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1
Balducci, Giulia. „Lightweight metal hydride-hydroxide systems for solid state hydrogen storage“. Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6534/.
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This thesis describes the preparation and characterisation of potential ‘modular’ solid state hydrogen storage solutions for on-board applications. The systems investigated throughout this work are based on reactions between light weight hydroxides and hydrides. In many senses light metal hydroxides can be seen as attractive candidates for hydrogen storage: they are low cost, present negligible toxicity and it is not possible to poison the fuel cell with decomposition products, unlike in nitrogen or boron containing systems. However, as the dehydrogenation products are the respective oxides, the major drawback of such systems lays in the fact the thermodynamics of rehydrogenation are not favourable for onboard applications. Hence, the system must be considered as a ‘charged module’, where the regeneration is performed ex-situ. Dehydrogenation can be achieved through reaction with light metal hydrides such as LiH or MgH2. A wide range of ‘modular’ release systems can be studied, however the most interesting in terms of theoretical gravimetric capacity, kinetics and thermodynamics within reasonable temperature range (RT - 350°C) use magnesium and lithium hydroxide and their hydrate forms. The present work focuses on the full investigation of three main systems: · Mg(OH)2 – MgH2 system · Mg(OH)2 – LiH system · LiOH(·H2O) – MgH2 system (both anhydrous and monohydrate LiOH were used) Mixtures of hydroxides and hydrides were prepared by manually grinding stoichiometric amounts of the starting materials. Further, nanostructuring the reactants was investigated as a means to control the dehydrogenation reaction and enhance the kinetics and thermodynamics of the process. Nanostructured Mg(OH)2 and LiOH(·H2O) have been successfully obtained using both novel and conventional synthetic routes. Reduction of the particle size of both hydrides was effectively achieved by mechanically milling the bulk materials. As detailed throughout Chapters 3, 4 and 5, promising results were obtained when employing nanosized reactants. The onset temperatures of hydrogen release were decreased and the overall systems performances enhanced. Particularly interesting results were obtained for the LiOH – MgH2 system, which exhibit a dramatic decrease of the onset temperature of H2 release of nearly 100 K when working with milled and nanostructured materials with respect to bulk reagents. All systems were characterised mainly by Powder X-ray diffraction (PXD) and simultaneous thermogravimetric analysis (TG-DTA) mass spectroscopy (MS). TG-DTA2 MS experiments were performed to obtain information on the onset and peak temperature of hydrogen release, weight loss percentage and nature and amount of the gases evolved during the reaction. Ex-situ PXD studies have been performed for each system in order to try and identify any intermediate species forming during the dehydrogenation process and ultimately propose a mechanism of H2 release. Since two fundamentally different types of reaction pathway could be proposed for the Mg(OH)2 – LiH system, powder neutron diffraction (PND) was employed for following the reaction in-situ. Developing a complete model of the dehydrogenation process in terms of mechanistic steps was found to be pivotal in order to understand and enhance such systems further.
2
Griffond, Arnaud Camille Maurice. „Concentrating Solar Thermal storage using metal hydride: Study of destabilised calcium hydrides“. Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/78467.
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This manuscript aims to study destabilised calcium hydrides system as thermal energy storage for concentration solar power. Using thermodynamic calculation and cost estimation, 3 different systems has been selected for in depth analysis of their thermal properties, the chemical reaction has been observed using in-situ synchrotron as well as their sorption properties. This laboratory scale analysis is used to select a promising material for on field application.
3
Poupin, Lucas Michel Dominique. „Development of metal hydride systems for thermal energy storage applications“. Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/84107.
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This thesis project furthers the development of innovative high temperature thermal energy storage using metal hydrides. The research greatly enhances the gravimetric energy density, which has the potential to lead to an increased efficiency of thermal energy storage. The project aimed at selecting suitable metal hydrides for scaling up and the investigation of heat storing reactors. Three systems were studied, including an autonomously operating thermal energy store of 1.8 MJ at 450 °C.
4
Webb, Timothy. „Structure-Function Relationships in Metal Hydrides: Origin of Pressure Hysteresis“. Thesis, Griffith University, 2017. http://hdl.handle.net/10072/366696.
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The hydrogen storage properties of a metal are highly dependent on its structure, including the crystal structures of the metal and the hydride, the defect structures of the metal and the relationship between hydrogen cycling and these properties. The aim of this project was to establish a greater understanding of the link between hysteresis and the structure of the metal, investigated by conducting in-situ diraction experiments on both palladium and LaNi5 and their hydrides.
Dislocations have a signicant impact on the pressure hysteresis in metal hydrides, but the exact link between them is poorly understood. A first experiment was performed aiming to increase the understanding of pressure hysteresis by investigating the annealing characteristics of dislocations in palladium hydride. Dislocations are created in the first traversal of the two-phase region in hydrogen cycled palladium but it is not clear what happens to the dislocations subsequent to the first cycle. An experiment was carried out to measure the density of dislocations while annealing in the phase, annealing under vacuum, and hydrogen cycling at increasing and decreasing temperatures. The dislocation density was measured using high resolution in-situ neutron diraction. It was found that annealing under vacuum and annealing in the phase produced the same result, but the dislocation density decreased much faster with temperature when the sample was hydrogen-cycled. Therefore the phase transformation signicantly aided in the removal of dislocations from the sample. It is suggested that the dislocations are gliding at the front of the advancing phase boundary, resulting in the removal of dislocations once the absorption/desorption is complete and the dislocations have reached the edge of a grain. This means that dislocations can be created and removed simultaneously during hydrogen cycling, resulting in a stable dislocation density. Dislocations gliding at the front of the phase boundary can also accommodate the strain of the transformation, explaining the reduced hysteresis on subsequent cycles compared to the first cycle.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
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5
Blinov, D. V., S. P. Malyshenko, V. I. Borzenko und D. O. Dunikov. „Experimental Investigations of Hydrogen Purification by Purging Through Metal Hydride“. Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35221.
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In an experimental stand [1] for investigation of properties of hydrogen accumulating the materials investigated
a new type of reactor cleaning and storage of hydrogen.
The applicability of hydrogen purging through metal hydride beds for the purification from nonpoisoning
admixtures is studied experimentally. The main characteristics of the process together with the
main technical barriers of the proposed technology are defined.
Specially designed stainless steel continuous flow reactor filled with LaFe0.1Mn0.3Ni4.8 intermetallic compound
is tested at variable inlet hydrogen/inert gas composition with measuring mass flow, pressure, temperature
and hydrogen content at the outlet both for charging and discharging mode. The estimations of hydrogen
losses and purification capacity show certain advantages of the studied technology in comparison with
PSA-like mode [1], especially from the point of view of operation regime simplification. The evident process
slow-down observed in the experiment is connected with saturation of metal hydride porous bed by hydrogen
and with temperature increase due to high thermal effect at sorption (~ 40 kJ/mole Н2). The ways for heat
and mass transfer optimization together with the range of applicability of the method for fine hydrogen purification
are described and discussed.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35221
6
Lutz, Michael [Verfasser], und André [Akademischer Betreuer] Thess. „Coupled metal hydride systems for energy storage / Michael Lutz ; Betreuer: André Thess“. Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2021. http://d-nb.info/1234452863/34.
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7
Sibanyoni, Johannes Mlandu. „Nanostructured light weight hydrogen storage materials“. University of the Western Cape, 2012. http://hdl.handle.net/11394/4631.
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Philosophiae Doctor - PhDThe main objective of this study was to advance kinetic performances of formation and decomposition of magnesium hydride by design strategies which include high energy ball milling in hydrogen (HRBM), in combination with the introduction of catalytic/dopant additives. In this regard, the transformation of Mg → MgH2 by high energy reactive ball milling in hydrogen atmosphere (HRBM) of Mg with various additives to yield nanostructured composite hydrogen storage materials was studied using in situ pressure-temperature monitoring that allowed to get time-resolved results about hydrogenation behaviour during HRBM. The as-prepared and re-hydrogenated nanocomposites were characterized using XRD, high-resolution SEM and TEM, as well as measurements of the mean particle size. Dehydrogenation performances of the nanocomposites were studied by DSC / TGA and TDS; and the re-hydrogenation behaviour was investigated using Sieverts volumetric technique.
8
Oksuz, Berke. „Production And Characterization Of Cani Compounds For Metal Hydride Batteries“. Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614676/index.pdf.
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Ni - MH batteries have superior properties which are long cycle life, low maintenance, high power, light weight, good thermal performance and configurable design. Hydrogen storage alloys play a dominant role in power service life of a Ni - MH battery and determining the electrochemical properties of the battery. LaNi5, belonging to the CaCu5 crystal structure type, satisfy many of the properties. The most important property of LaNi5 is fast hydrogen kinetics. Recently, CaNi5, belonging to same crystal type, has taken some attention due to its low cost, higher hydrogen storage capacity, good kinetic properties. However, the main restriction of its use is its very low cycle life.
The aim of the study is to obtain a more stable structure providing higher cycle life by the addition of different alloying elements. In this study, the effect of sixteen alloying elements (Mn, Sm, Sn, Al, Y, Cu, Si, Zn, Cr, Mg, Fe, Dy, V, Ti, Hf and Er) on cycle life was investigated. Sm, Y, Dy, Ti, Hf and Er were added for replacement of Ca and Mn, Sn, Al, Cu, Si, Zn, Cr, Mg, Fe and V were added for replacement of Ni. Alloys were produced by vacuum casting and heat treating followed by ball milling. The cells assembled, using the produced active materials as anode, which were cycled for charging and discharging. As a result, replacement of Ca with Hf, Ti, Dy and Er, and replacement of Ni with Si and Mn were observed to show better cycle durability rather than pure CaNi5.
9
Stienecker, Adam W. „An ultracapacitor - battery energy storage system for hybhrid electric vehicles /“. See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=toledo1121976890.
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Dissertation (Ph.D.)--University of Toledo, 2005.Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Bibliography: leaves 61-63.
10
Abdin, Zainul. „Components models for solar hydrogen hybrid energy systems based on metal hydride energy storage“. Thesis, Griffith University, 2017. http://hdl.handle.net/10072/370890.
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Modelling and simulation are essential tools for concept evaluation and for predicting
the performance of a hybrid energy system, since prototyping and testing each candidate
design for such a complex system would almost always be prohibitively cumbersome,
expensive and time consuming. To meet the modelling and simulation objectives, the various
components of the system (sources, storage, loads, and converters) need to be characterised
and modelled in a tractable way. The tuning of the models to reflect the actual system
components is a key milestone in this process and requires reliable and comprehensive
experimental data. Furthermore, environmental conditions such as ambient temperature may
have a significant impact on the performance, which has to be taken into account.
The complexity of hybrid energy systems and their dependence on embedded control
software increases the difficulty in predicting interactions among the various components and
subsystems. A modelling environment that can model not only the components but also
control algorithms (such as Matlab/Simulink, Homer etc.) is therefore advantageous.
Effective diagnosis of faults in an installed system also presents a challenge, because of the
interactions between the components and the control system. Modelling may play an
important role in diagnosis of the operating components. For example, running an electrolyser
model and comparing actual electrolyser operating variables with those obtained from the
model may help to diagnose a fault in the real electrolyser.
This thesis focuses on modelling the principal components of hybrid solar energy
systems that include energy storage in the form of hydrogen: a large photovoltaic array
subject to manufacturer’s variability and temperature inhomogeneity; two types of
electrolyser as commonly found in hydrogen energy systems; a metal-hydride hydrogen
storage tank; a fuel cell. Attention is given here to building physics-based component models with minimum empiricism and to critically analysing the state of the art in modelling such
components. The models have been realised in Simulink, so that they are mutually compatible
and can be linked into a whole of system model. All the models were validated against
experimental data and performed at least as well as models found in the literature. The thesis
is based on six papers, four already published and two submitted.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
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11
Kim, Ki Chul. „Thermodynamics of metal hydrides for hydrogen storage applications using first principles calculations“. Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34688.
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Metal hydrides are promising candidates for H2 storage, but high stability and poor kinetics are the important challenges which have to be solved for vehicular applications. Most of recent experimental reports for improving thermodynamics of metal hydrides have been focused on lowering reaction enthalpies of a metal hydride by mixing other compounds. However, finding out metal hydride mixtures satisfying favorable thermodynamics among a large number of possible metal hydride mixtures is inefficient and thus a systematic approach is required for an efficient and rigorous solution. Our approaches introduced in this thesis allow a systematic screening of promising metal hydrides or their mixtures from all possible metal hydrides and their mixtures. Our approaches basically suggest two directions for improving metal hydride thermodynamics. First, our calculations for examining the relation between the particle size of simple metal hydrides and thermodynamics of their decomposition reactions provide that the relation would depend on the total surface energy difference between a metal and its hydride form. It ultimately suggests that we will be able to screen metal hydride nanoparticles having favorable thermodynamics from all possible metal hydrides by examining the total surface differences. Second, more importantly, we suggest that our thermodynamic calculations combined with the grand canonical linear programming method and updated database efficiently and rigorously screen potential promising bulk metal hydrides and their mixtures from a large collection of possible combinations. The screened promising metal hydrides and their mixtures can release H2 via single step or multi step. Our additional free energy calculations for a few selected promising single step reactions and their metastable paths show that we can identify the most stable free energy paths for any selected reactant mixtures. In this thesis, we also demonstrate that a total free energy minimization method can predict the possible evolution of impurity other than H2 for several specified mixtures. However, it is not ready to predict reaction thermodynamics from a large number of compounds.
12
Danielsson, Mathias. „Spectroscopic study of titanium monohydride and storage ring experiments“. Doctoral thesis, Stockholm : Physics Department, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7451.
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13
Surrey, Alexander. „Preparation and Characterization of Nanoscopic Solid State Hydrogen Storage Materials“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-217904.
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Die Speicherung von Wasserstoff in Form von Hydriden im festen Aggregatzustand hat den Vorteil einer hohen volumetrischen und gravimetrischen Wasserstoffspeicherdichte, die sowohl für die stationäre als auch die mobile Anwendung nötig ist. Um die Anforderungen dieser Anwendungen erfüllen zu können, müssen die Speichereigenschaften dieser Materialien weiter verbessert werden. Als zentrales Konzept dieser Dissertation wird die Nanostrukturierung verfolgt, die eine vielversprechende Strategie zur Modifizierung der thermodynamischen und kinetischen Eigenschaften von Hydriden darstellt. Die Transmissionselektronenmikroskopie (TEM) stellt dabei eine unverzichtbare Untersuchungsmethode solch nanoskopischer Materialien dar. Als problematisch erweist sich dabei die durch Radiolyse hervorgerufene Zersetzung der meisten Hydride bei der Beleuchtung mit dem abbildenden Elektronenstrahl. Im ersten Teil dieser Arbeit wird eine Methodik entwickelt um dieses Phänomen quantitativ mit Hilfe von Valenzelektronenenergieverlustspektroskopie zu untersuchen. Hierzu kommt kugelgemahlenes MgH2 als Modellsystem zum Einsatz. Die Dehydrierung kann quantitativ durch die inelastische Streuung der hochenergetischen Elektronen am MgH2-Plasmon erklärt werden. Eine Lösung dieses grundlegenden Problems wird theoretisch an Hand von Multislice TEM-Kontrastsimulationen untersucht. Hierbei wird ein TEM Experiment unter Wasserstoff bei Umgebungsdruck anstatt unter Vakuum simuliert, was mit Hilfe eines speziellen TEM Halters, in dem das Gas durch elektronentransparente Fenster eingeschlossen ist, realisiert werden kann. Im zweiten Teil wird der Einfluss des Nanoconfinements (Nanoeinschließung), einer speziellen Form der Nanostrukturierung, des komplexen Hydrids LiBH4 auf dessen Wasserstoffspeichereigenschaften untersucht, wofür eine neuartige nanoporöse aerogel-ähnliche Kohlenstoff-Gerüststruktur zum Einsatz kommt. Diese wird durch Salt Templating synthetisiert - einer simplen und nachhaltigen Methode zur Herstellung nanoporöser kohlenstoffbasierter Materialien mit großen Porenvolumina. Es wird gezeigt, dass durch das Nanoconfinement die Wasserstoffdesorptionstemperatur, die für makroskopisches LiBH4 bei über 400 °C liegt, auf 310 °C sinkt und die Desorption bereits bei 200 °C einsetzt. Eine teilweise Rehydrierung ist unter moderaten Bedingungen (100 bar und 300 °C) möglich, wobei die Reversibilität durch eine partielle Oxidation des amorphen Bor gehemmt ist. Im Gegensatz zu Beobachtungen einer aktuellen Veröffentlichung von in hoch geordnetem, nanoporösen Kohlenstoff eingebetteten LiBH4 deuten die in-situ TEM-Heizexperimente der vorliegenden Arbeit darauf hin, dass beide Reaktionsprodukte (B und LiH) in den Poren des aerogel-ähnlichen Kohlenstoffs verbleibenStoring hydrogen in solid hydrides has the advantage of high volumetric and gravimetric hydrogen densities, which are needed for both stationary and mobile applications. However, the hydrogen storage properties of these materials must be further improved in order to meet the requirements of these applications. Nanostructuring, which represents one of the central approaches of this thesis, is a promising strategy to tailor the thermodynamic and kinetic properties of hydrides. Transmission electron microscopy (TEM) is an indispensable tool for the structural characterization of such nanosized materials, however, most hydrides degrade fast upon irradiation with the imaging electron beam due to radiolysis. In the first part of this work, a methodology is developed to quantitatively investigate this phenomenon using valence electron energy loss spectroscopy on ball milled MgH2 as a model system. The dehydrogenation can be quantitatively explained by the inelastic scattering of the incident high energy electrons by the MgH2 plasmon. A solution to this fundamental problem is theoretically studied by virtue of multislice TEM contrast simulations of a windowed environmental TEM experiment, which allows for performing the TEM analysis in hydrogen at ambient pressure rather than vacuum. In the second part, the effect of the nanoconfinement of the complex hydride LiBH4 on its hydrogen storage properties is investigated. For this, a novel nanoporous aerogel-like carbon scaffold is used, which is synthesized by salt templating - a facile and sustainable technique for the production of nanoporous carbon-based materials with large pore volumes. It is shown that the hydrogen desorption temperature, which is above 400 °C for bulk LiBH4, is reduced to 310 °C upon this nanoconfinement with an onset temperature as low as 200 °C. Partial rehydrogenation can be achieved under moderate conditions (100 bar and 300 °C), whereby the reversibility is hindered by the partial oxidation of amorphous boron. In contrast to recent reports on LiBH4 nanoconfined in highly ordered nanoporous carbon, in-situ heating in the TEM indicates that both decomposition products (B and LiH) remain within the pores of the aerogel-like carbon
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Book, Stefan. „Temperature and concentration dependence of hydrogen diffusion in vanadium measured by optical transmission“. Thesis, Uppsala universitet, Materialfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-239306.
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Hydrogen diffusion is investigated in a 50 nm film of vanadium and a vanadium superlattice. Diffusion constants for three different temperature and pressure pairs are determined for the 50 nm film. The diffusion constants for the temperature and pressure pairs are determined to be 4.5 $\pm$ 0.1 $\cdot 10^{-5} \text{ cm}^{-2}$ at 463 K and 0.05 H/V, 5.6 $\pm$ 0.1 $\cdot 10^{-5} \text{ cm}^{-2}$ at 463 K and 0.12 H/V and 8.0 $\pm$ 0.2 $\cdot 10^{-5} \text{ cm}^{-2}$ at 493 K and 0.05 H/V. The temperature and concentration dependence of the diffusion constants are determined. A concentration dependence of the diffusion constant is found with a higher rate of diffusion for a higher hydrogen concentration. The activation energy of chemical diffusion is determined to be 0.38 $\pm$ 0.03 eV.
15
Santoru, Antonio [Verfasser]. „Insights into the structure and reaction mechanism of alkali and alkaline-earth metal amide-metal hydride composite systems for hydrogen storage / Antonio Santoru“. Hamburg : Helmut-Schmidt-Universität, Bibliothek, 2018. http://d-nb.info/1162510706/34.
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16
Berti, Nicola. „MgH2-TiH2 hydrides as negative electrodesof Li-ion batteries“. Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1029/document.
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Les batteries lithium-ion sont aujourd’hui très utilisées pour alimenter l’électronique portable telle que les ordinateurs, les smartphones et les caméras. Cependant, de nouvelles applications telles que les véhicules électriques et les systèmes stationnaires de stockage d'énergie nécessitent des batteries à performances améliorées. En particulier, de nouveaux matériaux d'électrode avec des densités d'énergie plus élevées sont requis. Les hydrures de MgH2 et TiH2 et leurs mélanges possèdent de très fortes capacités électrochimiques (>1 Ah/g). Ils ont été étudiés comme matériaux d’électrode négative dans les batteries Li-ion. La réaction de conversion de ces hydrures avec du lithium et les changements structuraux induits ont été étudiés en détails pour mieux comprendre les mécanismes réactionnels et leur réversibilité. Les propriétés électrochimiques de couches minces de MgH2 et des poudres composites de MgH2+TiH2 ont été étudiées en utilisant à la fois des électrolytes organiques liquides et un électrolyte solide LiBH4. La capacité réversible et la tenue au cyclage dépendent fortement du rapport molaire entre les deux hydrures et des conditions de cyclage. Le transport de masse et la densité d’interfaces à l'intérieur de l'électrode sont identifiés comme les principaux facteurs affectant la réversibilité de la réaction de conversionToday, lithium-ion batteries are widely used as power supplies in portable electronics such as laptops, smartphones and cameras. However, new applications such as full electric vehicles and energy storage stationary systems require enhanced battery performances. In particular, novel electrode materials with higher energy density are needed.MgH2 and TiH2 hydrides and mixtures of them have high electrochemical capacity (> 1 Ah/g). They have been studied as negative electrode materials in Li-ion batteries. The conversion reaction of lithium with these hydrides and the related microstructural changes have been deeply investigated to gain a better understanding of reaction mechanisms and their reversibility. The electrochemical properties of MgH2 thin films and MgH2+TiH2 composite powders have been evaluated using both liquid organic and solid (LiBH4) electrolytes. Reversible capacity and cycle-life are found to strongly depend on both molar ratio between the hydrides and cycling conditions. Mass transport and density of interfaces within the electrode are identified as the main factors affecting the reversibility of the conversion reaction
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Stienecker, Adam W. „An Ultracapacitor - Battery Energy Storage System for Hybrid Electric Vehicles“. University of Toledo / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1121976890.
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18
Reissner, Alexander. „Metal Hydrides as Enabling Technology for the use of Hydrogen-Based Energy Storage Systems on Telecommunication Satellites“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-229226.
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Next generation telecommunication satellites will demand an increasing amount of power in the range of 30 kW or more within the next 10 years. Battery technology that can sustain 30 kW for an eclipse length of up to 72 minutes will represent a major impact on the total mass of the satellite, even with new Li-ion battery technologies. Regenerative fuel cell systems (RFCS) were identified years ago as a possible alternative to rechargeable batteries. Nevertheless, one major drawback was identified by several independent system studies, namely the need to dissipate large amounts of heat from the fuel cell (FC) during eclipse. This in turn requires massive thermal hardware (mainly large radiators) that can contribute up to 50% of the system mass. In order to overcome this issue, the use of metal hydrides (MH) as combined hydrogen and heat storage system was suggested as a starting point of the research presented in this thesis. During eclipse the FC must dissipate waste heat, and at the same time the MH tank must absorb heat in order to desorb hydrogen. Rather than dissipating the waste heat from the FC directly through a radiator, it can be stored solely, or partly, in the MH tank, to be dissipated during Equinox, with a 20 times slower rate, requiring a radiator with significantly less volume and mass. This thesis aims to present the potential of using such MH storage tanks to alternately store hydrogen and waste heat from the FC on-board a spacecraft, investigated by theoretical and experimental means. The model application for the MH tank technology considered in this thesis is a 39 kW telecommunication satellite. Nevertheless, the derived results are to be considered a generic outcome and can be translated or scaled to many other applicationsEs kann davon ausgegangen werden, dass der Trend hin zu Telekommunikationssatelliten mit immer höherer Leistung in den nächsten 10 Jahren zu Satelliten-Plattformen mit 30kW und mehr führen wird. Batterien, welche eine Leistung von 30kW für Eklipse-Längen von 72 Minuten zur Verfügung stellen müssen, werden daher einen immer größeren Einfluss auf die Gesamtmasse des Satelliten haben. Regenerative Brennstoffzellensysteme wurden daher schon vor Jahren als mögliche Alternative zu wieder aufladbaren Batterien untersucht. Mehrere unabhängige Studien sind zu dem Schluss gekommen, dass die größte Problematik in der Einführung von Brennstoffzellensystemen auf Satelliten darin besteht, die relativ großen Mengen an Abwärme effizient abzustrahlen. Die Radiatoren, die hierfür benötigt werden können 50% der Masse des Gesamtsystems ausmachen. Um dieses Problem zu überwinden wurde als Startpunkt der vorliegenden Arbeit die Nutzung von Metallhydriden als kombinierter Wasserstoff- und Wärmespeicher vorgeschlagen. Während sich der Satellit im Erdschatten befindet produziert die Brennstoffzelle Abwärme, während zur gleichen Zeit der Metallhydrid-Tank Wärme benötigt um Wasserstoff freizusetzen. Die Abwärme der Brennstoffzelle muss daher nicht direkt über Radiatoren abgestrahlt werden, sondern wird von Metallhydrid-Tank absorbiert um dann während dem restlichen Erdumlauf 20 mal langsamer mit einem deutlich kleinerem und leichteren Radiator abgegeben werden zu können. Diese Arbeit hat zum Ziel, das durch analytische und experimentelle Methoden untersuchte Potential der Anwendung einer solchen Technologie auf Satelliten zu präsentieren. Die Modellapplikation für diese Arbeit ist ein 39kW Telekommunikationssatellit. Die Ergebnisse lassen sich allerdings auch auf andere Anwendungen skalieren und übertragen
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Ntsendwana, Bulelwa. „Advanced low temperature metal hydride materials for low temperature proton exchange membrane fuel cell application“. Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8494_1307431585.
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Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy.
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Klose, Markus, Inge Lindemann, Minella Christian Bonatto, Katja Pinkert, Martin Zier, Lars Giebeler, Pau Nolis et al. „Unusual oxidation behavior of light metal hydride by tetrahydrofuran solvent molecules confined in ordered mesoporous carbon“. Cambridge University Press, 2014. https://tud.qucosa.de/id/qucosa%3A39011.
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Confining light metal hydrides in micro- or mesoporous scaffolds is considered to be a promising way to overcome the existing challenges for these materials, e.g. their application in hydrogen storage. Different techniques exist which allow us to homogeneously fill pores of a host matrix with the respective hydride, thus yielding well defined composite materials. For this report, the ordered mesoporous carbon CMK-3 was taken as a support for LiAlH₄ realized by a solution impregnation method to improve the hydrogen desorption behavior of LiAlH₄ by nanoconfinement effects. It is shown that upon heating, LiAlH₄ is unusually oxidized by coordinated tetrahydrofuran solvent molecules. The important result of the herein described work is the finding of a final composite containing nanoscale aluminum oxide inside the pores of the CMK-3 carbon host instead of a metal or alloy. This newly observed unusual oxidation behavior has major implications when applying these compounds for the targeted synthesis of homogeneous metal–carbon composite materials.
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Capurso, Giovanni. „Innovative Materials and Systems for Solid State Hydrogen Storage“. Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3422645.
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The research presented in this doctoral thesis concerns with the development of novel
materials and systems for solid state hydrogen storage.
The first group of works presented is on alkaline and alkaline-earth borohydrides. The
possibility to enhance their properties with the help of nanosupports has been widely
explored. An attempt to improve the dehydrogenation kinetics of lithium borohydride has
been made dispersing this material on the surface of modified nanotubes and graphite.
The resulting nanoconfined material displayed a decreased decomposition temperature in
comparison with pure material and further decreasing was observed when the surface area
of the supports was increased. An analogous experiment was performed to investigate this
effect in combination with the assets of a reactive hydride composite, where two materials
are mixed to obtain a compound with a lower decomposition enthalpy. The effect of the
mixture was beneficial in presence of the support, due to lower temperature melting. For
calcium borohydride an ordered mesoporous carbon was used after chemical activation.
The increased properties of this support resulted in lower decomposition temperature and
improved reversibility for a number of cycles at different pressure values.
The second research line is focused on magnesium hydride. To improve its kinetic properties
a zirconium-nickel alloy was investigated to evaluate its influence on the reaction
rate, both in absorption and desorption. The degradation observed in experimental reactors,
of different magnesium hydride powders catalyzed with a transition metal oxide,
motivated the fabrication of pellets with the addition of a binding agent, to obtain mechanical
resistance, still allowing hydrogen diffusion. Each pellet was supposed to behave
as an independent system, so they were also tested in a small reactor. Several hydrogen
absorption/desorption cycles were performed to compare the behaviour of the small reactor
with the laboratory data obtained on smaller quantity of powdered and pelletized
specimens.
Finally, the feasibility of a vehicular hydrogen tank system was investigated using an
interstitial metal hydride as storage material. Apart from material basic characterization,
two different kinds of experiment were performed. Static tests (measurements with automatic
flow control and constant settings) were used to evaluate wether the requirements
for desorption are met by the tank set-up. Then, dynamic tests were designed and applied
on the tank, where the hydrogen flow was fluctuating following a hypothetical on-road
trial. It was possible to underline the heat management issues of high-demanding performances
and to analyze some solutions for that. Different cycles were carried out on the
tank to find the ideal setting for high average and peak flows in a realistic experiment.L’attività di ricerca presentata in questa tesi di dottorato riguarda lo sviluppo di nuovi materiali e sistemi per lo stoccaggio di idrogeno allo stato solido. Il primo gruppo di attività presentate è sui boroidruri di metalli alcalini e alcalinoterrosi. È stata ampiamente esplorata la possibilità di migliorare le loro proprietà con l’ausilio di nanosupporti. Un tentativo di migliorare la cinetica di decomposizione del litio boroidruro è stato fatto disperdendo tale materiale sulla superficie di nanotubi di carbonio e grafite modificati.Il materiale nanoconfinato risultante ha mostrato una temperatura di decomposizione inferiore, se paragonato al materiale puro e un’ulteriore diminuzione è stata osservata aumentando l’area superficiale del supporto. Un esperimento analogo è stato eseguito per osservare questo effetto in combinazione con i vantaggi di un reactive hydride composite, nel quale due materiali sono combinati per ottenere un composto con una minor entalpia di decomposizione. L’effetto del composto è stato positivo in presenza del supporto, grazie alla minor temperatura di fusione. Per il calcio boroidruro è stato usato carbone mesoporoso dopo attivazione chimica. Le migliorate proprietà di questo supporto hanno dato una minor temperatura di decomposizione e una migliorata reversibilità per vari cicli a diverse pressioni. La seconda linea di ricerca si focalizza sull’idruro di magnesio. Per migliorare le sue proprietà cinetiche, è stata testata una lega zirconio-nickel, al fine di valutare la sua influenza sulla velocità di reazione in assorbimento e desorbimento. Il degrado di altre polveri di magnesio idruro catalizzate con un ossido metallico in reattori sperimentali ha motivato la produzione di pastiglie con l’aggiunta di un agente legante, per ottenere resistenza meccanica, consentendo comunque la diffusione dell’idrogeno. Era previsto che ogni pastiglia si comportasse come un sistema indipendente, infatti, sono state testate in un piccolo reattore. Diversi cicli di assorbimento e desorbimento sono stati effettuati per paragonare la risposta del reattore con dati di laboratorio ottenuti su minori quantità di polvere o pastiglie. Infine, è stata sperimentata la realizzabilità di un serbatoio di idrogeno veicolare usando un idruro di un metallo interstiziale. Oltre alla caratterizzazione di base del materiale, sono stati realizzati due tipi di esperimenti. Test statici (misure con controllo automatico di flusso e impostazioni costanti) sono stati usati per valutare se il serbatoio soddisfacesse i requisiti di rilascio di idrogeno. Test dinamici sono stati progettati e applicati al serbatoio, dove il flusso di idrogeno era variabile seguendo un’ipotetica prova su strada. È stato possibile evidenziare i problemi legati allo scambio di calore per le prestazioni di maggior consumo e analizzare alcune possibili soluzioni. Cicli diversi sono stati effettuati sul serbatoio in esperimenti realistici, per trovare le impostazioni ideali per alti valori di flusso medio e di picco.
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Razafindramanana, Volatiana. „Amélioration et compréhension du mécanisme d'activation de l'alliage FeTi dopé avec de l'hafnium, pour le stockage de l'hydrogène“. Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0907/document.
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La problématique de la première absorption (i.e. étape d’activation) de l’intermétallique FeTi, pour le stockage de l’hydrogène est souvent un frein pour son industrialisation. Le challenge réside dans la conception d’un « nouveau matériau » dont la première étape d’hydrogénation, s’effectue dans les mêmes conditions de température et de pression modérées, que lors de l’hydrogénation réversible. Une solution est de faire appel aux performances d’un élément dopant et/ou à la technique du broyage mécanique. Dans ce manuscrit, nous proposons l’utilisation de l’hafnium comme dopant. Ce projet complète les études qui ont été effectuées sur le zirconium (e.g. le zirconium commercial contient toujours une certaine quantité d’hafnium). L’ajout d’une faible quantité d’hafnium induit la formation d’une phase secondaire, « riche » en hafnium et en fer. Grâce à la présence de cette phase, la cinétique de première absorption est considérablement améliorée, et ce, sans traitement thermique préalable. L’étape d’activation comprend un seul mécanisme lorsque la taille des particules est faible. A contrario, un second mécanisme est mis en évidence, pour des particules de taille supérieure à 0,5 mm. La mécanosynthèse a permis non seulement d’obtenir la phase principale FeTi, mais aussi de favoriser la première absorption d’hydrogène. Des paramètres d’élaboration méticuleusement optimisés ont rendu possible la conception d’un matériau « modèle », par pulvérisation cathodique magnétron, sous forme de couche mince. Ce matériau modèle pourrait servir à étudier et à comprendre la diffusion de l’hydrogène à l’interface de la matrice FeTi et du dopant Zr ou HfThe issue of the first hydrogenation (i.e. activation process) of the intermetallic FeTi for the storage of hydrogen is often a brake for its use in industry. The challenge lies in the design of a "new material" whose first hydrogenation is carried out under the same conditions of moderate temperature and pressure, as during reversible absorption. Efficient solutions are to use a doping element and/or mechanical alloying process. In this work, we propose to use hafnium as a dopant. This project completes the studies that have been carried out on zirconium (e.g. commercial zirconium always contains a certain amount of hafnium). The addition of a small amount of hafnium induces the formation of a secondary phase, "rich" in hafnium and iron. Thanks to the presence of this phase, the kinetics of activation process is improved, without prior heat treatment. The activation process consists of a single step, when the particle size is small. However, a second step appears, for particles bigger than 0.5 mm. The mechanical alloying allowed the formation of the main phase FeTi, and also enhanced the activation process. An accurate control of deposition conditions allow us to design a ″model″ material by magnetron sputtering as thin layers. This ″model″ material can be used to study and understand the hydrogen diffusion, at the interface of the matrix (FeTi) and the dopant (Zr or Hf)
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Escobar, Diego. „Investigation of ZrNi, ZrMn2 and Zn(BH4)2 Metal/Complex Hydrides for Hydrogen Storage“. Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/701.
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The demand for efficient and clean fuel alternatives has been increasing in recent years and is expected to become more pronounced in the future. Utilization of hydrogen as a fuel is one of the most promising energy resources due to its easy production, abundance, regeneration and not creation of greenhouse gases during its combustion. Although gaseous hydrogen has a very high energy content per unit weight, its volumetric energy density is rather low. The large scale use of hydrogen as a fuel crucially depends on the development of compact hydrogen storage materials with a high mass content of hydrogen relative to total mass and to volume.
Certain metals and alloys are capable of reversibly absorbing large amounts of hydrogen to form metal hydrides. They exhibit the highest volumetric densities of hydrogen and are very promising for hydrogen storage because of their efficiency, cost and safety. Some of the metal hydride families can also be used in hydrogen compressors.
The objective of this work is to investigate the synthesis and characterization behavior of intermetallic alloys (ZrMn2, ZrNi) for hydrogen compression and of complex hydrides (Zn(BH4)2 ) for on-board hydrogen storage. An overview of hydrogen as a fuel and its storage means is provided, synthesis and characterization methods of metal hydrides are presented and the effect of mechanical milling and the catalytic doping of metal/complex hydrides are investigated in detail. The hydrogen storage alloys (hydrides) are extensively characterized using various analytical tools such as: XRD, SEM, EDS, TCD, FTIR and GC/MS. The thermal (heat flow and weight loss) and volumetric (storage capacity, kinetics, cycle life, etc) analysis have been carried out via DSC/TGA and high pressure PCT apparatus. Finally conclusions and recommendations for future work are provided to improve the absorption/desorption cycle of hydrogen storage in the compounds under investigation.
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Salque, Bruno. „Caractérisation mécanique de la respiration des hydrures pour uneconception optimisée des réservoirs de stockage de l’hydrogène par voie solide“. Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI026/document.
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L’hydrogène est une solution chimique de stockage d’énergie électrique intéressante. En effet, l’hydrogèneproduit devient un vecteur d’énergie utilisable de différentes façons. Pour développer l’industrie hydrogène,sa production, son stockage et sa consommation doivent être étudiés et optimisés.Cette thèse traite du stockage solide d’hydrogène dans des hydrures métalliques. Dans cette technologie,l’hydrogène est piégé à l’intérieur d’un matériau métallique selon une réaction chimique réversibleexothermique. L’hydrogène peut être libéré selon la réaction inverse, endothermique. Les performances dece stockage sont liées au choix du matériau, à la gestion des transferts thermiques et au système utilisé. Sesgrands avantages sont sa compacité énergétique et la sécurité d’un tel stockage. L’inconvénient majeur vientdu poids du système. Lors de l’absorption de l’hydrogène dans le matériau, ce dernier augmente de volume.Pour pouvoir dimensionner les réservoirs à hydrures métalliques, il est nécessaire de connaître les contraintesgénérées pas ce gonflement. Le confinement du matériau dans une enceinte étanche doit être garanti. Lecyclage entre les étapes de gonflement dégonflement dûs aux stockage/dé-stockage de l’hydrogène dans unhydrure métallique est appelé la respiration de l’hydrure.Ce travail de recherche commence par rappeler l’état de l’art sur l’hydrogène et les hydrures métalliques.Dans le second chapitre, le matériau sélectionné, LmNiCoMnAl , est caractérisé. Les deux chapitres suivantsprésentent l’étude expérimentale de la respiration en conditions oedométriques à contrainte imposée et dansun volume fixe. Le chapitre cinq présente les travaux de simulation numérique par éléments discrets. Lesgrains, modélisés sous forme de clusters, sont placés dans différentes conditions aux limites avec différentscoefficients de frottement.Les résultats des expériences complètent les travaux précédents sur d’autres matériaux. Contrairementau Ti-Cr-V, le LaNiCoMnAl voit sa densité diminuer au cours de la respiration pour les contraintes deconfinement utilisées. Le taux de décroissance de la densité diminue quand la contrainte de confinementaugmente. Quand l’échantillon est placé dans un volume fixe, les contraintes développées par le matériauaugmentent avec la quantité de matériau introduite dans le volume. La simulation numérique a permis demontrer qu’une dédensification est observée pour des niveaux de contrainte intermédiaires quand le coefficientde frottement augmente, confirmant l’hypothèse que les paramètres matériaux ont une importance dans lecomportement macroscopique des hydrures métalliques pendant la respirationHydrogen can be used as a storage for electric energy. Hydrogen may become an energy vector, whichcould be used and transported easily. For the hydrogen sector to develop and mature, production, storageand consumption should be researched and optimized.This PhD is dedicated to hydrogen solid storage in metal hydride. This technology consists in usinga reversible and exothermic chemical reaction between an alloy and hydrogen. The hydrogen is capturedinside the metal lattice and can be released with the endothermic opposite reaction. The main factors whichimpact the performance of this technology are the choice of material, the heat flow management and thesystem used. Its main advantages lay on safety and energy compactness. Its main drawbacks come from theweight of the system. When the material absorb hydrogen, its volume increases. To contain this materialin an airtight environment, it is mandatory to know how stress develop on the container that contains thematerial. The cycles of dilatation and contraction of the material, when it is loading or unloading hydrogen,is called breathing.This research begins with a large spectrum presentation of hydrogen. Then comes a chemical and structuralcharacterization of the material : LaNiCoMnAl. Its Composition-Temperature-Pressure characteristicsare given. The material exhibits granular properties and is structurally characterize using laser grain sizing,shape measurement and X-Ray tomography. The typical length scale of LaNiCoMnAl particles is 20 micrometers.The third and fourth chapters are concerned with the experimental behavior. A sample is placed ina stress controlled environment where its density is measured during cycling. The other experiment places asample in a fixed volume. In that case, the stress exerted on the material is recorded and measured duringcycling. In the last chapter, numerical simulations using the Discrete Element Method are used. The materialis modeled by X shaped clusters and studied with different friction parameters and boundary conditions.Following other works done on other materials, these experiment showed a different behavior of LaNi-CoMnAl compared to Ti-Cr-V. During breathing, LaNiCoMnAl exhibits a decrease in density even whensubmitted to a relatively large stress. The rate at which the density decreases is lowered when the confinementpressure increases. When the material is placed in a fixed volume, the stress increases with increasingpoured mass. Numerical simulations show a decrease in density when the friction parameter is high enough.It validates the hypothesis that material parameters play a major role in the macroscopic behavior of metalhydride during breathing
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Richard, Laura Amanda. „A study of the crystallographic, magnetic and electronic properties of selected ZrM2-H systems“. Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:276c59fe-cf45-42d2-a5a0-8c534c8b46bd.
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Dissolution of hydrogen into intermetallic compounds characteristically occurs at interstitial sites, causing little alteration to the base metal substructure but often bringing about substantial electronic and magnetic changes to the material. These hydrogen-induced alterations in the intermetallic hydrides are of interest both on a fundamental research level and in terms of technological applications; however, there exists no general theory as to how and why these alterations arise. The objective of this research is to elucidate to general effect of hydrogen on intermetallic compounds through the study of crystallographic, magnetic and electronic properties. An investigation has been carried out on the properties of three intermetallic compound - hydrogen systems of general formula ZrM₂, where M = V, Cr, Mn. All three compounds reversibly absorbed hydrogen with no change in crystal symmetry: powder diffraction studies showed that hydrogen was accommodated in interstitial sites of the existing metal sublattice via lattice expansion. The measurement of the magnetic properties of these systems was combined with the determination of conductivity and dielectric properties in order to describe the electronic e¤ects of hydrogen absorption. Despite the lack of signi
cant structural alteration in these systems, electron transfer between the metal sublattice and hydrogen may occur, as manifested in the appearance/disappearance of magnetic phenomena and the increase/decrease of electrical conductivity. Whilst the hydrogen addition in ZrM₂-H occurs simply via an expansion of the crystal structure, hydrogen does not act purely as null dilutant - there exist subtle electronic changes connected with the hydriding process as well.
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Gonzatti, Frank. „Fundamentos para concepção, controle e automação de uma planta armazenadora de energia utilizando hidrogênio“. Universidade Federal de Santa Maria, 2017. http://repositorio.ufsm.br/handle/1/12933.
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Electrical generation with renewable sources is intermittent due to the characteristics of the primary energy (sun, wind, run of water, etc.). This feature can cause fluctuations and distortions on the voltage levels compromising power quality, stability and reliability when connected to an electrical system. The storage of energy acting together either as standalone unit or interconnected to the generating source of the public network can increase the penetration of these sources in the energy matrix. Among the different forms of energy storage, the one using hydrogen is quite promising because of its characteristics such as low environmental impact, high energy density, and energy high storage capacity. In this thesis, it is proposed some basis for designing, controlling and analyzing a hydrogen-based energy storage plant, consisting of a set of an alkaline type electrolyzer, hydrogen storage in the form of metallic hydrides and a fuel cell stack of the type PEM. The proposed plant was modeled and validated through experimental tests. The model allowed simulation of the main physicochemical quantities involved in the process of generation, storage and conversion of hydrogen into electricity storage. The fuel cell stack that is part of the energy storage was automated to avoid damages to the membrane, acting mainly on temperature control, elimination of contaminants on the anode side, and voltage reestablishment through the controlled application of short-circuits. The metal hydride cylinder storing hydrogen has been also automated with the main purpose of performing a thermal exchange in the best possible way between the metal alloy and the environment. Reuniting these devices to make them to act in synchrony, the plant was automated, controlled and monitored through a software developed in the LabView platform, making it more autonomous the whole plant. This program allows also acquisition and storage of the main physico-chemical quantities during the plant operation. These magnitudes collected in the tests along with the simulation results were analyzed and characterized the fundaments of this thesis.A geração de energia elétrica a partir de fontes renováveis é intermitente devido às características da energia primária (sol, vento, fio d'água, etc.) e podem causar oscilações e distorções nos níveis de tensão comprometendo a qualidade da energia, a estabilidade e a confiabilidade quando conectadas ao sistema elétrico. O armazenamento de energia atuando junto a fonte geradora isolada ou interligada à rede pública pode aumentar a penetração dessas fontes, de baixo impacto ambiental, na matriz energética. Entre as diferentes formas de armazenamento de energia, o uso de hidrogênio é considerado bastante promissor devido ao baixo impacto ambiental, alta densidade de energia e alta capacidade de armazenamento. Nessa tese, propõe-se as bases para concepção, controle e análise de uma planta armazenadora de energia baseada em hidrogênio, constituída por um eletrolisador do tipo alcalino, armazenamento de hidrogênio na forma de hidretos metálicos e uma pilha de células a combustível do tipo PEM. A planta proposta foi modelada e validada através de testes experimentais. O modelo permite simular as principais grandezas físico-químicas envolvidas desde o processo de geração, armazenamento e conversão do hidrogênio armazenado em eletricidade. A pilha de células a combustível, que faz parte do armazenador de energia, foi automatizada para operar sem danos a membrana, atuando principalmente no controle da temperatura, na eliminação de contaminantes no lado do ânodo e no reestabelecimento da tensão através da aplicação controlada de curtos-circuitos na pilha. O cilindro de hidreto metálico que armazena o hidrogênio também foi automatizado com o intuito principal de realizar a troca térmica da melhor forma possível entre a liga metálica e o ambiente. Unindo esses dispositivos para atuarem em sincronia, a planta foi automatizada, controlada e monitorada através de um software desenvolvido na plataforma LabView, de tal forma a torná-la mais autônoma. Este programa também permite que sejam adquiridos e armazenados o comportamento das principais grandezas físico-químicas durante operação da planta. Essas grandezas levantadas em testes juntamente com resultados de simulações, foram analisadas e caraterizada os fundamentos desta tese.
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Sahlberg, Martin. „Light-Metal Hydrides for Hydrogen Storage“. Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-107380.
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Zhu, Dan. „Energy management of the embedded hydride tanks considering efficiency degradation and life span on fuel cell vehicles“. Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCA008.
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Le développement des sources d'énergie alternatives devient très important en raison de l'effet du changement climatique et de l'épuisement des combustibles fossiles. L’hydrogène est prometteur grâce à sa ressource illimité, sa densité énergétique élevée, sa grande flexibilité technologique et sa nature respectueuse de l’environnement. Avec un potentiel élevé en matière de sécurité et de fiabilité, le stockage d'hydrogène avec des hydrures métalliques (MH) est considéré comme la meilleure méthode. Cette thèse contribue à l'étude des performances des systèmes de stockage de l’hydrogène MH embouqué, plus particulièrement l’état de charge, la modélisation dynamique et la gestion thermique la pile à combustible.Tout d'abord, des modèles sont proposés pour l'analyse dynamique des performances et le calcul de l'état de charge (SOC). Le processus d'estimation SOC en ligne est ensuite réalisé en combinant un classifieur d'états multi-joint. Le modèle dynamique du réservoir prenant en compte la conversion de masse et d'énergie est proposé à l'aide de paramètres optimisés identifiés par un algorithme d'optimisation d'essaim partiel. De plus, le comportement dynamique du système de pile à combustible intégrant la pile à combustible à membrane échangeuse de protons (PEMFC) et le réservoir de stockage d'hydrogène MH est simulé à l'aide d'un modèle mathématique défini et validé à l'aide d'une base de données provenant des véhicules réels. Une stratégie de gestion thermique avec contrôleur PID est proposée pour réduire la dégradation et prolonger la durée de vie de la PEMFC. Enfin, d’essai est conçu en laboratoire et des expériences sont menées pour valider les modèles et stratégies proposésNowadays, the development of alternative energy sources becoming particularly important due to the effect of climate change and fossil fuels depletion. Hydrogen holds great promise thanks to its unlimited resources, high energy density, large technological flexibility and the environmentally friendly nature. With high potential of safety, storing hydrogen with metal hydrides (MH) is considered to be the optimal on-board hydrogen storage method for the future hydrogen vehicle. This thesis therefore contributes to analyzing the performance and proprieties of embedded MH hydrogen storage systems, including the characteristic estimation, dynamic modeling and thermal management coupling with fuel cells.Firstly, statistical models are proposed for dynamic performance analysis and state of charge (SOC) calculation. The online SOC estimation process is then realized combining a multi-joint state classifier. The dynamic model of the embedded MH tank considering mass and energy conversion is proposed using optimized parameters identified through particle swarm optimization (PSO) algorithm. Moreover, the dynamic behavior of the fuel cell system integrating proton-exchange-membrane fuel cell (PEMFC) and MH hydrogen storage tank is simulated with a mathematical model set and validated using a database from the real operation vehicles. A thermal management strategy with PID controller is proposed to reduce the degradation and extend the lifespan of PEMFC. Finally, a test bench is designed in laboratory and experiments are carried out to validate the proposed models and strategies
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Hosni, Bilel. „Élaboration par mécano-synthèse d'alliages à base Ti-Fe : caractérisation de leurs propriétés de stockage électrochimique d'hydrogène“. Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCA015.
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L’hydrogène est la solution potentielle pour réussir la transition énergétique d’un système actuel basé en grande partie sur les combustibles fossiles vers un système non émetteur de gaz toxiques et respectueux de l’environnement. Cependant, le stockage de l’hydrogène est un grand défi qui freine son application pratique dans les différents domaines. Les hydrures métalliques permettent de stocker une grande quantité d’hydrogène de façon réversible dans de bonnes conditions (Température, pression, sécurité…) comparée aux autres modes de stockage (gazeux et liquide). En plus, ces mêmes matériaux sont utilisés comme électrode négative dans les batteries Nickel-Métal Hydrure.Dans la première partie de cette thèse, les alliages Ti-Fe ont été synthétisés parmécanosynthèse pour différents temps de broyage et différents rapports massiquesbilles/poudre. Afin d’optimiser les paramètres d’élaboration, ces alliages ont été caractérisés par différentes techniques telles que la diffraction des rayons X, la microscopie électronique à balayage, la chronopotentiométrie, la chronoampérométrie et la voltamétrie cyclique.Dans une seconde partie, les alliages TiFe+4%MWNTs, TiFe0.95-xMx, TiFe0.90M0.10 etTiFe0.90Mn0.05V0.05 (x=0.05, 0.15) (M : Mn ou V) ont été élaborés selon les paramètres optimaux déterminés précédemment. L’influence de l’additif Nanotubes de Carbone à multiparois (MWNTs), de la substitution partielle du Fe par Mn et/ou V et de l’excès de Titane sur les propriétés structurales, morphologiques et électrochimiques telles que l’activation, la capacité de décharge électrochimique, la réversibilité, la tenue au cyclage, le coefficient de diffusion ont ensuite été étudiés. Les propriétés redox des électrodes, le potentiel de Nernst et la densité du courant d’échange, ont été déterminés, en se basant sur la première loi de Sternet le modèle théorique de Bulter -Volmer.Les résultats électrochimiques obtenus montrent que l’alliage TiFe+4 wt.% MWNTs présente les meilleures performances : une activation rapide (au 1er cycle) et une meilleure capacité maximale de décharge (266 mAh g-1) avec une réversibilité qui reste inchangéeHydrogen is the potential solution to make a success of the energy transition of a current system basically based on fossil fuels towards a system friendly to environment. However, the storage of hydrogen is a big challenge that hinders its practical application in different areas.. Metal hydrides can store a large amount of hydrogen reversibly under good conditions (temperature, pressure, safety ...) compared to other storage modes (gaseous and liquid). In addition, these same materials are used as negative electrode in Nickel-Metal Hydride batteriesIn the first part of this thesis, Ti-Fe alloys were synthesized using mechanical alloying (MA) under argon atmosphere at room temperature, with different ball to powder weight ratio and at different milling times. In order to determine the optimal parameters of the elaboration the metallic composite were investigated using different techniques such as X-ray diffraction, scanning electron microscopy (EDS support), chronopotentiometry, chronoamperometry and cyclic voltammetry,In the second part, the metallic compounds, TiFe+4%MWNTs, TiFe0.95-xMx, TiFe0.90M0.10 and TiFe0.90Mn0.05V0.05 (x=0.05, 0.15) (M : Mn or V), which are used as the negative electrode material for Ni-MH secondary batteries, were synthesized by mechanical alloying according to optimal parameters, previously determined.The effect of MWNT addition, the Mn and/or V partial substitution for Fe and the excess of titanium on the structural, morphological and electrochemical parameters such as activation, electrochemical discharge capacity, reversibility, cycle life time and hydrogen diffusion coefficient were investigated.The redox properties of the electrodes such as the Nernst potential and the exchange current density were studied based on Stern’s first law and the theoretical model of Bulter-Volmer.The electrochemical properties of studied samples show the best performance for TiFe+4% MWNTs alloy. Indeed, this alloy presents a rapid activation (1st cycle) and a best discharge capacity (266 mAhg-1) with a reversibility remaining unchanged
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Galdino, Gabriel Souza. „Influência do Pr na microestrutura e propriedades elétricas em ligas á base de LaPrMgAIMnCoNi utilizadas em baterias de Ni-HM“. Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-03042012-140538/.
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Neste trabalho foram estudadas ligas La0,7-xPrxMg0,3Al0,3Mn0,4Co0,5Ni3,8 (x= 0 a 0,7) no estado bruto de fusão, para utilização em eletrodos negativos de baterias de níquel-hidreto metálico (Ni-HM). A caracterização das ligas foi realizada através das seguintes técnicas: microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva (EDS) e difração de raios X. Foi também determinada capacidade de absorção de hidrogênio destas ligas. A hidrogenação do material foi realizada em dois processos sendo: o primeiro denominado de baixa pressão (0,2 MPa de hidrogênio e temperatura de 500ºC) e o segundo de alta pressão (1 MPa e de hidrogênio e temperatura de 25ºC). Foi observado que com o aumento do teor de Pr a capacidade de absorção de hidrogênio diminui. Para o estudo da capacidade de descarga das baterias foi utilizado um analisador digital de quatro canais e observou-se um decréscimo na capacidade de descarga das baterias com adição de praseodímio para as composições La0,7-xPrxMg0,3Al0,3Mn0,4Co0,5Ni3,8 (x= 0 a 0,3). A maior capacidade de descarga (386 mAhg-1) e estabilidade cíclica foi obtida para a liga La0,2Pr0,5Mg0,3Al0,3Mn0,4Co0,5Ni3,8. Esta capacidade obtida pode estar relacionada com a maior proporção da fase LaMg2Ni9 encontrada na liga com adição de 0,5 % at. de Pr.The La0,7-xPrxMg0,3Al0,3Mn0,4Co0,5Ni3,8 (x= 0 a 0.7) as-cast alloys to apply in negative electrodes for nickel-metal hydride batteries (Ni-MH). The characterizations of the alloys were realized by: scanning electron microscope (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction techniques. A study of hydrogen absorption capacity of the alloys realized. The hydrogenation of the material was performed in two processes: the low pressure (0.2 MPa of hydrogen and temperature of the 773 K) and high pressure (1 MPa of hydrogen and temperature of the 298 K). It was observed that with increasing Pr content occurred a decrease the hydrogen absorption capacity. The capacity of discharge of the batteries was determined utilizing an analyzer digital computerized composed of four channels. It was observed decreases of the discharge capacity of the batteries when increase praseodymium content in La0,7-xPrxMg0,3Al0,3Mn0,4Co0,5Ni3,8 (x= 0 a 0.3) alloys. The highest discharge capacity (386 mAhg-1) and stability cyclic were obtained to La0.2Pr0.5Mg0.3Al0.3Mn0.4Co0.5Ni3.8 alloy. This capacity can be related to the higher proportion of phase LaMg2Ni9 in the alloy with the addition of 0.5 at.% Pr.
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Suárez, Santiago Hernán. „Gestion de l'énergie d'un système de piles à combustible alimenté par un réservoir d'hydrogène à hydrure métallique“. Electronic Thesis or Diss., Bourgogne Franche-Comté, 2022. http://www.theses.fr/2022UBFCA019.
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Ce travail de thèse s’inscrit dans le cadre de la contribution à l’avancée scientifique et technologique de l'utilisation des énergies renouvelables au moyen d'un système de piles à combustible PEMFC alimenté par de l'hydrogène provenant d'un réservoir à hydrure métallique. La première partie du travail a été consacrée à la caractérisation de deux réservoirs commerciaux de cette technologie en mettant l’accent sur la dégradation de leurs performances. Des méthodes stochastiques ont été utilisées pour étudier l’impact du cyclage (charge /décharge) sur la variation des paramètres intrinsèques du des réservoirs. Dans un la deuxième partie, les résultats de cette étude ont été mis en œuvre à travers un modèle énergétique du réservoir développé sous l’environnement MATLAB /Simulink. Ce dernier modèle a fait l’objet d’une validation expérimentale grâce à un banc de test spécialement réalisé à cet effet. Le phénomène de vieillissement a été mis en évidence, apportant ainsi une avancée significative notamment en vue de l'industrialisation de ce type de solution. Finalement, le couplage thermo-fluidique entre la pile à combustible et le réservoir d'hydrure a été expérimenté, modélisé et simulé numériquementThis thesis work is part of the contribution to the scientific and technological advancement of the use of renewable energies based on a PEMFC fuel cell system powered by hydrogen from a metal hydride tank. The first part of the work was devoted to the characterisation of two commercial tanks of this technology with emphasis on their performance degradation. Stochastic methods were used to study the impact of cycling (charge/discharge) on the variation of the tanks' intrinsic parameters. In a second part, the results of this study were implemented through an energy model of the tank developed under the MATLAB /Simulink environment. The model was validated experimentally on a specially designed test bench. The ageing phenomenon was highlighted, providing a significant advance, particularly with a view to the industrialisation of this type of solution. Finally, the thermo-fluidic coupling between the fuel cell and the hydride tank was experimented, modelled and numerically simulated
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Mistry, Priyen C. „Coated metal hydrides for stationary energy storage applications“. Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38798/.
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This thesis explores suitable materials for energy stores for stationary applications, specifically a prototype hydrogen store, domestic thermal store operating between 25-100 C and a moderate thermal store for a concentrated solar power (CSP) plant operating at 400 C. The approach incorporated a unique coating technique to deliver prototype hydrogen and thermal storage media, where the coating could offer commercial advantages, for example, in the form of hydride activation and enhanced kinetics during successive cycling. The highly reversible Mg-MgH2 system is particularly promising for thermal storage, obtaining an enthalpy of reaction of 74.5 kJ/mol H2 that translates to a thermal energy capacity of approximately 2800 kJ/kg of MgH2. Nevertheless, magnesium is hindered by slow activation and poor kinetics of (de)hydrogenation, even when approaching temperatures ideal for concentrated solar power applications (in the region 400 C). Elevated temperature cycling studies were performed on commercial atomised Mg powder with magnetron sputtered catalysts (chromium, iron, vanadium and stainless steel) applied to their surfaces; the aim of which was to fabricate hydrogen storage materials that possess (de)hydrogenation characteristics equal to or even bettering their nanocrystalline equivalents, yet in a potentially economic and scalable manner. Following 50 cycles at 400 C, the coatings were found to have little to no positive impact on the behaviour of the atomised Mg powders. In addition, for both uncoated and coated samples the effects of an activation process at 400 C are matched by cycling the material 5 times from the outset, after which identical behaviour is observed during subsequent cycles. At 350 C, the benefits of catalyst coatings on the hydrogen storage properties of atomised Mg powders are evident during activation and successive cycling up to 90 times. The material undergoes different microstructural evolution during cycling when in the presence of a surface catalyst, causing an enhancement of the `nucleation and growth' stage of (de)hydrogenation. This was attributed to particle reorientation dominating particle sintering, whereas the opposite occurs for the uncoated material. For the domestic thermal and prototype hydrogen stores a selection of AB and AB2 intermetallic hydrides enhanced through catalysis or thermodynamic modification were investigated. TiFe produced via powder atomisation obtained thermodynamic properties (dehydrogenation H = 28.9 kJ/mol H2 and S = 105 J/K.mol H2) in line with published results. The minor substitution of Ni into TiFe1-xNix resulted in different hydrogenation characteristics to TiFe, for example, TiFe0:96Ni0:04 possessed a dehydrogenation of H = 29.9 kJ/mol H2 and S = 107 J/K.mol H2. Discrepancies between maximum achieved and theoretical capacities were observed for both atomised TiFe and TiFe0:96Ni0:04 and a range of possible contributing factors are discussed. A minor addition of Pd (1.17 wt.%) magnetron sputtered to the surface of TiFe0:96Ni0:04 enabled successful room temperature hydrogenation with no activation treatment required. Characterisation (SEM and TEM) confirmed it is not necessary to have complete Pd coverage in the form of a uniform coating and XPS was utilised to derive a theory for the activation mechanism. The AB2 alloy comparison between the commercially available Hydralloy C5 and in house fabricated Ti0:9Zr0:2Mn1:5V0:2Cr0:3 showed that Hydralloy C5 was the most promising alloy for the hydrogen store application with the higher working capacity (ca. 0.96 wt.%) in the pressure range of 4-15 bar at 22 C, despite Ti0:9Zr0:2Mn1:5V0:2Cr0:3 obtaining a higher maximum storage capacity (1.82 wt.%). The hydrogenation kinetics of both alloys were studied with corresponding activation energies and hydrogen diffusion coefficients determined. The kinetics of hydrogenation for both alloys is sufficiently fast that only the heat transfer of the storage system is the rate limiting parameter for hydrogen exchange for most technical applications.
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Kalinichenka, Siarhei. „Rascherstarrte nanokristalline Magnesiumlegierungen für die Wasserstoffspeicherung“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-79095.
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Im Rahmen der vorliegenden Arbeit sind die Struktur und die Wasserstoffsorptionseigenschaften neuer nanokristalliner, hydridbildender magnesiumbasierter Legierungen, die mittels Rascherstarrung (Melt-Spinning Verfahren) hergestellt wurden, untersucht worden. Der Schwerpunkt der Arbeit bestand in der Erforschung der Vorgänge während der Aktivierung und der zyklischen Hydrierung/Dehydrierung der rascherstarrten Mg-Legierungen. Zusätzlich wurde das Gefüge, das sich nach der Kristallisation, Aktivierung bzw. Hydrierung einstellt, seine Erhaltung und Auswirkung auf das H2-Speicherverhalten (Struktur-Eigenschafts-Beziehungen) untersucht.
Die für die Verbesserung der Kinetik des H2-Speicherverhaltens angestrebte Nanostruktur konnte nach der Hydrierung der rascherstarrten Legierungen erreicht werden. Die REM-, TEM- sowie EFTEM (EELS)-Untersuchungen zeigten, dass ein Y-Zusatz zu Mg-basierten Legierungen zu einer sehr feinen (ca. 50 nm) und homogenen Verteilung von Y-Hydriden im Gefüge der rascherstarrten Bänder führt. Mg2Ni-Hydride bilden dagegen größere Körner im Größenbereich von 2-3 µm. Bei den Cu-haltigen Legierungen wurde eine Koexistenz von Mg2NiH4 und MgCu2 in direkter Nachbarschaft nachgewiesen.
Detaillierte Untersuchungen der Wasserstoffabsorption haben gezeigt, dass die Chemisorption während des linearen Anfangsbereiches des Hydrierungsverlaufes geschwindigkeitsbestimmend ist. Nach dem linearen Hydrierungsverlauf ist die Hydrierungskinetik von der Wasserstoffdiffusion durch eine geschlossene Hydridschicht beeinflusst.
Mit dem breiten Spektrum der Untersuchungen (REM, EELS, TEM, HP-TGA, DSC, in situ-Synchrotron-XRD) als auch durch gezielte Variation der Zusammensetzungen wurden neue und grundlegende Erkenntnisse zum H2-Speicherverhalten der rascherstarrten Mg-basierten Legierungssysteme gewonnen. Besondere Beachtung verdient die Mg90Ni8Y1,6SE0,4-Legierung. Durch die Möglichkeit einer einfachen Herstellung, ihre schnelle Reaktionskinetik, ihren hohen Wasserstoffgehalt (bis zu 5,6 Gew.%) und ihre gute Zyklenstabilität eignet sich diese Legierung zur sicheren, volumeneffizienten sowie leichtgewichtigen Speicherung von Wasserstoff. Damit kann Wasserstoff gespeichert, transportiert und als CO2-freier Sekundärenergieträger in stationären und mobilen Anwendungen eingesetzt werden.
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Jonas, Ncumisa Prudence. „Electrochemical energy conversion using metal hydrides hydrogen storage materials“. Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_2992_1361369645.
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Metal hydrides hydrogen storage materials have the ability to reversibly absorb and release large amounts of hydrogen at low temperature and pressure. In this study, metal hydride materialsemployed as negative electrodes in Ni-MH batteries are investigated. Attention is on AB5 alloys due to their intermediate thermodynamic properties. However, AB5 alloys a have
tendency of forming oxide film on their surface which inhibits hydrogen dissociation and penetration into interstitial sites leading to reduced capacity. To redeem this, the materials were micro-encapsulated by electroless deposition with immersion in Pd and Pt baths. PGMs were found to increase activation, electrochemical activity and H2 sorption kinetics of the MH alloys. Between the two catalysts the one which displayed better performance was chosen. The materials were characterized by X-ray difractommetry, and the alloys presented hexagonal CaCu5 &ndash
type
structure of symmetry P6/mmm. No extra phases were found, all the modified electrodes displayed the same behavior as the parent material. No shift or change in peaks which corresponded to Pd or Pt were observed. Scanning Electron Microscopy showed surface morphology of the materials modified with Pd and Pt particles, the effect of using different reducing agents (i.e., N2H4 and NaH2PO2), and alloys functionalized with &gamma
-aminosopropyltrietheosilane solution prior to Pd deposition. From all the surface modified alloys, Pt and Pd particles were observed on the
surface of the AB5 alloys. Surface modification without pre-functionalization had non-uniform coatings, but the prefunctionalized exhibited more uniform coatings. Energy dispersive X-ray Spectroscopy and Atomic Absorption Spectroscopy determined loading of the Pt and Pd on the surface of all the alloys, and the results were as follows: EDS ( Pt 13.41 and Pd 31.08wt%), AAS (Pt 0.11 and Pd 0.78wt%). Checking effect of using different reducing agents N2H4 and NaH2PO2 for electroless Pd plating the results were as follows: EDS (AB5_N2H4_Pd- 7.57 and AB5_NaH2PO2_Pd- 31.08wt%), AAS (AB5_N2H4_Pd- 11.27 and AB5_NaH2PO2_Pd- 0.78wt%). For the AB5 alloys pre-functionalized with &gamma
-APTES, the results were: EDS (10.24wt%) and AAS (0.34wt%). Electrochemical characterization was carried out by charge/discharge cycling controlled via potential to test the AB5 alloy. Overpotential for unmodified, Pt and Pd modified
electrodes were -1.1V, -1.24V, and -1.60V, respectively. Both modified electrodes showed discharge overpotentials at lower values implying higher specific power for the battery in comparison with the unmodified electrodes. However, Pd electrode exhibited higher specific power than Pt. To check the effect of the reducing agent the results were as follows: AB5_ N2H4_Pd (0.4V) and AB5_NaH2PO2_Pd (-0.2V), sodium hypophosphite based alloy showing lower overpotential values, implying it had higher specific power than hydrazine based bath. Alloy prefunctionalized with &gamma
-APTES, the overpotential was (0.28V), which was higher than -0.2V of the alloy without pre-functionalization, which means pre-functionalization with &gamma
-APTES did not improve the performance of the alloy electrode. Polarization resistance of the electrodes was investigated with Electrochemical Impedance Spectroscopy. The unmodified alloy showed high resistance of
21.6884 while, both Pt and Pd modified electrodes exhibited decrease 14.7397 and 12.1061 respectively, showing increase in charge transfer for the modified electrodes. Investigating the effect of the reducing agent, the alloys exhibited the following results: (N2H4 97.8619 and NaH2PO2 12.1061) based bath. Alloy pre-functionalized with &gamma
-APTES displayed the
resistance of 9.3128. Cyclic Voltammetry was also used to study the electrochemical activity of the alloy electrodes. The voltammograms obtained displayed the anodic current peak at -0.64V
o -0.65V for the Pt and Pd modified electrodes, respectively. Furthermore, the electrode which was not coated with Pt or Pd the current peak occurred at -0.59V. The Pd and Pt coated
alloy electrodes represented lower discharge overpotentials, which are important to improve the battery performance. Similar results were also observed with alloy electrodes Pd modified
using N2H4 (-0.64V) and NaH2PO2 (-0.65V). For the electrode modified with and without &gamma
-APTES the over potentials were the same (-0.65V). PGM deposition has shown to significantly
improve activation and hydrogen sorption performance and increased the electro-catalytic activity of these alloy electrodes. Modified electrodes gave better performance than the unmodified
electrodes. As a result, Pd was chosen as the better catalyst for the modification of AB5 alloy. Based on the results, it was concluded that Pd electroless plated using NaH2PO2 reducing agent
had better performance than electroless plating using N2H4 as the reducing agent. Alloy electrode pre-functionalized with &gamma
-APTES gave inconsistent results, and this phenomenon needs to
be further investigated. In conclusion, the alloy modified with Pd employing NaH2PO2 based electroless plating bath exhibited consistent results, and was found to be suitable candidate for
use in Ni-MH batteries.
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Koultoukis, Evangelos D. „Efficient hydrogen storage and compressors by using metal hydrides“. Thesis, University of Bolton, 2014. http://ubir.bolton.ac.uk/1309/.
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Hydrogen gas is considered as the key "green" technology for its endless production-consumption procedure, known better as the "water-cycle". In this cycle, hydrogen is directly produced from water electrolysis and while forms water again, when combusted with oxygen, releasing energy. However, as the most lightweight gas, the volumetric density of hydrogen makes it inappropriate for use in most fuel applications. Hydrogen storage technologies that promote the compression of the gas, along with a solid state form of storage, based on the consumer needs, are a critical component to further development of a hydrogen fuel-based economy. Among the breakthrough hydrogen technologies, metal hydrides have drawn special attention due to their multiple properties. Their ability to react with hydrogen at various pressure and temperature conditions opened a whole new universe for storing energy in the form of hydrogen. Moreover, their unique capability to operate as thermal machines in order to compress hydrogen is of major importance and it will probably affect future hydrogen technologies. The research described in this thesis tries to reveal new metal hydrides with enhanced properties or to enrich knowledge on already investigated compounds. The research conducted was multidisciplinary in nature and all the involved detailed investigations tried to identify correlations between micro-structural and chemical properties with the thermodynamic properties of the metal hydrides. The research undertaken focused in three key research areas: (i) structural characterization by means of the X-Ray Diffraction (XRD) technique and Rietveld analysis, (ii) microstructural observation and microchemical characterization by SEM/EDX analysis and (iii) thermodynamic properties investigation by hydrogen absorption/desorption measurements. The interactions between these different properties can be complex, and they are not always resulting to data that can be easily exploited. In a more extensive manner, several Ti- or Zr-based intermetallic alloys have been synthesized from pure elements either using the arc-melting or the induction-levitation melting method. Both techniques are characterized as "Rapid Solidification Processes" with crucial influence on the crystal structure of the investigated compounds. The word "crucial" has been used in the last phrase since the rapid solidification of the liquid compounds result in fine, well-structured microstructures that are, as well as with the chemical properties, the key factor of their thermodynamic properties. All the compounds have been fully characterized by XRD and SEM/EDX, and they are mostly exhibiting the hexagonal C14 or the cubic C15 type Laves phases. More specifically, Zr-based compounds with Laves phase structures are considered advantageous hydrides for the large span of plateau pressures (0 - 1000 bar) they can exhibit when forming reversible metal hydrides. Since these intermetallic compounds are considered as low temperature hydrides, all hydrogen Pressure-Composition Isotherms (PCI) have been conducted in the range of 0 to ~100 oC. It has been shown that small compositional changes can affect the atomic structure that has a direct effect, in respect, on the thermodynamic properties. Thus, compounds with really close composition can have a very large difference in the equilibrium pressures in some given temperatures. Finally, the metal hydride hydrogen compression technology is presented in terms that metal hydrides with successive equilibrium pressures can be used in order to increase hydrogen pressure using only waste heat as driving force.
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Guo, Sheng. „Light metal borohydrides and Mg-based hydrides for hydrogen storage“. Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5674/.
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This work has investigated structural and compositional changes in LiBH\(_4\), Mg(BH\(_4\))\(_2\), Ca(BH\(_4\))\(_2\), LiBH\(_4\)-Ca(BH\(_4\))\(_2\), MgH\(_2\)-B-TiX (TiX = Ti, TiH\(_2\) or TiCl\(_3\)), and hydrided Li-Mg alloy during heating. The crystal and vibrational structures of these borohydrides/composites were characterized using lab-based X-ray diffraction (XRD) and Raman spectroscopy, with particular attention to the frequency/width changes of Raman vibrations of different polymorphs of borohydrides. The thermal stability and decomposition pathway of the borohydrides was studied mainly using differential scanning calorimetry and thermogravimetric analysis, XRD and Raman measurements, whilst the gaseous products during heating were monitored using a mass spectrometry. Hydrogen is the main decomposition gaseous product from all of these compounds, but in some cases a very small amount of diborane release was also detected. These studies suggest that the thermal decomposition of the metal borohydrides occurs via a wide range of reaction pathways, often in several steps, which may involve simultaneous competing reactions. This can include the formation of stable borane intermediates/by-products which largely preclude the possibility of reversibility. Furthermore, the role of diborane in the decomposition and formation of borohydrides, was later studied by heating metal borohydrides (or hydrides) to various temperatures in a gaseous diborane-hydrogen atmosphere; and different types of borane products were observed.
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Javadian-Deylami, Seyd Payam. „Metal Hydrides as Energy Storage for Concentrated Solar Thermal Applications“. Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/58986.
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Hydrogen storage properties of LiBH4 may be changed by interaction with other complex hydrides due to an intimate interaction between the respective alkaline metals and boron which facilitate a relatively larger hydrogen storage capacity. The cyclic stability of the following binary complex hydride systems LiBH4-Ca(BH4)2, LiBH4-NaBH4 and LiBH4-NaAlH4 shows significant reversibility and due to their relative high gravimetric H2 storage capacity and specific heat storage capacity, they may potentially act as heat storage materials.
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Delhomme, Baptiste. „Couplage d'un réservoir d'hydrure de magnésium avec une source externe de chaleur“. Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00767941.
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L'objectif de la thèse était d'étudier la faisabilité d'un couplage thermique entre un réservoir d'hydrure métallique et une source externe de chaleur. L'évolution des propriétés de composites à base d'hydrure de magnésium (MgH2) a été étudiée en fonction du nombre de cycles d'hydruration. On observe une très bonne stabilité de la capacité massique d'absorption sur le long terme (600 cycles réalisés). Les premiers cycles sont néanmoins marqués par une évolution importante de la microstructure qui dépend de la proportion et/ou de la nature de l'additif utilisé lors de la mécano-synthèse des poudre d'hydrure. Cette évolution est associée à une augmentation de la conductivité thermique, mais également à une légère dégradation des cinétiques intrinsèques de réaction ainsi qu'à une expansion volumique des composites. Nos mesures montrent que l'amplitude des contraintes mécaniques engendrées sur les parois d'un réservoir se stabilisent après une cinquantaine de cycles. Un réservoir contenant 10 kg de MgH2, et capable de stocker 6500 Nl d'hydrogène en 35 minutes a ensuite été développé au laboratoire. L'énergie des réactions d'absorption et de désorption est échangée avec une source externe de chaleur via un fluide caloporteur. Ce système permet de représenter l'intégration thermique d'un réservoir d'hydrure dans un système de cogénération. Un modèle numérique a été développé afin de mieux appréhender le comportement de ce réservoir. Des essais de couplage entre un réservoir de taille plus modeste et une pile à combustible haute température (SOFC) développant une puissance électrique de 1 kW ont également été réalisés au Politecnico di Torino.
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Pickering, Lydia. „Ti-V-Mn based metal hydrides for hydrogen storage and compression applications“. Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4992/.
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The overall aim of this work was to investigate the synthesis of Laves phase-related BCC solid solution Ti V Mn based alloys for use in hydrogen storage and hydrogen compression applications. In particular, for Ti0.5V0.5Mn-based alloys, the effect of composition, microstructure, and crystallography on the hydrogen sorption properties, were investigated. After investigating seven novel compositions based on Ti-V-Mn, (i.e. Ti\(_{0.5}\)V\(_{0.4}\)TM\(_{0.1}\)Mn, where TM = Nb, Cr, Mo, Ta and Ti\(_{0.5}\)V\(_{0.5-x}\)Nb\(_x\)Mn, where x = 0.05, 0.2 and 0.5) it was found that small amounts (0.05 - 0.1 at%) of Nb substituted for V resulted in smaller hysteresis between absorption and desorption as well as higher hydrogen dissociation pressures. This finding led to the successful development of a two-stage metal hydride compressor utilising one of the novel composition (Nb = 0.05), which is capable of pressurising a cylinder up to 650 bar from an input pressure of less than 10 bar at 0.5 g H\(_2\)/min In summary, these findings confirm that it is possible to tailor the plateau pressure and enthalpy of a metal hydride system formed by alloying Ti-V-Mn with other transition metals.
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Rizo, Pavel. „Mg/transition-metal nanomaterials for efficient hydrogen storage“. Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1050/document.
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Nanomatériaux à base de magnésium et de métaux de transition pour un stockage efficace de l'hydrogène. Le magnésium est un élément de choix pour le stockage de l’hydrogène à l’état solide en raison de sa grande abondance dans la croûte terrestre et de ses fortes capacités de sorption massique et volumétrique de l’hydrogène. Cependant, la réaction de sorption souffre d'une cinétique lente et l'hydrure formé est trop stable pour des applications fonctionnant sous conditions ambiantes. Le premier problème peut être résolu en développant des composites associant deux hydrures, MgH2 et TiH2, à l'échelle nanométrique. Ces matériaux sont synthétisés par broyage mécanique sous atmosphère réactive. Cette technique permet la formation des nanocomposites et leur hydrogénation en une seule étape. De plus, ces matériaux peuvent être produits à grande échelle pour les besoins des applications. Les travaux ont été menés en trois parties : i) l’optimisation de la teneur en TiH2 dans le système (1-y)MgH2+yTiH2. Ceci a été accompli en ajustant la teneur en titane (0,0125 ≤ y ≤ 0,3 mole), tout en conservant une bonne cinétique, une réversibilité de l'hydrogène et une durée de vie utile. Les données montrent que la valeur y = 0,025 offre le meilleur compromis pour développer les propriétés les plus adéquates; ii) l'extension à d’autres métaux de transition pour le système 0,95MgH2 + 0,05TMHx (TM: Sc, Y, Ti, Zr, V et Nb), en évaluant la contribution de chaque additif sur la cinétique, sur la réversibilité de l'hydrogène et sur la durée de vie en cyclage; iii) la conception d'un dispositif de cyclage automatique capable de réaliser des centaines de sorption/désorption dans le but de mesurer la durée de vie des hydrures métalliques. Le travail a été effectué à l'aide de nombreuses méthodes expérimentales. Pour la synthèse, le broyage réactif sous atmosphère d'hydrogène a été principalement utilisé. La structure cristalline et la composition chimique des nanomatériaux ont été obtenues à partir de l'analyse par diffraction des rayons X (DRX). La taille et la morphologie des particules ont été déterminées par microscopie électronique à balayage et spectroscopie de rayons X à dispersion d'énergie (SEM / EDS). Les propriétés thermodynamiques, cinétiques et cycliques de la sorption d'hydrogène ont été déterminées par la méthode de SievertsMg/transition-metal nanomaterials for efficient hydrogen storageMagnesium metal is a prominent element for solid-state hydrogen storage due to its large abundance in earth’s crust and its high weight and volumetric hydrogen uptakes. However, hydrogen sorption suffers from sluggish kinetics and the formed hydride is too stable for applications working under ambient conditions. The former issue can be solved by developing composites combining two hydrides, MgH2 and TiH2 at the nanoscale. These materials are synthesized by mechanical milling under reactive atmosphere. By this technique, the formation of nanocomposites and their hydrogenation can be obtained in a single-step. Moreover, these materials can be produced at large scale for application purposes. The work focused on three topics: i) the optimization of the TiH2 content in the (1-y) MgH2+yTiH2 system. This was accomplished by optimizing the titanium content (0.0125≤y≤0.3 mole), while keeping good kinetics, hydrogen reversibility and cycle-life. The data show that y=0.025 is the best compromise to fulfill the most practical properties; ii) the extension to other transition metals for the system 0.95MgH2+0.05TMHx (TM: Sc, Y, Ti, Zr, V and Nb), evaluating the contribution of each additive to kinetics, hydrogen reversibility and cycle-life; iii) the conception of an automatic cycling device able to carry out hundreds of sorption cycles whit the aim of measuring the cycle-life of metal hydrides. The work was done using manifold experimental methods. For synthesis, reactive ball milling under hydrogen atmosphere was primarily used. The crystal structure and the chemical composition of nanomaterials was determined from X-ray diffraction (XRD) analysis. Particle size and morphology were obtained by Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDS). Thermodynamic, kinetic and cycling properties toward hydrogen sorption were determined by the Sieverts method
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George, Lyci. „Structural Characterization of Metal Hydrides for Energy Applications“. FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/233.
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Hydrogen can be an unlimited source of clean energy for future because of its very high energy density compared to the conventional fuels like gasoline. An efficient and safer way of storing hydrogen is in metals and alloys as hydrides. Light metal hydrides, alanates and borohydrides have very good hydrogen storage capacity, but high operation temperatures hinder their application. Improvement of thermodynamic properties of these hydrides is important for their commercial use as a source of energy. Application of pressure on materials can have influence on their properties favoring hydrogen storage. Hydrogen desorption in many complex hydrides occurs above the transition temperature. Therefore, it is important to study the physical properties of the hydride compounds at ambient and high pressure and/or high temperature conditions, which can assist in the design of suitable storage materials with desired thermodynamic properties. The high pressure-temperature phase diagram, thermal expansion and compressibility have only been evaluated for a limited number of hydrides so far. This situation serves as a main motivation for studying such properties of a number of technologically important hydrides. Focus of this dissertation was on X-ray diffraction and Raman spectroscopy studies of Mg2FeH6, Ca(BH4)2, Mg(BH4)2, NaBH4, NaAlH4, LiAlH4, LiNH2BH3 and mixture of MgH2 with AlH3 or Si, at different conditions of pressure and temperature, to obtain their bulk modulus and thermal expansion coefficient. These data are potential source of information regarding inter-atomic forces and also serve as a basis for developing theoretical models. Some high pressure phases were identified for the complex hydrides in this study which may have better hydrogen storage properties than the ambient phase. The results showed that the highly compressible B-H or Al-H bonds and the associated bond disordering under pressure is responsible for phase transitions observed in brorohydrides or alanates. Complex hydrides exhibited very high compressibility suggesting possibility to destabilize them with pressure. With high capacity and favorable thermodynamics, complex hydrides are suitable for reversible storage. Further studies are required to overcome the kinetic barriers in complex hydrides by catalytic addition. A comparative study of the hydride properties with that of the constituting metal, and their inter relationships were carried out with many interesting features.
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Blinov, D. V., V. I. Borzenko, D. O. Dunikov und S. P. Malyshenko. „Developing New Solid-state Hydrogen Storage and Purification Reactors“. Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35604.
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New metal hydride hydrogen storage reactors is developed. Automatic diagnostic system capable of measuring the temperature of the porous bed metal hydride, pressure in metal hydride purification reac-tor, gas flow rate on the inlet and outlet of purification modules, the number of components of the gas mix-ture with a gas analyzer.
The estimations of hydrogen losses and purification capacity show certain advantages of the studied technology in comparison with PSA-like mode [1], especially from the point of view of operation regime simplification.
Experimental studies on the charge and discharge reactors RHO - 8 and RHO - 8I with pure hydrogen, to obtain data for verification of mathematical models [1, 2], and determine the effect of the configuration beds absorbing materials on the performance of the reactor.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35604
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Mazwi, Sive. „Hydrogen storage in Ti-based coatings and Ti6Al4V alloy“. University of the Western Cape, 2016. http://hdl.handle.net/11394/5319.
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>Magister Scientiae - MScHydrogen has been regarded as an ideal energy carrier for future, it can be stored as a liquid in cryogenic tanks, a gas in high pressure cylinders and as solid in metal hydrides. Hydrogen storage in metal hydrides is of research interest because hydrides often have high energy density than gas or liquid hydrogen and are relatively safe. Ti and Ti alloys are promising hydrogen storage material because they have high affinity for hydrogen, light in weight and react reversibly with hydrogen. This work aims to investigate the hydrogen storage capacity of CP- Ti and Ti6Al4V alloy and Pd/Ti6Al4V alloy, where Pd was deposited on Ti6Al4V alloy. Samples were hydrogenated from room temperature to 650 °C at atmospheric pressure in the vacuum furnace under the 15%H/Ar atmosphere. Hydrogenation was carried out for a period of 3 hours for all samples. Sample composition and layer thickness were determined using Rutherford backscattering spectrometry. The microstructure and phase transformation were investigated using optical microscopy and X-ray diffraction technique. Hydrogen storage capacity was determined using elastic recoil detection analysis and gravimetric method. It was found that hydrogenation temperature has an effect on hydrogen absorption, microstructure and phase transformation. Maximum hydrogen concentration was obtained at hydrogenation temperatures of 550 °C for all materials with 45.57 at.% in CP-Ti, 34.77 at.% in Ti6Al4V alloy and 39 at.% H in Pd/Ti6Al4V coated system. In CP-Ti it was found that hydrogen absorption begins at 550 °C and decreases at hydrogenation temperature of 650 °C and that hydrogenation at both temperatures leads to formation of titanium hydrides and needlelike microstructure. At temperatures below 550 °C no hydrides were formed. For Ti6Al4V alloy ERDA results showed that no significant hydrogen absorption occurred at temperatures below 550 °C and at hydrogenation temperature of 650 °C, hydrogen absorption decreased drastically. The δ- titanium hydride was detected in the sample hydrogenated at 550 °C. Fine needle like microstructure was observed in the sample hydrogenated at 550 °C, and at higher temperature (650 °C ) coarse needles were formed. Pd coatings on Ti6Al4V alloy was found to increase the absorption of hydrogen, and allowing hydrogen to be absorbed at low temperatures.
National Research Foundation (NRF)
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Chaise, Albin. „Etude expérimentale et numérique de réservoirs d’hydrure de magnésium“. Grenoble 1, 2008. http://www.theses.fr/2008GRE10257.
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L'objectif de la thèse était d'étudier la faisabilité du stockage solide de l'hydrogène sous forme d'hydrure de magnésium (MgH2). Dans un premier temps la poudre de MgH2 activé a été caractérisée d'un point de vue cinétique, thermodynamique, et thermique. Les cinétiques d'absorption / désorption de l'hydrogène s'avèrent très sensibles à une exposition des poudres à l'air. La réaction d'hydruration, très exothermique, nécessite d'évacuer très rapidement la chaleur pour charger un réservoir dans un temps raisonnable. Afin d'augmenter la conductivité thermique, un procédé de mise en forme du matériau avec ajout de graphite naturel expansé (GNE) a été développé. Cette mise en forme permet d'obtenir des disques solides et usinables d'MgH2 activé de porosité réduite, présentant une densité volumique de stockage deux fois plus élevée que la poudre libre, et dont la manipulation est plus facile et sûre. L'analyse du comportement thermique et des flux gazeux a d'abord été menée avec un réservoir de faible capacité (90 Nl d'H2) mais permettant de s'adapter à des configurations expérimentales variées. Un second réservoir a été conçu pour répondre aux spécificités des composites "MgH2 + GNE". Ce réservoir permet d'absorber 1200 Nl (105 g d'H. ) en 45 minutes, avec une densité volumique système équivalente à celle d'une bouteille d'hydrogène comprimé à 480 bars. Simultanément, un modèle numérique du comportement des réservoirs de MgH2 a été développé à l'aide du logiciel Fluent®. Les simulations numériques des chargements et des déchargements concordent avec l'expérience et expliquent le comportement réactionnel du matériauThe target of this thesis was to study the feasibility of solid hydrogen storage in magnesium hydride (MgH2). At first, kinetic, thermodynamic and thermal properties of activated MgH2 powder have been investigated. Powders sorption kinetics are very sensitive to air exposure. The heat released by the very exothermic absorption reaction needs to be removed to load a tank with hydrogen in a reasonable time. In order to increase the thermal conductivity, a compression process of the material with expanded natural graphite (ENG) has been developed. Owing to that process, tough and drillable disks of MgH2 can be obtained with a reduced porosity and twice the volumetric storage capacity of the free powder bed. Handling those disks is easier and safer. Heat and mass transfer analysis has been carried out with a first small capacity tank (90 Nl), which is adapted to different experimental configurations. A second tank has been designed to fit disks of "MgH2 + ENG". This tank can absorbe 1200 Nl (105 g H. ) in 45 minutes, with a volumetric storage density equivalent to 480 bar compressed hydrogen. At the same time, a numerical modeling of MgH2 tanks has been achieved with Fluent® software. Numerical simulations of sorption process fit experiments and can be used for a better understanding of the storage material thermal and chemical behavior
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Yu, Jiamei. „DFT study of hydrogen storage in complex hydrides doped with transition metals“. Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1879993751&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Escobar, Diego. „Investigation of ZrNi, ZrMn2 and Zn(BH4)2 metal/complex hydrides for hydrogen storage“. [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0001894.
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Zarpelon, Lia Maria Carlotti. „Estudo das características eletroquímicas e microestruturais de eletrodos de hidreto metálico à base de LaNi com adições de elementos de liga“. Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-19012017-092218/.
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Neste trabalho avaliou-se a ação positiva da substituição de lantânio por praseodímio e de lantânio por magnésio na performance eletroquímica de eletrodos de ligas de armazenamento de hidrogênio em estado bruto de fusão e com tratamento térmico. O La foi substituído por Mg nas ligas La0,7-xMgxPr0,3Al0,3Mn0,4Co0,5Ni3,8 (x=0,0-0,7) e por Pr nas ligas La0,7-yPryMg0,3Al0,3Mn0,4Co0,5Ni3,8 (y=0,0-0,7). Os parâmetros eletroquímicos analisados foram ativação, capacidade de descarga, retenção da capacidade de descarga, autodescarga e alta taxa de descarga. As ligas apresentaram comportamento passivo em relação à corrosão. As análises por MEV/EDS e por DRX com refinamento por Rietveld revelaram a presença majoritária de fases similares às fases LaNi5, PrNi5, LaMg2Ni9 e PrMg2Ni9 em função das composições das ligas estudadas. Os parâmetros de rede e os volumes da célula unitária das fases diminuíram com a substituição crescente de La por Mg e de La por Pr. As capacidades de descarga máxima decresceram com a substituição crescente de La por Mg e de La por Pr, acompanhando o decréscimo da abundância da fase similar à fase LaNi5 e o aumento da abundância da fase similar à fase LaMg2Ni9. Comparativamente, menores taxas de autodescarga e maior estabilidade cíclica foram observadas para o eletrodo da liga na condição x=0,1, ao passo que o eletrodo da liga na condição y=0,0 apresentou maiores valores de alta taxa de descarga, indicando melhor performance cinética.In this work, the positive action of the substitution of lanthanum by praseodymium and lanthanum by magnesium in the electrochemical performance of the as-cast and annealed hydrogen storage alloys electrodes had been evaluated. La was replaced by Mg in La0.7-xMgxPr0.3Al0.3Mn0.4Co0.5Ni3.8 (x=0.0-0.7) alloys and by Pr in La0.7-yPryMg0.3Al0.3Mn0.4Co0.5Ni3.8 (y=0.0-0.7) alloys. The electrochemical parameters analyzed were activation, discharge capacity, discharge capacity retention, self-discharge rate and high-rate dischargeability. The alloys showed a passive corrosion behavior. The analyses by SEM/EDS and XRD with Rietveld refinement revealed the majority presence of LaNi5, PrNi5, LaMg2Ni9 and PrMg2Ni9 similar reference phases depending on the compositions of the studied alloys. The lattice parameters and cell volumes of the component phases decreased with increasing substitution of La for Mg and with La for Pr. The maximum discharge capacity decreased with increasing substitution of La for Mg and with La for Pr, following the decrease in the abundance of LaNi5 similar phase and the increase in the abundance of to the LaMg2Ni9 similar phase. Lower self-discharge rates were observed for the alloy electrode when x=0.1, while higher high-rate dischargeability for the alloy electrode when y=0.0 indicated better kinetic performance, comparatively.
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Agresti, Filippo. „Hydrogen Storage in Metal and Complex Hydrides: from Possible Niche Applications towards Promising High Performance Systems“. Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3426941.
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A promising alternative to hydrogen storage in high pressure cylinders and cryogenic tanks is the hydrogen storage in solid form as metal hydrides or complex metal hydrides. However, much research is still necessary in this direction. In particular, the optimal pressure and temperature of operation for the use of a hydride-based tank in a PEM fuel cell-powered vehicle should remain in the of 1-10 atm and 25-120 °C, respectively. The further difficulty is related to the weight of the storing materials, which is still too high for efficient mobile applications compared to the amount of stored hydrogen.
The work reported in this thesis deals with systems belonging to several hydride classes such as complex hydrides, interstitial metal hydrides and magnesium-based hydrides. Improvements from the point of view of thermodynamic and kinetic properties are proposed and discussed on systems almost ready for niche applications and on other very promising systems but still far from hydrogen storage applications. Among the classical interstitial hydrides-forming alloys, the interaction of hydrogen with TiCr1.78-xMnx alloys, one of the most promising for the use in high pressure-solid state hybrid tanks, has been studied. Among the Mg-based hydrides, a compacted Mg-Al-based material is proposed in order to overcome the degradation problems found during the scaling up of MgH2 as hydrogen storage medium. Concerning the complex hydrides, the kinetics improvement of the Li-Mg-N-H system by high energy ball milling processing is discussed and the problem of reversibility and slow decomposition kinetics of LiBH4 has been faced.Una promettente alternativa allo stoccaggio dell’idrogeno in bombole ad alta pressione e in contenitori criogenici è lo stoccaggio dell’idrogeno allo stato solido utilizzando idruri metallici o idruri complessi. In ogni caso, molta ricerca è ancora necessaria in questa direzione. In particolare, la pressione e la temperatura di lavoro ottimali per un serbatoio da utilizzare in una vettura basata su celle a combustibili PEM dovrebbero rimanere rispettivamente negli intervalli 1-10 atm e 25-120 °C. L’ulteriore difficoltà è legata al peso dei materiali assorbenti, che è ancora troppo elevato rispetto alla quantità di idrogeno stoccata per applicazioni veicolari efficienti. Il lavoro riportato in questa tesi riguarda sistemi appartenenti a diverse classi di idruri come idruri complessi, idruri metallici interstiziali, idruri a base di magnesio. Vengono proposti e discussi miglioramenti dal punto di vista termodinamico e cinetico apportati a sistemi ormai quasi pronti ad applicazioni di nicchia e ad altri molto promettenti ma ancora lontani da applicazioni per lo stoccaggio dell’idrogeno. Per quanto riguarda i classici idruri interstiziali, è stata studiata l’interazione dell’idrogeno con le leghe TiCr1.78-xMnx, tra le più promettenti per l’utilizzo in serbatoi ibridi ad alta pressione. Riguardo gli idruri a base di magnesio, un materiale basato su Mg-Al compattato in pastiglie viene proposto per ovviare ai problemi legati allo “scaling-up” del MgH2. Per quanto riguarda la classe degli idruri complessi, viene discusso il miglioramento delle cinetiche di assorbimento/desorbimento di idrogeno grazie al trattamento con macinazione ad alta energia e vengono affrontati i problemi della reversibilità e della lenta cinetica di decomposizione del LiBH4.
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Seyed, Mohammadshahi Shahrzad. „Mass and Heat Transfer in Intermetallic-Hydrogen Storage Tanks“. Thesis, Griffith University, 2017. http://hdl.handle.net/10072/366341.
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Hydrogen is a potential future energy carrier, but reliable storage of the hydrogen is required for widespread use. Metal-hydrides (MH) are suitable materials for safe, stable and long-term hydrogen storage applications such as off-grid and hybrid solar systems due to the ability to store hydrogen at moderate pressure and temperature. However, poor thermal properties of MH beds coupled with the need for managing the significant amount of heat generated during the absorption and desorption reactions, is a serious barrier for fast hydrogen uptake and release unless an efficient design for the MH tank and the heat exchange system is used. Appropriate design of the tank and thermal management systems as well as a suitable choice of material can improve the performance of the MH systems and make them more suitable for commercial use. It is not usually practicable to build and test different MH tanks for large scale applications and explore the impact of different design and process parameters on the performance of the tanks. In contrast, mathematical models can be employed for examining various parameters, scenarios and used to predict the effect on the MH system without the cost of materials and manufacturing time. These models, however, must be accurate in order to reliably design large scale MH tanks and components and this accuracy can be achieved by refinement of the model’s parameters and equations based on practical systems. In turn, the accuracy of the model also needs to be validated through experimental data obtained from operating tank systems under different conditions.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
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Ångström, Jonas. „Hydrogen absorption/desorption properties of the Sc(AlxNi1-x)2 system“. Thesis, Uppsala universitet, Oorganisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159372.
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Sc(AlxNi1-x)2 is a pseudobinary C14 Laves phase and a potential interstitial hydrogen storage material or anode in a Ni-MH battery. A previous study showed that Sc1Al1Ni1 can store hydrogen reversibly; both interstitially and trough decomposition into ScH2 and AlNi. It is also known that the exact composition is very important for the hydrogen storage properties of pseudobinary Laves phases. This thesis work is aimed at synthesising Sc(AlxNi1-x)2 and study the effect of the Ni/Al ratio on the hydrogen absorption/desorption process as well as the interstitial storage capacity. Compositions with high nickel content had the highest capacity (at least 0.67wt% for ScAl0.66Ni1.34) and ones with high aluminium content had the lowest total storage capacity (0wt% for ScAl1.28Ni0.62). The former composition was also shown to absorb and desorb hydrogen during multiple cycles. Desorption of interstitial hydrogen from ScAl0.66Ni1.34 requires 4.6kJ/mol in activation energy.