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Auswahl der wissenschaftlichen Literatur zum Thema „Porosité hydrogène“
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Zeitschriftenartikel zum Thema "Porosité hydrogène"
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TIMOFEEVА, A. S., A. A. KOZHUKHOV, T. V. NIKITCHENKO und S. N. NEMYKIN. „THE EFFECT OF THE POROSITY OF HOT-BRIQUETTED IRON ON THE RELEASE OF HYDROGEN DURING SECONDARY OXIDATION WITH WATER OF DIFFERENT TEMPERATURES“. Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 78, Nr. 4 (11.05.2022): 322–29. http://dx.doi.org/10.32339/0135-5910-2022-4-322-329.
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During storage and transportation of the metallized product, moisture may enter it, resulting its oxidation occurring with the release of hydrogen. When delivering the product by sea, this can lead to fire and explosive situation. It is noted that the physicochemical properties of the metallized product, such as density, porosity, chemical composition, temperature, etc., have a great influence on the release of hydrogen. The purpose of this work is to determine the dependence of hydrogen release during iron oxidation in the metallized briquettes on their porosity and the temperature of the humidifying water. The results of study of the effect of porosity on the density of HBI are presented; the limits of changes in closed and open porosity and their effect on density were determined. It is shown that the bulk density of briquettes decreases with an increase in the porosity of HBI. The experiments were performed in order to determine the dependence of hydrogen release upon contact of briquettes with distilled water on the porosity and water temperature. It was found that with an increase in the open porosity of briquettes, their moisture saturation increases and the release of hydrogen increases. A change in the temperature of water that reacts with iron affects the release of hydrogen, but it practically does not affect the release rate within the parameters studied. When transporting the metallized briquettes it is recommended to take into account the effect of their open porosity on the intensity of hydrogen release in contact with moisture.
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Li, Wen Qiong, Xiang Ming Li, Qing Lin Jin und Rong Zhou. „Evolution of Porosity in Lotus-Type Porous Copper Fabricated by Continuous Casting Technique“. Applied Mechanics and Materials 278-280 (Januar 2013): 433–36. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.433.
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Lotus-type porous copper materials were fabricated by continuous casting technique. The relationship between porosity and external pressure were developed based on the solute mass conservation law. Theoretical values of porosity are in agreement with our experimental results. Results show that porosity decreases when the partial pressure of hydrogen increases for cases of no pressure of argon above melt, while porosity first increases and then decreases as the partial pressure of hydrogen increases for case of nonzero pressure of argon above melt.
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Kotian, Ravindra, Madhu Keshava Bangera, Karen Boaz und Prashanthi S. Madhyastha. „Effect of plasma gas atmosphere on hydroxyapatite-coated titanium-based implants“. Metallurgical Research & Technology 118, Nr. 1 (30.11.2020): 103. http://dx.doi.org/10.1051/metal/2020072.
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The study was designed to understand the influence of different atmospheres of plasma gas on hydroxyapatite-coated commercially pure Titanium (Ti) and titanium alloy (Ti-6Al-4V). Ti and Ti-6Al-4V were plasma spray-coated with hydroxyapatite in argon, nitrogen, argon/hydrogen, and nitrogen/hydrogen atmospheres. The microstructure, porosity, calcium to phosphate (Ca-P) ratio, surface roughness, and hardness of the coat were characterized using a scanning electron microscope, energy dispersive spectroscopy, image analyzer, profilometer, and Vickers hardness tester. The analyses of the coatings obtained in different plasma gas atmospheres showed variation in microstructure, morphology, porosity, surface roughness, and hardness. As the enthalpy decreased, an increase in porosity was observed in nitrogen/hydrogen, nitrogen, argon/hydrogen, and argon atmospheres, respectively. Peak Ca-P ratio was observed in argon, which is the most inert atmosphere compared to other tested plasma atmospheres. Atmospheres with high enthalpy presented an even surface with comparatively low surface roughness. Hardness value decreased with increasing porosity. The plasma gas atmosphere has a significant influence on Ca-P ratio, porosity, and microcracks of hydroxyapatite-coated oral implants.
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Cao, Rong, und Qing Lin Jin. „Theoretical Analysis of Porosity in an Ordered Porous Copper Fabricated by Continuous Unidirectional Solidification“. Materials Science Forum 933 (Oktober 2018): 136–41. http://dx.doi.org/10.4028/www.scientific.net/msf.933.136.
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Ordered porous copper with elongated pores has been fabricated by a continuous unidirectional solidification method in a hydrogen gas atmosphere with high pressure. The porosity of the ordered porous copper is significantly affected by the pressure of hydrogen. A theoretical model is developed to get the relation between the porosity and the processing parameters. The calculated values are in good agreement with the experimental results. Key words: Unidirectional solidification; Ordered porous copper; Porosity; Modeling.
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Bechelany, Mikhael, Adib Abou Chaaya, Fabien Frances, Ouardia Akdim, Didier Cot, Umit B. Demirci und Philippe Miele. „Nanowires with controlled porosity for hydrogen production“. J. Mater. Chem. A 1, Nr. 6 (2013): 2133–38. http://dx.doi.org/10.1039/c2ta00794k.
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Dispinar, D., S. Akhtar, A. Nordmark, M. Di Sabatino und L. Arnberg. „Degassing, hydrogen and porosity phenomena in A356“. Materials Science and Engineering: A 527, Nr. 16-17 (Juni 2010): 3719–25. http://dx.doi.org/10.1016/j.msea.2010.01.088.
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Ide, Takuya, Masakazu Tane und Hideo Nakajima. „Fabrication of Lotus-Type Porous NiAl and Ni3Al Intermetallic Compounds“. Solid State Phenomena 124-126 (Juni 2007): 1721–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1721.
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Lotus-type porous NiAl and Ni3Al intermetallic compounds, possessing cylindrical pores aligned in the direction parallel to the solidification direction, were fabricated by using a unidirectional solidification technique in a pressurized hydrogen atmosphere of 2.5MPa. The porosity of lotus NiAl is 24.2 %, and the porosity of lotus Ni3Al is 3.2%; the porosity of the porous NiAl is larger than that of Ni3Al. This is because the solubility gap of hydrogen between liquid and solid phases of NiAl is larger than that of Ni3Al.
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BARRAZA, ALEXYIA M., CARL EDWARD CROSS, CHRISTOPHER JASON STULL, JESSE N. MARTINEZ und CAROLIN FINK. „Applying In-Situ Radiography to Study Porosity Formation in Aluminum Welds“. Welding Journal 102, Nr. 1 (01.01.2023): 1–12. http://dx.doi.org/10.29391/2023.102.001.
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In-situ radiographic aluminum welding experiments were set up to observe the porosity formation and movement in aluminum weld pools. Aluminum Alloys 1100, 4047, and 6061 were autogenously gas tungsten arc welded while digitally recording radiograph images of macropores. Hydrogen was added in controlled parts per million through an argon-hydrogen shielding gas. The shielding gas hydrogen varied between 0 and 1000 parts per million of hydrogen, and three travel speeds were tested: 1.69, 2.54, and 3.39 mm/s. The transfer of hydrogen from the arc plasma to the weld pool was characterized using postweld gravimetric measurements to get the total pore volume and calculate weld metal hydrogen content. The amount of hydrogen added through the shielding gas played an important role in macropore volume and growth rate. Welding travel speed likewise played a critical role in hydrogen pickup. Alloy 1100 macropores originated at the bottom of the weld pool and then migrated upward toward the rear of the pool. Macropores in Alloys 4047 and 6061 originated at the leading edge of the weld pool and then moved downward and toward the rear of the pool. It is hypothesized that this difference in behavior is related to Marangoni-controlled fluid flow in Alloys 4047 and 6061.
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Muhammad Shahrul Nizam Shahrin, Norazila Othman, Nik Ahmad Ridhwan Nik Mohd, Mastura Ab Wahid und Mohd Zarhamdy Md. Zain. „Porosity Effect of the Silver Catalyst in Hydrogen Peroxide Monopropellant Thruster“. CFD Letters 13, Nr. 12 (17.12.2021): 1–20. http://dx.doi.org/10.37934/cfdl.13.12.120.
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In monopropellant system, hydrogen peroxide is used with catalyst to create an exothermic reaction. Catalyst made of silver among the popular choice for this application. Since the catalyst used is in porous state, the effect of its porosity in the hydrogen peroxide monopropellant thruster performances is yet unknown. The porosity changes depending on factors including catalyst pact compaction pressure, bed dimension, and type of catalyst used. As researches on this topic is relatively small, the optimum porosity value is usually left out. The performance of the thruster indicated by the pressure drop across the catalyst bed. Porosity of the catalyst bed adds additional momentum sink to the momentum equation that contributes to the pressure gradient which lead to pressure loss inside thruster. The effect of porosity influences the performance and precision of the thruster. Study of the pressure drop by the catalyst bed requires a lengthy period and expensive experiments, however, numerical simulation by mean of Computational Fluid Dynamics (CFD) can be an alternative. In this paper, 90 wt% hydrogen peroxide solution with silver catalyst is studied in order to investigate the influence of porosity to the performances of the thruster, and to find the optimum porosity of the thruster. Species transport model is applied in the single-phase reaction simulation using the EDM for turbulence-chemistry interaction. Through this study, the effect of porosity towards the thruster performances represented in term of pressure drop, exit velocity, bed temperature, and thrust, and porosity of 0.4 found to be as an optimal value.
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Dudun, Anireju, Yin Feng und Boyun Guo. „Numerical Simulation of Hydrogen Diffusion in Cement Sheath of Wells Used for Underground Hydrogen Storage“. Sustainability 15, Nr. 14 (11.07.2023): 10844. http://dx.doi.org/10.3390/su151410844.
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The negative environmental impact of carbon emissions from fossil fuels has promoted hydrogen utilization and storage in underground structures. Hydrogen leakage from storage structures through wells is a major concern due to the small hydrogen molecules that diffuse fast in the porous well cement sheath. The second-order parabolic partial differential equation describing the hydrogen diffusion in well cement was solved numerically using the finite difference method (FDM). The numerical model was verified with an analytical solution for an ideal case where the matrix and fluid have invariant properties. Sensitivity analyses with the model revealed several possibilities. Based on simulation studies and underlying assumptions such as non-dissolvable hydrogen gas in water present in the cement pore spaces, constant hydrogen diffusion coefficient, cement properties such as porosity and saturation, etc., hydrogen should take about 7.5 days to fully penetrate a 35 cm cement sheath under expected well conditions. The relatively short duration for hydrogen breakthrough in the cement sheath is mainly due to the small molecule size and high hydrogen diffusivity. If the hydrogen reaches a vertical channel behind the casing, a hydrogen leak from the well is soon expected. Also, the simulation result reveals that hydrogen migration along the axial direction of the cement column from a storage reservoir to the top of a 50 m caprock is likely to occur in 500 years. Hydrogen diffusion into cement sheaths increases with increased cement porosity and diffusion coefficient and decreases with water saturation (and increases with hydrogen saturation). Hence, cement with a low water-to-cement ratio to reduce water content and low cement porosity is desirable for completing hydrogen storage wells.
Dissertationen zum Thema "Porosité hydrogène"
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Fondement, Valentin. „Conception d'une sonde diagraphique neutronique dans le cadre de l'exploration et de l'exploitation minière de l'uranium“. Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALY076.
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Cette thèse s’inscrit dans le cadre d’une collaboration entre le CEA et ORANO Mining avec pour objectif de développer une nouvelle sonde diagraphique basée sur l’interrogation neutronique active, dans le cadre de l’exploration et de l’exploitation de l’uranium dont une part importante de la production provient aujourd’hui de mines utilisant la lixiviation in situ. L’extraction chimique du minerai s’effectue directement dans le sol, sur plusieurs centaines de mètres, par injection et collection de solutions chimiques. Pour évaluer la rentabilité du puits, il est non seulement nécessaire de connaitre la quantité d’uranium disponible, mais aussi la perméabilité du milieu géologique. Cette dernière est déterminée en mesurant la « porosité hydrogène », à savoir la fraction volumique de la roche occupée par de l’eau, à l’aide de sondes qui émettent puis mesurent des neutrons ayant diffusé sur les noyaux d’hydrogène. L’uranium, et plus précisément son isotope 235, est aussi mesurable à l’aide de sondes équipées d’un générateur de neutrons pulsé. Ces travaux de recherche ont abouti à la conception d’une sonde permettant de réaliser ces deux mesures avec un unique compteur proportionnel à hélium 3 entouré de polyéthylène et blindé avec du cadmium. Des impulsions de neutrons de durée 50 µs sont émises par le générateur toutes les 5 ms (à 200 Hz). Puis, au cours des 800 µs qui suivent l’arrêt de chaque tir, on mesure les neutrons diffusés dans la formation qui ne sont pas thermalisés entièrement et peuvent encore franchir le blindage en cadmium. On obtient un comptage inversement proportionnel à la quantité d’hydrogène présente dans l’environnement. Sur les millisecondes qui suivent, les neutrons thermiques encore présents dans la roche font fissionner des noyaux d’235U, ce qui émet en moyenne 2.5 neutrons prompts par fission. Une partie de ces derniers sont mesurés par le bloc de détection, tandis que les neutrons du générateur, devenus thermiques 800 µs après l’arrêt du tir, ne peuvent plus franchir le blindage en cadmium. Grace à cette double discrimination, temporelle et énergétique, on peut mesurer le signal des neutrons prompts de fission qui est proportionnel à la concentration en uranium. Le flux de neutrons thermiques interrogateurs étant absorbé par l’hydrogène présent dans l’environnement, on utilise la porosité hydrogène mesurée pour corriger le signal des neutrons prompts de fission. Après avoir étudié par simulation Monte-Carlo les grandeurs affectant les performances de ces deux mesures (diamètre de forage, décentrage de la sonde, épaisseur et matériau de tubage, gangue de boue, lithologie), nous avons validé expérimentalement leur faisabilité en laboratoire. Tout d’abord, plusieurs chaines d’acquisition ont été testées pour pouvoir mesurer des taux de comptage instantanés de l’ordre de 106 s-1, pendant et juste après chaque tir du générateur de neutrons. D’autre part, une sonde maquette de laboratoire a été réalisée et testée dans un fût d’étalonnage rempli de 1.6 t de sable de Fontainebleau, spécialement conçu pour ces essais. Un bon accord entre l’expérience et les simulations a permis de valider la mesure de teneur en uranium et d’appréhender de nouveaux phénomènes, notamment l’activation de l’oxygène 17 responsable d’un bruit d’un fond actif significatif dans les formations siliceuses saturées en eau. La qualification des méthodes de calcul du signal et du bruit a été menée à bien, ce qui a permis d’estimer les performances prévues en situation réelle, notamment des limites de détection entre 10 et 200 ppm en 3 min de mesure pour des porosité hydrogènes respectives de 0 et 40%This PhD in the frame of CEA - ORANO Mining collaboration, aims to develop a new logging tool, based on neutron active interrogation, in the scope of uranium exploration and exploitation. A large amount of its production comes from In situ recovery mines, by leaching chemically the ore in the ground over hundreds of meters. It is mandatory to determine the amount of uranium available, but also the permeability of the sand, to evaluate the profitability. This geological quantity can be assessed from the measurement of the porosity hydrogen that is the volume fraction of water in the rock formation. It is possible to measure this one by using neutron probes. Uranium, and especially its 235 isotope, can also be measured with that kind of logging tools, if they rely on a pulsed neutron generator. This research leads to a new probe design that allows performing the both measurements with a unique cadmium-shielded-helium 3-proportional counter. The generator emits a 50 µs neutron burst every 5 ms (at 200 Hz). In the 800 µs after the salvo we can measure the not-fully-thermalised neutrons, thanks to the cadmium shield acting like a filter. The obtained count is inversely proportional to the hydrogen, and water, environment content. Over the following milliseconds, thermal neutrons of the rock formation will lead to 235U nuclei fissions, which emit in average 2.5 prompt fission neutrons. A chunk of these neutrons is emitted toward our counter, as the neutrons from the generator, fully thermalized after 800 µs, cannot cross the cadmium. Thanks to that double energy-time discrimination, it is possible to measure the prompt fission neutron signal contribution, which is proportional to the uranium concentration. As thermal neutrons are absorbed by the hydrogen content in the environment, we can use the porosity hydrogen measurement to correct the prompt fission neutrons signal from its effect. Furthermore, a parametric study has been conducting, using the Monte-Carlo simulation code MCNP 6.1, to compare the quantities that affect the measurements performances (e.g. diameter, standoff, casing thickness, casing, mudcake thickness, lithology). Finally, the new measurement methods feasibility has been validated through two experimental campaigns: in one hand, the capability of the electronics to handle input count rates in the 106 s-1 yield, during and right after a pulse of the neutron D-T generator. In the other hand, a laboratory model of the neutron probe has been built and tested in a dedicated calibration drum, filled with 1.6 t Fontainebleau sand. An agreement between experiment and computer simulations has been found, which validates the uranium concentration measurement and allows the understanding of the main components of the active background. This study highlighted the contribution of the oxygen 17 activation delayed neutrons, in the water saturated sandstone environments. The signal and noise analysis method were qualified, leading to the first estimations of in situ performances, like the detection limit of the uranium concentration measurement, from 10 to 200 ppm for 3 min of acquisition, for hydrogen porosities ranging respectively from 0 to 40%
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Boulin, Pierre. „Expérimentation et Modélisation du Transfert d'hydrogène à travers des argiles de centre de stockage de déchets radioactifs“. Phd thesis, Grenoble INPG, 2008. http://tel.archives-ouvertes.fr/tel-00331826.
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Des gaz vont être générés par corrosion des conteneurs de déchets radioactifs au niveau d'un stockage en couche géologique profonde. Une bulle de gaz se crée et monte en pression. Si le gaz pénètre difficilement la formation géologique, l'augmentation de pression pourra la fissurer et créer des chemins préférentiels à la migration de radionucléides. Les argilites du Callovo-Oxfordien sont ici caractérisées. Un dispositif permettant de mesurer de très faibles perméabilités à l'hydrogène/hélium a été utilisé couplé au Dusty Gas Model. Les argilites proches de la saturation ont une porosité accessible au gaz inférieure à 1% voire 0,1% de la porosité totale. A partir de l'étude de l'effet Knudsen cette porosité pourrait être due à des pores de 50 à 200 nm de diamètre mis en évidence lors de la caractérisation des réseaux. En intégrant ces résultats dans un modèle opérationnel de l'ANDRA, la pression maximale atteinte au sein d'une alvéole de stockage serait de 83 bar.
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Boulin, Pierre. „Expérimentation et modélisation du transfert d'hydrogène à travers des argiles de centre de stockage de déchets radioactifs“. Phd thesis, Grenoble INPG, 2008. http://www.theses.fr/2008INPG0086.
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Des gaz vont être générés par corrosion des conteneurs de déchets radioactifs au niveau d'un stockage en couche géologique profonde. Une bulle de gaz se crée et monte en pression. Si le gaz pénètre difficilement la formation géologique, l'augmentation de pression pourra la fissurer et créer des chemins préférentiels à la migration de radionucléides. Les argilites du Callovo-Oxfordien sont ici caractérisées. Un dispositif permettant de mesurer de très faibles perméabilités à l'hydrogène/hélium a été utilisé couplé au Dusty Gas Model. Les argilites proches de la saturation ont une porosité accessible au gaz inférieure à 1% voire 0,1% de la porosité totale. A partir de l'étude de l'effet Knudsen cette porosité pourrait être due à des pores de 50 à 200 nm de diamètre mis en évidence lors de la caractérisation des réseaux. En intégrant ces résultats dans un modèle opérationnel de l'ANDRA, la pression maximale atteinte au sein d'une alvéole de stockage serait de 83 barGases will be generated by corrosion of high radioactive waste containers in deep geological repositories. A gas phase will be generated. Gas pressure will build up and penetrated the geological formation. If gases do not penetrate the geological barrier efficiently, the pressure build up may create a risk of fracturation and of creation of preferential pathways for radionuclide migration. The present work focuses on Callovo-Oxfordian argillites characterisation. An experiment, designed to measure very low permeabilities, was used with hydrogen/helium and analysed using the Dusty Gas Model. Argillites close to saturation have an accessible porosity to gas transfer that is lower than 0,1% to 1% of the porosity. Analysis of the Knudsen effect suggests that this accessible network should be made of 50 nm to 200 nm diameter pores. The permeabilities values were integrated to an ANDRA operating model. The model showed that the maximum pressure expected near the repository would be 83 bar
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Mirzaei, Behzad. „Oxide Hydrogen Interaction and Porosity Development in Al-Si Foundry Alloys“. Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16352.
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The oxide level of an A356 aluminium alloy will be controlled by (i) melting, casting and remelting A356 aluminium alloy for increasing the bi-films levels in the melt, and by (ii) additions of an extruded aluminium oxide rod directly to the melt. A clean A356 melt (no additions of any particulates) will be used as reference material. The melting experiments will be conducted in an electric resistance furnace under carefully controlled conditions. The three crucible experimental set-up, designed by SINTEF Materials and Chemistry, will be adopted to secure identical conditions for all three melts to be investigated. From each of the melts a series of reproducible castings will be made for tensile test measurements, as well as bend tests. The results from these tests will be statistically analysed. For the assessment of melt quality, in terms of inclusion count and bi-films index, the Porous Disc Filtration Apparatus (PoDFA) and the Reduced Pressure Test (RPT) will be adopted. For the analysis of fracture behaviour Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDX) will be use. The dissolved hydrogen level will be measured by adopting an ALSPEC H probe.If time is given, the data generated in the present work will be compared with results previously obtained by SINTEF Materials and Chemistry for experiments conducted under similar conditions. It is believed that the results from the present study will provide a sound basis for understanding the fundamentals of the key issues involve in the production of high quality aluminium castings.
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Lee, Peter D. „The formation of hydrogen porosity during the solidification of aluminium alloys“. Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318700.
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Salameh, Chrystelle Mounir. „Synthèse de matériaux nitrures fonctionnels à base de bore ou d'aluminium pour des applications en énergie (production et stockage de l'hydrogène)“. Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20157/document.
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Les matériaux céramiques poreux présentent des propriétés de grand intérêt grâce à leur potentiel dans les applications de l'énergie. L'objectif général de cette thèse concerne le développement de matériaux (carbo)nitrures pour la production et le stockage de l'hydrogène (synthèse, caractérisation, propriétés et applications). La voie polymère précéramique, offrant un grand nombre de possibilités dans la chimie et la science des céramiques, est utilisée pour élaborer ces matériaux. Tout d'abord, nous avons préparé les systèmes binaires poreux tels que AlN et BN en répliquant la structure du CMK-3 et du charbon actif. Après pyrolyse, nous avons démontré la faisabilité de produire des nitrures avec une porosité adaptée. Par ailleurs, en couplant la voie polymère précéramique avec la technologie des aérogels, nous avons réussi à préparer des aérogels AlN et BN avec une porosité relativement élevée. Nous avons évalué le potentiel de ces matériaux poreux pour le nanoconfinement de deux hydrures chimiques, l'alanate de sodium et l'ammoniaborane, respectivement. Dans les deux cas, la nanoconfinement a déstabilisé le réseau de l'hydrure et a permis la libération de H2 à de basses températures ; en outre, dans le cas de l'ammoniaborane confiné, aucun sous-produit gazeux indésirable n'a été détectée, ce qui confirme la pureté du H2 dégagé. Deuxièmement, nous avons préparé des systèmes quaternaires poreux par association de AlN/BN avec des céramiques à base de silicium. En particulier, nous avons élaboré des céramiques SiAlCN en utilisant deux approches: la voie à « 2 sources » et la voie à « source unique ». En ce qui concerne la première, nous avons préparé des matériaux mésoporeux ordonnés qui ont été utilisés comme supports catalytiques pour l'hydrolyse d'une solution alcaline de borohydrure de sodium. Nous avons réussi à générer du H2 avec des cinétiques élevées. En ce qui concerne la seconde approche, le travail a porté sur l'étude de la chimie de matériaux SiAlCN et SiBCN. Des mousses cellulaires SiAlCN ont été préparées par l'utilisation de charges sacrificiellesPorous inorganic materials are of great interest owing to their potential in energy applications. The general objective of the present thesis concerns the development of functional (carbo)nitrides for hydrogen generation and storage (material design, elaboration, properties and applications). The PDCs route, which offers a large number of opportunities in chemistry and ceramic sciences, has been applied to produce functional (carbo)nitrides materials. Firstly, we prepared porous binary systems such as AlN and BN by replicating the structure of CMK-3 and that of activated carbon. After pyrolysis and removal of the template, we demonstrated the feasibility of producing nitrides with tailored porosity. Moreover, by coupling the PDCs route with the aerogel technology, we succeeded in preparing polymer-derived AlN and BN aerogels. We assessed the potential of these porous AlN and BN materials in nanoconfinement of two chemical hydrides, namely sodium alanate and ammoniaborane, respectively. In both cases, the nanoconfinement destabilized the network of the hydride and favored the release of H2 at low temperature. Besides, in the case of nanoconfined ammoniaborane, no evolution of undesired gaseous by-products was observed, which means that pure hydrogen was produced in our conditions. Secondly, we prepared porous quaternary systems through the association of AlN/BN with Si-based ceramics. In particular, we investigated the preparation of SiAlCN with tailored porosity by using two approaches: the “molecular building block” and “single-source precursor” approaches. Concerning the former, we investigated the preparation of ordered mesoporous materials to be used as catalytic supports for hydrolysis of alkaline solution of sodium borohydride. We succeeded in generating high amounts of H2 with attractive kinetics. Concerning the latter approach, the work was focused on the investigation of the chemistry of SiAlCN and SiBCN materials with a particular focus on the elaboration of SiAlCN microcellular foams by a sacrificial processing route
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Bagetakos, Ioannis. „Shells, bubbles and holes : the porosity of the interstellar medium in galaxies“. Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/9085.
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We present an analysis of the properties of HI holes detected in 20 galaxies that are part of “The HI Nearby Galaxy Survey” (THINGS). We detected more than 1000 holes in total in the sampled galaxies. Where they can be measured, their sizes range from about 100 pc (our resolution limit) to about 2 kpc, their expansion velocities range from 4 to 36 km/s, and their ages are estimated to range between 3 and 150 Myr. The holes are found throughout the discs of the galaxies, out to the edge of the HI disc; 23% of the holes fall outside R25. We find that shear limits the age of holes in spirals; shear is less important in dwarf galaxies which explains why HI holes in dwarfs are rounder, on average than in spirals. Shear, which is particularly strong in the inner part of spiral galaxies, also explains why we find that holes outside R25 are larger and older. We derive the scale height of the HI disc as a function of galactocentric radius and find that the disc flares at large radii in all galaxies. We proceed to derive the surface and volume porosity (Q2D and Q3D) and find that this correlates with the type of the host galaxy: later Hubble types tend to be more porous. The size distribution of the holes in our sample follows a power law with a slope of a=−2.9. Assuming that the holes are the result of massive star formation, we derive values for the supernova rate (SNR) and star formation rate (SFR) which scales with the SFR derived based on other tracers. If we extrapolate the observed number of holes to include those that fall below our resolution limit, down to holes created by a single supernova, we find that our results are compatible with the hypothesis that HI holes result from star formation. We use HI data from THINGS, 8μm, 24μm, 70μm and HI maps from SINGS, CO(2–1) data from HERACLES and FUV data from NGS to present a visual comparison of these maps with respect to the locations of HI holes. We find that the vast majority of HI holes are also prominent in the 8μm map and to some extent in the 24μm map. There is a lack of molecular gas from the interior of nearly all the holes, which is consistent with the idea that the latter are filled with hot gas. About 60% of young holes have FUV emission detected in their interiors highlighting the presence of the parent OB association. In addition, FUV is detected on the rims of some of the older HI holes, presumably due to the dispersion of the OB association with respect to the gas. We describe the development of a 2–D cross-correlation method to compare multi-wavelength maps in a quantitative way (quantified by Ccoef ) and give some first results from the application of this method to the nearby galaxy NGC2403. We find that the all the dust tracers are well correlated (Ccoef > 0.7) with the 8μm–24μm correlation being the highest (Ccoef > 0.88). Similarly all the star formation tracers are well linked as expected (Ccoef > 0.6). With respect to the relations between star formation and dust tracers we found that most are well matched (Ccoef > 0.7) as dust grains are heated by radiation in star forming regions. At smaller scales (15") FUV correlates poorly (Ccoef ~ 0.3) with the dust tracers, a direct consequence of the absorption of FUV photons by dust. We find that the HI is reasonably well correlated with the 8μm emission (Ccoef ~ 0.6) illustrating the fact that HI is mixed with PAH’s. Interestingly, the HI map shows some correlation with the SF map (Ccoef ~ 0.4) even though FUV and HI emissions were found to be completely uncorrelated (Ccoef ~ 0).
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Anghel, Clara. „Modified oxygen and hydrogen transport in Zr-based oxides“. Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4095.
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Alat, Ece. „Analysis Of Magnesium Addition, Hydrogen Porosity And T6 Heat Treatment Effecrts On Mechanical And Microstructural Properties Of Pressure Die Cast 7075 Aluminum Alloy“. Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615018/index.pdf.
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Aluminum alloys are having more attention due to their high specific stiffness and processing advantages. 7075 aluminum alloy is a wrought composition aluminum alloy in the Al-Zn-Mg-Cu series. Due to the significant addition of these alloying
elements, 7075 has higher strength compared to all other aluminum alloys and effective precipitation hardenability characteristic.
On the other hand, aluminum alloys have some drawbacks, which hinder the widespread application of them. One of the most commonly encountered defects in aluminum alloys is the hydrogen porosity. Additionally, in case of 7075, another problem is the lack of fluidity. Magnesium addition is thought to be effective in compensating this deficiency. Accordingly, in this study, die cast 7075 aluminum alloy samples with hydrogen porosity and additional magnesium content were
investigated. The aim was to determine the relationship between hydrogen content and hydrogen porosity, and the effects of hydrogen porosity, additional magnesium
and T6 heat treatment on ultimate tensile and flexural strength properties of pressure die cast 7075 aluminum alloy.
7075 aluminum alloy returns were supplied from a local pressure die casting company. After spectral analysis, pressure die casting was conducted at two stages.
In the first stage, 7075 aluminum alloy with an increase in magnesium concentration was melted and secondly 7075 aluminum alloy was cast directly without any alloying addition. While making those castings, hydrogen content was
measured continuously before each casting operation. As a final operation T6 heat treatment is carried out for certain samples. Finally, in order to accomplish our aim,
mechanical and microstructural examination tests were conducted.
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Haurais, Florian. „Evaluate the contribution of the fuel cladding oxidation process on the hydrogen production from the reflooding during a potential severe accident in a nuclear reactor“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS375/document.
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En centrales nucléaires, un accident grave est une séquence très peu probable d’événements durant laquelle des composants du réacteur sont significativement endommagés, par interactions chimiques et/ou fusion, à cause de très hautes températures. Cela peut mener à des rejets radiotoxiques dans l’enceinte et à une entrée d’air dans le réacteur. Dans ce contexte, ce travail de thèse mené chez EDF R&D visait à modéliser la détérioration du gainage combustible, en alliages de zirconium, en conditions accidentelles : haute température et soit vapeur soit mélange air-vapeur. L’objectif final était d’améliorer la simulation par le code MAAP de l’oxydation du gainage et de la production d’hydrogène, en particulier pendant un renoyage avec de l’eau. Dû à l’épaississement progressif d’une couche de ZrO2 dense et protectrice, la cinétique d’oxydation du Zr en vapeur à hautes températures est généralement (sous-)parabolique. Cependant, à certaines températures, cette couche d’oxyde peut se fissurer, devenant poreuse et non protectrice. Par ce processus de « breakaway », la cinétique d’oxydation devient plus linéaire. De plus, l’augmentation de température peut mener les matériaux du réacteur à fondre et à se relocaliser dans le fond de cuve dont la rupture peut induire une entrée d’air dans le réacteur. Dans ce cas, l’oxygène et l’azote réagissent avec les gaines pré-oxydées, successivement par oxydation du Zr (épaississant la couche de ZrO2), nitruration du Zr (formant des particules de ZrN) et oxydation du ZrN (créant de l’oxyde et relâchant de l’azote). Ces réactions auto-entretenues relancent la fissuration du gainage et de sa couche de ZrO2, induisant une hausse de sa porosité ouverte. Afin de quantifier cette porosité du gainage, un protocole expérimental innovant en deux étapes a été défini et appliqué : il consistait à soumettre des échantillons de gainage en ZIRLO® à diverses conditions accidentelles pendant plusieurs durées puis à des mesures de la porosité ouverte par porosimétrie par intrusion de mercure. Les conditions de corrosion comprenaient plusieurs températures allant de 1100 à 1500 K ainsi que de la vapeur et un mélange air-vapeur 50-50 mol%. Pour les échantillons de ZIRLO® oxydés en vapeur, sauf à 1200 et 1250 K, les transitions de cinétique n’ont pas lieu et la porosité ouverte reste négligeable au cours de l’oxydation. Cependant, pour les autres échantillons, corrodés en air-vapeur ou oxydés en vapeur à 1200 ou 1250 K, des transitions « breakaway » sont observées et les résultats de porosimétrie montrent que la porosité ouverte augmente au cours de la corrosion, proportionnellement au gain en masse. De plus, il a été mis en évidence que la distribution de tailles de pores des échantillons de ZIRLO® s’étend significativement pendant la corrosion, en particulier après « breakaway ». En effet, ces tailles vont de 60 μm à environ : 2 μm avant la transition, 50 nm juste après et 2 nm plus longtemps après. Enfin, un modèle numérique en deux étapes a été développé dans le code MAAP pour améliorer sa simulation de l’oxydation du gainage. D’abord, grâce à la proportionnalité entre porosité ouverte et gain en masse des échantillons, des corrélations de porosité ont été implémentées pour chaque condition de corrosion. Ensuite, les valeurs de porosité calculées sont utilisées pour augmenter proportionnellement la vitesse d’oxydation du gainage. Ce modèle amélioré simule ainsi non seulement les réactions chimiques des gaines en Zr (oxydation et nitruration) mais aussi leur dégradation mécanique et son impact sur leur vitesse d’oxydation. Ceci a été validé en simulant des essais QUENCH (-06, -08, -10 et -16), conduits au KIT pour étudier le comportement de gaines dans des conditions accidentelles avec un renoyage final. Ces simulations montrent un meilleur comportement thermique du gainage et une production d’hydrogène significativement plus haute et donc plus proche des valeurs expérimentales, en particulier pendant le renoyageIn nuclear power plants, a severe accident is a very unlikely sequence of events during which components of the reactor core get significantly damaged, through chemical interactions and/or melting, because of very high temperatures. This may potentially lead to radiotoxic releases in the containment building and to air ingress in the reactor core. In that context, this thesis work led at EDF R&D aimed at modeling the deterioration of the nuclear fuel cladding, made of zirconium alloys, in accidental conditions: high temperature and either pure steam or air-steam mixture. The final objective was to improve the simulation by the MAAP code of the cladding oxidation and of the hydrogen production, in particular during a core reflooding with water. Due to the progressive thickening of a dense and protective ZrO2 layer, the oxidation kinetics of Zr in steam at high temperatures is generally (sub-)parabolic. However, at certain temperatures, this oxide layer may crack, becoming porous and not protective anymore. By this “breakaway” process, the oxidation kinetics becomes rather linear. Additionally, the temperature increase can lead core materials to melt and to relocate down to the vessel lower head whose failure may induce air ingress into the reactor core. In this event, oxygen and nitrogen both react with the pre-oxidized claddings, successively through oxidation of Zr (thickening the ZrO2 layer), nitriding of Zr (forming ZrN particles) and oxidation of ZrN (creating oxide and releasing nitrogen). These self-sustained reactions enhance the cracking of the cladding and of its ZrO2 layer, inducing a rise of its open porosity.In order to quantify this cladding porosity, an innovative two-step experimental protocol was defined and applied: it consisted in submitting ZIRLO® cladding samples first to various accidental conditions during several time periods and then to measurements of the open porosity through porosimetry by mercury intrusion. The tested corrosion conditions included numerous temperatures ranging from 1100 up to 1500 K as well as both pure steam and a 50-50 mol% air-steam mixture. For the ZIRLO® samples oxidized in pure steam, except at 1200 and 1250 K, the “breakaway” kinetic transitions do not occur and the open porosity remains negligible along the oxidation process. However, for all other samples, corroded in air-steam or oxidized in pure steam at 1200 or 1250 K, “breakaway” transitions are observed and the porosimetry results show that the open porosity increases along the corrosion process, proportionally to the mass gain. Moreover, it was evidenced that the pore size distribution of ZIRLO® samples significantly extends during corrosion, especially after “breakaway” transitions. Indeed, the detected pore sizes ranged from 60 μm down to around: 2 μm before the transition, 50 nm just after and 2 nm longer after. Finally, a two-step numerical model was developed in the MAAP code to improve its simulation of the cladding oxidation. First, thanks to the proportionality between open porosity and mass gain of cladding samples, porosity correlations were implemented for each tested corrosion condition. Second, the calculated porosity values are used to proportionally enhance the cladding oxidation rate. This improved model thus simulates not only chemical reactions of Zr-based claddings (oxidation and nitriding) but also their mechanical degradation and its impact on their oxidation rate. It was validated by simulating QUENCH tests (-06, -08, -10 and -16), conducted at KIT to study the behavior of claddings in accidental conditions with a final reflooding. These simulations show a better cladding thermal behavior and a hydrogen production significantly higher and so closer to experimental values, in particular during the reflooding
Buchteile zum Thema "Porosité hydrogène"
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Fankhänel, Beate, Ekaterina Schmid und Michael Stelter. „Influence of Reactive Filter Materials on Casting’s Quality in Aluminum Casting“. In Multifunctional Ceramic Filter Systems for Metal Melt Filtration, 215–39. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-40930-1_9.
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AbstractThis chapter presents the most important results of investigations on reactive filter materials for the purification of aluminum melts. Reactive filter materials were developed with the aim to remove impurities dissolved in the melt, such as hydrogen from liquid aluminum, by means of specific chemical interactions between the molten metal and the filter material. Selected ceramic foam filters, consisting of carbon-free and carbon-bonded ceramics, were used in their uncoated state as well as treated with various coatings. Numerous fundamental studies were carried out to evaluate the applicability of the new filter materials: sessile-drop-experiments, immersion and filtration tests, the metallographic evaluation of the used filters and the metal samples retrieved from these experiments. Interfacial reactions and the purity of the treated melts were determined with the help of these experiments, following microstructural analyses to obtain indications for the filtration properties and the potential chemical reactions between the filter material and the melt. As a result, it was possible to determine that spodumene, LiAl(Si2O6), positively influences the hydrogen porosity of aluminum castings when applied as a reactive filter material. Filtration alone already helps to prevent areas of increased macroporosity by calming the melt flow, but filter materials containing spodumene further affect microporosity in the castings in positive ways.
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Yang, Mingyang, Song Yan, Aimin Du und Sichuan Xu. „The Cracks Effect Analysis on In-Plane Diffusivity in Proton Exchange Membrane Fuel Cell Catalyst Layer by Lattice Boltzmann Method“. In Proceedings of the 10th Hydrogen Technology Convention, Volume 1, 141–50. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8631-6_16.
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AbstractCrack is always considered as a kind of defect on a catalyst layer in a proton exchange membrane fuel cell (PEMFC), and its enhancement on mass transfer ability has always been ignored. In this work, the crack effect analysis on in-plane (IP) diffusivity on a catalyst layer is numerically evaluated by a D2Q9 lattice Boltzmann method (LBM). The effects on some key parameters like crack length, width, quantity and shape are carried out. The IP concentration distribution of crack CL shows deviation from the theoretical value, and this is because of the tortuosity caused by the CL cracks. The crack shape has almost no effect on the IP effective diffusivity, and the crack length shows a little bit more influence than the crack width and quantity. The crack ratio of the CL is the dominant effect on the IP mass diffusivity enhancement, and the lower the CL porosity is, the higher this enhancement achieve.
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Fan, Runlin, Junsheng Zheng und Zize Zhan. „Penetration Behavior Analysis of Resin During the Impregnation Progress of Expanded Graphite Plates“. In Proceedings of the 10th Hydrogen Technology Convention, Volume 1, 291–96. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8631-6_29.
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AbstractResin impregnation is an important process in the manufacture of composite graphite bipolar plates to reduce their porosity and improve their air tightness as well as flexural strength. In order to improve the filling efficiency of resin into expanded graphite plates and to investigate the factors influencing the resin penetration process, we compare the penetration rate and the upper limit of absorption of epoxy resin, acrylic resin and water in graphite plates. It was found that capillary force is part of the driving forces for resin penetration into the graphite plates, while the boundary layer is the main source of resistance. The higher viscosity of the resin not only leads to a lower resin flow rate, but also results in the formation of a thicker boundary layer, creating additional resistance. Further, the pores are not permeable by resin when the thickness of the boundary layer is greater than the pore size, which is an important reason why the expanded graphite plate is difficult to be filled by resin adequately.
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Gerrard, A. J., und W. D. Griffiths. „The Formation of Hydrogen Related Porosity by Double Oxide Film Defects in Al Alloys“. In Shape Casting: 5th International Symposium 2014, 269–76. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118888100.ch33.
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Gerrard, A. J., und W. D. Griffiths. „The Formation of Hydrogen Related Porosity by Double Oxide Film Defects in Al Alloys“. In Shape Casting: 5th International Symposium 2014, 269–76. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-48130-2_33.
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Liao, Hengcheng, Qigui Wang, Wan Song, Lei Zhao und Ran Fan. „Effect of Solidification Velocity and Hydrogen Content on Porosity in Directionally Solidified A356 Castings“. In Light Metals 2012, 345–48. Cham: Springer International Publishing, 2012. http://dx.doi.org/10.1007/978-3-319-48179-1_58.
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Liao, Hengcheng, Qigui Wang, Wan Song, Lei Zhao und Ran Fan. „Effect of Solidification Velocity and Hydrogen Content on Porosity in Directionally Solidified A356 Castings“. In Light Metals 2012, 345–48. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118359259.ch58.
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Shahrin, Muhammad Shahrul Nizam, Norazila Othman, Nik Ahmad Ridhwan Nik Mohd und Mastura A. B. Wahid. „Effect of Porosity and Permeability Characteristics on the Silver Catalyst of the Hydrogen Peroxide Monopropellant Thruster Performances“. In Technological Advancement in Mechanical and Automotive Engineering, 399–415. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1457-7_33.
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Anyalebechi, P. N. „Investigation of the Effects of Solidification Rate and Melt Hydrogen Concentration on Porosity Formation in Aluminum Alloy 2024“. In EPD Congress 2011, 659–77. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118495285.ch74.
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Satishkumar, P., Barun Haldar, Naveen Mani Tripathi, Ankit Sharma, Dhaval Jaydevkumar Desai, Vijay Kumar Sharma, S. Seenivasan und Atul Babbar. „Effect of Interlayer Temperatures and Heat Inputs on Porosity and Hydrogen Solubility in Wire Arc Additive Manufactured AA2618 Aluminium“. In Advances in Pre- and Post-Additive Manufacturing Processes, 137–62. Boca Raton: CRC Press, 2024. http://dx.doi.org/10.1201/9781003428862-8.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Porosité hydrogène"
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Medricky, J., M. Vilemova, T. Chraska, N. Curry und N. Markocsan. „Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former“. In ITSC 2014, herausgegeben von R. S. Lima, A. Agarwal, M. M. Hyland, Y. C. Lau, G. Mauer, A. McDonald und F. L. Toma. DVS Media GmbH, 2014. http://dx.doi.org/10.31399/asm.cp.itsc2014p0680.
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Abstract Dysprosia stabilized zirconia coatings with large globular pores have good potential as TBC topcoats. In previous work, such coatings have been produced by air plasma spraying with the aid of a polymer pore former. The aim of this work is to optimize the spraying parameters. A design of experiments approach was used to create a two-level full factorial test matrix based on spray distance, powder feed rate, and hydrogen flow. An agglomerated and sintered dysprosia stabilized zirconia (DySZ) powder mixed with polymer particles was sprayed on Hastelloy X substrates that had been prepared with NiCoCrAlY bond coats. The coatings obtained were evaluated based on thermal conductivity, thermocyclic fatigue life, and morphology, which are shown to correlate with spray parameters and in-flight particle properties.
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Akinyose, Olusegun, Tariq Alshaikhmubarak, Marie Van Steene und Laurent Mosse. „Quantifying the Effects of Heavy Minerals on Thermal Neutron Porosity in Permo-Carboniferous Sandstone“. In 2022 SPWLA 63rd Annual Symposium. Society of Petrophysicists and Well Log Analysts, 2022. http://dx.doi.org/10.30632/spwla-2022-0116.
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Recent studies document the presence of rare earth elements and heavy minerals in Permo-Carboniferous sandstones of the Arabian Peninsula. The studies establish that the measure of the gadolinium concentration and the formation capture cross-section (sigma) are both good proxies for the rare earth elements and heavy minerals. The objective of this study is to assess, quantify and then correct for the effect of these rare earth elements on the thermal neutron porosity measurement. Thermal and epithermal neutron porosity datasets were acquired in wells intersecting the Permo-Carboniferous sandstone. Relevant environmental corrections were applied to the data except for the formation water salinity correction. The hydrogen index values are obtained from the thermal neutron porosity measurement using corrections incorporating the measured sigma from the gamma ray spectroscopy tool and the formation bulk density. The measured sigma provides a measure of the water salinity in the flushed zone that is used to account for salinity effects on the thermal neutron porosity. The measured sigma also senses the effect of the heavy matrix minerals whose neutron capture cross-section is very high. The bulk density provides the required input to perform a density correction on the thermal neutron porosity. The hydrogen index that results from the measured sigma and formation density corrections to the thermal neutron porosity is referenced to the epithermal neutron porosity for these Permo-Carboniferous sandstones. When shale is present, the computed hydrogen index shows small discrepancies from the epithermal neutron porosity. These discrepancies are due to minor remaining density effects on the epithermal neutron porosity. In clay free reservoir intervals and in zones with moderate gadolinium content, the matrix-corrected hydrogen index is essentially identical to the matrix-corrected epithermal neutron porosity. The corrections from the thermal neutron porosity to the hydrogen index amount to 1.5-2.0 pu in the clay free sands. Applying this process to another well, additionally shows a good agreement between the matrix-corrected hydrogen index and the hydrogen index from the nuclear magnetic resonance. A third and final well application illustrates the extreme effect that the presence of rare earth elements can have on the conventional thermal neutron porosity, with negative corrections up to 5 pu to obtain the hydrogen index. Implementing a practical correction process to the thermal neutron porosity for the rare earth element bearing Permo-Carboniferous sandstones; this work quantifies the effects that rare earth elements have on the thermal neutron porosity measurements for the first time.
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Shenefelt, Jeffrey R., Rogelio Luck, John T. Berry und Robert P. Taylor. „Solidification Modeling and Porosity Control in Aluminum Alloy Castings“. In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0710.
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Abstract Commercial software packages enable the thermal environment of shaped castings to be determined provided the boundary conditions are well understood. Criteria functions (CF’s) based on the thermal environment provide a means for estimating shrinkage porosity within a casting. However, the CF’s do not account for gas driven porosity forming within the casting. This paper reviews the CF’s and additional approaches to account for hydrogen evolution in aluminum-copper and aluminum-silicon alloys.
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Leu, Jai-Houng, Yancheng Zhang, Ay Su und Tian-Syung Lan. „Numerical Simulation of Hydrogen Production Trends with Porosity of the Electrode of URSOFC“. In 2021 IEEE 3rd Eurasia Conference on Biomedical Engineering, Healthcare and Sustainability (ECBIOS). IEEE, 2021. http://dx.doi.org/10.1109/ecbios51820.2021.9510307.
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Socariceanu, M., und X. An. „Effect of Weld Porosity on Super Duplex Stainless Steel Umbilical Tubes Under Hydrogen Induced Stress Cracking Exposure Condition“. In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95986.
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Abstract Super Duplex Stainless Steel (SDSS) is the preferred material utilized in steel tube umbilicals, due to its excellent corrosion resistance and high mechanical strength. SDSS is susceptible to Hydrogen Induced Stress Cracking (HISC) under the influence of a Cathodic Protection (CP) system, especially the welded zone. Porosity (relevant rounded indication) is one of the most common weld flaws that impacts the SDSS weld reject rate based on historical acceptance criteria. A study has been carried out investigating the influence of weld porosity on 25% Cr (SDSS) butt welded tube, under the effect of CP potential by using a Slow Strain Rate Testing (SSRT) technique. The study focused on the correlation between the level of porosity and the material mechanical performance when exposed to a simulated CP system in seawater at an elevated temperature. The impact of HISC was evaluated through an assessment of various tube welds including welds with different levels of porosity quantified by number, size and location of pores, when exposed directly to natural CP system in seawater for 4 and 8 weeks. Post hydrogen pre-charging, the samples were subjected immediately to a modified Slow Strain Rate Test (SSRT). After hydrogen charging and SSRT the resulting fracture morphology was examined using a scanning electron microscope (SEM), and the failure mode was assessed in relation to porosity locations. Experimental results indicate that all hydrogen pre-charged samples with or without pores decrease in ductility after exposure to the CP system which was further confirmed by the fractography analysis. It was observed that susceptibility of SDSS to HISC is broadly similar for welds with porosity or without porosity and brittle phenomena is more pronounced at the exposed surfaces of the samples. The study has demonstrated that the butt weld of SDSS umbilical tube with a controlled porosity level in line with ASME design codes does not show an increased susceptibility to HISC under CP system when compared to welds with no porosity.
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He, Aiguo, Qingyuan Ma, Tianen Liu, Jingcui Li, Hong Zhang, Kun Dai und Yunhu Lu. „Study on Sealing Integrity Mechanism of Salt Cavern Hydrogen Storage Under Alternating Load“. In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0699.
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ABSTRACT The sealing integrity of salt cavern hydrogen storage is an important technology and safety index of hydrogen storage. In the process of injection and production, the surrounding rock of hydrogen storage chamber is in the state of alternating load stress, and there is the risk of fatigue failure and leakage. Analysis of dynamic rock mechanics characteristics of surrounding rock of salt cavern hydrogen storage chamber under alternating load is the key to study the sealing integrity mechanism of salt cavern hydrogen storage chamber. Uniaxial tests, triaxial tests, cyclic loading and unloading tests and creep tests were carried out on rock samples from salt layer, interlayer and cap layer of hydrogen storage reservoir of Jintanmao 17 well by means of rock mechanics experimental machine RTR-1500. The deformation and failure characteristics, permeability, porosity, breakthrough pressure and other parameters of rock samples under alternating loads were discussed. Based on the results of the creep test, the Burgers creep model parameters for this block were fitted. The results show that: (1) in the triaxial cyclic loading and unloading experiment, the cyclic loading and unloading before the yield point decreases the porosity and permeability of the rock sample, while the cyclic loading and unloading after the yield point increases the porosity and permeability of the rock sample.(2) In the process of cyclic loading and unloading, the dissipative energy of cap rock is greater than that of interlayer, and with the increase of cycle times, the dissipative energy first decreases and then becomes stable.(3)Burgers creep model can well reflect the creep law of salt formation in the target block, and can be used to study the long-term stability of hydrogen storage cavity. The research results provide a scientific basis for the design and operation of salt cavern hydrogen storage. INTRODUCTION Salt rock has been used in the construction of hydrogen storage because of its low porosity, low permeability and damage recovery. Sealing integrity is very important for a salt cavern hydrogen storage tank. Only by maintaining the sealing integrity of the salt cavern hydrogen storage tank can the salt cavern hydrogen storage tank run stably.
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da Silva, Weslley Carlos Dias, Leandro Fonseca Ribeiro, Alexandre Queiroz Bracarense und Ezequiel Caires Pereira Pessoa. „Effect of the Hydrostatic Pressure in the Diffusible Hydrogen at the Underwater Wet Welding“. In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83002.
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The underwater wet welding using SMAW is widely used in maintenance and repairs of submerged structures. In this process, water can dissociate, providing substantial quantities of ions H+ and O2− at the molten pool. Hydrogen and oxygen may constitute gas bubbles in the molten weld metal which may result in formation of pores. The hydrogen can diffuse by the weld metal and heat-affected zone or be trapped in the structure of the weld metal in the form of residual hydrogen. The diffusible hydrogen in the weld metal and heat-affected zone might have a deleterious effect in the mechanical properties of welded joint. The diffusible hydrogen plus susceptible microstructure, such as martensite, presence of tensile residual tension and temperatures lower than 200°C can lead the arising of cracks in the weld metal and heat-affected zone. All these conditions are satisfied in underwater wet welding. The amount of diffusible hydrogen in the weld metal can be influenced by several factors. However, it is not yet known whether the depth of welding (pressure) affects the amount of diffusible hydrogen in weld metal. In this work, several measurements of diffusible hydrogen were made at following depth: 0.30m, 10m, 20m and 30m at wet welding. The electrode used was commercial waterproofed E6013. The diffusible hydrogen measurements were made through the gas chromatography method following the AWS D3.6M procedure. The porosity was measured using the macrographic method and a software called Quantikov. The weld bead reinforcement and width were also measured. The residual hydrogen also was measured. The results showed that diffusible hydrogen reduced substantially as the hydrostatic pressure increased. The porosity, as it was related previously, increased as the hydrostatic pressure increased. Changes in the residual hydrogen of the weld metal were not observed. So, it was possible to conclude that the welding depth affects directly the diffusible hydrogen and porosity levels of underwater wet welds.
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Takeda, Tetsuaki, und Koichi Ichimiya. „Experimental Study on Application of Heat Transfer Enhancement Method Using Porous Material With High Porosity“. In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75060.
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A technology development of a hydrogen production system by nuclear heat is being performed as a heat application system of the Very High Temperature Reactor (VHTR) in worldwide. As for the development of the coupling technology between the VHTR and the hydrogen production system, Japan Atomic Energy Agency had carried out a coupling technology test using a steam reforming process by natural gas. In the hydrogen production system by nuclear heat, the catalyst tube of the steam reformer is heated by the high temperature helium gas from the intermediate heat exchanger (IHX). There are several methods for heat transfer enhancement. For example, there are attaching various fins on the heat transfer surface, processing the surface roughly, and so on. Disk type fins are attached on the outside surface of the catalyst tube. The catalyst tube is inserted into the guide tube to increase an amount of heat transferred from the high temperature helium gas. However, it has to take into consideration the deterioration of the structure strength by attaching the fins on the tube surface with the design of the steam reformer. The objective of this study is to clarify performances of a method for heat transfer enhancement using porous material with high porosity by an experiment. The experiment has been performed using an apparatus which simulated the passage structure of the steam reformer to obtain characteristics of heat transfer.
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Oifoghe, Stanley, Victor Okowi und Holger Thern. „Oil-Base Mud Filtrate and Hydrogen Index Effects on Magnetic Resonance Porosity in Gas Reservoirs“. In 2018 AAPG International Conference and Exhibition. Tulsa, OK, USA: American Association of Petroleum Geologists, 2018. http://dx.doi.org/10.1306/42332oifoghe2018.
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Santos, Valter R., Mauri´cio J. Monteiro, Fernando C. R. Assunc¸a¯o, Alexandre Q. Bracarense, Ezequiel C. P. Pessoa, Ricardo R. Marinho, Jose´ Roberto Domingues und Leonardo A. Vieira. „Evaluation and Development of Electrodes for Wet Welding of Structural Ship Steels“. In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20808.
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To better understand the behavior of some commercial wet welding electrodes down to 20 m equivalent water depth as well as to develop a new electrode, a research program was initiated in 2007. This depth is considered the maximum expected in the in situ repair of structural parts of floating production units. The weld metal evaluation was done by microstructural characterization, Vickers hardness, Charpy and tensile tests, chemical analysis, and diffusible hydrogen measurement. The influences of pressure on the mechanical properties of the weld metal are presented and discussed on the basis of chemical composition, microstructure and porosity. The electrode under development showed promising results concerning the possibility to broaden the range of qualified welding procedures. This expectation is based on the good results of diffusible hydrogen, porosity, impact toughness and ductility down to 20 m equivalent water depth. The susceptibility of hydrogen cracking in weld metal and in heat affected zone was estimated comparatively. The presence of hydrogen cracks is discussed as an important limiting factor for the qualification of welding procedures in the class A of the AWS D3.6M:1999 specification.
Berichte der Organisationen zum Thema "Porosité hydrogène"
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Ningthoujam, J., J. K. Clark, T. R. Carter und H. A. J. Russell. Investigating borehole-density, sonic, and neutron logs for mapping regional porosity variation in the Silurian Lockport Group and Salina Group A-1 Carbonate Unit, Ontario. Natural Resources Canada/CMSS/Information Management, 2024. http://dx.doi.org/10.4095/332336.
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The Oil, Gas and Salt Resources Library (OGSRL) is a repository for data from wells licenced under the Oil, Gas and Salt Resources Act for Ontario. It has approximately 50,000 porosity and permeability drill core analyses on bedrock cores. It also has in analogue format, geophysical logs (e.g., gamma ray, gamma-gamma density, neutron, sonic) from approximately 20,000 wells. A significant challenge for geotechnical and hydrogeological studies of the region is the accessibility of digital data on porosity and permeability. Recent work completed on approximately 12,000 core analyses for the Silurian Lockport Group and Salina Group A-1 Carbonate Unit are geographically concentrated within productive oil and gas pools. An opportunity therefore exists to expand the bedrock porosity characterization for southern Ontario by using geophysical logs collected in open-hole bedrock wells that are more geographically dispersed. As part of this study, hard copy files of analog geophysical logs are converted to digital data (LAS format), followed by quality assessment and quality control (QAQC) to obtain meaningful results. From the digitized geophysical data, density, neutron, and sonic logs are selected to mathematically derive porosity values that are then compared with the corresponding measured core porosity values for the same depth interval to determine the reliability of the respective log types. In this study, a strong positive correlation (R²=0.589) is observed between porosity computed from a density log (density log porosity) and the corresponding core porosity. Conversely, sonic log porosity and neutron porosity show weak (R2 = 0.1738) and very weak (R2 = 0.0574) positive correlation with the corresponding core porosity data. This finding can be attributed to different factors (e.g., the condition of the borehole walls and fluids, the type and limitations of the technology at different points in time, knowledge of formation variability for calculations), and as such requires more investigation. The density log measures the bulk density of the formation (solid and fluid phases), and as such the derived porosity values indicate total porosity i.e., interparticle (primary) pore spaces, and vugs and fractures (secondary) pore spaces. The sonic log measures the interval transit time of a compressional soundwave travelling through the formation. High quality first arrival waveforms usually correspond to a route in the borehole wall free of fractures and vugs, which ultimately result in the derived porosity reflecting only primary porosity. As molds, vugs and fractures contribute significantly to the total porosity of the Lockport Group and Salina A-1 Carbonate strata, sonic porosity may not reflect true bulk formation porosity. The neutron porosity log measures the hydrogen index in a formation as a proxy for porosity, however, the current limitations of neutron logging tool fail to account for formation-related complexities including: the gas effect, the chloride effect and the shale effect that can lead to over- or underestimation of formation porosity. As a result, the density log appears to be the most reliable geophysical log in the OGSRL archives for total porosity estimation in the Lockport Group and Salina A-1 Carbonate Unit. Nonetheless, sonic porosity can be combined with density porosity to determine secondary porosity, whereas a combination of density and neutron porosity logs can be used to identify gas-bearing zones.
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Fisher, John E., Yury Gogotsi und Taner Yildirim. Carbide-Derived Carbons with Tunable Porosity Optimized for Hydrogen Storage. Office of Scientific and Technical Information (OSTI), Januar 2010. http://dx.doi.org/10.2172/969920.
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Barraza, Alexyia. In-situ Radiography of Hydrogen Porosity Growth and Development in Aluminum Welds. Office of Scientific and Technical Information (OSTI), Mai 2021. http://dx.doi.org/10.2172/1782618.
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Feng, Pingyun. Low-Density and High Porosity Hydrogen Storage Materials Built from Ultra-Light Elements. Final Scientific/Technical Report. Office of Scientific and Technical Information (OSTI), Januar 2014. http://dx.doi.org/10.2172/1114147.
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L51823 Underwater Wet Welding of Pipeline Steels. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), Juli 2000. http://dx.doi.org/10.55274/r0010390.
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Underwater wet welding is presently accepted only for structural repairs to offshore facilities. The application of underwater wet welding to sub-sea pipelines and risers has been limited due to its perceived quality deficiencies compared to surface welds. These include the potential for excessive porosity, the risk of hydrogen cracking that results from the liberation of hydrogen in the welding arc and the accelerated weld cooling rates produced by the presence of the water. The present method for offshore tie-ins and repairs involves the use of either mechanical clamps, hyperbaric welding, or raising the pipeline to the surface. The underwater wet welding techniques currently used are not capable of producing welds that meet the workmanship based quality requirements of API 1104 for land pipelines, but may be suitable for sub-sea pipelines and risers based on a fitness-for-service basis. If it could be shown that underwater wet welding is capable of producing adequate quality welds, or if the deficiencies could be ercome by the use of for example, scalloped sleeves, a substantial cost savings could be realized.