling constant and the superconducting critical temperature are approximately doubled by anharmonicity and Cmca  -  4 hydrogen becomes a superconductor above 200 K in all the studied pressure range. Contrary to many superconducting hydrides, where anharmoncity tends to lower the superconducting critical temperature, our results show that it can enhance superconductivity in molecular hydrogen.

  8. Autópsia oro-facial em vítimas de desastres em massa

    OpenAIRE

    Ventura, Cláudia Patrícia Moura

    2012-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária A Medicina Dentária Forense representa uma área da Medicina Dentária que visa extrair informações das peças e respetivos tecidos adjacentes e aplicar essas informações no processo de identificação humana. A medicina dentária forense utiliza métodos diferentes, entre eles salientamos a autópsia oro-facial que visa a extração dos ma...

  9. Toracocentese e biópsia pleural Thoracentesis and pleural biopsy

    Directory of Open Access Journals (Sweden)

    Roberta Sales

    2006-08-01

    Full Text Available A toracocentese é o método de escolha para a obtenção de amostras de líquido pleural. Embora seja considerado um procedimento pouco invasivo, é fundamental que a toracocentese obedeça a uma técnica padronizada com a finalidade de aprimorar a chance de diagnóstico e minimizar riscos. A biópsia de pleura tem por objetivo ampliar e complementar a chance de diagnóstico das doenças pleurais, sendo indicada em casos selecionados.Thoracentesis is the method of choice for obtaining samples of pleural fluid. Although it is considered a minimum invasive procedure, it is crucial to follow a standardized technique with the purpose of optimizing the chance of diagnosis and minimizing risks. The pleura biopsy may enlarge and complement the chance of diagnosis of the pleural diseases and is indicated in selected cases.

  10. Toxic myopathies: muscle biopsy features Miopatia tóxica: biópsia muscular

    Directory of Open Access Journals (Sweden)

    Rosana Herminia Scola

    2007-03-01

    Full Text Available Several drugs and toxic substances can cause muscular abnormalities and are frequent causes of acquired myopathies. We present a series of 32 patients, predominance of young adult patients, diagnosed with toxic myopathy. The most common substances inducing myopathy were corticosteroids (56.2% followed by the propoxyphene, neuroleptics, zidovudine and drug-induced hypokalemia. The investigation showed normal serum creatine kinase levels in 65.4%, myopathic pattern of the needle electromyography in 40% and the more frequent histological diagnosis of the muscle biopsy was type 2 fiber atrophy (59.3%. Clinical features, etiology, course of the disease, serum levels of muscular enzymes, electromyographic features and, especially, muscle biopsy features are discussed.Diversos medicamentos e substâncias tóxicas podem causar alterações musculares e são causas freqüentes de miopatia adquirida. Apresentamos uma série de 32 pacientes, predomínio de pacientes adulto jovens, com miopatia tóxica. As substâncias mais relacionadas com a miopatia foram os corticosteróides (56,2% seguidos pelo propoxifeno, neurolépticos, zidovudina e drogas indutoras de hipocalemia. A investigação mostrou níveis normais de creatino quinase sérica em 65,4%, eletromiografia de agulha com padrão miopático em 40% e o mais freqüente diagnóstico histológico da biópsia muscular foi atrofia de fibras do tipo 2 (59,3%. As manifestações clínicas, etiologia, tempo de evolução, nível sérico das enzimas musculares, alterações da eletroneuromiografia e, especialmente, da biópsia muscular são discutidos.

  11. Engineering analyses and design calculations of NASA, Langley Research Center hydrogen-air-vitiated heater with oxygen replenishment

    Science.gov (United States)

    1973-01-01

    The technical basis is presented for the design of the hydrogen-air-vitiated heater. The heater liner is subjected to a maximum thermal environment at a specified condition, where the combustion gas temperature, pressure and flow rate are 5000 F, 750 psia, and 11.0 lb/sec, respectively, and results in a heat flux of the order of 275 BTU/sec-sq ft. Cooling and stress analyses indicate that water is the logical choice for cooling of the combustor liner. A mixing analysis was undertaken to establish a good combination of combustor length and injector configuration. The analysis, using a conservative analytical approach, indicates a combustor length of the order of 5 ft combined with discrete fuel and oxidizer injection at an approximate 2-1/2 inch radial combustor position, and results in uniform combustion products at the heater exit for all specified envelope conditions.

  12. Hydrogen Embrittlement

    Science.gov (United States)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  13. Control of population of excited nitrogen molecules by mixing hydrogen in low pressure discharge; Chisso jun`antei reiki bunshi mitsudo no quenching ni yoru seigyo no kento

    Energy Technology Data Exchange (ETDEWEB)

    Uematsu, K.; Yumoto, M.; Sakai, T. [Musashi Institute of Technology, Tokyo (Japan)

    1998-06-01

    The authors have studied on surface treatment of PTFE by a low pressure discharge. It is deduced that excited nitrogen molecules contribute to introduce polar components on the surface. To confirm the speculation, we tried to change population of metastable nitrogen N2 (A{sup 3}{Sigma}u{sup +}) by quenching precursor N2 (B{sup 3}{pi}g), with hydrogen molecule. The decrease of relaxation time which indicates a change of excited molecule and measured by emission spectroscopy using a time after glow method was obtained. As a result, the relaxation times of N2 (B{sup 3}{pi}g) and N2 (A{sup 3}{Sigma}u{sup +}) decreased to 55% and 20% respectively, when mixing ratio of hydrogen was 3%. It was also deduced that hydrogen atom may take a part in a quenching process of N2 (A{sup 3}{Sigma}u{sup +}). 14 refs., 11 figs., 1 tab.

  14. Neutral interstellar hydrogen in the inner heliosphere under the influence of wavelength-dependent solar radiation pressure

    Science.gov (United States)

    Tarnopolski, S.; Bzowski, M.

    2009-01-01

    Context: With the plethora of detailed results from heliospheric missions such as Ulysses and SOHO and at the advent of the first mission dedicated to in situ studies of neutral heliospheric atoms IBEX, we have entered the era of precision heliospheric studies. Interpretation of these data requires precision modeling, with second-order effects quantitatively taken into account. Aims: We study the influence of the non-flat shape of the solar Lyman-α line on the distribution of neutral interstellar hydrogen in the inner heliosphere and assess the importance of this effect for interpretation of heliospheric in situ measurements. Methods: Based on available data, we (i) constructed a model of evolution for the solar Lyman-α line profile with solar activity; (ii) modified an existing test-particle code used to calculate the distribution of neutral interstellar hydrogen in the inner heliosphere so that it takes the dependence of radiation pressure on radial velocity into account; and (iii) compared results of the old and new version. Results: Discrepancies between the classical and Doppler models appear between ~5 and 3 AU and increase towards the Sun from a few percent to a factor of 1.5 at 1 AU. The classical model overestimates the density everywhere except for a ~60° cone around the downwind direction, where a density deficit appears. The magnitude of the discrepancies appreciably depends on the phase of the solar cycle, but only weakly on the parameters of the gas at the termination shock. For in situ measurements of neutral atoms performed at ~1 AU, like those planned for IBEX, the Doppler correction will need to be taken into account, because the modifications include both the magnitude and direction of the local flux by a few km s-1 and degrees, respectively, which, when unaccounted for, would introduce an error of a few km s-1 and degrees in determination of the magnitude and direction of the bulk velocity vector at the termination shock. Conclusions: The

  15. Atmospheric Pressure Plasma CVD of Amorphous Hydrogenated Silicon Carbonitride (a-SiCN:H) Films Using Triethylsilane and Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan Guruvenket; Steven Andrie; Mark Simon; Kyle W. Johnson; Robert A. Sailer

    2011-10-04

    Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films are synthesized by atmospheric pressure plasma enhanced chemical vapor (AP-PECVD) deposition using the Surfx Atomflow{trademark} 250D APPJ source with triethylsilane (HSiEt{sub 3}, TES) and nitrogen as the precursor and the reactive gases, respectively. The effect of the substrate temperature (T{sub s}) on the growth characteristics and the properties of a-SiCN:H films was evaluated. The properties of the films were investigated via scanning electron microscopy (SEM), atomic force microscopy (AFM) for surface morphological analyses, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) for chemical and compositional analyses; spectroscopic ellipsometry for optical properties and thickness determination and nanoindentation to determine the mechanical properties of the a-SiCN:H films. Films deposited at low T{sub s} depict organic like features, while the films deposited at high T{sub s} depict ceramic like features. FTIR and XPS studies reveal that an increases in T{sub s} helps in the elimination of organic moieties and incorporation of nitrogen in the film. Films deposited at T{sub s} of 425 C have an index of refraction (n) of 1.84 and hardness (H) of 14.8 GPa. A decrease in the deposition rate between T{sub s} of 25 and 250 C and increase in deposition rate between T{sub s} of 250 and 425 C indicate that the growth of a-SiCN:H films at lower T{sub s} are surface reaction controlled, while at high temperatures film growth is mass-transport controlled. Based on the experimental results, a potential route for film growth is proposed.

  16. Oral calcium supplementation ambulatory blood pressure and relation to changes in intracellular ions and sodium-hydrogen exchange.

    Science.gov (United States)

    Pikilidou, Maria I; Befani, Christina D; Sarafidis, Pantelis A; Nilsson, Peter M; Koliakos, George G; Tziolas, Ioannis M; Kazakos, Kiriakos A; Yovos, John G; Lasaridis, Anastasios N

    2009-12-01

    Calcium (Ca2+) supplementation has been shown paradoxically to reduce intracellular Ca2+ and induce vascular relaxation. The aim of the study was to assess 24-h blood pressure (BP) change after Ca2+ supplementation and to investigate its relation to changes in intracellular ions and the activity of the first isoform of sodium-hydrogen exchange (NHE-1) in subjects with hypertension and type 2 diabetes. This parallel, randomized controlled, single-blinded trial, consisted of 31 patients with type 2 diabetes, and hypertension who were allocated to receive 1,500 mg of Ca2+ per day (n = 15) or no treatment (n = 16) for 8 weeks. In the Ca2+ group a decrease of 1.7 +/- 2.7 mm Hg (mean +/- SE) P = 0.52 for mean 24-h systolic BP (SBP) and 2.1 +/- 1.5 mm Hg, P = 0.19 for mean 24-h diastolic BP (DBP) was recorded. Whereas in the control group an increase of 1.4 +/- 2.7 mm Hg, P = 0.59 for mean 24-h SBP and 1.2 +/- 2.8 mm Hg, P = 0.83 for mean 24-h DBP was observed. Intraplatelet Ca2+ decreased whereas intraplatelet magnesium (Mg2+) and erythrocyte K+ increased in the intervention group. Change in mean 24-h SBP in the pooled group correlated with both change in intraplatelet Ca2+ (r = 0.49, P < 0.05) and NHE-1 activity (r = 0.6, P < 0.001). The contribution of intraplatelet Ca2+ was attenuated when both parameters were entered in a multivariate regression model. The present study shows a weak, statistically nonsignificant trend towards association of Ca2+ supplementation on 24-h BP in hypertensive subjects with type 2 diabetes. However, our results indicated an interrelation of [Ca2+]i levels and NHE-1 activity on BP in patients with hypertension and type 2 diabetes.

  17. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg

    2016-01-01

    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  18. Biópsia per-oral do intestino delgado em 150 casos de diferentes enteroparasitoses

    Directory of Open Access Journals (Sweden)

    Norton de Figueiredo

    1967-04-01

    Full Text Available Os autores fazem uma apresentação sumária de alguns tipos de instrumentos utilizados na realização da biópsia duodeno-jejunal através intubação oral, ao mesmo tempo que comentam a importância do método no estudo da patologia intestinal. Em seguida apresentam os resultados de sua experiência empregando 6 diferentes tipos de sondas e mostram os resultados histopatológicos observados em 150 casos de diversas parasitoses intestinais, submetidos a estudo. Entre os resultados chamam a atenção para a presença freqüente da Giardia lamblia, detectada em 16 dos 50 (32% casos desta parasitose, contra 3 dos 27 (11,1% de esquistossomose e apenas 2 dos 108 (1,8% de estrongiloidíase. Relatam também o achado de numerosas leishmânias no córion da mucosa jejunal de um paciente parasitado pela Giardia lamblia, que era portador de Calazar. Apreciam, ainda, o significado de outras alterações, consideradas inespecíficas, sobre as quais aguardam estudos mais completos, para chegar a conclusões mais válidas. Entre estas, merece destaque o achado de atrofia das vilosidades intestinais em 27 pacientes infectados pelo Strongyloides stercoialis tendo que em 5 dêles havia parasitismo exclusivo pelo referido nematóide.

  19. Retratos de autópsias Psicossociais sobre suicídio de idosos em Teresina

    Directory of Open Access Journals (Sweden)

    Selena Mesquita Teixeira Sérvio

    Full Text Available O desígnio da presente pesquisa consiste em analisar os fatores psicossociais que perpassaram o suicídio de idosos em Teresina, por meio de uma investigação retrospectiva dos aspectos da vida do suicida antes do autoextermínio e da reconstituição dos fatores de risco para o suicídio. Trata-se de uma pesquisa de natureza qualitativa, descritiva e exploratória. Foram construídas autópsias psicossociais de cinco casos de suicídios de idosos ocorridos no período de 2004 a 2009. Esse método reúne três tipos de informação: ficha de identificação pessoal e social, genograma e entrevista semi-estruturada. A coleta foi viabilizada pelo relato de cinco sujeitos, familiares e parentes próximos ao idoso. O material obtido passou por três etapas: pré-análise, análise qualitativa e síntese analítica. Desse modo, os principais fatores de risco associados ao suicídio desses idosos foram: depressão, transtornos mentais graves, estigma referente ao envelhecimento, alcoolismo, automutilações, impulsividade, relações afetivas fragilizadas e história de vida marcada por eventos trágicos.

  20. Achados clínicopatológicos na tromboembolia pulmonar: estudo de 24 anos de autópsias

    OpenAIRE

    Bok Yoo,Hugo Hyung; Mendes,Fabiana Guandalini; Alem,Christine Elisabete Rubio; Fabro,Alexandre Todorovic; Corrente,José Eduardo; Queluz,Thais Thomaz

    2004-01-01

    INTRODUÇÃO: Tromboembolia pulmonar (TEP) é ainda uma afecção enigmática em diversos aspectos clínicos e epidemiológicos e frequentemente erroneamente diagnosticada. OBJETIVO: Descrever a prevalência e os achados anatomopatológicos de TEP em uma série de 5261 autópsias realizadas em um hospital universitário de nível terciário, correlacionar estes achados com as doenças de base e verificar a freqüência de suspeita clínica antemortem de TEP. MÉTODO: Revisão dos registros das autópsias consecuti...

  1. É a biópsia incisional útil na classificação dos carcinomas basocelulares?

    OpenAIRE

    Messina,Maria Cristina de Lorenzo; Valente,Neusa Yuriko Sakai; Castro,Luiz Guilherme Martins

    2006-01-01

    FUNDAMENTOS: O carcinoma basocelular é tumor constituído por diferentes tipos histológicos, que demonstram diversificado potencial de agressividade. Sabe-se que a correlação entre os tipos histológicos de carcinoma basocelular encontrados no material de biópsia pré-operatória e no material da peça cirúrgica excisional não é total. Na literatura essa correlação varia de 42,7 a 80%. OBJETIVO: Avaliar a correlação entre os tipos histológicos de carcinoma basocelular nas biópsias incisionais e re...

  2. Biópsia hepática por laparotomia paracostal em bovinos e búfalos

    OpenAIRE

    Minervino,Antonio Humberto Hamad; Barrêto Júnior,Raimundo Alves; Rodrigues,Frederico Augusto Mazzocca Lopes; Ferreira,Rodrigo Nogueira Fernandes; Saut,João Paulo Elsen; Queiroz,Genilson Fernandes; Reis,Leonardo Frasson dos; Ortolani,Enrico Lippi

    2009-01-01

    A técnica de biópsia hepática em ruminantes tem importante valor no diagnóstico clínico de doenças tóxicas e metabólicas, em especial nos desequilíbrios minerais. As técnicas mais comumente utilizadas restringem análises devido ao limitado volume de tecido obtido. No presente trabalho, avaliou-se o uso de uma técnica de biópsia hepática por laparotomia paracostal em bovinos e búfalos. Foram utilizados 10 bovinos e 10 búfalos hígidos. Os animais foram mantidos em estação, sedados com xilazina ...

  3. Present status of investigations of attacks by hydrogen upon non-loaded test pieces, as affected by hydrogen pressure, the duration of the experiment, and the hardening state of the material

    Energy Technology Data Exchange (ETDEWEB)

    1944-04-04

    Tests run before 1940 on resistance of steels to hydrogen attack seemed to indicate that steels containing at least 3% chromium (with or without molybdenum, vanadium, and tungsten) were resistant to attack up to 600/sup 0/C and 700 atm pressure for up to 1000 hours of testing. Hydrogen attack was evaluated by change (reduction) in the value of contraction of the steel. Thus it seemed then that steels such as N6, N8, N9, and N10 could be used in preheater hairpins with no problems. Since ruptures of the steels did occur after all, additional tests were run to take greater measure of the effects of length of exposure of the steels to hydrogen and of hardening procedures used in producing the steel. Those tests showed that hydrogen attack was present, but that it proceeded much more slowly than previously supposed and by unexpected mechanisms, so that even 1000 hours of testing was sometimes not a sufficient testing time. Tests showed that steels should be air-quenched instead of oil-quenched, that they should be annealed at some temperature outside the range 700/sup 0/C to 750/sup 0/C, and that they should have as little as possible of carbides in grain boundaries and carbon dissolved in ferrites. The mechanism of hydrogen attack was reevaluated. Instead of direct attack on carbide within crystalline grains, the mechanism was probably one of attack on carbides at grain boundaries, producing a slow migration of carbon out of the grains to the boundaries (concentration-gradient effect) and leaving a lower carbon concentration in the grains to be compensated for by breakup of carbides in the grains. 4 diagrams.

  4. Effect of storage and LEO cycling on manufacturing technology IPV nickel-hydrogen cells

    Science.gov (United States)

    Smithrick, John J.

    1987-01-01

    Yardney Manufacturing Technology (MANTECH) 50 A-hr space weight individual pressure vessel nickel-hydrogen cells were evaluated. This consisted of investigating: the effect of storage and charge/discharge cycling on cell performance. For the storage test the cells were precharged with hydrogen, by the manufacturer, to a pressure of 14.5 psia. After undergoing activation and acceptance tests, the cells were discharged at C/10 rate (5A) to 0.1 V or less. The terminals were then shorted. The cells were shipped to NASA Lewis Research Center where they were stored at room temperature in the shorted condition for 1 year. After storage, the acceptance tests were repeated at NASA Lewis. A comparison of test results indicate no significant degradation in electrical performance due to 1 year storage. For the cycle life test the regime was a 90 minute low earth orbit at deep depths of discharge (80 and 60 percent). At the 80 percent DOD the three cells failed on the average at cycle 741. Failure for this test was defined to occur when the cell voltage degraded to 1 V prior to completion of the 35 min discharge. The DOD was reduced to 60 percent. The cycle life test was continued.

  5. Effect of hydrogen isotope content on tensile flow behavior of Zr-2.5Nb pressure tube material between 25 and 300 °C

    Energy Technology Data Exchange (ETDEWEB)

    Bind, A.K. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094 (India); Sunil, S. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India); Singh, R.N., E-mail: rnsingh@barc.gov.in [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094 (India)

    2016-08-01

    Tensile properties of autoclaved Zr-2.5Nb pressure tube material containing hydrogen isotope between 5 and 200 wppm were evaluated between 25 and 300 °C using specimens with its axis oriented along longitudinal direction of the tube. Analysis of tensile test results showed that both YS and UTS of this alloy decreased linearly with increasing test temperature. The uniform and total plastic strain decreased marginally with increase in test temperature. At all test temperatures, before necking tensile properties were unaffected by hydrogen isotope concentration whereas hydrogen isotope had clear effect on post-necking tensile properties especially at 25 and 100 °C. Post-necking ductility showed a transition behavior at 25 and 100 °C and it was able to capture the effect of hydride embrittlement in this material. - Highlights: • Tensile properties of Zr-2.5Nb pressure tube alloy were evaluated. • Effect of deuterium content and test temperature were studied. • Pre-necking tensile properties appeared to unaffected by the deuterium content. • Post-necking tensile properties captured the effect of hydride embrittlement.

  6. Standard practice for evaluation of disbonding of bimetallic stainless alloy/steel plate for use in high-pressure, high-temperature refinery hydrogen service

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This practice covers a procedure for the evaluation of disbonding of bimetallic stainless alloy/steel plate for use in refinery high-pressure/high-temperature (HP/HT) gaseous hydrogen service. It includes procedures to (1) produce suitable laboratory test specimens, (2) obtain hydrogen charging conditions in the laboratory that are similar to those found in refinery HP/HT hydrogen gas service for evaluation of bimetallic specimens exposed to these environments, and (3) perform analysis of the test data. The purpose of this practice is to allow for comparison of data among test laboratories on the resistance of bimetallic stainless alloy/steels to hydrogen-induced disbonding (HID). 1.2 This practice applies primarily to bimetallic products fabricated by weld overlay of stainless alloy onto a steel substrate. Most of the information developed using this practice has been obtained for such materials. The procedures described herein, may also be appropriate for evaluation of hot roll bonded, explosive bonded...

  7. Verification of hydrogen isotope separation by pressure swing adsorption process: Successive volume reduction of isotopic gas mixture using SZ-5A column

    Energy Technology Data Exchange (ETDEWEB)

    Kotoh, K., E-mail: kotoh@nucl.kyushu-u.ac.jp [Dept. of Applied Quantum Phys. and Nucl. Eng., Faculty of Eng., Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Tanaka, M. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Takashima, S.; Tsuge, T. [Dept. of Applied Quantum Phys. and Nucl. Eng., Faculty of Eng., Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Asakura, Y.; Uda, T. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Sugiyama, T. [Faculty of Eng., Nagoya University, Furo-cho, Chigusa-ku, Nagoya 464-8601 (Japan)

    2011-12-15

    For the purpose of verifying the applicability of pressure swing adsorption (PSA) process to such as volume reduction of tritiated waste storage, an experimental series was carried out by a PSA apparatus having a zeolite packed column operated at the liquefied nitrogen temperature, where synthetic zeolite 5A was used as a candidate of adsorbents. Experimental results are shown here which were obtained from cyclic operation of isolating a volume of hydrogen decontaminated with its heaver isotope from a mixture of H{sub 2} and D{sub 2} while reducing a volume of this mixture storage. Successive reduction during six cycles is observed in the inventory of this hydrogen mixture in a gas holder. Experimental data are analyzed in order to evaluate the performance of this PSA process operating the hydrogen isotope separation, where several factors are introduced defining efficiencies of decontamination, volumetric reduction, and so on. These factors suggest that the PSA process is available for successive reduction of a tritiated hydrogen storage inventory. A tritium waste management system of PSA process combined with electrolysis is considerable which is aiming at reducing the inventory of tritiated water in storage.

  8. Experimental proof of the existence of a Widom line based on peculiarities of the behavior of hydrogen in nanoporous silicate at -45°C and atmospheric pressure

    Science.gov (United States)

    Bordonskii, G. S.; Gurulev, A. A.

    2017-04-01

    We have experimentally studied the thermal and microwave properties of a nanoporous medium (silica gel) with hydrogen-filled pores. On cooling down to about -45°C at atmospheric pressure, the system exhibited chemical transformations, a first-order phase transition with heat evolution, and a sharp change in the power of microwave radiation at 34 GHz transmitted through a sample. It is concluded that this point on the phase diagram corresponds to a point on the Widom line featuring sharp increase in fluctuations of the entropy and density of supercooled water formed during hydrogen interaction with the surface of pores in silica gel. These results confirm the existence of a second critical point of water, from which the Widom line originates.

  9. Hydrogen separation process

    Science.gov (United States)

    Mundschau, Michael [Longmont, CO; Xie, Xiaobing [Foster City, CA; Evenson, IV, Carl; Grimmer, Paul [Longmont, CO; Wright, Harold [Longmont, CO

    2011-05-24

    A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to a hydrogen separation membrane system comprising a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to an integrated water gas shift/hydrogen separation membrane system wherein the hydrogen separation membrane system comprises a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for pretreating a membrane, comprising: heating the membrane to a desired operating temperature and desired feed pressure in a flow of inert gas for a sufficient time to cause the membrane to mechanically deform; decreasing the feed pressure to approximately ambient pressure; and optionally, flowing an oxidizing agent across the membrane before, during, or after deformation of the membrane. A method of supporting a hydrogen separation membrane system comprising selecting a hydrogen separation membrane system comprising one or more catalyst outer layers deposited on a hydrogen transport membrane layer and sealing the hydrogen separation membrane system to a porous support.

  10. Performance of a hydrogen burner to simulate air entering scramjet combustors. [simulation of total temperature, total pressure, and volume fraction of oxygen of air at flight conditions

    Science.gov (United States)

    Russin, W. R.

    1974-01-01

    Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.

  11. Magnesium for Hydrogen Storage

    DEFF Research Database (Denmark)

    Vigeholm, B.; Kjøller, John; Larsen, Bent

    1980-01-01

    The reaction of hydrogen with commercially pure magnesium powder (above 99.7%) was investigated in the temperature range 250–400 °C. Hydrogen is readily sorbed above the dissociation pressure. During the initial exposure the magnesium powder sorbs hydrogen slowly below 400 °C but during the second...

  12. Performance of carbon-based hot frit substrates. 2, Coating performance studies in hydrogen at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, R.; Vanier, P.; Adams, J.; Svandrlik, J.; Powell, J.R.

    1993-07-01

    Erosion tests were conducted on coated graphite and 2D, 3D carbon- carbons in 1 atm hydrogen at high temperatures. Refractory NbC, TaC coatings were used. It was found that the most effective combination of coating and substrate was TaC deposited by chemical vapor reaction method on AXF-5QI graphite.

  13. Hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Donath, E.

    1942-10-16

    This report mentioned that not very severe demands for purity were made on the hydrogen used in hydrogenation of coal or similar raw materials, because the catalysts were not very sensitive to poisoning. However, the hydrogenation plants tried to remove most impurities anyway by means of oil washes. The report included a table giving the amount of wash oil used up and the amount of hydrogen lost by dissolving into the wash oil used up and the amount of hydrogen lost by dissolving into the wash oil in order to remove 1% of various impurities from 1000 m/sup 3/ of the circulating gas. The amounts of wash oil used up were 1.1 m/sup 3/ for removing 1% nitrogen, 0.3 m/sup 3/ for 1% carbon monoxide, 0.03 m/sup 3/ for 1% methane. The amount of hydrogen lost was 28 m/sup 3/ for 1% nitrogen, 9 m/sup 3/ for 1% methane and ranged from 9 m/sup 3/ to 39 m/sup 3/ for 1% carbon monoxide and 1 m/sup 3/ to 41 m/sup 3/ for carbon dioxide depending on whether the removal was done in liquid phase or vapor phase and with or without reduction of the oxide to methane. Next the report listed and described the major processes used in German hydrogenation plants to produce hydrogen. Most of them produced water gas, which then had its carbon monoxide changed to carbon dioxide, and the carbon oxides washed out with water under pressure and copper hydroxide solution. The methods included the Winkler, Pintsch-Hillebrand, and Schmalfeldt-Wintershall processes, as well as roasting of coke in a rotating generator, splitting of gases formed during hydrogenation, and separation of cokery gas into its components by the Linde process.

  14. Study of high-pressure hydrogen-operated wire chambers designed for a precision measurement of the singlet mu p capture rate

    CERN Document Server

    Maev, E M; Case, T A; Crowe, K M; Dick, P U; Dijksman, A; Egger, J; Fetisov, A A; Ganzha, V A; Herold, W D; Hartmann, F J; Kammel, P; Krivchitch, A G; Maev, O E; Petitjean, C; Petrov, G E; Prieels, R; Sadetsky, S M; Schapkin, G N; Schmidt, R; Semenchuk, G G; Soroka, M; Vorobyov, A A; Voropaev, N I

    2002-01-01

    This work was carried out as part of a project aiming at a greatly improved measurement of the muon capture rate from the singlet state of the mu p atom. The experiment will be performed at the intense muon beam of PSI using a new experimental method allowing high precision measurements of the lifetime of muons stopped in ultra-pure deuterium-depleted hydrogen (protium). The basic element of the detector is a time projection chamber operating in hydrogen gas at 10 bar pressure. The arrival times and trajectories of the incoming muons and the outgoing decay electrons are measured with this device providing effective suppression of background. The system of chambers and electronics is designed for the large muon stop rates required for attaining high statistical accuracy. During four beam periods at PSI, data were taken. Also, various studies of the MWPC performance in hydrogen were made including ageing studies of the chambers under irradiation with stopped muons and with alpha and beta sources. It was demonst...

  15. Hydrogen no-vent fill testing in a 1.2 cubic foot (34 liter) tank

    Science.gov (United States)

    Moran, Matthew E.; Nyland, Ted W.; Driscoll, Susan L.

    1991-01-01

    Experimental results of no-vent fill testing with liquid hydrogen in a 1.2 cubic foot (34 liter) stainless steel tank are presented. More than 40 tests were performed with various liquid inlet temperatures, inlet flowrates, initial tank wall temperatures, and liquid injection techniques. Fill levels equal to or exceeding 90 percent by volume were achieved in 40 percent of the tests with the tank pressure limited to a maximum of 30 psia. Three liquid injection techniques were employed; top spray, upward pipe discharge, and bottom diffuser. Effects of each of the varied parameters on the tank pressure history and final fill level are evaluated. The final fill level is found to be indirectly proportional to the initial wall and inlet liquid temperatures and directly proportional to the inlet liquid flowrate. Furthermore, the top spray is the most efficient no-vent fill method of the three configurations examined. The success of this injection method is primarily due to condensation of the ullage vapor onto the incoming liquid droplets. Ullage condensation counteracts the tank pressure rise resulting from energy exchange between the fluid and the warmer tank walls, and ullage compression. Upward pipe discharge from the tank bottom is the next most efficient method. Fluid circulation induced by this fill configuration tends to diminish thermal stratification in the bulk liquid, thus enhancing condensation at the liquid gas interface.

  16. Freqüência de Candida sp. em biópsias de lesões da mucosa bucal

    Directory of Open Access Journals (Sweden)

    Spolidorio Luís Carlos

    2003-01-01

    Full Text Available O objetivo desse trabalho foi determinar a freqüência da infecção por Candida sp. em biópsias de lesões da mucosa bucal, assim como associar a presença de Candida sp. com lesões malignas e lesões com vários graus de displasia. Foram utilizadas 832 biópsias da mucosa bucal, previamente incluídas em parafinas, cujos blocos foram obtidos dos arquivos da Disciplina de Patologia da Faculdade de Odontologia de Araraquara da UNESP, no período entre 1990-2001. Três cortes seqüenciais foram corados pelo ácido periódico de Schiff (PAS. Do total de biópsias 27,2% foram PAS positivas, dessas 83,25% eram provenientes de pacientes do sexo masculino. Houve associação positiva entre infecção com displasia epitelial leve, moderada, severa, carcinoma espinocelular e hiperqueratose (p < 0,05. Não houve associação entre hiperplasia fibrosa inflamatória, líquen plano, granuloma piogênico (p < 0,05 com infecções fúngicas. A língua foi o sítio mais acometido por infecções em relação a outros sítios (p < 0,05. A partir dos dados quantitativos, concluiu-se que houve correlação positiva de infecção por fungos, lesões displásicas e carcinoma, sendo mais freqüente no sexo masculino. Estes dados não permitem inferir se o fungo causa displasia epitelial e carcinoma, mas confirmam a maior presença de Candida nessas lesões.

  17. Hazards assessment and technical actions due to the production of pressured hydrogen within a pilot photovoltaic-electrolyser-fuel cell power system for agricultural equipment

    Directory of Open Access Journals (Sweden)

    Simone Pascuzzi

    2016-06-01

    Full Text Available A pilot power system formed by photovoltaic panels, alkaline electrolyser and fuel cell stacks was designed and set up to supply the heating system of an experimental greenhouse. The aim of this paper is to analyse the main safety aspects of this power system connected to the management of the pressured hydrogen, such as the explosion limits of the mixture hydrogen-oxygen, the extension of the danger zone, the protection pressure vessels and the system to make unreactive the plant. The electrolyser unit is the core of this plant and from the safety point of view has been equipped with devices able to highlight the malfunctions before they cause damages. Alarm situations are highlighted and the production process is cut off in safe conditions in the event that the operational parameters have an abnormal deviation from the design values. Also the entire power system has been designed so that any failure to its components does not compromise the workers’ safety even if the risk analysis is in progress because technical operations are being carried out for enhancing the plant functionality, making it more suitable to the designed task of supplying electrically the greenhouse heating system during cold periods. Some experimental data pertinent to the solar radiation and the corresponding hydrogen production rate are also reported. At present it does not exist a well-established safety reference protocol to design the reliability of these types of power plants and then the assumed safety measures even if related to the achieved pilot installation, can represent an original base of reference to set up guidelines for designing the safety of power plants in the future available for agricultural purposes.

  18. Hydrogen water intake via tube-feeding for patients with pressure ulcer and its reconstructive effects on normal human skin cells in vitro.

    Science.gov (United States)

    Li, Qiang; Kato, Shinya; Matsuoka, Daigo; Tanaka, Hiroshi; Miwa, Nobuhiko

    2013-09-10

    Pressure ulcer (PU) is common in immobile elderly patients, and there are some research works to investigate a preventive and curative method, but not to find sufficient effectiveness. The aim of this study is to clarify the clinical effectiveness on wound healing in patients with PU by hydrogen-dissolved water (HW) intake via tube-feeding (TF). Furthermore, normal human dermal fibroblasts OUMS-36 and normal human epidermis-derived cell line HaCaT keratinocytes were examined in vitro to explore the mechanisms relating to whether hydrogen plays a role in wound-healing at the cellular level. Twenty-two severely hospitalized elderly Japanese patients with PU were recruited in the present study, and their ages ranged from 71.0 to 101.0 (86.7 ± 8.2) years old, 12 male and 10 female patients, all suffering from eating disorder and bedridden syndrome as the secondary results of various underlying diseases. All patients received routine care treatments for PU in combination with HW intake via TF for 600 mL per day, in place of partial moisture replenishment. On the other hand, HW was prepared with a hydrogen-bubbling apparatus which produces HW with 0.8-1.3 ppm of dissolved hydrogen concentration (DH) and -602 mV to -583 mV of oxidation-reduction potential (ORP), in contrast to reversed osmotic ultra-pure water (RW), as the reference, with DH of size represented statistically significant difference versus before HW intake (p size reduction and early recovery, which potently ensue from either type-I collagen construction in dermal fibroblasts or the promoted mitochondrial reducing ability and ROS repression in epidermal keratinocytes as shown by immunostain or NBT and WST-1 assays, respectively.

  19. Synthesis of amorphous hydrogenated carbon thin films by magnetized radio-frequency discharge in argon–acetylene mixture at very low gas pressure

    Energy Technology Data Exchange (ETDEWEB)

    Hamdan, Ahmad, E-mail: ahmad.ba.hamdan@gmail.com; Al Makdessi, Georges; Margot, Joëlle

    2016-01-29

    This paper presents a characterization study of carbon thin films grown on crystalline silicon substrates using a magnetized high-frequency discharge in argon–acetylene mixture at very low pressure. Thin films with different morphological structure are obtained. Depending on the gas pressure, acetylene percentage and process time, it is possible to categorize the surface film morphology into three categories: smooth, cracked or microstructured. Moreover, when applying external magnetic field, it has been observed that depending on the substrate direction (perpendicular or parallel) to the reactor axis, it is possible to obtain different film morphologies. For specific conditions, energetic argon ions are formed which lead to film surface damaging and to their inclusion when they impinge the film surface. Chemical pathways and most likely isomers that contribute to the growth are also identified and discussed. Synthesizing materials in such low pressure conditions is of particular interest for better understanding the complex phenomena taking place in the plasma such as instabilities induced by particles and infra-red spectra of carbonaceous interstellar dust. - Highlights: • Deposition of amorphous hydrogenated carbon by magnetized RF-discharge • Modifying the film morphology by changing the pressure and the C{sub 2}H{sub 2} percentage • Studying the effect of the magnetic field on the film structure.

  20. CFD Modeling of the Multipurpose Hydrogen Test Bed (MHTB) Self-Pressurization and Spray Bar Mixing Experiments in Normal Gravity: Effect of the Accommodation Coefficient on the Tank Pressure

    Science.gov (United States)

    Kartuzova, Olga; Kassemi, Mohammad

    2015-01-01

    A CFD model for simulating the self-pressurization of a large scale liquid hydrogen storage tank is utilized in this paper to model the MHTB self-pressurization experiment. The kinetics-based Schrage equation is used to account for the evaporative and condensi ng interfacial mass flows in this model. The effect of the accommodation coefficient for calculating the interfacial mass transfer rate on the tank pressure during tank selfpressurization is studied. The values of the accommodation coefficient which were considered in this study vary from 1.0e-3 to 1.0e-1 for the explicit VOF model and from 1.0e-4 to 1.0e-3 for the implicit VOF model. The ullage pressure evolutions are compared against experimental data. A CFD model for controlling pressure in cryogenic storage tanks by spraying cold liquid into the ullage is also presented. The Euler-Lagrange approach is utilized for tracking the spray droplets and for modeling the interaction between the droplets and the continuous phase (ullage). The spray model is coupled with the VOF model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. Droplet-ullage heat and mass transfer are modeled. The flow, temperature, and interfacial mass flux, as well as droplets trajectories, size distribution and temperatures predicted by the model are presented. The ul lage pressure and vapor temperature evolutions are compared with experimental data obtained from the MHTB spray bar mixing experiment. The effect of the accommodation coefficient for calculating the interfacial and droplet mass transfer rates on the tank pressure during mixing of the vapor using spray is studied. The values used for the accommodation coefficient at the interface vary from 1.0e-5 to 1.0e-2. The droplet accommodation coefficient values vary from 2.0e-6 to 1.0e-4.

  1. High-Pressure Raman and Calorimetry Studies of Vanadium(III) Alkyl Hydrides for Kubas-Type Hydrogen Storage.

    Science.gov (United States)

    Morris, Leah; Trudeau, Michel L; Reed, Daniel; Book, David; Antonelli, David M

    2016-03-16

    Reversible hydrogen storage under ambient conditions has been identified as a major bottleneck in enabling a future hydrogen economy. Herein, we report an amorphous vanadium(III) alkyl hydride gel that binds hydrogen through the Kubas interaction. The material possesses a gravimetric adsorption capacity of 5.42 wt % H2 at 120 bar and 298 K reversibly at saturation with no loss of capacity after ten cycles. This corresponds to a volumetric capacity of 75.4 kgH2  m(-3) . Raman experiments at 100 bar confirm that Kubas binding is involved in the adsorption mechanism. The material possesses an enthalpy of H2 adsorption of +0.52 kJ mol(-1) H2 , as measured directly by calorimetry, and this is practical for use in a vehicles without a complex heat management system. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Biópsia mamária realizada pela técnica de biópsia helicoide: estudo experimental Breast biopsy performed by the helicoid biopsy technique: an experimental study

    Directory of Open Access Journals (Sweden)

    Eliel de Souza

    2010-12-01

    Full Text Available OBJETIVO: avaliar o desempenho da biópsia helicoide na realização de biópsias mamárias. MÉTODOS: foi selecionado aleatoriamente uma amostra composta de 30 pacientes portadoras de câncer de mama submetidas à mastectomia. Foram excluídas as mulheres portadoras de tumor que tivessem consistência pétrea, não-palpável, com manipulação cirúrgica prévia ou que contivesse líquido. Utilizando-se o kit de biópsia helicoide e um equipamento de core biopsy com cânula e agulha de 14 gauge, respectivamente, coletou-se um fragmento por equipamento em área sã e nos tumores, em cada peça cirúrgica, totalizando 120 fragmentos para estudo histológico. Para a análise dos dados, definiu-se um nível de confiança de 95% e utilizou-se o software SPSS, versão 13; o índice de concordância Kappa e o teste paramétrico t de Student. RESULTADOS: a média das idades das pacientes foi de 51,6 anos (±11,1 anos. A core biopsy apresentou sensibilidade de 93,3%, especificidade de 100% e acurácia de 96,7%, enquanto a biópsia helicoide teve sensibilidade de 96,7%, especificidade de 100% e acurácia de 98,3%. Na comparação entre a histologia dos tumores e dos fragmentos de biópsias, houve alto grau de concordância nos diagnósticos (Kappa igual a 0,9, com pPURPOSE: to assess the helicoid biopsy performance when carrying out breast biopsies. METHODS: thirty patients with breast cancer submitted to mastectomy were selected at random. Women with a tumor of petreous consistency, nonpalpable, submitted to previous surgical manipulation or containing fluid were excluded. The helicoid biopsy kit and a core biopsy device with a cannula and a 14-gauge-needle, respectively, were used to collect a fragment each from a healthy area and from the tumor of each surgical specimen, for a total of 120 fragments for histological study. Data were analyzed statistically by the parametric Student's t-test and by the Kappa concordance index at the 95% confidence level

  3. High pressure water electrolysis for space station EMU recharge

    Science.gov (United States)

    Lance, Nick; Puskar, Michael; Moulthrop, Lawrence; Zagaja, John

    1988-01-01

    A high pressure oxygen recharge system (HPORS), is being developed for application on board the Space Station. This electrolytic system can provide oxygen at up to 6000 psia without a mechanical compressor. The Hamilton standard HPORS based on a solid polymer electrolyte system is an extension of the much larger and succesful 3000 psia system of the U.S. Navy. Cell modules have been successfully tested under conditions beyond which spacecraft may encounter during launch. The control system with double redundancy and mechanical backups for all electronically controlled components is designed to ensure a safe shutdown.

  4. Modeling of pressure-induced far-infrared absorption spectra Molecular hydrogen pairs. [in outer planets atmospheres

    Science.gov (United States)

    Borysow, J.; Trafton, L.; Frommhold, L.; Birnbaum, G.

    1985-01-01

    Meyer et al. (1985) have calculated the accurate induced dipole moment function of H2-H2 from first principles, using highly correlated wave functions for the first time in such work. The present paper is concerned with the collision-induced translational-rotational absorption coefficient for molecular hydrogen pairs, taking into account computations on the basis of the fundamental theory considered by Meyer et al. Data have been obtained for temperatures in the range from 40 to 300 K. Criteria are developed for choosing among various model line shapes. It is found that certain models are capable of approximating the quantum profiles closely, with rms errors of only a few percent.

  5. Lattice stability and high-pressure melting mechanism of dense hydrogen up to 1.5 TPa

    KAUST Repository

    Geng, Hua Y.

    2015-09-01

    © 2015 American Physical Society. Lattice stability and metastability, as well as melting, are important features of the physics and chemistry of dense hydrogen. Using ab initio molecular dynamics (AIMD), the classical superheating limit and melting line of metallic hydrogen are investigated up to 1.5 TPa. The computations show that the classical superheating degree is about 100 K, and the classical melting curve becomes flat at a level of 350 K when beyond 500 GPa. This information allows us to estimate the well depth and the potential barriers that must be overcome when the crystal melts. Inclusion of nuclear quantum effects (NQE) using path integral molecular dynamics (PIMD) predicts that both superheating limit and melting temperature are lowered to below room temperature, but the latter never reaches absolute zero. Detailed analysis indicates that the melting is thermally activated, rather than driven by pure zero-point motion (ZPM). This argument was further supported by extensive PIMD simulations, demonstrating the stability of Fddd structure against liquefaction at low temperatures.

  6. Numerical study of threshold intensity dependence on gas pressure in the breakdown of molecular hydrogen induced by excimer laser

    Science.gov (United States)

    Gamal, Yosr E. E.-D.; Nassef, O. Aied

    2017-10-01

    In the present work, a numerical analysis is performed to investigate the threshold intensity dependence on gas pressure in laser spark ignition of the H2 plasma. The analysis considered the experimental measurements that were carried out by Yagi and Huo [Appl. Opt. 35, 3183 (1996)]. In their experiment, H2 in a pressure range of 150-3000 Torr is irradiated by a focused excimer laser source using a 96 cm lens at a wavelength of 248 nm and a pulse duration of 20 ns. The study, based on a modified electron cascade model [K. A. Hamam et al., J. Mod. Phys. 4, 311 (2013)], solves numerically a time-dependent energy equation for the distribution of the electron energy as well as a set of rate equations that describe the change in the formed excited molecule population. This model enabled the determination of the threshold intensity as a function of gas pressure. The validity of the model was tested by comparing the calculated thresholds with the experimentally measured ones. Moreover, the calculation of the electron energy distribution function and its parameters justified the role of the electron gain and loss processes in controlling the value of threshold intensity in relation to the gas pressure. The effect of loss processes on the threshold intensity is also presented.

  7. Characterization of hydrogen absorption during stress corrosion cracking of a 600 alloy in the primary environment of pressurized water reactors (PWR); Caracterisation de l'absorption de l'hydrogene lors de la corrosion sous contrainte (CSC) de l'alliage 600 en milieu primaire des reacteurs a eau pressurisee (REP)

    Energy Technology Data Exchange (ETDEWEB)

    Jambon, F.; Marchetti, L. [CEA Saclay, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, 91 - Gif-sur-Yvette (France); Chene, J. [CEA Saclay, UMR 8587 - Equipe Hydrogene / Materiaux de structure, CEA, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, 91 - Gif-sur-Yvette (France); Jomard, F. [GEMaC, CNRS Meudon, 92 - Meudon (France)

    2010-03-15

    The objective of this study is the understanding of hydrogen transport and absorption phenomena in nickel base materials in the primary type environment of pressurized water reactors (PWR). First, the authors report a literature survey on the role of hydrogen in alloy 600 stress corrosion cracking. This survey enabled experiments to be chosen and applied, the results of which are then discussed. Exposed samples are examined by secondary ion mass spectroscopy

  8. Turbulent and Stable/Unstable Laminar Burning Velocity Measurements from Outwardly Propagating Spherical Hydrogen-Air Flames at Elevated Pressures

    Science.gov (United States)

    Smallbone, Andrew; Tsuneyoshi, Kousaku; Kitagawa, Toshiaki

    The laminar burning velocity of pre-mixed hydrogen-air mixtures was measured in a fan stirred combustion bomb. Unstretched laminar burning velocities and Markstein lengths were obtained at 0.10MPa for equivalence ratios of 0.4, 0.6, 0.8 and 1.0 using high speed flame imaging. The difficulties which arose whilst obtaining similar measurements at 0.25MPa and 0.50MPa are outlined. The turbulent burning velocity was measured at equivalence ratios of 0.4 and 0.8 from explosions carried out at 0.10MPa with turbulence intensities of 0.8 and 1.6m/s. Higher turbulent burning velocity ratios were observed for mixtures which yielded lower Markstein lengths in the laminar combustion experiments.

  9. Sum frequency generation vibrational spectroscopy studies of adsorbates on Pt(111): Studies of CO at high pressures and temperatures, coadsorbed with olefins and its role as a poison in ethylene hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Kyle Yi [Univ. of California, Berkeley, CA (United States)

    2000-12-01

    High pressure high temperature CO adsorption and coadsorption with ethylene and propylene on Pt(111) was monitored in situ with infrared-visible sum frequency generation (SFG). At high pressures and high temperatures, CO dissociates on a Pt(111) surface to form carbon. At 400 torr CO pressure and 673K, CO modifies the Pt(111) surface through a carbonyl intermediate, and dissociates to leave carbon on the surface. SFG was used to follow the CO peak evolution from monolayer adsorption in ultra high vacuum (UHV) to 400 torr CO pressure. At this high pressure, a temperature dependence study from room temperature to 823K was carried out. Auger electron spectroscopy was used to identify carbon on the surface CO coadsorption with ethylene and CO coadsorption with propylene studies were carried out with 2-IR 1-visible SFG. With this setup, two spectral ranges covering the C-H stretch range and the CO stretch range can be monitored simultaneously. The coadsorption study with ethylene reveals that after 5L ethylene exposure on a Pt(111) surface to form ethylidyne , CO at high pressures cannot completely displace the ethylidyne from the surface. Instead, CO first adsorbs on defect sites at low pressures and then competes with ethylidyne for terrace sites at high pressures. Propylene coadsorption with CO at similar conditions shows that propylidyne undergoes conformation changes with increased CO pressure and at 1 torr, is absent from the Pt(111) surface. Experiments on CO poisoning of ethylene hydrogenation was carried by 2-IR 1-visible SFG. At 1 torr CO,10 torr ethylene and 100 torr hydrogen, CO was found to block active sites necessary for ethylene hydrogenation, Above 425K, CO desorbs from the surface to allow ethylene hydrogenation to occur. The gas phase species were monitored by gas chromatography.

  10. Hydrogen transport membranes

    Science.gov (United States)

    Mundschau, Michael V.

    2005-05-31

    Composite hydrogen transport membranes, which are used for extraction of hydrogen from gas mixtures are provided. Methods are described for supporting metals and metal alloys which have high hydrogen permeability, but which are either too thin to be self supporting, too weak to resist differential pressures across the membrane, or which become embrittled by hydrogen. Support materials are chosen to be lattice matched to the metals and metal alloys. Preferred metals with high permeability for hydrogen include vanadium, niobium, tantalum, zirconium, palladium, and alloys thereof. Hydrogen-permeable membranes include those in which the pores of a porous support matrix are blocked by hydrogen-permeable metals and metal alloys, those in which the pores of a porous metal matrix are blocked with materials which make the membrane impervious to gases other than hydrogen, and cermets fabricated by sintering powders of metals with powders of lattice-matched ceramic.

  11. Hydrogen bond effects on compressional behavior of isotypic minerals: high-pressure polymorphism of cristobalite-like Be(OH)2

    Energy Technology Data Exchange (ETDEWEB)

    Shelton, Hannah; Barkley, Madison C.; Downs, Robert T.; Miletich, Ronald; Dera, Przemyslaw

    2016-05-31

    Three isotypic crystals, SiO2 (α-cristobalite), ε-Zn(OH)2 (wülfingite), and Be(OH)2 (β-behoite), with topologically identical frameworks of corner-connected tetrahedra, undergo displacive compression-driven phase transitions at similar pressures (1.5–2.0 GPa), but each transition is characterized by a different mechanism resulting in different structural modifications. In this study, we report the crystal structure of the high-pressure γ-phase of beryllium hydroxide and compare it with the high-pressure structures of the other two minerals. In Be(OH)2, the transition from the ambient β-behoite phase with the orthorhombic space group P212121 and ambient unit cell parameters a = 4.5403(4) Å, b = 4.6253(5) Å, c = 7.0599(7) Å, to the high-pressure orthorhombic γ-polymorph with space group Fdd2 and unit cell parameters (at 5.3(1) GPa) a = 5.738(2) Å, b = 6.260(3) Å, c = 7.200(4) Å takes place between 1.7 and 3.6 GPa. This transition is essentially second order, is accompanied by a negligible volume discontinuity, and exhibits both displacive and reversible character. The mechanism of the phase transition results in a change to the hydrogen bond connectivities and rotation of the BeO4 tetrahedra.

  12. Hydrogen CARS thermometry in H2-N2 mixtures at high pressure and medium temperatures: influence of linewidths models

    Science.gov (United States)

    Hussong, J.; Stricker, W.; Bruet, X.; Joubert, P.; Bonamy, J.; Robert, D.; Michaut, X.; Gabard, T.; Berger, H.

    In order to improve the accuracy of H2 CARS thermometry, H2 Q-branch CARS spectra have been recorded for various H2-N2 mixtures in a high-pressure cell at different pressures and temperatures (up to 40 bar and 875 K). Due to the low spectral resolution of broadband CARS experiments, the relevant spectral lineshape factor is the linewidth ratio Γ(Q(3))/Γ(Q(1)), since Q(1) and Q(3) are the most intense lines of the Q-branch spectrum in this temperature range. For the first time, the speed-inhomogeneous effects are accounted for in the simulation of the CARS profiles. The evaluated temperatures are in good agreement with reference values obtained by thermocouples. The specific role on the accuracy of H2 CARS thermometry of the speed inhomogeneity is carefully analyzed, in connection with the influence of the nitrogen concentration.

  13. Experimental Demonstration of Advanced Palladium Membrane Separators for Central High Purity Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Sean Emerson; Neal Magdefrau; Susanne Opalka; Ying She; Catherine Thibaud-Erkey; Thoman Vanderspurt; Rhonda Willigan

    2010-06-30

    The overall objectives for this project were to: (1) confirm the high stability and resistance of a PdCu trimetallic alloy to carbon and carbide formation and, in addition, resistance to sulfur, halides, and ammonia; (2) develop a sulfur, halide, and ammonia resistant alloy membrane with a projected hydrogen permeance of 25 m{sup 3}m{sup -2}atm{sup -0.5}h{sup -1} at 400 C and capable of operating at pressures of 12.1 MPa ({approx}120 atm, 1750 psia); and (3) construct and experimentally validate the performance of 0.1 kg/day H{sup 2} PdCu trimetallic alloy membrane separators at feed pressures of 2 MPa (290 psia) in the presence of H{sub 2}S, NH{sub 3}, and HCl. This project successfully increased the technology readiness level of palladium-based metallic membranes for hydrogen separation from coal-biomass gasifier exhaust or similar hydrogen-containing gas streams. The reversible tolerance of palladium-copper (PdCu) alloys was demonstrated for H{sub 2}S concentrations varying from 20 ppmv up to 487 ppmv and NH{sub 3} concentrations up to 9 ppmv. In addition, atomistic modeling validated the resistance of PdCu alloys to carbon formation, irreversible sulfur corrosion, and chlorine attack. The experimental program highlighted two key issues which must be addressed as part of future experimental programs: (1) tube defects and (2) non-membrane materials of construction. Four out of five FCC PdCu separators developed leaks during the course of the experimental program because {approx}10% of the alloy tubes contained a single defect that resulted in a thin, weak point in the tube walls. These defects limited operation of the existing tubes to less than 220 psig. For commercial applications of a PdCu alloy hydrogen separator under high sulfur concentrations, it was determined that stainless steel 316 is not suitable for housing or supporting the device. Testing with sulfur concentrations of 487 {+-} 4 ppmv resulted in severe corrosion of the stainless steel components of

  14. Influence of preparation method on supported Cu-Ni alloys and their catalytic properties in high pressure CO hydrogenation

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Eriksen, Winnie L.; Duchstein, Linus Daniel Leonhard

    2014-01-01

    (50 bar CO and 50 bar H2). These alloy catalysts are highly selective (more than 99 mol%) and active for methanol synthesis; however, loss of Ni caused by nickel carbonyl formation is found to be a serious issue. The Ni carbonyl formation should be considered, if Ni-containing catalysts (even...... in alloyed form) are used under conditions with high partial pressure of CO. This journal is © The Royal Society of Chemistry....

  15. Oxygen and hydrogen isotope study of high-pressure metagabbros and metabasalts (Cyclades, Greece): implications for the subduction of oceanic crust

    Science.gov (United States)

    Putlitz, Benita; Matthews, Alan; Valley, John W.

    Oxygen and hydrogen stable isotope ratios of eclogite-facies metagabbros and metabasalts from the Cycladic archipelago (Greece) document the scale and timing of fluid-rock interaction in subducted oceanic crust. Close similarities are found between the isotopic compositions of the high-pressure rocks and their ocean-floor equivalents. High-pressure minerals in metagabbros have low δ18O values: garnet 2.6 to 5.9‰, glaucophane 4.3 to 7.1‰ omphacite 3.5 to 6.2‰. Precursor actinolite that was formed during the hydrothermal alteration of the oceanic crust by seawater analyses at 3.7 to 6.3‰. These compositions are in the range of the δ18O values of unaltered igneous oceanic crust and high-temperature hydrothermally altered oceanic crust. In contrast, high-pressure metabasalts are characterised by 18O-enriched isotopic compositions (garnet 9.2 to 11.5‰, glaucophane 10.6 to 12.5‰, omphacite 10.2 to 12.8‰), which are consistent with the precursor basalts having undergone low-temperature alteration by seawater. D/H ratios of glaucophane and actinolite are also consistent with alteration by seawater. Remarkably constant oxygen isotope fractionations, compatible with isotopic equilibrium, are observed among high-pressure minerals, with Δglaucophane-garnet= 1.37+/-0.24‰ and Δomphacite-garnet=0.72+/-0.24‰. For the estimated metamorphic temperature of 500°C, these fractionations yield coefficients in the equation Δ=A*106/T2 (in Kelvin) of Aglaucophane-garnet= 0.87+/-0.15 and Aomphacite-garnet=0.72+/-0.24. A fractionation of Δglaucophane-actinolite=0.94+/-0.21‰ is measured in metagabbros, and indicates that isotopic equilibrium was established during the metamorphic reaction in which glaucophane formed at the expense of actinolite. The preservation of the isotopic compositions of gabbroic and basaltic oceanic crust and the equilibrium fractionations among minerals shows that high-pressure metamorphism occurred at low water/rock ratios. The isotopic

  16. Biópsia estereotáxica guiada por imagem nas lesões do sistema nervoso central

    Directory of Open Access Journals (Sweden)

    NASSER JOSÉ AUGUSTO

    1998-01-01

    Full Text Available Em 44 biópsias estereotáxicas, guiadas por imagem, no período de agosto-1995 até março-1997, as lesões encontradas foram (ordem de frequência: gliomas (glioblastoma multiforme o mais comum, linfoma primário e demais lesões ligadas à síndrome da imunodeficiência adquirida, metástases, vasculites, cisto aracnóideo, doença de Creutzfeldt-Jakob, nódulo fibroglial calcificado. A idade variou de 1 a 83 anos. 41 lesões eram supratentoriais, 2 infratentoriais e uma da calota craniana. A mortalidade foi nula e a morbidade 2,3%. A literatura é revista. O autores concluem que este procedimento é seguro e eficaz.

  17. Analysis of intermediate pressure SiH4/He capacitively coupled plasma for deposition of an amorphous hydrogenated silicon film in consideration of thermal diffusion effects

    Science.gov (United States)

    Kim, Ho Jun; Lee, Hae June

    2017-08-01

    To achieve rapid, uniform deposition of an amorphous hydrogenated silicon (a-Si:H) film, a capacitively coupled plasma (CCP) is often used at an intermediate pressure (>100 Pa), with a silane (SiH4)-based mixture. At these pressures, heavy particle interactions (such as ion-ion, ion-neutral, and neutral-neutral reactions) contribute significantly to the formation of precursor radicals. By adding a consideration of the thermal diffusion effects to the neutral transport equation, the chemical processes have been numerically analyzed with variation in the number fraction of SiH4 and electrode spacing using a two-dimensional fluid model of radio frequency discharges in a cylindrically symmetric CCP reactor. The non-uniformity of the deposition rate profiles increases consistently as electrode spacing increases, although the non-uniformity of the plasma parameters decreases with the increase of electrode spacing. The simulated deposition rate profiles match well with the experimental data for the change of electrode spacing. Based on the validation of our model, we propose predictive designs to potentially improve the reactor and process by modifying the thermal and electrical surface conditions.

  18. Hydrogen storage methods

    Science.gov (United States)

    Züttel, Andreas

    Hydrogen exhibits the highest heating value per mass of all chemical fuels. Furthermore, hydrogen is regenerative and environmentally friendly. There are two reasons why hydrogen is not the major fuel of today's energy consumption. First of all, hydrogen is just an energy carrier. And, although it is the most abundant element in the universe, it has to be produced, since on earth it only occurs in the form of water and hydrocarbons. This implies that we have to pay for the energy, which results in a difficult economic dilemma because ever since the industrial revolution we have become used to consuming energy for free. The second difficulty with hydrogen as an energy carrier is its low critical temperature of 33 K (i.e. hydrogen is a gas at ambient temperature). For mobile and in many cases also for stationary applications the volumetric and gravimetric density of hydrogen in a storage material is crucial. Hydrogen can be stored using six different methods and phenomena: (1) high-pressure gas cylinders (up to 800 bar), (2) liquid hydrogen in cryogenic tanks (at 21 K), (3) adsorbed hydrogen on materials with a large specific surface area (at Tchemically bonded in covalent and ionic compounds (at ambient pressure), or (6) through oxidation of reactive metals, e.g. Li, Na, Mg, Al, Zn with water. The most common storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa (200 bar). New lightweight composite cylinders have been developed which are able to withstand pressures up to 80 MPa (800 bar) and therefore the hydrogen gas can reach a volumetric density of 36 kg.m-3, approximately half as much as in its liquid state. Liquid hydrogen is stored in cryogenic tanks at 21.2 K and ambient pressure. Due to the low critical temperature of hydrogen (33 K), liquid hydrogen can only be stored in open systems. The volumetric density of liquid hydrogen is 70.8 kg.m-3, and large volumes, where the thermal losses are small, can cause hydrogen to reach a

  19. A importância da biópsia muscular no diagnóstico de neuromiopatias

    Directory of Open Access Journals (Sweden)

    Luiz Fernando Bleggi-Torres P

    1994-09-01

    Full Text Available As doenças neuromusculares têm quadro clínico variado e manifestam-se principalmente em pacientes jovens, determinando incapacidade funcional progressiva. Avaliação clínica, eletromiografia, bioquímica sangüínea e biópsia muscular são indispensáveis para o correto diagnóstico etiológico. Apresentamos casuística de 124 casos diagnosticados por biópsia muscular com histoquímica enzimática, microscopia eletrônica e avaliação morfométrica da variação no diâmetro das fibras afetadas, comentando os principais elementos diagnósticos anátomo-patológicos. Necrose muscular, grande variabilidade no diâmetro de fibras e infiltração adiposa muscular predominam nos quadros miopáticos distróficos, que representaram 26% de nossos casos. Redução volumétrica com angulação das fibras sugeriu origem neurogênica, sendo a alteração importante detectada em 27% de nossos diagnósticos. Miopatia mitocondrial caracteriza-se por acúmulos periféricos de grande quantidade de mitocôndrias com ultraestrutura alterada. Cuidados especiais na escolha e coleta da amostra muscular podem minimizar achados inespecíficos ou alterações tipo estádio terminal que impossibilitam a caracterização adequada da doença.

  20. On the phase between pressure and heat release fluctuations for propane/hydrogen flames and its role in mode transitions

    KAUST Repository

    Hong, Seunghyuck

    2013-12-01

    This paper presents an experimental investigation into mode-transitions observed in a 50-kW, atmospheric pressure, backward-facing step combustor burning lean premixed C3H8/H2 fuel mixtures over a range of equivalence ratios, fuel compositions and preheat temperatures. The combustor exhibits distinct acoustic response and dynamic flame shape (collectively referred to as "dynamic modes") depending on the operating conditions. We simultaneously measure the dynamic pressure and flame chemiluminescence to examine the phase between pressure (p\\') and heat release fluctuations (q\\') in the observed dynamic modes. Results show that the heat release is in phase with the pressure oscillations (θqp≈0) at the onset of a dynamic mode, while as the operating conditions change within the mode, the phase grows until it reaches a critical value θqp=θc, at which the combustor switches to another dynamic mode. According to the classical Rayleigh criterion, this critical phase (θc) should be π/2, whereas our data show that the transition occurs well below this value. A linear acoustic energy balance shows that this critical phase marks the point where acoustic losses across the system boundaries equal the energy addition from the combustion process to the acoustic field. Based on the extended Rayleigh criterion in which the acoustic energy fluxes through the system boundaries as well as the typical Rayleigh source term (p\\'q\\') are included, we derive an extended Rayleigh index defined as Re=θqp/θc, which varies between 0 and 1. This index, plotted against a density-weighted strained consumption speed, indicates that the impact of the operating parameters on the dynamic mode selection of the combustor collapses onto a family of curves, which quantify the state of the combustor within a dynamic mode. At Re=0, the combustor enters a mode, and switches to another as Re approaches 1. The results provide a metric for quantifying the instability margins of fuel

  1. Hydrogen purifier module with membrane support

    Science.gov (United States)

    A hydrogen purifier utilizing a hydrogen-permeable membrane to purify hydrogen from mixed gases containing hydrogen is disclosed. Improved mechanical support for the permeable membrane is described, enabling forward or reverse differential pressurization of the membrane, which further stabilizes the membrane from wrinkling upon hydrogen uptake.

    2012-07-24

    A hydrogen purifier utilizing a hydrogen-permeable membrane to purify hydrogen from mixed gases containing hydrogen is disclosed. Improved mechanical support for the permeable membrane is described, enabling forward or reverse differential pressurization of the membrane, which further stabilizes the membrane from wrinkling upon hydrogen uptake.

  2. Hydrogen Fuelling Stations

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard

    This thesis concerns hydrogen fuelling stations from an overall system perspective. The study investigates thermodynamics and energy consumption of hydrogen fuelling stations for fuelling vehicles for personal transportation. For the study a library concerning the components in a hydrogen fuelling...... station has been developed in Dymola. The models include the fuelling protocol (J2601) for hydrogen vehicles made by Society of Automotive Engineers (SAE) and the thermodynamic property library CoolProp is used for retrieving state point. The components in the hydrogen fuelling library are building up....... A system consisting of one high pressure storage tank is used to investigate the thermodynamics of fuelling a hydrogen vehicle. The results show that the decisive parameter for how the fuelling proceeds is the pressure loss in the vehicle. The single tank fuelling system is compared to a cascade fuelling...

  3. Determination of UO 2(s) dissolution rates in a hydrogen peroxide medium as a function of pressure and temperature

    Science.gov (United States)

    Casas, Ignasi; Borrell, Maria; Sánchez, Laia; de Pablo, Joan; Giménez, Javier; Clarens, Frederic

    2008-03-01

    A continuously stirred flow-through tank reactor has been developed and successfully used to determine rates of dissolution of powdered samples of uranium dioxide at pressure and temperature conditions above the ambient values. The experiments have been performed in a temperature range from 20 to 50 °C and a total hydraulic pressure ranging from 1 to 32 bar. Experiments have been performed in a test solution containing 10 -4 mol/L of H 2O 2, 3 × 10 -3 mol/L of NaHCO 3 and, finally, NaClO 4 to get a constant ionic strength of 0.1 mol/L. An empirical equation has been obtained that describes the results in the experimental range studied and gives a good concordance with values obtained at ambient conditions in other works. On the other hand, scanning electron microscopy (SEM) has shown that the solid surface has homogeneously reacted, and, in addition, no secondary solid phase has been formed on the UO 2 surface.

  4. Pathways to Metallic Hydrogen

    OpenAIRE

    Silvera, Isaac F.; Deemyad, Shanti

    2008-01-01

    The traditional pathway that researchers have used in the goal of producing atomic metallic hydrogen is to compress samples with megabar pressures at low temperature. A number of phases have been observed in solid hydrogen and its isotopes, but all are in the insulating phase. The results of experiment and theory for this pathway are reviewed. In recent years a new pathway has become the focus of this challenge of producing metallic hydrogen, namely a path along the melting line. It has bee...

  5. Metastable ultracondensed hydrogenous materials

    Science.gov (United States)

    Nellis, W. J.

    2017-12-01

    The primary purpose of this paper is to stimulate theoretical predictions of how to retain metastably hydrogenous materials made at high pressure P on release to ambient. Ultracondensed metallic hydrogen has been made at high pressures in the fluid and reported made probably in the solid. Because the long quest for metallic hydrogen is likely to be concluded in the relatively near future, a logical question is whether another research direction, comparable in scale to the quest for metallic H, will arise in high pressure research. One possibility is retention of metastable solid metallic hydrogen and other hydrogenous materials on release of dynamic and static high pressures P to ambient. If hydrogenous materials could be retained metastably on release, those materials would be a new class of materials for scientific investigations and technological applications. This paper is a review of the current situation with the synthesis of metallic hydrogen, potential technological applications of metastable metallic H and other hydrogenous materials at ambient, and general background of published experimental and theoretical work on what has been accomplished with metastable phases in the past and thus what might be accomplished in the future.

  6. Non-Intrusive, Real-Time, On-Line Temperature Sensor for Superheated Hydrogen at High Pressure and High Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The SSC needs a hydrogen temperature sensor that can provide high accuracy, fast response and can be operated on a superheated hydrogen (SHH2) environment. This will...

  7. Achievement report for fiscal 1974 on Sunshine Program. Research and development of hydrogen production technology using high-temperature and high-pressure water electrolysis; 1974 nendo koon koatsusui denkaiho ni yoru suiso seizo gijutsu no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1975-05-30

    The goals at present are to clarify conditions for the realization of the water electrolysis process relative to various primary energy sources and to experimentally construct a small practical electrobath to operate at high temperature and high pressure for the attainment of high economic efficiency. Efforts in this fiscal year are mentioned below. Surveys and studies are conducted about hydrogen production by water electrolysis and about achievements in the past and problems at present concerning hydrogen production by water electrolysis in Japan and overseas. The expected role of water electrolysis in various primary energy sources is also studied and evaluated. For a high-temperature high-pressure water electrolysis bath conceptual design (small test plant, bathing temperature 120 degrees C, pressure 20atm, hydrogen production rate 2Nm{sup 3}/h), studies are conducted about a constant-load type high-temperature high-pressure (bipolar) diaphragm-assisted water electrolysis bath and a variable-load type high-temperature high-pressure diaphragm-assisted water electrolysis bath. Surveys and studies are also conducted about the expected role of water electrolysis in various primary energy sources, and the role is evaluated. (NEDO)

  8. High speed diagnostics for characterization of oxygen / hydrogen rocket injector flowfields

    Science.gov (United States)

    Locke, Justin M.

    Temporally-resolved diagnostics are needed to characterize the highly-turbulent flowfields of rocket engine combustors. Two different high speed diagnostic techniques have been applied successfully to study the combustion and mixing characteristics of single-element shear-coaxial injector flowfield in a rocket combustor. Tunable diode laser absorption spectroscopy (TDLAS) is applied to make in-situ measurements with combusting gas-gas propellants, and high speed imaging incorporating backlighting is applied to combusting and non-combusting liquid-gas and gas-gas propellants. Tunable diode laser absorption spectroscopy has been used to make path-integrated temperature and H2O mole fraction measurements in a gaseous oxygen / gaseous hydrogen uni-element rocket chamber with hot background flow. Four mixture conditions were studied at a nominal chamber pressure of 115 psia. Near infrared diode lasers were utilized to target rovibrational transitions of water vapor, which is created through the combustion processes. Both direct absorption spectroscopy and wavelength modulation spectroscopy with second harmonic normalized by first harmonic (1f-normalized WMS-2 f) techniques were applied, with the harmonic detection technique found to yield the best results. Centerline measurements were made at two axial locations, in the near-injector region and far-field region further downstream. Time-resolved measurements of temperature and H2O mole fraction in the rocket chamber are presented. The TDLAS measurements shows clear differences between the near-injector and downstream measurement locations. Mean path-integrated temperatures and H2O mole fractions in the near-injector region are lower than the downstream measurement location. Fluctuations in path-integrated temperature and H2O mole fraction in the downstream location are significantly greater than the near-injector region. This suggests increased turbulence and larger-scale mixing processes are occurring in the downstream

  9. Investigations in single and multi-component adsorption and desorption of low alkanes in a hydrogen mixture at a carbon adsorbent in view of the rating of alternating pressure systems for hydrogen production. Untersuchungen zur Ein- und Mehrkomponenten- Ad- und Desorption von niedrigen Alkanen im Gemisch mit Wasserstoff an einem Kohlenstoffadsorbens im Hinblick auf die Auslegung von DWA-Anlagen zur Wasserstoffgewinnung

    Energy Technology Data Exchange (ETDEWEB)

    Eichholtz, A.

    1984-07-06

    The investigations relate to the alternating-pressure adsorption and desorption of the pure gases hydrogen, methane, ethane, and propane, as well as of the binary gas mixtures hydrogen-methane, hydrogen-ethane, methane-ethane and ethane-propane at a carbonated molecular sieve. The cycle duration of such an alternating-pressure process and consequently the size of the separating reactors are determined by the component having the lowest adsorption effect during the adsorption phase, respectively by the one requiring the longest desorption time during the desorption phase. Assuming that the entire process of adsorption will be a very fast one, the break-through times of the components to be separated from a gas mixture at the adsorber exit, and thus the maximum possible cycle duration of the entire process, can be previously calculated by means of an equilibrium-zone model. (PW).

  10. Composition and method for hydrogen storage

    Science.gov (United States)

    Mao, Wendy L. (Inventor); Mao, Ho-Kwang (Inventor)

    2004-01-01

    A method for hydrogen storage includes providing water and hydrogen gas to a containment volume, reducing the temperature of the water and hydrogen gas to form a hydrogen clathrate at a first cryogenic temperature and a first pressure and maintaining the hydrogen clathrate at second cryogenic temperature within a temperature range of up to 250 K to effect hydrogen storage. The low-pressure hydrogen hydrate includes H.sub.2 O molecules, H.sub.2 molecules and a unit cell including polyhedron cages of hydrogen-bonded frameworks of the H.sub.2 O molecules built around the H.sub.2 molecules.

  11. Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y−(HF)n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator

    OpenAIRE

    Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

    2017-01-01

    Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF)n. The HF molecules were ionized in the form of complex ions associated with the negative core ions Y− produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y−(HF)n (Y=F, O2), where larger clusters with n≥4 were not dete...

  12. Design and Validation of In-Source Atmospheric Pressure Photoionization Hydrogen/Deuterium Exchange Mass Spectrometry with Continuous Feeding of D2O

    Science.gov (United States)

    Acter, Thamina; Lee, Seulgidaun; Cho, Eunji; Jung, Maeng-Joon; Kim, Sunghwan

    2017-10-01

    In this study, continuous in-source hydrogen/deuterium exchange (HDX) atmospheric pressure photoionization (APPI) mass spectrometry (MS) with continuous feeding of D2O was developed and validated. D2O was continuously fed using a capillary line placed on the center of a metal plate positioned between the UV lamp and nebulizer. The proposed system overcomes the limitations of previously reported APPI HDX-MS approaches where deuterated solvents were premixed with sample solutions before ionization. This is particularly important for APPI because solvent composition can greatly influence ionization efficiency as well as the solubility of analytes. The experimental parameters for APPI HDX-MS with continuous feeding of D2O were optimized, and the optimized conditions were applied for the analysis of nitrogen-, oxygen-, and sulfur-containing compounds. The developed method was also applied for the analysis of the polar fraction of a petroleum sample. Thus, the data presented in this study clearly show that the proposed HDX approach can serve as an effective analytical tool for the structural analysis of complex mixtures. [Figure not available: see fulltext.

  13. Hydrogen storage properties on mechanically milled graphite

    OpenAIRE

    Ichikawa, Takayuki; Chen, D. M.; Isobe, Shigehito; Gomibuchi, Emi; Fujii, Hironobu

    2004-01-01

    We investigated hydrogen absorption/desorption and structural properties in mechanically milled graphite under hydrogen pressures up to 6 MPa to clarify catalytic and hydrogen pressure effects in the milling. The results indicate that a small amount of iron contamination during milling plays a quite important role as a catalyst for hydrogen absorption/desorption properties in graphite. Two-peak structure for hydrogen desorption in the TDS profile is due to existence of two different occupatio...

  14. Tumores do tronco cerebral: estudo anatomopatológico em 35 casos de necrópsia

    Directory of Open Access Journals (Sweden)

    Carmen Lúcia Penteado Lancellotti

    1989-09-01

    Full Text Available Os tumores do tronco cerebral são raros e geralmente tratados sem diagnóstico histopatológico. Sua incidência varia na literatura entre 1,09% e 17,5% dos tumores cerebrais. O objetivo do trabalho foi relatar a casuísti desses tumores em 28500 necrópsias realizadas de 1952 a 1985 no Departamento de Anatomia Patológica da Santa Casa de São Paulo. Enfatizamos os aspectos neuropatológicos, comparamos nossos casos com os de outras séries e salientamos os tumores mais observados nessa região, com a finalidade de procurar contribuir para melhor abordagem terapêutica. Utilizamos alguns dados clínicos e, através do exame anatomopatológico, localizamos o tumor no tronco cerebral sendo o diagnóstico microscópico estabelecido segundo os critérios da Organização Mundial da Saúde. Dos 428 tumores intracranianos observados, 35 estavam localizados no tronco cerebral. Foram aqui incluídos os tumores próprios do tronco cerebral e as metástases e excluídos os tumores que infiltravam o tronco. A maior incidência ocorreu na primeira década e a causa de óbito predominante foi edema cerebral. A localização preferencial foi a ponte e o tumor mais freqüente foi o glioblas-tomia multiforme (19 casos. As metástases ficaram em segundo lugar na freqüência (9 casos, na maioria dos casos de origem pulmonar. Apesar de alguns autores se posicionarem contra a biópsia de tumor nessa região, baseando-se no alto risco cirúrgico, discordamos dessa opinião, pois acreditamos que, frente ao diagnóstico de glioma, será importante a caracterização ou não de malignidade. Ainda, não devemos deixar de considerar os diagnósticos diferenciais de processo expansivo no tronco. Enfim, com o diagnóstico anatomopatológico de glioma ou de uma das possibilidades aventadas, o procedimento terapêutico poderá ser mais adequado.

  15. Muscle biopsy in Pompe disease Biópsia muscular na doença de Pompe

    Directory of Open Access Journals (Sweden)

    Lineu Cesar Werneck

    2013-05-01

    Full Text Available Pompe disease (PD can be diagnosed by measuring alpha-glucosidase levels or by identifying mutations in the gene enzyme. Muscle biopsies can aid diagnosis in doubtful cases. Methods: A review of muscle biopsy from 19 cases of PD (infantile, 6 cases; childhood, 4 cases; and juvenile/adult, 9 cases. Results: Vacuoles with or without glycogen storage were found in 18 cases. All cases had increased acid phosphatase activity. The vacuole frequency varied (almost all fibers in the infantile form to only a few in the juvenile/adult form. Atrophy of type 1 and 2 fibers was frequent in all forms. Atrophic angular fibers in the NADH-tetrazolium reductase and nonspecific esterase activity were observed in 4/9 of the juvenile/adult cases. Conclusion: Increased acid phosphatase activity and vacuoles were the primary findings. Most vacuoles were filled with glycogen, and the adult form of the disease had fewer fibers with vacuoles than the infantile or childhood forms.O diagnóstico da doença de Pompe (PD pode ser feito pela dosagem da enzima alfa-glicosidase ou pela mutação do seu gene codificador. A biópsia muscular pode ajudar em casos duvidosos. Métodos: Revisão das biópsias musculares de 19 casos de PD (forma infantil, 6 casos; infantil tardia, 4; e juvenil/adulto, 9. Resultados: Encontrados vacúolos em 18 casos, com ou sem depósito de glicogênio. Todos mostraram aumento da fosfatase ácida. Os vacúolos estavam presentes na maioria das fibras nas formas infantis, menos frequentes nas formas juvenil e mais raros nas formas do adulto. A atrofia de fibras dos tipos 1 e 2 ocorreram em todas as formas. Fibras atróficas na NADH-tetrazolium redutase e esterase não específica foram observadas em 4/9 das formas infantil tardia/adulta. Conclusões: Os dados mais frequentes foram vacúolos, preenchidos por glicogênio com atividade aumentada da fosfatase ácida. A forma adulta apresenta menor número de vacúolos que as formas infantil e infantil

  16. Doenças renais em pacientes idosos submetidos à biópsia percutânea de rins nativos

    Directory of Open Access Journals (Sweden)

    Claudine Maria Jorge de Oliveira

    2010-12-01

    Full Text Available INTRODUÇÃO: Tem ocorrido aumento da população de idosos e estes vêm envelhecendo em melhores condições clínicas do que no passado. Entretanto, a distribuição e evolução das doenças renais nos idosos ainda são pouco conhecidas, em parte devido à resistência em indicar biópsia renal. OBJETIVO: Avaliar a distribuição, a evolução e as características clínicas das nefropatias diagnosticadas por biópsia em pacientes idosos. PACIENTES E MÉTODOS: Foram avaliadas todas as biópsias renais percutâneas de rins nativos. Elas foram realizadas entre janeiro de 1990 e dezembro de 2006 em 71 pacientes com idade mínima de 60 anos (67,3 ± 6,5 anos, sendo 47 do gênero masculino e 24 do feminino. Os pacientes foram agrupados conforme a indicação clínica da biópsia. RESULTADOS: Síndrome nefrótica foi verificada em 35 pacientes (49,3% associada, na maioria dos casos, à nefropatia membranosa (17 casos, seguida por amiloidose e glomeruloesclerose segmentar e focal com 7 casos cada. Hipótese diagnóstica de injúria renal aguda (IRA, com 19 pacientes, teve como principais diagnósticos a necrose tubular aguda (6 casos e a nefropatia do cilindro (3 casos. Dentre os 19 casos, apenas dois tiveram evolução satisfatória, enquanto os demais morreram precocemente ou evoluíram para doença renal avançada. Doze pacientes biopsiados por hematúria ou proteinúria assintomática tiveram diagnósticos variados, mas a maioria já apresentava nefropatia crônica relevante. Biópsia por síndrome nefrítica ocorreu em 5 casos, também com diagnósticos variados. CONCLUSÕES: Síndrome nefrótica foi a principal indicação de biópsia renal com a nefropatia membranosa como diagnóstico mais frequente. Entre os pacientes com IRA e hematúria ou proteinúria assintomática os diagnósticos foram variados com elevadas taxas de nefropatia crônica avançada.

  17. Discrepâncias clínico-patológicas e achados cardiovasculares em 409 autópsias consecutivas

    Directory of Open Access Journals (Sweden)

    Aline Fusco Fares

    2011-12-01

    Full Text Available FUNDAMENTO: As discrepâncias entre os diagnósticos clínicos e em autópsia persistem em todo o mundo. OBJETIVO: Avaliamos as autópsias em um hospital-escola para analisar a precisão dos diagnósticos cardiovasculares clínicos em comparação aos achados post-mortem. MÉTODOS: As 409 autópsias consecutivas entre 2003 e 2006 foram analisadas em um hospital terciário de São José do Rio Preto, São Paulo (SP, Brasil. A comparação dos achados cardiovasculares clínicos e patológicos foi realizada por meio da classificação de discrepâncias de Goldman. RESULTADOS: A taxa de autópsia no hospital foi de 8%. As causas cardiovasculares de óbito representavam 42,8% (175 de 409 pacientes dos diagnósticos de autópsia. Em 98 pacientes (56%, houve discrepâncias significativas (classes I e II, o que representa uma grande proporção de diagnósticos equivocados de infarto mesentérico (84,6%, infarto agudo do miocárdio (64,7%, dissecção da aorta (64,2% e embolia pulmonar (62,5%. Foram observadas maiores taxas de concordância para a insuficiência cardíaca congestiva (59% e para o acidente vascular cerebral isquêmico agudo (58,8%. A idade, o sexo, o tempo de permanência e a última unidade de admissão no hospital não foram associados aos critérios de Goldman. CONCLUSÃO: As discrepâncias dos diagnósticos clínicos e em autópsia relativos à morte cardiovascular permanecem elevados no Brasil, a despeito dos recursos tecnológicos disponíveis. Além disso, nossos achados reforçam a importância do exame post-mortem como uma contribuição para a melhoria da assistência médica.

  18. Hydrogen fracture toughness tester completion

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Michael J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-09-30

    The Hydrogen Fracture Toughness Tester (HFTT) is a mechanical testing machine designed for conducting fracture mechanics tests on materials in high-pressure hydrogen gas. The tester is needed for evaluating the effects of hydrogen on the cracking properties of tritium reservoir materials. It consists of an Instron Model 8862 Electromechanical Test Frame; an Autoclave Engineering Pressure Vessel, an Electric Potential Drop Crack Length Measurement System, associated computer control and data acquisition systems, and a high-pressure hydrogen gas manifold and handling system.

  19. Making the case for direct hydrogen storage in fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    James, B.D.; Thomas, C.E.; Baum, G.N.; Lomas, F.D. Jr.; Kuhn, I.F. Jr. [Directed Technologies, Inc., Arlington, VA (United States)

    1997-12-31

    Three obstacles to the introduction of direct hydrogen fuel cell vehicles are often states: (1) inadequate onboard hydrogen storage leading to limited vehicle range; (2) lack of an hydrogen infrastructure, and (3) cost of the entire fuel cell system. This paper will address the first point with analysis of the problem/proposed solutions for the remaining two obstacles addressed in other papers. Results of a recent study conducted by Directed Technologies Inc. will be briefly presented. The study, as part of Ford Motor Company/DOE PEM Fuel Cell Program, examines multiple pure hydrogen onboard storage systems on the basis of weight, volume, cost, and complexity. Compressed gas, liquid, carbon adsorption, and metal hydride storage are all examined with compressed hydrogen storage at 5,000 psia being judged the lowest-risk, highest benefit, near-term option. These results are combined with recent fuel cell vehicle drive cycle simulations to estimate the onboard hydrogen storage requirement for full vehicle range (380 miles on the combined Federal driving schedule). The results indicate that a PNGV-like vehicle using powertrain weights and performance realistically available by the 2004 PNGV target data can achieve approximate fuel economy equivalent to 100 mpg on gasoline (100 mpg{sub eq}) and requires storage of approximately 3.6 kg hydrogen for full vehicle storage quantity allows 5,000 psia onboard storage without altering the vehicle exterior lines or appreciably encroaching on the passenger or trunk compartments.

  20. Storage of liquid hydrogen in natural zeolite

    OpenAIRE

    Pavol Rybár; Carsten Drebenstedt; Mário Molokáč; Ladislav Hvizdák; Ľubomír Štrba

    2015-01-01

    When producing and utilizing hydrogen, its storage is one of the biggest problems. Hydrogen, as a gas, is extremely fluid with very low specific weight. Moreover, at a certain rate, the hydrogen-oxygen mixture is explosive. Therefore, the storage of hydrogen is relatively dangerous. A storage of liquid hydrogen in the natural zeolite, which is placed in large capacity battery, appears to be a suitable hydrogen storage method. Proposed and constructed pressure tank, large cap...

  1. Analysis of a weld of an hydrogen tank under pressure: contribution of the nano-indentation for the characterization; Analyse d'une soudure d'un reservoir d'hydrogene sous pression: apport de la nanoindentation pour la caracterisation

    Energy Technology Data Exchange (ETDEWEB)

    Russo, C.; Delobelle, P.; Perreux, D. [Laboratoire de Mecanique Appliquee R. Chaleat (LMARC), Institut FEMTO-ST, UFC and CNRS, 25 - Besancon (France); Russo, C.; Munier, E. [CEA Valduc, 21 - Is-sur-Tille (France); Decamps, B. [Institut de Chimie et des Materiaux Paris-Est vient, CNRS, CMTR-ICMPE, 94 - Thiais (France)

    2007-07-01

    This work deals with the size of an hydrogen spherical tank under pressure, composed of two half shell in aluminium alloy AZ5G machined in a forged bar and welded by electrons beam by a circumference. In this work, it is shown what the nano-indentation test can bring here. The influence of the tempering heat treatment after welding, the grains diameter and the loss in alloy elements (Zn and Mg) on the local mechanical properties of the weld bead has been revealed. In the same way, a hardening of the alloy due to the hydrogen penetration and leading to an increase of the dislocations density is observed. (O.M.)

  2. Informatització i digitalització de casos de necròpsia reals com a base de l'autoaprenentatge en patologia veterinària

    OpenAIRE

    Marco Valle, Alberto

    2008-01-01

    Es descriu breument el procediment pel qual a partir dels casos de necròpsia remesos a un servei de diagnòstic públic de patologia veterinària es programa: 1. Un mòdul de pràctiques de necròpsia amb casos reals. 2. Docència d'autoaprenentatge mitjançant l'elaboració de treballs clinicopatològics basats en «casos reals». 3. Seminaris d'exposició i discussió pública dels casos d'autoaprenentatge presentats pels mateixos estudiants. 4. Creació i manteniment d'una col·lecció dipòsit d'imatges dig...

  3. Alterações da pressão arterial em pacientes submetidos à biópsia na cavidade oral

    OpenAIRE

    Lima, Francisco Jadson; Evangelista, Augusto Pierry de Araújo; Silva, Renata Tôrres Moreira da; Alves, Pollianna Muniz; Lins, Ruthineia Diógenes Alves Uchoa; Godoy, Gustavo Pina

    2016-01-01

    A biópsia é um procedimento simples realizado rotineiramente por cirurgiões-dentistas e médicos, porém gera grande ansiedade e medo nos pacientes envolvidos. O objetivo deste estudo foi analisar a prevalência de alterações na pressão arterial em 63 pacientes submetidos à biópsia da cavidade oral, no período compreendido entre os meses de outubro de 2008 a novembro de 2009. A monitoração da pressão arterial destes pacientes foi realizada através da utilização do esfigmomanômetro durante o exam...

  4. Biópsia pulmonar incisional por toracoscopia paraxifoide transdiafragmática com dois portais em cães Pulmonary incisional biopsy by means of transdiaphragmatic paraxiphoid thoracoscopy with two ports in dog

    Directory of Open Access Journals (Sweden)

    Paula C. Basso

    2010-07-01

    Full Text Available As doenças respiratórias observadas na clínica médica de pequenos animais são numerosas, assim como as possibilidades diagnósticas, dentre as quais encontram-se os exames laboratoriais, os estudos radiográficos, os lavados broncoalveolares e as biópsias. Na presente pesquisa avaliaram-se os resultados da toracoscopia paraxifoide transdiafragmática para a realização de biópsia pulmonar em cães, sendo utilizados para tanto, 13 animais clinicamente sadios. Sob anestesia geral, produziu-se pneumotórax no volume de 30ml kg-1 de ar ambiente para cada hemitórax. O acesso foi obtido a partir de dois trocartes, posicionados entre o apêndice xifoide e o arco costal, os quais transfixaram o diafragma. O primeiro portal foi empregado para a passagem do endoscópio e o segundo para a utilização de pinça saca-bocado, empregada na obtenção de biópsia. Em seguida, a pinça foi removida e um dreno torácico foi posicionado através do portal. Durante os procedimentos, aferiram-se as frequências respiratória e cardíaca, a saturação de oxigênio, as pressões arterial média e venosa central e os parâmetros hemogasométricos. Os drenos foram removidos num período de até 48 horas de pós-operatório, verificando-se mínima produção de ar e/ou líquido. Concluiu-se se tratar de uma técnica rápida, segura e sem complicações trans e pós-operatórias, permitindo aquisição de material suficiente para a avaliação histológica do pulmão.There are many respiratory diseases in small animals, as well as the possibilities of diagnoses, as laboratory and radiographic exams, bronchoalveolar lavage and biopsies. This research aimed at assessing the results of transdiaphragmatic paraxiphoid thoracoscopies in pulmonary biopsies of thirteen clinically healthy dogs. Under general anesthesia, each dog was insufflated with 30ml kg-1 of air in each hemithorax; two trocars were placed between the xiphoid appendix and the costal arch through the

  5. Metallic Hydrogen and Nano-Tube Magnets

    Science.gov (United States)

    Cole, John W.

    2004-01-01

    When hydrogen is subjected to enough pressure the atoms will be pressed into close enough proximity that each electron is no longer bound to a single proton. The research objectives is to find whether metallic hydrogen can be produced and once produced will the metallic hydrogen be metastable and remain in the metallic form when the pressure is released.

  6. Hydrogen in the Methanol Production Process

    Science.gov (United States)

    Kralj, Anita Kovac; Glavic, Peter

    2006-01-01

    Hydrogen is a very important industrial gas in chemical processes. It is very volatile; therefore, it can escape from the process units and its mass balance is not always correct. In many industrial processes where hydrogen is reacted, kinetics are often related to hydrogen pressure. The right thermodynamic properties of hydrogen can be found for…

  7. In-situ experimental characterization of the clamping pressure effects on low temperature polymer electrolyte membrane electrolysis International Journal of Hydrogen Energy

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Cui, Xiaoti; Frensch, Steffen Henrik

    2017-01-01

    The recent acceleration in hydrogen production’s R&D will lead the energy transition. Low temperature polymer electrolyte membrane electrolysis (LT-PEME) is one of the most promising candidate technologies to produce hydrogen from renewable energy sources, and for synthetic fuel production. LT-PE...

  8. Enthalpy measurement of coal-derived liquids. Quarterly technical progress report, April--June 1978. [SRC process distillate; 157 to 675/sup 0/C and 130 to 1000 psia

    Energy Technology Data Exchange (ETDEWEB)

    Kidnay, A.J.; Yesavage, V.F.

    1978-08-01

    Experimental measurements were completed on a middle distillate furnished by Pittsburg and Midway Coal Mining Company. A total of 52 enthalpy measurements were made covering the ranges 157 to 675/sup 0/F and 130 to 1000 psia.

  9. Virtual autopsy in forensic sciences and its applications in the forensic odontology = A autópsia virtual nas ciências forenses e sua aplicação na Odontologia forense

    Directory of Open Access Journals (Sweden)

    Rosário Junior, Ademir Franco do

    2012-01-01

    Full Text Available Atualmente os avanços tecnológicos se fazem cada vez mais importantes nas ciências forenses. Por outro lado a autópsia ainda é uma abordagem tradicional na prática médica-odontológica, na qual evidências são coletadas por meio fotográfico e radiológico. Neste contexto, a Autópsia Virtual surge como uma ferramenta útil e complementar para o exame cadavérico. Através da alta tecnologia radiológica a Autópsia Virtual fornece uma visão eficiente e precisa do caso a ser analisado. Esta revisão crítica tem o objetivo de atualizar os Cirurgiões-dentistas apresentando o primeiro trabalho com o conteúdo voltado a Autópsia Virtual

  10. A novel liquid organic hydrogen carrier system based on catalytic peptide formation and hydrogenation

    OpenAIRE

    Hu, Peng; Fogler, Eran; Diskin-Posner, Yael; Iron, Mark A.; Milstein, David

    2015-01-01

    Hydrogen is an efficient green fuel, but its low energy density when stored under high pressure or cryogenically, and safety issues, presents significant disadvantages; hence finding efficient and safe hydrogen carriers is a major challenge. Of special interest are liquid organic hydrogen carriers (LOHCs), which can be readily loaded and unloaded with considerable amounts of hydrogen. However, disadvantages include high hydrogen pressure requirements, high reaction temperatures for both hydro...

  11. Hydrogen sensor

    Science.gov (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  12. Liquid hydrogen in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Yasumi, S. [Iwatani Corp., Osaka (Japan). Dept. of Overseas Business Development

    2009-07-01

    Japan's Iwatani Corporation has focused its attention on hydrogen as the ultimate energy source in future. Unlike the United States, hydrogen use and delivery in liquid form is extremely limited in the European Union and in Japan. Iwatani Corporation broke through industry stereotypes by creating and building Hydro Edge Co. Ltd., Japan's largest liquid hydrogen plant. It was established in 2006 as a joint venture between Iwatani and Kansai Electric Power Group in Osaka. Hydro Edge is Japan's first combined liquid hydrogen and ASU plant, and is fully operational. Liquid oxygen, liquid nitrogen and liquid argon are separated from air using the cryogenic energy of liquefied natural gas fuel that is used for power generation. Liquid hydrogen is produced efficiently and simultaneously using liquid nitrogen. Approximately 12 times as much hydrogen in liquid form can be transported and supplied as pressurized hydrogen gas. This technology is a significant step forward in the dissemination and expansion of hydrogen in a hydrogen-based economy.

  13. The microbiology behind the biogas process, stressing the regulating role of the hydrogen partial pressure. Mikrobiologien bag biogasprocessen med betoning av hydrogenpartialtrykkets regulerende rolle

    Energy Technology Data Exchange (ETDEWEB)

    Ahring, B. (Danmarks Tekniske Hoejskole, Lyngby (DK). Inst. for Bioteknologi); Westermann, P. (Copenhagen Univ. (DK). Dept. of General Microbiology)

    1989-01-01

    Anaerobic degradation of organic matter involves a complex mixture of bacteria - each with a specific role in the over-all degradation process. Three major metabolic groups of bacteria are involved: The hydrolytic and fermentative bacteria, which convert complex biopolymers, sugars, amino acids, fatty acids and so on to acetate, hydrogen and carbon dioxide on the one hand, and a mixture of alcohols, fatty acids, succinate, and lactate on the other. The latter substrates have to be converted to acetate, hydrogen, and carbon dioxide by the hydrogen-producing acetogenic bacteria, which depend for thermodynamic reasons on efficient removal of their fermentation product. The third group, the methanogenic bacteria, convert acetate, hydrogen, and carbon dioxide as well as the less important one carbon compounds methanol, methylamine, and formate to methane and carbon dioxide. The key regulator of anaerobic fermantations is hydrogen effectuated through interspecies hydrogen transfer. The special feature of this process is that hydrogen-using organisms can create conditions for obligate hydrogen-producing organisms to perform catabolic oxidations which would not have been energy-yielding in the absence of hydrogen removal. The last decade has brought some significant steps forward in our understanding of the anaerobic fermentation process. However, the influence of the ability of micro-organisms to use more than one energy substrate at a time, and to switch their catabolism from breaking carbon-carbon bonds to forming new carbon-carbon bonds, has only been studied to a small extent. Further, knowledge on the anaerobic degradation process is expected to evolve in the nearest future.

  14. Microbial corrosion and cracking in steel. A concept for evaluation of hydrogen-assisted stress corrosion cracking in cathodically protected high-pressure gas transmission pipelines

    DEFF Research Database (Denmark)

    Nielsen, Lars Vendelbo

    An effort has been undertaken in order to develop a concept for evaluation of the risk of hydrogen-assisted cracking in cathodically protected gas transmission pipelines. The effort was divided into the following subtasks: A. Establish a correlation between the fracture mechanical properties...... of high-strength pipeline steel and the concentration of hydrogen present in the steel. B. Determine the degree hydrogen absorption by cathodically protected steel exposed in natural soil sediment, which include activity of sulphate-reducing bacteria (SRB). C. Compare the above points with fracture...

  15. Solid-State Hydrogen Storage Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Availability of a safe, low-pressure, lightweight, compact hydrogen storage system is an enabling technology for hydrogen electric fuel cell usage for space...

  16. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, Ludwig [FuelCell Energy, Inc., Torrington, CT (United States)

    2016-01-21

    Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operation of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).

  17. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  18. Advanced Approaches to Greatly Reduce Hydrogen Gas Crossover Losses in PEM Electrolyzers Operating at High Pressures and Low Current Densities Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ElectroChem proposes a Phase II program to advance its very successful SBIR Phase I technology effort to the point of minimum hydrogen loss through the electrolyzer...

  19. Magnesium for Hydrogen Storage

    DEFF Research Database (Denmark)

    Pedersen, Allan Schrøder; Kjøller, John; Larsen, B.

    1983-01-01

    A study of the hydrogenation characteristics of fine magnesium powder during repeated cycling has been performed using a high-pressure microbalance facility. No effect was found from the cycling regarding kinetics and storage capacity. The reaction rate of the absorption process was fast at tempe......A study of the hydrogenation characteristics of fine magnesium powder during repeated cycling has been performed using a high-pressure microbalance facility. No effect was found from the cycling regarding kinetics and storage capacity. The reaction rate of the absorption process was fast...... at temperatures around 600 K and above, but the reversed reaction showed somewhat slower kinetics around 600 K. At higher temperatures the opposite was found. The enthalpy and entropy change by the hydrogenation, derived from pressure-concentration isotherms, agree fairly well with those reported earlier....

  20. Hydrogen attack - Influence of hydrogen sulfide. [on carbon steel

    Science.gov (United States)

    Eliezer, D.; Nelson, H. G.

    1978-01-01

    An experimental study is conducted on 12.5-mm-thick SAE 1020 steel (plain carbon steel) plate to assess hydrogen attack at room temperature after specimen exposure at 525 C to hydrogen and a blend of hydrogen sulfide and hydrogen at a pressure of 3.5 MN/sq m for exposure times up to 240 hr. The results are discussed in terms of tensile properties, fissure formation, and surface scales. It is shown that hydrogen attack from a high-purity hydrogen environment is severe, with the formation of numerous methane fissures and bubbles along with a significant reduction in the room-temperature tensile yield and ultimate strengths. However, no hydrogen attack is observed in the hydrogen/hydrogen sulfide blend environment, i.e. no fissure or bubble formation occurred and the room-temperature tensile properties remained unchanged. It is suggested that the observed porous discontinuous scale of FeS acts as a barrier to hydrogen entry, thus reducing its effective equilibrium solubility in the iron lattice. Therefore, hydrogen attack should not occur in pressure-vessel steels used in many coal gasification processes.

  1. Fuel Manifold Resists Embrittlement by Hydrogen

    Science.gov (United States)

    Adams, T.

    1986-01-01

    Completely-cast hydrogen-compatible alloy preferable to protective plating. Complexity of plating, welding, and brazing unnecessary if hydrogen-compatible alloy used for entire casting instead of protective overlay. Parts exposed to high-pressure hydrogen made immune to hydrogen embrittlement if fabricated from new alloy, Incoly 903 (or equivalent). Material strong and compatible with hydrogen at all temperatures and adapted for outlet manifold of Space Shuttle main combustion chamber.

  2. Será a insuficiência renal uma contra-indicação relativa para as biópsias broncoscópicas?

    Directory of Open Access Journals (Sweden)

    Nethal I. Metha

    2005-07-01

    Full Text Available Resumo: Em 1977, Cunningham e col. demonstraram que, nos doentes urémicos sujeitos a broncofibroscopia com biopsias, 45% tiveram hemorragias.Actualmente, não há trabalhos publicados que avaliem este risco.Os autores resolveram avaliar os processos de todas as broncofibroscopias realizadas entre 1997 e 2002 no Hospital de Bellvue, Nova Iorque, registando os resultados da ureia, da creatinina, do hemograma, do estudo da coagulação, do tipo de biópsias executadas da pré-medicação e das complicações.Os doentes eram incluídos nos trabalhos desde que tivessem a ureia superior ou igual a 30 mg/dl e/ou a creatinina superior ou igual a 2,0 mg/dl. Perante estes critérios foram incluídos no estudo 72 doentes.Vinte e cinco doentes dos 72(35 % foram submetidos a biopsias. Sete dos 25 (28 % foram hemodializados e 18 dos 25(72 % não foram hemodializados. Todos os doentes hemodializados foram submetidos à broncofibroscopia 24 horas depois da hemodiálise e foram submetidos a uma perfusão de desmopressina pré-broncofibroscopia, e um doente com coagulopatia recebeu plaquetas e plasma fresco.Os doentes hemodializados submetidos a biópsias tinham valores de ureia que oscilavam entre 31-65 mg/ /dl e valores de creatinina que oscilavam entre 5,2-18,7 mg/dl, e o único doente deste grupo que fez punção aspirativa transbrônquica tinha uma ureia de 32 mg/dl e uma creatinina de 4,3 mg/dl.Em doze dos 18 doentes não submetidos a hemodiálise e submetidos a biópsias, os valores de ureia oscilavam entre 20-69 mg/dl e os valores de creatinina entre 0,9-2,5 mg/dl. Deste grupo, os quatro doentes que foram submetidos a punção aspirativa transbrônquica tinham valores de ureia entre 20-62 mg/dl e valores de creatinina entre 1,1-4,5 mg/dl. Os dois doentes sujeitos a biópsias e punção aspirativa transbrônquica tinham valores de ureia de 30 e 35 mg/dl e valores de de 1,4 e 1,5 mg/dl. Um dos 25 doentes não hemodializados teve uma complica

  3. Ash removal by hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Rank, V.; von Hartmann, G.B.

    1942-10-17

    This method for the production of high-quality electrode coke involved the hydrogenation of coal to a filterable bitumen product. The hydrogenation and splitting processes were carried out to end at high-molecular-weight bitumens with some lighter oils produced. Variations in temperature, pressure, and throughput determined the type and amount of bitumens. Proper conditions allowed sufficient middle oil for recirculation as pasting oil as well as for increasing filterability by dilution. This partial hydrogenation could be performed without the addition of hydrogen, if hydrogen-producing aromatic compounds, such as tetraline or cresol, were used as pasting oils. For 700-atm hydrogenation, it was found that the Upper Silesian coal was the best with respect to yield, filterability, and recovery of the recycle oils. The lower pressures gave a better filterability while sacrificing yield and recycle oil. The more severe the hydrogenating conditions, the lighter the bitumens and the lower the melting point. For the range of 300 to 600 atm, it was found that filterability improved with increased temperature and decreased with a pressure gain. Larger throughputs caused relatively moderate decreases in filterability. The use of iron catalysts decreased filterability while changing gas and pasting-oil content had little effect. The optimum conditions established a pasting-oil equilibrium with the best filterability. Greater degrees of hydrogenation or splitting produced more recycle middle oils but decreased filterability, thus only the necessary paste oil was produced. By selecting proper conditions, an ashfree bituminous binder could be produced, as used in the production of the Soederberg electrode. 2 tables, 2 graphs

  4. Morbidade da biópsia da próstata transretal guiada por ultrassonografia Morbidity of transrectal ultrasound guided prostate biopsy

    Directory of Open Access Journals (Sweden)

    Raphael Sandes Solha

    2013-04-01

    Full Text Available OBJETIVO: Avaliar a incidência de complicações pós-procedimento nos pacientes submetidos a biópsia prostática transretal guiada por ultrassom no setor de intervenção do Departamento de Diagnóstico por Imagem da Escola Paulista de Medicina - Universidade Federal de São Paulo. MATERIAIS E MÉTODOS: Foram avaliados, via contato telefônico, 132 pacientes submetidos a biópsia de próstata transretal guiada por ultrassom no período de abril/2011 a junho/2011, seguindo o protocolo padrão do nosso setor. RESULTADOS: As complicações pós-biópsia foram categorizadas em maiores e menores de acordo com a necessidade de avaliação médica adicional. Cinquenta e nove pacientes (61,8% apresentaram complicações, e desses, grande parte (86,4% apresentou sintomas leves e autolimitados, considerados menores. Oito pacientes (8,2% apresentaram complicações maiores, sendo que apenas um deles necessitou de tratamento sob regime de internação hospitalar. A retenção urinária foi a complicação maior mais incidente no nosso estudo. CONCLUSÃO: Corroborando outros estudos da literatura, nosso trabalho demonstrou baixa prevalência de complicações maiores após a biópsia prostática transretal.OBJECTIVE: To evaluate the incidence of postprocedural complications in patients submitted to transrectal ultrasound-guided prostate biopsy at the Unit of Intervention, Department of Imaging Diagnosis of Escola Paulista de Medicina - Universidade Federal de São Paulo. MATERIALS AND METHODS: Telephone interviews were conducted with 132 patients who had undergone transrectal ultrasound-guided prostate biopsy in the period from April 2011 to June 2011, according to the institution's protocol. RESULTS: Post-biopsy complications were categorized into two groups - minor and major complications, according to their need for further clinical evaluation. Complications were reported by 59 patients (61.8%, most of them (86.4% with mild and self-limited symptoms

  5. Hydrogen gas storage in fluorinated ultramicroporous tunnel crystal.

    Science.gov (United States)

    Kataoka, Keisuke; Katagiri, Toshimasa

    2012-08-21

    We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder.

  6. HySDeP: a computational platform for on-board hydrogen storage systems – hybrid high-pressure solid-state and gaseous storage

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2016-01-01

    A computational platform is developed in the Modelica® language within the DymolaTM environment to provide a tool for the design and performance comparison of on-board hydrogen storage systems. The platform has been coupled with an open source library for hydrogen fueling stations to investigate ...... to a storage capacity four times larger than a tube-in-tube solution of the same size. The volumetric and gravimetric densities of the shell and tube are 2.46% and 1.25% respectively. The dehydriding ability of this solution is proven to withstand intense discharging conditions....

  7. The effects of hydrogen addition on NO formation in atmospheric-pressure, fuel-rich-premixed, burner-stabilized methane, ethane and propane flames

    NARCIS (Netherlands)

    Sepman, A. V.; Mokhov, A. V.; Levinsky, H. B.

    The effects of hydrogen addition on NO formation in fuel-rich, burner-stabilized methane, ethane and propane flames are reported. Profiles of temperature and NO mole fraction were obtained using spontaneous Raman scattering and laser-induced fluorescence (LIF), respectively. Experiments were

  8. Determination of diffusion coefficients of hydrogen and deuterium in Zr–2.5%Nb pressure tube material using hot vacuum extraction-quadrupole mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Komal Chandra, E-mail: komal@barc.gov.in [Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kulkarni, A.S.; Ramanjaneyulu, P.S. [Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Sunil, Saurav [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Saxena, M.K. [Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Singh, R.N. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tomar, B.S.; Ramakumar, K.L. [Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2015-06-15

    The diffusion coefficients of hydrogen and deuterium in Zr–2.5%Nb alloy were measured in the temperature range 523 to 673 K, employing hot vacuum extraction-quadrupole mass spectrometry (HVE-QMS). One end of the Zr–2.5%Nb alloy specimens was charged electrolytically with the desired hydrogen isotope. After annealing at different temperatures for a predetermined time, the specimens were cut into thin slices, which were analyzed for their H{sub 2}/D{sub 2} content using the HVE-QMS technique. The depth profile data were fitted into the equation representing the solution of Fick’s second law of diffusion. The activation energy of hydrogen/deuterium diffusion was obtained from the Arrhenius relation between the diffusion coefficient and temperature. The temperature dependent diffusion coefficient can be represented as D{sub H} = 1.41 × 10{sup −7} exp(−36,000/RT) and D{sub D} = 6.16 × 10{sup −8} exp(−35,262/RT) for hydrogen and deuterium, respectively.

  9. Hydrogen Generator

    Science.gov (United States)

    1983-01-01

    A unit for producing hydrogen on site is used by a New Jersey Electric Company. The hydrogen is used as a coolant for the station's large generator; on-site production eliminates the need for weekly hydrogen deliveries. High purity hydrogen is generated by water electrolysis. The electrolyte is solid plastic and the control system is electronic. The technology was originally developed for the Gemini spacecraft.

  10. A novel liquid organic hydrogen carrier system based on catalytic peptide formation and hydrogenation.

    Science.gov (United States)

    Hu, Peng; Fogler, Eran; Diskin-Posner, Yael; Iron, Mark A; Milstein, David

    2015-04-17

    Hydrogen is an efficient green fuel, but its low energy density when stored under high pressure or cryogenically, and safety issues, presents significant disadvantages; hence finding efficient and safe hydrogen carriers is a major challenge. Of special interest are liquid organic hydrogen carriers (LOHCs), which can be readily loaded and unloaded with considerable amounts of hydrogen. However, disadvantages include high hydrogen pressure requirements, high reaction temperatures for both hydrogenation and dehydrogenation steps, which require different catalysts, and high LOHC cost. Here we present a readily reversible LOHC system based on catalytic peptide formation and hydrogenation, using an inexpensive, safe and abundant organic compound with high potential capacity to store and release hydrogen, applying the same catalyst for loading and unloading hydrogen under relatively mild conditions. Mechanistic insight of the catalytic reaction is provided. We believe that these findings may lead to the development of an inexpensive, safe and clean liquid hydrogen carrier system.

  11. Estudo ultrastrutural de biópsias de conjuntiva em doenças metabólicas do sistema nervoso

    Directory of Open Access Journals (Sweden)

    S. Rosemberg

    1987-03-01

    Full Text Available Quarenta biópsias de conjuntivas obtidas de um número igual de crianças portadoras de doenças metabólicas do SNC, ou supostas de tal acometimento, foram analisadas do ponto de vista ultrastrutural. Em 20 casos foram observadas alterações ultrastruturais que possibilitaram firmar o diagnóstico de muco-polissacaridose em 8, gangliosidose G M1 em 6, distrofia neuro-axonal infantil em 4, gangliosidose G M1 em um e forma infantil tardia de lipofuscinose ceróide em um. Nos 20 casos em que o exame revelou-se negativo, este era esperado em dois (doença de Leigh e de Hallervorden-Spatz; em dois, o resultado revelou-se falso negativo (leucodistrofia metacromática e adrenoleucodistrofia; em 12 casos sua negatividade permitiu afastar doença de acúmulo; em 4 casos suspeitos de lipofuscinose ceróide seu resultado foi inconclusivo. O estudo ultrastrutural de biópsias de conjuntiva é um instrumento importante para o diagnóstico de doenças metabólicas do SNC.

  12. Malformações do sistema nervoso central : análise de 157 necrópsias pediátricas

    Directory of Open Access Journals (Sweden)

    NORONHA LÚCIA DE

    2000-01-01

    Full Text Available As malformações do sistema nervoso central (SNC têm sido relatadas como de alta prevalência, acometendo 5 a 10 crianças para 1000 nascidos vivos. Estudamos a frequência das malformações do SNC em 5837 necrópsias pediátricas realizadas no Serviço de Anatomia Patológica do Hospital de Clínicas-UFPR, entre 1960 e 1995. Encontraram-se 157 malformações do SNC, correspondendo a 2,69% das necrópsias. As malformações mais comuns foram os defeitos do tubo neural (61%, incluindo 47 anencefalias e 45 casos classificados no grupo das mieloencefaloceles. As anomalias da vesícula prosencefálica foram responsáveis por 8% das malformações encefálicas, havendo sete casos de holoprosencefalia. Em 3%, as alterações ocorreram na fossa posterior, com três malformações de Arnold-Chiari. No presente estudo, os índices de mortalidade por malformações do SNC foram mais altos no período neonatal.

  13. Avaliação de técnicas de biópsia renal em ovinos Evaluation of renal biopsy techniques in sheep

    Directory of Open Access Journals (Sweden)

    Pedro B. Néspoli

    2010-03-01

    Full Text Available Devido à escassez de trabalhos sobre biópsias renais em ovinos foi desenvolvido um estudo comparativo entre três técnicas de biópsia renal nesta espécie. Neste estudo foram utilizadas nove ovelhas (26,64 kg ±4,86 mestiças (Santa Inês em procedimentos seriados, com intervalos consecutivos de uma semana. Foram avaliados os aspectos clínicos, achados de patologia clínica, o peso das amostras renais, a qualidade histológica, o número de glomérulos e a presença de artefatos no corte histológico da técnica de biópsia percutânea cega, da biópsia guiada por ultrassonografia e do procedimento videolaparoscópico. Não foram observadas alterações hematológicas ou bioquímicas relevantes nos animais submetidos às biópsias renais e as manifestações clínicas detectadas foram leves e transitórias, exceto por um caso de obstrução uretral por coágulo sangüíneo. A técnica percutânea cega foi relacionada à maior ocorrência e gravidade de hematúria, com danos mais graves ao tecido renal e com o único caso de obstrução do fluxo urinário. Na técnica videolaparoscópica, o peso médio das amostras foi superior e a hematúria discreta e transitória. Verificou-se relação direta entre a ocorrência de hematúria grave e a presença de epitélio de transição nas amostras e o número de tentativas utilizado para a obtenção dos fragmentos.Due to lack of studies about renal biopsies in sheep, a comparative study was performed for three renal biopsy techniques in this species. In this study, nine crossbred (Santa Inês ewe lamb (26.64 kg ±4,86 were used in serial procedures with one week consecutive intervals. The clinical aspects, clinical pathological findings, renal sample weights, histology quality, number of glomeruli, and the presence of artifacts in the histology slices were evaluated using the techniques of percutaneous blind biopsy, ultrasound guided biopsies and of videolaparoscopic procedure. No relevant

  14. Development of high temperature reference electrodes for in-pile application: Part I. Feasibility study of the external pressure balanced Ag/AgCl reference electrode (EPBRE) and the cathodically charged Palladium hydrogen electrode

    Energy Technology Data Exchange (ETDEWEB)

    Bosch, R.W.; Van Nieuwenhove, R

    1998-10-01

    The main problems connected with corrosion potential measurements at elevated temperatures and pressures are related to the stability and lifetime of the reference electrode and the correct estimation of the potential related to the Standard Hydrogen Scale (SHE). Under Pressurised Water Reactor (PWR) conditions of 300 degrees Celsius and 150 bar, the choice of materials is also a limiting factor due to the influence of radiation. Investigations on two reference electrodes that can be used under PWR conditions are reported: the cathodically charged palladium hydrogen electrode, and the external pressure balanced silver/silver chloride electrode. Preliminary investigations with the Pd-electrode were focused on the calculation of the required charging time and the influence of dissolved oxygen. High temperature applications are discussed on the basis of results reported in the literature. Investigations with the silver/silver chloride reference electrode mainly dealt with the salt bridge which is necessary to connect the reference electrode with the testing solution. It is shown that the thermal junction potential is independent of the length of the salt bridge. In addition, the high temperature contributes to an increase of the conductivity of the solution, which is beneficial for the salt bridge connection.

  15. Biópsia com agulha grossa guiada por ultrassonografia para o diagnóstico dos tumores fibroepiteliais da mama Ultrasound-guided core needle biopsy for the diagnosis of fibroepithelial breast tumors

    Directory of Open Access Journals (Sweden)

    Marcos Desidério Ricci

    2011-01-01

    Full Text Available OBJETIVO: avaliar a taxa de concordância da biópsia percutânea com agulha grossa guiada por ultrassom seguida pela biópsia excisional em nódulos de mama palpáveis, sugestivos de tumores fibroepiteliais. MÉTODO: estudo retrospectivo que selecionou 70 biópsias com diagnóstico histológico de tumor fibroepitelial em 67 dentre 531 pacientes com lesões mamárias submetidas à biópsia percutânea com agulha grossa guiada por ultrassonografia, com transdutor linear de alta frequência (7.5 MHz, utilizando pistola automática Bard-Magnum e agulha 14 gauge. Foram incluídos os casos com diagnóstico de tumor fibroepitelial na biópsia percutânea ou biópsia excisional. Biópsias com diagnóstico histopatológico de fibroesclerose também foram incluídas no estudo. A força da concordância entre o resultado da biópsia percutânea e da biópsia excisional foi medida pelo coeficiente de Kappa. RESULTADOS: a biópsia excisional revelou 40 casos de fibroadenoma (57,1%, 19 de tumor filoide (27,2% e 11 de fibroesclerose (15,7%. A taxa de concordância para o fibroadenoma foi substancial (k = 0,68; IC95% = 0,45 - 0,91, quase perfeita para o tumor filoide (k = 0,81; IC95% = 0,57 - 1,0 e moderada para a fibroesclerose (k = 0,58; IC95% = 0,36 - 0,90. CONCLUSÕES: a biópsia percutânea com agulha grossa é propedêutica minimamente invasiva que tem taxas de concordância com a biópsia excisional, de "substancial" a "quase perfeita". A fibroesclerose deve ser considerada no diagnóstico diferencial dos tumores fibroepiteliais.PURPOSE: to evaluate the concordance rate of ultrasound-guided core needle biopsy followed by excisional biopsy in palpable breast lumps, suggestive of fibroepithelial tumors. METHOD: a retrospective study included 70 biopsies with a histological diagnosis of fibroepithelial tumor in 67 out of 531 patients with breast lesions submitted to ultrasound-guided core needle biopsy with a high frequency (7.5 MHz linear transducer

  16. Simple, Chemoselective Hydrogenation with Thermodynamic Stereocontrol

    OpenAIRE

    Iwasaki, Kotaro; Wan, Kanny K.; Oppedisano, Alberto; Crossley, Steven W. M.; Shenvi, Ryan A.

    2014-01-01

    Few methods permit the hydrogenation of alkenes to a thermodynamically favored configuration when steric effects dictate the alternative trajectory of hydrogen delivery. Dissolving metal reduction achieves this control, but with extremely low functional group tolerance. Here we demonstrate a catalytic hydrogenation of alkenes that affords the thermodynamic alkane products with remarkably broad functional group compatibility and rapid reaction rates at standard temperature and pressure.

  17. Simple, chemoselective hydrogenation with thermodynamic stereocontrol.

    Science.gov (United States)

    Iwasaki, Kotaro; Wan, Kanny K; Oppedisano, Alberto; Crossley, Steven W M; Shenvi, Ryan A

    2014-01-29

    Few methods permit the hydrogenation of alkenes to a thermodynamically favored configuration when steric effects dictate the alternative trajectory of hydrogen delivery. Dissolving metal reduction achieves this control, but with extremely low functional group tolerance. Here we demonstrate a catalytic hydrogenation of alkenes that affords the thermodynamic alkane products with remarkably broad functional group compatibility and rapid reaction rates at standard temperature and pressure.

  18. Precipitation hardening and hydrogen embrittlement of aluminum ...

    Indian Academy of Sciences (India)

    AA7020 Al–Mg–Zn, a medium strength aluminium alloy, is used in welded structures in military and aerospace applications. As it may be subjected to extremes of environmental exposures, including high pressure liquid hydrogen, it could suffer hydrogen embrittlement. Hydrogen susceptibility of alloy AA7020 was ...

  19. COST-EFFECTIVE METHOD FOR PRODUCING SELF SUPPORTED PALLADIUM ALLOY MEMBRANES FOR USE IN EFFICIENT PRODUCTION OF COAL DERIVED HYDROGEN

    Energy Technology Data Exchange (ETDEWEB)

    B. Lanning; J. Arps

    2005-08-31

    pressure of 50 psia, results in a flux of 155 scf/h/ft{sup 2} (exceeding the 2007 target by 55% and 77% of the 2010 target). Finally, on May 25, we presented a poster at the Hydrogen Program Review in Washington.

  20. Microfabricated hydrogen sensitive membranes

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, A.; Kraetz, L. [Lehrstuhl fuer Thermische Verfahrenstechnik, Technische Universitaet Kaiserslautern (Germany); Detemple, P.; Schmitt, S.; Hessel, V. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Faqir, N. [University of Jordan, Amman (Jordan); Bart, H.J.

    2009-01-15

    Thin, defect-free palladium, palladium/copper and palladium/silver hydrogen absorbing membranes were microfabricated. A dual sputtering technique was used to deposit the palladium alloy membranes of only 1 {mu}m thickness on a nonporous silicon substrate. Advanced silicon etching (ASE) was applied on the backside to create a mechanically stable support structure for the thin films. Performance evaluation was carried out for different gases in a temperature range of 20 C to 298 C at a constant differential pressure of 110 kPa at the two sides of the membrane. The composite membranes show an excellent permeation rate of hydrogen, which appears to be 0.05 Pa m{sup 3} s{sup -1} and 0.01.10{sup -3} Pa m{sup 3} s{sup -1} at 20 C for the microfabricated 23 % silver and the 53 % copper composite membranes, respectively. The selectivity to hydrogen over a gas mixture containing, in addition to hydrogen, carbon monoxide, carbon dioxide and nitrogen was measured. The mass spectrometer did not detect any CO{sub 2} or CO, showing that the membrane is completely hydrogen selective. The microfabricated membranes exhibit both high mechanical strength (they easily withstand pressures up to 4 bar) and high thermal stability (up to 650 C). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  1. Hydrogen storage for automobiles

    Energy Technology Data Exchange (ETDEWEB)

    Strickland, G.

    1979-01-01

    Results of an analysis of hydrogen-fueled automobiles are presented as a part of a continuing study conducted by Lawrence Livermore Laboratory (LLL) on Energy Storage Systems for Automobile Propulsion. The hydrogen is stored either as a metal hydride at moderate pressure in TiFe/sub 0/ /sub 9/Mn/sub 0/ /sub 1/H/sub x/ and at low pressure in MgH/sub x/ catalyzed with 10 wt % Ni, or it is stored in hollow glass microspheres at pressures up to about 400 atm. Improved projections are given for the two hydrides, which are used in combination to take advantage of their complementary properties. In the dual-hydride case and in the microsphere case where Ti-based hydride is used for initial operation, hydrogen is consumed in an internal-combustion engine; whereas in the third case, hydrogen from Ti-based hydride is used with air in an alkaline fuel cell/Ni-Zn battery combination which powers an electric vehicle. Each system is briefly described; and the results of the vehicle analysis are compared with those for the conventional automobile and with electric vehicles powered by Pb-acid or Ni-Zn batteries. Comparisons are made on the basis of automobile weight, initial user cost, and life-cycle cost. In this report, the results are limited to those for the 5-passenger vehicle in the period 1985-1990, and are provided as probable and optimistic values.

  2. Structural, electrical and thermodynamical aspects of hydrogenated ...

    Indian Academy of Sciences (India)

    Unknown

    situ resistance with change in hydrogen pressure, a modi- fied reactor vessel was used for containing the material having an electrode with ceramic insulation. 10 g of alloy was kept in the reactor vessel, which also had a provision for heating and for measuring temperature and hydrogen pressure. Prior to an absorption run ...

  3. Fatores preditivos de metástases axilares em pacientes com câncer de mama e biópsia de linfonodo sentinela positivo

    Directory of Open Access Journals (Sweden)

    Olívio Feitosa Costa Neto

    Full Text Available RESUMO Objetivo: avaliar os fatores de risco para presença de doença metastática axilar não sentinela em pacientes com câncer de mama e biópsia do linfonodo sentinela positiva. Métodos: estudo transversal, retrospectivo, de mulheres com câncer mamário operadas no Instituto do Câncer do Ceará, entre os anos de 2002 e 2012 e submetidas à biópsia de linfonodo sentinela. Resultados: de 946 pacientes com câncer de mama, 331 foram submetidas à biópsia de linfonodo sentinela, que foi positiva em 83. Estas foram submetidas à linfadenectomia axilar e 39 (46% apresentaram metástases em outros linfonodos axilares. As variáveis que foram significantes para doença axilar adicional foram Ki67>14 (p=0,043, presença de invasão angiolinfática (p=0,01 e tamanho tumoral (p=0,027. Não foi observado associação com receptores de estrogênio, progesterona, grau tumoral e Her-2. Discussão: a presença de invasão angiolinfática e tamanho tumoral tambémjáforam relacionados à metástase axilar adicional em outros estudos. Além destas variáveis observou-se o mesmo efeito preditivo quando avaliamos o Ki67. A validação destes resultados poderá permitira customização do tratamento do câncer de mama, podendo reduzir sua morbidade. Conclusão: invasão angiolinfática, tamanho tumoral (T3/T4 e Ki67>14 foram fatores preditivos de acometimento de metástase axilar além do linfonodo sentinela.

  4. Técnica de biópsia hepática em eqüino por laparoscopia Hepatic biopsy in horses by laparoscopy

    Directory of Open Access Journals (Sweden)

    Luis Cláudio Lopes Correia da Silva

    2002-06-01

    Full Text Available Este trabalho experimental objetivou a avaliação do uso da laparoscopia para biópsia hepática em eqüino e o estudo das possíveis alterações clínicas e laboratoriais decorrentes de tal procedimento. Foram utilizados 10 animais, os quais foram submetidos a procedimento cirúrgico em posição quadrupedal, por abordagem pelo flanco direito, no 17º espaço intercostal, após jejum alimentar e hídrico de 36 e 18 horas respectivamente. A avaliação pós-operatória constou de exame físico diário e colheita de amostras de sangue seriadas. O procedimento possibilitou inspeção dos órgãos e estruturas anatômicas localizados dorsalmente à direita da cavidade abdominal, favorecendo a escolha do local de biópsia hepática. Não foram observadas alterações no exame físico dos animais. Os exames hematológicos e de função hepática não apresentaram alterações significativas. Concluiu-se que o emprego da laparoscopia para realização de biópsia hepática em eqüino é simples, eficaz e seguro.The purpose of this research was to evaluate the use of laparoscopy in obtaining hepatic biopsy in horses and to determine a possible clinical and laboratorial changes related to the procedure. Ten animals were submitted to 36 hours of fastening and 18 hours of water deprivation and then operated in the standing position, through a right flank approach at the level of the 17th intercostal space. Post-operative evaluation consisted of daily physical examination and seriated blood sampling. The procedure allowed for wide visualization of the viscera and anatomical structures located on the right side of the abdominal cavity, favouring the choice of the spot for hepatic biopsy collection. No changes were noted in the physical state of the animals and alterations in hemogram and hepatic function tests were not statistically significant. It was concluded that laparoscopy is a simple, effective and safe technique for obtaining hepatic biopsy

  5. Enhanced Hydrogen Dipole Physisorption, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Channing [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2014-01-03

    The hydrogen gas adsorption effort at Caltech was designed to probe and apply our understanding of known interactions between molecular hydrogen and adsorbent surfaces as part of a materials development effort to enable room temperature storage of hydrogen at nominal pressure. The work we have performed over the past five years has been tailored to address the outstanding issues associated with weak hydrogen sorbent interactions in order to find an adequate solution for storage tank technology.

  6. Capacitive level meter for liquid hydrogen

    OpenAIRE

    Matsumoto, Koichi; Sobue, Masamitsu; Asamoto, Kai; Nishimura, Yuta; Abe, Satoshi; Numazawa, Takenori

    2011-01-01

    A capacitive level meter working at low temperatures was made to use in magnetic refrigerator for hydrogen liquefaction. The liquid level was measured from the capacitance between parallel electrodes immersed in the liquid. The meter was tested for liquid nitrogen, hydrogen, and helium. The operation was successful using an AC capacitance bridge. The estimated sensitivity of the meter is better than 0.2 mm for liquid hydrogen. The meter also worked with pressurized hydrogen. © 2010.

  7. BIÓPSIA PULMONAR EM BEZERROS COM BRONCOPNEUMONIA INDUZIDA PELA Mannheimia haemolytica PULMONAR BIOPSY IN CALVES WITH BRONCHOPNEUMONIA INDUCED BY Mannheimia haemolytica

    Directory of Open Access Journals (Sweden)

    Daniel Pessoa Gomes da Silva

    2009-09-01

    Full Text Available Com o propósito de avaliar a segurança, a eficácia diagnóstica da biópsia pulmonar e comparar a possível ocorrência de complicações decorrentes da técnica, entre bezerros sadios e com broncopneumonia induzida, utilizaram-se dez bezerros (G1 sadios e vinte bezerros portadores de broncopneumonia, divididos em quatro grupos de cinco bezerros (G2 a G5, os quais foram biopsiados 12, 24, 48 e 72 horas após a inoculação com Mannheimia haemolytica, respectivamente. A presença de crepitação grossa, som submaciço à percussão e as alterações radiográficas auxiliaram no diagnóstico da broncopneumonia e localizaram a área pulmonar a ser biopsiada nos grupos G2 a G5. As alterações microscópicas, visualizadas nos animais do grupo G2 a G5, foram as de broncopneumonia fibrinopurulenta. Nos bezerros do grupo G1 as alterações relacionadas à técnica foram: tosse, epistaxe, dispneia mista, taquipneia e taquicardia. Cinco (25% bezerros com broncopneumonia desenvolveram hemotórax após a biópsia e as alterações relacionadas à técnica foram: taquipneia, taquicardia, tosse, dispneia mista, apatia, mucosas pálidas e decúbito. Conclui-se que a biópsia pulmonar permite o diagnóstico de broncopneumonia em bezerros, contudo as complicações decorrentes da técnica limitam o seu uso apenas nas situações em que os métodos convencionais não tenham possibilitado o diagnóstico.

    PALAVRAS-CHAVES: Bezerros, biópsia pulmonar, broncopneumonia, Mannheimia haemolytica.

    The purpose of this study was to evaluate the safety and diagnostic efficacy of lung biopsy and to compare the possible occurrence of complications due to this technique in healthy calves and in calves with bronchopneumonia. Thirty Holstein calves were divided into a group of ten healthy animals (G1 and into four experimental groups (G2 to G5 of five calves each

  8. Características das encefalites em autópsias - aspectos epidemiológicos e morfológicos.

    OpenAIRE

    Terra, Sílvia Azevedo

    2007-01-01

    O termo encefalite significa inflamação do parênquima encefálico e dentre as possíveis etiologias da doença, destacamos a infecciosa, que entre outros agentes, pode ser causada por vírus, fungos, bactérias, protozoários e metazoários. Neste estudo retrospectivo, o objetivo foi descrever os dados epidemiológicos e morfológicos das encefalites em pacientes autopsiados no HE/UFTM no período de 1976 a 1986. Revisamos 1.267 laudos de autópsias e coletamos dados referentes à idade, ao gêne...

  9. Características das encefalites em autópsias: aspectos epidemiológicos e morfológicos.

    OpenAIRE

    Terra, Sílvia Azevedo

    2007-01-01

    O termo encefalite significa inflamação do parênquima encefálico e dentre as possíveis etiologias da doença, destacamos a infecciosa, que entre outros agentes, pode ser causada por vírus, fungos, bactérias, protozoários e metazoários. Neste estudo retrospectivo, o objetivo foi descrever os dados epidemiológicos e morfológicos das encefalites em pacientes autopsiados no HE/UFTM no período de 1976 a 1986. Revisamos 1.267 laudos de autópsias e coletamos dados referentes à idade, ao gêne...

  10. Biópsia hepática por laparotomia paracostal em bovinos e búfalos Paracostal liver biopsy in cattle and buffalo

    Directory of Open Access Journals (Sweden)

    Antonio Humberto Hamad Minervino

    2009-06-01

    Full Text Available A técnica de biópsia hepática em ruminantes tem importante valor no diagnóstico clínico de doenças tóxicas e metabólicas, em especial nos desequilíbrios minerais. As técnicas mais comumente utilizadas restringem análises devido ao limitado volume de tecido obtido. No presente trabalho, avaliou-se o uso de uma técnica de biópsia hepática por laparotomia paracostal em bovinos e búfalos. Foram utilizados 10 bovinos e 10 búfalos hígidos. Os animais foram mantidos em estação, sedados com xilazina e infiltrados localmente com lidocaína e epinefrina. O acesso à cavidade abdominal foi realizado por meio de uma incisão dorso-ventral de 15cm no flanco direito, iniciada ventralmente (cerca de 4-5cm ao processo transverso da 2a ou 3a vértebra lombar e situada caudalmente (cerca de 4cm e paralelamente à 13a costela, obtendo-se visualização do fígado. Foi então realizado pinçamento do bordo caudal do órgão com pinça Doyen para remoção de fragmento hepático (2 a 4g. Procedeu-se o fechamento da cavidade abdominal como de rotina. Foram analisados os parâmetros bioquímicos e hematológicos antes do procedimento (tempo zero e após 24 horas, 48 horas, 5 dias e 10 dias após a biópsia. Todas as variáveis bioquímicas estudadas retornaram aos valores basais 5 e 10 dias após o procedimento nos bovinos e búfalos, respectivamente. O tempo médio de cirurgia por animal foi de 25 minutos. A biópsia hepática por laparotomia paracostal demonstrou ser uma técnica eficaz e de baixo risco à saúde dos animais, permitindo a coleta de suficiente quantidade de tecido hepática para realização de múltiplas análises.Liver biopsy in ruminants is an important technique for clinical diagnosis of toxic and metabolic diseases, especially mineral disorders. The most frequent procedures used so far results in an small amount of liver and not enough for multiple tests. The present study aims to evaluate the efficacy of paracostal laparotomy

  11. Direct-hydrogen-fueled proton-exchange-membrane fuel cell system for transportation applications

    Energy Technology Data Exchange (ETDEWEB)

    Oei, D.; Adams, J.A.; Kinnelly, A.A. [and others

    1997-07-01

    In partial fulfillment of the U.S. Department of Energy Contract No. DE-ACO2-94CE50389, {open_quotes}Direct Hydrogen-Fueled Proton-Exchange-Membrane (PEM) Fuel Cell System for Transportation Applications{close_quotes}, this conceptual vehicle design report addresses the design and packaging of battery augmented fuel cell powertrain vehicles. This report supplements the {open_quotes}Conceptual Vehicle Design Report - Pure Fuel Cell Powertrain Vehicle{close_quotes} and includes a cost study of the fuel cell power system. The three classes of vehicles considered in this design and packaging exercise are the same vehicle classes that were studied in the previous report: the Aspire, representing the small vehicle class; the AIV (Aluminum Intensive Vehicle) Sable, representing the mid-size vehicle; and the E-150 Econoline, representing the van-size class. A preliminary PEM fuel cell power system manufacturing cost study is also presented. As in the case of the previous report concerning the {open_quotes}Pure Fuel Cell Powertrain Vehicle{close_quotes}, the same assumptions are made for the fuel cell power system. These assumptions are fuel cell system power densities of 0.33 kW/ka and 0.33 kW/l, platinum catalyst loading of less than or equal to 0.25 mg/cm{sup 2} total, and hydrogen tanks containing compressed gaseous hydrogen under 340 atm (5000 psia) pressure. The batteries considered for power augmentation of the fuel cell vehicle are based on the Ford Hybrid Electric Vehicle (HEV) program. These are state-of-the-art high power lead acid batteries with power densities ranging from 0.8 kW/kg to 2 kW/kg. The results reported here show that battery augmentation provides the fuel cell vehicle with a power source to meet instant high power demand for acceleration and start-up. Based on the assumptions made in this report, the packaging of the battery augmented fuel cell vehicle appears to be as feasible as the packaging of the pure fuel cell powered vehicle.

  12. Synthesis of Ni/Graphene Nanocomposite for Hydrogen Storage.

    Science.gov (United States)

    Zhou, Chunyu; Szpunar, Jerzy A; Cui, Xiaoyu

    2016-06-22

    We have designed a Ni-graphene composite for hydrogen storage with Ni nanoparticles of 10 nm in size, uniformly dispersed over a graphene substrate. This system exhibits attractive features like high gravimetric density, ambient conditions, and low activation temperature for hydrogen release. When charged at room temperature and an atmospheric hydrogen pressure of 1 bar, it could yield a hydrogen capacity of 0.14 wt %. When hydrogen pressure increased to 60 bar, the sorbent had a hydrogen gravimetric density of 1.18 wt %. The hydrogen release could occur at an operating temperature below 150 °C and completes at 250 °C.

  13. Nonmonotonic Temperature Dependence of the Pressure-Dependent Reaction Rate Constant and Kinetic Isotope Effect of Hydrogen Radical Reaction with Benzene Calculated by Variational Transition-State Theory.

    Science.gov (United States)

    Zhang, Hui; Zhang, Xin; Truhlar, Donald G; Xu, Xuefei

    2017-11-30

    The reaction between H and benzene is a prototype for reactions of radicals with aromatic hydrocarbons. Here we report calculations of the reaction rate constants and the branching ratios of the two channels of the reaction (H addition and H abstraction) over a wide temperature and pressure range. Our calculations, obtained with an accurate potential energy surface, are based on variational transition-state theory for the high-pressure limit of the addition reaction and for the abstraction reaction and on system-specific quantum Rice-Ramsperger-Kassel theory calibrated by variational transition-state theory for pressure effects on the addition reaction. The latter is a very convenient way to include variational effects, corner-cutting tunneling, and anharmonicity in falloff calculations. Our results are in very good agreement with the limited experimental data and show the importance of including pressure effects in the temperature interval where the mechanism changes from addition to abstraction. We found a negative temperature effect of the total reaction rate constants at 1 atm pressure in the temperature region where experimental data are missing and accurate theoretical data were previously missing as well. We also calculated the H + C 6 H 6 /C 6 D 6 and D + C 6 H 6 /C 6 D 6 kinetic isotope effects, and we compared our H + C 6 H 6 results to previous theoretical data for H + toluene. We report a very novel nonmonotonic dependence of the kinetic isotope effect on temperature. A particularly striking effect is the prediction of a negative temperature dependence of the total rate constant over 300-500 K wide temperature ranges, depending on the pressure but generally in the range from 600 to 1700 K, which includes the temperature range of ignition in gasoline engines, which is important because aromatics are important components of common fuels.

  14. Metallic Hydrogen: The Most Powerful Rocket Fuel Yet To Exist

    OpenAIRE

    Silvera, Isaac F.; Cole, John W.

    2010-01-01

    Wigner and Huntington first predicted that pressures of order 25 GPa were required for the transition of solid molecular hydrogen to the atomic metallic phase. Later it was predicted that metallic hydrogen might be a metastable material so that it remains metallic when pressure is released. Experimental pressures achieved on hydrogen have been more than an order of magnitude higher than the predicted transition pressure and yet it remains an insulator. We discuss the applications of metast...

  15. Modeling Droplet Heat and Mass Transfer during Spray Bar Pressure Control of the Multipurpose Hydrogen Test Bed (MHTB) Tank in Normal Gravity

    Science.gov (United States)

    Kartuzova, O.; Kassemi, M.

    2016-01-01

    A CFD model for simulating pressure control in cryogenic storage tanks through the injection of a subcooled liquid into the ullage is presented and applied to the 1g MHTB spray bar cooling experiments. An Eulerian-Lagrangian approach is utilized to track the spray droplets and capture the interaction between the discrete droplets and the continuous ullage phase. The spray model is coupled with the VOF model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. A new model for calculating the droplet-ullage heat and mass transfer is developed. In this model, a droplet is allowed to warm up to the saturation temperature corresponding to the ullage vapor pressure, after which it evaporates while remaining at the saturation temperature. The droplet model is validated against the results of the MHTB spray-bar cooling experiments with 50% and 90% tank fill ratios. The predictions of the present T-sat based model are compared with those of a previously developed kinetic-based droplet mass transfer model. The predictions of the two models regarding the evolving tank pressure and temperature distributions, as well as the droplets' trajectories and temperatures, are examined and compared in detail. Finally, the ullage pressure and local vapor and liquid temperature evolutions are validated against the corresponding data provided by the MHTB spray bar mixing experiment.

  16. Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

    Science.gov (United States)

    Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

    2010-04-13

    A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

  17. Hydrogen Bibliography

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-01

    The Hydrogen Bibliography is a compilation of research reports that are the result of research funded over the last fifteen years. In addition, other documents have been added. All cited reports are contained in the National Renewable Energy Laboratory (NREL) Hydrogen Program Library.

  18. Pressure-assisted cold denaturation of hen egg white lysozyme: the influence of co-solvents probed by hydrogen exchange nuclear magnetic resonance.

    Science.gov (United States)

    Vogtt, K; Winter, R

    2005-08-01

    COSY proton nuclear magnetic resonance was used to measure the exchange rates of amide protons of hen egg white lysozyme (HEWL) in the pressure-assisted cold-denatured state and in the heat-denatured state. After dissolving lysozyme in deuterium oxide buffer, labile protons exchange for deuterons in such a way that exposed protons are substituted rapidly, whereas "protected" protons within structured parts of the protein are substituted slowly. The exchange rates k obs were determined for HEWL under heat treatment (80 degrees C) and under high pressure conditions at low temperature (3.75 kbar, -13 degrees C). Moreover, the influence of co-solvents (sorbitol, urea) on the exchange rate was examined under pressure-assisted cold denaturation conditions, and the corresponding protection factors, P, were determined. The exchange kinetics upon heat treatment was found to be a two-step process with initial slow exchange followed by a fast one, showing residual protection in the slow-exchange state and P-factors in the random-coil-like range for the final temperature-denatured state. Addition of sorbitol (500 mM) led to an increase of P-factors for the pressure-assisted cold denatured state, but not for the heat-denatured state. The presence of 2 M urea resulted in a drastic decrease of the P-factors of the pressure-assisted cold denatured state. For both types of co-solvents, the effect they exert appears to be cooperative, i.e., no particular regions within the protein can be identified with significantly diverse changes of P-factors.

  19. Modeling Oxygen Prebreathe Protocols for Exploration Extravehicular Activities Using Variable Pressure Suits

    Science.gov (United States)

    Abercromby, Andrew F. J.; Conkin, Johnny; Gernhardt, Michael L.

    2017-01-01

    Exploration missions are expected to use variable pressure extravehicular activity (EVA) spacesuits as well as a spacecraft "exploration atmosphere" of 56.5 kPa (8.2 psia), 34% O2, both of which provide the possibility of reducing the oxygen prebreathe times necessary to reduce decompression sickness (DCS) risk. Previous modeling work predicted 8.4% DCS risk for an EVA beginning at the exploration atmosphere, followed by 15 minutes of in-suit O2 prebreathe, and 6 hours of EVA at 29.6 kPa (4.3 psia). In this study we model notional prebreathe protocols for a variable pressure suit where the exploration atmosphere is unavailable.

  20. Hydrogen vehicle fueling station

    Energy Technology Data Exchange (ETDEWEB)

    Daney, D.E.; Edeskuty, F.J.; Daugherty, M.A. [Los Alamos National Lab., NM (United States)] [and others

    1995-09-01

    Hydrogen fueling stations are an essential element in the practical application of hydrogen as a vehicle fuel, and a number of issues such as safety, efficiency, design, and operating procedures can only be accurately addressed by a practical demonstration. Regardless of whether the vehicle is powered by an internal combustion engine or fuel cell, or whether the vehicle has a liquid or gaseous fuel tank, the fueling station is a critical technology which is the link between the local storage facility and the vehicle. Because most merchant hydrogen delivered in the US today (and in the near future) is in liquid form due to the overall economics of production and delivery, we believe a practical refueling station should be designed to receive liquid. Systems studies confirm this assumption for stations fueling up to about 300 vehicles. Our fueling station, aimed at refueling fleet vehicles, will receive hydrogen as a liquid and dispense it as either liquid, high pressure gas, or low pressure gas. Thus, it can refuel any of the three types of tanks proposed for hydrogen-powered vehicles -- liquid, gaseous, or hydride. The paper discusses the fueling station design. Results of a numerical model of liquid hydrogen vehicle tank filling, with emphasis on no vent filling, are presented to illustrate the usefulness of the model as a design tool. Results of our vehicle performance model illustrate our thesis that it is too early to judge what the preferred method of on-board vehicle fuel storage will be in practice -- thus our decision to accommodate all three methods.

  1. Pressure effects on the dipole oscillator strength, polarizability, and mean excitation energy of a hydrogen impurity under cylindrical confinement: off-center axis effect

    Science.gov (United States)

    Cabrera-Trujillo, R.; Méndez-Fragoso, R.; Cruz, S. A.

    2017-07-01

    We study the electronic properties of a hydrogen atom under cylindrical confinement as obtained by a numerical solution to the Schrödinger equation by means of a finite-differences approach. In particular we calculate the dipole oscillator strength, static and dynamic dipole polarizabilities, as well as the mean excitation energy as a function of the position of the hydrogen impurity along the symmetry axis for the case of a ‘standard’ cylindrical confinement cavity and several confinement conditions. The effect of the displacement on the electronic properties is reflected in the change of the wave-function as the impurity approaches the cylinder potential lid produced by the surrounding confinement environment. We find that the intensity of the main dipole transition, {f}1sσ \\to 2pσ , is reduced as the atom is displaced off-center along the symmetry axis, reaching a minimum half-way between the center of the cylinder and the lid and then increasing when at the cylinder lid. In the process some other transition lines become more intense with a maximum also at half-way between the center and the cylinder lid. We find that the label assignment on the excitation transitions changes as the impurity is displaced along the symmetry axis due to the polarizability of the impurity electronic cloud. Results for the static and dynamic polarizability for the confined impurity as well as the mean excitation energy for the cases of penetrable and impenetrable confinement are presented. We find that the static polarizability increases as the impurity approaches the cylinder lid meanwhile the mean excitation energy is reduced.

  2. Hydrogen adsorption on rhodium

    Energy Technology Data Exchange (ETDEWEB)

    Belyaeva, M.E.; Michri, A.A.; Kalish, T.V.; Pshenichnikov, A.G.; Kazarinov, V.E.

    1987-09-01

    Measurements of thermal desorption and electron work function were used to investigate the mechanism of hydrogen adsorption from the gas phase on rhodium single-crystal faces and on a polycrystalline rhodium sample at room temperatures over the pressure range from 1.3-10/sup -3/ to 1.3 x 10/sup -5/ Pa. It was found that dipoles oriented with their negative ends toward the gas phase (dipoles of type I) form more rapidly than dipoles having the opposite orientation (dipoles of type II). For formation of the latter, a mechanism is proposed according to which the rate-determining step of the overall process is the transition of reversibly adsorbed hydrogen to dipoles of type II (the spillover), which occurs at surface defects. It was shown that the kinetics of this process with respect to the individual defect obeys an equation which is zeroth order in theta/sub H/ and pressure.

  3. Method for charging a hydrogen getter

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, C. Edwin (Golden, CO); Keyser, Matthew A. (Westminster, CO); Benson, David K. (Golden, CO)

    1998-01-01

    A method for charging a sample of either a permanent or reversible getter material with a high concentration of hydrogen while maintaining a base pressure below 10.sup.-4 torr at room temperature involves placing the sample of hydrogen getter material in a chamber, activating the sample of hydrogen getter material, overcharging the sample of getter material through conventional charging techniques to a high concentration of hydrogen, and then subjecting the sample of getter material to a low temperature vacuum bake-out process. Application of the method results in a reversible hydrogen getter which is highly charged to maximum capacities of hydrogen and which concurrently exhibits minimum hydrogen vapor pressures at room temperatures.

  4. Method for charging a hydrogen getter

    Science.gov (United States)

    Tracy, C.E.; Keyser, M.A.; Benson, D.K.

    1998-09-15

    A method for charging a sample of either a permanent or reversible getter material with a high concentration of hydrogen while maintaining a base pressure below 10{sup {minus}4} torr at room temperature involves placing the sample of hydrogen getter material in a chamber, activating the sample of hydrogen getter material, overcharging the sample of getter material through conventional charging techniques to a high concentration of hydrogen, and then subjecting the sample of getter material to a low temperature vacuum bake-out process. Application of the method results in a reversible hydrogen getter which is highly charged to maximum capacities of hydrogen and which concurrently exhibits minimum hydrogen vapor pressures at room temperatures. 9 figs.

  5. Hydrogen storage in carbon nanotubes.

    Science.gov (United States)

    Hirscher, M; Becher, M

    2003-01-01

    The article gives a comprehensive overview of hydrogen storage in carbon nanostructures, including experimental results and theoretical calculations. Soon after the discovery of carbon nanotubes in 1991, different research groups succeeded in filling carbon nanotubes with some elements, and, therefore, the question arose of filling carbon nanotubes with hydrogen by possibly using new effects such as nano-capillarity. Subsequently, very promising experiments claiming high hydrogen storage capacities in different carbon nanostructures initiated enormous research activity. Hydrogen storage capacities have been reported that exceed the benchmark for automotive application of 6.5 wt% set by the U.S. Department of Energy. However, the experimental data obtained with different methods for various carbon nanostructures show an extreme scatter. Classical calculations based on physisorption of hydrogen molecules could not explain the high storage capacities measured at ambient temperature, and, assuming chemisorption of hydrogen atoms, hydrogen release requires temperatures too high for technical applications. Up to now, only a few calculations and experiments indicate the possibility of an intermediate binding energy. Recently, serious doubt has arisen in relation to several key experiments, causing considerable controversy. Furthermore, high hydrogen storage capacities measured for carbon nanofibers did not survive cross-checking in different laboratories. Therefore, in light of today's knowledge, it is becoming less likely that at moderate pressures around room temperature carbon nanostructures can store the amount of hydrogen required for automotive applications.

  6. Hydrogen-powered lawn mower

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, K.; Lorenzoni, J.-L. (Geneva Univ. (Switzerland). Lab. de Cristallographie)

    1993-04-01

    We present a hydrogen-powered lawn mower which was adapted from a commercial model running on gasoline. The necessary modifications include adjustments to the carburettor and the insulation of a hydrogen reservoir containing about 5 kg of a metal hydride powder. Hydrogen is obtained by desorption of that powder at ambient temperature and 2 - 20 bar pressure. The reservoir is rechargeable at a hydrogen pressure of about 25 bar within less than 1 h. One charge lasts about 40 min. corresponding to about 800 m[sup 2] of cut lawn. The engine shows a reduced noise level and no tendency to backfiring. The prototype has run successfully for more than 1 year. (Author)

  7. Process sensitivity studies of the Westinghouse sulfur cycle for hydrogen generation

    Science.gov (United States)

    Carty, R. H.; Cox, K. E.; Funk, J. E.; Soliman, M. A.; Conger, W. L.; Brecher, L. E.; Spewock, S.

    1976-01-01

    The effect of variations of acid concentration, pressure, and temperature on the thermal process efficiency of the Westinghouse sulfur cycle was examined using the HYDRGN program. Modifications to the original program were made to duplicate the process flowsheet and take into account combined cycle heat-to-work efficiencies for electrochemical work requirements, aqueous solutions, and heat-of-mixing effects. A total of 125 process variations were considered (acid concentration: 50-90 w/o; pressure: 15-750 psia; temperature: 922K - 1366K). The methods of analysis, results, and conclusions are presented.

  8. Hydrogen sulfide in paraventricular nucleus attenuates blood pressure by regulating oxidative stress and inflammatory cytokines in high salt-induced hypertension.

    Science.gov (United States)

    Liang, Yan-Feng; Zhang, Dong-Dong; Yu, Xiao-Jing; Gao, Hong-Li; Liu, Kai-Li; Qi, Jie; Li, Hong-Bao; Yi, Qiu-Yue; Chen, Wen-Sheng; Cui, Wei; Zhu, Guo-Qing; Kang, Yu-Ming

    2017-03-15

    Hydrogen sulfide (H2S) is an important gaseous signaling molecule in neuro-modulation, anti-inflammatory, anti-oxidant and anti-hypertensive effects. The paraventricular nucleus (PVN) is a major integrative nucleus in regulating BP and SNA. The aim of this study is to explore whether endogenous or exogenous H2S changed by hydroxylamine hydrochloride (HA) or GYY4137 infused in the PVN affects RSNA and MAP by regulating oxidative stress or the balance between pro-inflammatory cytokines (PICs) and anti-inflammatory cytokines in high salt-induced hypertensive rats. Male Dahl rats were fed by high-salt or normal-salt diet. At the end of the 4th week, GYY4137, HA or vehicle was microinjected into bilateral PVN for 6 weeks. The levels of MAP, HR, plasma norepinephrine (NE), reactive oxygen species (ROS), NOX2, NOX4 and IL-1β were increased significantly in high salt-induced hypertensive rats. Higher levels of these parameters were detected in the group treated by HA, but lower levels in the GYY4137 group. The trends of H2S, CBS, IL-10 and Cu/Zn SOD were opposite to the parameters described above. These findings suggest that endogenous or exogenous H2S in the PVN attenuates sympathetic activity and hypertensive response, which are partly due to decrease of ROS and PICs within the PVN in high salt-induced hypertension. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Investigations on Cs-free alternatives for negative ion formation in a low pressure hydrogen discharge at ion source relevant parameters

    Science.gov (United States)

    Kurutz, U.; Friedl, R.; Fantz, U.

    2017-07-01

    Caesium (Cs) is applied in high power negative hydrogen ion sources to reduce a converter surface’s work function and thus enabling an efficient negative ion surface formation. Inherent drawbacks with the usage of this reactive alkali metal motivate the search for Cs-free alternative materials for neutral beam injection systems in fusion research. In view of a future DEMOnstration power plant, a suitable material should provide a high negative ion formation efficiency and comply with the RAMI issues of the system: reliability, availability, maintainability, inspectability. Promising candidates, like low work function materials (molybdenum doped with lanthanum (MoLa) and LaB6), as well as different non-doped and boron-doped diamond samples were investigated in this context at identical and ion source relevant parameters at the laboratory experiment HOMER. Negative ion densities were measured above the samples by means of laser photodetachment and compared with two reference cases: pure negative ion volume formation with negative ion densities of about 1× {10}15 {{{m}}}-3 and the effect of H- surface production using an in situ caesiated stainless steel sample which yields 2.5 times higher densities. Compared to pure volume production, none of the diamond samples did exhibit a measurable increase in H- densities, while showing clear indications of plasma-induced erosion. In contrast, both MoLa and LaB6 produced systematically higher densities (MoLa: ×1.60 LaB6: ×1.43). The difference to caesiation can be attributed to the higher work functions of MoLa and LaB6 which are expected to be about 3 eV for both compared to 2.1 eV of a caesiated surface.

  10. Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y−(HF)n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator

    Science.gov (United States)

    Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

    2017-01-01

    Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF)n. The HF molecules were ionized in the form of complex ions associated with the negative core ions Y− produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y−(HF)n (Y=F, O2), where larger clusters with n≥4 were not detected. The mechanisms for the formation of the HF, F−(HF)n, and O2−(HF)n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F−(HF)n (n=1–3), the energies for the loss of HF from F−(HF)3, F−(HF)2, and F−(HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy (ECM). These ECM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O2(HF)n]− (n=1–4) was discussed on the basis of the bond lengths of O2H–F−(HF)n and O2−H–F(HF)n obtained by ab initio calculations. The calculations indicated that [O2(HF)4]− separated into O2H and F−(HF)3. PMID:28966900

  11. Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y-(HF) n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator.

    Science.gov (United States)

    Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

    2017-01-01

    Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF) n . The HF molecules were ionized in the form of complex ions associated with the negative core ions Y - produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y - (HF) n (Y=F, O 2 ), where larger clusters with n ≥4 were not detected. The mechanisms for the formation of the HF, F - (HF) n , and O 2 - (HF) n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F - (HF) n ( n =1-3), the energies for the loss of HF from F - (HF) 3 , F - (HF) 2 , and F - (HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy ( E CM ). These E CM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O 2 (HF) n ] - ( n =1-4) was discussed on the basis of the bond lengths of O 2 H-F - (HF) n and O 2 - H-F(HF) n obtained by ab initio calculations. The calculations indicated that [O 2 (HF) 4 ] - separated into O 2 H and F - (HF) 3 .

  12. Stability analysis and testing of a train of centrifugal compressors for high pressure gas injection

    Energy Technology Data Exchange (ETDEWEB)

    Memmott, E.A. [Dresser-Rand Co., Olean, NY (United States)

    1999-07-01

    This paper describes the rotor dynamic stability analysis and the PTC-10 Class 1 test of a three body centrifugal compressor train for high pressure natural gas injection services. This train had a full load full pressure string test on hydrocarbon gases to a final discharge pressure of 500 BAR (7250 PSIA). Each compressor is of the back to back configuration, and is equipped with tilting pad seals, damper bearings, and a honeycomb labyrinth at the division wall with shunt holes. The driver is a gas turbine.

  13. Effects of functionalization, catenation, and variation of the metal oxide and organic linking units on the low-pressure hydrogen adsorption properties of metal-organic frameworks.

    Science.gov (United States)

    Rowsell, Jesse L C; Yaghi, Omar M

    2006-02-01

    The dihydrogen adsorption isotherms of eight metal-organic frameworks (MOFs), measured at 77 K up to a pressure of 1 atm, have been examined for correlations with their structural features. All materials display approximately Type I isotherms with no hysteresis, and saturation was not reached for any of the materials under these conditions. Among the six isoreticular MOFs (IRMOFs) studied, the catenated materials exhibit the largest capacities on a molar basis, up to 9.8 H(2) per formula unit. The addition of functional groups (-Br, -NH(2), -C(2)H(4)-) to the phenylene links of IRMOF-1 (MOF-5), or their replacement with thieno[3,2-b]thiophene moieties in IRMOF-20, altered the adsorption behavior by a minor amount despite large variations in the pore volumes of the resulting materials. In contrast, replacement of the metal oxide units with those containing coordinatively unsaturated metal sites resulted in greater H(2) uptake. The enhanced affinities of these materials, MOF-74 and HKUST-1, were further demonstrated by calculation of the isosteric heats of adsorption, which were larger across much of the range of coverage examined, compared to those of representative IRMOFs. The results suggest that under low-loading conditions, the H(2) adsorption behavior of MOFs can be improved by imparting larger charge gradients on the metal oxide units and adjusting the link metrics to constrict the pore dimensions; however, a large pore volume is still a prerequisite feature.

  14. Hydrogen program overview

    Energy Technology Data Exchange (ETDEWEB)

    Gronich, S. [Dept. of Energy, Washington, DC (United States). Office of Utility Technologies

    1997-12-31

    This paper consists of viewgraphs which summarize the following: Hydrogen program structure; Goals for hydrogen production research; Goals for hydrogen storage and utilization research; Technology validation; DOE technology validation activities supporting hydrogen pathways; Near-term opportunities for hydrogen; Market for hydrogen; and List of solicitation awards. It is concluded that a full transition toward a hydrogen economy can begin in the next decade.

  15. Information needs and instrumentation for hydrogen control and management

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gun Chul; Suh, Kune Y.; Lee, Seung Dong; Lee, Jin Yong [Seoul National Univ., Seoul (Korea, Republic of); Jae, Moo Sung [Hanyang Univ., Seoul (Korea, Republic of)

    2000-03-15

    In this study we examined instrument information, which is related to the severe accident management, guidance. We also examined the hydrogen control and management strategy. Hydrogen control occupies and important part in severe accident management and adequate hydrogen control strategy i needed to maintain the plant integrity. Reducing containment hydrogen during a severe accident will mitigate a potential containment failure mechanism. One of the hydrogen control strategies os intentional burning by the hydrogen igniter. Though intentional hydrogen burn strategy may cause pressure and temperature spikes, which are adverse effects, it si the fastest way of reducing the containment hydrogen concentration. From the Ulchin 3 and 4 plant information we developed a simple hydrogen ignition decision tree. And from the information of decision tree, hydrogen ignition decision can be determined in Containment Event Tree (CET). The end branch values in the CET are hydrogen concentrations, which will be used to assess the accident management measure.

  16. Hydrogen usage

    Energy Technology Data Exchange (ETDEWEB)

    1942-10-22

    This short tabular report listed the number of m/sup 3/ of hydrogen required for a (metric) ton of product for various combinations of raw material and product in a hydrogenation procedure. In producing auto gasoline, bituminous coal required 2800 m/sup 3/, brown coal required 2400 m/sup 3/, high-temperature-carbonization tar required 2100 m/sup 3/, bituminous coal distillation tar required 1300 m/sup 3/, brown-coal low-temperature-carbonization tar required 850 m/sup 3/, petroleum residues required 900 m/sup 3/, and gas oil required 500 m/sup 3/. In producing diesel oil, brown coal required 1900 m/sup 3/, whereas petroleum residues required 500 m/sup 3/. In producing diesel oil, lubricants, and paraffin by the TTH (low-temperature-hydrogenation) process, brown-coal low-temperature-carbonization tar required 550 m/sup 3/. 1 table.

  17. Change in lattice parameter of tantalum due to dissolved hydrogen

    Directory of Open Access Journals (Sweden)

    Gyanendra P. Tiwari

    2012-06-01

    Full Text Available The volume expansion of tantalum due to the dissolved hydrogen has been determined using Bragg equation. The hydrogen was dissolved in the pure tantalum metal at constant temperature (360 °C and constant pressure (132 mbar by varying the duration of hydrogen charging. The amount of dissolved hydrogen was within the solid solubility limit. The samples with different hydrogen concentration were analyzed by X-ray diffraction technique. Slight peak shifts as well as peak broadening were observed. The relative changes of lattice parameters plotted against the hydrogen concentration revealed that the lattice parameters varied linearly with the hydrogen concentration.

  18. Hydrogen storage by physisorption on porous materials

    Energy Technology Data Exchange (ETDEWEB)

    Panella, B.

    2006-09-13

    A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

  19. Reversible hydrogen storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, James A [Lexington, SC; Wang, Tao [Columbia, SC; Ebner, Armin D [Lexington, SC; Holland, Charles E [Cayce, SC

    2012-04-10

    In accordance with the present disclosure, a process for synthesis of a complex hydride material for hydrogen storage is provided. The process includes mixing a borohydride with at least one additive agent and at least one catalyst and heating the mixture at a temperature of less than about 600.degree. C. and a pressure of H.sub.2 gas to form a complex hydride material. The complex hydride material comprises MAl.sub.xB.sub.yH.sub.z, wherein M is an alkali metal or group IIA metal, Al is the element aluminum, x is any number from 0 to 1, B is the element boron, y is a number from 0 to 13, and z is a number from 4 to 57 with the additive agent and catalyst still being present. The complex hydride material is capable of cyclic dehydrogenation and rehydrogenation and has a hydrogen capacity of at least about 4 weight percent.

  20. Storage of liquid hydrogen in natural zeolite

    Directory of Open Access Journals (Sweden)

    Pavol Rybár

    2015-10-01

    Full Text Available When producing and utilizing hydrogen, its storage is one of the biggest problems. Hydrogen, as a gas, is extremely fluid with very low specific weight. Moreover, at a certain rate, the hydrogen-oxygen mixture is explosive. Therefore, the storage of hydrogen is relatively dangerous. A storage of liquid hydrogen in the natural zeolite, which is placed in large capacity battery, appears to be a suitable hydrogen storage method. Proposed and constructed pressure tank, large capacity battery, allows long-term and safe storage of liquid hydrogen, with the possibility to change its state from liquid to gaseous or contrarily in real time. Natural zeolite is an inert material with large internal surface area and high thermal capacity. In the future, presented large capacity battery VAZEP can be a part of the system for production and storage of electric energy generated by photovoltaic modules from the sun.

  1. Correlação entre a graduação histológica de biópsias e do espécimen cirúrgico em câncer da prostata

    Directory of Open Access Journals (Sweden)

    José Cury

    Full Text Available Foram estudados, retrospectivamente, os prontuários de 120 pacientes com câncer localizado da próstata nos estádios clínicos T1, T2 e T3a e que foram submetidos a 1infadenectomia ilíaca e a cirurgia radical da próstata. Todos haviam sido graduados pela escala de Gleason através de biópsias da próstata guiadas pela ultra-sonografia transretal. Correlacionamos a graduação histo1ógica destas biópsias da próstata com a graduação final obtida no exame da peça cirúrgica correspondente e obtivemos exata concordância em 39 pacientes (32,50%. Ao considerarmos a concordância de ± 1unidade, observamos concordância de resultado em 81 pacientes (67,50%. A subgraduação histológica das biópsias prostáticas foi encontrada em 75 pacientes (62,50% dos casos.

  2. Paralisia do nervo ulnar na lepra sem alterações cutâneas: biópsia do ramo superficial do nervo ulnar na mão

    Directory of Open Access Journals (Sweden)

    FREITAS MARCOS R. G. DE

    1998-01-01

    Full Text Available A lepra constitui causa frequente de acometimento de nervos periféricos, em nosso meio. O sistema nervoso periférico é acometido por vezes sem que haja alterações cutâneas: é a chamada forma neurítica pura. Nessa variante, o nervo mais afetado é o ulnar. Nos casos de acometimento isolado de nervos periféricos somente a feitura de biópsia de nervo conduzirá ao diagnóstico. Assim, resolvemos realizar biópsia do ramo sensitivo superficial do nervo ulnar na mão em 17 pacientes com paresia ou paralisia desse nervo e espessamento do mesmo na altura do cotovelo. Os principais achados foram: redução do número de fibras mielínicas em 14 casos, infiltrado inflamatório em 13, fibrose em 12, desmielinização e remielinização em 9, presença de granuloma em 6 e visualização do Mycobacterium leprae em 5. Concluímos que a biópsia do ramo sensitivo superficial do nervo ulnar na mão é um bom meio diagnóstico de lepra em pacientes com acometimento desse nervo

  3. Report of National Research Institute for Pollution and Resources for fiscal 1979. Research on conversion of coal to petroleum, research on coal liquefaction, high pressure liquid phase hydrogenation of coal by continuous test equipment, and manufacture of coal chemicals; 1979 nendo sekitan no yuka no kenkyu / sekitan no ekika no kenkyu / renzoku shiken sochi ni yoru sekitan no koatsu ekiso suisoka bunkai / coal chemicals no seizo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-07-01

    Research was conducted on conversion of coal to petroleum for the purpose of securing substitute liquid fuel. Recovery of hydrogen from the waste gas from the conversion process was explained, as were the conversion results from various coals produced in Japan. In coal liquefaction researches with the aim of manufacturing artificial petroleum, a report was made on each of the researches, i.e., the experiment results of coal liquefaction using various catalysts, manufacture of hydrogen by water gas reaction, catalytic action against coal paste, action of mixed oil and pressure against coal paste, result of hydrogen adding test for coal paste using an intermediate scale device, test result of secondary hydrogen addition for coal liquefied oil, and the test result of continuous secondary hydrogen addition for the liquefied oil. In the manufacture of fuel oil by hydro-cracking of coal or tar, a report was made on high pressure liquid phase hydrogenation of coal using a continuous testing device. Aromatic chemicals useful as chemical materials are supposed to be obtained by cutting inter-polymerized-unit bonding to make low molecules from the chemical structure of coal, removing surrounding radicals and simplifying it. A report was also made on the experiment of manufacturing coal chemicals by combination of high pressure liquid phase hydrogenation and hydro-dealkylation. (NEDO)

  4. Versatile Hydrogen

    Indian Academy of Sciences (India)

    Hydrogen is probably the most intriguing ele- ment in the periodic table. Although it is only the seventh most abundant element on earth, it is the most abundant element in the uni- verse. It combines with almost all the ele- ments of the periodic table, except for a few transition elements, to form binary compounds of the type E.

  5. On the possibility of metastable metallic hydrogen

    OpenAIRE

    Tenney, Craig M.; Sharkey, Keeper L.; McMahon, Jeffrey M.

    2017-01-01

    Metallic hydrogen is expected to exhibit remarkable physics. Examples include high-temperature superconductivity and possible novel types of quantum fluids. These could have revolutionary practical applications. The pressures required to obtain metallic hydrogen, however, are expected to be significant. For practical, and terrestrial applications, a key question is therefore whether this phase is metastable at lower pressures. In this work, this possibility is investigated, using first-princi...

  6. Use of reversible hydrides for hydrogen storage

    Science.gov (United States)

    Darriet, B.; Pezat, M.; Hagenmuller, P.

    1980-01-01

    The addition of metals or alloys whose hydrides have a high dissociation pressure allows a considerable increase in the hydrogenation rate of magnesium. The influence of temperature and hydrogen pressure on the reaction rate were studied. Results concerning the hydriding of magnesium rich alloys such as Mg2Ca, La2Mg17 and CeMg12 are presented. The hydriding mechanism of La2Mg17 and CeMg12 alloys is given.

  7. Hydrogen storage in nanostructured materials

    Energy Technology Data Exchange (ETDEWEB)

    Assfour, Bassem

    2011-02-28

    Hydrogen is an appealing energy carrier for clean energy use. However, storage of hydrogen is still the main bottleneck for the realization of an energy economy based on hydrogen. Many materials with outstanding properties have been synthesized with the aim to store enough amount of hydrogen under ambient conditions. Such efforts need guidance from material science, which includes predictive theoretical tools. Carbon nanotubes were considered as promising candidates for hydrogen storage applications, but later on it was found to be unable to store enough amounts of hydrogen under ambient conditions. New arrangements of carbon nanotubes were constructed and hydrogen sorption properties were investigated using state-of-the-art simulation methods. The simulations indicate outstanding total hydrogen uptake (up to 19.0 wt.% at 77 K and 5.52wt.% at 300 K), which makes these materials excellent candidates for storage applications. This reopens the carbon route to superior materials for a hydrogen-based economy. Zeolite imidazolate frameworks are subclass of MOFs with an exceptional chemical and thermal stability. The hydrogen adsorption in ZIFs was investigated as a function of network geometry and organic linker exchange. Ab initio calculations performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF framework. Subsequently, GCMC simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions. The best of these materials (ZIF-8) is found to be able to store up to 5 wt.% at 77 K and high pressure. We expected possible improvement of hydrogen capacity of ZIFs by substituting the metal atom (Zn{sup 2+}) in the structure by lighter elements such as B or Li. Therefore, we investigated the energy landscape of LiB(IM)4 polymorphs in detail and analyzed their hydrogen storage capacities. The structure with the fau topology was shown to be one of the best materials for hydrogen storage. Its

  8. Hydrogen in metals

    CSIR Research Space (South Africa)

    Carter, TJ

    2001-04-01

    Full Text Available The effects of hydrogen on various metals and the use of metal hydrides for hydrogen storage are discussed. The mechanisms of, and differences between, hydrogen embrittlement and hydrogen attack of ferritic steels are compared, common sources...

  9. Construction of hydrogenation stalls for explosions

    Energy Technology Data Exchange (ETDEWEB)

    Raichle, L.

    1943-05-03

    This report contained explanations for different questions that had been asked by the Association of Chemical Manufacturers. The first item discussed was the pressure occurring in hydrogenation stalls in hydrogen explosions. The pressures actually used were much smaller than the maximum design pressure due to burning gases being allowed to escape from the top and front of the stalls since these areas were open and it could not be assumed that the whole stall space was filled with a 32% hydrogen concentration at the beginning of an explosion. The second item discussed was specifications and rules for the building of hydrogenation stalls. These included the calculations for simple wind pressure according to the Building Code with the usual safety factors and the calculations for an inner pressure of 300 kg/m/sup 2/ with the usual safety factors. An explanation of a stall explosion in Poelitz and reinforced stall construction in Poelitz were two other items that were discussed. Appendix I of the report involved maximum pressures and temperature in hydrogen explosions. Diagram I was involved with this. Appendix II discussed the behavior of a hydrogen flame at high emerging velocities and Appendix III discussed stall construction at Poelitz.

  10. MELAS: clinical features, muscle biopsy and molecular genetics MELAS: manifestações clínicas, biópsia muscular e estudo molecular

    Directory of Open Access Journals (Sweden)

    Paulo José Lorenzoni

    2009-09-01

    Full Text Available OBJECTIVE: The aim of the study was to analyze a series of Brazilian patients suffering from MELAS. METHOD: Ten patients with MELAS were studied with correlation between clinical findings, laboratorial data, electrophysiology, histochemical and molecular features. RESULTS: Blood lactate was increased in eight patients. Brain image studies revealed a stroke-like pattern in all patients. Muscle biopsy showed ralled-red fibers (RRF in 90% of patients on modified Gomori-trichrome and in 100% on succinate dehydrogenase stains. Cytochrome c oxidase stain analysis indicated deficient activity in one patient and subsarcolemmal accumulation in seven patients. Strongly succinate dehydrogenase-reactive blood vessels (SSV occurred in six patients. The molecular analysis of tRNA Leu(UUR gene by PCR/RLFP and direct sequencing showed the A3243G mutation on mtDNA in 4 patients. CONCLUSION: The muscle biopsy often confirmed the MELAS diagnosis by presence of RRF and SSV. Molecular analysis of tRNA Leu(UUR gene should not be the only diagnostic criteria for MELAS.OBJETIVO: O objetivo deste estudo foi analisar uma série de pacientes brasileiros portadores de MELAS. MÉTODO: Dez pacientes com MELAS foram estudados com correlação entre manifestações clínicas, alterações laboratoriais, estudo eletrofisiológico, histoquímico e molecular. RESULTADOS: O nível de lactato sérico estava aumentado em 8 pacientes. O estudo das imagens do crânio revelou padrão semelhante ao de AVC isquêmico em todos os pacientes. A biópsia muscular mostrou fibras rajadas vermelhas (RRF em 90% dos pacientes na coloração pelo tricrômio de Gomori modificado e em 100% na reação histoquímica pela desidrogenase succicínica (SDH. A análise da coloração pela citocromo c oxidase indicou atividade deficiente em um paciente e acúmulo subsarcolemal em sete pacientes. Vasos com forte reação para SDH (SSV ocorreram em seis pacientes. O estudo molecular do gene tRNA Leu(UUR por

  11. Observar, ouvir, compartilhar: trabalho de campo para autópsias psicossociais Watching, listening and sharing: field work for psychosocial autopsies

    Directory of Open Access Journals (Sweden)

    Maria Cecília de Souza Minayo

    2012-08-01

    Full Text Available O artigo descreve as etapas de realização do trabalho de campo da pesquisa. É possível prevenir a antecipação do fim? Suicídio de Idosos no Brasil e possibilidades de Atuação do Setor de Saúde, realizada em 10 municípios das cinco regiões do país. A amostra composta por 51 autópsias psicossociais abrangeu cinco idosos que faleceram por suicídio em nove municípios e seis em um deles. Oitenta e quatro familiares foram entrevistados. Trabalhou-se com um roteiro denominado autópsia psicossocial e com observação do contexto. Cada entrevista durou 60 minutos em média, e na maioria dos casos, houve mais de um encontro com os familiares. O estudo foi construído por meio de um processo coletivo que abrangeu compartilhamento da revisão bibliográfica, discussão do universo, das amostras, das estratégias de abordagem, dos resultados de campo e das análises empíricas. Este artigo destaca a preparação teórica, conceitual e prática dos pesquisadores; o processo de elaboração dos instrumentos para o trabalho de campo; informações sobre as fontes de dados existentes e sobre as efetivamente acessadas; apresentação de credencial institucional; entrada no contexto das famílias, dificuldades e estratégias para realização do estudo empírico; entrada e saída do campo; e impacto da pesquisa sobre os investigadores.The article describes the research realization phases of field work in ten municipalities in five regions entitled "Is it possible to prevent the anticipation of the end? Suicide among the elderly in Brazil and the possibilities for action by the Health Sector." The sample comprises 51 psychosocial autopsies of 5 elderly people who committed suicide in 9 locations and 6 in another. 84 family members were interviewed. Semi-structured psychosocial autopsies and contextual observations were used. Each interview lasted 60 minutes on average and in the majority of the cases there was more than one encounter with family

  12. Hydrogen storage development

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E. [Sandia National Labs., Livermore, CA (United States)

    1998-08-01

    A summary of the hydride development efforts for the current program year (FY98) are presented here. The Mg-Al-Zn alloy system was studied at low Zn levels (2--4 wt%) and midrange Al contents (40--60 wt%). Higher plateau pressures were found with Al and Zn alloying in Mg and, furthermore, it was found that the hydrogen desorption kinetics were significantly improved with small additions of Zn. Results are also shown here for a detailed study of the low temperature properties of Mg{sub 2}NiH{sub 4}, and a comparison made between conventional melt cast alloy and the vapor process material.

  13. Adsorption of hydrogen on clean and modified magnesium films

    DEFF Research Database (Denmark)

    Johansson, Martin; Ostenfeld, Christopher Worsøe; Chorkendorff, Ib

    2006-01-01

    The sticking of hydrogen on 400 A thick magnesium films, grown under ultrahigh vacuum conditions, have been measured under conditions relevant for hydrogen storage, i.e., elevated temperatures and pressures. A model which describes the hydrogenation and desorption kinetics of the pure magnesium f...

  14. Phase boundary of hot dense fluid hydrogen.

    Science.gov (United States)

    Ohta, Kenji; Ichimaru, Kota; Einaga, Mari; Kawaguchi, Sho; Shimizu, Katsuya; Matsuoka, Takahiro; Hirao, Naohisa; Ohishi, Yasuo

    2015-11-09

    We investigated the phase transformation of hot dense fluid hydrogen using static high-pressure laser-heating experiments in a laser-heated diamond anvil cell. The results show anomalies in the heating efficiency that are likely to be attributed to the phase transition from a diatomic to monoatomic fluid hydrogen (plasma phase transition) in the pressure range between 82 and 106 GPa. This study imposes tighter constraints on the location of the hydrogen plasma phase transition boundary and suggests higher critical point than that predicted by the theoretical calculations.

  15. High-Area-Ratio Rocket Nozzle at High Combustion Chamber Pressure: Experimental and Analytical Validation

    Science.gov (United States)

    Jankovsky, Robert S.; Smith, Timothy D.; Pavli, Albert J.

    1999-01-01

    Experimental data were obtained on an optimally contoured nozzle with an area ratio of 1025:1 and on a truncated version of this nozzle with an area ratio of 440:1. The nozzles were tested with gaseous hydrogen and liquid oxygen propellants at combustion chamber pressures of 1800 to 2400 psia and mixture ratios of 3.89 to 6.15. This report compares the experimental performance, heat transfer, and boundary layer total pressure measurements with theoretical predictions of the current Joint Army, Navy, NASA, Air Force (JANNAF) developed methodology. This methodology makes use of the Two-Dimensional Kinetics (TDK) nozzle performance code. Comparisons of the TDK-predicted performance to experimentally attained thrust performance indicated that both the vacuum thrust coefficient and the vacuum specific impulse values were approximately 2.0-percent higher than the turbulent prediction for the 1025:1 configurations, and approximately 0.25-percent higher than the turbulent prediction for the 440:1 configuration. Nozzle wall temperatures were measured on the outside of a thin-walled heat sink nozzle during the test fittings. Nozzle heat fluxes were calculated front the time histories of these temperatures and compared with predictions made with the TDK code. The heat flux values were overpredicted for all cases. The results range from nearly 100 percent at an area ratio of 50 to only approximately 3 percent at an area ratio of 975. Values of the integral of the heat flux as a function of nozzle surface area were also calculated. Comparisons of the experiment with analyses of the heat flux and the heat rate per axial length also show that the experimental values were lower than the predicted value. Three boundary layer rakes mounted on the nozzle exit were used for boundary layer measurements. This arrangement allowed total pressure measurements to be obtained at 14 different distances from the nozzle wall. A comparison of boundary layer total pressure profiles and analytical

  16. Solar hydrogen for urban trucks

    Energy Technology Data Exchange (ETDEWEB)

    Provenzano, J.: Scott, P.B.; Zweig, R. [Clean Air Now, Northridge, CA (United States)

    1997-12-31

    The Clean Air Now (CAN) Solar Hydrogen Project, located at Xerox Corp., El Segundo, California, includes solar photovoltaic powered hydrogen generation, compression, storage and end use. Three modified Ford Ranger trucks use the hydrogen fuel. The stand-alone electrolyzer and hydrogen dispensing system are solely powered by a photovoltaic array. A variable frequency DC-AC converter steps up the voltage to drive the 15 horsepower compressor motor. On site storage is available for up to 14,000 standard cubic feet (SCF) of solar hydrogen, and up to 80,000 SCF of commercial hydrogen. The project is 3 miles from Los Angeles International airport. The engine conversions are bored to 2.9 liter displacement and are supercharged. Performance is similar to that of the Ranger gasoline powered truck. Fuel is stored in carbon composite tanks (just behind the driver`s cab) at pressures up to 3600 psi. Truck range is 144 miles, given 3600 psi of hydrogen. The engine operates in lean burn mode, with nil CO and HC emissions. NO{sub x} emissions vary with load and rpm in the range from 10 to 100 ppm, yielding total emissions at a small fraction of the ULEV standard. Two trucks have been converted for the Xerox fleet, and one for the City of West Hollywood. A public outreach program, done in conjunction with the local public schools and the Department of Energy, introduces the local public to the advantages of hydrogen fuel technologies. The Clean Air Now program demonstrates that hydrogen powered fleet development is an appropriate, safe, and effective strategy for improvement of urban air quality, energy security and avoidance of global warming impact. Continued technology development and cost reduction promises to make such implementation market competitive.

  17. Hydrogen-based electrochemical energy storage

    Science.gov (United States)

    Simpson, Lin Jay

    2013-08-06

    An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.

  18. Polymers for hydrogen infrastructure and vehicle fuel systems :

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Rachel Reina; Simmons, Kevin L.; San Marchi, Christopher W.

    2013-10-01

    This document addresses polymer materials for use in hydrogen service. Section 1 summarizes the applications of polymers in hydrogen infrastructure and vehicle fuel systems and identifies polymers used in these applications. Section 2 reviews the properties of polymer materials exposed to hydrogen and/or high-pressure environments, using information obtained from published, peer-reviewed literature. The effect of high pressure on physical and mechanical properties of polymers is emphasized in this section along with a summary of hydrogen transport through polymers. Section 3 identifies areas in which fuller characterization is needed in order to assess material suitability for hydrogen service.

  19. Storage, transmission and distribution of hydrogen

    Science.gov (United States)

    Kelley, J. H.; Hagler, R., Jr.

    1979-01-01

    Current practices and future requirements for the storage, transmission and distribution of hydrogen are reviewed in order to identify inadequacies to be corrected before hydrogen can achieve its full potential as a substitute for fossil fuels. Consideration is given to the storage of hydrogen in underground solution-mined salt caverns, portable high-pressure containers and dewars, pressure vessels and aquifers and as metal hydrides, hydrogen transmission in evacuated double-walled insulated containers and by pipeline, and distribution by truck and internal distribution networks. Areas for the improvement of these techniques are indicated, and these technological deficiencies, including materials development, low-cost storage and transmission methods, low-cost, long-life metal hydrides and novel methods for hydrogen storage, are presented as challenges for research and development.

  20. Two dimensional simulation of hydrogen iodide decomposition reaction using fluent code for hydrogen production using nuclear technology

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Jung Sik [The Institute of Machinery and Electronic Technology, Mokpo National Maritime University, Mokpo (Korea, Republic of); Shin, Young Joon; Lee, Ki Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Jae Hyuk [Division of Marine Engineering System, Korea Maritime and Ocean University, Busan (Korea, Republic of)

    2015-06-15

    The operating characteristics of hydrogen iodide (HI) decomposition for hydrogen production were investigated using the commercial computational fluid dynamics code, and various factors, such as hydrogen production, heat of reaction, and temperature distribution, were studied to compare device performance with that expected for device development. Hydrogen production increased with an increase of the surface-to-volume (STV) ratio. With an increase of hydrogen production, the reaction heat increased. The internal pressure and velocity of the HI decomposer were estimated through pressure drop and reducing velocity from the preheating zone. The mass of H2O was independent of the STV ratio, whereas that of HI decreased with increasing STV ratio.

  1. Hysteresis-free nanoplasmonic pd-au alloy hydrogen sensors

    DEFF Research Database (Denmark)

    Wadell, Carl; Nugroho, Ferry Anggoro Ardy; Lidström, Emil

    2015-01-01

    hydrogen sensors. By increasing the amount of Au in the alloy nanoparticles up to 25 atom %, we are able to suppress the hysteresis between hydrogen absorption and desorption, thereby increasing the sensor accuracy to below 5% throughout the investigated 1 mbar to 1 bar hydrogen pressure range. Furthermore......, we observe an 8-fold absolute sensitivity enhancement at low hydrogen pressures compared to sensors made of pure Pd, and an improved sensor response time to below one second within the 0-40 mbar pressure range, that is, below the flammability limit, by engineering the nanoparticle size....

  2. Hydrogen Storage Performance in Pd/Graphene Nanocomposites.

    Science.gov (United States)

    Zhou, Chunyu; Szpunar, Jerzy A

    2016-10-05

    We have developed a Pd-graphene nanocomposite for hydrogen storage. The spherically shaped Pd nanoparticles of 5-45 nm in size are homogeneously distributed over the graphene matrix. This new hydrogen storage system has favorable features like desirable hydrogen storage capacity, ambient conditions of hydrogen uptake, and low temperature of hydrogen release. At a hydrogen charging pressure of 50 bar, the material could yield a gravimetric density of 6.7 wt % in the 1% Pd/graphene nanocomposite. As we increased the applied pressure to 60 bar, the hydrogen uptake capacity reached 8.67 wt % in the 1% Pd/graphene nanocomposite and 7.16 wt % in the 5% Pd/graphene nanocomposite. This system allows storage of hydrogen in amounts that exceed the capacity of the gravimetric target announced by the U.S. Department of Energy (DOE).

  3. Optimization of a solar hydrogen storage system: Exergetic considerations

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, E.; Isorna, F.; Rosa, F. [Instituto Nacional de Tecnica Aeroespacial, Ctra. S. Juan-Matalascanas, km.34, 21130 Mazagon (Huelva) (Spain)

    2007-07-15

    From production to end-users, the choice of suitable hydrogen delivery and storage systems will be essential to assure the adequate introduction and development of these facilities. This article describes the main options for hydrogen storage when produced from renewable energy, and explains different criteria to be considered in the design and building-up of stationary hydrogen storage systems, with special attention to exergy issues. An example of exergy analysis is done using data from the solar hydrogen storage facility of the Spanish Instituto Nacional de Tecnica Aeroespacial (INTA). As expected, the main conclusions of this analysis show the advantage of low pressure hydrogen in comparison with other available methods to store hydrogen. Another interesting option, from the exergy efficiency point of view, is the storage of hydrogen in metal hydride systems. The last option, and the most inefficient, is the high pressure hydrogen storage. (author)

  4. Storage of hydrogen on carbons; Stockage de l'hydrogene sur les carbones

    Energy Technology Data Exchange (ETDEWEB)

    Conard, J. [Centre National de la Recherche Scientifique, CNRS-CRMD, 45 - Orleans-la-Source (France)

    2000-07-01

    The storage of hydrogen on carbons, with densities above 10% hydrogen weight, can be used in the sector of transport. However, only the physical-sorption of this gas (which is almost perfect and boils at 20 K under atmospheric pressure) cannot explain this performance. A study of the possible sites for one hydrogen, which can take very different forms, is presented, in order to better understand the rational development of this storage mode which could reach about ten weight %. (O.M.)

  5. Advanced Palladium Membrane Scale-up for Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Emerson, Sean; Magdefrau, Neal; She, Ying; Thibaud-Erkey, Catherine

    2012-10-31

    The main objective of this project was to construct, test, and demonstrate a Pd-Cu metallic tubular membrane micro-channel separator capable of producing 2 lb day{sup -1} H{sub 2} at 95% recovery when operating downstream of an actual coal gasifier. A key milestone for the project was to complete a pilot-scale gasifier test by 1 September 2011 and demonstrate the separation of 2 lb day{sup -1} H{sub 2} to verify progress toward the DOE's goals prior to down-selection for larger-scale (100 lb day{sup -1}) hydrogen separator development. Three different pilot-scale (1.5 ft{sup 2}) separators were evaluated downstream of coal gasifiers during four different tests and the key project milestone was achieved in August 2011, ahead of schedule. During three of those tests, all of the separators demonstrated or exceeded the targeted separation rate of 2 lb day{sup -1} H{sub 2}. The separator design was proved to be leak tight and durable in the presence of gasifier exhaust contaminants at temperatures and pressures up to 500 °C and 500 psia. The contaminants in the coal gasifier syngas for the most part had negligible impact on separator performance, with H{sub 2} partial pressure being the greatest determinant of membrane performance. Carbon monoxide and low levels of H{sub 2}S (<39 ppmv) had no effect on H{sub 2} permeability, in agreement with laboratory experiments. However, higher levels of H{sub 2}S (>100 ppmv) were shown to significantly reduce H{sub 2} separation performance. The presence of trace metals, including mercury and arsenic, appeared to have no effect based on the experimental data. Subscale Pd-Cu coupon tests further quantified the impact of H{sub 2}S on irreversible sulfide formation in the UTRC separators. Conditions that have a thermodynamic driving force to form coke were found to reduce the performance of the separators, presumably by blockage of effective separation area with carbon deposits. However, it was demonstrated that both in situ

  6. Main reaction process simulation of hydrogen gas discharge in a ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... ... reactions of hydrogen discharge in small electric vacuum components at low pressure and weak ionization were confirmed. Among the 21 types of reactions in hydrogen discharge process, 11 of them play importnat roles under low pressure and weak ionization in cold cathode electric vacuum device.

  7. The hydrogen; L'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The hydrogen as an energy system represents nowadays a main challenge (in a scientific, economical and environmental point of view). The physical and chemical characteristics of hydrogen are at first given. Then, the challenges of an hydrogen economy are explained. The different possibilities of hydrogen production are described as well as the distribution systems and the different possibilities of hydrogen storage. Several fuel cells are at last presented: PEMFC, DMFC and SOFC. (O.M.)

  8. Hydrogen Uptake of DPB Getter Pellets

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L N; Schildbach, M A; Herberg, J L; Saab, A P; Weigle, J; Chinn, S C; Maxwell, R S; McLean II, W

    2008-05-30

    The physical and chemical properties of 1,4-diphenylbutadiyne (DPB) blended with carbon-supported Pd (DPB-Pd/C) in the form of pellets during hydrogenation were investigated. A thermogravimetric analyzer (TGA) was employed to measure the kinetics of the hydrogen uptake by the DPB getter pellets. The kinetics obtained were then used to develop a semi-empirical model, based on gas diffusion into solids, to predict the performance of the getter pellets under various conditions. The accuracy of the prediction model was established by comparing the prediction models with independent experimental data on hydrogen pressure buildup in sealed systems containing DPB getter pellets and subjected to known rates of hydrogen input. The volatility of the hydrogenated DPB products and its effects on the hydrogen uptake kinetics were also analyzed.

  9. Liquid Metallic Hydrogen: A Building Block for the Liquid Sun

    OpenAIRE

    Robitaille P.-M.

    2011-01-01

    Liquid metallic hydrogen provides a compelling material for constructing a condensed matter model of the Sun and the photosphere. Like diamond, metallic hydrogen might have the potential to be a metastable substance requiring high pressures for forma- tion. Once created, it would remain stable even at lower pressures. The metallic form of hydrogen was initially conceived in 1935 by Eugene Wigner and Hillard B. Huntington who indirectly anticipated its elevated critical temper...

  10. Carbon Nanotubes–A Successful Hydrogen Storage Medium

    OpenAIRE

    Vijaya Ilango; Avika Gupta

    2013-01-01

    Hydrogen fuel is a zero-emission fuel which uses electrochemical cells or combustion in internal engines, to power vehicles and electric devices. Methods of hydrogen storage for subsequent use span many approaches, including high pressures, cryogenics and chemical compounds that reversibly release H2 upon heating. Most research into hydrogen storage is focused on storing hydrogen as a lightweight, compact energy carrier for mobile applications. With the accelerating demand for cleaner and m...

  11. Study on hydrogen absorption/desorption properties of uranium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroshi; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1996-10-01

    Hydrogen absorption/desorption properties of two U-Mn intermetallic compounds, U{sub 6}Mn and UMn{sub 2}, were investigated. U{sub 6}Mn absorbed hydrogen and the hydrogen desorption pressure of U{sub 6}Mn obtained from this experiment was higher than that of U, which was considered to be the effect of alloying, whereas UMn{sub 2} was not observed to absorb hydrogen up to 50 atm at room temperature. (author)

  12. DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Lueking, Angela D.; Li, Qixiu; Badding, John V.; Fonseca, Dania; Gutierrez, Humerto; Sakti, Apurba; Adu, Kofi; Schimmel, Michael

    2010-03-31

    Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

  13. HYDROGEN AND ITS DESORPTION IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    HSEUH,H.C.

    2002-11-11

    Hydrogen is the dominating gas specie in room temperature, ultrahigh vacuum systems of particle accelerators and storage rings, such as the Relativistic Heavy Ion Collider (RHIC) at Brookhaven. Rapid pressure increase of a few decades in hydrogen and other residual gases was observed during RHIC's recent high intensity gold and proton runs. The type and magnitude of the pressure increase were analyzed and compared with vacuum conditioning, beam intensity, number of bunches and bunch spacing. Most of these pressure increases were found to be consistent with those induced by beam loss and/or electron stimulated desorption from electron multipacting.

  14. Discrepâncias clínico-patológicas e achados cardiovasculares em 409 autópsias consecutivas Clinical and pathological discrepancies and cardiovascular findings in 409 consecutive autopsies

    Directory of Open Access Journals (Sweden)

    Aline Fusco Fares

    2011-12-01

    Full Text Available FUNDAMENTO: As discrepâncias entre os diagnósticos clínicos e em autópsia persistem em todo o mundo. OBJETIVO: Avaliamos as autópsias em um hospital-escola para analisar a precisão dos diagnósticos cardiovasculares clínicos em comparação aos achados post-mortem. MÉTODOS: As 409 autópsias consecutivas entre 2003 e 2006 foram analisadas em um hospital terciário de São José do Rio Preto, São Paulo (SP, Brasil. A comparação dos achados cardiovasculares clínicos e patológicos foi realizada por meio da classificação de discrepâncias de Goldman. RESULTADOS: A taxa de autópsia no hospital foi de 8%. As causas cardiovasculares de óbito representavam 42,8% (175 de 409 pacientes dos diagnósticos de autópsia. Em 98 pacientes (56%, houve discrepâncias significativas (classes I e II, o que representa uma grande proporção de diagnósticos equivocados de infarto mesentérico (84,6%, infarto agudo do miocárdio (64,7%, dissecção da aorta (64,2% e embolia pulmonar (62,5%. Foram observadas maiores taxas de concordância para a insuficiência cardíaca congestiva (59% e para o acidente vascular cerebral isquêmico agudo (58,8%. A idade, o sexo, o tempo de permanência e a última unidade de admissão no hospital não foram associados aos critérios de Goldman. CONCLUSÃO: As discrepâncias dos diagnósticos clínicos e em autópsia relativos à morte cardiovascular permanecem elevados no Brasil, a despeito dos recursos tecnológicos disponíveis. Além disso, nossos achados reforçam a importância do exame post-mortem como uma contribuição para a melhoria da assistência médica.BACKGROUND: Discrepancies between clinical and autopsy diagnoses persists worldwide. OBJECTIVE: We evaluated autopsies in a university hospital in order to assess the accuracy of clinical cardiovascular diagnosis compared to postmortem findings. METHODS: Four hundred nine consecutive autopsies between 2003 and 2006 were analyzed in a tertiary-care hospital

  15. O decréscimo vertiginoso das autópsias em um hospital universitário do Brasil nos últimos 20 anos The dramatic decline of the autopsies at a Brazilian university hospital in the last 20 years

    Directory of Open Access Journals (Sweden)

    Fabiana Resende Rodrigues

    2011-08-01

    Full Text Available INTRODUÇÃO: O declínio no número de autópsias em hospitais e instituições universitárias é evento amplamente reportado, inicialmente em países do primeiro mundo e posteriormente em muitos países em desenvolvimento, como o Brasil. As causas para essa tendência são múltiplas e complexas, incluindo aspectos religiosos, familiares e médicos. Entre estes últimos, salientam-se razões diagnósticas, caracterizadas pelo significativo avanço tecnológico na imagenologia, com a suposição de que todos os diagnósticos agora podem ser feitos em vida, e a crescente ansiedade de processos judiciais contra médicos por má prática. OBJETIVO: Demonstrar o decréscimo vertiginoso e drástico do número de autópsias em um hospital universitário no Brasil. MATERIAL E MÉTODO: Avaliou-se o número de registros nos livros de autópsias consecutivas realizadas no Departamento de Patologia do Hospital Universitário Antonio Pedro da Universidade Federal Fluminense (HUAP/UFF, Niterói, Rio de Janeiro, criando um banco dados em tabela do programa Microsoft Excel. RESULTADOS: Durante os anos 1966 a 2009, foram realizadas 23.813 necrópsias, sendo 12.702 de adultos e 11.111 de fetos. Entre os anos 1966 e 1998, foram realizadas mais necrópsias, no total de 23.321, sendo 12.482 de adultos e 10.839 de fetos. Já entre os anos 1999 e 2009, foi observado o declínio acentuado e drástico das mesmas, totalizando apenas 492 necrópsias, sendo 220 de adultos e 272 de fetos. CONCLUSÃO: Acreditamos que a principal causa para esse declínio é a pouca informação da população, que desconhece que o saber é fruto de estudo, pesquisa, prática e aprimoramento.INTRODUCTION: The decline in the number of autopsies at hospitals and university hospitals has been widely reported, initially in developed countries and afterwards in several developing countries including Brazil. The causes for this trend are multiple and complex, encompassing religious, family and

  16. Colonic hydrogen sulfide produces portal hypertension and systemic hypotension in rats.

    Science.gov (United States)

    Huc, Tomasz; Jurkowska, Halina; Wróbel, Maria; Jaworska, Kinga; Onyszkiewicz, Maksymilian; Ufnal, Marcin

    2017-01-01

    Hydrogen sulfide, a toxic gas, at low concentrations is also a biological mediator in animals. In the colon, hydrogen sulfide is produced by intestinal tissues and gut sulfur bacteria. Gut-derived molecules undergo liver metabolism. Portal hypertension is one of the most common complications contributing to the high mortality in liver cirrhosis. We hypothesized that the colon-derived hydrogen sulfide may affect portal blood pressure. Sprague-Dawley rats were maintained either on tap water (controls) or on water solution of thioacetamide to produce liver cirrhosis (CRH-R). Hemodynamics were measured after administration of either saline or Na2S, a hydrogen sulfide donor, into (1) the colon, (2) the portal vein, or (3) the femoral vein. Expression of enzymes involved in hydrogen sulfide metabolism was measured by RT-PCR. CRH-R showed a significantly higher portal blood pressure but a lower arterial blood pressure than controls. Saline did not affect hemodynamic parameters. In controls, intracolonic hydrogen sulfide decreased arterial blood pressure and portal blood flow but increased portal blood pressure. Similarly, hydrogen sulfide administered into the portal vein decreased arterial blood pressure but increased portal blood pressure. In contrast, hydrogen sulfide administered into the systemic vein decreased both arterial and portal blood pressures. CRH-R showed significantly greater responses to hydrogen sulfide than controls. CRH-R had a significantly higher liver concentration of hydrogen sulfide but lower expression of rhodanese, an enzyme converting hydrogen sulfide to sulfate. In conclusion, colon-administered hydrogen sulfide increases portal blood pressure while decreasing the systemic arterial blood pressure. The response to hydrogen sulfide is more pronounced in cirrhotic rats which show reduced hydrogen sulfide liver metabolism. Therefore, colon-derived hydrogen sulfide may be involved in the regulation of portal blood pressure, and may contribute to

  17. Estudo da biópsia por agulha cortante no diagnóstico histopatológico de lesões bucais = Cutting needle biopsy study in histopathological diagnosis of oral lesions

    Directory of Open Access Journals (Sweden)

    Braga, Ana Maria Corrêa

    2005-01-01

    Full Text Available Objetivo: Estudar a eficácia da biópsia por agulha cortante (BAC no diagnóstico de lesões bucais localizadas em tecidos moles, indicadas para biópsia incisional ou excisional, em 21 pacientes, de ambos os sexos, com idades entre 18 e 80 anos. Materiais e métodos: Para a realização das biópsias foi utilizada uma agulha cortante de 18 Ga × 9 cm. Cada peça foi submetida a três disparos com a agulha obtendo-se três espécimes que após o processamento laboratorial, originaram três lâminas. Para as análises histopatológicas elaborou-se um questionário contendo duas perguntas sobre o diagnóstico dos espécimes que foi aplicado em dois momentos diferentes, com e sem a história clínica. As respostas do questionário, em ambas as etapas, foram comparadas com os diagnósticos conclusivos das peças cirúrgicas removidas anteriormente. Resultados: Os resultados foram elaborados conforme uma escala de valores e submetidos à análise estatística de McNemar, a um nível de significância de 5%. O número de acertos dos diagnósticos específicos obtidos com os espécimes da agulha cortante foi estatisticamente superior em relação ao número de erros. Observou-se também que o número de acertos foi maior quando o examinador respondeu ao questionário com o conhecimento da história clínica. Conclusão: A biópsia por agulha cortante mostrou-se eficaz na elaboração do diagnóstico histopatológico de lesões bucais

  18. Hydrogen local vibrational modes in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    McCluskey, Matthew D. [Univ. of California, Berkeley, CA (United States). Dept. of Physics

    1997-06-01

    Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.

  19. Hydrogen Car Cartridges: A New Strategy for Hydrogen Storage, Delivering and Refueling

    Energy Technology Data Exchange (ETDEWEB)

    Prosini, Pier Paolo

    2007-07-01

    The purpose of the project is to introduce a sustainable model in the automotive field, guarantying the Kyoto agreements. The aim of the project is to develop an innovative hydrogen tank able to power an hydrogen fuel cell car with the same performance of liquid fuelled cars. Most of the system performance are expected to satisfy the Department of Energy (DOE) goals for 2015. The hydrogen releasing system is based on solid NaBH4 which is hydrolyzed with water or steam to obtain hydrogen. Sodium borate is obtained as by-product and it has to be recycled. Pure and humidified hydrogen, ready to be utilized in a fuel cell, is obtained by a simple and sure way. Hydrogen is produced only when it is requested and therefore there is never pressurized hydrogen or hydrogen overproduction The system works at atmospheric pressure avoiding the problems related to handling and storing pressurized gas. The car fuelling could be performed in area like the present service stations. The used cartridges can be removed and substituted by new cartridges. Contemporarily a water tank should be refilled. To improve the total energetic yield it was also proposed a NaBH4 regeneration process directly starting from the products of hydrolysis. (auth)

  20. Metallic hydrogen: The most powerful rocket fuel yet to exist

    Energy Technology Data Exchange (ETDEWEB)

    Silvera, Isaac F [Lyman Laboratory of Physics, Harvard University, Cambridge MA 02138 (United States); Cole, John W, E-mail: silvera@physics.harvard.ed [NASA MSFC, Huntsville, AL 35801 (United States)

    2010-03-01

    Wigner and Huntington first predicted that pressures of order 25 GPa were required for the transition of solid molecular hydrogen to the atomic metallic phase. Later it was predicted that metallic hydrogen might be a metastable material so that it remains metallic when pressure is released. Experimental pressures achieved on hydrogen have been more than an order of magnitude higher than the predicted transition pressure and yet it remains an insulator. We discuss the applications of metastable metallic hydrogen to rocketry. Metastable metallic hydrogen would be a very light-weight, low volume, powerful rocket propellant. One of the characteristics of a propellant is its specific impulse, I{sub sp}. Liquid (molecular) hydrogen-oxygen used in modern rockets has an Isp of {approx}460s; metallic hydrogen has a theoretical I{sub sp} of 1700s. Detailed analysis shows that such a fuel would allow single-stage rockets to enter into orbit or carry economical payloads to the moon. If pure metallic hydrogen is used as a propellant, the reaction chamber temperature is calculated to be greater than 6000 K, too high for currently known rocket engine materials. By diluting metallic hydrogen with liquid hydrogen or water, the reaction temperature can be reduced, yet there is still a significant performance improvement for the diluted mixture.

  1. Silane plus molecular hydrogen as a possible pathway to metallic hydrogen.

    Science.gov (United States)

    Yao, Yansun; Klug, Dennis D

    2010-12-07

    The high-pressure behavior of silane, SiH(4), plus molecular hydrogen was investigated using a structural search method and ab initio molecular dynamics to predict the structures and examine the physical origin of the pressure-induced drop in hydrogen intramolecular vibrational (vibron) frequencies. A structural distortion is predicted at 15 GPa from a slightly strained fcc cell to a rhombohedral cell that involves a small volume change. The predicted equation of state and the pressure-induced drop in the hydrogen vibron frequencies reproduces well the experimental data (Strobel TA, Somayazulu M, Hemley RJ (2009) Phys Rev Lett 103:065701). The bond weakening in H(2) is induced by intermolecular interactions between the H(2) and SiH(4) molecules. A significant feature of the high-pressure structures of SiH(4)(H(2))(2) is the dynamical behavior of the H(2) molecules. It is found that H(2) molecules are rotating in this pressure range whereas the SiH(4) molecules remain rigid. The detailed nature of the interactions of molecular hydrogen with SiH(4) in SiH(4)(H(2))(2) is therefore strongly influenced by the dynamical behavior of the H(2) molecules in the high-pressure structure. The phase with the calculated structure is predicted to become metallic near 120 GPa, which is significantly lower than the currently suggested pressure for metallization of bulk molecular hydrogen.

  2. Steady-state plant model to predict hydrogen levels in power plant components

    Science.gov (United States)

    Glatzmaier, Greg C.; Cable, Robert; Newmarker, Marc

    2017-06-01

    The National Renewable Energy Laboratory (NREL) and Acciona Energy North America developed a full-plant steady-state computational model that estimates levels of hydrogen in parabolic trough power plant components. The model estimated dissolved hydrogen concentrations in the circulating heat transfer fluid (HTF), and corresponding partial pressures within each component. Additionally for collector field receivers, the model estimated hydrogen pressure in the receiver annuli. The model was developed to estimate long-term equilibrium hydrogen levels in power plant components, and to predict the benefit of hydrogen mitigation strategies for commercial power plants. Specifically, the model predicted reductions in hydrogen levels within the circulating HTF that result from purging hydrogen from the power plant expansion tanks at a specified target rate. Our model predicted hydrogen partial pressures from 8.3 mbar to 9.6 mbar in the power plant components when no mitigation treatment was employed at the expansion tanks. Hydrogen pressures in the receiver annuli were 8.3 to 8.4 mbar. When hydrogen partial pressure was reduced to 0.001 mbar in the expansion tanks, hydrogen pressures in the receiver annuli fell to a range of 0.001 mbar to 0.02 mbar. When hydrogen partial pressure was reduced to 0.3 mbar in the expansion tanks, hydrogen pressures in the receiver annuli fell to a range of 0.25 mbar to 0.28 mbar. Our results show that controlling hydrogen partial pressure in the expansion tanks allows us to reduce and maintain hydrogen pressures in the receiver annuli to any practical level.

  3. Safety analysis of high pressure gasous fuel container punctures

    Energy Technology Data Exchange (ETDEWEB)

    Swain, M.R. [Univ. of Miami, Coral Gables, FL (United States)

    1995-09-01

    The following report is divided into two sections. The first section describes the results of ignitability tests of high pressure hydrogen and natural gas leaks. The volume of ignitable gases formed by leaking hydrogen or natural gas were measured. Leaking high pressure hydrogen produced a cone of ignitable gases with 28{degrees} included angle. Leaking high pressure methane produced a cone of ignitable gases with 20{degrees} included angle. Ignition of hydrogen produced larger overpressures than did natural gas. The largest overpressures produced by hydrogen were the same as overpressures produced by inflating a 11 inch child`s balloon until it burst.

  4. Contaminação tumoral em trajeto de biópsia de tumores ósseos malignos primários Tumor contamination in the biopsy path of primary malignant bone tumors

    Directory of Open Access Journals (Sweden)

    Marcelo Parente Oliveira

    2012-10-01

    Full Text Available OBJETIVO: Estudar os fatores possivelmente associados à contaminação tumoral do trajeto de biópsia de tumores ósseos malignos primários. MÉTODO: Foram estudados, retrospectivamente, 35 pacientes submetidos a tratamento cirúrgico com diagnóstico de osteossarcoma, tumor de Ewing e condrossarcoma. A amostra foi analisada para caracterização quanto à técnica de biópsia empregada, tipo histológico do tumor, realização de quimioterapia neoadjuvante, ocorrência de recidiva local e contaminação tumoral no trajeto da biópsia. RESULTADOS: Nos 35 pacientes avaliados ocorreram quatro contaminações (11,43%. Um caso era de osteossarcoma, dois casos de tumor de Ewing e um caso de condrossarcoma, não se observando associação entre o tipo de tumor e a presença de contaminação tumoral no trajeto da biópsia (p = 0,65. Também não se observou associação entre a presença de contaminação tumoral e a técnica de biópsia (p = 0,06. Por outro lado, observou-se associação entre a presença de contaminação tumoral e a ocorrência de recidiva local (p = 0,01 e entre a presença de contaminação e a não realização de quimioterapia neoadjuvante (p = 0,02. CONCLUSÃO: A contaminação tumoral no trajeto de biópsia de tumores ósseos malignos primários esteve associada à ocorrência de recidiva local. Por outro lado, não mostrou ser influenciada pelo tipo de biópsia realizada e pelo tipo histológico de tumor estudado. A quimioterapia neoadjuvante mostrou um efeito protetor contra esta complicação. A despeito desses achados, a contaminação tumoral é uma complicação que deve sempre ser considerada, sendo recomendada a remoção do trajeto da biópsia na cirurgia de ressecção do tumor.OBJECTIVE: To study factors possibly associated with tumor contamination in the biopsy path of primary malignant bone tumors. METHOD: Thirty-five patients who underwent surgical treatment with diagnoses of osteosarcoma, Ewing's tumor and

  5. Hydrogen Storage in Single-Walled Carbon Nanotubes at Room Temperature

    National Research Council Canada - National Science Library

    C. Liu; Y. Y. Fan; M. Liu; H. T. Cong; H. M. Cheng; M. S. Dresselhaus

    1999-01-01

    .... A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a modestly high pressure (about 10 megapascal...

  6. Stability of Metallic Hydrogen at Ambient Conditions

    OpenAIRE

    Ackland, Graeme J.

    2017-01-01

    The possibility of metallic hydrogen was first mooted by Wigner and Huntington in 1935. Here it is show that the calculations from that paper are in remarkably good agreement with modern density functional theory results. The possibility that metallic hydrogen could be recovered to ambient pressure is often attributed to papers by Brovman, although in fact they only say it would be metastable with undetermined lifetime. Density functional theory calculations presented here show that reasonabl...

  7. Stereoselective thymol hydrogenation. I. Kinetics of thymol hydrogenation on charcoal-supported platinum catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Besson, M.; Bullivant, L.; Nicolaus, N.; Gallezot, P. (Institut de Recherches sur la Catalyse-CNRS, Villeurbanne (France))

    1993-03-01

    The kinetics of thymol hydrogenation on a well-characterized supported platinum catalyst have been investigated in cyclohexane at temperatures between 313 and 373 K and under 3 MPa of hydrogen pressure. The relative rate constants of the different reaction pathways (hydrogenation via menthone or isomenthone, and direct hydrogenation to the four menthol diastereoisomers) were determined from the changes in composition of the reaction medium during the reaction process. It has been shown that hydrogenation via the menthone intermediates is the major route, the formation of the cis isomer (isomenthone) being favored. The configuration of the menthols, produced from direct hydrogenation or from the ketone intermediates, is controlled by the geometry of adsorption of the precursors on the metal surface, so that neoisomenthol with all substituents in the cis position is by far the most abundant steroisomer produced. 21 refs., 11 figs., 2 tabs.

  8. Metallization of fluid hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Nellis, W.J.; Louis, A.A.; Ashcroft, N.W.

    1997-05-14

    The electrical activity of liquid hydrogen has been measured at the high dynamic pressures, and temperatures that can be achieved with a reverberating shock wave. The resulting data are most naturally interpreted in terms of a continuous transition from a semiconducting to a metallic, largely diatomic fluid, the latter at 140 CPa, (ninefold compression) and 3000 K. While the fluid at these conditions resembles common liquid metals by the scale of its resistivity of 500 micro-ohm-cm, it differs by retaining a strong pairing character, and the precise mechanism by which a metallic state might be attained is still a matter of debate. Some evident possibilities include (i) physics of a largely one-body character, such as a band-overlap transition, (ii) physics of a strong-coupling or many-body character,such as a Mott-Hubbard transition, and (iii) process in which structural changes are paramount.

  9. Towards hydrogen metallization: an Ab initio approach; Vers la metallisation de l`hydrogene: approche AB initio

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, St

    1998-12-31

    The quest for metallic hydrogen is a major goal for both theoretical and experimental condensed matter physics. Hydrogen and deuterium have been compressed up to 200 GPa in diamond anvil cells, without any clear evidence for a metallic behaviour. Loubeyere has recently suggested that hydrogen could metallize, at pressures within experimental range, in a new Van der Waals compound: Ar(H{sub 2}){sub 2} which is characterized at ambient pressure by an open and anisotropic sublattice of hydrogen molecules, stabilized by an argon skeleton. This thesis deals with a detailed ab initio investigation, by Car-Parrinello molecular dynamics methods, of the evolution under pressure of this compound. In a last chapter, we go to much higher pressures and temperatures, in order to compare orbital and orbital free ab initio methods for the dense hydrogen plasma. (author) 109 refs.

  10. Stool examination and rectal biopsy in the diagnosis and evaluation of therapy of schistosomiasis mansoni Exame de fezes e biópsia retal no diagnóstico e controle de cura da esquistossomose mansoni

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Teles Rabello

    1992-12-01

    Full Text Available From each of a group of 217 adult males selected through enzyme-immunoassay or skin-test (Group A, six stool samples were examined by both the Lutz/Hoffman, Pons & Janer (Lutz/HPJ and Kato/Katz methods. In addition, one oogram of the rectal mucosa was performed. By these methods, schistosomiasis was detected in 44.7%, 47.5% and 40.1% of the individuals respectively. To evaluate the methods in the assessment of cure, the last 40 patients from group A, treated with a single oral dose of oxamniquine at 15 mg/kg were followed up for six months (Group B. The criteria for parasitological cure included three stool examinations by Kato/Katz and Lutz/HPJ methods, one, three and six months post-treatment and a rectal biopsy between the fourth and sixth months post-treatment. The examinations were negative in 87.5%, 90% and 95% of the patients, respectively. The efficacy of oxamniquine was 82.5% when the three methods were considered together and there was no statistically significant difference between the sensitivity of the individual methods.Em um grupo de 217 adultos do sexo masculino selecionados através de ELISA ou intradermoreação, realizaram-se seis exames de fezes pelos métodos de Lutz/Hoffman, Pons e Janer (Lutz/HPJ e Kato/Katz e um oograma da mucosa retal, observando-se positividade em 44,7%, 47,5% e 40,1%, respectivamente. A análise comparativa dos resultados mostrou: 1 aumento da sensibilidade de ambos os métodos de exames de fezes até a terceira amostra examinada; 2 maior sensibilidade da biópsia retal quando comparada ao exame de uma única amostra fecal pelos métodos de Lutz/HPJ ou Kato/Katz; 3 igual sensibilidade pelo exame de duas a cinco amostras fecais pelo método de Kato/Katz ou duas a seis amostras pelo método de Lutz/HPJ e a biópsia retal; 4 sensibilidade superior de seis amostras fecais pelo método de Kato/Katz, quando comparado à biópsia retal; 5 igual sensibilidade entre o mesmo número de amostras examinadas pelos

  11. Influência do tempo e do meio de transporte no isolamento de fungos patogênicos de biópsias de pele Effects of time delay and transportation on isolation of pathogenic fungi from skin biopsies

    Directory of Open Access Journals (Sweden)

    Rafael Taglialegna

    2008-04-01

    Full Text Available FUNDAMENTOS: Não está definido como o meio de transporte e o intervalo de tempo até o processamento final interferem no isolamento de fungos patogênicos em material obtido de biópsias de pele. OBJETIVOS: Determinar o efeito da inoculação tardia de biópsias de pele, transportadas em diferentes meios líquidos, na taxa de isolamento de fungos patogênicos. MÉTODOS: De 47 pacientes com lesões cutâneas suspeitas de micoses invasivas obtiveram-se 278 biópsias das lesões. Cada biópsia foi transportada em frascos com caldo Sabouraud com cloranfenicol ou solução salina de cloreto de sódio e inoculada em ágar Sabouraud após 48-72 horas (precoce ou após 72 horas até sete dias (tardio, constituindo-se quatro grupos de estudo. RESULTADOS: As medianas das taxas de isolamento dos quatro grupos de esporotricose foram 100% e de paracoccidioidomicose foram 84% e 50% nos grupos precoces/solução salina ou caldo Sabouraud e 64% e 84% nos grupos tardios/solução salina ou caldo Sabouraud, respectivamente (p=0,88. Baixas taxas de contaminação resultaram em especificidade diagnóstica de 82% para doenças não fúngicas. CONCLUSÕES: Biópsias de pele podem ser transportadas em caldo Sabouraud ou solução salina por períodos de até sete dias, à temperatura ambiente, sem afetar a viabilidade dos fungos.BACKGROUND: It is not clear how culture media used during transport and the interval between the biopsy procedure and final processing can affect the successful isolation of fungi. OBJECTIVE: The aim of this study was to investigate the effects of late inoculation of skin biopsies, transported in different sterile fluids, on the isolation rate of pathogenic fungi. METHODS: A total of 278 punch biopsy specimens were collected from 47 patients with suspected lesions of invasive mycoses. Each biopsy was transported in vials with Sabouraud medium with chloramphenicol or saline solution and finally inoculated on Sabouraud agar and 2

  12. Solubility of hydrogen sulfide in n-methylpyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Yarym-Agaev, N.L.; Matvienko, V.G.; Povalyaeva, N.V.

    1980-01-01

    The solubility of hydrogen sulfide in N-methylpyrrolidone was investigated over wide ranges of temperature and pressure. The dynamic variant of the gravimetric method was used at hydrogen sulfide pressures equal to or below atmospheric, and the static variant at higher pressures. In the dynamic variant of the gravimetric method hydrogen sulfide is passed through a known amount of solvent until saturation is reached, and the amount of gas dissolved is found from the weight increase. This method is particularly convenient in studies of highly soluble gases when the solvent has a low vapor pressure. If the vapor pressure of the solvent exceeded this value a correction for entrainment of solvent vapor by undissolved gas was applied. The study showed that the solubility of hydrogen sulfide in N-methylpyrrolidone rose steeply with increase of pressure and decrease of temperature and that it can be used as an effective absorbent of hydrogen sulfide in highly sulfurous natural gas. Since the solubility of hydrogen sulfide under atmospheric pressure is fairly high even at elevated temperatures, effective regeneration of N-methylpyrrolidone is possible by a combination of heating and blowing with an inert gas or by application of vacuum for removal of the hydrogen sulfide.

  13. Large-scale hydrogen liquefaction in Germany

    Energy Technology Data Exchange (ETDEWEB)

    Bracha, M.; Lorenz, G.; Patzelt, A.; Wanner, M. (Linde AG, Hoellriegelskreuth (Germany))

    1994-01-01

    To cover the demand of a steadily rising LH[sub 2] market, Linde has erected an industrial-scale hydrogen supply and liquefaction plant at Ingolstadt near Munich. It is located at a refinery site, where it utilizes hydrogen-rich waste gas. The liquefier has a daily liquefaction capacity of 4.4 tons and is based on a Claude process with nitrogen precooling. Apart from the liquefier, the whole plant comprises a PSA purification, a high-pressure hydrogen compressor station, a LH[sub 2] storage tank and filling stations for GH[sub 2] and LH[sub 2] trailers. (author)

  14. Liquefaction chemistry and kinetics: Hydrogen utilization studies

    Energy Technology Data Exchange (ETDEWEB)

    Rothenberger, K.S.; Warzinski, R.P.; Cugini, A.V. [Pittsburgh Energy Technology Center, PA (United States)] [and others

    1995-12-31

    The objectives of this project are to investigate the chemistry and kinetics that occur in the initial stages of coal liquefaction and to determine the effects of hydrogen pressure, catalyst activity, and solvent type on the quantity and quality of the products produced. The project comprises three tasks: (1) preconversion chemistry and kinetics, (2) hydrogen utilization studies, and (3) assessment of kinetic models for liquefaction. The hydrogen utilization studies work will be the main topic of this report. However, the other tasks are briefly described.

  15. Highly hydrogenated graphene via active hydrogen reduction of graphene oxide in the aqueous phase at room temperature.

    Science.gov (United States)

    Sofer, Zdeněk; Jankovský, Ondřej; Šimek, Petr; Soferová, Lýdie; Sedmidubský, David; Pumera, Martin

    2014-02-21

    Hydrogenated graphene and graphane are in the forefront of graphene research. Hydrogenated graphene is expected to exhibit ferromagnetism, tunable band gap, fluorescence, and high thermal and low electrical conductivity. Currently available techniques for fabrication of highly hydrogenated graphene use either a liquid ammonia (-33 °C) reduction pathway using alkali metals or plasma low pressure or ultra high pressure hydrogenation. These methods are either technically challenging or pose inherent risks. Here we wish to demonstrate that highly hydrogenated graphene can be prepared at room temperature in the aqueous phase by reduction of graphene oxide by nascent hydrogen generated by dissolution of metal in acid. Nascent hydrogen is known to be a strong reducing agent. We studied the influence of metal involved in nascent hydrogen generation and characterized the samples in detail. The resulting reduced graphenes and hydrogenated graphenes were characterized in detail. The resulting hydrogenated graphene had the chemical formula C1.16H1O0.66. Such simple hydrogenation of graphene is of high importance for large scale safe synthesis of hydrogenated graphene.

  16. Thermochemical properties of the hydrogen getter DEB

    Energy Technology Data Exchange (ETDEWEB)

    Balooch, M.; LeMay, J.D. [Lawrence Livermore National Lab., CA (United States); Wang, W.-E. [Department of Nuclear Engineering, 4164 Etcheverry Hall, University of California, Berkeley, CA 94720-1730 (United States)

    1999-04-20

    Vapor pressures of the hydrogen getter 1,4 bis(phenylethynyl)benzene (DEB), together with two of its derivatives namely DEB mixed with carbon-supported Pd (DEB-Pd/C) and hydrogenated DEB-Pd/C, are measured from room temperature to the melting temperature (179 C). The corresponding thermodynamic information, such as the enthalpy of vaporization, boiling point, and the deviation from ideal solution behavior of DEB-Pd/C, has been derived from the vapor pressure-temperature relationships. In addition, the hydrogenation kinetics of DEB-Pd/C (powder form and rod-like) has also been investigated at a fixed pressure of 13.3 Pa (0.1 Torr) and at four temperatures, 21 C, 35 C, 45 C and 55 C. (orig.) 5 refs.

  17. A hydrogen ice cube

    NARCIS (Netherlands)

    Peters, C.J.; Schoonman, J.; Schrauwers, A.

    2004-01-01

    Hydrogen is considered to be a highly promising energy carrier. Nonetheless, before hydrogen can become the fuel of choice for the future a number of slight problems will have to be overcome. For example, how can hydrogen be safely stored? Motor vehicles running on hydrogen may be clean in concept

  18. PNNL Development and Analysis of Material-Based Hydrogen Storage Systems for the Hydrogen Storage Engineering Center of Excellence

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Kriston P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Alvine, Kyle J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Kenneth I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Klymyshyn, Nicholas A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pires, Richard P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ronnebro, Ewa [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Simmons, Kevin L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weimar, Mark R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westman, Matthew P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-02-29

    The Hydrogen Storage Engineering Center of Excellence is a team of universities, industrial corporations, and federal laboratories with the mandate to develop lower-pressure, materials-based, hydrogen storage systems for hydrogen fuel cell light-duty vehicles. Although not engaged in the development of new hydrogen storage materials themselves, it is an engineering center that addresses engineering challenges associated with the currently available hydrogen storage materials. Three material-based approaches to hydrogen storage are being researched: 1) chemical hydrogen storage materials 2) cryo-adsorbents, and 3) metal hydrides. As a member of this Center, Pacific Northwest National Laboratory (PNNL) has been involved in the design and evaluation of systems developed with each of these three hydrogen storage materials. This report is a compilation of the work performed by PNNL for this Center.

  19. Capacity retention in hydrogen storage alloys

    Science.gov (United States)

    Anani, A.; Visintin, A.; Srinivasan, S.; Appleby, A. J.; Reilly, J. J.; Johnson, J. R.

    1992-01-01

    Results of our examination of the properties of several candidate materials for hydrogen storage electrodes and their relation to the decrease in H-storage capacity upon open-circuit storage over time are reported. In some of the alloy samples examined to date, only about 10 percent of the hydrogen capacity was lost upon storage for 20 days, while in others, this number was as high as 30 percent for the same period of time. This loss in capacity is attributed to two separate mechanisms: (1) hydrogen desorbed from the electrode due to pressure differences between the cell and the electrode sample; and (2) chemical and/or electrochemical degradation of the alloy electrode upon exposure to the cell environment. The former process is a direct consequence of the equilibrium dissociation pressure of the hydride alloy phase and the partial pressure of hydrogen in the hydride phase in equilibrium with that in the electrolyte environment, while the latter is related to the stability of the alloy phase in the cell environment. Comparison of the equilibrium gas-phase dissociation pressures of these alloys indicate that reversible loss of hydrogen capacity is higher in alloys with P(eqm) greater than 1 atm than in those with P(eqm) less than 1 atm.

  20. Pressure Dome for High-Pressure Electrolyzer

    Science.gov (United States)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  1. Safety aspects of large-scale combustion of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Edeskuty, F.J.; Haugh, J.J.; Thompson, R.T.

    1986-01-01

    Recent hydrogen-safety investigations have studied the possible large-scale effects from phenomena such as the accumulation of combustible hydrogen-air mixtures in large, confined volumes. Of particular interest are safe methods for the disposal of the hydrogen and the pressures which can arise from its confined combustion. Consequently, tests of the confined combustion of hydrogen-air mixtures were conducted in a 2100 m/sup 3/ volume. These tests show that continuous combustion, as the hydrogen is generated, is a safe method for its disposal. It also has been seen that, for hydrogen concentrations up to 13 vol %, it is possible to predict maximum pressures that can occur upon ignition of premixed hydrogen-air atmospheres. In addition information has been obtained concerning the survivability of the equipment that is needed to recover from an accident involving hydrogen combustion. An accident that involved the inadvertent mixing of hydrogen and oxygen gases in a tube trailer gave evidence that under the proper conditions hydrogen combustion can transit to a detonation. If detonation occurs the pressures which can be experienced are much higher although short in duration.

  2. High Pressure Supersonic Gas Jet Fueling on NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Soukhanovskii, V; Bell, M; Blanchard, W; Dong, J; Gernhardt, R; Kaita, R; Kugel, H; Provost, T; Roquemore, A; Sichta, P

    2007-06-25

    A supersonic gas injector (SGI) has been developed for fueling and diagnostic applications on NSTX. The SGI is comprised of a small de Laval converging-diverging graphite nozzle, a commercial piezoelectric gas valve, and a diagnostic package, all mounted on a movable probe at a low field side midplane port location. The nozzle operated in a pulsed regime at room temperature, reservoir deuterium pressure up to 2500 Torr (50 PSIA), flow rate up to 65 Torr l /s (4.55e21 particles/s), and a measured Mach number of about 4. In initial experiments the SGI was used for fueling of ohmic and 2 - 6 MW NBI-heated L- and H-mode plasmas. Reliable H-mode access was obtained with SGI fueling, with a fueling efficiency in the range 0.1 - 0.3. Good progress was also made toward a controlled density SGI-fueled H-mode plasma scenario with the flow rate of the uncontrolled high field side (HFS) gas injector reduced by up to 20. These experiments motivated a number of SGI upgrades: (1) the maximum plenum pressure has been increased to 5000 Torr (100 PSIA), (2) the plenum pressure volume has been doubled, (3) the gas delivery system has been changed to allow for injection of various gases, (4) a multi-pulse capability has been implemented. As a result of the upgrades, the maximum flow rate increased to about 130 Torr l /s. Laboratory gas jet characterization tests indicated a Mach number of about 4 with H2 and D2, and 4-6 with He and N2. Plasma experiments demonstrated the high-pressure gas jet fueling compatibility with H-mode plasmas, high fueling efficiency (0.1 - 0.3), and high SOL penetration.

  3. Economic and technical analysis of distributed utility benefits for hydrogen refueling stations

    Energy Technology Data Exchange (ETDEWEB)

    Iannucci, J.J.; Eyer, J.M.; Horgan, S.A. [Distributed Utility Associates, Livermore, CA (United States); Schoenung, S.M. [Longitude 122 West, Inc., Menlo Park, CA (United States)

    1998-08-01

    This paper discusses the potential economic benefits of operating hydrogen refueling stations to supplying pressurized hydrogen for vehicles, and supplying distributed utility generation, transmission and distribution peaking needs to the utility. The study determined under what circumstances using a hydrogen-fueled generator as a distributed utility generation source, co-located with the hydrogen refueling station components (electrolyzer and storage), would result in cost savings to the station owner, and hence lower hydrogen production costs.

  4. Hydrogen in marine diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Voegler, Arne

    2010-07-01

    To investigate ways of reducing the yearly fuel oil consumption of the UK fishing fleet of 300 million liters, with associated carbon emissions of 802,500tonnes, experiments were undertaken to explore the feasibility of supplementing diesel fuel in compression ignition engines with both on board generated oxy hydrogen and bottled hydrogen. A Beta Marine BD722 3 cylinder engine fitted on board of a 9.4m vessel was used as a test bed and parameters monitored included the in cylinder pressure, fuel economy (tank to propeller thrust analysis), exhaust gas analysis and the thermal performance at various load conditions. The outlet of an oxy hydrogen electrolyzer was connected to the air intake of the engine and the performance was monitored by powering the unit directly from the engine's alternator and also by an external battery. Another approach used bottled hydrogen gas which was introduced into the air intake at varying rates between 5%- 20% of the overall energy supplied and measured values were compared with baseline data gathered during diesel fuel only operations. By examining the force applied to a mooring rope under static conditions the propeller thrust of the vessel underway was calculated for varying speeds and the mechanical engine efficiency for different fuel ratios and loads was determined. Results have confirmed that modest fuel savings can be achieved by supplying hydrogen into the air intake of a diesel engine. The occurrence of engine knock at higher hydrogen supply rates was observed and it is indicated that this could be counter acted upon by shifting the injection timing closer towards top dead centre. (Author)

  5. Abnormal reactions in ethylene hydrogenation process

    Energy Technology Data Exchange (ETDEWEB)

    Tokuhashi, Kazuaki; Urano, Yokichi; Iwasaka, Masaji; Horiguchi, Sadashige; Kondo, Shigeo; Hashiguchi, Yukio

    1987-11-19

    Ethylene hydrogenation under a commercial acethylene hydrogenation catalyst(palladium catalyst supported in cylindrical alumina) and polymerization and/or pyrolysis of ethylene in a higher temperature range were experimentally studied to get basic data and to prevent the abnormal reactions in chemical plants. The danger of ethylene hydrogenation was studied under conditions of hydrogen concentration of 1.5 to 28.6% in the hydrogen-ethylene gas mixture, constant flow rate, temperature of 63/sup 0/C and pressure of 25.5kg/cm/sup 2/. The catalyst had high activity to the ethylene hydrogenation and the temperature of catalyst was easily raised by the reaction heat of ethylene hydrogenation. Both hydrogenation and pyrolysis took place actively at 400/sup 0/C or higher temperature. The outlet temperature of catalyst layer increased with the increase of ethylene flow rate owing to the accumulation of the reaction heat, so that the possibility of runaway reaction became higher. (11 figs, 4 refs)

  6. Effective hydrogen storage: a strategic chemistry challenge.

    Science.gov (United States)

    David, William I F

    2011-01-01

    This paper gives an overview of the current status and future potential of hydrogen storage from a chemistry perspective and is based on the concluding presentation of the Faraday Discussion 151--Hydrogen Storage Materials. The safe, effective and economical storage of hydrogen is one of the main scientific and technological challenges in the move towards a low-carbon economy. One key sector is transportation where future vehicles will most likely be developed around a balance of battery-electric and hydrogen fuel-cell electric technologies. Although there has been a very significant research effort in solid-state hydrogen storage, high-pressure gas storage combined with conventional metal hydrides is still seen as the current intermediate-term candidate for car manufacturers. Significant issues have arisen in the search for improved solid-state hydrogen storage materials; for example, facile reversibility has been a major challenge for many recently studied complex hydrides while physisorption in porous structures is still restricted to cryogenic temperatures. However, many systems fulfil the majority of necessary criteria for improved hydrogen storage--indeed, the discovery of reversibility in multicomponent hydride systems along with recent chemistry breakthroughs in off-board and solvent-assisted regeneration suggest that the goal of both improved on-board reversible and off-board regenerated hydrogen storage systems can be achieved.

  7. Why hydrogen; Pourquoi l'hydrogene?

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-02-01

    The energy consumption increase and the associated environmental risks, led to develop new energy sources. The authors present the potentialities of the hydrogen in this context of energy supply safety. They detail the today market and the perspectives, the energy sources for the hydrogen production (fossils, nuclear and renewable), the hydrogen transport, storage, distribution and conversion, the application domains, the associated risks. (A.L.B.)

  8. Biópsia percutânea de lesões ósseas guiada por tomografia computadorizada: taxas de definição diagnóstica e complicações

    Directory of Open Access Journals (Sweden)

    Macello Jose Sampaio Maciel

    2014-10-01

    Full Text Available Objetivo: Determinar taxas de definição diagnóstica e complicações da biópsia percutânea guiada por tomografia computadorizada (TC de lesões ósseas suspeitas de malignidade. Materiais e Métodos: Estudo retrospectivo que incluiu 186 casos de biópsia percutânea guiada por TC de lesões ósseas no período de janeiro de 2010 a dezembro de 2012. Todas as amostras foram obtidas usando agulhas de 8 a 10 gauge. Foram coletados dados demográficos, história de neoplasia maligna prévia, dados relacionados à lesão, ao procedimento e ao resultado histológico. Resultados: A maioria dos pacientes era do sexo feminino (57% e a idade média foi 53,0 ± 16,4 anos. Em 139 casos (74,6% a suspeita diagnóstica era metástase e os tumores primários mais comuns foram de mama (32,1% e próstata (11,8%. Os ossos mais envolvidos foram coluna vertebral (36,0%, bacia (32,8% e ossos longos (18,3%. Houve complicações em apenas três pacientes (1,6%, incluindo uma fratura, um caso de parestesia com comprometimento funcional e uma quebra da agulha necessitando remoção cirúrgica. Amostras de 183 lesões (98,4% foram consideradas adequadas para diagnóstico. Resultados malignos foram mais frequentes nos pacientes com suspeita de lesão secundária e história de neoplasia maligna conhecida (p < 0,001 e nos procedimentos orientados pela PET/CT (p = 0,011. Conclusão: A biópsia percutânea guiada por TC é segura e eficaz no diagnóstico de lesões ósseas suspeitas.

  9. Observation of the Wigner-Huntington transition to metallic hydrogen

    Science.gov (United States)

    Dias, Ranga P.; Silvera, Isaac F.

    2017-02-01

    Producing metallic hydrogen has been a great challenge in condensed matter physics. Metallic hydrogen may be a room-temperature superconductor and metastable when the pressure is released and could have an important impact on energy and rocketry. We have studied solid molecular hydrogen under pressure at low temperatures. At a pressure of 495 gigapascals, hydrogen becomes metallic, with reflectivity as high as 0.91. We fit the reflectance using a Drude free-electron model to determine the plasma frequency of 32.5 ± 2.1 electron volts at a temperature of 5.5 kelvin, with a corresponding electron carrier density of 7.7 ± 1.1 × 1023 particles per cubic centimeter, which is consistent with theoretical estimates of the atomic density. The properties are those of an atomic metal. We have produced the Wigner-Huntington dissociative transition to atomic metallic hydrogen in the laboratory.

  10. Determination of the dominant catalyst derived from the classic [RhCp*Cl₂]₂ precatalyst system: Is it single-metal Rh₁Cp*-based, subnanometer Rh₄ cluster-based, or Rh(0)n nanoparticle-based cyclohexene hydrogenation catalysis at room temperature and mild pressures?

    Energy Technology Data Exchange (ETDEWEB)

    Bayram, Ercan [Colorado State Univ., Fort Collins, CO (United States); Linehan, John C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fulton, John L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szymczak, Nathaniel K. [Univ. of Michigan, Ann Arbor, MI (United States); Finke, Richard G. [Colorado State Univ., Fort Collins, CO (United States)

    2015-05-27

    Determining the kinetically dominant catalyst in a given catalytic system is a forefront topic in catalysis. The [RhCp*Cl₂]₂ (Cp* =[η⁵-C₅(CH₃)₅]) system pioneered by Maitlis and co-workers is a classic precatalyst system from which homogeneous mononuclear Rh₁, subnanometer Rh₄ cluster, and heterogeneous polymetallic Rh(0)n nanoparticle have all arisen as viable candidates for the true hydrogenation catalyst, depending on the precise substrate, H₂ pressure, temperature, and catalyst concentration conditions. Addressed herein is the question of whether the prior assignment of homogeneous, mononuclear Rh₁Cp*-based catalysis is correct, or are trace Rh₄ subnanometer clusters or possibly Rh(0)n nanoparticles the dominant, actual cyclohexene hydrogenation catalyst at 22 °C and 2.7 atm initial H₂ pressure? The observation herein of Rh₄ species by in operando-X-ray absorption fine structure (XAFS) spectroscopy, at the only slightly more vigorous conditions of 26 °C and 8.3 atm H₂ pressure, and the confirmation of Rh₄ clusters by ex situ mass spectroscopy raises the question of the dominant, room temperature, and mild pressure cyclohexene hydrogenation catalyst derived from the classic [RhCp*Cl₂]₂ precatalyst pioneered by Maitlis and co-workers. Ten lines of evidence are provided herein to address the nature of the true room temperature and mild pressure cyclohexene hydrogenation catalyst derived from [RhCp*Cl₂]₂. Especially significant among those experiments are quantitative catalyst poisoning experiments, in the present case using 1,10-phenanthroline. Those poisoning studies allow one to distinguish mononuclear Rh₁, subnanometer Rh₄ cluster, and Rh(0)n nanoparticle catalysis hypotheses. The evidence obtained provides a compelling case for a mononuclear, Rh₁Cp*-based cyclohexene hydrogenation catalyst at 22 °C and 2.7 atm H₂ pressure. The resultant methodology, especially the quantitative

  11. Hydrogen nanobubble at normal hydrogen electrode

    Science.gov (United States)

    Nakabayashi, S.; Shinozaki, R.; Senda, Y.; Yoshikawa, H. Y.

    2013-05-01

    Electrochemically formed hydrogen nanobubbles at a platinum rotating disk electrode (RDE) were detected by re-oxidation charge. The dissolution time course of the hydrogen nanobubbles was measured by AFM tapping topography under open-circuit conditions at stationary platinum and gold single-crystal electrodes. The bubble dissolution at platinum was much faster than that at gold because two types of diffusion, bulk and surface diffusion, proceeded at the platinum surface, whereas surface diffusion was prohibited at the gold electrode. These findings indicated that the electrochemical reaction of normal hydrogen electrode partly proceeded heterogeneously on the three-phase boundary around the hydrogen nanobubble.

  12. Hydrogen storage in graphite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Park, C.; Tan, C.D.; Hidalgo, R.; Baker, R.T.K.; Rodriguez, N.M. [Northeastern Univ., Boston, MA (United States). Chemistry Dept.

    1998-08-01

    Graphite nanofibers (GNF) are a type of material that is produced by the decomposition of carbon containing gases over metal catalyst particles at temperatures around 600 C. These molecularly engineered structures consist of graphene sheets perfectly arranged in a parallel, perpendicular or at angle orientation with respect to the fiber axis. The most important feature of the material is that only edges are exposed. Such an arrangement imparts the material with unique properties for gas adsorption because the evenly separated layers constitute the most ordered set of nanopores that can accommodate an adsorbate in the most efficient manner. In addition, the non-rigid pore walls can also expand so as to accommodate hydrogen in a multilayer conformation. Of the many varieties of structures that can be produced the authors have discovered that when gram quantities of a selected number of GNF are exposed to hydrogen at pressures of {approximately} 2,000 psi, they are capable of adsorbing and storing up to 40 wt% of hydrogen. It is believed that a strong interaction is established between hydrogen and the delocalized p-electrons present in the graphite layers and therefore a new type of chemistry is occurring within these confined structures.

  13. High-pressure synthesis of tantalum dihydride

    Science.gov (United States)

    Kuzovnikov, Mikhail A.; Tkacz, Marek; Meng, Haijing; Kapustin, Dmitry I.; Kulakov, Valery I.

    2017-10-01

    The reaction of tantalum with molecular hydrogen was studied by x-ray diffraction in a diamond-anvil cell at room temperature and pressures from 1 to 41 GPa. At pressures up to 5.5 GPa, a substoichiometric tantalum monohydride with a distorted bcc structure was shown to be stable. Its hydrogen content gradually increased with the pressure increase, reaching H /Ta =0.92 (5 ) at 5 GPa. At higher pressures, a new dihydride phase of tantalum was formed. This phase had an hcp metal lattice, and its hydrogen content was virtually independent of pressure. When the pressure was decreased, the tantalum dihydride thus obtained transformed back to the monohydride at P =2.2 GPa . Single-phase samples of tantalum dihydride also were synthesized at a hydrogen pressure of 9 GPa in a toroid-type high-pressure apparatus, quenched to the liquid-N2 temperature, and studied at ambient pressure. X-ray diffraction showed them to have an hcp metal lattice with a =3.224 (3 ) and c =5.140 (5 )Å at T =85 K . The hydrogen content determined by thermal desorption was H /Ta =2.2 (1 ) .

  14. Hydrogen energy systems studies

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, J.M.; Kreutz, T.G.; Steinbugler, M. [Princeton Univ., NJ (United States)] [and others

    1996-10-01

    In this report the authors describe results from technical and economic assessments carried out during the past year with support from the USDOE Hydrogen R&D Program. (1) Assessment of technologies for small scale production of hydrogen from natural gas. Because of the cost and logistics of transporting and storing hydrogen, it may be preferable to produce hydrogen at the point of use from more readily available energy carriers such as natural gas or electricity. In this task the authors assess near term technologies for producing hydrogen from natural gas at small scale including steam reforming, partial oxidation and autothermal reforming. (2) Case study of developing a hydrogen vehicle refueling infrastructure in Southern California. Many analysts suggest that the first widespread use of hydrogen energy is likely to be in zero emission vehicles in Southern California. Several hundred thousand zero emission automobiles are projected for the Los Angeles Basin alone by 2010, if mandated levels are implemented. Assuming that hydrogen vehicles capture a significant fraction of this market, a large demand for hydrogen fuel could evolve over the next few decades. Refueling a large number of hydrogen vehicles poses significant challenges. In this task the authors assess near term options for producing and delivering gaseous hydrogen transportation fuel to users in Southern California including: (1) hydrogen produced from natural gas in a large, centralized steam reforming plant, and delivered to refueling stations via liquid hydrogen truck or small scale hydrogen gas pipeline, (2) hydrogen produced at the refueling station via small scale steam reforming of natural gas, (3) hydrogen produced via small scale electrolysis at the refueling station, and (4) hydrogen from low cost chemical industry sources (e.g. excess capacity in refineries which have recently upgraded their hydrogen production capacity, etc.).

  15. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

    2016-04-28

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.

  16. Interaction between an icosahedron Li(13) cluster and a graphene layer doped with a hydrogen atom.

    Science.gov (United States)

    Rangel, Eduardo; Vázquez, Gerardo; Magaña, Fernando; Sansores, Enrique

    2012-12-01

    It is known that graphene reacts with atomic hydrogen to form a hydrogenated sheet of graphene. In order to understand the nature of the interaction between hydrogen and lithium in hydrogenated samples, we have carried out first principle calculations. Density functional theory and molecular dynamics were used to study the interaction between an icosahedron Li(13) cluster, and a graphene layer doped with a hydrogen atom. It was found that a hydrogen atom is levitated from the graphene layer and absorbed into the cluster of Li at 300 K and atmospheric pressure, with a binding energy far exceeding that of the adsorption energy of a hydrogen atom on the graphene layer.

  17. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I

    1991-01-01

    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  18. Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

    2017-12-19

    Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

  19. Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

    Science.gov (United States)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

    2015-08-11

    Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

  20. Achados clínicopatológicos na tromboembolia pulmonar: estudo de 24 anos de autópsias Clinicopathological findings in pulmonary thromboembolism: a 24-year autopsy study

    Directory of Open Access Journals (Sweden)

    Hugo Hyung Bok Yoo

    2004-10-01

    Full Text Available INTRODUÇÃO: Tromboembolia pulmonar (TEP é ainda uma afecção enigmática em diversos aspectos clínicos e epidemiológicos e frequentemente erroneamente diagnosticada. OBJETIVO: Descrever a prevalência e os achados anatomopatológicos de TEP em uma série de 5261 autópsias realizadas em um hospital universitário de nível terciário, correlacionar estes achados com as doenças de base e verificar a freqüência de suspeita clínica antemortem de TEP. MÉTODO: Revisão dos registros das autópsias consecutivas realizadas de 1979 a 2002 para um estudo retrospectivo. Dos prontuários e dos relatórios de autópsias dos pacientes que tiveram TEP documentada, macro e/ou microscopicamente, foram extraídos dados demográficos, doenças de base, suspeita antemortem de TEP, localização dos trombos nos pulmões e provável local de origem da TEP. RESULTADOS: A freqüência de autópsias foi de 42,0% e TEP foi encontrada em 544 pacientes, sendo a principal causa da morte (TEP fatal em 225 casos. Doenças infecciosas (p=0,0003 foram associadas com TEP não fatal e trauma (p=0,007 com TEP fatal. A taxa de não suspeita antemortem de TEP foi 84,6% e 40,0% destes pacientes apresentaram TEP fatal. Doenças do sistema circulatório (p=0,0001, infecções (pBACKGROUND: Pulmonary thromboembolism (PTE is still an enigmatic disorder in many epidemiological and clinical features, remaining one of the most commonly misdiagnosed disorders. OBJECTIVE: To describe the prevalence and pathological findings of PTE in a series of autopsies, to correlate these findings with underlying diseases, and to verify the frequency of PTE clinically suspected before death. METHOD: The reports on 5261 consecutive autopsies performed from 1979 to 2002 in a Brazilian tertiary referral medical school were reviewed for a retrospective study. From the medical records and autopsy reports of the patients found with macroscopically and/or microscopically documented PTE, were gathered

  1. Análise da correlação entre tipos histológicos de carcinoma basocelular encontrados nas biópsias pré-operatórias e respectivas peças cirúrgicas

    OpenAIRE

    Maria Cristina de Lorenzo Messina

    2005-01-01

    O carcinoma basocelular (CBC) é tumor constituído por diferentes tipos histológicos, que demonstram diverso potencial de agressividade. Sabe-se que a correlação entre os tipos histológicos de CBC encontrados no material de biópsia pré-operatória e no material da peça cirúrgica excisional não é total. Na literatura esta correlação varia de 42,7 a 80,0% quando analisados os tipos histológicos predominantes (THP). No presente estudo foi feita análise retrospectiva de 70 casos de CBC primário sub...

  2. Biópsia transtorácica com agulha cortante (Trucut para o diagnóstico dos tumores mediastínicos Transthoracic biopsy with core cutting needle (Trucut for the diagnosis of mediastinal tumors

    Directory of Open Access Journals (Sweden)

    Mauro Zamboni

    2009-08-01

    Full Text Available Objetivo: Determinar a contribuição da biópsia percutânea com agulha cortante (Trucut no diagnóstico das massas mediastínicas. Método: Revisão retrospectiva de 56 doentes com massas mediastínicas submetidos a biópsias com agulha cortante orientadas, mas não guiadas, pela tomografia computadorizada do tórax, no período de 1999 a 2008. Resultados: A biopsia percutânea com agulha cortante forneceu material adequado para o diagnóstico em 49/56 casos, com índice de positividade de 88%. Em 7/56, o material colhido foi insuficiente para definir o diagnóstico (12%. Este método foi capaz de definir o diagnóstico em 88% dos doentes: 23/56 (41% linfomas; 12/56 (21% timomas; 5/56 (3% carcinomas tímicos; 3/56 (2% carcinoma indiferenciado de pequenas células e 1/56 (0,6% adenocarcinoma metastático, carcinoma epidermóide metastático, carcinoma neuroendócrino primitivo, plasmocitoma, teratoma, bócio. Após a biópsia, os doen tes foram submetidos a radiografia do tórax. Não houve nenhum tipo de complicação nestes doentes. Conclusão: A biópsia transtorácica com agulha cortante (Trucut orientada, mas não guiada pela tomografia computadorizada, tem alto rendimento, esclrrecendo o diagnóstico na maioria dos portadores de massas mediastínicas e pode ser útil, evitando a toracotomia exploradora, nos casos de tumores do mediastino inoperáveis ou de tratamento quimioterápico.Aim: To determine the contribution of percutaneous biopsy with core cutting needle (Trucut in the diagnosis of mediastinal tumours. Method: Retrospective review of 56 patients with mediastinal lesions who underwent percutaneous core cutting needle biopsy, oriented but not guided by computer assisted tomography of the thorax, 1999 - 2008. Results: Percutaneous biopsy with core cutting needle provided adequate material in 49/56, with a total positive sample rate of 88%. In 7/56 (12% cases the material was insufficient to define the diagnosis. Percutaneous core

  3. SISGR - Hydrogen Caged in Carbon-Exploration of Novel Carbon-Hydrogen Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lueking, Angela [Pennsylvania State Univ., State College, PA (United States); Badding, John [Pennsylvania State Univ., State College, PA (United States); Crespi, Vinent [Pennsylvania State Univ., State College, PA (United States)

    2015-12-01

    Hydrogen trapped in a carbon cage, captured through repulsive interactions, is a novel concept in hydrogen storage. Trapping hydrogen via repulsive interactions borrows an idea from macroscale hydrogen storage (i.e. compressed gas storage tanks) and reapplies these concepts on the nanoscale in specially designed molecular containers. Under extreme conditions of pressure, hydrogen solubility in carbon materials is expected to increase and carbon is expected to restructure to minimize volume via a mixed sp2/sp3 hydrogenated state. Thermodynamics dictate that pre-formed C-H structures will rearrange with increased pressure, yet the final carbon-hydrogen interactions may be dependent upon the mechanism by which hydrogen is introduced. Gas “trapping” is meant to denote gas present in a solid in a high density, adsorbed-like state, when the external pressure is much less than that necessary to provide a comparable fluid density. Trapping thus denotes a kinetically metastable state rather than thermodynamic equilibrium. This project probed mechanochemical means to polymerize select hydrocarbons in the presence of gases, in an attempt to form localized carbon cages that trap gases via repulsive interactions. Aromatic, polyaromatic, and hydroaromatic molecules expected to undergo cyclo-addition reactions were polymerized at high (~GPa) pressures to form extended hydrogenated amorphous carbon networks. Notably, aromatics with a pre-existing internal free volume (such as Triptycene) appeared to retain an internal porosity upon application of pressure. However, a high photoluminescence background after polymerization precluded in situ identification of trapped gases. No spectroscopic evidence was found after depressurization that would be indicative of pockets of trapped gases in a localized high-pressure environment. Control studies suggested this measurement may be insensitive to gases at low pressure. Similarly, no spectral fingerprint was found for gas-imbued spherical

  4. Novel, Ceramic Membrane System For Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, S.

    2012-12-31

    Separation of hydrogen from coal gas represents one of the most promising ways to produce alternative sources of fuel. Ceramatec, teamed with CoorsTek and Sandia National Laboratories has developed materials technology for a pressure driven, high temperature proton-electron mixed conducting membrane system to remove hydrogen from the syngas. This system separates high purity hydrogen and isolates high pressure CO{sub 2} as the retentate, which is amenable to low cost capture and transport to storage sites. The team demonstrated a highly efficient, pressure-driven hydrogen separation membrane to generate high purity hydrogen from syngas using a novel ceramic-ceramic composite membrane. Recognizing the benefits and limitations of present membrane systems, the all-ceramic system has been developed to address the key technical challenges related to materials performance under actual operating conditions, while retaining the advantages of thermal and process compatibility offered by the ceramic membranes. The feasibility of the concept has already been demonstrated at Ceramatec. This project developed advanced materials composition for potential integration with water gas shift rectors to maximize the hydrogenproduction.

  5. Hydrogen adsorption on N-decorated single wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rangel, Eduardo [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Codigo Postal 01000, Mexico D.F. (Mexico); Ruiz-Chavarria, Gregorio [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Codigo Postal 01000, Mexico D.F. (Mexico); Departamento de Fisica, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico Ciudad Universitaria, Codigo Postal 04510, Mexico D.F. (Mexico); Magana, L.F., E-mail: fernando@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Codigo Postal 01000, Mexico D.F. (Mexico); Arellano, J.S. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana, Unidad Azcapotzalco. Avenida San Pablo No. 180, Col. Reynosa Tamaulipas Codigo Postal 02200, Mexico D.F. (Mexico)

    2009-07-06

    Using density functional theory and molecular dynamics we found that N-decorated single walled (8,0) carbon nanotubes are potential high capacity hydrogen storage media. This system could store up to 6.0 wt% hydrogen at 300 K and ambient pressure, with average adsorption energy of -80 meV/(H{sub 2}). Nitrogen coverage was C{sub 8}N.

  6. Measurement of strong interaction parameters in antiprotonic hydrogen and deuterium

    CERN Document Server

    Augsburger, M A; Borchert, G L; Chatellard, D; Egger, J P; El-Khoury, P; Gorke, H; Gotta, D; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Siems, T; Simons, L M

    1999-01-01

    In the PS207 experiment at CERN, X-rays from antiprotonic hydrogen and deuterium have been measured at low pressure. The strong interaction shift and the broadening of the K/sub alpha / transition in antiprotonic hydrogen were $9 determined. Evidence was found for the individual hyperfine components of the protonium ground state. (7 refs).

  7. Final Report: Metal Perhydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J-Y.; Shi, S.; Hackney, S.; Swenson, D.; Hu, Y.

    2011-07-26

    Hydrogen is a promising energy source for the future economy due to its environmental friendliness. One of the important obstacles for the utilization of hydrogen as a fuel source for applications such as fuel cells is the storage of hydrogen. In the infrastructure of the expected hydrogen economy, hydrogen storage is one of the key enabling technologies. Although hydrogen possesses the highest gravimetric energy content (142 KJ/g) of all fuels, its volumetric energy density (8 MJ/L) is very low. It is desired to increase the volumetric energy density of hydrogen in a system to satisfy various applications. Research on hydrogen storage has been pursed for many years. Various storage technologies, including liquefaction, compression, metal hydride, chemical hydride, and adsorption, have been examined. Liquefaction and high pressure compression are not desired due to concerns related to complicated devices, high energy cost and safety. Metal hydrides and chemical hydrides have high gravimetric and volumetric energy densities but encounter issues because high temperature is required for the release of hydrogen, due to the strong bonding of hydrogen in the compounds. Reversibility of hydrogen loading and unloading is another concern. Adsorption of hydrogen on high surface area sorbents such as activated carbon and organic metal frameworks does not have the reversibility problem. But on the other hand, the weak force (primarily the van der Waals force) between hydrogen and the sorbent yields a very small amount of adsorption capacity at ambient temperature. Significant storage capacity can only be achieved at low temperatures such as 77K. The use of liquid nitrogen in a hydrogen storage system is not practical. Perhydrides are proposed as novel hydrogen storage materials that may overcome barriers slowing advances to a hydrogen fuel economy. In conventional hydrides, e.g. metal hydrides, the number of hydrogen atoms equals the total valence of the metal ions. One Li

  8. Evaluacion de la biopsia transpedicular guiada por TAC Avaliação da biópsia transpedicular guiada por TC Evaluation of transpedicular percutaneous biopsy guided by CT

    Directory of Open Access Journals (Sweden)

    Luis Miguel Rosales Olivarez

    2012-09-01

    Full Text Available OBJETIVO: Valorar la utilidad de la biopsia transpedicular percutánea guiada por Tomografía Axial Computarizada en conjunto con la sistematización de estudios como pruebas diagnósticas de la etiología de la destrucción vertebral. MÉTODOS: Estudio de serie de casos prospectivo transversal de 21 pacientes a los que se les realizó biopsia transpedicular percutánea guiada por Tomografía Axial Computarizada y estudios de laboratorio y gabinete de marzo a julio del 2011, para evaluar su utilidad en el diagnóstico de destrucción vertebral. RESULTADOS: Fueron 21 pacientes, 14 hombres y 7 mujeres, con edad media de 59,2 años, cuyos niveles más afectados estuvieron en L1, L2 y L3. El reporte de la biopsia tuvo una precisión diagnóstica del 90,4%. En 2 casos se realizó correlación clínica entre biopsia y sistematización de estudios para obtener el diagnóstico. CONCLUSIÓN: La biopsia guiada por Tomografía Axial Computarizada es una técnica sencilla, útil, de bajo costo y eficaz en el estudio de la destrucción vertebral; la sistematización de estudios permite corroborar el diagnóstico de la biopsia.OBJETIVO: Avaliar a utilidade da biópsia transpedicular percutânea guiada por tomografia axial computadorizada em conjunto com a sistematização de estudos, como exames diagnósticos da etiologia da destruição vertebral. MÉTODOS: Estudo de série de casos, prospectivo e transversal de 21 pacientes submetidos à biópsia transpedicular percutânea guiada por tomografia axial computadorizada e exames laboratoriais e radiológicos, de março a julho de 2011, para avaliar sua utilidade no diagnóstico de destruição vertebral. RESULTADOS: Foram analisados 21 pacientes, 14 homens e 7 mulheres, com média de idade de 59,2 anos, cujos níveis mais afetados foram L1, L2 e L3. O laudo da biópsia teve precisão diagnóstica de 90,4%. Em dois casos, realizou-se a correlação clínica entre biópsia e sistematização de exames para obter

  9. Handbook of hydrogen energy

    CERN Document Server

    Sherif, SA; Stefanakos, EK; Steinfeld, Aldo

    2014-01-01

    ""This book provides an excellent overview of the hydrogen economy and a thorough and comprehensive presentation of hydrogen production and storage methods.""-Scott E. Grasman, Rochester Institute of Technology, New York, USA

  10. Center for Hydrogen Storage.

    Science.gov (United States)

    2013-06-01

    The main goals of this project were to (1) Establish a Center for Hydrogen Storage Research at Delaware State University for the preparation and characterization of selected complex metal hydrides and the determination their suitability for hydrogen ...

  11. Hydrogen production by Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Chaudhuri Surabhi

    2005-12-01

    Full Text Available Abstract The limited fossil fuel prompts the prospecting of various unconventional energy sources to take over the traditional fossil fuel energy source. In this respect the use of hydrogen gas is an attractive alternate source. Attributed by its numerous advantages including those of environmentally clean, efficiency and renew ability, hydrogen gas is considered to be one of the most desired alternate. Cyanobacteria are highly promising microorganism for hydrogen production. In comparison to the traditional ways of hydrogen production (chemical, photoelectrical, Cyanobacterial hydrogen production is commercially viable. This review highlights the basic biology of cynobacterial hydrogen production, strains involved, large-scale hydrogen production and its future prospects. While integrating the existing knowledge and technology, much future improvement and progress is to be done before hydrogen is accepted as a commercial primary energy source.

  12. Metallic Hydrogen: A Game Changing Rocket Propellant

    Science.gov (United States)

    Silvera, Isaac F.

    2016-01-01

    The objective of this research is to produce metallic hydrogen in the laboratory using an innovative approach, and to study its metastability properties. Current theoretical and experimental considerations expect that extremely high pressures of order 4-6 megabar are required to transform molecular hydrogen to the metallic phase. When metallic hydrogen is produced in the laboratory it will be extremely important to determine if it is metastable at modest temperatures, i.e. remains metallic when the pressure is released. Then it could be used as the most powerful chemical rocket fuel that exists and revolutionize rocketry, allowing single-stage rockets to enter orbit and chemically fueled rockets to explore our solar system.

  13. Thermodynamic properties of hydrogen-helium plasmas.

    Science.gov (United States)

    Nelson, H. F.

    1972-01-01

    Calculation of the thermodynamic properties of an atomic hydrogen-helium plasma for postulated conditions present in a stagnation shock layer of a spacecraft entering the atmosphere of Jupiter. These properties can be used to evaluate transport properties, to calculate convective heating, and to investigate nonequilibrium behavior. The calculations have been made for temperatures from 10,000 to 100,000 K, densities of 10 to the minus 7th and .00001 g cu cm, and three plasma compositions: pure hydrogen, 50% hydrogen/50% helium, and pure helium. The shock layer plasma consists of electrons, protons, atomic hydrogen, atomic helium, singly ionized helium, and doubly atomized helium. The thermodynamic properties which have been investigated are: pressure, average molecular weight, internal energy, enthalpy, entropy, specific heat, and isentropic speed of sound. A consistent model was used for the reduction of the ionization potential in the calculation of the partition functions.

  14. Shape-dependent hydrogen-storage properties in Pd nanocrystals: which does hydrogen prefer, octahedron (111) or cube (100)?

    Science.gov (United States)

    Li, Guangqin; Kobayashi, Hirokazu; Dekura, Shun; Ikeda, Ryuichi; Kubota, Yoshiki; Kato, Kenichi; Takata, Masaki; Yamamoto, Tomokazu; Matsumura, Syo; Kitagawa, Hiroshi

    2014-07-23

    Pd octahedrons and cubes enclosed by {111} and {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, in situ solid-state (2)H NMR and hydrogen pressure-composition isotherm measurements. With these measurements, it was found that the exposed facets do not affect hydrogen-storage capacity; however, they significantly affect the absorption speed, with octahedral nanocrystals showing the faster response. The heat of adsorption of hydrogen and the hydrogen diffusion pathway were suggested to be dominant factors for hydrogen-absorption speed. Furthermore, in situ solid-state (2)H NMR detected for the first time the state of (2)H in a solid-solution (Pd + H) phase of Pd nanocrystals at rt.

  15. Simulation of the Fast Filling of Hydrogen Tanks

    OpenAIRE

    HEITSCH Matthias; Baraldi, Daniele; Moretto, Pietro

    2009-01-01

    High pressure storage of hydrogen in tanks is a promising option to provide the necessary fuel for transportation purposes. The fill process of a high-pressure tank should be reasonably short but must be designed to avoid too high temperatures in the tank. The paper describes the fast filling process of hydrogen tanks by simulations based on the Computational Fluid Dynamics (CFD) code CFX. The major result of the simulations is the local temperature distribution in the tank depending on th...

  16. EXPERIMENTAL STUDY OF THE THERMAL BEHAVIOUR OF HYDROGEN TANKS DURING HYDROGEN CYCLING

    OpenAIRE

    DE MIGUEL ECHEVARRIA NEREA; Acosta Iborra, Beatriz; Moretto, Pietro; HARSKAMP Frederik; BONATO CHRISTIAN

    2013-01-01

    The thermal behaviour of several commercial hydrogen tanks has been studied during high pressure (70-84 MPa) hydrogen cycling. The temperature of the gas at different points inside the tank, the temperature at the bosses and the tank outer wall temperature have been measured under different filling and emptying conditions. From the experimental results, the effect of the filling rate (1.5-4 g/s) and the influence of the liner material in the thermal behaviour of the hydrogen tanks have been e...

  17. Solid pellets for hydrogen storage; Des pastilles solides pour stocker l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Lepetit, V.

    2006-01-01

    Five researchers from the technical university of Denmark (DTU) have developed magnesium chloride salt pellets which can absorb ammonia (NH{sub 3}) in hexamine form at ambient temperature and pressure. These pellets can store up to the equivalent of 52% of their mass in ammonia (9% of hydrogen). The release of ammonia is obtained by heating the salt at 300 deg. C. In the presence of an iron-based catalyst, ammonia is transformed into nitrogen and hydrogen. This is probably the safest way invented so far to store hydrogen. Short paper. (J.S.)

  18. Hydrogen for road transport: implementations and developments; L'hydrogene pour le transport sur route: realisations et developpements

    Energy Technology Data Exchange (ETDEWEB)

    Junker, M.; Bocquet, L.; Bendif, M.; Karboviac, D. [Alphea, 57 - Forbach (France)

    2000-07-01

    The different technologies for the use of hydrogen in the road transport are overviewed: type of propulsion (fuel cell and electric motor or internal combustion motor), hydrogen production, on-board storage, infrastructure. The aspects of safety, standardization and regulation are approached too. At the present time, main of the hydrogen buses are equipped with polymer membrane cells (PEMFC), directly supplied in hydrogen and stored in tanks under pressure (300 bars). On the other hand, the automobile manufacturers are developing different types of prototypes: internal combustion engines with liquid hydrogen storage, PEM cell cars with hydrogen storage (liquid, gas or hydrides) or with methanol storage. The infrastructure type will depend on the primary fuel chosen by the automobile manufacturers and on the requirements of the petroleum firms. Several hydrogen service stations have been constructed. They deliver hydrogen, on a gaseous or liquid state; the hydrogen being produced by natural gas reforming or by electrolysis. The setting of a 'Hydrogen system' require indeed the development of specific means of production, transport, distribution and storage. The public acceptance will be won by safeguards of safety, reliability, performance and competitiveness. The research and development studies are nowadays particularly centred on: 1)the on-board hydrogen storage 2)the on-board systems of hydrogen production from methanol and gasoline 3)the standardization and regulation. (O.M.)

  19. Solar hydrogen generator

    Science.gov (United States)

    Sebacher, D. I.; Sabol, A. P. (Inventor)

    1977-01-01

    An apparatus, using solar energy to manufacture hydrogen by dissociating water molecules into hydrogen and oxygen molecules is described. Solar energy is concentrated on a globe containing water thereby heating the water to its dissociation temperature. The globe is pervious to hydrogen molecules permitting them to pass through the globe while being essentially impervious to oxygen molecules. The hydrogen molecules are collected after passing through the globe and the oxygen molecules are removed from the globe.

  20. Hydrogen Technologies Safety Guide

    Energy Technology Data Exchange (ETDEWEB)

    Rivkin, C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Burgess, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Buttner, W. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-01-01

    The purpose of this guide is to provide basic background information on hydrogen technologies. It is intended to provide project developers, code officials, and other interested parties the background information to be able to put hydrogen safety in context. For example, code officials reviewing permit applications for hydrogen projects will get an understanding of the industrial history of hydrogen, basic safety concerns, and safety requirements.

  1. A study of backfire in hydrogen engines

    Energy Technology Data Exchange (ETDEWEB)

    Sierens, R.; Rosseel, E. [University of Gent (Belgium)

    1999-07-01

    A 4 cylinder diesel engine is modified for hydrogen use by the installation of a gas carburettor. If the fuel-air mixture formed in the intake manifold pre-ignites before the inlet valve is closed, the result is backfire. This backfire phenomenon occurs easily in external mixture formation type hydrogen fuelled engines. In a first study the development of the pressure in the combustion chamber of one cylinder and the pressure in the inlet manifold is stored prior to backfire (during 32 successive cycles), as well as during and after backfire. The pressure traces are carefully examined and analysed to determine the start of combustion, the combustion duration, the maximum combustion pressure and the occurrence of knock for each of the successive cycles. It is observed that prior to backfire sudden pre-ignition combined with knock appears, which results in a run-away pre-ignition. In a second study the influence of engine parameters (ignition timing, supercharging conditions) on the occurrence of backfire are examined, as a function of the air-fuel ratio. Finally the behaviour of hythane mixtures (mixtures of natural gas and hydrogen) with respect to backfire is analysed in a GM V8 engine. For hythane mixtures with a hydrogen content of 80% or less, safe operation of the engine is guaranteed (no backfire nor knock), whatever the air-fuel ratio of the engine. (author)

  2. Hydrogen Sulfide in Preeclampsia : Potential Therapeutic Implications

    NARCIS (Netherlands)

    Holwerda, Kim

    2015-01-01

    The thesis provide insights into the production and possible therapeutic effect of the gaseous molecule hydrogen sulfide (H2S) in preeclampsia (PE). H2S is an important molecule in the (human) body. It is among others involved in blood pressure regulation, stimulation of vascular growth and

  3. Biological hydrogen photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, Y. [Univ. of Miami, FL (United States)

    1995-09-01

    Following are the major accomplishments of the 6th year`s study of biological hydrogen photoproduction which were supported by DOE/NREL. (1) We have been characterizing a biological hydrogen production system using synchronously growing aerobically nitrogen-fixing unicellular cyanobacterium, Synechococcus sp. Miami BG 043511. So far it was necessary to irradiate the cells to produce hydrogen. Under darkness they did not produce hydrogen. However, we found that, if the cells are incubated with oxygen, they produce hydrogen under the dark. Under 80% argon + 20% oxygen condition, the hydrogen production activity under the dark was about one third of that under the light + argon condition. (2) Also it was necessary so far to incubate the cells under argon atmosphere to produce hydrogen in this system. Argon treatment is very expensive and should be avoided in an actual hydrogen production system. We found that, if the cells are incubated at a high cell density and in a container with minimum headspace, it is not necessary to use argon for the hydrogen production. (3) Calcium ion was found to play an important role in the mechanisms of protection of nitrogenase from external oxygen. This will be a clue to understand the reason why the hydrogen production is so resistant to oxygen in this strain. (4) In this strain, sulfide can be used as electron donor for the hydrogen production. This result shows that waste water can be used for the hydrogen production system using this strain.

  4. Hydrogen Production for Refuelling Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hulteberg, Christian; Aagesen, Diane (Intelligent Energy, Long Beach, CA (United States))

    2009-08-15

    The aim of this work is to support the development of a high-profile demonstration of hydrogen generation technologies in a Swedish context. The overall objective of the demonstration is to deploy a reforming based hydrogen refilling station along the Swedish west coast; intermediate to the Malmoe refuelling station and planned stations in Goeteborg. In this way, the Norwegian hydrogen highway will be extended through the south of Sweden and down into Denmark. The aim of the project's first phase, where this constitutes the final report, was to demonstrate the ability to operate the IE reforming system on the E.On/SGC site-specific fuel. During the project, a preliminary system design has been developed, based on IE's proprietary reformer. The system has been operated at pressure, to ensure a stable operation of the downstream PSA; which has been operated without problems and with the expected hydrogen purity and recovery. The safe operation of the proposed and tested system was first evaluated in a preliminary risk assessment, as well as a full HazOp analysis. A thorough economic modelling has been performed on the viability of owning and operating this kind of hydrogen generation equipment. The evaluation has been performed from an on-site operation of such a unit in a refuelling context. The general conclusion from this modelling is that there are several parameters that influence the potential of an investment in a Hestia hydrogen generator. The sales price of the hydrogen is one of the major drivers of profitability. Another important factor is the throughput of the unit, more important than efficiency and utilization. Varying all of the parameters simultaneously introduce larger variations in the NPV, but 60% of the simulations are in the USD 90 000 to USD 180 000 interval. The chosen intervals for the parameters were: Hydrogen Sales Price (USD 5 - USD 7 per kg); Investment Cost (USD 70 000 - USD 130 000 per unit); Throughput (20 - 30 kg

  5. Advanced Hydrogen Turbine Development

    Energy Technology Data Exchange (ETDEWEB)

    Joesph Fadok

    2008-01-01

    Siemens has developed a roadmap to achieve the DOE goals for efficiency, cost reduction, and emissions through innovative approaches and novel technologies which build upon worldwide IGCC operational experience, platform technology, and extensive experience in G-class operating conditions. In Phase 1, the technologies and concepts necessary to achieve the program goals were identified for the gas turbine components and supporting technology areas and testing plans were developed to mitigate identified risks. Multiple studies were conducted to evaluate the impact in plant performance of different gas turbine and plant technologies. 2015 gas turbine technologies showed a significant improvement in IGCC plant efficiency, however, a severe performance penalty was calculated for high carbon capture cases. Thermodynamic calculations showed that the DOE 2010 and 2015 efficiency targets can be met with a two step approach. A risk management process was instituted in Phase 1 to identify risk and develop mitigation plans. For the risks identified, testing and development programs are in place and the risks will be revisited periodically to determine if changes to the plan are necessary. A compressor performance prediction has shown that the design of the compressor for the engine can be achieved with additional stages added to the rear of the compressor. Tip clearance effects were studied as well as a range of flow and pressure ratios to evaluate the impacts to both performance and stability. Considerable data was obtained on the four candidate combustion systems: diffusion, catalytic, premix, and distributed combustion. Based on the results of Phase 1, the premixed combustion system and the distributed combustion system were chosen as having the most potential and will be the focus of Phase 2 of the program. Significant progress was also made in obtaining combustion kinetics data for high hydrogen fuels. The Phase 1 turbine studies indicate initial feasibility of the

  6. Safe venting of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, W.F.; Dewart, J.M.; Edeskuty, F.J.

    1990-01-01

    The disposal of hydrogen is often required in the operation of an experimental facility that contains hydrogen. Whether the vented hydrogen can be discharged to the atmosphere safely depends upon a number of factors such as the flow rate and atmospheric conditions. Calculations have been made that predict the distance a combustible mixture can extend from the point of release under some specified atmospheric conditions. Also the quantity of hydrogen in the combustible cloud is estimated. These results can be helpful in deciding of the hydrogen can be released directly to the atmosphere, or if it must be intentionally ignited. 15 refs., 5 figs., 2 tabs.

  7. Liquefaction of hydrogen on a commercial scale. Wasserstoffverfluessigung im grosstechnischen Massstab

    Energy Technology Data Exchange (ETDEWEB)

    Patzelt, A.; Bracha, M.; Haas, W.; Wanner, M. (Linde AG, Werksgruppe Verfahrenstechnik und Anlagenbau, Hoellriegelskreuth (Germany))

    1992-01-01

    LINDE AG has established a pure hydrogen production plant in Ingolstadt. In addition to a filling station for gaseous high-pressure hydrogen, this pure hydrogen production plant has also a H[sub 2] liquefier with a daily capacity of about 4.4 tons of LH[sub 2]. (orig./MM).

  8. Interface effects in NaAlH4-carbon nanocomposites for hydrogen storage

    NARCIS (Netherlands)

    Gao, Jinbao|info:eu-repo/dai/nl/315029633; Ngene, Peter|info:eu-repo/dai/nl/314121684; Herrich, Monika; Xia, Wei; Gutfleisch, Oliver; Muhler, Martin; De Jong, Krijn P.|info:eu-repo/dai/nl/06885580X; De Jongh, Petra E.|info:eu-repo/dai/nl/186125372

    2014-01-01

    For practical solid-state hydrogen storage, reversibility under mild conditions is crucial. Complex metal hydrides such as NaAlH4 and LiBH4 have attractive hydrogen contents. However, hydrogen release and especially uptake after desorption are sluggish and require high temperatures and pressures.

  9. Measurements of capillary system degradation. [liquid hydrogen propellant retention capability

    Science.gov (United States)

    Warren, R. P.; Butz, J. R.; Maytum, C. D.; Fester, D. A.; Young, G. M.

    1975-01-01

    The effects of vibration, flow transients, and warm gas pressurization on capillary acquisition system performance were evaluated. The degradation observed under wide band random and high frequency sinusoidal vibration was of a substantially different nature from that obtained under low frequency sinusoidal vibration. With the former, ingestion of small gas bubbles into the liquid region was correlated by a hydrostatic model, while the capillary stability was destroyed and liquid was lost from the liquid region with the latter. No degradation was observed as a result of flow transients in a flight-type multichannel screen device, but it was observed in a transparent laboratory device. Liquid hydrogen outflow tests were conducted with a multilayer dual-screen-liner system with both helium and hydrogen pressurant gases. The tendency towards dryout of the device with hydrogen pressurant was found to increase with increasing pressurant temperature and length of prepressurization period. Dryout did not occur with helium pressurant.

  10. Hydrogen energy for beginners

    CERN Document Server

    2013-01-01

    This book highlights the outstanding role of hydrogen in energy processes, where it is the most functional element due to its unique peculiarities that are highlighted and emphasized in the book. The first half of the book covers the great natural hydrogen processes in biology, chemistry, and physics, showing that hydrogen is a trend that can unite all natural sciences. The second half of the book is devoted to the technological hydrogen processes that are under research and development with the aim to create the infrastructure for hydrogen energetics. The book describes the main features of hydrogen that make it inalienable player in processes such as fusion, photosynthesis, and metabolism. It also covers the methods of hydrogen production and storage, highlighting at the same time the exclusive importance of nanotechnologies in those processes.

  11. Cyclooctanaminium hydrogen succinate monohydrate

    Directory of Open Access Journals (Sweden)

    Sanaz Khorasani

    2012-04-01

    Full Text Available In the title hydrated salt, C8H18N+·C4H5O4−·H2O, the cyclooctyl ring of the cation is disordered over two positions in a 0.833 (3:0.167 (3 ratio. The structure contains various O—H.·O and N—H...O interactions, forming a hydrogen-bonded layer of molecules perpendicular to the c axis. In each layer, the ammonium cation hydrogen bonds to two hydrogen succinate anions and one water molecule. Each hydrogen succinate anion hydrogen bonds to neighbouring anions, forming a chain of molecules along the b axis. In addition, each hydrogen succinate anion hydrogen bonds to two water molecules and the ammonium cation.

  12. Technical and economic aspects of hydrogen storage in metal hydrides

    Science.gov (United States)

    Schmitt, R.

    1981-01-01

    The recovery of hydrogen from such metal hydrides as LiH, MgH2, TiH2, CaH2 and FeTiH compounds is studied, with the aim of evaluating the viability of the technique for the storage of hydrogen fuel. The pressure-temperature dependence of the reactions, enthalpies of formation, the kinetics of the hydrogen absorption and desorption, and the mechanical and chemical stability of the metal hydrides are taken into account in the evaluation. Economic aspects are considered. Development of portable metal hydride hydrogen storage reservoirs is also mentioned.

  13. Modeling Mars' Hydrogen Exosphere

    Science.gov (United States)

    Holmstrom, M.

    2006-12-01

    Traditionally, exospheric densities and velocity distributions are modelled by spherical symmetric analytical Chamberlain functions, assuming gravity is the only force acting on the neutrals. Planetary exospheres are however not spherical symmetric to any good approximation, as evident from observations, due to non- uniformexobase conditions and effects such as photoionization, radiation pressure, charge exchange, recombination and planetary rotation. To account for these effects numerical simulations are needed. Using Monte Carlo test particle simulations it is possible to account for the above effects (if ion distributions are assumed). Even though neutrals in the exospheres by definition do not collide often, collisions occur. Especially near the exobase the transition is gradual from collision dominated regions at lower heights (with Maxwellian velocity distributions) to essentially collisionless regions at greater heights. We present exospheric simulations that include collisions self consistently using the direct simulation Monte Carlo (DSMC) approach. The code is three dimensional, parallel and uses an adaptive grid, allowing many particles to be included in the simulations, leading to accurate results. In particular, we here study Mars' hydrogen exosphere and the effects of the above processes, including thermal escape rates.

  14. Ambient pressure fuel cell system

    Science.gov (United States)

    Wilson, Mahlon S.

    2000-01-01

    An ambient pressure fuel cell system is provided with a fuel cell stack formed from a plurality of fuel cells having membrane/electrode assemblies (MEAs) that are hydrated with liquid water and bipolar plates with anode and cathode sides for distributing hydrogen fuel gas and water to a first side of each one of the MEAs and air with reactant oxygen gas to a second side of each one of the MEAs. A pump supplies liquid water to the fuel cells. A recirculating system may be used to return unused hydrogen fuel gas to the stack. A near-ambient pressure blower blows air through the fuel cell stack in excess of reaction stoichiometric amounts to react with the hydrogen fuel gas.

  15. Test description and preliminary pitot-pressure surveys for Langley Test Technique Demonstrator at Mach 6

    Science.gov (United States)

    Everhart, Joel L.; Ashby, George C., Jr.; Monta, William J.

    1992-01-01

    A propulsion/airframe integration experiment conducted in the NASA Langley 20-Inch Mach 6 Tunnel using a 16.8-in.-long version of the Langley Test Technique Demonstrator configuration with simulated scramjet propulsion is described. Schlieren and vapor screen visualization of the nozzle flow field is presented and correlated with pitot-pressure flow-field surveys. The data were obtained at nominal free-stream conditions of Re = 2.8 x 10 exp 6 and a nominal engine total pressure of 100 psia. It is concluded that pitot-pressure surveys coupled to schlieren and vapor-screen photographs, and oil flows have revealed flow features including vortices, free shear layers, and shock waves occurring in the model flow field.

  16. Development of dense ceramic membranes for hydrogen separation.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Lee, T. H.; Zhang, G.; Dorris, S. E.; Rothenberger, K. S.; Martello, D. V.; Cugini, A. V.; Siriwardane, R. V.; Poston, J. A., Jr.; Fisher, E. P.

    2000-11-01

    We developed novel cermet (i.e., ceramic-metal composite) membranes for separating hydrogen from gas mixtures at high temperature and pressure. The hydrogen permeation rate in the temperature range of 600-900 C was determined for three classes of cermet membranes (ANL-1, ANL-2, and ANL-3). Among these membranes, ANL-3 showed the highest hydrogen permeation rate, with a maximum flux of 3.2 cm{sup 3}/min-cm{sup 2} for a 0.23-mm-thick membrane at 900 C. Effects of membrane thickness and hydrogen partial pressure on permeation rate indicated that bulk diffusion of hydrogen is rate-limiting for ANL-3 membranes. The lack of degradation in permeation rate during exposure to a simulated syngas mixture suggests that ANL-3 membranes are chemically stable and suitable for long-term operation.

  17. Dynamics of hydrogen in hydrogenated amorphous silicon

    Indian Academy of Sciences (India)

    bonding configuration due to hydrogen migration have been proposed as a mechanism of defect generation in a-Si:H [6,7]. Thus hydrogen plays a dual role in a-Si:H: (1) acting as a .... the sphere of radius R0 and allows to express. ∆F as a function of localization radius R0. Using eqs (10) and (11), the volume integration.

  18. Hydrogen-bond symmetrization in methane and hydrogen hydrates in the Mbar range

    Science.gov (United States)

    Bove, L. E.; Ranieri, U.; Gaal, R.; Finocchi, F.; Kuhs, W. F.; Falenty, A.; Klotz, S.; Gillet, P.

    2016-12-01

    Ice-VII and ice-X phases are the most stable forms of ice at high temperature and extreme pressures, typical of the interiors of satellites and planets. The phase transition between them is a prototypical case of quantum-driven phenomenon, as it can be described as a quantum delocalization of protons in the middle of O-O distances. Recent studies on LiCl- and NaCl-doped ice 1-3 have shown that the presence of salt inclusions in the ice lattice suppresses the quantum behavior of protons, hindering the appearance of the symmetric phase, and possibly suppressing the predicted high temperature superionic phase. This finding stimulated the investigation of similar effects in other water-based compounds, which are thought to be present in icy bodies, namely hydrogen and methane high pressure hydrates. Few experiments have been performed in the past to identify signatures of the hydrogen-bond symmetrization in methane and hydrogen hydrates without reaching conclusive results4,5. Here we present new results on the hydrogen-bond symmetrization of methane and hydrogen hydrates using Raman scattering in the Mbar range and semiclassical simulations including nuclear quantum effects. 1 Bove L. E. et al., E_ect of salt on the H-bond symmetrization in ice, Proc. Natl. Acad. Sci. USA 112, 8216, 2015 ; 2. Bronstein Y. et al., Quantum versus classical protons in pure and salty ice under pressure, Phys. Rev. B 93, 024104, 2016. 3. Klotz S. et al., Ice VII from aqueous salt solutions: From a glass to a crystal with broken H-bonds, Nature Sci. Rep. , in press. 4. Tanaka T. et al., Phase changes of _lled ice Ih methane hydrate under low temperature and high pressure, J. Chem. Phys. 139, 104701, 2013 5. Hirai H. et al., Structural changes of _lled ice Ic hydrogen hydrate under low temperatures and high pressures from 5 to 50 GPa, J. Chem. Phys. 137, 074505, 2012

  19. Measurements of Hydrogen Storage

    Science.gov (United States)

    Meisner, Gregory P.

    2004-03-01

    The many sensational claims of vast quantities of hydrogen (H) stored in carbon materials reported since 1996 have resulted in the H storage and carbon scientific literature now being cluttered with misinformation and some genuinely bad science. H storage experiments are not trivial, and they are prone to error and misinterpretation. For example, volumetric experiments use equilibrium gas pressures (P) and temperatures (T) measured in calibrated volumes to determine the number of moles of gas, and changes in P without changes in T (or leakage) are then interpreted as sorption. A typical mistake is measuring P vs. time after pressurizing a sample chamber and interpreting a drop in P as sorption. This is difficult to interpret as real absorption because all confounding effects (leaks, T drifts, thermal inhomogeneities, etc.) are nearly impossible to eliminate. Moreover, the basic thermodynamic properties of gas flow systems tell us that high-P gases filling evacuated chambers experience non-negligible rises in T. Another example of misinterpretation arises in gravimetric experiments that use weight (W) measurements corrected for large T-dependent buoyancy effects to determine gas sorption. Here a typical mistake is interpreting the actual sorption of heavy residual impurity gases as H sorption. These and other techniques for measuring H sorption must be performed and interpreted with great care due to difficulties associated with small sample sizes, high gas pressures, very reactive materials, contamination, low signal-to-noise, poor experimental design, and, in some cases, bad science. Good science respects the difference between measurement precision (the number of significant digits of P or W measurements) and experimental accuracy (the degree of certainty that P or W changes really represent H sorption). At General Motors, we endeavor to understand, conduct, and promote reliable H storage measurements on new materials and routinely use both volumetric

  20. Kinetic Monte Carlo study on the evolution of silicon surface roughness under hydrogen thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gang; Wang, Yu; Wang, Junzhuan; Pan, Lijia; Yu, Linwei; Zheng, Youdou; Shi, Yi, E-mail: yshi@nju.edu.cn

    2017-08-31

    Highlights: • The KMC method is adopted to investigate the relationships between surface evolution and hydrogen thermal treatment conditions. • The reduction in surface roughness is divided into two stages at relatively low temperatures, both exhibiting exponential dependence on the time. • The optimized surface structure can be obtained by precisely adjusting thermal treatment temperatures and hydrogen pressures. - Abstract: The evolution of a two-dimensional silicon surface under hydrogen thermal treatment is studied by kinetic Monte Carlo simulations, focusing on the dependence of the migration behaviors of surface atoms on both the temperature and hydrogen pressure. We adopt different activation energies to analyze the influence of hydrogen pressure on the evolution of surface morphology at high temperatures. The reduction in surface roughness is divided into two stages, both exhibiting exponential dependence on the equilibrium time. Our results indicate that a high hydrogen pressure is conducive to obtaining optimized surfaces, as a strategy in the applications of three-dimensional devices.