Dissertations / Theses: 'Regenerative fuel cell'

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Tan, Chiuan Chorng. "A new concept of regenerative proton exchange membrane fuel cell (R-‐PEMFC)." Thesis, La Réunion, 2015. http://www.theses.fr/2015LARE0012.

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Les travaux précédents trouvés dans la littérature ont mis l'importance sur la pile à combustible PEM ou électrolyseur PEM. Certains articles ont étudié également la pile à combustible réversible et le système d'alimentation en hydrogène par énergie solaire en intégrant à la fois la pile à combustible et électrolyseur. Contrairement à un « Unitised regenerative fuel cell (URFC)», notre conception a un compartiment individuel pour chaque système de PEM-Fuel Cell et d'electrolyseur-PEM et nommé Quasi - URFC. Grâce à ce nouveau concept, l'objectif principal est de réduire le coût de la pile à combustible régénératrice (RFC) en minimisant le rapport de surface superficielle géométrique du catalyseur de l'assemblage membrane électrodes (AME) des deux modes dans la cellule. D'ailleurs, nous visons également à construire un RFC plus compact, léger et portable par rapport à une pile à combustible ou l'électrolyseur classique. Ce travail de recherche est divisé en trois parties : la modélisation et simulation numérique, l'assemblage du prototype et le travail d'expérimentation. Quant à la partie de modélisation, un modèle physique multi-2D a été développé dans le but d'analyser les performances d'une pile à combustible à régénérée à trois-compartiments, qui se compose d'une piles à combustible et d'électrolyseur. Ce modèle numérique est basée sur la résolution des équations de conservation de masse, du momentum, des espèces et du courant électrique en utilisant une approche par éléments finis sur des grilles 2D . Les simulations permettent le calcul de la vitesse, de la concentration de gaz, la densité de courant et les distributions de potentiels en mode pile à combustible et en mode d'électrolyse, ainsi nous aider à prédire le comportement de quasi - RFC. En outre, l'assemblage du premier prototype du nouveau concept de pile à combustible à combustible régénérée a été achevée et testée au cours des trois années d'études dans le cadre d'une thèse. Les résultats expérimentaux de la 3 Compartiments R-PEMFC ont été prometteurs dans les deux modes, soit en mode piles à combustible et soit en mode d'électrolyseur. Ces résultats valideront ensuite les résultats de la simulation, obtenus auparavant par la modélisation
The past works found in the literature have focused on either PEM fuel cell or electrolyzer-PEM. Some of the papers even studied the unitised reversible regenerative fuel cell (URFC) and the solar power hydrogen system by integrating both fuel cell and electrolyzer. Unlike the URFC, our design has an individual compartment for each PEMFC and E-PEM systems and named Quasi-URFC. With this new concept, the main objective is to reduce the cost of regenerative fuel cell (RFC) by minimizing the ratio of the catalyst’s geometric surface area of the membrane electrode assembly (MEA) of both cell modes. Apart from that, we also aim to build a compact, light and portable RFC.This research work is divided into three parts: the modeling, assembly of the prototype and the experimentation work. As for the modeling part, a 2D multi-physics model has been developed in order to analyze the performance of a three chamber-regenerative fuel cell, which consists of both fuel cell and electrolyzer systems. This numerical model is based on solving conservation equations of mass, momentum, species and electric current by using a finite-element approach on 2D grids. Simulations allow the calculation of velocity, gas concentration, current density and potential's distributions in fuel cell mode and electrolysis mode, thus help us to predict the behavior of Quasi-RFC. Besides that, the assembly of the first prototype of the new concept of regenerative fuel cell has been completed and tested during the three years of PhD studies. The experimental results of the Three-Chamber RFC are promising in both fuel cell and electrolyzer modes and validate the simulation results that previously obtained by modeling

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Ito, Hiroshi. "Electrochemical studies for the development of Li-H2 thermally regenerative fuel cell." Kyoto University, 2004. http://hdl.handle.net/2433/147426.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(エネルギー科学)
甲第10980号
エネ博第91号
新制||エネ||25(附属図書館)
UT51-2004-G827
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授伊藤靖彦, 教授尾形幸生, 教授片桐晃
学位規則第4条第1項該当

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Najmi, Hussain. "Selectivity of Porous Composite Materials for Multispecies mixtures : Application to Fuel Cells." Thesis, Bourges, INSA Centre Val de Loire, 2018. http://www.theses.fr/2018ISAB0001/document.

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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

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Martino, Drew J. "Evaluation of Electrochemical Storage Systems for Higher Efficiency and Energy Density." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/470.

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Lack of energy storage is a key issue in the development of renewable energy sources. Most renewables, especially solar and wind, when used alone, cannot sustain a reliably constant power output over an extended period of time. These sources generally generate variable amounts of power intermittently, therefore, an efficient electrical energy storage (EES) method is required to better temporally balance power generation to power consumption. One of the more promising methods of electrical energy storage is the unitized regenerative fuel cell (UFRC.) UFRCs are fuel cells that can operate in a charge-discharge cycle, similar to a battery, to store and then to subsequently release power. Power is stored by means of electrolysis while the products of this electrolysis reaction can be recombined as in a normal fuel cell to release the stored power. A major advantage of UFRCs over batteries is that storage capacity can be decoupled from cell power, thus reducing the potential cost and weight of the cell unit. Here we investigate UFRCs based on hydrogen-halogen systems, specifically hydrogen-bromine, which has potential for improved electrode reaction kinetics and hence cheaper catalysts and higher efficiency and energy density. A mathematical model has been developed to analyze this system and determine cell behavior and cycle efficiency under various conditions. The conventional H2-Br2 URFCs, however also so far have utilized Pt catalysts and Nafion membranes. Consequently, a goal of this work was to explore alternate schemes and materials for the H2-Br2 URFC. Thus, three generations of test cells have been created. The first two cells were designed to use a molten bromide salt, ionic liquid or anion exchange membrane as the ion exchange electrolyte with the liquids supported on a porous membrane. This type of system provides the potential to reduce the amount of precious metal catalyst required, or possibly eliminate it altogether. Each cell showed improvement over the previous generation, although the results are preliminary. The final set of results are promising for anion exchange membranes on a cost basis compared Nafion. Another promising energy storage solution involves liquid methanol as an intermediate or as a hydrogen carrier. An alternative to storing high-pressure hydrogen is to produce it on-board/on-site on demand via a methanol electrocatalytic reformer (eCRef), a PEM electrolyzer in which methanol-water coelectrolysis takes place. Methanol handling, storage, and transportation is much easier than that for hydrogen. The hydrogen produced via methanol eCref may then be used in any number of applications, including for energy storage and generation in a standard H2-O2 PEM fuel cell. The mathematical modeling and analysis for an eCref is very similar to that of the HBr URFC. In this work, a comprehensive model for the coelectrolysis of methanol and water into hydrogen is created and compared with experimental data. The performance of the methanol electrolyzer coupled with a H2-O2 fuel cell is then compared for efficiency to that of a direct methanol fuel cell data and was found to be superior. The results suggest that an efficient and small paired eCRef-fuel cell system is potentially be a cheaper and more viable alternative to the standard direct methanol fuel cell. Both the H2-Br2 URFC and the methanol eCref in combination with a H2-O2 fuel cell have significant potential to provide higher energy efficiency and energy density for EES purposes.

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Vassallo, Joseph. "Multilevel converters for regenerative fuel-cells." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420375.

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Doddathimmaiah, Arun Kumar, and arun doddathimmaiah@rmit edu au. "Unitised Regenerative Fuel Cells in Solar - Hydrogen Systems for Remote Area Power Supply." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081128.140252.

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Remote area power supply (RAPS) is a potential early market for renewable energy - hydrogen systems because of the relatively high costs of conventional energy sources in remote regions. Solar-hydrogen RAPS systems commonly employ photovoltaic panels, a Proton Exchange Membrane (PEM) electrolyser, a storage for hydrogen gas, and a PEM fuel cell. Unitised Regenerative Fuel Cells (URFCs) use the same hardware for both electrolyser and fuel cell functions. Since both of these functions are not required simultaneously in a solar hydrogen RAPS system, URFCs based on PEM technology provide a promising opportunity for reducing the cost of the hydrogen subsystem used in renewable-energy hydrogen systems for RAPS. URFCs also have potential applications in the areas of aerospace, submarines, energy storage for central grids, and hydrogen cars. In this thesis, a general theoretical relationship between cell potential and current density of a single-cell PEM URFC operating in both fuel-cell (FC) and electrolyser (E) modes is developed using modified Butler-Volmer equations for both oxygen- and hydrogen-electrodes, and accounting for mass transport losses and saturation behaviour in both modes, membrane resistance to proton current, and membrane and electrode resistances to electron current. This theoretical relationship is used to construct a computer model based on Excel and Visual Basic to generate voltage-current (V-I) polarisation curves in both E and FC modes for URFCs with a range of membrane electrode assembly characteristics. The model is used to investigate the influence on polarisation curves of varying key parameters such charge transfer coefficients, exchange current densities, saturation currents, and membrane conductivity. A method for using the model to obtain best-fit values for electrode characteristics corresponding to an experime ntally-measured polarisation curve of a URFC is presented. The experimental component of the thesis has involved the design and construction of single PEM URFCs with an active area of 5 cm2 with a number of different catalyst types and loadings. V-I curves for all these cells have been measured and the performance of the cells compared. The computer model has then been used to obtain best-fit values for the electrode characteristics for the URFCs with single catalyst materials active in each mode on each electrode for the corresponding experimentally-measured V-I curves. Generally values have been found for exchange current densities, charge transfer coefficients, and saturation current densities that give a close fit between the empirical and theoretically-generated curves. The values found conform well to expectations based on the catalyst loadings, in partial confirmation of the validity of the modelling approach. The model thus promises to be a useful tool in identifying electrodes with materials and structures, together with optimal catalyst types and loadings that will improve URFC performance. Finally the role URFCs can play in developing cost-competitive solar- hydrogen RAPS systems is discussed, and some future directions for future URFC research and development are identified.

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Wojnar, Olek. "Analyzing carbohydrate-based regenerative fuel cells as a power source for unmanned aerial vehicles." Wright-Patterson AFB : Air Force Institute of Technology, 2008. http://handle.dtic.mil/100.2/ADA480693.

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Thesis (M.S. in Aeronautical Engineering) --Air Force Institute of Technology, 2008.
Title from title page of PDF document (viewed on Aug 8, 2008). "AFIT/GAE/ENY/08-M31" Includes bibliographical references.

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Kumar, Kavita. "Catalyseurs sans métaux nobles pour pile à combustible régénérative." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2284/document.

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Le dihydrogène (H2) se présente comme le futur vecteur énergétique pour une économie basée sur des ressources propres et respectueuses de l'environnement. Il est le combustible idéal de la pile à combustible régénérative constituée de deux entités : un électrolyseur pour sa production, et une pile à combustible pour sa conversion directe en énergie électrique. Ce système présente l'avantage d'être compact et autonome. Cependant, l'amélioration de l'activité catalytique des matériaux, leur stabilité et l'élimination de métaux nobles dans leur composition sont nécessaires. Des catalyseurs bifonctionnels à base de métaux de transition associés au graphène ont alors été synthétisés. L'interaction oxyde-graphène a été étudiée sur un catalyseur Co3O4/NRGO. À faible teneur en cobalt, l'interaction entre les atomes de cobalt de l'oxyde et les atomes d'azote greffés sur les plans de graphène a été observée par voltammétrie cyclique. Cette interaction est responsable d'une diminution de la taille des nanoparticules de cobaltite et de l'activité de celles-ci vis-à-vis de la réaction de réduction du dioxygène (RRO). La substitution du cobalt par le nickel dans des structures de type spinelle (NiCo2O4/RGO) obtenu par voie solvothermale, a permis d'améliorer les performances électrocatalytiques vis-à-vis de la RRO et de la RDO. Ce matériau et un autre de type Fe-N-C préparé en collaboration avec un laboratoire de l'Université Technique de Berlin ont servi de cathode dans des études préliminaires réalisées en configuration pile à combustible alcaline à membrane échangeuse d'anion (SAFC)
Hydrogen, as an environmentally friendly future energy vector, is a non-toxic and convenient molecule for regenerative fuel cell, which connects two different technologies: an electrolyzer for H2 production, and a fuel cell for its direct conversion to electric energy. This kind of system possesses many advantages, such as lightness, compactness and more autonomy. However, improvement of activity and durability of electrode materials free from noble metals in their composition is needed. Thereby, bifunctional catalysts composed of transition metals deposited onto graphene-based materials were synthesized. The interaction between the metal atom of the oxide and the graphene doped heteroatom in the Co3O4/NRGO catalyst was investigated physicochemically. With a low cobalt loading, the interaction between cobalt and nitrogen was characterized by cyclic voltammetry, which revealed that it was responsible for decreasing the oxide nanoparticle size, as well as increasing the material activity towards the oxygen reduction reaction (ORR). The substitution of Co by Ni in the spinel structure (NiCo2O4/RGO) obtained by solvothermal synthesis, allowed the enhancement of the electrocatalytic performances towards the ORR and OER. Moreover, this catalyst as well as another material prepared in collaborative program with a lab from Technical University of Berlin were used as cathode in preliminary studies undertaken on solid alkaline fuel cell (SAFC)

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Hosseini-Benhangi, Pooya. "Bifunctional oxygen reduction/evolution catalysts for rechargeable metal-air batteries and regenerative alkaline fuel cells." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60227.

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The electrocatalysis of oxygen reduction and evolution reactions (ORR and OER, respectively) on the same catalyst surface is among the long-standing challenges in electrochemistry with paramount significance for a variety of electrochemical systems including regenerative fuel cells and rechargeable metal-air batteries. Non-precious group metals (non-PGMs) and their oxides, such as manganese oxides, are the alternative cost-effective solutions for the next generation of high-performance bifunctional oxygen catalyst materials. Here, initial stage electrocatalytic activity and long-term durability of four non-PGM oxides and their combinations, i.e. MnO₂, perovskites (LaCoO₃ and LaNiO₃) and fluorite-type oxide (Nd₃IrO₇), were investigated for ORR and OER in alkaline media. The combination of structurally diverse oxides revealed synergistic catalytic effect by improved bifunctional activity compared to the individual oxide components. Next, the novel role of alkali-metal ion insertion and the mechanism involved for performance promotion of oxide catalysts were investigated. Potassium insertion in the oxide structures enhanced both ORR and OER performances, e.g. 110 and 75 mV decrease in the OER (5 mAcm-²) and ORR (-2 mAcm-²) overpotentials (in absolute values) of MnO₂-LaCoO₃, respectively, during galvanostatic polarization tests. In addition, the stability of K⁺ activated catalysts was improved compared to unactivated samples. Further, a factorial design study has been performed to find an active nanostructured manganese oxide for both ORR and OER, synthesized via a surfactant-assisted anodic electrodeposition method. Two-hour-long galvanostatic polarization at 5 mAcm-² showed the lowest OER degradation rate of 5 mVh-¹ for the electrodeposited MnOx with 270 mV lower OER overpotential compared to the commercial γ-MnO₂ electrode. Lastly, the effect of carbon addition to the catalyst layer, e.g. Vulcan XC-72, carbon nanotubes and graphene-based materials, was examined on the ORR/OER bifunctional activity and durability of MnO₂ LaCoO₃. The highest ORR and OER mass activities of -6.7 and 15.5 Ag-¹ at 850 and 1650 mVRHE, respectively, were achieved for MnO₂-LaCoO₃-multi_walled_carbon_nanotube-graphene, outperforming a commercial Pt electrode. The factors affecting the durability of mixed-oxide catalysts were discussed, mainly attributing the performance degradation to Mn valence changes during ORR/OER. A wide range of surface analyses were employed to support the presented electrochemical results as well as the proposed mechanisms.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

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Jamal, Al-Maleek. "Studies of pancreatic islet plasticity : a new paradigm in tissue regeneration." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85920.

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The morphogenetic plasticity of adult pancreatic islets of Langerhans has been implicated in the development of pancreatic adenocarcinomas and in islet transplant failure. The objective of this doctoral work was to investigate the extent of this plasticity and to characterize the unknown cell types and intracellular mechanisms involved in changes of adult islet phenotype.
In the first published study, isolated adult canine islets were induced to undergo a phenotypic switch into highly proliferative duct-like structures through a two-stage process entailing beta-cell death and the dedifferentiation of the resulting cells. The transformed islets were no longer immunoreactive for islet cell hormones, but now expressed markers of pancreatic duct epithelial cells. Pharmacologic inhibition of signal transduction demonstrated that the balance in signalling activity between ERK/Akt and JNK/caspase-3 appears to be an important regulator of islet cell death and differentiation.
In the second published study, quiescent adult human islets were induced to undergo a similar phenotypic switch into highly proliferative duct-like structures in a process that implicated glucagon- and somatostatin-expressing cells, and was characterized by a loss of expression of islet-specific hormones and transcription factors as well as a temporally-related rise in expression of markers of stermness and duct epithelium. Short-term treatment of these primitive duct-like structures with the islet neogenic factor INGAP 104-118 induced their scalable reversion back to islet-like structures in a P13-kinase-dependent manner. These neoislets resembled freshly isolated human islets with respect to the presence and topological arrangement of the four endocrine cell-types, islet gene expression and hormone production, insulin content and glucose-responsive insulin secretion. The demonstration that adult human islets are able to regenerate themselves establishes a new paradigm in the context of tissue regeneration and diabetes therapy.
These original findings may have important clinical implications for understanding and controlling pancreatic carcinogenesis and islet neogenesis in the adult human pancreas.

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Luo, Jun 1969. "Marrow stromal cells for myocardial regeneration." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84055.

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Normal bone marrow is composed of hematopoietic and non-hematopoietic cells. The later have also been termed stromal cells or mesenchymal cells. These cells were originally thought to provide an appropriate matrix for hematopoietic cell development, but recent examination of these cell populations suggests a much broader spectrum of activity, including the generation of bone, cartilage, tendon, fat and muscles including myocardium.
Cellular cardiomyoplasty (CCM) based on adult bone marrow stromal cells (MSCs) is a novel means of augmenting cardiomyocyte number and contractile function of the failing heart targeting the basic pathophysiology of heart failure.
Chapter I of this thesis briefly reviews the therapy of congestive heart failure and cellular cardiomyoplasty based on MSCs. The concept of MSCs for cardiomyoplasty and previous work conducted in our laboratory will be reviewed. Chapter II focuses on the fate of systemically implanted MSCs, in order to examine whether MSCs may participate in myocardial growth and injury in the post-natal immature hearts.
With the purpose of searching for universal donors for clinical application of MSC cardiomyoplasty, in chapter III we use a vast histocompatibility mismatch pig-to-rat model to examine the unique immune tolerance of MSCs. Chapter IV consists of closing remarks.

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Atoui, Rony R. "Marrow stromal cells as "universal donor cells" for myocardial regenerative therapy." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101837.

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Background. Recently rodent and porcine bone marrow stromal cells (MSCs) have been reported to be uniquely immune tolerant. In order to confirm these findings in human cells, we tested the hypothesis that human MSCs are also immune tolerant, such that they can be useful as "universal donor cells" for myocardial regenerative therapy.
Methods. Immunocompetent female rats underwent left coronary ligations (n=90). They were randomized into 3 groups. In Group I, lac-Z labeled male human MSCs were implanted into the peri-infarcted area. In Group II and III isogenic rat MSCs or culture medium were injected respectively. Echocardiography was carried out to assess cardiac function, and the specimens were examined serially for up to 8 weeks with immunohistochemistry, FISH and PCR to examine MSCs survival and differentiation.
Results. Human MSCs were found to survive within the rat myocardium without immunosuppression. This was confirmed by PCR and FISH test. No cellular infiltration characteristic of immune rejection was noted. Some of these cells appeared to express cardiomyocyte-specific markers such as troponin-Ic and connexin-43. Furthermore, the implanted MSCs significantly contributed to the improvement in ventricular function and attenuated LV remodeling.
Conclusions. Human MSC survived within this xenogeneic environment, and contributed to the improvement in cardiac function. Our findings support the feasibility of using these cells as "universal donor cells" for xeno- or allo-geneic cell therapy, as they can be tested, prepared and stored well in advance for urgent use. Allogeneic MSCs from healthy donors may be particularly useful for severely ill or elderly patients whose own MSCs could be dysfunctional.
Plusieurs études ont récemment démontré la tolérance immunologiquedes cellules souches stromales (CSS) issues de rongeurs et de porcinés. Pour confirmer cesrésultats chez les cellules humaines, l'étude actuelle évalue l'effet des CSS humaines sur larégénération du myocarde chez des rats immunocompétents et étudie la possibilité d'utiliserces CSS comme « donatrices universelles» à la suite d'un infarctus.

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Ong, Tone Stephan. "The diverse roles of collapsin response mediator protein 4 in mitosis and nerve regeneration." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103462.

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Microtubule-actin interactions underlie a diverse number of biological processes including cell motility, neuronal outgrowth, cellular wound healing, cell division and cortical flow. CRMPs (Collapsin Response Mediator Proteins) are a family of cytosolic phosphoproteins that play roles in regulating both actin and microtubule dynamics. The roles of the CRMP family of proteins in regulating these cellular processes have only been partially described. Our lab has been particularly interested in the function of the CRMP4 isoform because of its unique ability to complex with RhoA, a master regulator of the actin cytoskeleton. In this thesis we explore the function of CRMP4 in two biological processes that are dependent on actin and microtubule dynamics: mitosis (Chapter 2) and axon regeneration (Chapter 3 and 4). In Chapter 2, we identify CRMP4 as an important regulator of mitotic chromosomal alignment. We show that CRMP4 localizes to spindle microtubules during mitosis and that loss of CRMP4 disrupts chromosomal alignment, mitotic progression and spindle morphology. Furthermore, we demonstrate that these processes are dependent on CRMP4 phosphorylation, which may be important for recruitment of additional proteins to the mitotic machinery. In Chapter 3, we investigate the ability of an adeno-associated virus (AAV) encoding a CRMP4 antagonist C4RIP (CRMP4-RhoA inhibitory peptide) to enhance adult retinal ganglion cell (RGC) axon regeneration in an in vivo preclinical optic nerve injury model. We describe the inability of AAV-C4RIP to promote RGC regeneration and discuss the likelihood that AAV-mediated expression levels of C4RIP may be insufficient to promote regeneration. In Chapter 4, we describe the development and validation of cell permeable recombinant C4RIP (TAT-C4RIP) and discuss our data testing the effects of TAT-C4RIP on regeneration in vitro and in vivo. Together, these studies identify CRMP4 as an important regulator of mitosis, and describe our ongoing studies testing the effects of a CRMP4 antagonist on nerve regeneration.
Les interactions entre l'actine et les microtubules sont sous-jacentes à divers processus biologiques incluant la motilité cellulaire, le guidage neuronal, la cicatrisation cellulaire, la division cellulaire et la circulation corticale. Les protéines CRMPs (Collapsin Response Mediator Protein) sont une famille de phosphoprotéines cytosoliques jouant un rôle dans la régulation de la dynamique de l'actine et des microtubules. Cependant, cette régulation du cytosquelette par les CRMPs n'a été que partiellement décrite. Notre laboratoire s'intéresse à la fonction de l'isoforme CRMP4 en raison de sa capacité unique d'interagir avec RhoA, un régulateur important du cytosquelette d'actine. Dans cette thèse, nous explorons la fonction de CRMP4 dans deux processus biologiques qui dépendent de la dynamique de l'actine et des microtubules: la mitose (chapitre 2) et la régénération des axones (chapitre 3 et 4). Dans le chapitre 2 sera présentée notre identification de CRMP4 en tant que régulateur important de l'alignement chromosomique durant la mitose. Nous démontrons que, pendant la mitose, CRMP4 se situe sur les fuseaux mitotiques formés de microtubules et que la perte de CRMP4 perturbe l'alignement chromosomique, la progression de la mitose et la morphologie des fuseaux. En outre, nous démontrons que ces processus sont dépendants de la phosphorylation de CRMP4. Ceci pourrait être crucial pour le recrutement de protéines supplémentaires nécessaire pour la mitose. Dans le chapitre 3, nous étudions la capacité d'un virus adéno-associé (AAV) codant pour l'antagoniste de CRMP4, nommé C4RIP (CRMP4-RhoA inhibitory peptide), de favoriser la régénération de l'axone de cellules ganglionnaires de la rétine (RGC) chez l'adulte. Pour cela, nous utilisons un modèle in vivo de traumatismes du nerf optique chez le rat adulte. Nous décrivons l'incapacité des virus AAV-C4RIP de favoriser la régénération des RGCs et discutons de la probabilité que les niveaux de AAV-C4RIP exprimés puissent être insuffisants afin de favoriser la régénération. Le chapitre 4, quant à lui, est consacré à la description du développement et de la validation de la protéine recombinante TAT-C4RIP qui a le potentiel de traverser la membrane cellulaire. Nous y discutons les données concernant les effets de TAT-C4RIP sur la régénération in vitro et in vivo. Dans l'ensemble, ces études caractérisent CRMP4 comme important régulateur de la mitose et décrivent une nouvelle méthode de purification pour des protéines perméables à la membrane cellulaire.

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14

Zwimpfer, Thomas Joseph. "Regenerative synaptogenesis of retinal ganglion cell axons in non-retinal targets of the adult hamster." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39358.

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After optic nerve transection in the adult hamster (Carter et al., 1989) and rat (Vidal-Sanz et al., 1987), axons of retinal ganglion cells (RGCs) can regrow long distances through peripheral nerve (PN) grafts and form connections in the superior colliculus, a normal target of RGC axons. This thesis further investigated synaptogenesis in the injured mammalian CNS: regenerating RGC axons of adult hamsters were guided through PN grafts into two novel targets, the cerebellum (Cb) and the inferior colliculus (IC). When examined 2 to 9 months later, RGC axons were found to have extended into the grey matter of both targets for distances of up to 650 $ mu$m. Growth into white matter was rare and limited to 50 $ mu$m. RGC axons formed terminals and synapses in both targets. Within the Cb, there was a marked preference for growth and synapse formation in the granule cell layer (GCL) which could not be explained by: the position of the PN graft in the Cb, a selective denervation of the GCL, local damage to other neurons, or the distribution of reactive gliosis.
These anatomical studies indicate that regenerating CNS axons can form connections with novel targets in the adult hamster. The preferential synaptogenesis in the GCL of the Cb suggests that such connections are not formed randomly.

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Maria, Ola. "Identification and characterization of a cell source to regenerate salivary glands." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95118.

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Sjogren's syndrome and radiotherapy for head and neck cancer result in irreversible loss of functional salivary acini; known as xerostomia, for which no adequate treatment is available. Our group has been testing different biomaterials, extracellular matrix proteins, and graft cells for the development of an orally implantable tissue-engineered artificial salivary gland device. The major hurdle we faced was to find a suitable graft cell type that must establish tight junctions (TJs) and exhibit an adequate transepithelial electrical resistance (TER) in addition to being functional acinar secretory cells. Therefore, the aim of this thesis was to isolate and characterize a suitable graft cell type. We determined the distribution of TJ proteins in human salivary tissue to serve as a reference for future studies to assess the presence of appropriate TJ proteins in the graft cells we are looking for. We have found that claudin-1 was expressed in ductal and 25% of serous cells while claudin-2, -3, -4, JAM-A, occludin and ZO-1 were expressed in ductal and acinar cells. We characterized two candidate graft cells; human submandibular gland (HSG) cell line and primary human salivary gland (huSG) cells cultured individually on Matrigel (a basement membrane extract). Matrigel supported their morphogenesis and cytodifferentiation into 3-D polarized functional acinar units; expressing all TJ and acinar-specific proteins and exhibiting adequate TER. Thus, on Matrigel, both candidate cells showed ideal characteristics of suitable graft. However, neither Matrigel nor HSG would be used in clinical applications. Nevertheless, they would be implanted in animal models to further examine our envisioned artificial salivary gland device. Mesenchymal stem cells (MSCs) can differentiate into cells from all dermal lineages; carrying new promises and significant therapeutic implications. Importantly, MSCs have been isolated from different adult tissues including salivary glands, however; no
Le syndrome de Sjögren et la radiothérapie de la tête et du cou engendre une perte irréversible des acini salivaires fonctionnels: ce phénomène est la xérostomie, pour lequel aucun traitement adéquat n'existe actuellement. Notre groupe a testé différents biomatériaux, protéines de la matrice extracellulaire et des cellules de greffon pour le développement d'un dispositif tissulaire de glandes salivaires artificielles implantable oralement. L'obstacle majeur était de trouver un type cellulaire approprié pour la greffe qui devait établir des jonctions serrées (JSs), présenter une résistance électrique transépithéliale (RET) adéquate en plus se différencier en cellules acineuse sécrétrices fonctionnelles. Par conséquent, l'objectif de cette thèse a été d'isoler et de caractériser un type cellulaire approprié pour la greffe. Nous avons établi le paramètre de distribution des protéines de JSs dans les tissus salivaires de l'homme comme référence pour nos études suivantes dans le but d'évaluer la présence de protéines de JSs appropriées pour les cellules potentiellement destinées à la greffe. Nous avons déterminé que la claudine-1 est exprimée par les cellules ductales et par 25% des cellules séreuses alors que les claudines-2,3,4,occludin, JAM-A et ZO-1 sont exprimées par les cellules ductales et acineuses. Nous avons caractérisé deux types cellulaires candidats pour la greffe:la lignée cellulaire établie à partir des glandes humaines sous-mandibulaires (HGS) et des cellules primaires de glandes salivaires humaines (huGS) cultivées individuellement sur Matrigel. Matrigel permet leur morphogenèse et leur cytodifférenciation en unités acineuses 3-D polarisées et fonctionnelles, exprimant toutes les JSs, les protéines spécifiques des cellules acineuses et présentant une RET adéquate. Ainsi, sur Matrigel, les deux types cellulaires candidats ont montré des caractéristiques idéales pour une greffe approprié

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Srivastava, Sapna. "The potential of human adipose derived stem cells for myocardial regenerative therapy." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95088.

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Background: Cell therapy using Human Bone Marrow Stem Cells (HBMSCs) has been shown to improve heart function after a myocardial infarction. The harvesting technique involved with bone marrow stem cells is invasive and yields a low cell number. There is now an increasing interest in Human Adipose Derived Stem Cells (HADSCs) as they are abundant and readily accessible from liposuction material. The present study was undertaken to investigate if HADSCs are superior than HBMSCs in myocardial regenerative therapy. Results: Both HADSCs and HBMSCs proliferated in a time dependent manner, however, the proliferative ability of HADSC was greater than HBMSCs. In addition, both cells differentiated to the osteoblast lineage confirming their multipotency when treated with induction medium. Furthermore, treatment of both cells with 5-AC resulted in positive immunostaining of cardiac markers, troponinI and connexin 43, however the expression of these markers was enhanced in HADSCs. This was further confirmed by western blot analysis, however 5-AC treatment did not exhibit cell contraction or multinucleation. In addition, these results were further confirmed by our in vivo study. Both cells were injected in the heart of a rat model of myocardial infarction and was monitored for ejection fraction (EF) and fractional shortening (FS) for 24 hours, 3 weeks and 6 weeks post-surgery. The cardiac function of the rats treated with stem cells was improved as demonstrated by increase in EF and FS, however, a greater improvement was seen with HADSCs compared with HBMSCs. This notion is further substantiated by our studies on left ventricular infarct size measurement, showing that HADSC are more potent in reduction of the infarct compared to HBMSCs. Conclusion: The data suggest that HADSCs may prove to be a more ideal alternative for regenerative therapy in the future.
La thérapie cellulaire à l'aide de cellules souches humaines de la moelle osseuses (CSHMOs) a été démontré d'améliorer la fonction cardiaque après un infarctus du myocarde. La technique de récolte des CSHMOs est pourtant invasive et donne un nombre de cellules viables faible. Il y a maintenant un intérêt croissant dans les cellules souches humaines dérivés du tissu adipeux (CSHTAs), car elles sont abondantes et facilement accessibles à partir des amas de graisses provenant des chirurgies de liposuccion. La présente étude a été menée pour vérifier si les CSHTAs sont supérieures aux CSHMOs dans la thérapie régénératrice du myocarde. Résultats: Les CSHTAs ainsi que les CSHMOs ont proliféré dans une manière temps dépendante, cependant, la capacité proliférative des CSHTAs était supérieure à celle des CSHMOs. De plus, les deux types de cellules souches ce sont différenciées en lignée ostéoblastique, affirmant leur capacité multipotent lorsqu'elles sont traitées avec le milieu d'induction. En outre, le traitement des deux types de cellules souches avec le 5-AC a entraîné l'immunomarquage positif de troponin I et de connexine 43, marqueurs cardiaques, cependant l'expression de ces marqueurs était plus robuste dans les CSHTAs. Cela a été confirmé par analyse d'immunobuvardage de type Western, cependant les cellules traité au 5-AC ne présentait pas de contraction des cellules ou le développement de plusieurs noyaux. En plus, ces résultats ont été confirmés par nos études in vivo. Les deux types de cellules ont été injectées dans le cur d'un modèle de rat d'infarctus du myocarde et a été suivie pour la fraction d'éjection (FE) et la fraction de raccourcissement (FR) pour 24 heures, 3 semaines et 6 semaines post-chirurgie. La fonction cardiaque des rats traités avec les cellules souches a été améliorée, fait démontré par l'augmentation de l'FE et le FR, cependant, une plus grande amélioration de ce

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17

Ghali, Rodney. "Non-neuronal cell response to axonal damage in the visual paths of goldfish." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24005.

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Patterns of proliferation and changes in total cell number in the optic nerve, tract and tectum of goldfish have been examined following optic nerve crush or optic enucleation, using bromodeoxyuridine to label the proliferating cells. In general, an increase in proliferation and total cell number in all parts of the visual system was observed peaking between 7 and 14 days and resolving itself to normal or near normal levels by 32 days postoperative. Enucleation resulted in elevated proliferation values as compared to animals with an optic nerve crush, at least one early timepoint in each part of the visual system, but overall, there is little to suggest that axons are exerting a major effect on the cellular response. Finally, a seasonal effect on the proliferative response of non-neuronal cells and axonal regrowth has been demonstrated. Fish acclimatized under autumn-like conditions showed a faster initiation of the non-neuronal cell response and an enhanced rate of axonal regrowth when compared to fish acclimatized under spring-like conditions. It is believed that photoperiod plays a major role in the seasonal effects observed with temperature playing only a minor one.

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18

Houalla, Tarek. "Isolation of microglia from goldfish brain." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31238.

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This study aims at providing a new technique for the isolation and culture of goldfish microglial cells. So far no protocol has been designed for the growth of these cells in vitro, despite the growing interest in the remarkable capacity of goldfish central nervous system (CNS) for regenerating severed axons. This newly developed technique has little or no similarity to those used in the isolation of mammalian microglia, and is distinguished by its simple setup and its fast yield for microglial cells. In addition, a virtually pure population of microglia was generated when plated on untreated plastic dishes, eliminating further need for purification. This technique may thus provide a starting point for future characterization of the microglial cells in vitro, which may eventually help toward building a better understanding of the function and biology of these cells. A preliminary morphological characterization of the cells has also been conducted, in addition to groundwork experiments on the phagocytic activity of these cells in vitro, using myelin to stimulate phagocytosis. These assays were oriented toward providing a comparison to the mammalian cultures of microglia, and so far, displayed several similarities in morphologies and phagocytosis.

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Vidal-Sanz, Manuel. "Regenerative responses of injured adult rat retinal ganglion cells : axonal elongation, synapse formation and persistence of connections." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70180.

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To characterize the regenerative responses of adult mammalian central nervous system (CNS) neurons, their potential for axonal elongation, terminal growth, and synaptogenesis has been investigated in the retino-collicular system of the adult rat. For these studies, an experimental paradigm has been developed in the adult rat which consists of the total substitution of the optic nerve by an autologous segment of peripheral nerve (PN). The PN segment is used to promote axonal growth from axotomized retinal ganglion cells (RGCs) and to direct this growth towards the superior colliculus (SC), which is their main target in the normal CNS. In light and electron microscopic studies, after the application of retrogradely and orthogradely transported tracers and immunocytochemical markers, it has been documented that: (i) Up to 10% of the original RGC population can regenerate axons along these PN segments for distances that surpass those that separate the retina from the SC; (ii) Upon arrival at the interface created by the PN segment and the SC, some of the regenerated retinal axons extend and appear to arborize in the superficial layers of the SC for distances of approximately 500 $ mu$m; (iii) The retinal axons are capable of terminal differentiation and synapse formation in the SC, and; (iv) Re-formed axonal terminals, analyzed 16-18 months after connecting the retina to the SC, are not different from those observed in age-matched controls.

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FRANCO, EGBERTO G. "Desenvolvimento de novos eletrocatalisadores para celulas a combustivel a membrana polimerica trocadora de protons." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11208.

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Tese (Doutoramento)
IPEN/T
Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP

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Tardif, Derek. "Implication du facteur de transcription GATA-6 dans la régénération musculaire." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112311.

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Efficient muscle regeneration is essential in mammals in order to overcome daily stress such as wounds, exercise and pathologic processes. This regeneration relies on muscle stem cells, the satellite cells. After a lesion, satellite cells are activated, proliferate and differentiate in fonctionnal muscle fibers. Our laboratory has previously shown that the transcription factor GATA-6 is expressed in the satellite cells. The present thesis confirms the expression of this factor in this cell type. Also, it seems that GATA-6 could be implicated in the maintaining of quiescence of these cells. The GATA-6 heterozygous mouse muscle is characterized by an increase level of Myf5 and Pax7+ cells. Moreover, suppression of one copy of the GATA-6 gene in a muscular dystrophy model mouse, the mdx mice, alleviates its phenotype. Further experiments on a muscle-specific GATA-6 null mouse will allow a better understanding of the role of GATA-6 in muscle regeneration.
Keywords. GATA-6, muscle regeneration, mdx, satellite cells

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22

Lozano, Andres M. "The expression of the growth associated protein GAP-43 in injured and regenerating retinal ganglion cells of the adult rat /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75885.

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The lack of axonal regeneration in the adult mammalian CNS has been correlated with the apparent inability of these neurons to increase their expression of the growth associated protein, GAP-43 in response to injury. Here are reported studies of the expression of GAP-43, in retinal ganglion cells (RGCs) of the adult rat whose axons were cut at different distances along the optic nerve or cut immediately behind the eye and allowed to regenerate along peripheral nerve grafts. The immunocytochemical and axonal transport studies demonstrate that injured and regenerating RGCs synthesize and transport increased levels of GAP-43. The enhanced GAP-43 immunoreactivity and transport is triggered by axonal injury and the heightened transport of GAP-43 follows a time course which is influenced by axonal growth. The increased expression of GAP-43 and axonal regeneration into peripheral nerve grafts occur predominantly when axons are cut near their cell bodies suggesting that enhanced GAP-43 expression may be involved in the regulation of neuronal response required for axonal regrowth.

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23

Alabed, Yazan Z. 1979. "The role of RhoA interacting proteins in the Nogo signalling pathway of axon outgrowth inhibition /." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115855.

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Regrowth in the lesioned central nervous system is impeded by inhibitory molecules including myelin-associated inhibitors (MAIs) and chondroitin sulfate proteoglycans (CSPGs). Inhibitory molecules engage neuronal cell surface receptors and activate the small GTPase RhoA in injured neurons to mediate neurite outgrowth inhibition through targeted modifications to the cytoskeleton. Inhibition of RhoA with the ribosyltransferase C3 attenuates neurite outgrowth inhibition in vitro and in vivo but the ubiquitous expression and multifunctionality of RhoA may limit the specificity of therapeutic RhoA antagonists. The hypothesis of the thesis is that molecules that functionally interact with RhoA to mediate myelin-dependent inhibition may represent more specific targets for therapeutic intervention. We have explored the contribution of two RhoA interacting proteins to the neurite outgrowth inhibitory effects of MAIs. In Chapter 2 we describe the contribution of the rho effector, Rho kinase (ROCK) to MAI responses in neurons. In Chapter 3 we identify the cytosolic phosphoprotein CRMP4b (Collapsin Response Mediator Protein 4b) as a novel RhoA binding partner that mediates neuronal responses to CNS inhibitors. By structure function analysis we have developed a molecular antagonist of CRMP4b-RhoA binding that promotes neurite outgrowth on inhibitory substrates in vitro and has the potential to be a potent and specific molecular therapeutic for spinal cord injury. In Chapter 4 we identify glycogen sythase kinase 3b (GSK3b) as an important kinase in the MAI pathway that regulates protein interactions with RhoA. This thesis provides insights into the signal transduction machinery that is engaged in response to CNS inhibitors and suggests several novel therapeutic targets to promote axon regeneration following CNS injury.

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24

Van, Tonder Petrus Jacobus Malan. "Optimisation of water, temperature and voltage management on a regenerative fuel cell." Thesis, 2011. http://hdl.handle.net/10352/111.

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Thesis (M. Tech. - (Engineering: Electrical, Department: Electronic Engineering, Faculty of Engineering and Technology)) -- Vaal University of Technology, 2011.
“Never before in peacetime have we faced such serious and widespread shortage of energy” according to John Emerson, an economist and power expert for Chase Manhattan Bank. Many analysts believe that the problem will be temporary, but others believe the energy gap will limit economic growth for years to come. A possible solution to this problem can be fuel cell technology. Fuel cells (FCs) are energy conversion devices that generate electricity from a fuel like hydrogen. The FC however, could also be used in the reverse or regenerative mode to produce hydrogen. The reversible fuel cell (RFC) can produce hydrogen and oxygen by introducing water to the anode electrode chamber, and applying a potential across the anode and cathode. This will cause the decomposition of the water to produce oxygen at the anode side and hydrogen at the cathode side. In order to make this process as efficient as possible several aspects need to be optimised, for example, the operation temperature of the RFC, water management inside the RFC and supply voltage to the RFC. A three cell RFC and its components were constructed. The three cell RFC was chosen owing to technical reasons. The design factors that were taken into consideration were the different types of membranes, electrocatalysts, bipolar plates and flow topologies. A water trap was also designed and constructed to eliminate the water from the hydrogen water mixture due to water crossover within the MEA. In order to optimise the operation of the RFC a number of experiments were done on the RFC. These experiments included the optimal operating voltage, the effect that the temperature has on the production rate of hydrogen, and the effect that the water flow through the RFC has on the production rate of hydrogen. It was found that there is no need to control the water flow through the RFC because it had no effect on the production rate of hydrogen. The results also showed that if the operating temperature of the RFC were increased, the energy it consumes to warm the RFC significantly decreases the efficiency of the whole system. Thus the RFC need not be heated because it consumes significantly more energy to heat the RFC compared to the energy available from the hydrogen produced for later use. The optimised operating voltage for the three cell RFC was found to be 5.05 V. If the voltage were to be increased or decreased the RFC efficiency would decrease.

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Burger, Melanie. "Optimisation of the hydrogen pressure control in a regenerative proton exchange membrane fuel cell." Thesis, 2011. http://hdl.handle.net/10352/113.

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Thesis (M. Tech. - (Engineering: Electrical, Department: Electronic Engineering, Faculty of Engineering and Technology))--Vaal University of Technology.
Industrial countries, such as South Africa, rely heavily on energy sources to function profitably in today’s economy. Based on the 2008 fossil fuel CO2 emissions South Africa was rated the 13th largest emitting country and also the largest emitting country on the continent of Africa, and is still increasing. It was found that fuel cells can be used to generate electricity and that hydrogen is a promising fuel source. A fuel cell is an energy generation device that uses pure hydrogen (99.999%) and oxygen as a fuel to produce electric power. A regenerative fuel cell is a fuel cell that runs in reverse mode, which consumes electricity and water to produce hydrogen. This research was aimed at designing and constructing an optimised control system to control the hydrogen pressure in a proton exchange membrane regenerative fuel cell. The hydrogen generated by the fuel cell must be stored in order to be used at a later stage to produce electricity. A control system has been designed and constructed to optimise the hydrogen pressure control in a regenerative proton exchange membrane fuel cell. An experiment that was done to optimise the hydrogen system included the effects that the cathode chamber pressure has on the production of hydrogen and the most effective method of supplying hydrogen to a storage tank. The experiment also included the effects of a hydrogen buffer tank on the output hydrogen pressure and if the system can accommodate different output pressures. It was found that the cathode chamber pressure doesn’t need to be controlled because it has no effect on the rate of hydrogen produced. The results also showed that the flow of hydrogen need not to be controlled to be stored in a hydrogen storage tank, the best method is to let the produced hydrogen flow freely into the tank. The hydrogen produced was also confirmed to be 99.999% pure. The system was also tested at different output pressures; the control system successfully regulated these different output pressures.

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Juo, Min-Guei, and 卓敏貴. "Effect of oxygen electrode catalysts on unitized regenerative fuel cell." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/10210506268799438150.

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碩士
元智大學
機械工程學系
94
A satisfactory performance of an electrolytic battery is achieved with the electrode structure and the best operation temperature. The main purpose of the paper discusses the influence of catalysts and temperature on electrolytic response of water. The best candidate catalyst for fuel cell might be improper for electrolysis. It is an important and difficult work to choose the bifunctional electrodes with a thin catalyst layer. 50wt.% Ru + 50wt.% Ir is a good bifunctional catalyst for the oxygen electrode. By adding Pt and Ir in the catalyst increase the electrolytic efficiency. When the catalyst is IrRu, its best operation temperature is spent for 60℃~80℃. Adjust and rise the temperature of the cell, can reduce electrolytic energy, increase the activation of the catalyst, and accelerate speed of response. Analyse electric conduction of catalyst can know that the active influence of the catalyst be better than electric conduction of the catalyst metal. Increasing the temperature can improve the activation of catalyst, accelerate the electrolytic chemical reaction of water, and can increase electric conduction of the catalyst metal, make the electrolytic performance of water increase. The high-temperature condition will impel the electrolyte membrane to accelerate decay. When the moisture humidification of the fuel is not enough, MEA may be too dry, the membrane will because lose moisture cause the cell mass transfer polarisation. When temperature is 80 ℃, make the moisture of the membrane electrode group insufficient of fuel cell, cause the dryness of the membrane, hinder the transmission of the ion, and make efficiency unstable and drop. The best operation temperature of the fuel cell is 60 ℃. The fuel cell and electrolysis system need conductibility good catalyst. Usually join the carbon powder of good electric conductivity in the electrode catalyst. This experiment uses the PtRu catalyst includes of the carbon, probe for the influence on performance of carbon content. So we must experiment the URFC system without carbon, because the carbon will destroy the electrodes of the oxygen end when water is electrolytic, the carbon will be appeared electrolytically, and the electrolytic liquid of pollution makes its performance unable to promote.

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Skerritt, Mark. "Towards a Membrane Electrode Assembly for a Thermally Regenerative Fuel Cell." Thesis, 2013. http://hdl.handle.net/1974/7875.

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The thermally regenerative fuel cell (TRFC) concept that is analyzed is a polymer electrolyte membrane fuel cell (PEMFC), powered by the electro-oxidation of H2 and the electro-reduction of propiophenone. The main products of this fuel cell should be 1-phenyl-1-propanol and electricity. The 1-phenyl-1-propanol should then be converted back to propiophenone, while hydrogen is regenerated by using waste heat and a metal catalyst (Pd/SiO2). The first objective was to find a compatible polymer that would work as either an ionomer/binding agent and as a membrane in the membrane electrode assembly (MEA) of the TRFC. This was achieved by checking the compatibility of each polymer with 1-phenyl-1-propanol and propiophenone (the alcohol-ketone pair). Catalyst coated gas diffusion layers or catalyst coated membranes were made to test the stability of the polymers in the catalyst bed when exposed to the alcohol-ketone pair. If the polymer was compatible with the alcohol-ketone pair, MEAs were constructed using this polymer. The second objective was to test these MEAs inside a H2/propiophenone fuel cell that would prove the concept of our envisioned TRFC. It was found that the only polymer that was stable in the alcohol-ketone pair was mPBI (m-phenylene polybenzimidazole). The mPBI had to be doped with H3PO4 to enable H+ conductivity. Unfortunately, some H3PO4 leached out of the H3PO4-doped mPBI when in the presence of the alcohol-ketone pair. MEAs that were created using H3PO4-doped mPBI were found to work for H2/air and H2/propiophenone fed PEMFCs. The best performance achieved with the H2/propiophenone powered fuel cell was 6.23 μW/cm2. Unfortunately, the presence of the 1-phenyl-1-propanol product could not be proved by EIS or CV on the fuel cell, or by GC-FID of the cathode effluent. Other unknown products were seen in the GC-FID spectrum of the cathode effluent. Therefore, it is possible that the propiophenone did reduce at the cathode but it produced an unknown product. In conclusion, the viability of the proposed TRFC system was not verified. H3PO4 leaching from the MEA makes it impossible to use H3PO4-doped mPBI as the electrolyte in the final version of the MEA in the TRFC system.
Thesis (Master, Chemistry) -- Queen's University, 2013-04-12 17:16:37.724

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28

Bergen, Alvin P. "Integration and dynamics of a renewable regenerative hydrogen fuel cell system." Thesis, 2008. http://hdl.handle.net/1828/897.

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This thesis explores the integration and dynamics of residential scale renewable-regenerative energy systems which employ hydrogen for energy buffering. The development of the Integrated Renewable Energy Experiment (IRENE) test-bed is presented. IRENE is a laboratory-scale distributed energy system with a modular structure which can be readily re-configured to test newly developed components for generic regenerative systems. Key aspects include renewable energy conversion, electrolysis, hydrogen and electricity storage, and fuel cells. A special design feature of this test bed is the ability to accept dynamic inputs from and provide dynamic loads to real devices as well as from simulated energy sources/sinks. The integration issues encountered while developing IRENE and innovative solutions devised to overcome these barriers are discussed. Renewable energy systems that employ a regenerative approach to enable intermittent energy sources to service time varying loads rely on the efficient transfer of energy through the storage media. Experiments were conducted to evaluate the performance of the hydrogen energy buffer under a range of dynamic operating conditions. Results indicate that the operating characteristics of the electrolyser under transient conditions limit the production of hydrogen from excess renewable input power. These characteristics must be considered when designing or modeling a renewable-regenerative system. Strategies to mitigate performance degradation due to interruptions in the renewable power supply are discussed. Experiments were conducted to determine the response of the IRENE system to operating conditions that are representative of a residential scale, solar based, renewable-regenerative system. A control algorithm, employing bus voltage constraints and device current limitations, was developed to guide system operation. Results for a two week operating period that indicate that the system response is very dynamic but repeatable are presented. The overall system energy balance reveals that the energy input from the renewable source was sufficient to meet the demand load and generate a net surplus of hydrogen. The energy loss associated with the various system components as well as a breakdown of the unused renewable energy input is presented. In general, the research indicates that the technical challenges associated with hydrogen energy buffing can be overcome, but the round trip efficiency for the current technologies is low at only 22 percent.

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Hong, Ruei-Bo, and 洪瑞伯. "Preparation and performance of ternary catalyst in Unitized Regenerative Fuel Cell." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/81209099788985557919.

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碩士
元智大學
機械工程學系
97
This study provides the standard operation procedures of impregnation method and thermal decomposition of a polymeric precursor (DPP) method for the preparations of Pt-based catalysts as the electrode catalysts in unitized regenerative fuel cell (URFC). PtRu and PtIr have been widely used as the electrode catalysts in URFC because Ru can prevent the CO poison and Ir can provide better reversibility both at the water electrolysis mode and at the fuel cell mode. In addition, introduction of W has also been fund to increase specific surface area and resist CO poison. In order to decrease particle size and cost of the catalysts used in URFC, this study combines Pt, Ir, and Ru or W to form the ternary catalysts. This study used impregnation method to prepare Pt, PtIr, and PtRuIr; thermal decomposition of a polymeric precursor (DPP) method and microwave heating method to prepare PtWIr. For, impregnation and microwave heating method, three different pH values were selected for preparation. For DPP method, the chosen parameter was the heat treatment temperature. And some add Carbon nanotubes to prepare and compare. Carbon nanotubes material the use of commercial carbon nanotubes, respectively, as well as the oxidation of commercial carbon nanotubes. And other synthetic catalyst / carbon nanotubes, analysis of their physical properties and electrochemical properties. In this study, the use of impregnation catalyst synthesized with 60% -80% good recovery rate, by XRD can also be found to have a good crystalline structure, with an average particle size can also be controlled at below 5 nm. And found that when combining carbon nanotubes with the business when the Pt / CNT and PtWIr / CNT have good electrochemical surface area. And PtRuIr / CBT and PtIr / CBT by the cyclic voltammetry graph we can see that although both have a good reversibility, but its activity compared with Pt / CNT and PtWIr / CNT many poor in terms of performance. The experiment found that the use of DPP synthesis PtWIr / CNT could be synthesized than impregnation Pt / CNT higher activity, so the next choice PtWIr / CNT and may further improve the manufacturing process in terms of the URFC has the potential to be more than a new choice. This experiment also established a synthesis of the use of Pt catalyst impregnation with a high recovery rate and good lattice structure and the electrochemical activity of the synthetic method.

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Chang, Chih-Liang, and 張志樑. "Performance analysis of unitized regenerative fuel cell oxygen electrode using Pt-Ir catalyst." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33212864660492395644.

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碩士
明道大學
材料科學與工程學系碩士班
99
In this study, we use Pt-Ir as catalyst for creating a Pt-Ir thin film by a method of transferred onto proton exchange substrate, and producting a membrane electrode assembly combined with this Pt-Ir thin film, the proton exchange membrane and the gas diffusing electrode. The major purpose of this project was to produce bifunctional membrane electrode assemblies by mechanical alloying in Different ratio of Pt and Ir , and investigate the influences of efficiency of URFC under a condition of the current density is 500 mA/cm2 and the proposed electrolysis voltage less than 2.0 V. Our result shows that the sample without Mechanical Polishing which electric current decay more serious test by a long time water electrolysis analysis. We consider that the Pt-Ir catalyst to with mechanical alloying was better than without mechanical alloying. Because of that the crystals were affected by mechanical lapping and hot pressing, the pellet become more uniform ,and it will be effected the result of water electrolysis of URFC. We also observe the Crystallization structure by TEM、XRD、SEM and Microstructure in the process of mechanical alloying.

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31

Jansen, van Rensburg Neil. "Technology development of a maximum power point tracker for regenerative fuel cells." Thesis, 2015. http://hdl.handle.net/10352/317.

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M. Tech. (Department of Electronic Engineering, Faculty of Engineering and Technology) --Vaal University of Technology|
Global warming is of increasing concern due to several greenhouse gases. The combustion of fossil fuels is the major contributor to the greenhouse effect. To minimalise this effect, alternative energy sources have to be considered. Alternative energy sources should not only be environmentally friendly, but also renewable and/or sustainable. Two such alternative energy sources are hydrogen and solar energy. The regenerative fuel cell, commonly known as a hydrogen generator, is used to produce hydrogen. The current solar/hydrogen system at the Vaal University of Technology’s Telkom Centre of Excellence makes use of PV array to supply power to an inverter and the inverter is connected to the hydrogen generator. The inverter provides the hydrogen generator with 220VAC. The hydrogen generator has its own power supply unit to convert the AC power back to DC power. This reduces the efficiency of the system because there will be power loss when converting DC power to AC power and back to DC power. The hydrogen generator, however, could be powered directly from a PV array. However, the hydrogen generator needs specific input parameters in order to operate. Three different input voltages with their own current rating are required by the hydrogen generator to operate properly. Thus, a DC-DC power supply unit needs to be designed to be able to output these parameters to the hydrogen generator. It is also important to note that current PV panel efficiency is very low; therefore, the DC-DC power supply unit also needs to extract the maximum available power from the PV array. In order for the DC-DC power supply unit to be able to extract this maximum power, a maximum power point tracking algorithm needs to be implemented into the design. The DC-DC power supply is designed as a switch mode power supply unit. The reason for this is that the efficiency of a switch mode power supply is higher than that of a linear power supply. To reach the objective the following methodology was followed. The first part of the research provided an introduction to PV energy, charge controllers and hydrogen generators. The problem statement is included as well as the purpose of this research and how this research was to be carried out. The second part is the literature review. This includes the background study of algorithms implemented in MPPT’s; it also explains in detail how to design the MPPT DC-DC SMPS. The third part was divided into two sections. The first section is the design, programming and manufacturing of the MPPT DC-DC SMPS. The second section is the simulation of the system as a whole which is the simulation of the PV array connected to the MPPT DC-DC SMPS and the hydrogen generator. The fourth part in the research compared the results obtained in the simulation and practical setup. The last part of the research provided a conclusion along with recommendation made for further research. The simulation results showed that the system works with an efficiency of 40,84%. This is lower than expected but the design can be optimised to increase efficiency. The practical results showed the efficiency to be 38%. The reason for the lower efficiency is the simulation used ideal components and parameters, whereas the practical design has power losses due to the components not being ideal. The design of the DC-DC switch mode power supply, however, indicated that the hydrogen generator could be powered from a PV array without using an inverter, with great success.

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32

Allward, Todd. "Membrane Electrode Assembly Fabrication and Test Method Development for a Novel Thermally Regenerative Fuel Cell." Thesis, 2012. http://hdl.handle.net/1974/7594.

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A test system for the performance analysis of a novel thermally regenerative fuel cell (TRFC) using propiophenone and hydrogen as the oxidant and fuel respectively was designed and built. The test system is capable of either hydrogen-air or hydrogen-propiophenone operation. Membrane electrode assemblies (MEAs) were made using commercial phosphoric acid-doped polybenzimidazole (PBI) membranes and commercial electrodes. Using Pt/carbon paper electrodes with a catalyst loading of 1mg/cm2 and a membrane with an acid doping level of 10.2 mol acid/mol of polymer repeat unit, a maximum performance of 212 mW/cm2 at a current density of 575 mA/cm2 was achieved for baseline hydrogen-air testing at 110°C. Problems were encountered, however, in achieving consistent, reproducible performance for in-house fabricated MEAs. Furthermore, ex-situ electrochemical impedance spectrometry (EIS) showed that the phosphoric acid-doped PBI was unstable in the propiophenone and that acid-leaching was occurring. In order to have MEAs with consistent characteristics for verifying the test system performance, commercial phosphoric acid-doped PBI membrane electrode assemblies were used. At a temperature of 160°C and atmospheric pressure with hydrogen and air flowrates of 150 mL/min and 900 mL/min respectively a maximum power density of 387 mW/cm2 at a current density of 1.1 A/cm2 was achieved. This performance was consistent with the manufacturer’s specifications and these MEAs were subsequently used to verify the performance of TRFC test system despite the EIS results that indicated that acid-leaching would probably occur. The Pt catalyzed commercial MEAs achieved very limited performance for the hydrogenation of the ketone. However, the performance was less than but comparable to similar results previously reported in the literature by Chaurasia et al. [1]. For pure Pt catalyst loading of 1 mg/cm2, using a commercial PBI MEA operating at 160°C and atmospheric pressure, the maximum power density was 40 µW/cm2 at a current density of 1.3 mA/cm2. A 16 hour test was conducted for these conditions with a constant 1 ohm load, successfully demonstrating the operation of the test system. The test system will be used in the development of better catalysts for ketone hydrogenation.
Thesis (Master, Chemical Engineering) -- Queen's University, 2012-10-12 10:00:58.854

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33

Tsao, Zun-bing, and 曹遵秉. "Study on Pt / MWNT Electrocatalysts Prepared by Microwave-Assisted Polyol Method for Unitized Regenerative Fuel Cell." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/82702245297146546864.

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碩士
元智大學
機械工程學系
98
Homogenization regenerative fuel cell (URFC) The key technology is the catalyst layer, so in addition to improved catalysts and to improve performance, reduce the amount of catalyst used and thus reduce their costs as the biggest issue. This study tried to join the multi-walled carbon nanotubes (MWNT) and Pt binding, it can satisfy the increasing performance and reducing catalyst URFC use purposes. In this study, microwave heating method under the different pH values were prepared Pt / MWNT catalyst which, with the manufacturing process is simple, rapid response, equipment, easy access and so on. To replace the traditional carbon MWNT material, is expected to MWNT Merit mechanical and material properties, effectively enhance the activity of Pt and indirectly reduce the catalyst cost. PH values and to consider whether the oxidation of carbon nanotubes, using many materials Characteristics of sample detection technology. Made the final assessment of fuel cell membrane electrode pattern in the model with the water electrolysis performance. Found, Pt granules can be distributed evenly in the MWNT surface of the catalyst, the average grain size of about 3-5 nm, granules size as the pH value increases. After the pore volume of carbon nanotube oxidation increased, and the pore structure changed. The results showed that in the neutral environment can be synthesized with high purity and good crystallinity Leung Pt / MWNT. XPS high-resolution analysis revealed, pH, the more profit the higher the reduction in Pt. CV results also show that, Pt / NT and Pt / oNT the ESA is highest at pH = 7, respectively 70.89 and 70.68 m2 / g; attenuation in Pt / NT (pH = 7) 9% of the minimum attenuation. In the fuel cell mode, with Pt / NT (pH = 7) the performance of the highest output power of 655 mW/cm2, while the Pt / oNT (pH = 7) an output of 565 mW/cm2. Water electrolysis mode to Pt / NT (pH = 7) in the performance of 1.4V maximum, up to 202 mA/cm2, from these two tests can be found in Pt / NT (pH = 7) as the best catalyst in combination URFC

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Chang, Cheng-Hsiung, and 張政雄. "Study on Effects of Catalyst/Carbon Nanotubes Composite Electrocatalysts for the Performance of Unitized Regenerative Fuel Cell." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/20696844431413025791.

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碩士
元智大學
機械工程學系
96
The key technology on development of the unitized regenerative fuel cell (URFC) is in catalysts. Therefore, besides the enhancement of catalysts to improve the performance, reduction in the use of catalyst to decrease the cost of system has become the most important issue. This study has attempted to introduce the carbon nanotubes (CNTs) into the catalyst, based on the fact that CNTs have uniform structure and excellent conductivity. This is expected that the catalyst would have good dispersion on CNT surface, thus the high performance of URFC and the decrease in the catalyst use can be achieved. The impregnation method was employed to prepare the Pt and Pt-Ir catalysts, and the chemical vapor deposition method was used to synthesize the multi-walled carbon nanotubes. And then the catalyst/CNTs composite materials were prepared. All materials were characterized by surface techniques. Next, several sets of membrane electrode assembly (MEA) were made and the performance of URFC on water electrolysis and fuel cell modes were tested. The results show that the Pt catalyst from impregnation method has a purity of about 99 %, and the purity of Pt-Ir catalyst is approximately 96 %. Both the mean particle sizes of Pt and Pt-Ir catalysts were in the range of 5-10 nm. The XRD patterns indicate Pt (or Pt-Ir) catalyst displays the Pt (or Pt and Ir) fcc structure. The TEM images show that the as-grown CNTs are long and spaghetti-like with a diameter of probably 30-80 nm. The HRTEM images of catalyst/CNT composite also manifest the good dispersion of the catalyst on CNT surface. The test results of URFC show that in fuel cell mode the best capacity occurs as both oxygen and hydrogen electrodes are added the commercial CNTs. In water electrolysis mode, introduction of pCNT onto both electrodes perform the best capacity, which is even superior to that of the MEA composed of noble metals. In view of the hydrogen production, introduction of CNTs only on oxygen electrode can achieve stable and the highest yield.

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Kúš, Peter. "Tenkovrstvové katalyzátory pre použitie v elektrolyzéroch vody a regeneratívnych palivových článkoch s protónovo vodivou membránou." Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-388760.

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This dissertation thesis revolves around hydrogen economy and energy-storage electrochemical systems. More specifically, it investigates the possibility of using magnetron sputtering for deposition of efficient thin-film anode catalysts with low noble metal content for proton exchange membrane water electrolyzers (PEM-WEs) and unitized regenerative fuel cells (PEM-URFCs). The motivation for this research derives from the urgent need of minimizing the price of mentioned electrochemical devices should they enter mass production. Numerous experiments were carried out, correlating the actual in-cell performance with the varying position of thin-film catalyst within the membrane electrode assembly, with the composition of high-surface support sublayer and with the chemical structure of the catalyst itself. The wide arsenal of analytical methods ranging from electrochemical impedance spectroscopy through scanning electron microscopy to photoelectron spectroscopy allowed us to describe complex phenomena behind different obtained efficiencies. Consequent systematic optimizations led to the design of novel PEM-WE anode thin-film iridium catalyst with thickness of just 50 nm, supported on optimized TiC-based sublayer which performed similarly to standard counterparts despite using just a fraction of their noble metal...

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