High temperature regenerable hydrogen sulfide removal agents

DOEpatents

Copeland, Robert J.

1993-01-01

A system for high temperature desulfurization of coal-derived gases using regenerable sorbents. One sorbent is stannic oxide (tin oxide, SnO.sub.2), the other sorbent is a metal oxide or mixed metal oxide such as zinc ferrite (ZnFe.sub.2 O.sub.4). Certain otherwise undesirable by-products, including hydrogen sulfide (H.sub.2 S) and sulfur dioxide (SO.sub.2) are reused by the system, and elemental sulfur is produced in the regeneration reaction. A system for refabricating the sorbent pellets is also described.

Conceptual Design of Low-Temperature Hydrogen Production and High-Efficiency Nuclear Reactor Technology

NASA Astrophysics Data System (ADS)

Fukushima, Kimichika; Ogawa, Takashi

Hydrogen, a potential alternative energy source, is produced commercially by methane (or LPG) steam reforming, a process that requires high temperatures, which are produced by burning fossil fuels. However, as this process generates large amounts of CO2, replacement of the combustion heat source with a nuclear heat source for 773-1173K processes has been proposed in order to eliminate these CO2 emissions. In this paper, a novel method of nuclear hydrogen production by reforming dimethyl ether (DME) with steam at about 573K is proposed. From a thermodynamic equilibrium analysis of DME steam reforming, the authors identified conditions that provide high hydrogen production fraction at low pressure and temperatures of about 523-573K. By setting this low-temperature hydrogen production process upstream from a turbine and nuclear reactor at about 573K, the total energy utilization efficiency according to equilibrium mass and heat balance analysis is about 50%, and it is 75%for a fast breeder reactor (FBR), where turbine is upstream of the reformer.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Way, J. Douglas; Wolden, Colin A.

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 Mo 2C 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 Momore » 2C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft 2 at a feed pressure of only 20 psig. The highest H 2/N 2 selectivity obtained with this approach was 4.9. A transport model using “dusty gas” theory was derived to describe the hydrogen transport in the Mo 2C 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) Mo 2C catalyst layers. We have fabricated a Mo 2C/V composite membrane that in pure gas testing delivered a H 2 flux of 238 SCFH/ft 2 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/ft 2.psi. However, during testing of a Mo 2C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft 2.psi was obtained which was stable during the entire test, meeting the permeance associated with the 2010 DOE target flux. Lastly, the Mo 2C/V composite membranes were shown to be stable for at least 168 hours = one week

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

PubMed

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

Electrical properties of lanthanum chromite based ceramics in hydrogen and oxidizing atmospheres at high temperatures

NASA Astrophysics Data System (ADS)

Schmidt, V. H.

1981-06-01

Several results regarding the effect of hydrogen on lanthanum chromite were determined. Thermally-activated diffusion of hydrogen through La(Mg)CrO3 was found with a high activation energy. It was found that its electrical conductivity drops drastically, especially at low temperature, after exposure to hydrogen at high temperature. Also, the curvature of most of the conductivity plots, as well as the inability to observe the Hall effect, lends support to the proposal by Karim and Aldred that the small-polaron model which predicts thermally activated mobility is applicable to doped lanthanum chromite. From differential thermal analysis, an apparent absorption of hydrogen near 3000 C was noticed. Upon cooling the lanthanum chromite in hydrogen and subsequently reheating it in air, desorption occurred near 1700 C. The immediate purpose of this study was to determine whether hydrogen has a deleterious effect on lanthanum chromite in solid oxide fuel cells.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2010-10-01

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 plantmore » 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.« less

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

NASA Astrophysics Data System (ADS)

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.

High speed hydrogen/graphite interaction

NASA Technical Reports Server (NTRS)

Kelly, A. J.; Hamman, R.; Sharma, O. P.; Harrje, D. T.

1974-01-01

Various aspects of a research program on high speed hydrogen/graphite interaction are presented. Major areas discussed are: (1) theoretical predictions of hydrogen/graphite erosion rates; (2) high temperature, nonequilibrium hydrogen flow in a nozzle; and (3) molecular beam studies of hydrogen/graphite erosion.

Composition for use in high-temperature hydrogen-fluorine environments and method for making the composition

DOEpatents

Kovach, Louis; Holcombe, Cressie E.

1982-01-01

The present invention relates to a composition particularly suitable for as structural components subject to high-temperature environments containing gaseous hydrogen and fluorine. The composition of the present invention consists essentially of lanthanum hexaboride-molybdenum diboride with dispersed silicon. The composition is formed by hot pressing a powder mixture of lanthanum hexaboride as the major constituent and molybdenum disilicide. This composition exhibits substantial resistance to thermal shock and corrosion in environments containing hydrogen and fluorine gases at material surface temperatures up to about 1850.degree. K. Upon exposure of the hot-pressed composition to high-temperature environments containing fluorine gases, a highly protective layer of lanthanum trifluoride containing dispersed molybdenum is formed on exposed surfaces of the composition.

Composition for use in high-temperature hydrogen-fluorine environments and method for making the composition

DOEpatents

Kovach, L.; Holcombe, C.E.

1980-08-22

The present invention relates to a composition particularly suitable for use as structural components subject to high-temperature environments containing gaseous hydrogen and fluorine. The composition of the present invention consists essentially of lanthanum hexaboride-molybdenum diboride with dispersed silicon. The composition is formed by hot pressing a powder mixture of lanthanum hexaboride as the major constituent and molybdenum disilicide. This composition exhibits substantial resistance to thermal shock and corrosion in environments containing hydrogen and fluorine gases at material surface temperatures up to about 1850/sup 0/K. Upon exposure of the hot-pressed composition to high-temperature environments containing fluorine gases, a highly protective layer of lanthanum trifluoride containing dispersed molybdenum is formed on exposed surfaces of the composition.

Hydrogen permeation behavior through F82H at high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuda, S.; Katayama, K.; Shimozori, M.

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 tomore » 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)« less

Nanocomposite thin films for high temperature optical gas sensing of hydrogen

DOEpatents

Ohodnicki, Jr., Paul R.; Brown, Thomas D.

2013-04-02

The disclosure relates to a plasmon resonance-based method for H.sub.2 sensing in a gas stream at temperatures greater than about 500.degree. C. utilizing a hydrogen sensing material. The hydrogen sensing material is comprised of gold nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10.sup.-7 S/cm at a temperature of 700.degree. C. Exemplary inert matrix materials include SiO.sub.2, Al.sub.2O.sub.3, and Si.sub.3N.sub.4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. At high temperatures, blue shift of the plasmon resonance optical absorption peak indicates the presence of H.sub.2. The method disclosed offers significant advantage over active and reducible matrix materials typically utilized, such as yttria-stabilized zirconia (YSZ) or TiO.sub.2.

High-temperature superconductivity using a model of hydrogen bonds.

PubMed

Kaplan, Daniel; Imry, Yoseph

2018-05-29

Recently, there has been much interest in high-temperature superconductors and more recently in hydrogen-based superconductors. This work offers a simple model that explains the behavior of the superconducting gap based on naive BCS (Bardeen-Cooper-Schrieffer) theory and reproduces most effects seen in experiments, including the isotope effect and [Formula: see text] enhancement as a function of pressure. We show that this is due to a combination of the factors appearing in the gap equation: the matrix element between the proton states and the level splitting of the proton.

Electrical properties of lanthanum chromite based ceramics in hydrogen and oxidizing atmospheres at high temperatures. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, V.H.

1981-06-01

Several results regarding the effect of hydrogen on lanthanum chromite were determined. Thermally-activated diffusion of hydrogen through La(Mg)CrO/sub 3/ was found with a high activation energy. It was found that its electrical conductivity drops drastically, especially at low temperature, after exposure to hydrogen at high temperature. Also, the curvature of most of the conductivity plots, as well as the inability to observe the Hall effect, lends support to the proposal by Karim and Aldred that the small-polaron model which predicts thermally activated mobility is applicable to doped lanthanum chromite. From differential thermal analysis an apparent absorption of hydrogen near 300/supmore » 0/C was noticed. Upon cooling the lanthanum chromite in hydrogen and subsequently reheating it in air, desorption occurred near 170/sup 0/C. The immediate purpose of this study was to determine whether hydrogen has a deleterious effect on lanthanum chromite in solid oxide fuel cells.« less

Behavior of hydrogen in alpha-iron at lower temperatures

NASA Technical Reports Server (NTRS)

Weizer, V. G.

1973-01-01

Evidence is presented that the low temperature anomalies in the hydrogen occlusive behavior of alpha iron can be explained by means of a molecular occlusion theory. This theory proposes that the stable state of the absorbed hydrogen changes from atomic at high temperatures to molecular as the temperature is lowered below a critical value. Theories proposing to explain the anomalous behavior as being due to the capture, at lower temperatures, of hydrogen in traps are shown to be unacceptable.

Thermodynamics of hydrogen-helium mixtures at high pressure and finite temperature

NASA Technical Reports Server (NTRS)

Hubbard, W. B.

1972-01-01

A technique is reviewed for calculating thermodynamic quantities for mixtures of light elements at high pressure, in the metallic state. Ensemble averages are calculated with Monte Carlo techniques and periodic boundary conditions. Interparticle potentials are assumed to be coulombic, screened by the electrons in dielectric function theory. This method is quantitatively accurate for alloys at pressures above about 10 Mbar. An alloy of equal parts hydrogen and helium by mass appears to remain liquid and mixed for temperatures above about 3000 K, at pressures of about 15 Mbar. The additive volume law is satisfied to within about 10%, but the Gruneisen equation of state gives poor results. A calculation at 1300 K shows evidence of a hydrogen-helium phase separation.

SSH2S: Hydrogen storage in complex hydrides for an auxiliary power unit based on high temperature proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Baricco, Marcello; Bang, Mads; Fichtner, Maximilian; Hauback, Bjorn; Linder, Marc; Luetto, Carlo; Moretto, Pietro; Sgroi, Mauro

2017-02-01

The main objective of the SSH2S (Fuel Cell Coupled Solid State Hydrogen Storage Tank) project was to develop a solid state hydrogen storage tank based on complex hydrides and to fully integrate it with a High Temperature Proton Exchange Membrane (HT-PEM) fuel cell stack. A mixed lithium amide/magnesium hydride system was used as the main storage material for the tank, due to its high gravimetric storage capacity and relatively low hydrogen desorption temperature. The mixed lithium amide/magnesium hydride system was coupled with a standard intermetallic compound to take advantage of its capability to release hydrogen at ambient temperature and to ensure a fast start-up of the system. The hydrogen storage tank was designed to feed a 1 kW HT-PEM stack for 2 h to be used for an Auxiliary Power Unit (APU). A full thermal integration was possible thanks to the high operation temperature of the fuel cell and to the relative low temperature (170 °C) for hydrogen release from the mixed lithium amide/magnesium hydride system.

Hydrogen production by high-temperature water splitting using electron-conducting membranes

DOEpatents

Lee, Tae H.; Wang, Shuangyan; Dorris, Stephen E.; Balachandran, Uthamalingam

2004-04-27

A device and method for separating water into hydrogen and oxygen is disclosed. A first substantially gas impervious solid electron-conducting membrane for selectively passing hydrogen is provided and spaced from a second substantially gas impervious solid electron-conducting membrane for selectively passing oxygen. When steam is passed between the two membranes at disassociation temperatures the hydrogen from the disassociation of steam selectively and continuously passes through the first membrane and oxygen selectively and continuously passes through the second membrane, thereby continuously driving the disassociation of steam producing hydrogen and oxygen.

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

NASA Technical Reports Server (NTRS)

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.

High Temperature Electrolysis for Hydrogen Production from Nuclear Energy – TechnologySummary

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. E. O'Brien; C. M. Stoots; J. S. Herring

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 andmore » 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.« less

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

PubMed

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.

Perovskite-type oxide thin film integrated fiber optic sensor for high-temperature hydrogen measurement.

PubMed

Tang, Xiling; Remmel, Kurtis; Lan, Xinwei; Deng, Jiangdong; Xiao, Hai; Dong, Junhang

2009-09-15

Small size fiber optic devices integrated with chemically sensitive photonic materials are emerging as a new class of high-performance optical chemical sensor that have the potential to meet many analytical challenges in future clean energy systems and environmental management. Here, we report the integration of a proton conducting perovskite oxide thin film with a long-period fiber grating (LPFG) device for high-temperature in situ measurement of bulk hydrogen in fossil- and biomass-derived syngas. The perovskite-type Sr(Ce(0.8)Zr(0.1))Y(0.1)O(2.95) (SCZY) nanocrystalline thin film is coated on the 125 microm diameter LPFG by a facile polymeric precursor route. This fiber optic sensor (FOS) operates by monitoring the LPFG resonant wavelength (lambda(R)), which is a function of the refractive index of the perovskite oxide overcoat. At high temperature, the types and population of the ionic and electronic defects in the SCZY structure depend on the surrounding hydrogen partial pressure. Thus, varying the H(2) concentration changes the SCZY film refractive index and light absorbing characteristics that in turn shifts the lambda(R) of the LPFG. The SCZY-coated LPFG sensor has been demonstrated for bulk hydrogen measurement at 500 degrees C for its sensitivity, stability/reversibility, and H(2)-selectivity over other relevant small gases including CO, CH(4), CO(2), H(2)O, and H(2)S, etc.

Room temperature thermal conductivity measurements of neat MOF-5 compacts with high pressure hydrogen and helium

DOE PAGES

Semelsberger, Troy Allen; Veenstra, Mike; Dixon, Craig

2016-02-09

Metal-organic frameworks (MOFs) are a highly porous crystalline material with potential in various applications including on-board vehicle hydrogen storage for fuel cell vehicles. The thermal conductivity of MOFs is an important parameter in the design and ultimate performance of an on-board hydrogen storage system. However, in-situ thermal conductivity measurements have not been previously reported. The present study reports room temperature thermal conductivity and thermal diffusivity measurements performed on neat MOF-5 cylindrical compacts (ρ = 0.4 g/mL) as a function of pressure (0.27–90 bar) and gas type (hydrogen and helium). The transient plane source technique was used to measure both themore » non-directional thermal properties (isotropic method) and the directional thermal properties (anisotropic method). High pressure measurements were made using our in-house built low-temperature, high pressure thermal conductivity sample cell. The intrinsic thermal properties of neat MOF-5 measured under vacuum were—Isotropic: k isotropic = 0.1319 W/m K, α isotropic = 0.4165 mm 2/s; Anisotropic: k axial = 0.1477 W/m K, k radial = 0.1218 W/m K, α axial = 0.5096 mm 2/s, and α radial = 0.4232 mm 2/s. The apparent thermal properties of neat MOF-5 increased with increasing hydrogen and helium pressure, with the largest increase occurring in the narrow pressure range of 0–10 bar and then monotonically asymptoting with increasing pressures up to around 90 bar. On average, a greater than two-fold enhancement in the apparent thermal properties was observed with neat MOF-5 in the presence of helium and hydrogen compared to the intrinsic values of neat MOF-5 measured under vacuum. The apparent thermal properties of neat MOF-5 measured with hydrogen were higher than those measured with helium, which were directly related to the gas-specific thermal properties of helium and hydrogen. Neat MOF-5 exhibited a small degree of anisotropy under all conditions measured with

Room temperature thermal conductivity measurements of neat MOF-5 compacts with high pressure hydrogen and helium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semelsberger, Troy Allen; Veenstra, Mike; Dixon, Craig

Metal-organic frameworks (MOFs) are a highly porous crystalline material with potential in various applications including on-board vehicle hydrogen storage for fuel cell vehicles. The thermal conductivity of MOFs is an important parameter in the design and ultimate performance of an on-board hydrogen storage system. However, in-situ thermal conductivity measurements have not been previously reported. The present study reports room temperature thermal conductivity and thermal diffusivity measurements performed on neat MOF-5 cylindrical compacts (ρ = 0.4 g/mL) as a function of pressure (0.27–90 bar) and gas type (hydrogen and helium). The transient plane source technique was used to measure both themore » non-directional thermal properties (isotropic method) and the directional thermal properties (anisotropic method). High pressure measurements were made using our in-house built low-temperature, high pressure thermal conductivity sample cell. The intrinsic thermal properties of neat MOF-5 measured under vacuum were—Isotropic: k isotropic = 0.1319 W/m K, α isotropic = 0.4165 mm 2/s; Anisotropic: k axial = 0.1477 W/m K, k radial = 0.1218 W/m K, α axial = 0.5096 mm 2/s, and α radial = 0.4232 mm 2/s. The apparent thermal properties of neat MOF-5 increased with increasing hydrogen and helium pressure, with the largest increase occurring in the narrow pressure range of 0–10 bar and then monotonically asymptoting with increasing pressures up to around 90 bar. On average, a greater than two-fold enhancement in the apparent thermal properties was observed with neat MOF-5 in the presence of helium and hydrogen compared to the intrinsic values of neat MOF-5 measured under vacuum. The apparent thermal properties of neat MOF-5 measured with hydrogen were higher than those measured with helium, which were directly related to the gas-specific thermal properties of helium and hydrogen. Neat MOF-5 exhibited a small degree of anisotropy under all conditions measured with

Room temperature micro-hydrogen-generator

NASA Astrophysics Data System (ADS)

Gervasio, Don; Tasic, Sonja; Zenhausern, Frederic

A new compact and cost-effective hydrogen-gas generator has been made that is well suited for supplying hydrogen to a fuel-cell for providing base electrical power to hand-carried appliances. This hydrogen-generator operates at room temperature, ambient pressure and is orientation-independent. The hydrogen-gas is generated by the heterogeneous catalytic hydrolysis of aqueous alkaline borohydride solution as it flows into a micro-reactor. This reactor has a membrane as one wall. Using the membrane keeps the liquid in the reactor, but allows the hydrogen-gas to pass out of the reactor to a fuel-cell anode. Aqueous alkaline 30 wt% borohydride solution is safe and promotes long application life, because this solution is non-toxic, non-flammable, and is a high energy-density (≥2200 W-h per liter or per kilogram) hydrogen-storage solution. The hydrogen is released from this storage-solution only when it passes over the solid catalyst surface in the reactor, so controlling the flow of the solution over the catalyst controls the rate of hydrogen-gas generation. This allows hydrogen generation to be matched to hydrogen consumption in the fuel-cell, so there is virtually no free hydrogen-gas during power generation. A hydrogen-generator scaled for a system to provide about 10 W electrical power is described here. However, the technology is expected to be scalable for systems providing power spanning from 1 W to kW levels.

Hydrogen production by high temperature water splitting using electron conducting membranes

DOEpatents

Balachandran, Uthamalingam; Wang, Shuangyan; Dorris, Stephen E.; Lee, Tae H.

2006-08-08

A device and method for separating water into hydrogen and oxygen is disclosed. A first substantially gas impervious solid electron-conducting membrane for selectively passing protons or hydrogen is provided and spaced from a second substantially gas impervious solid electron-conducting membrane for selectively passing oxygen. When steam is passed between the two membranes at dissociation temperatures the hydrogen from the dissociation of steam selectively and continuously passes through the first membrane and oxygen selectively and continuously passes through the second membrane, thereby continuously driving the dissociation of steam producing hydrogen and oxygen. The oxygen is thereafter reacted with methane to produce syngas which optimally may be reacted in a water gas shift reaction to produce CO₂ and H₂.

Hydrogen Production via a High-Efficiency Low-Temperature Reformer

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 opposedmore » 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

Increase the threshold voltage of high voltage GaN transistors by low temperature atomic hydrogen treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erofeev, E. V., E-mail: erofeev@micran.ru; Fedin, I. V.; Kutkov, I. V.

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 levelmore » 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.« less

Integrated Temperature and Hydrogen Sensors with MEMS Technology

PubMed Central

Jiang, Hongchuan; Huang, Min; Yu, Yibing; Tian, Xiaoyu; Zhang, Wanli; Zhang, Jianfeng; Huang, Yifan; Yu, Kun

2017-01-01

In this work, a PdNi thin film hydrogen gas sensor with integrated Pt thin film temperature sensor was designed and fabricated using the micro-electro-mechanical system (MEMS) process. The integrated sensors consist of two resistors: the former, based on Pt film, is used as a temperature sensor, while the latter had the function of hydrogen sensing and is based on PdNi alloy film. The temperature coefficient of resistance (TCR) in both devices was measured and the output response of the PdNi film hydrogen sensor was calibrated based on the temperature acquired by the Pt temperature sensor. The SiN layer was deposited on top of Pt film to inhibit the hydrogen diffusion and reduce consequent disturbance on temperature measurement. The TCR of the PdNi film and the Pt film was about 0.00122/K and 0.00217/K, respectively. The performances of the PdNi film hydrogen sensor were investigated with hydrogen concentrations from 0.3% to 3% on different temperatures from 294.7 to 302.2 K. With the measured temperature of the Pt resistor and the TCR of the PdNi film, the impact of the temperature on the performances of the PdNi film hydrogen sensor was reduced. The output response, response time and recovery time of the PdNi film hydrogen sensors under the hydrogen concentration of 0.5%, 1.0%, 1.5% and 2.0% were measured at 313 K. The output response of the PdNi thin film hydrogen sensors increased with increasing hydrogen concentration while the response time and recovery time decreased. A cycling test between pure nitrogen and 3% hydrogen concentration was performed at 313 K and PdNi thin film hydrogen sensor demonstrated great repeatability in the cycling test. PMID:29301220

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

NASA Astrophysics Data System (ADS)

Roychowdhury, S.; Seifert, H.-P.; Spätig, P.; Que, Z.

2016-09-01

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.

Biofiltration of hydrogen sulfide by Sulfolobus metallicus at high temperatures.

PubMed

Morales, M; Silva, J; Morales, P; Gentina, J C; Aroca, G

2012-01-01

Biofiltration of reduced sulfur compounds such as hydrogen sulfide has been mainly applied to emissions at mild temperatures (25 to 35 °C). However, an important number of industrial gaseous emission containing sulfur compounds, from diverse industrial sectors (petroleum refinery, cellulose production, smelting, rendering plants and food industries) are emitted at temperatures over 50 °C. Most of the studies on thermophilic systems report that a higher elimination capacity can be obtained at elevated temperature, allowing the design of smaller equipment for the same loading rate than that required for removing the same load under mesophilic conditions. A biotrickling filter inoculated with Sulfolobus metallicus, which operates at three different residence times, 60, 80 and 120 s, and two different temperatures (45 and 55 °C) for treating H(2)S is reported. The input loads of H(2)S were progressively increased from 0 to 100 gS/m(3). The aim of this study was to determine the capacity and ability of S. metallicus to oxidize H(2)S at high temperatures. The better removal capacity of H(2)S obtained was 37.1 ± 1.7 gS/m(3) h at 55 °C for a residence time of 120 s. The difference of the removal capacity of H(2)S between the two temperatures was 4 g/m(3) h on average of sulfur removal for the different residence times.

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

PubMed

Ko, Tzu-Hsing; Chu, Hsin; Lin, Hsiao-Ping; Peng, Ching-Yu

2006-08-25

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 773K. 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.

Metallic Hydrogen - Potentially a High Energy Rocket Propellant

NASA Technical Reports Server (NTRS)

Cole, John; Silvera, Ike

2007-01-01

Pure metallic hydrogen is predicted to have a specific impulse (Isp) of 1700 seconds, but the reaction temperature is too high for current engine materials. Diluting metallic hydrogen with liquid hydrogen can reduce the reaction temperature to levels compatible with current material limits and still provide an Isp greater than 900 s. Metallic hydrogen has not yet been produced on earth, but experimental techniques exist that may change this situation. This paper will provide a brief description of metallic hydrogen and the status of experiments that may soon produce detectable quantities of this material in the lab. Also provided are some characteristics for diluted metallic hydrogen engines and launch vehicles.

Development Program of IS Process Pilot Test Plant for Hydrogen Production With High-Temperature Gas-Cooled Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin Iwatsuki; Atsuhiko Terada; Hiroyuki Noguchi

2006-07-01

At the present time, we are alarmed by depletion of fossil energy and effects on global environment such as acid rain and global warming, because our lives depend still heavily on fossil energy. So, it is universally recognized that hydrogen is one of the best energy media and its demand will be increased greatly in the near future. In Japan, the Basic Plan for Energy Supply and Demand based on the Basic Law on Energy Policy Making was decided upon by the Cabinet on 6 October, 2003. In the plan, efforts for hydrogen energy utilization were expressed as follows; hydrogenmore » is a clean energy carrier without carbon dioxide (CO{sub 2}) emission, and commercialization of hydrogen production system using nuclear, solar and biomass, not fossil fuels, is desired. However, it is necessary to develop suitable technology to produce hydrogen without CO{sub 2} emission from a view point of global environmental protection, since little hydrogen exists naturally. Hydrogen production from water using nuclear energy, especially the high-temperature gas-cooled reactor (HTGR), is one of the most attractive solutions for the environmental issue, because HTGR hydrogen production by water splitting methods such as a thermochemical iodine-sulfur (IS) process has a high possibility to produce hydrogen effectively and economically. The Japan Atomic Energy Agency (JAEA) has been conducting the HTTR (High-Temperature Engineering Test Reactor) project from the view to establishing technology base on HTGR and also on the IS process. In the IS process, raw material, water, is to be reacted with iodine (I{sub 2}) and sulfur dioxide (SO{sub 2}) to produce hydrogen iodide (HI) and sulfuric acid (H{sub 2}SO{sub 4}), the so-called Bunsen reaction, which are then decomposed endo-thermically to produce hydrogen (H{sub 2}) and oxygen (O{sub 2}), respectively. Iodine and sulfur dioxide produced in the decomposition reactions can be used again as the reactants in the Bunsen reaction. In JAEA

Fabrication method for a room temperature hydrogen sensor

NASA Technical Reports Server (NTRS)

Shukla, Satyajit V. (Inventor); Cho, Hyoung (Inventor); Seal, Sudipta (Inventor); Ludwig, Lawrence (Inventor)

2011-01-01

A sensor for selectively determining the presence and measuring the amount of hydrogen in the vicinity of the sensor. The sensor comprises a MEMS device coated with a nanostructured thin film of indium oxide doped tin oxide with an over layer of nanostructured barium cerate with platinum catalyst nanoparticles. Initial exposure to a UV light source, at room temperature, causes burning of organic residues present on the sensor surface and provides a clean surface for sensing hydrogen at room temperature. A giant room temperature hydrogen sensitivity is observed after making the UV source off. The hydrogen sensor of the invention can be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently used at room temperature.

Metal-Borohydride-Modified Zr(BH4 )4 ⋅8 NH3 : Low-Temperature Dehydrogenation Yielding Highly Pure Hydrogen.

PubMed

Huang, Jianmei; Ouyang, Liuzhang; Gu, Qinfen; Yu, Xuebin; Zhu, Min

2015-10-12

Due to its high hydrogen density (14.8 wt %) and low dehydrogenation peak temperature (130 °C), Zr(BH4 )4 ⋅8 NH3 is considered to be one of the most promising hydrogen-storage materials. To further decrease its dehydrogenation temperature and suppress its ammonia release, a strategy of introducing LiBH4 and Mg(BH4 )2 was applied to this system. Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 and Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 composites showed main dehydrogenation peaks centered at 81 and 106 °C as well as high hydrogen purities of 99.3 and 99.8 mol % H2 , respectively. Isothermal measurements showed that 6.6 wt % (within 60 min) and 5.5 wt % (within 360 min) of hydrogen were released at 100 °C from Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 and Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 , respectively. The lower dehydrogenation temperatures and improved hydrogen purities could be attributed to the formation of the diammoniate of diborane for Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 , and the partial transfer of NH3 groups from Zr(BH4 )4 ⋅8 NH3 to Mg(BH4 )2 for Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 , which result in balanced numbers of BH4 and NH3 groups and a more active H(δ+) ⋅⋅⋅(-δ) H interaction. These advanced dehydrogenation properties make these two composites promising candidates as hydrogen-storage materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

NASA Technical Reports Server (NTRS)

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.

Electrocatalytic Hydrogenation of Phenol over Platinum and Rhodium: Unexpected Temperature Effects Resolved

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Nirala; Song, Yang; Gutiérrez, Oliver Y.

2016-11-04

Both electrocatalytic hydrogenation (ECH) and thermal hydrogenation (TH) of phenol by Pt and Rh show a roll-over in rate with increasing temperature without changing the principal reaction pathways. The negative effect of temperature for aqueous-phase phenol H2 and electrocatalytic hydrogenation on Pt and Rh is deduced to be due to the unexpected buildup of dehydrogenated phenol adsorbates, which block active sites. Rates of ECH and TH increase similarly with increasing hydrogen chemical potential whether induced by applied potential or H2 pressure, both via increasing H coverage, and indirectly by removing site blockers, a very strong effect at high temperature. Thismore » enables unprecedented rates in the TH of phenol at these temperatures.« less

Emergence of a High-Temperature Superconductivity in Hydrogen Cycled pd Compounds as AN Evidence for Superstoihiometric H/d Sites

NASA Astrophysics Data System (ADS)

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.

High-Temperature Proton-Conducting Ceramics Developed

NASA Technical Reports Server (NTRS)

Sayir, Ali; Dynys, Frederick W.; Berger, M. H.

2005-01-01

High-temperature protonic conductors (HTPC) are needed for hydrogen separation, hydrogen sensors, fuel cells, and hydrogen production from fossil fuels. The HTPC materials for hydrogen separation at high temperatures are foreseen to be metal oxides with the perovskite structure A(sup 2+)B(sup 4+)C(sup 2-, sub 3) and with the trivalent cation (M(sup 3+)) substitution at the B(sup 4+)-site to introduce oxygen vacancies. The high affinity for hydrogen ions (H(sup +)) is advantageous for protonic transport, but it increases the reactivity toward water (H2O) and carbon dioxide (CO2), which can lead to premature membrane failure. In addition, there are considerable technological challenges related to the processing of HTPC materials. The high melting point and multi-cation chemistry of HTPC materials creates difficulties in in achieving high-density, single-phase membranes by solid-state sintering. The presence of secondary phases and grain-boundary interfaces are detrimental to the protonic conduction and environmental stability of polycrystalline HTPC materials.

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

NASA Astrophysics Data System (ADS)

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 (< 10 mTorr) 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 (< 1 kW), the molecular hydrogen temperature was observed to be linearly proportional to the pressure while the atomic hydrogen temperature was inversely proportional. Both temperatures were observed to rise linearly with input power. For high power operation (5-20 kW), the molecular temperature was found to rise with both power and pressure up to a maximum of approximately 1200 K. Spatially resolved 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.

Rhodium dihydride (RhH2) with high volumetric hydrogen density

PubMed Central

Li, Bing; Ding, Yang; Kim, Duck Young; Ahuja, Rajeev; Zou, Guangtian; Mao, Ho-Kwang

2011-01-01

Materials with very high hydrogen density have attracted considerable interest due to a range of motivations, including the search for chemically precompressed metallic hydrogen and hydrogen storage applications. Using high-pressure synchrotron X-ray diffraction technique and theoretical calculations, we have discovered a new rhodium dihydride (RhH2) with high volumetric hydrogen density (163.7 g/L). Compressing rhodium in fluid hydrogen at ambient temperature, the fcc rhodium metal absorbs hydrogen and expands unit-cell volume by two discrete steps to form NaCl-typed fcc rhodium monohydride at 4 GPa and fluorite-typed fcc RhH2 at 8 GPa. RhH2 is the first dihydride discovered in the platinum group metals under high pressure. Our low-temperature experiments show that RhH2 is recoverable after releasing pressure cryogenically to 1 bar and is capable of retaining hydrogen up to 150 K for minutes and 77 K for an indefinite length of time. PMID:22039219

Effect of Atomic Hydrogen on Preparation of Highly Moisture-Resistive SiNx Films at Low Substrate Temperatures

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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.

The problems of using a high-temperature sodium coolant in nuclear power plants for the production of hydrogen and other innovative applications

NASA Astrophysics Data System (ADS)

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.

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

PubMed Central

Li, Meng; Xie, De-Gang; Ma, Evan; Li, Ju; Zhang, Xi-Xiang; 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. PMID:28218260

Thermodynamics and Transport Phenomena in High Temperature Steam Electrolysis Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

James E. O'Brien

2012-03-01

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. 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. An overview of high temperature electrolysis technologymore » will be presented, including basic thermodynamics, experimental methods, heat and mass transfer phenomena, and computational fluid dynamics modeling.« less

Confinement of hydrogen at high pressure in carbon nanotubes

DOEpatents

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

2011-12-13

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

Influence of gaseous hydrogen on the mechanical properties of high temperature alloys

NASA Technical Reports Server (NTRS)

1976-01-01

Tensile tests of six nickel-base and one cobalt-base alloy were conducted in 34.5 MN/sq m helium and hydrogen environments at temperatures from 297 K to 1,088 K. Mechanical properties tests of the nickel-base alloy MAR M-246 (Hf modified), in two cast conditions, were conducted in gaseous environments at temperatures from 297 K to 1,144 K and pressures from one atmosphere to 34.5 MN/sq m. The objective of this program was to obtain the mechanical properties of the various alloys proposed for use in space propulsion systems in a pure hydrogen environment at different temperatures and to compare with the mechanical properties in helium at the same conditions. All testing was conducted on solid specimens exposed to external gaseous pressure. Smooth and notched tensile properties were determined using ASTM tensile testing techniques, and creep-rupture life was determined using ASTM creep-rupture techniques. Low-cycle fatigue life was established by constant total strain and constant stress testing using smooth specimens and a closed-loop test machine.

Searching for magnetism in hydrogenated graphene: using highly hydrogenated graphene prepared via Birch reduction of graphite oxides.

PubMed

Eng, Alex Yong Sheng; Poh, Hwee Ling; Šaněk, Filip; Maryško, Miroslav; Matějková, Stanislava; Sofer, Zdeněk; Pumera, Martin

2013-07-23

Fully hydrogenated graphene (graphane) and partially hydrogenated graphene materials are expected to possess various fundamentally different properties from graphene. We have prepared highly hydrogenated graphene containing 5% wt of hydrogen via Birch reduction of graphite oxide using elemental sodium in liquid NH3 as electron donor and methanol as proton donor in the reduction. We also investigate the influence of preparation method of graphite oxide, such as the Staudenmaier, Hofmann or Hummers methods on the hydrogenation rate. A control experiment involving NaNH2 instead of elemental Na was also performed. The materials were characterized in detail by electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy both at room and low temperatures, X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, combustible elemental analysis and electrical resistivity measurements. Magnetic measurements are provided of bulk quantities of highly hydrogenated graphene. In the whole temperature range up to room temperature, the hydrogenated graphene exhibits a weak ferromagnetism in addition to a contribution proportional to field that is caused not only by diamagnetism but also likely by an antiferromagnetic influence. The origin of the magnetism is also determined to arise from the hydrogenated graphene itself, and not as a result of any metallic impurities.

Microstructure and high-temperature tribological properties of Si-doped hydrogenated diamond-like carbon films

NASA Astrophysics Data System (ADS)

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.

Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ting, Valeska P.; Ramirez-Cuesta, Anibal J.; Bimbo, Nuno

Here in this paper we report direct physical evidence that confinement of molecular hydrogen (H 2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H 2 at temperatures up to 67 K above the liquid vapor critical temperature of bulk H 2. This extreme densification is attributed to confinement of 112 molecules in the optimally sized micropores, and occurs at pressures as low as 0.02 MPa. The quantities of contained, solid-like H 2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorptionmore » isotherms. The demonstration of the existence of solid-like H 2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H 2 density. Thus, this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.« less

Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures

DOE PAGES

Ting, Valeska P.; Ramirez-Cuesta, Anibal J.; Bimbo, Nuno; ...

2015-07-14

Here in this paper we report direct physical evidence that confinement of molecular hydrogen (H 2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H 2 at temperatures up to 67 K above the liquid vapor critical temperature of bulk H 2. This extreme densification is attributed to confinement of 112 molecules in the optimally sized micropores, and occurs at pressures as low as 0.02 MPa. The quantities of contained, solid-like H 2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorptionmore » isotherms. The demonstration of the existence of solid-like H 2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H 2 density. Thus, this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.« less

Mechanical properties of turbine blade alloys in hydrogen at elevated temperatures

NASA Technical Reports Server (NTRS)

Deluca, D. P.

1981-01-01

The mechanical properties of single crystal turbine blade alloys in a gaseous hydrogen environment were determined. These alloys are proposed for use in space propulsion systems in pure or partial high pressure hydrogen environments at elevated temperatures. Mechanical property tests included: tensile, creep, low fatigue (LCF), and crack growth. Specimens were in both transverse and longitudinal directions relative to the casting solidification direction. Testing was conducted on solid specimens exposed to externally pressurized environments of gaseous hydrogen and hydrogen-enriched steam.

On-line hydrogen-isotope measurements of organic samples using elemental chromium: An extension for high temperature elemental-analyzer techniques

USGS Publications Warehouse

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

Low temperature synthesis of hexagonal ZnO nanorods and their hydrogen sensing properties

NASA Astrophysics Data System (ADS)

Qurashi, Ahsanulhaq; Faiz, M.; Tabet, N.; Alam, Mir Waqas

2011-08-01

The growth of hexagonal ZnO nanorods was demonstrated by low temperature chemical synthesis approach. X-ray diffraction (XRD) analysis revealed a wurtzite hexagonal structure of the ZnO nanorods. The optical properties were measured by UV-vis spectrophotometer at room temperature. X-ray photoelectron spectroscopy (XPS) confirmed high purity of the ZnO nanorods. The hydrogen sensor made of the ZnO nanorods showed reversible response. The hydrogen gas tests were carried out in presence of ambient air and the influence of operation temperature on the hydrogen gas sensing property of ZnO nanorods was also investigated.

Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

DOEpatents

Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

1999-08-24

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

DOEpatents

Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

1997-07-08

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Sorption of hydrogen by silica aerogel at low-temperatures

NASA Astrophysics Data System (ADS)

Dolbin, A. V.; Khlistyuck, M. V.; Esel'son, V. B.; Gavrilko, V. G.; Vinnikov, N. A.; Basnukaeva, R. M.; Martsenuk, V. E.; Veselova, N. V.; Kaliuzhnyi, I. A.; Storozhko, A. V.

2018-02-01

The programmed thermal desorption method is used at temperatures of 7-95 K to study the sorption and subsequent desorption of hydrogen by a sample of silica aerogel. Physical sorption of hydrogen owing to the weak van-der-Waals interaction of hydrogen molecules with the silicon dioxide walls of the pores of the sample was observed over the entire temperature range. The total capacity of the aerogel sample for hydrogen was ˜1.5 mass %. It was found that when the sample temperature was lowered from 95 to 60 K, the characteristic sorption times for hydrogen by the silica aerogel increase; this is typical of thermally activated diffusion (Ea ≈ 408 K). For temperatures of 15-45 K the characteristic H2 sorption times depended weakly on temperature, presumably because of the predominance of a tunnel mechanism for diffusion over thermally activated diffusion. Below 15 K the characteristic sorption times increase somewhat as the temperature is lowered; this may be explained by the formation of a monolayer of H2 molecules on the surface of the aerogel grains.

Temperature- and composition-dependent hydrogen diffusivity in palladium from statistically-averaged molecular dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xiaowang; Heo, Tae Wook; Wood, Brandon C.

Solid-state hydrogen storage materials undergo complex phase transformations whose kinetics is often limited by hydrogen diffusion. Among metal hydrides, palladium hydride undergoes a diffusional phase transformation upon hydrogen uptake, during which the hydrogen diffusivity varies with hydrogen composition and temperature. Here we perform robust statistically-averaged molecular dynamics simulations to obtain a well-converged analytical expression for hydrogen diffusivity in bulk palladium that is valid throughout all stages of the reaction. Our studies confirm significant dependence of the diffusivity on composition and temperature that elucidate key trends in the available experimental measurements. Whereas at low hydrogen compositions, a single process dominates, atmore » high hydrogen compositions, diffusion is found to exhibit behavior consistent with multiple hopping barriers. Further analysis, supported by nudged elastic band computations, suggests that the multi-barrier diffusion can be interpreted as two distinct mechanisms corresponding to hydrogen-rich and hydrogen-poor local environments.« less

Temperature- and composition-dependent hydrogen diffusivity in palladium from statistically-averaged molecular dynamics

DOE PAGES

Zhou, Xiaowang; Heo, Tae Wook; Wood, Brandon C.; ...

2018-03-09

Solid-state hydrogen storage materials undergo complex phase transformations whose kinetics is often limited by hydrogen diffusion. Among metal hydrides, palladium hydride undergoes a diffusional phase transformation upon hydrogen uptake, during which the hydrogen diffusivity varies with hydrogen composition and temperature. Here we perform robust statistically-averaged molecular dynamics simulations to obtain a well-converged analytical expression for hydrogen diffusivity in bulk palladium that is valid throughout all stages of the reaction. Our studies confirm significant dependence of the diffusivity on composition and temperature that elucidate key trends in the available experimental measurements. Whereas at low hydrogen compositions, a single process dominates, atmore » high hydrogen compositions, diffusion is found to exhibit behavior consistent with multiple hopping barriers. Further analysis, supported by nudged elastic band computations, suggests that the multi-barrier diffusion can be interpreted as two distinct mechanisms corresponding to hydrogen-rich and hydrogen-poor local environments.« less

Arrays of Regenerated Fiber Bragg Gratings in Non-Hydrogen-Loaded Photosensitive Fibers for High-Temperature Sensor Networks

PubMed Central

Lindner, Eric; Chojetztki, Christoph; Brueckner, Sven; Becker, Martin; Rothhardt, Manfred; Vlekken, Johan; Bartelt, Hartmut

2009-01-01

We report about the possibility of using regenerated fiber Bragg gratings generated in photosensitive fibers without applying hydrogen loading for high temperature sensor networks. We use a thermally induced regenerative process which leads to a secondary increase in grating reflectivity. This refractive index modification has shown to become more stable after the regeneration up to temperatures of 600 °C. With the use of an interferometric writing technique, it is possible also to generate arrays of regenerated fiber Bragg gratings for sensor networks. PMID:22408510

An effective temperature compensation approach for ultrasonic hydrogen sensors

NASA Astrophysics Data System (ADS)

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.

Integrated multi-channel nano-engineered optical hydrogen and temperature sensor detection systems for launch vehicles

NASA Astrophysics Data System (ADS)

Alam, M. Z.; Moreno, J.; Aitchison, J. S.; Mojahedi, M.; Kazemi, A. A.

2008-08-01

Launch vehicles and other satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. Being a very small molecule, hydrogen is prone to leakage through seals and micro-cracks. Hydrogen detection in space application is very challenging; public acceptance of hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of cryogenic fluids in spaceport facilities, launch vehicle industry and aerospace agencies are currently relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh several hundred kilograms. Therefore, there is a critical need for miniaturized sensors and instruments suitable for use in space applications. This paper describes a novel multi-channel integrated nano-engineered optical sensor to detect hydrogen and monitor the temperature. The integrated optic sensor is made of multi-channel waveguide elements that measure hydrogen concentration in real Time. Our sensor is based on the use of a high index waveguide with a Ni/Pd overlay to detect hydrogen. When hydrogen is absorbed into the Ni/Pd alloy there is a change in the absorption of the material and the optical signal in the waveguide is increased. Our design uses a thin alloy (few nanometers thick) overlay which facilitates the absorption of the hydrogen and will result in a response time of approximately few seconds. Like other Pd/Pd-Ni based sensors the device response varies with temperature and hence the effects of temperature variations must be taken into account. One solution to this problem is simultaneous measurement of temperature in addition to hydrogen concentration at the same vicinity. Our approach here is to propose a temperature sensor that can easily be integrated on the same platform as the hydrogen sensor reported earlier by our group. One suitable choice of material system is silicon on insulator (SOI). Here, we propose a micro ring resonators

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Life cycle assessment of hydrogen production from S-I thermochemical process coupled to a high temperature gas reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giraldi, M. R.; Francois, J. L.; Castro-Uriegas, D.

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 wasmore » 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)« less

Distribution of deuterium and hydrogen in Zr and Ti foil assemblies under the action of a pulsed deuterium high-temperature plasma

NASA Astrophysics Data System (ADS)

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.

Hydrogen Clathrate Structures in Rare Earth Hydrides at High Pressures: Possible Route to Room-Temperature Superconductivity

NASA Astrophysics Data System (ADS)

Peng, Feng; Sun, Ying; Pickard, Chris J.; Needs, Richard J.; Wu, Qiang; Ma, Yanming

2017-09-01

Room-temperature superconductivity has been a long-held dream and an area of intensive research. Recent experimental findings of superconductivity at 200 K in highly compressed hydrogen (H) sulfides have demonstrated the potential for achieving room-temperature superconductivity in compressed H-rich materials. We report first-principles structure searches for stable H-rich clathrate structures in rare earth hydrides at high pressures. The peculiarity of these structures lies in the emergence of unusual H cages with stoichiometries H24 , H29 , and H32 , in which H atoms are weakly covalently bonded to one another, with rare earth atoms occupying the centers of the cages. We have found that high-temperature superconductivity is closely associated with H clathrate structures, with large H-derived electronic densities of states at the Fermi level and strong electron-phonon coupling related to the stretching and rocking motions of H atoms within the cages. Strikingly, a yttrium (Y) H32 clathrate structure of stoichiometry YH10 is predicted to be a potential room-temperature superconductor with an estimated Tc of up to 303 K at 400 GPa, as derived by direct solution of the Eliashberg equation.

Hydrogen Clathrate Structures in Rare Earth Hydrides at High Pressures: Possible Route to Room-Temperature Superconductivity.

PubMed

Peng, Feng; Sun, Ying; Pickard, Chris J; Needs, Richard J; Wu, Qiang; Ma, Yanming

2017-09-08

Room-temperature superconductivity has been a long-held dream and an area of intensive research. Recent experimental findings of superconductivity at 200 K in highly compressed hydrogen (H) sulfides have demonstrated the potential for achieving room-temperature superconductivity in compressed H-rich materials. We report first-principles structure searches for stable H-rich clathrate structures in rare earth hydrides at high pressures. The peculiarity of these structures lies in the emergence of unusual H cages with stoichiometries H_{24}, H_{29}, and H_{32}, in which H atoms are weakly covalently bonded to one another, with rare earth atoms occupying the centers of the cages. We have found that high-temperature superconductivity is closely associated with H clathrate structures, with large H-derived electronic densities of states at the Fermi level and strong electron-phonon coupling related to the stretching and rocking motions of H atoms within the cages. Strikingly, a yttrium (Y) H_{32} clathrate structure of stoichiometry YH_{10} is predicted to be a potential room-temperature superconductor with an estimated T_{c} of up to 303 K at 400 GPa, as derived by direct solution of the Eliashberg equation.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 analysismore » 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.« less

Structural phase transition at high temperatures in solid molecular hydrogen and deuterium

NASA Astrophysics Data System (ADS)

Cui, T.; Takada, Y.; Cui, Q.; Ma, Y.; Zou, G.

2001-07-01

We study the effect of temperature up to 1000 K on the structure of dense molecular para-hydrogen (p-H2) and ortho-deuterium (o-D2), using the path-integral Monte Carlo method. We find a structural phase transition from orientationally disordered hexagonal close packed (hcp) to an orthorhombic structure of Cmca symmetry before melting. The transition is basically induced by thermal fluctuations, but quantum fluctuations of protons (deuterons) are important in determining the transition temperature through effectively hardening the intermolecular interaction. We estimate the phase line between hcp and Cmca phases as well as the melting line of the Cmca solid.

Resistivity behavior of hydrogen and liquid silane at high shock compression

NASA Astrophysics Data System (ADS)

Wang, Yi-Gao; Liu, Fu-Sheng; Liu, Qi-Jun

2018-07-01

To study the electrical properties of hydrogen rich compounds under extreme conditions, the electrical resistivity of density hydrogen and silane fluid was measured, respectively. The hydrogen sample was prepared by compressing pure hydrogen gas to 10 MPa in a coolant target system at the temperature of 77 K. The silane sample can be obtained with the same method. High-pressure and high-temperature experiments were performed using a two-stage light-gas gun. The electrical resistivity of the sample decreased with increasing pressure and temperature as expected. A minimum electrical resistivity value of 0.3 × 10-3 Ω cm at 138 GPa and 4100 K was obtained for silane. The minimum resistivity of hydrogen in the state of 102 GPa and 4300 K was 0.35 Ω cm. It showed that the measured electrical resistivity of the shock-compressed hydrogen was an order of magnitude higher than fluid silane at 50-90 GPa. However, beyond 100 GPa, the resistivity difference between silane and hydrogen was very minor. The carriers in the sample were hydrogen, and the concentration of hydrogen atoms in these two substances was close to each other. These results supported the theoretical prediction that silane was interpreted simply in terms of chemical decomposition into silicon nanoparticles and fluid hydrogen, and electrical conduction flows predominately dominated by the fluid hydrogen. In addition, the results also supported the theory of "chemical precompression", the existence of Sisbnd H bond helped to reduce the pressure of hydrogen metallization. These findings could lead the way for further metallic phases of hydrogen-rich materials and experimental studies.

Causes of High-temperature Superconductivity in the Hydrogen Sulfide Electron-phonon System

NASA Astrophysics Data System (ADS)

Degtyarenko, N. N.; Mazur, E. A.

The electron and phonon spectra, as well as the density of electron and phonon states of the stable orthorhombic structure of hydrogen sulfide (SH2) at pressures 100-180 GPa have been calculated. It is found that the set of parallel planes of hydrogen atoms is formed at pressure ∼175 GPa as a result of structural changes in the unit cell of the crystal under pressure. There should be complete concentration of hydrogen atoms in these planes. As a result the electron properties of the system acquire a quasi-two-dimensional character. The features of in phase and antiphase oscillations of hydrogen atoms in these planes leading to two narrow high-energy peaks in the phonon density of states are investigated.

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

NASA Technical Reports Server (NTRS)

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.

Properties of materials in high pressure hydrogen at cryogenic, room, and elevated temperatures

NASA Technical Reports Server (NTRS)

Harris, J. A., Jr.; Vanwanderham, M. C.

1973-01-01

Various tests were conducted to determine the mechanical properties of 12 alloys that are commonly used or proposed for use in pressurized gaseous hydrogen or hydrogen containing environments. Properties determined in the hydrogen environments were compared to properties determined in a pure helium environment at the same conditions to establish environmental degradation. The specific mechanical properties tested include: high-cycle fatigue, low-cycle fatigue, fracture mechanics, creep-rupture, and tensile.

Effect of Hydrogen and Carbon on the Melting Temperature of the Core

NASA Astrophysics Data System (ADS)

Nakajima, Y.; Sakamaki, K.; Takahashi, E.; Fukai, Y.; Suzuki, T.; Funakoshi, K.

2007-12-01

The temperature of the Earth's outer core has been discussed based on the melting temperature of Fe- O-S alloys (e.g., Boehler, 1996). Although hydrogen and carbon are the possible candidates of the core component, their effects on the melting temperature of iron at high-pressures are unclear. Using a Kawai-type multi-anvil apparatus at SPring-8 synchrotron, we carried out a series of melting experiments on FeH and Fe3C up to 20 and 28 GPa, respectively. In the experiments on FeH, Fe sponge mixed with MgO was packed into a NaCl container with a hydrogen source, LiAlH4 (e.g., Fukai et al., 1989). During heating under high-pressures, hydrogenation of iron was observed by volume change. The phase boundary between ɛ'-phase (low-temperature phase) and γ-phase (high-temperature phase) of iron-hydride was determined using both cooling and heating experiments. Hydrogen concentrations in the γ-FeHx and ɛ'-FeHx were calculated based on the excess volume data from that of pure iron. It is found that γ-FeHx and ɛ'-FeHx synthesized in our experiments at pressures between 10 and 20 GPa are nearly stoichiometric FeH. Melting temperature of the γ-FeH was determined by the abrupt change in the X-ray diffraction patterns (crystalline to amorphous). The melting temperatures were determined to be 1473, 1473, 1493, 1573 and 1593 K at 10, 11.5, 15, 18 and 20 GPa, respectively. In the experiments using Fe3C, the synthesized Fe3C powder was encapsulated in a MgO container. In the diffraction sequences during heating, the peaks of Fe3C disappeared, and the new peaks identified as those of Fe7C3 were observed with halo caused by liquid. Finally, the Fe7C3 peaks disappeared, and only the halo pattern was observed. Based on these observations, the incongruent melting of Fe3C to Fe7C3 and liquid is estimated to occur at 1823 and 1923 K at 19.7 and 27.0 GPa, respectively. The liquidus temperatures of the Fe3C composition are found to be at 2098 and 2198 K at 19.5 and 26.8 GPa

Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen production.

PubMed

Bayro-Kaiser, Vinzenz; Nelson, Nathan

2016-12-01

The need for energy and the associated burden are ever growing. It is crucial to develop new technologies for generating clean and efficient energy for society to avoid upcoming energetic and environmental crises. Sunlight is the most abundant source of energy on the planet. Consequently, it has captured our interest. Certain microalgae possess the ability to capture solar energy and transfer it to the energy carrier, H 2 . H 2 is a valuable fuel, because its combustion produces only one by-product: water. However, the establishment of an efficient biophotolytic H 2 production system is hindered by three main obstacles: (1) the hydrogen-evolving enzyme, [FeFe]-hydrogenase, is highly sensitive to oxygen; (2) energy conversion efficiencies are not economically viable; and (3) hydrogen-producing organisms are sensitive to stressful conditions in large-scale production systems. This study aimed to circumvent the oxygen sensitivity of this process with a cyclic hydrogen production system. This approach required a mutant that responded to high temperatures by reducing oxygen evolution. To that end, we randomly mutagenized the green microalgae, Chlamydomonas reinhardtii, to generate mutants that exhibited temperature-sensitive photoautotrophic growth. The selected mutants were further characterized by their ability to evolve oxygen and hydrogen at 25 and 37 °C. We identified four candidate mutants for this project. We characterized these mutants with PSII fluorescence, P700 absorbance, and immunoblotting analyses. Finally, we demonstrated that these mutants could function in a prototype hydrogen-producing bioreactor. These mutant microalgae represent a novel approach for sustained hydrogen production.

Finite-Temperature Hydrogen Adsorption/Desorption Thermodynamics Driven by Soft Vibration Modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woo, Sung-Jae; Lee, Eui-Sup; Yoon, Mina

2013-01-01

It is widely accepted that room-temperature hydrogen storage on nanostructured or porous materials requires enhanced dihydrogen adsorption. In this work we reveal that room-temperature hydrogen storage is possible not only by the enhanced adsorption, but also by making use of the vibrational free energy from soft vibration modes. These modes exist for example in the case of metallo-porphyrin-incorporated graphenes (M-PIGs) with out-of-plane ( buckled ) metal centers. There, the in-plane potential surfaces are flat because of multiple-orbital-coupling between hydrogen molecules and the buckled-metal centers. This study investigates the finite-temperature adsorption/desorption thermodynamics of hydrogen molecules adsorbed on M-PIGs by employing first-principlesmore » total energy and vibrational spectrum calculations. Our results suggest that the current design strategy for room-temperature hydrogen storage materials should be modified by explicitly taking finite-temperature vibration thermodynamics into account.« less

Mechanical properties of several nickel alloys in hydrogen at elevated temperatures

NASA Technical Reports Server (NTRS)

Warren, J. R.; Harris, J. A., Jr.; Vanwanderham, M. C.

1977-01-01

Tests were performed to determine low cycle fatigue and crack growth rate properties of one iron-base and two forms of one cast nickel-base alloy. The alloys were tested in various forms and/or heat-treat conditions that are proposed for use in a high-pressure hydrogen or a hydrogen-water vapor environment. Some general conclusions can be made comparing the results of tests in a hydrogen environment with those in a hydrogen-water vapor environment. The hydrogen-water vapor environment caused a 50 percent average reduction in fatigue life, indicating extreme degradation when compared with tests conducted in air, for Incoloy 903 at 1033 K (1400 F). Crack growth rates increased significantly for all materials with increasing test temperature. A very significant increase (three orders of magnitude) in crack growth rate occurred for Incoloy 903 tested in the hydrogen-water vapor environment when compared with testing done in hydrogen along at 922 K (1200 F).

High capacity hydrogen storage nanocomposite materials

DOEpatents

Zidan, Ragaiy; Wellons, Matthew S.

2017-12-12

A novel hydrogen absorption material is provided comprising a mixture of a lithium hydride with a fullerene. The subsequent reaction product provides for a hydrogen storage material which reversibly stores and releases hydrogen at temperatures of about 270.degree. C.

High capacity hydrogen storage nanocomposite materials

DOEpatents

Zidan, Ragaiy; Wellons, Matthew S

2015-02-03

A novel hydrogen absorption material is provided comprising a mixture of a lithium hydride with a fullerene. The subsequent reaction product provides for a hydrogen storage material which reversibly stores and releases hydrogen at temperatures of about 270.degree. C.

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

NASA Technical Reports Server (NTRS)

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.

Hydrogen-atmosphere induction furnace has increased temperature range

NASA Technical Reports Server (NTRS)

Caves, R. M.; Gresslin, C. H.

1966-01-01

Improved hydrogen-atmosphere induction furnace operates at temperatures up to 5,350 deg F. The furnace heats up from room temperature to 4,750 deg F in 30 seconds and cools down to room temperature in 2 minutes.

Low-temperature hydrogen production from water and methanol using Pt/α-MoC catalysts

NASA Astrophysics Data System (ADS)

Lin, Lili; Zhou, Wu; Gao, Rui; Yao, Siyu; Zhang, Xiao; Xu, Wenqian; Zheng, Shijian; Jiang, Zheng; Yu, Qiaolin; Li, Yong-Wang; Shi, Chuan; Wen, Xiao-Dong; Ma, Ding

2017-03-01

Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM). This method requires less energy, and the simpler and more compact device design allows direct integration into PEMFC stacks. There remains, however, the need for an efficient APRM catalyst. Here we report that platinum (Pt) atomically dispersed on α-molybdenum carbide (α-MoC) enables low-temperature (150-190 degrees Celsius), base-free hydrogen production through APRM, with an average turnover frequency reaching 18,046 moles of hydrogen per mole of platinum per hour. We attribute this exceptional hydrogen production—which far exceeds that of previously reported low-temperature APRM catalysts—to the outstanding ability of α-MoC to induce water dissociation, and to the fact that platinum and α-MoC act in synergy to activate methanol and then to reform it.

Low-temperature hydrogen production from water and methanol using Pt/α-MoC catalysts.

PubMed

Lin, Lili; Zhou, Wu; Gao, Rui; Yao, Siyu; Zhang, Xiao; Xu, Wenqian; Zheng, Shijian; Jiang, Zheng; Yu, Qiaolin; Li, Yong-Wang; Shi, Chuan; Wen, Xiao-Dong; Ma, Ding

2017-04-06

Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM). This method requires less energy, and the simpler and more compact device design allows direct integration into PEMFC stacks. There remains, however, the need for an efficient APRM catalyst. Here we report that platinum (Pt) atomically dispersed on α-molybdenum carbide (α-MoC) enables low-temperature (150-190 degrees Celsius), base-free hydrogen production through APRM, with an average turnover frequency reaching 18,046 moles of hydrogen per mole of platinum per hour. We attribute this exceptional hydrogen production-which far exceeds that of previously reported low-temperature APRM catalysts-to the outstanding ability of α-MoC to induce water dissociation, and to the fact that platinum and α-MoC act in synergy to activate methanol and then to reform it.

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

DOEpatents

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.

The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature aqueous environment

NASA Astrophysics Data System (ADS)

Xu, Jian; Shoji, Tetsuo

2015-06-01

The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature water is studied by in situ monitoring corrosion potential (Ecorr), contact electric resistance (CER) and electrochemical impedance measurements (EIS), and ex situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The Ecorr and film resistance show large change when the environment is changed from hydrogenated water to oxygenated water and changeable with changing environment while the morphology and composition only show obvious distinction in the first cycle. The main factor controlling the electric/electrochemical properties of the oxide film is Ecorr.

Investigation of hydrogen bubbles behavior in tungsten by high-flux hydrogen implantation

NASA Astrophysics Data System (ADS)

Zhao, Jiangtao; Meng, Xuan; Guan, Xingcai; Wang, Qiang; Fang, Kaihong; Xu, Xiaohui; Lu, Yongkai; Gao, Jun; Liu, Zhenlin; Wang, Tieshan

2018-05-01

Hydrogen isotopes retention and bubbles formation are critical issues for tungsten as plasma-facing material in future fusion reactors. In this work, the formation and growing up behavior of hydrogen bubbles in tungsten were investigated experimentally. The planar TEM samples were implanted by 6.0keV hydrogens to a fluence of 3.38 ×1018 H ṡ cm-2 at room temperature, and well-defined hydrogen bubbles were observed by TEM. It was demonstrated that hydrogen bubbles formed when exposed to a fluence of 1.5 ×1018 H ṡ cm-2 , and the hydrogen bubbles grew up with the implantation fluence. In addition, the bubbles' size appeared larger with higher beam flux until saturated at a certain flux, even though the total fluence was kept the same. Finally, in order to understand the thermal annealing effect on the bubbles behavior, hydrogen-implanted samples were annealed at 400, 600, 800, and 1000 °C for 3 h. It was obvious that hydrogen bubbles' morphology changed at temperatures higher than 800 °C.

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, Stanley E.

1998-01-01

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiberoptic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences.

Effects of high-temperature hydrogenation treatment on sliding friction and wear behavior of carbide-derived carbon films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erdemir, A.; Kovalchenko, A.; McNallan, M. J.

2004-01-01

In this study, we investigated the effects of a high-temperature hydrogenation treatment on the sliding friction and wear behavior of nanostructured carbide-derived carbon (CDC) films in dry nitrogen and humid air environments. These films are produced on the surfaces of silicon carbide substrates by reacting the carbide phase with chlorine or chlorine-hydrogen gas mixtures at 1000 to 1100 C in a sealed tube furnace. The typical friction coefficients of CDC films in open air are in the range of 0.2 to 0.25, but in dry nitrogen, the friction coefficients are 0.15. In an effort to achieve lower friction on CDCmore » films, we developed and used a special hydrogenation process that was proven to be very effective in lowering friction of CDC films produced on SiC substrates. Specifically, the films that were post-hydrogen-treated exhibited friction coefficients as low as 0.03 in dry nitrogen, while the friction coefficients in humid air were 0.2. The wear of Si{sub 3}N{sub 4} counterface balls was hard to measure after the tests, while shallow wear tracks had formed on CDC films on SiC disks. Detailed mechanical and structural characterizations of the CDC films and sliding contact surfaces were done using a series of analytical techniques and these findings were correlated with the friction and wear behaviors of as-produced and hydrogen-treated CDC films.« less

Liquid Fuel Production from Biomass via High Temperature Steam Electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant L. Hawkes; Michael G. McKellar

2009-11-01

A process model of syngas production using high temperature electrolysis and biomass gasification is presented. Process heat from the biomass gasifier is used to heat steam for the hydrogen production via the high temperature steam electrolysis process. Hydrogen from electrolysis allows a high utilization of the biomass carbon for syngas production. Oxygen produced form the electrolysis process is used to control the oxidation rate in the oxygen-fed biomass gasifier. Based on the gasifier temperature, 94% to 95% of the carbon in the biomass becomes carbon monoxide in the syngas (carbon monoxide and hydrogen). Assuming the thermal efficiency of the powermore » cycle for electricity generation is 50%, (as expected from GEN IV nuclear reactors), the syngas production efficiency ranges from 70% to 73% as the gasifier temperature decreases from 1900 K to 1500 K. Parametric studies of system pressure, biomass moisture content and low temperature alkaline electrolysis are also presented.« less

Mixture including hydrogen and hydrocarbon having pressure-temperature stability

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

Mixture including hydrogen and hydrocarbon having pressure-temperature stability

DOEpatents

Mao, Wendy L [Washington, DC; Mao, Ho-Kwang [Washington, DC

2009-08-18

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

Reasons for high-temperature superconductivity in the electron-phonon system of hydrogen sulfide

NASA Astrophysics Data System (ADS)

Degtyarenko, N. N.; Mazur, E. A.

2015-08-01

We have calculated the electron and phonon spectra, as well as the densities of the electron and phonon states, of the stable orthorhombic structure of hydrogen sulfide SH2 in the pressure interval 100-180 GPa. It is found that at a pressure of 175 GPa, a set of parallel planes of hydrogen atoms is formed due to a structural modification of the unit cell under pressure with complete accumulation of all hydrogen atoms in these planes. As a result, the electronic properties of the system become quasi-two-dimensional. We have also analyzed the collective synphase and antiphase vibrations of hydrogen atoms in these planes, leading to the occurrence of two high-energy peaks in the phonon density of states.

Copper Alloy For High-Temperature Uses

NASA Technical Reports Server (NTRS)

Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

1994-01-01

Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, S.E.

1998-07-21

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiber optic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences. 3 figs.

Reasons for high-temperature superconductivity in the electron–phonon system of hydrogen sulfide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Degtyarenko, N. N.; Mazur, E. A., E-mail: eugen-masur@mail.ru

We have calculated the electron and phonon spectra, as well as the densities of the electron and phonon states, of the stable orthorhombic structure of hydrogen sulfide SH{sub 2} in the pressure interval 100–180 GPa. It is found that at a pressure of 175 GPa, a set of parallel planes of hydrogen atoms is formed due to a structural modification of the unit cell under pressure with complete accumulation of all hydrogen atoms in these planes. As a result, the electronic properties of the system become quasi-two-dimensional. We have also analyzed the collective synphase and antiphase vibrations of hydrogen atomsmore » in these planes, leading to the occurrence of two high-energy peaks in the phonon density of states.« less

Nuclear Microprobe using Elastic Recoil Detection (ERD) for Hydrogen Profiling in High Temperature Protonic Conductors

NASA Technical Reports Server (NTRS)

Berger, Pascal; Sayir, Ali; Berger, Marie-Helene

2004-01-01

The interaction between hydrogen and various high temperature protonic conductors (HTPC) has not been clearly understood due to poor densification and unreacted secondary phases. the melt-processing technique is used in producing fully dense simple SrCe(0.9)Y (0.10) O(3-delta) and complex Sr3Ca(1+x)Nb(2+x)O(9-delta) perovskites that can not be achieved by solid-state sintering. the possibilities of ion beam analysis have been investigated to quantify hydrogen distribution in HTPC perovskites subjected to water heat treatment. Nuclear microprobe technique is based on the interactions of a focused ion beam of MeV light ions (H-1, H-2, He-3, He-4,.) with the sample to be analyzed to determine local elemental concentrations at the cubic micrometer scale, the elastic recoil detection analysis technique (ERDA) has been carried out using He-4(+) microbeams and detecting the resulting recoil protons. Mappings of longitudinal sections of water treated SrCeO3 and Sr(Ca(1/3)Nb(2/3))O3 perovskites have been achieved, the water treatment strongly alters the surface of simple SrCe(0.9)Y(0.10)O(3-delta) perovskite. From Rutherford Back Scattering measurements (RBS), both Ce depletion and surface re-deposition is evidenced. the ERDA investigations on water treated Sr3Ca(1+x)Nb(2+x)O(9-delta) perovskite did not exhibit any spatial difference for the hydrogen incorporation from the surface to the centre. the amount of hydrogen incorporation for Sr3Ca(1+x)Nb(2+x)O(9-delta) was low and required further development of two less conventional techniques, ERDA in forward geometry and forward elastic diffusion H-1(p,p) H-1 with coincidence detection.

Processing Raman Spectra of High-Pressure Hydrogen Flames

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet; Kojima, Jun

2006-01-01

The Raman Code automates the analysis of laser-Raman-spectroscopy data for diagnosis of combustion at high pressure. On the basis of the theory of molecular spectroscopy, the software calculates the rovibrational and pure rotational Raman spectra of H2, O2, N2, and H2O in hydrogen/air flames at given temperatures and pressures. Given a set of Raman spectral data from measurements on a given flame and results from the aforementioned calculations, the software calculates the thermodynamic temperature and number densities of the aforementioned species. The software accounts for collisional spectral-line-broadening effects at pressures up to 60 bar (6 MPa). The line-broadening effects increase with pressure and thereby complicate the analysis. The software also corrects for spectral interference ("cross-talk") among the various chemical species. In the absence of such correction, the cross-talk is a significant source of error in temperatures and number densities. This is the first known comprehensive computer code that, when used in conjunction with a spectral calibration database, can process Raman-scattering spectral data from high-pressure hydrogen/air flames to obtain temperatures accurate to within 10 K and chemical-species number densities accurate to within 2 percent.

High temperature ceramic-tubed reformer

NASA Astrophysics Data System (ADS)

Williams, Joseph J.; Rosenberg, Robert A.; McDonough, Lane J.

1990-03-01

The overall objective of the HiPHES project is to develop an advanced high-pressure heat exchanger for a convective steam/methane reformer. The HiPHES steam/methane reformer is a convective, shell and tube type, catalytic reactor. The use of ceramic tubes will allow reaction temperature higher than the current state-of-the-art outlet temperatures of about 1600 F using metal tubes. Higher reaction temperatures increase feedstock conversion to synthesis gas and reduce energy requirements compared to currently available radiant-box type reformers using metal tubes. Reforming of natural gas is the principal method used to produce synthesis gas (primarily hydrogen and carbon monoxide, H2 and CO) which is used to produce hydrogen (for refinery upgrading), methanol, as well as several other important materials. The HiPHES reformer development is an extension of Stone and Webster's efforts to develop a metal-tubed convective reformer integrated with a gas turbine cycle.

A new high strength alloy for hydrogen fueled propulsion systems

NASA Technical Reports Server (NTRS)

Mcpherson, W. B.

1986-01-01

This paper describes the development of a high-strength alloy (1241 MPa ultimate and 1103 MPa yield, with little or no degradation in hydrogen) for application in advanced hydrogen-fueled rocket engines. Various compositions of the Fe-Ni-Co-Cr system with elemental additions of Cb, Ti and Al are discussed. After processing, notched tensile specimens were tested in 34.5-MPa hydrogen at room temperature, as the main screening test. The H2/air notch tensile ratio was used as the selection/rejection criterion. The most promising alloys are discussed.

Nanoporous Ni with High Surface Area for Potential Hydrogen Storage Application.

PubMed

Zhou, Xiaocao; Zhao, Haibo; Fu, Zhibing; Qu, Jing; Zhong, Minglong; Yang, Xi; Yi, Yong; Wang, Chaoyang

2018-06-01

Nanoporous metals with considerable specific surface areas and hierarchical pore structures exhibit promising applications in the field of hydrogen storage, electrocatalysis, and fuel cells. In this manuscript, a facile method is demonstrated for fabricating nanoporous Ni with a high surface area by using SiO₂ aerogel as a template, i.e., electroless plating of Ni into an SiO₂ aerogel template followed by removal of the template at moderate conditions. The effects of the prepared conditions, including the electroless plating time, temperature of the structure, and the magnetism of nanoporous Ni are investigated in detail. The resultant optimum nanoporous Ni with a special 3D flower-like structure exhibited a high specific surface area of about 120.5 m²/g. The special nanoporous Ni exhibited a promising prospect in the field of hydrogen storage, with a hydrogen capacity of 0.45 wt % on 4.5 MPa at room temperature.

Hydrogenation apparatus

DOEpatents

Friedman, Joseph [Encino, CA; Oberg, Carl L [Canoga Park, CA; Russell, Larry H [Agoura, CA

1981-01-01

Hydrogenation reaction apparatus comprising a housing having walls which define a reaction zone and conduits for introducing streams of hydrogen and oxygen into the reaction zone, the oxygen being introduced into a central portion of the hydrogen stream to maintain a boundary layer of hydrogen along the walls of the reaction zone. A portion of the hydrogen and all of the oxygen react to produce a heated gas stream having a temperature within the range of from 1100.degree. to 1900.degree. C., while the boundary layer of hydrogen maintains the wall temperature at a substantially lower temperature. The heated gas stream is introduced into a hydrogenation reaction zone and provides the source of heat and hydrogen for a hydrogenation reaction. There also is provided means for quenching the products of the hydrogenation reaction. The present invention is particularly suitable for the hydrogenation of low-value solid carbonaceous materials to provide high yields of more valuable liquid and gaseous products.

Hydrogenation apparatus

DOEpatents

Friedman, J.; Oberg, C. L.; Russell, L. H.

1981-06-23

Hydrogenation reaction apparatus is described comprising a housing having walls which define a reaction zone and conduits for introducing streams of hydrogen and oxygen into the reaction zone, the oxygen being introduced into a central portion of the hydrogen stream to maintain a boundary layer of hydrogen along the walls of the reaction zone. A portion of the hydrogen and all of the oxygen react to produce a heated gas stream having a temperature within the range of from 1,100 to 1,900 C, while the boundary layer of hydrogen maintains the wall temperature at a substantially lower temperature. The heated gas stream is introduced into a hydrogenation reaction zone and provides the source of heat and hydrogen for a hydrogenation reaction. There also is provided means for quenching the products of the hydrogenation reaction. The present invention is particularly suitable for the hydrogenation of low-value solid carbonaceous materials to provide high yields of more valuable liquid and gaseous products. 2 figs.

Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Wehrmeyer, Joseph A.; Osborne, Robin J.; Trinh, Huu P.; Turner, James (Technical Monitor)

2001-01-01

Optically accessible, high pressure, hot fire test articles are available at NASA Marshall for use in development of advanced rocket engine propellant injectors. Single laser-pulse ultraviolet (UV) Raman spectroscopy has been used in the past in these devices for analysis of high pressure H2- and CH4-fueled combustion, but relies on an independent pressure measurement in order to provide temperature information. A variation of UV Raman (High Resolution Hydrogen Raman Spectroscopy) is under development and will allow temperature measurement without the need for an independent pressure measurement, useful for flows where local pressure may not be accurately known. The technique involves the use of a spectrometer with good spectral resolution, requiring a small entrance slit for the spectrometer. The H2 Raman spectrum, when created by a narrow linewidth laser source and obtained from a good spectral resolution spectrograph, has a spectral shape related to temperature. By best-fit matching an experimental spectrum to theoretical spectra at various temperatures, a temperature measurement is obtained. The spectral model accounts for collisional narrowing, collisional broadening, Doppler broadening, and collisional line shifting of each Raman line making up the H2 Stokes vibrational Q-branch spectrum. At pressures from atmospheric up to those associated with advanced preburner components (5500 psia), collisional broadening though present does not cause significant overlap of the Raman lines, allowing high resolution H2 Raman to be used for temperature measurements in plumes and in high pressure test articles. Experimental demonstrations of the technique are performed for rich H2-air flames at atmospheric pressure and for high pressure, 300 K H2-He mixtures. Spectrometer imaging quality is identified as being critical for successful implementation of technique.

Fundamental Pathways for the Adsorption and Transport of Hydrogen on TiO2 Surfaces: Origin for Effective Sensing at about Room Temperature.

PubMed

Wang, Zhuo; Xia, Xiaohong; Guo, Meilan; Shao, Guosheng

2016-12-28

Effective detection of hydrogen at lowered temperature is highly desirable in promoting safety in using this abundant gas as a clean energy source. Through first-principle calculations in the framework of density functional theory, we find that the high-energy (002) surface for rutile TiO 2 is significantly more effective in adsorbing hydrogen atoms through dissociating hydrogen molecules. The pathways for the dissociation of hydrogen molecules and sequential migration of hydrogen atoms are identified through searching along various transitional states. Pathways of low potential barriers indicate promise for hydrogen sensing, even close to room temperature. This has been proven through sensors made of thin films of well-aligned rutile nanorods, wherein the high-energy (002) surface dictates the top surface of the active layer of the sensors.

Conductivity Analysis of Membranes for High-Temperature PEMFC Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, R.; Turner, J.A.

2005-01-01

Low-temperature operation requirements for per-fluorinated membranes are one factor that limits the viability of current fuel cell technology for transportation and other uses. Because of this, high-temperature membrane materials are being researched. The protonic conductivity of organic/inorganic hybrid composites, Nafion® analog material, and heteropoly acid doped Nafion membranes were studied using a BekkTech® conductivity test cell as a hydrogen pump. The goal was to find a high-temperature membrane with sufficient enough conductive properties to replace the currently implemented low-temperature membranes, such as Nafion. Four-point conductivity measurements were taken using a hydrogen pump experiment. Results showed that one of the organic/inorganicmore » membranes that we tested had similar protonic conductivity to Nafion. Nafion analog membranes were shown to have similar to slightly better conductivity than Nafion at high-temperatures. However, like Nafion, performance dropped upon dehydration of the membrane at higher temperatures. Of the heteropoly acid doped Nafion membranes studied, silicotungstic acid was found to be, overall, the most promising for use as a dopant.« less

Caution on the use of NBS 30 biotite for hydrogen-isotope measurements with on-line high-temperature conversion systems

USGS Publications Warehouse

Qi, Haiping; Coplen, Tyler B.; Olack, Gerard; Vennemann, Torsten W.

2014-01-01

RATIONALEThe supply of NBS 30 biotite is nearly exhausted. During measurements of NBS 30 and potential replacements, reproducible δ2HVSMOW-SLAP values could not be obtained by three laboratories using high-temperature conversion (HTC) systems. The cause of this issue has been investigated using the silver-tube technique for hydrogen-isotope measurements of water.METHODSThe δ2HVSMOW-SLAP values of NBS 30 biotite, other biotites, muscovites, and kaolinite with different particle sizes, along with IAEA-CH-7 polyethylene, and reference waters and NBS 22 oil that were sealed in silver-tube segments, were measured. The effect of absorbed water on mineral surfaces was investigated with waters both enriched and depleted in 2H. The quantitative conversion of hydrogen from biotite into gaseous hydrogen as a function of mass and particle size was also investigated.RESULTSThe δ2HVSMOW-SLAP values of NBS 30 obtained by three laboratories were as much as 21 ‰ too high compared with the accepted value of −65.7 ‰, determined by conventional off-line measurements. The experiments showed a strong correlation between grain size and the δ2HVSMOW-SLAP value of NBS 30 biotite, but not of biotites with lower iron content. The δ2HVSMOW-SLAP values of NBS 30 as a function of particle size show a clear trend toward −65.7 ‰ with finer grain size.CONCLUSIONSDetermination of the δ2HVSMOW-SLAP values of hydrous minerals and of NBS 30 biotite by on-line HTC systems coupled to isotope-ratio mass spectrometers may be unreliable because hydrogen in this biotite may not be converted quantitatively into molecular hydrogen. Extreme caution in the use and interpretation of δ2HVSMOW-SLAP on-line measurements of hydrous minerals is recommended.

High-temperature sorbent method for removal of sulfur-containing gases from gaseous mixtures

DOEpatents

Young, J.E.; Jalan, V.M.

1982-07-07

A copper oxide-zinc oxide mixture is used as a sorbent for removing hydrogen sulfide and other sulfur containing gases at high temperatures from a gaseous fuel mixture. This high-temperature sorbent is especially useful for preparing fuel gases for high temperature fuel cells. The copper oxide is initially reduced in a preconditioning step to elemental copper and is present in a highly dispersed state throughout the zinc oxide which serves as a support as well as adding to the sulfur sorbtion capacity. The spent sorbent is regenerated by high-temperature treatment with an air fuel, air steam mixture followed by hydrogen reduction to remove and recover the sulfur.

High-temperature sorbent method for removal of sulfur containing gases from gaseous mixtures

DOEpatents

Young, J.E.; Jalan, V.M.

1984-06-19

A copper oxide-zinc oxide mixture is used as a sorbent for removing hydrogen sulfide and other sulfur containing gases at high temperatures from a gaseous fuel mixture. This high-temperature sorbent is especially useful for preparing fuel gases for high temperature fuel cells. The copper oxide is initially reduced in a preconditioning step to elemental copper and is present in a highly dispersed state throughout the zinc oxide which serves as a support as well as adding to the sulfur sorption capacity. The spent sorbent is regenerated by high-temperature treatment with an air fuel, air steam mixture followed by hydrogen reduction to remove and recover the sulfur.

High-temperature sorbent method for removal of sulfur containing gases from gaseous mixtures

DOEpatents

Young, John E.; Jalan, Vinod M.

1984-01-01

A copper oxide-zinc oxide mixture is used as a sorbent for removing hydrogen sulfide and other sulfur containing gases at high temperatures from a gaseous fuel mixture. This high-temperature sorbent is especially useful for preparing fuel gases for high temperature fuel cells. The copper oxide is initially reduced in a preconditioning step to elemental copper and is present in a highly dispersed state throughout the zinc oxide which serves as a support as well as adding to the sulfur sorption capacity. The spent sorbent is regenerated by high-temperature treatment with an air fuel, air steam mixture followed by hydrogen reduction to remove and recover the sulfur.

High-temperature molten salt solar thermal systems

NASA Astrophysics Data System (ADS)

Copeland, R. J.; Leach, J. W.; Stern, G.

Conceptual designs of a solar thermal central receiver and a thermal storage subsystem were analyzed to estimate thermal losses and to assess the economics of high-temperature applications with molten salt transport fluids. Modifications to a receiver design being developed by the Martin Marietta Corporation were studied to investigate possible means for improving efficiency at high temperatures. Computations were made based on conceptual design of internally insulated high temperature storage tanks to estimate cost and performance. A study of a potential application of the system for thermochemical production of hydrogen indicates that thermal storage at 1100 C will be economically attractive.

Comparison of gate and drain current detection of hydrogen at room temperature with AlGaN /GaN high electron mobility transistors

NASA Astrophysics Data System (ADS)

Wang, Hung-Ta; Kang, B. S.; Ren, F.; Fitch, R. C.; Gillespie, J. K.; Moser, N.; Jessen, G.; Jenkins, T.; Dettmer, R.; Via, D.; Crespo, A.; Gila, B. P.; Abernathy, C. R.; Pearton, S. J.

2005-10-01

Pt-gated AlGaN /GaN high electron mobility transistors can be used as room-temperature hydrogen gas sensors at hydrogen concentrations as low as 100ppm. A comparison of the changes in drain and gate current-voltage (I-V) characteristics with the introduction of 500ppm H2 into the measurement ambient shows that monitoring the change in drain-source current provides a wider gate voltage operation range for maximum detection sensitivity and higher total current change than measuring the change in gate current. However, over a narrow gate voltage range, the relative sensitivity of detection by monitoring the gate current changes is up to an order of magnitude larger than that of drain-source current changes. In both cases, the changes are fully reversible in <2-3min at 25°C upon removal of the hydrogen from the ambient.

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

PubMed

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.

Method for charging a hydrogen getter

DOEpatents

Tracy, C. Edwin; Keyser, Matthew A.; Benson, David K.

1998-01-01

A method for charging a sample of either a permanent or reversible getter material with a high concentration of hydrogen while maintaining a base pressure below 10.sup.-4 torr at room temperature involves placing the sample of hydrogen getter material in a chamber, activating the sample of hydrogen getter material, overcharging the sample of getter material through conventional charging techniques to a high concentration of hydrogen, and then subjecting the sample of getter material to a low temperature vacuum bake-out process. Application of the method results in a reversible hydrogen getter which is highly charged to maximum capacities of hydrogen and which concurrently exhibits minimum hydrogen vapor pressures at room temperatures.

Method for charging a hydrogen getter

DOEpatents

Tracy, C.E.; Keyser, M.A.; Benson, D.K.

1998-09-15

A method for charging a sample of either a permanent or reversible getter material with a high concentration of hydrogen while maintaining a base pressure below 10{sup {minus}4} torr at room temperature involves placing the sample of hydrogen getter material in a chamber, activating the sample of hydrogen getter material, overcharging the sample of getter material through conventional charging techniques to a high concentration of hydrogen, and then subjecting the sample of getter material to a low temperature vacuum bake-out process. Application of the method results in a reversible hydrogen getter which is highly charged to maximum capacities of hydrogen and which concurrently exhibits minimum hydrogen vapor pressures at room temperatures. 9 figs.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lübben, Jens; Volkmann, Christian; Grabowsky, Simon

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 thismore » 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.« less

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

NASA Technical Reports Server (NTRS)

Eliezer, D.; Nelson, H. G.

1978-01-01

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

Superconducting H5S2 phase in sulfur-hydrogen system under high-pressure

NASA Astrophysics Data System (ADS)

Ishikawa, Takahiro; Nakanishi, Akitaka; Shimizu, Katsuya; Katayama-Yoshida, Hiroshi; Oda, Tatsuki; Suzuki, Naoshi

2016-03-01

Recently, hydrogen sulfide was experimentally found to show the high superconducting critical temperature (Tc) under high-pressure. The superconducting Tc shows 30-70 K in pressure range of 100-170 GPa (low-Tc phase) and increases to 203 K, which sets a record for the highest Tc in all materials, for the samples annealed by heating it to room temperature at pressures above 150 GPa (high-Tc phase). Here we present a solid H5S2 phase predicted as the low-Tc phase by the application of the genetic algorithm technique for crystal structure searching and first-principles calculations to sulfur-hydrogen system under high-pressure. The H5S2 phase is thermodynamically stabilized at 110 GPa, in which asymmetric hydrogen bonds are formed between H2S and H3S molecules. Calculated Tc values show 50-70 K in pressure range of 100-150 GPa within the harmonic approximation, which can reproduce the experimentally observed low-Tc phase. These findings give a new aspect of the excellent superconductivity in compressed sulfur-hydrogen system.

Superconducting H5S2 phase in sulfur-hydrogen system under high-pressure

PubMed Central

Ishikawa, Takahiro; Nakanishi, Akitaka; Shimizu, Katsuya; Katayama-Yoshida, Hiroshi; Oda, Tatsuki; Suzuki, Naoshi

2016-01-01

Recently, hydrogen sulfide was experimentally found to show the high superconducting critical temperature (Tc) under high-pressure. The superconducting Tc shows 30–70 K in pressure range of 100–170 GPa (low-Tc phase) and increases to 203 K, which sets a record for the highest Tc in all materials, for the samples annealed by heating it to room temperature at pressures above 150 GPa (high-Tc phase). Here we present a solid H5S2 phase predicted as the low-Tc phase by the application of the genetic algorithm technique for crystal structure searching and first-principles calculations to sulfur-hydrogen system under high-pressure. The H5S2 phase is thermodynamically stabilized at 110 GPa, in which asymmetric hydrogen bonds are formed between H2S and H3S molecules. Calculated Tc values show 50–70 K in pressure range of 100–150 GPa within the harmonic approximation, which can reproduce the experimentally observed low-Tc phase. These findings give a new aspect of the excellent superconductivity in compressed sulfur-hydrogen system. PMID:26983593

Thermodynamic analysis of chemical stability of ceramic materials in hydrogen-containing atmospheres at high temperatures

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1990-01-01

The chemical stability of several ceramic materials in hydrogen-containing environments was analyzed with thermodynamic considerations in mind. Equilibrium calculations were made as a function of temperature, moisture content, and total system pressure. The following ceramic materials were considered in this study: SiC, Si3N4, SiO2, Al2O3, mullite, ZrO2, Y2O3, CaO, MgO, BeO, TiB2, TiC, HfC, and ZrC. On the basis of purely thermodynamic arguments, upper temperature limits are suggested for each material for long-term use in H2-containing atmospheres.

Probing Hydrogen Diffusion under High Pressure

NASA Astrophysics Data System (ADS)

Bove, L. E.; Klotz, S.; Strassle, T.; Saitta, M.

2012-12-01

The study of the microscopic mechanism governing hydrogen and hydrogen-based liquids (as water, ammonia and methane) diffusion is crucial for a variety of scientific issues spanning most of natural sciences. As an example, characterizing hydrogen diffusion in a confined medium, like in porous systems or zeolites, is fundamental in problems relating to environment, hydrogen storage and industrial applications [1]. The presence of water diffusion in the minerals of the Earth's mantle have strong incidence on the processes governing volcanic eruptions and intermediate-depth seismicity. As last example, knowing in details the microscopic dynamics of hydrogen-based simple liquids under extreme conditions is essential in order to interpret observations and develop models of planet interiors [2]. On the other hand, water and other simple hydrogen-based liquids have always been key systems in the development of modern condensed-matter physics, because of their simple electronic structure and the peculiar properties deriving from the hydrogen-bond network. Their high compressibility and chemical reactivity have made these systems very challenging to study experimentally under static high P-T conditions. In the last few years, a large effort has been undertaken by several groups around the world [2] to extend the static and dynamic techniques to high temperatures and pressures, a program in which our group has been actively involved [3-6]. However, while the structure of water and other hydrogenated liquids of geological interest, is now known up to almost 20 GPa, the study of their transport properties greatly lags behind. We have recently developed a new large-volume gasket-anvil ensemble for the Paris-Edinburgh press based on a novel toroidal design [7], which allows to perform quasi elastic neutron scattering measurements on hydrogen based liquids up to one order of magnitude higher pressures (5 GPa) respect to what was achievable with standard methods [8]. The large

Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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.

Hydrogen Production and Delivery | Hydrogen and Fuel Cells | Hydrogen and

Science.gov Websites

degrees Celsius. Ultra-high temperatures are required for thermochemical reaction cycles to produce for the environmentally benign production of hydrogen. Very high reaction rates at these elevated temperatures give rise to very fast reaction rates, which significantly enhance production rates and more than

Metal Hydrides for High-Temperature Power Generation

DOE PAGES

Ronnebro, Ewa; Whyatt, Greg A.; Powell, Michael R.; ...

2015-08-10

Metal hydrides can be utilized for hydrogen storage and for thermal energy storage (TES) applications. By using TES with solar technologies, heat can be stored from sun energy to be used later which enables continuous power generation. We are developing a TES technology based on a dual-bed metal hydride system, which has a high-temperature (HT) metal hydride operating reversibly at 600-800°C to generate heat as well as a low-temperature (LT) hydride near room temperature that is used for hydrogen storage during sun hours until there is a need to produce electricity, such as during night time, a cloudy day, ormore » during peak hours. We proceeded from selecting a high-energy density, low-cost HT-hydride based on performance characterization on gram size samples, to scale-up to kilogram quantities and design, fabrication and testing of a 1.5kWh, 200kWh/m 3 bench-scale TES prototype based on a HT-bed of titanium hydride and a hydrogen gas storage instead of a LT-hydride. COMSOL Multiphysics was used to make performance predictions for cylindrical hydride beds with varying diameters and thermal conductivities. Based on experimental and modeling results, a bench-scale prototype was designed and fabricated and we successfully showed feasibility to meet or exceed all performance targets.« less

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

PubMed

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.

Predictions of glass transition temperature for hydrogen bonding biomaterials.

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Low Temperature Regenerators for Zero Boil-Off Liquid Hydrogen Pulse Tube Cryocoolers

NASA Technical Reports Server (NTRS)

Salerno, Louis J.; Kashani, Ali; Helvensteijn, Ben; Kittel, Peter; Arnoldm James O. (Technical Monitor)

2002-01-01

Recently, a great deal of attention has been focused on zero boil-off (ZBO) propellant storage as a means of minimizing the launch mass required for long-term exploration missions. A key component of ZBO systems is the cooler. Pulse tube coolers offer the advantage of zero moving mass at the cold head, and recent advances in lightweight, high efficiency cooler technology have paved the way for reliable liquid oxygen (LOx) temperature coolers to be developed which are suitable for flight ZBO systems. Liquid hydrogen (LH2) systems, however, are another matter. For ZBO liquid hydrogen systems, cooling powers of 1-5 watts are required at 20 K. The final development from tier for these coolers is to achieve high efficiency and reliability at lower operating temperatures. Most of the life-limiting issues of flight Stirling and pulse tube coolers are associated with contamination, drive mechanisms, and drive electronics. These problems are well in hand in the present generation coolers. The remaining efficiency and reliability issues reside with the low temperature regenerators. This paper will discuss advances to be made in regenerators for pulse tube LH2 ZBO coolers, present some historical background, and discuss recent progress in regenerator technology development using alloys of erbium.

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

NASA Astrophysics Data System (ADS)

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

2013-09-01

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.

Low-temperature hydrogen absorption into V and Nb metals from liquid hydrogen

NASA Astrophysics Data System (ADS)

Takata, H.; Ienaga, K.; Shiga, M.; Islam, Md S.; Inagaki, Y.; Tsujii, H.; Hashizume, K.; Kawae, T.

2018-03-01

We report experimental study on low-temperature hydrogen (H) absorption in vanadium (V) and niobium (Nb) nanocontacts below T = 20 K using a point-contact spectroscopy (PCS) technique. When a small bias voltage is applied between both sides of nanocontacts immersed in liquid H2, the differential conductance (dI/dV) and the second derivative (d2 I/dV 2) are changed from those for pure V and Nb nanocontacts. Further, the spectra approach to those for a high concentrated phase of H with increasing the bias voltage. The results indicate that in-situ investigation of H absorption process from liquid H2 is possible through dI/dV and d2 I/dV 2 measurements using the PCS technique.

High-power CW laser using hydrogen-fluorine reaction

NASA Technical Reports Server (NTRS)

Moynihan, P. I.

1975-01-01

Continuous-wave laser has been proposed based on reaction of hydrogen and fluorine. Hydrogen is produced by dissociation of hydrazine, which can be stored as liquid in light containers at room temperature.

Pressure and temperature fluctuation simulation of J-PARC cryogenic hydrogen system

NASA Astrophysics Data System (ADS)

Tatsumoto, H.; Ohtsu, K.; Aso, T.; Kawakami, Y.

2015-12-01

The J-PARC cryogenic hydrogen system provides supercritical cryogenic hydrogen to the moderators at a pressure of 1.5 MPa and temperature of 18 K and removes 3.8 kW of nuclear heat from the 1 MW proton beam operation. We prepared a heater for thermal compensation and an accumulator, with a bellows structure for volume control, to mitigate the pressure fluctuation caused by switching the proton beam on and off. In this study, a 1-D simulation code named DiSC-SH2 was developed to understand the propagation of pressure and temperature propagations through the hydrogen loop due to on and off switching of the proton beam. We confirmed that the simulated dynamic behaviors in the hydrogen loop for 300-kW and 500-kW proton beam operations agree well with the experimental data under the same conditions.

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

PubMed

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.

New insights into designing metallacarborane based room temperature hydrogen storage media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bora, Pankaj Lochan; Singh, Abhishek K.

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 chargemore » 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 H{sub 2} sorbent material with a 9 wt.% of reversible storage at ambient pressure and temperature.« less

Activation energy for diamond growth from the carbon-hydrogen gas system at low substrate temperatures

NASA Astrophysics Data System (ADS)

Stiegler, J.; Lang, T.; von Kaenel, Y.; Michler, J.; Blank, E.

1997-01-01

The growth kinetics of diamond films deposited at low substrate temperatures (600-400 °C) from the carbon-hydrogen gas system have been studied. When the substrate temperature alone was varied, independently of all other process parameters in the microwave plasma reactor, an activation energy in the order of 7 kcal/mol was observed. This value did not change with different carbon concentrations in hydrogen. It is supposed that growth kinetics in this temperature range are controlled by a single chemical reaction, probably the abstraction of surface bonded hydrogen by gas phase atomic hydrogen.

Controlling Hydrogen Embrittlement in Ultra-High Strength Steels

DTIC Science & Technology

2006-06-01

this tempering temperature, (5) finely distributed, partly coherent M2C (where M = 75 at.% Cr, 13 Fe and 12 Mo) in martensite , averaging 2 nm...states in a complex precipitation hardened martensitic microstructure and is susceptible to severe hydrogen embrittlement (HE) at threshold stress...repartitions to interstitial sites proximate to the highly stressed crack tip and, subsequently, may retrap at martensitic lath interfaces to produce substantial

Impact of temperature and substrate concentration on degradation rates of acetate, propionate and hydrogen and their links to microbial community structure.

PubMed

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.

Hydrogen adsorption and diffusion, and subcritical-crack growth in high strength steels and nickel base alloys

NASA Technical Reports Server (NTRS)

Wei, R. P.; Klier, K.; Simmons, G. W.; Chornet, E.

1973-01-01

Embrittlement, or the enhancement of crack growth by gaseous hydrogen in high strength alloys, is of primary interest in selecting alloys for various components in the space shuttle. Embrittlement is known to occur at hydrogen gas pressures ranging from fractions to several hundred atmospheres, and is most severe in the case of martensitic high strength steels. Kinetic information on subcritical crack growth in gaseous hydrogen is sparse at this time. Corroborative information on hydrogen adsorption and diffusion is inadequate to permit a clear determination of the rate controlling process and possible mechanism in hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Therefore, coordinated studies of the kinetics of crack growth, and adsorption and diffusion of hydrogen, using identical materials, have been initiated. Comparable conditions of temperature and pressure will be used in the chemical and mechanical experiments. Inconel 718 alloy and 18Ni(200) maraging steel have been selected for these studies. Results from these studies are expected to provide not only a better understanding of the gaseous hydrogen embrittlement phenomenon itself, but also fundamental information on hydrogen adsorption and diffusion, and crack growth information that can be used directly for design.

Confined high-pressure chemical deposition of hydrogenated amorphous silicon.

PubMed

Baril, Neil F; He, Rongrui; Day, Todd D; Sparks, Justin R; Keshavarzi, Banafsheh; Krishnamurthi, Mahesh; Borhan, Ali; Gopalan, Venkatraman; Peacock, Anna C; Healy, Noel; Sazio, Pier J A; Badding, John V

2012-01-11

Hydrogenated amorphous silicon (a-Si:H) is one of the most technologically important semiconductors. The challenge in producing it from SiH(4) precursor is to overcome a significant kinetic barrier to decomposition at a low enough temperature to allow for hydrogen incorporation into a deposited film. The use of high precursor concentrations is one possible means to increase reaction rates at low enough temperatures, but in conventional reactors such an approach produces large numbers of homogeneously nucleated particles in the gas phase, rather than the desired heterogeneous deposition on a surface. We report that deposition in confined micro-/nanoreactors overcomes this difficulty, allowing for the use of silane concentrations many orders of magnitude higher than conventionally employed while still realizing well-developed films. a-Si:H micro-/nanowires can be deposited in this way in extreme aspect ratio, small-diameter optical fiber capillary templates. The semiconductor materials deposited have ~0.5 atom% hydrogen with passivated dangling bonds and good electronic properties. They should be suitable for a wide range of photonic and electronic applications such as nonlinear optical fibers and solar cells. © 2011 American Chemical Society

The use of a very high temperature nuclear reactor in the manufacture of synthetic fuels

NASA Technical Reports Server (NTRS)

Farbman, G. H.; Brecher, L. E.

1976-01-01

The three parts of a program directed toward creating a cost-effective nuclear hydrogen production system are described. The discussion covers the development of a very high temperature nuclear reactor (VHTR) as a nuclear heat and power source capable of producing the high temperature needed for hydrogen production and other processes; the development of a hydrogen generation process based on water decomposition, which can utilize the outputs of the VHTR and be integrated with many different ultimate hydrogen consuming processes; and the evaluation of the process applications of the nuclear hydrogen systems to assess the merits and potential payoffs. It is shown that the use of VHTR for the manufacture of synthetic fuels appears to have a very high probability of making a positive contribution to meeting the nation's energy needs in the future.

Maglev system concept using 20-K high-temperature superconductors and hyperconductors

NASA Astrophysics Data System (ADS)

Hull, J. R.; He, Jianliang

A magnetically levitated high-speed ground transportation concept is proposed that uses high-temperature superconductors or hyperconductors, cooled by liquid hydrogen at 20 K, to provide levitation. An on-board hydrogen-powered turbine/generator provides electricity for propulsion by linear induction motors. The liquid hydrogen is used to cool the superconductors and the windings of the generator and motors before combusting in the turbine. The principal advantage of this system is the potential to greatly reduce the cost of the guideway, which is completely passive.

Metallic hydrogen

NASA Astrophysics Data System (ADS)

Silvera, Isaac F.; Dias, Ranga

2018-06-01

Hydrogen is the simplest and most abundant element in the Universe. There are two pathways for creating metallic hydrogen under high pressures. Over 80 years ago Wigner and Huntington predicted that if solid molecular hydrogen was sufficiently compressed in the T  =  0 K limit, molecules would dissociate to form atomic metallic hydrogen (MH). We have observed this transition at a pressure of 4.95 megabars. MH in this form has probably never existed on Earth or in the Universe; it may be a room temperature superconductor and is predicted to be metastable. If metastable it will have an important technological impact. Liquid metallic hydrogen can also be produced at intermediate pressures and high temperatures and is believed to make up ~90% of the planet Jupiter. We have observed this liquid–liquid transition, also known as the plasma phase transition, at pressures of ~1–2 megabar and temperatures ~1000–2000 K. However, in this paper we shall focus on the Wigner–Huntington transition. We shall discuss the methods used to observe metallic hydrogen at extreme conditions of static pressure in the laboratory, extending our understanding of the phase diagram of the simplest atom in the periodic table.

Low to high temperature energy conversion system

NASA Technical Reports Server (NTRS)

Miller, C. G. (Inventor)

1977-01-01

A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

Highly efficient hydrogen storage system based on ammonium bicarbonate/formate redox equilibrium over palladium nanocatalysts.

PubMed

Su, Ji; Yang, Lisha; Lu, Mi; Lin, Hongfei

2015-03-01

A highly efficient, reversible hydrogen storage-evolution process has been developed based on the ammonium bicarbonate/formate redox equilibrium over the same carbon-supported palladium nanocatalyst. This heterogeneously catalyzed hydrogen storage system is comparable to the counterpart homogeneous systems and has shown fast reaction kinetics of both the hydrogenation of ammonium bicarbonate and the dehydrogenation of ammonium formate under mild operating conditions. By adjusting temperature and pressure, the extent of hydrogen storage and evolution can be well controlled in the same catalytic system. Moreover, the hydrogen storage system based on aqueous-phase ammonium formate is advantageous owing to its high volumetric energy density. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bio-Fuel Production Assisted with High Temperature Steam Electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant Hawkes; James O'Brien; Michael McKellar

2012-06-01

Two hybrid energy processes that enable production of synthetic liquid fuels that are compatible with the existing conventional liquid transportation fuels infrastructure are presented. Using biomass as a renewable carbon source, and supplemental hydrogen from high-temperature steam electrolysis (HTSE), these two hybrid energy processes have the potential to provide a significant alternative petroleum source that could reduce dependence on imported oil. The first process discusses a hydropyrolysis unit with hydrogen addition from HTSE. Non-food biomass is pyrolyzed and converted to pyrolysis oil. The pyrolysis oil is upgraded with hydrogen addition from HTSE. This addition of hydrogen deoxygenates the pyrolysis oilmore » and increases the pH to a tolerable level for transportation. The final product is synthetic crude that could then be transported to a refinery and input into the already used transportation fuel infrastructure. The second process discusses a process named Bio-Syntrolysis. The Bio-Syntrolysis process combines hydrogen from HTSE with CO from an oxygen-blown biomass gasifier that yields syngas to be used as a feedstock for synthesis of liquid synthetic crude. Conversion of syngas to liquid synthetic crude, using a biomass-based carbon source, expands the application of renewable energy beyond the grid to include transportation fuels. It can also contribute to grid stability associated with non-dispatchable power generation. The use of supplemental hydrogen from HTSE enables greater than 90% utilization of the biomass carbon content which is about 2.5 times higher than carbon utilization associated with traditional cellulosic ethanol production. If the electrical power source needed for HTSE is based on nuclear or renewable energy, the process is carbon neutral. INL has demonstrated improved biomass processing prior to gasification. Recyclable biomass in the form of crop residue or energy crops would serve as the feedstock for this process. A

High Temperature Structural Foam

NASA Technical Reports Server (NTRS)

Weiser, Erik S.; Baillif, Faye F.; Grimsley, Brian W.; Marchello, Joseph M.

1997-01-01

The Aerospace Industry is experiencing growing demand for high performance polymer foam. The X-33 program needs structural foam insulation capable of retaining its strength over a wide range of environmental conditions. The High Speed Research Program has a need for low density core splice and potting materials. This paper reviews the state of the art in foam materials and describes experimental work to fabricate low density, high shear strength foam which can withstand temperatures from -220 C to 220 C. Commercially available polymer foams exhibit a wide range of physical properties. Some with densities as low as 0.066 g/cc are capable of co-curing at temperatures as high as 182 C. Rohacell foams can be resin transfer molded at temperatures up to 180 C. They have moduli of elasticity of 0.19 MPa, tensile strengths of 3.7 Mpa and compressive strengths of 3.6 MPa. The Rohacell foams cannot withstand liquid hydrogen temperatures, however Imi-Tech markets Solimide (trademark) foams which withstand temperatures from -250 C to 200 C, but they do not have the required structural integrity. The research activity at NASA Langley Research Center focuses on using chemical blowing agents to produce polyimide thermoplastic foams capable of meeting the above performance requirements. The combination of blowing agents that decompose at the minimum melt viscosity temperature together with plasticizers to lower the viscosity has been used to produce foams by both extrusion and oven heating. The foams produced exhibit good environmental stability while maintaining structural properties.

High spatial resolution fiber optical sensors for simultaneous temperature and chemical sensing for energy industries

NASA Astrophysics Data System (ADS)

Yan, Aidong; Huang, Sheng; Li, Shuo; Zaghloul, Mohamed; Ohodnicki, Paul; Buric, Michael; Chen, Kevin P.

2017-05-01

This paper demonstrates optical fibers as high-temperature sensor platforms. Through engineering and onfiber integration of functional metal oxide sensory materials, we report the development of an integrated sensor solution to perform temperature and chemical measurements for high-temperature energy applications. Using the Rayleigh optical frequency domain reflectometry (OFDR) distributed sensing scheme, the temperature and hydrogen concentration were measured along the fiber. To overcome the weak Rayleighbackscattering intensity exhibited by conventional optical fibers, an ultrafast laser was used to enhance the Rayleigh scattering by a direct laser writing method. Using the Rayleigh-enhanced fiber as sensor platform, both temperature and hydrogen reaction were monitored at high temperature up to 750°C with 4-mm spatial resolution.

Influence of hydrogen effusion from hydrogenated silicon nitride layers on the regeneration of boron-oxygen related defects in crystalline silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilking, S., E-mail: Svenja.Wilking@uni-konstanz.de; Ebert, S.; Herguth, A.

The degradation effect boron doped and oxygen-rich crystalline silicon materials suffer from under illumination can be neutralized in hydrogenated silicon by the application of a regeneration process consisting of a combination of slightly elevated temperature and carrier injection. In this paper, the influence of variations in short high temperature steps on the kinetics of the regeneration process is investigated. It is found that hotter and longer firing steps allowing an effective hydrogenation from a hydrogen-rich silicon nitride passivation layer result in an acceleration of the regeneration process. Additionally, a fast cool down from high temperature to around 550 °C seems tomore » be crucial for a fast regeneration process. It is suggested that high cooling rates suppress hydrogen effusion from the silicon bulk in a temperature range where the hydrogenated passivation layer cannot release hydrogen in considerable amounts. Thus, the hydrogen content of the silicon bulk after the complete high temperature step can be increased resulting in a faster regeneration process. Hence, the data presented here back up the theory that the regeneration process might be a hydrogen passivation of boron-oxygen related defects.« less

Rotational relaxation of molecular hydrogen at moderate temperatures

NASA Technical Reports Server (NTRS)

Sharma, S. P.

1994-01-01

Using a coupled rotation-vibration-dissociation model the rotational relaxation times for molecular hydrogen as a function of final temperature (500-5000 K), in a hypothetical scenario of sudden compression, are computed. The theoretical model is based on a master equation solver. The bound-bound and bound-free transition rates have been computed using a quasiclassical trajectory method. A review of the available experimental data on the rotational relaxation of hydrogen is presented, with a critical overview of the method of measurements and data reduction, including the sources of errors. These experimental data are then compared with the computed results.

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

NASA Astrophysics Data System (ADS)

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

Surface Treatment of Plastic Substrates using Atomic Hydrogen Generated on Heated Tungsten Wire at Low Temperatures

NASA Astrophysics Data System (ADS)

Heya, Akira; Matsuo, Naoto

2007-06-01

The surface properties of a plastic substrate were changed by a novel surface treatment called atomic hydrogen annealing (AHA). In this method, a plastic substrate was exposed to atomic hydrogen generated by cracking hydrogen molecules on heated tungsten wire. For the substrate, surface roughness was increased and halogen elements (F and Cl) were selectively etched by AHA. AHA was useful for pretreatment before film deposition on a plastic substrate because the changes in surface state relate to adhesion improvement. It is concluded that this method is a promising technique for preparing high-performance plastic substrates at low temperatures.

Method for determining hydrogen mobility as a function of temperature in superconducting niobium cavities

DOEpatents

May, Robert [Virginia Beach, VA

2008-03-11

A method for determining the mobility of hydrogen as a function of temperature in superconducting niobium cavities comprising: 1) heating a cavity under test to remove free hydrogen; 2) introducing hydrogen-3 gas into the cavity; 3) cooling the cavity to allow absorption of hydrogen-3; and 4) measuring the amount of hydrogen-3 by: a) cooling the cavity to about 4.degree. K while flowing a known and regulated amount of inert carrier gas such as argon or helium into the cavity; b) allowing the cavity to warm at a stable rate from 4.degree. K to room temperature as it leaves the chamber; and c) directing the exit gas to an ion chamber radiation detector.

The coexistence temperature of hydrogen clathrates: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Luis, D. P.; Romero-Ramirez, I. E.; González-Calderón, A.; López-Lemus, J.

2018-03-01

Extensive molecular dynamics simulations in the equilibrium isobaric-isothermal (NPT) ensemble were developed to determine the coexistence temperatures of the water hydrogen mixture using the direct coexistence method. The water molecules were modeled using the four-site TIP4P/Ice analytical potential, and the hydrogen molecules were described using a three-site potential. The simulations were performed at different pressures (p = 900, 1500, 3000, and 4000 bars). At each pressure, a series of simulations were developed at different temperatures (from 230 to 270 K). Our results followed a line parallel to the experimental coexistence temperatures and underestimated these temperatures by approximately 25 K in the investigated range. The final configurations could or could not contain a fluid phase depending on the pressure, in accordance with the phase diagram. In addition, we explored the dynamics of the H2 molecules through clathrate hydrate cages and observed different behaviors of the H2 molecules in the small cages and the large cages of the sII structure.

High-pressure melting curve of hydrogen.

PubMed

Davis, Sergio M; Belonoshko, Anatoly B; Johansson, Börje; Skorodumova, Natalia V; van Duin, Adri C T

2008-11-21

The melting curve of hydrogen was computed for pressures up to 200 GPa, using molecular dynamics. The inter- and intramolecular interactions were described by the reactive force field (ReaxFF) model. The model describes the pressure-volume equation of state solid hydrogen in good agreement with experiment up to pressures over 150 GPa, however the corresponding equation of state for liquid deviates considerably from density functional theory calculations. Due to this, the computed melting curve, although shares most of the known features, yields considerably lower melting temperatures compared to extrapolations of the available diamond anvil cell data. This failure of the ReaxFF model, which can reproduce many physical and chemical properties (including chemical reactions in hydrocarbons) of solid hydrogen, hints at an important change in the mechanism of interaction of hydrogen molecules in the liquid state.

Gaseous hydrogen embrittlement of high strength steels

NASA Technical Reports Server (NTRS)

Gangloff, R. P.; Wei, R. P.

1977-01-01

The effects of temperature, hydrogen pressure, stress intensity, and yield strength on the kinetics of gaseous hydrogen assisted crack propagation in 18Ni maraging steels were investigated experimentally. It was found that crack growth rate as a function of stress intensity was characterized by an apparent threshold for crack growth, a stage where the growth rate increased sharply, and a stage where the growth rate was unchanged over a significant range of stress intensity. Cracking proceeded on load application with little or no detectable incubation period. Gaseous hydrogen embrittlement susceptibility increased with increasing yield strength.

Facile fabrication of high-performance InGaZnO thin film transistor using hydrogen ion irradiation at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Byung Du; Park, Jin-Seong; Chung, K. B., E-mail: kbchung@dongguk.edu

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 devicemore » performance in IGZO TFT with an increase of the hydrogen ion irradiation dose.« less

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

NASA Astrophysics Data System (ADS)

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

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

Hydrogen-atom tunneling through a very high barrier; spontaneous thiol → thione conversion in thiourea isolated in low-temperature Ar, Ne, H2 and D2 matrices.

PubMed

Rostkowska, Hanna; Lapinski, Leszek; Nowak, Maciej J

2018-05-23

Spontaneous thiol → thione hydrogen-atom transfer has been investigated for molecules of thiourea trapped in Ar, Ne, normal-H2 (n-H2) and normal-D2 (n-D2) low-temperature matrices. The most stable thione isomer was the only form of the compound present in the matrices after their deposition. According to MP2/6-311++G(2d,p) calculations, the thiol tautomer should be higher in energy by 62.5 kJ mol-1. This less stable thiol form of the compound was photochemically generated in a thione → thiol process, occurring upon UV irradiation of the matrix. Subsequently, a very slow spontaneous conversion of the thiol tautomer into the thione form was observed for the molecules isolated in Ar, Ne, n-H2 and n-D2 matrices kept at 3.5 K and in the dark. Since the thiol → thione transformation in thiourea is a process involving the dissociation of a chemical bond, the barrier for this hydrogen-atom transfer is very high (104-181 kJ mol-1). Crossing such a high potential-energy barrier at a temperature as low as 3.5 K, is possible only by hydrogen-atom tunneling. The experimentally measured time constants of this tunneling process: 52 h (Ar), 76 h (Ne), 94 h (n-H2) and 94 h (n-D2), do not differ much from one another. Hence, the dependence of the tunneling rate on the matrix environment is not drastic. The progress of the thiol → thione conversion was also monitored for Ar matrices at different temperature: 3.5 K, 9 K and 15 K. For this temperature range, the experiments revealed no detectable temperature dependence of the rate of the tunneling process.

Thermal model development and validation for rapid filling of high pressure hydrogen tanks

DOE PAGES

Johnson, Terry A.; Bozinoski, Radoslav; Ye, Jianjun; ...

2015-06-30

This paper describes the development of thermal models for the filling of high pressure hydrogen tanks with experimental validation. Two models are presented; the first uses a one-dimensional, transient, network flow analysis code developed at Sandia National Labs, and the second uses the commercially available CFD analysis tool Fluent. These models were developed to help assess the safety of Type IV high pressure hydrogen tanks during the filling process. The primary concern for these tanks is due to the increased susceptibility to fatigue failure of the liner caused by the fill process. Thus, a thorough understanding of temperature changes ofmore » the hydrogen gas and the heat transfer to the tank walls is essential. The effects of initial pressure, filling time, and fill procedure were investigated to quantify the temperature change and verify the accuracy of the models. In this paper we show that the predictions of mass averaged gas temperature for the one and three-dimensional models compare well with the experiment and both can be used to make predictions for final mass delivery. Furthermore, due to buoyancy and other three-dimensional effects, however, the maximum wall temperature cannot be predicted using one-dimensional tools alone which means that a three-dimensional analysis is required for a safety assessment of the system.« less

A light hydrocarbon fuel processor producing high-purity hydrogen

NASA Astrophysics Data System (ADS)

Löffler, Daniel G.; Taylor, Kyle; Mason, Dylan

This paper discusses the design process and presents performance data for a dual fuel (natural gas and LPG) fuel processor for PEM fuel cells delivering between 2 and 8 kW electric power in stationary applications. The fuel processor resulted from a series of design compromises made to address different design constraints. First, the product quality was selected; then, the unit operations needed to achieve that product quality were chosen from the pool of available technologies. Next, the specific equipment needed for each unit operation was selected. Finally, the unit operations were thermally integrated to achieve high thermal efficiency. Early in the design process, it was decided that the fuel processor would deliver high-purity hydrogen. Hydrogen can be separated from other gases by pressure-driven processes based on either selective adsorption or permeation. The pressure requirement made steam reforming (SR) the preferred reforming technology because it does not require compression of combustion air; therefore, steam reforming is more efficient in a high-pressure fuel processor than alternative technologies like autothermal reforming (ATR) or partial oxidation (POX), where the combustion occurs at the pressure of the process stream. A low-temperature pre-reformer reactor is needed upstream of a steam reformer to suppress coke formation; yet, low temperatures facilitate the formation of metal sulfides that deactivate the catalyst. For this reason, a desulfurization unit is needed upstream of the pre-reformer. Hydrogen separation was implemented using a palladium alloy membrane. Packed beds were chosen for the pre-reformer and reformer reactors primarily because of their low cost, relatively simple operation and low maintenance. Commercial, off-the-shelf balance of plant (BOP) components (pumps, valves, and heat exchangers) were used to integrate the unit operations. The fuel processor delivers up to 100 slm hydrogen >99.9% pure with <1 ppm CO, <3 ppm CO 2. The

Simple Electrolyzer Model Development for High-Temperature Electrolysis System Analysis Using Solid Oxide Electrolysis Cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

JaeHwa Koh; DuckJoo Yoon; Chang H. Oh

2010-07-01

An electrolyzer model for the analysis of a hydrogen-production system using a solid oxide electrolysis cell (SOEC) has been developed, and the effects for principal parameters have been estimated by sensitivity studies based on the developed model. The main parameters considered are current density, area specific resistance, temperature, pressure, and molar fraction and flow rates in the inlet and outlet. Finally, a simple model for a high-temperature hydrogen-production system using the solid oxide electrolysis cell integrated with very high temperature reactors is estimated.

Palladium Gate All Around - Hetero Dielectric -Tunnel FET based highly sensitive Hydrogen Gas Sensor

NASA Astrophysics Data System (ADS)

Madan, Jaya; Chaujar, Rishu

2016-12-01

The paper presents a novel highly sensitive Hetero-Dielectric-Gate All Around Tunneling FET (HD-GAA-TFET) based Hydrogen Gas Sensor, incorporating the advantages of band to band tunneling (BTBT) mechanism. Here, the Palladium supported silicon dioxide is used as a sensing media and sensing relies on the interaction of hydrogen with Palladium-SiO2-Si. The high surface to volume ratio in the case of cylindrical GAA structure enhances the fortuities for surface reactions between H2 gas and Pd, and thus improves the sensitivity and stability of the sensor. Behaviour of the sensor in presence of hydrogen and at elevated temperatures is discussed. The conduction path of the sensor which is dependent on sensors radius has also been varied for the optimized sensitivity and static performance analysis of the sensor where the proposed design exhibits a superior performance in terms of threshold voltage, subthreshold swing, and band to band tunneling rate. Stability of the sensor with respect to temperature affectability has also been studied, and it is found that the device is reasonably stable and highly sensitive over the bearable temperature range. The successful utilization of HD-GAA-TFET in gas sensors may open a new door for the development of novel nanostructure gas sensing devices.

Optical high temperature sensor based on fiber Bragg grating

NASA Astrophysics Data System (ADS)

Zhang, Bowei

The aim of this thesis is to fabricate a fiber Bragg grating (FBG) temperature sensor that is capable to measure temperatures in excess of 1100°C. For this purpose, two topics have been studied and investigated during this project. One of them is the development of a high temperature resistant molecular-water induced FBGs; and the other is to investigate the effect of microwave-irradiation on the hydrogen-loaded FBG. The molecular-water induced FBGs are different from the other types of FBG. In these devices the refractive index is modulated by the periodic changes of molecular-water concentration within the grating. The device was developed using thermal annealing technology based on hydrogen-load FBG. Thermal stability of these devices was studied by measuring the grating reflectivity from room temperature to 1000°C. The stability of the device was tested by examining the FBG reflectivity for a period of time at certain temperatures. The results show that these devices are extremely stable at temperatures in excess of 1000°C. The hydroxyl concentration in the grating has been also investigated during this thesis. Based on the knowledge of hydroxyl groups inside FBG, a microwave treatment was designed to increase the hydroxyl concentration in the FBG area. The results show that the molecular-water induced grating, which was fabricated using microwave radiated hydrogen-loaded FBI, are stable at temperatures above 1100°C.

Creep-rupture behavior of iron superalloys in high pressure hydrogen

NASA Technical Reports Server (NTRS)

Bhattacharyya, S.

1981-01-01

Two cast alloys (CRM-6D and XF-818) and four sheet alloys (A-26, Incoloy 800H, N-155, and 19-9DL) in the thickness range of 0.79 to 0.99 mm were evaluated for use in the Stirling engine. The creep rupture behavior of these iron base high temperature alloys is being determined in air for 10 hr to 3,00 hr, and in 20.7 MPa (3,000 psi) H2 for 10 to 300 hr at temperatures of 650 deg to 925 deg. Material procurement, preparation and air creep rupture testing are described and existing data is analyzed. Systems for the high pressure hydrogen testing are discussed. Statistical analysis of temperature-compensated rupture data for each alloy is included.

Hot Jet Ignition Delay Characterization of Methane and Hydrogen at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Tarraf Kojok, Ali

This study contributes to a better understanding of ignition by hot combustion gases which finds application in internal combustion chambers with pre-chamber ignition as well as in wave rotor engine applications. The experimental apparatus consists of two combustion chambers: a pre chamber that generates the transient hot jet of gas and a main chamber which contains the main fuel air blend under study. Variables considered are three fuel mixtures (Hydrogen, Methane, 50% Hydrogen-Methane), initial pressure in the pre-chamber ranging from 1 to 2 atm, equivalence ratio of the fuel air mixture in the main combustion chamber ranging from 0.4 to 1.5, and initial temperature of the main combustion chamber mixture ranging from 297 K to 500 K. Experimental data makes use of 4 pressure sensors with a recorded sampling rate up to 300 kHz, as well as high speed Schlieren imaging with a recorded frame rate up to 20,833 frame per seconds. Results shows an overall increase in ignition delay with increasing equivalence ratio. High temperature of the main chamber blend was found not to affect hot jet ignition delay considerably. Physical mixing effects, and density of the main chamber mixture have a greater effect on hot jet ignition delay.

Properties of materials in high pressure hydrogen at room and elevated temperatures

NASA Technical Reports Server (NTRS)

Harris, J. A., Jr.

1972-01-01

Experimental efforts in this program for this period. Mechanical property tests of wrought and cast nickel-base alloys and one wrought cobalt-base alloy were conducted in 34.5 MN/sq m (5000-psig) helium and hydrogen or hydrogen mixtures. Comparison of test results was made to determine degradation of properties due to the hydrogen environments. All testing was conducted on solid specimens exposed to external gaseous pressure. Specific mechanical properties determined and the testing methods used are summarized.

High-pressure hydrogen testing of single crystal superalloys for advanced rocket engine turbopump turbine blades

NASA Technical Reports Server (NTRS)

Alter, W. S.; Parr, R. A.; Johnston, M. H.; Strizak, J. P.

1984-01-01

A screening program to determine the effects of high pressure hydrogen on selected candidate materials for advanced single crystal turbine blade applications is examined. The alloys chosen for the investigation are CM SX-2, CM SX-4C, Rene N-4, and PWA1480. Testing is carried out in hydrogen and helium at 34 MPa and room temperature, with both notched and unnotched single crystal specimens. Results show a significant variation in susceptibility to Hydrogen Environment Embrittlement (HEE) among the four alloys and a marked difference in fracture topography between hydrogen and helium environment specimens.

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

NASA Astrophysics Data System (ADS)

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Čeřovský, M., E-mail: scholtz@aldebaran.cz; Khun, J.; Rusová, K.

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-temperaturemore » plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.« less

Hybrid sulfur cycle operation for high-temperature gas-cooled reactors

DOEpatents

Gorensek, Maximilian B

2015-02-17

A hybrid sulfur (HyS) cycle process for the production of hydrogen is provided. The process uses a proton exchange membrane (PEM) SO.sub.2-depolarized electrolyzer (SDE) for the low-temperature, electrochemical reaction step and a bayonet reactor for the high-temperature decomposition step The process can be operated at lower temperature and pressure ranges while still providing an overall energy efficient cycle process.

Universal roles of hydrogen in electrochemical performance of graphene: high rate capacity and atomistic origins

PubMed Central

Ye, Jianchao; Ong, Mitchell T.; Heo, Tae Wook; Campbell, Patrick G.; Worsley, Marcus A.; Liu, Yuanyue; Shin, Swanee J.; Charnvanichborikarn, Supakit; Matthews, Manyalibo J.; Bagge-Hansen, Michael; Lee, Jonathan R.I.; Wood, Brandon C.; Wang, Y. Morris

2015-01-01

Atomic hydrogen exists ubiquitously in graphene materials made by chemical methods. Yet determining the effect of hydrogen on the electrochemical performance of graphene remains a significant challenge. Here we report the experimental observations of high rate capacity in hydrogen-treated 3-dimensional (3D) graphene nanofoam electrodes for lithium ion batteries. Structural and electronic characterization suggests that defect sites and hydrogen play synergistic roles in disrupting sp2 graphene to facilitate fast lithium transport and reversible surface binding, as evidenced by the fast charge-transfer kinetics and increased capacitive contribution in hydrogen-treated 3D graphene. In concert with experiments, multiscale calculations reveal that defect complexes in graphene are prerequisite for low-temperature hydrogenation, and that the hydrogenation of defective or functionalized sites at strained domain boundaries plays a beneficial role in improving rate capacity by opening gaps to facilitate easier Li penetration. Additional reversible capacity is provided by enhanced lithium binding near hydrogen-terminated edge sites. These findings provide qualitative insights in helping the design of graphene-based materials for high-power electrodes. PMID:26536830

Paradoxical roles of hydrogen in electrochemical performance of graphene: High rate capacity and atomistic origins

DOE PAGES

Ye, Jianchao C.; Ong, Mitchell T.; Heo, Tae Wook; ...

2015-11-05

Atomic hydrogen exists ubiquitously in graphene materials made by chemical methods. Yet determining the effect of hydrogen on the electrochemical performance of graphene remains a significant challenge. Here we report the experimental observations of high rate capacity in hydrogen-treated 3-dimensional (3D) graphene nanofoam electrodes for lithium ion batteries. Structural and electronic characterization suggests that defect sites and hydrogen play synergistic roles in disrupting sp 2 graphene to facilitate fast lithium transport and reversible surface binding, as evidenced by the fast charge-transfer kinetics and increased capacitive contribution in hydrogen-treated 3D graphene. In concert with experiments, multiscale calculations reveal that defect complexesmore » in graphene are prerequisite for low-temperature hydrogenation, and that the hydrogenation of defective or functionalized sites at strained domain boundaries plays a beneficial role in improving rate capacity by opening gaps to facilitate easier Li penetration. Additional reversible capacity is provided by enhanced lithium binding near hydrogen-terminated edge sites. Furthermore, these findings provide qualitative insights in helping the design of graphene-based materials for high-power electrodes.« less

High-temperature catalyst for catalytic combustion and decomposition

NASA Technical Reports Server (NTRS)

Mays, Jeffrey A. (Inventor); Lohner, Kevin A. (Inventor); Sevener, Kathleen M. (Inventor); Jensen, Jeff J. (Inventor)

2005-01-01

A robust, high temperature mixed metal oxide catalyst for propellant composition, including high concentration hydrogen peroxide, and catalytic combustion, including methane air mixtures. The uses include target, space, and on-orbit propulsion systems and low-emission terrestrial power and gas generation. The catalyst system requires no special preheat apparatus or special sequencing to meet start-up requirements, enabling a fast overall response time. Start-up transients of less than 1 second have been demonstrated with catalyst bed and propellant temperatures as low as 50 degrees Fahrenheit. The catalyst system has consistently demonstrated high decomposition effeciency, extremely low decomposition roughness, and long operating life on multiple test particles.

The solubility of hydrogen in plutonium in the temperature range 475 to 825 degrees centigrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, T.H.

1991-01-01

The solubility of hydrogen (H) in plutonium metal (Pu) was measured in the temperature range of 475 to 825{degree}C for unalloyed Pu (UA) and in the temperature range of 475 to 625{degree}C for Pu containing two-weight-percent gallium (TWP). For TWP metal, in the temperature range 475 to 600{degree}C, the saturated solution has a maximum hydrogen to plutonium ration (H/Pu) of 0.00998 and the standard enthalpy of formation ({Delta}H{degree}{sub f(s)}) is (-0.128 {plus minus} 0.0123) kcal/mol. The phase boundary of the solid solution in equilibrium with plutonium dihydride (PuH{sub 2}) is temperature independent. In the temperature range 475 to 625{degree}C, UAmore » metal has a maximum solubility at H/Pu = 0.011. The phase boundary between the solid solution region and the metal+PuH{sub 2} two-phase region is temperature dependent. The solubility of hydrogen in UA metal was also measured in the temperature range 650 to 825{degree}C with {Delta}H{degree}{sub f(s)} = (-0.104 {plus minus} 0.0143) kcal/mol and {Delta}S{degree}{sub f(s)} = 0. The phase boundary is temperature dependent and the maximum hydrogen solubility has H/Pu = 0.0674 at 825{degree}C. 52 refs., 28 figs., 9 tabs.« less

Process for producing high purity silicon nitride by the direct reaction between elemental silicon and nitrogen-hydrogen liquid reactants

DOEpatents

Pugar, Eloise A.; Morgan, Peter E. D.

1990-01-01

A process is disclosed for producing, at a low temperature, a high purity reaction product consisting essentially of silicon, nitrogen, and hydrogen which can then be heated to produce a high purity alpha silicon nitride. The process comprises: reacting together a particulate elemental high purity silicon with a high purity nitrogen-hydrogen reactant in its liquid state (such as ammonia or hydrazine) having the formula: N.sub.n H.sub.(n+m) wherein: n=1-4 and m=2 when the nitrogen-hydrogen reactant is straight chain, and 0 when the nitrogen-hydrogen reactant is cyclic. High purity silicon nitride can be formed from this intermediate product by heating the intermediate product at a temperature of from about 1200.degree.-1700.degree. C. for a period from about 15 minutes up to about 2 hours to form a high purity alpha silicon nitride product. The discovery of the existence of a soluble Si-N-H intermediate enables chemical pathways to be explored previously unavailable in conventional solid state approaches to silicon-nitrogen ceramics.

Process for producing high purity silicon nitride by the direct reaction between elemental silicon and nitrogen-hydrogen liquid reactants

DOEpatents

Pugar, E.A.; Morgan, P.E.D.

1987-09-15

A process is disclosed for producing, at a low temperature, a high purity reaction product consisting essentially of silicon, nitrogen, and hydrogen which can then be heated to produce a high purity alpha silicon nitride. The process comprises: reacting together a particulate elemental high purity silicon with a high purity nitrogen-hydrogen reactant in its liquid state (such as ammonia or hydrazine) having the formula: N/sub n/H/sub (n+m)/ wherein: n = 1--4 and m = 2 when the nitrogen-hydrogen reactant is straight chain, and 0 when the nitrogen-hydrogen reactant is cyclic. High purity silicon nitride can be formed from this intermediate product by heating the intermediate product at a temperature of from about 1200--1700/degree/C for a period from about 15 minutes up to about 2 hours to form a high purity alpha silicon nitride product. The discovery of the existence of a soluble Si/endash/N/endash/H intermediate enables chemical pathways to be explored previously unavailable in conventional solid-state approaches to silicon-nitrogen ceramics

Design of hydrogen vent line for the cryogenic hydrogen system in J-PARC

NASA Astrophysics Data System (ADS)

Tatsumoto, Hideki; Aso, Tomokazu; Kato, Takashi; Ohtsu, Kiichi; Hasegawa, Shoichi; Maekawa, Fujio; Futakawa, Masatoshi

2009-02-01

As one of the main experimental facilities in J-PARC, an intense spallation neutron source (JSNS) driven by a 1-MW proton beam selected supercritical hydrogen at a temperature of 20 K and a pressure of 1.5 MPa as a moderator material. Moderators are controlled by a cryogenic hydrogen system that has a hydrogen relief system, which consists of high and low pressure stage of manifolds, a hydrogen vent line and a stack, in order to release hydrogen to the outside safely. The design of the hydrogen vent line should be considered to prevent purge nitrogen gas in the vent line from freezing when releasing the cryogenic hydrogen, to prevent moisture in the stack placed in an outdoor location from freezing, and to inhibit large piping temperature reduction at a building wall penetration. In this work, temperature change behaviors in the hydrogen vent line were analyzed by using a CFD code, STAR-CD. We determined required sizes of the vent line based on the analytical results and its layout in the building.

Deposition method for producing silicon carbide high-temperature semiconductors

DOEpatents

Hsu, George C.; Rohatgi, Naresh K.

1987-01-01

An improved deposition method for producing silicon carbide high-temperature semiconductor material comprising placing a semiconductor substrate composed of silicon carbide in a fluidized bed silicon carbide deposition reactor, fluidizing the bed particles by hydrogen gas in a mildly bubbling mode through a gas distributor and heating the substrate at temperatures around 1200.degree.-1500.degree. C. thereby depositing a layer of silicon carbide on the semiconductor substrate.

Metallic Hydrogen

NASA Astrophysics Data System (ADS)

Silvera, Isaac; Zaghoo, Mohamed; Salamat, Ashkan

2015-03-01

Hydrogen is the simplest and most abundant element in the Universe. At high pressure it is predicted to transform to a metal with remarkable properties: room temperature superconductivity, a metastable metal at ambient conditions, and a revolutionary rocket propellant. Both theory and experiment have been challenged for almost 80 years to determine its condensed matter phase diagram, in particular the insulator-metal transition. Hydrogen is predicted to dissociate to a liquid atomic metal at multi-megabar pressures and T =0 K, or at megabar pressures and very high temperatures. Thus, its predicted phase diagram has a broad field of liquid metallic hydrogen at high pressure, with temperatures ranging from thousands of degrees to zero Kelvin. In a bench top experiment using static compression in a diamond anvil cell and pulsed laser heating, we have conducted measurements on dense hydrogen in the region of 1.1-1.7 Mbar and up to 2200 K. We observe a first-order phase transition in the liquid phase, as well as sharp changes in optical transmission and reflectivity when this phase is entered. The optical signature is that of a metal. The mapping of the phase line of this transition is in excellent agreement with recent theoretical predictions for the long-sought plasma phase transition to metallic hydrogen. Research supported by the NSF, Grant DMR-1308641, the DOE Stockpile Stewardship Academic Alliance Program, Grant DE-FG52-10NA29656, and NASA Earth and Space Science Fellowship Program, Award NNX14AP17H.

Synthesis of Ni/Graphene Nanocomposite for Hydrogen Storage.

PubMed

Zhou, Chunyu; Szpunar, Jerzy A; Cui, Xiaoyu

2016-06-22

We have designed a Ni-graphene composite for hydrogen storage with Ni nanoparticles of 10 nm in size, uniformly dispersed over a graphene substrate. This system exhibits attractive features like high gravimetric density, ambient conditions, and low activation temperature for hydrogen release. When charged at room temperature and an atmospheric hydrogen pressure of 1 bar, it could yield a hydrogen capacity of 0.14 wt %. When hydrogen pressure increased to 60 bar, the sorbent had a hydrogen gravimetric density of 1.18 wt %. The hydrogen release could occur at an operating temperature below 150 °C and completes at 250 °C.

High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors

PubMed Central

Ho, Dang; Jensen, Paul; Gutierrez-Zamora, Maria-Luisa; Beckmann, Sabrina; Manefield, Mike; Batstone, Damien

2016-01-01

A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA–stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C), acetoclastic Methanosarcina (55 to 60°C) and hydrogenotrophic Methanothermobacter (60 to 65°C). The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures. PMID:27490246

High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors.

PubMed

Ho, Dang; Jensen, Paul; Gutierrez-Zamora, Maria-Luisa; Beckmann, Sabrina; Manefield, Mike; Batstone, Damien

2016-01-01

A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C), acetoclastic Methanosarcina (55 to 60°C) and hydrogenotrophic Methanothermobacter (60 to 65°C). The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures.

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

PubMed Central

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

2015-01-01

Hydrogen is an efficient green fuel, but its low energy density when stored under high pressure or cryogenically, and safety issues, presents significant disadvantages; hence finding efficient and safe hydrogen carriers is a major challenge. Of special interest are liquid organic hydrogen carriers (LOHCs), which can be readily loaded and unloaded with considerable amounts of hydrogen. However, disadvantages include high hydrogen pressure requirements, high reaction temperatures for both hydrogenation and dehydrogenation steps, which require different catalysts, and high LOHC cost. Here we present a readily reversible LOHC system based on catalytic peptide formation and hydrogenation, using an inexpensive, safe and abundant organic compound with high potential capacity to store and release hydrogen, applying the same catalyst for loading and unloading hydrogen under relatively mild conditions. Mechanistic insight of the catalytic reaction is provided. We believe that these findings may lead to the development of an inexpensive, safe and clean liquid hydrogen carrier system. PMID:25882348

Integration of Photothermal Effect and Heat Insulation to Efficiently Reduce Reaction Temperature of CO2 Hydrogenation.

PubMed

Zhang, Wenbo; Wang, Liangbing; Wang, Kaiwen; Khan, Munir Ullah; Wang, Menglin; Li, Hongliang; Zeng, Jie

2017-02-01

The photothermal effect is applied in CO 2 hydrogenation to reduce the reaction temperature under illumination by encapsulating Pt nanocubes and Au nanocages into a zeolitic imidazolate framework (ZIF-8). Under illumination, the heat generated by the photothermal effect of Au nanocages is mainly insulated in the ZIF-8 to form a localized high-temperature region, thereby improving the catalytic activity of Pt nanocubes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement in low-temperature and instantaneous high-rate output performance of Al-free AB5-type hydrogen storage alloy for negative electrode in Ni/MH battery: Effect of thermodynamic and kinetic regulation via partial Mn substituting

NASA Astrophysics Data System (ADS)

Zhou, Wanhai; Zhu, Ding; Tang, Zhengyao; Wu, Chaoling; Huang, Liwu; Ma, Zhewen; Chen, Yungui

2017-03-01

A series of Al-free Mn-modified AB5-type hydrogen storage alloys have been designed and the effects of thermodynamic stability and electrochemical kinetics on electrochemical performance via Mn substituting have been investigated. Compared with high-Al alloys, the Al-free alloys in this study have better low-temperature performance and instantaneous high-rate output because of the higher surface catalytic ability. After partial substitution of Ni by Mn, both the hydrogen desorption capacity and plateau pressure decrease, and correspondingly results in an improved thermodynamic stability which is adverse to low-temperature delivery. Additionally, with the improvement of charge acceptance ability and anti-corrosion property via Mn substitution, the room-temperature discharge capacity and cycling stability increase slightly. However, Mn adversely affects the electrochemical kinetics and deteriorates both the surface catalytic ability and the bulk hydrogen diffusion ability, leading to the drop of low-temperature dischargeability, high-rate dischargeability and peak power (Ppeak). Based on the thermodynamic and kinetic regulation and overall electrochemical properties, the optimal composition is obtained when x = 0.2, the discharge capacity is 243.6 mAh g-1 at -40 °C with 60 mA g-1, and the Ppeak attains to 969.6 W kg-1 at -40 °C.

Dedicated nuclear facilities for electrolytic hydrogen production

NASA Technical Reports Server (NTRS)

Foh, S. E.; Escher, W. J. D.; Donakowski, T. D.

1979-01-01

An advanced technology, fully dedicated nuclear-electrolytic hydrogen production facility is presented. This plant will produce hydrogen and oxygen only and no electrical power will be generated for off-plant use. The conceptual design was based on hydrogen production to fill a pipeline at 1000 psi and a 3000 MW nuclear base, and the base-line facility nuclear-to-shaftpower and shaftpower-to-electricity subsystems, the water treatment subsystem, electricity-to-hydrogen subsystem, hydrogen compression, efficiency, and hydrogen production cost are discussed. The final conceptual design integrates a 3000 MWth high-temperature gas-cooled reactor operating at 980 C helium reactor-out temperature, direct dc electricity generation via acyclic generators, and high-current density, high-pressure electrolyzers based on the solid polymer electrolyte approach. All subsystems are close-coupled and optimally interfaced and pipeline hydrogen is produced at 1000 psi. Hydrogen costs were about half of the conventional nuclear electrolysis process.

Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts

NASA Astrophysics Data System (ADS)

Jeon, Ki-Joon; Moon, Hoi Ri; Ruminski, Anne M.; Jiang, Bin; Kisielowski, Christian; Bardhan, Rizia; Urban, Jeffrey J.

2011-04-01

Hydrogen is a promising alternative energy carrier that can potentially facilitate the transition from fossil fuels to sources of clean energy because of its prominent advantages such as high energy density (142 MJ kg-1 ref. 1), great variety of potential sources (for example water, biomass, organic matter), light weight, and low environmental impact (water is the sole combustion product). However, there remains a challenge to produce a material capable of simultaneously optimizing two conflicting criteria—absorbing hydrogen strongly enough to form a stable thermodynamic state, but weakly enough to release it on-demand with a small temperature rise. Many materials under development, including metal-organic frameworks, nanoporous polymers, and other carbon-based materials, physisorb only a small amount of hydrogen (typically 1-2 wt%) at room temperature. Metal hydrides were traditionally thought to be unsuitable materials because of their high bond formation enthalpies (for example MgH2 has a ΔHf˜75 kJ mol-1), thus requiring unacceptably high release temperatures resulting in low energy efficiency. However, recent theoretical calculations and metal-catalysed thin-film studies have shown that microstructuring of these materials can enhance the kinetics by decreasing diffusion path lengths for hydrogen and decreasing the required thickness of the poorly permeable hydride layer that forms during absorption. Here, we report the synthesis of an air-stable composite material that consists of metallic Mg nanocrystals (NCs) in a gas-barrier polymer matrix that enables both the storage of a high density of hydrogen (up to 6 wt% of Mg, 4 wt% for the composite) and rapid kinetics (loading in <30 min at 200 °C). Moreover, nanostructuring of the Mg provides rapid storage kinetics without using expensive heavy-metal catalysts.

Highly efficient temperature-induced visible light photocatalytic hydrogen production

NASA Astrophysics Data System (ADS)

Han, Bing

Photocatalysis is the acceleration of photoreaction in presence of a photocatalyst. Semiconductor photocatalysis has obtained much attention as a potential solution to the worldwide energy storage due to its promising ability to directly convert solar energy into chemical fuels. This dissertation research mainly employ three approaches to enhance photocatalytic activities, which includes (I) Modifying semiconductor nanomaterials for visible and near-IR light absorption; (II) Synthesis of light-diffuse-reflection-surface of SiO2 substrate to utilize scattered light; and (III) design of a hybrid system that combines light and heat to enhance visible light photocatalytic activity. Those approaches were applied to two systems: (1) hydrogen production from water; (2) carbon dioxide reforming of methane. The activity of noble metals such as platinum were investigated as co-catalysts and cheap earth abundant catalysts as alternatives to reduce cost were also developed. Stability, selectivity, mechanism were investigated. Great enhancement of visible light activity over a series of semiconductors/heterostructures were observed. Such extraordinary performance of artificial photosynthetic hydrogen production system would provide a novel approach for the utilization of solar energy for chemical fuel production.

Effect of species, life stage, and water temperature on the toxicity of hydrogen peroxide to fish

USGS Publications Warehouse

Rach, J.J.; Schreier, Theresa M.; Howe, G.E.; Redman, S.D.

1997-01-01

Hydrogen peroxide is a drug of low regulatory priority status that is effective in treating fish and fish eggs infected by fungi. However, only limited information is available to guide fish culturists in administering hydrogen peroxide to diseased fish. Laboratory tests were conducted to determine (1) the sensitivity of brown trout Salmo trutta, lake trout Salvelinus namaycush, fathead minnow Pimephales promelas, walleye Stizostedion vitreum, channel catfish Ictalurus punctatus, and bluegill Lepomis, machrochirus to hydrogen peroxide treatments; (2) the sensitivity of various life stages of rainbow trout Oncorhynchus mykiss to hydrogen peroxide treatments; and (3) the effect of water temperature on the acute toxicity of hydrogen peroxide to three fish species. Fish were exposed to hydrogen peroxide concentrations ranging from 100 to 5,000 mu L/L (ppm) for 15-min or 45-min treatments every other day for four consecutive treatments to determine the sensitivity of various species and life stages of fish. Except for walleye, most species of fish tested (less than or equal to 2 g) tolerated hydrogen peroxide of 1,000 mu L/L or greater. Walleyes were sensitive to hydrogen peroxide concentrations as low as 100 mu L/L. A correlation was found between the toxicity of hydrogen peroxide and the life stages of rainbow trout; larger fish were more sensitive. Generally, the toxicity of hydrogen peroxide increased for all species as water temperature increased. The results of these experiments demonstrate that it is important to consider the effects of species, life stage, and water temperature when conducting hydrogen peroxide treatments.

Simulations of supersonic highly under-expanded hydrogen jets

NASA Astrophysics Data System (ADS)

Miarnau Marin, Ana; Xiao, Cheng-Nian; Denner, Fabian; van Wachem, Berend

2017-11-01

The pressure drop across choke valves required to transport natural gas can be in the order of several hundred bars, leading to the development of supersonic under-expanded jets. When considering a real gas, the gas can cool upon expansion, a phenomenon which can be explained by the Joule-Thomson effect. This study compares the effects of using ideal and real gas equations of state, using a computational model in which hydrogen is released from a high-pressure tank, through a converging nozzle, into a chamber containing hydrogen at near-atmospheric conditions. The initial studies were carried out using an ideal gas assumption and nozzle pressure ratios of 10, 30 and 70 and the results were validated against existing literature. To account for the Joule-Thomson effect, ideal and real gas simulations were then carried out with a pressure ratio of 70. For the real gas model, the Peng-Robinson equation of state was chosen. At the nozzle exit, the ideal gas model underestimates the velocity and overestimates the temperature and density; as the flow expands, the flow properties are the same up to the Mach disk, at which point the ideal gas underestimates the Mach number and predicts a higher temperature and density than the Peng-Robinson model due to the absence of cooling.

Highly sensitive hydrogen detection of catalyst-free ZnO nanorod networks suspended by lithography-assisted growth.

PubMed

Huh, Junghwan; Park, Jonghyurk; Kim, Gyu Tae; Park, Jeong Young

2011-02-25

We have successfully demonstrated a ZnO nanorod-based 3D nanostructure to show a high sensitivity and very fast response/recovery to hydrogen gas. ZnO nanorods have been synthesized selectively over the pre-defined area at relatively low temperature using a simple self-catalytic solution process assisted by a lithographic method. The conductance of the ZnO nanorod device varies significantly as the concentration of the hydrogen is changed without any additive metal catalyst, revealing a high sensitivity to hydrogen gas. Its superior performance can be explained by the porous structure of its three-dimensional network and the enhanced surface reaction of the hydrogen molecules with the oxygen defects resulting from a high surface-to-volume ratio. It was found that the change of conductance follows a power law depending on the hydrogen concentration. A Langmuir isotherm following an ideal power law and a cross-over behavior of the activation energy with respect to hydrogen concentration were observed. This is a very novel and intriguing phenomenon on nanostructured materials, which suggests competitive surface reactions in ZnO nanorod gas sensors.

High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

NASA Astrophysics Data System (ADS)

Gannon, Paul; Amendola, Roberta

2012-12-01

High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

A ’Hydrogen Partitioning’ Model for Hydrogen Assisted Crack Growth.

DTIC Science & Technology

1984-09-01

the change in Stage II crack growth rate from Region A to Region C in the 18NI maraging steels . It cannot, however, explain the sudden drop off in...Neither partitioning of hydrogen nor adsorption equilibrium can account for the observed "high" temperature response of l8Ni maraging steel in hydrogen...ment and Stress Corrosion Cracking, American Society for Metals, Metals Park, OH, 1984, p. 103 (in press). 11. R. P. Wei: in Hydrogen Effects in

Metastable Metal Hydrides for Hydrogen Storage

DOE PAGES

Graetz, Jason

2012-01-01

The possibility of using hydrogen as a reliable energy carrier for both stationary and mobile applications has gained renewed interest in recent years due to improvements in high temperature fuel cells and a reduction in hydrogen production costs. However, a number of challenges remain and new media are needed that are capable of safely storing hydrogen with high gravimetric and volumetric densities. Metal hydrides and complex metal hydrides offer some hope of overcoming these challenges; however, many of the high capacity “reversible” hydrides exhibit a large endothermic decomposition enthalpy making it difficult to release the hydrogen at low temperatures. Onmore » the other hand, the metastable hydrides are characterized by a low reaction enthalpy and a decomposition reaction that is thermodynamically favorable under ambient conditions. The rapid, low temperature hydrogen evolution rates that can be achieved with these materials offer much promise for mobile PEM fuel cell applications. However, a critical challenge exists to develop new methods to regenerate these hydrides directly from the reactants and hydrogen gas. This spotlight paper presents an overview of some of the metastable metal hydrides for hydrogen storage and a few new approaches being investigated to address the key challenges associated with these materials.« less

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

PubMed

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.

Temperature-dependent absorption cross sections for hydrogen peroxide vapor

NASA Technical Reports Server (NTRS)

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.

Low-cost fabrication of highly sensitive room temperature hydrogen sensor based on ordered mesoporous Co-doped TiO2 structure

NASA Astrophysics Data System (ADS)

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-.

Temperature Dependence in the Terahertz Spectrum of Nicotinamide: Anharmonicity and Hydrogen-Bonded Network.

PubMed

Takahashi, Masae; Okamura, Nubuyuki; Fan, Xinyi; Shirakawa, Hitoshi; Minamide, Hiroaki

2017-04-06

We have investigated the terahertz-spectral property of nicotinamide focusing on the temperature dependence in the range of 14-300 K. We observed that almost all peaks in the terahertz spectrum of the nicotinamide crystal showed a remarkable shift with temperature, whereas the lowest-frequency peak at 34.8 cm -1 showed a negligible shift with temperature. By analyzing the terahertz spectrum with the dispersion-corrected density functional theory calculations, we found that the difference in the temperature dependence of the peak shift is well understood in terms of the presence/absence of stretching vibration of the intermolecular hydrogen bond in the mode and the change of cell parameters. The anharmonicity in the dissociation potential energy of very weak intermolecular hydrogen bonding causes the remarkable peak shift with temperature in the terahertz spectrum of nicotinamide. This finding suggests that the assignment and identification of peaks in the terahertz spectrum are systematically enabled by temperature-dependent measurements.

Hydrogen-bond symmetrization in methane and hydrogen hydrates in the Mbar range

NASA Astrophysics Data System (ADS)

Bove, L. E.; Ranieri, U.; Gaal, R.; Finocchi, F.; Kuhs, W. F.; Falenty, A.; Klotz, S.; Gillet, P.

2016-12-01

Ice-VII and ice-X phases are the most stable forms of ice at high temperature and extreme pressures, typical of the interiors of satellites and planets. The phase transition between them is a prototypical case of quantum-driven phenomenon, as it can be described as a quantum delocalization of protons in the middle of O-O distances. Recent studies on LiCl- and NaCl-doped ice 1-3 have shown that the presence of salt inclusions in the ice lattice suppresses the quantum behavior of protons, hindering the appearance of the symmetric phase, and possibly suppressing the predicted high temperature superionic phase. This finding stimulated the investigation of similar effects in other water-based compounds, which are thought to be present in icy bodies, namely hydrogen and methane high pressure hydrates. Few experiments have been performed in the past to identify signatures of the hydrogen-bond symmetrization in methane and hydrogen hydrates without reaching conclusive results4,5. Here we present new results on the hydrogen-bond symmetrization of methane and hydrogen hydrates using Raman scattering in the Mbar range and semiclassical simulations including nuclear quantum effects. 1 Bove L. E. et al., E_ect of salt on the H-bond symmetrization in ice, Proc. Natl. Acad. Sci. USA 112, 8216, 2015 ; 2. Bronstein Y. et al., Quantum versus classical protons in pure and salty ice under pressure, Phys. Rev. B 93, 024104, 2016. 3. Klotz S. et al., Ice VII from aqueous salt solutions: From a glass to a crystal with broken H-bonds, Nature Sci. Rep. , in press. 4. Tanaka T. et al., Phase changes of _lled ice Ih methane hydrate under low temperature and high pressure, J. Chem. Phys. 139, 104701, 2013 5. Hirai H. et al., Structural changes of _lled ice Ic hydrogen hydrate under low temperatures and high pressures from 5 to 50 GPa, J. Chem. Phys. 137, 074505, 2012

High-pressure torsion for new hydrogen storage materials.

PubMed

Edalati, Kaveh; Akiba, Etsuo; Horita, Zenji

2018-01-01

High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Since 2007, the method has been employed to enhance the hydrogenation kinetics in different Mg-based hydrogen storage materials. Recent studies showed that the method is effective not only for increasing the hydrogenation kinetics but also for improving the hydrogenation activity, for enhancing the air resistivity and more importantly for synthesizing new nanostructured hydrogen storage materials with high densities of lattice defects. This manuscript reviews some major findings on the impact of HPT process on the hydrogen storage performance of different titanium-based and magnesium-based materials.

Core--strategy leading to high reversible hydrogen storage capacity for NaBH4.

PubMed

Christian, Meganne L; Aguey-Zinsou, Kondo-François

2012-09-25

Owing to its high storage capacity (10.8 mass %), sodium borohydride (NaBH(4)) is a promising hydrogen storage material. However, the temperature for hydrogen release is high (>500 °C), and reversibility of the release is unachievable under reasonable conditions. Herein, we demonstrate the potential of a novel strategy leading to high and stable hydrogen absorption/desorption cycling for NaBH(4) under mild pressure conditions (4 MPa). By an antisolvent precipitation method, the size of NaBH(4) particles was restricted to a few nanometers (<30 nm), resulting in a decrease of the melting point and an initial release of hydrogen at 400 °C. Further encapsulation of these nanoparticles upon reaction of nickel chloride at their surface allowed the synthesis of a core--shell nanostructure, NaBH(4)@Ni, and this provided a route for (a) the effective nanoconfinement of the melted NaBH(4) core and its dehydrogenation products, and (b) reversibility and fast kinetics owing to short diffusion lengths, the unstable nature of nickel borohydride, and possible modification of reaction paths. Hence at 350 °C, a reversible and steady hydrogen capacity of 5 mass % was achieved for NaBH(4)@Ni; 80% of the hydrogen could be desorbed or absorbed in less than 60 min, and full capacity was reached within 5 h. To the best of our knowledge, this is the first time that such performances have been achieved with NaBH(4). This demonstrates the potential of the strategy in leading to major advancements in the design of effective hydrogen storage materials from pristine borohydrides.

Hydrogen and related materials at high density: Physics, chemistry and planetary implications

NASA Technical Reports Server (NTRS)

Hemley, R. J.; Mao, H. K.; Duffy, T. S.; Goncharov, A.; Vos, W.; Zha, C. S.; Eggert, J. H.; Li, M.; Hanfland, M.

1994-01-01

Recent studies of low-Z molecular materials including hydrogen to multimegabar pressures (less than 300 GPa) have uncovered a range of phenomena relevant to understanding the nature of the interiors of the outer planets and their satellites. Synchrotron x ray diffraction measurements (to 42 GPa) have been used to determine the crystal structure of the solid (hexagonal-close packed) and equation of state. Sound velocities in fluid and solid hydrogen (to 24 GPa) have been inverted to obtain elastic constants and aggregate bulk and shear moduli. In addition, an improved intermolecular potential has been determined which fits both static and shock-wave data. Use of the new potential for the molecular envelope of Jupiter suggests the need for major revisions of existing Jovian models or a reanalysis of reported free oscillations for the planet. Studies at higher pressures (greater than 100 GPa) reveal a sequence of pressure-induced symmetry-breaking transitions in molecular hydrogen, giving rise to three high-pressure phases (1, 2, and 3). Phase 1 is the rotationally disordered hcp phase which persists from low pressure to well above 100 GPa at high temperature (e.g., 300 K). Phase 2 is a low-temperature, high-pressure phase (transition at 100 GPa and 77 K in H2) with spectral features indicative of partial rotational ordering and crystallographic distortion. The transition to Phase 3 at 150 GPa is accompanied by a weakening of the molecular bond, gradual changes in orientational ordering, strong enhancement of the infrared intramolecular vibrational absorption, and strong intermolecular interactions similar to those of ambient-pressure network solids. Studies of the phase diagram reveal a triple point near 130 K and 160 GPa. Higher pressure measurements of vibrational spectra place a lower bound of approximately 250 GPa on the predicted transition pressure for dissociation of molecular hydrogen to form a monatomic metal.

Characterization of high-pressure capacitively coupled hydrogen plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nunomura, S.; Kondo, M.

2007-11-01

Capacitively coupled very-high-frequency hydrogen plasmas have been systematically diagnosed in a wide range of a gas pressure from 5 mTorr to 10 Torr. The plasma parameters, ion species, and ion energy distributions (IEDs) are measured using a Langmuir probe, optical emission spectroscopy, and energy filtered mass spectrometer. The measurement results show that the ion species in a hydrogen plasma is determined from ionization channels and subsequent ion-molecule reactions. The ions are dominated by H{sub 2}{sup +} at a less-collisional condition of < or approx. 20 mTorr, whereas those are dominated by H{sub 3}{sup +} at a collisional condition of >more » or approx. 20 mTorr. The IED is determined by both the sheath potential drop and ion-neutral collisions in the plasma sheath. The IED is broadened for a collisional sheath at > or approx. 0.3 Torr and the ion bombardment energy is lowered. For high-pressure discharge operated at {approx_equal}10 Torr, plasmas are characterized by a low electron temperature of {approx_equal}0.8 eV and a low ion bombardment energy of < or approx. 15 eV.« less

High-performance flexible hydrogen sensor made of WS2 nanosheet-Pd nanoparticle composite film

NASA Astrophysics Data System (ADS)

Kuru, Cihan; Choi, Duyoung; Kargar, Alireza; Liu, Chin Hung; Yavuz, Serdar; Choi, Chulmin; Jin, Sungho; Bandaru, Prabhakar R.

2016-05-01

We report a flexible hydrogen sensor, composed of WS2 nanosheet-Pd nanoparticle composite film, fabricated on a flexible polyimide substrate. The sensor offers the advantages of light-weight, mechanical durability, room temperature operation, and high sensitivity. The WS2-Pd composite film exhibits sensitivity (R 1/R 2, the ratio of the initial resistance to final resistance of the sensor) of 7.8 to 50 000 ppm hydrogen. Moreover, the WS2-Pd composite film distinctly outperforms the graphene-Pd composite, whose sensitivity is only 1.14. Furthermore, the ease of fabrication holds great potential for scalable and low-cost manufacturing of hydrogen sensors.

Influence of high pressure hydrogen environment on creep deformation of Mo-Re, Haynes 188, and NARloy-Z alloys

NASA Technical Reports Server (NTRS)

Sastry, S. M. L.; Yang, Charles C.; Ouyang, Shewang; Jerina, K. L.; Schwartz, D. S.

1994-01-01

The present study focuses on the investigation of the influence of hydrogen on the mechanical properties of three types of alloys at elevated temperatures. The reasons for the consideration of hydrogen effects are the potential use of hydrogen as a coolant in gas-cooled reactors and fuel in advanced hypersonic vehicles. The materials used in hydrogen atmosphere must not be embrittled by hydrogen at ambient temperature and should have good strength in hydrogen atmosphere at elevated temperature. The paucity of information concerning the mechanical performance in hydrogen atmosphere at elevated temperature has been a limiting factor in the selection and design of structural components for operation in hydrogen environment.

LIQUID BIO-FUEL PRODUCTION FROM NON-FOOD BIOMASS VIA HIGH TEMPERATURE STEAM ELECTROLYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. L. Hawkes; J. E. O'Brien; M. G. McKellar

2011-11-01

Bio-Syntrolysis is a hybrid energy process that enables production of synthetic liquid fuels that are compatible with the existing conventional liquid transportation fuels infrastructure. Using biomass as a renewable carbon source, and supplemental hydrogen from high-temperature steam electrolysis (HTSE), bio-syntrolysis has the potential to provide a significant alternative petroleum source that could reduce US dependence on imported oil. Combining hydrogen from HTSE with CO from an oxygen-blown biomass gasifier yields syngas to be used as a feedstock for synthesis of liquid transportation fuels via a Fischer-Tropsch process. Conversion of syngas to liquid hydrocarbon fuels, using a biomass-based carbon source, expandsmore » the application of renewable energy beyond the grid to include transportation fuels. It can also contribute to grid stability associated with non-dispatchable power generation. The use of supplemental hydrogen from HTSE enables greater than 90% utilization of the biomass carbon content which is about 2.5 times higher than carbon utilization associated with traditional cellulosic ethanol production. If the electrical power source needed for HTSE is based on nuclear or renewable energy, the process is carbon neutral. INL has demonstrated improved biomass processing prior to gasification. Recyclable biomass in the form of crop residue or energy crops would serve as the feedstock for this process. A process model of syngas production using high temperature electrolysis and biomass gasification is presented. Process heat from the biomass gasifier is used to heat steam for the hydrogen production via the high temperature steam electrolysis process. Oxygen produced form the electrolysis process is used to control the oxidation rate in the oxygen-blown biomass gasifier. Based on the gasifier temperature, 94% to 95% of the carbon in the biomass becomes carbon monoxide in the syngas (carbon monoxide and hydrogen). Assuming the thermal efficiency of

An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron-Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications.

PubMed

Tu, Yun; Ye, Lin; Zhou, Shao-Ping; Tu, Shan-Tung

2017-02-23

Local strain measurements are considered as an effective method for structural health monitoring of high-temperature components, which require accurate, reliable and durable sensors. To develop strain sensors that can be used in higher temperature environments, an improved metal-packaged strain sensor based on a regenerated fiber Bragg grating (RFBG) fabricated in hydrogen (H₂)-loaded boron-germanium (B-Ge) co-doped photosensitive fiber is developed using the process of combining magnetron sputtering and electroplating, addressing the limitation of mechanical strength degradation of silica optical fibers after annealing at a high temperature for regeneration. The regeneration characteristics of the RFBGs and the strain characteristics of the sensor are evaluated. Numerical simulation of the sensor is conducted using a three-dimensional finite element model. Anomalous decay behavior of two regeneration regimes is observed for the FBGs written in H₂-loaded B-Ge co-doped fiber. The strain sensor exhibits good linearity, stability and repeatability when exposed to constant high temperatures of up to 540 °C. A satisfactory agreement is obtained between the experimental and numerical results in strain sensitivity. The results demonstrate that the improved metal-packaged strain sensors based on RFBGs in H₂-loaded B-Ge co-doped fiber provide great potential for high-temperature applications by addressing the issues of mechanical integrity and packaging.

High-pressure torsion for new hydrogen storage materials

PubMed Central

Edalati, Kaveh; Akiba, Etsuo; Horita, Zenji

2018-01-01

Abstract High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Since 2007, the method has been employed to enhance the hydrogenation kinetics in different Mg-based hydrogen storage materials. Recent studies showed that the method is effective not only for increasing the hydrogenation kinetics but also for improving the hydrogenation activity, for enhancing the air resistivity and more importantly for synthesizing new nanostructured hydrogen storage materials with high densities of lattice defects. This manuscript reviews some major findings on the impact of HPT process on the hydrogen storage performance of different titanium-based and magnesium-based materials. PMID:29511396

Solvent induced temperature dependencies of NMR parameters of hydrogen bonded anionic clusters

NASA Astrophysics Data System (ADS)

Golubev, Nikolai S.; Shenderovich, Ilja G.; Tolstoy, Peter M.; Shchepkin, Dmitry N.

2004-07-01

The solvent induced temperature dependence of NMR parameters (proton and fluorine chemical shifts, the two-bond scalar spin coupling constant across the hydrogen bridge, 2hJFF) for dihydrogen trifluoride anion, (FH) 2F -, in a polar aprotic solvent, CDF 3/CDF 2Cl, is reported and discussed. The results are interpreted in terms of a simple electrostatic model, accounting a decrease of electrostatic repulsion of two negatively charged fluorine atoms on placing into a dielectric medium. The conclusion is drawn that polar medium causes some contraction of hydrogen bonds in ionic clusters combined with a decrease of hydrogen bond asymmetry.

Process for hydrogenation of hydrocarbon tars

DOEpatents

Dolbear, Geoffrey E.

1978-07-18

Hydrocarbon tars of high asphaltene content such as tars obtained from pyrolysis of coal are dissolved in a solvent formed from the hydrogenation of the coal tars, and the resultant mixture hydrogenated in the presence of a catalyst at a pressure from about 1500 to 5000 psig at a temperature from about 500.degree. F to about the critical temperature of the solvent to form a light hydrocarbon as a solvent for the tars. Hydrogen content is at least three times the amount of hydrogen consumed.

Studies of the use of heat from high temperature nuclear sources for hydrogen production processes

NASA Technical Reports Server (NTRS)

Farbman, G. H.

1976-01-01

Future uses of hydrogen and hydrogen production processes that can meet the demand for hydrogen in the coming decades were considered. To do this, a projection was made of the market for hydrogen through the year 2000. Four hydrogen production processes were selected, from among water electrolysis, fossil based and thermochemical water decomposition systems, and evaluated, using a consistent set of ground rules, in terms of relative performance, economics, resource requirements, and technology status.

Equilibrium and diffusion studies of metal-hydrogen systems

NASA Astrophysics Data System (ADS)

Maroevic, Petar

Several new methods and models have been developed pertaining to equilibrium properties of hydrogen in random binary substitutional alloys at room and lower temperatures, describing both statistics and kinetics of hydrogen in them. They represent a solution to the problem of the complete Fermi-Dirac description which is physically appropriate for these systems. Hydrogen diffusion which proceeds via lattice assisted quantum tunneling at room and lower temperatures requires a new and different description from the one based on the thermal hopping picture, which pertains only to relatively high temperatures. It is also shown that the analogs of the solution to the Fermi-Dirac problem of hydrogen can be successfully applied to the description of vacancies in a hydrogenated system, a phenomena known to occur due to high hydrogen-vacancy binding energies and the creation of hydrogen-vacancy clusters. The solution based on this model applies to much lower temperatures and higher concentrations than the tradition alone. This methodology has also been applied to the surface problem where very large vacancy and hydrogen concentrations occur. This is of special importance since mechanical properties are known to be greatly affected by the surface. As another consequence of hydrogen induced vacancies, hydrogen induced lattice migration (HILM) occurs. This has been demonstrated in our electrical resistivity study of palladium wires where recrystallization and annealing effects were observed upon hydrogen-heat-treatment (HHT).

Improved Durability of SOEC Stacks for High Temperature Electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

James E. O'Brien; Robert C. O'Brien; Xiaoyu Zhang

2013-01-01

High temperature steam electrolysis is a promising technology for efficient and sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology can be realized. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-termmore » durability of SOECs. Electrolyte-supported and electrode-supported SOEC stacks were provided by Ceramatec Inc. and Materials and Systems Research Inc. (MSRI), respectively, for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technologies developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, espectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. Optimization of electrode materials, interconnect coatings, and electrolyte-electrode interface microstructures contribute to better durability of SOEC stacks.« less

A titania nanotube-array room-temperature sensor for selective detection of hydrogen at low concentrations.

PubMed

Varghese, Oomman K; Mor, Gopal K; Grimes, Craig A; Paulose, Maggie; Mukherjee, Niloy

2004-09-01

A tremendous variation in electrical resistance, from the semiconductor to metallic range, has been observed in titania nanotube arrays at room temperature, approximately 25 degrees C, in the presence of < or = 1000 ppm hydrogen gas. The nanotube arrays are fabricated by anodizing titanium foil in an aqueous electrolyte solution containing hydrofluoric acid and acetic acid. Subsequently, the arrays are coated with a 10 nm layer of palladium by evaporation. Electrical contacts are made by sputtering a 2 mm diameter platinum disk atop the Pd-coated nanotube array. These sensors exhibit a resistance variation of the order of 10(4) in the presence of 100 ppm hydrogen at 25 degrees C. The sensors demonstrate complete reversibility, repeatability, high selectivity, negligible drift and wide dynamic range. The nanoscale geometry of the nanotubes, in particular the points of tube-to-tube contact, is believed to be responsible for the outstanding hydrogen gas sensitivities.

Stable catalyst layers for hydrogen permeable composite membranes

DOEpatents

Way, J. Douglas; Wolden, Colin A

2014-01-07

The present invention provides a hydrogen separation membrane based on nanoporous, composite metal carbide or metal sulfide coated membranes capable of high flux and permselectivity for hydrogen without platinum group metals. The present invention is capable of being operated over a broad temperature range, including at elevated temperatures, while maintaining hydrogen selectivity.

Liquid-phase chemical hydrogen storage: catalytic hydrogen generation under ambient conditions.

PubMed

Jiang, Hai-Long; Singh, Sanjay Kumar; Yan, Jun-Min; Zhang, Xin-Bo; Xu, Qiang

2010-05-25

There is a demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. Lithium and sodium borohydride, ammonia borane, hydrazine, and formic acid have been extensively investigated as promising hydrogen storage materials based on their relatively high hydrogen content. Significant advances, such as hydrogen generation temperatures and reaction kinetics, have been made in the catalytic hydrolysis of aqueous lithium and sodium borohydride and ammonia borane as well as in the catalytic decomposition of hydrous hydrazine and formic acid. In this Minireview we briefly survey the research progresses in catalytic hydrogen generation from these liquid-phase chemical hydrogen storage materials.

Low temperature hydrogen production during experimental hydration of partially-serpentinized dunite

NASA Astrophysics Data System (ADS)

Miller, Hannah M.; Mayhew, Lisa E.; Ellison, Eric T.; Kelemen, Peter; Kubo, Mike; Templeton, Alexis S.

2017-07-01

Dissolved hydrogen is common in mafic and ultramafic aquifers; however, the water/rock reactions that give rise to hydrogen production at near-surface temperatures are enigmatic. Similarly, mineral hydration experiments have not yet unequivocally demonstrated whether H2 can be produced at low-temperatures at significant rates from reaction of aqueous fluids with basalts and peridotites for prolonged amounts of time. We conducted laboratory-based water/rock reactions between partially serpentinized Oman dunite and a simulated Oman rainwater (RW) media, as well as a simulated seawater (SW) media, to quantify H2 generation rates at 100 °C. Throughout more than 9 months of water/rock reaction, extensive hydrogen production and consumption were observed in RW and SW media. In the first 24 h of reaction in anoxic fluids containing only dissolved N2 and CO2, the room-temperature pH in both RW and SW media increased from 6.5 to ∼9, and the average pH then remained relatively constant at pH 8.5 (±0.5 pH) for the duration of the experiments. We also measured some of the highest hydrogen concentrations observed in experimental low-temperature serpentinization reactions. The maximum measured H2 concentrations in SW media were 470 nmol H2 per g mineral after ∼3 months, while RW media H2 concentrations reached 280 nmol/g H2 after ∼3 months. After reaching micromolar dissolved H2(aq), the H2 concentrations notably declined, and CO2 was almost fully consumed. We measured the formation of formate (up to 98 μM) and acetate (up to 91 μM) associated with a drawdown of H2 and CO2 in the experiments. No CH4 or carbonate formation was observed. To identify reactions giving rise to low-temperature hydrogen production, the mineralogy and oxidation state of the Fe-bearing species in the dunite were extensively characterized before and after reaction using Raman spectroscopy, Quantitative Evaluation of Minerals by SCANing electron microscopy (QEMSCAN), powder X-ray diffraction (XRD

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 anmore » 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.« less

Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

NASA Technical Reports Server (NTRS)

Akyuzlu, Kazim M.; Coote, David

2013-01-01

A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and

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

PubMed

Mazzola, Guglielmo; Yunoki, Seiji; Sorella, Sandro

2014-03-19

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

Modelling of hydrogen permeability of membranes for high-purity hydrogen production

NASA Astrophysics Data System (ADS)

Zaika, Yury V.; Rodchenkova, Natalia I.

2017-11-01

High-purity hydrogen is required for clean energy and a variety of chemical technology processes. Different alloys, which may be well-suited for use in gas-separation plants, were investigated by measuring specific hydrogen permeability. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones), and identify the limiting factors. This paper presents a nonlinear mathematical model taking into account the dynamics of sorption-desorption processes and reversible capture of diffusing hydrogen by inhomogeneity of the material’s structure, and also modification of the model when the transport rate is high. The results of numerical modelling allow to obtain information about output data sensitivity with respect to variations of the material’s hydrogen permeability parameters. Furthermore, it is possible to analyze the dynamics of concentrations and fluxes that cannot be measured directly. Experimental data for Ta77Nb23 and V85Ni15 alloys were used to test the model. This work is supported by the Russian Foundation for Basic Research (Project No. 15-01-00744).

High temperature electrolytic recovery of oxygen from gaseous effluents from the carbo-chlorination of lunar anorthite and the hydrogenation of ilmenite: A theoretical study

NASA Technical Reports Server (NTRS)

Erstfield, T. E.; Williams, R. J.

1979-01-01

A thermodynamic analysis discusses the compositions of gaseous effluents from the reaction of carbon and chlorine and of hydrogen with lunar anorthite and ilmenite, respectively. The computations consider the effects of the indigenous volatiles on the solid/gas reactions and on the composition of the effluent gases. A theoretical parameterization of the high temperature electrolysis of such gases is given for several types of solid ceramic electrolytes, and the effect of oxygen removal on the effluents is computed. Potential chemical interactions between the gases and the ceramic electrolytes are analyzed and discussed.

High-pressure and high-temperature phase diagram for Fe0.9Ni0.1-H alloy

NASA Astrophysics Data System (ADS)

Shibazaki, Yuki; Terasaki, Hidenori; Ohtani, Eiji; Tateyama, Ryuji; Nishida, Keisuke; Funakoshi, Ken-ichi; Higo, Yuji

2014-03-01

Planetary cores are considered to consist of an iron-nickel (Fe-Ni) alloy and light elements and hydrogen is one of plausible light elements in the core. Here we have performed in situ X-ray diffraction experiments on an Fe0.9Ni0.1-H system up to 15.1 GPa and 1673 K, and investigated the effect of Ni on phase relations of FeHx under high pressure and high temperature. The experimental system in the present work was oversaturated with hydrogen. We found a face-center-cubic (fcc) phase (with hydrogen concentration up to x∼1) and a body-center-cubic (bcc) phase (x < 0.1) as stable phases. The partial melting was observed below 6 GPa. We could not observe a double-hexagonal-close-packed (dhcp) phase because of limitations in pressure and temperature conditions. The stability field of each phase of Fe0.9Ni0.1Hx was almost same as that of FeHx. The solidus of Fe0.9Ni0.1Hx was 500-700 K lower than the melting curve of Fe and its liquidus was 400-600 K lower than that of Fe in the pressure range of this study. Both the solidus and liquidus of Fe0.9Ni0.1Hx were depressed at around 3.5 GPa, as was the solidus of FeHx. The hydrogen contents in fcc-Fe0.9Ni0.1Hx just below solidus were slightly lower than those of fcc-FeHx, which suggests that nickel is likely to prevent dissolution of hydrogen into iron. Due to the lower hydrogen solubilities in Fe0.9Ni0.1 compared to Fe, the solidus of Fe0.9Ni0.1Hx is about 100-150 K higher than that of FeHx.

Hydrogen production with coal using a pulverization device

DOEpatents

Paulson, Leland E.

1989-01-01

A method for producing hydrogen from coal is described wherein high temperature steam is brought into contact with coal in a pulverizer or fluid energy mill for effecting a steam-carbon reaction to provide for the generation of gaseous hydrogen. The high temperature steam is utilized to drive the coal particles into violent particle-to-particle contact for comminuting the particulates and thereby increasing the surface area of the coal particles for enhancing the productivity of the hydrogen.

Powder Processing of High Temperature Cermets and Carbides at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Salvail, Pat; Panda, Binayak; Hickman, Robert R.

2007-01-01

The Materials and Processing Laboratory at NASA Marshall Space Flight Center is developing Powder Metallurgy (PM) processing techniques for high temperature cermet and carbide material consolidation. These new group of materials would be utilized in the nuclear core for Nuclear Thermal Rockets (NTR). Cermet materials offer several advantages for NTR such as retention of fission products and fuels, better thermal shock resistance, hydrogen compatibility, high thermal conductivity, and high strength. Carbide materials offer the highest operating temperatures but are sensitive to thermal stresses and are difficult to process. To support the effort, a new facility has been setup to process refractory metal, ceramic, carbides and depleted uranium-based powders. The facility inciudes inert atmosphere glove boxes for the handling of reactive powders, a high temperature furnace, and powder processing equipment used for blending, milling, and sieving. The effort is focused on basic research to identify the most promising compositions and processing techniques. Several PM processing methods including Cold and Hot Isostatic Pressing are being evaluated to fabricate samples for characterization and hot hydrogen testing.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rich Ciora; Paul KT Liu

2012-06-27

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

In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure.

PubMed

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

2018-03-31

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is known about the effects of high pressure hydrogen on the polymer sealing and barrier materials also found within these components. More study is required in order to determine the compatibility of common polymer materials found in the components of the hydrogen fuel delivery infrastructure with high pressure hydrogen. As a result, it is important to consider the changes in physical properties such as friction and wear in situ while the polymer is exposed to high pressure hydrogen. In this protocol, we present a method for testing the friction and wear properties of ethylene propylene diene monomer (EPDM) elastomer samples in a 28 MPa high pressure hydrogen environment using a custom-built in situ pin-on-flat linear reciprocating tribometer. Representative results from this testing are presented which indicate that the coefficient of friction between the EPDM sample coupon and steel counter surface is increased in high pressure hydrogen as compared to the coefficient of friction similarly measured in ambient air.

Isothermal Decomposition of Hydrogen Peroxide Dihydrate

NASA Technical Reports Server (NTRS)

Loeffler, M. J.; Baragiola, R. A.

2011-01-01

We present a new method of growing pure solid hydrogen peroxide in an ultra high vacuum environment and apply it to determine thermal stability of the dihydrate compound that forms when water and hydrogen peroxide are mixed at low temperatures. Using infrared spectroscopy and thermogravimetric analysis, we quantified the isothermal decomposition of the metastable dihydrate at 151.6 K. This decomposition occurs by fractional distillation through the preferential sublimation of water, which leads to the formation of pure hydrogen peroxide. The results imply that in an astronomical environment where condensed mixtures of H2O2 and H2O are shielded from radiolytic decomposition and warmed to temperatures where sublimation is significant, highly concentrated or even pure hydrogen peroxide may form.

Hydrogen storage methods.

PubMed

Züttel, Andreas

2004-04-01

Hydrogen exhibits the highest heating value per mass of all chemical fuels. Furthermore, hydrogen is regenerative and environmentally friendly. There are two reasons why hydrogen is not the major fuel of today's energy consumption. First of all, hydrogen is just an energy carrier. And, although it is the most abundant element in the universe, it has to be produced, since on earth it only occurs in the form of water and hydrocarbons. This implies that we have to pay for the energy, which results in a difficult economic dilemma because ever since the industrial revolution we have become used to consuming energy for free. The second difficulty with hydrogen as an energy carrier is its low critical temperature of 33 K (i.e. hydrogen is a gas at ambient temperature). For mobile and in many cases also for stationary applications the volumetric and gravimetric density of hydrogen in a storage material is crucial. Hydrogen can be stored using six different methods and phenomena: (1) high-pressure gas cylinders (up to 800 bar), (2) liquid hydrogen in cryogenic tanks (at 21 K), (3) adsorbed hydrogen on materials with a large specific surface area (at T<100 K), (4) absorbed on interstitial sites in a host metal (at ambient pressure and temperature), (5) chemically bonded in covalent and ionic compounds (at ambient pressure), or (6) through oxidation of reactive metals, e.g. Li, Na, Mg, Al, Zn with water. The most common storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa (200 bar). New lightweight composite cylinders have been developed which are able to withstand pressures up to 80 MPa (800 bar) and therefore the hydrogen gas can reach a volumetric density of 36 kg.m(-3), approximately half as much as in its liquid state. Liquid hydrogen is stored in cryogenic tanks at 21.2 K and ambient pressure. Due to the low critical temperature of hydrogen (33 K), liquid hydrogen can only be stored in open systems. The volumetric density of liquid hydrogen

Hydrogen storage methods

NASA Astrophysics Data System (ADS)

Züttel, Andreas

Hydrogen exhibits the highest heating value per mass of all chemical fuels. Furthermore, hydrogen is regenerative and environmentally friendly. There are two reasons why hydrogen is not the major fuel of today's energy consumption. First of all, hydrogen is just an energy carrier. And, although it is the most abundant element in the universe, it has to be produced, since on earth it only occurs in the form of water and hydrocarbons. This implies that we have to pay for the energy, which results in a difficult economic dilemma because ever since the industrial revolution we have become used to consuming energy for free. The second difficulty with hydrogen as an energy carrier is its low critical temperature of 33 K (i.e. hydrogen is a gas at ambient temperature). For mobile and in many cases also for stationary applications the volumetric and gravimetric density of hydrogen in a storage material is crucial. Hydrogen can be stored using six different methods and phenomena: (1) high-pressure gas cylinders (up to 800 bar), (2) liquid hydrogen in cryogenic tanks (at 21 K), (3) adsorbed hydrogen on materials with a large specific surface area (at T<100 K), (4) absorbed on interstitial sites in a host metal (at ambient pressure and temperature), (5) chemically bonded in covalent and ionic compounds (at ambient pressure), or (6) through oxidation of reactive metals, e.g. Li, Na, Mg, Al, Zn with water. The most common storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa (200 bar). New lightweight composite cylinders have been developed which are able to withstand pressures up to 80 MPa (800 bar) and therefore the hydrogen gas can reach a volumetric density of 36 kg.m-3, approximately half as much as in its liquid state. Liquid hydrogen is stored in cryogenic tanks at 21.2 K and ambient pressure. Due to the low critical temperature of hydrogen (33 K), liquid hydrogen can only be stored in open systems. The volumetric density of liquid hydrogen is

High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering

NASA Astrophysics Data System (ADS)

Arakawa, Yasuaki; Ueno, Kohei; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

2016-08-01

We have grown Mg-doped GaN films with low residual hydrogen concentration using a low-temperature pulsed sputtering deposition (PSD) process. The growth system is inherently hydrogen-free, allowing us to obtain high-purity Mg-doped GaN films with residual hydrogen concentrations below 5 × 1016 cm-3, which is the detection limit of secondary ion mass spectroscopy. In the Mg profile, no memory effect or serious dopant diffusion was detected. The as-deposited Mg-doped GaN films showed clear p-type conductivity at room temperature (RT) without thermal activation. The GaN film doped with a low concentration of Mg (7.9 × 1017 cm-3) deposited by PSD showed hole mobilities of 34 and 62 cm2 V-1 s-1 at RT and 175 K, respectively, which are as high as those of films grown by a state-of-the-art metal-organic chemical vapor deposition apparatus. These results indicate that PSD is a powerful tool for the fabrication of GaN-based vertical power devices.

Divacancy-hydrogen complexes in dislocation-free high-purity germanium. [Annealing, Hall effect, steady-state concentration energy dependence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haller, E.E.; Hubbard, G.S.; Hansen, W.L.

1976-09-01

A defect center with a single acceptor level at E/sub v/ + 0.08 eV appears in H/sub 2/-grown dislocation-free high-purity germanium. Its concentration changes reversibly upon annealing up to 650 K. By means of Hall-effect and conductivity measurements over a large temperature range the temperature dependence of the steady-state concentration between 450 and 720 K as well as the transients following changes in temperature were determined. The observed acceptor level is attributed to the divacancy-hydrogen complex V/sub 2/H. The complex reacts with hydrogen, dissolved in the Ge lattice or stored in traps, according to V/sub 2/H + H reversible V/submore » 2/H/sub 2/. An energy level associated with the divacancy-dihydrogen complex was not observed. These results are in good agreement with the idea that hydrogen in germanium forms a ''very deep donor'' (i.e., the energy level lies inside the valence band).« less

An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron–Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications

PubMed Central

Tu, Yun; Ye, Lin; Zhou, Shao-Ping; Tu, Shan-Tung

2017-01-01

Local strain measurements are considered as an effective method for structural health monitoring of high-temperature components, which require accurate, reliable and durable sensors. To develop strain sensors that can be used in higher temperature environments, an improved metal-packaged strain sensor based on a regenerated fiber Bragg grating (RFBG) fabricated in hydrogen (H2)-loaded boron–germanium (B–Ge) co-doped photosensitive fiber is developed using the process of combining magnetron sputtering and electroplating, addressing the limitation of mechanical strength degradation of silica optical fibers after annealing at a high temperature for regeneration. The regeneration characteristics of the RFBGs and the strain characteristics of the sensor are evaluated. Numerical simulation of the sensor is conducted using a three-dimensional finite element model. Anomalous decay behavior of two regeneration regimes is observed for the FBGs written in H2-loaded B–Ge co-doped fiber. The strain sensor exhibits good linearity, stability and repeatability when exposed to constant high temperatures of up to 540 °C. A satisfactory agreement is obtained between the experimental and numerical results in strain sensitivity. The results demonstrate that the improved metal-packaged strain sensors based on RFBGs in H2-loaded B–Ge co-doped fiber provide great potential for high-temperature applications by addressing the issues of mechanical integrity and packaging. PMID:28241465

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

NASA Astrophysics Data System (ADS)

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.

Metal-Coated Optical Fibers for High Temperature Applications

NASA Technical Reports Server (NTRS)

Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

1996-01-01

This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

Effects of Internal and External Hydrogen on Inconel 718

NASA Technical Reports Server (NTRS)

Walter, R. J.; Frandsen, J. D.

1999-01-01

Internal hydrogen embrittlement (IHE) and hydrogen environment embrittlement (HEE) tensile and bend crack growth tests were performed on Inconel 718. For the IHE tests, the specimens were precharged to approximately 90 ppm hydrogen by exposure to 34.5 MPa H2 at 650 C. The HEE tests were performed in 34.5 MPa H2. Parameters evaluated were test temperature, strain rate for smooth and notch specimen geometries. The strain rate effect was very significant at ambient temperature for both IHE and HEE and decreased with increasing temperatures. For IHE, the strain rate effect was neglible at 260'C, and for HEE the strain rate effect was neglible at 400 C. At low temperatures, IHE was more severe than HEE, and at high temperatures HEE was more severe than IHE with a cross over temperature about 350 C. At 350 C, the equilibrium hydrogen concentration in Inconel 718 is about 50% lower than the hydrogen content of the precharged IHE specimens. Dislocation hydrogen sweeping of surface absorbed hydrogen was the likely transport mechanism for increasing the hydrogen concentration in the HEE tests sufficiently to produce the same degree of embrittlement as that of the more highly hydrogen charged IHE specimens. The main IHE fracture characteristic was formation of large, brittle flat facets, which decreased with increasing test temperature. The IHE fracture matrix surrounding the large facets ranged between brittle fine faceted to microvoid ductility depending upon strain rate, specimen geometry as well as temperature. The HEE fractures were characteristically fine featured, transgranular and brittle with a significant portion forming a "saw tooth" crystallographic pattern. Both IHE and HEE fractures were predominantly along the {1 1 1) slip and twin boundaries. With respect to embrittlement mechanism, it was postulated that dislocation hydrogen sweeping and hydrogen enhanced localized plasticity were active in HEE and IHE for concentrating hydrogen along (1 1 1) slip and twin

Demonstrated survivability of a high temperature optical fiber cable on a 1500 pound thrust rocket chamber

NASA Technical Reports Server (NTRS)

Sovie, Amy L.

1992-01-01

A demonstration of the ability of an existing optical fiber cable to survive the harsh environment of a rocket engine was performed at the NASA Lewis Research Center. The intent of this demonstration was to prove the feasibility of applying fiber optic technology to rocket engine instrumentation systems. Extreme thermal transient tests were achieved by wrapping a high temperature optical fiber, which was cablized for mechanical robustness, around the combustion chamber outside wall of a 1500 lb Hydrogen-Oxygen rocket engine. Additionally, the fiber was wrapped around coolant inlet pipes which were subject to near liquid hydrogen temperatures. Light from an LED was sent through the multimode fiber, and output power was monitored as a function of time while the engine was fired. The fiber showed no mechanical damage after 419 firings during which it was subject to transients from 30 K to 350 K, and total exposure time to near liquid hydrogen temperatures in excess of 990 seconds. These extreme temperatures did cause attenuation greater than 3 dB, but the signal was fully recovered at room temperature. This experiment demonstrates that commercially available optical fiber cables can survive the environment seen by a typical rocket engine instrumentation system, and disclose a temperature-dependent attenuation observed during exposure to near liquid hydrogen temperatures.

Highly hydrogenated graphene through microwave exfoliation of graphite oxide in hydrogen plasma: towards electrochemical applications.

PubMed

Eng, Alex Yong Sheng; Sofer, Zdenek; Šimek, Petr; Kosina, Jiri; Pumera, Martin

2013-11-11

Hydrogenated graphenes exhibit a variety of properties with potential applications in devices, ranging from a tunable band gap to fluorescence, ferromagnetism, and the storage of hydrogen. We utilize a one-step microwave-irradiation process in hydrogen plasma to create highly hydrogenated graphene from graphite oxides. The procedure serves the dual purposes of deoxygenation and concurrent hydrogenation of the carbon backbone. The effectiveness of the hydrogenation process is investigated on three different graphite oxides (GOs), which are synthesized by using the Staudenmaier, Hofmann, and Hummers methods. A systematic characterization of our hydrogenated graphenes is performed using UV/Vis spectroscopy, SEM, AFM, Raman spectroscopy, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), combustible elemental analysis, and electrical conductivity measurements. The highest hydrogenation extent is observed in hydrogenated graphene produced from the Hummers-method GO, with a hydrogen content of 19 atomic % in the final product. In terms of the removal of oxygen groups, microwave exfoliation yields graphenes with very similar oxygen contents despite differences in their parent GOs. In addition, we examine the prospective application of hydrogenated graphenes as electrochemical transducers through a cyclic voltammetry (CV) study. The highly hydrogenated graphenes exhibit fast heterogeneous electron-transfer rates, suggestive of their suitability for electrochemical applications in electrodes, supercapacitors, batteries, and sensors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 materialsmore » 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

Low-Cost High-Pressure Hydrogen Generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cropley, Cecelia C.; Norman, Timothy J.

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

Influence of gaseous hydrogen on metals

NASA Technical Reports Server (NTRS)

Walter, R. J.; Chandler, W. T.

1973-01-01

Tensile, fracture toughness, threshold stress intensity for sustained-load crack growth, and cyclic and sustained load crack growth rate measurements were performed on a number of alloys in high-pressure hydrogen and helium environments. The results of tensile tests performed in 34.5 MN/m2 (5000 psi) hydrogen indicated that Inconel 625 was considerable embrittled at ambient temperature but was not embrittled at 144 K (-200 F). The tensile properties of AISI 321 stainless steel were slightly reduced at ambient temperature and 144 K (-200 F). The tensile properties of Ti-5Al-2.5 Sn ELI were essentially unaffected by hydrogen at 144 K (-200 F). OFHC copper was not embrittled by hydrogen at ambient temperature or at 144 K (-200 F).

Toward hydrogen detection at room temperature with printed ZnO nanoceramics films activated with halogen lighting

NASA Astrophysics Data System (ADS)

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.

Possibility of high temperature superconducting phases in PdH

NASA Astrophysics Data System (ADS)

Tripodi, Paolo; Di Gioacchino, Daniele; Borelli, Rodolfo; Vinko, Jenny Darja

2003-05-01

Possible new superconducting phases with a high critical transition temperature (Tc) have been found in stable palladium-hydrogen (PdHx) samples for stoichiometric ratio x=H/Pd⩾1, in addition to the well-known low critical transition temperature (0⩽Tc⩽9) when x is in the range (0.75⩽x⩽1.00). Possible new measured superconducting phases with critical temperature in the range 51⩽Tc⩽295 K occur. This Tc varies considerably with every milli part of x when x exceeds unit. A superconducting critical current density Jc⩾6.1×104 A cm-2 has been measured at 77 K with HDC=0 T.

Hydrogen axion star: metallic hydrogen bound to a QCD axion BEC

DOE PAGES

Bai, Yang; Barger, Vernon; Berger, Joshua

2016-12-23

As a cold dark matter candidate, the QCD axion may form Bose-Einstein condensates, called axion stars, with masses around 10 -11M⊙ . In this paper, we point out that a brand new astrophysical object, a Hydrogen Axion Star (HAS), may well be formed by ordinary baryonic matter becoming gravitationally bound to an axion star. Here, we study the properties of the HAS and nd that the hydrogen cloud has a high pressure and temperature in the center and is likely in the liquid metallic hydrogen state. Because of the high particle number densities for both the axion star and themore » hydrogen cloud, the feeble interaction between axion and hydrogen can still generate enough internal power, around 10 13W (m a/=5 meV) 4, to make these objects luminous point sources. Furthermore, high resolution ultraviolet, optical and infrared telescopes can discover HAS via black-body radiation.« less

Hydrogen axion star: metallic hydrogen bound to a QCD axion BEC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Yang; Barger, Vernon; Berger, Joshua

As a cold dark matter candidate, the QCD axion may form Bose-Einstein condensates, called axion stars, with masses around 10 -11M⊙ . In this paper, we point out that a brand new astrophysical object, a Hydrogen Axion Star (HAS), may well be formed by ordinary baryonic matter becoming gravitationally bound to an axion star. Here, we study the properties of the HAS and nd that the hydrogen cloud has a high pressure and temperature in the center and is likely in the liquid metallic hydrogen state. Because of the high particle number densities for both the axion star and themore » hydrogen cloud, the feeble interaction between axion and hydrogen can still generate enough internal power, around 10 13W (m a/=5 meV) 4, to make these objects luminous point sources. Furthermore, high resolution ultraviolet, optical and infrared telescopes can discover HAS via black-body radiation.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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:more » 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.« less

On the room-temperature phase diagram of high pressure hydrogen: an ab initio molecular dynamics perspective and a diffusion Monte Carlo study.

PubMed

Chen, Ji; Ren, Xinguo; Li, Xin-Zheng; Alfè, Dario; Wang, Enge

2014-07-14

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.

Hydrogen Permeability of Polymer Matrix Composites at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Grenoble, Ray W.; Gates, Thomas S

2005-01-01

This paper presents experimental methods and results of an ongoing study of the correlation between damage state and hydrogen gas permeability of laminated composite materials under mechanical strains and thermal loads. A specimen made from IM-7/977-2 composite material has been mechanically cycled at room temperature to induce microcrack damage. Crack density and tensile modulus were observed as functions of number of cycles. Damage development was found to occur most quickly in the off-axis plies near the outside of the laminate. Permeability measurements were made after 170,000 cycles and 430,000 cycles. Leak rate was found to depend on applied mechanical strain, crack density, and test temperature.

Hydrogen Annealing Of Single-Crystal Superalloys

NASA Technical Reports Server (NTRS)

Smialek, James L.; Schaeffer, John C.; Murphy, Wendy

1995-01-01

Annealing at temperature equal to or greater than 2,200 degrees F in atmosphere of hydrogen found to increase ability of single-crystal superalloys to resist oxidation when subsequently exposed to oxidizing atmospheres at temperatures almost as high. Supperalloys in question are principal constituents of hot-stage airfoils (blades) in aircraft and ground-based turbine engines; also used in other high-temperature applications like chemical-processing plants, coal-gasification plants, petrochemical refineries, and boilers. Hydrogen anneal provides resistance to oxidation without decreasing fatigue strength and without need for coating or reactive sulfur-gettering constituents. In comparison with coating, hydrogen annealing costs less. Benefits extend to stainless steels, nickel/chromium, and nickel-base alloys, subject to same scale-adhesion and oxidation-resistance considerations, except that scale is chromia instead of alumina.

Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability.

PubMed

Bao, Di; Gao, Peng; Shen, Xiande; Chang, Cheng; Wang, Longqiang; Wang, Ying; Chen, Yujin; Zhou, Xiaoming; Sun, Shuchao; Li, Guobao; Yang, Piaoping

2014-02-26

The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process.

Hydrogen-rich scandium compounds at high pressures

NASA Astrophysics Data System (ADS)

Abe, Kazutaka

2017-10-01

Scandium hydrides at high pressures have been investigated by using ab initio density functional calculations. Although the stable scandium hydride so far known to have the highest content rate of hydrogen is ScH3, other more hydrogen-rich compounds are found to be possible at high pressures. These are ScH4 in the I 4 /m m m structure above 160 GPa, ScH6 in the P 63/m m c structure from 135 to 265 GPa, and ScH6 in the I m 3 ¯m structure above 265 GPa. The three phases are all metallic, and the superconducting transition temperatures estimated from the extended McMillan equation are 67 K in the I 4 /m m m ScH4 at 195 GPa, 63 K in the P 63/m m c ScH6 at 145 GPa, and 130 K in the I m 3 ¯m ScH6 at 285 GPa. While the I 4 /m m m tetrahydride and the I m 3 ¯m hexahydride were similarly predicted for yttrium (another group-3 element), the P 63/m m c hexahydride is possible only for scandium. The smaller atomic size of scandium stabilizes the P 63/m m c structure, and other nearby d -block elements, whose atomic sizes are smaller or comparable, might be likewise capable of forming such polyhydrides.

Li{sub 4}FeH{sub 6}: Iron-containing complex hydride with high gravimetric hydrogen density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saitoh, Hiroyuki, E-mail: cyto@spring8.or.jp; Takagi, Shigeyuki; Matsuo, Motoaki

2014-07-01

Li{sub 4}FeH{sub 6}, which has the highest gravimetric hydrogen density of iron-containing complex hydrides reported so far, is synthesized by hydrogenation of a powder mixture of iron and LiH above 6.1 GPa at 900 °C. In situ synchrotron radiation X-ray diffraction measurements reveal that while kinetics require high temperature and thus high pressure for the synthesis, Li{sub 4}FeH{sub 6} is expected to be thermodynamically stable slightly below room temperature at ambient pressure; further synthetic studies to suppress the kinetic effects may enable us to synthesize Li{sub 4}FeH{sub 6} at moderate pressures. Li{sub 4}FeH{sub 6} can be recovered at ambient conditions wheremore » Li{sub 4}FeH{sub 6} is metastable.« less

Order in dense hydrogen at low temperatures

PubMed Central

Edwards, B.; Ashcroft, N. W.

2004-01-01

By increase in density, impelled by pressure, the electronic energy bands in dense hydrogen attain significant widths. Nevertheless, arguments can be advanced suggesting that a physically consistent description of the general consequences of this electronic structure can still be constructed from interacting but state-dependent multipoles. These reflect, in fact self-consistently, a disorder-induced localization of electron states partially manifesting the effects of proton dynamics; they retain very considerable spatial inhomogeneity (as they certainly do in the molecular limit). This description, which is valid provided that an overall energy gap has not closed, leads at a mean-field level to the expected quadrupolar coupling, but also for certain structures to the eventual emergence of dipolar terms and their coupling when a state of broken charge symmetry is developed. A simple Hamiltonian incorporating these basic features then leads to a high-density, low-temperature phase diagram that appears to be in substantial agreement with experiment. In particular, it accounts for the fact that whereas the phase I–II phase boundary has a significant isotope dependence, the phase II–III boundary has very little. PMID:15028839

High pressure/high temperature thermogravimetric apparatus. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calo, J.M.; Suuberg, E.M.

1999-12-01

The purpose of this instrumentation grant was to acquire a state-of-the-art, high pressure, high temperature thermogravimetric apparatus (HP/HT TGA) system for the study of the interactions between gases and carbonaceous solids for the purpose of solving problems related to coal utilization and applications of carbon materials. The instrument that we identified for this purpose was manufactured by DMT (Deutsche Montan Technologies)--Institute of Cokemaking and Coal Chemistry of Essen, Germany. Particular features of note include: Two reactors: a standard TGA reactor, capable of 1100 C at 100 bar; and a high temperature (HT) reactor, capable of operation at 1600 C andmore » 100 bar; A steam generator capable of generating steam to 100 bar; Flow controllers and gas mixing system for up to three reaction gases, plus a separate circuit for steam, and another for purge gas; and An automated software system for data acquisition and control. The HP/TP DMT-TGA apparatus was purchased in 1996 and installed and commissioned during the summer of 1996. The apparatus was located in Room 128 of the Prince Engineering Building at Brown University. A hydrogen alarm and vent system were added for safety considerations. The system has been interfaced to an Ametek quadruple mass spectrometer (MA 100), pumped by a Varian V250 turbomolecular pump, as provided for in the original proposed. With this capability, a number of gas phase species of interest can be monitored in a near-simultaneous fashion. The MS can be used in a few different modes. During high pressure, steady-state gasification experiments, it is used to sample, measure, and monitor the reactant/product gases. It can also be used to monitor gas phase species during nonisothermal temperature programmed reaction (TPR) or temperature programmed desorption (TPD) experiments.« less

Evidence for a first-order liquid-liquid transition in high-pressure hydrogen from ab initio simulations.

PubMed

Morales, Miguel A; Pierleoni, Carlo; Schwegler, Eric; Ceperley, D M

2010-07-20

Using quantum simulation techniques based on either density functional theory or quantum Monte Carlo, we find clear evidence of a first-order transition in liquid hydrogen, between a low conductivity molecular state and a high conductivity atomic state. Using the temperature dependence of the discontinuity in the electronic conductivity, we estimate the critical point of the transition at temperatures near 2,000 K and pressures near 120 GPa. Furthermore, we have determined the melting curve of molecular hydrogen up to pressures of 200 GPa, finding a reentrant melting line. The melting line crosses the metalization line at 700 K and 220 GPa using density functional energetics and at 550 K and 290 GPa using quantum Monte Carlo energetics.

Role of Hydrogen in High-Yield Growth of Boron Nitride Nanotubes at Atmospheric Pressure by Induction Thermal Plasma.

PubMed

Kim, Keun Su; Couillard, Martin; Shin, Homin; Plunkett, Mark; Ruth, Dean; Kingston, Christopher T; Simard, Benoit

2018-01-23

We recently demonstrated scalable manufacturing of boron nitride nanotubes (BNNTs) directly from hexagonal BN (hBN) powder by using induction thermal plasma, with a high-yield rate approaching 20 g/h. The main finding was that the presence of hydrogen is crucial for the high-yield growth of BNNTs. Here we investigate the detailed role of hydrogen by numerical modeling and in situ optical emission spectroscopy (OES) and reveal that both the thermofluidic fields and chemical pathways are significantly altered by hydrogen in favor of rapid growth of BNNTs. The numerical simulation indicated improved particle heating and quenching rates (∼10 5 K/s) due to the high thermal conductivity of hydrogen over the temperature range of 3500-4000 K. These are crucial for the complete vaporization of the hBN feedstock and rapid formation of nanosized B droplets for the subsequent BNNT growth. Hydrogen is also found to extend the active BNNT growth zone toward the reactor downstream, maintaining the gas temperature above the B solidification limit (∼2300 K) by releasing the recombination heat of H atoms, which starts at 3800 K. The OES study revealed that H radicals also stabilize B or N radicals from dissociation of the feedstock as BH and NH radicals while suppressing the formation of N 2 or N 2 + species. Our density functional theory calculations showed that such radicals can provide faster chemical pathways for the formation of BN compared with relatively inert N 2 .

Multilayer graphane synthesized under high hydrogen pressure

DOE PAGES

Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; ...

2015-12-19

A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis inmore » the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.« less

Hydrogen and nitrogen turboexpanders with high gas expansion ratios

NASA Astrophysics Data System (ADS)

Davydenkov, I. A.; Davydov, A. B.; Perestoronin, G. A.

The paper examines the design features of a four-stage hydrogen turboexpander with an expansion ratio of 80 and two-stage nitrogen turboexpander with an expansion ratio of 120. The test results obtained under imitations in air are presented. The adiabatic efficiency of the hydrogen and nitrogen turboexpanders under operating conditions has reached 0,65 and 0, 78, respectively. The use of high-performance high-pressure hydrogen and nitrogen turboexpanders has considerably increased the capacity of a large hydrogen liquefier.

Vacuum ultraviolet photolysis of hydrogenated amorphous carbons. III. Diffusion of photo-produced H2 as a function of temperature

NASA Astrophysics Data System (ADS)

Martín-Doménech, R.; Dartois, E.; Muñoz Caro, G. M.

2016-06-01

Context. Hydrogenated amorphous carbon (a-C:H) has been proposed as one of the carbonaceous solids detected in the interstellar medium. Energetic processing of the a-C:H particles leads to the dissociation of the C-H bonds and the formation of hydrogen molecules and small hydrocarbons. Photo-produced H2 molecules in the bulk of the dust particles can diffuse out to the gas phase and contribute to the total H2 abundance. Aims: We have simulated this process in the laboratory with plasma-produced a-C:H and a-C:D analogs under astrophysically relevant conditions to investigate the dependence of the diffusion as a function of temperature. Methods: Experimental simulations were performed in a high-vacuum chamber, with complementary experiments carried out in an ultra-high-vacuum chamber. Plasma-produced a-C:H and a-C:D analogs were UV-irradiated using a microwave-discharged hydrogen flow lamp. Molecules diffusing to the gas-phase were detected by a quadrupole mass spectrometer, providing a measurement of the outgoing H2 or D2 flux. By comparing the experimental measurements with the expected flux from a one-dimensional diffusion model, a diffusion coefficient D could be derived for experiments carried out at different temperatures. Results: Dependence on the diffusion coefficient D with the temperature followed an Arrhenius-type equation. The activation energy for the diffusion process was estimated (ED(H2) = 1660 ± 110 K, ED(D2) = 2090 ± 90 K), as well as the pre-exponential factor (D0(H2) = 0.0007 cm2 s-1, D0(D2) = 0.0045 cm2 s-1). Conclusions: The strong decrease of the diffusion coefficient at low dust particle temperatures exponentially increases the diffusion times in astrophysical environments. Therefore, transient dust heating by cosmic rays needs to be invoked for the release of the photo-produced H2 molecules in cold photon-dominated regions, where destruction of the aliphatic component in hydrogenated amorphous carbons most probably takes place.

High pressure-high temperature phase diagram of an energetic crystal: Dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50)

DOE PAGES

Dreger, Z. A.; Breshike, C. J.; Gupta, Y. M.

2017-05-08

Raman spectroscopy was used to examine the high pressure-high temperature structural and chemical stability of an insensitive, high-performance energetic crystal – dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50). The phase diagram was determined over 8 GPa and (293-760) K. Under isobaric heating, the melting/decomposition of TKX-50 is preceded by a transformation to two consecutive high-temperature intermediates; a lower-temperature intermediate – diammonium 5,5’-bistetrazole-1,1'-diolate, and a higher-temperature intermediate – dihydroxylammonium 5,5'-bistetrazolate and/or diammonium 5,5'-bistetrazolate. Pressure strongly increases the transition temperatures for these transformations and subsequent decomposition. As a result, significant increase in the chemical stability of TKX-50 and intermediates with pressure was attributed to a suppressionmore » of hydrogen-transfer.« less

An in situ tensile test apparatus for polymers in high pressure hydrogen

DOE PAGES

Alvine, Kyle J.; Kafentzis, Tyler A.; Pitman, Stan G.; ...

2014-10-31

Degradation of material properties by high-pressure hydrogen is an important factor in determining the safety and reliability of materials used in high-pressure hydrogen storage and delivery. Hydrogen damage mechanisms have a time dependence that is linked to hydrogen outgassing after exposure to the hydrogen atmosphere that makes ex situ measurements of mechanical properties problematic. Designing in situ measurement instruments for high-pressure hydrogen is challenging due to known hydrogen incompatibility with many metals and standard high-power motor materials like Nd. Here we detail the design and operation of a solenoid based in situ tensile tester under high-pressure hydrogen environments up tomore » 5,000 psi. Here, modulus data from high-density polyethylene (HDPE) samples tested under high-pressure hydrogen are also reported as compared to baseline measurements taken in air.« less

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

PubMed

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.

Degradation by water vapor of hydrogenated amorphous silicon oxynitride films grown at low temperature.

PubMed

Lee, Hyung-Ik; Park, Jong-Bong; Xianyu, Wenxu; Kim, Kihong; Chung, Jae Gwan; Kyoung, Yong Koo; Byun, Sunjung; Yang, Woo Young; Park, Yong Young; Kim, Seong Min; Cho, Eunae; Shin, Jai Kwang

2017-10-26

We report on the degradation process by water vapor of hydrogenated amorphous silicon oxynitride (SiON:H) films deposited by plasma-enhanced chemical vapor deposition at low temperature. The stability of the films was investigated as a function of the oxygen content and deposition temperature. Degradation by defects such as pinholes was not observed with transmission electron microscopy. However, we observed that SiON:H film degrades by reacting with water vapor through only interstitial paths and nano-defects. To monitor the degradation process, the atomic composition, mass density, and fully oxidized thickness were measured by using high-resolution Rutherford backscattering spectroscopy and X-ray reflectometry. The film rapidly degraded above an oxygen composition of ~27 at%, below a deposition temperature of ~150 °C, and below an mass density of ~2.15 g/cm 3 . This trend can be explained by the extents of porosity and percolation channel based on the ring model of the network structure. In the case of a high oxygen composition or low temperature, the SiON:H film becomes more porous because the film consists of network channels of rings with a low energy barrier.

Magnetic suspension using high temperature superconducting cores

NASA Technical Reports Server (NTRS)

Scurlock, R. G.

1992-01-01

The development of YBCO high temperature superconductors, in wire and tape forms, is rapidly approaching the point where the bulk transport current density j vs magnetic field H characteristics with liquid nitrogen cooling will enable its use in model cores. On the other hand, BSCCO high temperature superconductor in wire form has poor j-H characteristics at 77 K today, although with liquid helium or hydrogen cooling, it appears to be superior to NbTi superconductor. Since liquid nitrogen cooling is approx. 100 times cheaper than liquid helium cooling, the use of YBCO is very attractive for use in magnetic suspension. The design is discussed of a model core to accommodate lift and drag loads up to 6000 and 3000 N respectively. A comparison is made between the design performance of a liquid helium cooled NbTi (or BSCCO) superconducting core and a liquid nitrogen cooled YBCO superconducting core.

Porous nuclear fuel element for high-temperature gas-cooled nuclear reactors

DOEpatents

Youchison, Dennis L [Albuquerque, NM; Williams, Brian E [Pacoima, CA; Benander, Robert E [Pacoima, CA

2011-03-01

Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere

NASA Astrophysics Data System (ADS)

Leenaarts, J.; Carlsson, M.; Hansteen, V.; Rutten, R. J.

2007-10-01

Context: The ionization of hydrogen in the solar chromosphere and transition region does not obey LTE or instantaneous statistical equilibrium because the timescale is long compared with important hydrodynamical timescales, especially of magneto-acoustic shocks. Since the pressure, temperature, and electron density depend sensitively on hydrogen ionization, numerical simulation of the solar atmosphere requires non-equilibrium treatment of all pertinent hydrogen transitions. The same holds for any diagnostic application employing hydrogen lines. Aims: To demonstrate the importance and to quantify the effects of non-equilibrium hydrogen ionization, both on the dynamical structure of the solar atmosphere and on hydrogen line formation, in particular Hα. Methods: We implement an algorithm to compute non-equilibrium hydrogen ionization and its coupling into the MHD equations within an existing radiation MHD code, and perform a two-dimensional simulation of the solar atmosphere from the convection zone to the corona. Results: Analysis of the simulation results and comparison to a companion simulation assuming LTE shows that: a) non-equilibrium computation delivers much smaller variations of the chromospheric hydrogen ionization than for LTE. The ionization is smaller within shocks but subsequently remains high in the cool intershock phases. As a result, the chromospheric temperature variations are much larger than for LTE because in non-equilibrium, hydrogen ionization is a less effective internal energy buffer. The actual shock temperatures are therefore higher and the intershock temperatures lower. b) The chromospheric populations of the hydrogen n = 2 level, which governs the opacity of Hα, are coupled to the ion populations. They are set by the high temperature in shocks and subsequently remain high in the cool intershock phases. c) The temperature structure and the hydrogen level populations differ much between the chromosphere above photospheric magnetic elements

High temperature ceramic composition for hydrogen retention

DOEpatents

Webb, R.W.

1974-01-01

A ceramic coating for H retention in fuel elements is described. The coating has relatively low thermal neutron cross section, is not readily reduced by H at 1500 deg F, is adherent to the fuel element base metal, and is stable at reactor operating temperatures. (JRD)

Purification of Hydrogen

DOEpatents

Newton, A S

1950-12-05

Disclosed is a process for purifying hydrogen containing various gaseous impurities by passing the hydrogen over a large surface of uranium metal at a temperature above the decomposition temperature of uranium hydride, and below the decomposition temperature of the compounds formed by the combination of the uranium with the impurities in the hydrogen.

Hydrogen passivation of silicon(100) used as templates for low-temperature epitaxy and oxidation

NASA Astrophysics Data System (ADS)

Atluri, Vasudeva Prasad

Epitaxial growth, oxidation and ohmic contacts require surfaces as free as possible of physical defects and chemical contaminants, especially, oxygen and hydrocarbons. Wet chemical cleaning typically involves a RCA clean to remove contaminants by stripping the native oxide and regrowing a chemical oxide with only trace levels of carbon and metallic impurities. Low temperature epitaxy, T<800sp° C, limits the thermal budget for the desorption of impurities and surface oxides, and can be performed on processed structures. But, silicon dioxide cannot be desorbed at temperatures lower than 800sp°C. Recently, hydrogen passivation of Si(111) has been reported to produce stable and ordered surfaces at low temperatures. Hydrogen can then be desorbed between 200sp°C and 600sp°C prior to deposition. In this work, Si(100) is passivated via a solution of hydrofluoric acid in alcohol (methanol, ethanol, or isopropyl alcohol) with HF concentrations between 0.5 to 10%. A rinse in water or alcohol is performed after etching to remove excess fluorine. This work investigates wet chemical cleaning of Si(100) to produce ordered, hydrogen-terminated, oxygen- and carbon-free surfaces to be used as templates for low temperature epitaxial growth and rapid thermal oxidation. Ion beam analysis, Tapping mode atomic force microscopy, Fourier transform infrared spectroscopy, Secondary ion mass spectroscopy, Chemical etching, Capacitance-voltage measurements and Ellipsometry are used to measure, at the surface and interface, impurities concentration, residual disorder, crystalline order, surface topography, roughness, chemical composition, defects density, electrical characteristics, thickness, and refractive index as a function of cleaning conditions for homoepitaxial silicon growth and oxidation. The wetting characteristics of the Si(100) surfaces are measured with a tilting plate technique. Different materials are analyzed by ion beam analysis for use as hydrogen standards in elastic

High specific energy, high capacity nickel-hydrogen cell design

NASA Technical Reports Server (NTRS)

Wheeler, James R.

1993-01-01

A 3.5 inch rabbit-ear-terminal nickel-hydrogen cell has been designed and tested to deliver high capacity at a C/1.5 discharge rate. Its specific energy yield of 60.6 wh/kg is believed to be the highest yet achieved in a slurry-process nickel-hydrogen cell, and its 10 C capacity of 113.9 AH the highest capacity yet made at a discharge rate this high in the 3.5 inch diameter size. The cell also demonstrated a pulse capability of 180 amps for 20 seconds. Specific cell parameters, performance, and future test plans are described.

Hydrogenation and hydrogen intercalation of hexagonal boron nitride on Ni(1 1 1): reactivity and electronic structure

NASA Astrophysics Data System (ADS)

Späth, F.; Gebhardt, J.; Düll, F.; Bauer, U.; Bachmann, P.; Gleichweit, C.; Görling, A.; Steinrück, H.-P.; Papp, C.

2017-09-01

We investigate the reactivity of hexagonal boron nitride (h-BN) on a Ni(1 1 1) single crystal towards atomic hydrogen over a wide exposure range. Near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy (XPS) show that for low hydrogen exposures hydrogenation of the h-BN sheet is found. In contrast, intercalation of hydrogen between h-BN and the Ni(1 1 1) substrate occurs for high exposures. For intermediate regimes, a mixture of intercalation and hydrogenation is observed. From temperature-programmed desorption and temperature-programmed XPS experiments, we conclude that the hydrogen covalently bound to h-BN is rather stable with a desorption temperature of 600 K, while intercalated hydrogen is desorbing already at 390 K. Further insight into the structural arrangements and the thermodynamics of the system is obtained by comparing our experimental results with extensive density-functional theory calculations. Together with ultraviolet photoelectron spectroscopy measurements, the calculations provide detailed insight into the influence of hydrogenation on the electronic structure of h-BN.

ZIF-8 immobilized nickel nanoparticles: highly effective catalysts for hydrogen generation from hydrolysis of ammonia borane.

PubMed

Li, Pei-Zhou; Aranishi, Kengo; Xu, Qiang

2012-03-28

Highly dispersed Ni nanoparticles have been successfully immobilized by the zeolitic metal-organic framework ZIF-8 via sequential deposition-reduction methods, which show high catalytic activity and long durability for hydrogen generation from hydrolysis of aqueous ammonia borane (NH(3)BH(3)) at room temperature. This journal is © The Royal Society of Chemistry 2012

Constitutive and damage material modeling in a high pressure hydrogen environment

NASA Technical Reports Server (NTRS)

Russell, D. A.; Fritzemeier, L. G.

1991-01-01

Numerous components in reusable space propulsion systems such as the SSME are exposed to high pressure gaseous hydrogen environments. Flow areas and passages in the fuel turbopump, fuel and oxidizer preburners, main combustion chamber, and injector assembly contain high pressure hydrogen either high in purity or as hydrogen rich steam. Accurate constitutive and damage material models applicable to high pressure hydrogen environments are therefore needed for engine design and analysis. Existing constitutive and cyclic crack initiation models were evaluated only for conditions of oxidizing environments. The main objective is to evaluate these models for applicability to high pressure hydrogen environments.

High yields of hydrogen production from methanol steam reforming with a cross-U type reactor

PubMed Central

Zhang, Shubin; Chen, Junyu; Zhang, Xuelin; Liu, Xiaowei

2017-01-01

This paper presents a numerical and experimental study on the performance of a methanol steam reformer integrated with a hydrogen/air combustion reactor for hydrogen production. A CFD-based 3D model with mass and momentum transport and temperature characteristics is established. The simulation results show that better performance is achieved in the cross-U type reactor compared to either a tubular reactor or a parallel-U type reactor because of more effective heat transfer characteristics. Furthermore, Cu-based micro reformers of both cross-U and parallel-U type reactors are designed, fabricated and tested for experimental validation. Under the same condition for reforming and combustion, the results demonstrate that higher methanol conversion is achievable in cross-U type reactor. However, it is also found in cross-U type reactor that methanol reforming selectivity is the lowest due to the decreased water gas shift reaction under high temperature, thereby carbon monoxide concentration is increased. Furthermore, the reformed gas generated from the reactors is fed into a high temperature proton exchange membrane fuel cell (PEMFC). In the test of discharging for 4 h, the fuel cell fed by cross-U type reactor exhibits the most stable performance. PMID:29121067

High yields of hydrogen production from methanol steam reforming with a cross-U type reactor.

PubMed

Zhang, Shubin; Zhang, Yufeng; Chen, Junyu; Zhang, Xuelin; Liu, Xiaowei

2017-01-01

This paper presents a numerical and experimental study on the performance of a methanol steam reformer integrated with a hydrogen/air combustion reactor for hydrogen production. A CFD-based 3D model with mass and momentum transport and temperature characteristics is established. The simulation results show that better performance is achieved in the cross-U type reactor compared to either a tubular reactor or a parallel-U type reactor because of more effective heat transfer characteristics. Furthermore, Cu-based micro reformers of both cross-U and parallel-U type reactors are designed, fabricated and tested for experimental validation. Under the same condition for reforming and combustion, the results demonstrate that higher methanol conversion is achievable in cross-U type reactor. However, it is also found in cross-U type reactor that methanol reforming selectivity is the lowest due to the decreased water gas shift reaction under high temperature, thereby carbon monoxide concentration is increased. Furthermore, the reformed gas generated from the reactors is fed into a high temperature proton exchange membrane fuel cell (PEMFC). In the test of discharging for 4 h, the fuel cell fed by cross-U type reactor exhibits the most stable performance.

An Analysis of Methanol and Hydrogen Production via High-Temperature Electrolysis Using the Sodium Cooled Advanced Fast Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shannon M. Bragg-Sitton; Richard D. Boardman; Robert S. Cherry

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 feedmore » 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.« less

In situ Raman cell for high pressure and temperature studies of metal and complex hydrides.

PubMed

Domènech-Ferrer, Roger; Ziegs, Frank; Klod, Sabrina; Lindemann, Inge; Voigtländer, Ralf; Dunsch, Lothar; Gutfleisch, Oliver

2011-04-15

A novel cell for in situ Raman studies at hydrogen pressures up to 200 bar and at temperatures as high as 400 °C is presented. This device permits in situ monitoring of the formation and decomposition of chemical structures under high pressure via Raman scattering. The performance of the cell under extreme conditions is stable as the design of this device compensates much of the thermal expansion during heating which avoids defocusing of the laser beam. Several complex and metal hydrides were analyzed to demonstrate the advantageous use of this in situ cell. Temperature calibration was performed by monitoring the structural phase transformation and melting point of LiBH(4). The feasibility of the cell in hydrogen atmosphere was confirmed by in situ studies of the decomposition of NaAlH(4) with added TiCl(3) at different hydrogen pressures and the decomposition and rehydrogenation of MgH(2) and LiNH(2). © 2011 American Chemical Society

Trapping of hydrogen atoms in X-irradiated salts at room temperature and the decay kinetics

NASA Technical Reports Server (NTRS)

May, C. E.; Philipp, W. H.; Marsik, S. J.

1974-01-01

The salts (hypophosphites, formates, a phosphite, a phosphate, and an oxalate) were X-irradiated, whereby hydrogen formed chemically by a radiolytic process becomes trapped in the solid. By room temperature vacuum extraction, the kinetics for the evolution of this trapped hydrogen was studied mass spectrometrically. All salts except two exhibited second-order kinetics. The two exceptions (NaH2PO2(H2O) and K2HPO4) showed first-order kinetics. Based on experimental results, the escape of hydrogen involves three steps: the diffusion of hydrogen atoms from the bulk to the surface, association of these atoms on the surface (rate controlling step for second-order hydrogen evolution), and the desorption of molecular hydrogen from the surface. The hydrogen does not escape if the irradiated salt is stored in air, apparently because adsorbed air molecules occupy surface sites required in the escape mechanism.

HYFIRE II: fusion/high-temperature electrolysis conceptual-design study. Annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fillo, J.A.

1983-08-01

As in the previous HYFIRE design study, the current study focuses on coupling a Tokamak fusion reactor with a high-temperature blanket to a High-Temperature Electrolyzer (HTE) process to produce hydrogen and oxygen. Scaling of the STARFIRE reactor to allow a blanket power to 6000 MW(th) is also assumed. The primary difference between the two studies is the maximum inlet steam temperature to the electrolyzer. This temperature is decreased from approx. 1300/sup 0/ to approx. 1150/sup 0/C, which is closer to the maximum projected temperature of the Westinghouse fuel cell design. The process flow conditions change but the basic design philosophymore » and approaches to process design remain the same as before. Westinghouse assisted in the study in the areas of systems design integration, plasma engineering, balance-of-plant design, and electrolyzer technology.« less

Modelling deuterium release from tungsten after high flux high temperature deuterium plasma exposure

NASA Astrophysics Data System (ADS)

Grigorev, Petr; Matveev, Dmitry; Bakaeva, Anastasiia; Terentyev, Dmitry; Zhurkin, Evgeny E.; Van Oost, Guido; Noterdaeme, Jean-Marie

2016-12-01

Tungsten is a primary candidate for plasma facing materials for future fusion devices. An important safety concern in the design of plasma facing components is the retention of hydrogen isotopes. Available experimental data is vast and scattered, and a consistent physical model of retention of hydrogen isotopes in tungsten is still missing. In this work we propose a model of non-equilibrium hydrogen isotopes trapping under fusion relevant plasma exposure conditions. The model is coupled to a diffusion-trapping simulation tool and is used to interpret recent experiments involving high plasma flux exposures. From the computational analysis performed, it is concluded that high flux high temperature exposures (T = 1000 K, flux = 1024 D/m2/s and fluence of 1026 D/m2) result in generation of sub-surface damage and bulk diffusion, so that the retention is driven by both sub-surface plasma-induced defects (bubbles) and trapping at natural defects. On the basis of the non-equilibrium trapping model we have estimated the amount of H stored in the sub-surface region to be ∼10-5 at-1, while the bulk retention is about 4 × 10-7 at-1, calculated by assuming the sub-surface layer thickness of about 10 μm and adjusting the trap concentration to comply with the experimental results for the integral retention.

Evidence for a first-order liquid-liquid transition in high-pressure hydrogen from ab initio simulations

PubMed Central

Morales, Miguel A.; Pierleoni, Carlo; Schwegler, Eric; Ceperley, D. M.

2010-01-01

Using quantum simulation techniques based on either density functional theory or quantum Monte Carlo, we find clear evidence of a first-order transition in liquid hydrogen, between a low conductivity molecular state and a high conductivity atomic state. Using the temperature dependence of the discontinuity in the electronic conductivity, we estimate the critical point of the transition at temperatures near 2,000 K and pressures near 120 GPa. Furthermore, we have determined the melting curve of molecular hydrogen up to pressures of 200 GPa, finding a reentrant melting line. The melting line crosses the metalization line at 700 K and 220 GPa using density functional energetics and at 550 K and 290 GPa using quantum Monte Carlo energetics. PMID:20566888

Temperature peaking at beginning of breakdown in 2.45 GHz pulsed off-resonance electron cyclotron resonance ion source hydrogen plasma

NASA Astrophysics Data System (ADS)

Cortázar, O. D.; Megía-Macías, A.; Vizcaíno-de-Julián, A.

2012-10-01

An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 μs are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas.

Internal hydrogen-induced subcritical crack growth in austenitic stainless steels

NASA Astrophysics Data System (ADS)

Huang, J. H.; Altstetter, C. J.

1991-11-01

The effects of small amounts of dissolved hydrogen on crack propagation were determined for two austenitic stainless steel alloys, AISI 301 and 310S. In order to have a uniform distribution of hydrogen in the alloys, they were cathodically charged at high temperature in a molten salt electrolyte. Sustained load tests were performed on fatigue precracked specimens in air at 0 ‡C, 25 ‡C, and 50 ‡C with hydrogen contents up to 41 wt ppm. The electrical potential drop method with optical calibration was used to continuously monitor the crack position. Log crack velocity vs stress intensity curves had definite thresholds for subcritical crack growth (SCG), but stage II was not always clearly delineated. In the unstable austenitic steel, AISI 301, the threshold stress intensity decreased with increasing hydrogen content or increasing temperature, but beyond about 10 wt ppm, it became insensitive to hydrogen concentration. At higher concentrations, stage II became less distinct. In the stable stainless steel, subcritical crack growth was observed only for a specimen containing 41 wt ppm hydrogen. Fractographic features were correlated with stress intensity, hydrogen content, and temperature. The fracture mode changed with temperature and hydrogen content. For unstable austenitic steel, low temperature and high hydrogen content favored intergranular fracture while microvoid coalescence dominated at a low hydrogen content. The interpretation of these phenomena is based on the tendency for stress-induced phase transformation, the different hydrogen diffusivity and solubility in ferrite and austenite, and outgassing from the crack tip. After comparing the embrittlement due to internal hydrogen with that in external hydrogen, it is concluded that the critical hydrogen distribution for the onset of subcritical crack growth is reached at a location that is very near the crack tip.

Effect of fermentation temperature on hydrogen production from cow waste slurry by using anaerobic microflora within the slurry.

PubMed

Yokoyama, Hiroshi; Waki, Miyoko; Moriya, Naoko; Yasuda, Tomoko; Tanaka, Yasuo; Haga, Kiyonori

2007-02-01

We examined hydrogen production from a dairy cow waste slurry (13.4 g of volatile solids per liter) by batch cultures in a temperature range from 37 to 85 degrees C, using microflora naturally present within the slurry. Without the addition of seed bacteria, hydrogen was produced by simply incubating the slurry, using the microflora within the slurry. Interestingly, two peaks of fermentation temperatures for hydrogen production from the slurry were observed at 60 and 75 degrees C (392 and 248 ml H2 per liter of slurry, respectively). After the termination of the hydrogen evolution, the microflora cultured at 60 degrees C displayed hydrogen-consuming activity, but hydrogen-consuming activity of the microflora cultured at 75 degrees C was not detected, at least for 24 days. At both 60 and 75 degrees C, the main by-product was acetate, and the optimum pH of the slurry for hydrogen production was around neutral. Bacteria related to hydrogen-producing moderate and extreme thermophiles, Clostridium thermocellum and Caldanaerobacter subterraneus, were detected in the slurries cultured at 60 and 75 degrees C, respectively, by denaturing gradient gel electrophoresis analyses, using the V3 region of 16S rDNA.

Numerical Simulation of Temperature Sensor Self-Heating Effects in Gaseous and Liquid Hydrogen Under Cryogenic Conditions

NASA Astrophysics Data System (ADS)

Langebach, R.; Haberstroh, Ch.

2010-04-01

In this paper a numerical investigation is presented that characterizes the free convective flow field and the resulting heat transfer mechanisms for a resistance temperature sensor in liquid and gaseous hydrogen at various cryogenic conditions. Motivation for this is the detection of stratification effects e.g. inside a liquid hydrogen storage vessel. In this case, the local temperature measurement in still resting fluid requires a very high standard of precision despite an extremely poor thermal anchoring of the sensor. Due to electrical power dissipation a certain amount of heat has to be transferred from sensor to fluid. This can cause relevant measurement errors due to a slightly elevated sensor temperature. A commercial CFD code was employed to calculate the heat and mass transfer around the typical sensor geometry. The results were compared with existing heat transfer correlations from the literature. As a result the magnitude of averaged heat transfer coefficients and sensor over-heating as a function of power dissipation are given in figures. From the gained numerical results a new correlation for the averaged Nusselt Number is presented that represents very low Rayleigh Number flows. The correlation can be used to estimate sensor self-heating effects in similar situations.

Atomic hydrogen as a launch vehicle propellant

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan A.

1990-01-01

An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb (sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 1b(sub f)/s/lb(sub m) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

Atomic hydrogen as a launch vehicle propellant

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan A.

1990-01-01

An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb(sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 lb(sub f)/s/lb(sub m)) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

Development of Criteria for Flameholding Tendencies within Premixer Passages for High Hydrogen Content Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Elliot Sullivan-; McDonell, Vincent G.

Due to increasingly stringent air quality requirements stationary power gas turbines have moved to lean-premixed operation, which reduces pollutant emissions but can result in flashback. Flashback can cause serious damage to the premixer hardware. Curtailing flashback can be difficult with hydrocarbon fuels and becomes even more challenging when hydrogen is used as the fuel. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design a premixer that will not anchor a flame if flashback occurs. Even with a well-designed combustor flashback can occur under certain circumstances, thus itmore » is necessary to determine how to avoid flameholding within the premixer passageways of a gas turbine. To this end, an experiment was designed that would determine the flameholding propensities at elevated pressures and temperatures of three different classes of geometric features commonly found in gas turbine premixers, with both natural gas and hydrogen fuel. Experiments to find the equivalence ratio at blow off were conducted within an optically accessible test apparatus with four flameholders: 0.25 and 0.50 inch diameter cylinders, a reverse facing step with a height of 0.25 inches, and a symmetric airfoil with a thickness of 0.25 inches and a chord length of one inch. Tests were carried out at temperatures between 300 K and 750 K, at pressures up to 9 atmospheres. Typical bulk velocities were between 40 and 100 m/s. The effect of airfoil’s angle of rotation was also investigated. Blow off for hydrogen flames was found to occur at much lower adiabatic flame temperatures than natural gas flames. Additionally it was observed that at high pressures and high turbulence intensities, reactant velocity does not have a noticeable effect on the point of blow off due in large part to corresponding increases in turbulent flame speed. Finally a semi empirical correlation was developed that predicts flame extinction

The resistance of selected high strength alloys to embrittlement by a hydrogen environment. [iron and cobalt base alloys

NASA Technical Reports Server (NTRS)

Benson, R. B., Jr.

1974-01-01

Selected high strength iron base and cobalt base alloys were resistant to degradation of mechanical properties in a one atmosphere hydrogen environment at ambient temperature. These alloys were strengthened initially by cold working which produced strain induced martensite and fcc mechanical twins in an fcc matrix. Heat treatment of the cobalt base alloy after cold working produced carbide precipitates with retention of an hcp epsilon phase which increased the yield strength level. High strength alloys can be produced which have some resistance to degradation of mechanical properties by a hydrogen environment under certain conditions.

Conceptual Launch Vehicles Using Metallic Hydrogen Propellant

NASA Astrophysics Data System (ADS)

Cole, John W.; Silvera, Isaac F.; Foote, John P.

2008-01-01

Solid molecular hydrogen is predicted to transform into an atomic solid with metallic properties under pressures >4.5 Mbar. Atomic metallic hydrogen is predicted to be metastable, limited by some critical temperature and pressure, and to store very large amounts of energy. Experiments may soon determine the critical temperature, critical pressure, and specific energy availability. It is useful to consider the feasibility of using metastable atomic hydrogen as a rocket propellant. If one assumes that metallic hydrogen is stable at usable temperatures and pressures, and that it can be affordably produced, handled, and stored, then it may be a useful rocket propellant. Assuming further that the available specific energy can be determined from the recombination of the atoms into molecules (216 MJ/kg), then conceptual engines and launch vehicle concepts can be developed. Under these assumptions, metallic hydrogen would be a revolutionary new rocket fuel with a theoretical specific impulse of 1700 s at a chamber pressure of 100 atm. A practical problem that arises is that rocket chamber temperatures may be too high for the use of this pure fuel. This paper examines an engine concept that uses liquid hydrogen or water as a diluent coolant for the metallic hydrogen to reduce the chamber temperature to usable values. Several launch vehicles are then conceptually developed. Results indicate that if metallic hydrogen is experimentally found to have the properties assumed in this analysis, then there are significant benefits. These benefits become more attractive as the chamber temperatures increase.

Impact of hydrogen dilution on optical properties of intrinsic hydrogenated amorphous silicon films prepared by high density plasma chemical vapor deposition for solar cell applications

NASA Astrophysics Data System (ADS)

Chen, Huai-Yi; Lee, Yao-Jen; Chang, Chien-Pin; Koo, Horng-Show; Lai, Chiung-Hui

2013-01-01

P-i-n single-junction hydrogenated amorphous silicon (a-Si:H) thin film solar cells were successfully fabricated in this study on a glass substrate by high density plasma chemical vapor deposition (HDP-CVD) at low power of 50 W, low temperature of 200°C and various hydrogen dilution ratios (R). The open circuit voltage (Voc ), short circuit current density (Jsc ), fill factor (FF) and conversion efficiency (η) of the solar cell as well as the refractive index (n) and absorption coefficient (α) of the i-layer at 600 nm wavelength rise with increasing R until an abrupt drop at high hydrogen dilution, i.e. R > 0.95. However, the optical energy bandgap (Eg ) of the i-layer decreases with the R increase. Voc and α are inversely correlated with Eg . The hydrogen content affects the i-layer and p/i interface quality of the a-Si:H thin film solar cell with an optimal value of R = 0.95, which corresponds to solar cell conversion efficiency of 3.85%. The proposed a-Si:H thin film solar cell is expected to be improved in performance.

High Temperature Steam Electrolysis: Demonstration of Improved Long-Term Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. E. O'Brien; X. Zhang; R. C. O'Brien

2011-11-01

Long-term performance is an ongoing issue for hydrogen production based on high-temperature steam electrolysis (HTSE). For commercial deployment, solid-oxide electrolysis stacks must achieve high performance with long-term degradation rates of {approx}0.5%/1000 hours or lower. Significant progress has been achieved toward this goal over the past few years. This paper will provide details of progress achieved under the Idaho National Laboratory high temperature electrolysis research program. Recent long-term stack tests have achieved high initial performance with degradation rates less than 5%/khr. These tests utilize internally manifolded stacks with electrode-supported cells. The cell material sets are optimized for the electrolysis mode ofmore » operation. Details of the cells and stacks will be provided along with details of the test apparatus, procedures, and results.« less

High temperature solid oxide regenerative fuel cell for solar photovoltaic energy storage

NASA Technical Reports Server (NTRS)

Bents, David J.

1987-01-01

A hydrogen-oxygen regenerative fuel cell energy storage system based on high temperature solid oxide fuel cell technology is discussed which has application to darkside energy storage for solar photovoltaics. The forward and reverse operating cycles are described, and heat flow, mass, and energy balance data are presented to characterize the system's performance and the variation of performance with changing reactant storage pressure. The present system weighs less than nickel hydrogen battery systems after 0.7 darkside operation, and it maintains a specific weight advantage over radioisotope generators for discharge periods up to 72 hours.

High temperature solid oxide regenerative fuel cell for solar photovoltaic energy storage

NASA Astrophysics Data System (ADS)

Bents, David J.

A hydrogen-oxygen regenerative fuel cell energy storage system based on high temperature solid oxide fuel cell technology is discussed which has application to darkside energy storage for solar photovoltaics. The forward and reverse operating cycles are described, and heat flow, mass, and energy balance data are presented to characterize the system's performance and the variation of performance with changing reactant storage pressure. The present system weighs less than nickel hydrogen battery systems after 0.7 darkside operation, and it maintains a specific weight advantage over radioisotope generators for discharge periods up to 72 hours.

Low-Temperature Decontamination with Hydrogen Peroxide or Chlorine Dioxide for Space Applications

PubMed Central

Macken, S.; Giri, K.; Walker, J. T.; Bennett, A. M.

2012-01-01

The currently used microbial decontamination method for spacecraft and components uses dry-heat microbial reduction at temperatures of >110°C for extended periods to prevent the contamination of extraplanetary destinations. This process is effective and reproducible, but it is also long and costly and precludes the use of heat-labile materials. The need for an alternative to dry-heat microbial reduction has been identified by space agencies. Investigations assessing the biological efficacy of two gaseous decontamination technologies, vapor hydrogen peroxide (Steris) and chlorine dioxide (ClorDiSys), were undertaken in a 20-m3 exposure chamber. Five spore-forming Bacillus spp. were exposed on stainless steel coupons to vaporized hydrogen peroxide and chlorine dioxide gas. Exposure for 20 min to vapor hydrogen peroxide resulted in 6- and 5-log reductions in the recovery of Bacillus atrophaeus and Geobacillus stearothermophilus, respectively. However, in comparison, chlorine dioxide required an exposure period of 60 min to reduce both B. atrophaeus and G. stearothermophilus by 5 logs. Of the three other Bacillus spp. tested, Bacillus thuringiensis proved the most resistant to hydrogen peroxide and chlorine dioxide with D values of 175.4 s and 6.6 h, respectively. Both low-temperature decontamination technologies proved effective at reducing the Bacillus spp. tested within the exposure ranges by over 5 logs, with the exception of B. thuringiensis, which was more resistant to both technologies. These results indicate that a review of the indicator organism choice and loading could provide a more appropriate and realistic challenge for the sterilization procedures used in the space industry. PMID:22492450

Decomposition of carbon dioxide by recombining hydrogen plasma with ultralow electron temperature

NASA Astrophysics Data System (ADS)

Yamazaki, Masahiro; Nishiyama, Shusuke; Sasaki, Koichi

2018-06-01

We examined the rate coefficient for the decomposition of CO2 in low-pressure recombining hydrogen plasmas with electron temperatures between 0.15 and 0.45 eV, where the electron-impact dissociation was negligible. By using this ultralow-temperature plasma, we clearly observed decomposition processes via vibrational excited states. The rate coefficient of the overall reaction, CO2 + e → products, was 1.5 × 10‑17 m3/s in the ultralow-temperature plasma, which was 10 times larger than the decomposition rate coefficient of 2 × 10‑18 m3/s in an ionizing plasma with an electron temperature of 4 eV.

Carbon nanotube materials for hydrogen storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dillon, A.C.; Parilla, P.A.; Jones, K.M.

1998-08-01

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption onmore » planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.« less

The effect of surface oxide layer on the rate of hydrogen emission from aluminum and its alloys in a high vacuum

NASA Technical Reports Server (NTRS)

Makarova, V. I.; Zyabrev, A. A.

1979-01-01

The influence of surface oxide layers on the kinetics of hydrogen emission at the high vacuum of 10 to the minus 8th power torr was investigated at temperatures from 20 to 450 C using samples of pure AB00 aluminum and the cast alloy AMg. Cast and deformed samples of AMts alloy were used to study the effect of oxide film thickness on the rate of hydrogen emission. Thermodynamic calculations of the reactions of the generation and dissociation of aluminum oxide show that degasification at elevated temperatures (up to 600 C) and high vacuum will not reduce the thickness of artificially-generated surface oxide layers on aluminum and its alloys.

THE PRODUCTION OF HYDROGEN PEROXIDE BY HIGH OXYGEN PRESSURES

PubMed Central

Gilbert, Daniel L.; Gerschman, Rebeca; Ruhm, K. Barclay; Price, William E.

1958-01-01

Hydrogen peroxide is formed in solutions of glutathione exposed to oxygen. This hydrogen peroxide or its precursors will decrease the viscosity of polymers like desoxyribonucleic acid and sodium alginate. Further knowledge of the mechanism of these chemical effects of oxygen might further the understanding of the biological effects of oxygen. This study deals with the rate of solution of oxygen and with the decomposition of hydrogen peroxide in chemical systems exposed to high oxygen pressures. At 6 atmospheres, the absorption coefficient for oxygen into water was about 1 cm./hour and at 143 atmospheres, it was about 2 cm./hour; the difference probably being due to the modus operandi. The addition of cobalt (II), manganese (II), nickel (II), or zinc ions in glutathione (GSH) solutions exposed to high oxygen pressure decreased the net formation of hydrogen peroxide and also the reduced glutathione remaining in the solution. Studies on hydrogen peroxide decomposition indicated that these ions act probably by accelerating the hydrogen perioxide oxidation of glutathione. The chelating agent, ethylenediaminetetraacetic acid disodium salt, inhibited the oxidation of GSH exposed to high oxygen pressure for 14 hours. However, indication that oxidation still occurred, though at a much slower rate, was found in experiments lasting 10 weeks. Thiourea decomposed hydrogen peroxide very rapidly. When GSH solutions were exposed to high oxygen pressure, there was oxidation of the GSH, which became relatively smaller with increasing concentrations of GSH. PMID:13525677

Effect of hydrogen on the strength and microstructure of selected ceramics

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.; Hull, David R.; Misra, Ajay K.

1990-01-01

Ceramics in monolithic form and as composite constituents in the form of fibers, matrices, and coatings are currently being considered for a variety of high-temperature applications in aeronautics and space. Many of these applications involve exposure to a hydrogen-containing environment. The compatibility of selected ceramics in gaseous high-temperature hydrogen is assessed. Environmental stability regimes for the long term use of ceramic materials are defined by the parameters of temperature, pressure, and moisture content. Thermodynamically predicted reactions between hydrogen and several monolithic ceramics are compared with actual performance in a controlled environment. Morphology of hydrogen attack and the corresponding strength degradation is reported for silicon carbide, silicon nitride, alumina, magnesia, and mullite.

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).

PubMed

Gehre, Matthias; Renpenning, Julian; Geilmann, Heike; Qi, Haiping; Coplen, Tyler B; Kümmel, Steffen; Ivdra, Natalija; Brand, Willi A; Schimmelmann, Arndt

2017-03-30

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 (H 2 ) is responsible for non-quantitative H 2 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. The EA-Cr/HTC reactor was substantially modified for the conversion of halogen- and sulfur-bearing samples. The performance of the novel conversion setup for solid and liquid samples was monitored and optimized using a simultaneously operating dual-detection system of IRMS and ion trap MS. The method with several variants in the reactor, including the addition of manganese metal chips, was evaluated in three laboratories using EA-Cr/HTC-IRMS (on-line method) and compared with traditional uranium-reduction-based conversion combined with manual dual-inlet IRMS analysis (off-line method) in one laboratory. The modified EA-Cr/HTC reactor setup showed an overall H 2 -recovery of more than 96% for all halogen- and sulfur-bearing organic compounds. All results were successfully normalized via two-point calibration with VSMOW-SLAP reference waters. Precise and accurate hydrogen isotopic analysis was achieved for a variety of organics containing F-, Cl-, Br-, I-, and S-bearing heteroelements. The robust nature of the on-line EA-Cr/HTC technique was demonstrated by a series of 196 consecutive measurements with a single reactor filling. The optimized EA-Cr/HTC reactor design can be implemented in existing analytical equipment using commercially available material and

Photochemical Hydrogen Doping Induced Embedded Two-Dimensional Metallic Channel Formation in InGaZnO at Room Temperature.

PubMed

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.

Hydrogen production from coal using a nuclear heat source

NASA Technical Reports Server (NTRS)

Quade, R. N.

1976-01-01

A strong candidate for hydrogen production in the intermediate time frame of 1985 to 1995 is a coal-based process using a high-temperature gas-cooled reactor (HTGR) as a heat source. Expected process efficiencies in the range of 60 to 70% are considerably higher than all other hydrogen production processes except steam reforming of a natural gas. The process involves the preparation of a coal liquid, hydrogasification of that liquid, and steam reforming of the resulting gaseous or light liquid product. A study showing process efficiency and cost of hydrogen vs nuclear reactor core outlet temperature has been completed, and shows diminishing returns at process temperatures above about 1500 F. A possible scenario combining the relatively abundant and low-cost Western coal deposits with the Gulf Coast hydrogen users is presented which provides high-energy density transportation utilizing coal liquids and uranium.

Fast detection and low power hydrogen sensor using edge-oriented vertically aligned 3-D network of MoS2 flakes at room temperature

NASA Astrophysics Data System (ADS)

Agrawal, A. V.; Kumar, R.; Venkatesan, S.; Zakhidov, A.; Zhu, Z.; Bao, Jiming; Kumar, Mahesh; Kumar, Mukesh

2017-08-01

The increased usage of hydrogen as a next generation clean fuel strongly demands the parallel development of room temperature and low power hydrogen sensors for their safety operation. In this work, we report strong evidence for preferential hydrogen adsorption at edge-sites in an edge oriented vertically aligned 3-D network of MoS2 flakes at room temperature. The vertically aligned edge-oriented MoS2 flakes were synthesised by a modified CVD process on a SiO2/Si substrate and confirmed by Scanning Electron Microscopy. Raman spectroscopy and PL spectroscopy reveal the signature of few-layer MoS2 flakes in the sample. The sensor's performance was tested from room temperature to 150 °C for 1% hydrogen concentration. The device shows a fast response of 14.3 s even at room temperature. The sensitivity of the device strongly depends on temperature and increases from ˜1% to ˜11% as temperature increases. A detail hydrogen sensing mechanism was proposed based on the preferential hydrogen adsorption at MoS2 edge sites. The proposed gas sensing mechanism was verified by depositing ˜2-3 nm of ZnO on top of the MoS2 flakes that partially passivated the edge sites. We found a decrease in the relative response of MoS2-ZnO hybrid structures. This study provides a strong experimental evidence for the role of MoS2 edge-sites in the fast hydrogen sensing and a step closer towards room temperature, low power (0.3 mW), hydrogen sensor development.

Hydrogen Permeability of Incoloy 800H, Inconel 617, and Haynes 230 Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pattrick Calderoni

A potential issue in the design of the NGNP reactor and high-temperature components is the permeation of fission generated tritium and hydrogen product from downstream hydrogen generation through high-temperature components. Such permeation can result in the loss of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system. The issue will be addressed in the engineering design phase, and requires knowledge of permeation characteristics of the candidate alloys. Of three potential candidates for high-temperature components of the NGNP reactor design, the hydrogen permeability has been documented well onlymore » for Incoloy 800H, but at relatively high partial pressures of hydrogen. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. The hydrogen permeability of Haynes 230 has not been published. To support engineering design of the NGNP reactor components, the hydrogen permeability of Inconel 617 and Haynes 230 were determined using a measurement system designed and fabricated at the Idaho National Laboratory. The performance of the system was validated using Incoloy 800H as reference material, for which the permeability has been published in several journal articles. The permeability of Incoloy 800H, Inconel 617 and Haynes 230 was measured in the temperature range 650 to 950 °C and at hydrogen partial pressures of 10-3 and 10-2 atm, substantially lower pressures than used in the published reports. The measured hydrogen permeability of Incoloy 800H and Inconel 617 were in good agreement with published values obtained at higher partial pressures of hydrogen. The hydrogen permeability of Inconel 617 and Haynes 230 were similar, about 50% greater than for Incoloy 800H and with similar temperature dependence.« less

Hydrogen Assisted Cracking of High Strength Steel Welds

DTIC Science & Technology

1988-05-01

cracking of high strength steel welds. The microplasticity theory originally proposed by M Beachem is used to explain the effect of hydrogen on the var... microplasticity mechanism rather than embrittlement (B7). He suggests that the hydrogen in the lattice ahead of the crack tip assists whatever...intensity level on the observed fracture mode. This theory postu- lates that hydrogen will promote cracking by a microplasticity mechanism rather than

A High-Temperature MEMS Surface Fence for Wall-Shear-Stress Measurement in Scramjet Flow

PubMed Central

Ma, Binghe; Deng, Jinjun; Yuan, Weizheng; Zhou, Zitong; Zhang, Han

2017-01-01

A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 °C. The packaged sensor is calibrated over a range of ~65 Pa and then used to examine the development of the transient flow of the scramjet ignition process (Mach 2 airflow, stagnation pressure, and a temperature of 0.8 MPa and 950 K, respectively). The results show that the sensor is able to detect the transient flow conditions of the scramjet ignition process including shock impact, flow correction, steady state, and hydrogen off. PMID:29065498

A High-Temperature MEMS Surface Fence for Wall-Shear-Stress Measurement in Scramjet Flow.

PubMed

Ma, Chengyu; Ma, Binghe; Deng, Jinjun; Yuan, Weizheng; Zhou, Zitong; Zhang, Han

2017-10-22

A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 °C. The packaged sensor is calibrated over a range of ~65 Pa and then used to examine the development of the transient flow of the scramjet ignition process (Mach 2 airflow, stagnation pressure, and a temperature of 0.8 MPa and 950 K, respectively). The results show that the sensor is able to detect the transient flow conditions of the scramjet ignition process including shock impact, flow correction, steady state, and hydrogen off.

Low temperature, low pressure hydrogen gettering

DOEpatents

Anderson, D. Richard; Courtney, Robert L.; Harrah, Larry A.

1976-06-15

The invention relates to the gettering of hydrogen and its isotopes, the gettering materials being painted or coated onto, or otherwise disposed in an area or volume from which hydrogen is to be removed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klaehn, John; Peterson, Eric; Orme, Christopher

2013-01-01

Idaho National Laboratory (INL), GE Global Research (GEGR), and Western Research Institute (WRI) have successfully produced hydrogen-selective membranes for water-gas-shift (WGS) modules that enable high-pressure hydrogen product streams. Several high performance (HP) polymer membranes were investigated for their gas separation performance under simulated (mixed gas) and actual syngas conditions. To enable optimal module performance, membranes with high hydrogen (H 2) selectivity, permeance, and stability under WGS conditions are required. The team determined that the VTEC PI 80-051 and VTEC PI 1388 (polyimide from Richard Blaine International, Inc.) are prime candidates for the H 2 gas separations at operating temperatures (~200°C).more » VTEC PI 80-051 was thoroughly analyzed for its H 2 separations under syngas processing conditions using more-complex membrane configurations, such as tube modules and hollow fibers. These membrane formats have demonstrated that the selected VTEC membrane is capable of providing highly selective H 2/CO 2 separation (α = 7-9) and H 2/CO separation (α = 40-80) in humidified syngas streams. In addition, the VTEC polymer membranes are resilient within the syngas environment (WRI coal gasification) at 200°C for over 1000 hours. The information within this report conveys current developments of VTEC PI 80-051 as an effective H 2 gas separations membrane for high-temperature syngas streams.« less

Thin film thermocouples for high temperature turbine application

NASA Technical Reports Server (NTRS)

Martin, Lisa C.

1991-01-01

The objective is to develop thin film thermocouples (TFTC) for Space Shuttle Main Engine (SSME) components such as the high pressure fuel turbopump (HPFTP) blades and to test TFTC survivability and durability in the SSME environment. The purpose for developing TFTC's for SSME components is to obtain blade temperatures for computational models developed for fluid mechanics and structures. The TFTC must be able to withstand the presence of high temperature, high pressure hydrogen as well as a severe thermal transient due to a cryogenic to combustion temperature change. The TFTC's will eventually be installed and tested on SSME propulsion system components in the SSME test bed engine. The TFTC's were successfully fabricated on flat coupons of MAR-M 246 (Hf+), which is the superalloy material used for HPFTP turbine blades. The TFTC's fabricated on flat coupons survived thermal shock cycling as well as testing in a heat flux measurement facility which provided a rapid thermal transient. The same fabrication procedure was used to deposit TFTC's on HPFTP first stage rotor blades. Other results from the experiments are presented, and future testing plans are discussed.

Ortho-para-hydrogen equilibration on Jupiter

NASA Technical Reports Server (NTRS)

Carlson, Barbara E.; Lacis, Andrew A.; Rossow, William B.

1992-01-01

Voyager IRIS observations reveal that the Jovian para-hydrogen fraction is not in thermodynamic equilibrium near the NH3 cloud top, implying that a vertical gradient exists between the high-temperature equilibrium value of 0.25 at depth and the cloud top values. The height-dependent para-hydrogen profile is obtained using an anisotropic multiple-scattering radiative transfer model. A vertical correlation is found to exist between the location of the para-hydrogen gradient and the NH3 cloud, strongly suggesting that paramagnetic conversion on NH3 cloud particle surfaces is the dominant equilibration mechanism. Below the NH3 cloud layer, the para fraction is constant with depth and equal to the high-temperature equilibrium value of 0.25. The degree of cloud-top equilibration appears to depend on the optical depth of the NH3 cloud layer. Belt-zone variations in the para-hydrogen profile seem to be due to differences in the strength of the vertical mixing.

Oxygen Handling and Cooling Options in High Temperature Electrolysis Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manohar S. Sohal; J. Stephen Herring

2008-07-01

Idaho National Laboratory is working on a project to generate hydrogen by high temperature electrolysis (HTE). In such an HTE system, safety precautions need to be taken to handle high temperature oxygen at ~830°C. This report is aimed at addressing oxygen handling in a HTE plant.. Though oxygen itself is not flammable, most engineering material, including many gases and liquids, will burn in the presence of oxygen under some favorable physicochemical conditions. At present, an absolute set of rules does not exist that can cover all aspects of oxygen system design, material selection, and operating practices to avoid subtle hazardsmore » related to oxygen. Because most materials, including metals, will burn in an oxygen-enriched environment, hazards are always present when using oxygen. Most materials will ignite in an oxygen-enriched environment at a temperature lower than that in air, and once ignited, combustion rates are greater in the oxygen-enriched environment. Even many metals, if ignited, burn violently in an oxygen-enriched environment. However, these hazards do not preclude the operations and systems involving oxygen. Oxygen can be safely handled and used if all the materials in a system are not flammable in the end-use environment or if ignition sources are identified and controlled. In fact, the incidence of oxygen system fires is reported to be low with a probability of about one in a million. This report is a practical guideline and tutorial for the safe operation and handling of gaseous oxygen in high temperature electrolysis system. The intent is to provide safe, practical guidance that permits the accomplishment of experimental operations at INL, while being restrictive enough to prevent personnel endangerment and to provide reasonable facility protection. Adequate guidelines are provided to govern various aspects of oxygen handling associated with high temperature electrolysis system to generate hydrogen. The intent here is to present

Composition and method for hydrogen storage

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

Microstructure and yield strength effects on hydrogen and tritium induced cracking in HERF (high-energy-rate-forged) stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, M J; Tosten, M H

1989-01-01

Rising-load J-integral measurements and falling-load threshold stress intensity measurements were used to characterize hydrogen and tritium induced cracking in high-energy-rate-forged (HERF) 21-6-9 stainless steel. Samples having yield strengths in the range 517--930 MPa were thermally charged with either hydrogen or tritium and tested at room temperature in either air or high-pressure hydrogen gas. In general, the hydrogen isotopes reduced the fracture toughness by affecting the fracture process. Static recrystallization in the HERF microstructures affected the material's fracture toughness and its relative susceptibility to hydrogen and tritium induced fracture. In hydrogen-exposed samples, the reduction in fracture toughness was primarily dependent onmore » the susceptibility of the microstructure to intergranular fracture and only secondarily affected by strength in the range of 660 to 930 MPa. Transmission-electron microscopy observations revealed that the microstructures least susceptible to hydrogen-induced intergranular cracking contained patches of fully recrystallized grains. These grains are surrounded by highly deformed regions containing a high number density of dislocations. The microstructure can best be characterized as duplex'', with soft recrystallized grains embedded in a hard, deformed matrix. The microstructures most susceptible to hydrogen-induced intergranular fracture showed no well-developed recrystallized grains. The patches of recrystallized grains seemed to act as crack barriers to hydrogen-induced intergranular fracture. In tritium-exposed-and-aged samples, the amount of static recrystallization also affected the fracture toughness properties but to a lesser degree. 7 refs., 25 figs.« less

Low temperature, low pressure hydrogen gettering

DOEpatents

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

1975-07-22

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. (auth)

The H{sub 60}Si{sub 6}C{sub 54} heterofullerene as high-capacity hydrogen storage medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yong, Yongliang, E-mail: ylyong@haust.edu.cn; Department of Physics, Zhejiang University, Hangzhou 310027; Zhou, Qingxiao

2016-07-15

With the great success in Si atoms doped C{sub 60} fullerene and the well-established methods for synthesis of hydrogenated carbon fullerenes, this leads naturally to wonder whether Si-doped fullerenes are possible for special applications such as hydrogen storage. Here by using first-principles calculations, we design a novel high-capacity hydrogen storage material, H{sub 60}Si{sub 6}C{sub 54} heterofullerene, and confirm its geometric stability. It is found that the H{sub 60}Si{sub 6}C{sub 54} heterofullerene has a large HOMO-LUMO gap and a high symmetry, indicating it is high chemically stable. Further, our finite temperature simulations indicate that the H{sub 60}Si{sub 6}C{sub 54} heterofullerene ismore » thermally stable at 300 K. H{sub 2} molecules would enter into the cage from the Si-hexagon ring because of lower energy barrier. Through our calculation, a maximum of 21 H{sub 2} molecules can be stored inside the H{sub 60}Si{sub 6}C{sub 54} cage in molecular form, leading to a gravimetric density of 11.11 wt% for 21H{sub 2}@H{sub 60}Si{sub 6}C{sub 54} system, which suggests that the hydrogenated Si{sub 6}C{sub 54} heterofullerene could be suitable as a high-capacity hydrogen storage material.« less

Hydrogenation at low temperatures does not always lead to saturation: the case of HNCO

NASA Astrophysics Data System (ADS)

Noble, J. A.; Theule, P.; Congiu, E.; Dulieu, F.; Bonnin, M.; Bassas, A.; Duvernay, F.; Danger, G.; Chiavassa, T.

2015-04-01

Context. It is generally agreed that hydrogenation reactions dominate chemistry on grain surfaces in cold, dense molecular cores, saturating the molecules present in ice mantles. Aims: We present a study of the low temperature reactivity of solid phase isocyanic acid (HNCO) with hydrogen atoms, with the aim of elucidating its reaction network. Methods: Fourier transform infrared spectroscopy and mass spectrometry were employed to follow the evolution of pure HNCO ice during bombardment with H atoms. Both multilayer and monolayer regimes were investigated. Results: The hydrogenation of HNCO does not produce detectable amounts of formamide (NH2CHO) as the major product. Experiments using deuterium reveal that deuteration of solid HNCO occurs rapidly, probably via cyclic reaction paths regenerating HNCO. Chemical desorption during these reaction cycles leads to loss of HNCO from the surface. Conclusions: It is unlikely that significant quantities of NH2CHO form from HNCO. In dense regions, however, deuteration of HNCO will occur. HNCO and DNCO will be introduced into the gas phase, even at low temperatures, as a result of chemical desorption.

The ignition delay times of hydrogen/silan/air mixtures at low temperatures

NASA Astrophysics Data System (ADS)

Tropin, D. A.; Bochenkov, E. S.; Fedorov, A. V.

2018-03-01

In the paper the ignition delay times of hydrogen-silane-air mixtures at low pressures from 0.4 atm to 1 atm and mixture temperatures from 300 K to 900 K using the detailed kinetic mechanisms were calculated. It was shown that dependencies of ignition delay time on temperature are non-monotonic. In these dependences a region of "negative temperature coefficient" is presented. The effect of the mixture pressure and the silane concentration in the mixture on the length of this region was revealed. It was shown that the increasing of the silane concentration in the mixture, as well as the increasing the mixture pressure, leads to increasing of the "negative temperature coefficient" region length.

Acid-catalyzed hydrogenation during kerosene hydrodewaxing over H/ZSM-5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longstaff, D.C.; Hanson, F.V.

1996-11-01

Hydrogen addition to the products derived from cracking kerosene over H/ZSM-5 was observed at hydrogen pressures between 4.1-8.7 MPa and at 373-390{degrees}C. At low pressures, kerosene cracking over H/ZSM-5 yielded typical cracked products: aromatics, as well as low molecular weight saturates and olefins. Endothermic reactor temperature profiles were also observed, indicative of cracking reactions. At high hydrogen partial pressures product selectivity was altered in that kerosene cracking gave high yields of low molecular weight paraffins and low yields of olefins and aromatics. Reactor temperature profiles were exothermic, indicative of hydrocracking reactions. A mechanism for acid catalyzed hydrogenation is suggested. Althoughmore » hydrogenation was not observed at lower hydrogen pressures, hydrogen proved beneficial in maintaining catalyst activity at a stable level. Lost catalyst activity was restored by maintaining the catalyst under static hydrogen at 1.4 MPa and 370{degrees}C for 16h. 36 refs., 14 figs., 3 tabs.« less

Measurement component technology. Volume 1: Cryogenic pressure measurement technology, high pressure flange seals, hydrogen embrittlement of pressure transducer material, close coupled versus remote transducer installation and temperature compensation of pressure transducers

NASA Technical Reports Server (NTRS)

Hayakawa, K. K.; Udell, D. R.; Iwata, M. M.; Lytle, C. F.; Chrisco, R. M.; Greenough, C. S.; Walling, J. A.

1972-01-01

The results are presented of an investigation into the availability and performance capability of measurement components in the area of cryogenic temperature, pressure, flow and liquid detection components and high temperature strain gages. In addition, technical subjects allied to the components were researched and discussed. These selected areas of investigation were: (1) high pressure flange seals, (2) hydrogen embrittlement of pressure transducer diaphragms, (3) The effects of close-coupled versus remote transducer installation on pressure measurement, (4) temperature transducer configuration effects on measurements, and (5) techniques in temperature compensation of strain gage pressure transducers. The purpose of the program was to investigate the latest design and application techniques in measurement component technology and to document this information along with recommendations for upgrading measurement component designs for future S-2 derivative applications. Recommendations are provided for upgrading existing state-of-the-art in component design, where required, to satisfy performance requirements of S-2 derivative vehicles.

Iron-rich clay minerals on Mars - Potential sources or sinks for hydrogen and indicators of hydrogen loss over time

NASA Technical Reports Server (NTRS)

Burt, D. M.

1989-01-01

Although direct evidence is lacking, indirect evidence suggests that iron-rich clay minerals or poorly-ordered chemical equivalents are widespread on the Martian surface. Such clays can act as sources or sinks for hydrogen ('hydrogen sponges'). Ferrous clays can lose hydrogen and ferric clays gain it by the coupled substitution Fe(3+)O(Fe(2+)OH)-1, equivalent to minus atomic H. This 'oxy-clay' substitution involves only proton and electron migration through the crystal structure, and therefore occurs nondestructively and reversibly, at relatively low temperatures. The reversible, low-temperature nature of this reaction contrasts with the irreversible nature of destructive dehydroxylation (H2O loss) suffered by clays heated to high temperatures. In theory, metastable ferric oxy-clays formed by dehydrogenation of ferrous clays over geologic time could, if exposed to water vapor, extract the hydrogen from it, releasing oxygen.

Note: Low phase noise programmable phase-locked loop with high temperature stability.

PubMed

Michálek, Vojtěch; Procházka, Ivan

2017-03-01

The design and construction of low jitter programmable phase-locked loop with low temperature coefficient of phase are presented. It has been designed for demanding high precision timing applications, especially as a clock source for event timer with subpicosecond precision. The phase-locked loop itself has a jitter of few hundreds of femtoseconds. It produces square wave with programmable output frequency from 100 MHz to 500 MHz and programmable amplitude of 0.25 V to 1.2 V peak-to-peak, which is locked to 5 MHz or 10 MHz reference frequency common for disciplined oscillators and highly stable clocks such as hydrogen maser. Moreover, it comprises an on-board temperature compensated crystal oscillator for stand-alone usage. The device provides temperature coefficient of the phase lock of 0.9 ps/K near room temperature.

Research of the high performance low temperature vortex street flowmeter

NASA Astrophysics Data System (ADS)

Gao, Feng; Chen, Yang; Zhang, Zhen-peng; Geng, Wei-guo

2007-07-01

Flow measurement is the key method for R&D and operation monitoring of liquid rocket engine. Therefore, it is important to measure flux of low temperature liquid propellants for the liquid hydrogen/liquid oxygen or the liquid oxygen/kerosene rocket engine. Presently in China, the level meter and the turbine flowmeter are usually used in the experimentation of the liquid hydrogen/liquid oxygen rocket engine. The level meter can only scale average flux and the precision of the turbine flowmeter (the measuring wild point is 1.5%) can not be ensured due to the reason which there is not devices of low temperature real-time demarcation in China. Therefore, it is required to research the high performance low temperature flow measurement equipment and the vortex street flowmeter is selected because of its advantages. In the paper, some key techniques of low temperature vortex street flowmeter are researched from the design aspect. Firstly, the basic theoretical research of vortex street flowmeter includes signal detection method, shape of vortex producer and effects of dimension of vertex producer to vortex quality. Secondly, low temperature vortex street flowmeter adopts the method of piezoelectric components stress mode. As for the weakness of phase-change, lattice change and fragility for many piezoelectric materials in low temperature, it can not be fulfilled piezoelectric signal and mechanism performance under this condition. Some piezoelectric materials which can be used in low temperature are illustrated in the paper by lots of research in order for the farther research. The article places emphasis upon low temperature trait of piezoelectric materials, and the structure designs of signal detector and calculation of stress, electric charge quantity and heat transfer.

High-pressure modulation of the structure of the bacterial photochemical reaction center at physiological and cryogenic temperatures

NASA Astrophysics Data System (ADS)

Timpmann, Kõu; Kangur, Liina; Lõhmus, Ants; Freiberg, Arvi

2017-07-01

The optical absorption and fluorescence response to external high pressure of the reaction center membrane chromoprotein complex from the wild-type non-sulfur photosynthetic bacterium Rhodobacter sphaeroides was investigated using the native pigment cofactors as local molecular probes of the reaction center structure at physiological (ambient) and cryogenic (79 K) temperatures. In detergent-purified complexes at ambient temperature, abrupt blue shift and accompanied broadening of the special pair band was observed at about 265 MPa. These reversible in pressure features were assigned to a pressure-induced rupture of a lone hydrogen bond that binds the photo-chemically active L-branch primary electron donor bacteriochlorophyll cofactor to the surrounding protein scaffold. In native membrane-protected complexes the hydrogen bond rupture appeared significantly restricted and occurred close to about 500 MPa. The free energy change associated with the rupture of the special pair hydrogen bond in isolate complexes was estimated to be equal to about 12 kJ mol-1. In frozen samples at cryogenic temperatures the hydrogen bond remained apparently intact up to the maximum utilized pressure of 600 MPa. In this case, however, heterogeneous spectral response of the cofactors from the L-and M-branches was observed due to anisotropic build-up of the protein structure. While in solid phase, the special pair fluorescence as a function of pressure exactly followed the respective absorption spectrum at a constant Stokes shift, at ambient temperature, the two paths began to deviate strongly from one other at the hydrogen bond rupture pressure. This effect was tentatively interpreted by different emission properties of hydrogen-bound and hydrogen-unbound special pair exciton states.

Hydrogen Embrittlement of Automotive Advanced High-Strength Steels

NASA Astrophysics Data System (ADS)

Lovicu, Gianfranco; Bottazzi, Mauro; D'Aiuto, Fabio; De Sanctis, Massimo; Dimatteo, Antonella; Santus, Ciro; Valentini, Renzo

2012-11-01

Advanced high-strength steels (AHSS) have a better combination between strength and ductility than conventional HSS, and higher crash resistances are obtained in concomitance with weight reduction of car structural components. These steels have been developed in the last few decades, and their use is rapidly increasing. Notwithstanding, some of their important features have to be still understood and studied in order to completely characterize their service behavior. In particular, the high mechanical resistance of AHSS makes hydrogen-related problems a great concern for this steel grade. This article investigates the hydrogen embrittlement (HE) of four AHSS steels. The behavior of one transformation induced plasticity (TRIP), two martensitic with different strength levels, and one hot-stamping steels has been studied using slow strain rate tensile (SSRT) tests on electrochemically hydrogenated notched samples. The embrittlement susceptibility of these AHSS steels has been correlated mainly to their strength level and to their microstructural features. Finally, the hydrogen critical concentrations for HE, established by SSRT tests, have been compared to hydrogen contents absorbed during the painting process of a body in white (BIW) structure, experimentally determined during a real cycle in an industrial plant.

Growth of room temperature ferromagnetic Ge1-xMnx quantum dots on hydrogen passivated Si (100) surfaces

NASA Astrophysics Data System (ADS)

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.

Advanced high temperature materials for the energy efficient automotive Stirling engine

NASA Technical Reports Server (NTRS)

Titran, R. H.; Stephens, J. R.

1984-01-01

The Stirling Engine is under investigated jointly by the Department of Energy and NASA Lewis as an alternative to the internal combustion engine for automotive applications. The Stirling Engine is an external combustion engine that offers the advantage of high fuel economy, low emissions, low noise, and low vibrations compared to current internal combustion automotive engines. The most critical component from a materials viewpoint is the heater head consisting of the cylinders, heating tubes, and regenerator housing. Materials requirements for the heater head include compatibility with hydrogen, resistance to hydrogen permeation, high temperature oxidation/corrosion resistance and high temperature creep-rupture and fatigue properties. A continuing supporting materials research and technology program has identified the wrought alloys CG-27 and 12RN72 and the cast alloys XF-818 and NASAUT 4G-A1 as candidate replacements for the cobalt containing alloys used in current prototype engines. Based on the materials research program in support of the automotive Stirling engine it is concluded that manufacture of the engine is feasible from low cost iron-base alloys rather than the cobalt alloys rather than the cobalt alloys used in prototype engines. This paper will present results of research that led to this conclusion.

Method for low temperature catalytic production of hydrogen

DOEpatents

Mahajan, Devinder

2003-07-22

The invention provides a process for the catalytic production of a hydrogen feed by exposing a hydrogen feed to a catalyst which promotes a base-catalyzed water-gas-shift reaction in a liquid phase. The hydrogen feed can be provided by any process known in the art of making hydrogen gas. It is preferably provided by a process that can produce a hydrogen feed for use in proton exchange membrane fuel cells. The step of exposing the hydrogen feed takes place preferably from about 80.degree. C. to about 150.degree. C.

Hydrogen-based electrochemical energy storage

DOEpatents

Simpson, Lin Jay

2013-08-06

An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.

Validation of an Integrated Hydrogen Energy Station

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heydorn, Edward C

This report presents the results of a 10-year project conducted by Air Products and Chemicals, Inc. (Air Products) to determine the feasibility of coproducing hydrogen with electricity. The primary objective was to demonstrate the technical and economic viability of a hydrogen energy station using a high-temperature fuel cell designed to produce power and hydrogen. This four-phase project had intermediate go/no-go decisions and the following specific goals: Complete a technical assessment and economic analysis of the use of high-temperature fuel cells, including solid oxide and molten carbonate, for the co-production of power and hydrogen (energy park concept). Build on the experiencemore » gained at the Las Vegas H2 Energy Station and compare/contrast the two approaches for co-production. Determine the applicability of co-production from a high-temperature fuel cell for the existing merchant hydrogen market and for the emerging hydrogen economy. Demonstrate the concept on natural gas for six months at a suitable site with demand for both hydrogen and electricity. Maintain safety as the top priority in the system design and operation. Obtain adequate operational data to provide the basis for future commercial activities, including hydrogen fueling stations. Work began with the execution of the cooperative agreement with DOE on 30 September 2001. During Phase 1, Air Products identified high-temperature fuel cells as having the potential to meet the coproduction targets, and the molten carbonate fuel cell system from FuelCell Energy, Inc. (FuelCell Energy) was selected by Air Products and DOE following the feasibility assessment performed during Phase 2. Detailed design, construction and shop validation testing of a system to produce 250 kW of electricity and 100 kilograms per day of hydrogen, along with site selection to include a renewable feedstock for the fuel cell, were completed in Phase 3. The system also completed six months of demonstration operation at

High-temperature oxidation kinetics of sponge-based E110 cladding alloy

NASA Astrophysics Data System (ADS)

Yan, Yong; Garrison, Benton E.; Howell, Mike; Bell, Gary L.

2018-02-01

Two-sided oxidation experiments were recently conducted at 900°C-1200 °C in flowing steam with samples of sponge-based Zr-1Nb alloy E110. Although the old electrolytic E110 tubing exhibited a high degree of susceptibility to nodular corrosion and experienced breakaway oxidation rates in a relatively short time, the new sponge-based E110 demonstrated steam oxidation behavior comparable to Zircaloy-4. Sample weight gain and oxide layer thickness measurements were performed on oxidized E110 specimens and compared to oxygen pickup and oxide layer thickness calculations using the Cathcart-Pawel correlation. Our study shows that the sponge-based E110 follows the parabolic law at temperatures above 1015 °C. At or below 1015 °C, the oxidation rate was very low when compared to Zircaloy-4 and can be represented by a cubic expression. No breakaway oxidation was observed at 1000 °C for oxidation times up to 10,000 s. Arrhenius expressions are given to describe the parabolic rate constants at temperatures above 1015 °C and cubic rate constants are provided for temperatures below 1015 °C. The weight gains calculated by our equations are in excellent agreement with the measured sample weight gains at all test temperatures. In addition to the as-fabricated E110 cladding sample, prehydrided E110 cladding with hydrogen concentrations in the 100-150 wppm range was also investigated. The effect of hydrogen content on sponge-based E110 oxidation kinetics was minimal. No significant difference was found between as-fabricated and hydrided samples with regard to oxygen pickup and oxide layer thickness for hydrogen contents below 150 wppm.

Alternative Fuels Data Center: Hydrogen Production and Distribution

Science.gov Websites

created by reacting natural gas with high-temperature steam. The carbon monoxide is reacted with water to synthesis gas can also be created by reacting coal or biomass with high-temperature steam and oxygen in a : Renewable liquid fuels, such as ethanol, are reacted with high-temperature steam to produce hydrogen near

Hydrogen gas sensors using a thin Ta2O5 dielectric film

NASA Astrophysics Data System (ADS)

Kim, Seongjeen

2014-12-01

A capacitive-type hydrogen gas sensor with a MIS (metal-insulator-semiconductor) structure was investigated for high-temperature applications. In this work, a tantalum oxide (Ta2O5) layer of tens of nanometers in thickness formed by oxidizing tantalum film in rapid thermal processing (RTP) was exploited with the purpose of sensitivity improvement. Silicon carbide (SiC), which is good even at high temperatures over 500 °C, was used as the substrate. We fabricated sensors composed of Pd/Ta2O5/SiC, and the dependences of the capacitance response properties and the I-V characteristics on the hydrogen concentration were analyzed from the temperature range of room temperature to 500 °C. As a result, our hydrogen sensor showed promising performance with respect to the sensitivity and the adaptability at high temperature.

High Pressure and Temperature Effects in Polymers

NASA Astrophysics Data System (ADS)

Bucknall, David; Arrighi, Valeria; Johnston, Kim; Condie, Iain

Elastomers are widely exploited as the basis for seals in gas and fluid pipelines. The underlying behaviour of these elastomer at the high pressure, elevated temperatures they experience in operation is poorly understood. Consequently, the duty cycle of these materials is often deliberately limited to a few hours, and in order to prevent failure, production is stopped in order to change the seals in critical joints. The result is significant time lost due to bringing down production to change the seals as well as knock on financial costs. In order to address the fundamental nature of the elastomers at their intended operating conditions, we are studying the gas permeation behaviour of hydrogenated natural butyl rubber (HNBR) and fluorinated elastomers (FKM) at a high pressure and elevated temperature. We have developed a pressure system that permits gas permeation studies at gas pressures of up to 5000 psi and operating temperatures up to 150° C. In this paper, we will discuss the nature of the permeation behaviour at these extreme operating conditions, and how this relates to the changes in the polymer structure. We will also discuss the use of graphene-polymer thin layer coatings to modify the gas permeation behaviour of the elastomers.

Method for absorbing hydrogen using an oxidation resisant organic hydrogen getter

DOEpatents

Shepodd, Timothy J [Livermore, CA; Buffleben, George M [Tracy, CA

2009-02-03

A composition for removing hydrogen from an atmosphere, comprising a mixture of a polyphenyl ether and a hydrogenation catalyst, preferably a precious metal catalyst, and most preferably platinum, is disclosed. This composition is stable in the presence of oxygen, will not polymerize or degrade upon exposure to temperatures in excess of 200.degree. C., or prolonged exposure to temperatures in the range of 100-300.degree. C. Moreover, these novel hydrogen getter materials can be used to efficiently remove hydrogen from mixtures of hydrogen/inert gas (e.g., He, Ar, N.sub.2), hydrogen/ammonia atmospheres, such as may be encountered in heat exchangers, and hydrogen/carbon dioxide atmospheres. Water vapor and common atmospheric gases have no adverse effect on the ability of these getter materials to absorb hydrogen.

Hydrogen-storing hydride complexes

DOEpatents

Srinivasan, Sesha S [Tampa, FL; Niemann, Michael U [Venice, FL; Goswami, D Yogi [Tampa, FL; Stefanakos, Elias K [Tampa, FL

2012-04-10

A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

Anaerobic digestion of organic fraction of municipal solid waste combining two pretreatment modalities, high temperature microwave and hydrogen peroxide.

PubMed

Shahriari, Haleh; Warith, Mostafa; Hamoda, Mohamed; Kennedy, Kevin J

2012-01-01

In order to enhance anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW), pretreatment combining two modalities, microwave (MW) heating in presence or absence of hydrogen peroxide (H(2)O(2)) were investigated. The main pretreatment variables affecting the characteristics of the OFMSW were temperature (T) via MW irradiation and supplemental water additions of 20% and 30% (SWA20 and SW30). Subsequently, the focus of this study was to evaluate mesophilic batch AD performance in terms of biogas production, as well as changes in the characteristics of the OFMSW post digestion. A high MW induced temperature range (115-175°C) was applied, using sealed vessels and a bench scale MW unit equipped with temperature and pressure controls. Biochemical methane potential (BMP) tests were conducted on the whole OFMSW as well as the liquid fractions. The whole OFMSW pretreated at 115°C and 145°C showed 4-7% improvement in biogas production over untreated OFMSW (control). When pretreated at 175°C, biogas production decreased due to formation of refractory compounds, inhibiting the digestion. For the liquid fraction of OFMSW, the effect of pretreatment on the cumulative biogas production (CBP) was more pronounced for SWA20 at 145°C, with a 26% increase in biogas production after 8days of digestion, compared to the control. When considering the increased substrate availability in the liquid fraction after MW pretreatment, a 78% improvement in biogas production vs. the control was achieved. Combining MW and H(2)O(2) modalities did not have a positive impact on OFMSW stabilization and enhanced biogas production. In general, all samples pretreated with H(2)O(2) displayed a long lag phase and the CBP was usually lower than MW irradiated only samples. First order rate constant was calculated. Copyright © 2011 Elsevier Ltd. All rights reserved.

High-temperature-resistant distributed Bragg reflector fiber laser written in Er/Yb co-doped fiber.

PubMed

Guan, Bai-Ou; Zhang, Yang; Wang, Hong-Jun; Chen, Da; Tam, Hwa-Yaw

2008-03-03

We present a high-temperature-resistant distributed Bragg reflector fiber laser photowritten in Er/Yb codoped phosphosilicate fiber that is capable of long-term operation at 500 degrees C. Highly saturated Bragg gratings are directly inscribed into the Er/Yb fiber without hydrogen loading by using a 193 nm excimer laser and phase mask method. After annealing at elevated temperature, the remained gratings are strong enough for laser oscillation. The laser operates in robust single mode with output power more than 1 dBm and signal-to-noise ratio better than 70 dB over the entire temperature range from room temperature to 500 degrees C.

The Economic Potential of Nuclear-Renewable Hybrid Energy Systems Producing Hydrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruth, Mark; Cutler, Dylan; Flores-Espino, Francisco

This report is one in a series of reports that Idaho National Laboratory and the Joint Institute for Strategic Energy Analysis are publishing that address the technical and economic aspects of nuclear-renewable hybrid energy systems (N-R HESs). This report discusses an analysis of the economic potential of a tightly coupled N-R HES that produces electricity and hydrogen. Both low and high temperature electrolysis options are considered in the analysis. Low-temperature electrolysis requires only electricity to convert water to hydrogen. High temperature electrolysis requires less electricity because it uses both electricity and heat to provide the energy necessary to electrolyze water.more » The study finds that, to be profitable, the examined high-temperature electrosis and low-temperature electrosis N-R HES configurations that produce hydrogen require higher electricity prices, more electricity price volatility, higher natural gas prices, or higher capacity payments than the reference case values of these parameters considered in this analysis.« less

Two-temperature equilibration in warm dense hydrogen measured with x-ray scattering from the LCLS

NASA Astrophysics Data System (ADS)

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.

Low-Temperature Postfunctionalization of Highly Conductive Oxide Thin-Films toward Solution-Based Large-Scale Electronics.

PubMed

Ban, Seok-Gyu; Kim, Kyung-Tae; Choi, Byung Doo; Jo, Jeong-Wan; Kim, Yong-Hoon; Facchetti, Antonio; Kim, Myung-Gil; Park, Sung Kyu

2017-08-09

Although transparent conducting oxides (TCOs) have played a key role in a wide range of solid-state electronics from conventional optoelectronics to emerging electronic systems, the processing temperature and conductivity of solution-processed materials seem to be far exceeding the thermal limitations of soft materials and insufficient for high-perfomance large-area systems, respectively. Here, we report a strategy to form highly conductive and scalable solution-processed oxide materials and their successful translation into large-area electronic applications, which is enabled by photoassisted postfunctionalization at low temperature. The low-temperature fabrication of indium-tin-oxide (ITO) thin films was achieved by using photoignited combustion synthesis combined with photoassisted reduction process under hydrogen atmosphere. It was noteworthy that the photochemically activated hydrogens on ITO surface could be triggered to facilitate highly crystalline oxygen deficient structure allowing significant increase of carrier concentration and mobility through film microstructure modifications. The low-temperature postfunctionalized ITO films demonstrated conductivity of >1607 S/cm and sheet resistance of <104 Ω/□ under the process temperature of less than 300 °C, which are comparable to those of vacuum-deposited and high-temperature annealed ITO films. Based on the photoassisted postfunctionalization route, all-solution-processed transparent metal-oxide thin-film-transistors and large-area integrated circuits with the ITO bus lines were demonstrated, showing field-effect mobilities of >6.5 cm 2 V -1 s -1 with relatively good operational stability and oscillation frequency of more than 1 MHz in 7-stage ring oscillators, respectively.

Liquid metal hydrogen barriers

DOEpatents

Grover, George M.; Frank, Thurman G.; Keddy, Edward S.

1976-01-01

Hydrogen barriers which comprise liquid metals in which the solubility of hydrogen is low and which have good thermal conductivities at operating temperatures of interest. Such barriers are useful in nuclear fuel elements containing a metal hydride moderator which has a substantial hydrogen dissociation pressure at reactor operating temperatures.

Production of carbon monoxide-free hydrogen and helium from a high-purity source

DOEpatents

Golden, Timothy Christopher [Allentown, PA; Farris, Thomas Stephen [Bethlehem, PA

2008-11-18

The invention provides vacuum swing adsorption processes that produce an essentially carbon monoxide-free hydrogen or helium gas stream from, respectively, a high-purity (e.g., pipeline grade) hydrogen or helium gas stream using one or two adsorber beds. By using physical adsorbents with high heats of nitrogen adsorption, intermediate heats of carbon monoxide adsorption, and low heats of hydrogen and helium adsorption, and by using vacuum purging and high feed stream pressures (e.g., pressures of as high as around 1,000 bar), pipeline grade hydrogen or helium can purified to produce essentially carbon monoxide -free hydrogen and helium, or carbon monoxide, nitrogen, and methane-free hydrogen and helium.

Hydrogen storage in Earth's mantle and core

NASA Technical Reports Server (NTRS)

Prewitt, Charles T.

1994-01-01

Two different approaches to explaining how hydrogen might be stored in the mantle are illustrated by a number of papers published over the past 25-30 years, but there has been little attempt to provide objective comparisons of the two. One approach invokes the presence in the mantle of dense hydrous magnesium silicates (DHMS) stable at elevated pressures and temperatures. The other involves nominally anhydrous minerals (NAM) that contain hydrogen as a minor constituent on the ppm level. Experimental studies on DHMS indicate these phases may be stable to pressures and temperatures as high at 16 GPa and 1200 C. This temperature is lower than that indicated by a mantle geotherm at 16 GPa, but may be reasonable for a subducting slab. It is possible that other DHMS could be stable to even higher pressures, but little is known about maximum temperature limits. For NAM, small amounts of hydrogen (up to several hundred ppm) have been detected in olivine, orthopyroxene, clinopyroxene, and garnet recovered from xenoliths in kimberlites, eclogites, and alkali basalts; it has been demonstrated that synthetic wadsleyite and perovskite can accommodate significant amounts of hydrogen. A number of problems are associated with each possibility. For NAM originating in the mantle, one would like to assume that the hydrogen measured in samples recovered on Earth's surface was incorporated when the phase-crystallized at high temperatures and pressures, but it could have been introduced during transport to the surface. Major problems for the DHMS proponents are that none of these phases have been found as minerals and little is yet known about their stabilities in systems containing other cations such as Fe, Al, and Ca.

Criteria Development for Gas Turbine Premixer Flameholding Tendencies of Natural Gas and High Hydrogen Content Fuels

NASA Astrophysics Data System (ADS)

Sullivan-Lewis, Elliot Gregory

Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation, which reduces pollutant emissions but can result in flashback. Flashback can cause serious damage to the premixer hardware. Curtailing flashback can be difficult with hydrocarbon fuels and becomes even more challenging when the fuel contains hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design a premixer that will not anchor a flame if flashback occurs. Even with a well-designed combustor, flashback can occur under certain circumstances. Thus it is necessary to determine how to avoid flameholding within the premixer passageways of a gas turbine. To this end, an experiment was designed that would determine the flameholding propensities at elevated pressures and temperatures of three different classes of geometric features commonly found in gas turbine premixers, with both natural gas and hydrogen containing fuel. Experiments to find the equivalence ratio at blow off were conducted within an optically accessible test apparatus with four flameholders: 0.25 and 0.50 inch diameter cylinders, a reverse facing step with a height of 0.25 inches, and a symmetric airfoil with a thickness of 0.25 inches and a chord length of one inch. Tests were carried out at temperatures between 300 K and 750 K, at pressures up to 9 atmospheres. Typical bulk velocities were between 40 and 100 m/s. The effect of the airfoil's angle of rotation was also investigated. Blow off for hydrogen reactions was found to occur at much lower adiabatic flame temperatures than natural gas reactions. Additionally it was observed that at high pressures and high turbulence intensities, reactant velocity does not have a noticeable effect on the point of blow off due in large part to corresponding increases in turbulent flame speed. Finally a semi empirical correlation was developed that predicts flame

Method of gettering hydrogen under conditions of low pressure

DOEpatents

Mendelsohn, M.H.; Gruen, D.M.

1983-08-09

A ternary intermetallic compound having the formula Zr(V[sub 1[minus]x]Cr[sub x])[sub 2] where x is in the range of 0.01 to 0.90 is capable of reversibly sorbing hydrogen at temperatures ranging from room temperature to 200 C, at pressures down to 10[sup [minus]6] Torr. The compound is suitable for use as a hydrogen getter in low pressure, high temperature applications such as magnetic confinement fusion devices. 3 figs.

Hydrogenated TiO 2@reduced graphene oxide sandwich-like nanosheets for high voltage supercapacitor applications

DOE PAGES

Pham, Viet Hung; Nguyen-Phan, Thuy-Duong; Tong, Xiao; ...

2017-10-09

Hydrogenated TiO 2 has recently attracted considerable attention as potential electrode materials for supercapacitors due to its abundance, low cost, high conductivity, remarkable rate capability, and outstanding long-term cycling stability. In this paper, we demonstrate the synthesis of hydrogenated TiO 2 nanoparticles anchored on reduced graphene oxide nanosheets (HTG) in the form of sandwich-like nanosheet composites. Further, we explored their implementation as electrode materials for high voltage, symmetric supercapacitors, operating in the voltage window of 0–1.8 V. The HTGs were prepared by a sol-gel method, followed by hydrogenation in the temperature range 300–500 °C. Of the prepared composites, HTG preparedmore » at 400 °C exhibited the largest specific capacitance of 51 F g -1 at the current density of 1.0 A g -1 and excellent rate capability with 82.5% capacitance retention as the current density increased 40-fold, from 0.5 to 20.0 A g -1. HTG's excellent rate capability was attributed to its sandwich-like nanostructure, in which ultrasmall hydrogenated TiO 2 nanoparticles densely anchored onto both surfaces of the two-dimensional reduced graphene oxide sheets. Moreover, HTG-based supercapacitors also exhibited long-term cycling stability with the retention over 80% of its initial capacitance after 10,000 cycles. Finally, these properties suggest that HTG is a promising electrode material for the scalable manufacture of high-performance supercapacitors.« less

Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verona, C.; Marinelli, Marco; Verona-Rinati, G.

We report on a comparative study of transfer doping of hydrogenated single crystal diamond surface by insulators featured by high electron affinity, such as Nb{sub 2}O{sub 5}, WO{sub 3}, V{sub 2}O{sub 5}, and MoO{sub 3}. The low electron affinity Al{sub 2}O{sub 3} was also investigated for comparison. Hole transport properties were evaluated in the passivated hydrogenated diamond films by Hall effect measurements, and were compared to un-passivated diamond films (air-induced doping). A drastic improvement was observed in passivated samples in terms of conductivity, stability with time, and resistance to high temperatures. The efficiency of the investigated insulators, as electron acceptingmore » materials in hydrogenated diamond surface, is consistent with their electronic structure. These surface acceptor materials generate a higher hole sheet concentration, up to 6.5 × 10{sup 13} cm{sup −2}, and a lower sheet resistance, down to 2.6 kΩ/sq, in comparison to the atmosphere-induced values of about 1 × 10{sup 13} cm{sup −2} and 10 kΩ/sq, respectively. On the other hand, hole mobilities were reduced by using high electron affinity insulator dopants. Hole mobility as a function of hole concentration in a hydrogenated diamond layer was also investigated, showing a well-defined monotonically decreasing trend.« less

Hydrogenated TiO 2@reduced graphene oxide sandwich-like nanosheets for high voltage supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pham, Viet Hung; Nguyen-Phan, Thuy-Duong; Tong, Xiao