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Oxide Fuel Cells (oxide + fuel_cell)
Kinds of Oxide Fuel Cells Selected AbstractsThe Electrophoretic Deposition of Lanthanum Manganite Powders for a Cathode-Supported Solid Oxide Fuel Cell in Planar and Tubular ConfigurationsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2008Ivana Krklju The purpose of this research was to obtain porous, high-quality cathodes for solid oxide fuel cells in both planar and tubular shapes. To accomplish this, cathodic electrophoretic deposition of the LaMnO3 powder (synthesized by the modified sol,gel method proposed by Pechini) was performed. The optimal sintering temperatures were 1200°C and 1300°C for the tubular and planar configurations, respectively. Single-phase deposits with about 40% porosity were obtained in both configurations. The cathode quality was confirmed by depositing an electrolyte layer of YSZ. After the cosintering of both layers, an extremely dense electrolyte layer was obtained, and the cathode layer retained its high porosity. [source] Anode-Supported Tubular Micro-Solid Oxide Fuel CellINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2007Partho Sarkar A tubular anode-supported "micro-solid oxide fuel cell" (,SOFC) has been developed for producing high volumetric power density (VPD) SOFC systems featuring rapid turn on/off capability. An electrophoretic deposition (EPD)-based, facile manufacturing process is being refined to produce the anode support, anode functional and electrolyte layers of a single cell. ,SOFCs (diameter <5 mm) have two main potential advantages, a substantial increase in the electrolyte surface area per unit volume of a stack and also rapid start-up. As fuel cell power is directly proportional to the active electrolyte surface area, a ,SOFC stack can substantially increase the VPD of an SOFC device. A decrease in tube diameter allows for a reduction in wall thickness without any degradation of a cell's mechanical properties. Owing to its thin wall, a ,SOFC has an extremely high thermal shock resistance and low thermal mass. These two characteristics are fundamental in reducing start-up and turn-off time for the SOFC stack. Traditionally, SOFC has not been considered for portable applications due to its high thermal mass and low thermal shock resistance (start-up time in hours), but with ,SOFCs' potential for rapid start-up, new possibilities for portable and transportable applications open up. [source] SOFCo Planar Solid Oxide Fuel CellINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2004Liang A. Xue SOFCo-EFS Holdings LLC has developed a multi-layer, planar solid oxide fuel cell (SOFC) stack that has the potential to provide superior performance and reliability at reduced costs. Our approach combines state-of-the-art SOFC materials with the manufacturing technology and infrastructure established for multi-layer ceramic (MLC) packages for the microelectronics industry. With the proper selection of SOFC materials, implementation of MLC fabrication methods offers unique designs for stacks. Over the past two years, substantial progress has been made in the design and manufacturing development of our second-generation stack. Effective stack and manifold seals have been developed. Cell performance has been improved and relatively low non-cell contributions to stack resistance have been achieved. Stack development has been facilitated through the implementation of two key test methods: (1) a 10-cm single-cell test to bridge the gap in performance data obtained from button cell tests (used for cell R&D) and stack tests; and (2) a novel instrumented short stack (<5 cells) that allows for effective isolation of individual contributions to stack resistance. As a result of progress made to date, a clear pathway for improving stack performance has been established, thereby building confidence that commercial stack performance targets will be reached. [source] An Efficient Solid Oxide Fuel Cell Based upon Single-Phase Perovskites,ADVANCED MATERIALS, Issue 14 2005W. Tao An all-perovskite solid oxide fuel cell has been achieved using LSCM ((La0.75Sr0.25)0.95Cr0.5Mn0.5O3,,) as the anode, LSGMCo (La0.8Sr0.2Ga0.8Mg0.15 -Co0.05O3,,) as the electrolyte, and GSC (Gd0.4Sr0.6CoO3,,) as the cathode (see Figure). The all-perovskite design enhances structural integrity and minimizes interface polarization losses. [source] Functionally Graded Layers Prepared by Atmospheric Plasma Spraying for Solid Oxide Fuel Cells,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009W. S. Xia Two functionally graded layers between the electrolyte and adjacent electrodes were prepared by atmospheric plasma spraying (APS) for solid oxide fuel cells (SOFCs). Both the porosity and material compositions gradually vary in the two graded layers. The SOFC with the graded layers has higher electronic conductivity and far lower interface resistance than that without graded layers. [source] Time,Temperature,Transformation (TTT) Diagrams for Crystallization of Metal Oxide Thin FilmsADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Jennifer L. M. Rupp Abstract Time,temperature,transformation (TTT) diagrams are proposed for the crystallization of amorphous metal oxide thin films and their specific characteristics are discussed in comparison to glass-based materials, such as glass-ceramics and metallic glasses. The films crystallize from amorphous to full crystallinity in the solid state. As an example the crystallization kinetics for a single-phase metal oxide, ceria, and its gadolinia solid solutions are reported made by the precipitation thin-film method spray pyrolysis. The crystallization of an amorphous metal oxide thin film generally follows the Lijschitz,Sletow,Wagner (LSW) Ostwald ripening theory: Below the percolation threshold of 20 vol% single grains crystallize in the amorphous phase and low crystallization rates are measured. In this state no impact of solute on crystallization is measurable. Once the grains form primary clusters above the threshold the solute slows down crystallization (and grain growth) thus shifting the TTT curves of the doped ceria films to longer times and higher temperatures in comparison to undoped ceria. Current views on crystallization of metal oxide thin films, the impact of solute dragging, and primary TTT diagrams are discussed. Finally, examples on how to use these TTT diagrams for better thermokinetic engineering of metal oxide thin films for MEMS are given, for example, for micro-Solid Oxide Fuel Cells and resistive sensors. In these examples the electrical properties depend on the degree of crystallinity and, thereby, on the TTT conditions. [source] Vertically Aligned Nanocomposite Thin Films as a Cathode/Electrolyte Interface Layer for Thin-Film Solid Oxide Fuel CellsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Jongsik Yoon Abstract A thin layer of a vertically aligned nanocomposite (VAN) structure is deposited between the electrolyte, Ce0.9Gd0.1O1.95 (CGO), and the thin-film cathode layer, La0.5Sr0.5CoO3 (LSCO), of a thin-film solid-oxide fuel cell (TFSOFC). The self-assembled VAN nanostructure contains highly ordered alternating vertical columns of CGO and LSCO formed through a one-step thin-film deposition process that uses pulsed laser deposition. The VAN structure significantly improves the overall performance of the TFSOFC by increasing the interfacial area between the electrolyte and cathode. Low cathode polarization resistances of 9,×,10,4 and 2.39,, were measured for the cells with the VAN interlayer at 600 and 400,°C, respectively. Furthermore, anode-supported single cells with LSCO/CGO VAN interlayer demonstrate maximum power densities of 329, 546, 718, and 812,mW cm,2 at 550, 600, 650, and 700,°C, respectively, with an open-circuit voltage (OCV) of 1.13,V at 550,°C. The cells with the interlayer triple the overall power output at 650,°C compared to that achieved with the cells without an interlayer. The binary VAN interlayer could also act as a transition layer that improves adhesion and relieves both thermal stress and lattice strain between the cathode and the electrolyte. [source] Optimisation and Evaluation of La0.6Sr0.4CoO3,,,, Cathode for Intermediate Temperature Solid Oxide Fuel CellsFUEL CELLS, Issue 5 2009Youkun Tao Abstract In this work, La0.6Sr0.4CoO3,,,,/Ce1,,xGdxO2,,,, (LSC/GDC) composite cathodes are investigated for SOFC application at intermediate temperatures, especially below 700,°C. The symmetrical cells are prepared by spraying LSC/GDC composite cathodes on a GDC tape, and the lowest polarisation resistance (Rp) of 0.11,,,cm2 at 700,°C is obtained for the cathode containing 30,wt.-% GDC. For the application on YSZ electrolyte, symmetrical LSC cathodes are fabricated on a YSZ tape coated on a GDC interlayer. The impact of the sintering temperature on the microstructure and electrochemical properties is investigated. The optimum temperature is determined to be 950,°C; the corresponding Rp of 0.24,,,cm2 at 600,°C and 0.06,,,cm2 at 700,°C are achieved, respectively. An YSZ-based anode-supported solid oxide fuel cell is fabricated by employing LSC/GDC composite cathode sintered at 950,°C. The cell with an active electrode area of 4,×,4,cm2 exhibits the maximum power density of 0.42,W,cm,2 at 650,°C and 0.54,W,cm,2 at 700,°C. More than 300,h operating at 650,°C is carried out for an estimate of performance and degradation of a single cell. Despite a decline at the beginning, the stable performance during the later term suggests a potential application. [source] Samarium-Doped Ceria Nanowires: Novel Synthesis and Application in Low-Temperature Solid Oxide Fuel CellsADVANCED MATERIALS, Issue 14 2010Ying Ma Samarium-doped ceria (SDC) nanowires are synthesized by a novel, template-, surfactant-free and cost-effective method, using citric acid as precipitating/complexing agent for formation of citrate precursor nanowires. The single SOFC based on SDC nanowires/Na2CO3 nanocomposites as electrolyte is fabricated and the maximum power densities of 417 and 522,mW,cm,2 at 550 and 600,°C are achieved, showing great potential for low-temperature SOFCs. [source] Electrode Properties of the Ruddlesden,Popper Series, Lan+1NinO3n+1 (n=1, 2, and 3), as Intermediate-Temperature Solid Oxide Fuel CellsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Suguru Takahashi The Ruddlesden,Popper phases, Lan+1NinO3n+1 (n=1, 2, and 3), were synthesized by a solid-state reaction for use as cathodes in an intermediate-temperature (500°,700°C) solid oxide fuel cell. The samples crystallized into an orthorhombic layered perovskite structure. The overall electrical conductivity increased with the increase of n in the intermediate temperature range. Single test-cells, which consisted of samarium-oxide-doped ceria (SDC; Sm0.2Ce0.8Ox) as an electrolyte, Ni,SDC cermet (Ni,SDC) as an anode, and Lan+1NinO3n+1 as a cathode, were fabricated for measurements of cell performance at 500°,700°C. Current interruption measurements revealed that both the ohmic and overpotential losses at 700°C decreased with the increase of n. La4Ni3O10 was found to exhibit the best cathode characteristics in the Lan+1NinO3n+1 series. Maximum test-cell power densities with La4Ni3O10 (n=3) were 10.2, 36.5, and 88.2 mW/cm2 at 500°, 600°, and 700°C, respectively. [source] Glass-to-Metal Seal Interfacial Analysis using Electron Probe Microscopy for Reliable Solid Oxide Fuel CellsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2009Scarlett J. Widgeon The chemical compatibility between sealing glasses and interconnect materials for solid oxide fuel cells (SOFCs) has been studied in SOFC environments. Two borate-based glass compositions were sealed to interconnect materials, 441 stainless-steel (441SS) and Mn1.5Co1.5O4 -coated 441SS. The Mn1.5Co1.5O4 -coated 441SS coupons were analyzed as-received using X-ray diffraction (XRD) and electron probe microanalysis (EPMA) to obtain structural information and concentration profiles, respectively. The concentration profiles and the lack of Fe-containing phases present in the XRD spectrum show Fe is present throughout the coating, suggesting that Fe is partially substituted in the Mn1.5Co1.5O4 spinel. The glass,metal coupons were heat treated in air at 750°C for 500 h. The specimens were analyzed by EPMA and scanning electron microscope (SEM) to obtain images of the glass microstructure at the interface, to verify seal adherence, and to record concentration profiles across the glass,metal interface, with an emphasis on Cr. In total, four seal configurations were tested and analyzed, and in all cases the glasses remained well adhered to the metal and coating, and there was no microstructural evidence of new reaction phases present at the interface. There was slight diffusion of Cr from the 441SS into the sealing glasses, and Cr diffusion was hindered by the coating on the coated 441SS samples. [source] Thin Yttrium-Stabilized Zirconia Electrolyte Solid Oxide Fuel Cells by Centrifugal CastingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2002Jiang Liu A centrifugal casting technique was developed for depositing thin 8-mol%-yttrium-stabilized zirconia (YSZ) electrolyte layers on porous NiO-YSZ anode substrates. After the bilayers were cosintered at 1400°C, dense pinhole-free YSZ coatings with thicknesses of ,25 ,m were obtained, while the Ni-YSZ retained porosity. After La0.6Sr0.4Co0.2Fe0.8O3 (LSCF)-Ce0.9Gd0.1O1.95 (GDC) or La0.8Sr0.2MnO3 (LSM)-YSZ cathodes were deposited, single SOFCs produced near-theoretical open-circuit voltages and power densities of ,1 W/cm2 at 800°C. Impedance spectra measured during cell tests showed that polarization resistances accounted for ,70%,80% of the total cell resistance. [source] Effect of Nickel Oxide/Yttria-Stabilized Zirconia Anode Precursor Sintering Temperature on the Properties of Solid Oxide Fuel CellsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2000Søren Primdahl An NiO/yttria-stabilized zirconia (YSZ) layer sintered at temperatures between 1100° and 1500°C onto dense YSZ electrolyte foils forms the precursor structure for a porous Ni/YSZ cermet anode for solid oxide fuel cells. Conflicting requirements for the electrochemical performance and mechanical strength of such cells are investigated. A minimum polarization resistance of 0.09 ,.cm2at 1000°C in moist hydrogen is obtained for sintering temperatures of 1300°,1400°C. The mechanical strength of the cells decreases with increased sintering temperature because of the formation of channel cracks in the electrode layers, originating in a thermal expansion coefficient mismatch between the layers. [source] ChemInform Abstract: Low Thermal Expansion MBa(Co,M,)4O7 Cathode Materials Based on Tetrahedral-Site Cobalt Ions for Solid Oxide Fuel Cells.CHEMINFORM, Issue 31 2010Jung-Hyun Kim Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Simple Solid Oxide Fuel Cells.CHEMINFORM, Issue 13 2010Bin Lin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Computational Study on the Catalytic Mechanism of Oxygen Reduction on La0.5Sr0.5MnO3 in Solid Oxide Fuel Cells.CHEMINFORM, Issue 47 2007YongMan Choi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Thermal modeling and simulation of an integrated solid oxide fuel cell and charcoal gasification systemENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2009C. Ozgur Colpan Abstract In this study we propose a novel integrated charcoal gasification and solid oxide fuel cell (SOFC) system, which is intended to produce electricity and heat simultaneously. This system mainly consists of an updraft gasifier using air and steam as the gasification agents, a planar and direct internal reforming SOFC and a low temperature gas cleanup system. The performance of this system is assessed through numerical modeling using a pre-developed and validated heat transfer model of the SOFC and thermodynamic models for the rest of the components. These models are used to simulate the performance of the cell and system for a case study. In addition, a parametric study is conducted to assess the effect of Reynolds number at the fuel channel inlet of the SOFC on the cell performance, e.g., fuel utilization and power density, and the system performance, e.g., electrical efficiency, exergetic efficiency, and power to heat ratio. The number of stacks is also calculated for different Reynolds numbers to discuss the economical feasibility of the integrated system. The results show that the electrical efficiency, exergetic efficiency and power to heat ratio of this system are 33.31%, 45.72%, and 1.004, respectively, for the base case. The parametric study points out that taking the Reynolds number low yields higher electrical and exergetic efficiencies for the system, but it also increases the cost of the system. © 2009 American Institute of Chemical Engineers Environ Prog, 2009 [source] Temperature and Impurity Concentration Effects on Degradation of Nickel/Yttria-stabilised Zirconia Anode in PH3 -Containing Coal SyngasFUEL CELLS, Issue 1 2010M. Zhi Abstract Degradation of the Ni/yttria-stabilised zirconia (YSZ) anode of the solid oxide fuel cell has been evaluated in the coal syngas containing different PH3 concentrations in the temperature range from 750 to 900,°C. Thermodynamic equilibrium calculations show that PH3 in the coal syngas gas is converted mostly to P2O3 at 750,900,°C. The phosphorous impurity reacts with the Ni-YSZ anode to form phosphates. The P-impurity poisoning leads to the deactivation of the Ni catalyst and to the reduction in the electronic conductivity of the anode. The impurity poisoning effect on the anode is exacerbated by increase in the temperature and/or the PH3 concentration. [source] Optimisation and Evaluation of La0.6Sr0.4CoO3,,,, Cathode for Intermediate Temperature Solid Oxide Fuel CellsFUEL CELLS, Issue 5 2009Youkun Tao Abstract In this work, La0.6Sr0.4CoO3,,,,/Ce1,,xGdxO2,,,, (LSC/GDC) composite cathodes are investigated for SOFC application at intermediate temperatures, especially below 700,°C. The symmetrical cells are prepared by spraying LSC/GDC composite cathodes on a GDC tape, and the lowest polarisation resistance (Rp) of 0.11,,,cm2 at 700,°C is obtained for the cathode containing 30,wt.-% GDC. For the application on YSZ electrolyte, symmetrical LSC cathodes are fabricated on a YSZ tape coated on a GDC interlayer. The impact of the sintering temperature on the microstructure and electrochemical properties is investigated. The optimum temperature is determined to be 950,°C; the corresponding Rp of 0.24,,,cm2 at 600,°C and 0.06,,,cm2 at 700,°C are achieved, respectively. An YSZ-based anode-supported solid oxide fuel cell is fabricated by employing LSC/GDC composite cathode sintered at 950,°C. The cell with an active electrode area of 4,×,4,cm2 exhibits the maximum power density of 0.42,W,cm,2 at 650,°C and 0.54,W,cm,2 at 700,°C. More than 300,h operating at 650,°C is carried out for an estimate of performance and degradation of a single cell. Despite a decline at the beginning, the stable performance during the later term suggests a potential application. [source] Microstructure and Microfabrication Considerations for Self-Supported On-Chip Ultra-Thin Micro-Solid Oxide Fuel Cell MembranesFUEL CELLS, Issue 5 2009B.-K. Lai Abstract La0.6Sr0.4Co0.8Fe0.2O3,,,, (LSCF) has been sputtered on bare Si and Si3N4 and yttria-stabilised zirconia (YSZ) thin films to investigate annealing temperature- and thickness-dependent microstructure and functional properties, as well as their implications for designing failure-resistant micro-solid oxide fuel cell (,SOFC) membranes. The LSCF thin films crystallise in the 400,450,°C range; however, after annealing in the 600,700,°C range, cracks are observed. The formation of cracks is also thickness-dependent. High electrical conductivity, ,520,Scm,1 at 600,°C, and low activation energy, ,0.13,eV, in the 400,600,°C range, are still maintained for LSCF films as thin as 27,nm. Based on these studies, a strong correlation between microstructure and electrical conductivity has been observed and an annealing temperature-thickness design space that is complementary to temperature-stress design space has been proposed for designing reliable membranes using sputtered LSCF thin films. Microfabrication approaches that maintain the highest possible surface and interface quality of heterostructured membranes have been carefully examined. By taking advantage of the microstructure, microfabrication and geometrical structural considerations, we were able to successfully fabricate large-area, self-supported membranes. These results are also relevant to conventional or grid-supported SOFC membranes using ultrathin nanocrystalline cathodes and ,SOFCs using cathode thin films other than LSCF. [source] Reactivity in LaGaO3/Ni and CeO2/Ni SystemsFUEL CELLS, Issue 2 2006N. Solak Abstract The reactivity in CeO2/Ni and LaGaO3/Ni systems, which are constituents of intermediate temperature solid oxide fuel cell (IT-SOFC) anodes, has been investigated both computationally and experimentally. The CALPHAD-method (CALculating of PHAse Diagrams), employing BINGSS and THERMOCALC software, was used to obtain a self-consistent set of Gibbs energy functions describing the systems. Interactions in the LaGaO3/Ni system were predicted using a thermodynamic database developed for the La-Ga-Ni-O system. Similarly, to analyze the CeO2/Ni system, the Ce-Ni-O ternary phase diagram was calculated using known thermodynamic data for binary Ce-O, Ni-O, and Ce-Ni systems. The experimental work was designed based on the calculated phase diagrams. While the La-Ga-Ni-O system experiments were conducted in air, the Ce-Ni-O system was also investigated in a reducing atmosphere. The calculated Ce-Ni-O diagram is in good agreement with the experimental results. It has been found that NiO does not react with CeO2. Extended solid solutions of La(Ga,Ni)O3, La2(Ni,Ga)O4, and La4(Ni,Ga)3O10 were found in the La-Ga-Ni-O system. Additionally, the compound LaNiGa11O19, with magnetoplumbite-type structure, has been found, which has not been reported in the literature so far. It is concluded that La2NiO4 is not chemically compatible, as a cathode material, with the LSGM electrolyte. [source] Optimized La0.6Sr0.4CoO3,, Thin-Film Electrodes with Extremely Fast Oxygen-Reduction KineticsADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Judith Januschewsky Abstract La0.6Sr0.4CoO3,, (LSC) thin-film electrodes are prepared on yttria-stabilized zirconia (YSZ) substrates by pulsed laser deposition at different deposition temperatures. The decrease of the film crystallinity, occurring when the deposition temperature is lowered, is accompanied by a strong increase of the electrochemical oxygen exchange rate of LSC. For more or less X-ray diffraction (XRD)-amorphous electrodes deposited between ca. 340 and 510,°C polarization resistances as low as 0.1,, cm2 can be obtained at 600,°C. Such films also exhibit the best stability of the polarization resistance while electrodes deposited at higher temperatures show a strong and fast degradation of the electrochemical kinetics (thermal deactivation). Possible reasons for this behavior and consequences with respect to the preparation of high-performance solid oxide fuel cell (SOFC) cathodes are discussed. [source] Preparation of a Nanoscale/SOFC-Grade Yttria-Stabilized Zirconia Material: A Quasi-Optimization of the Hydrothermal Coprecipitation ProcessINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2008Yang-Chuang Chang Yttria-stabilized zirconia (YSZ) is the key material for an electrolyte of a solid oxide fuel cell (SOFC). In order to prepare a nanoscale/SOFC-grade 8YSZ material, the hydrothermal coprecipitation process is intensively investigated for process improvement and product identification. From the characterization results of the 8YSZ product, the operation conditions were selected for process optimization. The criteria used in optimization condition determination were the reproducibility of the 8YSZ product and the particle size, the crystallinity, as well as the operation simplicity. Experimental results showed that a nanoscale/SOFC-grade 8YSZ powder was directly prepared. The quasi-optimum conditions of the process are proposed. [source] SOFCo Planar Solid Oxide Fuel CellINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2004Liang A. Xue SOFCo-EFS Holdings LLC has developed a multi-layer, planar solid oxide fuel cell (SOFC) stack that has the potential to provide superior performance and reliability at reduced costs. Our approach combines state-of-the-art SOFC materials with the manufacturing technology and infrastructure established for multi-layer ceramic (MLC) packages for the microelectronics industry. With the proper selection of SOFC materials, implementation of MLC fabrication methods offers unique designs for stacks. Over the past two years, substantial progress has been made in the design and manufacturing development of our second-generation stack. Effective stack and manifold seals have been developed. Cell performance has been improved and relatively low non-cell contributions to stack resistance have been achieved. Stack development has been facilitated through the implementation of two key test methods: (1) a 10-cm single-cell test to bridge the gap in performance data obtained from button cell tests (used for cell R&D) and stack tests; and (2) a novel instrumented short stack (<5 cells) that allows for effective isolation of individual contributions to stack resistance. As a result of progress made to date, a clear pathway for improving stack performance has been established, thereby building confidence that commercial stack performance targets will be reached. [source] An Efficient Solid Oxide Fuel Cell Based upon Single-Phase Perovskites,ADVANCED MATERIALS, Issue 14 2005W. Tao An all-perovskite solid oxide fuel cell has been achieved using LSCM ((La0.75Sr0.25)0.95Cr0.5Mn0.5O3,,) as the anode, LSGMCo (La0.8Sr0.2Ga0.8Mg0.15 -Co0.05O3,,) as the electrolyte, and GSC (Gd0.4Sr0.6CoO3,,) as the cathode (see Figure). The all-perovskite design enhances structural integrity and minimizes interface polarization losses. [source] Performance analysis of a solid oxide fuel cell with reformed natural gas fuelINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2010S. M. Jafarian Abstract In the present study a two-dimensional model of a tubular solid oxide fuel cell operating in a stack is presented. The model analyzes electrochemistry, momentum, heat and mass transfers inside the cell. Internal steam reforming of the reformed natural gas is considered for hydrogen production and Gibbs energy minimization method is used to calculate the fuel equilibrium species concentrations. The conservation equations for energy, mass, momentum and voltage are solved simultaneously using appropriate numerical techniques. The heat radiation between the preheater and cathode surface is incorporated into the model and local heat transfer coefficients are determined throughout the anode and cathode channels. The developed model has been compared with the experimental and numerical data available in literature. The model is used to study the effect of various operating parameters such as excess air, operating pressure and air inlet temperature and the results are discussed in detail. The results show that a more uniform temperature distribution can be achieved along the cell at higher air-flow rates and operating pressures and the cell output voltage is enhanced. It is expected that the proposed model can be used as a design tool for SOFC stack in practical applications. Copyright © 2009 John Wiley & Sons, Ltd. [source] A modularized framework for solving an economic,environmental power generation mix problemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2004Haoxiang Xia Abstract This paper presents a modularized simulation modelling framework for evaluating the impacts on economic cost and CO2 emissions resulting from the introduction of a solid oxide fuel cell (SOFC) system into the existing mix of centralized power generation technologies in Japan. The framework is comprised of three parts: a dual-objective linear programming model that solves the generation best-mix problem for the existing power generation technologies; a nonlinear SOFC system model in which the economic cost and CO2 emissions by the SOFC system can be calculated; and the Queuing Multi-Objective Optimizer (QMOO), a multi-objective evolutionary algorithm (MOEA) developed at the EPFL in Switzerland as the overall optimizer of the combined power supply system. Thus, the framework integrates an evolutionary algorithm that is more suitable for handling nonlinearities with a calculus-based method that is more efficient in solving linear programming problems. Simulation experiments show that the framework is successful in solving the stated problem. Moreover, the three components of the modularized framework can be interconnected through a platform-independent model integration environment. As a result, the framework is flexible and scalable, and can potentially be modified and/or integrated with other models to study more complex problems. Copyright © 2004 John Wiley & Sons, Ltd. [source] Integrated model framework for the evaluation of an SOFC/GT system as a centralized power sourceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2004Michihisa Koyama Abstract New power generation technologies are expected to reduce various environmental impacts of providing electricity to urban regions for some investment cost. Determining which power generation technologies are most suitable for meeting the demand of a particular region requires analysis of tradeoffs between costs and environmental impacts. Models simulating different power generation technologies can help quantify these tradeoffs. An Internet-based modelling infrastructure called DOME (distributed object-based modelling environment) provides a flexible mechanism to create integrated models from independent simulation models for different power generation technologies. As new technologies appear, corresponding simulation models can readily be added to the integrated model. DOME was used to combine a simulation model for hybrid SOFC (solid oxide fuel cell) and gas turbine system with a power generation capacity and dispatch optimization model. The integrated models were used to evaluate the effectiveness of the system as a centralized power source for meeting the power demand in Japan. Evaluation results indicate that a hybrid system using micro-tube SOFC may reduce CO2 emissions from power generation in Japan by about 50%. Copyright © 2004 John Wiley & Sons, Ltd. [source] Alternative concept for SOFC with direct internal reforming operation: Benefits from inserting catalyst rodAICHE JOURNAL, Issue 6 2010Pannipha Dokamaingam Abstract Mathematical models of direct internal reforming solid oxide fuel cell (DIR-SOFC) fueled by methane are developed using COMSOL® software. The benefits of inserting Ni-catalyst rod in the middle of tubular-SOFC are simulated and compared to conventional DIR-SOFC. It reveals that DIR-SOFC with inserted catalyst provides smoother temperature gradient along the system and gains higher power density and electrochemical efficiency with less carbon deposition. Sensitivity analyses are performed. By increasing inlet fuel flow rate, the temperature gradient and power density improve, but less electrical efficiency with higher carbon deposition is predicted. The feed with low inlet steam/carbon ratio enhances good system performances but also results in high potential for carbon formation; this gains great benefit of DIR-SOFC with inserted catalyst because the rate of carbon deposition is remarkably low. Compared between counter- and co-flow patterns, the latter provides smoother temperature distribution with higher efficiency; thus, it is the better option for practical applications. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Modeling of CO2 gasification of carbon for integration with solid oxide fuel cellsAICHE JOURNAL, Issue 4 2009Andrew C. Lee Abstract This modeling study focuses on gasification of carbon by CO2 in a minimally fluidized bed containing a solid oxide fuel cell (SOFC). Kinetic parameters for a five-step reaction mechanism characterizing the Boudouard reaction (C + CO2 , 2CO) were determined thermogravimetrically at 1 atm from 973 to 1273 K. Experimentally determined kinetic parameters are employed in a transport model that predicts velocities and gas concentration profiles established in the carbon bed as a consequence of convection, diffusion, and heterogeneous reaction. The model is used to simulate the effect of an imbedded SOFC, in contact with the carbon bed. Although the model does not assume particular I-V characteristics for the fuel cell, it indicates that current densities in the practical range of 100,1000 mA/cm2 can be supported. Results show that temperature strongly affects the current density, whereas CO2 flow rate has only a weak effect. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] | ||||||||||||||||||||||||||||