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Rismanchian, Azadeh. "Copper Nickel Anode for Methane SOFC." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1312299949.
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Lay, Elisa. "Nouveaux matériaux d'électrode de cellule SOFC." Phd thesis, Grenoble 1, 2009. http://www.theses.fr/2009GRE10307.
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Ce travail est consacré à l'étude des influences de deux cations, le cérium et le baryum, sur les propriétés structurales, physico-chimiques, électriques et électrochimiques de l'oxyde (La,Sr)(Cr,Mn)O3 (LSCM). L'effet de l'état d'oxydation du cérium a été déterminé en substituant les sites A de LSCM et d'un oxyde de composition proche, CexSr1-xCr0,5Mn0,5O3 (CeSCM). L'influence des propriétés de basicité du baryum a été examinée. Les matériaux sont stables en conditions de fonctionnement d'anode pour SOFC. La conductivité est de type p pour CeLSCM et CeSCM. Les composés LBCM sont des semi-conducteurs de type n pour des pressions partielles comprises entre 1 et 10-4 atm, et de type p pour des pressions plus faibles. Sous atmosphère neutre, la conductivité électrique totale augmente avec la teneur en cérium dans LSCM, et la conductivité des matériaux CeSCM est similaire à celle de CeLSCM substitué par 25% de cérium (36 S. Cm-1 à 900 °C). Sous atmosphère réductrice, la conductivité des matériaux CeLSCM est de l'ordre de 1 S. Cm-1. La quantité de baryum n'a pas d'influence sur la conductivité de LSBCM. La caractérisation d'électrodes ponctuelles denses a permis de montrer que les performances anodiques augmentent avec la teneur en cérium substitué au lanthane dans LSCM. La nature des processus impliqués n'est pas modifiée lorsque le strontium est substitué par le cérium, même si l'absence de lanthane pénalise le comportement anodique. Des performances intéressantes pour une application comme matériau d'anode pour SOFC ont été atteintes pour le composé La0,75Ba0,25Cr0,5Mn0,5O3. Les origines des contributions élémentaires des caractéristiques d'électrode sont discutéesInfluences of two cations, cerium and baryum, have been examined on the structural, physico-chemical, electrical and electrochemical properties of LSCM (La,Sr)(Cr,Mn)O3 as an anode for SOFC. LSCM was subtituted on the A site of the perovskite (cerium on lanthanum sites, or baryum on strontium sites). The related composition CeSCM (CexSr1-xCr0. 5Mn0. 5O3) has been synthetised in order to increase Ce4+ concentration. Chemical stabilities are discussed in elaboration and operating conditions. Electrical conductivity measurements have been performed in different atmospheres. CeLSCM and CeSCM are p-type semi-conductors. LBSCM materials are n-type semi-conductors for pO2 from 1 atm to 10-4 atm, and p-type for lower pO2. Electrical conductivity for CeLSCM materials increases with cerium content. Conductivities of CeSCM materials are similar. In reducing conditions, these materials exhibit a conductivity of 1 S. Cm-1 at 900 °C, except for CeSCM 50 (0,2 S. Cm-1). Baryum content has no influence on electrical conductivity of LBSCM; it is divided by 2 compared with LSCM in air and in H2- 3% H2O, and is slighty better than LSCM in argon. Electrochemical characterizations have been performed on dense pin-shaped electrodes. Stationnary and dynamic periodic measurements were performed. Anodic performances of CeLSCM materials increase with cerium content. CeLSCM 37. 5 properties are compatible with an application as anode SOFC operating beyond 800 °C. Electrode reaction is not modified when strontium is substituted by cerium. However, lanthanum absence has a poor effect on performance. LBCM exhibits interesting performances as an anode for SOFC. Origins of electrode reactions are discussed
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Lay, Elisa. "Nouveaux matériaux d'électrode de cellule SOFC." Phd thesis, Université Joseph Fourier (Grenoble), 2009. http://tel.archives-ouvertes.fr/tel-00461152.
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Ce travail est consacré à l'étude des influences de deux cations, le cérium et le baryum, sur les propriétés structurales, physico-chimiques, électriques et électrochimiques de l'oxyde (La,Sr)(Cr,Mn)O3 (LSCM). L'effet de l'état d'oxydation du cérium a été déterminé en substituant les sites A de LSCM et d'un oxyde de composition proche, CexSr1-xCr0,5Mn0,5O3 (CeSCM). L'influence des propriétés de basicité du baryum a été examinée. Les matériaux sont stables en conditions de fonctionnement d'anode pour SOFC. La conductivité est de type p pour CeLSCM et CeSCM. Les composés LBCM sont des semi-conducteurs de type n pour des pressions partielles comprises entre 1 et 10-4 atm, et de type p pour des pressions plus faibles. Sous atmosphère neutre, la conductivité électrique totale augmente avec la teneur en cérium dans LSCM, et la conductivité des matériaux CeSCM est similaire à celle de CeLSCM substitué par 25% de cérium (36 S.cm-1 à 900 °C). Sous atmosphère réductrice, la conductivité des matériaux CeLSCM est de l'ordre de 1 S.cm-1. La quantité de baryum n'a pas d'influence sur la conductivité de LSBCM. La caractérisation d'électrodes ponctuelles denses a permis de montrer que les performances anodiques augmentent avec la teneur en cérium substitué au lanthane dans LSCM. La nature des processus impliqués n'est pas modifiée lorsque le strontium est substitué par le cérium, même si l'absence de lanthane pénalise le comportement anodique. Des performances intéressantes pour une application comme matériau d'anode pour SOFC ont été atteintes pour le composé La0,75Ba0,25Cr0,5Mn0,5O3. Les origines des contributions élémentaires des caractéristiques d'électrode sont discutées.
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Hubert, Maxime. "Durabilité des convertisseurs électrochimiques haute température à oxydes solides : une étude expérimentale et de modélisation basée sur la caractérisation au synchrotron par nanotomographie des rayons X." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI011/document.
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Ce travail porte sur l’étude de la dégradation des convertisseurs électrochimiques haute température à oxydes solides. Une approche couplant des tests électrochimiques, des caractérisations post-mortem avancées et une modélisation multi-échelle a été mise en place afin d’établir les liens entre les performances, la microstructure des électrodes et leur dégradation. Dans ce but, des essais de durabilité de plus de mille heures ont été menés dans différentes conditions opératoires. La microstructure des électrodes a été reconstruite par nano-holotomographie des rayons X pour la cellule de référence avant et après vieillissement. Une attention particulière a été apportée à la mesure de la résolution spatiale et à la fiabilisation du protocole expérimental. Grâce aux volumes 3D, les propriétés microstructurales de l’électrode H2 en Ni-YSZ ont été quantifiées pour les cellules à l’état initial et vieillies. Un modèle physique d’agglomération des particules de Nickel a ensuite été ajusté sur les analyses tridimensionnelles et intégré dans une structure de modélisation multi-échelle développée au laboratoire. Il a auparavant été nécessaire de compléter l’outil numérique avec un module spécifique dédié aux matériaux composant l’électrode à oxygène fait avec un conducteur mixte ionique-électronique. Une fois le modèle validé sur des courbes de polarisation expérimentales, il a été utilisé pour quantifier la contribution de l’agglomération du Nickel sur les pertes de performances mesurées expérimentalement en mode pile à combustible et électrolyseThis work aims at a better understanding of the high temperature Solid Oxide Cells degradation. An approach based on electrochemical tests, advanced post-test characterizations and multi-scale models has been used to investigate the links between the performances, the electrodes microstructure and their degradation. In that goal, long-term durability tests have been performed over thousand hours in different operating conditions. Electrode microstructures have been reconstructed by X-ray nano-holotomography for the pristine and the aged cells. It is worth noting that a special attention has been paid to improve both the process reliability for the tomographic experiments as well as the spatial resolution of the 3D reconstructed images. Thanks to the valuable 3D volumes, the Ni-YSZ microstructural properties of the H2 electrode have been quantified for the fresh and the aged samples. Then, a physically-based model for Nickel particle agglomeration has been adjusted on the microstructural parameters obtained by the 3D analysis and implemented in an in-house multi-scale modelling framework. Beforehand, it has been necessary to enrich the available numerical tool with a specific module dedicated to the oxygen electrode made in Mixed Ionic Electronic Conducting materials. Once validated on polarisation curves, the completed model has been used to quantify the contribution of Nickel agglomeration on the experimental degradation rates recorded in fuel cell and electrolysis modes
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Doux, Jean-Marie. "Recherche exploratoire de nouveaux matériaux d'électrolyte pour piles à combustible et électrolyseurs à oxyde solide (SOFC et SOEC)." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4094/document.
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Ces travaux portent sur la recherche de matériaux alternatifs d’électrolyte ou d’électrodes de piles à combustible à oxyde solide. Une méthodologie basée sur la composition de l’oxyborate La26O27(BO3)8, développé à l’IMN, a permis de mettre en évidence deux matériaux prometteurs : Ba3Ti3O6(BO3)2 et K3Sb4O10(BO3). La synthèse de poudres de Ba3Ti3O6(BO3)2 et de phases substituées sur les sites du Ba ou du Ti ont été réalisés par voie solide à 950 °C. Les mesures de conductivité ont été effectuées par EIS sur des échantillons denses (compacité ≥ 90 %). Sous air, la conductivité est purement anionique et dépasse 10-4 S.cm-1 à 700 °C. Elle augmente pour les composés substitués par un élément de valence supérieure, et inversement. Sous atmosphère hydrogénée, une forte augmentation de conductivité est observée (x 200), liée à l’apparition d’une contribution électronique. Une étude couplant DRX, XPS et ATG montre que cette contribution est due à une réduction de 5 % du Ti4+ en Ti3+ et que cette réaction est réversible. Les calculs DFT ont permis de déterminer les énergies de formation et de migration des défauts dans le matériau. L’oxyborate K3Sb4O10(BO3) a été obtenu sous forme de monocristaux et de poudre. Une étude approfondie de la densification a été nécessaire afin d’obtenir des échantillons denses (compacité ≈ 90 %), en utilisant un broyage planétaire et/ou une aide au frittage. La conductivité du matériau sous air est de l’ordre de 10-3 S.cm-1 à 700 °C. Ces travaux mettent en évidence pour la première fois des niveaux de conductivité (ioniques et/ou électroniques) importants dans les oxyborates. Cette approche peut être appliquée à la recherche de matériaux alternatifs pour SOFCThis work focuses on the search for alternative electrolyte or electrodes materials for solid oxide fuel cells. A methodology based on the composition of the La26O27(BO3)8 oxyborate, developed at the IMN, revealed two promising materials: Ba3Ti3O6(BO3)2 and K3Sb4O10(BO3). Syntheses of powders of Ba3Ti3O6(BO3)2 and substituted phases on the Ba or Ti atomic site were carried out by solid state reaction at 950 °C. Conductivity measurements were carried out by electrochemical impedance spectroscopy on dense samples (relative density ≥ 90 %). Under air, the conductivity is purely anionic and exceeds 10-4 S.cm-1 at 700 °C. Conductivity increases for compounds substituted with a supervalent element, and vice versa. In a hydrogen containing atmosphere, a large increase of conductivity is observed (x 200), linked to the appearance of an electronic contribution. A study combining XRD, XPS and TGA shows that this contribution is due to the reduction of 5 % of the Ti4+ in Ti3+ and that this reaction is reversible. DFT calculations allowed to determine the formation energies and the migration barriers of the defects in the material. K3Sb4O10(BO3) oxyborate was obtained as single crystals and powder. A thorough study of the densification of the material was necessary in order to obtain dense samples (relative density ≈ 90 %), using ball milling and/or sintering aid. The conductivity of the material in air is about 10-3 S.cm-1 at 700 °C. This work highlights significant conductivity levels (ionic and/or electronic) observed for the first time in oxyborates. This approach can be applied to find alternative materials for SOFC
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Feighery, Alan John. "Zirconia-based electroceramic materials for SOFC applications." Thesis, University of St Andrews, 1999. http://hdl.handle.net/10023/13601.
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The phase relations, electrical properties and structural characteristics of doped cubic stabilised Zirconia based electroceramic materials have been investigated using a number of characterisation techniques. The phase relations of the ternary systems ZrO2 -Y2O3 -TiO2 and ZrO2 -Gd2 O3 - TiO2 at 1500°C have been investigated. Electrical characterisation in air and in low oxygen partial pressures has been carried out using 2-probe A.C. Impedance Spectroscopy and 4-probe D.C. resistivity measurements to ascertain whether compositions within these systems could be utilised as the anode materials in Solid Oxide Fuel Cells. The effect of porosity on the ionic and electronic conducting properties of the ZrO2 -Y2 O3 -TiO2 system has been investigated to provide a clearer understanding of the effect of the porosity within candidate anode materials. The effect of Al2O3 additions on the electrical properties and stability of the Solid Oxide Fuel Cell material of choice, 8 mol% Yttria stabilised Zirconia, has been investigated. Al2 O3 has been found to remain primarily as a second phase within the 8YSZ, however a small quantity of Al3+ does dissolve into the fluorite matrix. Al2 O3 has been found to have a negligible effect on the high temperature ionic conductivity of 8YSZ and improves the resistance of 8YSZ to hydrothermal degradation by stabilising the cubic structure. High temperature Time of Flight Neutron Diffraction has been used to link the change in activation energy observed in 8YSZ to a break down in local ordering of oxygen ions. Extended X-ray absorption Fine Structure Spectroscopy has been used to characterise the local structure of the cations in 8 mol% Yttria-stabilised Zirconia. Analysis of the high temperature data reveals that the local structure is quite different from the average crystallographic structure. The oxygen vacancies were determined to be associated with Zirconium ions and found to disorder at high temperatures.
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Lee, Soo-na. "Chromium poisoning of cathodes in the SOFC." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24554.
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Mixed Ionic Electronic Conductors (MIECs) such as La0.6Sr0.4Co0.2Fe0.8O3δ (LSCF) and La2NiO4+δ (LNO) are gaining much attention as candidate cathode materials at reduced working temperatures (600-800°C), because they exhibit better oxygen transport properties, in comparison to earlier cathode materials such as LaxSr1xMnyO3δ(LSM). The main objective of the study in this thesis is establishing the relationship between the amount of chromium and performance degradation of LSCF and Sr-free LNO cathodes, and improving understanding of the mechanism. LSCF were screen printed onto Ce0.9Gd0.1O1.95 (CGO10) electrolyte pellets and infiltrated with chromium nitrate solutions to different Cr levels up to 2wt%. Electrochemical impedance spectroscopy at 500 ~ 800°C showed that even very low levels of Cr give a significant increase in cathode polarisation resistance, which increases with Cr concentration. The impedance response was analysed using the model of Adler, Lane and Steele (ALS model) to extract oxygen self-diffusion (Do) and surface exchange (ko) parameters for the LSCF. The results show that Cr reduces both Do and ko, the latter being the more affected. However, the activation energies for polarisation resistance, Do and ko are not significantly affected by Cr content. This indicates that the Cr poisoning mechanism involves the de-activation of sites for oxygen exchange on the LSCF surface and that the cathode's residual activity is by means of remaining active sites. The surface reaction and diffusion of oxygen in dense LSCF was studied by oxygen isotope exchange using bulk specimens and depth profile analysis. The specimen surfaces were coated with different thicknesses of Cr2O3 by sputtering prior to exchange. The results showed that the Cr2O3 surface layer had a large inhibiting effect on ko, in agreement with the electrochemical measurements, but a negligible effect on Do because diffusion of Cr into the bulk was very slow. The effect of Cr on Sr-free LNO electrodes deposited symmetrically onto Ce0.9Gd0.1O1.95 (CGO10) electrolytes by screen printing was studied in a similar way. XRD of LNO/Cr2O3 powder mixtures annealed at 1000°C for 24h showed that LNO reacts readily with Cr2O3 to form LaCrO3 and LaNiO3. Despite this reactivity, the electrochemical experiments show that the polarisation resistance of LNO cathodes is insensitive to Cr introduced by solution infiltration for Cr concentrations up to 1%. For concentrations above this level the Cr increases the polarisation resistance, but to a much lesser degree in comparison to LSCF. Cr reduces the rate of the oxygen reduction reaction on the LNO surfaces, but does not change the activation energy significantly. The relatively good tolerance of LNO cathodes to Cr ingress is probably due to the reaction products themselves having some useful catalytic activity for oxygen reduction.
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Hu, Yang. "Study of GdBaCo2-xMxO5+δ (M=Ni, Fe; x = 0, 0.1, 0.2,...) as new cathode materials for IT-SOFC application." Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00619609.
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GdBaCo2O5+δ a été présenté récemment comme un matériau de cathode potentiel pour pile à combustible à oxyde solide. Cependant, sa réactivité chimique avec la zircone yttriée et son fort coefficient de dilatation constituent une limite importante à son utilisation. L'objet de ce travail est l'étude des composés GdBaCo2 xMxO5+δ (M = Ni, Fe, x = 0, 0.1, 0.2...) i.e. substitués au fer et au nickel pour objectif d'améliorer les propriétés du composé original pour l'application pile à combustible. Tout d'abord, différentes méthodes de synthèse ont été essayées et comparées, les méthodes par voie chimique montrant un net avantage pour l'obtention de taux de substitution élevés. Les propriétés physico-chimiques des matériaux synthétisés ont été caractérisées. Si la structure des composés évolue avec la nature et le taux du substituant, les propriétés de ces composés en termes de conduction électronique ou d'évolution du contenu en oxygène sont relativement constantes. Finalement, les performances électrochimiques de plusieurs compositions sous forme d'électrodes poreuses ont été testées avec différents types d'électrolytes. Les résultats montrent que la substitution n'apporte rien pour ce qui concerne la dilatation des composés et par ailleurs ne semble pas améliorer significativement les performances électrochimiques.
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Schwartz, Brian. "Analysis of the potential for thermal radiation promotion within solid oxide fuel cells." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53909.
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Solid oxide fuel cell (SOFC) systems have the potential to provide highly efficient power generation systems capable of utilizing readily available hydrocarbons. It is hoped that these systems will be capable of replacing some of the conventional power systems and act to reduce overall emissions and increase energy efficiency. SOFC technology faces many challenges such as high cost, lifetime uncertainties, and long startup times; and these challenges have prevented SOFC technology from being widely adopted.
Established methods for providing SOFC stack thermal management are either very costly, work against system design goals, or are unreliable. If SOFC thermal management needs could be reduced, it is possible that SOFC cost and lifetime could be improved. It is thought that promotion of thermal radiation within a SOFC stack may add thermal control which will reduce the need for stack thermal management. Radiation may be promoted by decreasing the length: hydraulic diameter ratio of cathode flow channels and by increasing the manifold size to create a larger stack radiation enclosure. Full thermal tests of a SOFC stack are difficult and expensive, and due to this simulations of a SOFC are widely used to analyze stack thermal behavior.
In this work, a model of a SOFC “unit cell” is adjusted to represent modern SOFC stacks. The proposed methods for radiation promotion are tested with simulations using this model, and conclusions of radiation promotion in SOFC stacks are provided. Additionally, radiative properties of commonly used materials are obtained through experiments, and future work for reducing stack reliance on active thermal management is proposed.
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Satapathy, Akshaya Kumar. "Layered perovskites as cathode materials for IT-SOFC." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/11962.
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T* based La₀.₉Ln₀.₉Sr₀.₂CuO₄ (Ln = Sm & Gd) has been investigated as cathode material for intermediate temperature solid oxide fuel cell using Ce₀.₉Gd₀.₁O₁.₉₅ (GDC) and La₀.₉Sr₀.₁Ga₀.₈Mg₀.₂O₃-δ (LSGM-9182) as the electrolyte material. Both oxides crystallize in tetragonal P4/nmm symmetry. The structural and phase stability has been confirmed up to 800 °C by High temperature XRD studies. The coefficient of thermal expansion (CTE) and oxygen content decrease with decreasing size of the Ln³+ ions from Ln = Sm to Gd. While the decrease in CTE is due to the increasing co-valence of the Ln–O bond, the decrease in electrical conductivity at high temperature is due to the increasing oxide ion vacancies and a bending of the O–Cu–O bonds. The highest value of DC conductivity has been observed for the LSSCu, which showed a metal like temperature dependence. LGSCu showed a semiconductor to metallic temperature dependence of conductivity with a maximum of 25 Scm-¹. From the microstructural characterization and the polarisation resistance measurement of the symmetric cells at temperature ranges from 700 - 800 °C, 900 °C has been chosen as the most suitable sintering temperature and LGSCu has shown the minimum polarization resistance of 0.35 Ωcm² and 0.09 Ωcm² at 800 °C using GDC and LSGM-9182 electrolytes respectively under OCV condition. To improve the ASR of LGSCu, the composite of LGSCu and GDC with varying wt. % of GDC has been optimised and it shows the ASR of 0.12 Ωcm² using GDC as the electrolyte because it enhance the triple phase boundary region. The maximum power density of single-cell SOFCs fabricated with the La₀.₉Ln₀.₉Sr₀.₂CuO₄ (Ln= Sm & Gd) cathodes, La₀.₉Sr₀.₁Ga₀.₈Mg₀.₂O₃-δ (LSGM-9182) electrolyte, and Ni–Ce₀.₉Gd₀.₁O₁.₉₅ cermet anode exhibit 720 and 824 mWcm-² at 800 °C respectively. The phase pure T* Nd₁.₃₂Ce₀.27Sr₀.₄₁CuO₄-δ (NCSCu) has been synthesized by combustion method and its crystal chemistry, thermal and electrochemical properties, and catalytic activity in SOFC were evaluated using LSGM-9182 as the electrolyte. It shows promising performance and can be used as potential cathode materials for IT-SOFC. The effect of B-site Ni and Co substitution for Cu on the structural and electrochemical properties of the T* La₀.₉Gd₀.₉Sr₀.₂CuO₄ has been investigated as cathode materials for intermediate temperature solid oxide fuel cells using LSGM-9182 as the electrolyte. At a given temperature, the electrical conductivity gradually increases with increasing Ni content and the CTE gradually decreases. Ni doping has also improved the electrochemical performance. Sr doped A /A //B₂O₅+δ (A / = Rare Earth, A // = Ba or Sr and B = Transition Metals) layered perovskites improves the electrochemical performance due to the increase in electrical conductivity and smaller size difference between Ln+³ and Sr+². However these layered perovskites suffer from high thermal expansion coefficient (20-23 x 10-6 K-1) which does not match with the state of the art electrolyte materials. B-site transition metal doped layered perovskites of compositions SmBa₀.₅Sr₀.₅Co₂-ₓO₅+δ (M = Cu, Ni, Fe) have been investigated as cathode material for intermediate temperature solid oxide fuel cell using LSGM-9182 as the electrolyte material. Phase purity has been confirmed by XRD technique. The crystal cell parameters have been found out using Rietveld refinement by FULLPROF software. The substitution of Cu, Ni and Fe for Co lowers the CTE of Co-based materials by suppression of the spin state transition of Co³+ which will be highly advantageous for long term SOFC application. The introduction of transition metals exhibit inferior electrochemical performance to pristine cathode using LSGM-9182 as the electrolyte but still shows reasonable power density with advantage of lower CTE value thereby can be explored as promising cathode material for IT-SOFCs.
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Sarwari, Javid, and Abbas Heidari. "Ersätta APU:n med SOFC-GT Hybridsystem inom luftfarten." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-38930.
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The current Auxiliary Power Unit (APU) contributes a lot to the greenhouse effect in terms of emissions, and in the form of noise and also is very heavy. The need for more electricity has increased in aircrafts and therefore major aircraft suppliers like Boeing and Airbus want to switch to more electric aircraft (MEA) which is lighter and has less environmental impacts. The purpose of this work is to investigate the possibilities of replacing today's traditional APU with fuel cells. In this work presents six different common fuel cell types which used commercially in various areas in the market. We have also analyzed and investigated the most suitable fuel cell types and have chosen to apply the SOFC-GT Hybrid Systems. We have investigated and compared both systems with pros and cons. We have used different methods in this work including the FOI3-method and Safran & Honeywell for calculations of emissions for all systems. Finally, we have analyzed and investigated the emissions, noise and weight for both systems.Nuvarande Auxiliary Power Unit (APU) bidrar mycket negativt till växthuseffekten i form av emissionsutsläpp och även i form av buller och är dessutom mycket tunga. Behovet av mer elektricitet ökar i flygplan och därför vill stora flygplanstillverkare såsom Boeing och Airbus övergå till more electric aircraft (MEA) vilket är lättare och har mindre miljöpåverkan. Syftet med detta arbete är att undersöka möjligheterna av att ersätta dagens traditionella APU mot bränsleceller. I detta arbete presenteras sex olika bränslecellstyper som finns på marknaden och används kommersiellt inom olika områden. Vi har analyserat och undersökt de lämpligaste bränslecellstyper för applicering och därefter har vi valt att implementera SOFC- GT Hybridsystemen. Vi har undersökt och jämfört båda systemens för- och nackdelar. Metodmässigt används bland annat FOI3-Metoden och Safran & Honeywell för beräkningar av utsläpp av emissioner för samtliga system. Slutligen har vi analyserat och undersökt skillnader i utsläpp av emissioner, buller och vikt för båda systemen.
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Stanislowski, Michael. "Verdampfung von Werkstoffen beim Betrieb von Hochtemperaturbrennstoffzellen (SOFC)." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979707803.
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Fouquet, Daniel. "Einsatz von Kohlenwasserstoffen in der Hochtemperatur-Bennstoffzelle SOFC." Aachen Wiss.-Verl. Mainz, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2707906&prov=M&dok_var=1&dok_ext=htm.
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Haschka, Markus Stephan. "Online-Identifikation fraktionaler Impedanzmodelle für die Hochtemperaturbrennstoffzelle SOFC." Karlsruhe : Univ.-Verl. Karlsruhe, 2008. http://d-nb.info/989222365/34.
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Mitchell-Williams, Thomas Benjamin. "Tailoring superconductor and SOFC structures for power applications." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267811.
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High temperature superconductors (HTS) and solid oxide fuel cells (SOFCs) both offer the possibility for dramatic improvements in efficiency in power applications such as generation, transmission and use of electrical energy. However, production costs and energy losses prohibit widespread adoption of these technologies. This thesis investigates low-cost methods to tailor the structures of HTS wires and SOFCs to reduce these energy losses. Section I focusses on methods to produce filamentary HTS coated conductors that show reduced AC losses. This includes spark-discharge striation to pattern existing HTS tapes and inkjet printing of different filamentary architectures. The printed structures are directly deposited filaments and ‘inverse’ printed tracks where an initially deposited barrier material separates superconducting regions. Furthermore, the concept and first stages of a more complex ‘Rutherford’ cable architecture are presented. Additionally, Section I investigates how waste material produced during the manufacture of an alternative low-AC loss cable design, the Roebel cable, can be used to make trapped field magnets that produce a uniform magnetic field profile over a large area. This trapped field magnet work is extended to study self-supporting soldered stacks of HTS tape that demonstrate unprecedented magnetic field uniformity. Section II looks at how nanostructuring porous SOFC electrodes via solution infiltration of precursors can improve long-term stability and low temperature performance. Inkjet printing is utilised as a scalable, low-cost technique to infiltrate lab-scale and commercial samples. Anode infiltration via inkjet printing is demonstrated and methods to increase nanoparticle loading beyond ~1 wt% are presented. Symmetric cells with infiltrated cathodes are shown to have improved performance and stability during high temperature aging. Additionally, the sequence of solution infiltration is found to be important for samples dual-infiltrated with two different nanoparticle precursors.
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Arregui, Buldain Amaia. "Stability studies of critical components in SOFC technologies." Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368096.
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The present thesis work focuses on the stability of intermediate temperature SOFC technologies and it is divided in two parts: (i)cathode stability in anode-supported cells and (ii)fabrication and operation of tubular metal supported SOFCs.
In the first part, the stability of ferritic perovskite cathodes currently implemented at IK4-Ikerlan and SOFCpower (LSF-SDC and LSCF-GDC, respectively) was studied in a specific experimental DoE design. The influence of cathode processing and operation conditions together with intrinsic degradation mechanisms and extrinsic ones related to chromium poisoning and air humidification were analyzed in detail. Moreover, the effectiveness of two interconnect coating materials, MCO spinel and novel LNC perovskite against chromium poisoning of the cathode was studied. With this commitment, anode-supported half-cells manufactured by SOFCpower were used making profit of the verified high reproducibility of these cells.
In parallel, work at IK4-Ikerlan in tubular MSC technology demonstrated critical instability related to the operation under high fuel utilization and deficient diffusion barrier layer (DBL) implementation. This allowed element interdiffusion during the manufacturing process between the metal support and the anode. In the second part of this thesis work, a second generation (G2) of tubular MSCs based on an innovative DBL has been developed in all aspects. This includes processing parameters optimization and stability studies. During this work, an intrinsic variable degradation mechanism related to the DBL and manufacturing process of MSC turned out to be critical in G2 cells stability during operation. At this point, understanding such a mechanism and determining its origin became the most fascinating challenge of my investigation.
Overall, this thesis work focuses in the study of critical parameters in SOFCs stability. Factors affecting the stability of cell components over a wide range of operation conditions and degradation mechanisms related to the manufacturing process and operation are considered in detail.
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Arregui, Buldain Amaia. "Stability studies of critical components in SOFC technologies." Doctoral thesis, University of Trento, 2013. http://eprints-phd.biblio.unitn.it/974/1/Doctoral_thesis_Amaia_Arregui_Buldain.pdf.
Full textAbstract:
The present thesis work focuses on the stability of intermediate temperature SOFC technologies and it is divided in two parts: (i)cathode stability in anode-supported cells and (ii)fabrication and operation of tubular metal supported SOFCs.
In the first part, the stability of ferritic perovskite cathodes currently implemented at IK4-Ikerlan and SOFCpower (LSF-SDC and LSCF-GDC, respectively) was studied in a specific experimental DoE design. The influence of cathode processing and operation conditions together with intrinsic degradation mechanisms and extrinsic ones related to chromium poisoning and air humidification were analyzed in detail. Moreover, the effectiveness of two interconnect coating materials, MCO spinel and novel LNC perovskite against chromium poisoning of the cathode was studied. With this commitment, anode-supported half-cells manufactured by SOFCpower were used making profit of the verified high reproducibility of these cells.
In parallel, work at IK4-Ikerlan in tubular MSC technology demonstrated critical instability related to the operation under high fuel utilization and deficient diffusion barrier layer (DBL) implementation. This allowed element interdiffusion during the manufacturing process between the metal support and the anode. In the second part of this thesis work, a second generation (G2) of tubular MSCs based on an innovative DBL has been developed in all aspects. This includes processing parameters optimization and stability studies. During this work, an intrinsic variable degradation mechanism related to the DBL and manufacturing process of MSC turned out to be critical in G2 cells stability during operation. At this point, understanding such a mechanism and determining its origin became the most fascinating challenge of my investigation.
Overall, this thesis work focuses in the study of critical parameters in SOFCs stability. Factors affecting the stability of cell components over a wide range of operation conditions and degradation mechanisms related to the manufacturing process and operation are considered in detail.
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Silva, Gabriel Magalhães e. "Síntese e propriedades de cerâmicas de LaxSr1-xCryFe1-y(Mn1-y)O3-δ para aplicações em célula de combustível e catalisadores." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-19092018-155147/.
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O mundo moderno é extremamente dependente de combustíveis fósseis como fonte de energia primária e essa forte dependência leva a problemas políticos, econômicos e ambientais. Como possível solução a esses problemas tem-se as células combustíveis, pois são dispositivos que geram energia elétrica limpa diretamente de reações eletroquímicas produzindo, além da energia elétrica, apenas calor e água. Logo, percebe-se que essas células são fontes de energia confiáveis, renováveis e não poluentes, que contribuem para o desenvolvimento sustentável. Devido a isso, este trabalho teve como objetivo principal a síntese (por um método inédito) e a caracterização de materiais porosos a base de cromita de lantânio, LaxSr1-xCryFe1-y(Mn1-y)O3-?, para possível implementação como material de anodo e catodo de célula a combustível de óxido sólido (SOFC). Particularmente, estudos com anodos nos quais o transporte eletrônico é feito por materiais cerâmicos ao invés de metais são a área mais promissora na pesquisa recente. Além disso, materiais a base de manganita de lantânio dopadas com estrôncio são na atualidade os materiais mais usados na construção do catodo da SOFC. Nesta tese os materiais foram sintetizados pelo método sol-gel com agentes direcionador e dilatador de estrutura, resultando em materiais porosos em forma de esponja e com a estrutura perovskita, porém com fases espúrias. Foi estudada a influência do processamento de calcinação e de dopagem sobre as estruturas cristalográficas e porosas dos materiais. A maior temperatura de calcinação favoreceu a formação da estrutura perovskita com a retenção da fase romboédrica e reduziu a presença das fases espúrias, porém reduziu a porosidade, principalmente dos menores mesoporos, e a área superficial dos materiais. Por outro lado, ao dopar o sítio B os materiais com 75 %mol de La e calcinação a 1000 °C, observou-se a formação de um maior volume de mesoporos, ao mesmo tempo, que produziu uma maior quantidade de mesoporos menores e favoreceu a retenção da fase romboédrica da estrutura perovskita. Quanto ao comportamento eletrocatalítico, as células com eletrodos confeccionados a partir de La0,33Sr0,66Cr0,33Mn0,33O3-? apresentaram os melhores resultados tanto para anodo como para catodo entre as amostras avaliadas na tese. Além do mais, foram obtidos dois materiais, um cerâmico (La0,33Sr0,66Cr0,33Mn0,33O3-?) e um compósito cerâmico (La0,33Sr0,66Cr0,33Mn0,33O3-? + ZrO2 8%mol Y2O3) bons candidatos a catodo da SOFC. Esses materiais possuem uma composição química não encontrada na literatura para tal finalidade, ou seja, são inéditos.The modern world is extremely dependent on fossil combustibles as primary source of energy and, this dependence brings political, economic and ambient problems. As a possible solution to these problems are the fuel cells, because they are devices that generate clean electric energy directly from electrochemical reactions, producing besides electric energy, heat and water. Therefore, these cells are reliable, renewable and non-pollutant sources, that contribute to the sustainable development. Related to it, this work had the main goal the synthesis (by a new method) and characterization of porous materials based on lanthanum chromite, LaxSr1-xCryFe1-y(Mn1-y)O3-?, for possible use as anode and cathode material of Solid Oxide Fuel Cell (SOFC). In particular, studies of anodes in which the electronic transport is performed by ceramic materials instead of metals are the most promising recent research area. Moreover, materials based on lanthanum manganite doped with strontium are now a days the more used materials for SOFC cathodes. In this thesis, the materials were synthesized by the sol-gel method with directing and swelling structure agents, resulting in porous sponge materials with perovskite structure, but having spurious phases. The influence of the calcination and doping of the materials upon the crystallographic and porous structures were studied. Higher calcination temperature favored the formation of the perovskite structure and reduced the presence of spurious phases, but reduced the porosity, mainly of smaller mesopores and the surface area. On the other hand, doping the B site in materials with 75 %mol of La and the calcination at 1000 oC produced a higher mesopore volume, a higher amount of small mesopores and favored the retention of the rhombohedral perovskite structure. Regarding the catalytic behavior, the cells with electrodes of La0,33Sr0,66Cr0,33Mn0,33O3-? presented the best results as anode and cathode among the evaluate samples. Moreover, two materials were obtained, a ceramic one, (La0,33Sr0,66Cr0,33Mn0,33O3-?) and a ceramic composite, (La0,33Sr0,66Cr0,33Mn0,33O3-? + ZrO2 8%mol Y2O3), good candidates as SOFC cathodes. These materials have a chemical composition, which were not reported in the literature for this application, being unique.
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Sá, Anderson Moreira. "Desenvolvimento de materiais catódicos para células a combustível de óxido sólido (SOFC)." Universidade Federal da Paraíba, 2016. http://tede.biblioteca.ufpb.br:8080/handle/tede/8497.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Fuel cells (FC) are electrochemical devices that convert chemical energy from certain fuels into electrical energy, through oxidation-reduction reactions. They have a basic structure consisting of an electrolyte layer intercalating two electrodes: the cathode (positive electrode) and anode (negative electrode). In this work, cathode materials for solid oxide fuel cells (SOFC) were developed, such as lanthanum cobaltite doped with strontium and iron (La0,6Sr0,4Co0,2Fe0,8O3-8-LSCF6428) was synthesized by the modified polymeric precursors method, also known as modified Pechini method and compared the performance with the composite electrodes La0,6Sr0,4Co0,2Fe0,8O3-8/Ce0,9 Gd0,1O2-8 (LSCF6428/ CGO) and La0,6Sr0,4Co0,2Fe0,8O3-8/Ce0,9Gd0,1O2-8/Prox (LSCF6428/CGO/PROX). The method of synthesis consists in the use of commercial gelatin as polymerizing agent for metal ions. The powder obtained at 350 ° C / 2h was calcined at 800 and 1000 ° C / 4h and characterized by thermal gravimetric analysis (TG), particle size distribution, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The films of (LSCF6428), (LSCF6428 / CGO) and (LSCF6428 / CGO / PROX) were obtained by serigraph of calcined powders at 1000 ° C. The films were deposited on ceria substrates doped with gadolinia Ce0,9Gd0,1O2-8(CGO), sintered at 1150°C and characterized by impedance spectroscopy (in pure oxygen) between 600 and 800°C. The obtained results indicated that the method used was efficient in the formation of porous powders and with the perovskite crystalline structure. The crystallite size for the composite of LSCF6428 / CGO was of 336 (nm) for the LSCF6428 and 98 (nm) for the CGO, being also the expected for a powder calcined at 1000 ° C. The value of the area specific resistance (ASR) for the electrode of pure LSCF6428 at 750 ° C was of 0.25 ohms.cm2 quite plausible, especially because it was not made use of platinum, for the LSCF/CGO/ Prox was obtained an ASR of 0.02 ohms.cm2 at 750 ° C.
As células a combustível (CaC) são dispositivos eletroquímicos que transformam a energia química de determinados combustíveis em energia elétrica, por meio de reações de oxirredução. Possuem uma estrutura básica que consiste em uma camada de eletrólito intercalando dois eletrodos: cátodo (eletrodo positivo) e anodo (eletrodo negativo). Neste trabalho, foram desenvolvidos materiais catódicos para células a combustíveis de óxidos sólidos (SOFC), tais como, a cobaltita de lantânio dopada com estrôncio e ferro (La0,6Sr0,4Co0,2Fe0,8O3-δ – LSCF6428) foi sintetizado pelo método dos precursores poliméricos modificado, também conhecido como Pechini modificado e comparado o desempenho com o de eletrodos compósitos La0,6Sr0,4Co0,2Fe0,8O3-δ/Ce0,9Gd0,1O2-δ (LSCF6428/CGO) e La0,6Sr0,4Co0,2Fe0,8O3-δ/ Ce0,9Gd0,1O2-δ/PrOx (LSCF6428/CGO/PrOx). O método de síntese consiste na utilização da gelatina comercial como agente polimerizante para íons metálicos. O pó obtido a 350 °C/ 2h foi calcinado a 800 e 1000 °C/ 4h e caracterizados por analise termogravimétrica (TG), distribuição de tamanho de partícula, difração de raio X (DRX) e microscopia eletrônica de varredura (MEV). Os filmes de (LSCF6428), (LSCF6428/CGO) e (LSCF6428/CGO/PrOx), foram obtidos por serigrafia de pós calcinados a 1000 °C. Os filmes foram depositados sobre substratos de céria dopada com gadolínia Ce0,9Gd0,1O2-δ (CGO), sinterizados a 1150 °C e caracterizados por espectroscopia de impedância (em oxigênio puro) entre 600 e 800 °C. Os resultados obtidos indicaram que o método utilizado foi eficiente na formação de pós porosos e com a estrutura cristalina perovskita. O tamanho de cristalito para o compósito de LSCF6428/CGO foi de 336 (nm) para o LSCF6428 e 98 (nm) para o CGO, sendo, também o esperado para um pó calcinado a 1000 °C. O valor da resistência específica de área (REA) para o eletrodo de LSCF6428 puro a 750 °C foi de 0,25 ohms.cm2 bastante plausível, principalmente por não ter sido feito uso de platina, para o LSCF/CGO/PrOx foi obtido uma REA de 0,02 ohms.cm2 a 750 °C.
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Leite, Douglas Will. "Obtenção do cermet Ni-ZrO2 por moagem de alta energia." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-01082011-142900/.
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A obtenção do Cermet de níquel-zircônia via moagem de alta energia (Mechanical Alloying MA) foi estudado visando a preparação de anodos de células a combustível de óxido sólido (SOFC). O níquel metálico foi adicionado em três concentrações: 30, 40 e 50% em volume. As operações de moagem foram conduzidas em moinho vibratório de alta energia do tipo SPEX. Estudou-se a influência do tempo de moagem, a eficiência de aditivos para controle do processo, tipo e geometria dos potes de moagem. A influência destas variáveis foram avaliadas através de análises de tamanho de partículas, determinação de área superficial e morfologia do material resultante. O uso de pote de teflon resultou em contaminação por carbono. Por outro lado, o uso de pote de aço aumenta a contaminação por impurezas metálicas. As diversas geometrias projetadas para os potes mostraram que potes com maiores raios de concordância (R.15) apresentaram melhor rendimento. Após a conformação e sinterização a 1300°C em atmosfera de argônio, as amostras apresentaram valores de densidade entre 60 a 80% da densidade teórica. As microestruturas observadas por microscopia eletrônica de varredura revelaram uma boa homogeneidade na distribuição de fases do Cermet. A técnica de moagem de alta energia apresentou-se como boa opção na fabricação de Cermet Ni-ZrO2.The ZrO2 and metallic Ni Cermet obtained by Mechanical Alloying MA is studied in the present work with the objective to prepare solid oxide fuel cells anodes (SOFC). Metallic Ni is added under three different concentrations: 30, 40 and 50% volume. The millings were conducted in SPEX vibratory mill where the influence of milling time, process control additives efficiency, type and geometry of milling vessels were studied. The study of the influence of these variables was made under particle size analysis, surface area determination and resulting material morphology. The use of teflon vessel causes contamination by carbon. On the other side, steel vessel increases the contamination by metallic impurities. The several geometries projected and analyzed for the vessels showed that vessels with larger bottom radius (R.15) showed the best results. After conformation and sintering at 1300°C in argon atmosphere the samples reached densities between 60 and 80% of the theoretical density. Microstructures observed by scanning electron microscopy reveal good homogeneity in the Cermet phases distribution. The mechanical alloying technique was considered a good option to obtain Ni- ZrO2 Cermet.
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Haag, Florian [Verfasser]. "Kohlenstoffbildung und -detektion in erdgasbetriebenen SOFC-Systemen / Florian Haag." Aachen : Shaker, 2015. http://d-nb.info/1080762841/34.
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Diegelmann, Christian B. "Potenzial einer SOFC-APU bei der Verbrauchsoptimierung von Kraftfahrzeugen." kostenfrei, 2008. http://mediatum2.ub.tum.de/doc/653487/653487.pdf.
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Rooker, William E. "Enhancing the thermal design and optimization of SOFC technology." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/18881.
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Krüger, Michael [Verfasser]. "Verfahrensentwicklung für SOFC-Hybridkraftwerke mit integrierter Kohlevergasung / Michael Krüger." München : Verlag Dr. Hut, 2013. http://d-nb.info/1033041319/34.
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Garcia-Vargas, Maria José. "Oxidation behaviour of potential materials for metallic SOFC interconnects." Lille 1, 2006. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2006/50376_2006_208.pdf.
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Les interconnecteurs de SOFC à haute température ont deux rôles principaux: la connexion électrique entre les cellules et l'approvisionnement des gaz dans le stack. Ce travail porte sur l'étude d'interconnecteurs métalliques pour SOFC fonctionnant à une température d'environ 800°e. Deux matériaux austénitiques et trois ferritiques, ayant un pourcentage de Cr compris entre 17% et 27%, ont été sélectionnés pour étudier le comportement en oxydation dans différentes atmosphères. Une étude par diffraction des rayons-X (ORX) du comportement d'oxydation de ces matériaux à 800°C a été réalisée pendant les premières 100 h sous air sec et humide. Des essais d'oxydation à moyen terme (1000 h) ont été de plus réalisés. Chaque échantillon a été caractérisé microscopiquement après les essais d'oxydation à temps court et à moyen terme. Pour éviter le problème de la migration du chrome, montré par les études précédentes sur ce type de matériaux, deux couches protectrices de type spinelle ont été développées. Ensuite, quelques échantillons ont été recouverts avec ces couches de protection en utilisant la projection au plasma atmosphérique (APS). Des essais d'oxydation à moyen terme ont été réalisés, sans montrer de migration du chrome à travers la couche de protection. Finalement trois interconnecteurs, avec ou sans une couche de protection, ont été essayés sur la cathode d'une cellule. Les interconnecteurs et les cellules ont été analysées par MEB, après chaque test.
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Elmer, Theo. "A novel SOFC tri-generation system for building applications." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/30516/.
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In response to the critical need to decarbonise the built environment, alternative methods for more effective energy utilisation need to be explored including tri-generation systems. Tri-generation is the simultaneous generation of electricity, heating and/or cooling from a single fuel source. Solid oxide fuel cell (SOFC) and liquid desiccant demonstrate many characteristics that make them an attractive option in the development of an efficient and effective tri-generation system. SOFCs have high operational electrical efficiencies and a thermal output in good agreement with the low temperature regeneration requirement of liquid desiccants. The aim of this thesis is to design, develop and test an efficient and effective proof of concept tri-generation system based on SOFC and liquid desiccant air conditioning technology for building applications. An extensive review of the literature shows that no previous work has been reported on such a system. The research has critically examined, both theoretically and experimentally, the novel tri-generation system concept. Simulations show tri-generation system efficiencies of up to 71% are achievable at a 1.5kWe capacity, which are encouraging values for a system of this size. An integration analysis, based on empirical data, provides good agreement with the simulations. At a 1.5kWe output, a tri-generation efficiency of 69% has been demonstrated. The inclusion of liquid desiccant air conditioning provides an efficiency increase of up to 15% compared to SOFC electrical operation only, demonstrating the merit of the novel tri-generation system in applications that require simultaneous electrical power, heating and dehumidification/cooling. An experimental system, using a micro-tubular SOFC shows the novel system can generate 150W of electrical power, 443W of heat or 279W of cooling. Instantaneous tri-generation system efficiency is low at around 25%. This is primarily due to the low capacity and poor performance of the micro-tubular SOFC. Although the performance is low, the experimental results demonstrate regeneration of a potassium formate desiccant solution using the thermal output from the micro-tubular SOFC in the first of its kind tri-generation system. The thesis has established that a clear operational advantage of the novel SOFC liquid desiccant tri-generation system is the potential for nonsynchronous operation. The constant SOFC thermal output can be used to re-concentrate the desiccant solution as a form of thermal energy storage. Unlike thermal storage techniques based on sensible energy, a significant advantage of (chemical) thermal energy storage in the form of strong desiccant solution is that there are minimal losses over time. Using this nonsynchronous operating concept, the experimental system can generate an increased peak cooling output of up to 527W and a daily tri-generation efficiency of 38%. An economic assessment demonstrates questionable performance; however this is anticipated to improve with SOFC capital cost reductions. Environmental assessments establish that emission reductions of up to 51% compared to a base case system are possible, with the potential for zero carbon operation with the transition to a pure hydrogen fuel. The thesis presents the following general conclusions with respect to the novel SOFC liquid desiccant tri-generation system: (1) SOFC and liquid desiccant air conditioning are an effective technological pairing. High tri-generation efficiencies, particularly in hot and humid climates, are demonstrated; (2) appropriate matching of component capacity is necessary. Overall tri-generation system performance is more influenced by the SOFC component than the liquid desiccant; and (3) it is primarily the optimisation of the liquid desiccant component that facilitates effective tri-generation system integration and operation. The thesis proposes that future work should focus on improving the thermal agreement between the SOFC and liquid desiccant component, accompanied by field trial testing in a building context.
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Baumann, Frank Stephan. "Oxygen reduction kinetics on mixed conducting SOFC model cathodes." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-27056.
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Slippey, Andrew J. "Dynamic modeling and analysis of multiple SOFC system configurations /." Online version of thesis, 2009. http://hdl.handle.net/1850/10834.
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Geromel, Prette Andre Luiz. "Sintering of Co2MnO4 spinel for protective coatings in SOFC." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/367848.
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Protective coatings are often deposited on SOFC interconnectors to avoid poisoning of cathode from chromium species that evaporate from stainless steel interconnects or supports. Co2MnO4 spinel compounds are usually considered as the main constituent of protection barriers. Nevertheless, such ceramic sinters at high temperatures (>1200°C) and this can be problematic for the properties of the stainless steel components. One of the major issues is, in fact, the creation of a compact and impermeable coating at relatively low temperature in order to preserve the metal substrate. In the present research work, Co2MnO4 spinel was synthesized by various methods (solid-state, gel-combustion, co-precipitation and reverse micelle) and the obtained specific surface area, structure and particle size were correlated with thermal behaviour, sintering temperature and achieved density. It was found that regardless the synthesis process the only obtained phase is Co2MnO4. Specific surface area from 0,8 to 65 m2g-1 was obtained, depending on the synthesis method.
Sintering aids such as Nb2O5 and LiF were used to obtain dense microstructure at relatively low temperature. Considerable changes in sintering temperature were observed this being even 100-200ºC lower than that necessary for the consolidation of pure spinel though microstructure with only close pores was achieved.
A novel sintering method based on Field Assisted Techniques (FAST) that promoted flash-sintering phenomenon was finally applied to Co2MnO4. Small electric field (<7,5 V cm-1) applied to the spinel decreases the sintering temperature down to 600°C. The application of an electric field above 7,5 V cm-1 flash-sintering phenomenon takes place and sintering temperature drops to about 300°C, the sintering time being less than 1 second.
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Geromel, Prette Andre Luiz. "Sintering of Co2MnO4 spinel for protective coatings in SOFC." Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/542/1/Prette_Tesi_PhD_PDF.pdf.
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Protective coatings are often deposited on SOFC interconnectors to avoid poisoning of cathode from chromium species that evaporate from stainless steel interconnects or supports. Co2MnO4 spinel compounds are usually considered as the main constituent of protection barriers. Nevertheless, such ceramic sinters at high temperatures (>1200°C) and this can be problematic for the properties of the stainless steel components. One of the major issues is, in fact, the creation of a compact and impermeable coating at relatively low temperature in order to preserve the metal substrate. In the present research work, Co2MnO4 spinel was synthesized by various methods (solid-state, gel-combustion, co-precipitation and reverse micelle) and the obtained specific surface area, structure and particle size were correlated with thermal behaviour, sintering temperature and achieved density. It was found that regardless the synthesis process the only obtained phase is Co2MnO4. Specific surface area from 0,8 to 65 m2g-1 was obtained, depending on the synthesis method.
Sintering aids such as Nb2O5 and LiF were used to obtain dense microstructure at relatively low temperature. Considerable changes in sintering temperature were observed this being even 100-200ºC lower than that necessary for the consolidation of pure spinel though microstructure with only close pores was achieved.
A novel sintering method based on Field Assisted Techniques (FAST) that promoted flash-sintering phenomenon was finally applied to Co2MnO4. Small electric field (<7,5 V cm-1) applied to the spinel decreases the sintering temperature down to 600°C. The application of an electric field above 7,5 V cm-1 flash-sintering phenomenon takes place and sintering temperature drops to about 300°C, the sintering time being less than 1 second.
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Azzolini, Andrea. "Production and performance of Cu-based anode-supported SOFC." Doctoral thesis, Università degli studi di Trento, 2014. https://hdl.handle.net/11572/368614.
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Tubular SOFCs were produced by extrusion of the supporting anode composed by GDC10 and Cu oxides. A 10 μm thin GDC10 electrolytic layer and the LSF20:GDC10 cathode were deposited by dip-coating and the complete cell was co-sintered in one step. Thanks to the optimization of the composition and the employment of Li2O as sintering aid, the densification of the electrolyte was accomplished more than 500°C below the sintering temperature of GDC10. The cell had a maximum OCV of 0.54 V and the highest measured power density was 8.98 mW cm-2 with a peak power density projected to be 27.5 mW cm-2.
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Azzolini, Andrea. "Production and performance of Cu-based anode-supported SOFC." Doctoral thesis, University of Trento, 2014. http://eprints-phd.biblio.unitn.it/1356/1/Production_and_performance_of_Cu-based_anode-supported_SOFC.pdf.
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Tubular SOFCs were produced by extrusion of the supporting anode composed by GDC10 and Cu oxides. A 10 μm thin GDC10 electrolytic layer and the LSF20:GDC10 cathode were deposited by dip-coating and the complete cell was co-sintered in one step. Thanks to the optimization of the composition and the employment of Li2O as sintering aid, the densification of the electrolyte was accomplished more than 500°C below the sintering temperature of GDC10. The cell had a maximum OCV of 0.54 V and the highest measured power density was 8.98 mW cm-2 with a peak power density projected to be 27.5 mW cm-2.
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Guesnet, Laura. "Développement de nouvelles architectures de piles à combustible SOFC tout cérine pour un fonctionnement à température réduite." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0218.
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En employant de nouvelles architectures de cellules à oxyde solide (SOC - Solid Oxide Cells), il est possible d’en réduire la température de fonctionnement. L’objectif de cette thèse a donc été d’élaborer des mises en forme innovantes afin de diminuer le nombre d’étapes nécessaires à la fabrication de la cellule, permettant aussi d’en diminuer le coût : l’élaboration d’un support poreux/dense/poreux tout coulage en bande puis infiltration de catalyseurs pour l’obtention des électrodes est le procédé retenu. Le support poreux/dense/poreux a été exclusivement préparé à base de GDC10 (Ce0,9Gd0,1O2-δ) pour éviter les problèmes de réactivité entre les différentes couches. Au cours de cette thèse, deux méthodes de mises en forme ont été utilisées successivement: pressage/sérigraphie/infiltration (1) puis coulage en bande/infiltration (2). Dans chacun des cas, les paramètres de mises en forme ont été optimisés dans le but d’obtenir les meilleures performances électrochimiques. La méthode de mise à forme (1) a déjà fait l’objet d’une partie de thèse à l’ICMCB côté oxygène, mais elle a été perfectionnée côté hydrogène : couche de collectage, nature du catalyseur (NiO, CuO, cérine dopée yttrium), taux d’infiltration. Pour diminuer le nombre de cycles nécessaires et améliorer la qualité de l’imprégnation, une nouvelle technique a été employée : l’infiltration par voie supercritique. Dans le cas de la mise en forme (2), les paramètres propres à l’élaboration de la suspension (nature des additifs, nature des billes/jarre employées) et à celle des supports poreux/dense/poreux (cycles de déliantage/frittage) ont permis d’obtenir des résistances de polarisation très proches de celles obtenues grâce à la mise en forme (1), en dépit de résistances séries encore élevées sans doute en lien avec de pollutions résiduelles carbonées. Les paramètres finalement retenus sont : un dispersant de type ester phosphorique, 90% de graphite ajouté pour réaliser les squelettes poreux, un déliantage conduit à 800°C/6h sous O2 humide, et un frittage de l’ensemble à 1450°C/3hWhen involving new solid oxide cells (SOCs) architectures, it’s possible to reduce their operating temperature. The objective of this thesis was therefore to develop innovative shaping processes in order to reduce the cell manufacturing steps number, also allowing to reduce their cost : the preparation of a porous/dense/porous support by tape-casting, then the infiltration of catalysts to obtain the electrodes was the chosen process. The porous/dense/porous support was only prepared with GDC10 (Ce0.9Gd0.1O2-δ) to avoid chemical reactivity issues between the various layers. During this thesis, two shaping methods were successively used: pressing/screen-printing/infiltration (1) then tape-casting/infiltration (2). In each case, the shaping parameters have been optimized in order to obtain the best electrochemical performances. The shaping method (1) was already part of a thesis topic at ICMCB regarding the oxygen side of the SOC, but it has been here improved regardin the hydrogen side: the collecting layer, the catalyst nature (NiO, CuO, yttrium doped ceria), infiltration rate. To reduce the number of required cycles and improve the impregnation quality, a new technique was used: the infiltration in supercritical medium. In the case of shaping (2), the specific parameters of the i) suspension preparation (additives nature, nature of the used balls/jar) and of the ii) porous/dense/ porous supports (debinding/sintering cycles) have made it possible to obtain polarization resistances very close to those obtained by shaping (1), despite slightly higher series resistances, probably in linkto some remaining carbon pollution. The parameters finally retained are: a phosphoric ester type dispersant, 90% of graphite added to shape the porous skeletons, a debinding performed at 800°C/6h under wet O2, and a whole sintering at 1450°C/3h
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Hughes, Dimitri O. "A hardware-based transient characterization of electrochemical start-up in an SOFC/gas turbine hybrid environment using a 1-D real time SOFC model." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41229.
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Solid oxide fuel cell/gas turbine (SOFC/GT) hybrid systems harness the capability to operate nearly 15 to 20 percentage points more efficiently than standard natural gas or pulverized coal power plants. Though the performance of these systems is quite promising, a number of system integration challenges, primarily with regards to thermal transport, still remain. It is for that reason that the Hybrid Performance Project (HyPer) facility, a Hardware-in-the-Loop SOFC/GT hybrid simulator, was built at the National Energy Technology Laboratory in Morgantown, WV. The HyPer facility couples an actual gas turbine with a combination of hardware and software that are used to simulate an actual SOFC. The facility is used to empirically address the system integration issues associated with fuel cell/gas turbine hybrids. Through this dissertation project, the software component of the SOFC simulator was upgraded from a 0-D lumped SOFC model to a 1-D, distributed, real-time operating SOFC model capable of spatio-temporal characterization of a fuel cell operating with a gas turbine in a hybrid arrangement. Once completed and verified, the upgraded HyPer facility was used to characterize the impact of cold air by-pass and initial fuel cell load on electrochemical start-up in an SOFC/GT hybrid environment. The impact of start-up on fuel cell inlet process parameters, SOFC performance and SOFC distributed behavior are presented and analyzed in comparative manner. This study represents the first time that an empirical parametric study, characterizing system operation during electrochemical start-up has been conducted.
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Monaco, Federico. "Analyse de la dégradation des cellules à oxydes solides fonctionnant en mode pile à combustibles et électrolyse : évolution microstructurale et stabilité des matériaux d'électrodes." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALI034.
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Ce travail a été dédié à l’étude de la dégradation des piles à oxyde solide fonctionnant en mode électrolyse et pile à combustibles. Une approche intégrée couplant (i) des caractérisations électrochimiques, (ii) des analyses post-test avancées et (iii) une modélisation multi-échelle a été adoptée. Des tests de longue durée ont été menés avec des cellules standards (Ni YSZ/YSZ/GDC/LSCF) pour évaluer la dégradation des performances en fonction des conditions de fonctionnement. Des échantillons, extraits de cellules initiales et après test, ont été finement caractérisés pour déterminer les évolutions microstructurales et physico-chimiques des deux électrodes en fonctionnement. En outre, des modèles de cinétiques élémentaires ont été développés et validés expérimentalement pour l’électrode à hydrogène (cermet Ni-YSZ) et pour l’électrode à oxygène (LSCF/LSCF-GDC) avant d’être intégrés dans un modèle de cellule à l'échelle macroscopique. L'outil numérique multi-échelle a été utilisé pour étudier les mécanismes sous-jacents contrôlant les phénomènes de dégradation. Par ailleurs, leurs effets sur les performances de la cellule en fonction des conditions de fonctionnement ont été évalués et discutés grâce au modèle. Sur la base des résultats présentés dans ce travail, il a été confirmé que la dégradation des SOCs est nettement plus importante en mode électrolyse par rapport à un fonctionnement en pile à combustibles fonctionnant sous H2. Cette différence peut être attribuée d’une part, à l'effet des surtensions cathodiques sur l'instabilité du nickel dans l’électrode à hydrogène. D’autre part, il a été observé et démontré que la déstabilisation du LSCF est favorisée sous fort courant anodique à haute températureThis work was dedicated to the analysis of the degradation of solid oxide cells operated in electrolysis and fuel cell modes. A threefold methodology has been applied by coupling (i) electrochemical tests, (ii) advanced post-test analyses and (iii) multi-scale modeling. Long-term durability experiments have been carried out on standard cells (Ni-YSZ/YSZ/GDC/LSCF) to investigate the performance loss as a function of the operating conditions. Specimens, which have been extracted from the pristine and aged samples, have been characterized to evaluate the microstructural and physico-chemical evolutions occurring at the two electrodes. In parallel, detailed micro-kinetic models for the hydrogen electrode (Ni-YSZ cermet) and for the oxygen electrode (LSCF/LSCF-GDC) have been developed and experimentally validated before being integrated into a macro-scale model for the complete cell. The multi-scale numerical tool has been used to propose a better understanding of the underlying forces driving the degradation. Moreover, the impact on the cell performances has been simulated and discussed as a function of the operating conditions. Based on the results presented in this work, it has been confirmed that the degradation of SOCs is significantly larger in electrolysis mode with respect to fuel cell operation under H2. On the one hand, it has been shown that the difference in durability behavior can be ascribed to the effect of the cathodic overpotential on the nickel instability in the hydrogen electrode. On the other hand, it has been observed and demonstrated that the destabilization of the LSCF is favored by both the anodic current and the high operating temperature
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Chen, Ming. "Understanding the thermodynamics at the LaMnO₃-YSZ interface in SOFC /." Zürich : ETH, 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16146.
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Stiller, Christoph. "Design, Operation and Control Modelling of SOFC/GT Hybrid Systems." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-718.
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This thesis focuses on modelling-based design, operation and control of solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid systems. Fuel cells are a promising approach to high-efficiency power generation, as they directly convert chemical energy to electric work. High-temperature fuel cells such as the SOFC can be integrated in gas turbine processes, which further increases the electrical efficiency to values up to 70%. However, there are a number of obstacles for safe operation of such a system, such as fuel cell damage through thermal loads or undesired chemical reactions, or gas turbine problems related to high thermal capacity and volume of the pressurised components. Development of suitable plant design as well as operation and control strategies is hence a key task for realisation of the mentioned systems.
The first part of the thesis describes the utilised models. All component models that have been developed and applied for the work are mathematically defined based on a fixed pattern. The thermodynamically most relevant components are tubular SOFC, indirect internal reformer and heat exchangers, and spatially discretised models are used for these. For the turbomachinery, map-based steady-state behaviour is modelled. Gas residence times and pressure drops are accounted for in all components they are relevant.
Based on the component models, three different hybrid cycles are examined. In the first cycle, the SOFC replaces the combustion chamber of a recuperated single-shaft turbine. The SOFC is pressurised and the cycle is called “directly integrated SOFC cycle” (DIC). Further cycle options are a DIC with a two-shaft gas turbine (DIC-2T) and an indirectly integrated SOFC cycle (IIC). In the latter, the compressed gas is heated recuperatively with the exhaust gas and the SOFC is operated at ambient pressure by connecting its air inlet to the turbine exhaust. All cycles incorporate the SOFC system design proposed by Siemens-Westinghouse, including indirect internal reforming, a tubular SOFC bundle and anode recirculation by an ejector. The first cycle (DIC) is regarded as standard cycle.
Objectives for highly efficient, safe system design are formulated and design parameters are associated. A design calculation determines the design parameters for the standard cycle, based on a nominal power output of 220 kW. The design LHVbased electric efficiency is app. 63%. Related to the design point, steady-state part-load ability of the system is analysed and displayed in two-dimensional performance maps where each axis represents one degree of freedom. Degrees of freedom considered are fuel and air flow; fuel utilisation is assumed constant. A result is that a strategy with constant mean fuel cell temperature is most advantageous in terms of safe and gentle operation. Further advantages of this strategy are the ability for low part-load and high efficiency at part-load operation.
A control strategy is derived for dynamical implementation of the found part-load strategy. The system power output is primarily controlled by the SOFC power. The fuel utilisation is kept within certain bounds and the fuel flow is manipulated to control it to its design value. The fuel cell temperature is controlled by the air flow, which again is controlled by manipulating the GT shaft speed through the generator power. To determine the required air flow, a mixed feedforward and feedback strategy is used, where the feedforward part calculates a prediction based on the net power output and the feedback part provides correction based on the measurement of the SOFC fuel outlet temperature. Additional constraints to the control system are the supervision of the shaft speed and the valid operation regime of the anode recirculation ejector.
The proposed control strategy provides robust control. The mean SOFC temperature, however, shows large transient deviation upon large load steps. The time to reach the setpoint power for large load steps is up to 70 s, while small load steps are followed in typically 1-2 s. A conclusion is that the system is suitable for load following operation as long as small load steps occur, as for example in distributed power generation for residential applications.
Shutdown and startup strategies are introduced where the gas turbine provides air for cooling/heating throughout the procedures. Additional equipment and piping such as an auxiliary burner, a turbine exhaust throttle, a bypass around the recuperative heat exchanger as well as nitrogen and hydrogen supply and mixing units are required. Therewith, smooth cooling/heating of the cell can be accomplished without external electric power, but with a considerable amount of fuel and flushing nitrogen required.
A further analysis investigates fuel flexibility of a system designed for methane: Hydrogen can be utilised without larger system modifications; only the control system characteristics must be adapted. Because no endothermic steam reforming takes place, the power output is, however, reduced to 70% of the original value, and efficiency is reduced to 55%. Applying the additional equipment required for shutdown/startup, the power can be increased to 94% of the original value, although at a further efficiency decrease. In order to use ethanol as fuel in the ejector-driven anode, a recuperative vaporiser must be applied in the fuel channel. Supposed that reliable reforming catalysts for ethanol can be provided, 88% of the original power output can be achieved at a high efficiency of 62%.
The investigation of the other cycle options reveals that a two turbine cycle where the power turbine is rotating at constant speed, mostly differs in terms of controllability. For controlling the air flow, another handle such as variable inlet guide vanes or air bypass around the SOFC system is required. The indirectly integrated SOFC cycle (IIC) has a significantly lower efficiency of only 56%, assuming the SOFC at the same temperature level than in the DIC.
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Stübner, Ralph. "Untersuchungen zu den Eigenschaften der Anode der Festoxid-Brennstoffzelle (SOFC)." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2002. http://nbn-resolving.de/urn:nbn:de:swb:14-1025078611046-09161.
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This thesis investigates the electrical and electrochemical properties and the long-term stability of anodes of the solid oxide fuel cell (SOFC). A model is suggested, which describes the impedance spectra of symmetrical anode cells. According to this, the series resistance in the spectra is caused by the resistance of the electrolyte (YSZ), ohmic parts of the anodes, which are described as porous electrodes, and by the partial contacting of the anodes. A major contribution to it is provided by the nickel matrix in the anodes. The high frequency relaxation in the spectra is assigned to the transfer reaction, the low frequency to a gas diffusion inhibition along the gas supply channels. The degradation of the symmetrical anode cells, which has been observed in long-term experiments, is ascribed to a degradation of the electrolyte material, of the transfer reaction, of the nickel matrix in the anodes and of the contact resistance between the anodes and the current collecting nickel grids. The degradation rate of the last two depends on the gas composition. A model for the observed behaviour in time is presentedDiese Arbeit untersucht die elektrischen und elektrochemischen Eigenschaften und die Langzeitbeständigkeit der Anoden von Festoxid-Brennstoffzellen (SOFC). Ein Modell wird vorgestellt, mit dem die Impedanzspektren symmetrischer Anodenzellen beschrieben werden können. Demnach ist der Serienwiderstand in den Spektren verursacht durch den Widerstand des Elektrolyten (YSZ), ohmsche Anteile in den Anoden, die als poröse Elektroden beschrieben werden, und durch die partielle Kontaktierung der Anoden. Maßgebliche Beiträge liefert hier die Nickelmatrix in den Anoden. Die hochfrequente Relaxation in den Spektren wird der Durchtrittsreaktion, die niederfrequente einer Gasdiffusionshemmung entlang der Gasversorgungskanäle zugeordnet. Die in Langzeitversuchen beobachtete Degradation der symmetrischen Anondenzellen wird zurückgeführt auf eine Degradation des Elektrolytmaterials, der Durchtrittsreaktion, der Nickelmatrix in den Anoden und des Kontaktwiderstandes zwischen den Anoden und den stromabnehmenden Nickelnetzen. Die Degradation der beiden letzteren ist in ihrer Rate abhängig von der Gaszusammensetzung. Ein Modell für das beobachtete zeitliche Verhalten wird vorgestellt
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Mücke, Robert. "Sinterung von Zirkoniumdioxid-Elektrolyten im Mehrlagenverbund der oxidkeramischen Brennstoffzelle (SOFC)." Jülich Forschungszentrum, Zentralbibliothek, 2007. http://bibpurl.oclc.org/web/32917.
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Morandi, Anne. "Intégration de matériaux oxydes innovants dans une cellule IT-SOFC." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00860737.
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Cette thèse vise à évaluer le potentiel d'un nouveau couple cathode / électrolyte pour une application en IT-SOFC (700°C), par le biais de l'élaboration et du test de cellules à anode support de configuration planaire. Les matériaux concernés sont l'électrolyte BaIn0.3Ti0.7O2.85 (BIT07), de structure perovskite, et les nickelates de terres rares Ln2-xNiO4+ (LnN, Ln = La, Nd, Pr) en tant que cathodes ; ces matériaux ont montré des propriétés prometteuses dans des travaux préliminaires effectués à l'IMN et l'ICMCB. La première partie de cette thèse porte sur la mise en place d'un protocole d'élaboration de cellules complètes utilisant des techniques bas coûts et industrialisables (cellules de taille 3 x 3 cm2) : l'anode Ni / BIT07 a été élaborée par coulage en bande, l'électrolyte BIT07 par vacuum slip casting et les cathodes par sérigraphie. Les mesures électrochimiques réalisées sur une première génération de cellules ont mis en évidence la nécessité d'ajouter une couche barrière de GDC entre les cathodes LnN et l'électrolyte BIT07. Les meilleures performances ont été obtenues pour une cellule BIT07 / Ni | BIT07 | GDC | PrN, avec une densité de puissance à 700°C et 0.7 V de 176 mW cm-2 pour une faible résistance de polarisation de 0. 29 Ω cm2. La principale limitation des performances a été identifiée comme étant la résistance interne du banc de test, donnant lieu à des valeurs de résistances séries anormalement élevées. Cette cellule a été opérée avec succès durant plus de 500 heures sous courant, avec néanmoins une vitesse de dégradation extrapolée élevée de l'ordre de 27% / kh.
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Dietrich, Ralph-Uwe [Verfasser]. "Aufbau und Erprobung eines propanbetriebenen SOFC-Systems / Ralph-Uwe Dietrich." Clausthal-Zellerfeld : Universitätsbibliothek Clausthal, 2013. http://d-nb.info/1033177008/34.
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San, Baogang. "Dynamic modelling of SOFC marine power systems and shipboard applications." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23156.
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Sustainable and efficient provision of shipboard energy is an obvious challenge for the merchant marine industry. Various initiatives have been made to find alternatives to replace the currently used combustion engine for ship power and propulsion. In recent years, fuel cell technology, as has been widely advertised as a clean and efficient means of power generation, is drawing much attention from the marine industry. Among various types of fuel cells, the Solid Oxide Fuel Cell (SOFC) tops others in terms of energy conversion efficiency as it can be fed with both hydrogen rich fuels and traditional fossil fuels after being chemically reformed. These features make it most promising to meet the large power demands of seagoing ships. However, due to the comprehensive and hazardous working environment, shipboard installation of SOFC power systems is not available. Can the SOFC be a viable proposition for commercial shipping and how will it behave under severe seagoing circumstances? These questions need to be addressed before commercialising SOFC marine power systems. In the thesis, simulation methods are used to predict the performance of marine SOFC systems at both static and dynamic working loads. A mathematical model is developed for describing the thermodynamic nature of a tubular SOFC concerning the thermal equilibrium of the system. Electric-chemical reactions are reflected in the stack modelling. Reforming reactions of the fuel are included in the model. Auxiliary subcomponents within the SOFC power system are modelled based on their own mechanisms and working principles. The whole simulation system is composed by combining subcomponent models via reasonable control strategies to function the system's purpose. SOFC power system models are developed to represent different working scenarios which may possibly occur onboard ship. The dynamic responses of simulation systems are examined. Thermal flow transfer influence, manifold volume influence and controller 's influence are also taken into account in the dynamic modelling process. As concluded from the simulation outcomes, the sample SOFC system, while running alone, could satisfy the demand of dynamic load change for both propulsion and auxiliary power. However, the electric output of the SOFC system would be greatly smoothed if paralleled with a battery. In addition, risk and safety issues regarding SOFC onboard installation are examined from both design and operating perspectives. Relevant ship rules and regulations for verifications of system installation and maintenance are reviewed in detail. Conceptual design of marine SOFC application are also proposed at the last stage.
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Stübner, Ralph. "Untersuchungen zu den Eigenschaften der Anode der Festoxid-Brennstoffzelle (SOFC)." Doctoral thesis, Technische Universität Dresden, 2001. https://tud.qucosa.de/id/qucosa%3A24154.
Full textAbstract:
This thesis investigates the electrical and electrochemical properties and the long-term stability of anodes of the solid oxide fuel cell (SOFC). A model is suggested, which describes the impedance spectra of symmetrical anode cells. According to this, the series resistance in the spectra is caused by the resistance of the electrolyte (YSZ), ohmic parts of the anodes, which are described as porous electrodes, and by the partial contacting of the anodes. A major contribution to it is provided by the nickel matrix in the anodes. The high frequency relaxation in the spectra is assigned to the transfer reaction, the low frequency to a gas diffusion inhibition along the gas supply channels. The degradation of the symmetrical anode cells, which has been observed in long-term experiments, is ascribed to a degradation of the electrolyte material, of the transfer reaction, of the nickel matrix in the anodes and of the contact resistance between the anodes and the current collecting nickel grids. The degradation rate of the last two depends on the gas composition. A model for the observed behaviour in time is presented.Diese Arbeit untersucht die elektrischen und elektrochemischen Eigenschaften und die Langzeitbeständigkeit der Anoden von Festoxid-Brennstoffzellen (SOFC). Ein Modell wird vorgestellt, mit dem die Impedanzspektren symmetrischer Anodenzellen beschrieben werden können. Demnach ist der Serienwiderstand in den Spektren verursacht durch den Widerstand des Elektrolyten (YSZ), ohmsche Anteile in den Anoden, die als poröse Elektroden beschrieben werden, und durch die partielle Kontaktierung der Anoden. Maßgebliche Beiträge liefert hier die Nickelmatrix in den Anoden. Die hochfrequente Relaxation in den Spektren wird der Durchtrittsreaktion, die niederfrequente einer Gasdiffusionshemmung entlang der Gasversorgungskanäle zugeordnet. Die in Langzeitversuchen beobachtete Degradation der symmetrischen Anondenzellen wird zurückgeführt auf eine Degradation des Elektrolytmaterials, der Durchtrittsreaktion, der Nickelmatrix in den Anoden und des Kontaktwiderstandes zwischen den Anoden und den stromabnehmenden Nickelnetzen. Die Degradation der beiden letzteren ist in ihrer Rate abhängig von der Gaszusammensetzung. Ein Modell für das beobachtete zeitliche Verhalten wird vorgestellt.
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Mücke, Robert. "Sinterung von Zirkoniumdioxid-Elektrolyten im Mehrlagenverbund der oxidkeramischen Brennstoffzelle (SOFC) /." Jülich : Forschungszentrum, Zentralbibliothek, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016734417&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Pang, Yukun. "Investigation of tin-intermetallic-metal materials for SOFC interconnect application /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1456296241&sid=12&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (M.S.)--Southern Illinois University Carbondale, 2007."Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 55-57). Also available online.
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Larby, Line. "Development of Novel (Cu,Fe)3O4 Coatings for AISI 441 Solid Oxide Cell Interconnects : Coating optimization and long-term study." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279130.
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As current environmental challenges are gaining increased attention, development of clean energy solutions is becoming one of the essential strategies to keep within the boundaries of established environmental policies. Solid oxide cell (SOC) technology can provide clean energy conversion and storage when hydrogen is the energy carrier. The high total energy conversion efficiency resulting from the high operation temperature of SOCs make the technology promising, but material costs must be reduced to make it commercially viable. Therefore, this thesis aims to study the long- term performance of a novel cost-optimized cell interconnect at 650 and 850 °C. At high temperatures, chromium evaporation from the interconnect result in electrode poisoning, which may be mitigated by application of a protective coating. The studied interconnect is an AISI 441 steel with some different pre-oxidized copper and iron spinel coatings. Sample analysis was made mainly with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffraction. It was found that the most promising pre-oxidation treatment was 24 h at 750 °C and that chromium migration was restrained at 650 °C long-term treatment but not at 850 °C where it wasfound available for evaporation at the surface.När samtida milljöutmaningar får ökad uppmärksamhet blir gröna energilösningar en av de viktigaste strategierna för att hålla sig inom satta gränser från etablerade miljöriktlinjer. Teknologin bakom fastoxidceller, eller solid oxide cells (SOCs), kan bidra med grön omvandling och lagring av energi när energibäraren är väte. Den höga totala omvandlingseffektiviteten, som kommer med den höga verkningstemperaturen, gör SOC till en lovande teknologi, men materialkostnaderna måste först reduceras innan den blir komersiellt gångbar. Därför syftar detta examensarbete till att undersöka prestandan av en ny, kostnadsoptimerad cellinterkonnektor på lång sikt i 650 och 850 °C. Vid höga temperaturer förångas krom från interkonnektorn, vilket leder till elektrodförgiftning, men kan mildras genom applicering av en skyddande beläggning. Den undersökta interkonnektorn är ett stål som betäcknas AISI 441 belagt med några olika föroxiderade beläggningar av koppar- och järnspinell. Proverna analyserades i huvudsak genom svepelektronmikroskopi kobinerat med energidispersiv röntgenspektroskopi och röntgendiffraktometri. Det visades att den mest lovande föroxideringsbehandlingen var 24 h i 750 °C och att krom förblev återhållet vid 650 °men inte vid 850 °C då det fanns tillgängligt för förångning vidytan.
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Chakravarthula, Venkata Adithya. "Transient Analysis of a Solid Oxide Fuel Cell/ Gas Turbine Hybrid System for Distributed Electric Propulsion." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484651177170392.
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Tang, Shijie. "Development of Multiphase Oxygen-ion Conducting Electrolytes for Low Temperature Solid Oxide Fuel Cells." Scholarly Repository, 2007. http://scholarlyrepository.miami.edu/oa_theses/112.
Full textAbstract:
One of the major trends of development of solid oxide fuel cells is to reduce the operating temperature from the high temperature range (>950°C) and intermediate temperature range (750-850°C) to the low temperature range (450-650°C). Development of low temperature oxygen ion conducting electrolytes is focused on single-phase materials including Bi2O3 and CeO2-based oxides. These materials have high ion conductivity at the low temperature range, but they are unstable in reducing environments and they are also electronic conductors. In the present research, three types of multiphase materials, Ce0.887Y0.113O1.9435 (CYO)-ZrO2, CYO- yttria-stabilized zirconia (YSZ), and CuO-CYO were investigated. We found that the conductivity of multiphase electrolyte CuO-CYO with a mass ratio of 1:3 is at least 4 times greater than that of CYO and 10 times greater than that of YSZ, the most commonly used material, obtained in the present experiments at 600°C. The enhancement of conductivity in multiphase materials correlates with the level of mismatch between the two phases. Large mismatches in terms of valance and structure result in high vacancy density and hence high oxygen ion conductivity at grain boundaries. This study demonstrates that synthesis of multiphase ceramic materials is a feasible new avenue for development of oxygen ion electrolyte material for low temperature SOFCs.
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Aguilar, Luis Felipe. "Development of Sulfur Tolerant Materials for the Hydrogen Sulfide Solid Oxide Fuel Cell." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6979.
Full textAbstract:
One of the major technical challenges towards a viable H2S//Air SOFC is to identify and develop anode materials that are electronically conductive, chemically and electrochemically stable, and catalytically active when exposed to H2S-rich environments. The corrosive nature of H2S renders most traditional state-of-the-art SOFC anode materials (Ni, Pt, Ag) useless for long-term cell performance even at very low sulfur concentrations. In my doctoral thesis work, a new class of perovskite-based anodes was developed for potential use in SOFCs operating with H2S and sulfur-containing fuels. Cermets from this family of materials have shown excellent chemical stability and electrochemical performance at typical SOFC operating conditions. As an added benefit, they appear to preferentially oxidize H2S over hydrogen, as suggested by open circuit voltage, impedance spectra, and cell performance measurements obtained using various H2S-H2-N2 fuel mixtures. Cell power output values were among the highest reported in the literature and showed no significant deterioration during 48-hour testing periods. Impedance measurements indicated overall cell resistances decreased with increasing temperature and H2S content of the fuel. This behavior is starkly different from that of contemporary SOFC anodes, where the presence of H2S usually increases overall polarization resistance and ultimately destroys the cell. Results are promising due to the drastic improvement in sulfur tolerance compared to the current generation of SOFC power systems.
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Stout, Sean Dakota. "DESIGN AND CHARACTERIZATION OF INTERMEDIATE TEMPERATURE SOLD OXIDE FUEL CELLS WITH A HONEYCOMB STRUCTURE; OPERATION, RESEARCH, AND OPPORTUNITIES." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1740.
Full textAbstract:
The aim of this thesis is to propose the design process and considerations to be employed in the fabrication of a high-volumetric-power-density intermediate temperature solid oxide fuel cell (IT-SOFC), as well as the necessary characterization and analysis techniques for such a device. A novel hexagonal honeycomb design will be proposed with functionally graded electrodes and an alternative electrolyte – a previously unexplored configuration based on attained research. The potential use of CFD software to investigate mass and heat transport properties of an SOFC having such a design shall be discussed, as well as the utility of experimental methods such as the generation of a polarization curve and the use of SEM to characterize electrochemical performance and microstructure, respectively. Fabrication methods shall also be evaluated, and it will be shown that the proposed design is not only feasible but meets the goal of designing an SOFC with a power density of 2 W/cm3 operating at or below 650 C.