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Sample records for temperature hydrogen attack

  1. Effect of microstructures on the hydrogen attack to gamma titanium aluminide at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hamzah, E. [Faculty of Mechanical Engineering, Universiti Technologi Malaysia 81310, Johor Bahru (Malaysia)]. E-mail: esah@fkm.utm.my; Suardi, K. [Faculty of Mechanical Engineering, Universiti Technologi Malaysia 81310, Johor Bahru (Malaysia); Ourdjini, A. [Faculty of Mechanical Engineering, Universiti Technologi Malaysia 81310, Johor Bahru (Malaysia)

    2005-04-25

    Intermetallic alloys based on gamma titanium aluminide are now regarded as promising candidates for high temperature applications such as for aerospace, marine and automotive engine components, due to their high specific strength and modulus. Their oxidation resistance is good, especially at intermediate and high temperature; oxidation resistance can be obtained up to 800 deg. C. One critical area of application is in combustion engines in aerospace vehicles such as hypersonic airplanes and high-speed civil transport airplanes. This entails the use of hydrogen as a fuel component and it has been widely reported by researchers that these materials exhibit corrosion in the form of environment embrittlement in the presence of hydrogen. A fair amount of research has been carried out to investigate the influence of hydrogen in {gamma}-titanium aluminide. Some researchers reported that {alpha}{sub 2} and lamellar phases had major influence in the susceptible of hydrogen to alloys, while hydrogen is too low to penetrate the {gamma}-phases. This research focused on the effect of different microstructures of {gamma}-titanium aluminide to the diffusion coefficient of hydrogen (D) and the corrosion product after hydrogen attack. Modification of {gamma}-titanium aluminide can be achieved by heat treatment of as-cast binary samples Ti-45% Al and Ti-48% Al. All samples were then subjected to corrosion attack under cathodically charged with galvanostatic mode for 6 h. The potential variation with time was monitored from these data the values of the diffusion coefficient of hydrogen (D) to {gamma}-titanium aluminide was obtained. D was calculated based on Fick's second Law. These results were compared with that obtained from micro-Vickers hardness profiling, which was measured at cross-section area per depth from the top corroded surface. The hardness values were calculated using the error function equation. An image analyzer; X-ray diffraction (XRD); scanning electron

  2. Effect of microstructures on the hydrogen attack to gamma titanium aluminide at low temperature

    International Nuclear Information System (INIS)

    Hamzah, E.; Suardi, K.; Ourdjini, A.

    2005-01-01

    Intermetallic alloys based on gamma titanium aluminide are now regarded as promising candidates for high temperature applications such as for aerospace, marine and automotive engine components, due to their high specific strength and modulus. Their oxidation resistance is good, especially at intermediate and high temperature; oxidation resistance can be obtained up to 800 deg. C. One critical area of application is in combustion engines in aerospace vehicles such as hypersonic airplanes and high-speed civil transport airplanes. This entails the use of hydrogen as a fuel component and it has been widely reported by researchers that these materials exhibit corrosion in the form of environment embrittlement in the presence of hydrogen. A fair amount of research has been carried out to investigate the influence of hydrogen in γ-titanium aluminide. Some researchers reported that α 2 and lamellar phases had major influence in the susceptible of hydrogen to alloys, while hydrogen is too low to penetrate the γ-phases. This research focused on the effect of different microstructures of γ-titanium aluminide to the diffusion coefficient of hydrogen (D) and the corrosion product after hydrogen attack. Modification of γ-titanium aluminide can be achieved by heat treatment of as-cast binary samples Ti-45% Al and Ti-48% Al. All samples were then subjected to corrosion attack under cathodically charged with galvanostatic mode for 6 h. The potential variation with time was monitored from these data the values of the diffusion coefficient of hydrogen (D) to γ-titanium aluminide was obtained. D was calculated based on Fick's second Law. These results were compared with that obtained from micro-Vickers hardness profiling, which was measured at cross-section area per depth from the top corroded surface. The hardness values were calculated using the error function equation. An image analyzer; X-ray diffraction (XRD); scanning electron microscope (SEM) and secondary ion mass

  3. Alloys influence in ferritic steels with hydrogen attack

    International Nuclear Information System (INIS)

    Moro, L; Rey Saravia, D; Lombardich, J; Saggio, M; Juan, A; Blanco, J

    2003-01-01

    Materials exposed to a corrosive environment and high temperatures, are associated with a decrease of their mechanical properties and embitterment.At room temperatures atomic hydrogen diffuses easily through metals structure, it accumulates in lattice defects forming molecular hydrogen and generating cracking due to internal stresses.Under high temperatures the phenomenon is more complex.The steels in these conditions present different structures of precipitates, that the change under creep conditions period.In this work it is determined the influence of Cr and V alloys, the changes of ferritic steel resistance in a corrosive environment and high temperatures.1.25 Cr 1 Mo 0.25 V and 2.25Cr 1 Mo under different loads and temperatures previously attacked by hydrogen environment.The hydrogen is induced by the electrolytic technique, optimizing the choice of temperatures, current density, electrolyte, etc. In order to control an adequate cathode charge, a follow up procedure is carried out by electronic barrier microscopy.After the attack, the material is settled at room temperatures for certain period of time, to allow the hydrogen to leave and evaluate the residual damage.Creep by torsion assays, under constant load and temperature is used as an experimental technique.With the outcome data curves are drawn in order to study the secondary creep rate, with the applied load and temperature, determining the value of stress exponent n and the activation energy Q.Comparing to equal assays to the same ferritic steels but non attacked by hydrogen, these values allows the prediction of microstructure changes present during these tests

  4. A continuum damage analysis of hydrogen attack in 2.25 Cr-1Mo vessel

    DEFF Research Database (Denmark)

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

    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...... 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 of hydrogen pressure, temperature and stresses result in a nonuniform damage distribution over the vessel wall. Stresses inside the vessel wall first tend to accelerate...

  5. Hydrogen attack evaluation of boiler tube using ultrasonic wave

    International Nuclear Information System (INIS)

    Won, Soon Ho; Hyun, Yang Ki; Lee, Jong O; Cho, Kyung Shik; Lee, Jae Do

    2001-01-01

    The presence of hydrogen in industrial plants is a source of damage. Hydrogen attack is one such form of degradation and often causing large tube ruptures that necessitate an immediate shutdown. Hydrogen attack may reduce the fracture toughness as well as the strength of steels. This reduction is caused partially by the presence of cavities and microcracks at the grain boundaries. In the past several techniques have been used with limited results. This paper describes the application of an ultrasonic velocity, attenuation and backscatter techniques for detecting the presence of hydrogen damage in utility boiler tubes. Ultrasonic tests showed a decrease in wave velocity and an increase in attenuation. Such results demonstrate the potential for ultrasonic nondestructive testing to quantify damage. Based on this study, recommendations are that both velocity and attenuation be used to detect hydrogen attack in steels.

  6. Hydrogen attack of pressure-vessel steel. Progress report, April 1, 1980-March 31, 1981

    International Nuclear Information System (INIS)

    Shewmon, P.G.

    1980-12-01

    The nucleation and growth of methane bubbles in the hydrogen attack of pressure vessel steel has been shown to obey models developed to describe the growth of bubbles limiting the creep ductility of metals. This has been done through studies of the effect of prior deformation on bubble nucleation as well as the effect of methane pressure (stress) and temperature on growth kinetics. A comprehensive model of the factors limiting growth has been developed. Its application to the hydrogen attack of a 2 1/4 Cr-1 Mo steel leads to several interesting predictions

  7. A Study on the VHCF Fatigue Behaviors of Hydrogen Attacked Inconel 718 Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Chang-Min [Kyungpook National Univ., DMI Senior Fellow, Daegu (Korea, Republic of); Nahm, Seung-Hoon [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Kim, Jun-Hyong; Pyun, Young-Sik [Sun Moon Univ., Chunan (Korea, Republic of)

    2016-07-15

    This study is to investigate the influence of hydrogen attack and UNSM on fatigue behaviors of the Inconel 718 alloy. The decrease of the fatigue life between the untreated and the hydrogen attacked material is 10-20%. The fatigue lives of hydrogen attacked specimen decreased without a fatigue limit, similar to those of nonferrous materials. Due to hydrogen embrittlement, about 80% of the surface cracks were smaller than the average grain size of 13 μm. Many small surface cracks caused by the embrittling effect of hydrogen attack were initiated at the grain boundaries and surface scratches. Cracks were irregularly distributed, grew, and then coalesced through tearing, leading to a reduction of fatigue life. Results revealed that the fatigue lives of UNSM-treated specimens were longer than those of the untreated specimens.

  8. Hydrogen migration in Lu at low temperatures

    International Nuclear Information System (INIS)

    Yamakawa, K.

    1997-01-01

    The migration of hydrogen in Lu is determined by electrical resistance measurements in temperature range of 140-170 K. Disordered hydrogen atoms, which are formed by quenching, migrate to order during annealing in the above temperature range. The rate of the resistance decrease depends on the ordering rate of hydrogen. From the resistance decrease during isothermal annealings, the activation energy of hydrogen migration is determined as 0.43 eV (41.5 kJ mol -1 ). (orig.)

  9. Low Temperature Hydrogen Antihydrogen Interactions

    International Nuclear Information System (INIS)

    Armour, E. A. G.; Chamberlain, C. W.

    2001-01-01

    In view of current interest in the trapping of antihydrogen (H-bar) atoms at low temperatures, we have carried out a full four-body variational calculation to determine s-wave elastic phase shifts for hydrogen antihydrogen scattering, using the Kohn Variational Principle. Terms outside the Born-Oppenheimer approximation have been taken into account using the formalism of Kolos and Wolniewicz. As far as we are aware, this is the first time that these terms have been included in an H H-bar scattering calculation. This is a continuation of earlier work on H-H-bar interactions. Preliminary results differ substantially from those calculated using the Born-Oppenheimer approximation. A method is outlined for reducing this discrepancy and taking the rearrangement channel into account.

  10. BEHAVIOR OF THERMAL SPRAY COATINGS AGAINST HYDROGEN ATTACK

    OpenAIRE

    Vargas, Fabio; Latorre, Guillermo; Uribe, Iván

    2003-01-01

    The behavior of nickel and chrome alloys applied as thermal spray coatings to be used as protection against embrittlement by hydrogen is studied. Coatings were applied on a carbon steel substrate, under conditions that allow obtain different crystalline structures and porosity levels, in order to determine the effect of these variables on the hydrogen permeation kinetics and as a protection means against embrittlement caused this element. In order to establish behaviors as barriers and protec...

  11. Hydrogen-Atom Attack on Methyl Viologen in Aqueous Solution Studied by Pulse Radiolysis

    DEFF Research Database (Denmark)

    Solar, S.; Solar, W.; Getoff, N.

    1984-01-01

    Using hydrogen at high pressures of up to 150 bar (0.12 mol dm–3 H2) as an OH scavenger in aqueous MV2+ solutions (pH 1) it is possible to differentiate between two kinds of transient formed simultaneously by H-atom attack on methyl viologen. One of them is assigned to an H adduct on the N atom, ...

  12. Hydrogen attack of steel. Progress report, April 1, 1978--March 31, 1979

    International Nuclear Information System (INIS)

    Shewmon, P.G.

    1978-01-01

    Four normalized carbon steels made in different ways (Si-killed, Al-killed, REM-treated, and electroslag refined) were studied to determine the role of differing fine inclusions on the early stages of hydrogen attack (HA). Hydrogen exposures were made at 450 0 C (6.5 MPa) and 375 0 C (7.6 MPa). The first stage of HA is shown to be the development of a closely spaced (1-2 μm) array of small bubbles over the ferrite/pearlite, or occasionally the ferrite/ferrite boundaries. These grew together to form tears, primarily in the rolling plane, leading to more rapid expansion normal to this plane. The planes of separation followed high solute layers in banded steel but only rarely did the fracture surfaces follow inclusions. At 450 0 C REM-treated steel was attacked the fastest and the Al-killed steel took two to four times as long for attack

  13. Nickel brittling by hydrogen. Temperature effect

    International Nuclear Information System (INIS)

    Lapitz, P.A; Fernandez, S; Alvarez, M.G

    2006-01-01

    The results of a study on the effect of different variables on the susceptibility to brittling by hydrogen and the velocity of propagation of fissures in nickel wire (99.7% purity) are described. The hydrogen load was carried out by cathodic polarization in H 2 SO 4 0.5m solution. The susceptibility to brittling by hydrogen was determined with traction tests at slow deformation speed and constant cathodic potential, and the later observation of the fracture surface by scanning electron microscopy. The variables studied were: applied cathodic overpower, speed of initial deformation and temperature. The results showed that the speed of fissure propagation in the nickel by brittleness from hydrogen is a function of the applied potential and the speed of deformation used. Without tension, the hydrogen load by cathodic polarization at room temperature leads to the formation of cavities similar to those observed when the hydrogenation is performed in the presence of gaseous hydrogen at high pressure and temperature (CW)

  14. Hydrogen Production from Nuclear Energy via High Temperature Electrolysis

    International Nuclear Information System (INIS)

    James E. O'Brien; Carl M. Stoots; J. Stephen Herring; Grant L. Hawkes

    2006-01-01

    This paper presents the technical case for high-temperature nuclear hydrogen production. A general thermodynamic analysis of hydrogen production based on high-temperature thermal water splitting processes is presented. Specific details of hydrogen production based on high-temperature electrolysis are also provided, including results of recent experiments performed at the Idaho National Laboratory. Based on these results, high-temperature electrolysis appears to be a promising technology for efficient large-scale hydrogen production

  15. Relation of temperature and humidity to the risk of recurrent gout attacks.

    Science.gov (United States)

    Neogi, Tuhina; Chen, Clara; Niu, Jingbo; Chaisson, Christine; Hunter, David J; Choi, Hyon; Zhang, Yuqing

    2014-08-15

    Gout attack risk may be affected by weather (e.g., because of volume depletion). We therefore examined the association of temperature and humidity with the risk of recurrent gout attacks by conducting an internet-based case-crossover study in the United States (in 2003-2010) among subjects with a diagnosis of gout who had 1 or more attacks during 1 year of follow-up. We examined the association of temperature and humidity over the prior 48 hours with the risk of gout attacks using a time-stratified approach and conditional logistic regression. Among 632 subjects with gout, there was a significant dose-response relationship between mean temperature in the prior 48 hours and the risk of subsequent gout attack (P = 0.01 for linear trend). Higher temperatures were associated with approximately 40% higher risk of gout attack compared with moderate temperatures. There was a reverse J-shaped relationship between mean relative humidity and the risk of gout attacks (P = 0.03 for quadratic trend). The combination of high temperature and low humidity had the greatest association (odds ratio = 2.04, 95% confidence interval: 1.26, 3.30) compared with moderate temperature and relative humidity. Thus, high ambient temperature and possibly extremes of humidity were associated with an increased risk of gout attack, despite the likelihood that individuals are often in climate-controlled indoor environments. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. The permeation of hydrogen in a steel at elevated temperature by an electrochemical method

    International Nuclear Information System (INIS)

    Tsubakino, H.; Ando, A.; Yamakawa, K.

    1984-01-01

    An electrochemical permeation method has been widely used to study the transport characteristics of hydrogen in metals, i.e., the content, diffusivity and permeability. This electrochemical measurement technique has the following remarkable features: a good detection limit for the measurement of hydrogen content, a simpler measuring apparatus, suitability for successive measurement of the transport characteristics, and flexibility in variation of experimental conditions. However this method has been restricted to temperatures below 373 K because an aqueous solution has been used as an electrode. In this study, an electrochemical permeation method using molten salts at elevated temperatures (673-773 K) in the range of practical interest for hydrogen attack in steel is presented. The introduction of hydrogen by use of molten salts has been reported but it has been performed at 423473 K and at 553 K

  17. Metallic Membranes for High Temperature Hydrogen Separation

    DEFF Research Database (Denmark)

    Ma, Y.H.; Catalano, Jacopo; Guazzone, Federico

    2013-01-01

    membrane fabrication methods have matured over the last decades, and the deposition of very thin films (1–5 µm) of Pd over porous ceramics or modified porous metal supports is quite common. The H2 permeances and the selectivities achieved at 400–500 °C were in the order of 50–100 Nm3/m/h/bar0.5 and greater......Composite palladium membranes have extensively been studied in laboratories and, more recently, in small pilot industrial applications for the high temperature separation of hydrogen from reactant mixtures such as water-gas shift (WGS) reaction or methane steam reforming (MSR). Composite Pd...... than 1000, respectively. This chapter describes in detail composite Pd-based membrane preparation methods, which consist of the grading of the support and the deposition of the dense metal layer, their performances, and their applications in catalytic membrane reactors (CMRs) at high temperatures (400...

  18. The equilibrium hydrogen pressure-temperature diagram for the liquid sodium-hydrogen-oxygen system

    International Nuclear Information System (INIS)

    Knights, C.F.; Whittingham, A.C.

    1982-01-01

    The underlying equilibria in the sodium-hydrogen-oxygen system are presented in the form of a completmentary hydrogen equilibrium pressure-temperature diagram, constructed by using published data and supplemented by experimental measurements of hydrogen equilibrium pressures over condensed phases in the system. Possible applications of the equilibrium pressure-temperature phase diagram limitations regarding its use are outlined

  19. Ultrasonic and metallographic studies on AISI 4140 steel exposed to hydrogen at high pressure and temperature

    Science.gov (United States)

    Oruganti, Malavika

    This thesis conducts an investigation to study the effects of hydrogen exposure at high temperature and pressure on the behavior of AISI 4140 steel. Piezoelectric ultrasonic technique was primarily used to evaluate surface longitudinal wave velocity and defect geometry variations, as related to time after exposure to hydrogen at high temperature and pressure. Critically refracted longitudinal wave technique was used for the former and pulse-echo technique for the latter. Optical microscopy and scanning electron microscopy were used to correlate the ultrasonic results with the microstructure of the steel and to provide better insight into the steel behavior. The results of the investigation indicate that frequency analysis of the defect echo, determined using the pulse-echo technique at regular intervals of time, appears to be a promising tool for monitoring defect growth induced by a high temperature and high pressure hydrogen-related attack.

  20. Ceramic membranes for high temperature hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Adcock, K.D.; Fain, D.E.; James, D.L.; Powell, L.E.; Raj, T.; Roettger, G.E.; Sutton, T.G. [East Tennessee Technology Park, Oak Ridge, TN (United States)

    1997-12-01

    The separative performance of the authors` ceramic membranes has been determined in the past using a permeance test system that measured flows of pure gases through a membrane at temperatures up to 275 C. From these data, the separation factor was determined for a particular gas pair from the ratio of the pure gas specific flows. An important project goal this year has been to build a Mixed Gas Separation System (MGSS) for measuring the separation efficiencies of membranes at higher temperatures and using mixed gases. The MGSS test system has been built, and initial operation has been achieved. The MGSS is capable of measuring the separation efficiency of membranes at temperatures up to 600 C and pressures up to 100 psi using a binary gas mixture such as hydrogen/methane. The mixed gas is fed into a tubular membrane at pressures up to 100 psi, and the membrane separates the feed gas mixture into a permeate stream and a raffinate stream. The test membrane is sealed in a stainless steel holder that is mounted in a split tube furnace to permit membrane separations to be evaluated at temperatures up to 600 C. The compositions of the three gas streams are measured by a gas chromatograph equipped with thermal conductivity detectors. The test system also measures the temperatures and pressures of all three gas streams as well as the flow rate of the feed stream. These data taken over a range of flows and pressures permit the separation efficiency to be determined as a function of the operating conditions. A mathematical model of the separation has been developed that permits the data to be reduced and the separation factor for the membrane to be determined.

  1. Dependence of hydrogen-induced lattice defects and hydrogen embrittlement of cold-drawn pearlitic steels on hydrogen trap state, temperature, strain rate and hydrogen content

    International Nuclear Information System (INIS)

    Doshida, Tomoki; Takai, Kenichi

    2014-01-01

    The effects of the hydrogen state, temperature, strain rate and hydrogen content on hydrogen embrittlement susceptibility and hydrogen-induced lattice defects were evaluated for cold-drawn pearlitic steel that absorbed hydrogen in two trapping states. Firstly, tensile tests were carried out under various conditions to evaluate hydrogen embrittlement susceptibility. The results showed that peak 2 hydrogen, desorbed at temperatures above 200 °C as determined by thermal desorption analysis (TDA), had no significant effect on hydrogen embrittlement susceptibility. In contrast, hydrogen embrittlement susceptibility increased in the presence of peak 1 hydrogen, desorbed from room temperature to 200 °C as determined by TDA, at temperatures higher than −30 °C, at lower strain rates and with higher hydrogen content. Next, the same effects on hydrogen-induced lattice defects were also evaluated by TDA using hydrogen as a probe. Peak 2 hydrogen showed no significant effect on either hydrogen-induced lattice defects or hydrogen embrittlement susceptibility. It was found that hydrogen-induced lattice defects formed under the conditions where hydrogen embrittlement susceptibility increased. This relationship indicates that hydrogen embrittlement susceptibility was higher under the conditions where the formation of hydrogen-induced lattice defects tended to be enhanced. Since hydrogen-induced lattice defects formed by the interaction between hydrogen and strain were annihilated by annealing at a temperature of 200 °C, they were presumably vacancies or vacancy clusters. One of the common atomic-level changes that occur in cold-drawn pearlitic steel showing higher hydrogen embrittlement susceptibility is the formation of vacancies and vacancy clusters

  2. Low temperature, low pressure hydrogen gettering

    International Nuclear Information System (INIS)

    Anderson, D.R.; Courtney, R.L.; Harrah, L.A.

    1975-01-01

    A system is described for the gettering of hydrogen and its isotopes. The gettering materials are painted or coated onto, or otherwise disposed in an area or volume from which hydrogen is to be removed

  3. The effects of stress, anxiety, and outdoor temperature on the frequency and severity of Raynaud's attacks: the Raynaud's Treatment Study.

    Science.gov (United States)

    Brown, K M; Middaugh, S J; Haythornthwaite, J A; Bielory, L

    2001-04-01

    It was expected that stress and anxiety would be related to Raynaud's phenomenon (RP) attack characteristics when mild outdoor temperatures produced partial or no digital vasoconstriction. Hypotheses were that in warmer temperature categories, compared to those below 40 degrees F, higher stress or anxiety would be associated with more frequent, severe, and painful attacks. The Raynaud's Treatment Study recruited 313 participants with primary RP. Outcomes were attack rate, severity, and pain. Predictors were average daily outdoor temperature, stress, anxiety, age, gender, and a stress-by-temperature or an anxiety-by-temperature interaction. Outcomes were tested separately in multiple linear regression models. Stress and anxiety were tested in separate models. Stress was not a significant predictor of RP attack characteristics. Higher anxiety was related to more frequent attacks above 60 degrees F. It was also related to greater attack severity at all temperatures, and to greater pain above 60 degrees F and between 40 degrees and 49.9 degrees F.

  4. Ceramic membranes for high temperature hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  5. 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.

  6. Low temperature ultrasonic study of hydrogen in niobium

    International Nuclear Information System (INIS)

    Poker, D.B.

    1979-01-01

    Measurements were made of the velocity and attenuation of ultrasonic waves in niobium containing 1000 ppM oxygen with additional concentrations of hydrogen, to determine the properties of a relaxation of the hydrogen which appears below 10 K. Measurements were made as a function of temperature, frequency, polarization of the ultrasonic wave, hydrogen isotope, and concentration of hydrogen and oxygen. The Birnbaum--Flynn model of hydrogen tunnelling is modified to take into account the trapping of hydrogen by interstitial impurities. An Orbach process is proposed for a relaxation between the degenerate first excited states. Three parameters which are determined by the hydrogen ultrasonic attenuation data are sufficient to describe the properties of this model. The model correctly predicts the presence of unusual features of the relaxation which are not contained in a classical model of hydrogen motion over a potential barrrier; the decrease of the hydrogen relaxation strength at low temperatures, the decrease in velocity below the relaxation temperature without a corresponding effect in the attenuation, and the broadness of the deuterium decrement peak compared to that for hydrogen. A reasonable fit to the velocity data for low concentration of hydrogen is made by the model with no adjustable parameters. A fit to the heat capacity can be made with the addition of parameters representing the strain effects of the oxygen trapping

  7. Gas generation from radiolytic attack of TRU-contaminated hydrogenous waste

    International Nuclear Information System (INIS)

    Zerwekh, A.

    1979-06-01

    In 1970, the Waste Management and Transportation Division of the Atomic Energy Commission ordered a segregation of transuranic (TRU)-contaminated solid wastes. Those below a contamination level of 10 nCi/g could still be buried; those above had to be stored retrievably for 20 y. The possibility that alpha-radiolysis of hydrogenous materials might produce toxic, corrosive, and flammable gases in retrievably stored waste prompted an investigation of gas identities and generation rates in the laboratory and field. Typical waste mixtures were synthesized and contaminated for laboratory experiments, and drums of actual TRU-contaminated waste were instrumented for field testing. Several levels of contamination were studied, as well as pressure, temperature, and moisture effects. G (gas) values were determined for various waste matrices, and degradation products were examined

  8. An effective temperature compensation approach for ultrasonic hydrogen sensors

    Science.gov (United States)

    Tan, Xiaolong; Li, Min; Arsad, Norhana; Wen, Xiaoyan; Lu, Haifei

    2018-03-01

    Hydrogen is a kind of promising clean energy resource with a wide application prospect, which will, however, cause a serious security issue upon the leakage of hydrogen gas. The measurement of its concentration is of great significance. In a traditional approach of ultrasonic hydrogen sensing, a temperature drift of 0.1 °C results in a concentration error of about 250 ppm, which is intolerable for trace amount of gas sensing. In order to eliminate the influence brought by temperature drift, we propose a feasible approach named as linear compensation algorithm, which utilizes the linear relationship between the pulse count and temperature to compensate for the pulse count error (ΔN) caused by temperature drift. Experimental results demonstrate that our proposed approach is capable of improving the measurement accuracy and can easily detect sub-100 ppm of hydrogen concentration under variable temperature conditions.

  9. Hydrogen yield from low temperature steam reforming of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Das, N.K.; Dalai, A.K. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Chemical Engineering, Catalysis and Chemical Reaction Engineering Laboratories; Ranganathan, R. [Saskatchewan Research Council, Saskatoon, SK (Canada)

    2007-02-15

    Interest in the use of ethanol for fuel cell hydrogen production was discussed with particular reference to a study in which the production of hydrogen was maximized through low temperature steam reforming of ethanol in the temperature range of 200 to 360 degrees C. The primary objective of this study was to determine the effect of Mn concentration on a Cu/Al{sub 2}O{sub 3} catalyst for steam reforming of ethanol to produce hydrogen. The purpose was to maximize ethanol conversion and hydrogen selectivity in the lowest possible reaction temperature for the ideal catalyst activity. The optimum reaction conditions in the presence of a suitable catalyst can produce the desired products of hydrogen and carbon dioxide. Cu/Al{sub 2}O{sub 3} catalysts with six different concentrations ranging from 0 to 10 weight per cent Mn, were prepared, characterized and studied for the ethanol-steam reforming reaction. The effects of different process variables were studied, including water-to-ethanol feed ratio, space time and catalyst reduction temperatures on ethanol conversion and hydrogen yield. Maximum ethanol conversion of 60.7 per cent and hydrogen yield of 3.74 (mol of hydrogen per mol of ethanol converted) were observed at 360 degrees C for a catalyst with 2.5 weight per cent Mn loading. 29 refs., 3 tabs., 12 figs.

  10. Intermolecular hydrogen bonds: From temperature-driven proton ...

    Indian Academy of Sciences (India)

    Abstract. We have combined neutron scattering and a range of numerical simulations to study hydrogen bonds in condensed matter. Two examples from a recent thesis will be presented. The first concerns proton transfer with increasing temperature in short inter- molecular hydrogen bonds [1,2]. These bonds have unique ...

  11. Amide proton temperature coefficients as hydrogen bond indicators in proteins

    International Nuclear Information System (INIS)

    Cierpicki, Tomasz; Otlewski, Jacek

    2001-01-01

    Correlations between amide proton temperature coefficients (Δσ HN /ΔT) and hydrogen bonds were investigated for a data set of 793 amides derived from 14 proteins. For amide protons showing temperature gradients more positive than -4.6 ppb/K there is a hydrogen bond predictivity value exceeding 85%. It increases to over 93% for amides within the range between -4 and -1 ppb/K. Detailed analysis shows an inverse proportionality between amide proton temperature coefficients and hydrogen bond lengths. Furthermore, for hydrogen bonds of similar bond lengths, values of temperature gradients in α-helices are on average 1 ppb/K more negative than in β-sheets. In consequence, a number of amide protons in α-helices involved in hydrogen bonds shorter than 2 A show Δσ HN /ΔT 10 helices and 98% in β-turns have temperature coefficients more positive than -4.6ppb/K. Ring current effect also significantly influences temperature coefficients of amide protons. In seven out of eight cases non-hydrogen bonded amides strongly deshielded by neighboring aromatic rings show temperature coefficients more positive than -2 ppb/K. In general, amide proton temperature gradients do not change with pH unless they correspond to conformational changes. Three examples of pH dependent equilibrium showing hydrogen bond formation at higher pH were found. In conclusion, amide proton temperature coefficients offer an attractive and simple way to confirm existence of hydrogen bonds in NMR determined structures

  12. Low-temperature diffusion of hydrogen isotopes in tantalum

    International Nuclear Information System (INIS)

    Peichl, R.; Ziegler, P.; Weidinger, A.

    1987-01-01

    The mobility of hydrogen and deuterium in tantalum is investigated in the temperature range between 4.2 and 30 K. On the time scale of the present experiment (25 μs) we find that hydrogen begins to move above 15 K whereas deuterium remains immobile at least up to 30 K. Since the interpretation of the data depends critically on the exact hydrogen configurations a major part of the paper is devoted to this problem. We suggest that hydrogen can exist in fairly localized or more extended states depending on the local homogeneity of the crystal. (orig.)

  13. High temperature equation of state of metallic hydrogen

    International Nuclear Information System (INIS)

    Shvets, V. T.

    2007-01-01

    The equation of state of liquid metallic hydrogen is solved numerically. Investigations are carried out at temperatures from 3000 to 20 000 K and densities from 0.2 to 3 mol/cm 3 , which correspond both to the experimental conditions under which metallic hydrogen is produced on earth and the conditions in the cores of giant planets of the solar system such as Jupiter and Saturn. It is assumed that hydrogen is in an atomic state and all its electrons are collectivized. Perturbation theory in the electron-proton interaction is applied to determine the thermodynamic potentials of metallic hydrogen. The electron subsystem is considered in the randomphase approximation with regard to the exchange interaction and the correlation of electrons in the local-field approximation. The proton-proton interaction is taken into account in the hard-spheres approximation. The thermodynamic characteristics of metallic hydrogen are calculated with regard to the zero-, second-, and third-order perturbation theory terms. The third-order term proves to be rather essential at moderately high temperatures and densities, although it is much smaller than the second-order term. The thermodynamic potentials of metallic hydrogen are monotonically increasing functions of density and temperature. The values of pressure for the temperatures and pressures that are characteristic of the conditions under which metallic hydrogen is produced on earth coincide with the corresponding values reported by the discoverers of metallic hydrogen to a high degree of accuracy. The temperature and density ranges are found in which there exists a liquid phase of metallic hydrogen

  14. Performance of CVD and CVR coated carbon-carbon in high temperature hydrogen

    Science.gov (United States)

    Adams, J. W.; Barletta, R. E.; Svandrlik, J.; Vanier, P. E.

    As a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings which will be time and temperature stable at extremely high temperatures in flowing hydrogen. These coatings must protect the underlying carbon structure from attack by the hydrogen coolant. Degradation which causes small changes in the reactor component, e.g. hole diameter in the hot frit, can have a profound effect on operation. The ability of a component to withstand repeated temperature cycles is also a coating development issue. Coatings which crack or spall under these conditions would be unacceptable. While refractory carbides appear to be the coating material of choice for carbon substrates being used in PBR components, the method of applying these coatings can have a large effect on their performance. Two deposition processes for these refractory carbides, chemical vapor deposition (CVD) and chemical vapor reaction (CVR), have been evaluated. Screening tests for these coatings consisted of testing of coated 2-D and 3-D weave carbon-carbon in flowing hot hydrogen at one atmosphere. Carbon loss from these samples was measured as a function of time. Exposure temperatures up to 3,000 K were used, and samples were exposed in a cyclical fashion cooling to room temperature between exposures. The results of these measurements are presented along with an evaluation of the relative merits of CVR and CVD coatings for this application.

  15. Nanodiamond for hydrogen storage: temperature-dependent hydrogenation and charge-induced dehydrogenation.

    Science.gov (United States)

    Lai, Lin; Barnard, Amanda S

    2012-02-21

    Carbon-based hydrogen storage materials are one of hottest research topics in materials science. Although the majority of studies focus on highly porous loosely bound systems, these systems have various limitations including use at elevated temperature. Here we propose, based on computer simulations, that diamond nanoparticles may provide a new promising high temperature candidate with a moderate storage capacity, but good potential for recyclability. The hydrogenation of nanodiamonds is found to be easily achieved, in agreement with experiments, though we find the stability of hydrogenation is dependent on the morphology of nanodiamonds and surrounding environment. Hydrogenation is thermodynamically favourable even at high temperature in pure hydrogen, ammonia, and methane gas reservoirs, whereas water vapour can help to reduce the energy barrier for desorption. The greatest challenge in using this material is the breaking of the strong covalent C-H bonds, and we have identified that the spontaneous release of atomic hydrogen may be achieved through charging of hydrogenated nanodiamonds. If the degree of induced charge is properly controlled, the integrity of the host nanodiamond is maintained, which indicates that an efficient and recyclable approach for hydrogen release may be possible. This journal is © The Royal Society of Chemistry 2012

  16. Hydrogen-Antihydrogen Collisions at Cold Temperatures

    Science.gov (United States)

    Zygelman, Bernard

    2001-05-01

    With the CERN anti-proton de-accelerator now on line, it is anticipated that antihydrogen ( \\overline H) atoms will be created, cooled, and stored in large numbers (M. H. Holzscheitner and M. Charlton, Rep. Prog. Phys. 62),1 (1999). It has recently been proposed that the introduction of cold, spin-polarized, hydrogen atoms into a gas of trapped anti-hydrogen could allow the sympathetic cooling of the anti-hydrogen into the sub-Kelvin regime (P. Froelich, S. Jonsell, A.Saenz, B. Zygelman, and A. Dalgarno, Phys. Rev. Lett. 84), 4577 (2000). In this talk we will present the results of calculations that estimate the rate of elastic scattering of H with \\overline H, and compare that to the rate in which the fragmentation reaction, H + \\overline H arrow p \\overline p + e^+ e^- occurs and limits the utility of sympathetic cooling. Unlike the ground state of the H2 system, the H \\overline H system possesses a non-vanishing electric dipole moment (B. Zygelman, A. Saenz, P. Froelich, S. Jonsell and A. Dalgarno, Phys. Rev. A, in Press (2001).) that allows for the additional inelastic reaction H + \\overline H arrow H\\overline H^* + h ν , where H \\overline H^* is a quasi-bound state of the hydrogen-antihydrogen complex. The rate for radiative association into quasi-bound states of the H \\overline H^* complex will be presented and we will explore the viability for the spectroscopic study of this novel four-body matter-antimatter system. Collaborators in this study include, A. Dalgarno, P. Froelich, A. Saenz and S. Jonsell. I wish to thank the Institute for Theoretical Atomic and Molecular Physics (ITAMP) for their hospitality and support during sabbatical leave where part of this work was done. Partial support was provided by NSF grants to the Smithsonian Institution and Harvard University for ITAMP.

  17. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    International Nuclear Information System (INIS)

    Nakano, H.; Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-01-01

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure

  18. Predictions of glass transition temperature for hydrogen bonding biomaterials.

    Science.gov (United States)

    van der Sman, R G M

    2013-12-19

    We show that the glass transition of a multitude of mixtures containing hydrogen bonding materials correlates strongly with the effective number of hydroxyl groups per molecule, which are available for intermolecular hydrogen bonding. This correlation is in compliance with the topological constraint theory, wherein the intermolecular hydrogen bonds constrain the mobility of the hydrogen bonded network. The finding that the glass transition relates to hydrogen bonding rather than free volume agrees with our recent finding that there is little difference in free volume among carbohydrates and polysaccharides. For binary and ternary mixtures of sugars, polyols, or biopolymers with water, our correlation states that the glass transition temperature is linear with the inverse of the number of effective hydroxyl groups per molecule. Only for dry biopolymer/sugar or sugar/polyol mixtures do we find deviations due to nonideal mixing, imposed by microheterogeneity.

  19. Hydrogen production from high temperature electrolysis and fusion reactor

    International Nuclear Information System (INIS)

    Dang, V.D.; Steinberg, J.F.; Issacs, H.S.; Lazareth, O.; Powell, J.R.; Salzano, F.J.

    1978-01-01

    Production of hydrogen from high temperature electrolysis of steam coupled with a fusion reactor is studied. The process includes three major components: the fusion reactor, the high temperature electrolyzer and the power conversion cycle each of which is discussed in the paper. Detailed process design and analysis of the system is examined. A parametric study on the effect of process efficiency is presented

  20. Hydrogen production from fusion reactors coupled with high temperature electrolysis

    International Nuclear Information System (INIS)

    Fillo, J.A.; Powell, J.R.; Steinberg, M.

    The decreasing availability of fossil fuels emphasizes the need to develop systems which will produce synthetic fuel to substitute for and complement the natural supply. An important first step in the synthesis of liquid and gaseous fuels is the production of hydrogen. Thermonuclear fusion offers an inexhaustible source of energy for the production of hydrogen from water. Processes which may be considered for this purpose include electrolysis, thermochemical decomposition or thermochemical-electrochemical hybrid cycles. Preliminary studies at Brookhaven indicate that high temperature electrolysis has the highest potential efficiency for production of hydrogen from fusion. Depending on design electric generation efficiencies of approximately 40 to 60 percent and hydrogen production efficiencies of approximately 50 to 70 percent are projected for fusion reactors using high temperature blankets

  1. Anomalously deep penetration of hydrogen into niobium under action of pulse high temperature hydrogen plasma

    International Nuclear Information System (INIS)

    Didyk, A.Yu.

    2011-01-01

    The method of elastic recoil detection (ERD) has been used for the study of storage and redistribution processes of hydrogen atoms under the influence of pulse high temperature hydrogen plasma obtained using the 'Plasma Focus' PF-4 set-up in three high purity niobium foils. It was established that with an increase of number of PF-4 set-up pulses there occur spreading and transfer of implanted hydrogen atoms to large depths in three Nb-foils which are significantly larger than the projected range of hydrogen ions (with the velocity ∼ 10 8 cm/s). The maximum hydrogen concentration up to 60 at. % is reached in the nearest to Ph-4 surface of the third Nb-foil at 20 impulses of the Ph-4 set-up. The observed phenomenon can be described by transfer of implanted hydrogen atoms under the action of powerful shock waves, created by pulse hydrogen plasma and (or) by accelerating hydrogen atom diffusion under the influence of compression straining wave at the front of the shock wave at redistribution of hydrogen atoms at large depths. Similar behavior was discovered and described also in series of nickel, vanadium, niobium and tantalum foils (two or three foils and more in a series) including series of foils from heterogeneous (different) materials, which were studied, too

  2. Hydrogenation and high temperature oxidation of Zirconium claddings

    International Nuclear Information System (INIS)

    Novotny, T.; Perez-Feró, E.; Horváth, M.

    2015-01-01

    In the last few years a new series of experiments started for supporting the new LOCA criteria, considering the proposals of US NRC. The effects which can cause the embrittlement of VVER fuel claddings were reviewed and evaluated in the framework of the project. The purpose of the work was to determine how the fuel cladding’s hydrogen uptake under normal operating conditions, effect the behavior of the cladding under LOCA conditions. As a first step a gas system equipment with gas valves and pressure gauge was built, in which the zirconium alloy can absorb hydrogen under controlled conditions. In this apparatus E110 (produced by electrolytic method, currently used at Paks NPP) and E110G (produced by a new technology) alloys were hydrogenated to predetermined hydrogen contents. According the results of ring compression tests the E110G alloys lose their ductility above 3200 ppm hydrogen content. This limit can be applied to determine the ductile-brittle transition of the nuclear fuel claddings. After the hydrogenation, high temperature oxidation experiments were carried out on the E110G and E110 samples at 1000 °C and 1200 °C. 16 pieces of E110G and 8 samples of E110 with 300 ppm and 600 ppm hydrogen content were tested. The oxidation of the specimens was performed in steam, under isothermal conditions. Based on the ring compression tests load-displacement curves were recorded. The main objective of the compression tests was to determine the ductile-brittle transition. These results were compared to the results of our previous experiments where the samples did not contain hydrogen. The original claddings showed more ductile behavior than the samples with hydrogen content. The higher hydrogen content resulted in a more brittle mechanical behavior. However no significant difference was observed in the oxidation kinetics of the same cladding types with different hydrogen content. The experiments showed that the normal operating hydrogen uptake of the fuel claddings

  3. Improvements in the susceptibility to hydrogen attack and stress-relief cracking of 2 1/4Cr-1Mo steels

    International Nuclear Information System (INIS)

    Imanaka, T.; Sato, S.; Shimomura, J.; Aso, K.

    1985-01-01

    The influence of sulphur content at extremely low level on the susceptibility to hydrogen attack and stress-relief cracking in 2 1/4Cr-1Mo steels was studied. The reduction of sulphur content and/or the addition of REM (rare earth metal) or Ca in accordance with sulphur content remarkably improve the resistivity against hydrogen attack and stress-relief cracking. Micro-structural examination has showed that there exist Mn-REM-S-Al-O complex particles in the REM-added steels. It is concluded that the effect of REM on hydrogen attack and stress-relief cracking is to reduce ''the free sulphur'' in 2 1/4Cr-1Mo steels

  4. High temperature hydrogenation of CaC6

    International Nuclear Information System (INIS)

    Srinivas, G.; Howard, C.A.; Skipper, N.T.; Bennington, S.M.; Ellerby, M.

    2009-01-01

    The structure and superconducting properties of high temperature hydrogenated calcium-graphite intercalation compound, CaC 6 have been investigated using room temperature X-ray diffraction, and temperature and field dependence of magnetisation. It is found that the hydrogenation can only decompose the CaC 6 phase, and generate a mixture of CaH 2 and graphite as the final compound. The hydrogenation of CaC 6 also reveals a degradation of its superconducting properties. The experimental results are discussed in detail and it is found that the formation of stable CaH 2 and deintercalation are the main source for observed phase separation and suppression in superconductivity.

  5. Stability analysis of high temperature superconducting coil in liquid hydrogen

    International Nuclear Information System (INIS)

    Nakayama, T.; Yagai, T.; Tsuda, M.; Hamajima, T.

    2007-01-01

    Recently, it is expected that hydrogen plays an important role in energy source including electric power in near future. Liquid hydrogen has high potential for cooling down superconducting coil wound with high temperature superconductors (HTS), such as BSCCO, YBCO. In this paper, we study stabilities of the coils wound with BSCCO tapes, which are immersed in the liquid hydrogen, and compare stability results with those cooled by liquid helium. We treat a minimum propagation zone (MPZ) theory to evaluate the coil stability considering boiling heat flux of the liquid hydrogen, and specific heat, heat conduction and resistivity of HTS materials as a function of temperature. It is found that the coil cooled by the liquid hydrogen has higher stability margin than that cooled by the liquid helium. We compare the stability margins of both coils wound with Bi-2223/Ag tape and Bi-2212/Ag tape in liquid hydrogen. As a result, it is found that the stability of Bi-2212 coil is equivalent to that of Bi-2223 coil in low and high magnetic field, while the maximum current of Bi-2212 coil exceeds a little bit that of Bi-2223 coil in both magnetic fields

  6. Consequences of metallic fuel-cladding liquid phase attack during over-temperature transient on fuel element lifetime

    International Nuclear Information System (INIS)

    Lahm, C.E.; Koenig, J.F.; Seidel, B.R.

    1990-01-01

    Metallic fuel elements irradiated in EBR-II at temperatures significantly higher than design, causing liquid phase attack of the cladding, were subsequently irradiated at normal operating temperatures to first breach. The fuel element lifetime was compared to that for elements not subjected to the over-temperature transient and found to be equivalent. 1 ref., 3 figs

  7. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    International Nuclear Information System (INIS)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu

    2014-01-01

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H 2 in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between “on” and “off” states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (V Zn  + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, V Zn  + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μ B . The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism

  8. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    Science.gov (United States)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu

    2014-01-01

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H2 in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between "on" and "off" states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (VZn + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, VZn + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μB. The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism.

  9. Hydrogen permeation behavior through F82H at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, S.; Katayama, K.; Shimozori, M.; Fukada, S. [Interdisciplinary Graduate School of Engineering Science, Kyushu University, Kyushu (Japan); Ushida, H. [Energy Science and Engineering, Faculty of Engineering, Kyushu University, Kyushu (Japan); Nishikawa, M. [Malaysia-Japan International Institute of Technology, UTM, Kuala Lumpur (Malaysia)

    2015-03-15

    F82H is a primary candidate of structural material and coolant pipe material in a blanket of a fusion reactor. Understanding tritium permeation behavior through F82H is important. In a normal operation of a fusion reactor, the temperature of F82H will be controlled below 550 C. degrees because it is considered that F82H can be used up to 30,000 hours at 550 C. degrees. However, it is necessary to assume the situation where F82H is heated over 550 C. degrees in a severe accident. In this study, hydrogen permeation behavior through F82H was investigated in the temperature range from 500 to 800 C. degrees. In some cases, water vapor was added in a sample gas to investigate an effect of water vapor on hydrogen permeation. The permeability of hydrogen in the temperature range from 500 to 700 C. degrees agreed well with the permeability reported by E. Serra et al. The degradation of the permeability by water vapor was not observed. After the hydrogen permeation reached in a steady state at 700 C. degrees, the F82H sample was heated to 800 C. degrees. The permeability of hydrogen through F82H sample which was once heated up to 800 C. degrees was lower than that of the original one. (authors)

  10. Study on low temperature plasma driven permeation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Masayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs.

  11. Study on low temperature plasma driven permeation of hydrogen

    International Nuclear Information System (INIS)

    Takizawa, Masayuki

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs

  12. Room temperature Sieving of Hydrogen Isotopes Using 2-D Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hitchcock, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Colon-Mercado, H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Krentz, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Serkiz, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Velten, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Xiao, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-28

    Hydrogen isotope separation is critical to the DOE’s mission in environmental remediation and nuclear nonproliferation. Isotope separation is also a critical technology for the NNSA, and the ability to perform the separations at room temperature with a relatively small amount of power and space would be a major advancement for their respective missions. Recent work has shown that 2-D materials such as graphene and hexagonal boron nitride can act as an isotopic sieve at room temperature; efficiently separating hydrogen isotopes in water with reported separation ratios of 10:1 for hydrogen: deuterium separation for a single pass. The work performed here suggests that this technique has merit, and furthermore, we are investigating optimization and scale up of the required 2-D material based membranes.

  13. Sensitivity to temperature of nuclear energy generation by hydrogen burning

    International Nuclear Information System (INIS)

    Mitalas, R.

    1981-01-01

    The sensitivity to temperature of nuclear energy generation by hydrogen burning is discussed. The complexity of the sensitivity is due to the different equilibration time-scales of the constituents of the p-p chain and CN cycle and the dependence of their abundances and time-scales on temperature. The time-scale of the temperature perturbation, compared to the equilibrium time-scale of a constituent, determines whether the constituent is in equilibrium and affects the sensitivity. The temperature sensitivity of the p-p chain for different values of hydrogen abundance, when different constituents come into equilibrium is presented, as well as its variation with 3 He abundance. The temperature sensitivity is drastically different from n 11 , the temperature sensitivity of the proton-proton reaction, unless the time-scale of temperature perturbation is long enough for 3 He to remain in equilibrium. Even in this case the sensitivity of the p-p chain differs significantly from n 11 , unless the temperature is so low that PP II and PP III chains can be neglected. The variation of the sensitivity of CN energy generation is small for different time-scales of temperature variation, because the temperature sensitivities of individual reactions are so similar. The combined sensitivity to temperature of energy generation by hydrogen burning is presented and shown to have a maximum of 16.4 at T 6 = 24.5. For T 6 > 25 the temperature sensitivity is given by the sensitivity of 14 N + p reaction. (author)

  14. Ovonic Renewable Hydrogen (ORH) - low temperature hydrogen production from renewable fuels

    International Nuclear Information System (INIS)

    Reichman, B.; Mays, W.; Strebe, J.; Fetcenko, M.

    2009-01-01

    'Full text': ECD has developed a new technology to produce hydrogen from various organic matters. In this technology termed Ovonic Renewable Hydrogen (ORH), base material such as NaOH is used as a reactant to facilitate the reforming of the organic matters to hydrogen gas. This Base-Facilitated Reforming (BFR) process is a one-step process and has number of advantages over the conventional steam reforming and gasification processes including lower operation temperature and lower heat consumption. This paper will describe the ORH process and discuss its technological and economics advantages over the conventional hydrogen production processes. ORH process has been studied and demonstrated on variety of renewable fuels including liquid biofuels and solid biomass materials. Results of these studies will be presented. (author)

  15. The effects of incubation period and temperature on the Hydrogen ...

    African Journals Online (AJOL)

    The effects of incubation period and temperature on the Hydrogen sulphide (H 2 S) technique for detection of faecal contamination in water. ... African Journal of Environmental Science and Technology. Journal Home ... A total of 171 water samples from 3 sources were analyzed for the presence of faecal contamination by

  16. High temperature electrolysis for hydrogen production using nuclear energy

    International Nuclear Information System (INIS)

    Herring, J. Stephen; O'brien, James E.; Stoots, Carl M.; Hawkes, Grant L.; Hartvigsen, Joseph J.

    2005-01-01

    High-temperature nuclear reactors have the potential for substantially increasing the efficiency of hydrogen production from water splitting, which can be accomplished via high-temperature electrolysis (HTE) or thermochemical processes. In order to achieve competitive efficiencies, both processes require high-temperature operation (∼850degC). High-temperature electrolytic water splitting supported by nuclear process heat and electricity has the potential to produce hydrogen with overall system efficiencies of 45 to 55%. At the Idaho National Laboratory, we are developing solid-oxide cells to operate in the steam electrolysis mode. The research program includes both experimental and modeling activities. Experimental results were obtained from ten-cell and 22-cell planar electrolysis stacks, fabricated by Ceramatec, Inc. The electrolysis cells are electrolyte-supported, with scandia-stabilized zirconia electrolytes (∼200 μm thick, 64 cm 2 active area), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions, gas glow rates, and current densities. Hydrogen production rates greater than 100 normal liters per hour for 196 hours have been demonstrated. In order to evaluate the performance of large-scale HTE operations, we have developed single-cell models, based on FLUENT, and a process model, using the systems-analysis code HYSYS. (author)

  17. Low temperature heat capacity of lutetium and lutetium hydrogen alloys

    International Nuclear Information System (INIS)

    Thome, D.K.

    1977-10-01

    The heat capacity of high purity electrotransport refined lutetium was measured between 1 and 20 0 K. Results for theta/sub D/ were in excellent agreement with theta values determined from elastic constant measurements. The heat capacity of a series of lutetium-hydrogen solid solution alloys was determined and results showed an increase in γ from 8.2 to about 11.3 mJ/g-atom-K 2 for hydrogen content increasing from zero to about one atomic percent. Above one percent hydrogen γ decreased with increasing hydrogen contents. The C/T data showed an increase with temperature decreasing below about 2.5 0 K for samples with 0.1 to 1.5 atomic percent hydrogen. This accounts for a large amount of scatter in theta/sub D/ versus hydrogen content in this range. The heat capacity of a bulk sample of lutetium dihydride was measured between 1 and 20 0 K and showed a large increase in theta/sub D/ and a large decrease in γ compared to pure lutetium

  18. Study on hydrogen production by high temperature electrolysis of steam

    International Nuclear Information System (INIS)

    Hino, Ryutaro; Aita, Hideki; Sekita, Kenji; Haga, Katsuhiro; Iwata, Tomo-o.

    1997-09-01

    In JAERI, design and R and D works on hydrogen production process have been conducted for connecting to the HTTR under construction at the Oarai Research Establishment of JAERI as a nuclear heat utilization system. As for a hydrogen production process by high-temperature electrolysis of steam, laboratory-scale experiments were carried out with a practical electrolysis tube with 12 cells connected in series. Hydrogen was produced at a maximum density of 44 Nml/cm 2 h at 950degC, and know-how of operational procedures and operational experience were also accumulated. Thereafter, a planar electrolysis cell supported by a metallic plate was fabricated in order to improve hydrogen production performance and durability against thermal cycles. In the preliminary test with the planar cell, hydrogen has been produced continuously at a maximum density of 33.6 Nml/cm 2 h at an electrolysis temperature of 950degC. This report presents typical test results mentioned above, a review of previous studies conducted in the world and R and D items required for connecting to the HTTR. (author)

  19. Influence of the Ambient Temperature, to the Hydrogen Fuel Cell Functioning

    Directory of Open Access Journals (Sweden)

    POPOVICI Ovidiu

    2012-10-01

    Full Text Available The reversible fuel cell can be used to produce hydrogen. The hydrogen is further the chemical energy source to produce electrical energy using the fuel cell. The ambient temperature will influence theparameters of the hydrogen fuel cell.

  20. Influence of the Ambient Temperature, to the Hydrogen Fuel Cell Functioning

    OpenAIRE

    POPOVICI Ovidiu; HOBLE Dorel Anton

    2012-01-01

    The reversible fuel cell can be used to produce hydrogen. The hydrogen is further the chemical energy source to produce electrical energy using the fuel cell. The ambient temperature will influence theparameters of the hydrogen fuel cell.

  1. Low temperature catalytic reforming of heptane to hydrogen and syngas

    Directory of Open Access Journals (Sweden)

    M.E.E. Abashar

    2016-09-01

    Full Text Available The production of hydrogen and syngas from heptane at a low temperature is studied in a circulating fast fluidized bed membrane reactor (CFFBMR. A thin film of palladium-based membrane is employed to the displacement of the thermodynamic equilibrium for high conversion and yield. A mathematical model is developed to simulate the reformer. A substantial improvement of the CFFBMR is achieved by implementing the thin hydrogen membrane. The results showed that almost complete conversion of heptane and 46.25% increase of exit hydrogen yield over the value without membrane are achieved. Also a wide range of the H2/CO ratio within the recommended industrial range is obtained. The phenomena of high spikes of maximum nature at the beginning of the CFFBMR are observed and explanation offered. The sensitivity analysis results have shown that the increase of the steam to carbon feed ratio can increase the exit hydrogen yield up to 108.29%. It was found that the increase of reaction side pressure at a high steam to carbon feed ratio can increase further the exit hydrogen yield by 49.36% at a shorter reactor length. Moreover, the increase of reaction side pressure has an important impact in a significant decrease of the carbon dioxide and this is a positive sign for clean environment.

  2. Chemical equilibria relating the isotopic hydrogens at low temperatures

    International Nuclear Information System (INIS)

    Pyper, J.W.; Souers, P.C.

    1976-01-01

    Hydrogen fusion will require a fuel mixture of liquefied or frozen D 2 and T 2 . The composition of this fuel mixture is described by the equilibrium constant K/sub DT/. The theory of isotopic exchange reactions is discussed as applied to the hydrogen isotopes. A literature survey of the values of K/sub HD/, K/sub HT/, and K/sub DT/ found no values of K/sub DT/ for temperatures below 25 0 K and no values of K/sub HD/ and K/sub HT/ for temperatures below 50 0 K. The existing data are critically evaluated, and simplified formulas for the three equilibrium constants in the temperature range 50 to 300 0 K are derived from them. Harmonic approximation theory with rotational correction was used to calculate values of K/sub HD/, K/sub HT/, and K/sub DT/ in the temperature range 4.2 to 50 0 K. It is found that K/sub DT/ = 2.995 exp(-10.82/T) in the temperature range 16.7 to 33.3 0 K to an accuracy of 1%. Tables, graphs, and equations of K/sub HD/, K/sub HT/, and K/sub DT/ are given for the temperature range 4.2 to 50 0 K. 27 references, 14 tables, 8 figures

  3. High-temperature study of superconducting hydrogen and deuterium sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Durajski, A.P. [Institute of Physics, Czestochowa University of Technology, Ave. Armii Krajowej 19, 42-200 Czestochowa (Poland); Szczesniak, R. [Institute of Physics, Czestochowa University of Technology, Ave. Armii Krajowej 19, 42-200 Czestochowa (Poland); Institute of Physics, Jan Dlugosz University, Ave. Armii Krajowej 13/15, 42-200 Czestochowa (Poland); Pietronero, L. [Sapienza, Universita di Roma, Dip. Fisica, P. le A. Moro 2, 00185 Roma (Italy); Institute of Complex Systems, CNR, Via dei Taurini 19 Roma (Italy); London Institute for Mathematical Sciences, South Street 22, Mayfair London (United Kingdom)

    2016-05-15

    Hydrogen-rich compounds are extensively explored as candidates for a high-temperature superconductors. Currently, the measured critical temperature of 203 K in hydrogen sulfide (H{sub 3}S) is among the highest over all-known superconductors. In present paper, using the strong-coupling Eliashberg theory of superconductivity, we compared in detail the thermodynamic properties of two samples containing different hydrogen isotopes H{sub 3}S and D{sub 3}S at 150 GPa. Our research indicates that it is possible to reproduce the measured values of critical temperature 203 K and 147 K for H{sub 3}S and D{sub 3}S by using a Coulomb pseudopotential of 0.123 and 0.131, respectively. However, we also discuss a scenario in which the isotope effect is independent of pressure and the Coulomb pseudopotential for D{sub 3}S is smaller than for H{sub 3}S. For both scenarios, the energy gap, specific heat, thermodynamic critical field and related dimensionless ratios are calculated and compared with other conventional superconductors. We shown that the existence of the strong-coupling and retardation effects in the systems analysed result in significant differences between values obtained within the framework of the Eliashberg formalism and the prediction of the Bardeen-Cooper-Schrieffer theory. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Hydrogen desorption from mechanically milled carbon micro coils hydrogenated at high temperature

    International Nuclear Information System (INIS)

    Yoshio Furuya; Shuichi Izumi; Seiji Motojima; Yukio Hishikawa

    2005-01-01

    Carbon micro coils (CMC) have been prepared by the catalytic pyrolysis of acetylene at 750-800 C. The as grown coils have an almost amorphous structure and contain about 1 mass% hydrogen. They have 0.1 - 10 mm coil length, 1-5 μm coil diameter, 0.1-0.5 μm coil pitch and about 100 m 2 /g specific surface area. They were graphitized, as maintaining the morphology of the coils, by heat-treating at a higher temperature than 2500 C in Ar atmosphere. The layer space (d) of graphitized CMC was determined to be 0.341 nm, forming a 'herringbone' structure with an inclination of 10-40 degree versus the coiled fiber axis, having a specific surface area of about 8 m 2 /g. The hydrogen absorption behaviors of CMC were investigated from RT to 1200 C by a thermal desorption spectrometry (TDS) using a quadrupole mass analyzer. In TDS measurements, pre-existing hydrogen, which was due to the residual acetylene incorporated into CMC on its growing, desorbed from 700 C and peaked at about 900 C. The increment in the main peak of desorbed hydrogen in the as-grown CMC heat-treated at 500 C for 1 h under high pressure of hydrogen gas (1.9 or 8.9 MPa) was not remarkable as is shown in Fig.1. While, in the CMC samples milled mechanically for 1 h at RT using a planetary ball mill, the increase of desorbed hydrogen became to be great with the hydrogen pressure (up to 8.9 MPa) on heat-treating at 500 C, as is shown in Fig.2. In these CMC samples, the building up temperature of the hydrogen desorption was shifted to a lower one and the temperature range of desorption became to be wider than those in the as-grown CMC because of the appearance of another desorption peak at about 600 C in addition to the peak ranging from 850 C to 900 C. The same kind of peak was also slightly observed in as-grown CMC (Fig.1). It is clear that this desorption at about 600 C has contributed to the remarkable increase of desorbed hydrogen in the milled CMC. In this work, values of more than 2 mass% were obtained

  5. Hydrogen diffusion at moderate temperatures in p-type Czochralski silicon

    International Nuclear Information System (INIS)

    Huang, Y.L.; Ma, Y.; Job, R.; Ulyashin, A.G.

    2004-01-01

    In plasma-hydrogenated p-type Czochralski silicon, rapid thermal donor (TD) formation is achieved, resulting from the catalytic support of hydrogen. The n-type counter doping by TD leads to a p-n junction formation. A simple method for the indirect determination of the diffusivity of hydrogen via applying the spreading resistance probe measurements is presented. Hydrogen diffusion in silicon during both plasma hydrogenation and post-hydrogenation annealing is investigated. The impact of the hydrogenation duration, annealing temperature, and resistivity of the silicon wafers on the hydrogen diffusion is discussed. Diffusivities of hydrogen are determined in the temperature range 270-450 deg. C. The activation energy for the hydrogen diffusion is deduced to be 1.23 eV. The diffusion of hydrogen is interpreted within the framework of a trap-limited diffusion mechanism. Oxygen and hydrogen are found to be the main traps

  6. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    Science.gov (United States)

    Nicovich, J. M.; Wine, P. H.

    1988-01-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  7. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu, E-mail: ycwu@whu.edu.cn [School of Physics and Technology, Hubei Nuclear Solid Physics Key Laboratory, Wuhan University, Wuhan 430072 (China)

    2014-01-21

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H{sub 2} in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between “on” and “off” states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (V{sub Zn} + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, V{sub Zn} + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μ{sub B}. The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism.

  8. HIGH-TEMPERATURE ELECTROLYSIS FOR HYDROGEN PRODUCTION FROM NUCLEAR ENERGY

    Energy Technology Data Exchange (ETDEWEB)

    James E. O& #39; Brien; Carl M. Stoots; J. Stephen Herring; Joseph J. Hartvigsen

    2005-10-01

    An experimental study is under way to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800 to 900ºC. Results presented in this paper were obtained from a ten-cell planar electrolysis stack, with an active area of 64 cm2 per cell. The electrolysis cells are electrolyte-supported, with scandia-stabilized zirconia electrolytes (~140 µm thick), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions (0.1 - 0.6), gas flow rates (1000 - 4000 sccm), and current densities (0 to 0.38 A/cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. Cell operating potentials and cell current were varied using a programmable power supply. Hydrogen production rates up to 90 Normal liters per hour were demonstrated. Values of area-specific resistance and stack internal temperatures are presented as a function of current density. Stack performance is shown to be dependent on inlet steam flow rate.

  9. Magnetic resonance studies of atomic hydrogen gas at low temperatures

    International Nuclear Information System (INIS)

    Hardy, W.N.; Morrow, M.; Jochemsen, R.; Statt, B.W.; Kubik, P.R.; Marsolais, R.M.; Berlinsky, A.J.; Landesman, A.

    1980-01-01

    Using a pulsed low temperature discharge in a closed cell containing H 2 and 4 He, we have been able to store a low density (approximately 10 12 atoms/cc) gas of atomic hydrogen for periods of order one hour in zero magnetic field and T=1 K. Pulsed magnetic resonance at the 1420 MHz hyperfine transition has been used to study a number of the properties of the gas, including the recombination rate H + H + 4 He→H 2 + 4 He, the hydrogen spin-exchange relaxation rates, the diffusion coefficient of H in 4 He gas and the pressure shift of the hyperfine frequency due to the 4 He buffer gas. Here we discuss the application of hyperfine frequency shifts as a probe of the H-He potential, and as a means for determining the binding energy of H on liquid helium

  10. The effect of climate variability on urinary stone attacks: increased incidence associated with temperature over 18 °C: a population-based study.

    Science.gov (United States)

    Park, Hyoung Keun; Bae, Sang Rak; Kim, Satbyul E; Choi, Woo Suk; Paick, Sung Hyun; Ho, Kim; Kim, Hyeong Gon; Lho, Yong Soo

    2015-02-01

    The aim of this study was to evaluate the effect of seasonal variation and climate parameters on urinary tract stone attack and investigate whether stone attack is increased sharply at a specific point. Nationwide data of total urinary tract stone attack numbers per month between January 2006 and December 2010 were obtained from the Korean Health Insurance Review and Assessment Service. The effects of climatic factors on monthly urinary stone attack were assessed using auto-regressive integrated moving average (ARIMA) regression method. A total of 1,702,913 stone attack cases were identified. Mean monthly and monthly average daily urinary stone attack cases were 28,382 ± 2,760 and 933 ± 85, respectively. The stone attack showed seasonal trends of sharp incline in June, a peak plateau from July to September, and a sharp decline after September. The correlation analysis showed that ambient temperature (r = 0.557, p r = 0.513, p stone attack cases. However, after adjustment for trends and seasonality, ambient temperature was the only climate factor associated with the stone attack cases in ARIMA regression test (p = 0.04). Threshold temperature was estimated as 18.4 °C. Risk of urinary stone attack significantly increases 1.71% (1.02-2.41 %, 95% confidence intervals) with a 1 °C increase of ambient temperature above the threshold point. In conclusion, monthly urinary stone attack cases were changed according to seasonal variation. Among the climates variables, only temperature had consistent association with stone attack and when the temperature is over 18.4 °C, urinary stone attack would be increased sharply.

  11. Plasma Temperature Determination of Hydrogen Containing High-Frequency Electrodeless Lamps by Intensity Distribution Measurements of Hydrogen Molecular Band

    OpenAIRE

    Gavare, Zanda; Revalde, Gita; Skudra, Atis

    2010-01-01

    The goal of the present work was the investigation of the possibility to use intensity distribution of the Q-branch lines of the hydrogen Fulcher-α diagonal band (d3Πu−→a3∑g+ electronic transition; Q-branch with v=v′=2) to determine the temperature of hydrogen containing high-frequency electrodeless lamps (HFEDLs). The values of the rotational temperatures have been obtained from the relative intensity distributions for hydrogen-helium and hydrogen-argon HFEDLs depending on the applied curren...

  12. High temperature fast reactor for hydrogen production in Brazil

    International Nuclear Information System (INIS)

    Nascimento, Jamil A. do; Ono, Shizuca; Guimaraes, Lamartine N.F.

    2008-01-01

    The main nuclear reactors technology for the Generation IV, on development phase for utilization after 2030, is the fast reactor type with high temperature output to improve the efficiency of the thermo-electric conversion process and to enable applications of the generated heat in industrial process. Currently, water electrolysis and thermo chemical cycles using very high temperature are studied for large scale and long-term hydrogen production, in the future. With the possible oil scarcity and price rise, and the global warming, this application can play an important role in the changes of the world energy matrix. In this context, it is proposed a fast reactor with very high output temperature, ∼ 1000 deg C. This reactor will have a closed fuel cycle; it will be cooled by lead and loaded with nitride fuel. This reactor may be used for hydrogen, heat and electricity production in Brazil. It is discussed a development strategy of the necessary technologies and some important problems are commented. The proposed concept presents characteristics that meet the requirements of the Generation IV reactor class. (author)

  13. The probability of heterogeneous recombination of hydrogen atoms in low-temperature hydrogen plasma

    International Nuclear Information System (INIS)

    Islyaikin, A.; Rybkin, V.; Svetsov, V.

    2000-01-01

    In the group of the optical methods, the investigations of the process of recombination of the hydrogen atoms were studied mainly by the jet procedure, based on the measurement of the dependence of the intensity of radiation of the discharge on the speed of flow of particles which makes it possible to obtain information on the processes of annihilation of active particles on the surface of the discharge device both in the zone of plasma at outside to the zone (in the post glow region). However, to realise this method, it is necessary to use higher linear speed of the flow of the particles and this creates additional technical difficulties. A similar disadvantage is not found in the calculation methods of technical application with special reference to the examination of the processes of heterogeneous recombination of the atoms in the low-temperature hydrogen plasma is the main task of this work

  14. Neutron temperature measurements in a cryogenic hydrogenous moderator

    International Nuclear Information System (INIS)

    Ball, R.M.; Hoovler, G.S.; Lewis, R.H.

    1995-01-01

    Benchmarkings of neutronic calculations are most successful when there is a direct correlation between a measurement and an analytic result. In the thermal neutron energy region, the fluence rate as a function of moderator temperature and position within the moderator is an area of potential correlation. The measurement can be done by activating natural lutetium. The two isotopes of the element lutetium have widely different cross sections and permit the discrimination of flux shape and energy distributions at different reactor conditions. The 175 Lu has a 1/v dependence in the thermal energy region, and 176 Lu has a resonance structure that approximates a constant cross section in the same region. The saturation activation of the two isotopes has been measured in an insulated moderator container at the center of a thermal heterogeneous reactor designed for space nuclear propulsion. The measurements were made in a hydrogenous (polyethylene) moderator at three temperatures (83, 184, and 297 K) and five locations within the moderator. Simultaneously, the reactivity effect of the change in the moderator temperature was determined to be positive with an increase in temperature. The plot of activation shows the variation in neutron fluence rate and current with temperature and explains the positive reactivity coefficient. A neutron temperature can be inferred from a postulated Maxwell-Boltzmann distribution and compared with Monte Carlo or other calculations

  15. Low temperature isotope effects of hydrogen diffusion in metallic glasses

    International Nuclear Information System (INIS)

    Hofmann, A.; Kronmueller, H.

    1989-01-01

    Snoek-like relaxation peaks of Hydrogen and Deuterium in amorphous Fe 80 B 20 , Fe 40 Ni 40 P 14 B 6 and Fe 91 Zr 9 are detected. At low H, D concentrations the peaks are near 200 K and show small isotope effects of the average activation energies (anti Q H ≅ 0.6 eV, anti Q D - anti Q H ≤ 10 meV). For higher H, D-contents the peaks shift to lower temperatures around to 120 K and show distinct isotope effects in the activation energies (anti Q H ≅ 0.3 eV, anti Q D - anti Q H ≅ 30 meV) and in the amplitude of the low temperature tails of the relaxation peaks. This points to isotope mass dependent deviations from the Arrhenius law due to nonthermal tunneling processes. (orig.)

  16. Low temperature hydrogen embrittlement of niobium. II. Microscopic observations

    International Nuclear Information System (INIS)

    Grossbeck, M.L.; Birnbaum, H.K.

    1977-01-01

    The detailed, microscopic processes which occur during the hydrogen embrittlement of pure Nb are examined using in situ SEM crack propagation studies, SEM fractography, electron diffraction and ion probe methods. These results show that the fracture process occurs in a stress induced NbH hydride phase which forms in front of the propagating crack. The experimental results are in good agreement with the stress induced hydride embrittlement mechanism which is discussed. The thermodynamics of precipitation of hydrides under external stress is discussed and calculations are presented for the stress effects on the α-β solvus temperatures. These are related to the embrittlement process and evidence is presented to support the calculated stress effects on the solvus temperature

  17. Plasma Temperature Determination of Hydrogen Containing High-Frequency Electrode less Lamps by Intensity Distribution Measurements of Hydrogen Molecular Band

    International Nuclear Information System (INIS)

    Gavare, Z.; Revalde, G.; Skudra, A.

    2011-01-01

    The goal of the present work was the investigation of the possibility to use intensity distribution of the Q-branch lines of the hydrogen Fulcher-a diagonal band (d3η u- a3Σg + electronic transition; Q-branch with ν=ν=2) to determine the temperature of hydrogen containing high-frequency electrode less lamps (HFEDLs). The values of the rotational temperatures have been obtained from the relative intensity distributions for hydrogen-helium and hydrogen-argon HFEDLs depending on the applied current. The results have been compared with the method of temperature derivation from Doppler profiles of He 667.8 nm and Ar 772.4 nm lines. The results of both methods are in good agreement, showing that the method of gas temperature determination from the intensity distribution in the hydrogen Fulcher-a (2-2)Q band can be used for the hydrogen containing HFEDLs. It was observed that the admixture of 10% hydrogen in the argon HFEDLs significantly reduces the gas temperature

  18. Attack of carbonic anhydride and hydrogen sulfide on API class H cement slurries exposed to saline formation waters

    Directory of Open Access Journals (Sweden)

    Márquez, G.

    2011-09-01

    Full Text Available This paper discusses the attack of the major ions (sulfate, chloride, and magnesium and sour gases, present in natural gas (CO2 y SH2, on API class H cement, the type used in gas wells under high pressure and temperature. The effects of these chemical agents on this cement was simulated to study the physicochemical changes due to the action of sour gases and formation water. Cement specimens were immersed in neutral solutions containing fixed concentrations of the major ions inside Parr reactors. These solutions were analysed and XRD analyses were conducted for over two months to identify mineralogical variations from 14 to 60 days. The objective of this research was to determine the effects of the joint attack of major ions and sour gases on cement pastes. The main effects of both gases, jointly or separately, on cement durability were, respectively, the carbonation process and the leaching of some components.

    Se simuló la acción agresiva de los denominados iones fundamentales (sulfato, cloruro y magnesio y los gases agrios presentes en el gas natural (CO2 y H2S sobre un cemento API clase H utilizado en pozos gasíferos a presión y temperatura elevadas, al objeto de observar sus alteraciones fisicoquímicas por la acción combinada de tales gases y las aguas de formación. Se prepararon varias probetas del material cementante para su inmersión en disoluciones neutras, conteniendo los iones fundamentales en concentraciones fijas, dentro de reactores tipo Parr. Se analizaron durante más de dos meses una serie de disoluciones en contacto con el cemento utilizado; así como, mediante DRX, la evolución de la mineralogía de dicho material entre los 14 y los 60 días. Los principales efectos de ambos gases, en conjunto o por separado, sobre la durabilidad del cemento fueron, respectivamente, la formación de carbonato cálcico y la lixiviación de algunos componentes.

  19. Spectroscopic study of low-temperature hydrogen absorption in palladium

    Energy Technology Data Exchange (ETDEWEB)

    Ienaga, K., E-mail: ienaga@issp.u-tokyo.ac.jp; Takata, H.; Onishi, Y.; Inagaki, Y.; Kawae, T. [Department of Applied Quantum Physics, Faculty of Engineering, Kyushu University, Motooka, Nishi-Ku, Fukuoka 819-0395 (Japan); Tsujii, H. [Department of Physics, Faculty of Education, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Kimura, T. [Department of Physics, Kyushu University, Hakozaki, Higashi-Ku, Fukuoka 812-8581 (Japan)

    2015-01-12

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H{sub 2} using inelastic electron spectroscopy (IES). After introduction of liquid H{sub 2}, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ∼ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  20. Hydrogen Temperature-Programmed Desorption (H2 TPD) of Supported Platinum Catalysts.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Miller, J.T.; Meyers, B.L.; Modica, F.S.; Lane, G.S.; Vaarkamp, M.

    1993-01-01

    Hydrogen temperature-programmed desorption (TPD) of supported platinum catalysts, Pt/KLTL, Pt/H-LTL, Pt/K-MAZ, Pt/H-MAZ, Pt/-Al2O3, and Pt/SiO2, was performed after hydrogen reduction at 300, 450, or 650°C. For all catalysts, reversible desorption of chemisorbed hydrogen occurred at approximately

  1. High-temperature nuclear reactor power plant cycle for hydrogen and electricity production – numerical analysis

    Directory of Open Access Journals (Sweden)

    Dudek Michał

    2016-01-01

    Full Text Available High temperature gas-cooled nuclear reactor (called HTR or HTGR for both electricity generation and hydrogen production is analysed. The HTR reactor because of the relatively high temperature of coolant could be combined with a steam or gas turbine, as well as with the system for heat delivery for high-temperature hydrogen production. However, the current development of HTR’s allows us to consider achievable working temperature up to 750°C. Due to this fact, industrial-scale hydrogen production using copper-chlorine (Cu-Cl thermochemical cycle is considered and compared with high-temperature electrolysis. Presented calculations show and confirm the potential of HTR’s as a future solution for hydrogen production without CO2 emission. Furthermore, integration of a hightemperature nuclear reactor with a combined cycle for electricity and hydrogen production may reach very high efficiency and could possibly lead to a significant decrease of hydrogen production costs.

  2. Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

    Directory of Open Access Journals (Sweden)

    Sangchoel Kim

    2013-10-01

    Full Text Available We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5 layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

  3. The Potential for Low-Temperature Abiotic Hydrogen Generation and a Hydrogen-Driven Deep Biosphere

    Science.gov (United States)

    Huang, Shanshan; Thorseth, Ingunn H.

    2011-01-01

    Abstract The release and oxidation of ferrous iron during aqueous alteration of the mineral olivine is known to reduce aqueous solutions to such extent that molecular hydrogen, H2, forms. H2 is an efficient energy carrier and is considered basal to the deep subsurface biosphere. Knowledge of the potential for H2 generation is therefore vital to understanding the deep biosphere on Earth and on extraterrestrial bodies. Here, we provide a review of factors that may reduce the potential for H2 generation with a focus on systems in the core temperature region for thermophilic to hyperthermophilic microbial life. We show that aqueous sulfate may inhibit the formation of H2, whereas redox-sensitive compounds of carbon and nitrogen are unlikely to have significant effect at low temperatures. In addition, we suggest that the rate of H2 generation is proportional to the dissolution rate of olivine and, hence, limited by factors such as reactive surface areas and the access of water to fresh surfaces. We furthermore suggest that the availability of water and pore/fracture space are the most important factors that limit the generation of H2. Our study implies that, because of large heat flows, abundant olivine-bearing rocks, large thermodynamic gradients, and reduced atmospheres, young Earth and Mars probably offered abundant systems where microbial life could possibly have emerged. Key Words: Serpentinization—Olivine—Hydrogen—Deep biosphere—Water—Mars. Astrobiology 11, 711–724. PMID:21923409

  4. Effect of the annealing temperature for the hydrogen Q-degradation on superconducting cavities

    International Nuclear Information System (INIS)

    Ota, Tomoko; Sukenobu, Satoru; Tanabe, Yoshio; Onishi, Yoshimichi; Noguchi, Shuichi; Ono, Masaaki; Saito, Kenji; Shishido, Toshio; Yamazaki, Yoshishige

    1997-01-01

    Hydrogen Q-degradation was studied in niobium superconducting cavities prepared by barrel polishing, and electropolishing without annealing, though a fast cooling down of cavities. Cavity performance with various annealing temperature were tested using a 1.3GHz single-cell cavity to compare the effects of annealing temperature for hydrogen Q-degradation. (author)

  5. Hydrogen assisted catalytic biomass pyrolysis. Effect of temperature and pressure

    DEFF Research Database (Denmark)

    Stummann, M.Z.; Høj, M.; Schandel, C. B.

    2018-01-01

    fraction of 17 and 22% daf, corresponding to an energy recovery of between 40 and 53% in the organic product. The yield of the non-condensable gases varied between a mass fraction of 24 and 32% daf and the char yield varied between 9.6 and 18% daf. The condensed organics contained a mass fraction of 42....... The effect of varying the temperature (365–511 °C) and hydrogen pressure (1.6–3.6 MPa) on the product yield and organic composition was studied. The mass balance closed by a mass fraction between 90 and 101% dry ash free basis (daf). The yield of the combined condensed organics and C4+ varied between a mass......–75% aromatics, based on GC × GC-FID chromatographic peak area, and the remainder was primarily naphthenes with minor amounts of paraffins. The condensed organics were essentially oxygen free (mass fraction below 0.001%) when both reactors were used. Bypassing the HDO reactor increased the oxygen concentration...

  6. Detonation cell size measurements and predictions in hydrogen-air-steam mixtures at elevated temperatures

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsberg, T.; Boccio, J.; Economos, C.

    1994-01-01

    The present research reports on the effect of initial mixture temperature on the experimentally measured detonation cell size for hydrogen-air-steam mixtures. Experimental and theoretical research related to combustion phenomena in hydrogen-air-steam mixtures has been ongoing for many years. However, detonation cell size data currently exists or hydrogen-air-steam mixtures up to a temperature of only 400K. Sever accident scenarios have been identified for light water reactors (LWRs) where hydrogen-air mixture temperatures in excess of 400K could be generated within containment. The experiments in this report focus on extending the cell size data base for initial mixture temperatures in excess of 400K. The experiments were carried out in a 10-cm inner-diameter, 6.1-m long heated detonation tube with a maximum operating temperature of 700K and spatial temperature uniformity of ±14K. Detonation cell size measurements provide clear evidence that the effect of hydrogen-air initial gas mixture temperature, in the range 300K--650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The hydrogen-air detonability limits for the 10-cm inside-diameter test vessel, based upon the onset of single-head spin, decreased from 15 percent by hydrogen at 300K down to about 9 percent hydrogen at 650K. The one-dimensional ZND model does a very good job at predicting the overall trends in the cell size data over the range of hydrogen-air-steam mixture compositions and temperature studied in the experiments

  7. LARGE-SCALE HYDROGEN PRODUCTION FROM NUCLEAR ENERGY USING HIGH TEMPERATURE ELECTROLYSIS

    International Nuclear Information System (INIS)

    O'Brien, James E.

    2010-01-01

    Hydrogen can be produced from water splitting with relatively high efficiency using high-temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high-temperature process heat. When coupled to an advanced high temperature nuclear reactor, the overall thermal-to-hydrogen efficiency for high-temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. Demand for hydrogen is increasing rapidly for refining of increasingly low-grade petroleum resources, such as the Athabasca oil sands and for ammonia-based fertilizer production. Large quantities of hydrogen are also required for carbon-efficient conversion of biomass to liquid fuels. With supplemental nuclear hydrogen, almost all of the carbon in the biomass can be converted to liquid fuels in a nearly carbon-neutral fashion. Ultimately, hydrogen may be employed as a direct transportation fuel in a 'hydrogen economy.' The large quantity of hydrogen that would be required for this concept should be produced without consuming fossil fuels or emitting greenhouse gases. An overview of the high-temperature electrolysis technology will be presented, including basic theory, modeling, and experimental activities. Modeling activities include both computational fluid dynamics and large-scale systems analysis. We have also demonstrated high-temperature electrolysis in our laboratory at the 15 kW scale, achieving a hydrogen production rate in excess of 5500 L/hr.

  8. Medium temperature reaction between lanthanide and actinide carbides and hydrogen

    International Nuclear Information System (INIS)

    Dean, G.; Lorenzelli, R.; Pascard, R.

    1964-01-01

    Hydrogen is fixed reversibly by the lanthanide and actinide mono carbides in the range 25 - 400 C, as for pure corresponding metals. Hydrogen goes into the carbides lattice through carbon vacancies and the total fixed amount is approximately equal to two hydrogen atoms per initial vacancy. Final products c.n thus be considered as carbo-hydrides of general formula M(C 1-x , H 2x ). The primitive CFC, NaCl type, structure remains unchanged but expands strongly in the case of actinide carbides. With lanthanide carbides, hydrogenation induces a phase transformation with reappearance of the metal structure (HCP). Hydrogen decomposition pressures of all the studied carbo-hydrides are greater than those of the corresponding di-hydrides. (authors) [fr

  9. Hydrogen-induced room-temperature plasticity in TC4 and TC21 alloys

    DEFF Research Database (Denmark)

    Yuan, Baoguo; Jin, Yongyue; Hong, Chuanshi

    2017-01-01

    In order to reveal the effect of hydrogen on the room-temperature plasticity of the titanium alloys TC4 and TC21, compression tests have been carried out at room temperature. Results show that an appropriate amount of hydrogen can improve the room-temperature plasticity of both the TC4 and TC21...... alloys. The ultimate compression strain of the TC4 alloy containing a hydrogen concentration of 0.5 wt.% increases by 39% compared to the untreated material. For the TC21 alloy the ultimate compression strain is increased by 33% at a hydrogen concentration of 0.6 wt.%. The main reason for the improvement...... of hydrogen-induced room-temperature plasticity of the TC4 and TC21 alloys is discussed....

  10. Effect of hydrogen on the integrity of aluminium–oxide interface at elevated temperatures

    KAUST Repository

    Li, Meng; Xie, De-Gang; Ma, Evan; Li, Ju; Zhang, Xixiang; Shan, Zhi-Wei

    2017-01-01

    Hydrogen can facilitate the detachment of protective oxide layer off metals and alloys. The degradation is usually exacerbated at elevated temperatures in many industrial applications; however, its origin remains poorly understood. Here by heating hydrogenated aluminium inside an environmental transmission electron microscope, we show that hydrogen exposure of just a few minutes can greatly degrade the high temperature integrity of metal–oxide interface. Moreover, there exists a critical temperature of ∼150 °C, above which the growth of cavities at the metal–oxide interface reverses to shrinkage, followed by the formation of a few giant cavities. Vacancy supersaturation, activation of a long-range diffusion pathway along the detached interface and the dissociation of hydrogen-vacancy complexes are critical factors affecting this behaviour. These results enrich the understanding of hydrogen-induced interfacial failure at elevated temperatures.

  11. Effect of hydrogen on the integrity of aluminium–oxide interface at elevated temperatures

    KAUST Repository

    Li, Meng

    2017-02-20

    Hydrogen can facilitate the detachment of protective oxide layer off metals and alloys. The degradation is usually exacerbated at elevated temperatures in many industrial applications; however, its origin remains poorly understood. Here by heating hydrogenated aluminium inside an environmental transmission electron microscope, we show that hydrogen exposure of just a few minutes can greatly degrade the high temperature integrity of metal–oxide interface. Moreover, there exists a critical temperature of ∼150 °C, above which the growth of cavities at the metal–oxide interface reverses to shrinkage, followed by the formation of a few giant cavities. Vacancy supersaturation, activation of a long-range diffusion pathway along the detached interface and the dissociation of hydrogen-vacancy complexes are critical factors affecting this behaviour. These results enrich the understanding of hydrogen-induced interfacial failure at elevated temperatures.

  12. An experimental investigation of the rate of hydrogen absorption in zirconium-2.5 wt percent niobium from steam/hydrogen mixtures at elevated temperatures

    International Nuclear Information System (INIS)

    Langman, V.J.

    1984-08-01

    The test specifications for an experimental program to study the rate of hydrogen absorption in zirconium-2.5 weight percent niobium pressure tube material from steam/hydrogen mixtures at elevated temperatures are discussed

  13. Effect of trapping and temperature on the hydrogen embrittlement susceptibility of alloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Galliano, Florian; Andrieu, Eric; Blanc, Christine; Cloue, Jean-Marc; Connetable, Damien; Odemer, Gregory, E-mail: gregory.odemer@ensiacet.fr

    2014-08-12

    Ni-based alloy 718 is widely used to manufacture structural components in the aeronautic and nuclear industries. Numerous studies have shown that alloy 718 may be sensitive to hydrogen embrittlement. In the present study, the susceptibilities of three distinct metallurgical states of alloy 718 to hydrogen embrittlement were investigated to identify both the effect of hydrogen trapping on hydrogen embrittlement and the role of temperature in the hydrogen-trapping mechanism. Cathodic charging in a molten salt bath was used to saturate the different hydrogen traps of each metallurgical state. Tensile tests at different temperatures and different strain rates were carried out to study the effect of hydrogen on mechanical properties and failure modes, in combination with hydrogen content measurements. The results demonstrated that Ni-based superalloy 718 was strongly susceptible to hydrogen embrittlement between 25 °C and 300 °C, and highlighted the dominant roles played by the hydrogen solubility and the hydrogen trapping on mechanical behavior and fracture modes.

  14. High temperature cathodic charging of hydrogen in zirconium alloys and iron and nickel base alloys

    International Nuclear Information System (INIS)

    John, J.T.; De, P.K.; Gadiyar, H.S.

    1990-01-01

    These investigations lead to the development of a new technique for charging hydrogen into metals and alloys. In this technique a mixture of sulfates and bisulfates of sodium and potassium is kept saturated with water at 250-300degC in an open pyrex glass beaker and electrolysed using platinum anode and the material to be charged as the cathode. Most of the studies were carried out on Zr alloys. It is shown that because of the high hydrogen flux available at the surface and the high diffusivity of hydrogen in metals at these temperatures the materials pick up hydrogen faster and more uniformly than the conventional electrolytic charging at room temperature and high temperature autoclaving in LiOH solutions. Chemical analysis, metallographic examination and XRD studies confirm this. This technique has been used to charge hydrogen into many iron and nickel base austentic alloys, which are very resistant to hydrogen pick up and to H-embrittlement. Since this involved a novel method of electrolysing water, the hydrogen/deuterium isotopic ratio has been studied. At this temperatures the D/H ratio in the evolved hydrogen gas was found to be closer to the value in the liquid water, which means a smaller separation factor. This confirm the earlier observation that separation factor decreases with increase of temperature. (author). 16 refs., 21 fi gs., 6 tabs

  15. Precursors-Derived Ceramic Membranes for High-Temperature Separation of Hydrogen

    OpenAIRE

    Yuji, Iwamoto

    2007-01-01

    This review describes recent progress in the development of hydrogen-permselective ceramic membranes derived from organometallic precursors. Microstructure and gas transport property of microporous amorphous silica-based membranes are briefly described. Then, high-temperature hydrogen permselectivity, hydrothermal stability as well as hydrogen/steam selectivity of the amorphous silica-based membranes are discussed from a viewpoint of application to membrane reactors for conversion enhancement...

  16. Experimental evaluation of improved dual temperature hydrogen isotopic exchange reaction system

    International Nuclear Information System (INIS)

    Asakura, Yamato; Uchida, Shunsuke

    1984-01-01

    A proposed dual temperature hydrogen isotopic exchange reaction system between water and hydrogen gas is evaluated experimentally. The proposed system is composed of low temperature co-current reactors for reaction between water mists and hydrogen gas and high temperature co-current reactors for reaction between water vapor and hydrogen gas. Thus, operation is possible under atmospheric pressure with high reaction efficiency. Using the pilot test system which is composed of ten low temperature (30 0 C) reaction units and ten high temperature (200 0 C) reaction units, an experimental separation of deuterium from light water is carried out. The enrichment factor under steady state conditions, its dependency on operating time, and the reaction period necessary to obtain the steady state enrichment factor are determined experimentally and compared with calculations. It is shown that separation ability in a multistage reaction system can be estimated by numerical calculation using actual reaction efficiency in a unit reactor. (author)

  17. Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

    International Nuclear Information System (INIS)

    Čeřovský, M.; Khun, J.; Rusová, K.; Scholtz, V.; Soušková, H.

    2013-01-01

    The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials

  18. Determination of hydrogen diffusivity and permeability in W near room temperature applying a tritium tracer technique

    International Nuclear Information System (INIS)

    Ikeda, T.; Otsuka, T.; Tanabe, T.

    2011-01-01

    Tungsten is a primary candidate of plasma facing material in ITER and beyond, owing to its good thermal property and low erosion. But hydrogen solubility and diffusivity near ITER operation temperatures (below 500 K) have scarcely studied. Mainly because its low hydrogen solubility and diffusivity at lower temperatures make the detection of hydrogen quite difficult. We have tried to observe hydrogen plasma driven permeation (PDP) through nickel and tungsten near room temperatures applying a tritium tracer technique, which is extremely sensible to detect tritium diluted in hydrogen. The apparent diffusion coefficients for PDP were determined by permeation lag times at first time, and those for nickel and tungsten were similar or a few times larger than those for gas driven permeation (GDP). The permeation rates for PDP in nickel and tungsten were larger than those for GDP normalized to the same gas pressure about 20 and 5 times larger, respectively.

  19. High-temperature effect of hydrogen on sintered alpha-silicon carbide

    Science.gov (United States)

    Hallum, G. W.; Herbell, T. P.

    1986-01-01

    Sintered alpha-silicon carbide was exposed to pure, dry hydrogen at high temperatures for times up to 500 hr. Weight loss and corrosion were seen after 50 hr at temperatures as low as 1000 C. Corrosion of SiC by hydrogen produced grain boundary deterioration at 1100 C and a mixture of grain and grain boundary deterioration at 1300 C. Statistically significant strength reductions were seen in samples exposed to hydrogen for times greater than 50 hr and temperatures above 1100 C. Critical fracture origins were identified by fractography as either general grain boundary corrision at 1100 C or as corrosion pits at 1300 C. A maximum strength decrease of approximately 33 percent was seen at 1100 and 1300 C after 500 hr exposure to hydrogen. A computer assisted thermodynamic program was also used to predict possible reaction species of SiC and hydrogen.

  20. Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Čeřovský, M., E-mail: scholtz@aldebaran.cz [Institute of Chemical Technology in Prague, Department of Food Preservation, Faculty of Food and Biochemical Technology (Czech Republic); Khun, J. [Institute of Chemical Technology in Prague, Department of Physics and Measurements, Faculty of Chemical Engineering (Czech Republic); Rusová, K. [Institute of Chemical Technology in Prague, Department of Food Preservation, Faculty of Food and Biochemical Technology (Czech Republic); Scholtz, V. [Institute of Chemical Technology in Prague, Department of Physics and Measurements, Faculty of Chemical Engineering (Czech Republic); Soušková, H. [Institute of Chemical Technology in Prague, Department of Computing and Control Engineering, Faculty of Chemical Engineering (Czech Republic)

    2013-09-15

    The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.

  1. Basic study on high temperature gas cooled reactor technology for hydrogen production

    International Nuclear Information System (INIS)

    Chang, Jong Hwa; Lee, W. J.; Lee, H. M.

    2003-01-01

    The annual production of hydrogen in the world is about 500 billion m 3 . Currently hydrogen is consumed mainly in chemical industries. However hydrogen has huge potential to be consumed in transportation sector in coming decades. Assuming that 10% of fossil energy in transportation sector is substituted by hydrogen in 2020, the hydrogen in the sector will exceed current hydrogen consumption by more than 2.5 times. Currently hydrogen is mainly produced by steam reforming of natural gas. Steam reforming process is chiefest way to produce hydrogen for mass production. In the future, hydrogen has to be produced in a way to minimize CO2 emission during its production process as well as to satisfy economic competition. One of the alternatives to produce hydrogen under such criteria is using heat source of high-temperature gas-cooled reactor. The high-temperature gas-cooled reactor represents one type of the next generation of nuclear reactors for safe and reliable operation as well as for efficient and economic generation of energy

  2. Influence of hydrogen additions on high-temperature superplasticity of titanium alloys

    International Nuclear Information System (INIS)

    Lederich, R.J.; Sastry, S.M.L.

    1982-01-01

    The effects of the addition of up to 1.0 wt pct hydrogen as a transient alloying element on the superplastic formability (SPF) of fine-grained, equiaxed Ti-6Al-4V (Ti-64) and duplex-annealed Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) were determined. Small amounts of internal hydrogen greatly improve the SPF of the alloys. Formability at 720-900 C was evaluated by an instrumented cone-forming test with continuous monitoring of strain with time. Argon/1 pct hydrogen and argon/4 pct hydrogen gas mixtures were used for charging the alloys with hydrogen as well as for superplastic forming. Hydrogen additions lower the beta-transus temperature of alpha-beta titanium alloys, and the proportions of the alpha and beta phases required for optimum superplasticity can thus be obtained at lower temperatures in hydrogen-modified alloys than in standard alloys. The increased amount of beta phase in the hydrogen-modified titanium alloys reduces the grain growth rates at forming temperature, thus reducing the time-dependent decrease in superplastic strain rate at constant stress or the increase in flow stress at constant strain rate. Process parameters for superplastic forming of Ti-64 and Ti-6242 using argon-hydrogen gas mixtures were determined. 8 references

  3. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    Directory of Open Access Journals (Sweden)

    Honggang Chang

    2015-10-01

    Full Text Available With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

  4. Medium temperature reaction between lanthanide and actinide carbides and hydrogen; Reaction a temperature moyenne entre les monocarbures de lanthanides et d'actinides et l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Dean, G; Lorenzelli, R; Pascard, R [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-07-01

    Hydrogen is fixed reversibly by the lanthanide and actinide mono carbides in the range 25 - 400 C, as for pure corresponding metals. Hydrogen goes into the carbides lattice through carbon vacancies and the total fixed amount is approximately equal to two hydrogen atoms per initial vacancy. Final products c.n thus be considered as carbo-hydrides of general formula M(C{sub 1-x}, H{sub 2x}). The primitive CFC, NaCl type, structure remains unchanged but expands strongly in the case of actinide carbides. With lanthanide carbides, hydrogenation induces a phase transformation with reappearance of the metal structure (HCP). Hydrogen decomposition pressures of all the studied carbo-hydrides are greater than those of the corresponding di-hydrides. (authors) [French] Les monocarbures d'actinides et de lanthanides fixent reversiblement de l'hydrogene a temperature peu elevee, a peu pres dans les memes conditions que les metaux purs correspondants. L'hydrogene penetre dans le reseau des carbures par l'intermediaire des lacunes de carbone, et la quantite totale fixee est approximativement egale a deux atomes d'hydrogene par lacune initiale. Les produits obtenus peuvent donc etre consideres comme des carbohydrures de formule generale M(C{sub 1-x}, H{sub 2x}). La structure d'origine CFC, type NaCl est conservee, mais avec une forte expansion, dans le cas des carbures d'actinides. En revanche, l'hydrogenation entraine un changement de phase cristalline avec retour a la structure du metal (HC) pour les carbures de lanthanides. Tous les carbohydrures etudies ont des tensions de decomposition en hydrogene superieures a celles des dihydrures correspondants. (auteurs)

  5. Hydrogen termination of CVD diamond films by high-temperature annealing at atmospheric pressure

    NARCIS (Netherlands)

    Seshan, V.; Ullien, D.; Castellanos-Gomez, A.; Sachdeva, S.; Murthy, D.H.K.; Savenije, T.J.; Ahmad, H.A.; Nunney, T.S.; Janssens, S.D.; Haenen, K.; Nesládek, M.; Van der Zant, H.S.J.; Sudhölter, E.J.R.; De Smet, L.C.P.M.

    2013-01-01

    A high-temperature procedure to hydrogenate diamond films using molecular hydrogen at atmospheric pressure was explored. Undoped and doped chemical vapour deposited (CVD) polycrystalline diamond films were treated according to our annealing method using a H2 gas flow down to ?50 ml/min (STP) at

  6. Temperature dependence of anti-hydrogen production in the ATHENA experiment

    CERN Document Server

    Bonomi, G; Amsler, Claude; Bouchta, A; Bowe, P; Carraro, C; Cesar, C L; Charlton, M; Doser, Michael; Filippini, V; Fontana, A; Fujiwara, M C; Funakoshi, R; Genova, P; Hangst, J S; Hayano, R S; Jørgensen, L V; Lagomarsino, V; Landua, Rolf; Lindelöf, D; Lodi-Rizzini, E; Macri, M; Madsen, N; Montagna, P; Pruys, H S; Regenfus, C; Riedler, P; Rotondi, A; Testera, G; Variola, A; Van der Werf, D P

    2004-01-01

    The ATHENA experiment recently produced the first sample of cold anti-hydrogen atoms by mixing cold plasmas of anti-protons and positrons. The temperature of the positron plasma was increased by controlled RF heating and the anti-hydrogen production rate was measured. Preliminary results are presented. (8 refs).

  7. Effect of temperature and hydraulic retention time on hydrogen producing granules: Homoacetogenesis and morphological characteristics

    International Nuclear Information System (INIS)

    Abreu, A. A.; Danko, A. S.; Alves, M. M.

    2009-01-01

    The effect of temperature and hydraulic retention time (HRT) on the homoacetogenesisi and on the morphological characteristics of hydrogen producing granules was investigated. Hydrogen was produced using an expanded granular sludge blanket (EGSB) reactor, fed with glucose and L-arabinose, under mesophilic (37 degree centigrade), thermophilic (55 degree centigrade), and hyper thermophilic (70 degree centigrade) conditions. (Author)

  8. Temperature setting and thermal regulation system for liquid hydrogen bubble chamber; Systeme de mise en temperature et de regulation thermique de chambres a bulles a hydrogene liquide

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J; Prugne, P; Roubeau, P [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1961-07-01

    Hydrogen bubble chamber cooling and constant temperature maintenance in the 25/28 deg. K, range by means of liquid hydrogen boiling under atmospheric pressure (20.4 deg. K) need a device, if possible automatic allowing the introduction of a variable amount of cold to counterbalance the heat transfer either static or due to the chamber operation. A variable impedance heat exchanger has been designed, built and experimented for this purpose. This device, which takes little space (less than 1000 cm{sup 3}) allows transfer of a variable cold power between 0 and 500 watts (0 to 50 liter of evaporated hydrogen). (author) [French] Pour le refroidissement des chambres a bulles a hydrogene et pour le maintien d'une temperature constante dans la gamme 25/28 deg. K au moyen d'hydrogene a l'ebullition sous pression atmospherique (20,4 deg. K), on a besoin d'un dispositif, si possible automatique, permettant l'introduction d'une quantite variable de froid pour compenser le transfert de chaleur, soit statique, soit du a l'operation de la chambre. Un echangeur de chaleur a impedance variable a ete concu, construit et essaye pour cet usage. Ce dispositif qui est peu encombrant (en dessous de 1000 cm{sup 3} ) permet le transfert d'une puissance frigorifique, variable entre 0 et 500 watts (0 a 50 litres d'hydrogene evapore). (auteur)

  9. System Evaluation and Economic Analysis of a HTGR Powered High-Temperature Electrolysis Hydrogen Production Plant

    International Nuclear Information System (INIS)

    McKellar, Michael G.; Harvego, Edwin A.; Gandrik, Anastasia A.

    2010-01-01

    A design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production has been developed. The HTE plant is powered by a high-temperature gas-cooled reactor (HTGR) whose configuration and operating conditions are based on the latest design parameters planned for the Next Generation Nuclear Plant (NGNP). The current HTGR reference design specifies a reactor power of 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 322 C and 750 C, respectively. The power conversion unit will be a Rankine steam cycle with a power conversion efficiency of 40%. The reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes a steam-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The overall system thermal-to-hydrogen production efficiency (based on the higher heating value of the produced hydrogen) is 40.4% at a hydrogen production rate of 1.75 kg/s and an oxygen production rate of 13.8 kg/s. An economic analysis of this plant was performed with realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a cost of $3.67/kg of hydrogen assuming an internal rate of return, IRR, of 12% and a debt to equity ratio of 80%/20%. A second analysis shows that if the power cycle efficiency increases to 44.4%, the hydrogen production efficiency increases to 42.8% and the hydrogen and oxygen production rates are 1.85 kg/s and 14.6 kg/s respectively. At the higher power cycle efficiency and an IRR of 12% the cost of hydrogen production is $3.50/kg.

  10. Economic Analysis of a Nuclear Reactor Powered High-Temperature Electrolysis Hydrogen Production Plant

    International Nuclear Information System (INIS)

    E. A. Harvego; M. G. McKellar; M. S. Sohal; J. E. O'Brien; J. S. Herring

    2008-01-01

    A reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production was developed to provide a basis for comparing the HTE concept with other hydrogen production concepts. The reference plant design is driven by a high-temperature helium-cooled nuclear reactor coupled to a direct Brayton power cycle. The reference design reactor power is 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 540 C and 900 C, respectively. The electrolysis unit used to produce hydrogen includes 4,009,177 cells with a per-cell active area of 225 cm2. The optimized design for the reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes an air-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The inlet air for the air-sweep system is compressed to the system operating pressure of 5.0 MPa in a four-stage compressor with intercooling. The alternating-current, AC, to direct-current, DC, conversion efficiency is 96%. The overall system thermal-to-hydrogen production efficiency (based on the lower heating value of the produced hydrogen) is 47.12% at a hydrogen production rate of 2.356 kg/s. An economic analysis of this plant was performed using the standardized H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program, and using realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost. A cost of $3.23/kg of hydrogen was calculated assuming an internal rate of return of 10%

  11. Core Body and Skin Temperature in Type 1 Narcolepsy in Daily Life; Effects of Sodium Oxybate and Prediction of Sleep Attacks

    NARCIS (Netherlands)

    van der Heide, Astrid; Werth, Esther; Donjacour, Claire E H M; Reijntjes, Robert H A M; Lammers, Gert Jan; Van Someren, Eus J W; Baumann, Christian R; Fronczek, Rolf

    2016-01-01

    STUDY OBJECTIVES: Previous laboratory studies in narcolepsy patients showed altered core body and skin temperatures, which are hypothesised to be related to a disturbed sleep wake regulation. In this ambulatory study we assessed temperature profiles in normal daily life, and whether sleep attacks

  12. Optimizing a High-Temperature Hydrogen Co-generation Reactor for Both Economic and Environmental Performance

    International Nuclear Information System (INIS)

    Weimar, Mark R.; Wood, Thomas W.; Reichmuth, Barbara A.; Johnson, Wayne L.

    2003-01-01

    This paper analyzes outcomes for a 3000 MWt High Temperature Gas Reaction nuclear power plant, given price and cost assumptions, and determined what level of hydrogen and electricity production would optimize the plant economically and environmentally (carbon reduction). The tradeoff between producing hydrogen through steam methane reformation and producing electricity is so disproportionate, that advanced reactors will likely be used only as peaking plants for electricity unless policymakers intervene with incentives to change the mix of electricity and hydrogen. The magnitude of the increase in electric prices or decrease in hydrogen prices required to allow electricity production indicate that substantial error in cost estimates would be required to change our analysis.

  13. Heat pump cycle by hydrogen-absorbing alloys to assist high-temperature gas-cooled reactor in producing hydrogen

    International Nuclear Information System (INIS)

    Satoshi, Fukada; Nobutaka, Hayashi

    2010-01-01

    A chemical heat pump system using two hydrogen-absorbing alloys is proposed to utilise heat exhausted from a high-temperature source such as a high-temperature gas-cooled reactor (HTGR), more efficiently. The heat pump system is designed to produce H 2 based on the S-I cycle more efficiently. The overall system proposed here consists of HTGR, He gas turbines, chemical heat pumps and reaction vessels corresponding to the three-step decomposition reactions comprised in the S-I process. A fundamental research is experimentally performed on heat generation in a single bed packed with a hydrogen-absorbing alloy that may work at the H 2 production temperature. The hydrogen-absorbing alloy of Zr(V 1-x Fe x ) 2 is selected as a material that has a proper plateau pressure for the heat pump system operated between the input and output temperatures of HTGR and reaction vessels of the S-I cycle. Temperature jump due to heat generated when the alloy absorbs H 2 proves that the alloy-H 2 system can heat up the exhaust gas even at 600 deg. C without any external mechanical force. (authors)

  14. Penetration of hydrogen isotopes through EhI 698 alloy at high pressure and temperature

    International Nuclear Information System (INIS)

    Bystritskij, V.M.; Voznyak, Ya.; Granovskij, V.B.

    1986-01-01

    The paper deals with investigations of the process of hydrogen and deuterium penetration through the high-temperature alloy EhI-698 at a pressure up to 1 kbar and temperature up to 1050 K. Parameters of the process obey Sieverts's law and can be described by Arrenius's and Vant-Goff's equations. The obtained results lead to a conclusion that the alloy EhI-698 is good for vessels to be employed in hydrogen media

  15. Modelling the influence of austenitisation temperature on hydrogen trapping in Nb containing martensitic steels

    International Nuclear Information System (INIS)

    Lang, Peter; Rath, Markus; Kozeschnik, Ernst; Rivera-Diaz-del-Castillo, Pedro E.J.

    2015-01-01

    Hydrogen trapping behaviour is investigated by means of thermokinetic simulations in a martensitic steel. The heat treatment consists of austenitisation followed by quenching and tempering. The model prescribes a minimum in hydrogen trapping at an austenitisation temperature of 1050 °C. Below this temperature, austenite grain boundaries are the prevailing trap, whereas niobium atoms in solid solution are the main traps above 1050 °C. The model describes precisely the experimental results

  16. Solubility of hydrogen in water in a broad temperature and pressure range

    International Nuclear Information System (INIS)

    Baranenko, V.I.; Kirov, V.S.

    1989-01-01

    In the coolant of water-water reactors, as a result of radiolytic decomposition of water and chemical additives (hydrazine and ammonia) and saturation of the make-up water of the first loop with free hydrogen in order to suppress radiolysis, 30-60 ml/kg of hydrogen is present in normal conditions. On being released from the water, it is free to accumulate in micropores of the metals, resulting in hydrogen embrittlement; gas accumulates in stagnant zones, with deterioration in heat transfer in the first loop and corresponding difficulty in the use of the reactor and the whole reactor loop. To determine the amount of free hydrogen and hydrogen dissolved in water in different elements of the first loop, it is necessary to know the limiting solubility of hydrogen in water at different temperatures and pressures, and also to have the corresponding theoretical dependences. The experimental data on the solubility of hydrogen in water are nonsystematic and do not cover the parameter ranges of modern nuclear power plants (P = 10-30 MPa, T = 260-370C). Therefore, the aim of the present work is to establish a well-founded method of calculating the limiting solubility of hydrogen in water and, on this basis, to compile tables of the limiting solubility of hydrogen in water at pressures 0.1-50 MPa and temperatures 0-370C

  17. Safety characteristics of hydrogen at super ambient conditions: lubricant contamination influencing the auto ignition temperature

    International Nuclear Information System (INIS)

    Liebner, C.; Schroder, V.; Holtappels, K.

    2006-01-01

    Inventing hydrogen as a commonly used future energy carrier the long term social acceptance as well as the clean energy image strongly depends upon the safety of its applications. The safety characteristics of hydrogen build a special challenge e.g. in the field of combustion engine development. Small impurities from lubricants used in motors and pumps, may serve as radical source, strongly influencing the auto ignition temperature of hydrogen. Auto Ignition Temperature (AIT) of Hydrogen-Air mixtures were measured in closed autoclaves made from stainless steel, similar to the closed bomb method described in the European standard EN 1839. Initial pressures of 10 bar(a) and 30 bar(a) of a premixed stoichiometric hydrogen-air mixture were investigated. Auto ignition can be obtained about 100 K below the standard AIT (560 deg C, atmospheric pressure) and 300 K below the standard AIT when contaminated through motor oil. (authors)

  18. Hydrogen absorption/desorption characteristics of room temperature ...

    Indian Academy of Sciences (India)

    ZrMn2-Ni system; metal hydrides; hydrogen storage materials. ... where ∼ 2.5 to 2.9 H/F.U. can be reversibly stored under the ideal operating conditions. ... these are promising candidates for stationary and short range mobile applications.

  19. Hydrogen embrittlement of Zr-2.5Nb PT with temperature

    International Nuclear Information System (INIS)

    Oh, Dong Joon; Ahn, Sang Bok; Kim, Young Suk

    2003-01-01

    The aim of this study is to investigate the effect of hydrogen embrittlement of Zr-2.5Nb CANDU pressure tube. The tests were performed at three hydrogen contents for transverse tensile and CCT specimens while the test temperatures were changed (RT to 300 .deg. C). The specimens were directly machined from the tube retaining original curvature using electric discharge machine. Both the transverse tensile and the fracture toughness tests showed the hydrogen embrittlement clearly at RT but this phenomenon was disappeared while the test temperature arrived over 250 .deg. C

  20. High temperature attack of ores by a liquor containing essentially a soluble bicarbonate

    International Nuclear Information System (INIS)

    Maurel, Pierre; Nicolas, Francois; Bosca, Bernard.

    1978-01-01

    New process for high temperature oxidizing digestion of ores containing at least one metal in the uranium, vanadium and molybdenum group, by an aqueous liquor containing sodium bicarbonate and sodium carbonate in the presence of free oxygen insufflated into the reaction medium [fr

  1. 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.

  2. Measurement of effective solvus temperature of hydrogen in Zr - 2. 5 wt % Nb using acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, C.E.; Ambler, J.F.R.

    1978-01-01

    The effect of applied tensile stress on the solvus temperature of hydrogen in cold-worked Zr - 2.5 wt % Nb has been measured using acoustic emission. Hydrides are necessary for delayed hydrogen cracking and the lowest temperature at which hydride cracking cannot be detected by acoustic emission was taken as the solvus temperature. The results show that any effect of tensile stress on terminal solubility, Cs, is undetectable. Between about 2 and 100 ppM hydrogen, the results can be described by: C/sub s/ = 1.40 x 10/sup 5/ exp - (36100/RT) ppM. They also suggest that the equilibrium phase, delta-hydride, is responsible for delayed hydrogen cracking.

  3. Compatibility between vandium-base alloys and flowing lithium: Partitioning of hydrogen at elevated temperatures

    International Nuclear Information System (INIS)

    Hull, A.B.; Chopra, O.K.; Loomis, B.; Smith, D.

    1989-12-01

    A major concern in fusion reactor design is possible hydrogen-isotope-induced embrittlement of structural alloys in the neutron environment expected in these reactors. Hydrogen fractionation occurs between lithium and various refractory metals according to a temperature-dependent distribution coefficient, K H , that is defined as the ration of the hydrogen concentration in the metallic specimen to that in the liquid lithium. In the present work, K H was determined for pure vanadium and several binary and ternary alloys, and the commercial Vanstar 7. Hydrogen distribution studies were performed in an austenitic steel forced-circulation lithium loop. Equilibrium concentrations of hydrogen in vanadium-base alloys exposed to flowing lithium at temperatures of 350 to 550 degree C were measured by inert gas fusion techniques and residual gas analysis. Thermodynamic calculations are consistent with the effect of chromium and titanium in the alloys on the resultant hydrogen fractionation. Experimental and calculated results indicate that K H values are very low; i.e., the hydrogen concentrations in the lithium-equilibrated vanadium-base alloy specimens are about two orders of magnitude lower than those in the lithium. Because of this low distribution coefficient, embrittlement of vanadium alloys by hydrogen in lithium would not be expected. 15 refs., 5 figs., 4 tabs

  4. Hydrogen production methods efficiency coupled to an advanced high temperature accelerator driven system

    International Nuclear Information System (INIS)

    Rodríguez, Daniel González; Lira, Carlos Alberto Brayner de Oliveira

    2017-01-01

    The hydrogen economy is one of the most promising concepts for the energy future. In this scenario, oil is replaced by hydrogen as an energy carrier. This hydrogen, rather than oil, must be produced in volumes not provided by the currently employed methods. In this work two high temperature hydrogen production methods coupled to an advanced nuclear system are presented. A new design of a pebbled-bed accelerator nuclear driven system called TADSEA is chosen because of the advantages it has in matters of transmutation and safety. For the conceptual design of the high temperature electrolysis process a detailed computational fluid dynamics model was developed to analyze the solid oxide electrolytic cell that has a huge influence on the process efficiency. A detailed flowsheet of the high temperature electrolysis process coupled to TADSEA through a Brayton gas cycle was developed using chemical process simulation software: Aspen HYSYS®. The model with optimized operating conditions produces 0.1627 kg/s of hydrogen, resulting in an overall process efficiency of 34.51%, a value in the range of results reported by other authors. A conceptual design of the iodine-sulfur thermochemical water splitting cycle was also developed. The overall efficiency of the process was calculated performing an energy balance resulting in 22.56%. The values of efficiency, hydrogen production rate and energy consumption of the proposed models are in the values considered acceptable in the hydrogen economy concept, being also compatible with the TADSEA design parameters. (author)

  5. Hydrogen production methods efficiency coupled to an advanced high temperature accelerator driven system

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Daniel González; Lira, Carlos Alberto Brayner de Oliveira [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear; Fernández, Carlos García, E-mail: danielgonro@gmail.com, E-mail: mmhamada@ipen.br [Instituto Superior de Tecnologías y Ciencias aplicadas (InSTEC), La Habana (Cuba)

    2017-07-01

    The hydrogen economy is one of the most promising concepts for the energy future. In this scenario, oil is replaced by hydrogen as an energy carrier. This hydrogen, rather than oil, must be produced in volumes not provided by the currently employed methods. In this work two high temperature hydrogen production methods coupled to an advanced nuclear system are presented. A new design of a pebbled-bed accelerator nuclear driven system called TADSEA is chosen because of the advantages it has in matters of transmutation and safety. For the conceptual design of the high temperature electrolysis process a detailed computational fluid dynamics model was developed to analyze the solid oxide electrolytic cell that has a huge influence on the process efficiency. A detailed flowsheet of the high temperature electrolysis process coupled to TADSEA through a Brayton gas cycle was developed using chemical process simulation software: Aspen HYSYS®. The model with optimized operating conditions produces 0.1627 kg/s of hydrogen, resulting in an overall process efficiency of 34.51%, a value in the range of results reported by other authors. A conceptual design of the iodine-sulfur thermochemical water splitting cycle was also developed. The overall efficiency of the process was calculated performing an energy balance resulting in 22.56%. The values of efficiency, hydrogen production rate and energy consumption of the proposed models are in the values considered acceptable in the hydrogen economy concept, being also compatible with the TADSEA design parameters. (author)

  6. CHALLENGES IN GENERATING HYDROGEN BY HIGH TEMPERATURE ELECTROLYSIS USING SOLID OXIDE CELLS

    Energy Technology Data Exchange (ETDEWEB)

    M. S. Sohal; J. E. O' Brien; C. M. Stoots; M. G. McKellar; J. S. Herring; E. A. Harvego

    2008-03-01

    Idaho National Laboratory’s (INL) high temperature electrolysis research to generate hydrogen using solid oxide electrolysis cells is presented in this paper. The research results reported here have been obtained in a laboratory-scale apparatus. These results and common scale-up issues also indicate that for the technology to be successful in a large industrial setting, several technical, economical, and manufacturing issues have to be resolved. Some of the issues related to solid oxide cells are stack design and performance optimization, identification and evaluation of cell performance degradation parameters and processes, integrity and reliability of the solid oxide electrolysis (SOEC) stacks, life-time prediction and extension of the SOEC stack, and cost reduction and economic manufacturing of the SOEC stacks. Besides the solid oxide cells, balance of the hydrogen generating plant also needs significant development. These issues are process and ohmic heat source needed for maintaining the reaction temperature (~830°C), high temperature heat exchangers and recuperators, equal distribution of the reactants into each cell, system analysis of hydrogen and associated energy generating plant, and cost optimization. An economic analysis of this plant was performed using the standardized H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program, and using realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a cost of $3.23/kg of hydrogen assuming an internal rate of return of 10%. These issues need interdisciplinary research effort of federal laboratories, solid oxide cell manufacturers, hydrogen consumers, and other such stakeholders. This paper discusses research and development accomplished by INL on such issues and highlights associated challenges that need to

  7. Study of the chemisorption and hydrogenation of propylene on platinum by temperature-programed desorption

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, S.; Nakamura, M.; Yoshioka, N.

    1978-01-01

    Temperature-programed desorption (TPD) chromotograms of propylene adsorbed on platinum black in the absence or presence of hydrogen preadsorbed, admitted simultaneously, or admitted later, all showed four peaks at about 260/sup 0/ (A), 380/sup 0/ (B), 570/sup 0/ (C), and higher than 720/sup 0/K (D). Peaks A and B were identified as mixtures of propylene and propane, and peaks C and D were methane formed by thermal decomposition of the chemisorbed propylene during desorption. When nitrogen rather than helium was used as the carrier gas for the TPD, only delta-hydrogen was observed; this suggested that propylene was more strongly adsorbed on the platinum than hydrogen. Studies of the reactivities with propylene of the various types of chemisorbed hydrogen previously detected by TPD showed that propylene reacted with ..gamma..-hydrogen present on the surface in the form of hydrogen atoms chemisorbed on top of platinum atoms and with ..beta..-hydrogen, molecular hydrogen chemisorbed in a bridged form, but did not react with delta-hydrogen. Tables and graph.

  8. Temperature dependent dual hydrogen sensor response of Pd nanoparticle decorated Al doped ZnO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, D.; Barman, P. B.; Hazra, S. K., E-mail: surajithazra@yahoo.co.in [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh-173234 (India); Dutta, D. [IC Design and Fabrication Centre, Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700032 (India); Kumar, M.; Som, T. [SUNAG Laboratory, Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

    2015-10-28

    Sputter deposited Al doped ZnO (AZO) thin films exhibit a dual hydrogen sensing response in the temperature range 40 °C–150 °C after surface modifications with palladium nanoparticles. The unmodified AZO films showed no response in hydrogen in the temperature range 40 °C–150 °C. The operational temperature windows on the low and high temperature sides have been estimated by isolating the semiconductor-to-metal transition temperature zone of the sensor device. The gas response pattern was modeled by considering various adsorption isotherms, which revealed the dominance of heterogeneous adsorption characteristics. The Arrhenius adsorption barrier showed dual variation with change in hydrogen gas concentration on either side of the semiconductor-to-metal transition. A detailed analysis of the hydrogen gas response pattern by considering the changes in nano palladium due to hydrogen adsorption, and semiconductor-to-metal transition of nanocrystalline Al doped ZnO layer due to temperature, along with material characterization studies by glancing incidence X-ray diffraction, atomic force microscopy, and transmission electron microscopy, are presented.

  9. Preliminary estimations on the heat recovery method for hydrogen production by the high temperature steam electrolysis

    International Nuclear Information System (INIS)

    Koh, Jae Hwa; Yoon, Duck Joo

    2009-01-01

    As a part of the project 'development of hydrogen production technologies by high temperature electrolysis using very high temperature reactor', we have developed an electrolyzer model for high temperature steam electrolysis (HTSE) system and carried out some preliminary estimations on the effects of heat recovery on the HTSE hydrogen production system. To produce massive hydrogen by using nuclear energy, the HTSE process is one of the promising technologies with sulfur-iodine and hybrid sulfur process. The HTSE produces hydrogen through electrochemical reaction within the solid oxide electrolysis cell (SOEC), which is a reverse reaction of solid oxide fuel cell (SOFC). The HTSE system generally operates in the temperature range of 700∼900 .deg. C. Advantages of HTSE hydrogen production are (a) clean hydrogen production from water without carbon oxide emission, (b) synergy effect due to using the current SOFC technology and (c) higher thermal efficiency of system when it is coupled nuclear reactor. Since the HTSE system operates over 700 .deg. C, the use of heat recovery is an important consideration for higher efficiency. In this paper, four different heat recovery configurations for the HTSE system have been investigated and estimated

  10. Design Configurations and Coupling High Temperature Gas-Cooled Reactor and Hydrogen Plant

    International Nuclear Information System (INIS)

    Chang H. Oh; Eung Soo Kim; Steven Sherman

    2008-01-01

    The US Department of Energy is investigating the use of high-temperature nuclear reactors to produce hydrogen using either thermochemical cycles or high-temperature electrolysis. Although the hydrogen production processes are in an early stage of development, coupling either of these processes to the high-temperature reactor requires both efficient heat transfer and adequate separation of the facilities to assure that off-normal events in the production facility do not impact the nuclear power plant. An intermediate heat transport loop will be required to separate the operations and safety functions of the nuclear and hydrogen plants. A next generation high-temperature reactor could be envisioned as a single-purpose facility that produces hydrogen or a dual-purpose facility that produces hydrogen and electricity. Early plants, such as the proposed Next Generation Nuclear Plant (NGNP), may be dual-purpose facilities that demonstrate both hydrogen and efficient electrical generation. Later plants could be single-purpose facilities. At this stage of development, both single- and dual-purpose facilities need to be understood

  11. Application of low-temperature plasma for the synthesis of hydrogenated graphene (graphane)

    Science.gov (United States)

    Shavelkina, M. B.; Amirov, R. H.; Katarzhis, V. A.; Kiselev, V. I.

    2017-12-01

    The possibility of a direct synthesis of hydrogenated graphene in decomposition of methane by means of low-temperature plasma was investigated. A DC plasma torch with an expanding channel-anode, a vortex gas supply and a self-setting arc length was used as a generator of low-temperature plasma. Argon was used as the plasma-forming gas. The temperatures of argon plasma and with methane addition to it were determined on the basis of spectral measurements. The synthesis products were characterized by electron microscopy and thermogravimetry. The effect of hydrogenated graphene as a nanomodifier on the properties of the cubic boron nitride based functional ceramics was investigated.

  12. Hydrogen Production System with High Temperature Electrolysis for Nuclear Power Plant

    International Nuclear Information System (INIS)

    Kentaro, Matsunaga; Eiji, Hoashi; Seiji, Fujiwara; Masato, Yoshino; Taka, Ogawa; Shigeo, Kasai

    2006-01-01

    Steam electrolysis with solid oxide cells is one of the most promising methods for hydrogen production, which has the potential to be high efficiency. Its most parts consist of environmentally sound and common materials. Recent development of ceramics with high ionic conductivity suggests the possibility of widening the range of operating temperature with maintaining the high efficiency. Toshiba is constructing a hydrogen production system with solid oxide electrolysis cells for nuclear power plants. Tubular-type cells using YSZ (Yttria-Stabilized- Zirconia) as electrolyte showed good performance of steam electrolysis at 800 to 900 deg C. Larger electrolysis cells with present configuration are to be combined with High Temperature Reactors. The hydrogen production efficiency on the present designed system is expected around 50% at 800 to 900 deg C of operating temperature. For the Fast Reactors, 'advanced cell' with higher efficiency at lower temperature are to be introduced. (authors)

  13. Syntrophic interactions drive the hydrogen production from glucose at low temperature in microbial electrolysis cells

    KAUST Repository

    Lu, Lu; Xing, Defeng; Ren, Nanqi; Logan, Bruce E.

    2012-01-01

    H2 can be obtained from glucose by fermentation at mesophilic temperatures, but here we demonstrate that hydrogen can also be obtained from glucose at low temperatures using microbial electrolysis cells (MECs). H2 was produced from glucose at 4°C

  14. Temperature suppression of STM-induced desorption of hydrogen on Si(100) surfaces

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Nakayama, T.

    1999-01-01

    The temperature dependence of hydrogen (H) desorption from Si(100) H-terminated surfaces by a scanning tunneling microscope (STM) is reported for negative sample bias. It is found that the STM induced H desorption rate (R) decreases several orders of magnitude when the substrate temperature...

  15. Effects of temperature on SCC propagation in high temperature water injected with hydrogen peroxide

    International Nuclear Information System (INIS)

    Nakano, Junichi; Sato, Tomonori; Kato, Chiaki; Yoshiyuki, Kaji; Yamamoto, Masahiro; Tsukada, Takashi

    2012-09-01

    To understand the stress corrosion cracking (SCC) behaviour of austenitic stainless steels (SSs) in the boiling water reactor (BWR) coolant environment, it is significant to investigate the effect of hydrogen peroxide (H 2 O 2 ) produced by the radiolysis of water on SCC under the various water chemistry and operational conditions. At the start-up or shut-down periods, for example, the conditions of radiation and temperature on the structural materials are different from those during the plant normal operation, and may be influencing on SCC behaviour. Therefore, the effect of temperature on SCC in high temperature water injected with H 2 O 2 was evaluated by SCC propagation test at the present study. Oxide films on the metal surface in crack were examined and the thermal equilibrium diagram was calculated to estimate the environmental situation in the crack. On the thermally sensitized type 304 SS, crack growth tests were conducted in high temperature water injected with H 2 O 2 to simulate water radiolysis in the core. Small CT type specimens with a width of 15.5 mm and thickness of 6.2 mm were machined from the sensitized SS. SCC growth tests were conducted in high temperature water injected with 100 ppb H 2 O 2 at 453 and 561 K. To minimize H 2 O 2 decomposition by a contact with metal surface of autoclave, the CT specimen was isolated from inner surface of the autoclave by the inner modules made of polytetrafluoroethylene (PTFE), and PTFE lining was also used for the inner surface of inlet and sampling tubes. Base on the measurement of sampled water, it was confirmed that 80-90 % of injected H 2 O 2 remained around the CT specimen in autoclave. Constant load at initial K levels of 11-20 MPam 1/2 was applied to the CT specimens during crack growth tests. After crack growth tests, CT specimens were split into two pieces on the plane of crack propagation. Scanning electron microscope (SEM) examination and laser Raman spectroscopy for outer oxide layer of oxide

  16. Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.R.; Foger, K.; Breakspere, R.J.

    1979-05-01

    Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts was studied with 0.9-3Vertical Bar3< platinum on silica gel, aerosil, sodium and lanthanum Y zeolites, and ..gamma..-alumina, and on aerosil-supported gold-platinum alloys containing 2, 10, 24, 33, and 85Vertical Bar3< gold. Surface enrichment with gold in the alloy systems, as derived from hydrogen adsorption data and predicted from surface enrichment theory and electron microscopic measurements of particle size, were in good agreement, which indicated that equilibrium was achieved by the thermal treatment (oxygen at 573/sup 0/K, hydrogen at 620/sup 0/K, repeated cycles) used. Hydrogen spillover to gold was observed at the higher hydrogen pressures tested on the alloys with high gold content, and to the zeolite supports. The temperature-programed desorption profiles were independent of gold content, which indicated that gold acts only as diluent, and that isolated surface platinum atoms become populated with hydrogen atoms either by hydrogen atom spillover from platinum ensembles to gold and from the gold to the isolated platinum, and/or by adsorption of a molecule directly on the isolated platinum and chemisorption of one H atom at an adjacent gold atom. The distribution of surface platinum ensembles was evaluated by a computer simulation method.

  17. 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 ...

  18. High temperature corrosion in the thermochemical hydrogen production from nuclear heat

    International Nuclear Information System (INIS)

    Coen-Porisini, F.; Imarisio, G.

    1976-01-01

    In the production of hydrogen by water decomposition utilizing nuclear heat, a multistep process has to be employed. Water and the intermediate chemical products reach in chemical cycles giving hydrogen and oxygen with regeneration of the primary products used. Three cycles are examined, characterized by the presence of halide compounds and particularly hydracids at temperatures up to 800 0 C. Corrosion tests were carried out in hydrobromic acid, hydrochloric acid, ferric chloride solutions, and hydriodic acid

  19. The self limiting effect of hydrogen cluster in gas jet under liquid nitrogen temperature

    International Nuclear Information System (INIS)

    Han Jifeng; Yang Chaowen; Miao Jingwei; Fu Pengtao; Luo Xiaobing; Shi Miangong

    2010-01-01

    The generation of hydrogen clusters in gas jet is tested using the Rayleigh scattering method under liquid nitrogen temperature of 79 K. The self limiting effect of hydrogen cluster is studied and it is found that the cluster formation is greatly affected by the number of expanded molecules. The well designed liquid nitrogen cold trap ensured that the hydrogen cluster would keep maximum size for maximum 15 ms during one gas jet. The scattered light intensity exhibits a power scaling on the backing pressure ranging from 5 to 48 bar with the power value of 4.1.

  20. Ion temperature profiles along a hydrogen diagnostic beam in a TORE SUPRA tokamak plasma

    International Nuclear Information System (INIS)

    Romannikov, A.; Petrov, Yu.; Platts, P.; Khess, V.; Khutter, T.; Farzhon, Zh.; Moro, F.

    2002-01-01

    By means of corpuscular diagnostics one studies temperature of ions along a diagnostic hydrogen beam. Paper presents comparison of temperature of plasma (deuterium) basic ions measures by means of the active corpuscular diagnostics with temperature of C + carbon ions along a beam. One studies behavior peculiarities of T i ion temperature profiles for TORE-SUPRA different modes, such as: formation of plane and even hollow T i profiles for ohmic modes, variation of T i profiles under operation of an ergodic diverter, difference of temperature of basic ions measured by means of the active corpuscular diagnostics from C +5 temperature. Paper offers clear explanation of these peculiarities [ru

  1. Why is magnesium diboride's superconducting temperature increased by the hydrogenation process?

    International Nuclear Information System (INIS)

    Flaumbaum, V.V.; Russell, G.J.; Stewart, G.A.

    2002-01-01

    Full text: This work demonstrates that the superconducting transition temperature for MgB 2 can be increased significantly by the hydrogenation process. A preliminary electronic report has already been placed on the archival web site http://au.arXiv.org/with reference number cond-mat/0112301. Given that there appears not to be a large enough interstitial site to accommodate the hydrogen, it is not yet clear what mechanism is involved. The justification for attempting hydrogenation was that metallic Pd becomes a superconductor when it is hydrogenated. We exposed MgB 2 powder to pure hydrogen gas in a stainless steel chamber and heated it. Before removing the specimen, the chamber was cooled in liquid N 2 and opened to air. This was an attempt to 'poison' the specimen's surface. The T c , determined using ac susceptibility, was found to increased for all hydrogenated specimens. The largest increase achieved so far is AT C ∼1.25 K for a specimen hydrogenated under 10 atm H 2 at 600 deg C for 2 hours (H/MgB 2 ∼ 0.03). However, the optimum conditions are yet to be determined. A further complication is that a similar effect (albeit smaller) is obtained by subjecting the MgB 2 to the same process but with helium or argon gas instead of hydrogen

  2. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E; Roth, F von; Hottinger, P; Truong, T B [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  3. Sensitization of erbium in silicon-rich silica : the effect of annealing temperature and hydrogen passivation

    International Nuclear Information System (INIS)

    Wilkinson, A.R.; Forcales, M.; Elliman, R.G.

    2005-01-01

    This paper reports on the effect of annealing temperature and hydrogen passivation on the excitation cross-section and photoluminescence of erbium in silicon-rich silica. Samples were prepared by co-implantation of Si and Er into SiO 2 followed by a single thermal anneal at temperatures ranging from 800 to 1100 degrees C, and with or without hydrogen passivation performed at 500 degrees C. Using time-resolved photoluminescence, the effective erbium excitation cross-section is shown to increase by a factor 3, while the number of optically active erbium ions decreases by a factor of 4 with increasing annealing temperature. Hydrogen passivation is shown to increase the luminescence intensity and to shorten the luminescence lifetime at 1.54 μm only in the presence of Si nanocrystals. The implications fo these results for realizing a silicon-based optical amplifier are also discussed. (author). 19 refs., 3 figs

  4. Hydrogen production by high temperature electrolysis of water vapour and nuclear reactors

    International Nuclear Information System (INIS)

    Jean-Pierre Py; Alain Capitaine

    2006-01-01

    This paper presents hydrogen production by a nuclear reactor (High Temperature Reactor, HTR or Pressurized Water Reactor, PWR) coupled to a High Temperature Electrolyser (HTE) plant. With respect to the coupling of a HTR with a HTE plant, EDF and AREVA NP had previously selected a combined cycle HTR scheme to convert the reactor heat into electricity. In that case, the steam required for the electrolyser plant is provided either directly from the steam turbine cycle or from a heat exchanger connected with such cycle. Hydrogen efficiency production is valued using high temperature electrolysis. Electrolysis production of hydrogen can be performed with significantly higher thermal efficiencies by operating in the steam phase than in the water phase. The electrolysis performance is assessed with solid oxide and solid proton electrolysis cells. The efficiency from the three operating conditions (endo-thermal, auto-thermal and thermo-neutral) of a high temperature electrolysis process is evaluated. The technical difficulties to use the gases enthalpy to heat the water are analyzed, taking into account efficiency and technological challenges. EDF and AREVA NP have performed an analysis to select an optimized process giving consideration to plant efficiency, plant operation, investment and production costs. The paper provides pathways and identifies R and D actions to reach hydrogen production costs competitive with those of other hydrogen production processes. (authors)

  5. High performance hydrogen storage from Be-BTB metal-organic framework at room temperature.

    Science.gov (United States)

    Lim, Wei-Xian; Thornton, Aaron W; Hill, Anita J; Cox, Barry J; Hill, James M; Hill, Matthew R

    2013-07-09

    The metal-organic framework beryllium benzene tribenzoate (Be-BTB) has recently been reported to have one of the highest gravimetric hydrogen uptakes at room temperature. Storage at room temperature is one of the key requirements for the practical viability of hydrogen-powered vehicles. Be-BTB has an exceptional 298 K storage capacity of 2.3 wt % hydrogen. This result is surprising given that the low adsorption enthalpy of 5.5 kJ mol(-1). In this work, a combination of atomistic simulation and continuum modeling reveals that the beryllium rings contribute strongly to the hydrogen interaction with the framework. These simulations are extended with a thermodynamic energy optimization (TEO) model to compare the performance of Be-BTB to a compressed H2 tank and benchmark materials MOF-5 and MOF-177 in a MOF-based fuel cell. Our investigation shows that none of the MOF-filled tanks satisfy the United States Department of Energy (DOE) storage targets within the required operating temperatures and pressures. However, the Be-BTB tank delivers the most energy per volume and mass compared to the other material-based storage tanks. The pore size and the framework mass are shown to be contributing factors responsible for the superior room temperature hydrogen adsorption of Be-BTB.

  6. Sensitivity Studies of Advanced Reactors Coupled to High Temperature Electrolysis (HTE) Hydrogen Production Processes

    International Nuclear Information System (INIS)

    Edwin A. Harvego; Michael G. McKellar; James E. O'Brien; J. Stephen Herring

    2007-01-01

    High Temperature Electrolysis (HTE), when coupled to an advanced nuclear reactor capable of operating at reactor outlet temperatures of 800 C to 950 C, has the potential to efficiently produce the large quantities of hydrogen needed to meet future energy and transportation needs. To evaluate the potential benefits of nuclear-driven hydrogen production, the UniSim process analysis software was used to evaluate different reactor concepts coupled to a reference HTE process design concept. The reference HTE concept included an Intermediate Heat Exchanger and intermediate helium loop to separate the reactor primary system from the HTE process loops and additional heat exchangers to transfer reactor heat from the intermediate loop to the HTE process loops. The two process loops consisted of the water/steam loop feeding the cathode side of a HTE electrolysis stack, and the steam or air sweep loop used to remove oxygen from the anode side. The UniSim model of the process loops included pumps to circulate the working fluids and heat exchangers to recover heat from the oxygen and hydrogen product streams to improve the overall hydrogen production efficiencies. The reference HTE process loop model was coupled to separate UniSim models developed for three different advanced reactor concepts (a high-temperature helium cooled reactor concept and two different supercritical CO2 reactor concepts). Sensitivity studies were then performed to evaluate the affect of reactor outlet temperature on the power cycle efficiency and overall hydrogen production efficiency for each of the reactor power cycles. The results of these sensitivity studies showed that overall power cycle and hydrogen production efficiencies increased with reactor outlet temperature, but the power cycle producing the highest efficiencies varied depending on the temperature range considered

  7. Advanced Intermediate Heat Transport Loop Design Configurations for Hydrogen Production Using High Temperature Nuclear Reactors

    International Nuclear Information System (INIS)

    Chang Oh; Cliff Davis; Rober Barner; Paul Pickard

    2005-01-01

    The US Department of Energy is investigating the use of high-temperature nuclear reactors to produce hydrogen using either thermochemical cycles or high-temperature electrolysis. Although the hydrogen production processes are in an early stage of development, coupling either of these processes to the high-temperature reactor requires both efficient heat transfer and adequate separation of the facilities to assure that off-normal events in the production facility do not impact the nuclear power plant. An intermediate heat transport loop will be required to separate the operations and safety functions of the nuclear and hydrogen plants. A next generation high-temperature reactor could be envisioned as a single-purpose facility that produces hydrogen or a dual-purpose facility that produces hydrogen and electricity. Early plants, such as the proposed Next Generation Nuclear Plant (NGNP), may be dual-purpose facilities that demonstrate both hydrogen and efficient electrical generation. Later plants could be single-purpose facilities. At this stage of development, both single- and dual-purpose facilities need to be understood. A number of possible configurations for a system that transfers heat between the nuclear reactor and the hydrogen and/or electrical generation plants were identified. These configurations included both direct and indirect cycles for the production of electricity. Both helium and liquid salts were considered as the working fluid in the intermediate heat transport loop. Methods were developed to perform thermal-hydraulic evaluations and cycle-efficiency evaluations of the different configurations and coolants. The thermal-hydraulic evaluations estimated the sizes of various components in the intermediate heat transport loop for the different configurations. The relative sizes of components provide a relative indication of the capital cost associated with the various configurations. Estimates of the overall cycle efficiency of the various

  8. Studies of the use of high-temperature nuclear heat from an HTGR for hydrogen production

    Science.gov (United States)

    Peterman, D. D.; Fontaine, R. W.; Quade, R. N.; Halvers, L. J.; Jahromi, A. M.

    1975-01-01

    The results of a study which surveyed various methods of hydrogen production using nuclear and fossil energy are presented. A description of these methods is provided, and efficiencies are calculated for each case. The process designs of systems that utilize the heat from a general atomic high temperature gas cooled reactor with a steam methane reformer and feed the reformer with substitute natural gas manufactured from coal, using reforming temperatures, are presented. The capital costs for these systems and the resultant hydrogen production price for these cases are discussed along with a research and development program.

  9. Studies of the use of high-temperature nuclear heat from an HTGR for hydrogen production

    International Nuclear Information System (INIS)

    Peterman, D.D.; Fontaine, R.W.; Quade, R.N.; Halvers, L.J.; Jahromi, A.M.

    1975-01-01

    The results of a study which surveyed various methods of hydrogen production using nuclear and fossil energy are presented. A description of these methods is provided, and efficiencies are calculated for each case. The process designs of systems that utilize the heat from a general atomic high temperature gas cooled reactor with a steam methane reformer and feed the reformer with substitute natural gas manufactured from coal, using reforming temperatures, are presented. The capital costs for these systems and the resultant hydrogen production price for these cases are discussed along with a research and development program

  10. The reaction of hydrogen atoms with hydrogen peroxide as a function of temperature

    DEFF Research Database (Denmark)

    Lundström, T.; Christensen, H.; Sehested, K.

    2001-01-01

    The temperature dependence for the reaction of H atoms with H2O2 at pH 1 has been determined using pulse radiolysis technique. The reaction was studied in the temperature range 10-120 degreesC. The rate constant at 25 degreesC was found to be 5.1 +/- 0.5 x 10(7) dm(3) mol(-1) s(-1) and the activa......The temperature dependence for the reaction of H atoms with H2O2 at pH 1 has been determined using pulse radiolysis technique. The reaction was studied in the temperature range 10-120 degreesC. The rate constant at 25 degreesC was found to be 5.1 +/- 0.5 x 10(7) dm(3) mol(-1) s(-1...

  11. Research and development program of hydrogen production system with high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Miyamoto, Y.; Shiozawa, S.; Ogawa, M.; Inagaki, Y.; Nishihara, T.; Shimizu, S.

    2000-01-01

    Japan Atomic Energy Research Institute (JAERI) has been developing a hydrogen production system with a high temperature gas-cooled reactor (HTGR). While the HTGR hydrogen production system has the following advantages compared with a fossil-fired hydrogen production system; low operation cost (economical fuel cost), low CO 2 emission and saving of fossil fuel by use of nuclear heat, it requires some items to be solved as follows; cost reduction of facility such as a reactor, coolant circulation system and so on, development of control and safety technologies. As for the control and safety technologies, JAERI plans demonstration test with hydrogen production system by steam reforming of methane coupling to 30 Wt HTGR, named high temperature engineering test reactor (HTTR). Prior to the demonstration test, a 1/30-scale out-of-pile test facility is in construction for safety review and detailed design of the HTTR hydrogen production system. Also, design study will start for reduction of facility cost. Moreover, basic study on hydrogen production process without CO 2 emission is in progress by thermochemical water splitting. (orig.)

  12. New insights into designing metallacarborane based room temperature hydrogen storage media.

    Science.gov (United States)

    Bora, Pankaj Lochan; Singh, Abhishek K

    2013-10-28

    Metallacarboranes are promising towards realizing room temperature hydrogen storage media because of the presence of both transition metal and carbon atoms. In metallacarborane clusters, the transition metal adsorbs hydrogen molecules and carbon can link these clusters to form metal organic framework, which can serve as a complete storage medium. Using first principles density functional calculations, we chalk out the underlying principles of designing an efficient metallacarborane based hydrogen storage media. The storage capacity of hydrogen depends upon the number of available transition metal d-orbitals, number of carbons, and dopant atoms in the cluster. These factors control the amount of charge transfer from metal to the cluster, thereby affecting the number of adsorbed hydrogen molecules. This correlation between the charge transfer and storage capacity is general in nature, and can be applied to designing efficient hydrogen storage systems. Following this strategy, a search for the best metallacarborane was carried out in which Sc based monocarborane was found to be the most promising H2 sorbent material with a 9 wt.% of reversible storage at ambient pressure and temperature.

  13. Computational model for a high temperature electrolyzer coupled to a HTTR for efficient nuclear hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Daniel; Rojas, Leorlen; Rosales, Jesus; Castro, Landy; Gamez, Abel; Brayner, Carlos, E-mail: danielgonro@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Garcia, Lazaro; Garcia, Carlos; Torre, Raciel de la, E-mail: lgarcia@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Sanchez, Danny [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)

    2015-07-01

    High temperature electrolysis process coupled to a very high temperature reactor (VHTR) is one of the most promising methods for hydrogen production using a nuclear reactor as the primary heat source. However there are not references in the scientific publications of a test facility that allow to evaluate the efficiency of the process and other physical parameters that has to be taken into consideration for its accurate application in the hydrogen economy as a massive production method. For this lack of experimental facilities, mathematical models are one of the most used tools to study this process and theirs flowsheets, in which the electrolyzer is the most important component because of its complexity and importance in the process. A computational fluid dynamic (CFD) model for the evaluation and optimization of the electrolyzer of a high temperature electrolysis hydrogen production process flowsheet was developed using ANSYS FLUENT®. Electrolyzer's operational and design parameters will be optimized in order to obtain the maximum hydrogen production and the higher efficiency in the module. This optimized model of the electrolyzer will be incorporated to a chemical process simulation (CPS) code to study the overall high temperature flowsheet coupled to a high temperature accelerator driven system (ADS) that offers advantages in the transmutation of the spent fuel. (author)

  14. Computational model for a high temperature electrolyzer coupled to a HTTR for efficient nuclear hydrogen production

    International Nuclear Information System (INIS)

    Gonzalez, Daniel; Rojas, Leorlen; Rosales, Jesus; Castro, Landy; Gamez, Abel; Brayner, Carlos; Garcia, Lazaro; Garcia, Carlos; Torre, Raciel de la; Sanchez, Danny

    2015-01-01

    High temperature electrolysis process coupled to a very high temperature reactor (VHTR) is one of the most promising methods for hydrogen production using a nuclear reactor as the primary heat source. However there are not references in the scientific publications of a test facility that allow to evaluate the efficiency of the process and other physical parameters that has to be taken into consideration for its accurate application in the hydrogen economy as a massive production method. For this lack of experimental facilities, mathematical models are one of the most used tools to study this process and theirs flowsheets, in which the electrolyzer is the most important component because of its complexity and importance in the process. A computational fluid dynamic (CFD) model for the evaluation and optimization of the electrolyzer of a high temperature electrolysis hydrogen production process flowsheet was developed using ANSYS FLUENT®. Electrolyzer's operational and design parameters will be optimized in order to obtain the maximum hydrogen production and the higher efficiency in the module. This optimized model of the electrolyzer will be incorporated to a chemical process simulation (CPS) code to study the overall high temperature flowsheet coupled to a high temperature accelerator driven system (ADS) that offers advantages in the transmutation of the spent fuel. (author)

  15. Lithium doping on covalent organic framework-320 for enhancing hydrogen storage at ambient temperature

    International Nuclear Information System (INIS)

    Xia, Liangzhi; Liu, Qing

    2016-01-01

    Density Functional Theory (DFT) combines with grand canonical Monte Carlo (GCMC) simulations are performed to explore the effect of Li doping on the hydrogen storage capability of COF-320. The results show that the interaction energy between the H 2 and the Li-doped COF-320 is about three times higher than that of pristine COF-320. GCMC simulations are employed to study the hydrogen uptake of Li-doped COF-320 at ambient temperature, further confirm that the lithium doping can improve the hydrogen uptake at ambient temperature. Our results demonstrate that Li-doped COFs have good potential in the field of hydrogen storage. - Graphical abstract: Fig. 1. The optimized cluster model used here to represent the COF-320 and possible adsorption sites (A, B, C) for adsorption of metals in the COF-320. The dangling bonds are terminated by H atoms. C, H, and N atoms are shown as gray, white, and blue colors, respectively. Fig. 2. The adsorption isotherm of H 2 in the pristine and Li-doped COF-320 at 298 K. - Highlights: • The binding sites of single and two lithium atoms in COF-320 were studied. • The interaction energy between the H 2 and the Li-doped COF-320 is about three times higher than that of pristine COF-320. • H 2 uptakes on the Li-doped COFs obtain significant improvement at ambient temperature. • Lithium-doping is a successful strategy for improving hydrogen uptake.

  16. Parent material and weldments degradation on SASOL reduction reactors due to combined effect of thermal fatigue, vibration and hydrogen attack

    International Nuclear Information System (INIS)

    Borla, Jan Z.

    2002-01-01

    All six installed reduction reactors showed the same failure pattern, which can be attributed to inadequate original design, material degradation due to service conditions and improper maintenance activities. Service is typically low frequency fatigue load conditions with changes of pressure, temperature and batch load. All revealed defects severely affected the integrity of the pressure envelope and vessels were classified for major repair work with subsequent in situ monitoring program. The justification for such extensive and costly repair required a positive evaluation of the current condition of equipment. After complete study, a report was prepared which included the fitness for purpose evaluation, remaining life assessment and recommendation for future field inspections. All reactors were found to be suitable for repair. Within the scope of repair a number of critical elements were redesigned and replaced. The repair was successful and all reactors were put back into operation. Unique expertise was obtained regarding setting the parameters of dehydrogenation in reference to the heavy wall items. Taking replicas and surface sampling appeared to be very reliable and simple tools in monitoring the condition of pressure envelope. For the purpose of future inspection shutdowns specific inspection requirements were put in place to ensure continuous monitoring of the vessel integrity

  17. Hydrogen production from biomass pyrolysis gas via high temperature steam reforming process

    International Nuclear Information System (INIS)

    Wongchang, Thawatchai; Patumsawad, Suthum

    2010-01-01

    Full text: The aim of this work has been undertaken as part of the design of continuous hydrogen production using the high temperature steam reforming process. The steady-state test condition was carried out using syngas from biomass pyrolysis, whilst operating at high temperatures between 600 and 1200 degree Celsius. The main reformer operating parameters (e.g. temperature, resident time and steam to biomass ratio (S/B)) have been examined in order to optimize the performance of the reformer. The operating temperature is a key factor in determining the extent to which hydrogen production is increased at higher temperatures (900 -1200 degree Celsius) whilst maintaining the same as resident time and S/B ratio. The effects of exhaust gas composition on heating value were also investigated. The steam reforming process produced methane (CH 4 ) and ethylene (C 2 H 4 ) between 600 to 800 degree Celsius and enhanced production ethane (C 2 H 6 ) at 700 degree Celsius. However carbon monoxide (CO) emission was slightly increased for higher temperatures all conditions. The results show that the use of biomass pyrolysis gas can produce higher hydrogen production from high temperature steam reforming. In addition the increasing reformer efficiency needs to be optimized for different operating conditions. (author)

  18. The effects of nanoscale geometry and spillover on room temperature storage of hydrogen on silica nanosprings

    International Nuclear Information System (INIS)

    Corti, Giancarlo; Zhan, Yingqian; Wang, Lidong; Hare, Brian; Cantrell, Timothy; II, Miles Beaux; Prakash, Tej; Ytreberg, F Marty; McIlroy, David N; Miller, Michael A

    2013-01-01

    Silica nanosprings (NSs) consisting of multiple nanowires intertwined were demonstrated to reversibly store 0.85 wt% hydrogen at 20 bar and room temperature. X-ray photoelectron spectroscopy indicates a mixed 3 + –4 + ionization state of the silicon atoms and partially explains the enhanced surface adsorption of H 2 relative to other forms of silica. Theoretical modeling and simulation using a Lennard-Jones potential demonstrated that interstitial sites between the silica nanowires forming the NS are energetically more favorable adsorption sites relative to single nanowires. The addition of Pd nanoparticles to the surface of the silica NSs was demonstrated to increase the hydrogen storage capacity to ≈3.5 wt% at 66 bar and room temperature. Palladium-nanoparticle-induced hydrogen spillover is attributed to the enhanced storage capacity relative to bare silica NSs. (paper)

  19. FINAL REPORT: Room Temperature Hydrogen Storage in Nano-Confined Liquids

    Energy Technology Data Exchange (ETDEWEB)

    VAJO, JOHN

    2014-06-12

    DOE continues to seek solid-state hydrogen storage materials with hydrogen densities of ≥6 wt% and ≥50 g/L that can deliver hydrogen and be recharged at room temperature and moderate pressures enabling widespread use in transportation applications. Meanwhile, development including vehicle engineering and delivery infrastructure continues for compressed-gas hydrogen storage systems. Although compressed gas storage avoids the materials-based issues associated with solid-state storage, achieving acceptable volumetric densities has been a persistent challenge. This project examined the possibility of developing storage materials that would be compatible with compressed gas storage technology based on enhanced hydrogen solubility in nano-confined liquid solvents. These materials would store hydrogen in molecular form eliminating many limitations of current solid-state materials while increasing the volumetric capacity of compressed hydrogen storage vessels. Experimental methods were developed to study hydrogen solubility in nano-confined liquids. These methods included 1) fabrication of composites comprised of volatile liquid solvents for hydrogen confined within the nano-sized pore volume of nanoporous scaffolds and 2) measuring the hydrogen uptake capacity of these composites without altering the composite composition. The hydrogen storage capacities of these nano-confined solvent/scaffold composites were compared with bulk solvents and with empty scaffolds. The solvents and scaffolds were varied to optimize the enhancement in hydrogen solubility that accompanies confinement of the solvent. In addition, computational simulations were performed to study the molecular-scale structure of liquid solvent when confined within an atomically realistic nano-sized pore of a model scaffold. Confined solvent was compared with similar simulations of bulk solvent. The results from the simulations were used to formulate a mechanism for the enhanced solubility and to guide the

  20. Continuous Hydrogen Production from Agricultural Wastewaters at Thermophilic and Hyperthermophilic Temperatures.

    Science.gov (United States)

    Ramos, Lucas Rodrigues; Silva, Edson Luiz

    2017-06-01

    The objective of this study was to investigate the effects of hydraulic retention time (HRT) (8 to 0.5 h) and temperature (55 to 75 °C) in two anaerobic fluidized bed reactors (AFBR) using cheese whey (AFBR-CW = 10,000 mg sugars L -1 ) and vinasse (AFBR-V = 10,000 mg COD L -1 ) as substrates. Decreasing the HRT to 0.5 h increased the hydrogen production rates in both reactors, with maximum values of 5.36 ± 0.81 L H 2 h -1 L -1 in AFBR-CW and 0.71 ± 0.16 L H 2 h -1 L -1 in AFBR-V. The optimal conditions for hydrogen production were the HRT of 4 h and temperature of 65 °C in AFBR-CW, observing maximum hydrogen yield (HY) of 5.51 ± 0.37 mmol H 2 g COD -1 . Still, the maximum HY in AFBR-V was 1.64 ± 0.22 mmol H 2 g COD -1 at 4 h and 55 °C. However, increasing the temperature to 75 °C reduced the hydrogen production in both reactors. Methanol and butyric, acetic, and lactic acids were the main metabolites at temperatures of 55 and 65 °C, favoring the butyric and acetic metabolic pathways of hydrogen production. The increased productions of lactate, propionate, and methanol at 75 °C indicate that the hydrogen-producing bacteria in the thermophilic inoculum were inhibited under hyperthermophilic conditions.

  1. Hydrogen/Oxygen Reactions at High Pressures and Intermediate Temperatures: Flow Reactor Experiments and Kinetic Modeling

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Glarborg, Peter

    A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, the mechanism is used to simulate published data on ignition delay time and laminar burning velocity of hydrogen. The flow reactor results show that at reducing, stoichiometric, and oxidizing conditions, conversion starts at temperatures of 750–775 K, 800–825 K, and 800–825 K, respectively. In oxygen atmosphere......, ignition occurs at the temperature of 775–800 K. In general, the present model provides a good agreement with the measurements in the flow reactor and with recent data on laminar burning velocity and ignition delay time....

  2. The effect of heat pretreatment temperature on fermentative hydrogen production using mixed cultures

    Energy Technology Data Exchange (ETDEWEB)

    Baghchehsaraee, Bita; Nakhla, George; Karamanev, Dimitre; Margaritis, Argyrios [Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario N6A 5B9 (Canada); Reid, Gregor [Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario (Canada); Canadian Research and Development Center for Probiotics, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2 (Canada)

    2008-08-15

    The effect of heat treatment at different temperatures on two types of inocula, activated sludge and anaerobically digested sludge, was investigated in batch cultures. Heat treatments were conducted at 65, 80 and 95 C for 30 min. The untreated inocula produced less amount of hydrogen than the pretreated inocula, with lactic acid as the main metabolite. The maximum yields of 2.3 and 1.6 mol H{sub 2}/mol glucose were achieved for the 65 C pretreated anaerobically digested and activated sludges, respectively. Approximately a 15% decrease in yield was observed with increasing pretreatment temperature from 65 to 95 C concomitant with an increase in butyrate/acetate ratio from 1.5 to 2.4 for anaerobically digested sludge. The increase of pretreatment temperature of activated sludge to 95 C suppressed the hydrogen production by lactic acid fermentation. DNA analysis of the microbial community showed that the elevated pretreatment temperatures reduced the species diversity. (author)

  3. Study of the high temperature characteristics of hydrogen storage alloys

    CERN Document Server

    Rong, Li; Shaoxiong, Zhou; Yan, Qi; 10.1016/j.jallcom.2004.07.006

    2005-01-01

    In this work, the phase structure of as-cast and melt-spun (MmY)/sub 1/(NiCoMnAl)/sub 5/ alloys (the content of yttrium is 0-2.5wt.%) and their electrochemical properties were studied with regard to discharge capacity at different temperatures (30-80 degrees C) and cycling life at 30 degrees C. It is found that the substitution of yttrium increase the electrochemical capacity of the compounds and decrease the difference in capacity between as-cast and as-quenched compounds at 30 degrees C. When increasing the yttrium concentration from 0 to 2.5wt.%, the cycling life of both the as-cast and the melt- spun compounds deteriorated, although the latter have a slightly longer cycle life than the former. The remarkable feature of the alloys obtained by yttrium substitution is the improvement of the high temperature electrochemical properties. It shows that the stability of the hydrides is increased. Compared with the as-cast alloys, the melt-spun ribbons have higher electrochemical charge /discharge capacity in the ...

  4. The INNOHYP-CA Project: producing Hydrogen by innovative high-temperature processes

    International Nuclear Information System (INIS)

    Giaconia, A.; Giorgiantoni, G.; Liberatore, R.; Tarquini, P.; Vignolini, M.

    2008-01-01

    The Project, financed under the 6. Framework Programme, has selected a member of innovative high-temperature processes that seem promising for large-scale production of Hydrogen. ENEA has contributed to the analysis of the status of national and regional projects in the European countries and to the definition of guidelines for the future development of these technologies [it

  5. Fracture toughness of the F-82H steel-effect of loading modes, hydrogen, and temperature

    International Nuclear Information System (INIS)

    Li, H.-X.; Jones, R.H.; Hirth, J.P.; Gelles, D.S.

    1996-01-01

    The effects of loading mode, hydrogen, and temperature on fracture toughness and tearing modulus were examined for a ferritic/martensitic steel (F-82H). The introduction of a shear load component, mode III, significantly decreased the initiation and propagation resistance of cracks compared to the opening load, mode I, behavior. Mode I crack initiation and propagation exhibited the highest resistance. A minimum resistance occurred when the mode I and mode III loads were nearly equal. The presence of 4 wppm hydrogen decreased the cracking resistance compared to behavior without H regardless of the loading mode. The minimum mixed-mode fracture toughness with the presence of hydrogen was about 30% of the hydrogen-free mode I fracture toughness. The mixed-mode toughness exhibited a lesser sensitivity to temperature than the mode I toughness. The J IC value was 284 kJ/m 2 at room temperature, but only 60 kJ/m 2 at -55 C and 30 kJ/m 2 at -90 C. The ductile to brittle transition temperature (DBTT) was apparently higher than -55 C. (orig.)

  6. Butterfly valve with metal seals controls flow of hydrogen from cryogenic through high temperatures

    Science.gov (United States)

    Johnson, L. D.

    1967-01-01

    Butterfly valve with metal seals operates over a temperature range of minus 423 degrees to plus 440 degrees F with hydrogen as a medium and in a radiation environment. Media flow is controlled by an internal butterfly disk which is rotated by an actuation shaft.

  7. A hydrogen production experiment by the thermo-chemical and electrolytic hybrid hydrogen production in lower temperature range. System viability and preliminary thermal efficiency estimation

    International Nuclear Information System (INIS)

    Takai, Toshihide; Nakagiri, Toshio; Inagaki, Yoshiyuki

    2008-10-01

    A new experimental apparatus by the thermo-chemical and electrolytic Hybrid-Hydrogen production in Lower Temperature range (HHLT) was developed and hydrogen production experiment was performed to confirm the system operability. Hydrogen production efficiency was estimated and technical problems were clarified through the experimental results. Stable operation of the SO 3 electrolysis cell and the sulfur dioxide solution electrolysis cell were confirmed during experimental operation and any damage which would be affected solid operation was not detected under post operation inspection. To improve hydrogen production efficiency, it was found that the reduction of sulfuric acid circulation and the decrease in the cell voltage were key issues. (author)

  8. Summary - Advanced high-temperature reactor for hydrogen and electricity production

    International Nuclear Information System (INIS)

    Forsberg, Charles W.

    2001-01-01

    Historically, the production of electricity has been assumed to be the primary application of nuclear energy. That may change. The production of hydrogen (H 2 ) may become a significant application. The technology to produce H 2 using nuclear energy imposes different requirements on the reactor, which, in turn, may require development of new types of reactors. Advanced High Temperature reactors can meet the high temperature requirements to achieve this goal. This alternative application of nuclear energy may necessitate changes in the regulatory structure

  9. Substrate temperature dependence of microcrystallinity in plasma-deposited, boron-doped hydrogenated silicon alloys

    International Nuclear Information System (INIS)

    Rajeswaran, G.; Kampas, F.J.; Vanier, P.E.; Sabatini, R.L.; Tafto, J.

    1983-01-01

    The glow-discharge decomposition of silane diluted in hydrogen using diborane as a dopant results in the deposition of p-type microcrystalline silicon films at relatively low temperatures. The conductivity of these films is critically dependent on the substrate temperature when the ratio of silane flow rate to total gas flow rate is 1%. Electron micrographs show that highly conducting films contain numerous clusters of 2.5-nm crystallites that are embedded in an amorphous medium

  10. On the temperature dependence of H-U{sub iso} in the riding hydrogen model

    Energy Technology Data Exchange (ETDEWEB)

    Lübben, Jens; Volkmann, Christian [Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany); Grabowsky, Simon [School of Chemistry and Biochemistry, Stirling Highway 35, WA-6009 Crawley (Australia); Edwards, Alison [Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Morgenroth, Wolfgang [Institut für Geowissenschaften, Abteilung Kristallographie, Goethe-Universität, Altenhöferallee 1, 60438 Frankfurt am Main (Germany); Fabbiani, Francesca P. A. [GZG, Abteilung Kristallographie, Georg-August Universität, Goldschmidtstrasse 1, 37077 Göttingen (Germany); Sheldrick, George M. [Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany); Dittrich, Birger, E-mail: birger.dittrich@chemie.uni-hamburg.de [Institut für Anorganische und Angewandte Chemie, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany)

    2014-07-01

    The temperature dependence of hydrogen U{sub iso} and parent U{sub eq} in the riding hydrogen model is investigated by neutron diffraction, aspherical-atom refinements and QM/MM and MO/MO cluster calculations. Fixed values of 1.2 or 1.5 appear to be underestimated, especially at temperatures below 100 K. The temperature dependence of H-U{sub iso} in N-acetyl-l-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-U{sub iso} below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found.

  11. On the temperature dependence of H-Uiso in the riding hydrogen model

    International Nuclear Information System (INIS)

    Lübben, Jens; Volkmann, Christian; Grabowsky, Simon; Edwards, Alison; Morgenroth, Wolfgang; Fabbiani, Francesca P. A.; Sheldrick, George M.; Dittrich, Birger

    2014-01-01

    The temperature dependence of hydrogen U iso and parent U eq in the riding hydrogen model is investigated by neutron diffraction, aspherical-atom refinements and QM/MM and MO/MO cluster calculations. Fixed values of 1.2 or 1.5 appear to be underestimated, especially at temperatures below 100 K. The temperature dependence of H-U iso in N-acetyl-l-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-U iso below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found

  12. Hydrogen production system coupled with high-temperature gas-cooled reactor (HTTR)

    International Nuclear Information System (INIS)

    Shiozawa, Shusaku

    2003-01-01

    On the HTTR program, R and D on nuclear reactor technology and R and D on thermal application technology such as hydrogen production and so on, are advanced. When carrying out power generation and thermal application such as hydrogen production and so on, it is, at first, necessary to supply nuclear heat safely, stably and in low cost, JAERI carries out some R and Ds on nuclear reactor technology using HTTR. In parallel to this, JAERI also carries out R and D for jointing nuclear reactor system with thermal application systems because of no experience in the world on high temperature heat of about 1,000 centigrade supplied by nuclear reactor except power generation, and R and D on thermochemical decomposition method IS process for producing hydrogen from water without exhaust of carbon dioxide. Here were described summaries on R and D on nuclear reactor technology, R and D on jointing technology using HTTR hydrogen production system, R and D on IS process hydrogen production, and comparison hydrogen production with other processes. (G.K.)

  13. High-temperature oxidation of Zircaloy in hydrogen-steam mixtures

    International Nuclear Information System (INIS)

    Chung, H.M.; Thomas, G.R.

    1982-09-01

    Oxidation rates of Zircaloy-4 cladding tubes have been measured in hydrogen-steam mixtures at 1200 to 1700 0 C. For a given isothermal oxidation temperature, the oxide layer thicknesses have been measured as a function of time, steam supply rate, and hydrogen overpressure. The oxidation rates in the mixtures were compared with similar data obtained in pure steam and helium-steam environments under otherwise identical conditions. The rates in pure steam and helium-steam mixtures were equivalent and comparable to the parabolic rates obtained under steam-saturated conditions and reported in the literature. However, when the helium was replaced with hydrogen of equivalent partial pressure, a significantly smaller oxidation rate was observed. For high steam-supply rates, the oxidation kinetics in a hydrogen-steam mixture were parabolic, but the rate was smaller than for pure steam or helium-steam mixtures. Under otherwise identical conditions, the ratio of the parabolic rate for hydrogen-steam to that for pure steam decreased with increasing temperature and decreasing steam-supply rate

  14. Present status of r and d on hydrogen production by high temperature electrolysis of steam

    International Nuclear Information System (INIS)

    Hino, Ryutaro; Aita, Hideki; Sekita, Kenji; Haga, Katsuhiro; Miyamoto, Yoshiaki; Iwata, Tomo-o.

    1995-08-01

    In JAERI, design and R and D works on hydrogen production process have been conducted for connecting to the HTTR under construction at the Oarai Establishment of the JAERI as the nuclear heat utilization system. As for a hydrogen production process by high-temperature electrolysis of steam, laboratory-scale experiments have been conducted using a practical electrolysis tube with 12 cells connected in series. Hydrogen was produced at a maximum density of 44 Nml/cm 2 h at 950degC, and know-how of operational procedures and operational experience have been also accumulated. Then, a self-supporting planar electrolysis cell was fabricated in order to improve hydrogen production performance. In the preliminary test with the planar cell, hydrogen has been produced continuously at a maximum density of 36 Nml/cm 2 h at lower electrolysis temperature of 850degC. This report presents typical test results mentioned above, a review of previous studies conducted in the world and R and D items required for connecting to the HTTR. (author)

  15. Efficient room temperature hydrogen sensor based on UV-activated ZnO nano-network

    Science.gov (United States)

    Kumar, Mohit; Kumar, Rahul; Rajamani, Saravanan; Ranwa, Sapana; Fanetti, Mattia; Valant, Matjaz; Kumar, Mahesh

    2017-09-01

    Room temperature hydrogen sensors were fabricated from Au embedded ZnO nano-networks using a 30 mW GaN ultraviolet LED. The Au-decorated ZnO nano-networks were deposited on a SiO2/Si substrate by a chemical vapour deposition process. X-ray diffraction (XRD) spectrum analysis revealed a hexagonal wurtzite structure of ZnO and presence of Au. The ZnO nanoparticles were interconnected, forming nano-network structures. Au nanoparticles were uniformly distributed on ZnO surfaces, as confirmed by FESEM imaging. Interdigitated electrodes (IDEs) were fabricated on the ZnO nano-networks using optical lithography. Sensor performances were measured with and without UV illumination, at room temperate, with concentrations of hydrogen varying from 5 ppm to 1%. The sensor response was found to be ˜21.5% under UV illumination and 0% without UV at room temperature for low hydrogen concentration of 5 ppm. The UV-photoactivated mode enhanced the adsorption of photo-induced O- and O2- ions, and the d-band electron transition from the Au nanoparticles to ZnO—which increased the chemisorbed reaction between hydrogen and oxygen. The sensor response was also measured at 150 °C (without UV illumination) and found to be ˜18% at 5 ppm. Energy efficient low cost hydrogen sensors can be designed and fabricated with the combination of GaN UV LEDs and ZnO nanostructures.

  16. Membrane steam reforming of natural gas for hydrogen production by utilization of medium temperature nuclear reactor

    International Nuclear Information System (INIS)

    Djati Hoesen Salimy

    2010-01-01

    The assessment of steam reforming process with membrane reactor for hydrogen production by utilizing of medium temperature nuclear reactor has been carried out. Difference with the conventional process of natural gas steam reforming that operates at high temperature (800-1000°C), the process with membrane reactor operates at lower temperature (~500°C). This condition is possible because the use of perm-selective membrane that separate product simultaneously in reactor, drive the optimum conversion at the lower temperature. Besides that, membrane reactor also acts the role of separation unit, so the plant will be more compact. From the point of nuclear heat utilization, the low temperature of process opens the chance of medium temperature nuclear reactor utilization as heat source. Couple the medium temperature nuclear reactor with the process give the advantage from the point of saving fossil fuel that give direct implication of decreasing green house gas emission. (author)

  17. Hydrogen enhanced thermal fatigue of y-titanium aluminide

    NARCIS (Netherlands)

    Dunfee, William; Gao, Ming; Wei, Robert P.; Wei, W.

    1995-01-01

    A study of hydrogen enhanced thermal fatigue cracking was carried out for a gamma-based Ti-48Al-2Cr alloy by cycling between room temperature and 750 or 900 °C. The results showed that hydrogen can severely attack the gamma alloy, with resulting lifetimes as low as three cycles, while no failures

  18. Hydrogen Temperature-Programmed Desorption in Platinum Catalysts: Decomposition and Isotopic Exchange by Spillover Hydrogen of Chemisorbed Ammonia.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Miller, J.T.; Meyers, B.L.; Barr, M.K.; Modica, F.S.

    1996-01-01

    H{2}-TPD of Pt/alumina catalysts display multiple hydrogendesorptions. In addition to chemisorbed hydrogen (Peak I) atapproximately 175}o{C, there is a small hydrogen desorption (PeakII) at about 250}o{C and a large, irreversible hydrogen desorption(Peak III) at 450}o{C. The quantity of hydrogen

  19. Exchange of hydrogen isotopes in oxide ceramics at room temperature

    International Nuclear Information System (INIS)

    Suzuki, H.; Morita, K.; Soda, K.

    2001-01-01

    The decay curves of D and up-take curves of H on the exchange of D implanted into Li 2 TiO 3 for H in H 2 O vapor caused by exposure to normal-air at room temperature have been measured as a function of exposure time at different implantation concentrations by means of the elastic recoil detection technique. The re-emission curves of D retained and H up-taken in a specimen by isochronal annealing for 10 min have been also measured. It is found that the thermal re-emission of D and H takes place uniformly over the whole specimen due to local molecular recombination in the bulk and that the re-emission rates of H and D in the near-surface layers are slower than those in the deeper layers. It is also found that the decay of D caused by the D-H exchange takes place rapidly in the beginning and the retained amount of D attains at a constant level and the retained fraction of D are higher as the initial implantation concentrations of D are lower. The decay curves of D and the up-take curves of H have been analysed using the mass balance equations, in which the elementary processes are taken into account according to the exchange model of one way diffusion from the surface into the bulk. It is shown that the solution of the mass balance equations reproduces well the experimental data. The rate constants of the elementary processes determined are discussed. (orig.)

  20. Selective Hydrogenation of Acrolein Over Pd Model Catalysts: Temperature and Particle-Size Effects.

    Science.gov (United States)

    O'Brien, Casey P; Dostert, Karl-Heinz; Schauermann, Swetlana; Freund, Hans-Joachim

    2016-10-24

    The selectivity in the hydrogenation of acrolein over Fe 3 O 4 -supported Pd nanoparticles has been investigated as a function of nanoparticle size in the 220-270 K temperature range. While Pd(111) shows nearly 100 % selectivity towards the desired hydrogenation of the C=O bond to produce propenol, Pd nanoparticles were found to be much less selective towards this product. In situ detection of surface species by using IR-reflection absorption spectroscopy shows that the selectivity towards propenol critically depends on the formation of an oxopropyl spectator species. While an overlayer of oxopropyl species is effectively formed on Pd(111) turning the surface highly selective for propenol formation, this process is strongly hindered on Pd nanoparticles by acrolein decomposition resulting in CO formation. We show that the extent of acrolein decomposition can be tuned by varying the particle size and the reaction temperature. As a result, significant production of propenol is observed over 12 nm Pd nanoparticles at 250 K, while smaller (4 and 7 nm) nanoparticles did not produce propenol at any of the temperatures investigated. The possible origin of particle-size dependence of propenol formation is discussed. This work demonstrates that the selectivity in the hydrogenation of acrolein is controlled by the relative rates of acrolein partial hydrogenation to oxopropyl surface species and of acrolein decomposition, which has significant implications for rational catalyst design. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Influence of temperature, hydrogen and boric acid concentration on IGSCC susceptibility of unsensitized 316 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Arioka, Koji [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan)

    2002-09-01

    IGSCC susceptibility of unsensitized 316SS under PWR primary water was studied as a function of solution temperature, dissolved hydrogen, and boric acid concentration by SSRT test using specimens with cold deformed hump. IGSCC growth rate was dependent on temperature and the obtained activation energy was 21.6K cal/mol. Regarding the influence of dissolved hydrogen, there was a simple monotonic increase in crack growth rate with the increasing hydrogen concentration within the PWR primary water chemistry specifications. Also, there was a remarkable difference in IGSCC susceptibility with regard to the effect to boric acid concentration. Within the tested concentration, the IGSCC susceptibility under high concentrated boric acid solution (2300ppm B) was inhibited in comparison with that under 500ppm B. These temperature and dissolved hydrogen dependencies of IGSCC susceptibility were similar to the literature on published data on irradiated 316SS. Although further study is required to clarify the mechanism, however the similarity of the dependencies suggests that the rate-limited IGSCC process of un-irradiated 316SS is related to that of IASCC. (author)

  2. Importance of temperature, pH, and boric acid concentration on rates of hydrogen production from galvanized steel corrosion

    International Nuclear Information System (INIS)

    Loyola, V.M.

    1982-01-01

    One of the known sources of hydrogen gas within a nuclear plant containment building during a LOCA is the high temperature corrosion of galvanized steel yielding hydrogen gas. The importance of this source of hydrogen will vary depending on the severity of the accident. In an accident which resulted in core degradation, for example, the major source of hydrogen would probably be the metal-water reaction of the zircaloy cladding, and the corrosion of galvanized steel would then become a relatively minor source of hydrogen. However, in an accident in which core degradation is avoided or limited to minor damage, the corrosion of galvanized steel, and presumably of other materials as well, would then become a major contributor to the buildup of hydrogen within containment. The purpose of this paper is to present the overall effects of temperature, pH, and boric acid concentration on the rate of hydrogen generation over a broad range of each parameter

  3. Influence of rolling direction and carbide precipitation on IGSCC susceptibility in hydrogenated high temperature water

    International Nuclear Information System (INIS)

    Arioka, Koji; Yamada, Takuyo; Terachi, Takumi; Chiba, Goro

    2005-01-01

    IGSCC growth behaviors of austenitic stainless steels in hydrogenated high temperature water were studied using compact type specimens (0.5T for cold worked materials). The effect of cold rolling direction, alloy composition and carbide precipitation on crack growth behaviors was studied in hydrogenated high temperature water. Then, to examine the effect of cold work and carbide precipitation on IGSCC behaviors, the role of grain boundary sliding studied in high temperature air using CT specimens. The similar dependences of carbide precipitation and cold work on IGSCC and creep behaviors suggest that grain boundary sliding might play an important role by itself or in conjunction with other reactions such as crack tip dissolution etc. (author)

  4. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    2010-01-01

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion...... of attack surfaces of the cloud computing scenario participants....

  5. SCC growth behavior of stainless steel weld heat-affected zone in hydrogenated high temperature water

    International Nuclear Information System (INIS)

    Yamada, Takuyo; Terachi, Takumi; Miyamoto, Tomoki; Arioka, Koji

    2010-01-01

    It is known that the SCC growth rate of stainless steels in high-temperature water is accelerated by cold-work (CW). The weld heat-affected-zone (HAZ) of stainless steels is also deformed by weld shrinkage. However, only little have been reported on the SCC growth of weld HAZ of SUS316 and SUS304 in hydrogenated high-temperature water. Thus, in this present study, SCC growth experiments were performed using weld HAZ of stainless steels, especially to obtain data on the dependence of SCC growth on (1) temperature and (2) hardness in hydrogenated water at temperatures from 250degC to 340degC. And then, the SCC growth behaviors were compared between weld HAZ and CW stainless steels. The following results have been obtained. Significant SCC growth were observed in weld HAZ (SUS316 and SUS304) in hydrogenated water at 320degC. The SCC growth rates of the HAZ are similar to that of 10% CW non-sensitized SUS316, in accordance with that the hardness of weld HAZ is also similar to that of 10% CW SUS316. Temperature dependency of SCC growth of weld HAZ (SUS316 and SUS304) is also similar to that of 10% CW non-sensitized SUS316. That is, no significant SCC were observed in the weld HAZ (SUS316 and SUS304) in hydrogenated water at 340degC. This suggests that SCC growth behaviors of weld HAZ and CW stainless steels are similar and correlated with the hardness or yield strength of the materials, at least in non-sensitized regions. And the similar temperature dependence between the HAZ and CW stainless steels suggests that the SCC growth behaviors are also attributed to the common mechanism. (author)

  6. High-temperature hydrogen-air-steam detonation experiments in the BNL small-scale development apparatus

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsburg, T.; Boccio, J.; Economos, C.; Finfrock, C.; Gerlach, L.; Sato, K.; Kinoshita, M.

    1994-08-01

    The Small-Scale Development Apparatus (SSDA) was constructed to provide a preliminary set of experimental data to characterize the effect of temperature on the ability of hydrogen-air-steam mixtures to undergo detonations and, equally important, to support design of the larger scale High-Temperature Combustion Facility (HTCF) by providing a test bed for solution of a number of high-temperature design and operational problems. The SSDA, the central element of which is a 10-cm inside diameter, 6.1-m long tubular test vessel designed to permit detonation experiments at temperatures up to 700K, was employed to study self-sustained detonations in gaseous mixtures of hydrogen, air, and steam at temperatures between 300K and 650K at a fixed initial pressure of 0.1 MPa. Hydrogen-air mixtures with hydrogen composition from 9 to 60 percent by volume and steam fractions up to 35 percent by volume were studied for stoichiometric hydrogen-air-steam mixtures. Detonation cell size measurements provide clear evidence that the effect of hydrogen-air gas mixture temperature, in the range 300K-650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The hydrogen-air detonability limits for the 10-cm inside diameter SSDA test vessel, based upon the onset of single-head spin, decreased from 15 percent hydrogen at 300K down to between 9 and 10 percent hydrogen at 650K. The one-dimensional ZND model does a very good job at predicting the overall trends in the cell size data over the range of hydrogen-air-steam mixture compositions and temperature studied in the experiments

  7. Kinetics of the oxidation of hydrogen sulfite by hydrogen peroxide in aqueous solution:. ionic strength effects and temperature dependence

    Science.gov (United States)

    Maaß, Frank; Elias, Horst; Wannowius, Klaus J.

    Conductometry was used to study the kinetics of the oxidation of hydrogen sulfite, HSO -3, by hydrogen peroxide in aqueous non-buffered solution at the low concentration level of 10 -5-10 -6 M, typically found in cloud water. The kinetic data confirm that the rate law reported for the pH range 3-6 at higher concentration levels, rate= kH·[H +]·[HSO -3]·[H 2O 2], is valid at the low concentration level and at low ionic strength Ic. At 298 K and Ic=1.5×10 -4 M, third-order rate constant kH was found to be kH=(9.1±0.5)×10 7 M -2 s -1. The temperature dependence of kH led to an activation energy of Ea=29.7±0.9 kJ mol -1. The effect of the ionic strength (adjusted with NaCl) on rate constant kH was studied in the range Ic=2×10 -4-5.0 M at pH=4.5-5.2 by conductometry and stopped-flow spectrophotometry. The dependence of kH on Ic can be described with a semi-empirical relationship, which is useful for the purpose of comparison and extrapolation. The kinetic data obtained are critically compared with those reported earlier.

  8. Materials for high-temperature hydrogen fluorine environments. Final report, June 1976-December 1978

    International Nuclear Information System (INIS)

    Holcombe, C.E. Jr.; Kovach, L.

    1981-03-01

    A determination has been made of the stability of 35 materials under high-temperature, fluorine rich, hydrogen fluoride torch testing. Refractory materials tested included 4 borides, 3 carbides, 3 nitrides, 12 oxides, 1 oxynitride, 1 sulfide, 10 metals, and carbon (10 types). Three materials distinctly performed better than nickel: lanthanum hexaboride, calcium hexaboride, and lanthanum silicon oxynitride. Of these, lanthanum hexaboride is the best candidate tested since it has an estimated upper use temperature > 1726 K, which is above the melting point and more than 300 K above the upper use temperature of nickel

  9. Materials for high-temperature hydrogen fluorine environments. Final report, June 1976-December 1978

    Energy Technology Data Exchange (ETDEWEB)

    Holcombe, C.E. Jr.; Kovach, L.

    1981-03-01

    A determination has been made of the stability of 35 materials under high-temperature, fluorine rich, hydrogen fluoride torch testing. Refractory materials tested included 4 borides, 3 carbides, 3 nitrides, 12 oxides, 1 oxynitride, 1 sulfide, 10 metals, and carbon (10 types). Three materials distinctly performed better than nickel: lanthanum hexaboride, calcium hexaboride, and lanthanum silicon oxynitride. Of these, lanthanum hexaboride is the best candidate tested since it has an estimated upper use temperature > 1726 K, which is above the melting point and more than 300 K above the upper use temperature of nickel.

  10. Isolation of non-sulphur photosynthetic bacterial strains efficient in hydrogen production at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.P.; Srivastava, S.C. (Banaras Hindu Univ., Varanasi (IN). Centre of Advanced Study in Botany)

    1991-01-01

    Four strains of non-sulphur photosynthetic bacteria were isolated from root zone associations of aquatic plants like Azolla, Salvinia and Eichhornia, as well as the deep-water rice. Based on the gross cell morphology and pigmentation, the isolates resembled Rhodopseudomonas sp. and have been designated as BHU strains 1 to 4, respectively. When subjected to elevated temperature (from 33-45{sup o}C), substantial growth/hydrogen production could be observed only in strains 1 and 4. Strains 2 and 3 on the other hand, showed diminished growth and negligible hydrogen photoproduction. The BHU strains 1 and 4 have been selected as the most active (thermostable) hydrogen producing strains of local origin as far as the Indian tropical climate is concerned. (author).

  11. Experimental study of temperature sensor for an ocean-going liquid hydrogen (LH2) carrier

    Science.gov (United States)

    Nakano, A.; Shimazaki, T.; Sekiya, M.; Shiozawa, H.; Aoyagi, A.; Ohtsuka, K.; Iwakiri, T.; Mikami, Z.; Sato, M.; Kinoshita, K.; Matsuoka, T.; Takayama, Y.; Yamamoto, K.

    2018-04-01

    The prototype temperature sensors for an ocean-going liquid hydrogen (LH2) carrier were manufactured by way of trial. All of the sensors adopted Platinum 1000 (PT-1000) resistance thermometer elements. Various configurations of preproduction temperature sensors were tested in AIST's LH2 test facility. In the experiments, a PT-1000 resistance thermometer, calibrated at the National Metrology Institute of Japan at AIST, was used as the standard thermometer. The temperatures measured by the preproduction sensors were compared with the temperatures measured by the standard thermometer, and the measurement accuracy of the temperature sensors in LH2 was investigated and discussed. It was confirmed that the measurement accuracies of the preproduction temperature sensors were within ±50 mK, which is the required measurement accuracy for a technical demonstration ocean-going LH2 carrier.

  12. High Temperature Electrolysis for Hydrogen Production from Nuclear Energy – TechnologySummary

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots; J. S. Herring; M. G. McKellar; E. A. Harvego; M. S. Sohal; K. G. Condie

    2010-02-01

    The Department of Energy, Office of Nuclear Energy, has requested that a Hydrogen Technology Down-Selection be performed to identify the hydrogen production technology that has the best potential for timely commercial demonstration and for ultimate deployment with the Next Generation Nuclear Plant (NGNP). An Independent Review Team has been assembled to execute the down-selection. This report has been prepared to provide the members of the Independent Review Team with detailed background information on the High Temperature Electrolysis (HTE) process, hardware, and state of the art. The Idaho National Laboratory has been serving as the lead lab for HTE research and development under the Nuclear Hydrogen Initiative. The INL HTE program has included small-scale experiments, detailed computational modeling, system modeling, and technology demonstration. Aspects of all of these activities are included in this report. In terms of technology demonstration, the INL successfully completed a 1000-hour test of the HTE Integrated Laboratory Scale (ILS) technology demonstration experiment during the fall of 2008. The HTE ILS achieved a hydrogen production rate in excess of 5.7 Nm3/hr, with a power consumption of 18 kW. This hydrogen production rate is far larger than has been demonstrated by any of the thermochemical or hybrid processes to date.

  13. High Temperature Electrolysis for Hydrogen Production from Nuclear Energy - Technology Summary

    International Nuclear Information System (INIS)

    O'Brien, J.E.; Stoots, C.M.; Herring, J.S.; McKellar, M.G.; Harvego, E.A.; Sohal, M.S.; Condie, K.G.

    2010-01-01

    The Department of Energy, Office of Nuclear Energy, has requested that a Hydrogen Technology Down-Selection be performed to identify the hydrogen production technology that has the best potential for timely commercial demonstration and for ultimate deployment with the Next Generation Nuclear Plant (NGNP). An Independent Review Team has been assembled to execute the down-selection. This report has been prepared to provide the members of the Independent Review Team with detailed background information on the High Temperature Electrolysis (HTE) process, hardware, and state of the art. The Idaho National Laboratory has been serving as the lead lab for HTE research and development under the Nuclear Hydrogen Initiative. The INL HTE program has included small-scale experiments, detailed computational modeling, system modeling, and technology demonstration. Aspects of all of these activities are included in this report. In terms of technology demonstration, the INL successfully completed a 1000-hour test of the HTE Integrated Laboratory Scale (ILS) technology demonstration experiment during the fall of 2008. The HTE ILS achieved a hydrogen production rate in excess of 5.7 Nm3/hr, with a power consumption of 18 kW. This hydrogen production rate is far larger than has been demonstrated by any of the thermochemical or hybrid processes to date.

  14. Morphology, Microstructure, and Hydrogen Content of Carbon Nanostructures Obtained by PECVD at Various Temperatures

    Directory of Open Access Journals (Sweden)

    M. Acosta Gentoiu

    2017-01-01

    Full Text Available Carbon nanostructures were obtained by acetylene injection into an argon plasma jet in the presence of hydrogen. The samples were synthesized in similar conditions, except that the substrate deposition temperatures TD were varied, ranging from 473 to 973 K. A strong dependence of morphology, structure, and graphitization upon TD was found. We obtained vertical aligned carbon nanotubes (VA-CNTs at low temperatures as 473 K, amorphous carbon nanoparticles (CNPs at temperatures from about 573 to 673 K, and carbon nanowalls (CNWs at high temperatures from 773 to 973 K. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, elastic recoil detection analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to substantiate the differences in these material types. It is known that hydrogen concentration modifies strongly the properties of the materials. Different concentrations of hydrogen-bonded carbon could be identified in amorphous CNP, VA-CNT, and CNW. Also, the H : C ratios along depth were determined for the obtained materials.

  15. On the problem of safe usage of 12MKh steel at elevated temperatures and high hydrogen pressures

    International Nuclear Information System (INIS)

    Archakov, Yu.I.; Teslya, B.M.

    1982-01-01

    The behaviour of the 12MKh steel in hydrogen at pressures of 4-100 MPa and temperatures of 450-600 deg C has been investigated to study the regularities of hydrogen corrosion process. The samples are held in hydrogen under all-round compression in autoclaves with subsequent determination of mechanical properties, carbon content and microstructure. Dependencies of time to begining of intensive embrittlement under given conditions are found. The empiric equation for the calculation of time to beginning of hydrogen corrosion is derived, the safe usage of the 12MKh steel at different temperatures and pressures are determined

  16. Lithium doping on covalent organic framework-320 for enhancing hydrogen storage at ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Liangzhi, E-mail: 15004110853@163.com; Liu, Qing

    2016-12-15

    Density Functional Theory (DFT) combines with grand canonical Monte Carlo (GCMC) simulations are performed to explore the effect of Li doping on the hydrogen storage capability of COF-320. The results show that the interaction energy between the H{sub 2} and the Li-doped COF-320 is about three times higher than that of pristine COF-320. GCMC simulations are employed to study the hydrogen uptake of Li-doped COF-320 at ambient temperature, further confirm that the lithium doping can improve the hydrogen uptake at ambient temperature. Our results demonstrate that Li-doped COFs have good potential in the field of hydrogen storage. - Graphical abstract: Fig. 1. The optimized cluster model used here to represent the COF-320 and possible adsorption sites (A, B, C) for adsorption of metals in the COF-320. The dangling bonds are terminated by H atoms. C, H, and N atoms are shown as gray, white, and blue colors, respectively. Fig. 2. The adsorption isotherm of H{sub 2} in the pristine and Li-doped COF-320 at 298 K. - Highlights: • The binding sites of single and two lithium atoms in COF-320 were studied. • The interaction energy between the H{sub 2} and the Li-doped COF-320 is about three times higher than that of pristine COF-320. • H{sub 2} uptakes on the Li-doped COFs obtain significant improvement at ambient temperature. • Lithium-doping is a successful strategy for improving hydrogen uptake.

  17. Reinvestigation of the Henry's law constant for hydrogen peroxide with temperature and acidity variation.

    Science.gov (United States)

    Huang, Daoming; Chen, Zhongming

    2010-01-01

    Hydrogen peroxide is not only an important oxidant in itself; it also serves as both sink and temporary reservoir for other important oxidants including HOx (OH and HO2) radicals and O3 in the atmosphere. Its partitioning between gas and aqueous phases in the atmosphere, usually described by its Henry's law constant (K(H)), significantly influences its role in atmospheric processes. Large discrepancies between the K(H) values reported in previous work, however, have created uncertainty for atmospheric modelers. Based on our newly developed online instrumentation, we have re-determined the temperature and acidity dependence of K(H) for hydrogen peroxide at an air pressure of (0.960 +/- 0.013) atm (1 atm = 1.01325 x 10(5) Pa). The results indicated that the temperature dependence of K(H) for hydrogen peroxide fits to the Van't Hoff equation form, expressed as lnK(H) = a/T - b, and a = -deltaH/R, where K(H) is in M/atm (M is mol/L), T is in degrees Kelvin, R is the ideal gas constant, and deltaH is the standard heat of solution. For acidity dependence, results demonstrated that the K(H) value of hydrogen peroxide appeared to have no obvious dependence on decreasing pH level (from pH 7 to pH 1). Combining the dependence of both temperature and acidity, the obtained a and b were 7024 +/- 138 and 11.97 +/- 0.48, respectively, deltaH was (58.40 +/- 1.15) kJ/(K x mol), and the uncertainties represent sigma. Our determined K(H) values for hydrogen peroxide will therefore be of great use in atmospheric models.

  18. Effect of dissolved hydrogen on corrosion of 316NG stainless steel in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Lijin [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China); Peng, Qunjia, E-mail: qunjiapeng@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Shoji, Tetsuo [Frontier Research Initiative, New Industry Creation Hatchery Center, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Han, En-Hou; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Wang, Lei [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China)

    2015-12-15

    Highlights: • Dissolved hydrogen (DH) effect on corrosion of stainless steel in high temperature water. • Increasing DH caused decrease of Cr- but increase of Fe-concentrations in the inner oxide layer. • Concentration gradient of Cr and Fe in the inner oxide layer. • DH effect was attributed to the accelerated diffusion of Fe ion in the inner oxide layer. - Abstract: Characterizations of oxide films formed on 316 stainless steel in high temperature, hydrogenated water were conducted. The results show the oxide film consists of an outer layer with oxide particles of Fe–Ni spinel and hematite, and an inner continuous layer of Fe–Cr–Ni spinel. Increasing dissolved hydrogen (DH) concentrations causes decrease of Cr- and increase of Fe-concentrations in the inner layer. A continuous decrease of Cr- and increase of Fe-concentrations was observed from the surface of the inner layer to the oxide/substrate interface. The DH effect is attributed to the enhanced diffusion of Fe ions in the oxide film by hydrogen.

  19. System Evaluations and Life-Cycle Cost Analyses for High-Temperature Electrolysis Hydrogen Production Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Edwin A. Harvego; James E. O' Brien; Michael G. McKellar

    2012-05-01

    This report presents results of system evaluations and lifecycle cost analyses performed for several different commercial-scale high-temperature electrolysis (HTE) hydrogen production concepts. The concepts presented in this report rely on grid electricity and non-nuclear high-temperature process heat sources for the required energy inputs. The HYSYS process analysis software was used to evaluate both central plant designs for large-scale hydrogen production (50,000 kg/day or larger) and forecourt plant designs for distributed production and delivery at about 1,500 kg/day. The HYSYS software inherently ensures mass and energy balances across all components and it includes thermodynamic data for all chemical species. The optimized designs described in this report are based on analyses of process flow diagrams that included realistic representations of fluid conditions and component efficiencies and operating parameters for each of the HTE hydrogen production configurations analyzed. As with previous HTE system analyses performed at the INL, a custom electrolyzer model was incorporated into the overall process flow sheet. This electrolyzer model allows for the determination of the average Nernst potential, cell operating voltage, gas outlet temperatures, and electrolyzer efficiency for any specified inlet steam, hydrogen, and sweep-gas flow rates, current density, cell active area, and external heat loss or gain. The lifecycle cost analyses were performed using the H2A analysis methodology developed by the Department of Energy (DOE) Hydrogen Program. This methodology utilizes spreadsheet analysis tools that require detailed plant performance information (obtained from HYSYS), along with financial and cost information to calculate lifecycle costs. There are standard default sets of assumptions that the methodology uses to ensure consistency when comparing the cost of different production or plant design options. However, these assumptions may also be varied within the

  20. 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.

  1. Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma

    Science.gov (United States)

    Samuell, Cameron M.; Corr, Cormac S.

    2015-08-01

    Neutral gas temperatures in hydrogen plasmas are important for experimental and modelling efforts in fusion technology, plasma processing, and surface modification applications. To provide values relevant to these application areas, neutral gas temperatures were measured in a low pressure (radiofrequency helicon discharge using spectroscopic techniques. The atomic and molecular species were not found to be in thermal equilibrium with the atomic temperature being mostly larger then the molecular temperature. In low power operation (measurements near a graphite target demonstrated localised cooling near the sample surface. The temporal evolution of the molecular gas temperature during a high power 1.1 ms plasma pulse was also investigated and found to vary considerably as a function of pressure.

  2. Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J. Douglas [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical and Biological Engineering; Wolden, Colin A. [Colorado School of Mines, Golden, CO (United States)

    2013-09-30

    Colorado School of Mines (CSM) developed high temperature, hydrogen permeable membranes that contain no platinum group metals with the goal of separating hydrogen from gas mixtures representative of gasification of carbon feedstocks such as coal or biomass in order to meet DOE NETL 2015 hydrogen membrane performance targets. We employed a dual synthesis strategy centered on transition metal carbides. In the first approach, novel, high temperature, surface diffusion membranes based on nanoporous Mo2C were fabricated on ceramic supports. These were produced in a two step process that consisted of molybdenum oxide deposition followed by thermal carburization. Our best Mo2C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft2 at a feed pressure of only 20 psig. The highest H2/N2 selectivity obtained with this approach was 4.9. A transport model using “dusty gas” theory was derived to describe the hydrogen transport in the Mo2C coated, surface diffusion membranes. The second class of membranes developed were dense metal foils of BCC metals such as vanadium coated with thin (< 60 nm) Mo2C catalyst layers. We have fabricated a Mo2C/V composite membrane that in pure gas testing delivered a H2 flux of 238 SCFH/ft2 at 600 °C and 100 psig, with no detectable He permeance. This exceeds the 2010 DOE Target flux. This flux is 2.8 times that of pure Pd at the same membrane thickness and test conditions and over 79% of the 2015 flux target. In mixed gas testing we achieved a permeate purity of ≥99.99%, satisfying the permeate purity milestone, but the hydrogen permeance was low, ~0.2 SCFH/ft2.psi. However, during testing of a Mo2C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft2.psi was obtained which was stable during the entire test, meeting the permeance associated with

  3. Hydrogen production through high-temperature electrolysis in a solid oxide cell

    International Nuclear Information System (INIS)

    Herring, J.St.; Lessing, P.; O'Brien, J.E.; Stoots, C.; Hartvigsen, J.; Elangovan, S.

    2004-01-01

    An experimental research programme is being conducted by the INEEL and Ceramatec, Inc., to test the high-temperature, electrolytic production of hydrogen from steam using a solid oxide cell. The research team is designing and testing solid oxide cells for operation in the electrolysis mode, producing hydrogen rising a high-temperature heat and electrical energy. The high-temperature heat and the electrical power would be supplied simultaneously by a high-temperature nuclear reactor. Operation at high temperature reduces the electrical energy requirement for electrolysis and also increases the thermal efficiency of the power-generating cycle. The high-temperature electrolysis process will utilize heat from a specialized secondary loop carrying a steam/hydrogen mixture. It is expected that, through the combination of a high-temperature reactor and high-temperature electrolysis, the process will achieve an overall thermal conversion efficiency of 40 to 50%o while avoiding the challenging chemistry and corrosion issues associated with the thermochemical processes. Planar solid oxide cell technology is being utilised because it has the best potential for high efficiency due to minimized voltage and current losses. These losses also decrease with increasing temperature. Initial testing has determined the performance of single 'button' cells. Subsequent testing will investigate the performance of multiple-cell stacks operating in the electrolysis mode. Testing is being performed both at Ceramatec and at INEEL. The first cells to be tested were single cells based on existing materials and fabrication technology developed at Ceramatec for production of solid oxide fuel cells. These cells use a relatively thick (∼ 175 μm) electrolyte of yttria- or scandia-stabilised zirconia, with nickel-zirconia cermet anodes and strontium-doped lanthanum manganite cathodes. Additional custom cells with lanthanum gallate electrolyte have been developed and tested. Results to date have

  4. Influence of hydrogen and temperature on the mechanical behaviour in an austenitic stainless steel

    International Nuclear Information System (INIS)

    Lamani, Emil; Jouinot, Patrice

    2003-01-01

    The mechanical behaviour of an austenitic stainless steel has been studied in this work, by means of two techniques: disk pressure embrittlement test (French standard NF E 29-723) and special biaxial tensile test. Specimens for both techniques are embedded disks, loaded by a continuously increasing gas pressure until rupture. Tests have been performed at various temperatures, between 18 o C and 655 o C, with loading speeds from 0.06 to 7 MPa/min. Their main results have been recorded as relationships between gas pressure and specimen deflection until its burst or cracking. Other observations (fracture, microstructure, etc.) are performed to assess the structural evolution with the temperature. The influence of hydrogen is evaluated by the comparison of the rupture parameters of specimens tested similarly under helium and hydrogen. The embrittlement index, E.I is determined as the ratio of the rupture pressures under helium and hydrogen taking into account also the effects of the loading speed and the gas purity. It has been noticed that the mechanical behaviour of the steel is strongly influenced by the apparition of a second phase in the austenitic structure: the deformation induced martensite, α, which presence is identified by microscopic observations and X-ray diffraction. At room temperature, the steel presents a relatively high sensitivity to the hydrogen embrittlement (2.20 ≤ E.I ≤ 2.40), while, with the temperature increasing, together with the reduction of the martensitic transformation, it was observed a rapid diminution of this sensitivity. Obtained results allow to define the performance of this steel for thin walls applications, as it is the case of expansions bellows in the chemical industry. (Original)

  5. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    Czech Academy of Sciences Publication Activity Database

    Vesel, A.; Drenik, A.; Elersic, K.; Mozetič, M.; Kovač, J.; Gyergyek, T.; Stöckel, Jan; Varju, Jozef; Pánek, Radomír; Balat-Pichelin, M.

    2014-01-01

    Roč. 305, June (2014), s. 674-682 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : Inconel * Oxidation * High temperature * Oxygen plasma * Hydrogen plasma Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.711, year: 2014 https://www.sciencedirect.com/science/article/pii/S0169433214007119

  6. CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

    NARCIS (Netherlands)

    Westerhout, J.; Cardozo, N. J. L.; Rapp, J.; van Rooij, G. J.

    2009-01-01

    The CH A-X molecular band is measured upon seeding the hydrogen plasma in the linear plasma generator Pilot-PSI [electron temperature T-e=0.1-2.5 eV and electron density n(e)=(0.5-5) X 10(20) m(-3)] with methane. Calculated inverse photon efficiencies for these conditions range from 3 up to

  7. Heart Attack

    Science.gov (United States)

    ... properly causes your body's blood sugar levels to rise, increasing your risk of heart attack. Metabolic syndrome. This occurs when you have obesity, high blood pressure and high blood sugar. Having metabolic ...

  8. Heart Attack

    Science.gov (United States)

    ... family history of heart attack race – African Americans, Mexican Americans, Native Americans, and native Hawaiians are at ... Your doctor will prescribe the medicines that are right for you. If you have had a heart ...

  9. Study on introduction scenario of the high temperature gas-cooled reactor hydrogen cogeneration system (GTHTR300C). Part 1

    International Nuclear Information System (INIS)

    Nishihara, Tetsuo; Takeda, Tetsuaki

    2005-09-01

    Japan Atomic Energy Research Institute is carrying out the research and development of the high temperature gas-cooled reactor hydrogen cogeneration system (GTHTR300C) aiming at the practical use around 2030. Preconditions of GTHTR300C introduction are the increase of hydrogen demand and the needs of new nuclear power plants. In order to establish the introduction scenario, it should be clarified that the operational status of existing nuclear power plants, the introduction number of fuel cell vehicles as a main user of hydrogen and the capability of hydrogen supply by existing plants. In this report, estimation of the nuclear power plants that will be decommissioned with a high possibility by 2030 and selection of the model district where the GTHTR300C can be introduced as an alternative system are conducted. Then the hydrogen demand and the capability of hydrogen supply in this district are investigated and the hydrogen supply scenario in 2030 is considered. (author)

  10. Influence of hydrogen and test temperature on mechanical properties of vanadium and niobium

    International Nuclear Information System (INIS)

    Stoloff, N.S.; Ashok, S.; Xiao, P.

    1981-01-01

    The influence of hydrogen on fatigue life of niobium and vanadium is described. In tests carried out under stress control conditions on unnotched material hydrogen extends fatigue life of both metals. However, in stress controlled tests on notched bars and in strain control tests on unnotched bars hydrogen is detrimental to fatigue life. Hydrided alloys are much more sensitive to notches than are the unalloyed metals. Frequency effects on fatigue life also are much more severe in hydrided alloys, lower frequency leading to shorter life. The results of delayed failure, creep tests and elevated temperature fatigue tests also are reported. Niobium and vanadium reveal reduced fatigue lives at elevated temperatures for tests carried out in vacuum. The results of limited hold time and low frequency tests on strain controlled fatigue life also are reported. Increasing hold time increases fatigue life of niobium in the range 450 to 650 0 C. Fractographic features change from striations in unalloyed metals to cleavage in the hydrided alloys tested at room temperature

  11. Red soil as a regenerable sorbent for high temperature removal of hydrogen sulfide from coal gas

    International Nuclear Information System (INIS)

    Ko, T.-H.; Chu Hsin; Lin, H.-P.; Peng, C.-Y.

    2006-01-01

    In this study, hydrogen sulfide (H 2 S) was removed from coal gas by red soil under high temperature in a fixed-bed reactor. Red soil powders were collected from the northern, center and southern of Taiwan. They were characterized by XRPD, porosity analysis and DCB chemical analysis. Results show that the greater sulfur content of LP red soils is attributed to the higher free iron oxides and suitable sulfidation temperature is around 773 K. High temperature has a negative effect for use red soil as a desulfurization sorbent due to thermodynamic limitation in a reduction atmosphere. During 10 cycles of regeneration, after the first cycle the red soil remained stable with a breakthrough time between 31 and 36 min. Hydrogen adversely affects sulfidation reaction, whereas CO exhibits a positive effect due to a water-shift reaction. COS was formed during the sulfidation stage and this was attributed to the reaction of H 2 S and CO. Results of XRPD indicated that, hematite is the dominant active species in fresh red soil and iron sulfide (FeS) is a product of the reaction between hematite and hydrogen sulfide in red soils. The spinel phase FeAl 2 O 4 was found during regeneration, moreover, the amount of free iron oxides decreased after regeneration indicating the some of the free iron oxide formed a spinel phase, further reducting the overall desulfurization efficiency

  12. Effects of reducing temperatures on the hydrogen storage capacity of double-walled carbon nanotubes with Pd loading.

    Science.gov (United States)

    Sheng, Qu; Wu, Huimin; Wexler, David; Liu, Huakun

    2014-06-01

    The effects of different temperatures on the hydrogen sorption characteristics of double-walled carbon nanotubes (DWCNTs) with palladium loading have been investigated. When we use different temperatures, the particle sizes and specific surface areas of the samples are different, which affects the hydrogen storage capacity of the DWCNTs. In this work, the amount of hydrogen storage capacity was determined (by AMC Gas Reactor Controller) to be 1.70, 1.85, 2.00, and 1.93 wt% for pristine DWCNTS and for 2%Pd/DWCNTs-300 degrees C, 2%Pd/DWCNTs-400 degrees C, and 2%Pd/DWCNTs-500 degrees C, respectively. We found that the hydrogen storage capacity can be enhanced by loading with 2% Pd nanoparticles and selecting a suitable temperature. Furthermore, the sorption can be attributed to the chemical reaction between atomic hydrogen and the dangling bonds of the DWCNTs.

  13. 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.

  14. Influence of temperature on hydrogen production from bread mill wastewater by sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Tang, G.L.; Huang, J.; Li, Y.Y.; Sun, Z.J. [China Agricultural Univ., Beijing (China). College of Resources and Environmental Sciences; Tang, Q.Q. [Nanjing Univ., Nanjing (China). Medical School

    2008-07-01

    Hydrogen (H{sub 2}) energy has been touted as a sustainable and clean energy source that can solve environmental problems such as acid rain, greenhouse gases and transboundary pollution. While most hydrogen is currently produced from nonrenewable sources such as oil, natural gas, and coal, these processes are energy-intensive and costly. The biological production of hydrogen using fermentative bacteria is an environmentally friendly and energy-saving process which has recently attracted much attention as an effective way of converting biomass into H{sub 2}. Waste-based H{sub 2} production processes mainly include wastewater from paper mills, municipal solid waste, rice winery wastewater, and food wastewater from cafeterias. This study investigated the use of bread mill wastewater for biological production of hydrogen due to its high production potential. Annual bread production in China is estimated to be over 1.5 million tons, producing 10 m{sup 3} of wastewater per ton of bread. The wastewater has high chemical oxygen demand and carbohydrate concentrations and is therefore suitable for anaerobic treatment processes. This study evaluated the effect of temperature on H{sub 2} production from bread mill wastewater by sewage sludge in lab-scale experiments. H{sub 2} production, the distribution of volatile fatty acids and the lag-phase time were influenced by temperature. H{sub 2} production and H{sub 2} yield increased with increasing temperature. The optimal temperature for H{sub 2} production was 50 degrees C. Butyrate, acetate and alcohol were the main by-products of H{sub 2} fermentation. According to 16S rDNA analysis, the dominant microflora was Clostridium, but the microbial species varied with temperature. The activation energy for H{sub 2} production was estimated to be 92 kJ per mol for bread mill wastewater. It was concluded that bread mill wastewater could potentially serve as a substrate for H{sub 2} production. This research provides a means of

  15. Physical properties of Fe doped In_2O_3 magnetic semiconductor annealed in hydrogen at different temperature

    International Nuclear Information System (INIS)

    Baqiah, H.; Ibrahim, N.B.; Halim, S.A.; Chen, S.K.; Lim, K.P.; Kechik, M.M. Awang

    2016-01-01

    The effects of hydrogen-annealing at different temperatures (300, 400, 500 and 600 °C) on physical properties of In_2_−_xFe_xO_3 (x=0.025) thin film were investigated. The structural measurement using XRD shows that the film has a single In_2O_3 phase structure when annealed in hydrogen at 300–500 °C, however when annealed in hydrogen at 600 °C the film has a mixed phase structure of In_2O_3 and In phases. The electrical measurements show that the carrier concentrations of the films decrease with the increase of hydrogen-annealing temperature in the range 300–500 °C. The optical band gap of the films decreases with increasing hydrogen-annealing temperatures. The saturation magnetisation, Ms, and coercivity of films increase with the increment of hydrogen annealing temperature. The film annealed at 300 °C has the lowest resistivity, ρ=0.03 Ω cm, and the highest carrier concentrations, n=6.8×10"1"9 cm"−"3, while film annealed at 500 °C has both good electrical (ρ=0.05 Ω.cm and n=2.2×10"1"9 cm"−"3) and magnetic properties, Ms=21 emu/cm"-"3. - Highlights: • Physical properties of films were sensitive to hydrogen-annealing temperature. • Magnetisation, Ms, of films increased with increase of hydrogen annealing temperature. • Film annealed in hydrogen at 300 °C has the lowest resistivity, ρ=0.03 Ω cm. • Film annealed in hydrogen at 600 °C has highest magnetisation, Ms=30 emu/cm"3.

  16. Temperature oscillations in methanol partial oxidation reactor for the production of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinsu; Byeon, Jeonguk; Seo, Il Gyu; Lee, Hyun Chan; Kim, Dong Hyun; Lee, Jietae [Kyungpook National University, Daegu (Korea, Republic of)

    2013-04-15

    Methanol partial oxidation (POX) is a well-known reforming reaction for the production of hydrogen from methanol. Since POX is relatively fast and highly exothermic, this reforming method will be efficient for the fast start-up and load-following operation. However, POX generates hot spots around catalyst and even oscillations in the reactor temperature. These should be relieved for longer operations of the reactor without catalyst degradations. For this, temperature oscillations in a POX reactor are investigated experimentally. Various patterns of temperature oscillations according to feed flow rates of reactants and reactor temperatures are obtained. The bifurcation phenomena from regular oscillations to chaotic oscillations are found as the methanol flow rate increases. These experimental results can be used for theoretical analyses of oscillations and for designing safe reforming reactors.

  17. Temperature oscillations in methanol partial oxidation reactor for the production of hydrogen

    International Nuclear Information System (INIS)

    Kim, Jinsu; Byeon, Jeonguk; Seo, Il Gyu; Lee, Hyun Chan; Kim, Dong Hyun; Lee, Jietae

    2013-01-01

    Methanol partial oxidation (POX) is a well-known reforming reaction for the production of hydrogen from methanol. Since POX is relatively fast and highly exothermic, this reforming method will be efficient for the fast start-up and load-following operation. However, POX generates hot spots around catalyst and even oscillations in the reactor temperature. These should be relieved for longer operations of the reactor without catalyst degradations. For this, temperature oscillations in a POX reactor are investigated experimentally. Various patterns of temperature oscillations according to feed flow rates of reactants and reactor temperatures are obtained. The bifurcation phenomena from regular oscillations to chaotic oscillations are found as the methanol flow rate increases. These experimental results can be used for theoretical analyses of oscillations and for designing safe reforming reactors

  18. Effect of water electrolysis temperature of hydrogen production system using direct coupling photovoltaic and water electrolyzer

    Directory of Open Access Journals (Sweden)

    Tetsuhiko Maeda

    2016-01-01

    Full Text Available We propose control methods of a photovoltaic (PV-water electrolyzer (ELY system that generates hydrogen by controlling the number of ELY cells. The advantage of this direct coupling between PV and ELY is that the power loss of DC/DC converter is avoided. In this study, a total of 15 ELY cells are used. In the previous researches, the electrolyzer temperature was constantly controlled with a thermostat. Actually, the electrolyzer temperature is decided by the balance of the electrolysis loss and the heat loss to the outside. Here, the method to control the number of ELY cells was investigated. Maximum Power Point Tracking efficiency of more than 96% was achieved without ELY temperature control. Furthermore we construct a numerical model taking into account of ELY temperature. Using this model, we performed a numerical simulation of 1-year. Experimental data and the simulation results shows the validity of the proposed control method.

  19. Hydrogen production at <550 C using a low temperature thermochemical cycle

    International Nuclear Information System (INIS)

    Lewis, M.A.; Serban, M.; Basco, J.K.

    2004-01-01

    A Department of Energy goal is to identify new technologies for producing hydrogen cost effectively without greenhouse gas emissions. Thermochemical cycles are one of the potential options under investigation. Thermochemical cycles consist of a series of reactions in which water is thermally decomposed and all other chemicals are recycled. Only heat and water are consumed. However, most thermochemical cycles require process heat at temperatures of 850-900 deg C. Argonne National Laboratory is developing low temperature cycles designed for lower temperature heat, 500-550 deg C, which is more readily available. For this temperature region, copper-chlorine (Cu-Cl) cycles are the most promising cycle. Several Cu-Cl cycles have been examined in the laboratory and the most promising cycle has been identified. Proof-of-principle experiments are nearly complete. A preliminary assessment of cycle efficiency is promising. Details of the experiments and efficiency calculations are discussed. (author)

  20. Metalized T graphene: A reversible hydrogen storage material at room temperature

    International Nuclear Information System (INIS)

    Ye, Xiao-Juan; Zhong, Wei; Du, You-Wei; Liu, Chun-Sheng; Zeng, Zhi

    2014-01-01

    Lithium (Li)-decorated graphene is a promising hydrogen storage medium due to its high capacity. However, homogeneous mono-layer coating graphene with lithium atoms is metastable and the lithium atoms would cluster on the surface, resulting in the poor reversibility. Using van der Waals-corrected density functional theory, we demonstrated that lithium atoms can be homogeneously dispersed on T graphene due to a nonuniform charge distribution in T graphene and strong hybridizations between the C-2p and Li-2p orbitals. Thus, Li atoms are not likely to form clusters, indicating a good reversible hydrogen storage. Both the polarization mechanism and the orbital hybridizations contribute to the adsorption of hydrogen molecules (storage capacity of 7.7 wt. %) with an optimal adsorption energy of 0.19 eV/H 2 . The adsorption/desorption of H 2 at ambient temperature and pressure is also discussed. Our results can serve as a guide in the design of new hydrogen storage materials based on non-hexagonal graphenes.

  1. The influence of column temperature on the hydrogen isotopes separation performance of FDC

    International Nuclear Information System (INIS)

    Deng Xiaojun; Luo Deli; Qin Cheng; Yang Wan; Huang Guoqiang; Huang Zhiyong

    2014-01-01

    Frontal displacement chromatography (FDC) is a promising method for hydrogen isotopes separation with obvious advantages such as simple operation process, low tritium retention in system and easy to scale up, etc. We designed and constructed a FDC device using Pd-Al 2 O 3 as separation material in previous study, and the feasibility of FDC for hydrogen isotopes separation was confirmed. On the basis of the results, a series of experiments at different column temperatures were carried out to investigate the temperature influence to the separation performance, with the composition of (5 ± 0.1)% H 2 -(5 ± 0.1)% D 2 -(90 ± 0.1)% Ar of feed gas. Experiments were carried out at the temperature of 303K, 273K, 263K, 253K, 213K, at the gas flow rate of 15 mL (NTP)/min. The results indicated that lower temperature, higher enrichment factor while the feed gas composition and the gas flow rate are definite; lower temperature, shorter 'separation transition state', and then better separation efficiency. The deuterium enrichment factor became 65 from l.5 while the temperature decreased to 273K from 303K. It also showed that the deuterium recovery ratio and the deuterium abundance of product gas increases with the temperature decrease except for the case of 303K. At the temperature of 273K and below, the deuterium recovery ratio were all higher than 42%, deuterium abundance of product were all larger than 98%, and the maximum of deuterium abundance at 213K was 99.8%. (authors)

  2. System Evaluation and Economic Analysis of a Nuclear Reactor Powered High-Temperature Electrolysis Hydrogen-Production Plant

    International Nuclear Information System (INIS)

    Harvego, E.A.; McKellar, M.G.; Sohal, M.S.; O'Brien, J.E.; Herring, J.S.

    2010-01-01

    A reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production was developed to provide a basis for comparing the HTE concept with other hydrogen production concepts. The reference plant design is driven by a high-temperature helium-cooled nuclear reactor coupled to a direct Brayton power cycle. The reference design reactor power is 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 540 C and 900 C, respectively. The electrolysis unit used to produce hydrogen includes 4,009,177 cells with a per-cell active area of 225 cm2. The optimized design for the reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes an air-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The inlet air for the air-sweep system is compressed to the system operating pressure of 5.0 MPa in a four-stage compressor with intercooling. The alternating current (AC) to direct current (DC) conversion efficiency is 96%. The overall system thermal-to-hydrogen production efficiency (based on the lower heating value of the produced hydrogen) is 47.1% at a hydrogen production rate of 2.356 kg/s. An economic analysis of this plant was performed using the standardized H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program, and using realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost. A cost of $3.23/kg of hydrogen was calculated assuming an internal rate of return of 10%.

  3. Modification of the properties of Pt-Al/sub 2/O/sub 3/ catalysts by hydrogen at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Menon, P.G.; Froment, G.F.

    1979-08-01

    Pulse reactor studies were performed on the hydrogenolysis of n-pentane and n-hexane at 400/sup 0/C on two commercial reforming catalysts that contained 0.6 and 0.75% platinum on alumina, respectively, and which were calcined in air at 500/sup 0/C, followed by hydrogen-reduction at 400/sup 0/-600/sup 0/C. On catalysts reduced at 400/sup 0/C, hydrogenolysis was the main reaction; with increasing reducing temperature, hydrogenolysis was suppressed and isomerization selectivity increased; at 550/sup 0/C pretreatment temperature, hydrogenolysis was near zero. This selective catalyst deactivation was reversed by oxidizing the catalyst in air at 500/sup 0/C in a similar manner as previously found for sulfided and chlorided catalysts. Temperature-programed desorption of hydrogen adsorbed at 20/sup 0/-600/sup 0/C revealed that the higher the adsorption temperature, the higher the temperature of the hydrogen desorption peaks: the hydrogen adsorbed below 400/sup 0/C desorbed mainly at 50/sup 0/-300/sup 0/C, but the hydrogen adsorbed at higher temperatures desorbed at 300/sup 0/-500/sup 0/C. Apparently, two types of hydrogen adsorb in the two temperature regions, of which the more strongly adsorbed type inhibits hydrogenolysis but not isomerization.

  4. Quantum rotation and translation of hydrogen molecules encapsulated inside C₆₀: temperature dependence of inelastic neutron scattering spectra.

    Science.gov (United States)

    Horsewill, A J; Goh, K; Rols, S; Ollivier, J; Johnson, M R; Levitt, M H; Carravetta, M; Mamone, S; Murata, Y; Chen, J Y-C; Johnson, J A; Lei, X; Turro, N J

    2013-09-13

    The quantum dynamics of a hydrogen molecule encapsulated inside the cage of a C60 fullerene molecule is investigated using inelastic neutron scattering (INS). The emphasis is on the temperature dependence of the INS spectra which were recorded using time-of-flight spectrometers. The hydrogen endofullerene system is highly quantum mechanical, exhibiting both translational and rotational quantization. The profound influence of the Pauli exclusion principle is revealed through nuclear spin isomerism. INS is shown to be exceptionally able to drive transitions between ortho-hydrogen and para-hydrogen which are spin-forbidden to photon spectroscopies. Spectra in the temperature range 1.6≤T≤280 K are presented, and examples are given which demonstrate how the temperature dependence of the INS peak amplitudes can provide an effective tool for assigning the transitions. It is also shown in a preliminary investigation how the temperature dependence may conceivably be used to probe crystal field effects and inter-fullerene interactions.

  5. Linear and nonlinear optical properties of multilayered spherical quantum dots: Effects of geometrical size, hydrogenic impurity, hydrostatic pressure and temperature

    International Nuclear Information System (INIS)

    Karimi, M.J.; Rezaei, G.; Nazari, M.

    2014-01-01

    Based on the effective mass and parabolic one band approximations, simultaneous effects of the geometrical size, hydrogenic impurity, hydrostatic pressure, and temperature on the intersubband optical absorption coefficients and refractive index changes in multilayered spherical quantum dots are studied. Energy eigenvalues and eigenvectors are calculated using the fourth-order Runge–Kutta method and optical properties are obtained using the compact density matrix approach. The results indicate that the hydrogenic impurity, hydrostatic pressure, temperature and geometrical parameters such as the well and barrier widths have a great influence on the linear, the third-order nonlinear and the total optical absorption coefficients and refractive index changes. -- Highlights: • Hydrogenic impurity effects on the optical properties of a MSQD are investigated. • Hydrostatic pressure and temperature effects are also studied. • Hydrogenic impurity has a great influence on the linear and nonlinear ACs and RICs. • Hydrostatic pressure and temperature change the linear and nonlinear ACs and RICs

  6. Hydrogen Reduction of Hematite Ore Fines to Magnetite Ore Fines at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Wenguang Du

    2017-01-01

    Full Text Available Surplus coke oven gases (COGs and low grade hematite ores are abundant in Shanxi, China. Our group proposes a new process that could simultaneously enrich CH4 from COG and produce separated magnetite from low grade hematite. In this work, low-temperature hydrogen reduction of hematite ore fines was performed in a fixed-bed reactor with a stirring apparatus, and a laboratory Davis magnetic tube was used for the magnetic separation of the resulting magnetite ore fines. The properties of the raw hematite ore, reduced products, and magnetic concentrate were analyzed and characterized by a chemical analysis method, X-ray diffraction, optical microscopy, and scanning electron microscopy. The experimental results indicated that, at temperatures lower than 400°C, the rate of reduction of the hematite ore fines was controlled by the interfacial reaction on the core surface. However, at temperatures higher than 450°C, the reaction was controlled by product layer diffusion. With increasing reduction temperature, the average utilization of hydrogen initially increased and tended to a constant value thereafter. The conversion of Fe2O3 in the hematite ore played an important role in the total iron recovery and grade of the concentrate. The grade of the concentrate decreased, whereas the total iron recovery increased with the increasing Fe2O3 conversion.

  7. Effects of impurities on hydrogen permeability through palladium alloy membrane at comparatively high pressure and temperature

    International Nuclear Information System (INIS)

    Yoshida, Hiroshi; Konishi, Satoshi; Katsuta, Hiroji; Naruse, Yuji

    1982-02-01

    Palladium alloy membrane method is considered to be a useful technique for fusion reactor fuel purification process. To study the feasibility of this method, the effects of impurities on permeation characteristics of palladium alloy membrane were examined. Experiments were carried out at practical conditions: pressure; 120 - 1200 kPa, temperature; about 700 K. No poisoning effect on hydrogen permeability of commercial Pd-Ag (Au.Ru) alloy was observed for impurities such as NH 3 , CH 4 , CO, CO 2 , O 2 and N 2 , which were mixed with hyper-pure H 2 at low concentration level (10 - 10000 ppm). Deterioration occurred by contamination with oil vapor. However, regeneration of the membrane was easily performed by air baking followed by hydrogen reduction. Chemical reactions in the permeation cell were also examined. (author)

  8. Porous Silicon Hydrogen Sensor at Room Temperature: The Effect of Surface Modification and Noble Metal Contacts

    Directory of Open Access Journals (Sweden)

    Jayita KANUNGO

    2009-04-01

    Full Text Available Porous silicon (PS was fabricated by anodization of p-type crystalline silicon of resistivity 2-5 Ω cm. After formation, the PS surface was modified by the solution containing noble metal like Pd. Pd-Ag catalytic contact electrodes were deposited on porous silicon and on p-Silicon to fabricate Pd-Ag/PS/p-Si/Pd-Ag sensor structure to carry out the hydrogen sensing experiments. The Sensor was exposed to 1% hydrogen in nitrogen as carrier gas at room temperature (270C. Pd modified sensor showed minimum fluctuations and consistent performance with 86% response, response time and recovery time of 24 sec and 264 sec respectively. The stability experiments were studied for both unmodified and Pd modified sensor structures for a period of about 24 hours and the modified sensors showed excellent durability with no drift in response behavior.

  9. High-temperature hydrogen-air-steam detonation experiments in the BNL small-scale development apparatus

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsberg, T.; Boccio, J.; Economos, C.; Finfrock, C.; Gerlach, L.; Sato, K.

    1994-01-01

    The Small-Scale Development Apparatus (SSDA) was constructed to provide a preliminary set of experimental data to characterize the effect of temperature on the ability of hydrogen-air-steam-mixtures to undergo detonations and, equally important, to support design of the larger-scale High-Temperature Combustion Facility (HTCF) by providing a test bed for solution of a number of high-temperature design and operational problems. The SSDA, the central element of which is 10-cm inside diameter, 6.1-m long tubular test vessel designed to permit detonation experiments at temperatures up to 700K, was employed to study self-sustained detonations in gaseous mixtures of hydrogen, air, and steam at temperature between 300K and 650K at a fixed pressure of 0.1 MPa. Detonation cell size measurements provide clear evidence that the effect of hydrogen-air gas mixture temperature, in the range 300K to 650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The one-dimensional ZND model does a very good job at predicting the overall trends in the cell size data over the range of hydrogen-air-steam mixture compositions and temperature studied in the experiments. Experiments were conducted to measure the rate of hydrogen oxidation in the absence of ignition sources at temperatures of 500K and 650K, for hydrogen-air mixtures of 15% and 50%, and for a mixture of equimolar hydrogen-air and 30% steam at 650K. The rate of hydrogen oxidation was found to be significant at 650K. Reduction of hydrogen concentration by chemical reaction from 50 to 44% hydrogen, and from 15 to 11% hydrogen, were observed on a time frame of minutes. The DeSoete rate equation predicts the 50% experiment very well, but greatly underestimates the reaction rate of the lean mixtures

  10. Hydrogen production by high-temperature gas-cooled reactor. Conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system

    International Nuclear Information System (INIS)

    Sakaba, Nariaki; Ohashi, Hirofumi; Sato, Hiroyuki; Hara, Teruo; Kato, Ryoma; Kunitomi, Kazuhiko

    2008-01-01

    Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands a massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine sulphur (IS) process.The heat of 10 MWth at approximately 900degC, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. In this paper, we describe the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed. This involves the integration of three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer, and process heat exchanger. A new mixer-settler type of Bunsen reactor is also designed. This integrates three separate functions of Bunsen reactor, phase separator, and pump. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Alastuey, A. [Laboratoire de Physique, ENS Lyon, CNRS, Lyon (France); Ballenegger, V. [Institut UTINAM, Universite de Franche-Comte, CNRS, Besancon (France)

    2010-01-15

    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.ve leading corrections to the ideal Saha equation of state have been derived[A. Alastuey, V. Ballenegger et al., J. Stat. Phys. 130, 1119 (2008)]. Those corrections account for all effects of interactions and thermal excitations up to order exp(E{sub H} /kT) included, where E{sub H} {approx_equal} -13.6 eV is the ground state energy of the hydrogen atom. Among the.ve leading corrections, three are easy to evaluate, while the remaining ones involve suitably truncated internal partition functions of H{sub 2} molecules and H{sup -} and H{sub 2}{sup +} ions, for which no analytical formulae are available in closed form. We estimate those partitions functions at.nite temperature via a simple phenomenology based on known values of rotational and vibrational energies. This allows us to compute numerically the leading deviations to the Saha pressure along several isotherms and isochores. Our values are compared with those of the OPAL tables (for pure hydrogen) calculated within the ACTEX method (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The Advanced High-Temperature Reactor (AHTR) for Producing Hydrogen to Manufacture Liquid Fuels

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Peterson, P.F.; Ott, L.

    2004-01-01

    Conventional world oil production is expected to peak within a decade. Shortfalls in production of liquid fuels (gasoline, diesel, and jet fuel) from conventional oil sources are expected to be offset by increased production of fuels from heavy oils and tar sands that are primarily located in the Western Hemisphere (Canada, Venezuela, the United States, and Mexico). Simultaneously, there is a renewed interest in liquid fuels from biomass, such as alcohol; but, biomass production requires fertilizer. Massive quantities of hydrogen (H2) are required (1) to convert heavy oils and tar sands to liquid fuels and (2) to produce fertilizer for production of biomass that can be converted to liquid fuels. If these liquid fuels are to be used while simultaneously minimizing greenhouse emissions, nonfossil methods for the production of H2 are required. Nuclear energy can be used to produce H2. The most efficient methods to produce H2 from nuclear energy involve thermochemical cycles in which high-temperature heat (700 to 850 C) and water are converted to H2 and oxygen. The peak nuclear reactor fuel and coolant temperatures must be significantly higher than the chemical process temperatures to transport heat from the reactor core to an intermediate heat transfer loop and from the intermediate heat transfer loop to the chemical plant. The reactor temperatures required for H2 production are at the limits of practical engineering materials. A new high-temperature reactor concept is being developed for H2 and electricity production: the Advanced High-Temperature Reactor (AHTR). The fuel is a graphite-matrix, coated-particle fuel, the same type that is used in modular high-temperature gas-cooled reactors (MHTGRs). The coolant is a clean molten fluoride salt with a boiling point near 1400 C. The use of a liquid coolant, rather than helium, reduces peak reactor fuel and coolant temperatures 100 to 200 C relative to those of a MHTGR. Liquids are better heat transfer fluids than gases

  13. Synergistic effect of helium and hydrogen for bubble swelling in reduced-activation ferritic/martensitic steel under sequential helium and hydrogen irradiation at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Wenhui [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Guo, Liping, E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Chen, Jihong; Luo, Fengfeng; Li, Tiecheng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Ren, Yaoyao [Center for Electron Microscopy, Wuhan University, Wuhan 430072 (China); Suo, Jinping; Yang, Feng [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-04-15

    Highlights: • Helium/hydrogen synergistic effect can increase irradiation swelling of RAFM steel. • Hydrogen can be trapped to the outer surface of helium bubbles. • Too large a helium bubble can become movable. • Point defects would become mobile and annihilate at dislocations at high temperature. • The peak swelling temperature for RAFM steel is 450 °C. - Abstract: In order to investigate the synergistic effect of helium and hydrogen on swelling in reduced-activation ferritic/martensitic (RAFM) steel, specimens were separately irradiated by single He{sup +} beam and sequential He{sup +} and H{sup +} beams at different temperatures from 250 to 650 °C. Transmission electron microscope observation showed that implantation of hydrogen into the specimens pre-irradiated by helium can result in obvious enhancement of bubble size and swelling rate which can be regarded as a consequence of hydrogen being trapped by helium bubbles. But when temperature increased, Ostwald ripening mechanism would become dominant, besides, too large a bubble could become mobile and swallow many tiny bubbles on their way moving, reducing bubble number density. And these effects were most remarkable at 450 °C which was the peak bubble swelling temperature for RAMF steel. When temperature was high enough, say above 450, point defects would become mobile and annihilate at dislocations or surface. As a consequence, helium could no longer effectively diffuse and clustering in materials and bubble formation was suppressed. When temperature was above 500, helium bubbles would become unstable and decompose or migrate out of surface. Finally no bubble was observed at 650 °C.

  14. Synergistic effect of helium and hydrogen for bubble swelling in reduced-activation ferritic/martensitic steel under sequential helium and hydrogen irradiation at different temperatures

    International Nuclear Information System (INIS)

    Hu, Wenhui; Guo, Liping; Chen, Jihong; Luo, Fengfeng; Li, Tiecheng; Ren, Yaoyao; Suo, Jinping; Yang, Feng

    2014-01-01

    Highlights: • Helium/hydrogen synergistic effect can increase irradiation swelling of RAFM steel. • Hydrogen can be trapped to the outer surface of helium bubbles. • Too large a helium bubble can become movable. • Point defects would become mobile and annihilate at dislocations at high temperature. • The peak swelling temperature for RAFM steel is 450 °C. - Abstract: In order to investigate the synergistic effect of helium and hydrogen on swelling in reduced-activation ferritic/martensitic (RAFM) steel, specimens were separately irradiated by single He + beam and sequential He + and H + beams at different temperatures from 250 to 650 °C. Transmission electron microscope observation showed that implantation of hydrogen into the specimens pre-irradiated by helium can result in obvious enhancement of bubble size and swelling rate which can be regarded as a consequence of hydrogen being trapped by helium bubbles. But when temperature increased, Ostwald ripening mechanism would become dominant, besides, too large a bubble could become mobile and swallow many tiny bubbles on their way moving, reducing bubble number density. And these effects were most remarkable at 450 °C which was the peak bubble swelling temperature for RAMF steel. When temperature was high enough, say above 450, point defects would become mobile and annihilate at dislocations or surface. As a consequence, helium could no longer effectively diffuse and clustering in materials and bubble formation was suppressed. When temperature was above 500, helium bubbles would become unstable and decompose or migrate out of surface. Finally no bubble was observed at 650 °C

  15. Early evaluation of hydrogen isotopes separation by V4Cr4Ti-based sorbents at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kulsartov, Timur, E-mail: tima@physics.kz [Institute of Experimental and Theoretical Physics of Kazakh National University, 050038 Almaty (Kazakhstan); Institute of Atomic Energy of National Nuclear Center, 071100 Kurchatov (Kazakhstan); Shestakov, Vladimir; Chikhray, Yevgen; Kenzhina, Inesh; Askerbekov, Saulet [Institute of Experimental and Theoretical Physics of Kazakh National University, 050038 Almaty (Kazakhstan); Gordienko, Yuriy; Ponkratov, Yuriy; Zaurbekova, Zhanna [Institute of Atomic Energy of National Nuclear Center, 071100 Kurchatov (Kazakhstan)

    2016-12-15

    This paper presents the results of experiments on hydrogen isotopes sorption with V4Cr4Ti vanadium alloys from a mixture of hydrogen isotopes. The studies were carried out at temperatures of 353 K, 393 K, 423 K; and pressures of 10{sup 3}–10{sup 4} Pa in gas mixture of hydrogen isotopes. The α-phase domain of V-H (D) system was studied, where the concentration of hydrogen isotopes atoms should not exceed 0.015H (D) atoms per metal atom. The separation parameters were derived for several saturation conditions accordingly to registered time dependences of hydrogen isotopes partial pressure drop. The conclusion was made about the prospects of using vanadium alloys in hydrogen isotopes separation and purification systems.

  16. Influence of dissolved hydrogen and temperature on primary water stress corrosion cracking of mill annealed alloy 600

    Energy Technology Data Exchange (ETDEWEB)

    Totsuka, Nobuo; Nishikawa, Yoshito [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan); Nakajima, Nobuo

    2002-09-01

    The influence of dissolved hydrogen and temperature on primary water stress corrosion cracking (PWSCC) of alloy 600 was experimentally studied at temperature ranging from 310 to 360degC and hydrogen contents ranging from 0 to 4 ppm using slow strain rate tensile technique (SSRT) and constant load tensile test. As a result, it was revealed that the PWSCC susceptibility of alloy 600 has a maximum near 3 ppm of dissolved hydrogen at 360degC and the peak shifts to 1 ppm at 320degC. The mechanism of the peak shift is not clear yet, however, it is possibly explained by the change of absorbed hydrogen in the metal caused by the change of hydrogen recombination reaction and/or change of the surface film. (author)

  17. Reducibility of ceria-lanthana mixed oxides under temperature programmed hydrogen and inert gas flow conditions

    International Nuclear Information System (INIS)

    Bernal, S.; Blanco, G.; Cifredo, G.; Perez-Omil, J.A.; Pintado, J.M.; Rodriguez-Izquierdo, J.M.

    1997-01-01

    The present paper deals with the preparation and characterization of La/Ce mixed oxides, with La molar contents of 20, 36 and 57%. We carry out the study of the structural, textural and redox properties of the mixed oxides, comparing our results with those for pure ceria. For this aim we use temperature programmed reduction (TPR), temperature programmed desorption (TPD), nitrogen physisorption at 77 K, X-ray diffraction and high resolution electron microscopy. The mixed oxides are more easy to reduce in a flow of hydrogen than ceria. Moreover, in an inert gas flow they release oxygen in higher amounts and at lower temperatures than pure CeO 2 . The textural stability of the mixed oxides is also improved by incorporation of lanthana. All these properties make the ceria-lanthana mixed oxides interesting alternative candidates to substitute ceria in three-way catalyst formulations. (orig.)

  18. Hydrogen content, interfacial exchange and hydrogen diffusion in high-temperature protonic conductors based on strontium and barium cerates

    International Nuclear Information System (INIS)

    Vdovin, G.K.; Kurumchin, Eh.Kh.

    2004-01-01

    The hydrogen content and kinetics of the hydrogen exchange in the barium and strontium doped cerates are studied in the reduction atmosphere through the methods of isotope counterbalancing and isotope exchange. The measurements are carried out at 500-840 Deg C and hydrogen pressure of 2.7-16 gPa. It is established, that the hydrogen interfacial exchange proceeds at high velocities through the dissociative-type mechanisms. The effective activation energy of the hydrogen heteroexchange is determined. The coefficient of the hydrogen diffusion in BaCe 0.95 Nd 0.5 O 3-δ is calculated. The hydrogen content per formula unit constituted (0.48±0.05) in the SrCe 0.95 Y 0.05 O 3-δ and (0.60±0.05) in the BaCe 0.95 Nd 0.5 O 3-δ at 550 and 720 Deg C correspondingly and hydrogen pressure of 6.7 gPa [ru

  19. Low temperature removal of surface oxides and hydrocarbons from Ge(100) using atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Walker, M., E-mail: m.walker@warwick.ac.uk; Tedder, M.S.; Palmer, J.D.; Mudd, J.J.; McConville, C.F.

    2016-08-30

    Highlights: • Preparation of a clean, well-ordered Ge(100) surface with atomic hydrogen. • Surface oxide layers removed by AHC at room temperature, but not hydrocarbons. • Increasing surface temperature during AHC dramatically improves efficiency. • AHC with the surface heated to 250 °C led to a near complete removal of contaminants. • (2 × 1) LEED pattern from IBA and AHC indicates asymmetric dimer reconstruction. - Abstract: Germanium is a group IV semiconductor with many current and potential applications in the modern semiconductor industry. Key to expanding the use of Ge is a reliable method for the removal of surface contamination, including oxides which are naturally formed during the exposure of Ge thin films to atmospheric conditions. A process for achieving this task at lower temperatures would be highly advantageous, where the underlying device architecture will not diffuse through the Ge film while also avoiding electronic damage induced by ion irradiation. Atomic hydrogen cleaning (AHC) offers a low-temperature, damage-free alternative to the common ion bombardment and annealing (IBA) technique which is widely employed. In this work, we demonstrate with X-ray photoelectron spectroscopy (XPS) that the AHC method is effective in removing surface oxides and hydrocarbons, yielding an almost completely clean surface when the AHC is conducted at a temperature of 250 °C. We compare the post-AHC cleanliness and (2 × 1) low energy electron diffraction (LEED) pattern to that obtained via IBA, where the sample is annealed at 600 °C. We also demonstrate that the combination of a sample temperature of 250 °C and atomic H dosing is required to clean the surface. Lower temperatures prove less effective in removal of the oxide layer and hydrocarbons, whilst annealing in ultra-high vacuum conditions only removes weakly bound hydrocarbons. Finally, we examine the subsequent H-termination of an IBA-cleaned sample using XPS, LEED and ultraviolet

  20. Experimental and Numerical Study of Low Temperature Methane Steam Reforming for Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Martin Khzouz

    2017-12-01

    Full Text Available Low temperature methane steam reforming for hydrogen production, using experimental developed Ni/Al2O3 catalysts is studied both experimentally and numerically. The catalytic activity measurements were performed at a temperature range of 500–700 °C with steam to carbon ratio (S/C of 2 and 3 under atmospheric pressure conditions. A mathematical analysis to evaluate the reaction feasibility at all different conditions that have been applied by using chemical equilibrium with applications (CEA software and in addition, a mathematical model focused on the kinetics and the thermodynamics of the reforming reaction is introduced and applied using a commercial finite element analysis software (COMSOL Multiphysics 5.0. The experimental results were employed to validate the extracted simulation data based on the yields of the produced H2, CO2 and CO at different temperatures. A maximum hydrogen yield of 2.7 mol/mol-CH4 is achieved at 700 °C and S/C of 2 and 3. The stability of the 10%Ni/Al2O3 catalyst shows that the catalyst is prone to deactivation as supported by Thermogravimetric Analysis TGA results.

  1. On the solubility of hydrogen in the systems titanium-aluminium-hydrogen, titanium-vanadium-hydrogen and titanium-aluminium-vanadium-hydrogen in the temperature region of 800 to 1,0000C at hydrogen pressures of 0.1 to 400 mm.Hg

    International Nuclear Information System (INIS)

    Kauder, G.W.

    1973-01-01

    The hydrogen concentrations on Ti-Al, Ti-V and Ti-Al-V alloys were determined in the temperature region from 800 to 1,000 0 C and at hydrogen pressures of 0.1 to 400 mm.Hg using a gravimetric measuring process. The thus obtained results allowed the drawing of hydrogen activity slopes in the titanium rich corner of the systems titanium-hydrogen, titanium-aluminium-hydrogen, titanium-vanadium-hydrogen and such for the technical titanium alloys Ti-6Al-4V and Ti-6Al-6V. In spite of the antagonistic effects of the elements aluminium and vanadium on the stabilization of the α and β phase regions of titanium, a hydrogen-activity-increasing effect was always found in which the aluminium influence was greater than that of vanadium. Breaks occured in the hydrogen activity curves and phase boundaries, and phase regions were determined over their positions. Isothermal phase diagrams for the titanium-rich corner of the system titanium-aluminium-hydrogen at 800, 850 and 900 0 C and for the titanium-rich corner of the titanium-vanadium-hydrogen system at 900, 950 and 1,000 0 C were drawn up from the hydrogen activity curves. (orig./LH) [de

  2. Sensitivity of encapsulated diamond-protein transistor renewed by low temperature hydrogen plasma

    Czech Academy of Sciences Publication Activity Database

    Krátká, Marie; Neykova, Neda; Ukraintsev, Egor; Kromka, Alexander; Rezek, Bohuslav

    2013-01-01

    Roč. 8, č. 2 (2013), s. 1598-1608 ISSN 1452-3981 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GAP108/12/0996; GA ČR GD202/09/H041 Institutional support: RVO:68378271 Keywords : nanocrystalline diamond * solution-gated field-effect transistor * low temperature hydrogen termination * proteins * encapsulation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.956, year: 2013 http://www.electrochemsci.org/list13.htm#current

  3. Fast Rotational Diffusion of Water Molecules in a 2D Hydrogen Bond Network at Cryogenic Temperatures

    Science.gov (United States)

    Prisk, T. R.; Hoffmann, C.; Kolesnikov, A. I.; Mamontov, E.; Podlesnyak, A. A.; Wang, X.; Kent, P. R. C.; Anovitz, L. M.

    2018-05-01

    Individual water molecules or small clusters of water molecules contained within microporous minerals present an extreme case of confinement where the local structure of hydrogen bond networks are dramatically altered from bulk water. In the zinc silicate hemimorphite, the water molecules form a two-dimensional hydrogen bond network with hydroxyl groups in the crystal framework. Here, we present a combined experimental and theoretical study of the structure and dynamics of water molecules within this network. The water molecules undergo a continuous phase transition in their orientational configuration analogous to a two-dimensional Ising model. The incoherent dynamic structure factor reveals two thermally activated relaxation processes, one on a subpicosecond timescale and another on a 10-100 ps timescale, between 70 and 130 K. The slow process is an in-plane reorientation of the water molecule involving the breaking of hydrogen bonds with a framework that, despite the low temperatures involved, is analogous to rotational diffusion of water molecules in the bulk liquid. The fast process is a localized motion of the water molecule with no apparent analogs among known bulk or confined phases of water.

  4. Heterogeneously catalyzed deuterium separation processes: Hydrogen-water exchange studies at elevated temperatures and pressures

    International Nuclear Information System (INIS)

    Halliday, J.D.; Rolston, J.H.; Au, J.C.; Den Hartog, J.; Tremblay, R.R.

    1985-01-01

    New processes for the separation of hydrogen isotopes are required to produce heavy water for CANDU nuclear reactors and to extract tritium formed in the moderator during reactor operation. Wetproofed platinum catalysts capable of promoting rapid exchange of isotopes between countercurrent flows of hydrogen and liquid water in packed columns have been developed at CRNL over the past 15 years. These catalysts provide a catalystic surface for the gas phase exchange reaction H/sub 2/O/sub (v)/ + HD/sub (g)/ ↔ HDO/sub (v)/ + H/sub 2(g)/ as well as a large liquid surface for the liquid phase isotope transfer reaction HDO/sub (v)/ + H/sub 2/O/sub (iota)/↔HDO/sub (iota)/+H/sub 2/O/sub (v)/. Any economic stand-alone heavy water separation process, based on bithermal hydrogen-water exchange over wetproofed platinum catalysts, requires rapid overall exchange of isotopes between two phases at two temperatures. Catalysts developed for cold tower operation at 25-60 0 C are now being tested in a laboratory scale stainless steel trickle bed reactor for performance and stability at simulated hot tower conditions, 150 0 C and 2.0 MPa pressure. Catalytically active layers containing platinum supported on carbon or crystalline silica and wetproofed with Teflon have been prepared on ceramic spheres and stainless steel screening and tested in both random and ordered bed columns

  5. Hydrogen from biomass gas steam reforming for low temperature fuel cell: energy and exergy analysis

    Directory of Open Access Journals (Sweden)

    A. Sordi

    2009-03-01

    Full Text Available This work presents a method to analyze hydrogen production by biomass gasification, as well as electric power generation in small scale fuel cells. The proposed methodology is the thermodynamic modeling of a reaction system for the conversion of methane and carbon monoxide (steam reforming, as well as the energy balance of gaseous flow purification in PSA (Pressure Swing Adsorption is used with eight types of gasification gases in this study. The electric power is generated by electrochemical hydrogen conversion in fuel cell type PEMFC (Proton Exchange Membrane Fuel Cell. Energy and exergy analyses are applied to evaluate the performance of the system model. The simulation demonstrates that hydrogen production varies with the operation temperature of the reforming reactor and with the composition of the gas mixture. The maximum H2 mole fraction (0.6-0.64 mol.mol-1 and exergetic efficiency of 91- 92.5% for the reforming reactor are achieved when gas mixtures of higher quality such as: GGAS2, GGAS4 and GGAS5 are used. The use of those gas mixtures for electric power generation results in lower irreversibility and higher exergetic efficiency of 30-30.5%.

  6. Remarks on the thermochemical production of hydrogen from water using heat from the high temperature reactor

    International Nuclear Information System (INIS)

    Barnert, H.

    1980-06-01

    In this report, some aspects of the production of hydrogen from water using heat from the High Temperature Reactor has been studied. These aspects are: the theoretical potential for economic competitivness, the application of hydrogen in the Heat Market, the size of the market potential in the Federal Republic of Germany and the extent of research and development work. In addition another novel proposal for a thermochemical cycle has been studied. For the description of the theoretical potential for economic competitivness, a definition of the 'coupling', has been introduced, which is thermodynamicaly developed; the thermochemical cycle is compared with the thermochemical cycle. Using the coupling, it becomes possible to describe a relation between thermodynamical parameters and the ecomomical basic data of capital costs. Reasons are given from the theoretical point of view for the application of hydrogen as an energy carrier of high exergetic value in the heat market. The discussion of energy problems as 'questions of global survival' leads here to a proposal for the introduction of the term 'extropy'. The market potential in the Federal Republic of Germany is estimated. A further novel proposal for a thermochemical cycle is the 'hydrocarbon-hybrid-process'. The extent of research and development work is explained. (orig.) [de

  7. Relationship between carbon microstructure, adsorption energy and hydrogen adsorption capacity at different temperatures

    International Nuclear Information System (INIS)

    Jacek Jagiello; Matthias Thommes

    2005-01-01

    Various microporous materials such as activated carbons, nano-tubes, synthetic microporous carbons as well as metal organic framework materials are being considered for hydrogen storage applications by means of physical adsorption. To develop materials of practical significance for hydrogen storage it is important to understand the relationships between pore sizes, adsorption energies and adsorption capacities. The pore size distribution (PSD) characterization is traditionally obtained from the analysis of nitrogen adsorption isotherms measured at 77 K. However, a portion of the pores accessible to H 2 may not be accessible to N 2 at this temperature. Therefore, it was recently proposed to use the DFT analysis of H 2 adsorption isotherms to characterize pore structure of materials considered for hydrogen storage applications. In present work, adsorption isotherms of H 2 and N 2 at cryogenic temperatures are used for the characterization of carbon materials. Adsorption measurements were performed with Autosorb 1 MP (Quantachrome Instruments, Boynton Beach, Florida, USA). As an example, Fig 1 compares PSDs calculated for the activated carbon sample (F400, Calgon Carbon) using combined H 2 and N 2 data, and using N 2 isotherm only. The nitrogen derived PSD does not include certain amount of micropores which are accessible to H 2 but not to N 2 molecules. Obviously, the difference in the calculated PSDs by the two methods will depend on the actual content of small micropores in a given sample. Carbon adsorption properties can also be characterized by the isosteric heat of adsorption, Qst, related to the adsorption energy and dependent on the carbon pore/surface structure. Fig 2 shows Qst data calculated using the Clausius-Clapeyron equation from H 2 isotherms measured at 77 K and 87 K for the carbon molecular sieve CMS 5A (Takeda), oxidized single wall nano-tubes (SWNT), and graphitized carbon black (Supelco). The Qst values decrease with increasing pore sizes. The

  8. Ultrafast quenching of metals to liquid-helium temperatures - investigation of the low-temperature mobility of hydrogen in niobium

    International Nuclear Information System (INIS)

    Blanz, M.; Blocher, R.; Carstanjen, H.D.; Messer, R.; Plachke, D.; Seeger, A.

    1989-01-01

    A novel technique for ultrafast quenching from 300 K to 4.2 K has been developed. It employs a fast jet of liquid helium with a speed of about 10 2 m/s and allows us to quench metal samples in about 6 ms. This corresponds to a quenching rate of about 4.5x10 4 K/s, which exceeds that achievable by conventional quenching in liquid helium by more than one order of magnitude. The technique has been used for a resistometric study of the behaviour of hydrogen in niobium quenched-in from the α-phase by means of isochronal and isothermal annealing. Even in the low-temperature region below 20 K a considerable recovery of the resistivity has been found, which cannot be seen in conventional quenching experiments. (orig.)

  9. Hydrogen production by water-splitting using heat supplied by a high-temperature reactor

    International Nuclear Information System (INIS)

    Courvoisier, P.; Rastoin, J.; Titiliette, Z.

    1976-01-01

    Some aspects of the use of heat of nuclear origin for the production of hydrogen by water-splitting are considered. General notions pertaining to the yield of chemical cycles are discussed and the heat balance corresponding to two specific processes is evaluated. The possibilities of high temperature reactors, with respect to the coolant temperature levels, are examined from the standpoint of core design and technology of some components. Furthermore, subject to a judicious selection of their characteristics, these reactors can lead to excellent use of nuclear fuel. The coupling of the nuclear reactor with the chemical plant by means of a secondary helium circuit gives rise to the design of an intermediate heat exchanger, which is an important component of the overall installation. (orig.) [de

  10. 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.

  11. Economic Analysis of the Reference Design for a Nuclear-Driven High-Temperature-Electrolysis Hydrogen Production Plant

    International Nuclear Information System (INIS)

    E. A. Harvego; M. G. McKellar; M. S. Sohal; J. E. O'Brien; J. S. Herring

    2008-01-01

    A reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production was developed to provide a basis for comparing the HTE concept with other hydrogen production concepts. The reference plant design is driven by a high-temperature helium-cooled reactor coupled to a direct Brayton power cycle. The reference design reactor power is 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 540 C and 900 C, respectively. The electrolysis unit used to produce hydrogen consists of 4,009,177 cells with a per-cell active area of 225 cm2. A nominal cell area-specific resistance, ASR, value of 0.4 Ohm-cm2 with a current density of 0.25 A/cm2 was used, and isothermal boundary conditions were assumed. The optimized design for the reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes an air-sweep system to remove the excess oxygen that is evolved on the anode side of the electrolyzer. The inlet air for the air-sweep system is compressed to the system operating pressure of 5.0 MPa in a four-stage compressor with intercooling. The alternating current, AC, to direct current, DC, conversion is 96%. The overall system thermal-to-hydrogen production efficiency (based on the low heating value of the produced hydrogen) is 47.12% at a hydrogen production rate of 2.356 kg/s. An economic analysis of the plant was also performed using the H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost using realistic financial and cost estimating assumptions. A required cost of $3.23 per kg of hydrogen produced was calculated assuming an internal rate of return of 10%. Approximately 73% of this cost ($2.36/kg) is the result of capital costs associated with

  12. Study and modelling of an industrial plant for hydrogen production by High Temperature Steam Electrolysis

    International Nuclear Information System (INIS)

    Bertier, L.

    2012-01-01

    HTSE field (High Temperature Steam Electrolysis) is moving from the research phase to development phase. It's now necessary to prove and to possibly improve the technology competitiveness. Therefore we need a tool able to allow communication between hydrogen producers and electrolysis cell stack designers. Designers seek where their efforts have to focus, for example by searching what are the operating best conditions for HTSE (voltage, temperature). On the contrary, the producer wants to choose the most suitable stack for its needs and under the best conditions: hydrogen has to be produced at the lowest price. Two main constraints have been identified to reach this objective: the tool has to be inserted into a process simulation software and needs to be representative of the cell and stack used technology. These constraints are antagonistic. Making an object model in a process simulation usually involves a highly simplified representation of it. To meet these constraints, we have built a model chain starting from the electrode models and leading to a representative model of the HTSE technology used process. Work and added value of this thesis mainly concern a global and local energy optimization approach. Our model allows at each scale an appropriate analysis of the main phenomena occurring in each object and a quantification of the energy and economic impacts of the technology used. This approach leads to a tool able to achieve the technical and economic optimization of a HTSE production unit. (author) [fr

  13. Some problems on materials tests in high temperature hydrogen base gas mixture

    International Nuclear Information System (INIS)

    Shikama, Tatsuo; Tanabe, Tatsuhiko; Fujitsuka, Masakazu; Yoshida, Heitaro; Watanabe, Ryoji

    1980-01-01

    Some problems have been examined on materials tests (creep rupture tests and corrosion tests) in high temperature mixture gas of hydrogen (80%H 2 + 15%CO + 5%CO 2 ) simulating the reducing gas for direct steel making. H 2 , CO, CO 2 and CH 4 in the reducing gas interact with each other at elevated temperature and produce water vapor (H 2 O) and carbon (soot). Carbon deposited on the walls of retorts and the water condensed at pipings of the lower temperature gas outlet causes blocking of gas flow. The gas reactions have been found to be catalyzed by the retort walls, and appropriate selection of the materials for retorts has been found to mitigate the problems caused by water condensation and carbon deposition. Quartz has been recognized to be one of the most promising materials for minimizing the gas reactions. And ceramic coating, namely, BN (born nitride) on the heat resistant superalloy, MO-RE II, has reduced the amounts of water vapor and deposited carbon (sooting) produced by gas reactions and has kept dew points of outlet gas below room temperature. The well known emf (thermo-electromotive force) deterioration of Alumel-Chromel thermocouples in the reducing gases at elevated temperatures has been also found to be prevented by the ceramic (BN) coating. (author)

  14. Effect of Different Operating Temperatures on the Biological Hydrogen Methanation in Trickle Bed Reactors

    Directory of Open Access Journals (Sweden)

    Andreas Lemmer

    2018-05-01

    Full Text Available To improve the reactor efficiency, this study investigated the influence of temperature on the biological hydrogen methanation (BHM in trickle-bed reactors (TBR. Rising temperatures increase the metabolic activity of methanogenic microorganisms, thus leading to higher reactor specific methane formation rates (MFR. In order to quantify the potential for improved performance, experiments with four different operating temperatures ranging from 40 to 55 °C were carried out. Methane content increased from 88.29 ± 2.12 vol % at 40 °C to 94.99 ± 0.81 vol % at 55 °C with a stable biological process. Furthermore, a reactor specific methane formation rate (MFR of up to 8.85 ± 0.45 m3 m−3 d−1 was achieved. It could be shown that the microorganisms were able to adapt to higher temperatures within hours. The tests showed that TBR performance with regard to BHM can be significantly increased by increasing the operating temperature.

  15. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Vesel, Alenka; Drenik, Aleksander; Elersic, Kristina; Mozetic, Miran; Kovac, Janez [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Gyergyek, Tomaz [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, SI-1000 Ljubljana (Slovenia); Stockel, Jan; Varju, Jozef; Panek, Radomir [Institute of Plasma Physics, Academy of Sciences of the Czech Republic, Ze Slovankou 3, Praha 8 (Czech Republic); Balat-Pichelin, Marianne, E-mail: marianne.balat@promes.cnrs.fr [PROMES-CNRS Laboratory, 7 rue du four solaire, 66120 Font Romeu Odeillo (France)

    2014-06-01

    Initial stages of Inconel 625 superalloy (Ni{sub 60}Cr{sub 30}Mo{sub 10}Ni{sub 4}Nb{sub 1}) oxidation upon short treatment with gaseous plasma at different temperatures up to about 1600 K were studied. Samples were treated for different periods up to a minute by oxygen or hydrogen plasma created with a microwave discharge in the standing-wave mode at a pressure of 40 Pa and a power 500 W. Simultaneous heating of the samples was realized by focusing concentrated solar radiation from a 5 kW solar furnace directly onto the samples. The morphological changes upon treatment were monitored using scanning electron microscopy, compositional depth profiling was performed using Auger electron spectroscopy, while structural changes were determined by X-ray diffraction. The treatment in oxygen plasma caused formation of metal oxide clusters of three dimensional crystallites initially rich in nickel oxide with the increasing chromium oxide content as the temperature was increasing. At about 1100 K iron and niobium oxides prevailed on the surface causing a drop of the material emissivity at 5 μm. Simultaneously the NiCr{sub 2}O{sub 4} compound started growing at the interface between the oxide film and bulk alloy and the compound persisted up to temperatures close to the Inconel melting point. Intensive migration of minority alloying elements such as Fe and Ti was observed at 1600 K forming mixed surface oxides of sub-micrometer dimensions. The treatment in hydrogen plasma with small admixture of water vapor did not cause much modification unless the temperature was close to the melting point. At such conditions aluminum segregated on the surface and formed well-defined Al{sub 2}O{sub 3} crystals.

  16. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    Science.gov (United States)

    Vesel, Alenka; Drenik, Aleksander; Elersic, Kristina; Mozetic, Miran; Kovac, Janez; Gyergyek, Tomaz; Stockel, Jan; Varju, Jozef; Panek, Radomir; Balat-Pichelin, Marianne

    2014-06-01

    Initial stages of Inconel 625 superalloy (Ni60Cr30Mo10Ni4Nb1) oxidation upon short treatment with gaseous plasma at different temperatures up to about 1600 K were studied. Samples were treated for different periods up to a minute by oxygen or hydrogen plasma created with a microwave discharge in the standing-wave mode at a pressure of 40 Pa and a power 500 W. Simultaneous heating of the samples was realized by focusing concentrated solar radiation from a 5 kW solar furnace directly onto the samples. The morphological changes upon treatment were monitored using scanning electron microscopy, compositional depth profiling was performed using Auger electron spectroscopy, while structural changes were determined by X-ray diffraction. The treatment in oxygen plasma caused formation of metal oxide clusters of three dimensional crystallites initially rich in nickel oxide with the increasing chromium oxide content as the temperature was increasing. At about 1100 K iron and niobium oxides prevailed on the surface causing a drop of the material emissivity at 5 μm. Simultaneously the NiCr2O4 compound started growing at the interface between the oxide film and bulk alloy and the compound persisted up to temperatures close to the Inconel melting point. Intensive migration of minority alloying elements such as Fe and Ti was observed at 1600 K forming mixed surface oxides of sub-micrometer dimensions. The treatment in hydrogen plasma with small admixture of water vapor did not cause much modification unless the temperature was close to the melting point. At such conditions aluminum segregated on the surface and formed well-defined Al2O3 crystals.

  17. Two-step gasification of cattle manure for hydrogen-rich gas production: Effect of biochar preparation temperature and gasification temperature.

    Science.gov (United States)

    Xin, Ya; Cao, Hongliang; Yuan, Qiaoxia; Wang, Dianlong

    2017-10-01

    Two-step gasification process was proposed to dispose cattle manure for hydrogen rich gas production. The effect of temperature on product distribution and biochar properties were first studied in the pyrolysis-carbonization process. The steam gasification of biochar derived from different pyrolysis-carbonization temperatures was then performed at 750°C and 850°C. The biochar from the pyrolysis-carbonization temperatures of 500°C had high carbon content and low volatiles content. According to the results of gasification stage, the pyrolysis-carbonization temperature of 500°C and the gasification temperature of 850°C were identified as the suitable conditions for hydrogen production. We obtained 1.61m 3 /kg of syngas production, 0.93m 3 /kg of hydrogen yield and 57.58% of hydrogen concentration. This study shows that two-step gasification is an efficient waste-to-hydrogen energy process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The influence of alkali-free and alkaline shotcrete accelerators within cement systems Influence of the temperature on the sulfate attack mechanisms and damage

    International Nuclear Information System (INIS)

    Paglia, C.; Wombacher, F.; Boehni, H.

    2003-01-01

    The resistance to sulfate attack of mixtures accelerated with alkali-free and alkaline accelerators was found to be mainly influenced by the Al 3+ and SO 4 2- added via the admixtures. Microstructural observations showed decalcification and disintegration of the CSH gel, which acted as an additional Ca 2+ supplier as compared to the CH for ettringite formation. The CSH decalcification was mainly observed with a homogeneous distribution of the alkali-free admixture. The disintegration of the CSH gel increased the porosity and allowed more sulfate solution to penetrate into the specimens. This process promoted the swelling of the specimens and directly contributed to the expansion, explaining the lack of a direct relationship between the ettringite formation and the expansion. Moreover, the CSH gel disintegration, typical for MgSO 4 attack, also occurred with Na 2 SO 4 solutions and depending on the aluminate-sulfate distribution and the extent of the CSH gel disintegration, different damage types were detected. At higher temperatures (65 deg. C) the damage was mainly controlled by the growth, the rearrangement and the thermal stability of ettringite

  19. High and rapid hydrogen release from thermolysis of ammonia borane near PEM fuel cell operating temperature

    Science.gov (United States)

    Varma, Arvind; Hwang, Hyun Tae; Al-Kukhun, Ahmad

    2016-11-15

    A system for generating and purifying hydrogen. To generate hydrogen, the system includes inlets configured to receive a hydrogen carrier and an inert insulator, a mixing chamber configured to combine the hydrogen carrier and the inert insulator, a heat exchanger configured to apply heat to the mixture of hydrogen carrier and the inert insulator, wherein the applied heat results in the generation of hydrogen from the hydrogen carrier, and an outlet configured to release the generated hydrogen. To purify hydrogen, the system includes a primary inlet to receive a starting material and an ammonia filtration subassembly, which may include an absorption column configured to absorb the ammonia into water for providing purified hydrogen at a first purity level. The ammonia filtration subassembly may also include an adsorbent member configured to adsorb ammonia from the starting material into an adsorbent for providing purified hydrogen at a second purity level.

  20. IGSCC growth behaviors of Alloy 690 in hydrogenated high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Arioka, K.; Yamada, T.; Miyamoto, T.; Terachi, T. [INSS, (Japan)

    2011-07-01

    The rate of growth of stress corrosion cracking (SCC) was measured for cold worked and thermally treated and solution treated Alloy 690 (UNS N06690, CW TT690, CW ST690) in hydrogenated pressurized water reactor (PWR) primary water under static load condition. Three important patterns were observed: First, Intergranular stress corrosion cracking (IGSCC) was observed on both TT and ST690 even in static load condition if materials were heavily cold worked although the rate of SCC growth was much slower than that of CW mill annealed Alloy 600. Furthermore much rapid SCC growth was recognized in 20% CW TT690 than that of 20% CW ST690. This is quite different result in the literature in high temperature caustic solution. Second, in order to assess the role of creep, rates of creep crack growth were measured in air, argon, and hydrogen gas environments using 20% CW TT690, and 20% CW MA600 in the range of temperatures between 360 and 460 C; intergranular creep cracking (IG creep cracking) was observed on the test materials even in air. Similar slope of 1/T-type temperature dependencies on IGSCC and IG creep crack growth were observed on 20% CW TT690. Similar fracture morphologies and similar 1/T-type temperature dependencies suggest that creep is important in the growth of IGSCC of CW TT690 in high temperature water. Third, cavities and pores were observed at grain boundaries near tips of SCC and creep although the size of the cavities and pores of SCC were much smaller than that of creep cracks. Also the population and size of cavities seem to decrease with decreasing test temperature. These results suggest that the difference in the size and population of cavities might be related with the difference in crack growth rate. And the cavities seem to be formed result from collapse of vacancies at grain boundaries as the crack embryo. This result suggests that diffusion of condensation of vacancies in high stressed fields occurs in high temperature water and gas environments

  1. Volumetric, acoustic and viscometric behaviour of dipotassium hydrogen phosphate and disodium hydrogen phosphate in aqueous solution of N-acetyl glycine at different temperatures

    International Nuclear Information System (INIS)

    Kumar, Harsh; Singla, Meenu; Mittal, Heena

    2016-01-01

    Highlights: • Densities, speeds of sound, viscosities of phosphate salts in aqueous N-acetyl glycine. • Large values of partial molar volume for dipotassium hydrogen phosphate. • Partial molar volume of transfer are positive for phosphate salts. • Positive B-coefficient values indicate ion–solvent interactions. - Abstract: Densities, speeds of sound and viscosities of dipotassium hydrogen phosphate (DPHP) and disodium hydrogen phosphate (DSHP) in aqueous solutions of N-acetyl glycine (AcGly) are reported at different temperatures. Densities and speeds of sound have been used to calculate apparent molar volume, apparent molar isentropic compression, partial molar volume, partial molar isentropic compression, partial molar volume of transfer, partial molar isentropic compression of transfer and partial molar expansivity. Pair and triplet interaction coefficients have also been calculated. Experimental viscosities have been used to determine B-coefficients. Further pair and triplet interaction coefficients have also been calculated. The results are discussed in terms of solute–solvent interactions.

  2. Highly sensitive work function hydrogen gas sensor based on PdNPs/SiO2/Si structure at room temperature

    Directory of Open Access Journals (Sweden)

    G. Behzadi pour

    Full Text Available In this study, fabrication of highly sensitive PdNPs/SiO2/Si hydrogen gas sensor using experimental and theoretical methods has been investigated. Using chemical method the PdNPs are synthesized and characterized by X-ray diffraction (XRD. The average size of PdNPs is 11 nm. The thickness of the oxide film was 20 nm and the surface of oxide film analyzed using Atomic-force microscopy (AFM. The C-V curve for the PdNPs/SiO2/Si hydrogen gas sensor in 1% hydrogen concentration and at the room temperature has been reported. The response time and recovery time for 1% hydrogen concentration at room temperature were 1.2 s and 10 s respectively. The response (R% for PdNPs/SiO2/Si MOS capacitor hydrogen sensor was 96%. The PdNPs/SiO2/Si MOS capacitor hydrogen sensor showed very fast response and recovery times compared to SWCNTs/PdNPs, graphene/PdNPs, nanorod/PdNPs and nanowire/PdNPs hydrogen gas sensors. Keywords: Sensitive, Oxide film, Capacitive, Resistance

  3. Optimized Flow Sheet for a Reference Commercial-Scale Nuclear-Driven High-Temperature Electrolysis Hydrogen Production Plant

    International Nuclear Information System (INIS)

    M. G. McKellar; J. E. O'Brien; E. A. Harvego; J. S. Herring

    2007-01-01

    This report presents results from the development and optimization of a reference commercial scale high-temperature electrolysis (HTE) plant for hydrogen production. The reference plant design is driven by a high-temperature helium-cooled reactor coupled to a direct Brayton power cycle. The reference design reactor power is 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 540 C and 900 C, respectively. The electrolysis unit used to produce hydrogen consists of 4.176 - 10 6 cells with a per-cell active area of 225 cm2. A nominal cell area-specific resistance, ASR, value of 0.4 Ohm-cm2 with a current density of 0.25 A/cm2 was used, and isothermal boundary conditions were assumed. The optimized design for the reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes an air-sweep system to remove the excess oxygen that is evolved on the anode side of the electrolyzer. The inlet air for the air-sweep system is compressed to the system operating pressure of 5.0 MPa in a four-stage compressor with intercooling. The overall system thermal-to-hydrogen production efficiency (based on the low heating value of the produced hydrogen) is 49.07% at a hydrogen production rate of 2.45 kg/s with the high-temperature helium-cooled reactor concept. The information presented in this report is intended to establish an optimized design for the reference nuclear-driven HTE hydrogen production plant so that parameters can be compared with other hydrogen production methods and power cycles to evaluate relative performance characteristics and plant economics

  4. Syntrophic interactions drive the hydrogen production from glucose at low temperature in microbial electrolysis cells

    KAUST Repository

    Lu, Lu

    2012-11-01

    H2 can be obtained from glucose by fermentation at mesophilic temperatures, but here we demonstrate that hydrogen can also be obtained from glucose at low temperatures using microbial electrolysis cells (MECs). H2 was produced from glucose at 4°C in single-chamber MECs at a yield of about 6mol H2mol-1 glucose, and at rates of 0.25±0.03-0.37±0.04m3 H2m-3d-1. Pyrosequencing of 16S rRNA gene and electrochemical analyses showed that syntrophic interactions combining glucose fermentation with the oxidization of fermentation products by exoelectrogens was the predominant pathway for current production at a low temperature other than direct glucose oxidization by exoelectrogens. Another syntrophic interaction, methanogenesis and homoacetogenesis, which have been found in 25°C reactors, were not detected in MECs at 4°C. These results demonstrate the feasibility of H2 production from abundant biomass of carbohydrates at low temperature in MECs. © 2012 Elsevier Ltd.

  5. Synthesis and characterization of boron-oxygen-hydrogen thin films at low temperatures

    International Nuclear Information System (INIS)

    Music, D.; Koelpin, H.; Atiser, A.; Kreissig, U.; Bobek, T.; Hadam, B.; Schneider, J.M.

    2005-01-01

    We have studied the influence of synthesis temperature on chemical composition and mechanical properties of X-ray amorphous boron-oxygen-hydrogen (B-O-H) films. These B-O-H films have been synthesized by RF sputtering of a B-target in an Ar atmosphere. Upon increasing the synthesis temperature from room temperature to 550 deg. C, the O/B and H/B ratios decrease from 0.73 to 0.15 and 0.28 to 0.07, respectively, as determined by elastic recoil detection analysis. It is reasonable to assume that potential sources of O and H are residual gas and laboratory atmosphere. The elastic modulus, as measured by nanoindentation, increases from 93 to 214 GPa, as the O/B and H/B ratios decreases within the range probed. Hence, we have shown that the effect of impurity incorporation on the elastic properties is extensive and that the magnitude of the incorporation is a strong function of the substrate temperature

  6. 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.

  7. Interplay of community dynamics, temperature, and productivity on the hydrogen isotope signatures of lipid biomarkers

    Directory of Open Access Journals (Sweden)

    S. N. Ladd

    2017-09-01

    Full Text Available The hydrogen isotopic composition (δ2H of lipid biomarkers has diverse applications in the fields of paleoclimatology, biogeochemistry, and microbial community dynamics. Large changes in hydrogen isotope fractionation have been observed among microbes with differing core metabolisms, while environmental factors including temperature and nutrient availability can affect isotope fractionation by photoautotrophs. Much effort has gone into studying these effects under laboratory conditions with single species cultures. Moving beyond controlled environments and quantifying the natural extent of these changes in freshwater lacustrine settings and identifying their causes is essential for robust application of δ2H values of common short-chain fatty acids as a proxy of net community metabolism and of phytoplankton-specific biomarkers as a paleohydrologic proxy. This work targets the effect of community dynamics, temperature, and productivity on 2H∕1H fractionation in lipid biomarkers through a comparative time series in two central Swiss lakes: eutrophic Lake Greifen and oligotrophic Lake Lucerne. Particulate organic matter was collected from surface waters at six time points throughout the spring and summer of 2015, and δ2H values of short-chain fatty acids, as well as chlorophyll-derived phytol and the diatom biomarker brassicasterol, were measured. We paired these measurements with in situ incubations conducted with NaH13CO3, which were used to calculate the production rates of individual lipids in lake surface water. As algal productivity increased from April to June, net discrimination against 2H in Lake Greifen increased by as much as 148 ‰ for individual fatty acids. During the same time period in Lake Lucerne, net discrimination against 2H increased by as much as 58 ‰ for individual fatty acids. A large portion of this signal is likely due to a greater proportion of heterotrophically derived fatty acids in the winter and early

  8. The criteria of critical runaway and stable temperatures of catalytic decomposition of hydrogen peroxide in the presence of hydrochloric acid

    International Nuclear Information System (INIS)

    Lu, K.-T.; Yang, C.-C.; Lin, P.-C.

    2006-01-01

    The hydrogen peroxide and hydrochloric acid are used in close proximity in the computer chip manufacture. The hydrochloric acid catalyzes an exothermic decomposition of hydrogen peroxide into oxygen and water. The accumulation of heat and non-condensable gas increases temperature and pressure in this reaction process always lead to runaway reaction and accident owing to inadvertent mixing. Thus, the chemical reaction hazard has to be clearly identified. Its critical runaway temperatures and unstable reaction criteria in this reaction process have to be determined urgently. In this investigation, we estimated its kinetic parameters at various volumetric ratios of the hydrogen peroxide to hydrochloric acid. Then, used these kinetic parameters to evaluate their critical temperatures and stable criteria in each reaction processes. The analytic results are important and useful for the design of safety system in the computer chip manufacture

  9. High Efficient Reduction of Graphene Oxide via Nascent Hydrogen at Room Temperature

    Directory of Open Access Journals (Sweden)

    Qiqi Zhuo

    2018-02-01

    Full Text Available To develop a green and efficient method to synthesize graphene in relative milder conditions is prerequisite for graphene applications. A chemical reducing method has been developed to high efficiently reduce graphene oxide (GO using Fe2O3 and NH3BH3 as catalyst and reductants, respectively. During the process, environmental and strong reductive nascent hydrogen were generated surrounding the surface of GO sheets by catalyst hydrolysis reaction of NH3BH3 and were used for reduction of GO. The reduction process was studied by ultraviolet absorption spectroscopy, Raman spectroscopy, and Fourier transform infrared spectrum. The structure and morphology of the reduced GO were characterized with scanning electron microscopy and transmission electron microscopy. Compared to metal (Mg/Fe/Zn/Al particles and acid system which also use nascent hydrogen to reduce GO, this method exhibited higher reduction efficiency (43.6%. Also the reduction was carried out at room temperature condition, which is environmentally friendly. As a supercapacitor electrode, the reversible capacity of reduced graphene oxide was 113.8 F g−1 at 1 A g−1 and the capacitance retention still remained at 90% after 200 cycles. This approach provides a new method to reduce GO with high reduction efficiency by green reductant.

  10. Effect of Low-Temperature Sensitization on Hydrogen Embrittlement of 301 Stainless Steel

    Directory of Open Access Journals (Sweden)

    Chieh Yu

    2017-02-01

    Full Text Available The effect of metastable austenite on the hydrogen embrittlement (HE of cold-rolled (30% reduction in thickness 301 stainless steel (SS was investigated. Cold-rolled (CR specimens were hydrogen-charged in an autoclave at 300 or 450 °C under a pressure of 10 MPa for 160 h before tensile tests. Both ordinary and notched tensile tests were performed in air to measure the tensile properties of the non-charged and charged specimens. The results indicated that cold rolling caused the transformation of austenite into α′ and ε-martensite in the 301 SS. Aging at 450 °C enhanced the precipitation of M23C6 carbides, G, and σ phases in the cold-rolled specimen. In addition, the formation of α′ martensite and M23C6 carbides along the grain boundaries increased the HE susceptibility and low-temperature sensitization of the 450 °C-aged 301 SS. In contrast, the grain boundary α′-martensite and M23C6 carbides were not observed in the as-rolled and 300 °C-aged specimens.

  11. Development status on hydrogen production technology using high-temperature gas-cooled reactor at JAEA, Japan

    International Nuclear Information System (INIS)

    Shiozawa, Shusaku; Ogawa, Masuro; Hino, Ryutaro

    2006-01-01

    The high-temperature gas-cooled reactor (HTGR), which is graphite-moderated and helium-cooled, is attractive due to its unique capability of producing high temperature helium gas and its fully inherent reactor safety. In particular, hydrogen production using the nuclear heat from HTGR (up to 900 deg. C) offers one of the most promising technological solutions to curb the rising level of CO 2 emission and resulting risk of climate change. The interests in HTGR as an advanced nuclear power source for the next generation reactor, therefore, continue to rise. This is represented by the Japanese HTTR (High-Temperature Engineering Test Reactor) Project and the Chinese HTR-10 Project, followed by the international Generation IV development program, US nuclear hydrogen initiative program, EU innovative HTR technology development program, etc. To enhance nuclear energy application to heat process industries, the Japan Atomic Energy Agency (JAEA) has continued extensive efforts for development of hydrogen production system using the nuclear heat from HTGR in the framework of the HTTR Project. The HTTR Project has the objectives of establishing both HTGR technology and heat utilization technology. Using the HTTR constructed at the Oarai Research and Development Center of JAEA, reactor performance and safety demonstration tests have been conducted as planned. The reactor outlet temperature of 950 deg. C was successfully achieved in April 2004. For hydrogen production as heat utilization technology, R and D on thermo-chemical water splitting by the 'Iodine-Sulfur process' (IS process) has been conducted step by step. Proof of the basic IS process was made in 1997 on a lab-scale of hydrogen production of 1 L/h. In 2004, one-week continuous operation of the IS process was successfully demonstrated using a bench-scale apparatus with hydrogen production rate of 31 L/h. Further test using a pilot scale facility with greater hydrogen production rate of 10 - 30 m 3 /h is planned as

  12. Parametric Evaluation of Large-Scale High-Temperature Electrolysis Hydrogen Production Using Different Advanced Nuclear Reactor Heat Sources

    International Nuclear Information System (INIS)

    Harvego, Edwin A.; McKellar, Michael G.; O'Brien, James E.; Herring, J. Stephen

    2009-01-01

    High Temperature Electrolysis (HTE), when coupled to an advanced nuclear reactor capable of operating at reactor outlet temperatures of 800 C to 950 C, has the potential to efficiently produce the large quantities of hydrogen needed to meet future energy and transportation needs. To evaluate the potential benefits of nuclear-driven hydrogen production, the UniSim process analysis software was used to evaluate different reactor concepts coupled to a reference HTE process design concept. The reference HTE concept included an Intermediate Heat Exchanger and intermediate helium loop to separate the reactor primary system from the HTE process loops and additional heat exchangers to transfer reactor heat from the intermediate loop to the HTE process loops. The two process loops consisted of the water/steam loop feeding the cathode side of a HTE electrolysis stack, and the sweep gas loop used to remove oxygen from the anode side. The UniSim model of the process loops included pumps to circulate the working fluids and heat exchangers to recover heat from the oxygen and hydrogen product streams to improve the overall hydrogen production efficiencies. The reference HTE process loop model was coupled to separate UniSim models developed for three different advanced reactor concepts (a high-temperature helium cooled reactor concept and two different supercritical CO2 reactor concepts). Sensitivity studies were then performed to evaluate the affect of reactor outlet temperature on the power cycle efficiency and overall hydrogen production efficiency for each of the reactor power cycles. The results of these sensitivity studies showed that overall power cycle and hydrogen production efficiencies increased with reactor outlet temperature, but the power cycles producing the highest efficiencies varied depending on the temperature range considered

  13. Room temperature synthesis of heptazine-based microporous polymer networks as photocatalysts for hydrogen evolution.

    Science.gov (United States)

    Kailasam, Kamalakannan; Schmidt, Johannes; Bildirir, Hakan; Zhang, Guigang; Blechert, Siegfried; Wang, Xinchen; Thomas, Arne

    2013-06-25

    Two emerging material classes are combined in this work, namely polymeric carbon nitrides and microporous polymer networks. The former, polymeric carbon nitrides, are composed of amine-bridged heptazine moieties and showed interesting performance as a metal-free photocatalyst. These materials have, however, to be prepared at high temperatures, making control of their chemical structure difficult. The latter, microporous polymer networks have received increasing interest due to their high surface area, giving rise to interesting applications in gas storage or catalysis. Here, the central building block of carbon nitrides, a functionalized heptazine as monomer, and tecton are used to create microporous polymer networks. The resulting heptazine-based microporous polymers show high porosity, while their chemical structure resembles the ones of carbon nitrides. The polymers show activity for the photocatalytic production of hydrogen from water, even under visible light illumination. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Temperature-Dependent Rate Coefficients for the Reaction of CH2OO with Hydrogen Sulfide.

    Science.gov (United States)

    Smith, Mica C; Chao, Wen; Kumar, Manoj; Francisco, Joseph S; Takahashi, Kaito; Lin, Jim Jr-Min

    2017-02-09

    The reaction of the simplest Criegee intermediate CH 2 OO with hydrogen sulfide was measured with transient UV absorption spectroscopy in a temperature-controlled flow reactor, and bimolecular rate coefficients were obtained from 278 to 318 K and from 100 to 500 Torr. The average rate coefficient at 298 K and 100 Torr was (1.7 ± 0.2) × 10 -13 cm 3 s -1 . The reaction was found to be independent of pressure and exhibited a weak negative temperature dependence. Ab initio quantum chemistry calculations of the temperature-dependent reaction rate coefficient at the QCISD(T)/CBS level are in reasonable agreement with the experiment. The reaction of CH 2 OO with H 2 S is 2-3 orders of magnitude faster than the reaction with H 2 O monomer. Though rates of CH 2 OO scavenging by water vapor under atmospheric conditions are primarily controlled by the reaction with water dimer, the H 2 S loss pathway will be dominated by the reaction with monomer. The agreement between experiment and theory for the CH 2 OO + H 2 S reaction lends credence to theoretical descriptions of other Criegee intermediate reactions that cannot easily be probed experimentally.

  15. Thermodynamic analysis of the efficiency of high-temperature steam electrolysis system for hydrogen production

    Science.gov (United States)

    Mingyi, Liu; Bo, Yu; Jingming, Xu; Jing, Chen

    High-temperature steam electrolysis (HTSE), a reversible process of solid oxide fuel cell (SOFC) in principle, is a promising method for highly efficient large-scale hydrogen production. In our study, the overall efficiency of the HTSE system was calculated through electrochemical and thermodynamic analysis. A thermodynamic model in regards to the efficiency of the HTSE system was established and the quantitative effects of three key parameters, electrical efficiency (η el), electrolysis efficiency (η es), and thermal efficiency (η th) on the overall efficiency (η overall) of the HTSE system were investigated. Results showed that the contribution of η el, η es, η th to the overall efficiency were about 70%, 22%, and 8%, respectively. As temperatures increased from 500 °C to 1000 °C, the effect of η el on η overall decreased gradually and the η es effect remained almost constant, while the η th effect increased gradually. The overall efficiency of the high-temperature gas-cooled reactor (HTGR) coupled with the HTSE system under different conditions was also calculated. With the increase of electrical, electrolysis, and thermal efficiency, the overall efficiencies were anticipated to increase from 33% to a maximum of 59% at 1000 °C, which is over two times higher than that of the conventional alkaline water electrolysis.

  16. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.; Gerlach, L.; Malliakos, A.

    1995-01-01

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant product,s and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below

  17. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.

    1996-01-01

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant products, and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below

  18. Detonation cell size measurements in high-temperature hydrogen-air-steam mixtures at the BNL high-temperature combustion facility

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsberg, T.; Boccio, J.L.

    1997-11-01

    The High-Temperature Combustion Facility (HTCF) was designed and constructed with the objective of studying detonation phenomena in mixtures of hydrogen-air-steam at initially high temperatures. The central element of the HTCF is a 27-cm inner-diameter, 21.3-m long cylindrical test vessel capable of being heating to 700K ± 14K. A unique feature of the HTCF is the 'diaphragmless' acetylene-oxygen gas driver which is used to initiate the detonation in the test gas. Cell size measurements have shown that for any hydrogen-air-steam mixture, increasing the initial mixture temperature, in the range of 300K to 650K, while maintaining the initial pressure of 0.1 MPa, decreases the cell size and thus makes the mixture more detonable. The effect of steam dilution on cell size was tested in stoichiometric and off-stoichiometric (e.g., equivalence ratio of 0.5) hydrogen-air mixtures. Increasing the steam dilution in hydrogen-air mixtures at 0.1 MPa initial pressure increases the cell size, irrespective of initial temperature. It is also observed that the desensitizing effect of steam diminished with increased initial temperature. A 1-dimensional, steady-state Zel'dovich, von Neumann, Doring (ZND) model, with full chemical kinetics, has been used to predict cell size for hydrogen-air-steam mixtures at different initial conditions. Qualitatively the model predicts the overall trends observed in the measured cell size versus mixture composition and initial temperature and pressure. It was found that the proportionality constant used to predict detonation cell size from the calculated ZND model reaction zone varies between 10 and 100 depending on the mixture composition and initial temperature. 32 refs., 35 figs

  19. On the yield of cold and ultracold neutrons for liquid hydrogen at low temperatures near the melting point

    CERN Document Server

    Morishima, N

    1999-01-01

    The neutron scattering cross sections for liquid hydrogen in the temperature range from the melting point to the boiling point are calculated. It is shown that lowering the temperature results in a significant increase in the yield of cold neutrons: for instance, a 44% increase for an incident neutron energy of 19.4 meV. The major cause of this increment is the para-to-ortho transition of a hydrogen molecule though accompanied by an appreciable increase in the density. The results of the cold- and ultracold-neutron yields are discussed in connection with the experimental results of Altarev et al. at the WWR-M reactor.

  20. Relationship between carbon microstructure, adsorption energy and hydrogen adsorption capacity at different temperatures

    International Nuclear Information System (INIS)

    Jagiello, J.; Thommes, M.

    2005-01-01

    Various microporous materials such as activated carbons, nano-tubes, synthetic micro-porous carbons as well as metal organic framework materials are being considered for hydrogen storage applications by means of physical adsorption. To develop materials of practical significance for hydrogen storage it is important to understand the relationships between pore sizes, adsorption energies and adsorption capacities. The pore size distribution (PSD) characterization is traditionally obtained from the analysis of nitrogen adsorption isotherms measured at 77 K. However, a portion of the pores accessible to H 2 may not be accessible to N 2 at this temperature. Therefore, it was recently proposed to use the DFT analysis of H 2 adsorption isotherms to characterize pore structure of materials considered for hydrogen storage applications [1]. In present work, adsorption isotherms of H 2 and N 2 at cryogenic temperatures are used for the characterization of carbon materials. Adsorption measurements were performed with Autosorb 1 MP [Quantachrome Instruments, Boynton Beach, Florida, USA]. As an example, Fig 1 compares PSDs calculated for the activated carbon sample (F400, Calgon Carbon) using combined H 2 and N 2 data, and using N 2 isotherm only. The nitrogen derived PSD does not include certain amount of micro-pores which are accessible to H 2 but not to N 2 molecules. Obviously, the difference in the calculated PSDs by the two methods will depend on the actual content of small micro-pores in a given sample. Carbon adsorption properties can also be characterized by the isosteric heat of adsorption, Qst, related to the adsorption energy and dependent on the carbon pore/surface structure. Fig 2 shows Qst data calculated using the Clausius-Clapeyron equation from H 2 isotherms measured at 77 K and 87 K for the carbon molecular sieve CMS 5A (Takeda), oxidized single wall nano-tubes (SWNT) [2], and graphitized carbon black (Supelco). The Qst values decrease with increasing pore

  1. Fracture resistance of the VNC-2USh steel with different content of diffusion-mobile hydrogen at low temperature

    International Nuclear Information System (INIS)

    Yablonskij, I.S.; Sankho, K.

    1979-01-01

    Presented are the investigation results for the diffusible hydrogen (DH) content effect on cracking resistance and mechanical properties of the VNC-2USh steel in the temperature range from -75-100 deg C. In this range σsub(B), σsub(0.2) and σ are not practically sensitive to the DH content change from 0.27 to 3 cm 3 /100g. At room temperature the increase of DH content in the above concentration range results in 45 % decrease of cracking resistance under static loading. At -75 deg C the cracking resistance does not depend on DH content. Within the temperature range from -40-75 deg C placed is a temperature boundary, separating the regions of predominant effects of hydrogen and low temperature embrittlement on repture strength of the VNC-2 steel at moderated rates of deformation

  2. Studies on the permeation of hydrogen through steam generator tubes at high temperatures using an electrochemical method

    International Nuclear Information System (INIS)

    Giraudeau, F.; Yang, L.; Steward, F.R.; DeBouvier, O.

    1998-01-01

    The permeation of hydrogen through steam generator tubes at high temperatures (∼ 300 degrees C) has been studied using an electrochemical technique. With this technique, hydrogen is generated on one side of the tube and monitored on the other side. The time for the hydrogen to reach the other side is used to determine the diffusion coefficient of hydrogen in the tube. Boundary conditions at the entry and exit sides have been investigated separately. Preliminary studies were performed on Stainless Steel 316 and Nickel Alloy 800 to better understand the influence of the solution chemistry on the electrochemical evolution of hydrogen. The surface phenomena effect and the trapping effect are discussed to account for differences observed in the permeation response. The hydrogen permeation through oxides at the exit side has been studied. Two nickel alloys (Alloy 800 and Alloy 600), materials widely used for steam generator tubes, have been investigated. The tubes were prefilmed using two different treatments. The oxides were formed in dry air at high temperatures (300 degrees C to 600 degrees C), or in humid gas at 300 degrees C. The diffusion coefficients at 300 degrees C in Stainless Steel 316 and Alloy 800 were determined to be of the order of 10 -6 - 10 -7 cm 2 /s for the bare metal. This is in agreement with results obtained by gas phase permeation techniques in the literature. (author)

  3. Room temperature hydrogen generation from hydrolysis of ammonia-borane over an efficient NiAgPd/C catalyst

    KAUST Repository

    Hu, Lei

    2014-12-01

    NiAgPd nanoparticles are successfully synthesized by in-situ reduction of Ni, Ag and Pd salts on the surface of carbon. Their catalytic activity was examined in ammonia borane (NH3BH3) hydrolysis to generate hydrogen gas. This nanomaterial exhibits a higher catalytic activity than those of monometallic and bimetallic counterparts and a stoichiometric amount of hydrogen was produced at a high generation rate. Hydrogen production rates were investigated in different concentrations of NH3BH3 solutions, including in the borates saturated solution, showing little influence of the concentrations on the reaction rates. The hydrogen production rate can reach 3.6-3.8 mol H2 molcat -1 min-1 at room temperature (21 °C). The activation energy and TOF value are 38.36 kJ/mol and 93.8 mol H2 molcat -1 min-1, respectively, comparable to those of Pt based catalysts. This nanomaterial catalyst also exhibits excellent chemical stability, and no significant morphology change was observed from TEM after the reaction. Using this catalyst for continuously hydrogen generation, the hydrogen production rate can be kept after generating 6.2 L hydrogen with over 10,000 turnovers and a TOF value of 90.3 mol H2 molcat -1 min-1.

  4. Study of susceptibility to hydrogen embrittlement of welded joints of large WWER reactor vessels at different temperatures

    International Nuclear Information System (INIS)

    Mazel', R.E.; Kuznetsova, T.P.; Grinenko, V.G.; Sapronova, M.N.

    1977-01-01

    The effect is studied of hydrogen and a coolant of WWER on the susceptibility to brittle fracture of welded joints from steels 15Kh2MFA and 15Kh2NMFA obtained by automatic submerged arc welding with the use of the welding materials of different purity. The effect of hydrogen (concentration range 0.5-7.5 cm 3 /100 g, testing temperatures 20, 70 and 325 deg C) and the coolant (pressures up to 120 atm, temperatures 20-350 deg C) have been estimated by the fracture work during static bending tests. It is shown that the purification of the welding materials enhances the fracture properties by about a factor of 2. Hydrogenation results in a sharp drop (by about a factor of 3) of the fracture work. The increased testing temperature (up to 325 deg C) is accompanied by disappearance of the effect of hydrogen embrittlement, which is explained by an increase in the diffusion mobility of atomic hydrogen. Under the action of the coolant the fracture work shows a two-fold decrease, while the pressure being increased up to 100 atm leads to greater fracture work decrease

  5. Formation of the low-resistivity compound Cu_3Ge by low-temperature treatment in an atomic hydrogen flux

    International Nuclear Information System (INIS)

    Erofeev, E. V.; Kazimirov, A. I.; Fedin, I. V.; Kagadei, V. A.

    2016-01-01

    The systematic features of the formation of the low-resistivity compound Cu_3Ge by low-temperature treatment of a Cu/Ge two-layer system in an atomic hydrogen flux are studied. The Cu/Ge two-layer system is deposited onto an i-GaAs substrate. Treatment of the Cu/Ge/i-GaAs system, in which the layer thicknesses are, correspondingly, 122 and 78 nm, in atomic hydrogen with a flux density of 10"1"5 at cm"2 s"–"1 for 2.5–10 min at room temperature induces the interdiffusion of Cu and Ge, with the formation of a polycrystalline film containing the stoichiometric Cu_3Ge phase. The film consists of vertically oriented grains 100–150 nm in size and exhibits a minimum resistivity of 4.5 µΩ cm. Variations in the time of treatment of the Cu/Ge/i-GaAs samples in atomic hydrogen affect the Cu and Ge depth distribution, the phase composition of the films, and their resistivity. Experimental observation of the synthesis of the Cu_3Ge compound at room temperature suggests that treatment in atomic hydrogen has a stimulating effect on both the diffusion of Cu and Ge and the chemical reaction of Cu_3Ge-compound formation. These processes can be activated by the energy released upon the recombination of hydrogen atoms adsorbed at the surface of the Cu/Ge/i-GaAs sample.

  6. Analysis of transient permeation behavior of hydrogen isotope caused by abrupt temperature change of first wall and blanket wall material

    International Nuclear Information System (INIS)

    Yamawaki, Michio; Tanaka, Satoru; Kiyoshi, Tsukasa

    1989-01-01

    To obtain further information on the transient permeation behavior of hydrogen isotopes as caused by an abrupt temperature change, numerical calculations were carried out for two typical metals, nickel and vanadium. Deuterium permeation through nickel is analyzed as a typical case of bulk-diffusion-limited permeation. Its transient behavior changed dramatically according to the specimen thickness. The transient behavior, in general, is separated into two parts, initial and latter period behaviors. Conditions which cause such a separation were evaluated. Evaluation of the hydrogen diffusivity and solubility by an analysis of transient curves of hydrogen permeation was carried out. The transient behavior of simultaneous gas- and ion-driven hydrogen permeation through vanadium was also analyzed. Overshooting of the hydrogen permeation rate appears with an abrupt temperature increase. Increasing the impinging ion flux causes the overshooting peak to become sharper, and also reduces the change of the steady-state permeation rate to be attained after the temperature change compared with the initial value. (orig.)

  7. Generation of Hydrogen and Methane during Experimental Low-Temperature Reaction of Ultramafic Rocks with Water

    Science.gov (United States)

    McCollom, Thomas M.; Donaldson, Christopher

    2016-06-01

    Serpentinization of ultramafic rocks is widely recognized as a source of molecular hydrogen (H2) and methane (CH4) to support microbial activity, but the extent and rates of formation of these compounds in low-temperature, near-surface environments are poorly understood. Laboratory experiments were conducted to examine the production of H2 and CH4 during low-temperature reaction of water with ultramafic rocks and minerals. Experiments were performed by heating olivine or harzburgite with aqueous solutions at 90°C for up to 213 days in glass bottles sealed with butyl rubber stoppers. Although H2 and CH4 increased steadily throughout the experiments, the levels were very similar to those found in mineral-free controls, indicating that the rubber stoppers were the predominant source of these compounds. Levels of H2 above background were observed only during the first few days of reaction of harzburgite when CO2 was added to the headspace, with no detectable production of H2 or CH4 above background during further heating of the harzburgite or in experiments with other mineral reactants. Consequently, our results indicate that production of H2 and CH4 during low-temperature alteration of ultramafic rocks may be much more limited than some recent experimental studies have suggested. We also found no evidence to support a recent report suggesting that spinels in ultramafic rocks may stimulate H2 production. While secondary silicates were observed to precipitate during the experiments, formation of these deposits was dominated by Si released by dissolution of the glass bottles, and reaction of the primary silicate minerals appeared to be very limited. While use of glass bottles and rubber stoppers has become commonplace in experiments intended to study processes that occur during serpentinization of ultramafic rocks at low temperatures, the high levels of H2, CH4, and SiO2 released during heating indicate that these reactor materials are unsuitable for this purpose.

  8. One-Dimensional Vanadium Dioxide Nanostructures for Room Temperature Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Aline Simo

    2015-06-01

    Full Text Available In relation to hydrogen (H2 economy in general and gas sensing in particular, an extensive set of one dimensional (1-D nano-scaled oxide materials are being investigated as ideal candidates for potential gas sensing applications. This is correlated to their set of singular surface characteristics, shape anisotropy and readiness for integrated devices. Nanostructures of well- established gas sensing materials such as Tin Oxide (SnO2, Zinc Oxide (ZnO, Indium (III Oxide (In2O3, and Tungsten Trioxide (WO3 have shown higher sensitivity and gas selectivity, quicker response, faster time recovery, as well as an enhanced capability to detect gases at low concentrations. While the overall sensing characteristics of these so called 1-D nanomaterials are superior, they are efficient at high temperature; generally above 200 0C. This operational impediment results in device complexities in integration that limit their technological applications, specifically in their miniaturized arrangements. Unfortunately, for room temperature applications, there is a necessity to dope the above mentioned nano-scaled oxides with noble metals such as Platinum (Pt, Palladium (Pd, Gold (Au, Ruthenium (Ru. This comes at a cost. This communication reports, for the first time, on the room temperature enhanced H2 sensing properties of a specific phase of pure Vanadium Dioxide (VO2 phase A in their nanobelt form. The relatively observed large H2 room temperature sensing in this Mott type specific oxide seems to reach values as low as 14 ppm H2 which makes it an ideal gas sensing in H2 fuelled systems.

  9. Temperature effects on the behavior of liquid hydrogen isotopes inside a spherical-shell directly driven inertial confinement fusion target

    International Nuclear Information System (INIS)

    Kim, K.; Mok, L.S.

    1984-05-01

    The present work studies the temperature effects on the formation of a uniform liquid hydrogen layer inside a spherical glass shell (SGS). The profile of the liquid layer is first investigated for an isothermal case. An equation suitable for describing the profile is derived by including the London-van der Waals attractive forces between the liquid and substrate molecules. Two theoretical models are then established to explain the changes in the liquid layer profile under the influence of a vertically applied temperature gradient. The characteristics of the fluid flows are obtained by solving the fluid equations under the low-Reynolds-number approximations. The effect of the component separation both in the liquid layer and the vapor region, which is induced by the temperature gradient, is studied when the enclosure inside the SGS is a mixture of hydrogen isotopes. A uniform layer can also be formed for the mixture liquid except that the required temperature gradient is now positive in direction, unlike the case of the single-component liquid. The heating effect due to the radioactive decay of tritium is also evaluated. An experimental apparatus capable of generating a desired temperature gradient across the SGS at liquid hydrogen temperatures is described. The profiles of the liquid layer are observed for different temperature gradients and the results are in qualitative agreement with the theoretical predictions

  10. Effects of temperature and mass conservation on the typical chemical sequences of hydrogen oxidation

    Science.gov (United States)

    Nicholson, Schuyler B.; Alaghemandi, Mohammad; Green, Jason R.

    2018-01-01

    Macroscopic properties of reacting mixtures are necessary to design synthetic strategies, determine yield, and improve the energy and atom efficiency of many chemical processes. The set of time-ordered sequences of chemical species are one representation of the evolution from reactants to products. However, only a fraction of the possible sequences is typical, having the majority of the joint probability and characterizing the succession of chemical nonequilibrium states. Here, we extend a variational measure of typicality and apply it to atomistic simulations of a model for hydrogen oxidation over a range of temperatures. We demonstrate an information-theoretic methodology to identify typical sequences under the constraints of mass conservation. Including these constraints leads to an improved ability to learn the chemical sequence mechanism from experimentally accessible data. From these typical sequences, we show that two quantities defining the variational typical set of sequences—the joint entropy rate and the topological entropy rate—increase linearly with temperature. These results suggest that, away from explosion limits, data over a narrow range of thermodynamic parameters could be sufficient to extrapolate these typical features of combustion chemistry to other conditions.

  11. Hydrogen Treatment for Superparamagnetic VO2 Nanowires with Large Room-Temperature Magnetoresistance.

    Science.gov (United States)

    Li, Zejun; Guo, Yuqiao; Hu, Zhenpeng; Su, Jihu; Zhao, Jiyin; Wu, Junchi; Wu, Jiajing; Zhao, Yingcheng; Wu, Changzheng; Xie, Yi

    2016-07-04

    One-dimensional (1D) transition metal oxide (TMO) nanostructures are actively pursued in spintronic devices owing to their nontrivial d electron magnetism and confined electron transport pathways. However, for TMOs, the realization of 1D structures with long-range magnetic order to achieve a sensitive magnetoelectric response near room temperature has been a longstanding challenge. Herein, we exploit a chemical hydric effect to regulate the spin structure of 1D V-V atomic chains in monoclinic VO2 nanowires. Hydrogen treatment introduced V(3+) (3d(2) ) ions into the 1D zigzag V-V chains, triggering the formation of ferromagnetically coupled V(3+) -V(4+) dimers to produce 1D superparamagnetic chains and achieve large room-temperature negative magnetoresistance (-23.9 %, 300 K, 0.5 T). This approach offers new opportunities to regulate the spin structure of 1D nanostructures to control the intrinsic magnetoelectric properties of spintronic materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Future Low Temperature Plasma Science and Technology: Attacking Major Societal Problems by Building on a Tradition of Scientific Rigor

    Science.gov (United States)

    Graves, David

    2014-10-01

    Low temperature plasma (LTP) science is unequivocally one of the most prolific areas for varied applications in modern technology. For example, plasma etching technology is essential for reliably and rapidly patterning nanometer scale features over areas approaching one square meter with relatively inexpensive equipment. This technology enabled the telecommunication and information processing revolution that has transformed human society. I explore two concepts in this talk. The first is that the firm scientific understanding of LTP is and has been the enabling feature of these established technological applications. And the second is that LTP technology is poised to contribute to several emerging societal challenges. Beyond the important, ongoing applications of LTP science to problems of materials processing related to energy generation (e.g. thin film solar cell manufacture), there are novel and less well known potential applications in food and agriculture, infection control and medicine. In some cases, the potentially low cost nature of the applications in so compelling that they can be thought of as examples of frugal innovation. Supported in part by NSF and DoE.

  13. Polymer-derived microporous ceramics for membranes and sensors for high temperature hydrogen purification and sensing

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Ravi Mohan

    2012-06-11

    The growing interest in the use of hydrogen as main fuel has increased the need for pure hydrogen (H{sub 2}) production and purification. There are several by-products (CO, H{sub 2}O, CO{sub 2}) associated with the production of hydrogen which might damage the production rate. Therefore, separation of hydrogen from other gases is an important step in the hydrogen production process. If H{sub 2} can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single-step under high temperature conditions. The main goal of the present work is the high temperature H{sub 2} purification and sensing by applying polymer-derived ceramics. To prove the concept, the microporous SiBCN, Si{sub 3}N{sub 4} and SiCN ceramic membranes have been synthesized by the polymer-pyrolysis route and their performance for the hydrogen separation have been evaluated in tubular membranes as well as in planar chemiresistors. The synthesis of amorphous SiBCN ceramics has been realized through pyrolysis of poly(organoborosilazanes) in argon. Multilayered amorphous SiBCN/{gamma}-Al{sub 2}O{sub 3}/{alpha}-Al{sub 2}O{sub 3} membranes with gradient porosity have been realized and assessed with respect to the thermal stability, pore-size distribution and H{sub 2}/CO permeance. N{sub 2}-adsorption measurement indicates micropores in the range of 0.68-0.73 nm for three-fold SiBCN/{gamma}-Al{sub 2}O{sub 3}/{alpha}-Al{sub 2}O{sub 3} membrane. SEM characterization of three-fold SiBCN/{gamma}-Al{sub 2}O{sub 3}/{alpha}-Al{sub 2}O{sub 3} membrane shows the thickness of SiBCN membrane layer is 2.8 {mu}m; gas permeance measurements of the membrane shows H{sub 2}/CO selectivity of about 10.5 and the H{sub 2} permeance of about 1.05 x 10{sup -8} mol m{sup -2}s{sup -1}Pa{sup -1}. The observed gas permeation properties point out that the transportation of gas molecules through the membrane is governed by both

  14. Hydrogen separation from high temperature CO-containing syn-gas flow using molecular ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Soudarev, A.; Konakov, G.; Souryaninov, A.; Molchanov, A. [Boyko Research Engineering Ceramic Heat Engines Center Ltd., St. Petersburg (Russian Federation); Lelait, L.; Stevens, P.H. [European Inst. for Power Studies, Karlsruhe (Germany)

    2006-07-01

    Poisoning of the platinum (Pt) metals used as catalysts for proton exchange membrane fuel cells (PEMFCs) can negatively impact on PEMFC operation efficiency. In order to address this issue, a supply of hydrogen with a carbon monoxide (CO) admixtures is required. This paper provided details of a new type of molecular ceramic membrane (MCM) that allows the separation of hydrogen (H{sub 2}) from the hydrocarbon fuel reforming products that contain CO and has higher temperature and pressure capacity than other membranes. After various tests, alumo-magnesium spinel (AMS) was selected as the most promising porous material for the ceramic multi-layer membrane. The crystalline structure of the AMS showed good thermo-dynamic stability during tests that ranged between 20 and 1400 degrees C, as well as a chemical resistance relative to the effects of the aggressive fuel cell environment, and no exposure to the oxidation-recovery processes in the CO and H{sub 2} flow. The macroporous substrate of the AMS and the membrane selection layers have the same composition. The formation of the carrier was conducted by a semi-dry molding on a hydraulic press. Formation of the nano-porous structure in the carrier macro-pores by the polysilicon acid sol solution treatment allowed the synthesis of the amorphous silica and crystobalite crystals with a developed surface and nano-dimension subporosity. Test results have shown that the MCM has optimum penetrability and selectivity values as well as admissible thermo-mechanical properties. H{sub 2} flow through the membrane was 1.5-1.7 times greater than the CO flow. It was concluded that the AMS-based membrane devices will increase the efficiency of the PEMFC power plants and reduce their degradation capacity. 2 refs., 1 tab., 1 fig.

  15. Development of High Temperature SiC Based Hydrogen/Hydrocarbon Sensors with Bond Pads for Packaging

    Science.gov (United States)

    Xu, Jennifer C.; Hunter, Gary W.; Chen, Liangyu; Biagi-Labiosa, Azlin M.; Ward, Benjamin J.; Lukco, Dorothy; Gonzalez, Jose M., III; Lampard, Peter S.; Artale, Michael A.; Hampton, Christopher L.

    2011-01-01

    This paper describes efforts towards the transition of existing high temperature hydrogen and hydrocarbon Schottky diode sensor elements to packaged sensor structures that can be integrated into a testing system. Sensor modifications and the technical challenges involved are discussed. Testing of the sensors at 500 C or above is also presented along with plans for future development.

  16. Diffusion characteristics of specific metals at the high temperature hydrogen separation; Diffusionseigenschaften bestimmter Metalle bei der Hochtemperatur-Wasserstoffabtrennung

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Christian

    2010-09-07

    This paper evaluates the metals palladium, nickel, niobium, tantalum, titanium and vanadium according to their ability to separate hydrogen at high temperatures. This evaluation is chiefly based on a thorough consideration of the properties of diffusion for these metals. The various known hydrogen permeabilities of the metals in a temperature range from 300 to 800 C, as well as their physical and mechanical properties will be presented consistent with the current state of technology. The theory of hydrogen diffusion in metals and the mathematical basis for the calculation of diffusion will also be shown. In the empirical section of the paper, permeability measurements are taken in a temperature range of 400 to 825 C. After measurement, the formation of the oxide coating on these membranes is examined using a light-optical microscope. The results of these examinations allow a direct comparison of the different permeabilities of the various metals within the temperature range tested, and also allow for a critical evaluation of the oxide coating formed on the membranes. The final part of the paper shows the efficiency of these metals in the context of in-situ hydrogen separation in a biomass reformer. (orig.)

  17. Unravelling the dependence of hydrogen oxidation kinetics on the size of Pt nanoparticles by in operando nanoplasmonic temperature sensing

    DEFF Research Database (Denmark)

    Wettergren, Kristina; Hellman, Anders; Cavalca, Filippo Carlo

    2015-01-01

    We use a noninvasive nanoscale optical-temperature measurement method based on localized surface plasmon resonance to investigate the particle size-dependence of the hydrogen oxidation reaction kinetics on model supported Pt nanocatalysts at atmospheric pressure in operando. With decreasing average...

  18. Hydrogen Production via a High-Efficiency Low-Temperature Reformer

    Energy Technology Data Exchange (ETDEWEB)

    Paul KT Liu; Theo T. Tsotsis

    2006-05-31

    Fuel cells are promoted by the US government as a viable alternative for clean and efficient energy generation. It is anticipated that the fuel cell market will rise if the key technical barriers can be overcome. One of them is certainly fuel processing and purification. Existing fuel reforming processes are energy intensive, extremely complicated and capital intensive; these disadvantages handicap the scale-down of existing reforming process, targeting distributed or on-board/stationary hydrogen production applications. Our project involves the bench-scale demonstration of a high-efficiency low-temperature steam reforming process. Hydrogen production can be operated at 350 to 400ºC with our invention, as opposed to >800ºC of existing reforming. In addition, our proposed process improves the start-up deficiency of conventional reforming due to its low temperature operation. The objective of this project is to demonstrate the invented process concept via a bench scale unit and verify mathematical simulation for future process optimization study. Under this project, we have performed the experimental work to determine the adsorption isotherm, reaction kinetics, and membrane permeances required to perform the process simulation based upon the mathematical model developed by us. A ceramic membrane coated with palladium thin film fabricated by us was employed in this study. The adsorption isotherm for a selected hydrotalcite adsorbent was determined experimentally. Further, the capacity loss under cyclic adsorption/desorption was confirmed to be negligible. Finally a commercial steam reforming catalyst was used to produce the reaction kinetic parameters required for the proposed operating condition. With these input parameters, a mathematical simulation was performed to predict the performance of the invented process. According to our simulation, our invented hybrid process can deliver 35 to 55% methane conversion, in comparison with the 12 and 18-21% conversion of

  19. System Evaluation and Life-Cycle Cost Analysis of a Commercial-Scale High-Temperature Electrolysis Hydrogen Production Plant

    Energy Technology Data Exchange (ETDEWEB)

    Edwin A. Harvego; James E. O' Brien; Michael G. McKellar

    2012-11-01

    Results of a system evaluation and lifecycle cost analysis are presented for a commercial-scale high-temperature electrolysis (HTE) central hydrogen production plant. The plant design relies on grid electricity to power the electrolysis process and system components, and industrial natural gas to provide process heat. The HYSYS process analysis software was used to evaluate the reference central plant design capable of producing 50,000 kg/day of hydrogen. The HYSYS software performs mass and energy balances across all components to allow optimization of the design using a detailed process flow sheet and realistic operating conditions specified by the analyst. The lifecycle cost analysis was performed using the H2A analysis methodology developed by the Department of Energy (DOE) Hydrogen Program. This methodology utilizes Microsoft Excel spreadsheet analysis tools that require detailed plant performance information (obtained from HYSYS), along with financial and cost information to calculate lifecycle costs. The results of the lifecycle analyses indicate that for a 10% internal rate of return, a large central commercial-scale hydrogen production plant can produce 50,000 kg/day of hydrogen at an average cost of $2.68/kg. When the cost of carbon sequestration is taken into account, the average cost of hydrogen production increases by $0.40/kg to $3.08/kg.

  20. Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

    Directory of Open Access Journals (Sweden)

    Mason L. Terry

    2007-01-01

    Full Text Available The changes in open-circuit voltage (Voc, short-circuit current density (Jsc, and internal quantum efficiency (IQE of aLuminum induced crystallization, ion-assisted deposition (ALICIA polycrystalline silicon thin-film solar cells on low-temperature glass substrates due to rapid thermal anneal (RTA treatment and subsequent remote microwave hydrogen plasma passivation (hydrogenation are examined. Voc improvements from 130 mV to 430 mV, Jsc improvements from 1.2 mA/cm2 to 11.3 mA/cm2, and peak IQE improvements from 16% to > 70% are achieved. A 1-second RTA plateau at 1000°C followed by hydrogenation increases the Jsc by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion length of at least 1 μm due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and Voc due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance.

  1. Fermentative hydrogen production from cassava stillage by mixed anaerobic microflora: Effects of temperature and pH

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Gang; Xie, Li; Zou, Zhonghai; Zhou, Qi [Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), UNEP-Tongji, Tongji University, Siping Road No. 1239, Shanghai 200092 (China); Wang, Jing-Yuan (School of Civil and Environmental Engineering, Nanyang Technological University, N1-01b-45, 50 Nanyang Avenue, 639798 Singapore)

    2010-12-15

    Fermentative hydrogen production from cassava stillage was conducted to investigate the influences of temperature (37 C, 60 C, 70 C) and initial pH (4-10) in batch experiments. Although the seed sludge was mesophilic anaerobic sludge, maximum hydrogen yield (53.8 ml H{sub 2}/gVS) was obtained under thermophilic condition (60 C), 53.5% and 198% higher than the values under mesophilic (37 C) and extreme-thermophilic (70 C) conditions respectively. The difference was mainly due to the different VFA and ethanol distributions. Higher hydrogen production corresponded with higher ratios of butyrate/acetate and butyrate/propionate. Similar hydrogen yields of 66.3 and 67.8 ml H{sub 2}/gVS were obtained at initial pH 5 and 6 respectively under thermophilic condition. The total amount of VFA and ethanol increased from 3536 to 7899 mg/l with the increase of initial pH from 4 to 10. Initial pH 6 was considered as the optimal pH due to its 19% higher total VFA and ethanol concentration than that of pH 5. Homoacetogenesis and methonogenesis were very dependent on the initial pH and temperature even when the inoculum was heat-pretreated. Moreover, a difference between measured and theoretical hydrogen was observed in this study, which could be attributed to homoacetogenesis, methanogenesis and the degradation of protein. (author)

  2. Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

    OpenAIRE

    A. Sattar; C. Arslan; C. Ji; S. Sattar; K. Yousaf; S. Hashim

    2015-01-01

    The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen productio...

  3. Techno-economic study of hydrogen production by high temperature electrolysis and coupling with different thermal energy sources

    International Nuclear Information System (INIS)

    Rivera-Tinoco, R.

    2009-03-01

    This work focuses on the techno-economic study of massive hydrogen production by the High Temperature Electrolysis (HTE) process and also deals with the possibility of producing the steam needed in the process by using different thermal energy sources. Among several sources, those retained in this study are the biomass and domestic waste incineration units, as well as two nuclear reactors (European Pressurised water Reactor - EPR and Sodium Fast Reactor - SFR). Firstly, the technical evaluation of the steam production by each of these sources was carried out. Then, the design and modelling of the equipments composing the process, specially the electrolysers (Solid Oxides Electrolysis Cells), are presented. Finally, the hydrogen production cost for each energy sources coupled with the HTE process is calculated. Moreover, several sensibility studies were performed in order to determine the process key parameter and to evaluate the influence of the unit size effect, the electric energy cost, maintenance, the cells current density, their investment cost and their lifespan on the hydrogen production cost. Our results show that the thermal energy cost is much more influent on the hydrogen production cost than the steam temperature at the outlet stream of the thermal source. It seems also that the key parameters for this process are the electric energy cost and the c ells lifespan. The first one contributes for more than 70% of the hydrogen production cost. From several cell lifespan values, it seems that a 3 year value, rather than 1 year, could lead to a hydrogen production cost reduced on 34%. However, longer lifespan values going from 5 to 10 years would only lead to a 8% reduction on the hydrogen production cost. (author)

  4. The lithium-lithium hydride process for the production of hydrogen: comparison of two concepts for 950 and 1300 deg C HTR helium outlet temperature

    International Nuclear Information System (INIS)

    Oertel, M.; Weirich, W.; Kuegler, B.; Luecke, L.; Pietsch, M.; Winkelmann, U.

    1987-01-01

    The lithium-lithium hydride process serves to generate hydrogen from water efficiently, using the high temperature heat of a nuclear reactor. Thermodynamic analyses show that hydrogen can be produced with an overall thermal efficiency of 48% at conventional HTR outlet temperatures of 950 0 C. Assuming helium heat of 1300 0 C, 56% overall thermal efficiency can be achieved. (author)

  5. UO{sub 2} surface oxidation by mixtures of water vapor and hydrogen as a function of temperature

    Energy Technology Data Exchange (ETDEWEB)

    Espriu-Gascon, A., E-mail: alexandra.espriu@upc.edu [Department of Chemical Engineering, Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Llorca, J.; Domínguez, M. [Institut de Tècniques Energètiques (INTE), Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE), Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Giménez, J.; Casas, I. [Department of Chemical Engineering, Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Pablo, J. de [Department of Chemical Engineering, Universitat Politècnica Catalunya-Barcelona Tech, Diagonal 647, E-08028 Barcelona (Spain); Fundació CTM Centre Tecnològic, Plaça de la Ciència 2, E-08243 Manresa (Spain)

    2015-12-15

    In the present work, X-Ray Photoelectron Spectroscopy (XPS) was used to study the effect of water vapor on the UO{sub 2} surface as a function of temperature. The experiments were performed in situ inside a high pressure chamber attached to the XPS instrument. UO{sub 2} samples were put in contact with either hydrogen or argon streams, saturated with water at room temperature, and the sample surface evolution was analyzed by XPS. In the case of the water vapor/argon experiments, one experiment at 350 °C was performed and, in the case of the water vapor/hydrogen experiments, the temperatures used inside the reactor were 60, 120, 200 and 350 °C. On one hand, in presence of argon, the results obtained showed that the water vapor in the argon stream oxidized 93% of the U(IV) in the sample surface. On the other hand, the degree of UO{sub 2} surface oxidation showed a different dependence on the temperature in the experiments performed in the presence of hydrogen: the maximum surface oxidation occurred at 120 °C, where 65.4% of U(IV) in the sample surface was oxidized, while at higher temperatures, the surface oxidation decreased. This observation is attributed to the increase of hydrogen reducing effect when temperature increases which prevents part of the oxidation of the UO{sub 2} surface by the water vapor. - Highlights: • UO{sub 2} surface has been oxidized by water vapor in an argon stream at 350 °C. • H{sub 2} reduced more uranium oxidation produced by water at 350 °C when compared to Ar. • In H{sub 2} presence, the uranium oxidation produced by water depends on the temperature.

  6. Site-Specific Hydrogen Isotope Composition of Propane: Mass spectrometric methods, equilibrium temperature dependence, and kinetics of exchange

    Science.gov (United States)

    Xie, H.; Ponton, C.; Kitchen, N.; Lloyd, M. K.; Lawson, M.; Formolo, M. J.; Eiler, J. M.

    2016-12-01

    Intramolecular isotope ordering can constrain temperatures of synthesis, mechanisms of formation, and/or source substrates of organic compounds. Here we explore site-specific hydrogen isotope variations of propane. Statistical thermodynamic models predict that at equilibrium methylene hydrogen (-CH2-) in propane will be 10's of per mil higher in D/H ratio than methyl hydrogen (-CH3) at geologically relevant temperatures, and that this difference is highly temperature dependent ( 0.5-1 ‰/°C). Chemical-kinetic controls on site-specific D/H in propane could constrain the mechanisms, conditions and extents of propane synthesis or destruction. We have developed a method for measuring the difference in D/H ratio between methylene and methyl hydrogen in propane by gas source mass spectrometry. The data were measured using the Thermo Fisher Double Focusing Sector high resolution mass spectrometer (DFS), and involve comparison of the D/H ratios of molecular ion (C3H8+) and the ethyl fragmental ion (C2H5+). We demonstrate the accuracy and precision of this method through analysis of D-labeled and independently analyzed propanes. In the exchange experiments, propane was heated (100-200 oC) either alone or in the presence of D-enriched water (δD=1,1419 ‰ SMOW), with or without one of several potentially catalytic substrates for hours to weeks. Propane was found to exchange hydrogen with water vigorously at 200 °C in the presence of metal catalysts. In the presence of Ni catalyst, methylene hydrogen exchanges 2.5 times faster than methyl hydrogen. Hydrogen exchange in the presence of Pd catalyst is more effective and can equilibrate hydrogen isotope distribution on propane on the order of 7 days. Isotopic exchange in the presence of natural materials have also been tested, but is only measurable in the methylene group at 200 °C. High catalytic activity of Pd permits attainment of a bracketed, time-invariant equilibrium state that we use to calibrate the site

  7. Photochemically engineering the metal-semiconductor interface for room-temperature transfer hydrogenation of nitroarenes with formic acid.

    Science.gov (United States)

    Li, Xin-Hao; Cai, Yi-Yu; Gong, Ling-Hong; Fu, Wei; Wang, Kai-Xue; Bao, Hong-Liang; Wei, Xiao; Chen, Jie-Sheng

    2014-12-08

    A mild photochemical approach was applied to construct highly coupled metal-semiconductor dyads, which were found to efficiently facilitate the hydrogenation of nitrobenzene. Aniline was produced in excellent yield (>99 %, TOF: 1183) using formic acid as hydrogen source and water as solvent at room temperature. This general and green catalytic process is applicable to a wide range of nitroarenes without the involvement of high-pressure gases or sacrificial additives. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Hydrogen dynamics in the low temperature phase of LiBH{sub 4} probed by quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Remhof, Arndt, E-mail: arndt.remhof@empa.ch [Empa, Swiss Federal Institute for Materials Science and Technology, Hydrogen and Energy, CH-8600 Dübendorf (Switzerland); Züttel, Andreas [Empa, Swiss Federal Institute for Materials Science and Technology, Hydrogen and Energy, CH-8600 Dübendorf (Switzerland); Ramirez-Cuesta, Timmy; García-Sakai, Victoria [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Frick, Bernhard [Institut Laue-Langevin, F-38002 Grenoble (France)

    2013-12-12

    Highlights: • Inelastic fixed window sans offer new possibilities in neutron backscattering spectrometers. • Two different kind of reorientational motion were identified in the low temperature phase of LiBH{sub 4}. • Thermally activated jump rotation. - Abstract: LiBH{sub 4} contains 18.5 wt% hydrogen and undergoes a structural phase transition (orthorhombic → hexagonal) at 381 K which is associated with a large increase in hydrogen and lithium solid-state mobility. We investigated the hydrogen dynamics in the low temperature phase of LiBH{sub 4} by quasielastic neutron scattering, including a new kind of inelastic fixed window scan (IFWS). In the temperature range from 175 to 380 K the H-dynamics is dominated by thermally activated rotational jumps of the [BH{sub 4}]{sup −} anion around the c3 axis with an activation energy of about 162 meV. In agreement with earlier NMR data, a second type of thermally activated motion with an activation energy of about 232 meV could be identified using the IFWS. The present study of hydrogen dynamics in LiBH{sub 4} illustrates the feasibility of using IFWS on neutron backscattering spectrometers as a probe of localised motion.

  9. Hydrogen production by high-temperature electrolysis of water vapor steam. Test results obtained with an electrolysis tube

    International Nuclear Information System (INIS)

    Hino, Ryutaro; Miyamoto, Yoshiaki

    1995-01-01

    High-temperature electrolysis of water vapor steam is an advanced hydrogen production process decomposing high temperature steam up to 1,000degC, which applies an electro-chemical reaction reverse to the solid oxide fuel cell. At Japan Atomic Energy Research Institute, laboratory-scale experiments have been conducted using a practical electrolysis tube with 12 electrolysis cells in order to develop heat utilization systems for high-temperature gas-cooled reactors. The electrolysis cells of which electrolyte was yttria-stabilized zirconia were formed on a porous ceramic tube in series by plasma spraying. In the experiments, water steam mixed with argon carrier gas was supplied into the electrolysis tube heated at a constant temperature regulated in the range from 850degC to 950degC, and electrolysis power was supplied by a DC power source. Hydrogen production rate increased with applied voltage and electrolysis temperature; the maximum production rate was 6.9Nl/h at 950degC. Hydrogen production rate was correlated with applied current densities on the basis of experimental data. High energy efficiency was achieved under the applied current density ranging from 80 to 100 mA/cm 2 . (author)

  10. Low temperature internal friction in pure iron charged with hydrogen or deuterium

    International Nuclear Information System (INIS)

    Moser, P.; Dufresne, J.F.; Ritchie, I.G.

    1977-01-01

    The search for the elusive hydrogen Snoek-peak in pure iron has been continued with specimens charged with either hydrogen or deuterium. The peaks observed are attributed to deformation produced during charging and can be classified as an α-type peak and a Snoek-Koester type peak. The detailed behavior of these peaks during systematic outgassing of hydrogen or deuterium is described

  11. Heart Attack Recovery FAQs

    Science.gov (United States)

    ... recommendations to make a full recovery. View an animation of a heart attack . Heart Attack Recovery Questions ... Support Network Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  12. Determinations of the temperature of terminal solid solubility in dissolution and precipitation of hydrogen/deuterium in irradiated Zircaloy-4

    Energy Technology Data Exchange (ETDEWEB)

    Vizcaino, P [CNEA-CONICET, Centro Atomico Ezeiza (Argentina)

    2012-07-01

    The proposed plan is an approach to the metallurgical consequences of the high neutron fluencies (10''2''2 n/cm''2) on the hydrogen behavior in zirconium based alloys, based on the significance of the microstructural behavior of the high burn up fuel claddings during the dry storage period. The studies are focused on Zircaloy-4, concerning to two processes: Neutron irradiation damage; Hydrogen pick up. The Zircaloy-4 was taken from cooling channels of the PHWR Atucha 1. These components remained more than 10 years in service, reaching neutron fluencies up to 10''2''2 n/cm''2. In the last recent years, measurements of the hydride dissolution temperatures have shown that hydrogen solubility is affected by the neutron irradiation, increasing it respect to the unirradiated Zircaloy solubility. In addition, in this material the amorphization/dissolution of the second phase particles (SPPs) was observed, being proposed an interaction between the hydrogen atoms, the SPPs and the irradiation defects as a possible explanation of the observed behavior. For the present case, attention will be focused on the hydride precipitation process, since it is strongly related with delay hydrogen cracking initiation, a problem of direct concern for the dry storage. The goal of the present proposal is to make an approach to the source of the observed effect, applying several specific techniques as differential scanning calorimetry (DSC), high resolution x-ray diffraction and transmission electron microscopy. The objectives can be divided as follows: Determination of the temperatures of terminal solid solubility in dissolution (TTSSd) and in precipitation (TTSSp) in high fluency irradiated Zircaloy-4, reproducing the temperatures at which the Zircaloy fuel claddings remain during dry storage by an annealing program during the DSC experiments; Observations by optical and transmission electron microscopy of the hydride distribution before (as received material) and after high temperature

  13. Continuous high-temperature surveillance instrumentation for Dresden-2 hydrogen water chemistry program

    International Nuclear Information System (INIS)

    Fleming, M.F.; Mitchell, R.A.; Nelson, J.L.

    1987-01-01

    The objective of this program (under EPRI Contract RP1930-11) is to install and operate a high-temperature surveillance instrumentation system capable of monitoring the length of cracks in boiling water reactor (BWR) piping during plant operation. The ability to measure crack growth in BWR power plant piping welds is important to rapidly identify the effectiveness of repairs (such as the Hydrogen Water Chemistry Program). The feasibility of a system capable of continuous ultrasonic instrumentation at 600 0 F (288 0 C) was successfully demonstrated at the Dresden-2 suction line known as N1B. This intergranular stress corrosion cracking (IGSCC) surveillance instrumentation is sound in principal, because it survived on N1B for a time period of more than nine months from April 1985 to January 1986 (the last time data were recorded). The redesigned low-profile transducer system used for this system operated successfully for the same nine-month time period. This low profile transducer fits in the two-inch space normally occupied by insulation. As a result of poor routing of the coaxial cables running from the low-profile transducer to the electrical feed-throughs between the drywell and containment, these cables melted. Other instrument cables nearby were not damaged

  14. The effect of temperature and effluent recycle rate on hydrogen production by undefined bacterial granules.

    Science.gov (United States)

    Ngoma, L; Masilela, P; Obazu, F; Gray, V M

    2011-10-01

    Biohydrogen production in an anaerobic fluidized granular bed bioreactor was strongly dependent on temperature and effluent recycle rates. At 45 °C as the effluent recycle rate was increased from 1.3 to 3.5 L/min, the total H₂ output for the bioreactor increased from 10.6 to 43.2 L/h. Volumetric H(2) productivity also increased from 2.1 to 8.7 L H₂/L/h. At 70°C as the effluent recycle was increased from 1.3 to 3.5 L/min, the total H₂ output for the bioreactor increased from 13.8 to 73.8L/h. At 70 °C volumetric H(2) productivities increased from 2.8 to 14.8L H₂/L/h as the effluent recycle rate was increased from 1.3 to 3.5 L/min. At 45 °C % H₂ was 45% and reached 67% at 70 °C. Maximum hydrogen yields at 45 °C were 1.24 and 2.2 mol H₂/mol glucose at 70 °C. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Simonkolleite nano-platelets: Synthesis and temperature effect on hydrogen gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Sithole, J. [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa); Dept. of Physics, University of Western Cape, Private Bag X 17, Belleville (South Africa); Ngom, B.D., E-mail: bdngom@tlabs.ac.za [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa) and African Laser Centre, CSIR campus, P.O. Box 395, Pretoria (South Africa); Laboratoire de Photonique et de Nano-Fabrication, Groupe de Physique du Solide et Sciences des Materiaux, Departement de Physique Facultes des Sciences et Technique Universite Cheikh Anta Diop de Dakar, Dakar (Senegal); Khamlich, S. [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa); African Laser Centre, CSIR campus, P.O. Box 395, Pretoria (South Africa); Manikanadan, E. [National Centre for Nano-Structured Materials (NCNSM), Council for Scientific and Industrial Research, Pretoria (South Africa); Manyala, N. [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa); Saboungi, M.L. [Centre de Recherche sur la Matiere Divisee, CNRS-Orleans, Orleans (France); Knoessen, D. [Dept. of Physics, University of Western Cape, Private Bag X 17, Belleville (South Africa); Nemutudi, R.; Maaza, M. [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa)

    2012-08-01

    In this work, the new refined mineral platelets-like morphology of simonkolleite based particles described by Shemetzer et al. (1985) were synthesized in zinc nitrate aqueous solution by a moderate solution process. The morphological and structural properties of the platelets-like Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}H{sub 2}O were characterized by scanning electron microscope energy dispersed X-ray spectroscopy, transmission electron microscope, powder X-ray diffraction and selected area electron diffraction as well as attenuated total reflection infrared spectroscopy. The morphology as well as the size in both basal and transversal directions of the simonkolleite Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}H{sub 2}O nano/micro crystals was found to be significantly depending on the specific concentration of 0.1 M of Zn{sup 2+}/Cl{sup -} ions in the precursor solution. The simonkolleite Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}H{sub 2}O nano-platelets revealed a significant and singular H{sub 2} gas sensing characteristics. The operating temperature was found to play a key role on the sensing properties of simonkolleite. The effect of temperature on the simonkolleite sample as a hydrogen gas sensor was studied by recording the change in resistivity of the film in presence of the test gas. The results on the sensitivity and response time as per comparison to earlier reported ZnO based sensors are indicated and discussed.

  16. Hydrogen isotope exchange of organic compounds in dilute acid at elevated temperatures

    International Nuclear Information System (INIS)

    Werstiuk, N.H.

    1987-01-01

    Introduction of one or more deuterium (or tritium) atoms into organic molecules can be accomplished in many ways depending on the nature of the substrate and the extent and sterochemistry of deuteriation or tritiation required. Some of the common methods include acid- and base-catalyzed exchange of carbonyl compounds, metal hydride reductions, dissolving metal reductions, catalytic reduction of double bonds, chromatographic exchange, homogeneous and heterogeneous metal-catalyzed exchange, base-catalyzed exchange of carbon acids other than carbonyl compounds and acid-catalyzed exchange via electrophilic substitution. Only the latter three methods have been used for perdeuteriation of organic compounds. A very useful compendium of labeling methods with examples has been available to chemists for some time. Although metal-catalyzed exchange has been used extensively, the method suffers from some deficiencies: irreproducibility of catalyst surfaces, catalyst poisoning, side reactions such as coupling and hydrogenolysis of labile groups and low deuterium incorporation. Usually a number of cycles are required with fresh catalyst and fresh deuterium source to achieve substantial isotope incorporation. Acid-catalyzed exchange of aromatics and alkenes, strongly acidic media such as liquid DBr, concentrated DBr, acetic acid/stannic chloride, concentrated D 3 PO 4 , concentrated DC1, D 3 PO 4 /BF 3 SO 2 , 50-80% D 2 SO 4 and DFSO 4 /SbF 5 at moderate temperatures (<100 degrees) have been used to effect exchange. The methods are not particularly suitable for large scale deuteriations because of the cost and the fact that the recovery and upgrading of the diluted deuterium pool is difficult. This paper describes the hydrogen isotope exchange of a variety of organic compounds in dilute aqueous acid (0.1-0.5 M) at elevated temperatures (150-300 degrees)

  17. Hydrogen bond network relaxation in aqueous polyelectrolyte solutions: the effect of temperature

    International Nuclear Information System (INIS)

    Sarti, S; Bordi, F; Truzzolillo, D

    2012-01-01

    Dielectric spectroscopy data over the range 100 MHz-40 GHz allow for a reliable analysis of two of the major relaxation phenomena for polyelectrolytes (PE) in water. Within this range, the dielectric relaxation of pure water is dominated by a near-Debye process at ν = 18.5 GHz corresponding to a relaxation time of τ = 8.4 ps at 25 °C. This mode is commonly attributed to the cooperative relaxation specific to liquids forming a hydrogen bond network (HBN) and arising from long range H-bond-mediated dipole-dipole interactions. The presence of charged polymers in water partially modifies the dielectric characteristics of the orientational water molecule relaxation due to a change of the dielectric constant of water surrounding the charges on the polyion chain. We report experimental results on the effect of the presence of a standard flexible polyelectrolyte (sodium polyacrylate) on the HBN relaxation in water for different temperatures, showing that the HBN relaxation time does not change by increasing the polyelectrolyte density in water, even if relatively high concentrations are reached (0.02 monomol l -1 ≤ C ≤ 0.4 monomol l -1 ). We also find that the effect of PE addition on the HBN relaxation is not even a broadening of its distribution, rather a decrease of the spectral weight that goes beyond the pure volume fraction effect. This extra decrease is larger at low T and less evident at high T, supporting the idea that the correlation length of the water is less affected by the presence of charged flexible chains at high temperatures. (paper)

  18. Mapping temperature-induced conformational changes in the Escherichia coli heat shock transcription factor sigma 32 by amide hydrogen exchange

    DEFF Research Database (Denmark)

    Rist, Wolfgang; Jørgensen, Thomas J D; Roepstorff, Peter

    2003-01-01

    Stress conditions such as heat shock alter the transcriptional profile in all organisms. In Escherichia coli the heat shock transcription factor, sigma 32, out-competes upon temperature up-shift the housekeeping sigma-factor, sigma 70, for binding to core RNA polymerase and initiates heat shock...... gene transcription. To investigate possible heat-induced conformational changes in sigma 32 we performed amide hydrogen (H/D) exchange experiments under optimal growth and heat shock conditions combined with mass spectrometry. We found a rapid exchange of around 220 of the 294 amide hydrogens at 37...... degrees C, indicating that sigma 32 adopts a highly flexible structure. At 42 degrees C we observed a slow correlated exchange of 30 additional amide hydrogens and localized it to a helix-loop-helix motif within domain sigma 2 that is responsible for the recognition of the -10 region in heat shock...

  19. Hydrogen detector

    International Nuclear Information System (INIS)

    Kumagaya, Hiromichi; Yoshida, Kazuo; Sanada, Kazuo; Chigira, Sadao.

    1994-01-01

    The present invention concerns a hydrogen detector for detecting water-sodium reaction. The hydrogen detector comprises a sensor portion having coiled optical fibers and detects hydrogen on the basis of the increase of light transmission loss upon hydrogen absorption. In the hydrogen detector, optical fibers are wound around and welded to the outer circumference of a quartz rod, as well as the thickness of the clad layer of the optical fiber is reduced by etching. With such procedures, size of the hydrogen detecting sensor portion can be decreased easily. Further, since it can be used at high temperature, diffusion rate is improved to shorten the detection time. (N.H.)

  20. Gold Supported on Graphene Oxide: An Active and Selective Catalyst for Phenylacetylene Hydrogenations at Low Temperatures

    DEFF Research Database (Denmark)

    Shao, Lidong; Huang, Xing; Teschner, Detre

    2014-01-01

    A constraint to industrial implementation of gold-catalyzed alkyne hydrogenation is that the catalytic activity was always inferior to those of other noble metals. In this work, gold was supported on graphene oxide (Au/GO) and used in a hydrogenation application. A 99% selectivity toward styrene...

  1. Hydrogen-rich gas production from waste plastics by pyrolysis and low-temperature steam reforming over a ruthenium catalyst

    International Nuclear Information System (INIS)

    Namioka, Tomoaki; Saito, Atsushi; Inoue, Yukiharu; Park, Yeongsu; Min, Tai-jin; Roh, Seon-ah; Yoshikawa, Kunio

    2011-01-01

    Operating conditions for low-temperature pyrolysis and steam reforming of plastics over a ruthenium catalyst were investigated. In the range studied, the highest gas and lowest coke fractions for polystyrene (PS) with a 60 g h -1 scale, continuous-feed, two-stage gasifier were obtained with a pyrolyzer temperature of 673 K, steam reforming temperature of 903 K, and weight hourly space velocity (WHSV) of 0.10 g-sample g-catalyst -1 h -1 . These operating conditions are consistent with optimum conditions reported previously for polypropylene. Our results indicate that at around 903 K, the activity of the ruthenium catalyst was high enough to minimize the difference between the rates of the steam reforming reactions of the pyrolysates from polystyrene and polypropylene. The proposed system thus has the flexibility to compensate for differences in chemical structures of municipal waste plastics. In addition, the steam reforming temperature was about 200 K lower than the temperature used in a conventional Ni-catalyzed process for the production of hydrogen. Low-temperature steam reforming allows for lower thermal input to the steam reformer, which results in an increase in thermal efficiency in the proposed process employing a Ru catalyst. Because low-temperature steam reforming can be also expected to reduce thermal degradation rates of the catalyst, the pyrolysis-steam reforming process with a Ru catalyst has the potential for use in small-scale production of hydrogen-rich gas from waste plastics that can be used for power generation.

  2. Life cycle assessment of hydrogen production from S-I thermochemical process coupled to a high temperature gas reactor

    Energy Technology Data Exchange (ETDEWEB)

    Giraldi, M. R.; Francois, J. L.; Castro-Uriegas, D. [Departamento de Sistemas Energeticos, Facultad de Ingenieria, Universidad Nacional Autonoma de Mexico, Paseo Cuauhnahuac No. 8532, Col. Progreso, C.P. 62550, Jiutepec, Morelos (Mexico)

    2012-07-01

    The purpose of this paper is to quantify the greenhouse gas (GHG) emissions associated to the hydrogen produced by the sulfur-iodine thermochemical process, coupled to a high temperature nuclear reactor, and to compare the results with other life cycle analysis (LCA) studies on hydrogen production technologies, both conventional and emerging. The LCA tool was used to quantify the impacts associated with climate change. The product system was defined by the following steps: (i) extraction and manufacturing of raw materials (upstream flows), (U) external energy supplied to the system, (iii) nuclear power plant, and (iv) hydrogen production plant. Particular attention was focused to those processes where there was limited information from literature about inventory data, as the TRISO fuel manufacture, and the production of iodine. The results show that the electric power, supplied to the hydrogen plant, is a sensitive parameter for GHG emissions. When the nuclear power plant supplied the electrical power, low GHG emissions were obtained. These results improve those reported by conventional hydrogen production methods, such as steam reforming. (authors)

  3. Examining the temperature behavior of stainless steel surfaces exposed to hydrogen plasmas in the Lithium Tokamak eXperiment (LTX)

    Science.gov (United States)

    Bedoya, Felipe; Allain, Jean Paul; Kaita, Robert; Lucia, Matthew; St-Onge, Denis; Ellis, Robert; Majeski, Richard

    2014-10-01

    The Materials Analysis Particle Probe (MAPP) is an in-situ diagnostic designed to characterize plasma-facing components (PFCs) in tokamak devices. MAPP is installed in LTX at Princeton Plasma Physics Laboratory. MAPP's capabilities include remotely operated XPS acquisition and temperature control of four samples. The recent addition of a focused ion beam allows XPS depth profiling analysis. Recent published results show an apparent correlation between hydrogen retention and temperature of Li coated stainless steel (SS) PFCs exposed to plasmas like those of LTX. According to XPS data, the retention of hydrogen by the coated surfaces decreases at above 180 °C. In the present study MAPP will be used to study the oxidation of Li coatings as a function of time and temperature of the walls when Li coatings are applied. Experiments in the ion-surface interaction experiment (IIAX) varying the hydrogen fluence on the SS samples will be also performed. Conclusions resulting from this study will be key to explain the PFC temperature-dependent variation of plasma performance observed in LTX. This work was supported by U.S. DOE Contracts DE-AC02-09CH11466, DE-AC52-07NA27344 and DE-SC0010717.

  4. Low temperature processed InGaZnO thin film transistor using the combination of hydrogen irradiation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun-Woo; Choi, Min-Jun; Jo, Yongcheol; Chung, Kwun-Bum, E-mail: kbchung@dongguk.edu

    2014-12-01

    Highlights: • We studied the low temperature process of InGaZnO oxide thin film transistor. • Hydorgen irradiation was used for low temperature process below 150 °C. • Using hydrogen irradiation, field effect mobility of IGZO TFT was enhanced to ∼5 cm{sup 2} /Vs. • We examined the origin of improvement of device performance via electronic structure. - Abstract: Device performance of radio frequency (RF) sputtered InGaZnO (IGZO) thin film transistors (TFTs) were improved using combination post-treatment with hydrogen irradiation and low temperature annealing at 150 °C. Under the combination treatment, IGZO TFTs were significantly enhanced without changing physical structure and chemical composition. On the other hand, the electronic structure represents a dramatically modification of the chemical bonding states, band edge states below the conduction band, and band alignment. Compared to the hydrogen irradiation or low temperature annealing, the combination treatment induces the increase of oxygen deficient chemical bonding states, the shallow band edge state below the conduction band, and the smaller energy difference of conduction band offset, which can generate the increase in charge carrier and enhance the device performance.

  5. Hydrogen pellet ablation and accelerator by current in high temperature plasmas

    International Nuclear Information System (INIS)

    Kuteev, B.V.

    1995-01-01

    Hydrogen pellet ablation and acceleration by current in high temperature plasmas are analyzed. The present state of ablation theory and experiment is discussed and an ablation model is formulated. This model takes into account the energy distribution of the particles (both electrons and ions) participating in the ablation process, electrostatic effects of the cloud charging and changes of the pellet form during ablation. Without charging the pellet form tends to a shape resembling a lentil while it remains almost spherical if charged. A new algorithm for ablation rate calculations that can be used for an arbitrary initial form of the pellet is described. The results of this kinetic two dimensional approach differ from those of the Parks ablation scaling used in the ITER design by not more than 30%. Plasma shielding effects are not significant in the ablation if strong turbulence in the cloud is taken into account. Acceleration analysis is based on the Braginskii corrected electron distribution function. For the lentil mode of ablation, acceleration is higher than those for the charged mode by a factor of 1.76. The ablation models are compared with the experiments on T-10, JET, TFTR, Heliotron-E and Tore Supra. A sensitivity analysis shows that pellet size and electron temperature are the most significant factors for determination of the penetration length. The available database of penetration lengths is not sufficient for distinguishing between the models. Acceleration for the charged model correlates with experimental data better than that for the lentil mode. The effect of the hot ions is seen on the ablation. Finally, ablation at reactor relevant plasma and pellet parameters is considered. This range of the plasma parameters needs a correction of the ablation scaling as follows: dN/dt ∼ n 0.453 e T 1.72 e r 1.443 p M -0.283 i , where n e and T e are the electron density and temperature, respectively, and r p and M i are the pellet radius and atomic mass

  6. High-temperature hydrogenation of pure and silver-decorated titanate nanotubes to increase their solar absorbance for photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Plodinec, Milivoj [Ruđer Bošković Institute, Bijenička 54, HR-1002 Zagreb (Croatia); Gajović, Andreja, E-mail: gajovic@irb.hr [Ruđer Bošković Institute, Bijenička 54, HR-1002 Zagreb (Croatia); Jakša, Gregor; Žagar, Kristina; Čeh, Miran [Institute Jožef Stefan, Jamova 39, 1000 Ljubljana (Slovenia)

    2014-04-05

    Graphical abstract: The aim of the work is to study how annealing in a reducing atmosphere of titanate nanotubes (TiNT) and Ag decorated titanate nanotubes (TiNT@Ag) influenced on their structure, morphology, phase transitions, UV–ViS-NIR absorbance and photocatalytic activity. An increase of photocatalytic activity after a heat treatment in a reducing atmosphere was observed in the TiNT and TiNT@Ag. We found that the hydrogenated TiNT@Ag samples (TiNT@Ag-HA) had a two-times higher photodegradation impact on the caffeine than the TiNT samples, which is a consequence of the increased absorption of visible light and the synergetic effects between the silver and the TiO{sub 2} nanoparticles that increase the efficiency of the formation of electron–hole pairs and the charge transfer to the surface of the nanoparticles. -- Highlights: • Titanate nanotubes with and without Ag nanoparticles were hydrogenated at 550 °C. • TiO{sub 2} nanostructures obtained by hydrogenation have core–shell structure. • Hydrogenated samples show absorption in the visible spectral region. • Hydrogenated Ag decorated sample show stronger absorption in visible than in UV. • Photocatalytic efficiency is improved by hydrogenation and by Ag nanoparticles. -- Abstract: Titanate nanotubes (TiNTs) and silver-decorated titanate nanotubes (TiNTs@Ag) were synthesized using the hydrothermal method. In the decorated nanotubes the silver particles were obtained by the photoreduction of AgNO{sub 3} under UV light. Pure and Ag-decorated nanotubes were high-temperature heat treated at 550 °C in a hydrogen atmosphere and the “core–shell”-structured TiO{sub 2} nanoparticles were formed. For the structural characterization of all the titanate nanostructures we used conventional and analytical transmission electron microscopy (TEM) techniques, X-ray diffraction (XRD) and Raman spectroscopy. The Ag-decorated titanate nanostructures were additionally studied by X-ray photo

  7. Bio-oil Stabilization by Hydrogenation over Reduced Metal Catalysts at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huamin; Lee, Suh-Jane; Olarte, Mariefel V.; Zacher, Alan H.

    2016-08-30

    Biomass fast pyrolysis integrated with bio-oil upgrading represents a very attractive approach for converting biomass to hydrocarbon transportation fuels. However, the thermal and chemical instability of bio-oils presents significant problems when they are being upgraded, and development of effective approaches for stabilizing bio-oils is critical to the success of the technology. Catalytic hydrogenation to remove reactive species in bio-oil has been considered as one of the most efficient ways to stabilize bio-oil. This paper provides a fundamental understanding of hydrogenation of actual bio-oils over a Ru/TiO2 catalyst under conditions relevant to practical bio-oil hydrotreating processes. Bio-oil feed stocks, bio-oils hydrogenated to different extents, and catalysts have been characterized to provide insights into the chemical and physical properties of these samples and to understand the correlation of the properties with the composition of the bio-oil and catalysts. The results indicated hydrogenation of various components of the bio-oil, including sugars, aldehydes, ketones, alkenes, aromatics, and carboxylic acids, over the Ru/TiO2 catalyst and 120 to 160oC. Hydrogenation of these species significantly changed the chemical and physical properties of the bio-oil and overall improved its thermal stability, especially by reducing the carbonyl content, which represented the content of the most reactive species (i.e., sugar, aldehydes, and ketones). The change of content of each component in response to increasing hydrogen additions suggests the following bio-oil hydrogenation reaction sequence: sugar conversion to sugar alcohols, followed by ketone and aldehyde conversion to alcohols, followed by alkene and aromatic hydrogenation, and then followed by carboxylic acid hydrogenation to alcohols. Hydrogenation of bio-oil samples with different sulfur contents or inorganic material contents suggested that sulfur poisoning of the reduced Ru metal catalysts was

  8. Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

    Energy Technology Data Exchange (ETDEWEB)

    Mashovets, N.S., E-mail: mashovets@rambler.ru [Khmelnickiy National University (Ukraine); Pastukh, I.M., E-mail: pastim@mail.ru [Khmelnickiy National University (Ukraine); Voloshko, S.M. [Khmelnickiy National University (Ukraine); National Technical University of Ukraine “Kyiv Polytechnic Institute” (Ukraine)

    2017-01-15

    Highlights: • Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. • Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). • The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. - Abstract: X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples’ argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm{sup 2}. The above material shows the promise of the technology of low-temperature

  9. Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

    International Nuclear Information System (INIS)

    Mashovets, N.S.; Pastukh, I.M.; Voloshko, S.M.

    2017-01-01

    Highlights: • Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. • Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). • The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. - Abstract: X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples’ argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm 2 . The above material shows the promise of the technology of low-temperature

  10. Experimental researches on hydrogen generation by aluminum with adding lithium at high temperature

    International Nuclear Information System (INIS)

    Yang, Weijuan; Zhang, Tianyou; Liu, Jianzhong; Wang, Zhihua; Zhou, Junhu; Cen, Kefa

    2015-01-01

    In order to recover the released heat of Al–H_2O reaction and promote the reaction itself, the hydrogen production processes of aluminum with lithium addition in molten state are investigated. Experiments are conducted by both a thermogravimetric analyzer and a special experimental facility at high temperature. The results on both apparatuses show that the addition of Li can promote the reactivity of aluminum with water. Compared with pure aluminum, only 5% of Li content can achieve a great improvement: the H_2 yield increases from 8.7% to 53% and the average H_2 generation rate from 15 to 112 mL min"−"1 g"−"1. With the increase of Li content, H_2 yield is improved distinctly and the period with a high H_2 generation rate is prolonged. In the Al–20%Li case, the H_2 yield of 88% is obtained, and it appears a stable period in which the H_2 generation rate keeps high. When adding lithium, LiAlO_2 appears in the products and the products are made of columnar crystals. The pores with an average size of 17–33 nm in the LiAlO_2 products are manyfold bigger than the pores of alumina, which takes an important role in improving the reactivity of aluminum and water. - Highlights: • The Al–H_2O reaction with Li addition in molten state was researched. • Li addition can achieve a great promotion of H_2 yield and H_2 generation rate. • The Al–20%Li case achieved a H_2 yield of 88%. • With Li addition, LiAlO_2 was detected in the reaction products. • XRD and TEM-EDS results indicated the promoting mechanism of Li.

  11. Inverted Fuel Cell: Room-Temperature Hydrogen Separation from an Exhaust Gas by Using a Commercial Short-Circuited PEM Fuel Cell without Applying any Electrical Voltage.

    Science.gov (United States)

    Friebe, Sebastian; Geppert, Benjamin; Caro, Jürgen

    2015-06-26

    A short-circuited PEM fuel cell with a Nafion membrane has been evaluated in the room-temperature separation of hydrogen from exhaust gas streams. The separated hydrogen can be recovered or consumed in an in situ olefin hydrogenation when the fuel cell is operated as catalytic membrane reactor. Without applying an outer electrical voltage, there is a continuous hydrogen flux from the higher to the lower hydrogen partial pressure side through the Nafion membrane. On the feed side of the Nafion membrane, hydrogen is catalytically split into protons and electrons by the Pt/C electrocatalyst. The protons diffuse through the Nafion membrane, the electrons follow the short-circuit between the two brass current collectors. On the cathode side, protons and electrons recombine, and hydrogen is released. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Evaluation of the DSC technique in the determination of the terminal temperature solubility of hydrogen in Zircaloy 4

    International Nuclear Information System (INIS)

    Vizcaino, Pablo; Banchik, Abraham D.

    1999-01-01

    The determination of the terminal temperature solubility of hydrogen in the zirconium alloys is a matter of our interest, since the hydride precipitation in these materials make them susceptible to the delay hydrogen cracking (DHC). Nowadays efforts are directed to the determination of this parameter on irradiated materials. In this frame we have begun a program to determine these curves on irradiated zirconium alloys like Zircaloys, Zr 2.5% Nb, Zr 1% Nb, zirconium sponge and high oxygen zirconium with different microstructures using the differential scanning calorimeter technique. The earlier task that we have imposed to us is the evaluation the reproducibility of this technique and the influence of the heating and cooling rates on the results. With these objectives we have initiated this work measuring the terminal temperature solubility (TTS) in unirradiated recrystallized and cold worked Zircaloy-4. We have found that the reproducibility of the technique is good; the average values (TSSD) and (TSSP) agree within the experimental error and the dispersions are low. Variance analysis indicates that the values of TSSD and TSSP do not depend on the heating and cooling rates. Within the rank analyzed the differences in the measurements are only possible to be attributed to statistical and/or experimental errors. The obtained curves of solubility show to a good agreement with the values obtained by others authors until 200 ppm (weight) of hydrogen. Similar comparisons between precipitation curves have not been made in regard to which these values depend on the maximum temperature reached in the experience. (author)

  13. Effect of steam condensation on pressure and temperature under hydrogen jet fire in a vented enclosure

    International Nuclear Information System (INIS)

    Kuznetsov, Mike; Xiao, Jianjun; Travis, Jack

    2017-01-01

    Hydrogen release through leaks due to the LOCA and MCCI accidents and its immediate ignition leads to formation of hydrogen jet fire in a containment of reactor building. An experimental study of hydrogen jet fire in a chamber of 1x1x1 m 3 volume with different vent position, vent areas from 1 to 90 cm 2 and hydrogen mass flow rates from 0.027 to 1.087 g/s were performed in current work. Depending on hydrogen mass flow rate and vent area a well-ventilated or under-ventilated jet fire regime may occur. In the case of relatively small hydrogen release rate and large vent area, relatively stable jet fire behaviour for well-ventilated jet fire leading to over-pressure not more than 0.8 mbar was found. Three different scenarios of under-ventilated jet fire behaviour with self-extinction, re-ignition and external flame leading to relatively high overpressure of 10-100 mbar were found experimentally and numerically. Numerical simulations with GASFLOW-MPI code were performed with/without modelling heat conduction in solid walls, steam condensation, convective heat transfer and thermal radiation. With heat transfer modelling, both initial pressure peak and pressure decay were very well predicted compared to the experimental data. Numerical simulations were then compared with experimental Background Oriented Schlieren (BOS) images obtained to visualize the hydrogen combustion process. Self-extinction and re-ignition events were captured in the numerical simulation as well. An adiabatic case indicates that heat transfer and steam condensation must be included into the combustion model to accurately predict the physical phenomena of turbulent hydrogen jet flames in a vented enclosure. (author)

  14. Effect of Atomic Hydrogen on Preparation of Highly Moisture-Resistive SiNx Films at Low Substrate Temperatures

    Science.gov (United States)

    Heya, Akira; Niki, Toshikazu; Takano, Masahiro; Yonezawa, Yasuto; Minamikawa, Toshiharu; Muroi, Susumu; Minami, Shigehira; Izumi, Akira; Masuda, Atsushi; Umemoto, Hironobu; Matsumura, Hideki

    2004-12-01

    Highly moisture-resistive SiNx films on a Si substrate are obtained at substrate temperatures of 80°C by catalytic chemical vapor deposition (Cat-CVD) using a source gas with H2. Atomic hydrogen effected the selective etching of a weak-bond regions and an increase in atomic density induced by the energy of the surface reaction. It is concluded that Cat-CVD using H2 is a promising candidate for the fabrication of highly moisture-resistive SiNx films at low temperatures.

  15. The diffusion cross section for atomic hydrogen in helium gas at low temperature and the H-He potential

    International Nuclear Information System (INIS)

    Jochemsen, R.; Berlinsky, A.J.; Hardy, W.N.

    1984-01-01

    A calculation of the diffusion cross section Q sub(D) of hydrogen atoms in helium gas at low temperature is performed and compared with recent experimental results. The comparison allows an improved determination of the H-He potential. Calculations were done for three different potentials: our own empirical potential based on experimental high-energy scattering results and calculated long-range dispersion terms, which gives good results for Q sub(D) and total collision cross sections; a recently determined semi-empirical potential, and an ab initio calculated potential. All three potentials imply a strong temperature dependence of Q sub(D) for T < 1.5 K

  16. Thermodynamic diagrams for high temperature plasmas of air, air-carbon, carbon-hydrogen mixtures, and argon

    CERN Document Server

    Kroepelin, H; Hoffmann, K-U

    2013-01-01

    Thermodynamic Diagrams for High Temperature Plasmas of Air, Air-Carbon, Carbon-Hydrogen Mixtures, and Argon provides information relating to the properties of equilibrium gas plasmas formed from hydrocarbons, from air without argon, from pure argon, and from mixtures of air and carbon at various compositions, temperatures and pressures. The data are presented in graphical rather than tabular form to provide a clearer picture of the plasma processes investigated. This book is composed of four chapters, and begins with the introduction to the characteristics of plasmas, with emphasis on their th

  17. Toward hydrogen detection at room temperature with printed ZnO nanoceramics films activated with halogen lighting

    Science.gov (United States)

    Nguyen, Van Son; Jubera, Véronique; Garcia, Alain; Debéda, Hélène

    2015-12-01

    Though semiconducting properties of ZnO have been extensively investigated under hazardous gases, research is still necessary for low-cost sensors working at room temperature. Study of printed ZnO nanopowders-based sensors has been undertaken for hydrogen detection. A ZnO paste made with commercial nanopowders is deposited onto interdigitated Pt electrodes and sintered at 400 °C. The ZnO layer structure and morphology are first examined by XRD, SEM, AFM and emission/excitation spectra prior to the study of the effect of UV-light on the electrical conduction of the semiconductor oxide. The response to hydrogen exposure is subsequently examined, showing that low UV-light provided by halogen lighting enhances the gas response and allows detection at room temperature with gas responses similar to those obtained in dark conditions at 150 °C. A gas response of 44% (relative change in current) under 300 ppm is obtained at room temperature. Moreover, it is demonstrated that very low UV-light power (15 μW/mm2) provided by the halogen lamp is sufficient to give sensitivities as high as those for much higher powers obtained with a UV LED (7.7 mW/mm2). These results are comparable to those obtained by others for 1D or 2D ZnO nanostructures working at room temperature or at temperatures up to 250 °C.

  18. Centrifugal Deposited Au-Pd Core-Shell Nanoparticle Film for Room-Temperature Optical Detection of Hydrogen Gas.

    Science.gov (United States)

    Song, Han; Luo, Zhijie; Liu, Mingyao; Zhang, Gang; Peng, Wang; Wang, Boyi; Zhu, Yong

    2018-05-06

    In the present work, centrifugal deposited Au-Pd core-shell nanoparticle (NP) film was proposed for the room-temperature optical detection of hydrogen gas. The size dimension of 44, 48, 54, and 62 nm Au-Pd core-shell nanocubes with 40 nm Au core were synthesized following a solution-based seed-mediated growth method. Compared to a pure Pd NP, this core-shell structure with an inert Au core could decrease the H diffusion length in the Pd shell. Through a modified centrifugal deposition process, continues film samples with different core-shell NPs were deposited on 10 mm diameter quartz substrates. Under various hydrogen concentration conditions, the optical response properties of these samples were characterized by an intensity-based optical fiber bundle sensor. Experimental results show that the continues film that was composed of 62 nm Au-Pd core-shell NPs has achieved a stable and repeatable reflectance response with low zero drift in the range of 4 to 0.1% hydrogen after a stress relaxation mechanism at first few loading/unloading cycles. Because of the short H diffusion length due to the thinner Pd shell, the film sample composed of 44 nm Au-Pd NPs has achieved a dramatically decreased response/recovery time to 4 s/30 s. The experiments present the promising prospect of this simple method to fabricate optical hydrogen sensors with controllable high sensitivity and response rate at low cost.

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

    KAUST Repository

    Zhou, Zhen; Hernandez Perez, Francisco; Shoshin, Yuriy; van Oijen, Jeroen A.; de Goey, Laurentius P.H.

    2017-01-01

    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.

  20. 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.

  1. Photochemical Hydrogen Doping Induced Embedded Two-Dimensional Metallic Channel Formation in InGaZnO at Room Temperature.

    Science.gov (United States)

    Kim, Myeong-Ho; Lee, Young-Ahn; Kim, Jinseo; Park, Jucheol; Ahn, Seungbae; Jeon, Ki-Joon; Kim, Jeong Won; Choi, Duck-Kyun; Seo, Hyungtak

    2015-10-27

    The photochemical tunability of the charge-transport mechanism in metal-oxide semiconductors is of great interest since it may offer a facile but effective semiconductor-to-metal transition, which results from photochemically modified electronic structures for various oxide-based device applications. This might provide a feasible hydrogen (H)-radical doping to realize the effectively H-doped metal oxides, which has not been achieved by thermal and ion-implantation technique in a reliable and controllable way. In this study, we report a photochemical conversion of InGaZnO (IGZO) semiconductor to a transparent conductor via hydrogen doping to the local nanocrystallites formed at the IGZO/glass interface at room temperature. In contrast to thermal or ionic hydrogen doping, ultraviolet exposure of the IGZO surface promotes a photochemical reaction with H radical incorporation to surface metal-OH layer formation and bulk H-doping which acts as a tunable and stable highly doped n-type doping channel and turns IGZO to a transparent conductor. This results in the total conversion of carrier conduction property to the level of metallic conduction with sheet resistance of ∼16 Ω/□, room temperature Hall mobility of 11.8 cm(2) V(-1) sec(-1), the carrier concentration at ∼10(20) cm(-3) without any loss of optical transparency. We demonstrated successful applications of photochemically highly n-doped metal oxide via optical dose control to transparent conductor with excellent chemical and optical doping stability.

  2. US work on technical and economic aspects of electrolytic, thermochemical, and hybrid processes for hydrogen production at temperatures below 550 deg. C

    International Nuclear Information System (INIS)

    Petri, M.C.; Yyldyz, B.; Klickman, A.E.

    2006-01-01

    Hydrogen demand is increasing, but there are few options for affordable hydrogen production free of greenhouse gas emissions. Nuclear power is one of the most promising options. Most research is focused on high-temperature electrolytic and thermochemical processes for nuclear-generated hydrogen, but it will be many years before very high temperature reactors become commercially available. For light water reactors or supercritical reactors, low-temperature water electrolysis is a currently available technology for hydrogen production. Higher efficiencies may be gained through thermo-electrochemical hydrogen production cycles, but there are only a limited number that have heat requirements consistent with the lower temperatures of light-water reactor technology. Indeed, active research is ongoing for only three such cycles in the USA. Reductions in electricity and system costs would be needed (or the imposition of a carbon tax) for low-temperature water electrolysis to compete with today's costs for steam methane reformation. The interactions between hydrogen and electricity markets and hydrogen and electricity producers are complex and will evolve as the markets evolve. (author)

  3. Hydrogen production system based on high temperature gas cooled reactor energy using the sulfur-iodine (SI) thermochemical water splitting cycle

    International Nuclear Information System (INIS)

    Garcia, L.; Gonzalez, D.

    2011-01-01

    Hydrogen production from water using nuclear energy offers one of the most attractive zero-emission energy strategies and the only one that is practical on a substantial scale. Recently, strong interest is seen in hydrogen production using heat of a high-temperature gas-cooled reactor. The high-temperature characteristics of the modular helium reactor (MHR) make it a strong candidate for producing hydrogen using thermochemical or high-temperature electrolysis (HTE) processes. Eventually it could be also employ a high-temperature gas-cooled reactor (HTGR), which is particularly attractive because it has unique capability, among potential future generation nuclear power options, to produce high-temperature heat ideally suited for nuclear-heated hydrogen production. Using heat from nuclear reactors to drive a sulfur-iodine (SI) thermochemical hydrogen production process has been interest of many laboratories in the world. One of the promising approaches to produce large quantity of hydrogen in an efficient way using the nuclear energy is the sulfur-iodine (SI) thermochemical water splitting cycle. Among the thermochemical cycles, the sulfur iodine process remains a very promising solution in matter of efficiency and cost. This work provides a pre-conceptual design description of a SI-Based H2-Nuclear Reactor plant. Software based on chemical process simulation (CPS) was used to simulate the thermochemical water splitting cycle Sulfur-Iodine for hydrogen production. (Author)

  4. System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures

    KAUST Repository

    Ehrhart, Brian D.; Muhich, Christopher L.; Al-Shankiti, Ibraheam; Weimer, Alan W.

    2016-01-01

    . The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas

  5. Effect of direction of approach to temperature on the delayed hydrogen cracking behavior of cold-worked Zr-2.5Nb

    International Nuclear Information System (INIS)

    Ambler, J.F.R.

    1984-01-01

    The delayed hydrogen cracking behavior of cold-worked Zr-2.5Nb at temperatures above about 423 K depends upon the direction of approach to test temperature. Cooling to the test temperatures results in an increase in crack growth rate, da/dt, with increase in temperature, given by the following Arrhenius relationship da/dt = 6.86 X 10 -1 exp(--71500/RT) Heating from room temperature to the test temperature results in the same increase in da/dt with temperature, but only up to a certain temperature, T /SUB DAT/ . The temperature, T /SUB DAT/ , increases with the amount of hydride precipitated during cooling to room temperature, prior to heating, and with cooling rate. The results obtained can be explained in terms of the Simpson and Puls model of delayed hydrogen cracking, if the hydride precipitated at the crack tip is initially fully constrained and the matrix hydride loses constraint during heating

  6. Production analysis of methanol and hydrogen of a modificated blast furnace gas using nuclear energy of the high temperature reactor

    International Nuclear Information System (INIS)

    Peschel, W.

    1985-12-01

    Modern blast furnaces are operated with a coke ration of 500 kg/t pig iron. The increase of the coke ratio to 1000 kg/t pig iron raises the content of carbon monoxide and hydrogen in the blast furnace gas. On the basis of a blast furnace gas modificated in such a way, the production of methanol and hydrogen is investigated under the coupling of current and process heat from the high temperature reactor. Moreover the different variants are discussed, for which respectively a material and energetic balance as well as an estimation of the production costs is performed. Regarding the subsequent treatment of the blast furnace gas it turns out favourably in principle to operate the blast furnace with a nitrogen-free wind consisting only of oxygen and steam. The production costs show a strong dependence on the raw material costs, whose influence is shown in a nomograph. (orig.) [de

  7. Room Temperature Reactivity Of Silicon Nanocrystals With Solvents: The Case Of Ketone And Hydrogen Production From Secondary Alcohols: Catalysis?

    KAUST Repository

    El Demellawi, Jehad K.; Holt, Christopher; Abou-Hamad, Edy; Al-Talla, Zeyad; Saih, Youssef; Chaieb, Saharoui

    2015-01-01

    Although silicon nanoparticles dispersed in liquids are used in various applications ranging from bio-labeling to hydrogen production, their reactivities with their solvents and their catalytic properties re-main still unexplored. Here, we discovered that, because of their surface structures and mechanical strain, silicon nanoparticles react strongly with their solvents and may act as catalysts for the dehydrogenation, at room temperature, of secondary alcohols (e.g. isopropanol) to ketones and hydrogen. This catalytic reaction was followed by gas chromatography, pH measurements, mass spectroscopy and solidstate NMR. This discovery provides new understanding of the role played by silicon nanoparticles, and nanosilicon in general, in their stability in solvents in general as well as being candidates in catalysis.

  8. Room Temperature Reactivity Of Silicon Nanocrystals With Solvents: The Case Of Ketone And Hydrogen Production From Secondary Alcohols: Catalysis?

    KAUST Repository

    El Demellawi, Jehad K.

    2015-05-29

    Although silicon nanoparticles dispersed in liquids are used in various applications ranging from bio-labeling to hydrogen production, their reactivities with their solvents and their catalytic properties re-main still unexplored. Here, we discovered that, because of their surface structures and mechanical strain, silicon nanoparticles react strongly with their solvents and may act as catalysts for the dehydrogenation, at room temperature, of secondary alcohols (e.g. isopropanol) to ketones and hydrogen. This catalytic reaction was followed by gas chromatography, pH measurements, mass spectroscopy and solidstate NMR. This discovery provides new understanding of the role played by silicon nanoparticles, and nanosilicon in general, in their stability in solvents in general as well as being candidates in catalysis.

  9. Safety conditions of using structural steels under high temperature and pressures in hydrogen containing environment

    International Nuclear Information System (INIS)

    Asviyan, M.B.

    1984-01-01

    The method for establishing full-strength conditions was suggested on the base of results of creep-rupture test of tube samples under hydrogen pressure and according to permissible stresses in neutral medium. Applicability of the method was considered taking St3 and 12KhM steels as examples. It was shown that the use of suggested dependences and special efficiency factors enables to forecast endurance limit for the given steel grade and assigned partial hydrogen pressure without labour-intensive test conducting

  10. Effect of Low-Temperature Sensitization on Hydrogen Embrittlement of 301 Stainless Steel

    OpenAIRE

    Chieh Yu; Ren-Kae Shiue; Chun Chen; Leu-Wen Tsay

    2017-01-01

    The effect of metastable austenite on the hydrogen embrittlement (HE) of cold-rolled (30% reduction in thickness) 301 stainless steel (SS) was investigated. Cold-rolled (CR) specimens were hydrogen-charged in an autoclave at 300 or 450 °C under a pressure of 10 MPa for 160 h before tensile tests. Both ordinary and notched tensile tests were performed in air to measure the tensile properties of the non-charged and charged specimens. The results indicated that cold rolling caused the transforma...

  11. Increase the threshold voltage of high voltage GaN transistors by low temperature atomic hydrogen treatment

    Energy Technology Data Exchange (ETDEWEB)

    Erofeev, E. V., E-mail: erofeev@micran.ru [Tomsk State University of Control Systems and Radioelectronics, Research Institute of Electrical-Communication Systems (Russian Federation); Fedin, I. V.; Kutkov, I. V. [Research and Production Company “Micran” (Russian Federation); Yuryev, Yu. N. [National Research Tomsk Polytechnic University, Institute of Physics and Technology (Russian Federation)

    2017-02-15

    High-electron-mobility transistors (HEMTs) based on AlGaN/GaN epitaxial heterostructures are a promising element base for the fabrication of high voltage electronic devices of the next generation. This is caused by both the high mobility of charge carriers in the transistor channel and the high electric strength of the material, which makes it possible to attain high breakdown voltages. For use in high-power switches, normally off-mode GaN transistors operating under enhancement conditions are required. To fabricate normally off GaN transistors, one most frequently uses a subgate region based on magnesium-doped p-GaN. However, optimization of the p-GaN epitaxial-layer thickness and the doping level makes it possible to attain a threshold voltage of GaN transistors close to V{sub th} = +2 V. In this study, it is shown that the use of low temperature treatment in an atomic hydrogen flow for the p-GaN-based subgate region before the deposition of gate-metallization layers makes it possible to increase the transistor threshold voltage to V{sub th} = +3.5 V. The effects under observation can be caused by the formation of a dipole layer on the p-GaN surface induced by the effect of atomic hydrogen. The heat treatment of hydrogen-treated GaN transistors in a nitrogen environment at a temperature of T = 250°C for 12 h reveals no degradation of the transistor’s electrical parameters, which can be caused by the formation of a thermally stable dipole layer at the metal/p-GaN interface as a result of hydrogenation.

  12. Increase the threshold voltage of high voltage GaN transistors by low temperature atomic hydrogen treatment

    International Nuclear Information System (INIS)

    Erofeev, E. V.; Fedin, I. V.; Kutkov, I. V.; Yuryev, Yu. N.

    2017-01-01

    High-electron-mobility transistors (HEMTs) based on AlGaN/GaN epitaxial heterostructures are a promising element base for the fabrication of high voltage electronic devices of the next generation. This is caused by both the high mobility of charge carriers in the transistor channel and the high electric strength of the material, which makes it possible to attain high breakdown voltages. For use in high-power switches, normally off-mode GaN transistors operating under enhancement conditions are required. To fabricate normally off GaN transistors, one most frequently uses a subgate region based on magnesium-doped p-GaN. However, optimization of the p-GaN epitaxial-layer thickness and the doping level makes it possible to attain a threshold voltage of GaN transistors close to V_t_h = +2 V. In this study, it is shown that the use of low temperature treatment in an atomic hydrogen flow for the p-GaN-based subgate region before the deposition of gate-metallization layers makes it possible to increase the transistor threshold voltage to V_t_h = +3.5 V. The effects under observation can be caused by the formation of a dipole layer on the p-GaN surface induced by the effect of atomic hydrogen. The heat treatment of hydrogen-treated GaN transistors in a nitrogen environment at a temperature of T = 250°C for 12 h reveals no degradation of the transistor’s electrical parameters, which can be caused by the formation of a thermally stable dipole layer at the metal/p-GaN interface as a result of hydrogenation.

  13. Nitride and carbide thin films as hydrogen permeation barrier on Manet steel

    International Nuclear Information System (INIS)

    Benamati, G.; Checchetto, R.; Bonelli, M.; Gratton, L.M.; Guzman, L.; Miotello, A.; Terlain, A.

    1995-01-01

    TiC / TiN bilayers, ∼ 1.2 μm thick, were deposited on Manet II steel by the ion beam assisted deposition technique to investigate the possible use of this ceramic coating as hydrogen barrier. Hydrogen permeation experiments in the temperature range 470-570 K showed indeed that this coating is a very efficient barrier to the hydrogen permeation being able to reduce the hydrogen flux up to two order of magnitude with respect to the uncoated steel. Preliminary compatibility tests between coated Manet II and Pb-17Li showed no attack of Pb-17Li to the steel. (orig.)

  14. Nitride and carbide thin films as hydrogen permeation barrier on MANET steel

    International Nuclear Information System (INIS)

    Benamati, G.

    1994-01-01

    TiC/TiN bilayers, - 1.2 μm thick, were deposited on Manet II steel by the ion beam assisted deposition technique to investigate the possible use of this ceramic coating as hydrogen barrier. Hydrogen permeation experiments in the temperature range 470-570 K showed indeed that this coating is a very efficient barrier to the hydrogen permeation being able to reduce the hydrogen flux up to two order of magnitude with respect to the uncoated steel. Preliminary compatibility tests between coated Manet II and Pb-17Li showed no attack of Pb-17Li to the steel. (author) 8 refs.; 2 figs.; 1 tab

  15. Hydrogen permeability, diffusivity, and solubility of SUS 316L stainless steel in the temperature range 400 to 800 .deg. C for fusion reactor applications

    International Nuclear Information System (INIS)

    Lee, S. K.; Kim, H. S.; Noh, S. J.; Han, J. H.

    2011-01-01

    Tritium permeation is one of the critical issues for the economy and safety of fusion power plants. As an initial step in tritium permeation research for fusion reactor applications, experiments were initiated by using hydrogen as a tritium substitute. An experimental system for hydrogen permeation and related behaviors in solid materials was designed and constructed. A continuous flow method was adopted with a capacity for high temperatures up to ∼1,000 .deg. C under ultra-high vacuums of ∼10 -7 Pa. The hydrogen permeation behavior in SUS 316L stainless steel was investigated in the temperature range from 400 .deg. C to 800 .deg. C. As a result, the permeability, diffusivity and solubility of hydrogen were determined. The results were compared with the previously existing reference data. Changes in the sample's surface morphology after the hydrogen permeation experiment are also addressed.

  16. Remarkably Enhanced Room-Temperature Hydrogen Sensing of SnO₂ Nanoflowers via Vacuum Annealing Treatment.

    Science.gov (United States)

    Liu, Gao; Wang, Zhao; Chen, Zihui; Yang, Shulin; Fu, Xingxing; Huang, Rui; Li, Xiaokang; Xiong, Juan; Hu, Yongming; Gu, Haoshuang

    2018-03-23

    In this work, SnO₂ nanoflowers synthesized by a hydrothermal method were employed as hydrogen sensing materials. The as-synthesized SnO₂ nanoflowers consisted of cuboid-like SnO₂ nanorods with tetragonal structures. A great increase in the relative content of surface-adsorbed oxygen was observed after the vacuum annealing treatment, and this increase could have been due to the increase in surface oxygen vacancies serving as preferential adsorption sites for oxygen species. Annealing treatment resulted in an 8% increase in the specific surface area of the samples. Moreover, the conductivity of the sensors decreased after the annealing treatment, which should be attributed to the increase in electron scattering around the defects and the compensated donor behavior of the oxygen vacancies due to the surface oxygen adsorption. The hydrogen sensors of the annealed samples, compared to those of the unannealed samples, exhibited a much higher sensitivity and faster response rate. The sensor response factor and response rate increased from 27.1% to 80.2% and 0.34%/s to 1.15%/s, respectively. This remarkable enhancement in sensing performance induced by the annealing treatment could be attributed to the larger specific surface areas and higher amount of surface-adsorbed oxygen, which provides a greater reaction space for hydrogen. Moreover, the sensors with annealed SnO₂ nanoflowers also exhibited high selectivity towards hydrogen against CH₄, CO, and ethanol.

  17. Thermodynamics of hydrogen adsorption in MOF-177 at low temperatures: measurements and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, Eric [College of Engineering, Purdue University, West Lafayette, IN 47907 (United States); Dailly, Anne [Chemical and Environmental Sciences Laboratory, General Motors Corporation, Warren, MI 48090 (United States)], E-mail: poirierem@gmail.com, E-mail: anne.dailly@gm.com

    2009-05-20

    Hydrogen adsorption measurements and modelling for the Zn-based microporous metal-organic framework (MOF) Zn{sub 4}O(1,3,5-benzenetribenzoate){sub 2}, MOF-177, were performed over the 50-77 K and 0-40 bar ranges. The maximum excess adsorption measured under these conditions varies over about 105-70 mg g{sup -1}. An analysis of the isotherms near saturation shows that hydrogen is ultimately adsorbed in an incompressible phase whose density is comparable to that of the bulk liquid. These liquid state properties observed under supercritical conditions reveal a remarkable effect of nanoscale confinement. The entire set of adsorption isotherms can be well described using a micropore filling model. The latter is used, in particular, to determine the absolute amounts adsorbed and the adsorption enthalpy. When expressed in terms of absolute adsorption, the isotherms show considerable hydrogen storage capacities, reaching up to 125 mg g{sup -1} at 50 K and 25 bar. The adsorption enthalpies are calculated as a function of fractional filling and range from 3 to 5 kJ mol{sup -1} in magnitude, in accordance with physisorption. These results are discussed with respect to a similar analysis performed on another Zn-based MOF, Zn{sub 4}O(1,4-benzenedicarboxylate){sub 3}, IRMOF-1, presented recently. It is found that both materials adsorb hydrogen by similar mechanisms.

  18. Two photon emission by hydrogen-like atoms in high temperature plasmas

    International Nuclear Information System (INIS)

    Costescu, A.; Manzatu, I.; Dinu, C.; Mihailescu, I.N.

    1981-08-01

    New exact solutions and a rather simple polynomial expression of the power emitted in the two photon transition from a metastable 2s state to the ground state of a hydrogen-like atom were infered with the aid of the Coulomb Green's function method. It was shown that the two photon decay represents under certain circumstances a significant power loss mechanism. (authors)

  19. Room temperature hydrogen sensing with the graphite/ZnO nanorod junctions decorated with Pt nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Yatskiv, Roman; Grym, Jan; Gladkov, Petar; Černohorský, Ondřej; Vaniš, Jan; Maixner, J.; Dickerson, J.H.

    2016-01-01

    Roč. 116, February (2016), s. 124-129 ISSN 0038-1101 R&D Projects: GA MŠk(CZ) LD14111; GA ČR(CZ) GA15-17044S Institutional support: RVO:67985882 Keywords : Graphite based junction * Hydrogen sensor * Electrophoretic deposition Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.580, year: 2016

  20. Low Temperature Curing of Hydrogen Silsesquioxane Surface Coatings for Corrosion Protection of Aluminum

    DEFF Research Database (Denmark)

    Lampert, Felix; Jensen, Annemette Hindhede; Møller, Per

    2016-01-01

    Hydrogen Silsesquioxane (HSQ) has shown to be a promising precursor for corrosion protective glass coatings for metallic substrates due to the excellent barrier properties of the films, especially in the application of protective coatings for aluminum in the automotive industry where high chemica...

  1. Thermodynamics of hydrogen adsorption in MOF-177 at low temperatures: measurements and modelling

    International Nuclear Information System (INIS)

    Poirier, Eric; Dailly, Anne

    2009-01-01

    Hydrogen adsorption measurements and modelling for the Zn-based microporous metal-organic framework (MOF) Zn 4 O(1,3,5-benzenetribenzoate) 2 , MOF-177, were performed over the 50-77 K and 0-40 bar ranges. The maximum excess adsorption measured under these conditions varies over about 105-70 mg g -1 . An analysis of the isotherms near saturation shows that hydrogen is ultimately adsorbed in an incompressible phase whose density is comparable to that of the bulk liquid. These liquid state properties observed under supercritical conditions reveal a remarkable effect of nanoscale confinement. The entire set of adsorption isotherms can be well described using a micropore filling model. The latter is used, in particular, to determine the absolute amounts adsorbed and the adsorption enthalpy. When expressed in terms of absolute adsorption, the isotherms show considerable hydrogen storage capacities, reaching up to 125 mg g -1 at 50 K and 25 bar. The adsorption enthalpies are calculated as a function of fractional filling and range from 3 to 5 kJ mol -1 in magnitude, in accordance with physisorption. These results are discussed with respect to a similar analysis performed on another Zn-based MOF, Zn 4 O(1,4-benzenedicarboxylate) 3 , IRMOF-1, presented recently. It is found that both materials adsorb hydrogen by similar mechanisms.

  2. Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

    OpenAIRE

    Arslan, C.; Sattar, A.; Ji, C.; Sattar, S.; Yousaf, K.; Hashim, S.

    2015-01-01

    The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste...

  3. Terrorists and Suicide Attacks

    National Research Council Canada - National Science Library

    Cronin, Audrey K

    2003-01-01

    Suicide attacks by terrorist organizations have become more prevalent globally, and assessing the threat of suicide attacks against the United States and its interests at home and abroad has therefore...

  4. Solidarity under Attack

    DEFF Research Database (Denmark)

    Meret, Susi; Goffredo, Sergio

    2017-01-01

    https://www.opendemocracy.net/can-europe-make-it/susi-meret-sergio-goffredo/solidarity-under-attack......https://www.opendemocracy.net/can-europe-make-it/susi-meret-sergio-goffredo/solidarity-under-attack...

  5. Pericarditis - after heart attack

    Science.gov (United States)

    ... include: A previous heart attack Open heart surgery Chest trauma A heart attack that has affected the thickness of your heart muscle Symptoms Symptoms include: Anxiety Chest pain from the swollen pericardium rubbing on the ...

  6. Heart attack first aid

    Science.gov (United States)

    First aid - heart attack; First aid - cardiopulmonary arrest; First aid - cardiac arrest ... A heart attack occurs when the blood flow that carries oxygen to the heart is blocked. The heart muscle ...

  7. Effect of temperature and dissolved hydrogen on oxide films formed on Ni and Alloy 182 in simulated PWR water

    International Nuclear Information System (INIS)

    Mendonça, R.; Bosch, R.-W.; Van Renterghem, W.; Vankeerberghen, M.; Araújo Figueiredo, C. de

    2016-01-01

    Alloy 182 is a nickel-based weld metal, which is susceptible to stress corrosion cracking in PWR primary water. It shows a peak in SCC susceptibility at a certain temperature and hydrogen concentration. This peak is related to the electrochemical condition where the Ni to NiO transition takes place. One hypothesis is that the oxide layer at this condition is not properly developed and so the material is not optimally protected against SCC. Therefore the oxide layer formed on Alloy 182 is investigated as a function of the dissolved hydrogen concentration and temperature around this Ni/NiO transition. Exposure tests were performed with Alloy 182 and Ni coupons in a PWR environment at temperatures between 300 °C and 345 °C and dissolved hydrogen concentration between 5 and 35 cc (STP)H 2 /kg. Post-test analysis of the formed oxide layers were carried out by SEM, EDS and XPS. The exposure tests with Ni coupons showed that the Ni/NiO transition curve is at a higher temperature than the curve based on thermodynamic calculations. The exposure tests with Alloy 182 showed that oxide layers were present at all temperatures, but that the morphology changed from spinel crystals to needle like oxides when the Ni/NiO transition curve was approached. Oxide layers were present below the Ni/NiO transition curve i.e. when the Ni coupon was still free of oxides. In addition an evolved slip dissolution model was proposed that could explain the observed experimental results and the peak in SCC susceptibility for Ni-based alloys around the Ni/NiO transition. - Highlights: • Exposure tests with Ni-coupons showed that the Ni/NiO transition curve shifted to more oxidizing conditions. • The Ni specimens tested in PWR water were free of oxides at all temperatures. • The exposure tests with Alloy 182 showed that oxide layers were present at all temperatures. • The Alloy 182 surface morphology changed from spinel crystals to needle like oxides when the Ni/NiO curve was approached

  8. Effect of temperature and dissolved hydrogen on oxide films formed on Ni and Alloy 182 in simulated PWR water

    Energy Technology Data Exchange (ETDEWEB)

    Mendonça, R. [CAPES Foundation, Ministry of Education, Brasilia (Brazil); Bosch, R.-W., E-mail: rbosch@sckcen.be [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Van Renterghem, W.; Vankeerberghen, M. [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Araújo Figueiredo, C. de [CDTN/CNEN, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, MG (Brazil)

    2016-08-15

    Alloy 182 is a nickel-based weld metal, which is susceptible to stress corrosion cracking in PWR primary water. It shows a peak in SCC susceptibility at a certain temperature and hydrogen concentration. This peak is related to the electrochemical condition where the Ni to NiO transition takes place. One hypothesis is that the oxide layer at this condition is not properly developed and so the material is not optimally protected against SCC. Therefore the oxide layer formed on Alloy 182 is investigated as a function of the dissolved hydrogen concentration and temperature around this Ni/NiO transition. Exposure tests were performed with Alloy 182 and Ni coupons in a PWR environment at temperatures between 300 °C and 345 °C and dissolved hydrogen concentration between 5 and 35 cc (STP)H{sub 2}/kg. Post-test analysis of the formed oxide layers were carried out by SEM, EDS and XPS. The exposure tests with Ni coupons showed that the Ni/NiO transition curve is at a higher temperature than the curve based on thermodynamic calculations. The exposure tests with Alloy 182 showed that oxide layers were present at all temperatures, but that the morphology changed from spinel crystals to needle like oxides when the Ni/NiO transition curve was approached. Oxide layers were present below the Ni/NiO transition curve i.e. when the Ni coupon was still free of oxides. In addition an evolved slip dissolution model was proposed that could explain the observed experimental results and the peak in SCC susceptibility for Ni-based alloys around the Ni/NiO transition. - Highlights: • Exposure tests with Ni-coupons showed that the Ni/NiO transition curve shifted to more oxidizing conditions. • The Ni specimens tested in PWR water were free of oxides at all temperatures. • The exposure tests with Alloy 182 showed that oxide layers were present at all temperatures. • The Alloy 182 surface morphology changed from spinel crystals to needle like oxides when the Ni/NiO curve was

  9. Temperature dependent selective detection of hydrogen and acetone using Pd doped WO3/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Kaur, Jasmeet; Anand, Kanica; Kohli, Nipin; Kaur, Amanpreet; Singh, Ravi Chand

    2018-06-01

    Reduced graphene oxide (RGO) and Pd doped WO3 nanocomposites were fabricated by employing electrostatic interactions between poly (diallyldimethylammonium chloride) (PDDA) modified Pd doped WO3 nanostructures and graphite oxide (GO) and studied for their gas sensing application. XRD, Raman, FTIR, FESEM-EDX, TEM, TGA, XPS and Photoluminescence techniques were used for characterization of as-synthesized samples. Gas sensing studies revealed that the sensor with optimized doping of 1.5 mol% Pd and 1 wt% GO shows temperature dependent selectivity towards hydrogen and acetone. The role of WO3, Pd and RGO has been discussed in detail for enhanced sensing performance.

  10. Two-temperature equilibration in warm dense hydrogen measured with x-ray scattering from the LCLS

    Science.gov (United States)

    Fletcher, Luke; High Energy Density Sciences Collaboration

    2017-10-01

    Understanding the properties of warm dense hydrogen plasmas is critical for modeling stellar and planetary interiors, as well as for inertial confinement fusion (ICF) experiments. Of central importance are the electron-ion collision and equilibration times that determine the microscopic properties in a high energy density state. Spectrally and angularly resolved x-ray scattering measurements from fs-laser heated hydrogen have resolved the picosecond evolution and energy relaxation from a two-temperature plasma towards thermodynamic equilibrium in the warm dense matter regime. The interaction of rapidly heated cryogenic hydrogen irradiated by a 400 nm, 5x1017 W/cm2 , 70 fs-laser is visualized with ultra-bright 5.5 kev x-ray pulses from the Linac Coherent Light (LCLS) source in 1 Hz repetition rate pump-probe setting. We demonstrate that the energy relaxation is faster than many classical binary collision theories that use ad hoc cutoff parameters used in the Landau-Spitzer determination of the Coulomb logarithm. This work was supported by the DOE Office of Science, Fusion Energy Science under contract No. SF00515 and supported under FWP 100182 and DOE Office of Basic Energy Sciences, Materials Sciences and Engineering Division, contract DE-AC02-76SF00515.

  11. Temperature effect on the photoinduced reduction of methyl viologen with several sensitizers and the evolution of hydrogen from water

    Energy Technology Data Exchange (ETDEWEB)

    Nenadovic, M.T.; Micic, O.I.; Rajh, T.; Savic, D.

    1983-01-01

    Irradiation by visible light of an aqueous solution containing a photosensitizer, methyl viologen (MV/sup 2 +/) and ethylenediaminetetraacetic acid leads to the formation of the reduced form of methyl viologen (MV/sup +/). The quantum yield for the formation of MV/sup +/ depends strongly on the time during which the formation is observed owing to the reaction of MV/sup +/ with oxidative products and its reduction to MV/sup 0/. Proflavin, acridine yellow and ruthenium(II)tris(2,2-bipyridyl) were used as photosensitizers and showed the same ability to promote hydrogen evolution. When CdS was used as a sensitizer a factor of 10 less hydrogen was obtained than when the dyes were used. The redox catalysts platinum, Pt-TiO/sub 2/-RuO/sub 2/ and Pt-CdS in colloidal systems showed approximately the same activity towards the reduction of water. The reduction of MV/sup 2 +/ and the evolution of hydrogen were enhanced at higher temperatures (70/sup 0/C). The optimum conditions for water reduction on redox catalysts in colloidal system under continuous illumination are analysed.

  12. System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures

    KAUST Repository

    Ehrhart, Brian D.

    2016-09-22

    The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas-gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered. © 2016 Hydrogen Energy Publications LLC.

  13. Phase transition temperatures of 405-725 K in superfluid ultra-dense hydrogen clusters on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Holmlid, Leif, E-mail: holmlid@chem.gu.se [Atmospheric Science, Department of Chemistry, University of Gothenburg, SE-412 96 Göteborg (Sweden); Kotzias, Bernhard [Airbus DS, Department Mechanical Engineering, D28199 Bremen (Germany)

    2016-04-15

    Ultra-dense hydrogen H(0) with its typical H-H bond distance of 2.3 pm is superfluid at room temperature as expected for quantum fluids. It also shows a Meissner effect at room temperature, which indicates that a transition point to a non-superfluid state should exist above room temperature. This transition point is given by a disappearance of the superfluid long-chain clusters H{sub 2N}(0). This transition point is now measured for several metal carrier surfaces at 405 - 725 K, using both ultra-dense protium p(0) and deuterium D(0). Clusters of ordinary Rydberg matter H(l) as well as small symmetric clusters H{sub 4}(0) and H{sub 3}(0) (which do not give a superfluid or superconductive phase) all still exist on the surface at high temperature. This shows directly that desorption or diffusion processes do not remove the long superfluid H{sub 2N}(0) clusters. The two ultra-dense forms p(0) and D(0) have different transition temperatures under otherwise identical conditions. The transition point for p(0) is higher in temperature, which is unexpected.

  14. Phase transition temperatures of 405-725 K in superfluid ultra-dense hydrogen clusters on metal surfaces

    International Nuclear Information System (INIS)

    Holmlid, Leif; Kotzias, Bernhard

    2016-01-01

    Ultra-dense hydrogen H(0) with its typical H-H bond distance of 2.3 pm is superfluid at room temperature as expected for quantum fluids. It also shows a Meissner effect at room temperature, which indicates that a transition point to a non-superfluid state should exist above room temperature. This transition point is given by a disappearance of the superfluid long-chain clusters H_2_N(0). This transition point is now measured for several metal carrier surfaces at 405 - 725 K, using both ultra-dense protium p(0) and deuterium D(0). Clusters of ordinary Rydberg matter H(l) as well as small symmetric clusters H_4(0) and H_3(0) (which do not give a superfluid or superconductive phase) all still exist on the surface at high temperature. This shows directly that desorption or diffusion processes do not remove the long superfluid H_2_N(0) clusters. The two ultra-dense forms p(0) and D(0) have different transition temperatures under otherwise identical conditions. The transition point for p(0) is higher in temperature, which is unexpected.

  15. Effect of high hydrogen content on metallurgical and mechanical properties of zirconium alloy claddings after heat-treatment at high temperature

    International Nuclear Information System (INIS)

    Turque, Isabelle

    2016-01-01

    Under hypothetical loss-of-coolant accident conditions, fuel cladding tubes made of zirconium alloys can be exposed to steam at high temperature (HT, up 1200 C) before being cooled and then quenched in water. In some conditions, after burst occurrence the cladding can rapidly absorb a significant amount of hydrogen (secondary hydriding), up to 3000 wt.ppm locally, during steam exposition at HT. The study deals with the effect, poorly studied up to date, of high contents of hydrogen on the metallurgical and mechanical properties of two zirconium alloys, Zircaloy-4 and M5, during and after cooling from high temperatures, at which zirconium is in its β phase. A specific facility was developed to homogeneously charge in hydrogen up to ∼ 3000 wt.ppm cladding tube samples of several centimeters in length. Phase transformations, chemical element partitioning and hydrogen precipitation during cooling from the β temperature domain of zirconium were studied by using several techniques, for the materials containing up to ∼ 3000 wt.ppm of hydrogen in average: in-situ neutron diffraction upon cooling from 700 C, X-ray diffraction, μ-ERDA, EPMA and electron microscopy in particular. The results were compared to thermodynamic predictions. In order to study the effect of high hydrogen contents on the mechanical behavior of the (prior-)μ phase of zirconium, axial tensile tests were performed at various temperatures between 20 and 700 C upon cooling from the β temperature domain, on samples with mean hydrogen contents up to ∼ 3000 wt.ppm. The results show that metallurgical and mechanical properties of the (prior-)β phase of zirconium alloys strongly depend on temperature and hydrogen content. (author) [fr

  16. Development of a Hydrogen Gas Sensor Using a Double Saw Resonator System at Room Temperature

    Directory of Open Access Journals (Sweden)

    Zainab Yunusa

    2015-02-01

    Full Text Available A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%.

  17. Etching effects of low temperature hydrogen plasma on encapsulated diamond transistors

    Czech Academy of Sciences Publication Activity Database

    Krátká, Marie; Neykova, Neda; Kromka, Alexander; Rezek, Bohuslav

    2012-01-01

    Roč. 53, č. 2 (2012), s. 97-103 ISSN 0001-7140 R&D Projects: GA ČR GD202/09/H041; GA ČR(CZ) GBP108/12/G108; GA ČR GAP108/12/0996 Institutional research plan: CEZ:AV0Z10100521 Keywords : encapsulated diamond transistors * hydrogen plasma Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Composite Dos Attack Model

    Directory of Open Access Journals (Sweden)

    Simona Ramanauskaitė

    2012-04-01

    Full Text Available Preparation for potential threats is one of the most important phases ensuring system security. It allows evaluating possible losses, changes in the attack process, the effectiveness of used countermeasures, optimal system settings, etc. In cyber-attack cases, executing real experiments can be difficult for many reasons. However, mathematical or programming models can be used instead of conducting experiments in a real environment. This work proposes a composite denial of service attack model that combines bandwidth exhaustion, filtering and memory depletion models for a more real representation of similar cyber-attacks. On the basis of the introduced model, different experiments were done. They showed the main dependencies of the influence of attacker and victim’s properties on the success probability of denial of service attack. In the future, this model can be used for the denial of service attack or countermeasure optimization.

  19. Growth of room temperature ferromagnetic Ge1-xMnx quantum dots on hydrogen passivated Si (100) surfaces

    Science.gov (United States)

    Gastaldo, Daniele; Conta, Gianluca; Coïsson, Marco; Amato, Giampiero; Tiberto, Paola; Allia, Paolo

    2018-05-01

    A method for the synthesis of room-temperature ferromagnetic dilute semiconductor Ge1-xMnx (5 % < x < 8 %) quantum dots by molecular beam epitaxy by selective growth on hydrogen terminated silicon (100) surface is presented. The functionalized substrates, as well as the nanostructures, were characterized in situ by reflection high-energy electron diffraction. The quantum dots density and equivalent radius were extracted from field emission scanning electron microscope pictures, obtained ex-situ. Magnetic characterizations were performed by superconducting quantum interference device vibrating sample magnetometry revealing that ferromagnetic order is maintained up to room temperature: two different ferromagnetic phases were identified by the analysis of the field cooled - zero field cooled measurements.

  20. A Free-Radical Pathway to Hydrogenated Phenanthrene in Molecular Clouds-Low Temperature Growth of Polycyclic Aromatic Hydrocarbons.

    Science.gov (United States)

    Thomas, Aaron M; Lucas, Michael; Yang, Tao; Kaiser, Ralf I; Fuentes, Luis; Belisario-Lara, Daniel; Mebel, Alexander M

    2017-08-05

    The hydrogen-abstraction/acetylene-addition mechanism has been fundamental to unravelling the synthesis of polycyclic aromatic hydrocarbons (PAHs) detected in combustion flames and carbonaceous meteorites like Orgueil and Murchison. However, the fundamental reaction pathways accounting for the synthesis of complex PAHs, such as the tricyclic anthracene and phenanthrene along with their dihydrogenated counterparts, remain elusive to date. By investigating the hitherto unknown chemistry of the 1-naphthyl radical with 1,3-butadiene, we reveal a facile barrierless synthesis of dihydrophenanthrene adaptable to low temperatures. These aryl-type radical additions to conjugated hydrocarbons via resonantly stabilized free-radical intermediates defy conventional wisdom that PAH growth is predominantly a high-temperature phenomenon and thus may represent an overlooked path to PAHs as complex as coronene and corannulene in cold regions of the interstellar medium like in the Taurus Molecular Cloud. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. High pressure apparatus for hydrogen isotopes to pressures of 345 MPa (50,000 psi) and temperatures of 12000C

    International Nuclear Information System (INIS)

    Lakner, J.F.

    1977-01-01

    A functional new high pressure, high temperature apparatus for hydrogen isotopes uses an internally heated pressure vessel within a larger pressure vessel. The pressure capability is 345 MPa (50 K psi) at 1200 0 C. The gas pressure inside the internal vessel is balanced with gas pressure in the external vessel. The internal vessel is attached to a closure and is also the sample container. Our design allows thin-walled internal vessel construction and keeps the sample from ''seeing'' the furnace or other extraneous environment. The sample container together with the closure can easily be removed and loaded under argon using standard glove-box procedures. The small volume of the inner vessel permits small volumes of gas to be used, thus increasing the sensitivity during pressure-volume-temperature (PVT) work

  2. A spatial model for a stream networks of Citarik River with the environmental variables: potential of hydrogen (PH) and temperature

    Science.gov (United States)

    Bachrudin, A.; Mohamed, N. B.; Supian, S.; Sukono; Hidayat, Y.

    2018-03-01

    Application of existing geostatistical theory of stream networks provides a number of interesting and challenging problems. Most of statistical tools in the traditional geostatistics have been based on a Euclidean distance such as autocovariance functions, but for stream data is not permissible since it deals with a stream distance. To overcome this autocovariance developed a model based on the distance the flow with using convolution kernel approach (moving average construction). Spatial model for a stream networks is widely used to monitor environmental on a river networks. In a case study of a river in province of West Java, the objective of this paper is to analyze a capability of a predictive on two environmental variables, potential of hydrogen (PH) and temperature using ordinary kriging. Several the empirical results show: (1) The best fit of autocovariance functions for temperature and potential hydrogen (ph) of Citarik River is linear which also yields the smallest root mean squared prediction error (RMSPE), (2) the spatial correlation values between the locations on upstream and on downstream of Citarik river exhibit decreasingly

  3. Influence of temperature and hydrogen content on stress-induced radial hydride precipitation in Zircaloy-4 cladding

    Energy Technology Data Exchange (ETDEWEB)

    Desquines, J., E-mail: jean.desquines@irsn.fr; Drouan, D.; Billone, M.; Puls, M.P.; March, P.; Fourgeaud, S.; Getrey, C.; Elbaz, V.; Philippe, M.

    2014-10-15

    Radial hydride precipitation in stress relieved Zircaloy-4 fuel claddings is studied using a new thermal–mechanical test. Two maximum temperatures for radial hydride precipitation heat treatment are studied, 350 and 450 °C with hydrogen contents ranging between 50 and 600 wppm. The new test provides two main results of interest: the minimum hoop stress required to precipitate radial hydrides and a maximum stress above which, all hydrides precipitate in the radial direction. Based on these two extreme stress conditions, a model is derived to determine the stress level required to obtain a given fraction of radial hydrides after high temperature thermal–mechanical heat treatment. The proposed model is validated using metallographic observation data on pressurized tubes cooled down under constant pressure. Most of the samples with reoriented hydrides are further subjected to a ductility test. Using finite element modeling, the test results are analyzed in terms of crack nucleation within radial hydrides at the outer diameter and crack growth through the thickness of the tubular samples. The combination of test results shows that samples with hydrogen contents of about 100 wppm had the lowest ductility.

  4. Enhanced TiC/SiC Ohmic contacts by ECR hydrogen plasma pretreatment and low-temperature post-annealing

    International Nuclear Information System (INIS)

    Liu, Bingbing; Qin, Fuwen; Wang, Dejun

    2015-01-01

    Highlights: • Low-temperature ECR microwave hydrogen plasma were pretreated for moderately doped (1 × 10"1"8 cm"−"3) SiC surfaces. • The relationship among Ohmic properties, the SiC surface properties and TiC/SiC interface properties were established. • Interface band structures were analyzed to elucidate the mechanism by which the Ohmic contacts were formed. - Abstract: We proposed an electronic cyclotron resonance (ECR) microwave hydrogen plasma pretreatment (HPT) for moderately doped (1 × 10"1"8 cm"−"3) SiC surfaces and formed ideal TiC/SiC Ohmic contacts with significantly low contact resistivity (1.5 × 10"−"5 Ω cm"2) after low-temperature annealing (600 °C). This is achieved by reducing barrier height at TiC/SiC interface because of the release of pinned Fermi level by surface flattening and SiC surface states reduction after HPT, as well as the generation of donor-type carbon vacancies, which reduced the depletion-layer width for electron tunneling after annealing. Interface band structures were analyzed to elucidate the mechanism of Ohmic contact formations.

  5. The muon spin response to intermittent hyperfine interaction: modelling the high-temperature electrical activity of hydrogen in silicon

    International Nuclear Information System (INIS)

    Lord, J S; Cox, S F J; Charlton, M; Werf, D P Van der; Lichti, R L; Amato, A

    2004-01-01

    At temperatures above 600 K in silicon, unlike at lower temperatures, the partitioning of muonium between its neutral paramagnetic states and its charged or electronically diamagnetic states corresponds closely to thermodynamic equilibrium. The individual charge states are short lived, with many cycles of carrier capture and release occurring within the muon lifetime. The resultant intermittent hyperfine interaction depolarizes the muons strongly, with longitudinal and transverse relaxation rates remaining distinct up to about 700 K but becoming equal at still higher temperatures. Data up to 900 K are presented and interpreted. The muon spin rotation spectrum in transverse magnetic fields, although collapsed to a single broad line in this charge exchange regime, is shifted substantially from the muon Larmor frequency, the shift being non-linear in field and only in small part due to electron polarization. A new density matrix treatment shows how all three observables can be accounted for with a consistent set of transition rates. These in turn may be interpreted in terms of effective donor and acceptor energy levels appropriate to this high-temperature regime, confirming negative-U behaviour and providing the first estimate, for muonium, of this elusive parameter. At temperatures where passivation complexes are dissociated, these findings provide a guide to, and microscopic models for, the electrical activity of hydrogen

  6. Effects of Iodide and Hydrogen Peroxide on Measuring High Temperature pH in Various Lithium Borate Buffer Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Jae Sik; Yun, Myung Hee; Yeon, Jei Won; Song, Kyu Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-10-15

    In a reactor coolant system of nuclear power plants, the need for reliable high temperature pH electrodes has resulted from interests in the corrosion and corrosion product behaviors of the structural materials in a high temperature coolant system. In developing the electrodes for measuring the high temperature pH of aqueous solutions, it is necessary to note two major problems: the chemical stability of an electrode against other chemical impurities, and an electrode's integrity as the temperature and pressure are varied between operational extremes. Over the past decade Macdonald et al. and Danielson et al. have developed many ceramic membrane pH electrodes based on a yttrium stabilized zirconium oxide. However, there are still many experimental difficulties associated with the problems in obtaining electrochemical information across different pressure boundaries and against many kinds of chemical impurities caused by the radiolysis of water and the leakage of a fuel clad. In the present work, we investigated the effects of the environmental factors on a high temperature pH. The selected environmental factors are as follows: system pressure, and chemical species such as iodide and hydrogen peroxide ions.

  7. Temperature dependence of the hydrogen-broadening coefficient for the nu 9 fundamental of ethane

    Science.gov (United States)

    Halsey, G. W.; Hillman, J. J.; Nadler, Shacher; Jennings, D. E.

    1988-01-01

    Experimental results for the temperature dependence of the H2-broadening coefficient for the nu 9 fundamental of ethane are reported. Measurements were made over the temperature range 95-300 K using a novel low-temperature absorption cell. These spectra were recorded with the Doppler-limited diode laser spectrometer at NASA Goddard. The results are compared with recent measurements and model predictions.

  8. Distribution of deuterium and hydrogen in Zr and Ti foil assemblies under the action of a pulsed deuterium high-temperature plasma

    Science.gov (United States)

    Bondarenko, G. G.; Volobuev, I. V.; Eriskin, A. A.; Kobzev, A. P.; Nikulin, V. Ya.; Peregudova, E. N.; Silin, P. V.; Borovitskaya, I. V.

    2017-09-01

    Deuteron and proton elastic recoil detection analysis is used to study the accumulation and redistribution of deuterium and hydrogen in assemblies of two high-pure zirconium or titanium foils upon pulsed action of high-temperature deuterium plasma (PHTDP) in a plasma-focus installation PF-4. It is noted that, under the action of PHTDP, an implanted deuterium and hydrogen gas impurity are redistributed in the irradiated foils in large depths, which are significantly larger than the deuterium ion free paths (at their maximum velocity to 108 cm/s). The observed phenomenon is attributed to the carrying out of implanted deuterium and hydrogen under the action of powerful shock waves formed in the metallic foils under the action of PHTDP and/or the acceleration of diffusion of deuterium and hydrogen atoms under the action of a compression-rarefaction shock wave at the shock wave front with the redistribution of deuterium and hydrogen to large depths.

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

    International Nuclear Information System (INIS)

    Roychowdhury, S.; Seifert, H.-P.; Spätig, P.; Que, Z.

    2016-01-01

    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.

  10. 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.

  11. Microstructure and high-temperature tribological properties of Si-doped hydrogenated diamond-like carbon films

    Science.gov (United States)

    Zhang, Teng Fei; Wan, Zhi Xin; Ding, Ji Cheng; Zhang, Shihong; Wang, Qi Min; Kim, Kwang Ho

    2018-03-01

    Si-doped DLC films have attracted great attention for use in tribological applications. However, their high-temperature tribological properties remain less investigated, especially in harsh oxidative working conditions. In this study, Si-doped hydrogenated DLC films with various Si content were synthesized and the effects of the addition of Si on the microstructural, mechanical and high-temperature tribological properties of the films were investigated. The results indicate that Si doping leads to an obvious increase in the sp3/sp2 ratio of DLC films, likely due to the silicon atoms preferentially substitute the sp2-hybridized carbon atoms and augment the number of sp3 sites. With Si doping, the mechanical properties, including hardness and adhesion strength, were improved, while the residual stress of the DLC films was reduced. The addition of Si leads to higher thermal and mechanical stability of DLC films because the Si atoms inhibit the graphitization of the films at an elevated temperature. Better high-temperature tribological properties of the Si-DLC films under oxidative conditions were observed, which can be attributed to the enhanced thermal stability and formation of a Si-containing lubricant layer on the surfaces of the wear tracks. The nano-wear resistance of the DLC films was also improved by Si doping.

  12. Advanced High-Temperature Reactor for Production of Electricity and Hydrogen: Molten-Salt-Coolant, Graphite-Coated-Particle-Fuel

    International Nuclear Information System (INIS)

    Forsberg, C.W.

    2002-01-01

    The objective of the Advanced High-Temperature Reactor (AHTR) is to provide the very high temperatures necessary to enable low-cost (1) efficient thermochemical production of hydrogen and (2) efficient production of electricity. The proposed AHTR uses coated-particle graphite fuel similar to the fuel used in modular high-temperature gas-cooled reactors (MHTGRs), such as the General Atomics gas turbine-modular helium reactor (GT-MHR). However, unlike the MHTGRs, the AHTR uses a molten salt coolant with a pool configuration, similar to that of the PRISM liquid metal reactor. A multi-reheat helium Brayton (gas-turbine) cycle, with efficiencies >50%, is used to produce electricity. This approach (1) minimizes requirements for new technology development and (2) results in an advanced reactor concept that operates at essentially ambient pressures and at very high temperatures. The low-pressure molten-salt coolant, with its high heat capacity and natural circulation heat transfer capability, creates the potential for (1) exceptionally robust safety (including passive decay-heat removal) and (2) allows scaling to large reactor sizes [∼1000 Mw(e)] with passive safety systems to provide the potential for improved economics

  13. Shape-Dependent Activity of Ceria for Hydrogen Electro-Oxidation in Reduced-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Tong, Xiaofeng; Luo, Ting; Meng, Xie; Wu, Hao; Li, Junliang; Liu, Xuejiao; Ji, Xiaona; Wang, Jianqiang; Chen, Chusheng; Zhan, Zhongliang

    2015-11-04

    Single crystalline ceria nanooctahedra, nanocubes, and nanorods are hydrothermally synthesized, colloidally impregnated into the porous La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) scaffolds, and electrochemically evaluated as the anode catalysts for reduced temperature solid oxide fuel cells (SOFCs). Well-defined surface terminations are confirmed by the high-resolution transmission electron microscopy--(111) for nanooctahedra, (100) for nanocubes, and both (110) and (100) for nanorods. Temperature-programmed reduction in H2 shows the highest reducibility for nanorods, followed sequentially by nanocubes and nanooctahedra. Measurements of the anode polarization resistances and the fuel cell power densities reveal different orders of activity of ceria nanocrystals at high and low temperatures for hydrogen electro-oxidation, i.e., nanorods > nanocubes > nanooctahedra at T ≤ 450 °C and nanooctahedra > nanorods > nanocubes at T ≥ 500 °C. Such shape-dependent activities of these ceria nanocrystals have been correlated to their difference in the local structure distortions and thus in the reducibility. These findings will open up a new strategy for design of advanced catalysts for reduced-temperature SOFCs by elaborately engineering the shape of nanocrystals and thus selectively exposing the crystal facets. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Web server attack analyzer

    OpenAIRE

    Mižišin, Michal

    2013-01-01

    Web server attack analyzer - Abstract The goal of this work was to create prototype of analyzer of injection flaws attacks on web server. Proposed solution combines capabilities of web application firewall and web server log analyzer. Analysis is based on configurable signatures defined by regular expressions. This paper begins with summary of web attacks, followed by detection techniques analysis on web servers, description and justification of selected implementation. In the end are charact...

  15. Numerical analysis of performance of steam reformer of methane reforming hydrogen production system connected with high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Yin Huaqiang; Jiang Shengyao; Zhang Youjie

    2007-01-01

    Methane conversion rate and hydrogen output are important performance indexes of the steam reformer. The paper presents numerical analysis of performance of the reformer connected with high-temperature gas-cooled reactor HTR-10. Setting helium inlet flow rate fixed, performance of the reformer was examined with different helium inlet temperature, pressure, different process gas temperature, pressure, flow rate, and different steam to carbon ratio. As the range concerned, helium inlet temperature has remarkable influence on the performance, and helium inlet temperature, process gas temperature and pressure have little influence on the performance, and improving process gas flow rate, methane conversion rate decreases and hydrogen output increases, however improving steam to carbon ratio has reverse influence on the performance. (authors)

  16. Seven Deadliest Microsoft Attacks

    CERN Document Server

    Kraus, Rob; Borkin, Mike; Alpern, Naomi

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting Microsoft products? Then you need Seven Deadliest Microsoft Attacks. This book pinpoints the most dangerous hacks and exploits specific to Microsoft applications, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Windows Operating System-Password AttacksActive Directory-Escalat

  17. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... stroke symptoms. Popular Topics TIA Cardiac Catheter Cholesterol Heart Attack Stent © 2018, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. ...

  18. Seven deadliest USB attacks

    CERN Document Server

    Anderson, Brian

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting USB technology? Then you need Seven Deadliest USB Attacks. This book pinpoints the most dangerous hacks and exploits specific to USB, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: USB Hacksaw USB Switchblade USB Based Virus/Malicous Code Launch USB Device Overflow RAMdum

  19. Line profiles of hydrogenic ions from high-temperature and high-density plasmas

    International Nuclear Information System (INIS)

    Hou Qing; Li Jianming

    1991-01-01

    Applying the Hooper's first-order theory, the authors calculate the static micro-electric field distributions in plasmas containing various multiply-charged ions. The influences of the impurity concentrations on the micro electric field distributions and on the Lyman profiles (n→1) from hydrogenic ions are analysed. Based on the optical-thin line profiles, the radiation transfer equation in sphere plasmas with various optical depths is solved. The results confirm that the opacity-broadening of the line profiles has almost no effect on the separation of Lyman β splitted peaks. Such separation is determined by electric field at which the static micro-electric field distribution has a maximum. The separation can be utilized for spatially resolved and temporally resolved density diagnostic of fusion plasmas

  20. Chemical reactivity of hydrogen, nitrogen, and oxygen atoms at temperatures below 100 k

    Science.gov (United States)

    Mcgee, H. A., Jr.

    1973-01-01

    The synthesis of unusual compounds by techniques employing cryogenic cooling to retard their very extreme reactivity was investigated. Examples of such species that were studied are diimide (N2H2), cyclobutadiene (C4H4), cyclopropanone (C3H4O), oxirene (C2H2O), and many others. Special purpose cryogenically cooled inlet arrangements were designed such that the analyses incurred no warm-up of the cold, and frequently explosively unstable, compounds. Controlled energy electron impact techniques were used to measure critical potentials and to develop the molecular energetics and thermodynamics of these molecules and to gain some insight into their kinetic characteristics as well. Three and four carbon strained ring molecules were studied. Several reactions of oxygen and hydrogen atoms with simple molecules of H, N, C, and O in hard quench configurations were studied. And the quench stabilization of BH3 was explored as a model system in cryochemistry.

  1. Collisional broadening of depolarized spectral lines of hydrogen gases at low temperatures

    International Nuclear Information System (INIS)

    Hout, K.D. van den.

    1978-01-01

    Experimental results are presented for the collisional broadening and shift of H 2 , D 2 and HD rotational Raman and depolarized Rayleigh lines at various temperatures between 25 K and 300 K. These are then discussed within the context of current theoretical concepts. For a few temperatures the line broadening cross sections are also reported as a function of the ortho-para composition for H 2 and D 2 . (C.F.)

  2. A TEM based study of the microstructure during room temperature and low temperature hydrogen storage cycling in MgH2 promoted by Nb–V

    International Nuclear Information System (INIS)

    Tan Xuehai; Zahiri, Beniamin; Holt, Chris M.B.; Kubis, Alan; Mitlin, David

    2012-01-01

    Magnesium hydride combined with a new bimetallic Nb–V catalyst displays remarkably rapid and stable low temperature (200 °C) hydrogen storage kinetics, even after 500 full volumetric absorption/desorption cycles. The system is also able to fairly rapidly absorb hydrogen at room temperature at a pressure of 1 bar. This unprecedented absorption behavior was demonstrated for 20 cycles. We employed extensive cryo-stage transmission electron microscopy (TEM) analysis on fully and partially sorbed materials to provide insight into the rapid Mg to MgH 2 phase transformation. After extended cycling of what was initially a 1.5 μm thick fully dense alloy film, the sample structure becomes analogous to that of a weakly agglomerated nanocomposite powder. The cycled Mg–V–Nb structure consists of a dense distribution of catalytic Nb–V nanocrystallites covering the surfaces of larger Mg and MgH 2 particles. The partially absorbed 20 °C and 200 °C microstructures both show this morphology. TEM results combined with Johnson–Mehl–Avrami-type kinetic analysis point to the surface catalyst distribution and stability against coarsening as being a key influence on the two-stage hydriding kinetics. Remarkably, the mean size of the Nb 0.5 V 0.5 H nanocrystallites stays essentially invariant throughout cycling; it is 3 nm after 45 cycles and 4 nm after 500 cycles. A mechanistic description is provided for the cycling-induced microstructural evolution in the ternary alloy as well as in the binary baselines.

  3. Room-Temperature and Aqueous-Phase Synthesis of Plasmonic Molybdenum Oxide Nanoparticles for Visible-Light-Enhanced Hydrogen Generation.

    Science.gov (United States)

    Shi, Jiayuan; Kuwahara, Yasutaka; Wen, Meicheng; Navlani-García, Miriam; Mori, Kohsuke; An, Taicheng; Yamashita, Hiromi

    2016-09-06

    A straightforward aqueous synthesis of MoO3-x nanoparticles at room temperature was developed by using (NH4 )6 Mo7 O24 ⋅4 H2 O and MoCl5 as precursors in the absence of reductants, inert gas, and organic solvents. SEM and TEM images indicate the as-prepared products are nanoparticles with diameters of 90-180 nm. The diffuse reflectance UV-visible-near-IR spectra of the samples indicate localized surface plasmon resonance (LSPR) properties generated by the introduction of oxygen vacancies. Owing to its strong plasmonic absorption in the visible-light and near-infrared region, such nanostructures exhibit an enhancement of activity toward visible-light catalytic hydrogen generation. MoO3-x nanoparticles synthesized with a molar ratio of Mo(VI) /Mo(V) 1:1 show the highest yield of H2 evolution. The cycling catalytic performance has been investigated to indicate the structural and chemical stability of the as-prepared plasmonic MoO3-x nanoparticles, which reveals its potential application in visible-light catalytic hydrogen production. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

    Science.gov (United States)

    Arslan, C.; Sattar, A.; Ji, C.; Sattar, S.; Yousaf, K.; Hashim, S.

    2015-11-01

    The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste. The maximum cumulative bio-hydrogen production of 650 mL was obtained from noodle waste under thermophilic temperature condition. Most of the production was observed during the first 48 h of incubation, which continued until 72 h of incubation. The decline in pH during this interval was 4.3 and 4.4 from a starting value of 7 under mesophilic and thermophilic conditions, respectively. Most of the glucose consumption was also observed during 72 h of incubation and the maximum consumption was observed during the first 24 h, which was the same duration where the maximum pH drop occurred. The maximum hydrogen yields of 82.47 mL VS-1, 131.38 mL COD-1, and 44.90 mL glucose-1 were obtained from thermophilic food waste, thermophilic noodle waste and mesophilic rice waste, respectively. The production of volatile fatty acids increased with an increase in time and temperature in food waste and noodle waste reactors whereas they decreased with temperature in rice waste reactors. The statistical modelling returned good results with high values of coefficient of determination (R2) for each waste type and 3-D response surface plots developed by using models developed. These plots developed a better understanding regarding the impact of temperature and incubation time on bio-hydrogen production trend, glucose consumption during incubation and volatile fatty acids production.

  5. A Room-temperature Hydrogen Gas Sensor Using Palladium-decorated Single-Walled Carbon Nanotube/Si Heterojunction

    Directory of Open Access Journals (Sweden)

    Yong Gang DU

    2016-05-01

    Full Text Available We report a room-temperature (RT hydrogen gas (H2 sensor based on palladium-decorated single-walled carbon nanotube/Si (Pd-SWNTs/Si heterojunction. The current-voltage (I-V curves of the Pd-SWNTs/Si heterojunction in different concentrations of H2 were measured. The experimental results reveal that the Pd-SWNTs/Si heterojunction exhibits high H2 response. After exposure to 0.02 %, 0.05 %, and 0.1 % H2 for 10 min, the resistance of the heterojunction increases dramatically. The response is 122 %, 269 % and 457 %, respectively. A simple interfacial theory is used to understand the gas sensitivity results. This approach is a step toward future CNTs-based gas sensors for practical application.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12925

  6. Observation of structure transition as a function of temperature in depositing hydrogenated sp2-rich carbon films

    Science.gov (United States)

    Wang, Yongfu; Gao, Kaixiong; Zhang, Junyan

    2018-05-01

    In this study, we carried out the transition experiments of graphite-like (GL) to fullerene-like (FL) structures by placing high temperature steel substrates in the depositing environment which can form FL hydrogenated carbon films. We investigated the changes of bond mixtures, H content, aromatic clusters and internal stress at the transition process, and proposed the transformation mechanism inferred from Raman, TEM cross-section, FTIR and XPS results. It was found that the size of aromatic clusters and accordingly graphene planes and the formation of edge dangling bonds were the key steps. H+ bombardment leaded to the splitting of large graphene planes (at GL stage) into more and smaller planes (at FL stage) and the formation of edge dangling bonds; Some of these dangling bonds were reduced by the formation of pentagons and subsequent curving of the smaller planes, which were an indicator of FL structures.

  7. Effects of hydrogen annealing on the room temperature ferromagnetism and optical properties of Cr-doped ZnO nanoparticles

    International Nuclear Information System (INIS)

    Tong Liuniu; Wang Yichao; He Xianmei; Han Huaibin; Xia Ailin; Hu Jinlian

    2012-01-01

    We explore the effects of hydrogen annealing on the room temperature ferromagnetism and optical properties of Cr-doped ZnO nanoparticles synthesized by the sol-gel method. X-ray diffraction and x-ray photoelectron spectroscopy data show evidence that Cr has been incorporated into the wurtzite ZnO lattice as Cr 2+ ions substituting for Zn 2+ ions without any detectable secondary phase in as-synthesized Zn 0.97 Cr 0.03 O nanopowders. The room temperature magnetization measurements reveal a large enhancement of saturation magnetization M s as well as an increase of coercivity of H 2 -annealed Zn 0.97 Cr 0.03 O:H samples. It is found that the field-cooled magnetization curves as a function of temperature from 40 to 400 K can be well fitted by a combination of a standard Bloch spin-wave model and Curie–Weiss law. The values of the fitted parameters of the ferromagnetic exchange interaction constant a and the Curie constant C of H 2 -annealed Zn 0.97 Cr 0.03 O:H nanoparticles are almost doubled upon H 2 -annealing. Photoluminescence measurements show evidence that the shallow donor defect or/and defect complexes such as hydrogen occupying an oxygen vacancy H o may play an important role in the origin of H 2 -annealing induced enhancement of ferromagnetism in Cr-H codoped ZnO nanoparticles. - Graphical Abstract: The H 2 -annealing induced enhancement of room temperature ferromagnetism in Cr-doped ZnO nanoparticles is observed. It is found that the field-cooled M-T curves can be well fitted by a combination of a standard Bloch spin-wave model and Curie–Weiss law. The values of the fitted parameters of the ferromagnetic exchange interaction constant a and the Curie constant C of H 2 -annealed Zn 0.97 Cr 0.03 O:H nanoparticles are almost doubled upon H 2 -annealing. The PL data show evidence that the hydrogen related shallow donor defect or/and defect complexes may be responsible for it. Display Omitted Highlights: ► The H 2 -annealing induced a large enhancement of

  8. Interaction between a high density-low temperature plasma and a frozen hydrogen pellet in a railgun injector

    International Nuclear Information System (INIS)

    Grapperhaus, M.J.

    1993-01-01

    A model has been developed which describes the ablation process of frozen hydrogen pellets in an electromagnetic railgun. The model incorporates the neutral gas shielding model in which the pellet surface is heated by incident electrons from the plasma arc. The heated surface then ablates, forming a neutral cloud which attenuates the incoming electrons. The energy lost in the cloud by the electrons heats the ablatant material as it flows into the plasma arc. Under steady-state conditions, a scaling law for the ablation rate was derived as a function of plasma-arc temperature and density. In addition, flow conditions and the criteria for the existence of a steady-state solution were formulated and subsequently examined under simplifying assumptions. Comparison with experimentally observed ablation rates shows good qualitative agreement

  9. Study of nickel hydrogen battery discharge performance after charge and stand at warm temperature

    International Nuclear Information System (INIS)

    Donley, S.W.; Verrier, D.C.

    1992-01-01

    Spacecraft batteries are normally installed in the discharged condition. It may be necessary that they be charged and trickle-charged prior to launch in an environment different from that in which they are intended to operate. The purpose of the testing described in this paper was to determine the battery capacity achieved after treatment at prelaunch conditions as a function of charge rate, charge temperature, trickle charge temperature, and time. In this testing the discharge in every case was performed under simulated space thermal conditions

  10. Durability and regeneration of catalysts of the iron family in hydrogenation of low-temperature tar

    Energy Technology Data Exchange (ETDEWEB)

    Funasaka, W; Yokogawa, C; Hayashi, K; Kawamura, T; Fujita, H; Suga, S

    1949-01-01

    The low-temperature tar consisting of neutral and acidic oils has been reduced under atmospheric pressure between 400/sup 0/ and 500/sup 0/ by using catalysts prepared from Fe-Cr-kieselguhr, yellow ocher, and other material. When the reduction was performed at 480/sup 0/ with the yellow ocher from Niwasaka, Fukushima Prefacture, Japan, the low-temperature tar was easily converted to neutral and light oils and the catalysts could be regenerated by repeated baking and reduction. It is concluded that the commercialization of this reduction process is possible by using a cycle (each takes 20 minutes) composed of catalytic reaction, baking, and reduction of the catalysts.

  11. Analysis of shade, temperature and hydrogen peroxide concentration during dental bleaching: in vitro study with the KTP and diode lasers.

    Science.gov (United States)

    Fornaini, C; Lagori, G; Merigo, E; Meleti, M; Manfredi, M; Guidotti, R; Serraj, A; Vescovi, P

    2013-01-01

    Many dental bleaching techniques are now available, several of them using a laser source. However, the literature on the exact role of coherent light in the biochemical reaction of the whitening process is very discordant. The aims of this in vitro study were: (1) to compare two different laser sources, a KTP laser with a wavelength of 532 nm and a diode laser with a wavelength of 808 nm, during dental bleaching, and (2) to investigate the relationships among changes in gel temperature, tooth shade and hydrogen peroxide (HP) concentration during laser irradiation. Altogether, 116 bovine teeth were bleached using a 30% HP gel, some of them with gel only and others with gel plus one of the two lasers (532 or 808 nm) at two different powers (2 and 4 W). The KTP laser produced a significant shade variation with a minimal temperature increase. The diode laser led to a higher temperature increase with a greater reduction in HP concentration, but the change in shade was only statistically significant with a power of 4 W. At a power of 2 W, the KTP laser caused a greater change in shade than the diode laser. No significant correlations were found among temperature, HP concentration and shade variation. The KTP laser appears to provide better results with less dangerous thermal increases than the diode laser. This might call into question most of the literature affirming that the action of laser bleaching is by increasing the gel temperature and, consequently, the speed of the redox reaction. Further study is required to investigate the correlations between the parameters investigated and efficacy of the bleaching process.

  12. Plants under dual attack

    NARCIS (Netherlands)

    Ponzio, C.A.M.

    2016-01-01

    Though immobile, plants are members of complex environments, and are under constant threat from a wide range of attackers, which includes organisms such as insect herbivores or plant pathogens. Plants have developed sophisticated defenses against these attackers, and include chemical responses

  13. Heart attack - discharge

    Science.gov (United States)

    ... and lifestyle Cholesterol - drug treatment Controlling your high blood pressure Deep vein thrombosis - discharge Dietary fats explained Fast food tips Heart attack - discharge Heart attack - what to ask your doctor Heart bypass ... pacemaker - discharge High blood pressure - what to ask your doctor How to read ...

  14. WC as a non-platinum hydrogen evolution electrocatalyst for high temperature PEM water electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

    2012-01-01

    Tungsten carbide (WC) nanopowder was tested as a non-platinum cathode electrocatalyst for polymer electrolyte membrane (PEM) water electrolysers, operating at elevated temperatures. It was prepared in thermal plasma reactor with confined plasma jet from WO3 precursor in combination with CH4...

  15. 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

    . The vessel dynamics are modeled using a simplified engineering and a CFD model to evaluate the performance of various EOS to predict vessel pressures, temperatures mass flow rates and jet flame lengths. It is shown that the chosen EOS and the chosen specific heat capacity correlation are important to model...

  16. Hydrogen- and helium-implanted silicon: Low-temperature positron-lifetime studies

    DEFF Research Database (Denmark)

    Mäkinen, S.; Rajainmäki, H.; Linderoth, Søren

    1991-01-01

    High-purity single-crystal samples of float-zoned Si have been implanted with 6.95-MeV protons and with 25-MeV 3He2 ions at 15 K, and the positron-lifetime technique has been used to identify the defects created in the samples, and to study the effects of H and He on the annealing of point defects...... in Si. The results have been compared with those of proton-irradiated Si. A 100–300-K annealing stage was clearly observed in hydrogen (H+) -implanted Si, and this stage was almost identical to that in the p-irradiated Si. The final annealing state of the H+-implanted Si started at about 400 K......, and it is connected to annealing out of negatively charged divacancy-oxygen pairs. This stage was clearly longer than that for the p-irradiated Si, probably due to the breakup of Si-H bonds at about 550 K. The 100-K annealing stage was not seen with the He-implanted samples. This has been explained by assuming...

  17. Hydrogen Embrittlement

    Science.gov (United States)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    hydrogen embrittlement. The effects of hydrogen gas on mechanical properties such as tensile strength, ductility, fracture, low and high cycle fatigue, crack growth rate, and creep rupture are analyzed with respect to the general trends established from the HEE index values. It is observed that the severity of HE effects is also influenced by environmental factors such as pressure, temperature, and hydrogen gas purity. The severity of HE effects is also influenced by material factors such as surface finish, heat treatment, and product forms, compositions, grain direction, and crystal orientations.

  18. A low-temperature partial-oxidation-methanol micro reformer with high fuel conversion rate and hydrogen production yield

    International Nuclear Information System (INIS)

    Wang, Hsueh-Sheng; Huang, Kuo-Yang; Huang, Yuh-Jeen; Su, Yu-Chuan; Tseng, Fan-Gang

    2015-01-01

    Highlights: • A low-operating temperature of the POM-mode micro methanol reformer is obtained. • The effect of channel design on the performance is studied. • The effect of solid content and binder’ ratio on the performance is studied. • The centrifugal process is benefit for the modification of performance. • 98% of methanol conversion rate of the micro reformer can be obtained at 180 °C. - Abstract: A partial oxidation methanol micro reformer (POM-μReformer) with finger-shaped channels for low operating temperature and high conversing efficiency is proposed in this study. The micro reformer employs POM reaction for low temperature operation (less than 200 °C), exothermic reaction, and quick start-up, as well as air feeding capability; and the finger type reaction chambers for increasing catalyst loading as well as reaction area for performance enhancement. In this study, centrifugal technique was introduced to assist on the catalyst loading with high amount and uniform distribution. The solid content (S), binder’s ratio (B), and channel design (the ratio between channel’s length and width, R) were investigated in detail to optimize the design parameters. Scanning electron microscopy (SEM), gas chromatography (GC), and inductively coupled plasma-mass spectrometer (ICP-MS) were employed to analyze the performance of the POM-μReformer. The result depicted that the catalyst content and reactive area could be much improved at the optimized condition, and the conversion rate and hydrogen selectivity approached 97.9% and 97.4%, respectively, at a very low operating temperature of 180 °C with scarce or no binder in catalyst. The POM-μReformer can supply hydrogen to fuel cells by generating 2.23 J/min for 80% H 2 utilization and 60% fuel cell efficiency at 2 ml/min of supplied reactant gas, including methanol, oxygen and argon at a mixing ratio of 12.2%, 6.1% and 81.7%, respectively

  19. Reactivity of hydrogen with uranium in the presence of Pt

    International Nuclear Information System (INIS)

    Balooch, M.; Siekhaus, W.J.

    1997-07-01

    The surface-reaction of di-hydrogen with uranium in the presence of Pt clusters has been studied using scanning tunneling microscopy (STM). Uranium was deposited on highly oriented pyrolytic graphite (HOPG) and annealed at temperatures up to 1200 degrees C to obtain atomically pyrolytic flat surfaces. Pt clusters were then formed using evaporation from a Pt source onto the surface and subsequent annealing. Hydrogen mainly attacked uranium in the vicinity of Pt clusters and formed hydride. The hydride formation probability is almost constant at 2.3x10 -4 over the range of exposures studied

  20. Isotopic studies on ligand exchange between complex and simple cyanides in aqueous medium and in liquid hydrogen cyanide. Part 1. Rate law and temperature dependence study of the radiocyanide exchange between hydrogen cyanide and octacyanotungstate(4) in aque us medium

    International Nuclear Information System (INIS)

    Zielinski, M.

    1978-01-01

    Dark radiocyanide ligand exchange in the closed system consisting of K 4 W(CN) 8 , hydrogen cyanide and water have been investigated. It has been found that the reaction is first order in respect to the complex cyanide and zero order in respect to the free hydrogen cyanide. Arrhenius activation energy within the temperature interval of 20-100 0 C equals to 32.373 kcal/mole. Enthalpy and entropy of activation are correspondingly ΔH not equal to Λ31.716kcal/mole and ΔS not equal to =5.45 e.u. A preliminary discussion of the above findings is presented. (author)

  1. Emergence of a high-temperature superconductivity in hydrogen cycled Pd compounds as an evidence for super-stoichiometric H/D sites

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, Andrei; Castano, Carlos; Miley, George [University of Illinois at Urbana - Champaign, lL (United States); Lipson, Andrei; Lyakhov, Boris [lnstitute of Physical Chemistry, RAS, Moscow (Russian Federation); Mitin, Alexander [P. Kapitza Institute for Physical Problems, RAS, Moscow (Russian Federation)

    2006-07-01

    Transport and magnetic properties of hydrogen cycled PdH{sub x} and Pd/PdO:H{sub x} (x {approx} = (4/6) x 10{sup -4}) nano-composite consisting of a Pd matrix with hydrogen trapped inside dislocation cores have been studied. The results suggest emergence of a high-temperature superconductivity stale of a condensed hydrogen phase confined inside deep dislocation cores in the Pd matrix. The possible role of hydrogen/deuterium filled dislocation nano-tubes is discussed. These dislocation cores could be considered as active centers of LENR triggering due to (i) short D-D separation distance ({approx}Bohr radius); (ii) high-local D-loading in the Pd and the corresponding effective lattice compression; (iii) a large optic phonon energy resulting in a most effective lattice-nuclei energy transfer.

  2. Emergence of a high-temperature superconductivity in hydrogen cycled Pd compounds as an evidence for super-stoichiometric H/D sites

    International Nuclear Information System (INIS)

    Lipson, Andrei; Castano, Carlos; Miley, George; Lipson, Andrei; Lyakhov, Boris; Mitin, Alexander

    2006-01-01

    Transport and magnetic properties of hydrogen cycled PdH x and Pd/PdO:H x (x ∼ = (4/6) x 10 -4 ) nano-composite consisting of a Pd matrix with hydrogen trapped inside dislocation cores have been studied. The results suggest emergence of a high-temperature superconductivity stale of a condensed hydrogen phase confined inside deep dislocation cores in the Pd matrix. The possible role of hydrogen/deuterium filled dislocation nano-tubes is discussed. These dislocation cores could be considered as active centers of LENR triggering due to (i) short D-D separation distance (∼Bohr radius); (ii) high-local D-loading in the Pd and the corresponding effective lattice compression; (iii) a large optic phonon energy resulting in a most effective lattice-nuclei energy transfer

  3. Emergence of a High-Temperature Superconductivity in Hydrogen Cycled pd Compounds as AN Evidence for Superstoihiometric H/d Sites

    Science.gov (United States)

    Lipson, Andrei; Castano, Carlos; Miley, George; Lipson, Andrei; Lyakhov, Boris; Mitin, Alexander

    2006-02-01

    Transport and magnetic properties of hydrogen cycled PdHx and Pd/PdO:Hx (x ~ (4/6) × 10-4) nano-composite consisting of a Pd matrix with hydrogen trapped inside dislocation cores have been studied. The results suggest emergence of a high-temperature superconductivity state of a condensed hydrogen phase confined inside deep dislocation cores in the Pd matrix. The possible role of hydrogen/deuterium filled dislocation nano-tubes is discussed. These dislocation cores could be considered as active centers of LENR triggering due to (i) short D-D separation distance (~Bohr radius); (ii) high-local D-loading in the Pd and the corresponding effective lattice compression; (iii) a large optic phonon energy resulting in a most effective lattice-nuclei energy transfer.

  4. The problems of using a high-temperature sodium coolant in nuclear power plants for the production of hydrogen and other innovative applications

    Science.gov (United States)

    Sorokin, A. P.; Alexeev, V. V.; Kuzina, Ju. A.; Konovalov, M. A.

    2017-11-01

    The intensity of the hydrogen sources arriving from the third contour of installation in second in comparison with the hydrogen sources on NPP BN-600 increases by two - three order at using of high-temperature nuclear power plants with the sodium coolant (HT-NPP) for drawing of hydrogen and other innovative applications (gasification and a liquefaction of coal, profound oil refining, transformation of biomass to liquid fuel, in the chemical industry, metallurgy, the food-processing industry etc.). For these conditions basic new technological solutions are offered. The main condition of their implementation is raise of hydrogen concentration in the sodium coolant on two - three order in comparison with the modern NPP, in a combination to hydrogen removal from sodium and its pumping out through membranes from vanadium or niobium. The researches with use diffusive model have shown possibility to expel a casium inflow in sodium through a leakproof shell of fuel rods if vary such parameters as a material of fuel rods shell, its thickness and maintenance time at design of fuel rods for high-temperature NPP. However maintenance of high-temperature NPP in the presence of casium in sodium is inevitable at loss of leakproof of a fuel rods shell. In these conditions for minimisation of casium diffusion in structural materials it is necessary to provide deep clearing of sodium from cesium.

  5. Room-temperature electroluminescence of Er-doped hydrogenated amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gusev, Oleg; Bresler, Mikhail; Kuznetsov, Alexey; Kudoyarova, Vera; Pak, Petr; Terukov, Evgenii; Tsendin, Konstantin; Yassievich, Irina [A F Ioffe Physico-Technical Institute, Politekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); Fuhs, Walther [Hahn-Meitner Institut, Abteilung Photovoltaik, Rudower Chaussee 5, D-12489 Berlin (Germany); Weiser, Gerhard [Phillips-Universitat Marburg, Fachbereich Physik, D-35032 Marburg (Germany)

    1998-05-11

    We have observed room-temperature erbium-ion electroluminescence in erbium-doped amorphous silicon. Electrical conduction through the structure is controlled by thermally activated ionization of deep D{sup -} defects in an electric field and the reverse process of capture of mobile electrons by D{sup 0} states. Defect-related Auger excitation (DRAE) is responsible for excitation of erbium ions located close to dangling-bond defects. Our experimental data are consistent with the mechanisms proposed

  6. The reaction of hydrogen peroxide with Fe(II) ions at elevated temperatures

    DEFF Research Database (Denmark)

    Christensen, H.; Sehested, K.; Løgager, T.

    1993-01-01

    The rate constant for the reaction between Fe(II) ions and H2O2 has been determined at pH 0.4-2 as a function of temperature in the range 5-300-degrees-C. H2O2 was produced by irradiating the aqueous solution with a pulse of electrons. The rate constants at 20 and 300-degrees-C were determined...

  7. Isotope dependent, temperature regulated, energy repartitioning in a low-barrier, short-strong hydrogen bonded cluster

    NARCIS (Netherlands)

    Li, X. H.; Oomens, J.; Eyler, J. R.; Moore, D. T.; Iyengar, S. S.

    2010-01-01

    We investigate and analyze the vibrational properties, including hydrogen/deuterium isotope effects, in a fundamental organic hydrogen bonded system using multiple experimental (infrared multiple photon dissociation and argon-tagged action spectroscopy) and computational techniques. We note a

  8. 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...

  9. HYBRID SULFUR CYCLE FLOWSHEETS FOR HYDROGEN PRODUCTION USING HIGH-TEMPERATURE GAS-COOLED REACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Gorensek, M.

    2011-07-06

    Two hybrid sulfur (HyS) cycle process flowsheets intended for use with high-temperature gas-cooled reactors (HTGRs) are presented. The flowsheets were developed for the Next Generation Nuclear Plant (NGNP) program, and couple a proton exchange membrane (PEM) electrolyzer for the SO2-depolarized electrolysis step with a silicon carbide bayonet reactor for the high-temperature decomposition step. One presumes an HTGR reactor outlet temperature (ROT) of 950 C, the other 750 C. Performance was improved (over earlier flowsheets) by assuming that use of a more acid-tolerant PEM, like acid-doped poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI), instead of Nafion{reg_sign}, would allow higher anolyte acid concentrations. Lower ROT was accommodated by adding a direct contact exchange/quench column upstream from the bayonet reactor and dropping the decomposition pressure. Aspen Plus was used to develop material and energy balances. A net thermal efficiency of 44.0% to 47.6%, higher heating value basis is projected for the 950 C case, dropping to 39.9% for the 750 C case.

  10. Hydrogen storage in graphite nanofibers: effect of synthesis catalyst and pretreatment conditions.

    Science.gov (United States)

    Lueking, Angela D; Yang, Ralph T; Rodriguez, Nelly M; Baker, R Terry K

    2004-02-03

    A series of graphite nanofibers (GNFs) that were subjected to various pretreatments were used to determine how modifications in the carbon structure formed during either synthesis or pretreatment steps results in active or inactive materials for hydrogen storage. The nanofibers possessing a herringbone structure and a high degree of defects were found to exhibit the best performance for hydrogen storage. These materials were exposed to several pretreatment procedures, including oxidative, reductive, and inert environments. Significant hydrogen storage levels were found for several in situ pretreatments. Examination of the nanofibers by high-resolution transmission electron microscopy (TEM) after pretreatment and subsequent hydrogen storage revealed the existence of edge attack and an enhancement in the generation of structural defects. These findings suggest that pretreatment in certain environments results in the creation of catalytic sites that are favorable toward hydrogen storage. The best pretreatment resulted in a 3.8% hydrogen release after exposure at 69 bar and room temperature.

  11. PALLADIUM/COPPER ALLOY COMPOSITE MEMBRANES FOR HIGH TEMPERATURE HYDROGEN SEPARATION FROM COAL-DERIVED GAS STREAMS; F

    International Nuclear Information System (INIS)

    J. Douglas Way; Robert L. McCormick

    2001-01-01

    Recent advances have shown that Pd-Cu composite membranes are not susceptible to the mechanical, embrittlement, and poisoning problems that have prevented widespread industrial use of Pd for high temperature H(sub 2) separation. These membranes consist of a thin ((approx)10(micro)m) film of metal deposited on the inner surface of a porous metal or ceramic tube. Based on preliminary results, thin Pd(sub 60)Cu(sub 40) films are expected to exhibit hydrogen flux up to ten times larger than commercial polymer membranes for H(sub 2) separation, and resist poisoning by H(sub 2)S and other sulfur compounds typical of coal gas. Similar Pd-membranes have been operated at temperatures as high as 750 C. The overall objective of the proposed project is to demonstrate the feasibility of using sequential electroless plating to fabricate Pd(sub 60)Cu(sub 40) alloy membranes on porous supports for H(sub 2) separation. These following advantages of these membranes for processing of coal-derived gas will be demonstrated: High H(sub 2) flux; Sulfur tolerant, even at very high total sulfur levels (1000 ppm); Operation at temperatures well above 500 C; and Resistance to embrittlement and degradation by thermal cycling. The proposed research plan is designed to providing a fundamental understanding of: Factors important in membrane fabrication; Optimization of membrane structure and composition; Effect of temperature, pressure, and gas composition on H(sub 2) flux and membrane selectivity; and How this membrane technology can be integrated in coal gasification-fuel cell systems

  12. Reduction of hydrogen desorption temperature of ball-milled MgH2 by NbF5 addition

    International Nuclear Information System (INIS)

    Recham, N.; Bhat, V.V.; Kandavel, M.; Aymard, L.; Tarascon, J.-M.; Rougier, A.

    2008-01-01

    Enhanced sorption properties of ball-milled MgH 2 are reported by adding NbF 5 . Among various catalyst amounts, 2 mol% of NbF 5 reveals to be the optimum concentration leading to significant reduction of the desorption temperature as well as faster kinetics of ball-milled MgH 2 . At 200 deg. C, temperature at which MgH 2 does not show any activity, MgH 2NbF 5 /2mol% composite desorbs 3.2 wt.% of H 2 in 50 mins. Interestingly, the addition of NbF 5 is also associated with an increase in the desorption pressure. At 300 deg. C, MgH 2NbF 5 /2mol% composite starts to desorb hydrogen at 600 mbar in comparison with 1 mbar for MgH 2 . Further improvements were successfully achieved by pre-grinding NbF 5 prior to ball-milling the catalyst with MgH 2 . Such pre-ground NbF 5 catalyzed MgH 2 composite desorbs 3 wt.% of H 2 at 150 deg. C. Improved properties are associated with smaller activation energies down to values close to the enthalpy of formation of MgH 2 . Finally, the mechanism at the origin of the enhancement is discussed in terms of catalyst stability, MgF 2 formation and electronic density localization

  13. Influences of Structure Disorder and Temperature on Properties of Proton Conductivity in Hydrogen-Bond Molecular Systems

    Institute of Scientific and Technical Information of China (English)

    PANG Xiao-Feng; YU Jia-Feng

    2007-01-01

    The dynamic properties of proton conductivity along hydrogen-bonded molecular systems,for example,ice crystal,with structure disorder or damping and finite temperatures exposed in an externally applied electric-field have been numerically studied by Runge-Kutta way in our Soliton model.The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping of medium,the velocity of its conductivity increases with increasing of the externally applied electric-field and decreasing of the damping coefficient of medium,but the proton-soliton disperses for quite great fluctuation of the force constant and damping coefficient.In the numerical simulation we find that the proton-soliton in our model is thermally stable in a large region of temperature of T ≤ 273 K under influences of damping and externally applied electric-field in ice crystal.This shows that our model is available and appropriate to ice.

  14. Influences of Structure Disorder and Temperature on Properties of Proton Conductivity in Hydrogen-Bond Molecular Systems

    International Nuclear Information System (INIS)

    Pang Xiaofeng; Yu Jiafeng

    2007-01-01

    The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-field have been numerically studied by Runge-Kutta way in our soliton model. The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping of medium, the velocity of its conductivity increases with increasing of the externally applied electric-field and decreasing of the damping coefficient of medium, but the proton-soliton disperses for quite great fluctuation of the force constant and damping coefficient. In the numerical simulation we find that the proton-soliton in our model is thermally stable in a large region of temperature of T≤273 K under influences of damping and externally applied electric-field in ice crystal. This shows that our model is available and appropriate to ice.

  15. Reaction of chlorine nitrate with hydrogen chloride and water at Antarctic stratospheric temperatures

    Science.gov (United States)

    Tolbert, Margaret A.; Rossi, Michel J.; Malhotra, Ripudaman; Golden, David M.

    1987-01-01

    Laboratory studies of heterogeneous reactions important for ozone depletion over Antarctica are reported. The reaction of chlorine nitrate (ClONO2) with H2O and HCl on surfacers that simulate polar stratospheric clouds are studied at temperatures relevant to the Antarctic stratosphere. The gaseous products of the resulting reactions, HOCl, Cl2O, and Cl2, could readily photolyze in the Antarctic spring to produce active chlorine for ozone depletion. Furthermore, the additional formation of condensed-phase HNO3 could serve as a sink for odd nitrogen species that would otherwise scavenge the active chlorine.

  16. Catalytic steam gasification of biomass in fluidized bed at low temperature: Conversion from livestock manure compost to hydrogen-rich syngas

    International Nuclear Information System (INIS)

    Xiao, Xianbin; Le, Duc Dung; Li, Liuyun; Meng, Xianliang; Cao, Jingpei; Morishita, Kayoko; Takarada, Takayuki

    2010-01-01

    Utilizing large amounts of animal waste as a source of renewable energy has the potential to reduce its disposal problems and associated pollution issues. Gasification characteristics of the manure compost make it possible for low temperature gasification. In this paper, an energy efficient approach to hydrogen-rich syngas from manure compost is represented at relatively low temperature, around 600 o C, in a continuous-feeding fluidized bed reactor. The effects of catalyst performance, reactor temperature, steam, and reaction type on gas yield, gas composition, and carbon conversion efficiency are discussed. The Ni-Al 2 O 3 catalyst simultaneously promotes tar cracking and steam reforming. Higher temperature contributes to higher gas yield and carbon conversion. The steam introduction increases hydrogen yield, by steam reforming and water-gas shift reaction. Two-stage gasification is also tried, showing the advantage of better catalyst utilization and enhancing the catalytic reactions to some extent.

  17. Interactions of hydrogen with graphite at low pressure and elevated temperature

    International Nuclear Information System (INIS)

    Hoinkis, E.

    1991-03-01

    The plasma facing components of the vacuum chamber for thermonuclear fusion experiments are clad with graphite. Recycling of gases affects the plasma properties, and the tritium quantity accumulated in the graphite during the operation of Tokamaks with DT must be known. An adsorption isotherm for deuterium on the nuclear grade graphitic Matrix A3-3 was measured by using a volumetric method at 1173 K at pressures c = 2.5 eV/D 2 using Fowler's equation and isotherms were calculated for this E c value. These isotherms predict saturation of the adsorption sites in graphite at T D2 > 0.1 Pa. At T > 1173 K and P D2 -2 Pa the adsorbed quantity is less than 1% of the saturation level. The release kinetics of deuterium was measured at temperatures uo to 2000 K. D 2 desorption commenced at 1170 K. The maximum of the release rate is observed at T p = 1770 K. A Lennard-Jones potential energy diagram was calculated, which suggests a C-H bond energy E b ≅ 3.4 eV/D and an activation energy of desorption E d ≅ 4 eV/D 2 . The partial pressures of hydrocarbons C n ≤3 H m in equilibrium with graphite were calculated. At total pressures -2 Pa the partial pressures of these hydrocarbons are less than 10 -7 Pa in the temperature range 600-1500 K. (orig./MM)

  18. Partial local thermal equilibrium in a low-temperature hydrogen plasma

    International Nuclear Information System (INIS)

    Hey, J.D.; Chu, C.C.; Rash, J.P.S.

    1999-01-01

    If the degree of ionisation is sufficient, competition between de-excitation by electron collisions and radiative decay determines the smallest principal quantum number (the so-called 'thermal limit') above which partial local thermodynamic equilibrium (PLTE) holds under the particular conditions of electron density and temperature. The LTE (PLTE) criteria of Wilson (JQSRT 1962;2:477-90), Griem (Phys Rev 1963;131:1170-6; Plasma Spectroscopy. New York: McGraw-Hill, 1964), Drawin (Z Physik 1969;228: 99-119), Hey (JQSRT 1976;16:69-75), and Fujimoto and McWhirter (Phys Rev A 1990;42:6588-601) are examined as regards their applicability to neutral atoms. For these purposes, we consider for simplicity an idealised, steady-state, homogeneous and primarily optically thin plasma, with some additional comments and numerical estimates on the roles of opacity and of atom-atom collisions. Particularly for atomic states of lower principal quantum number, the first two of the above criteria should be modified quite appreciably before application to neutral radiators in plasmas of low temperature, because of the profoundly different nature of the near-threshold collisional cross-sections for atoms and ions, while the most recent criterion should be applied with caution to PLTE of atoms in cold plasmas in ionisation balance. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  19. High temperature hydrogen sulfide adsorption on activated carbon - I. Effects of gas composition and metal addition

    Science.gov (United States)

    Cal, M.P.; Strickler, B.W.; Lizzio, A.A.

    2000-01-01

    Various types of activated carbon sorbents were evaluated for their ability to remove H2S from a simulated coal gas stream at a temperature of 550 ??C. The ability of activated carbon to remove H2S at elevated temperature was examined as a function of carbon surface chemistry (oxidation, thermal desorption, and metal addition), and gas composition. A sorbent prepared by steam activation, HNO3 oxidation and impregnated with Zn, and tested in a gas stream containing 0.5% H2S, 50% CO2 and 49.5% N2, had the greatest H2S adsorption capacity. Addition of H2, CO, and H2O to the inlet gas stream reduced H2S breakthrough time and H2S adsorption capacity. A Zn impregnated activated carbon, when tested using a simulated coal gas containing 0.5% H2S, 49.5% N2, 13% H2, 8.5% H2O, 21% CO, and 7.5% CO2, had a breakthrough time of 75 min, which was less than 25 percent of the length of breakthrough for screening experiments performed with a simplified gas mixture of 0.5% H2S, 50% CO2, and 49.5% N2.

  20. An Analysis of Methanol and Hydrogen Production via High-Temperature Electrolysis Using the Sodium Cooled Advanced Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shannon M. Bragg-Sitton; Richard D. Boardman; Robert S. Cherry; Wesley R. Deason; Michael G. McKellar

    2014-03-01

    Integration of an advanced, sodium-cooled fast spectrum reactor into nuclear hybrid energy system (NHES) architectures is the focus of the present study. A techno-economic evaluation of several conceptual system designs was performed for the integration of a sodium-cooled Advanced Fast Reactor (AFR) with the electric grid in conjunction with wind-generated electricity. Cases in which excess thermal and electrical energy would be reapportioned within an integrated energy system to a chemical plant are presented. The process applications evaluated include hydrogen production via high temperature steam electrolysis and methanol production via steam methane reforming to produce carbon monoxide and hydrogen which feed a methanol synthesis reactor. Three power cycles were considered for integration with the AFR, including subcritical and supercritical Rankine cycles and a modified supercritical carbon dioxide modified Brayton cycle. The thermal efficiencies of all of the modeled power conversions units were greater than 40%. A thermal efficiency of 42% was adopted in economic studies because two of the cycles either performed at that level or could potentially do so (subcritical Rankine and S-CO2 Brayton). Each of the evaluated hybrid architectures would be technically feasible but would demonstrate a different internal rate of return (IRR) as a function of multiple parameters; all evaluated configurations showed a positive IRR. As expected, integration of an AFR with a chemical plant increases the IRR when “must-take” wind-generated electricity is added to the energy system. Additional dynamic system analyses are recommended to draw detailed conclusions on the feasibility and economic benefits associated with AFR-hybrid energy system operation.

  1. 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

  2. A rod-packing microporous hydrogen-bonded organic framework for highly selective separation of C2H2/CO2at room temperature

    KAUST Repository

    Li, Peng

    2014-11-13

    Self-assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod-packing 3D microporous hydrogen-bonded organic framework (HOF-3). This material shows permanent porosity and demonstrates highly selective separation of C2H2/CO2 at ambient temperature and pressure.

  3. A rod-packing microporous hydrogen-bonded organic framework for highly selective separation of C2H2/CO2at room temperature

    KAUST Repository

    Li, Peng; He, Yabing; Zhao, Yunfeng; Weng, Linhong; Wang, Hailong; Krishna, Rajamani A A; Wu, Hui; Zhou, Wei; O'Keeffe, Michael A.; Han, Yu; Chen, Banglin

    2014-01-01

    Self-assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod-packing 3D microporous hydrogen-bonded organic framework (HOF-3). This material shows permanent porosity and demonstrates highly selective separation of C2H2/CO2 at ambient temperature and pressure.

  4. Effects of aging temperature on electrical conductivity and hardness of Cu-3 at. pct Ti alloy aged in a hydrogen atmosphere

    KAUST Repository

    Semboshi, S.; Nishida, T.; Numakura, H.; Al-Kassab, T.; Kirchheim, R.

    2011-01-01

    To improve the balance of the electrical conductivity and mechanical strength for dilute Cu-Ti alloys by aging in a hydrogen atmosphere, the influence of aging temperature ranging from 673 K to 773 K (400 °C to 500 °C) on the properties of Cu-3 at

  5. Analysis of silicon-based integrated photovoltaic-electrochemical hydrogen generation system under varying temperature and illumination

    Institute of Scientific and Technical Information of China (English)

    Vishwa Bhatt; Brijesh Tripathi; Pankaj Yadav; Manoj Kumar

    2017-01-01

    Last decade witnessed tremendous research and development in the area of photo-electrolytic hydrogen generation using chemically stable nanostructured photo-cathode/anode materials.Due to intimately coupled charge separation and photo-catalytic processes,it is very difficult to optimize individual components of such system leading to a very low demonstrated solar-to-fuel efficiency (SFE) of less than 1%.Recently there has been growing interest in an integrated photovoltaic-electrochemical (PV-EC) system based on GaAs solar cells with the demonstrated SFE of 24.5% under concentrated illumination condition.But a high cost of GaAs based solar cells and recent price drop of poly-crystalline silicon (pc-Si) solar cells motivated researchers to explore silicon based integrated PV-EC system.In this paper a theoretical framework is introduced to model silicon-based integrated PV-EC device.The theoretical framework is used to analyze the coupling and kinetic losses of a silicon solar cell based integrated PV-EC water splitting system under varying temperature and illumination.The kinetic loss occurs in the range of 19.1%-27.9% and coupling loss takes place in the range of 5.45%-6.74% with respect to varying illumination in the range of 20-100 mW/cm2.Similarly,the effect of varying temperature has severe impact on the performance of the system,wherein the coupling loss occurs in the range of 0.84%-21.51% for the temperature variation from 25 to 50 ℃.

  6. Heart Attack Payment - National

    Data.gov (United States)

    U.S. Department of Health & Human Services — Payment for heart attack patients measure – national data. This data set includes national-level data for payments associated with a 30-day episode of care for heart...

  7. Heart Attack Payment - Hospital

    Data.gov (United States)

    U.S. Department of Health & Human Services — Payment for heart attack patients measure – provider data. This data set includes provider data for payments associated with a 30-day episode of care for heart...

  8. Heart Attack Payment - State

    Data.gov (United States)

    U.S. Department of Health & Human Services — Payment for heart attack patients measure – state data. This data set includes state-level data for payments associated with a 30-day episode of care for heart...

  9. Corrosion resistant materials for fluorine and hydrogen fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Hauffe, K.

    1984-12-01

    Aluminum and Duralumin are resistant against fluorine and hydrogen fluoride up to 600 and 700 K, respectively. The resistance of nickel and its alloys, particularly monel, against fluorine and hydrogen fluoride is fairly good up to 900 and 800 K. During the attack of nickel-chromium alloys by fluorine between 1000 and 1300 K, it appears an inner fluorination similarly to the inner oxidation. The resistance of titanium in water-free liquid fluorine at lower temperatures with <0,3 mm.a/sup -1/ is comparable to that of nickel and monel. However, the corrosion of titanium in gaseous fluorine amounts at 377 K only 0,0082 mm.a/sup -1/. In spite of their limited resistance against fluorine and hydrogen fluoride, very pure molybdenum and tungsten are employed as construction materials in the rocket technology because of their large strength at high temperatures if fluorine-hydrogen and fluorine-hydrazine flames are used. Lanthanum and calcium borides are only little attacked by fluorine hydrazine flames between 1400 and 1800 K; they are superior to all special grade alloys. The same is true in a lower temperature region (290-400 K) with fluorcarbon resins. Organic materials substitute in increasing extent metal alloys and non-metal inorganic materials.

  10. Corrosion resistant materials for fluorine and hydrogen fluoride

    International Nuclear Information System (INIS)

    Hauffe, K.

    1984-01-01

    Aluminum and Duralumin are resistant against fluorine and hydrogen fluoride up to 600 and 700 K, respectively. The resistance of nickel and its alloys, particularly monel, against fluorine and hydrogen fluoride is fairly good up to 900 and 800 K. During the attack of nickel-chromium alloys by fluorine between 1000 and 1300 K, it appears an inner fluorination similarly to the inner oxidation. The resistance of titanium in water-free liquid fluorine at lower temperatures with -1 is comparable to that of nickel and monel. However, the corrosion of titanium in gaseous fluorine amounts at 377 K only 0,0082 mm.a -1 . In spite of their limited resistance against fluorine and hydrogen fluoride, very pure molybdenum and tungsten are employed as construction materials in the rocket technology because of their large strength at high temperatures if fluorine-hydrogen and fluorine-hydrazine flames are used. Lanthanum and calcium borides are only little attacked by fluorine hydrazine flames between 1400 and 1800 K; they are superior to all special grade alloys. The same is true in a lower temperature region (290-400 K) with fluorcarbon resins. Organic materials substitute in increasing extent metal alloys and non-metal inorganic materials. (orig.) [de

  11. Cooperating attackers in neural cryptography.

    Science.gov (United States)

    Shacham, Lanir N; Klein, Einat; Mislovaty, Rachel; Kanter, Ido; Kinzel, Wolfgang

    2004-06-01

    A successful attack strategy in neural cryptography is presented. The neural cryptosystem, based on synchronization of neural networks by mutual learning, has been recently shown to be secure under different attack strategies. The success of the advanced attacker presented here, called the "majority-flipping attacker," does not decay with the parameters of the model. This attacker's outstanding success is due to its using a group of attackers which cooperate throughout the synchronization process, unlike any other attack strategy known. An analytical description of this attack is also presented, and fits the results of simulations.

  12. Influence of γ-irradiation on the transport kinetics of hydrogen in pre-transition oxidized Zircaloy-4 at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Frantz A., E-mail: frantz.martin@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, F-91191 Gif-sur-Yvette (France); Dauvois, Vincent, E-mail: vincent.dauvois@cea.fr [CEA, DEN, DPC, SECR, Laboratoire de Radiolyse et de la Matière Organique, F-91191 Gif-sur-Yvette (France); Esnouf, Stéphane, E-mail: stephane.esnouf@cea.fr [CEA, DEN, DPC, SECR, Laboratoire de Radiolyse et de la Matière Organique, F-91191 Gif-sur-Yvette (France); CEA, DSM, IRAMIS, LIDYL, PCR, F-91191 Gif-sur-Yvette (France); Fourdrin, Chloé, E-mail: chloe.fourdrin@culture.gouv.fr [CEA, DEN, DPC, SECR, Laboratoire de Radiolyse et de la Matière Organique, F-91191 Gif-sur-Yvette (France); Jomard, François, E-mail: francois.jomard@uvsq.fr [CNRS/UVSQ, UMR 8635, GEMAC, 45 avenue des Etats Unis – Bâtiment Fermat, F-78035 Versailles (France); Chêne, Jacques, E-mail: chene_jacques@orange.fr [CNRS/CEA, UMR 8587, LECA – CEA, Saclay, F-91191 Gif-sur-Yvette (France)

    2015-10-15

    In a context of nuclear fuel reprocessing, the free-of-fuel hulls and ends of cladding tubes are compacted. The possibility of hydrogen degasing or absorption from/into these tubes has been studied with and without gamma irradiation at 293 K by means of deuterium as isotopic tracer for hydrogen. Under irradiation, as without, the hydrides present in the Zircaloy-4 hulls seem stable. The oxide layer present at the surface of the hulls allows a slow diffusion of deuterium, and the irradiation appeared to have no specific effect on the diffusion process: in both cases, hydrogen diffusion coefficients of the order of 5·10{sup −18} cm{sup 2} s{sup −1} have been found. The subsurface activity of deuterium is increased by one order of magnitude at least under irradiation, probably due to an activation of the dissociation/absorption kinetic steps. - Highlights: • Hydrogen diffusion coefficients at RT in zirconia grain boundaries were determined. • γ irradiation increases the hydrogen subsurface activity when exposed to H{sub 2} gas. • The dense thin zirconia film is not altered much by HNO{sub 3} exposure at 90 °C for 24 h. • Hydrogen desorption from Zr hydrides was studied at room temperature under γ rays.

  13. Long-Term Demonstration of Hydrogen Production from Coal at Elevated Temperatures Year 6 - Activity 1.12 - Development of a National Center for Hydrogen Technology

    Energy Technology Data Exchange (ETDEWEB)

    Stanislowski, Joshua; Tolbert, Scott; Curran, Tyler; Swanson, Michael

    2012-04-30

    The Energy & Environmental Research Center (EERC) has continued the work of the National Center for Hydrogen Technology® (NCHT®) Program Year 6 Task 1.12 project to expose hydrogen separation membranes to coal-derived syngas. In this follow-on project, the EERC has exposed two membranes to coal-derived syngas produced in the pilot-scale transport reactor development unit (TRDU). Western Research Institute (WRI), with funding from the State of Wyoming Clean Coal Technology Program and the North Dakota Industrial Commission, contracted with the EERC to conduct testing of WRI’s coal-upgrading/gasification technology for subbituminous and lignite coals in the EERC’s TRDU. This gasifier fires nominally 200–500 lb/hour of fuel and is the pilot-scale version of the full-scale gasifier currently being constructed in Kemper County, Mississippi. A slipstream of the syngas was used to demonstrate warm-gas cleanup and hydrogen separation using membrane technology. Two membranes were exposed to coal-derived syngas, and the impact of coal-derived impurities was evaluated. This report summarizes the performance of WRI’s patent-pending coalupgrading/ gasification technology in the EERC’s TRDU and presents the results of the warm-gas cleanup and hydrogen separation tests. Overall, the WRI coal-upgrading/gasification technology was shown to produce a syngas significantly lower in CO2 content and significantly higher in CO content than syngas produced from the raw fuels. Warm-gas cleanup technologies were shown to be capable of reducing sulfur in the syngas to 1 ppm. Each of the membranes tested was able to produce at least 2 lb/day of hydrogen from coal-derived syngas.

  14. Modeling low-temperature serpentinization reactions to estimate molecular hydrogen production with implications for potential microbial life on Saturn's moon Enceladus.

    Science.gov (United States)

    Zwicker, Jennifer; Smrzka, Daniel; Taubner, Ruth-Sophie; Bach, Wolfgang; Rittmann, Simon; Schleper, Christa; Peckmann, Jörn

    2017-04-01

    Serpentinization of ultramafic rocks attracts much interest in research on the origin of life on Earth and the search for life on extraterrestrial bodies including icy moons like Enceladus. Serpentinization on Earth occurs in peridotite-hosted systems at slow-spreading mid-ocean ridges, and produces large amounts of molecular hydrogen and methane. These reduced compounds can be utilized by diverse chemosynthetic microbial consortia as a metabolic energy source. Although many hydrothermal vents emit hot and acidic fluids today, it is more likely that life originated in the Archean at sites producing much cooler and more alkaline fluids that allowed for the synthesis and stability of essential organic molecules necessary for life. Therefore, a detailed understanding of water-rock interaction processes during low-temperature serpentinization is of crucial importance in assessing the life-sustaining potential of these environments. In the course of serpentinization, the metasomatic hydration of olivine and pyroxene produces various minerals including serpentine minerals, magnetite, brucite, and carbonates. Hydrogen production only occurs if ferrous iron within iron-bearing minerals is oxidized and incorporated as ferric iron into magnetite. The PHREEQC code was used to model the pH- and temperature-dependent dissolution of olivine and pyroxene to form serpentine, magnetite and hydrogen under pressure and temperature conditions that may exist on Saturn's icy moon Enceladus. Various model setups at 25 and 50°C were run to assess the influence of environmental parameters on hydrogen production. The results reveal that hydrogen production rates depend on the composition of the initial mineral assemblage and temperature. The current assumption is that there is a gaseous phase between Enceladus' ice sheet and subsurface ocean. To test various scenarios, model runs were conducted with and without the presence of a gas phase. The model results show that hydrogen production is

  15. Evaluation of the security of a hydrogen producing plant by means of the S I cycle coupled to a nuclear reactor of high temperature

    International Nuclear Information System (INIS)

    Ruiz S, T.; Francois, J. L.; Nelson, P. F.; Cruz G, M. J.

    2011-11-01

    At the present one of the processes that demonstrates, theoretically, to be one of the most efficient for the hydrogen production is the thermal-chemistry cycle Sulfur-Iodine. One way of obtaining the temperature ranges required by the process is through the helium coming from a very high temperature reactor. The coupling of the chemical plant with the nuclear plant presents aspects of security that should be analyzed; among them the analysis of the danger of the process materials is, with the purpose of implementing security measures to protect the facilities and equipment s, the environment and the population. These measures can be: emergency answer plans of the stations, definition of the minimum distance required among facilities, determination of the exclusion area, etc. In this study simulations were made with the computer code Phast in order to knowing the possible affectation areas due to the liberation of a great quantity of energy due to a helium leak to very high temperature, of toxic materials or by a possible hydrogen combustion. The results for the liberations of sulfuric acid, hydrogen, iodine, helium and sulfur dioxide are shown, specially. The operation conditions were taken of a combination of the preliminary design proposed by General Atomics and the optimized conditions by the Korea Advanced Institute of Science and Technology, considering a production of 1 kg-mol/s of hydrogen. The iodine was the material that presented a major affectation area. (Author)

  16. Impact of temperature and substrate concentration on degradation rates of acetate, propionate and hydrogen and their links to microbial community structure.

    Science.gov (United States)

    Zhao, Jing; Westerholm, Maria; Qiao, Wei; Yin, Dongmin; Bi, Shaojie; Jiang, Mengmeng; Dong, Renjie

    2018-05-01

    The present study investigates the conversion of acetate, propionate and hydrogen consumption linked to the microbial community structure and related to temperature and substrate concentration. Biogas reactors were continuously fed with coffee powder (20 g-COD/L) or acetate (20, 40, and 60 g-COD/L) and operated for 193 days at 37 °C or 55 °C conditions. Starting HRT was 23 days which was then reduced to 7 days. The kinetics of acetate and propionate degradation and hydrogen consumption rates were measured in batch assays. At HRT 7 days, the degradation rate of propionate was higher in thermophilic batches, while acetate degradation rate was higher at mesophilic conditions. The gaseous hydrogen consumption in acetate reactors increased proportionally with temperature and substrate concentration, while the dissolved hydrogen was not affected. The relative high abundance of hydrogentrophic methanogens indicated that the methanogenesis was directed towards the syntrophic acetate oxidation pathway at high acetate concentration and high temperature. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Process flow sheet evaluation of a nuclear hydrogen steelmaking plant applying very high temperature reactors for efficient steel production with less CO{sub 2} emissions

    Energy Technology Data Exchange (ETDEWEB)

    Kasahara, Seiji, E-mail: kasahara.seiji@jaea.go.jp; Inagaki, Yoshiyuki; Ogawa, Masuro

    2014-05-01

    Highlights: • CO{sub 2} emissions from a nuclear hydrogen steelmaking system was 13–21% of that from a blast furnace steelmaking system. • Heat input to shaft furnace in hydrogen steelmaking was large with much H{sub 2} consumption in the part. • Though hydrogen production thermal efficiency had influence on total heat input to hydrogen steelmaking, the effect on the CO{sub 2} emissions was small. • Steelmaking scale of a nuclear hydrogen steelamking plant with 2 VHTRs was a little smaller than that of the largest Midrex{sup ®} steelmaking plants. - Abstract: Recently, CO{sub 2} reduction is an important problem for steelmaking. Substitution of coal, presently used as a reducing agent of iron ore in blast furnaces, to hydrogen produced by non-fossil energy is a way to reduce CO{sub 2} emissions. In this study, the idea of nuclear hydrogen steelmaking (NHS) system was investigated using very high temperature reactor (VHTR) and thermochemical hydrogen production iodine–sulfur (IS) process. Heat input and CO{sub 2} emissions including material production, material transportation, and electricity generation were evaluation criteria. Results of the NHS system were compared with those of a conventional blast furnace steelmaking (BFS) system. Influence of heat input options to the steelmaking process and hydrogen production thermal efficiency of IS process were investigated for the NHS system. Though heat input to the NHS system was 130–142% of that to the BFS system, CO{sub 2} emissions of the system were 13–21%. Pre-heating of hydrogen by coal combustion before blowing to a shaft furnace was effective to decrease heat input, although CO{sub 2} emissions increased. Direct pre-heating by nuclear heat was also effective without increase of CO{sub 2} emissions if close location of the nuclear reactor to the steelmaking plant was publicly accepted. Hydrogen production thermal efficiency had a significant influence on the heat input. Conceptual design of a

  18. Development of nickel membranes deposited on ceramic materials by electroless plating: studies of the hydrogen perm-selectivity properties at elevated temperatures

    International Nuclear Information System (INIS)

    Amer, J.

    2008-09-01

    The main objective of this work was to synthesize nickel based membranes by electroless plating on materials such as alumina-α, alumina-γ and zirconia with various textures and to determine their hydrogen perm-selectivity at high temperatures. The synthesis of metal films of high purity (≥ 99% mass Ni) resulting from the choice of hydrazine with its dual role of reducing and complexing agent has revealed that the diameter of pores on the surface support has an impact on the quality of metal adherence. The various contributions of hydrogen transport through these composite membranes at low temperatures (Knudsen and surface diffusion) and at high temperatures (Knudsen and activated diffusion) was established. At its implementation in a membrane reactor (reaction of propane dehydrogenation), the layer of nickel showed a very good resistance to coking. (author)

  19. The effects of hydrothermal temperature on the photocatalytic performance of ZnIn2S4 for hydrogen generation under visible light irradiation

    International Nuclear Information System (INIS)

    Tian, Fei; Zhu, Rongshu; Song, Kelin; Niu, Minli; Ouyang, Feng; Cao, Gang

    2015-01-01

    Highlights: • The ZnIn 2 S 4 (120, 140, 160, 180, and 200 °C) was prepared. • The activities splitting water to hydrogen under visible light were evaluated. • The activity achieved the best when hydrothermal temperature was 160 °C. • The activity order is related to the surface morphology and surface defects. - Abstract: A series of ZnIn 2 S 4 photocatalysts were successfully synthesized using the hydrothermal method with different hydrothermal temperatures (120, 140, 160, 180, and 200 °C) and characterized by various analysis techniques, such as UV–vis, XRD, SEM, BET and PL. The results indicated that these photocatalysts had a similar band gap. The hydrothermal temperature had a huge influence on the properties of the photocatalysts such as the BET surface area, the total pore volume, the average pore diameter, the defects and the morphology. The photocatalytic activities of ZnIn 2 S 4 were evaluated based on photocatalytic hydrogen production from water under visible-light irradiation. The activity order is attributed to the coefficient of the surface morphology and the surface defects. The hydrogen production efficiency achieved the best when the hydrothermal temperature was 160 °C. On the basis of the characterization of the catalysts, the effects of the hydrothermal temperature on the photocatalytic activity of ZnIn 2 S 4 were discussed

  20. Equilibrium studies on liquid ammonia-potassium amide-hydrogen system at high pressures and temperatures (Preprint No. CA-10)

    International Nuclear Information System (INIS)

    Donde, M.M.; Srinivasa, K.; Raman, S.

    1989-04-01

    Insoluble deposits were observed to form during the operation of Heavy Water Plant at Talcher, based on ammonia-hydrogen exchange process with potassium amide as catalyst. Experiments were undertaken to investigate this phenomenon under controlled conditions in the laboratory employing high pressures and elevated temperatures. It was observed that deposit formation was very minimal in the autoclave and no visible deposit was left on the strainer-filter, in all the experiments. Deposit analysis showed the presence of potassium hydroxide monohydrate as major component and alpha-potassium hydroxide and potassium azide as minor components. It is suggested that the presence of hydroxide may be due to the reaction of amide with the residual moisture in the system during the experiment and any ingress of moisture while opening for collection of deposit. Azide formation is explained by following reactions occurring during the experiments. NH 3 +KNH 2 →NH 2 -NH 2 +KH; NH 2 -NH 2 +KNH 2 →KN 3 +3H 2 . (author). 1 fig

  1. Effect of dipotassium hydrogen phosphate on thermodynamic properties of glycine and L-alanine in aqueous solutions at different temperatures

    International Nuclear Information System (INIS)

    Kumar, Harsh; Kaur, Kirtanjot

    2012-01-01

    Highlights: ► Densities and speeds of sound of amino acids in DKHP. ► Apparent molar volume and apparent molar compressibilities were calculated. ► The partial molar expansibilities at infinite dilution φ E 0 were obtained. ► Hydration number n H was calculated. ► The results are discussed in terms of solute–solvent interactions. - Abstract: Densities, ρ, speed of sound, u for glycine, L-alanine have been measured in aqueous solutions of dipotassium hydrogen phosphate (DKHP) ranging from 0.2, 0.4, 0.6 and 0.8 mol·kg −1 at temperatures T = (288.15, 298.15, 308.15 and 318.15) K. The different parameters such as apparent molar volume, limiting apparent molar volume, transfer volume, partial molar expansibility have been derived from density data. Experimental speeds of sound data were used to estimate apparent molar adiabatic compressibility, limiting apparent molar adiabatic compressibility, transfer parameter and hydration number. These parameters have been discussed in the light of ion-ion and ion-solvent interactions.

  2. Physico Chemical Characteristic of Kappa Carrageenan Degraded Using Hydrogen Peroxide

    Directory of Open Access Journals (Sweden)

    Rizky Febriansyah Siregar

    2017-02-01

    Full Text Available AbstractKappa carrageenan is polysaccharide that widely used in food, pharmaceutical, cosmetic, textile and printing industries as coagulate agent, stabilizer and gelling agent. Hydrogen peroxide (H2O2 is strong oxidator to degrade polysaccharide. Hydrogen peroxide has some advantades such as cheap, easy to get and savety environment. Degradation method using hydrogen peroxide is a technology based on establishment radical hydoxile reactive that attack the glycosidic of polysaccharides as a result reducing in molecular weight of polysaccharide. The aims of this study were to analyze the effect of hydrogen peroxide concentration, temperature and degradation time to molecular weight of refined kappa carrageenan. Structural changes on kappa carrageenan degradation were characterized by viscometer, SEM and FTIR. Hydrogen peroxide concentration, temperature and degradation time were significantly reducing molecular weight and changes in the structural function of refined kappa carrageenan. The lowest molecular weight of refined kappa carrageenan degraded was obtained from the treatment 3% of hydrogen peroxide at temperature 80°C and degradation time for 4 hours.

  3. Cyber Attacks, Information Attacks, and Postmodern Warfare

    Directory of Open Access Journals (Sweden)

    Valuch Jozef

    2017-06-01

    Full Text Available The aim of this paper is to evaluate and differentiate between the phenomena of cyberwarfare and information warfare, as manifestations of what we perceive as postmodern warfare. We describe and analyse the current examples of the use the postmodern warfare and the reactions of states and international bodies to these phenomena. The subject matter of this paper is the relationship between new types of postmodern conflicts and the law of armed conflicts (law of war. Based on ICJ case law, it is clear that under current legal rules of international law of war, cyber attacks as well as information attacks (often performed in the cyberspace as well can only be perceived as “war” if executed in addition to classical kinetic warfare, which is often not the case. In most cases perceived “only” as a non-linear warfare (postmodern conflict, this practice nevertheless must be condemned as conduct contrary to the principles of international law and (possibly a crime under national laws, unless this type of conduct will be recognized by the international community as a “war” proper, in its new, postmodern sense.

  4. Diffusion of hydrogen in yttrium

    International Nuclear Information System (INIS)

    Vorobyov, V.V.; Ryabchikov, L.N.

    1966-01-01

    In this work the diffusion coefficients of hydrogen in yttrium were determined from the rate at which the hydrogen was released from yttrium samples under a vacuum at temperatures of 450 to 850 0 C and from the quantity of hydrogen retained by yttrium at hydrogen pressures below 5 x 10 - 4 mm Hg in the same temperature range

  5. Facile fabrication of high-performance InGaZnO thin film transistor using hydrogen ion irradiation at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byung Du [School of Electrical and Electronic Engineering, 50, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Jin-Seong [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, K. B., E-mail: kbchung@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2014-10-20

    Device performance of InGaZnO (IGZO) thin film transistors (TFTs) are investigated as a function of hydrogen ion irradiation dose at room temperature. Field effect mobility is enhanced, and subthreshold gate swing is improved with the increase of hydrogen ion irradiation dose, and there is no thermal annealing. The electrical device performance is correlated with the electronic structure of IGZO films, such as chemical bonding states, features of the conduction band, and band edge states below the conduction band. The decrease of oxygen deficient bonding and the changes in electronic structure of the conduction band leads to the improvement of device performance in IGZO TFT with an increase of the hydrogen ion irradiation dose.

  6. The effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity

    Science.gov (United States)

    Owji, Erfan; Keshavarz, Alireza; Mokhtari, Hosein

    2016-10-01

    In this paper, the effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity are investigated. For this purpose, the effects of temperature, pressure and quantum dot size on the band gap energy, effective mass, and dielectric constant are studied. The eigenenergies and eigenstates for valence and conduction band are calculated by using Runge-Kutta numerical method. Results show that changes in the temperature, pressure and size lead to the alteration of the band gap energy and effective mass. Also, increasing the temperature redshifts the optical gain peak and at special temperature ranges lead to increasing or decreasing of it. Further, by reducing the size, temperature-dependent of optical gain is decreased. Additionally, enhancing of the hydrostatic pressure blueshifts the peak of optical gain, and its behavior as a function of pressure which depends on the size. Finally, increasing the radius rises the redshifts of the peak of optical gain.

  7. On-line hydrogen-isotope measurements of organic samples using elemental chromium: An extension for high temperature elemental-analyzer techniques

    Science.gov (United States)

    Gehre, Matthias; Renpenning, Julian; Gilevska, Tetyana; Qi, Haiping; Coplen, Tyler B.; Meijer, Harro A.J.; Brand, Willi A.; Schimmelmann, Arndt

    2015-01-01

    The high temperature conversion (HTC) technique using an elemental analyzer with a glassy carbon tube and filling (temperature conversion/elemental analysis, TC/EA) is a widely used method for hydrogen isotopic analysis of water and many solid and liquid organic samples with analysis by isotope-ratio mass spectrometry (IRMS). However, the TC/EA IRMS method may produce inaccurate δ2H results, with values deviating by more than 20 mUr (milliurey = 0.001 = 1‰) from the true value for some materials. We show that a single-oven, chromium-filled elemental analyzer coupled to an IRMS substantially improves the measurement quality and reliability for hydrogen isotopic compositions of organic substances (Cr-EA method). Hot chromium maximizes the yield of molecular hydrogen in a helium carrier gas by irreversibly and quantitatively scavenging all reactive elements except hydrogen. In contrast, under TC/EA conditions, heteroelements like nitrogen or chlorine (and other halogens) can form hydrogen cyanide (HCN) or hydrogen chloride (HCl) and this can cause isotopic fractionation. The Cr-EA technique thus expands the analytical possibilities for on-line hydrogen-isotope measurements of organic samples significantly. This method yielded reproducibility values (1-sigma) for δ2H measurements on water and caffeine samples of better than 1.0 and 0.5 mUr, respectively. To overcome handling problems with water as the principal calibration anchor for hydrogen isotopic measurements, we have employed an effective and simple strategy using reference waters or other liquids sealed in silver-tube segments. These crimped silver tubes can be employed in both the Cr-EA and TC/EA techniques. They simplify considerably the normalization of hydrogen-isotope measurement data to the VSMOW-SLAP (Vienna Standard Mean Ocean Water-Standard Light Antarctic Precipitation) scale, and their use improves accuracy of the data by eliminating evaporative loss and associated isotopic fractionation while

  8. On-line hydrogen-isotope measurements of organic samples using elemental chromium: an extension for high temperature elemental-analyzer techniques.

    Science.gov (United States)

    Gehre, Matthias; Renpenning, Julian; Gilevska, Tetyana; Qi, Haiping; Coplen, Tyler B; Meijer, Harro A J; Brand, Willi A; Schimmelmann, Arndt

    2015-01-01

    The high temperature conversion (HTC) technique using an elemental analyzer with a glassy carbon tube and filling (temperature conversion/elemental analysis, TC/EA) is a widely used method for hydrogen isotopic analysis of water and many solid and liquid organic samples with analysis by isotope-ratio mass spectrometry (IRMS). However, the TC/EA IRMS method may produce inaccurate δ(2)H results, with values deviating by more than 20 mUr (milliurey = 0.001 = 1‰) from the true value for some materials. We show that a single-oven, chromium-filled elemental analyzer coupled to an IRMS substantially improves the measurement quality and reliability for hydrogen isotopic compositions of organic substances (Cr-EA method). Hot chromium maximizes the yield of molecular hydrogen in a helium carrier gas by irreversibly and quantitatively scavenging all reactive elements except hydrogen. In contrast, under TC/EA conditions, heteroelements like nitrogen or chlorine (and other halogens) can form hydrogen cyanide (HCN) or hydrogen chloride (HCl) and this can cause isotopic fractionation. The Cr-EA technique thus expands the analytical possibilities for on-line hydrogen-isotope measurements of organic samples significantly. This method yielded reproducibility values (1-sigma) for δ(2)H measurements on water and caffeine samples of better than 1.0 and 0.5 mUr, respectively. To overcome handling problems with water as the principal calibration anchor for hydrogen isotopic measurements, we have employed an effective and simple strategy using reference waters or other liquids sealed in silver-tube segments. These crimped silver tubes can be employed in both the Cr-EA and TC/EA techniques. They simplify considerably the normalization of hydrogen-isotope measurement data to the VSMOW-SLAP (Vienna Standard Mean Ocean Water-Standard Light Antarctic Precipitation) scale, and their use improves accuracy of the data by eliminating evaporative loss and associated isotopic fractionation while

  9. Seven Deadliest Wireless Technologies Attacks

    CERN Document Server

    Haines, Brad

    2010-01-01

    How can an information security professional keep up with all of the hacks, attacks, and exploits? One way to find out what the worst of the worst are is to read the seven books in our Seven Deadliest Attacks Series. Not only do we let you in on the anatomy of these attacks but we also tell you how to get rid of them and how to defend against them in the future. Countermeasures are detailed so that you can fight against similar attacks as they evolve. Attacks featured in this book include:Bluetooth AttacksCredit Card, Access Card, and Passport AttacksBad Encryption

  10. Ambient-temperature fabrication of microporous carbon terminated with graphene walls by sputtering process for hydrogen storage applications

    International Nuclear Information System (INIS)

    Banerjee, Arghya Narayan; Joo, Sang Woo; Min, Bong-Ki

    2013-01-01

    A very thin amorphous carbon film (10–30 nm), has been bombarded with sputtered Cr nanoparticles, resulting in inelastic collision between the nanoparticles and the nuclei of the C-atoms causing atom displacement and re-arrangement into graphene layers. The process occurs at ambient temperature. Fabrication of graphitic microporous carbon terminated with few-to-multilayer graphene walls has been verified by Raman spectroscopy and scanning transmission electron microscopy. High resolution transmission electron micrographs reveal that the formation of graphene layers is highly sensitive to the sputtering parameters. With a gradual increase in the sputtering voltage/current density/time from 3.5 kV/40 mA–cm −2 /1.0 min to 5.0 kV/70 mA–cm −2 /3.0 min the graphitic domains are found to transform from semi-graphitized layers to well-defined, highly ordered, larger-area graphene walls within the microporous network. The mechanism of this graphitic microporous carbon formation is assumed to be due to two simultaneous processes: in one hand, the sputtering plasma, containing energetic ions and sub-atomic particles, act as dry-etchant to activate the a:C film to transform it into microporous carbon, whereas on the other hand, the charged metal nanoparticle/ion bombardment under sputtering resulted in the inelastic collision between the nanoparticles/ions and the nuclei of the C atoms followed by atom displacement (and displacement cascade) and re-arrangement into ordered structure to form graphitic domains within the microporous carbon network. H 2 storage experiment of the samples depicts excellent hydrogen storage properties. This simple, cost-effective, complementary-metal-oxide-semiconductor-compatible, single-step process of metal-graphene hybrid nanomaterial formation may find interesting applications in the field of optoelectronics and biotechnology. Additionally, this method can be adopted easily for the incorporation of transition metals into graphene and

  11. Symmetric and asymmetric zeolitic imidazolate frameworks (ZIFs)/polybenzimidazole (PBI) nanocomposite membranes for hydrogen purification at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tingxu; Shi, Gui Min; Chung, Tai-Shung [Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore (Singapore)

    2012-11-15

    High-performance zeolitic imidazolate frameworks (ZIFs)/polybenzimidazole (PBI) nanocomposites are molecularly designed for hydrogen separation at high temperatures, and demonstrate it in a useful configuration as dual-layer hollow fibers for the first time. By incorporating as-synthesized nanoporous ZIF-8 nanoparticles into the high thermal stability but extremely low permeability polybenzimidazole (PBI), the resultant mixed matrix membranes show an impressive enhancement in H{sub 2} permeability as high as a hundred times without any significant deduction in H{sub 2}/CO{sub 2} selectivity. The 30/70 ZIF-8/PBI dense membrane has a H{sub 2} permeability of 105.4 Barrer and a H{sub 2}/CO{sub 2} selectivity of 12.3. This performance is far superior to ZIF-7/PBI membranes and is the best ever reported data for H{sub 2}-selective polymeric materials in the literature. Meanwhile, defect-free ZIF-8-PBI/Matrimid dual-layer hollow fibers are successfully fabricated, without post-annealing and coating, by optimizing ZIF-8 nanoparticle loadings, spinning conditions, and solvent-exchange procedures. Two types of hollow fibers targeted at either high H{sub 2}/CO{sub 2} selectivity or high H{sub 2} permeance are developed: i) PZM10-I B fibers with a medium H{sub 2} permeance of 64.5 GPU (2.16 x 10{sup -8} mol m{sup -2} s{sup -1} Pa{sup -1}) at 180 C and a high H{sub 2}/CO{sub 2} selectivity of 12.3, and, ii) PZM33-I B fibers with a high H{sub 2} permeance of 202 GPU (6.77 x 10{sup -8} mol m{sup -2} s{sup -1} Pa{sup -1}) at 180 C and a medium H{sub 2}/CO{sub 2} selectivity of 7.7. This work not only molecularly designs novel nanocomposite materials for harsh industrial applications, such as syngas and hydrogen production, but also, for the first time, synergistically combines the strengths of both ZIF-8 and PBI for energy-related applications. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. The political attack ad

    Directory of Open Access Journals (Sweden)

    Palma Peña-Jiménez, Ph.D.

    2011-01-01

    Full Text Available During election campaigns the political spot has a clear objective: to win votes. This message is communicated to the electorate through television and Internet, and usually presents a negative approach, which includes a direct critical message against the opponent, rather than an exposition of proposals. This article is focused on the analysis of the campaign attack video ad purposely created to encourage the disapproval of the political opponent among voters. These ads focus on discrediting the opponent, many times, through the transmission of ad hominem messages, instead of disseminating the potential of the political party and the virtues and manifesto of its candidate. The article reviews the development of the attack ad since its first appearance, which in Spain dates back to 1996, when the famous Doberman ad was broadcast, and examines the most memorable campaign attack ads.

  13. A fatal elephant attack.

    Science.gov (United States)

    Hejna, Petr; Zátopková, Lenka; Safr, Miroslav

    2012-01-01

    A rare case of an elephant attack is presented. A 44-year-old man working as an elephant keeper was attacked by a cow elephant when he tripped over a foot chain while the animal was being medically treated. The man fell down and was consequently repeatedly attacked with elephant tusks. The man sustained multiple stab injuries to both groin regions, a penetrating injury to the abdominal wall with traumatic prolapse of the loops of the small bowel, multiple defects of the mesentery, and incomplete laceration of the abdominal aorta with massive bleeding into the abdominal cavity. In addition to the penetrating injuries, the man sustained multiple rib fractures with contusion of both lungs and laceration of the right lobe of the liver, and comminuted fractures of the pelvic arch and left femoral body. The man died shortly after he had been received at the hospital. The cause of death was attributed to traumatic shock. © 2011 American Academy of Forensic Sciences.

  14. Simultaneous Production of Hydrogen and Methane from Sugar Beet Molasses in a Two Phase Anaerobic Digestion System in UASB Reactors under Thermophilic Temperature (55 Deg C)

    Energy Technology Data Exchange (ETDEWEB)

    Kongjan, P.; Villafa, S.; Beltran, P.; Min, B.; Angelidaki, I. (Dept. of Environmental Engineering, Technical Univ. of Denmark, DK-2800, Lyngby (Denmark)). e-mail: pak@env.dtu.dk

    2008-10-15

    Simultaneous production of hydrogen and methane in two sequential stages of acidogenic and methanogenic step was investigated in two serial operated up-flow anaerobic sludge bed (UASB) reactors at thermophilic temperature (55 deg C). Hydrogen production from molasses was carried out in the first reactor at the hydraulic retention time (HRT) of 1 day. Molasses were converted into hydrogen with the yield of 1.3 mole-H{sub 2}/mole-hexose{sub added} or 82.7 ml- H{sub 2}/g-VS{sub added} of molasses, and the hydrogen productivity was 2696 ml-H{sub 2}/dxl{sub reactor}. The effluent (mainly butyrate, acetate and lactate) after the acidogenic process was subsequently fed to the second reactor for methane production at HRT of 3 days. Methane production yield of 255 ml-H{sub 2}/g-VS{sub added} of influent or 130.1 ml-H{sub 2}/g-VS{sub added} of molasses and methane production rate of 1056 ml/dxl{sub reactor} were obtained. Significant decrease of volatile fatty acids (VFAs) was also observed in the effluent of the second reactor. A two phase anaerobic digestion was successfully demonstrated for molasses as a potential substrate to produce hydrogen and subsequent methane in the UASB reactors

  15. Optimization of on-line hydrogen stable isotope ratio measurements of halogen- and sulfur-bearing organic compounds using elemental analyzer–chromium/high-temperature conversion isotope ratio mass spectrometry (EA-Cr/HTC-IRMS)

    Science.gov (United States)

    Gehre, Matthias; Renpenning, Julian; Geilmann, Heike; Qi, Haiping; Coplen, Tyler B.; Kümmel, Steffen; Ivdra, Natalija; Brand, Willi A.; Schimmelmann, Arndt

    2017-01-01

    Rationale: Accurate hydrogen isotopic analysis of halogen- and sulfur-bearing organics has not been possible with traditional high-temperature conversion (HTC) because the formation of hydrogen-bearing reaction products other than molecular hydrogen (H2) is responsible for non-quantitative H2 yields and possible hydrogen isotopic fractionation. Our previously introduced, new chromium-based EA-Cr/HTC-IRMS (Elemental Analyzer–Chromium/High-Temperature Conversion Isotope Ratio Mass Spectrometry) technique focused primarily on nitrogen-bearing compounds. Several technical and analytical issues concerning halogen- and sulfur-bearing samples, however, remained unresolved and required further refinement of the reactor systems.

  16. Operational performance of the development of a 15 kW parabolic trough mid-temperature solar receiver/reactor for hydrogen production

    International Nuclear Information System (INIS)

    Hong, Hui; Liu, Qibin; Jin, Hongguang

    2012-01-01

    Highlights: ► A 15 kW solar chemical receiver/reactor for hydrogen production was developed. ► The solar thermochemical efficiency of the receiver/reactor was in the range of 20–28%. ► Hydrogen production exceeding 80% was achieved. ► The research results extend the application of mid-temperature solar thermal energy. -- Abstract: In this paper, we report the operational performance and energy conversion efficiency of a developed 15 kW solar chemical receiver/reactor for hydrogen production. A concentrated solar heat of around 200–300 °C was utilized to provide process heat to drive methanol steam reforming. A modified 15 kW direct-irradiation solar reactor coupled with a linear receiver positioned along the focal line of a one-axis parabolic trough concentrator was used. The experiments were conducted from 200 to 300 °C under a mean solar flux of 300–800 W/m 2 and a reactant feeding rate of 6 kg/h. Reactants were continuously fed, and the attained conversion rate of methanol was more than 70% at 700 W/m 2 . The typical solar thermochemical efficiency of solar thermal energy converted into chemical energy was in the 20–28% range. The overall energy efficiency of input solar power conversion into chemical energy reached up to 17% and may be further increased by improving solar field efficiency. Hydrogen production exceeding 80% was achieved. In addition, preliminary economic evaluation was performed, and methods for further improvement were proposed. This paper proves that solar hydrogen production is feasible by combining solar thermal energy with alternative fuel at around 200–300 °C, which is much lower than the temperature of other solar thermochemical processes. This may offer an economic approach to solar fuel production and extend the application of mid-temperature solar thermal energy.

  17. Low-cost fabrication of highly sensitive room temperature hydrogen sensor based on ordered mesoporous Co-doped TiO2 structure

    Science.gov (United States)

    Li, Zhong; Haidry, Azhar Ali; Wang, Tao; Yao, Zheng Jun

    2017-07-01

    The development of cost-effective gas sensors with improved sensing properties and minimum power consumption for room temperature hydrogen leakage monitoring is in increasing demand. In this context, this report focus on the facile fabrication of ordered mesoporous TiO2 via evaporation-induced self-assembly route. With the controlled doping threshold (3%Co-TiO2), the output resistance change to 1000 ppm H2 is ˜4.1 × 103 with the response time of 66 s. The sensor response exhibits power law dependence with an increase in the hydrogen concentration, where the power law coefficient was found not only specific to the kind of target gas but also related to temperature. Further, the effect of structure integrity with doping level and humidity on sensing characteristics is interpreted in terms of variation in surface potential eVS and depletion region w caused by the adsorption of molecular oxygen O2-.

  18. Attacker Model Lab

    OpenAIRE

    2006-01-01

    tut quiz present Tutorial Quiz Presentation Interactive Media Element This interactive tutorial the two sub-classes of computer attackers: amateurs and professionals. It provides valuable insight into the nature of necessary protection measure for information assets. CS3600 Information Assurance: Introduction to Computer Security Course

  19. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... major stroke. It's important to call 9-1-1 immediately for any stroke symptoms. Popular Topics TIA Cardiac Catheter Cholesterol Heart Attack Stent © 2018, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. The content in this ...

  20. Temporal Cyber Attack Detection.

    Energy Technology Data Exchange (ETDEWEB)

    Ingram, Joey Burton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Draelos, Timothy J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Galiardi, Meghan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Doak, Justin E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-11-01

    Rigorous characterization of the performance and generalization ability of cyber defense systems is extremely difficult, making it hard to gauge uncertainty, and thus, confidence. This difficulty largely stems from a lack of labeled attack data that fully explores the potential adversarial space. Currently, performance of cyber defense systems is typically evaluated in a qualitative manner by manually inspecting the results of the system on live data and adjusting as needed. Additionally, machine learning has shown promise in deriving models that automatically learn indicators of compromise that are more robust than analyst-derived detectors. However, to generate these models, most algorithms require large amounts of labeled data (i.e., examples of attacks). Algorithms that do not require annotated data to derive models are similarly at a disadvantage, because labeled data is still necessary when evaluating performance. In this work, we explore the use of temporal generative models to learn cyber attack graph representations and automatically generate data for experimentation and evaluation. Training and evaluating cyber systems and machine learning models requires significant, annotated data, which is typically collected and labeled by hand for one-off experiments. Automatically generating such data helps derive/evaluate detection models and ensures reproducibility of results. Experimentally, we demonstrate the efficacy of generative sequence analysis techniques on learning the structure of attack graphs, based on a realistic example. These derived models can then be used to generate more data. Additionally, we provide a roadmap for future research efforts in this area.

  1. Questioning hydrogen

    International Nuclear Information System (INIS)

    Hammerschlag, Roel; Mazza, Patrick

    2005-01-01

    As an energy carrier, hydrogen is to be compared to electricity, the only widespread and viable alternative. When hydrogen is used to transmit renewable electricity, only 51% can reach the end user due to losses in electrolysis, hydrogen compression, and the fuel cell. In contrast, conventional electric storage technologies allow between 75% and 85% of the original electricity to be delivered. Even when hydrogen is extracted from gasified coal (with carbon sequestration) or from water cracked in high-temperature nuclear reactors, more of the primary energy reaches the end user if a conventional electric process is used instead. Hydrogen performs no better in mobile applications, where electric vehicles that are far closer to commercialization exceed fuel cell vehicles in efficiency, cost and performance. New, carbon-neutral energy can prevent twice the quantity of GHG's by displacing fossil electricity than it can by powering fuel cell vehicles. The same is true for new, natural gas energy. New energy resources should be used to displace high-GHG electric generation, not to manufacture hydrogen

  2. Anaerobic fermentation combined with low-temperature thermal pretreatment for phosphorus-accumulating granular sludge: Release of carbon source and phosphorus as well as hydrogen production potential.

    Science.gov (United States)

    Zou, Jinte; Li, Yongmei

    2016-10-01

    Releases of organic compounds and phosphorus from phosphorus-accumulating granular sludge (PGS) and phosphorus-accumulating flocculent sludge (PFS) during low-temperature thermal pretreatment and anaerobic fermentation were investigated. Meanwhile, biogas production potential and microbial community structures were explored. The results indicate that much more soluble chemical oxygen demand (SCOD) and phosphorus were released from PGS than from PFS via low-temperature thermal pretreatment because of the higher extracellular polymeric substances (EPS) content in PGS and higher ratio of phosphorus reserved in EPS. Furthermore, PGS contains more anaerobes and dead cells, resulting in much higher SCOD and volatile fatty acids release from PGS than those from PFS during fermentation. PGS fermentation facilitated the n-butyric acid production, and PGS exhibited the hydrogen production potential during fermentation due to the presence of hydrogen-producing bacteria. Therefore, anaerobic fermentation combined with low-temperature thermal pretreatment can facilitate the recovery of carbon and phosphorus as well as producing hydrogen from PGS. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Blocking of Brute Force Attack

    OpenAIRE

    M.Venkata Krishna Reddy

    2012-01-01

    A common threat Web developers face is a password-guessing attack known as a brute-force attack. A brute-force attack is an attempt to discover a password by systematically trying every possible combination of letters, numbers, and symbols until you discover the one correct combination that works. If your Web site requires user authentication, you are a good target for a brute-force attack. An attacker can always discover a password through a brute-force attack, but the downside is that it co...

  4. Bluetooth security attacks comparative analysis, attacks, and countermeasures

    CERN Document Server

    Haataja, Keijo; Pasanen, Sanna; Toivanen, Pekka

    2013-01-01

    This overview of Bluetooth security examines network vulnerabilities and offers a comparative analysis of recent security attacks. It also examines related countermeasures and proposes a novel attack that works against all existing Bluetooth versions.

  5. Temperature-dependent kinetics of charge transfer, hydrogen-atom transfer, and hydrogen-atom expulsion in the reaction of CO+ with CH4 and CD4.

    Science.gov (United States)

    Melko, Joshua J; Ard, Shaun G; Johnson, Ryan S; Shuman, Nicholas S; Guo, Hua; Viggiano, Albert A

    2014-09-18

    We have determined the rate constants and branching ratios for the reactions of CO(+) with CH4 and CD4 in a variable-temperature selected ion flow tube. We find that the rate constants are collisional for all temperatures measured (193-700 K for CH4 and 193-500 K for CD4). For the CH4 reaction, three product channels are identified, which include charge transfer (CH4(+) + CO), H-atom transfer (HCO(+) + CH3), and H-atom expulsion (CH3CO(+) + H). H-atom transfer is slightly preferred to charge transfer at low temperature, with the charge-transfer product increasing in contribution as the temperature is increased (H-atom expulsion is a minor product for all temperatures). Analogous products are identified for the CD4 reaction. Density functional calculations on the CO(+) + CH4 reaction were also conducted, revealing that the relative temperature dependences of the charge-transfer and H-atom transfer pathways are consistent with an initial charge transfer followed by proton transfer.

  6. Moderate Temperature Dense Phase Hydrogen Storage Materials within the US Department of Energy (DOE H2 Storage Program: Trends toward Future Development

    Directory of Open Access Journals (Sweden)

    Scott McWhorter

    2012-05-01

    Full Text Available Hydrogen has many positive attributes that make it a viable choice to augment the current portfolio of combustion-based fuels, especially when considering reducing pollution and greenhouse gas (GHG emissions. However, conventional methods of storing H2 via high-pressure or liquid H2 do not provide long-term economic solutions for many applications, especially emerging applications such as man-portable or stationary power. Hydrogen storage in materials has the potential to meet the performance and cost demands, however, further developments are needed to address the thermodynamics and kinetics of H2 uptake and release. Therefore, the US Department of Energy (DOE initiated three Centers of Excellence focused on developing H2 storage materials that could meet the stringent performance requirements for on-board vehicular applications. In this review, we have summarized the developments that occurred as a result of the efforts of the Metal Hydride and Chemical Hydrogen Storage Centers of Excellence on materials that bind hydrogen through ionic and covalent linkages and thus could provide moderate temperature, dense phase H2 storage options for a wide range of emerging Proton Exchange Membrane Fuel Cell (PEM FC applications.

  7. 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...

  8. Automated Discovery of Mimicry Attacks

    National Research Council Canada - National Science Library

    Giffin, Jonathon T; Jha, Somesh; Miller, Barton P

    2006-01-01

    .... These systems are useful only if they detect actual attacks. Previous research developed manually-constructed mimicry and evasion attacks that avoided detection by hiding a malicious series of system calls within a valid sequence allowed by the model...

  9. Heart Attack Symptoms in Women

    Science.gov (United States)

    ... fat, cholesterol and other substances (plaque). Watch an animation of a heart attack . Many women think the ... Support Network Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  10. Seven harmonic susceptibility in oxygen and hydrogen loading of sintered YBCO by μs pulsed electrolysis in an aqueous solution at room temperature

    International Nuclear Information System (INIS)

    Tripodi, P.; Di Gioacchino, D.; Celani, F.

    1996-09-01

    The complex AC susceptibility of high T c superconducting materials has been described in terms of the first seven harmonic component of Fourier series. Has been measured the χ' n and χ n (n=1,7) of sintered YBa 2 Cu 3 O 7-x (YBCO) bulk oxygen and hydrogen loaded samples versus amplitude and frequency of AC magnetic field at fixed temperature. The sample have been loaded by μs current pulses electrolysis in an aqueous solution (0.3N LiOH+H 2 O) at room temperature. In addition to the simplicity of the experimental setup, this procedure allows to obtain extremely high equivalent hydrogen/oxygen gas pressure on the surface of the electrodes. The YBCO electrode is polarized by short pulse width (0.5-10 μs) and high power (120 W) peaks with a variable repetition rate (0.1-10000 Hz). The pulses are obtained by an home.made pulse generator. The difference in the behavior of the susceptibilities harmonic component between the deficiency and oxygen or hydrogen loaded samples give us the possibility to connect the susceptibilities with variations of the flux pinning in respect to normal losses in the superconducting materials. The loading can be a good probe to have information on the mechanism of the processes that sustain the critical current density Jc in this situation these affects appear strongly dependent on the loading conditions. By comparison of this measurements has been observed drastic change in behavior of susceptibility

  11. On the room-temperature phase diagram of high pressure hydrogen: An ab initio molecular dynamics perspective and a diffusion Monte Carlo study

    International Nuclear Information System (INIS)

    Chen, Ji; Ren, Xinguo; Li, Xin-Zheng; Alfè, Dario; Wang, Enge

    2014-01-01

    The finite-temperature phase diagram of hydrogen in the region of phase IV and its neighborhood was studied using the ab initio molecular dynamics (MD) and the ab initio path-integral molecular dynamics (PIMD). The electronic structures were analyzed using the density-functional theory (DFT), the random-phase approximation, and the diffusion Monte Carlo (DMC) methods. Taking the state-of-the-art DMC results as benchmark, comparisons of the energy differences between structures generated from the MD and PIMD simulations, with molecular and dissociated hydrogens, respectively, in the weak molecular layers of phase IV, indicate that standard functionals in DFT tend to underestimate the dissociation barrier of the weak molecular layers in this mixed phase. Because of this underestimation, inclusion of the quantum nuclear effects (QNEs) in PIMD using electronic structures generated with these functionals leads to artificially dissociated hydrogen layers in phase IV and an error compensation between the neglect of QNEs and the deficiencies of these functionals in standard ab initio MD simulations exists. This analysis partly rationalizes why earlier ab initio MD simulations complement so well the experimental observations. The temperature and pressure dependencies for the stability of phase IV were also studied in the end and compared with earlier results

  12. Attack Trees with Sequential Conjunction

    NARCIS (Netherlands)

    Jhawar, Ravi; Kordy, Barbara; Mauw, Sjouke; Radomirović, Sasa; Trujillo-Rasua, Rolando

    2015-01-01

    We provide the first formal foundation of SAND attack trees which are a popular extension of the well-known attack trees. The SAND at- tack tree formalism increases the expressivity of attack trees by intro- ducing the sequential conjunctive operator SAND. This operator enables the modeling of

  13. The reaction of uranium with moist hydrogen

    International Nuclear Information System (INIS)

    Pearce, R.J.; Kay, P.

    1987-10-01

    The reaction of uranium in moist hydrogen at a total pressure of 101 kPa over the temperature range 105 0 -200 0 C and water vapour pressures in the range 5-100 kPa has been examined in a limited thermogravimetric study. It has been shown that initially there is a period during which only linear kinetics are observed with a rate similar to that exhibited in similarly moist argon, i.e. hydrogen has no apparent effect on the reaction. At water vapour pressures of and above 49 kPa, corresponding to hydrogen:water vapour pressure ratios in the range 1:1 to 1:100, over the exposure times studied (not > 20h) only such linear kinetics are observed. Below this water vapour pressure and after an initial period of linear kinetics a continuously increasing reaction rate was observed in some instances resulting from rapid attach on localised areas. The localised reaction rates were approximately 2-3 orders of magnitude faster than the original linear reaction kinetics and the interaction rates in either moist argon or moist air. Comparison with a single experiment carried out at 150 0 C indicated that breakaway rates were approaching that in dry hydrogen. During breakaway attack there was a significant increase in the relative amounts of uranium hydride formed. The duration of the linear kinetics phase was extended by pre-oxidation of the uranium surface, decreasing temperature at a constant water vapour pressure, or increasing water vapour pressure (or water vapour: hydrogen pressure ratio) at a constant temperature. (author)

  14. Advanced CSiC composites for high-temperature nuclear heat transport with helium, molten salts, and sulphur-iodine thermochemical hydrogen process fluids

    International Nuclear Information System (INIS)

    Peterson, P.F.; Forsberg, Ch.W.; Pickard, P.S.

    2004-01-01

    This paper discusses the use of liquid-silicon-impregnated (LSI) carbon-carbon composites for the development of compact and inexpensive heat exchangers, piping, vessels and pumps capable of operating in the temperature range of 800 to 1 100 deg C with high-pressure helium, molten fluoride salts, and process fluids for sulfur-iodine thermochemical hydrogen production. LSI composites have several potentially attractive features, including ability to maintain nearly full mechanical strength to temperatures approaching 1 400 deg C, inexpensive and commercially available fabrication materials, and the capability for simple forming, machining and joining of carbon-carbon performs, which permits the fabrication of highly complex component geometries. In the near term, these materials may prove to be attractive for use with a molten-salt intermediate loop for the demonstration of hydrogen production with a gas-cooled high temperature reactor. In the longer term, these materials could be attractive for use with the molten-salt cooled advanced high temperature reactor, molten salt reactors, and fusion power plants. (author)

  15. Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports.

    Science.gov (United States)

    Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H

    2013-05-30

    Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/Al S.G. ) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/Al S.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/Al S.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

  16. Research and development on is process components for hydrogen production. (2) Corrosion resistance of glass lining in high temperature sulfuric acid

    International Nuclear Information System (INIS)

    Tanaka, Nobuyuki; Iwatsuki, Jin; Kubo, Shinji; Terada, Atsuhiko; Onuki, Kaoru

    2009-01-01

    Japan Atomic Energy Agency has been conducting a research and development on hydrogen production system using High Temperature Gas-Cooled Reactor. As a part of this effort, thermochemical water-splitting cycle featuring iodine- and sulfur-compounds (IS process) is under development considering its potential of large-scale economical hydrogen production. The IS process constitutes very severe environments on the materials of construction because of the corrosive nature of process chemicals, especially of the high temperature acidic solution of sulfuric acid and hydriodic acid dissolving iodine. Therefore, selection of the corrosion-resistant materials and development of the components has been studied as a crucial subject of the process development. This paper discusses corrosion resistance of commercially available glass-lining material in high temperature sulfuric acid. Corrosion resistance of a soda glass used for glass-lining was examined by immersion tests. The experiments were performed in 47-90wt% sulfuric acids at temperatures of up to 400degC and for the maximum immersion time of 100 hours using an autoclave designed for the concerned tests. In every condition tested, no indication of localized corrosion such as defect formation or pitting corrosion was observed. Also, the corrosion rates decreased with the progress of immersion, and were low enough (≅0.1 mm/year) after 60-90 hours of immersion probably due to formation of a silica rich surface. (author)

  17. Experimental investigation of solid hydrogen pellet ablation in high-temperature plasmas using holographic interferometry and other diagnostics

    International Nuclear Information System (INIS)

    Thomas, C.E. Jr.

    1981-03-01

    The technology currently most favored for the refueling of fusion reactors is the high-velocity injection of solid hydrogen pellets. Design details are presented for a holographic interferometer/shadowgraph used to study the microscopic characteristics of a solid hydrogen pellet ablating in an approx. 1-keV plasma. Experimental data are presented for two sets of experiments in which the interferometer/shadowgraph was used to study approx. 1-mm-diam solid hydrogen pellets injected into the Impurity Study Experiment (ISX-B) tokamak at Oak Ridge National Laboratory (ORNL) at velocities of 1000 m/s. In addition to the use of the holographic interferometer, the pellet ablation process is diagnosed by studying the emission of Balmer-alpha photons and by using the available tokamak diagnostics

  18. Laser fluorescence spectroscopy by two-photon excitation for detection of hydrogen atoms in a periphery region of high temperature plasmas

    International Nuclear Information System (INIS)

    Kim, Hee-Je; Kajiwara, Toshinori; Motoyama, Sumio; Muraoka, Katsunori; Akazaki, Masanori; Okada, Tatsuo; Maeda, Mitsuo

    1989-01-01

    For measurements of atomic hydrogen density in the periphery region of high temperature plasmas, laser fluorescence spectroscopy (LFS) by two-photon excitation (1s-3s, 3d) was developed. Based upon the theoretical estimates for laser source requirements, which indicated the laser energy and spectral width to be more than 10 mJ (assuming the pulse duration of 10 ns) and several tens of picometers around the wavelength of 205.1 nm, respectively, the first Stokes generation in deuterium gas of ArF laser output was adopted and shown to have the necessary performance. Through the LFS experiment employing the laser source, the minimum detectable limit of atomic hydrogen, normalized by a laser power and an observing solid angle, was demonstrated to be 1 x 10 14 [m -3 · MW · sr], which is usually sufficient for the above purpose, and the accuracy of the density determination was shown to be within a factor 2. (author)

  19. Hydrogen absorption/desorption characteristics of room temperature ZrMn2-xNix system (x = 1.25-1.50)

    International Nuclear Information System (INIS)

    Kumar, Vinod; Pukazhselvan, D.; Singh, S.K.; Tyagi, A.K.

    2014-01-01

    The present communication deals with the hydrogen storage characteristics of C15 laves phase ZrMn 2-x Ni x system tailored within the x values of 1.25 to 1.50. Drastic variations in thermodynamics of the hydride phase is observed for any little changes of concentration x within this narrow range. The most promising room temperature hydrogen storage materials are found to be formed within the range of 1.35 to 1.45 where ∼ 2.5 to 2.9 H/F.U. can be reversibly stored under the ideal operating conditions. The heat of the reaction is found to be ∼ 17 kJ/mol, which means these are promising candidates for stationary and short range mobile applications. The phase structural features and the thermodynamic aspects of all the materials are discussed in detail. (author)

  20. The role of radiation damage on retention and temperature intervals of helium and hydrogen