Denna förstudie har utförts ombord på Stena Vision och syftar till att undersöka om en bränslecellskonvertering av fartygets elkraftsproduktion är tekniskt genomförbar. Genom att studera fartygets konstruktion, samt de lagar och förordningar som gäller för installationer på fartyg, har författarna konstruerat ett förslag på ny elnätsstruktur som presenteras i bilaga B2. Författarna lägger även fram ett designförslag på ett bränslesystem, för det nya bränslet vätgas, vilket presenteras i bilaga D. En viktig slutsats är att om en fullständig konvertering, där även nödgeneratorn ersätts, kommer en lagändring vara nödvändig. / This feasibility study has been carried out onboard Stena Vision and it aims to investigate if a fuel cell conversion of the ships electrical power production plant is technically possible. Through studies of the ships construction, as well as laws and regulations regarding ships installations, the authors has constructed a proposal for a new design for the electrical system. The proposal is presented in "bilaga B2". The authors also presents a design proposal for a new fuel system, adapted for the new fuel hydrogen. The new fuel system proposal is presented in "bilaga D". One of the most important conclusions in this thesis is that a full conversion, including the emergency generator, would demand a law amendment.

abstract: Proton exchange membrane fuel cells (PEMFCs) run on pure hydrogen and oxygen (or air), producing electricity, water, and some heat. This makes PEMFC an attractive option for clean power generation. PEMFCs also operate at low temperature which makes them quick to start up and easy to handle. PEMFCs have several important limitations which must be overcome before commercial viability can be achieved. Active areas of research into making them commercially viable include reducing the cost, size and weight of fuel cells while also increasing their durability and performance. A growing and important part of this research involves the computer modeling of fuel cells. High quality computer modeling and simulation of fuel cells can help speed up the discovery of optimized fuel cell components. Computer modeling can also help improve fundamental understanding of the mechanisms and reactions that take place within the fuel cell. The work presented in this thesis describes a procedure for utilizing computer modeling to create high quality fuel cell simulations using Ansys Fluent 12.1. Methods for creating computer aided design (CAD) models of fuel cells are discussed. Detailed simulation parameters are described and emphasis is placed on establishing convergence criteria which are essential for producing consistent results. A mesh sensitivity study of the catalyst and membrane layers is presented showing the importance of adhering to strictly defined convergence criteria. A study of iteration sensitivity of the simulation at low and high current densities is performed which demonstrates the variance in the rate of convergence and the absolute difference between solution values derived at low numbers of iterations and high numbers of iterations. / Dissertation/Thesis / M.S.Tech Chemistry 2011

abstract: This work investigates in-situ stress evolution of interfacial and bulk processes in electrochemical systems, and is divided into two projects. The first project examines the electrocapillarity of clean and CO-covered electrodes. It also investigates surface stress evolution during electro-oxidation of CO at Pt{111}, Ru/Pt{111} and Ru{0001} electrodes. The second project explores the evolution of bulk stress that occurs during intercalation (extraction) of lithium (Li) and formation of a solid electrolyte interphase during electrochemical reduction (oxidation) of Li at graphitic electrodes. Electrocapillarity measurements have shown that hydrogen and hydroxide adsorption are compressive on Pt{111}, Ru/Pt{111}, and Ru{0001}. The adsorption-induced surface stresses correlate strongly with adsorption charge. Electrocatalytic oxidation of CO on Pt{111} and Ru/Pt{111} gives a tensile surface stress. A numerical method was developed to separate both current and stress into background and active components. Applying this model to the CO oxidation signal on Ru{0001} gives a tensile surface stress and elucidates the rate limiting steps on all three electrodes. The enhanced catalysis of Ru/Pt{111} is confirmed to be bi-functional in nature: Ru provides adsorbed hydroxide to Pt allowing for rapid CO oxidation. The majority of Li-ion batteries have anodes consisting of graphite particles with polyvinylidene fluoride (PVDF) as binder. Intercalation of Li into graphite occurs in stages and produces anisotropic strains. As batteries have a fixed size and shape these strains are converted into mechanical stresses. Conventionally staging phenomena has been observed with X-ray diffraction and collaborated electrochemically with the potential. Work herein shows that staging is also clearly observed in stress. The Li staging potentials as measured by differential chronopotentiometry and stress are nearly identical. Relative peak heights of Li staging, as measured by these two techniques, are similar during reduction, but differ during oxidation due to non-linear stress relaxation phenomena. This stress relaxation appears to be due to homogenization of Li within graphite particles rather than viscous flow of the binder. The first Li reduction wave occurs simultaneously with formation of a passivating layer known as the solid electrolyte interphase (SEI). Preliminary experiments have shown the stress of SEI formation to be tensile (~+1.5 MPa). / Dissertation/Thesis / Deconvolution programm - see Appendix C / ECdata4 program - see Appendix C / Ph.D. Materials Science and Engineering 2011

abstract: Mechanisms for oxygen reduction are proposed for three distinct cases covering two ionic liquids of fundamentally different archetypes and almost thirty orders of magnitude of proton activity. Proton activity is treated both extrinsically by varying the concentration and intrinsically by selecting proton donors with a wide range of aqueous pKa values. The mechanism of oxygen reduction in ionic liquids is introduced by way of the protic ionic liquid (pIL) triethylammonium triflate (TEATf) which shares some similarities with aqueous acid solutions. Oxygen reduction in TEATf begins as the one electron rate limited step to form superoxide, O2*-, which is then rapidly protonated by the pIL cation forming the perhydroxyl radical, HO2*. The perhydroxyl radical is further reduced to peroxidate (HO2-) and hydrogen peroxide in proportions in accordance with their pKa. The reaction does not proceed beyond this point due to the adsorption of the conjugate base triethylammine interfering with the disproportionation of hydrogen peroxide. This work demonstrates that this mechanism is consistent across Pt, Au, Pd, and Ag electrodes. Two related sets of experiments were performed in the inherently aprotic ionic liquid 1-butyl-2,3-dimethylimidazolium triflate (C4dMImTf). The first involved the titration of acidic species of varying aqueous pKa into the IL while monitoring the extent of oxygen reduction as a function of pKa and potential on Pt and glassy carbon (GC) electrodes. These experiments confirmed the greater propensity of Pt to reduce oxygen by its immediate and abrupt transition from one electron reduction to four electron reduction, while oxygen reduction on GC gradually approaches four electron reduction as the potentials were driven more cathodic. The potential at which oxygen reduction initiates shows general agreement with the Nernst equation and the acid's tabulated aqueous pKa value, however at the extremely acidic end, a small deviation is observed. The second set of experiments in C4dMImTf solicited water as the proton donor for oxygen reduction in an approximation of the aqueous alkaline case. The water content was varied between extremely dry (<0.1 mol% H2O) and saturated (approximately 15.8 mol% H2O}). As the water content increased so too did the extent of oxygen reduction eventually approach two electrons on both Pt and GC. However, additional water led to a linear increase in the Tafel slope under enhanced mass transport conditions up to the point of 10 mol% water. This inhibition of oxygen adsorption is the result of the interaction between superoxide and water and more specifically is proposed to be associated with decomposition of theC4dMIm+ cation by hydroxide at the elevated temperatures required for the experiment. Oxygen reduction on both Pt and GC follows Nernstian behavior as the water content is increased. Separate mechanisms for oxygen reduction on Pt and GC are proposed based on the nature of the Nernstian response in these systems. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2011

Novel type of catalyst for proton exchange membrane fuel cells anode is demonstrated. It is based on magnetron sputtered Pt-CeO2 a Pt-Sn-CeO2 mixed oxides. It is shown, that these materials allow to significantly decrease amount of platinum in the anode catalyst. The preparation method yields high amount of platinum in ionized form, especially Pt2+ , which is related to the high activity. Stability of these catalytic layers were investigated under conditions similar to fuel cell anode (humidified hydrogen at elevated temperature). Also interaction of hydrogen a water under UHV conditions were studied, demonstrating high stability of the Pt2+ species. In the last part of the work sputtered Pt-Co mixed catalyst were investigated to be used in the PEMFC cathode. It is demonstrated that at right conditions, the sputtered alloy catalyst improves mass activity on cathode by factor more than two.

abstract: With a recent shift to a more environmentally conscious society, low-carbon and non-carbon producing energy production methods are being investigated and applied all over the world. Of these methods, fuel cells show great potential for clean energy production. A fuel cell is an electrochemical energy conversion device which directly converts chemical energy into electrical energy. Proton exchange membrane fuel cells (PEMFCs) are a highly researched energy source for automotive and stationary power applications. In order to produce the power required to meet Department of Energy requirements, platinum (Pt) must be used as a catalyst material in PEMFCs. Platinum, however, is very expensive and extensive research is being conducted to develop ways to reduce the amount of platinum used in PEMFCs. In the current study, three catalyst synthesis techniques were investigated and evaluated on their effectiveness to produce platinum-on copper (Pt@Cu) core-shell nanocatalyst on multi-walled carbon nanotube (MWCNT) support material. These three methods were direct deposition method, two-phase surfactant method, and single-phase surfactant method, in which direct deposition did not use a surfactant for particle size control and the surfactant methods did. The catalyst materials synthesized were evaluated by visual inspection and fuel cell performance. Samples which produced high fuel cell power output were evaluated using transmission electron microscopy (TEM) imaging. After evaluation, it was concluded that the direct deposition technique was effective in synthesizing Pt@Cu core-shell nanocatalyst on MWCNTs support when a rinsing process was used before adding platinum. The peak power density achieved by the rinsed core-shell catalyst was 618 mW.cm-2 , 13 percent greater than that of commercial platinum-carbon (Pt/C) catalyst. Transmission electron microscopy imaging revealed the core-shell catalyst contained Pt shells and platinum-copper alloy cores. Rinsing with deionized (DI) water was shown to be a crucial step in core-shell catalyst deposition as it reduced the number of platinum colloids on the carbon nanotube surface. After evaluation, it was concluded that the two-phase surfactant and single-phase surfactant synthesis methods were not effective at producing core-shell nanocatalyst with the parameters investigated. / Dissertation/Thesis / M.S.Tech Technology 2012

L'utilisation de pile à combustible à bord d'un avion impose d'extraire des espèces légères (telles que l'hydrogène et les hydrocarbures légers) du combustible liquide qui est stocké et utilisé, éventuellement à des températures où se produit une pyrolyse du carburant. La porosité d’un matériau composite pourrait être utilisée pour filtrer les espèces sélectionnées. L'efficacité de séparation d’un matériau poreux dépend de deux facteurs qui sont: la perméance et la sélectivité.Ces facteurs sont souvent déterminés avec une configuration classique utilisant un échantillon en forme d’un disque d’un matériau poreux. Cependant, cette configuration est loin de la réalité qui est composée de tubes. Par conséquent, une étude est réalisée en considérant les deux configurations en utilisant différents types de disques poreux et un tube composite poreux. Ensuite, les résultats obtenus sont comparés et les différents facteurs affectant le processus de perméation sont étudiés.Après cela, un banc d'essai innovant est développé et utilisé afin de déterminer la distribution axiale des deux propriétés d'un tube poreux en acier inoxydable (c'est-à-dire la perméance et la sélectivité). Les effets des conditions opératoires (débit massique d'entrée et pression d'entrée) ont été étudiés. Une nouvelle forme radiale de l'équation de perméabilité aux gaz a été développée pour ce travail et sa relation avec la perméabilité de Darcy est établie. La variation de pression le long de l'axe central du tube est déterminée. Les effets de cette variation de pression sur les propriétés physiques des gaz tels que la densité et la viscosité sont déterminés et leur influence sur la sélectivité est étudiée en utilisant différents gaz tels que l'azote, le dioxyde de carbone, le méthane et l'hélium.Plus tard, un mélange binaire de dioxyde de carbone (CO2) et d'Azote (N2) est considéré sous trois compositions volumétriques différentes (50/50%, 60/40% et 70/30%) afin d'évaluer la propriété de séparation de gaz d’un tube poreux (effet de membrane). La perméabilité au gaz pur, la perméabilité du mélange, la sélectivité idéale et la sélectivité de séparation de ce tube sont déterminées pour un débit massique et une pression d'entrée différents. Les facteurs affectant les distributions de CO2 et de N2 à l'intérieur du tube poreux sont étudiés.Les résultats obtenus peuvent être utiles pour comprendre les facteurs affectant la séparation des gaz dans le cas d'un tube poreux pour des processus industriels continus. / Using Fuel Cell on board of aircraft imposes to extract light species (such as Hydrogen and light hydrocarbons) from the liquid fuel which is stored and used, possibly at temperatures where a fuel pyrolysis occurs. Porosity of a composite material could be used to filtrate the selected species. The separation efficiency of a porous material depends upon two factors which are: Permeance and Selectivity.These factors are often determined with a classical configuration using a porous disk sample. However, this configuration is far from the realistic one consisting of tubes. Therefore, a study is performed considering both configurations using different types of porous disks and a porous composite tube. Then, the obtained results are compared and the different factors affecting the permeation process are studied.After that, an innovative permselectivity test bench is developed and used in order to determine the axial distribution of the two properties of a stainless steel porous tube (i.e. permeance and selectivity). The effects of the operating conditions (inlet mass flowrate and inlet pressure) have been studied. A new radial form of the gas permeability equation has been developed for this work and its relationship with Darcy‘s permeability is established. The pressure variation along the centre axis of the tube is determined. The effects of this pressure variation on the physical properties of gases such as density and viscosity are determined and their influence on the selectivity is studied using different gases such as Nitrogen, Carbon dioxide, Methane, and Helium. Later, a binary mixture of Carbon Dioxide (CO2) and of Nitrogen (N2) is considered under three different volumetric compositions (50/50%, 60/40% and 70/30%) in order to evaluate the separation property of the porous stainless steel tube (membrane effect). The pure gas permeability, the mixture permeability, the ideal selectivity and the separation selectivity of this tube are determined for a different mass flowrate and inlet pressure. The factors affecting the distributions of CO2 and N2 inside the porous tube are investigated. The obtained results can be useful to understand the factors affecting gas separation in case of a porous tube for continuous industrial processes

139 f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-03-22T17:52:48Z No. of bitstreams: 1 Efeito do lantânio nas propriedades de catalisadores de cobre, cério e zircônio, na reação de PROX.pdf: 1865766 bytes, checksum: fc63e93a913ab80e690a741cf6ea78bd (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-06-05T17:31:16Z (GMT) No. of bitstreams: 1 Efeito do lantânio nas propriedades de catalisadores de cobre, cério e zircônio, na reação de PROX.pdf: 1865766 bytes, checksum: fc63e93a913ab80e690a741cf6ea78bd (MD5) / Made available in DSpace on 2013-06-05T17:31:16Z (GMT). No. of bitstreams: 1 Efeito do lantânio nas propriedades de catalisadores de cobre, cério e zircônio, na reação de PROX.pdf: 1865766 bytes, checksum: fc63e93a913ab80e690a741cf6ea78bd (MD5) Previous issue date: 2012 / CAPES / Devido ao desenvolvimento das células a combustível de membrana trocadora de prótons (PEMFCs), abastecidas com hidrogênio, é necessário encontrar processos para a purificação desse gás. Os processos tradicionais de produção, como a reforma a vapor do gás natural, produzem misturas ricas em hidrogênio com quantidades baixas de monóxido de carbono (≈ 0,5-2,0%) que, no entanto, são suficientes para envenenar os eletrodos de platina das PEMFCs. A oxidação preferencial do monóxido de carbono em misturas ricas em hidrogênio (PROX) tem sido apontada como uma das rotas mais adequadas para a purificação de hidrogênio para células a combustível. Vários estudos têm mostrado que os catalisadores baseados em óxidos de cobre e cério ou óxidos de cobre, cério e zircônio, são altamente ativos e seletivos para a produção de dióxido de carbono na oxidação preferencial do monóxido de carbono. Outros estudos têm mostrado que a dopagem do óxido de cério ou do óxido de cério e zircônio com íons terras-raras, tal como o íon La3+, produz sólidos com área superficial específica e capacidade de estocagem de oxigênio mais elevadas. Com o objetivo de encontrar catalisadores mais eficientes para a reação de PROX, neste trabalho estudou-se o efeito do lantânio sobre as propriedades de catalisadores baseados em cobre, cério e zircônio, concentrando-se no aumento da área superficial específica e da capacidade de estocagem de oxigênio. Foram preparados catalisadores baseados em cobre, cério e lantânio (CuO-Ce1-xLaxO2-x/2), bem como cobre, cério, zircônio e lantânio (CuO-Ce0,5-x/2Zr0,5-x/2LaxO2-x/2), com composições diferentes (x = 0,0; 0,05; 0,10; 0,15; 0,20), 6 % em massa de Cu, além de catalisadores isentos de cério (CuO-ZrO2 e CuO-La2O3), para comparação, através de precipitação simultânea utilizando hidróxido de potássio como agente precipitante. As amostras foram caracterizadas por análise química elementar, termogravimetria, espectroscopia no infravermelho com transformada de Fourier, difração de raios X, medidas de área superficial específica, redução à temperatura programada, medidas de capacidade de estocagem de oxigênio e troca isotópica com oxigênio-18 (18O2). Os catalisadores foram avaliados na oxidação preferencial do monóxido de carbono na faixa de 150 a 300 °C. Observou-se que a adição de lantânio aumenta a área superficial específica dos catalisadores, devido à diminuição do tamanho médio de cristal, no caso dos catalisadores isentos de zircônio e, provavelmente, devido a um aumento da porosidade, no caso dos catalisadores contendo zircônio. Além disso, verificou-se que pequenas quantidades de lantânio aumentam a capacidade de estocagem de oxigênio dos sólidos e aumentam a mobilidade do oxigênio. No entanto, a adição de lantânio não melhora o desempenho dos catalisadores na oxidação preferencial do monóxido de carbono, um fato que foi relacionado com a diminuição do teor de cério nos catalisadores à medida que o teor de lantânio é aumentado. Isto pode ser relacionado com a interface entre as partículas de óxido de cobre e óxido de cério, onde ocorre a reação, que diminui à medida que aumenta a quantidade de lantânio nos catalisadores. Além disso, a adição de 10 % de dióxido de carbono, durante a reação a 150 °C, diminui a atividade dos catalisadores, o que foi atribuído à quimissorção do dióxido de carbono no óxido de cério. Por outro lado, a adição de 2 % de água não altera significativamente a atividade ou a seletividade dos catalisadores testados. O catalisador baseado em cobre, cério e zircônio, isento de lantânio, foi o mais ativo e seletivo. / Salvador

Addressing the low power generation of anodic biocatalysts is pertinent to the advancement of microbial fuel cell technology. While Propionibacterium freudenreichii ssp. shermanii has shown potential as a biocatalyst, its incomplete consumption of the anodic substrate is a persistent issue. This research aims to optimize substrate consumption to increase power generation using Propionibacterium freudenreichii ssp. shermanii as a biocatalyst. The effect of coculturing Geobacter sulfurreducens with Propionibacterium freudenreichii ssp. shermanii was investigated. The cocatalyst and pure culture performance was tested in an air-cathode microbial fuel cell. Geobacter sulfurreducens produced the highest maximum power density among the experimental cases. Power density produced by Propionibacterium freudenreichii ssp. shermanii was improved in the air-cathode design compared to previous experiments performed in an H-type design. The novel cocatalyst was shown to produce electricity, however a full characterization to elucidate the contribution to power generation by each microbe would be desirable to investigate.

Membranas à base de polímeros perfluorosulfonados, como a Nafion, vêm sendo extensivamente usadas como membrana de troca protônica em células a combustível (FC). O objetivo deste trabalho foi desenvolver membranas eletrólito à base de polindeno sulfonado (SPInd) e poli(fluoreto de vinilideno) (PVDF), para uso como membranas de troca protônica em condições semelhantes às da membrana Nafion. As membranas foram preparadas por casting em diferentes composições utilizando PVDF como reforço mecânico e PVDF sulfonado (SPVDF) como agente compatibilizante. Todas as membranas foram avaliadas por análise termogravimétrica, calorimetria exploratória diferencial, análise dinâmico mecânica, microscopia eletrônica de varredura, grau de inchamento, capacidade de troca iônica e espectroscopia de impedância eletroquímica. As membranas com características semelhantes à membrana Nafion foram avaliadas em protótipo de FC a 80 °C. A membrana SPInd50/PVDF e as membranas com agente compatibilizante apresentaram condutividades iônicas na ordem de 10-2 S/cm, comparáveis àquela da membrana Nafion. A membrana com melhor desempenho em protótipo de FC foi o SPInd/PVDFC12, preparado com 50% de SPInd, 47,5% de PVDF e 2,5% de SPVDF (p/p), cujos valores de potencial de circuito aberto e densidade de potência máximo foram de 1,02 V e 74,54 mW/cm2, respectivamente. Apesar da densidade de potência máxima ser inferior à da membrana Nafion (603 mW/cm2), a membrana SPInd/PVDFC12 apresenta potencial para uso como eletrólito em célula a combustível. / Perfluorosulfonic acid ionomer membranes, e.g. Nafion, have been extensively used as proton exchange membranes in fuel cells (FC) due to their high proton conductivity and good mechanical properties. The aim of this work was to develop electrolyte membranes based on sulfonated polyindene (SPInd) and poly(vinylidene fluoride) (PVDF) to be used in the same conditions as Nafion. Membranes were prepared by casting with different compositions using PVDF as mechanical reinforcement and sulfonated PVDF (SPVDF) as coupling agent. The produced membranes were evaluated by thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis, scanning electron microscopy, water uptake, ion exchange capacity and electrochemical impedance spectroscopy. The membranes with similar results to Nafion, were evaluated in a FC prototype at 80 °C. The membrane SPInd50/PVDF and all the membranes with coupling agent had ionic conductivity in the order of 10-2 S/cm, comparable to the Nafion´s. The polyelectrolyte with the best performance was the SPInd/PVDFC12 which was prepared with 50 wt% SPInd, 47.5 wt% PVDF and 2.5 wt% SPVDF, that reached an open circuit voltage of 1.02 V and maximum power density of 74.54 mW/cm2. Even though Nafion´s maximum power density was higher (603 mW/cm2), the SPInd/PVDFC12 membrane showed potential to be used as electrolyte in fuel cells.