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Fisher, Jeffrey Dean. "The Icelandic example : planning for hydrogen fueled transportation in Oregon /." Connect to title online (Scholars' Bank), 2009. http://hdl.handle.net/1794/9899.
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Evans, Thomas H. "Development of an on-board compressed gas storage system for hydrogen powered vehicle applications." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10339.
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Thesis (Ph. D.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains viii, 162 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-142).
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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.
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Anwer, Andri, and Edward Boujakly. "En jämförelsestudie av risker och säkerhet mellan elbilar och vätgasbilar." Thesis, KTH, Hållbar produktionsutveckling (ML), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301026.
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Rapporten är skriven för ett högskoleingenjörsexamensarbete på kungliga tekniska högskolan, inom programmet maskinteknik, med inriktning industriell ekonomi och produktion. Bakgrunden av detta arbete ska ge läsaren en grund för de olika modellerna, elbilar och vätgasbilar samt väcka ett intresse för att bevara säkerheten med valet av bil. Syftet och målet med denna studie har varit att presentera en jämförelsestudie, gällande elbilar och vätgasbilar, samt svara på frågeställningarna som arbetet tagit fram. Resultatet av arbetet bygger på både FMEA- analyser för vätgasbilar och elbilar, samt jämförelsematris som ger en förtydligad bild på skillnader mellan elbilar och vätgasbilar, ur vissa valda funktioner. En förtydligad bild av FMEA analysen har byggt, genom att tillämpa ett paretodiagram som beskriver de olika risker och prioritering som finns för respektive modell. Rekommendationer och ytterligare säkerhetsarbeten för att minimera dessa risker beskrivs i FMEA analysen, utifrån indata och beskrivningar från tidigare rapporter, samt kunskap från studier. Resultatet från FMEA- analysen, paretodiagrammet, samt jämförelsematrisen visar att vätgasbilar är en säkrare modell och har en framtid eftersom utvecklingsmöjligheterna fortfarande finns, då dessa är nya på marknaden. Vätgasbilen är även mindre riskbenägen modell jämfört med elbilar, detta kan man visa med hjälp av RPN-talet, som är lägre för vätgasbilar, i jämförelse med elbilarnas RPN-tal.The background of this thesis will give the reader the basis for the models of electric and hydrogen fueled vehicles. The purpose and goal of this study has been to present a comparative study regarding electric and hydrogen vehicles, and to answer the questions that the study has raised. The results of the work are based on both FMEA analysis for hydrogen and electric vehicles, as well as a comparison matrix that provides a clarified picture of the differences between electric vehicles and hydrogen vehicles, through certain selected factors. A clarified picture of the FMEA analysis results has been built by applying a pareto diagram that describes the different risks of each model and also what their priorities are. Recommendations and additional safety work to minimize these risks are suggested and described in the FMEA analysis, based on input data and descriptions from previous reports, as well as gained knowledge from studies. The results from the FMEA analysis, pareto-diagram and the comparison matrix shows that hydrogen vehicles are a less risk-prone model compared to electric vehicles and have a bright future as development opportunities still exist, this due to the fact that they are still new in the automotive industry. This can be proved with the help of the RPN number for hydrogen vehicles, which is lower compared to the RPN number of electric vehicles.
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Meyer, Patrick E. "Vehicle & infrastructure relationships in hydrogen transportation networks : development of the H₂VISION modeling tool /." Online version of thesis, 2006. https://ritdml.rit.edu/dspace/handle/1850/2670.
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Pulido, Jon R. (Jon Ramon) 1974. "Modeling hydrogen fuel distribution infrastructure." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29529.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2004.Includes bibliographical references (p. 70-73).
This thesis' fundamental research question is to evaluate the structure of the hydrogen production, distribution, and dispensing infrastructure under various scenarios and to discover if any trends become apparent after sensitivity analysis. After reviewing the literature regarding the production, distribution, and dispensing of hydrogen fuel, a hybrid product pathway and network flow model is created and solved. In the literature review, an extensive analysis is performed of the forthcoming findings of the National Academy of Engineering Board on Energy and Environmental Systems (BEES). Additional considerations from operations research literature and general supply chain theory are applied to the problem under consideration. The second section develops a general model for understanding hydrogen production, distribution, and dispensing systems based on the findings of the BEES committee. The second chapter also frames the analysis that the thesis will review using the model. In the problem formulation chapter, the details of the analytic model at examined at length and heuristics solution methods are proposed. Three heuristic methodologies are described and implemented. An in-depth discussion of the final model solution method is described. In the fourth chapter, the model uses the state of California as a test case for hydrogen consumption in order to generate preliminary results for the model The results of the MIP solutions for certain market penetration scenarios and the heuristic solutions for each scenario are shown and sensitivity analysis is performed. The final chapter summarizes the results of the model, compares the performance of heuristics, and indicates further areas for research, both in terms of developing strong lower bounds
(cont.) for the heuristics, better optimization techniques, and expanded models for consideration.
by Jon R. Pulido.
M.Eng.in Logistics
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Campbell, Callum Richard. "Hydrogen storage and fuel processing strategies." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2564.
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It is widely recognised that fossil fuels are finite, and alternatives should be investigated to secure future energy supplies. Much research is directed towards hydrogen as a fuel, but the gas is unmanageable without an effective storage and distribution strategy. This work investigates the Methylcyclohexane-Toluene-Hydrogen (MTH) system of hydrogen storage with a view to providing vehicular fuel or storing energy produced by intermittent producers. Stable liquid-hydrocarbon hydrogen storage enables hydrogen distribution using the existing fossil fuel network, eliminating the need to build a new fuel infrastructure. A literature survey is carried out covering the area of Liquid Organic Hydrogen Carriers (LOHCs). A study of the technoeconomic bottlenecks which would prevent the widespread use of the MTH system is conducted to direct the project research efforts, which reveals that the vehicular on-board dehydrogenation system must be reduced in size to be practical. Process intensification is attempted by dehydrogenating methylcyclohexane in the liquid-phase, which is experimentally demonstrated in this work (an original contribution). However, to be feasible for a vehicle, the liquid-phase dehydrogenation system demands a specific window of conditions, with hydrocarbon vapour pressure, enthalpy of reaction and equilibrium constant all being important factors. No window is possible to satisfy all conditions for the MTH system, which renders this vehicular system infeasible. Alternative liquid carriers are investigated to solve the problem, but no clear candidate carrier is found without using highly experimental and costly molecules. This leads to a new investigation of other applications for the MTH system. MCH for power to a Scottish whisky distillery is investigated, followed by an investment appraisal of the distillery system. The system is technically feasible but attracts a high capital expenditure (almost £16M) and operational cost (£2.4M annually) which is uncompetitive with alternative options such as biomass fuels. Finally, possible future work in the field of LOHC technology is considered.
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Ciaravino, John S. "Study of hydrogen as an aircraft fuel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FCiaravino.pdf.
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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2003.Thesis advisor(s): Oscar Biblarz, Garth Hobson. Includes bibliographical references (p. 45-47). Also available online.
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Ye, Qiang. "Spontaneous hydrogen evolution in direct methanol fuel cells /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20YEQ.
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Damm, David Lee. "Batch reactors for scalable hydrogen production." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29705.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Andrei Fedorov; Committee Member: Srinivas Garimella; Committee Member: Timothy Lieuwen; Committee Member: William Koros; Committee Member: William Wepfer. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hussy, Ines. "Mesophilic fermentative hydrogen production from biomass." Thesis, University of South Wales, 2005. https://pure.southwales.ac.uk/en/studentthesis/mesophilic-fermentative-hydrogen-production-from-biomass(c099e92e-5777-48e9-bf1f-a1f72d91254e).html.
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Hydrogen is considered a possible alternative to fossil fuels. Hydrogen can be produced through dark fermentation with 1 mol hexose yielding a maximum of 4 mol hydrogen in association with acetate production, and 2 mol hydrogen in association with butyrate production. However, an economically and technically feasible process is yet to be established. So far research into fermentative hydrogen production has focused on pure and soluble carbohydrates, particularly glucose. To reduce substrate costs, use of more complex low-cost co- and waste products of the food industry or biomass crops which have undergone minimum pre-treatment would be desirable. Also, whilst much research to date has focused on use of pure bacterial strains, an easily obtainable mixed microflora would be preferable to avoid costs of substrate sterilisation. Therefore this research project focused on fermentative hydrogen production from three abundant (in the UK) low cost substrates, namely a wheat starch co-product, sugarbeet and perennial ryegrass. Anaerobic digester sludge obtained from the local sewage works was used as inoculum in a continuously stirred tank reactor. Production of hydrogen and other fermentation products was measured to gain information about the main metabolic pathways used. To lower hydrogen partial pressure the reactor was sparged with nitrogen and the effect on hydrogen production observed. It was demonstrated that stable fermentative hydrogen production from the wheat starch co-product and sugarbeet water extract was possible in continuous operation. Hydrogen production from grass extract was demonstrated in batch mode. Sparging with nitrogen significantly increased hydrogen yields, by 46% for the wheat starch co-product, by 67% for sugarbeet water extract, and by 184% for ryegrass extract. Maximum yields achieved were 1.9 mol hydrogen per mol hexose converted for 16 days on starch, 1.7 mol per mol hexose converted for 5 days on sugarbeet water extract and 0.8 mol hydrogen per mol hexose converted in batch from grass extract. Therefore up to 48% of the maximum theoretical hydrogen yield was produced. Various factors were identified as preventing higher hydrogen yields. Hydrogen production was more closely related to butyrate than acetate concentration. Also, lactate, ethanol and propionate, which are products of carbohydrate fermenting metabolic pathways that do not produce hydrogen, were detected, as were signs of hydrogen consuming homoacetogenesis in continuous operation.
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O'Keefe, Daniel Brian. "Temperature control of a hydrogen fuel cell stack." Tallahassee, Fla. : Florida State University, 2010. http://purl.fcla.edu/fsu/lib/digcoll/undergraduate/honors-theses/2181959.
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Thesis (Honors paper)--Florida State University, 2010.Advisor: Dr. John Telotte, Florida State University, College of Engineering, Dept. of Chemical and Biomedical Engineering. Includes bibliographical references.
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Björkman, Katarina. "Hydrogen gas in Sweden : Is hydrogen gas a viable energy carrier in Sweden?" Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-49015.
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Detta arbete innefattar att undersöka hur vätgas kan användas i Sverige, dels för energilagring men även som bränsle för fordon. Den ökande användningen av varierande förnyelsebara energikällor i den svenska energimixen innebär problem med stabilitet i kraftnätet, något som energilagring kan vara en lösning på. Samtidigt finns mål att fasa ut fossila energikällor, exempelvis diesel och bensin, något som transportsektorn är mycket beroende av. Enligt intervjuerna så är ett av de stora hindren för att implementera vätgas i Sverige att det saknas standarder och regelverk. Likaså framkommer det att de intervjuobjektens projekt inom vätgas i nuläget inte är pengamässigt lönsamma. I beräkningarna framkom det att varken det nuvarande fallet eller målfallet leder till lönsamma investeringar. Den sektor som är närmast lönsamhet är transportsektorn som kräver antingen en minskning på 90 % av komponenternas kostnad eller en 10-faldig ökning av priset på fossila bränslen. Slutsatserna dragna i denna studie är att det finns användningsområden för vätgas inom flera områden, bränsle, energilagring och inom industrin, utöver den användningen inom industrin som finns idag. För att ha en hållbar produktion av vätgas bör denna vara med elektrolys som baseras på emissionsfri elektricitet, exempelvis från solceller. De ekonomiska målen, i studien kallat target case, är inte tillräckliga utan ytterligare kostnadsminskningar kommer att behövas.There is a rising demand for energy and at the same time, fossil fuels need to be phased out due to global warming. This means that the energy needs to come from renewable energy resources, for instance photovoltaics. One issue with such energy sources is that they may have variating production which can induce issues with stability in the electrical grid. This study aims to investigate hydrogen in Sweden as energy storage and vehicle fuel. Methods used are literature review, interviews and calculations. According to the interviews are one of the main issues with implementing hydrogen the lack of standards. Today it is the local fire department who approves of hydrogen system which induces irregularities in the handling. It is also said that none of the projects in the interviews is profitable moneywise, something that also can be seen in the calculations. In order to reach break-even some serious changes with regarding costs of components or the alternative, for instance, fossil fuel and electricity. The application closest to break even is transportation which demands a 90 % decrease in component price or a 10-fold increase in fossil fuel price. In conclusion, there are future applications for hydrogen as energy storage, vehicle fuel and in industry, apart from the current industry applications. The most sustainable way to produce hydrogen is via electrolysis with emission-free electricity. In order for hydrogen to become economically viable, the target case is not enough but even greater cost reductions are needed.
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Thomas, Mathew. "Hydrogen applications for Lambert - St. Louis International Airport." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Thomas_Mathew_09007dcc805eac40.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed January 22, 2009) Includes bibliographical references (p. 53-55).
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Syed, Khurram Raza. "Electrochemical generation of hydrogen." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/13813.
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Global warming and the energy crisis are two of the greatest challenges on which mankind is currently focused. This has forced governments and other organisations to think how to protect the environment and how to reduce fuel costs. A variety of new and exciting technologies are being investigated to address the energy problem. Alternative energy sources such as solar power, fuel cells, wind power and tidal waves are active areas of commercial and scientific pursuit. A major area of current research is moving towards the hydrogen economy and hydrogen based energy systems. Hydrogen can be produced in many ways, most commonly by steam reforming of hydrocarbon (70% to 85% thermal efficiency) but the downside is that it releases carbon mono oxide (CO)), compared with commercial PEM electrolysers where performance has been reported to be 56 -73% at normal temperature pressure(NTP) with zero carbon emission. Electrochemical production of hydrogen has several advantages: (i) It gives pure hydrogen. (ii) It allows portability (e.g. Solar energy could be used to power the electrochemical cell). (iii) It can be produced on demand. The generation of Hydrogen via electrolysis has been the subject of many studies over the last two hundred years. However, there is still room for further work to improve both the efficiency of the process and methods of storage of the gas. The cleanest method at present is to produce hydrogen by electrolysis, and the main focus of this research is to design and develop such a green energy fuel cell for on-demand application. The aim of the work presented in this thesis was to further investigate the electrolysis method for hydrogen production. An Electrochemical fuel cell contains a minimum of two electrodes: the positively charged electrode called the anode where oxygen bubble will form, and the second negatively charged electrode called the cathode, where hydrogen bubbles will form during a chemical reaction caused by applying electrical current between these electrode. The project was initiated with the objective of finding a low cost solution for on-demand hydrogen generation. To establish a starting point, the first cell (cell-1) design was based on the work of Stephen Barrie Chambers (see chapter 3) to check the performance levels. The fabrication of the cell-1 design resulted in a mixture of hydrogen and oxygen in the same chamber, which means the cell-1 design, has a possible fire and explosion hazard. The device also has the drawback of lower performance of hydrogen production; columbic efficiency is between 40% to 46% at 1 amp to 3 amp current in 30% KOH alkaline solution. However, the advantage of reproducing Stephen’s innovation is that it allowed a quick and deep understanding of hydrogen generation. This thesis presents recent work on the fabrication of low cost electrolysis cells containing continuous flow alkaline (KOH, up to 30%) electrolyte using low cost electrodes (stainless steel 316) and membranes based on ultrahigh molecular weight polyethylene (UHMW PE) to produce hydrogen without the hazard of fire and explosion. In this research an On-Demand Hydrogen Generation cell-3 achieved a 95% hydrogen generation coulombic efficiency, which is about 49% efficiency improvement as compared to the stainless steel electrode, and was 22% better than the nano structured electrode. The typical cell voltage is 2.5 V at current flow ranging from 30 to 120 mA cm-2 in 30% KOH electrolyte. The achievement here of such high efficiencies paves the way for more research in the areas of space management, electrode surface structure and flow control (based on the application requirement). This invention can be used for aeronautic, marine and automotive application as well as in many other areas.
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Sheikhansari, Abdolkarim. "Evaluation of solid oxide fuel cells operating on hydrogen sulfide contaminated fuel." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/17699/.
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This research was conducted to investigate the effect of hydrogen sulfide on the performance of single solid oxide fuel cells. A test rig was designed and commissioned to test 5x5 cm2 cells (active area: 4x4 cm2). The test rig consists of a gas blender, a humidifier, a high temperature furnace, fuel and air manifolds and a control/data logging system. The characterisation techniques used in this project, include v-i measurement, EIS and SEM/EDX analysis. The first series of experiments were carried out to investigate the effect of time, hydrogen partial pressure and temperature on the performance of the cells operating on clean fuel. The results showed that the current of lowest resistance is independent of the operating temperature, however, depends on partial pressure of H2 and tends to increase as PH2 rises. The lowest resistance of the cell occurs at almost constant fuel utilization which was equal to 17 % in this research. In the second series of tests, the cells were exposed to a range of H2S concentrations i.e. 50, 100, 150 and 200 ppm. The composition of the fuel mixture was 0.1 nl/min (14.5 %) of H2, 0.567 nl/min (82.5 %) of N2 and 0.020 nl/min (3 %) of H2O (steam). All the contamination tests were carried out at 700 ˚C. The cells were exposed to H2S for 12 hours followed by a recovery period for 24 hours. The results revealed that the voltage drop at the end of the exposure period was similar for all degrees of poisoning. However, the performance at the end of the recovery, was different. The degree of recovery tended to decrease as the concentration of H2S increased. The SEM analysis of samples showed that H2S has caused the anode structure to change. This change occurred at the interface of anode functioning and support layers and was more severe at higher concentrations of H2S. In addition, two contamination models were developed based on the H2S degradation mechanism. The models considered the effects of time and H2S concentration. However, they could not predict the performance of the poisoned cells as the voltage drop at the end of exposure time was independent of the H2S concentration for the tested range.
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Deshmukh, Soumitra R. "Design principles for multifunctional microchemical systems application to portable hydrogen production /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.56 Mb., p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220736.
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Nilsson, Marita. "Hydrogen Generation for Fuel Cells in Auxiliary Power Systems." Doctoral thesis, KTH, Kemiteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10024.
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Heavy-duty trucks are in idle operation during long periods of time, providing the vehicles with electricity via the alternator at standstill. Idling trucks contribute to large amounts of emissions and high fuel consumption as a result of the low efficiency from fuel to electricity. Auxiliary power units, which operate independently of the main engine, are promising alternatives for supplying trucks with electricity. Fuel cell-based auxiliary power units could offer high efficiencies and low noise. The hydrogen required for the fuel cell could be generated in an onboard fuel reformer using the existing truck fuel. The work presented in this thesis concerns hydrogen generation from transportation fuels by autothermal reforming focusing on the application of fuel cell auxiliary power units. Diesel and dimethyl ether have been the fuels of main focus. The work includes reactor design aspects, preparation and testing of reforming catalysts including characterization studies and evaluation of operating conditions. The thesis is a summary of five scientific papers. Major issues for succeeding with diesel reforming are fuel injection, reactant mixing and achieving fuel cell quality reformate. The results obtained in this work contribute to the continued research and development of diesel reforming catalysts and processes. A diesel reformer, designed to generate hydrogen to feed a 5 kWe polymer electrolyte fuel cell has been evaluated for autothermal reforming of commercial diesel fuel. The operational results show the feasibility of the design to generate hydrogen-rich gases from complex diesel fuel mixtures and have, together with CFD calculations, been supportive in the development of a new improved reformer design. In addition to diesel, the reforming reactor design was shown to run satisfactorily with other hydrocarbon mixtures, such as gasoline and E85. Rh-based catalysts were used in the studies and exhibit high performance during diesel reforming without coke formation on the catalyst surface. An interesting finding is that the addition of Mn to Rh catalysts appears to improve activity during diesel reforming. Therefore, Mn could be considered to be used to decrease the noble metal loading, and thereby the cost, of diesel reforming catalysts. Dimethyl ether is a potential diesel fuel alternative and has lately been considered as hydrogen carrier for fuel cells in truck auxiliary power units. The studies related to dimethyl ether have been focused on the evaluation of Pd-based catalysts and the influence of operating parameters for autothermal reforming. PdZn-based catalysts were found to be very promising for DME reforming, generating product gases with high selectivity to hydrogen and carbon dioxide. The high product selectivity is correlated to PdZn interactions, leading to decreased activity of decomposition reactions. Auxiliary power systems fueled with DME could, therefore, make possible fuel processors with very low complexity compared to diesel-fueled systems. The work presented in this thesis has enhanced our understanding of diesel and DME reforming and will serve as basis for future studies.QC 20100804
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Ramos, Paja Carlos Andrés. "Fuel cell modelling and control for hydrogen consumption optimization." Doctoral thesis, Universitat Rovira i Virgili, 2009. http://hdl.handle.net/10803/8467.
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en Español:Se propone un modelo de FC basado en ecuaciones electroquímicas para predicción del exceso de oxígeno y de la temperatura de la pila, permitiendo además una conexión circuital con la carga. Así mismo, se presenta una técnica de modelado basada en Fuzzy, orientada a la emulación, obteniendo gran precisión con carga computacional reducida. Usando este último modelo se diseña e implementa un emulador. Estos modelos y el sistema de emulación fueron validados usando un sistema experimental.
Adicionalmente, diferentes topologías de sistemas de potencia basados en FC se proponen y analizan, obteniendo un criterio de selección dependiendo de la aplicación. Así mismo, se presentan criterios de control para una operación segura y eficiente del sistema. Finalmente, se proponen una metodología para la caracterización de los puntos óptimos de operación, y una estructura de control para operar en esas condiciones óptimas, siendo validados en un sistema experimental representativo del estado del arte.
in English:
A new FC modeling approach based on electrochemical equations for thermal and oxygen excess ration prediction with a circuit-based load connection is introduced. A fuzzy-based modeling technique is also proposed for emulation purposes, it reproducing the fuel cell dynamics with a high accuracy and a short computational time. The implementation of a fuel cell emulation system, based on this model, is described and analyzed. The models and the emulation system are experimentally validated by using a benchmark fuel cell system.
Different topologies for fuel cell-auxiliary storage devices interaction are also proposed and analyzed, thus giving an architecture selection criterion based on the load profile. Controllers, dynamic constrains and control objectives are designed for a safe and efficient fuel cell operation. Finally, a methodology for the identification of the fuel cell optimal operation conditions has been proposed, and a control strategy for operating in that optimal profile is introduced and validated.
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Haraldsson, Kristina. "On direct hydrogen fuel cell vehicles : modelling and demonstration." Doctoral thesis, Stockholm : Department of Chemical Engineering and Technology, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147.
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Reyes, Allan B. "Cryogenic, compressed, and liquid hydrogen fuel storage in vehicles." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40475.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Vita.
Includes bibliographical references.
Hydrogen is the viable energy carrier of future energy and transportation systems due to its clean emissions, light weight, and abundance. Its extremely low volumetric density, however, presents significant challenges to storage onboard vehicles. The study involves a survey of the current state of direct hydrogen storage technologies-cryogenic, compressed, and liquid storage-and an analysis of the problems associated with its storage. The significant storage problems that are reviewed and analyzed are issues with cool-down, boil-off, dormancy, materials, and space limitations. The goal of this study is to ultimately provide design insights on storage tanks, whether they be built for thermal performance (insulated), mechanical performance (pressure vessels), or both. The critical parameter that is analyzed is the inner shell wall thickness, or the layer that holds and encompasses the fuel. Graphs were provided to illustrate the reliance of the aforementioned problems on inner shell wall thickness. The results show that-given current materials-a nominal thickness of 10 cm is appropriate for liquid storage and a thickness of 4 cm is appropriate for flexibly fuelled storage and cryogenic compressed storage mechanisms.
(cont.) Additionally, the performance of these storage mechanisms was also projected for potential future materials. The conclusions were that more research needs to be dedicated into two broad areas: thermally-efficient insulation and stronger pressure vessel materials.
by Allan B. Reyes.
S.B.
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Mandal, Pratiti. "Investigation and Mitigation of Degradation in Hydrogen Fuel Cells." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/709.
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The ever increasing demand of petroleum in the transport sector has led to depletion of low cost/low risk reserves, increased levels of pollution, and greenhouse gas emissions that take a heavy toll on the environment as well as the national economy. There is an urgent need to use alternative energy resources along with an efficient and affordable energy conversion system to arrest environmental degradation. Polymer electrolyte fuel cells (PEFCs) show great promise in this regard - they use hydrogen gas as a fuel that electrochemically reacts with air to produce electrical energy and water as the by product. In a fuel cell electric vehicle (FCEV), these zero tail pipe emission systems offer high efficiency and power density for medium-heavy duty and long range transportation. However, PEFC technology is currently challenged by its limited durability when subjected to harsh and adverse operating conditions and transients that arises during the normal course of vehicle operation. The hydrogen-based fuel cell power train for electric vehicles must achieve high durability while maintaining high power efficiency and fuel economy in order to equal the range and lifetime of an internal-combustion-engine vehicle. The technology also needs to meet the cost targets to make FCEVs a commercial success. In this dissertation, one of the degradation phenomena that severely impede the durability of the system has been investigated. In scenarios where the cell becomes locally starved of hydrogen fuel, “cell reversal” occurs, which causes the cell to consume itself through carbon corrosion and eventually fail. Carbon corrosion in the anode disrupts the original structure of the electrode and can cause undesirable outcomes like catalyst particle migration, aggregation, loss of structural and chemical integrity. A comprehensive study using advanced electrochemical diagnostics and high resolution 3D imaging was performed and a new understanding to extend PEFC life time and robustness, by implementing engineered materials solutions, has been achieved. This will eventually help in making fuel cell systems more efficient, durable and economically viable, in order to better harness clean energy resources.
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Steneteg, Jakob. "Corrosion Resistant Multi-Component Coatings for Hydrogen Fuel Cells." Thesis, Linköpings universitet, Tunnfilmsfysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-174617.
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Multi-component coatings and high entropy alloys have in recent years attracted great interest for research, since they have shown to exhibit properties greater than the com- ponents of their parts. Today’s climate challenges requires transitioning from fossil fuels to renewable energy sources which demands use of new technology and new innovations. The hydrogen fuel cell is a technology which produces no carbon emissions, and the drive for innovation has led researchers to apply multi-component (high entropy alloys) coatings to invent the next generation hydrogen fuel cells and help the transition to renewable energy sources. This thesis has investigated the process-structure-property relationships of four deposi- tion growth parameters: target current (Itarget), argon pressure (PAr). substrate bias (Vsubstrate) and deposition time (tdeposition) on TiNbZrTa-coatings, grown by magnetron sputtering using an industrial deposition system. The range of the parameters have been: Itarget from 2.5 to 6 A, PAr from 1 to 17 mTorr, Vsubstrate from 30 to 200 V and tdeposition from 3.6 to 12 minutes (depending on Itarget). Coatings have been grown on Si (001) and stainless steel 304 and 316L substrates. The coating microstructure was analyzed by X-ray diffraction and electron microscopy. The results have yielded that all coatings are equimolar and that the coatings exhibit three different morphologies, two different topologies and two different corresponding structures. The different morphologies are wave, coarse columnar and fine columnar morphology. The two topologies are nodular and dune surface topology. The two different structures are a solid solution BCC (110) phase and an amorphous or nanocrystalline phase. The results indicate that parameters affecting the temperature of the substrate (Tsubstrate) is the prime decider for the final morphology of the coatings. High Itarget and Vsubstrate, low PAr and long tdeposition all increases Tsubstrate and results in a coating which exhibits a fine columnar morphology, dune topology and a solid solution BCC phase. These types of coatings have also proven to have improved corrosion resistance compared to the other type of coatings seen in this thesis. The other kind of coating is grown with low Itarget and Vsubstrate, high PAr and short tdeposition, which causes minimal increase of Tsubstrate. These growth parameters result in a coating with coarse columnar morphology, nodular topology and amorphous or nanocrystalline phase, with less corrosion resistance.FunMat II
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KHAGHANI, ALI. "MANUFACTURING OF MATERIAL BASED HYDROGEN FUEL FOR LIGHTWEIGHT VEHICLES." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613155.
Full textAbstract:
Vehicles powered by hydrogen fuel cells store hydrogen as a cooled liquid at 20 degrees kelvin
or a compressed gas at 10,000 pounds per square inch. An alternative that eliminates the need
for these extremes of temperature and pressure is to heat a compound containing covalently
bonded hydrogen, causing it to release the hydrogen to the fuel cell. Ammonia borane, which is
stable at ambient conditions, requires minimal energy for dehydrogenation, and is rich in
hydrogen, is a possible storage medium for hydrogen. If a viable storage system could be
engineered, demand for ammonia borane as a source of hydrogen would increase. The goal of
this project is to develop a processing plant and to optimize design specifications for scaling up
processing of ammonia borane through the metathesis reaction pathway. Optimization of
individual unit operations was determined using quality-by-design concepts, which allowed the
team to confirm scalability, design limitations, and competitive market pricing. The final design
involves the application of two mixers, two reactors, and four separators. The plant design
should yield 99 percent pure ammonia borane.
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Fabricio, de Barros Viktor, and William Sandberg. "The Transition Towards Hydrogen as a Sustainable Fuel : Exploring the Organizational Field of Hydrogen Mobility in Sweden." Thesis, Umeå universitet, Företagsekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-185359.
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The overall goal with this master’s thesis is to describe the institutionalization process of the organizational field of Hydrogen Refuelling Stations (HRS) with green hydrogen produced via electrolysis for the heavy-duty truck sector in Sweden. Hydrogen mobility is a recent technology, which makes its organizational field formation and development processes interesting to examine. As society is becoming more concerned about sustainable transitions from fossil-based fuels to renewable carbon-free sources of fuels, it was deemed relevant to make a thesis regarding the topic. We recognized that there was a need to further investigate the institutional process of an organizational field that may not yet be established and working with recent technologies. By studying an organizational field in its early phases, one might be able to get a deeper understanding of the underlying processes behind the formation and development of an organizational field. As the purpose of this study was to get a deeper understanding of the institutionalization process of HRS infrastructure for fuel cell heavy duty trucks in Sweden, interviews with people from the organizational field were made.As little was known about the given organizational field, stakeholder theory was used toidentify the four stakeholder groups of Customers, Suppliers, Interest Groups and Governmentwere selected in order to understand the roles different stakeholders play in the formation and development processes of organizational fields. In addition, some external trigger events from institutionalization theory were added which were “technical discontinuities” and “shocks”that likely sparks change will be further explaining factors. Furthermore, the commitment-trust theory is utilized to understand activities in cross-organizational projects that build commitment and trust that in turn strengthens the legitimacy of the collaboration. By combining these additional theories with institutional theory, we expect to contribute to the understanding of field formation and development. An analysis was made, comparing our empirical findings with literature from the theoretical framework. From that it was possible to conclude that the selected organizational field is currently in the first stage of the new institutionalization process and hold a discussion of trigger events and the role the different stakeholder currently inhabits and if there is more to be done from each stakeholder in the future. We are also establishing which actions the stakeholders commonly take when it comes to build commitment and trust in cross organizational projects. Lastly, recommendations and practical/theoretical contributions are provided.
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Lakshminarayanan, Karthikeyan. "Synthesis and characterization of hydrogen separation membranes." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/lakshminarayanan/LakshminarayananK0506.pdf.
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Aldenholt, Robin. "Hydrogen fuel cells for the development of a sustainable society : A case study on opinions and pedagogics regarding hydrogen fuel cells in Sandviken." Thesis, KTH, Skolan för teknikvetenskaplig kommunikation och lärande (ECE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206149.
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Last couple of years’ vehicles propelled by electricity generated from a hydrogen fuel cell has emerged as an alternative to the fossil fuel vehicles, so that the greenhouse gas emissions causing climate change can decrease. In Sandviken, a collaboration between the municipality, Sandvik AB and AGA has resulted in a hydrogen refuelling station, only the fourth in Sweden. As the knowledge and awareness of hydrogen fuel cells is unknown Sandvik AB wants to investigate what the general opinion and knowledge is but more importantly, how can pedagogical theories be used to increase awareness and knowledge. The purpose of this thesis is therefore to examine what the population of Sandviken think of a development of a hydrogen society as well as climate change and the concept of sustainable development. Based on the found status of knowledge and awareness in these issues a couple of tools and actions are suggested on how to increase general knowledge and awareness, applicable both for schools and organisations outside school. The method used to fulfil the purpose was a survey that was sent out to people employed at Sandviken municipality and Sandvik AB. The survey results were analysed to see which factors correlate with a likelihood to support a hydrogen society development. That is used to see what approach to use when educating people about hydrogen and sustainable development. The results show that people in Sandviken were very positive about the hydrogen refuelling station, and the level of knowledge people had did not significantly affect how much support they showed. However, the people’s support for a hydrogen development is greatly affected by the fact that a refuelling station has been built. Therefore, the result that the level of hydrogen knowledge seems irrelevant should not be taken as a general fact true for all societies. When educating people about hydrogen one should put emphasis on raising awareness and knowledge in sustainable development and climate change, since that has a positive effect on the likelihood to support a hydrogen development. This could be done via a, in this report constructed, SSI case (socio-scientific issues) that can be adjusted to fit environments and occasions outside school.De senaste åren har bilar framdrivna av elektricitet producerad av vätgasbränsleceller blivit ett alternativ till bilarna som drivs av fossila bränslen, så att växthusgasutsläppen som orsakar klimatförändringen kan minskas. I Sandviken har ett samarbete som involverar Sandvikens kommun, Sandvik AB och AGA resulterat i en tankstation för vätgas, endast den fjärde i Sverige. Eftersom kunskapsnivån och medvetenheten om vätgasbränsleceller är okänd vill Sandvik AB undersöka vad den generella åsikten och kunskapen om detta är men kanske ännu viktigare, hur man kan använda pedagogik-teorier för att öka kunskap och medvetenhet. Syftet med det här arbetet är därför att studera vad invånarna i Sandviken tycker om en utveckling av ett vätgassamhälle, liksom klimatförändring och konceptet hållbar utveckling. Baserat på den nuvarande statusen på kunskap och medvetenhet inom dessa ämnen kommer rapporten att föreslå ett antal verktyg och åtgärder som kan användas för att öka kunskap och medvetenhet, tillämpbara både i skolan och i organisationer utanför skolan. För att uppfylla det här syftet så skickades en enkät ut till anställda på Sandvikens kommun och Sandvik AB. Enkätresultaten analyserades för att utforska vilka faktorer som korrelerar med en sannolikhet att stödja en utveckling av ett vätgassamhälle, något som kan användas som en utgångspunkt när man utbildar människor om detta. Resultaten visar att människor i Sandviken var mycket positiva till vätgastankstationen och att nivån av kunskap om vätgas de har inte direkt påverkade hur mycket stöd de visade. Dock kan det faktum att en tankstation har byggts påverka hur mycket stöd vätgas har. Att kunskapsnivån om vätgas skulle vara irrelevant ska därför inte ses som ett generellt resultat applicerbart på alla samhällen. När man vill utbilda människor om vätgas så bör tonvikt läggas på att öka kunskap och medvetenhet för hållbar utveckling och klimatförändringen, eftersom dessa faktorer visade sig ge en positiv effekt på sannolikheten att stödja en utveckling av ett vätgassamhälle. Det kan göras genom att använda det SNI-fall (samhällsfrågor med naturvetenskapligt innehåll) som finns beskrivet i rapporten och som kan justeras för att passa miljöer och tillfällen utanför skolan
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Semidey, Flecha Lymarie. "First-principles approach to screening multi-component metal alloys for hydrogen purification membranes." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31710.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Dr. David S. Sholl; Committee Member: Dr. Andrei G. Fedorov; Committee Member: Dr. Ronald R. Chance; Committee Member: Dr. Victor Breedveld; Committee Member: Dr. William Koros. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Emerson, Charles W. "Hydrogen energy : a study of the use of anaerobic digester gas to generate electricity utilizing stand-alone hydrogen fuel cells at wastewater treatment plants /." Online version of thesis, 2007. http://hdl.handle.net/1850/5474.
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McGlocklin, Kristin Hew Eden Mario R. "Economic analysis of various reforming techniques and fuel sources for hydrogen production." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Theses/MCGLOCKLIN_KRISTIN_35.pdf.
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Koorts, Waldo Pieter. "Scoping of a commercial micro reformer for the production of hydrogen." Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/8175.
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Hydrogen has gained interest as fuel recently as the harmful effects of fossil fuels on the environment can no longer be ignored. Hydrogen, which produces no pollutants, forms the feed for cleaner fuel cells systems currently in use. Fuel cells, although not as economically viable as fossil fuels, have found a foothold in the energy market in various markets like power backup and use in remote locations. Production of hydrogen is still largely done via fossil fuel reforming and this technology has received renewed interest for use with fuel cells in the form of micro- reformers or fuel processors. This study entailed the performance benchmarking of a so called Best-in-Class commercial micro reformer (as available in 2010), the 1 kW WS FLOX Reformer, and was undertaken under the auspices of the national HySA programme. The study’s focus was primarily on reformate output quality (carbon monoxide concentration), and start up time, thermal efficiency and hydrogen output (15 SCLM). The reformer consisted of a combustion section encased in an outer reforming section consisting of three reactors in series, steam reforming, water gas shift and selective methanation. As-provided temperature control is simplified though the use of only one temperature setpoint in the combustion chamber and temperature control in the CO clean up stages obtained through means of heat transfer with incoming water being evaporated. Combustion takes place through flame combustion or by means of the supplier’s patented FLOX (flameless oxidation) combustion. The purchased FLOX Reformer assembly was integrated into a fully automated unit with all balance of plant components as well as microGC and flue gas analysis for measurement of outlet conditions. The FLOX Reformer was tested at multiple combustion temperatures, combustion flowrates, reforming loads and steam-to-carbon ratios to obtain a wide set of benchmark data. From the testing it was found that the reformer was able to produce the necessary 15 SCLM hydrogen with a carbon monoxide purity of less than 10 ppm as required in fuel cells for all testing if the reaction temperatures were within the recommended limits. Intermediary water gas shift analysis showed methane and carbon monoxide conversion in the reforming and water gas shift stages to be identical to thermodynamic equilibrium conversion – 95% and higher for all temperatures. iii Selective methanation conversion obtained was 99%, but not always at equilibrium conversion due to increased selective methanation temperatures, where carbon dioxide methanation was also observed at the higher temperatures. Temperature control through heat exchange with incoming water in the CO removal stages was found to be less than ideal as the temperature inside these stages fluctuated dramatically due to inaccuracies in the water pump and a lagged response to flowrate changes. Startup times of less than an hour was observed for multiple combustion flowrates and the reformer boasts a standby function to reduce this to less than half an hour. The thermal efficiency was independently confirmed and tested and found to be higher than 70 % for flame combustion and on par with other commercially available fuel processors. The suppliers trademark FLOX combustion only reaching 65% due to decreased combustion efficiency.
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Varady, Mark Jordan. "Fuel reformation and hydrogen generation in direct droplet impingement reactors." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42826.
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Distributed hydrogen generation from liquid hydrocarbon fuels to supply portable fuel cells presents an attractive, high energy density alternative to current battery technology. Traditional unit operation reactor design for hydrogen generation becomes inadequate with decrease in scale because of the unique challenges of size and weight minimization. To address the challenge of reactor scale-down, the concept of multifunctional reactors has emerged, in which synergistic combination of different unit operations is explored to achieve improved performance. The direct droplet impingement reactor (DDIR) studied here is based on this approach in which the liquid feed is atomized using a regularly spaced array of droplet generators with unparalleled control over droplet characteristics, followed by vaporization and reaction directly on the catalyst surface. Considering each droplet generator in the array as a unit cell, a comprehensive, first-principles model of the DDIR has been developed by considering the intimately coupled processes of 1) droplet transport, heating, evaporation, and impingement on the catalyst surface, 2) liquid reagent film formation, capillary penetration, and vaporization within the catalyst layer, and 3) gas phase heat and mass transfer and catalytic reactions. Simulations are performed to investigate the effect of reactor operating parameters on performance. Experimental validation of the model is carried out by visualizing droplet impingement and liquid film accumulation while simultaneously monitoring reaction product composition over a range of operating conditions. Results suggest an optimal unit cell shape for reaction selectivity based on a balance between reagent back diffusion and catalyst bed thermal resistance. Further, achieving a target throughput is best accomplished by adding together a larger number unit cells with optimized geometry and lower throughput (per unit cell) to more effectively spread heat and avoid hotspots at the catalyst interface. At the same time, conditions must be satisfied for ensuring droplet impingement on the catalyst surface, which become more stringent as unit cell throughput is decreased.
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Kyazze, Godfrey. "Hydrogen production via dark fermentation of carbohydrate-rich substrates." Thesis, University of South Wales, 2007. https://pure.southwales.ac.uk/en/studentthesis/hydrogen-production-via-dark-fermentation-of-carbohydraterich-substrates(99988ecc-92c4-4c04-98a2-23ff8d097fc3).html.
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Hydrogen could replace fossil fuels for power generation and transportation and contribute to a low carbon economy. However, current methods of producing hydrogen e.g. steam methane reformation of natural gas are not sustainable and also contribute to COi emissions. Dark fermentation of carbohydrate-rich waste organics and energy crops to hydrogen using mixed microflora could contribute to the mix of technologies for producing hydrogen sustainably. Naturally available mixed microflora can be enriched e.g. by heat treatment to select for hydrogen producers, typically clostridia. Fermentation endproducts from the hydrogen-producing stage could be fed to a second anaerobic digestion stage to recover more energy as methane and to stabilise the effluent. Although anaerobic digestion is well established, fermentative hydrogen production is not. This work evaluated the feasibility of hydrogen production from two energy crops, grass and fodder maize in batch culture without pretreatment; investigated the effect of increase in substrate (sucrose) concentration, attractive from an energy point of view, on the yield and stability of hydrogen production in continuous culture; examined the performance of a mesophilic high rate anaerobic digester treating effluent from a continuous hydrogen-producing bioreactor; demonstrated the possibility of changeover of substrate - sucrose, starch and xylose - during continuous hydrogen production and evaluated the effect of sparging with CO2 , a process gas, on hydrogen production. It was demonstrated for the first time that hydrogen production from grass and fodder maize by direct fermentation in batch culture (2.3 L reactor, 35°C, pH 5.2-5.3) is possible, with hydrogen yields of 75.6 ml/g dry matter wilted perennial rye grass and62.4 ml/g dry matter of fodder maize. In continuous culture (pH 5.2-5.3, 35°C, 12 hour hydraulic retention time (HRT)), stable hydrogen production was achieved up to 40 g/L sucrose concentration - with decreasing hydrogen yields, from 1.7±0.2 mol/mol hexose added at 10 g/L to 1.2±0.3 mol/mol hexose at 40 g/L - beyond which the system became unstable. The decrease in hydrogen yield and lack of stability at higher substrate concentrations was attributed to feedback inhibition by volatile fatty acids (VFAs). Effluent from the hydrogen reactor was readily degraded in an upflow anaerobic filter up to an organic loading rate of 10 gCOD/L/d (2 d HRT) and/or a sodium concentration of 1.87 g/L. Reduction of sodium levels in the methane reactor by using calcium hydroxide as alkali in the hydrogen reactor was found to extend the efficiency of degradation of VFAs; overall COD reduction for the two stage system fed with 20 g/L sucrose increased from 83% (with NaOH as alkali) to 91% with Ca(OH)2 . It was easier to switch from starch to sucrose and vice versa during continuous hydrogen production; however switching from sucrose or starch to xylose was slower, requiring operation for about 1 day in batch culture before continuous operation could commence. Sparging with CO2 improved hydrogen yield from sucrose by at least 71% and appeared to inhibit homoacetogenesis from starch. This work verifies the potential technical feasibility of generating hydrogen, a clean energy carrier, sustainably from carbohydrate-rich waste organics and energy crops.
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Ma, Zhu. "First-principles study of hydrogen storage materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22672.
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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2008.Committee Chair: Mei-Yin Chou; Committee Member: Erbil, Ahmet; Committee Member: First, Phillip; Committee Member: Landman, Uzi; Committee Member: Wang, Xiao-Qian.
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DeGolyer, Jessica Suzanne. "Fuel Life-Cycle Analysis of Hydrogen vs. Conventional Transportation Fuels." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-08192008-124223/.
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Fuel life-cycle analyses were performed to compare the affects of hydrogen on annual U.S. light-duty transportation emissions in future year 2030. Five scenarios were developed assuming a significant percentage of hydrogen fuel cell vehicles to compare different feedstock fuels and technologies to produce hydrogen. The five hydrogen scenarios are: Central Natural Gas, Central Coal Gasification, Central Thermochemical Nuclear, Distributed Natural Gas, and Distributed Electrolysis. The Basecase used to compare emissions was the Annual Energy Outlook 2006 Report that estimated vehicle and electricity mix in year 2030. A sixth scenario, High Hybrid, was included to compare vehicle technologies that currently exist to hydrogen fuel cell vehicles that commercially do not exist. All hydrogen scenarios assumed 30% of the U.S. light-duty fleet to be hydrogen fuel cell vehicles in year 2030. Energy, greenhouse emissions, and criteria pollutant emissions including volatile organic compounds, particulate matter, sulfur dioxides, nitrogen dioxides, and carbon monoxide were evaluated. Results show that the production of hydrogen using thermochemical nuclear technology is the most beneficial in terms of energy usage, greenhouse gas emissions, and criteria pollutant emissions. Energy usage decreased by 36%, greenhouse gas emissions decreased by 46% or 9.6 x 108 tons, and criteria emissions were reduced by 28-47%. The centrally-produced hydrogen scenarios proved to be more energy efficient and overall release fewer emissions than the distributed hydrogen production scenarios. The only hydrogen scenario to show an increase in urban pollution is the Distributed Natural Gas scenario with a 60% increase in SOx emissions..
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Imholt, Timothy James Roberts James Andrew. "Carbon nanotube/microwave interactions and applications to hydrogen fuel cells." [Denton, Tex.] : University of North Texas, 2004. http://digital.library.unt.edu/permalink/meta-dc-5796.
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Brady, C. D. A. "Non-noble electrocatalysts for hydrogen oxidation in acidic fuel cells." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596860.
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The objective of this project was to advance the development of cost effective, low-temperature hydrogen fuel cells, by creating non-noble anode electrocatalysts for application in acidic electrolytes. The electrocatalytic activity of nanocrystalline tungsten carbides, WC and W2C, towards the anodic oxidation of hydrogen is presented. The tungsten carbides, which were synthesised by solid-state reduction of W(VI) using carbon, are both electrocatalytic. The WC phase shows greater electrocatalysis than the W2C phase, and also shows a greater degree of passivity against corrosion. Silver was co-deposited on the WC phase which results in ca. 25% higher electrocatalytic activity towards the hydrogen electrode reactions relative to WC alone. WC synthesised with Co or Ni additions shows reduced passivity because of the formation of corrodible Ni2W4C and Co3W10C3.4 phases, neither of which show any significant electrocatalytic activity. Furthermore, Ni and Co catalyse the crystal growth of WC during thermal synthesis. This lowers the catalytic performance of electrodes relative to those fabricated from nanocrystalline WC. The Frey-Farthing-Chen electrodeoxidation of NiTa2O6, CoTa2O6 and NiWO4 in the presence of carbon produces TaC or WC particulate electrocatalysts and corrodible Ni or Co containing side-products. TaC shows increased passivity against corrosion but reduced electrocatalytic activity relative to WC. The electrocatalytic activity of the carbides was not enhanced by this synthetic procedure or by the presence of Ni or Co. A compositional range of amorphous, Ni-C and Co-C thin films were synthesised. Ni-C thin films show higher catalytic activity than Co-C thin films of equivalent metal concentration. Films containing less than 20 atm% metal passivate in sulphuric acid. Films containing more than 20 atm% metal do not passivate fully in acid but still show much greater corrosion resistance than the pure metals.
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Granlund, Moa Z. "Fuel Reforming for Hydrogen Production in Heavy-Duty Vehicle Applications." Doctoral thesis, KTH, Kemisk teknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159423.
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The depletion of fossil fuels together with growing environmental concerns have created incitement for developing a more energy-efficient and environmentally-friendly vehicle fleet. The development towards cleaner heavy-duty vehicles started already in the 80’s with the introduction of emission legislations. Initially, engine optimization was enough for reaching the legislated levels of emissions. However, at present engine optimization is not enough but exhaust aftertreatment has become an essential part of heavy-duty vehicles, in order to meet the emission standards. Today, the total emissions are targeted which means that there is an interest in decreasing the idling emissions as well as the emissions during operation. To reduce the overall emissions several states in the USA have introduced idling legislations. Due to the limitations in idling time alternative solutions for power generation during rests are requested. A possible alternative is a fuel cell auxiliary power unit, combining a fuel cell with a fuel reformer (FC-APU). The focus of this thesis is the development of the fuel reformer for an FC-APU, in which the hydrogen to the fuel cell is generated from diesel in a high-temperature catalytic process. The produced hydrogen can also be used in other heavy-duty vehicle applications i.e. selective catalytic reduction of NOx (HC-SCR), where addition of hydrogen is essential for reaching high conversion at low temperatures. The effect of using hydrogen from a fuel reformer in HC-SCR is included in this work. The catalytic material development is focused on developing promoted materials with lower rhodium content but with catalytic activity comparable to that of materials with higher rhodium content. This includes evaluation and extensive characterization of both fresh and aged promoted materials. The work also includes reactor design where a micro reactor with multiple air inlets is evaluated. This work has contributed to increased knowledge of catalytic materials suitable for reforming of diesel. By changing the support material from the traditionally used alumina to ceria-zirconia, increased H2 yield was achieved. In addition, the ceria-zirconia supported material was less prone to coke. By promoting the material with cobalt or lanthanum it was possible to decrease the rhodium content by 2/3 with enhanced catalytic performance. It was also discovered that promotion with lanthanum decreased the tendency for coking even further. Additionally, the lanthanum-promoted material had higher thermal stability as well as a stable highly dispersed rhodium phase. Furthermore, the work has contributed to an increased knowledge concerning the fuel reformer’s effect on HC-SCR. The work displays clear evidence of benefits with using hydrogen-rich gas from a fuel reformer instead of pure hydrogen. The benefits are derived from the content of low molecular weight hydrocarbons present in the hydrogen-rich gas, which are strong reducing agents increasing the NOx reduction. This finding proves that fuel reforming in combination with HC-SCR is a viable option for NOx abatement.QC 20150202
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Jarvis, Jennifer Anne. "Hydrogen entry in Zircaloy-4 fuel cladding : an electrochemical study." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103730.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 291-297).
Corrosion and hydrogen pickup of zirconium alloy fuel cladding in water cooled nuclear reactors are life-limiting phenomena for fuel. This thesis studies the fate of hydrogen liberated by waterside corrosion of Zircaloy-4 fuel cladding in Pressurized Water Reactors (PWRs): are the adsorbed protons incorporated into the oxide and eventually the metal, or are they evolved into molecular hydrogen and released into the coolant? Water chemistry modeling was used to understand effects of radiolysis and CRUD. Density functional theory (DFT) was used to investigate the role of oxidized Zr(Fe,Cr)2 second phase particles. Chemical potentials and the electron chemical potential were used to connect these two modeling efforts. A radiolysis model was developed for the primary loop of a PWR. Dose profiles accounting for fuel burnup, boron addition, axial power profiles, and a CRUD layer were produced. Dose rates to the bulk coolant increased by 21-22% with 12.5-75 pim thick CRUD layers. Radially-averaged core chemistry was compared to single-channel chemistry at individual fuel rods. Calculations showed that local chemistry was more oxidizing at high-power fuel and fuel with CRUD. Local hydrogen peroxide concentrations were up to 2.5 ppb higher than average levels of 5-8 ppb. Radiolysis results were used to compute chemical potentials and the corrosion potential. Marcus theory was applied to compare the band energies of oxides associated with Zircaloy-4 and the energy levels for proton reduction in PWR conditions. Hydrogen interactions with Cr203 and Fe203, both found in oxidized precipitates, were studied with DFT. Atomic adsorption of hydrogen was modeled on the Cr and Feterminated (0001) surfaces. Climbing Image-Nudged Elastic Band calculations were used to model the competing pathways of hydrogen migration into the subsurface and molecular hydrogen formation. A two-step mechanism for hydrogen recombination was identified consisting of: reduction of an adsorbed proton (H+) to a hydride ion (H-) and H2 formation from an adjacent adsorbed proton and hydride ion. Overall, results suggest that neither surface will be an easy entrance point for hydrogen ingress and that Cr203 is more likely to be involved in hydrogen evolution than the Fe203.
by Jennifer Anne Jarvis.
Ph. D.
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Margarit, Bel Nuria 1977. "Chemical simulation of hydrogen generation in a plasma fuel reformer." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17781.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.Includes bibliographical references (p. 101-103).
A model for a plasma fuel reformer or plasmatron has been developed. The model was based in a series of experiments realized at the Plasma Science and Fusion Center with such a plasmatron. The device is set up to produce syngas (hydrogen and carbon monoxide gas mixture) from partial oxidation of any hydrocarbon. We studied the behavior of methane as fuel and used the GRI methane combustion mechanism in our simulations. The goal was to characterize the reactor to be able to understand and predict its performance for a wide range of operating conditions, such as different flow rates, air to fuel flow ratio or power supply. The simulation tool used for this purpose was CHEMKIN 3.7. The fuel reformer was designed as a reactor where combustion is initiated by an electric discharge due to ohmic heating of the arc region. Two different types of reactors were used to model the plasmatron. The Plug Flow Reactor (PLUG) assumed a homogenous zero-dimensional closed system. The Partially Stirred Reactor (PASR) considered random mixing determined by a frequency mixing parameter, which is directly dependant of the system fluid dynamic properties. Experimental results with methane generated 6%-7% molar of hydrogen and 5% of carbon monoxide. Hydrogen and oxygen balance evidenced that water and carbon dioxide are important co-products, obtaining respectively 10% and 3% at the exhaust. Also 15%- 20% of methane and 3%-5% of oxygen remained unreacted. From discharge observations, energy estimations and model simulations, it was found that the electric arc initiates combustion by locally rising the temperature and then propagating the reaction by heat and mass transfer/mixing to the surroundings.
(cont.) Simulation results demonstrated that there is an optimum characteristic mixing time for each residence time, depending on the initial temperature reached at the arc. It was also found that the more spread the energy is, or the more mass is heated to a moderate temperature, the better the performance results.
by Nuria Margarit Bel.
S.M.
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Laguna, Bercero Miguel A. "Hydrogen and fuel cells: an efficient and clean energy alternative." Revista de Química, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/100084.
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El avance tecnológico más importante de las próximas décadas pasa por el uso del hidrógeno como combustible, sustituyendo el consumo masivo de los combustibles fósiles. De esta manera, utilizando tecnologías basadas en pilas de combustible, conseguiremos sistemas energéticos más eficientes que los actuales y, además respetuosos, con el medio ambiente.The most important technological development in the coming decades will be the use of hydrogen as an alternative to the widely used fossil fuels. By the use of fuel cell based technologies, it will be feasible to produce energy systems that will be more efficient than the current ones and that will also be environmentally friendly.
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Kaini, Bhanu. "THERMODYNAMIC EVALUATION OF PROCESSES FOR HYDROGEN PRODUCTION FROM CARBONACEOUS FUEL." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/328.
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This research work presents the thermodynamic analysis of hydrogen production using steam methane reforming process at different conditions. The model is developed using HSC 4.1 software and spreadsheet. Methane is chosen to represent the carbonaceous fuel and steam methane reforming process (once through and cyclic) for hydrogen production is analyzed based on 1st law and 2nd law of thermodynamics i.e., energetic and exergetic efficiencies. The mass, energy and exergy analysis of each step is done. The optimal condition for production of maximum hydrogen is found using CO2 removal agent and O2 transfer compound. The efficiency is calculated as a function of steam content, temperature and amount of CO2 removal agent and O2 transfer compound. The pressure is kept constant at one atmosphere. Operating temperature, CaO loading, Fe2O3 loading and H2O content is determined from the once through process. It is found that the maximum H2 production is with the cyclic process. Maximum H2 produced in cyclic process with CaO & Fe2O3 loadings is 99.2%. Also CO2 content is comparatively lower in cyclic process. Theoretical efficiencies can be used to compare with the available data which will help to minimize the losses in the process. The results can be used as a baseline for the design of H2 production technology. The main aim of this research is to develop a thermodynamic protocol for evaluating hydrogen production processes.
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Fereidounizadeh, Neda. "Hydrogen Fuel in Sweden, a Comparative Study of Five Countries." Thesis, Linnéuniversitetet, Institutionen för byggd miljö och energiteknik (BET), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105303.
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Under the shadow of the climate change dilemma and its consequence for the human’s future, the need for secured and stable energy sources is vital. Academia, political leaders, and influential business actors play a key role to introduce schemes to facilitate the adaptation of new technologies and energy systems improvement. Hydrogen as an energy carrier is one of the solutions to tackle environmental concerns in recent decades. However, hydrogen technology needs constant development to reduce its cost and to find production methods by which fossil fuels can be replaced by clean hydrogen. In this study, five different countries in terms of hydrogen technology introduction, their National Strategy on Hydrogen, influential variables on hydrogen application have been investigated. Along with a comparison between five countries, the differences in policies and political incentives and their effect on hydrogen applications have been studied. Policy incentives work differently according to the various cultural norms. In some countries such as Japan financial incentives work better but in some such as Sweden non-financial incentives work well. Along with policy introduction, collaboration between policy, industry, and academia contribute to the successful introduction, diffusion, and application of new technologies. Regarding hydrogen technology in Sweden, introduction of National Strategy on Hydrogen, a shift from hydrogen application in industry to transport section, and giving less priority to biogas and more to hydrogen fuel, applying suitable policy incentives can be helpful for Sweden to act faster and benefit more from hydrogen.
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Imholt, Timothy James. "Carbon Nanotube/Microwave Interactions and Applications to Hydrogen Fuel Cells." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc5796/.
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One of the leading problems that will be carried into the 21st century is that of alternative fuels to get our planet away from the consumption of fossil fuels. There has been a growing interest in the use of nanotechnology to somehow aid in this progression. There are several unanswered questions in how to do this. It is known that carbon nanotubes will store hydrogen but it is unclear how to increase that storage capacity and how to remove this hydrogen fuel once stored. This document offers some answers to these questions. It is possible to implant more hydrogen in a nanotube sample using a technique of ion implantation at energy levels ~50keV and below. This, accompanied with the rapid removal of that stored hydrogen through the application of a microwave field, proves to be one promising avenue to solve these two unanswered questions.
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Shentsov, Volodymyr. "Safety of indoor use of fuel cell and hydrogen systems." Thesis, Ulster University, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648022.
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This research investigates and closes a number of knowledge gaps in the safety of the indoor use of fuel cell and hydrogen (FCH) systems. New analytical models were developed and validated for steady state release and dispersion of hydrogen in an enclosure with one and two vents. Jet fire phenomena were studied for different combustion regimes, including well-ventilated and under-ventilated regimes, self-extinction, re-ignition and an external jet flame. To identify aims and objectives a broad literature review of theoretical, experimental and modelling work relating to hydrogen releases and jet fires has been completed. Based on knowledge gaps identified a model for passive ventilation of a sustained gaseous leak in an enclosure with one vent has been developed on the assumption of perfect mixing. The model predictions are compared against experimental helium concentration for both uniform and non-uniform helium-ail' mixtures. The criterion for mixture uniformity in an enclosure with one vent is suggested. Model equations derived for passive ventilation aided for the developments of engineering tools in the form of nomograms. These nomograms can be used to calculate the mass flow rate limit leading to 100% hydrogen concentration and calculation of steady state hydrogen concentration in the enclosure. In situations where simple analytical formulas are not applicable use of CFD is required. For this reason Numerical and physical requirements were formulated for simulations of light gas release and dispersion in one vent enclosure based on a parametric study and are acceptable from hydrogen safety engineering point of view. Hydrogen jet fire phenomenon requires numerical investigation therefore a study performed to identify general rules for hydrogen fire regimes in an enclosUl'e. Two modes of under-ventilated fires were observed and identified: external flame and self-extinction of the flame. The phenomenon of the hydrogen flame "re-ignition" by termination of hydrogen supply in an enclosure with one and two vents was reproduced in numerical experiments and recommendations are given. An equation is proposed foJ' the prediction of time when, two possible modes of under-ventilated regimes can occur: self-extinction or an external flame. The results of the current research have contributed to the European guidelines deliverable D 5.1 of the "Pre-normative research on safe indoor use of fuel cells and hydrogen systems" HyIndoor project (www.hyindoor.cu).
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Shan, Xi. "Hydrogen Storage for Micro-fabricated Electrochemical Devices." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1089864469.
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Liu, Hong, and 劉紅. "Bio-hydrogen production from carbohydrate-containing wastewater." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31244518.
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Chidziva, Stanford. "Green hydrogen production for fuel cell applications and consumption in SAIAMC research facility." University of Western Cape, 2020. http://hdl.handle.net/11394/7859.
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Philosophiae Doctor - PhDToday fossil fuels such as oil, coal and natural gas are providing for our ever growing energy needs. As the world’s fossil fuel reserves fast become depleted, it is vital that alternative and cleaner fuels are found. Renewable energy sources are the way of the future energy needs. A solution to the looming energy crisis can be found in the energy carrier hydrogen. Hydrogen can be produced by a number of production technologies. One hydrogen production method explored in this study is electrolysis of water.
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Marthosa, Sutida. "Improvement of electrocatalyst performance in hydrogen fuel cells by multiscale modelling." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/improvement-of-electrocatalyst-performance-in-hydrogen-fuel-cells-by-multiscale-modelling(534c4857-865e-4759-a44f-e1639e4eaa1b).html.
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The work in this thesis addresses the improvement of electrocatalyst performance in hydrogen PEM fuel cells. An agglomerate model for a catalyst layer was coupled with a one dimensional macroscale model in order to investigate the fuel cell performance. The model focuses on the agglomerate scale and the characteristic length in this study was 0.4 µm. The model was validated successfully with the experimental data. Based on the analysis of variance method at a 99% confidence level, the variation in the average fuel cell voltage was significantly sensitive to that in the volume fraction of electrolyte in an agglomerate. The effect of changing electrolyte film thickness was observed to have a significant impact only in the mass transport limited region, whereas the effect of changing agglomerate radius was found over the entire range of current density. An analysis comparing the effect of agglomerate shape at a constant platinum loading, a constant characteristic length and assuming the semi-finite structure was suitable for this study. Sphere, cylinder and slab agglomerate geometries were considered. The behaviour of the utilisation effectiveness was discovered to be strongly affected by the agglomerate shape. The improvement in the utilisation effectiveness was non-linear with current density. The advantage of the slab geometry in distributing reactant through the agglomerate volume was reduced and consequently the increase in utilisation effectiveness for slab-like agglomerates diminishes in the high current density region. At 0.85 Acm−2, the maximum improvement of the catalyst utilisation effectiveness in slab was 27.8% based on the performance in sphere. The improvement in fuel cell maximum power density achieved using slab-like agglomerate was limited to around 3%. The improvement in the overall fuel cell performance by changing the agglomerate shape was not significant. To achieve significant improvements in fuel cell performance will require changes to other features of the catalyst layer.
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Sjödin, Andreas, and Elias Ekberg. "Hydrogen - The future fuel for construction equipment? : A well to tank analysis of hydrogen powered machine applications at Volvo CE." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-48753.
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As the world is moving towards a more sustainable energy perspective, construction equipment sees the requirement to change its current way of operation with fossil fuels to reduce its environmental impact. In order to pursue the electrification of construction equipment a dense power source is essential, where hydrogen powered fuel cells have the potential to be a sufficient energy source. This thesis work is carried out in order to find the least CO2 emissive pathway for hydrogen to various construction sites. This is done by collecting state of the art data for production, processing and storage technologies. With the assembled data an optimization model was developed using mixed integer linear programming. The technologies found that showed promising adaptability for construction equipment in the state of art regarding production were steam methane reforming (SMR), proton exchange membrane electrolyser (PEMEC) and alkaline electrolyser. They showed promising characteristics due to their high level of maturity and possibility for reducing the environmental impact compared to the current operation. To investigate the hydrogen pathway and its possibilities, four scenarios were created for four types of construction sites. The scenarios have different settings for distance, grid connection and share of renewables, where the operations have various energy profiles that is to be satisfied. The optimal hydrogen pathway to reduce the CO2 emissions according to the model, were either PEMEC on-site or gaseous delivery of SMR CCS produced hydrogen. The share of renewables in the energy mix showed to be an important factor to determine which of the hydrogen pathways that were chosen for the different scenarios. Moreover, in the long run PEMEC was considered to be a more sustainable solution due to SMR using natural gas as feedstock. It was therefore concluded that for a high share of renewables PEMEC was the optimal solution, where for a low share of renewables SMR CCS produced hydrogen was optimal as the energy mix would result in a more emissive operation when using PEMEC.