Science.gov

Sample records for geometry solid oxide

  1. Making Solid Geometry Solid.

    ERIC Educational Resources Information Center

    Hartz, Viggo

    1981-01-01

    Allowing students to use a polystyrene cutter to fashion their own three-dimensional models is suggested as a means of allowing individuals to experience problems and develop ideas related to solid geometry. A list of ideas that can lead to mathematical discovery is provided. (MP)

  2. Advanced alternate planar geometry solid oxide fuel cells

    SciTech Connect

    Elangovan, S.; Prouse, D.; Khandkar, A.; Donelson, R.; Marianowski, L. )

    1992-11-01

    The potential of high temperature Solid Oxide Fuel Cells as high performance, high efficiency energy conversion device is well known. Investigation of several cell designs have been undertaken by various researchers to derive the maximum performance benefit from the device while maintaining a lower cost of production to meet the commercialization cost target. The present investigation focused on the planar SOFC design which allows for the use of mature low cost production processes to be employed. A novel design concept was investigated which allows for improvements in performance through increased interface stability, and lowering of cost through enhanced structural integrity and the use of low cost metal interconnects. The new cell design consisted of a co-sintered porous/dense/porous zirconia layer with the electrode material infiltrated into the porous layers. The two year program conducted by a team involving Ceramatec and the Institute of Gas Technology, culminated in a multi-cell stack test that exhibited high performance. Considerable progress was achieved in the selection of cell components, and establishing and optimizing the cell and stack fabrication parameters. It was shown that the stack components exhibited high conductivities and low creep at the operating temperature. The inter-cell resistive losses were shown to be small through out-of-cell characterization. The source of performance loss was identified to be the anode electrolyte interface. This loss however can be minimized by improving the anode infiltration technique. Manifolding and sealing of the planar devices posed considerable challenge. Even though the open circuit voltage was 250 mV/cell lower than theoretical, the two cell stack had a performance of 300 mA/cm[sup 2] at 0.4V/cell with an area specific resistance of 1 [Omega]-cm[sup 2]/cell. improvements in manifolding are expected to provide much higher performance.

  3. Advanced alternate planar geometry solid oxide fuel cells. Final report

    SciTech Connect

    Elangovan, S.; Prouse, D.; Khandkar, A.; Donelson, R.; Marianowski, L.

    1992-11-01

    The potential of high temperature Solid Oxide Fuel Cells as high performance, high efficiency energy conversion device is well known. Investigation of several cell designs have been undertaken by various researchers to derive the maximum performance benefit from the device while maintaining a lower cost of production to meet the commercialization cost target. The present investigation focused on the planar SOFC design which allows for the use of mature low cost production processes to be employed. A novel design concept was investigated which allows for improvements in performance through increased interface stability, and lowering of cost through enhanced structural integrity and the use of low cost metal interconnects. The new cell design consisted of a co-sintered porous/dense/porous zirconia layer with the electrode material infiltrated into the porous layers. The two year program conducted by a team involving Ceramatec and the Institute of Gas Technology, culminated in a multi-cell stack test that exhibited high performance. Considerable progress was achieved in the selection of cell components, and establishing and optimizing the cell and stack fabrication parameters. It was shown that the stack components exhibited high conductivities and low creep at the operating temperature. The inter-cell resistive losses were shown to be small through out-of-cell characterization. The source of performance loss was identified to be the anode electrolyte interface. This loss however can be minimized by improving the anode infiltration technique. Manifolding and sealing of the planar devices posed considerable challenge. Even though the open circuit voltage was 250 mV/cell lower than theoretical, the two cell stack had a performance of 300 mA/cm{sup 2} at 0.4V/cell with an area specific resistance of 1 {Omega}-cm{sup 2}/cell. improvements in manifolding are expected to provide much higher performance.

  4. Quadric solids and computational geometry

    SciTech Connect

    Emery, J.D.

    1980-07-25

    As part of the CAD-CAM development project, this report discusses the mathematics underlying the program QUADRIC, which does computations on objects modeled as Boolean combinations of quadric half-spaces. Topics considered include projective space, quadric surfaces, polars, affine transformations, the construction of solids, shaded image, the inertia tensor, moments, volume, surface integrals, Monte Carlo integration, and stratified sampling. 1 figure.

  5. Mixed oxide solid solutions

    DOEpatents

    Magno, Scott; Wang, Ruiping; Derouane, Eric

    2003-01-01

    The present invention is a mixed oxide solid solution containing a tetravalent and a pentavalent cation that can be used as a support for a metal combustion catalyst. The invention is furthermore a combustion catalyst containing the mixed oxide solid solution and a method of making the mixed oxide solid solution. The tetravalent cation is zirconium(+4), hafnium(+4) or thorium(+4). In one embodiment, the pentavalent cation is tantalum(+5), niobium(+5) or bismuth(+5). Mixed oxide solid solutions of the present invention exhibit enhanced thermal stability, maintaining relatively high surface areas at high temperatures in the presence of water vapor.

  6. Laws of granular solids: geometry and topology.

    PubMed

    DeGiuli, Eric; McElwaine, Jim

    2011-10-01

    In a granular solid, mechanical equilibrium requires a delicate balance of forces at the disordered grain scale. To understand how macroscopic rigidity can emerge in this amorphous solid, it is crucial that we understand how Newton's laws pass from the disordered grain scale to the laboratory scale. In this work, we introduce an exact discrete calculus, in which Newton's laws appear as differential relations at the scale of a single grain. Using this calculus, we introduce gauge variables that describe identically force- and torque-balanced configurations. In a first, intrinsic formulation, we use the topology of the contact network, but not its geometry. In a second, extrinsic formulation, we introduce geometry with the Delaunay triangulation. These formulations show, with exact methods, how topology and geometry in a disordered medium are related by constraints. In particular, we derive Airy's expression for a divergence-free, symmetric stress tensor in two and three dimensions. PMID:22181138

  7. Tips on Creating Complex Geometry Using Solid Modeling Software

    ERIC Educational Resources Information Center

    Gow, George

    2008-01-01

    Three-dimensional computer-aided drafting (CAD) software, sometimes referred to as "solid modeling" software, is easy to learn, fun to use, and becoming the standard in industry. However, many users have difficulty creating complex geometry with the solid modeling software. And the problem is not entirely a student problem. Even some teachers and…

  8. Solid oxide electrochemical reactor science.

    SciTech Connect

    Sullivan, Neal P.; Stechel, Ellen Beth; Moyer, Connor J.; Ambrosini, Andrea; Key, Robert J.

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  9. Thermal analysis of combinatorial solid geometry models using SINDA

    NASA Technical Reports Server (NTRS)

    Gerencser, Diane; Radke, George; Introne, Rob; Klosterman, John; Miklosovic, Dave

    1993-01-01

    Algorithms have been developed using Monte Carlo techniques to determine the thermal network parameters necessary to perform a finite difference analysis on Combinatorial Solid Geometry (CSG) models. Orbital and laser fluxes as well as internal heat generation are modeled to facilitate satellite modeling. The results of the thermal calculations are used to model the infrared (IR) images of targets and assess target vulnerability. Sample analyses and validation are presented which demonstrate code products.

  10. Intermediate temperature solid oxide fuel cells.

    PubMed

    Brett, Daniel J L; Atkinson, Alan; Brandon, Nigel P; Skinner, Stephen J

    2008-08-01

    High temperature solid oxide fuel cells (SOFCs), typified by developers such as Siemens Westinghouse and Rolls-Royce, operate in the temperature region of 850-1000 degrees C. For such systems, very high efficiencies can be achieved from integration with gas turbines for large-scale stationary applications. However, high temperature operation means that the components of the stack need to be predominantly ceramic and high temperature metal alloys are needed for many balance-of-plant components. For smaller scale applications, where integration with a heat engine is not appropriate, there is a trend to move to lower temperatures of operation, into the so-called intermediate temperature (IT) range of 500-750 degrees C. This expands the choice of materials and stack geometries that can be used, offering reduced system cost and, in principle, reducing the corrosion rate of stack and system components. This review introduces the IT-SOFC and explains the advantages of operation in this temperature regime. The main advances made in materials chemistry that have made IT operation possible are described and some of the engineering issues and the new opportunities that reduced temperature operation affords are discussed. This tutorial review examines the advances being made in materials and engineering that are allowing solid oxide fuel cells to operate at lower temperature. The challenges and advantages of operating in the so-called 'intermediate temperature' range of 500-750 degrees C are discussed and the opportunities for applications not traditionally associated with solid oxide fuel cells are highlighted. This article serves as an introduction for scientists and engineers interested in intermediate temperature solid oxide fuel cells and the challenges and opportunities of reduced temperature operation. PMID:18648682

  11. Solid oxide fuel cell generator

    DOEpatents

    Draper, Robert; George, Raymond A.; Shockling, Larry A.

    1993-01-01

    A solid oxide fuel cell generator has a pair of spaced apart tubesheets in a housing. At least two intermediate barrier walls are between the tubesheets and define a generator chamber between two intermediate buffer chambers. An array of fuel cells have tubes with open ends engaging the tubesheets. Tubular, axially elongated electrochemical cells are supported on the tubes in the generator chamber. Fuel gas and oxidant gas are preheated in the intermediate chambers by the gases flowing on the other side of the tubes. Gas leakage around the tubes through the tubesheets is permitted. The buffer chambers reentrain the leaked fuel gas for reintroduction to the generator chamber.

  12. Solid oxide fuel cell generator

    DOEpatents

    Draper, R.; George, R.A.; Shockling, L.A.

    1993-04-06

    A solid oxide fuel cell generator has a pair of spaced apart tubesheets in a housing. At least two intermediate barrier walls are between the tubesheets and define a generator chamber between two intermediate buffer chambers. An array of fuel cells have tubes with open ends engaging the tubesheets. Tubular, axially elongated electrochemical cells are supported on the tubes in the generator chamber. Fuel gas and oxidant gas are preheated in the intermediate chambers by the gases flowing on the other side of the tubes. Gas leakage around the tubes through the tubesheets is permitted. The buffer chambers reentrain the leaked fuel gas for reintroduction to the generator chamber.

  13. Reverse engineering: algebraic boundary representations to constructive solid geometry.

    SciTech Connect

    Buchele, S. F.; Ellingson, W. A.

    1997-12-17

    Recent advances in reverse engineering have focused on recovering a boundary representation (b-rep) of an object, often for integration with rapid prototyping. This boundary representation may be a 3-D point cloud, a triangulation of points, or piecewise algebraic or parametric surfaces. This paper presents work in progress to develop an algorithm to extend the current state of the art in reverse engineering of mechanical parts. This algorithm will take algebraic surface representations as input and will produce a constructive solid geometry (CSG) description that uses solid primitives such as rectangular block, pyramid, sphere, cylinder, and cone. The proposed algorithm will automatically generate a CSG solid model of a part given its algebraic b-rep, thus allowing direct input into a CAD system and subsequent CSG model generation.

  14. Solid-oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Fee, D. C.; Ackerman, J. P.

    Solid-Oxide Fuel Cell (SOFC) systems offer significant advantages for a variety of fuels and applications. The simplicity and high efficiency of a direct reforming, contaminant-tolerant power system is advantageous for small natural gas or volatile liquid-fueled utility and industrial congeneration plants, as well as residential use. The further gain in efficiency from the incorporation of a bottoming cycle in large-scale plants is advantageous for coal-fueled utility baseload or industrial cogeneration facilities. Development of SOFC components is well advanced. The present effort focuses on improving cell life and performance as well as integration of cells into an array.

  15. Solid-oxide fuel cell electrolyte

    DOEpatents

    Bloom, Ira D.; Hash, Mark C.; Krumpelt, Michael

    1993-01-01

    A solid-oxide electrolyte operable at between 600.degree. C. and 800.degree. C. and a method of producing the solid-oxide electrolyte are provided. The solid-oxide electrolyte comprises a combination of a compound having weak metal-oxygen interactions with a compound having stronger metal-oxygen interactions whereby the resulting combination has both strong and weak metal-oxygen interaction properties.

  16. Solid oxide electrolysis: Concluding remarks.

    PubMed

    Jun, Areum; Ju, Young-Wan; Kim, Guntae

    2015-01-01

    Renewable energy resources such as solar energy, wind energy, hydropower or geothermal energy have attracted significant attention in recent years. Renewable energy sources have to match supply with demand, therefore it is essential that energy storage devices (e.g., secondary batteries) are developed. However, secondary batteries are accompanied with critical problems such as high cost for the limited energy storage capacity and loss of charge over time. Energy storage in the form of chemical species, such as H2 or CO2, have no constraints on energy storage capacity and will also be essential. When plentiful renewable energy exists, for example, it could be used to convert H2O into hydrogen via water electrolysis. Also, renewable energy resources could be used to reduce CO2 into CO and recycle CO2 and H2O into sustainable hydrocarbon fuels in solid oxide electrolysis (SOE). PMID:26470860

  17. SABRINA: an interactive solid geometry modeling program for Monte Carlo

    SciTech Connect

    West, J.T.

    1985-01-01

    SABRINA is a fully interactive three-dimensional geometry modeling program for MCNP. In SABRINA, a user interactively constructs either body geometry, or surface geometry models, and interactively debugs spatial descriptions for the resulting objects. This enhanced capability significantly reduces the effort in constructing and debugging complicated three-dimensional geometry models for Monte Carlo Analysis.

  18. Solid oxide materials research accelerated electrochemical testing

    SciTech Connect

    Windisch, C.; Arey, B.

    1995-08-01

    The objectives of this work were to develop methods for accelerated testing of cathode materials for solid oxide fuel cells under selected operating conditions. The methods would be used to evaluate the performance of LSM cathode material.

  19. Interfacial material for solid oxide fuel cell

    DOEpatents

    Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

    1999-01-01

    Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

  20. An analytical approach for solid oxide cell electrode geometric design

    NASA Astrophysics Data System (ADS)

    Nelson, George J.

    2015-12-01

    An analytical model for gas distributions in porous solid oxide cell electrodes is applied to develop dimensionless metrics that describe electrode performance. These metrics include two forms of a dimensionless reactant depletion current density and a geometry sensitive Damköhler number used to assess electrode catalytic effectiveness. The first dimensionless depletion current density defines when reducing electrode thickness no longer benefits mass transfer performance for a given cell geometry. The second dimensionless depletion current density provides a gage of deviation from the limiting current behavior predicted using button-cell experimental and modeling approaches. The Damköhler number and related catalytic effectiveness quantify two-dimensional transport effects under non-depleted operating conditions, providing a means of generalizing insights from reactant depletion behavior for typical cell operating conditions. A finite element solution for gas transport based on the dusty-gas model is used as a benchmark for the analytical model and dimensionless metrics. Estimates of concentration polarization based on analytical and numerical models compare well to published experimental data. Analytical performance predictions provide clear demonstration of the influence of two-dimensional electrode geometry on solid oxide cell performance. These results agree with finite element predictions and suggest that reduction of electrode thickness does not exclusively benefit cell performance.

  1. Supercritical water oxidation - Microgravity solids separation

    NASA Technical Reports Server (NTRS)

    Killilea, William R.; Hong, Glenn T.; Swallow, Kathleen C.; Thomason, Terry B.

    1988-01-01

    This paper discusses the application of supercritical water oxidation (SCWO) waste treatment and water recycling technology to the problem of waste disposal in-long term manned space missions. As inorganic constituents present in the waste are not soluble in supercritical water, they must be removed from the organic-free supercritical fluid reactor effluent. Supercritical water reactor/solids separator designs capable of removing precipitated solids from the process' supercritical fluid in zero- and low- gravity environments are developed and evaluated. Preliminary experiments are then conducted to test the concepts. Feed materials for the experiments are urine, feces, and wipes with the addition of reverse osmosis brine, the rejected portion of processed hygiene water. The solid properties and their influence on the design of several oxidation-reactor/solids-separator configurations under study are presented.

  2. Thin-film solid-oxide fuel cells

    SciTech Connect

    Jankowski, A.F.

    1997-05-01

    Fuel cells are energy conversion devices that would save billions of dollars in fuel costs alone each year in the United States if they could be implemented today for stationary and transportation applications (1-5). There are a wide variety of fuel cells available, e.g. molten carbonate, phosphoric acid, proton exchange membrane and solid-oxide. However, solid-oxide fuel cells (SOFCS) are potentially more efficient and less expensive per kilowatt of power in comparison to other fuel cells. For transportation applications, the energy efficiency of a conventional internal combustion engine would be increased two-fold as replaced with a zero-emission SOFC. The basic unit of a SOFC consists of an anode and cathode separated by an oxygen-ion conducting, electrolyte layer. Manifolded stacks of fuel cells, with electrical interconnects, enable the transport and combination of a fuel and oxidant at elevated temperature to generate electrical current. Fuel cell development has proceeded along different paths based on the configuration of the anode-electrolyte-cathode. Various configurations include the tubular, monolithic and planar geometries. A planar geometry for the anode-electrolyte-cathode accompanied by a reduction in layer thickness offers the potential for high power density. Maximum power densities will require yet additional innovations in the assembly of fuel cell stacks with all of the manifolding stipulations for gas flow and electrical interconnects.

  3. Stability of solid oxide fuel cell materials

    SciTech Connect

    Armstrong, T.R.; Bates, J.L.; Chick, L.A.

    1996-04-01

    Interconnection materials in a solid oxide fuel cell are exposed to both highly oxidizing conditions at the cathode and to highly reducing conditions at the anode. The thermal expansion characteristics of substituted lanthanum and yttrium chromite interconnect materials were evaluated by dilatometry as a function of oxygen partial pressures from 1 atm to 10{sup -18} atm, controlled using a carbon dioxide/hydrogen buffer.

  4. The solid angle (geometry factor) for a spherical surface source and an arbitrary detector aperture

    DOE PAGESBeta

    Favorite, Jeffrey A.

    2016-01-13

    It is proven that the solid angle (or geometry factor, also called the geometrical efficiency) for a spherically symmetric outward-directed surface source with an arbitrary radius and polar angle distribution and an arbitrary detector aperture is equal to the solid angle for an isotropic point source located at the center of the spherical surface source and the same detector aperture.

  5. Thin-Film Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Chen, Xin; Wu, Nai-Juan; Ignatiev, Alex

    2009-01-01

    The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. This can result in the reduction of mass, volume, and the cost of materials for a given power level.

  6. Oxidation-reduction capacities of aquifer solids

    SciTech Connect

    Barcelona, M.J.; Holm, T.R.

    1991-01-01

    Oxidation-reduction processes play a major role in the mobility, transport, and fate of inorganic and organic chemical constituents in natural waters. Therefore, the manipulation of redox conditions in natural and treated water systems is assumed to be a common option for the control of contaminant concentrations. Measurements of the oxidation (i.e., of aqueous Cr(2+)) and reduction (i.e., of aqueous Cr2O7(2-) and H2O2) capacities of aquifer solids and groundwater have been made on samples from a sand-and-gravel aquifer. The groundwater contributed less than 1% of the system oxidation or reduction poising capacity. Reduction capacities averaged 0.095, 0.111, and 0.136 mequiv/g of dry solids for oxic, transitional, and reducing Eh conditions, respectively. Measured oxidation capacities averaged 0.4 mequiv/g of dry solids over the range of redox intensity conditions. These capacities represent considerable resistance to the adjustment of redox conditions even at uncontaminated sites. Hydrogen peroxide reduction by aquifer solid samples proceeds rapidly relative to microbially mediated decomposition. The study indicates the need for closer scrutiny of the predictability and cost effectiveness of attempts to manipulate redox conditions in poorly poised aquifer systems.

  7. Nanocrystalline cerium oxide materials for solid fuel cell systems

    DOEpatents

    Brinkman, Kyle S

    2015-05-05

    Disclosed are solid fuel cells, including solid oxide fuel cells and PEM fuel cells that include nanocrystalline cerium oxide materials as a component of the fuel cells. A solid oxide fuel cell can include nanocrystalline cerium oxide as a cathode component and microcrystalline cerium oxide as an electrolyte component, which can prevent mechanical failure and interdiffusion common in other fuel cells. A solid oxide fuel cell can also include nanocrystalline cerium oxide in the anode. A PEM fuel cell can include cerium oxide as a catalyst support in the cathode and optionally also in the anode.

  8. Solid oxide MEMS-based fuel cells

    DOEpatents

    Jankowksi, Alan F.; Morse, Jeffrey D.

    2007-03-13

    A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. The electrolyte layer can consist of either a solid oxide or solid polymer material, or proton exchange membrane electrolyte materials may be used. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

  9. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

    SciTech Connect

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; Gail Geiger; Kevin Keegan; John Noetzel; Larry Chick

    2003-12-08

    The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from January 1, 2003 to June 30, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; and Task 9 Stack Testing with Coal-Based Reformate.

  10. Generator configuration for solid oxide fuel cells

    DOEpatents

    Reichner, Philip

    1989-01-01

    Disclosed are improvements in a solid oxide fuel cell generator 1 having a multiplicity of electrically connected solid oxide fuel cells 2, where a fuel gas is passed over one side of said cells and an oxygen-containing gas is passed over the other side of said cells resulting in the generation of heat and electricity. The improvements comprise arranging the cells in the configuration of a circle, a spiral, or folded rows within a cylindrical generator, and modifying the flow rate, oxygen concentration, and/or temperature of the oxygen-containing gases that flow to those cells that are at the periphery of the generator relative to those cells that are at the center of the generator. In these ways, a more uniform temperature is obtained throughout the generator.

  11. Solid-oxide fuel-cell performance

    SciTech Connect

    Fee, D.C.; Zwick, S.A.; Ackerman, J.P.

    1983-01-01

    Two models have been developed to describe the performance of solid-oxide fuel cells: (1) a cell model which calculates cell performance for various conditions of temperature, current density, and gas composition; and (2) a systems model which performs detailed heat and mass balances around each component in a power plant. The cell model provides insight into the performance tradeoffs in cell design. Further, the cell model provides the basis for predicting fuel cell performance in a power plant environment as necessary for the systems code. Using these two tools, analysis of an atmospheric pressure, natural gas fueled, internally reforming power plant confirms the simplicity and increased efficiency of a solid oxide fuel cell system compared to existing plants.

  12. Sintered electrode for solid oxide fuel cells

    DOEpatents

    Ruka, Roswell J.; Warner, Kathryn A.

    1999-01-01

    A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation.

  13. Monolithic solid oxide fuel cell development

    NASA Technical Reports Server (NTRS)

    Myles, K. M.; Mcpheeters, C. C.

    1989-01-01

    The feasibility of the monolithic solid oxide fuel cell (MSOFC) concept has been proven, and the performance has been dramatically improved. The differences in thermal expansion coefficients and firing shrinkages among the fuel cell materials have been minimized, thus allowing successful fabrication of the MSOFC with few defects. The MSOFC shows excellent promise for development into a practical power source for many applications from stationary power, to automobile propulsion, to space pulsed power.

  14. OXIDATION-REDUCTION CAPACITIES OF AQUIFER SOLIDS

    EPA Science Inventory

    Measurements of the oxidation (i.e., of aqueous Cr2+) and reduction (i.e., of aqueous Cr2O72- and H202) capacities of aquifer solids and groundwater have been made on samples from a sand-and-gravel aquifer. The gro...

  15. Solid oxide fuel cell with monolithic core

    DOEpatents

    McPheeters, Charles C.; Mrazek, Franklin C.

    1988-01-01

    A solid oxide fuel cell in which fuel and oxidant gases undergo an electrochemical reaction to produce an electrical output includes a monolithic core comprised of a corrugated conductive sheet disposed between upper and lower generally flat sheets. The corrugated sheet includes a plurality of spaced, parallel, elongated slots which form a series of closed, linear, first upper and second lower gas flow channels with the upper and lower sheets within which a fuel gas and an oxidant gas respectively flow. Facing ends of the fuel cell are generally V-shaped and provide for fuel and oxidant gas inlet and outlet flow, respectively, and include inlet and outlet gas flow channels which are continuous with the aforementioned upper fuel gas and lower oxidant gas flow channels. The upper and lower flat sheets and the intermediate corrugated sheet are preferably comprised of ceramic materials and are securely coupled together such as by assembly in the green state and sintering together during firing at high temperatures. A potential difference across the fuel cell, or across a stacked array of similar fuel cells, is generated when an oxidant gas such as air and a fuel such as hydrogen gas is directed through the fuel cell at high temperatures, e.g., between 700.degree. C. and 1100.degree. C.

  16. Solid oxide fuel cell with monolithic core

    DOEpatents

    McPheeters, C.C.; Mrazek, F.C.

    1988-08-02

    A solid oxide fuel cell in which fuel and oxidant gases undergo an electrochemical reaction to produce an electrical output includes a monolithic core comprised of a corrugated conductive sheet disposed between upper and lower generally flat sheets. The corrugated sheet includes a plurality of spaced, parallel, elongated slots which form a series of closed, linear, first upper and second lower gas flow channels with the upper and lower sheets within which a fuel gas and an oxidant gas respectively flow. Facing ends of the fuel cell are generally V-shaped and provide for fuel and oxidant gas inlet and outlet flow, respectively, and include inlet and outlet gas flow channels which are continuous with the aforementioned upper fuel gas and lower oxidant gas flow channels. The upper and lower flat sheets and the intermediate corrugated sheet are preferably comprised of ceramic materials and are securely coupled together such as by assembly in the green state and sintering together during firing at high temperatures. A potential difference across the fuel cell, or across a stacked array of similar fuel cells, is generated when an oxidant gas such as air and a fuel such as hydrogen gas is directed through the fuel cell at high temperatures, e.g., between 700 C and 1,100 C. 8 figs.

  17. A Study of Oxides for Solid Oxide Cells

    NASA Astrophysics Data System (ADS)

    Comets, Olivier

    As the world energy consumption increases, it is a question of global health to increase energy production efficiency and to reduce CO2 emissions. In that respect, solid oxide cells are solid state devices that convert directly fuel into electricity, or vice versa. In fact, when run in fuel cell mode, such devices produce electricity with efficiency up to twice that of current natural gas power plants. However, systems equipped with them have only seen limited commercialization owing to issues of cost, durability, and performance. In this thesis, three different aspects of solid oxide cells are studied. First, the effects of stress on the properties of mixed ionic electronic conducting oxides are considered. Such oxides can be used as electrode materials, where they are often subject to large stresses, which can, in turn, affect their performance. Hence, understanding the relationship between stress and properties in such materials is crucial. Non-stoichiometry in strontium substituted lanthanum cobaltite is found to increase under tension and to decrease under compression. Then, degradation taking place when the cell is run in electrolysis mode is discussed. A high current allows for a high production rate of hydrogen gas. However, this can also lead to oxygen bubble nucleating in the electrolyte and subsequent degradation of the cell. The analysis conducted here shows that such nucleation phenomenon can be avoided by keeping the overpotential at the oxygen electrode below a critical value. Finally, the growth and coarsening of catalyst nanoparticles at the surface of an oxide is studied. Scientists have developed new oxides for anodes in which a catalyst material is dissolved and exsolves under operating conditions. As the performance of the cell is controlled by the surface area of the catalyst phase, understanding the kinetics of the growth is critical to predict the performance of the cell. An approach is developed to study the growth of one particle, in the

  18. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

    SciTech Connect

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; Gail Geiger; Kevin Keegan; Larry Chick

    2004-05-07

    The objective of this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from July 1, 2003 to December 31, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; Task 9 Stack Testing with Coal-Based Reformate; and Task 10 Technology Transfer from SECA CORE Technology Program. In this reporting period, unless otherwise noted Task 6--System Fabrication and Task 7--System Testing will be reported within Task 1 System Design and Integration. Task 8--Program Management, Task 9--Stack Testing with Coal Based Reformate, and Task 10--Technology Transfer from SECA CORE Technology Program will be reported on in the Executive Summary section of this report.

  19. TEACHERS' GUIDE. NINTH GRADE PLANE AND SOLID GEOMETRY FOR THE ACADEMICALLY TALENTED.

    ERIC Educational Resources Information Center

    HORN, R.A.

    MATERIALS ARE INTENDED FOR A UNIFIED AND ACCELERATED PLANE AND SOLID GEOMETRY COURSE AND FOR EASY MODIFICATION AND ADAPTATION BY EXPERIENCED OR INEXPERIENCED TEACHER. TEXTBOOKS TO WHICH THE GUIDE HAS BEEN KEYED ARE LISTED. UNITS ARE GIVEN FOR BOTH SEMESTERS WITH TIME ALLOTMENTS RECOMMENDED. EACH UNIT IS SUBDIVIDED INTO TOPICS AND OBJECTIVES,…

  20. Assessing the Effectiveness of Learning Solid Geometry by Using an Augmented Reality-Assisted Learning System

    ERIC Educational Resources Information Center

    Lin, Hao-Chiang Koong; Chen, Mei-Chi; Chang, Chih-Kai

    2015-01-01

    This study integrates augmented reality (AR) technology into teaching activities to design a learning system that assists junior high-school students in learning solid geometry. The following issues are addressed: (1) the relationship between achievements in mathematics and performance in spatial perception; (2) whether system-assisted learning…

  1. Comparative Effects of Two Modes of Computer-Assisted Instructional Package on Solid Geometry Achievement

    ERIC Educational Resources Information Center

    Gambari, Isiaka Amosa; Ezenwa, Victoria Ifeoma; Anyanwu, Romanus Chogozie

    2014-01-01

    The study examined the effects of two modes of computer-assisted instructional package on solid geometry achievement amongst senior secondary school students in Minna, Niger State, Nigeria. Also, the influence of gender on the performance of students exposed to CAI(AT) and CAI(AN) packages were examined. This study adopted a pretest-posttest…

  2. Graphene oxide film as solid lubricant.

    PubMed

    Liang, Hongyu; Bu, Yongfeng; Zhang, Junyan; Cao, Zhongyue; Liang, Aimin

    2013-07-10

    As a layered material, graphene oxide (GO) film is a good candidate for improving friction and antiwear performance of silicon-based MEMS devices. Via a green electrophoretic deposition (EPD) approach, GO films with tunable thickness in nanoscale are fabricated onto silicon wafer in a water solution. The morphology, microstructure, and mechanical properties as well as the friction coefficient and wear resistance of the films were investigated. The results indicated that the friction coefficient of silicon wafer was reduced to 1/6 its value, and the wear volume was reduced to 1/24 when using GO film as solid lubricant. These distinguished tribology performances suggest that GO films are expected to be good solid lubricants for silicon-based MEMS/NEMS devices. PMID:23786494

  3. The TMI regenerable solid oxide fuel cell

    NASA Technical Reports Server (NTRS)

    Cable, Thomas L.

    1995-01-01

    Energy storage and production in space requires rugged, reliable hardware which minimizes weight, volume, and maintenance while maximizing power output and usable energy storage. These systems generally consist of photovoltaic solar arrays which operate during sunlight cycles to provide system power and regenerate fuel (hydrogen) via water electrolysis; during dark cycles, hydrogen is converted by the fuel cell into system. The currently preferred configuration uses two separate systems (fuel cell and electrolyzer) in conjunction with photovoltaic cells. Fuel cell/electrolyzer system simplicity, reliability, and power-to-weight and power-to-volume ratios could be greatly improved if both power production (fuel cell) and power storage (electrolysis) functions can be integrated into a single unit. The Technology Management, Inc. (TMI), solid oxide fuel cell-based system offers the opportunity to both integrate fuel cell and electrolyzer functions into one unit and potentially simplify system requirements. Based an the TMI solid oxide fuel cell (SOPC) technology, the TMI integrated fuel cell/electrolyzer utilizes innovative gas storage and operational concepts and operates like a rechargeable 'hydrogen-oxygen battery'. Preliminary research has been completed on improved H2/H2O electrode (SOFC anode/electrolyzer cathode) materials for solid oxide, regenerative fuel cells. Improved H2/H2O electrode materials showed improved cell performance in both fuel cell and electrolysis modes in reversible cell tests. ln reversible fuel cell/electrolyzer mode, regenerative fuel cell efficiencies (ratio of power out (fuel cell mode) to power in (electrolyzer model)) improved from 50 percent (using conventional electrode materials) to over 80 percent. The new materials will allow the TMI SOFC system to operate as both the electrolyzer and fuel cell in a single unit. Preliminary system designs have also been developed which indicate the technical feasibility of using the TMI SOFC

  4. Tubular solid oxide fuel cell development program

    SciTech Connect

    1995-08-01

    This paper presents an overview of the Westinghouse Solid Oxide Fuel Cell (SOFC) development activities and current program status. The Westinghouse goal is to develop a cost effective cell that can operate for 50,000 to 100,000 hours. Progress toward this goal will be discussed and test results presented for multiple single cell tests which have now successfully exceeded 56,000 hours of continuous power operation at temperature. Results of development efforts to reduce cost and increase power output of tubular SOFCs are described.

  5. Sealant materials for solid oxide fuel cells

    SciTech Connect

    Krumpelt, M.

    1995-08-01

    The objective of this work is to complete the development of soft glass-ceramic sealants for the solid oxide fuel cell (SOFC). Among other requirements, the materials must soften at the operation temperature of the fuel cell (600-1000{degrees}C) to relieve stresses between stack components, and their thermal expansions must be tailored to match those of the stack materials. Specific objectives included addressing the needs of industrial fuel cell developers, based on their evaluation of samples we supply, as well as working with commercial glass producers to achieve scaled-up production of the materials without changing their properties.

  6. Solid oxide fuel cell combined cycles

    SciTech Connect

    Bevc, F.P.; Lundberg, W.L.; Bachovchin, D.M.

    1996-12-31

    The integration of the solid oxide fuel cell and combustion turbine technologies can result in combined-cycle power plants, fueled with natural gas, that have high efficiencies and clean gaseous emissions. Results of a study are presented in which conceptual designs were developed for 3 power plants based upon such an integration, and ranging in rating from 3 to 10 MW net ac. The plant cycles are described and characteristics of key components summarized. Also, plant design-point efficiency estimates are presented as well as values of other plant performance parameters.

  7. Tubular solid oxide fuel cell current collector

    DOEpatents

    Bischoff, Brian L.; Sutton, Theodore G.; Armstrong, Timothy R.

    2010-07-20

    An internal current collector for use inside a tubular solid oxide fuel cell (TSOFC) electrode comprises a tubular coil spring disposed concentrically within a TSOFC electrode and in firm uniform tangential electrical contact with the electrode inner surface. The current collector maximizes the contact area between the current collector and the electrode. The current collector is made of a metal that is electrically conductive and able to survive under the operational conditions of the fuel cell, i.e., the cathode in air, and the anode in fuel such as hydrogen, CO, CO.sub.2, H.sub.2O or H.sub.2S.

  8. Solid Oxide Fuel Cell Auxiliary Power Unit

    SciTech Connect

    J. Weber

    2001-12-12

    Solid Oxide Fuel Cell (SOFC) is an attractive, efficient, clean source of power for transportation, military, and stationary applications. Delphi has pioneered its application as an auxiliary Power Unit (APU) for transportation. Delphi is also interested in marketing this technology for stationary applications. Its key advantages are high efficiency and compatibility with gasoline, natural gas and diesel fuel. It's consistent with mechanizations that support the trend to low emissions. Delphi is committed to working with customers and partners to bring this novel technology to market.

  9. Mathematical modeling of solid oxide fuel cells

    NASA Technical Reports Server (NTRS)

    Lu, Cheng-Yi; Maloney, Thomas M.

    1988-01-01

    Development of predictive techniques, with regard to cell behavior, under various operating conditions is needed to improve cell performance, increase energy density, reduce manufacturing cost, and to broaden utilization of various fuels. Such technology would be especially beneficial for the solid oxide fuel cells (SOFC) at it early demonstration stage. The development of computer models to calculate the temperature, CD, reactant distributions in the tubular and monolithic SOFCs. Results indicate that problems of nonuniform heat generation and fuel gas depletion in the tubular cell module, and of size limitions in the monolithic (MOD 0) design may be encountered during FC operation.

  10. Solid oxide fuel cell having monolithic core

    DOEpatents

    Ackerman, J.P.; Young, J.E.

    1983-10-12

    A solid oxide fuel cell is described for electrochemically combining fuel and oxidant for generating galvanic output, wherein the cell core has an array of electrolyte and interconnect walls that are substantially devoid of any composite inert materials for support. Instead, the core is monolithic, where each electrolyte wall consists of thin layers of cathode and anode materials sandwiching a thin layer of electrolyte material therebetween. The electrolyte walls are arranged and backfolded between adjacent interconnect walls operable to define a plurality of core passageways alternately arranged where the inside faces thereof have only the anode material or only the cathode material exposed. Means direct the fuel to the anode-exposed core passageways and means direct the oxidant to the anode-exposed core passageways and means direct the oxidant to the cathode-exposed core passageway; and means also direct the galvanic output to an exterior circuit. Each layer of the electrolyte and interconnect materials is of the order of 0.002 to 0.01 cm thick; and each layer of the cathode and anode materials is of the order of 0.002 to 0.05 cm thick.

  11. Sintered electrode for solid oxide fuel cells

    DOEpatents

    Ruka, R.J.; Warner, K.A.

    1999-06-01

    A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation. 4 figs.

  12. Three-dimensional elastic stress and displacement analysis of finite geometry solids containing cracks

    NASA Technical Reports Server (NTRS)

    Kring, J.; Gyekenyesi, J.; Mendelson, A.

    1977-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement fields in finite geometry bars containing central, surface, and double-edge cracks under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Normal stresses and the stress intensity factor variation along the crack periphery are calculated using the obtained displacement field. The reported results demonstrate the usefulness of this method in calculating stress intensity factors for commonly encountered crack geometries in finite solids.

  13. Advanced alternate planar geometry solid oxide fuel cells

    SciTech Connect

    Prouse, D.; Elangovan, S.; Khandkar, A. ); Donelson, R.; Marianowski, L. )

    1989-01-01

    During this quarter, progress was made at Ceramatec in seal development and conductivity measurements of YIG compositions. A creep test was completed on the porous/dense/porous triilayer. IGT provided a discussion on possible interconnect materials. The following tasks are reported on: cell design analysis, program liaison and test facility preparation, cell component fabrication/development, out-of-cell tests. 9 figs, 2 tabs.

  14. Solid oxide fuel cell having monolithic core

    DOEpatents

    Ackerman, John P.; Young, John E.

    1984-01-01

    A solid oxide fuel cell for electrochemically combining fuel and oxidant for generating galvanic output, wherein the cell core has an array of electrolyte and interconnect walls that are substantially devoid of any composite inert materials for support. Instead, the core is monolithic, where each electrolyte wall consists of thin layers of cathode and anode materials sandwiching a thin layer of electrolyte material therebetween, and each interconnect wall consists of thin layers of the cathode and anode materials sandwiching a thin layer of interconnect material therebetween. The electrolyte walls are arranged and backfolded between adjacent interconnect walls operable to define a plurality of core passageways alternately arranged where the inside faces thereof have only the anode material or only the cathode material exposed. Means direct the fuel to the anode-exposed core passageways and means direct the oxidant to the cathode-exposed core passageway; and means also direct the galvanic output to an exterior circuit. Each layer of the electrolyte and interconnect materials is of the order of 0.002-0.01 cm thick; and each layer of the cathode and anode materials is of the order of 0.002-0.05 cm thick.

  15. Cartesian grid simulations of gas-solids flow systems with complex geometry

    SciTech Connect

    Dietiker, Jean-Francois; Li, Tingwen; Garg, Rahul; Shahnam, Mehrdad

    2013-02-01

    Complex geometries encountered in many applications of gas–solids flow need special treatment in most legacy multiphase flow solvers with Cartesian numerical grid. This paper briefly outlines the implementation of a cut cell technique in the open-source multiphase flow solver—MFIX for accurate representation of complex geometries. Specifically, applications of the Cartesian cut cell method to different gas–solids fluidization systems including a small scale bubbling fluidized bed with submerged tube bundle and a complete pilot-scale circulating fluidized bed will be presented. In addition to qualitative predictions on the general flow behaviors inside each system, quantitative comparison with the available experimental data will be presented. Furthermore, some results on extending the current cut-cell technique to Lagrangian–Eulerian simulations will be presented.

  16. Stability of solid oxide fuel cell materials

    SciTech Connect

    Armstrong, T.R.; Bates, J.L.; Coffey, G.W.; Pederson, L.R.

    1996-08-01

    Chromite interconnection materials in an SOFC are exposed to both highly oxidizing conditions at the cathode and to highly reducing conditions at the anode. Because such conditions could lead to component failure, the authors have evaluated thermal, electrical, chemical, and structural stabilities of these materials as a function of temperature and oxygen partial pressure. The crystal lattice of the chromites was shown to expand for oxygen partial pressures smaller than 10{sup {minus}10} atm, which could lead to cracking and debonding in an SOFC. Highly substituted lanthanum chromite compositions were the most susceptible to lattice expansion; yttrium chromites showed better dimensional stability by more than a factor of two. New chromite compositions were developed that showed little tendency for lattice expansion under strongly reducing conditions, yet provided a good thermal expansion match to other fuel cell components. Use of these new chromite interconnect compositions should improve long-term SOFC performance, particularly for planar cell configurations. Thermodynamic properties of substituted lanthanum manganite cathode compositions have been determined through measurement of electromotive force as a function of temperature. Critical oxygen decomposition pressures for Sr and Ca-substituted lanthanum manganites were established using cells based on a zirconia electrolyte. Strontium oxide and calcium oxide activities in a lanthanum manganite matrix were determined using cells based on strontium fluoride and calcium fluoride electrolytes, respectively. The compositional range of single-phase behavior of these ABO{sub 3}-type perovskites was established as a function of A/B cation ratios and the extent of acceptor doping. Before this work, very little thermodynamic information was in existence for substituted manganite compositions. Such information is needed to predict the long-term stability of solid oxide fuel cell assemblies.

  17. Interconnection of bundled solid oxide fuel cells

    SciTech Connect

    Brown, Michael; Bessette, II, Norman F; Litka, Anthony F; Schmidt, Douglas S

    2014-01-14

    A system and method for electrically interconnecting a plurality of fuel cells to provide dense packing of the fuel cells. Each one of the plurality of fuel cells has a plurality of discrete electrical connection points along an outer surface. Electrical connections are made directly between the discrete electrical connection points of adjacent fuel cells so that the fuel cells can be packed more densely. Fuel cells have at least one outer electrode and at least one discrete interconnection to an inner electrode, wherein the outer electrode is one of a cathode and and anode and wherein the inner electrode is the other of the cathode and the anode. In tubular solid oxide fuel cells the discrete electrical connection points are spaced along the length of the fuel cell.

  18. Tubular solid oxide fuel cell demonstration activities

    SciTech Connect

    Veyo, S.E.

    1995-08-01

    The development of a viable fuel cell driven electrical power generation system involves not only the development of cell and stack technology, but also the development of the overall system concept, the strategy for control, and the ancillary subsystems. The design requirements used to guide system development must reflect a customer focus in order to evolve a commercial product. In order to obtain useful customer feedback, Westinghouse has practiced the deployment with customers of fully integrated, automatically controlled, packaged solid oxide fuel cell power generation systems. These field units have served to demonstrate to customers first hand the beneficial attributes of the SOFC, to expose deficiencies through experience in order to guide continued development, and to garner real world feedback and data concerning not only cell and stack parameters, but also transportation, installation, permitting and licensing, start-up and shutdown, system alarming, fault detection, fault response, and operator interaction.

  19. High power density solid oxide fuel cells

    DOEpatents

    Pham, Ai Quoc; Glass, Robert S.

    2004-10-12

    A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

  20. Solid oxide fuel cell matrix and modules

    DOEpatents

    Riley, B.

    1988-04-22

    Porous refractory ceramic blocks arranged in an abutting, stacked configuration and forming a three dimensional array provide a support structure and coupling means for a plurality of solid oxide fuel cells (SOFCs). The stack of ceramic blocks is self-supporting, with a plurality of such stacked arrays forming a matrix enclosed in an insulating refractory brick structure having an outer steel layer. The necessary connections for air, fuel, burnt gas, and anode and cathode connections are provided through the brick and steel outer shell. The ceramic blocks are so designed with respect to the strings of modules that by simple and logical design the strings could be replaced by hot reloading if one should fail. The hot reloading concept has not been included in any previous designs. 11 figs.

  1. Solid oxide fuel cell process and apparatus

    DOEpatents

    Cooper, Matthew Ellis; Bayless, David J.; Trembly, Jason P.

    2011-11-15

    Conveying gas containing sulfur through a sulfur tolerant planar solid oxide fuel cell (PSOFC) stack for sulfur scrubbing, followed by conveying the gas through a non-sulfur tolerant PSOFC stack. The sulfur tolerant PSOFC stack utilizes anode materials, such as LSV, that selectively convert H.sub.2S present in the fuel stream to other non-poisoning sulfur compounds. The remaining balance of gases remaining in the completely or near H.sub.2S-free exhaust fuel stream is then used as the fuel for the conventional PSOFC stack that is downstream of the sulfur-tolerant PSOFC. A broad range of fuels such as gasified coal, natural gas and reformed hydrocarbons are used to produce electricity.

  2. Solid oxide fuel cell power system development

    SciTech Connect

    Kerr, Rick; Wall, Mark; Sullivan, Neal

    2015-06-26

    This report summarizes the progress made during this contractual period in achieving the goal of developing the solid oxide fuel cell (SOFC) cell and stack technology to be suitable for use in highly-efficient, economically-competitive, commercially deployed electrical power systems. Progress was made in further understanding cell and stack degradation mechanisms in order to increase stack reliability toward achieving a 4+ year lifetime, in cost reduction developments to meet the SECA stack cost target of $175/kW (in 2007 dollars), and in operating the SOFC technology in a multi-stack system in a real-world environment to understand the requirements for reliably designing and operating a large, stationary power system.

  3. Computational modeling of solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Penmetsa, Satish Kumar

    In the ongoing search for alternative and environmentally friendly power generation facilities, the solid oxide fuel cell (SOFC) is considered one of the prime candidates for the next generation of energy conversion devices due to its capability to provide environmentally friendly and highly efficient power generation. Moreover, SOFCs are less sensitive to composition of fuel as compared to other types of fuel cells, and internal reforming of the hydrocarbon fuel cell can be performed because of higher operating temperature range of 700°C--1000°C. This allows us to use different types of hydrocarbon fuels in SOFCs. The objective of this study is to develop a three-dimensional computational model for the simulation of a solid oxide fuel cell unit to analyze the complex internal transport mechanisms and sensitivity of the cell with different operating conditions, and also to develop SOFC with higher operating current density with a more uniform gas distributions in the electrodes and with lower ohmic losses. This model includes mass transfer processes due to convection and diffusion in the gas flow channels based on the Navier-Stokes equations as well as combined diffusion and advection in electrodes using Brinkman's hydrodynamic equation and associated electrochemical reactions in the trilayer of the SOFC. Gas transport characteristics in terms of three-dimensional spatial distributions of reactant gases and their effects on electrochemical reactions at the electrode-electrolyte interface, and in the resulting polarizations, are evaluated for varying pressure conditions. Results show the significance of the Brinkman's hydrodynamic model in electrodes to achieve more uniform gas concentration distributions while using a higher operating pressure and over a higher range of operating current densities.

  4. SPH-DCDEM model for arbitrary geometries in free surface solid-fluid flows

    NASA Astrophysics Data System (ADS)

    Canelas, Ricardo B.; Crespo, Alejandro J. C.; Domínguez, Jose M.; Ferreira, Rui M. L.; Gómez-Gesteira, Moncho

    2016-05-01

    A unified discretization of rigid solids and fluids is introduced, allowing for resolved simulations of fluid-solid phases within a meshless framework. The numerical solution, attained by Smoothed Particle Hydrodynamics (SPH) and a variation of Discrete Element Method (DEM), the Distributed Contact Discrete Element Method (DCDEM) discretization, is achieved by directly considering solid-solid and solid-fluid interactions. The novelty of the work is centred on the generalization of the coupling of the DEM and SPH methodologies for resolved simulations, allowing for state-of-the-art contact mechanics theories to be used in arbitrary geometries, while fluid to solid and vice versa momentum transfers are accurately described. The methods are introduced, analysed and discussed. Initial validations on the DCDEM and the fluid coupling are presented, drawing from test cases in the literature. An experimental campaign serves as a validation point for complex, large scale solid-fluid flows, where a set of blocks in several configurations is subjected to a dam-break wave. Blocks are tracked and positions are then compared between experimental data and the numerical solutions. A Particle Image Velocimetry (PIV) technique allows for the quantification of the flow field and direct comparison with numerical data. The results show that the model is accurate and is capable of treating highly complex interactions, such as transport of debris or hydrodynamic actions on structures, if relevant scales are reproduced.

  5. Advanced materials for solid oxide fuel cells

    SciTech Connect

    Armstrong, T.R.; Stevenson, J.

    1995-08-01

    The purpose of this research is to improve the properties of the current state-of-the-art materials used for solid oxide fuel cells (SOFCs). The objectives are to: (1) develop materials based on modifications of the state-of-the-art materials; (2) minimize or eliminate stability problems in the cathode, anode, and interconnect; (3) Electrochemically evaluate (in reproducible and controlled laboratory tests) the current state-of-the-art air electrode materials and cathode/electrolyte interfacial properties; (4) Develop accelerated electrochemical test methods to evaluate the performance of SOFCs under controlled and reproducible conditions; and (5) Develop and test materials for use in low-temperature SOFCs. The goal is to modify and improve the current state-of-the-art materials and minimize the total number of cations in each material to avoid negative effects on the materials properties. Materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabricatoin and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component composition and processing on those reactions.

  6. Alternative materials for solid oxide fuel cells

    SciTech Connect

    Stevenson, J.W.; Armstrong, T.R.

    1994-08-01

    The purpose of this research is to develop alternative materials for solid oxide fuel cell (SOFC) interconnections and electrodes with improved electrical, thermal, and electrochemical properties. A second objective is to develop synthesis and fabrication methods for these materials whereby they can be processed in air into SOFCs. The approach is to (1) develop modifications of the current, state-of-the-art materials used in SOFCs, (2) minimize the number of cations used in the SOFC materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabrication and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component composition and processing on those reactions. This paper summarizes a comprehensive study that assessed the effect of ambient oxygen partial pressure on the stability of air-sinterable chromites and the sintering behavior of doped lanthanum manganites.

  7. Reactive vaporization of oxides in solid oxide fuel cell systems

    NASA Astrophysics Data System (ADS)

    Key, Camas Fought

    Metals such as chromium, aluminum and silicon are of extreme technological and industrial importance due to the corrosion resistance they offer in oxidizing environments at high temperature. Much of this robustness is based on the formation of a thin, well-adhered metal-oxide (MO) layer on the surface of the metal. In particularly corrosive environments or at high-enough temperatures and or pressures, the MO will chemically react with constituents in the surrounding gas, removing atoms from the solid. For many systems, material loss and subsequent mechanical failure is the foremost concern. However, in solid oxide fuel cell (SOFC) systems, the presence of gaseous metal species leads to severe degradation in electrochemical performance well before mechanical limits are reached. Reactive vaporization from ferritic stainless steels, chromia, aluminosilicates and a candidate electrode material (Sr2VMoO6), was investigated using the transpiration method. Two novel collection methods were employed: condensation of vapors on wafer collectors analyzed with Rutherford backscattering spectrometry (RBS); and, condensation of vapors on quartz wool analyzed via inductively coupled plasma mass spectroscopy (ICP-MS). Identification and quantification of vapor species provided assessment of material performance in SOFC environments. Experiments demonstrated that Cr vapor species from ferritic stainless steels used for SOFC interconnect applications could be reduced by as much as one order of magnitude through the application of barrier coatings. Base alloys were compared and exhibited a variety of Cr vaporization rates despite being similar in composition, thus illustrating the importance of minor elemental constituents in the alloy. Measurements identified Si as the primary volatile element in aluminosilicate materials when Si concentrations in the bulk material were as low as one percent. Aluminosilicate materials demonstrated a burn out phase during the first hundred hours at

  8. Degradation in Solid Oxide Cells During High Temperature Electrolysis

    SciTech Connect

    Manohar Sohal

    2009-05-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells. One goal of that project is to address the technical and degradation issues associated with solid oxide electrolysis cells. This report covers a variety of these degradation issues, which were discussed during a workshop on “Degradation in Solid Oxide Electrolysis Cells and Strategies for its Mitigation,” held in Phoenix, AZ on October 27, 2008. Three major degradation issues related to solid oxide electrolysis cells discussed at the workshop are: • Delamination of O2-electrode and bond layer on steam/O2-electrode side • Contaminants (Ni, Cr, Si, etc.) on reaction sites (triple-phase boundary) • Loss of electrical/ionic conductivity of electrolyte. This list is not all inclusive, but the workshop summary can be useful in providing a direction for future research related to the degradation of solid oxide electrolysis cells.

  9. Monolithic Solid Oxide Fuel Cell development

    NASA Technical Reports Server (NTRS)

    Myles, K. M.; Mcpheeters, C. C.

    1989-01-01

    The Monolithic Solid Oxide Fuel Cell (MSOFC) is an oxide-ceramic structure in which appropriate electronic and ionic conductors are fabricated in a honeycomb shape similar to a block of corrugated paperboard. These electronic and ionic conductors are arranged to provide short conduction paths to minimize resistive losses. The power density achievable with the MSOFC is expected to be about 8 kW/kg or 4 kW/L, at fuel efficienceis over 50 percent, because of small cell size and low resistive losses in the materials. The MSOFC operates in the range of 700 to 1000 C, at which temperatures rapid reform of hydrocarbon fuels is expected within the nickel-YSZ fuel channels. Tape casting and hot roll calendering are used to fabricate the MSOFC structure. The performance of the MSOFC has improved significantly during the course of development. The limitation of this system, based on materials resistance alone without interfacial resistances, is 0.093 ohm-sq cm area-specific resistance (ASR). The current typical performance of MSOFC single cells is characterized by ASRs of about 0.4 to 0.5 ohm-sq cm. With further development the ASR is expected to be reduced below 0.2 ohm-sq cm, which will result in power levels greater than 1.4 W/sq cm. The feasibility of the MSOFC concept was proven, and the performance was dramatically improved. The differences in thermal expansion coefficients and firing shrinkages among the fuel cell materials were minimized. As a result of good matching of these properties, the MSOFC structure was successfully fabricated with few defects, and the system shows excellent promise for development into a practical power source.

  10. Monolithic Solid Oxide Fuel Cell development

    NASA Astrophysics Data System (ADS)

    Myles, K. M.; McPheeters, C. C.

    1989-12-01

    The Monolithic Solid Oxide Fuel Cell (MSOFC) is an oxide-ceramic structure in which appropriate electronic and ionic conductors are fabricated in a honeycomb shape similar to a block of corrugated paperboard. These electronic and ionic conductors are arranged to provide short conduction paths to minimize resistive losses. The power density achievable with the MSOFC is expected to be about 8 kW/kg or 4 kW/L, at fuel efficienceis over 50 percent, because of small cell size and low resistive losses in the materials. The MSOFC operates in the range of 700 to 1000 C, at which temperatures rapid reform of hydrocarbon fuels is expected within the nickel-YSZ fuel channels. Tape casting and hot roll calendering are used to fabricate the MSOFC structure. The performance of the MSOFC has improved significantly during the course of development. The limitation of this system, based on materials resistance alone without interfacial resistances, is 0.093 ohm-sq cm area-specific resistance (ASR). The current typical performance of MSOFC single cells is characterized by ASRs of about 0.4 to 0.5 ohm-sq cm. With further development the ASR is expected to be reduced below 0.2 ohm-sq cm, which will result in power levels greater than 1.4 W/sq cm. The feasibility of the MSOFC concept was proven, and the performance was dramatically improved. The differences in thermal expansion coefficients and firing shrinkages among the fuel cell materials were minimized. As a result of good matching of these properties, the MSOFC structure was successfully fabricated with few defects, and the system shows excellent promise for development into a practical power source.

  11. Domain Decomposition of a Constructive Solid Geometry Monte Carlo Transport Code

    SciTech Connect

    O'Brien, M J; Joy, K I; Procassini, R J; Greenman, G M

    2008-12-07

    Domain decomposition has been implemented in a Constructive Solid Geometry (CSG) Monte Carlo neutron transport code. Previous methods to parallelize a CSG code relied entirely on particle parallelism; but in our approach we distribute the geometry as well as the particles across processors. This enables calculations whose geometric description is larger than what could fit in memory of a single processor, thus it must be distributed across processors. In addition to enabling very large calculations, we show that domain decomposition can speed up calculations compared to particle parallelism alone. We also show results of a calculation of the proposed Laser Inertial-Confinement Fusion-Fission Energy (LIFE) facility, which has 5.6 million CSG parts.

  12. Stress analysis and stress-intensity factors for finite geometry solids containing rectangular surface cracks

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, J. P.; Mendelson, A.

    1977-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses, and the stress-intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress-intensity factors are also obtained for a through-thickness, center-cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress-intensity factors for commonly encountered surface crack geometries in finite solids

  13. Stress analysis and stress intensity factors for finite geometry solids containing rectangular surface cracks

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, J. P.; Mendelson, A.

    1975-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses and the stress intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress intensity factors are also obtained for a through-thickness, center cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress intensity factors for commonly encountered surface crack geometries in finite solids.

  14. Durability evaluation of reversible solid oxide cells

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyu; O'Brien, James E.; O'Brien, Robert C.; Housley, Gregory K.

    2013-11-01

    An experimental investigation on the performance and durability of single solid oxide cells (SOCs) is under way at the Idaho National Laboratory. Reversible operation of SOCs includes electricity generation in the fuel cell mode and hydrogen generation in the electrolysis mode. Degradation is a more significant issue when operating SOCs in the electrolysis mode. In order to understand and mitigate the degradation issues in high temperature electrolysis, single SOCs with different configurations from several manufacturers have been evaluated for initial performance and long-term durability. Cells were obtained from four industrial partners. Cells from Ceramatec Inc. and Materials and Systems Research Inc. (MSRI) showed improved durability in electrolysis mode compared to previous stack tests. Cells from Saint Gobain Advanced Materials Inc. (St. Gobain) and SOFCPower Inc. demonstrated stable performance in the fuel cell mode, but rapid degradation in the electrolysis mode, especially at high current density. Electrolyte-electrode delamination was found to have a significant impact on degradation in some cases. Enhanced bonding between electrolyte and electrode and modification of the electrode microstructure helped to mitigate degradation. Polarization scans and AC impedance measurements were performed during the tests to characterize cell performance and degradation.

  15. Solid oxide fuel cell matrix and modules

    DOEpatents

    Riley, Brian

    1990-01-01

    Porous refractory ceramic blocks arranged in an abutting, stacked configuration and forming a three dimensional array provide a support structure and coupling means for a plurality of solid oxide fuel cells (SOFCs). Each of the blocks includes a square center channel which forms a vertical shaft when the blocks are arranged in a stacked array. Positioned within the channel is a SOFC unit cell such that a plurality of such SOFC units disposed within a vertical shaft form a string of SOFC units coupled in series. A first pair of facing inner walls of each of the blocks each include an interconnecting channel hole cut horizontally and vertically into the block walls to form gas exit channels. A second pair of facing lateral walls of each block further include a pair of inner half circular grooves which form sleeves to accommodate anode fuel and cathode air tubes. The stack of ceramic blocks is self-supporting, with a plurality of such stacked arrays forming a matrix enclosed in an insulating refractory brick structure having an outer steel layer. The necessary connections for air, fuel, burnt gas, and anode and cathode connections are provided through the brick and steel outer shell. The ceramic blocks are so designed with respect to the strings of modules that by simple and logical design the strings could be replaced by hot reloading if one should fail. The hot reloading concept has not been included in any previous designs.

  16. Modeling Degradation in Solid Oxide Electrolysis Cells

    SciTech Connect

    Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff

    2010-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  17. Nanotubular array solid oxide fuel cell.

    PubMed

    Motoyama, Munekazu; Chao, Cheng-Chieh; An, Jihwan; Jung, Hee Joon; Gür, Turgut M; Prinz, Friedrich B

    2014-01-28

    This report presents a demonstration and characterization of a nanotubular array of solid oxide fuel cells (SOFCs) made of one-end-closed hollow tube Ni/yttria-stabilized zirconia/Pt membrane electrode assemblies (MEAs). The tubular MEAs are nominally ∼5 μm long and have <500 nm outside diameter with total MEA thickness of nearly 50 nm. Open circuit voltages up to 660 mV (vs air) and power densities up to 1.3 μW cm(-2) were measured at 550 °C using H2 as fuel. The paper also introduces a fabrication methodology primarily based on a template process involving atomic layer deposition and electrodeposition for building the nanotubular MEA architecture as an important step toward achieving high surface area ultrathin SOFCs operating in the intermediate to low-temperature regime. A fabricated nanotubular SOFC theoretically attains a 20-fold increase in the effective surface, while projections indicate the possibility of achieving up to 40-fold. PMID:24266776

  18. Nanostructured Solid Oxide Fuel Cell Electrodes

    SciTech Connect

    Sholklapper, Tal Zvi

    2007-12-15

    The ability of Solid Oxide Fuel Cells (SOFC) to directly and efficiently convert the chemical energy in hydrocarbon fuels to electricity places the technology in a unique and exciting position to play a significant role in the clean energy revolution. In order to make SOFC technology cost competitive with existing technologies, the operating temperatures have been decreased to the range where costly ceramic components may be substituted with inexpensive metal components within the cell and stack design. However, a number of issues have arisen due to this decrease in temperature: decreased electrolyte ionic conductivity, cathode reaction rate limitations, and a decrease in anode contaminant tolerance. While the decrease in electrolyte ionic conductivities has been countered by decreasing the electrolyte thickness, the electrode limitations have remained a more difficult problem. Nanostructuring SOFC electrodes addresses the major electrode issues. The infiltration method used in this dissertation to produce nanostructure SOFC electrodes creates a connected network of nanoparticles; since the method allows for the incorporation of the nanoparticles after electrode backbone formation, previously incompatible advanced electrocatalysts can be infiltrated providing electronic conductivity and electrocatalysis within well-formed electrolyte backbones. Furthermore, the method is used to significantly enhance the conventional electrode design by adding secondary electrocatalysts. Performance enhancement and improved anode contamination tolerance are demonstrated in each of the electrodes. Additionally, cell processing and the infiltration method developed in conjunction with this dissertation are reviewed.

  19. Durability Evaluation of Reversible Solid Oxide Cells

    SciTech Connect

    Xiaoyu Zhang; James E. O'Brien; Robert C. O'Brien; Gregory K. Housley

    2013-11-01

    An experimental investigation on the performance and durability of single solid oxide cells (SOCs) is under way at the Idaho National Laboratory. Reversible operation of SOCs includes electricity generation in the fuel cell mode and hydrogen generation in the electrolysis mode. Degradation is a more significant issue when operating SOCs in the electrolysis mode. In order to understand and mitigate the degradation issues in high temperature electrolysis, single SOCs with different configurations from several manufacturers have been evaluated for initial performance and long-term durability. A new test apparatus for single cell and small stack tests has been developed for this purpose. Cells were obtained from four industrial partners. Cells from Ceramatec Inc. and Materials and Systems Research Inc. (MSRI) showed improved durability in electrolysis mode compared to previous stack tests. Cells from Saint Gobain Advanced Materials Inc. (St. Gobain) and SOFCPower Inc. demonstrated stable performance in the fuel cell mode, but rapid degradation in the electrolysis mode, especially at high current density. Electrolyte-electrode delamination was found to have a significant impact on degradation in some cases. Enhanced bonding between electrolyte and electrode and modification of the electrode microstructure helped to mitigate degradation. Polarization scans and AC impedance measurements were performed during the tests to characterize cell performance and degradation.

  20. Method of electrode fabrication for solid oxide electrochemical cells

    DOEpatents

    Jensen, Russell R.

    1990-01-01

    A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used.

  1. Method of electrode fabrication for solid oxide electrochemical cells

    DOEpatents

    Jensen, R.R.

    1990-11-20

    A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used. 5 figs.

  2. Energy storage in ultrathin solid oxide fuel cells.

    PubMed

    Van Overmeere, Quentin; Kerman, Kian; Ramanathan, Shriram

    2012-07-11

    The power output of hydrogen fuel cells quickly decreases to zero if the fuel supply is interrupted. We demonstrate thin film solid oxide fuel cells with nanostructured vanadium oxide anodes that generate power for significantly longer time than reference porous platinum anode thin film solid oxide fuel cells when the fuel supply is interrupted. The charge storage mechanism was investigated quantitatively with likely identified contributions from the oxidation of the vanadium oxide anode, its hydrogen storage properties, and different oxygen concentration at the electrodes. Fuel cells capable of storing charge even for short periods of time could contribute to ultraminiaturization of power sources for mobile energy. PMID:22712483

  3. Solids flow pattern in the exit region of a CFB -- Furnace influence of exit geometry

    SciTech Connect

    Johnsson, F.; Leckner, B.; Vrager, A.

    1999-07-01

    The effect of the exit geometry on the flow pattern in a circulating fluidized bed (CFB) riser was studied in a cold 1/9 scale model of the Chalmers 12 MW CFB boiler. The model, which is made of transparent perspex, was operated according to the simplified scaling laws proposed by Glicksman et al. (1993). 12 different exit configurations were compared at different fluidization velocities. Two bed materials were used: iron and steel. In order to verify the scaling laws, vertical pressure and density profiles, net solids flux and pressure fluctuations measured in the model were compared with corresponding results from the 12 MW boiler. The exit configurations were evaluated by comparing the net solids fluxes and the vertical pressure and density profiles of the riser. The overall flow behavior of the scale-model was found to be similar to that of the boiler: A dense bottom bed, a splash zone and a transport zone could be identified. The dynamics (in-bed pressure fluctuations) of the bottom bed were in agreement with those of the boiler. Differences between net solids fluxes during operation with different exits were in some cases of an order of magnitude. However, there were almost no difference in solids flux between an abrupt exit, an extended exit (such as that of the boiler) and an enhanced extension. A decrease in the net solids flux (increase in the internal back-mixing) could be obtained by inserting obstacles in the upper part of the riser, and an increase in the net solids flux was achieved by narrowing the duct from the riser to the cyclone inlet (increasing the average velocity in the duct). The original configuration of the duct with an inclined bottom results in back-mixing from the duct to the furnace, thereby reducing the net (external) solids flux.

  4. Neutralization Of Multiply Charged Rydberg Ions Interacting With Solid Surfaces Under The Grazing Incidence Geometry

    NASA Astrophysics Data System (ADS)

    Majkic, M. D.; Nedeljkovic, N. N.; Galijas, S. M. D.

    2010-07-01

    We elaborated the time-symmetric, two-state vector model to investigate the intermediate stages of the electron capture into the Rydberg states of multiply charged ions interacting with solid surface under the grazing incidence geometry. The neutralization distances for the ions XeZ+ interacting with Al-surface are calculated, for core charges Z ?[5,30]. The corresponding mean neutralization distances are in agreement with the data deduced from the measured kinetic energy gain due to the image acceleration of the ions.

  5. Solid Oxide Fuel Cell Systems PVL Line

    SciTech Connect

    Susan Shearer - Stark State College; Gregory Rush - Rolls-Royce Fuel Cell Systems

    2012-05-01

    In July 2010, Stark State College (SSC), received Grant DE-EE0003229 from the U.S. Department of Energy (DOE), Golden Field Office, for the development of the electrical and control systems, and mechanical commissioning of a unique 20kW scale high-pressure, high temperature, natural gas fueled Stack Block Test System (SBTS). SSC worked closely with subcontractor, Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) over a 13 month period to successfully complete the project activities. This system will be utilized by RRFCS for pre-commercial technology development and training of SSC student interns. In the longer term, when RRFCS is producing commercial products, SSC will utilize the equipment for workforce training. In addition to DOE Hydrogen, Fuel Cells, and Infrastructure Technologies program funding, RRFCS internal funds, funds from the state of Ohio, and funding from the DOE Solid State Energy Conversion Alliance (SECA) program have been utilized to design, develop and commission this equipment. Construction of the SBTS (mechanical components) was performed under a Grant from the State of Ohio through Ohio's Third Frontier program (Grant TECH 08-053). This Ohio program supported development of a system that uses natural gas as a fuel. Funding was provided under the Department of Energy (DOE) Solid-state Energy Conversion Alliance (SECA) program for modifications required to test on coal synthesis gas. The subject DOE program provided funding for the electrical build, control system development and mechanical commissioning. Performance testing, which includes electrical commissioning, was subsequently performed under the DOE SECA program. Rolls-Royce Fuel Cell Systems is developing a megawatt-scale solid oxide fuel cell (SOFC) stationary power generation system. This system, based on RRFCS proprietary technology, is fueled with natural gas, and operates at elevated pressure. A critical success factor for development of the full scale system is the capability to

  6. Modeling for CVD of Solid Oxide Electrolyte

    SciTech Connect

    Starr, T.L.

    2002-09-18

    Because of its low thermal conductivity, high thermal expansion and high oxygen ion conductivity yttria-stabilized zirconia (YSZ) is the material of choice for high temperature electrolyte applications. Current coating fabrication methods have their drawbacks, however. Air plasma spray (APS) is a relatively low-cost process and is suitable for large and relatively complex shapes. it is difficult to produce uniform, relatively thin coatings with this process, however, and the coatings do not exhibit the columnar microstructure that is needed for reliable, long-term performance. The electron-beam physical vapor deposition (EB-PVD) process does produce the desirable microstructure, however, the capital cost of these systems is very high and the line-of-sight nature of the process limits coating uniformity and the ability to coat large and complex shapes. The chemical vapor deposition (CVD) process also produces the desirable columnar microstructure and--under proper conditions--can produce uniform coatings over complex shapes. CVD has been used for many materials but is relatively undeveloped for oxides, in general, and for zirconia, in particular. The overall goal of this project--a joint effort of the University of Louisville and Oak Ridge National Laboratory (ORNL)--is to develop the YSZ CVD process for high temperature electrolyte applications. This report describes the modeling effort at the University of Louisville, which supports the experimental work at ORNL. Early work on CVD of zirconia and yttria used metal chlorides, which react with water vapor to form solid oxide. Because of this rapid gas-phase reaction the water generally is formed in-situ using the reverse water-gas-shift reaction or a microwave plasma. Even with these arrangements gas-phase nucleation and powder formation are problems when using these precursors. Recent efforts on CVD of zirconia and YSZ have focused on use of metal-organic precursors (MOCVD). These are more stable in the gas

  7. Intermediate Temperature Solid Oxide Fuel Cell Development

    SciTech Connect

    S. Elangovan; Scott Barnett; Sossina Haile

    2008-06-30

    Solid oxide fuel cells (SOFCs) are high efficiency energy conversion devices. Present materials set, using yttria stabilized zirconia (YSZ) electrolyte, limit the cell operating temperatures to 800 C or higher. It has become increasingly evident however that lowering the operating temperature would provide a more expeditious route to commercialization. The advantages of intermediate temperature (600 to 800 C) operation are related to both economic and materials issues. Lower operating temperature allows the use of low cost materials for the balance of plant and limits degradation arising from materials interactions. When the SOFC operating temperature is in the range of 600 to 700 C, it is also possible to partially reform hydrocarbon fuels within the stack providing additional system cost savings by reducing the air preheat heat-exchanger and blower size. The promise of Sr and Mg doped lanthanum gallate (LSGM) electrolyte materials, based on their high ionic conductivity and oxygen transference number at the intermediate temperature is well recognized. The focus of the present project was two-fold: (a) Identify a cell fabrication technique to achieve the benefits of lanthanum gallate material, and (b) Investigate alternative cathode materials that demonstrate low cathode polarization losses at the intermediate temperature. A porous matrix supported, thin film cell configuration was fabricated. The electrode material precursor was infiltrated into the porous matrix and the counter electrode was screen printed. Both anode and cathode infiltration produced high performance cells. Comparison of the two approaches showed that an infiltrated cathode cells may have advantages in high fuel utilization operations. Two new cathode materials were evaluated. Northwestern University investigated LSGM-ceria composite cathode while Caltech evaluated Ba-Sr-Co-Fe (BSCF) based pervoskite cathode. Both cathode materials showed lower polarization losses at temperatures as low as 600

  8. The TMI Regenerative Solid Oxide Fuel Cell

    NASA Technical Reports Server (NTRS)

    Cable, Thomas L.; Ruhl, Robert C.; Petrik, Michael

    1996-01-01

    Energy storage and production in space requires rugged, reliable hardware which minimizes weight, volume, and maintenance while maximizing power output and usable energy storage. Systems generally consist of photovoltaic solar arrays which operate (during sunlight cycles) to provide system power and regenerate fuel (hydrogen) via water electrolysis and (during dark cycles) fuel cells convert hydrogen into electricity. Common configurations use two separate systems (fuel cell and electrolyzer) in conjunction with photovoltaic cells. Reliability, power to weight and power to volume ratios could be greatly improved if both power production (fuel cells) and power storage (electrolysis) functions can be integrated into a single unit. The solid oxide fuel cell (SOFC) based design integrates fuel cell and electrolyzer functions and potentially simplifies system requirements. The integrated fuel cell/electrolyzer design also utilizes innovative gas storage concepts and operates like a rechargeable 'hydrogen-oxygen battery'. Preliminary research has been completed on improved H2/H20 electrode (SOFC anode/electrolyzer cathode) materials for regenerative fuel cells. Tests have shown improved cell performance in both fuel and electrolysis modes in reversible fuel cell tests. Regenerative fuel cell efficiencies, ratio of power out (fuel cell mode) to power in (electrolyzer mode), improved from 50 percent using conventional electrode materials to over 80 percent. The new materials will allow a single SOFC system to operate as both the electolyzer and fuel cell. Preliminary system designs have also been developed to show the technical feasibility of using the design for space applications requiring high energy storage efficiencies and high specific energy. Small space systems also have potential for dual-use, terrestrial applications.

  9. Glass/BNNT Composite for Sealing Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Hurst, Janet B.; Choi, Sung R.

    2007-01-01

    A material consisting of a barium calcium aluminosilicate glass reinforced with 4 weight percent of boron nitride nanotubes (BNNTs) has shown promise for use as a sealant in planar solid oxide fuel cells (SOFCs).

  10. Solid oxide fuel cell operable over wide temperature range

    DOEpatents

    Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

    2001-01-01

    Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

  11. Symmetrical, bi-electrode supported solid oxide fuel cell

    NASA Technical Reports Server (NTRS)

    Cable, Thomas L. (Inventor); Sofie, Stephen W. (Inventor)

    2009-01-01

    The present invention is a symmetrical bi-electrode supported solid oxide fuel cell comprising a sintered monolithic framework having graded pore electrode scaffolds that, upon treatment with metal solutions and heat subsequent to sintering, acquire respective anodic and cathodic catalytic activity. The invention is also a method for making such a solid oxide fuel cell. The graded pore structure of the graded pore electrode scaffolds in achieved by a novel freeze casting for YSZ tape.

  12. Delivery system for molten salt oxidation of solid waste

    DOEpatents

    Brummond, William A.; Squire, Dwight V.; Robinson, Jeffrey A.; House, Palmer A.

    2002-01-01

    The present invention is a delivery system for safety injecting solid waste particles, including mixed wastes, into a molten salt bath for destruction by the process of molten salt oxidation. The delivery system includes a feeder system and an injector that allow the solid waste stream to be accurately metered, evenly dispersed in the oxidant gas, and maintained at a temperature below incineration temperature while entering the molten salt reactor.

  13. Solid oxide fuel cell steam reforming power system

    DOEpatents

    Chick, Lawrence A.; Sprenkle, Vincent L.; Powell, Michael R.; Meinhardt, Kerry D.; Whyatt, Greg A.

    2013-03-12

    The present invention is a Solid Oxide Fuel Cell Reforming Power System that utilizes adiabatic reforming of reformate within this system. By utilizing adiabatic reforming of reformate within the system the system operates at a significantly higher efficiency than other Solid Oxide Reforming Power Systems that exist in the prior art. This is because energy is not lost while materials are cooled and reheated, instead the device operates at a higher temperature. This allows efficiencies higher than 65%.

  14. Materials for Intermediate-Temperature Solid-Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Kilner, John A.; Burriel, Mónica

    2014-07-01

    Solid-oxide fuel cells are devices for the efficient conversion of chemical energy to electrical energy and heat. Research efforts are currently addressed toward the optimization of cells operating at temperatures in the region of 600°C, known as intermediate-temperature solid-oxide fuel cells, for which materials requirements are very stringent. In addition to the requirements of mechanical and chemical compatibility, the materials must show a high degree of oxide ion mobility and electrochemical activity at this low temperature. Here we mainly examine the criteria for the development of two key components of intermediate-temperature solid-oxide fuel cells: the electrolyte and the cathode. We limit the discussion to novel approaches to materials optimization and focus on the fluorite oxide for electrolytes, principally those based on ceria and zirconia, and on perovskites and perovskite-related families in the case of cathodes.

  15. Effects of Humidity on Solid Oxide Fuel Cell Cathodes

    SciTech Connect

    Hardy, John S.; Stevenson, Jeffry W.; Singh, Prabhakar; Mahapatra, Manoj K.; Wachsman, E. D.; Liu, Meilin; Gerdes, Kirk R.

    2015-03-17

    This report summarizes results from experimental studies performed by a team of researchers assembled on behalf of the Solid-state Energy Conversion Alliance (SECA) Core Technology Program. Team participants employed a variety of techniques to evaluate and mitigate the effects of humidity in solid oxide fuel cell (SOFC) cathode air streams on cathode chemistry, microstructure, and electrochemical performance.

  16. System for conversion between the boundary representation model and a constructive solid geometry model of an object

    DOEpatents

    Christensen, N.C.; Emery, J.D.; Smith, M.L.

    1985-04-29

    A system converts from the boundary representation of an object to the constructive solid geometry representation thereof. The system converts the boundary representation of the object into elemental atomic geometrical units or I-bodies which are in the shape of stock primitives or regularized intersections of stock primitives. These elemental atomic geometrical units are then represented in symbolic form. The symbolic representations of the elemental atomic geometrical units are then assembled heuristically to form a constructive solid geometry representation of the object usable for manufacturing thereof. Artificial intelligence is used to determine the best constructive solid geometry representation from the boundary representation of the object. Heuristic criteria are adapted to the manufacturing environment for which the device is to be utilized. The surface finish, tolerance, and other information associated with each surface of the boundary representation of the object are mapped onto the constructive solid geometry representation of the object to produce an enhanced solid geometry representation, particularly useful for computer-aided manufacture of the object. 19 figs.

  17. System for conversion between the boundary representation model and a constructive solid geometry model of an object

    DOEpatents

    Christensen, Noel C.; Emery, James D.; Smith, Maurice L.

    1988-04-05

    A system converts from the boundary representation of an object to the constructive solid geometry representation thereof. The system converts the boundary representation of the object into elemental atomic geometrical units or I-bodies which are in the shape of stock primitives or regularized intersections of stock primitives. These elemental atomic geometrical units are then represented in symbolic form. The symbolic representations of the elemental atomic geometrical units are then assembled heuristically to form a constructive solid geometry representation of the object usable for manufacturing thereof. Artificial intelligence is used to determine the best constructive solid geometry representation from the boundary representation of the object. Heuristic criteria are adapted to the manufacturing environment for which the device is to be utilized. The surface finish, tolerance, and other information associated with each surface of the boundary representation of the object are mapped onto the constructive solid geometry representation of the object to produce an enhanced solid geometry representation, particularly useful for computer-aided manufacture of the object.

  18. Three-dimensional elastic stress and displacement analysis of finite geometry solids containing cracks

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, J. P.; Mendelson, A.

    1974-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement distributions in various bodies containing cracks. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. When decoupling the equations and their boundary conditions is not possible, the use of a successive approximation procedure permits the analytical solution of the resulting ordinary differential equations. The results obtained show a considerable potential for using this method in the three-dimensional analysis of finite geometry solids and suggest a possible extension of this technique to nonlinear material behavior.

  19. Boundary to Constructive Solid Geometry Mappings: a Focus on 2-D Issues

    NASA Technical Reports Server (NTRS)

    Peterson, D. P.

    1985-01-01

    The problem of converting boundary representation (B-rep) to constructive solid geometry representation (CSG-rep) (and vice versa) is discussed in two phases. The first phase entails finding a CSG-rep that defines the region bounded by a polygonal profile curve. The second phase utilizes the results of the first phase to find a CSG-rep for many non-polygonal profile curves. A mathematically concise representation of a region bounded by a polygonal is presented. Namely, any polygonal region bounded by an n sided polygon may be represented by a binary tree which has at most n planar halfspaces as leaves. A structure for this representation and an algorithm for calculating is discussed.

  20. TOPICAL REVIEW The physics of solid-state neutron detector materials and geometries

    NASA Astrophysics Data System (ADS)

    Caruso, A. N.

    2010-10-01

    Detection of neutrons, at high total efficiency, with greater resolution in kinetic energy, time and/or real-space position, is fundamental to the advance of subfields within nuclear medicine, high-energy physics, non-proliferation of special nuclear materials, astrophysics, structural biology and chemistry, magnetism and nuclear energy. Clever indirect-conversion geometries, interaction/transport calculations and modern processing methods for silicon and gallium arsenide allow for the realization of moderate- to high-efficiency neutron detectors as a result of low defect concentrations, tuned reaction product ranges, enhanced effective omnidirectional cross sections and reduced electron-hole pair recombination from more physically abrupt and electronically engineered interfaces. Conversely, semiconductors with high neutron cross sections and unique transduction mechanisms capable of achieving very high total efficiency are gaining greater recognition despite the relative immaturity of their growth, lithographic processing and electronic structure understanding. This review focuses on advances and challenges in charged-particle-based device geometries, materials and associated mechanisms for direct and indirect transduction of thermal to fast neutrons within the context of application. Calorimetry- and radioluminescence-based intermediate processes in the solid state are not included.

  1. Electrochemically Deposited Ceria Structures for Advanced Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Brown, Evan C.

    As the pursuit towards emissions reduction intensifies with growing interest and nascent technologies, solid oxide fuel cells (SOFCs) remain an illustrious candidate for achieving our goals. Despite myriad advantages, SOFCs are still too costly for widespread deployment, even as unprecedented materials developments have recently emerged. This suggests that, in addition to informed materials selection, the necessary power output--and, thereby, cost-savings--gains must come from the fuel cell architecture. The work presented in this manuscript primarily investigates cathodic electrochemical deposition (CELD) as a scalable micro-/nanoscale fabrication tool for engineering ceria-based components in a SOFC assembly. Also, polymer sphere lithography was utilized to deposit fully connected, yet fully porous anti-dot metal films on yttira-stabilized zirconia (YSZ) with specific and knowable geometries, useful for mechanistic studies. Particular attention was given to anode structures, for which anti-dot metal films on YSZ served as composite substrates for subsequent CELD of doped ceria. By tuning the applied potential, a wide range of microstructures from high surface area coatings to planar, thin films was possible. In addition, definitive deposition was shown to occur on the electronically insulating YSZ surfaces, producing quality YSZ|ceria interfaces. These CELD ceria deposits exhibited promising electrochemical activity, as probed by A.C. Impedance Spectroscopy. In an effort to extend its usefulness as a SOFC fabrication tool, the CELD of ceria directly onto common SOFC cathode materials without a metallic phase was developed, as well as templated deposition schemes producing ceria nanowires and inverse opals.

  2. Flow and Geometry Control the Onset of Jamming in Fractures with High Solid-Fraction Fluids

    NASA Astrophysics Data System (ADS)

    Medina, R.; Elkhoury, J. E.; Shannon, L. J.; Detwiler, R. L.; Morris, J.; Prioul, R.; Desroches, J.

    2013-12-01

    Fluids containing a large fraction of suspended solids are common in the subsurface. Examples include fluids used for environmental remediation, hydraulic fracturing fluids and magma. These fluid-solid mixtures behave as non-Newtonian fluids where interactions between fluid, suspended solids, and pore walls can lead to jamming of the suspended solids. Jamming causes the velocity of the solid to decrease locally to zero causing a rapid decrease in permeability as the fluid is forced to flow through the pore space within the immobilized solid. Here we present results from experiments that quantify the flow of non-Newtonian suspensions in an analog parallel-plate fracture (transparent 15cm x 15cm with ~3-mm aperture) and explore the dependence of jamming on flow conditions, fracture geometry, and the action of gravity. We used guar gum mixed with water (0.75%) as the fluid and added 50% by volume of crushed silica (< 300μm). Flow rates ranged from 0.2ml/min to 6.0ml/min, cell orientation varied from horizontal to vertical (bottom to top) flow and a transducer provided continuous measurement of differential pressure across the cell. A strobed LED panel backlit the cell and a high-resolution CCD camera captured frequent (0.2 Hz) images during all experiments. Particle image velocimetry (PIV) yielded measurements of the evolving velocity field during experiments (see Figure). In the vertical orientation during the initial period of high flow rate, outflow decreased rapidly and the differential pressure increased indicating jamming within the cell. Subsequent efforts to flush solids from the cell suggested that jamming occurred at the inlet of the cell. This was likely due to settling of solids within the flow field indicating that the time scale associated with settling was shorter than the time scale of advection through the cell. In the horizontal orientation, localized jamming occurred at the lowest flow rate in a region near the outlet. This suggests that when

  3. Stack configurations for tubular solid oxide fuel cells

    SciTech Connect

    Armstrong, Timothy R.; Trammell, Michael P.; Marasco, Joseph A.

    2010-08-31

    A fuel cell unit includes an array of solid oxide fuel cell tubes having porous metallic exterior surfaces, interior fuel cell layers, and interior surfaces, each of the tubes having at least one open end; and, at least one header in operable communication with the array of solid oxide fuel cell tubes for directing a first reactive gas into contact with the porous metallic exterior surfaces and for directing a second reactive gas into contact with the interior surfaces, the header further including at least one busbar disposed in electrical contact with at least one surface selected from the group consisting of the porous metallic exterior surfaces and the interior surfaces.

  4. Application of Vacuum Deposition Methods to Solid Oxide Fuel Cells

    SciTech Connect

    Pederson, Larry R.; Singh, Prabhakar; Zhou, Xiao Dong

    2006-07-01

    The application of vacuum deposition techniques to the fabrication of solid oxide fuel cell materials and structures are reviewed, focusing on magnetron sputtering, vacuum plasma methods, laser ablation, and electrochemical vapor deposition. A description of each method and examples of use to produce electrolyte, electrode, and/or electrical interconnects are given. Generally high equipment costs and relatively low deposition rates have limited the use of vacuum deposition methods in solid oxide fuel cell manufacture, with a few notable exceptions. Vacuum methods are particularly promising in the fabrication of micro fuel cells, where thin films of high quality and unusual configuration are desired.

  5. Ionic conductors for solid oxide fuel cells

    SciTech Connect

    Krumpelt, M.; Bloom, I.D.; Pullockaran, J.D.; Myles, K.M.

    1991-12-31

    An electrolyte that operates at temperatures ranging from 600{degree}C to 800{degree}C is discussed. The electrolyte conducts charge ionically as well as electronically. The ionic conductors include molecular framework structures having planes or channels large enough to transport oxides or hydrated protons and having net-positive or net-negative charges. Representative molecular framework structures include substituted aluminum phosphates, orthosilicates, silicoaluminates, cordierites, apatites, sodalites, and hollandites.

  6. Ionic conductors for solid oxide fuel cells

    SciTech Connect

    Krumpelt, Michael; Bloom, Ira D.; Pullockaran, Jose D.; Myles, Kevin M.

    1993-01-01

    An electrolyte that operates at temperatures ranging from 600.degree. C. to 800.degree. C. is provided. The electrolyte conducts charge ionically as well as electronically. The ionic conductors include molecular framework structures having planes or channels large enough to transport oxides or hydrated protons and having net-positive or net-negative charges. Representative molecular framework structures include substituted aluminum phosphates, orthosilicates, silicoaluminates, cordierites, apatites, sodalites, and hollandites.

  7. Low temperature ozone oxidation of solid waste surrogates

    NASA Astrophysics Data System (ADS)

    Nabity, James A.; Lee, Jeffrey M.

    2015-09-01

    Solid waste management presents a significant challenge to human spaceflight and especially, long-term missions beyond Earth orbit. A six-month mission will generate over 300 kg of solid wastes per crewmember that must be dealt with to eliminate the need for storage and prevent it from becoming a biological hazard to the crew. There are several methods for the treatment of wastes that include oxidation via ozone, incineration, microbial oxidation or pyrolysis and physical methods such as microwave drying and compaction. In recent years, a low temperature oxidation process using ozonated water has been developed for the chemical conversion of organic wastes to CO2 and H2O. Experiments were conducted to evaluate the rate and effectiveness with which ozone oxidized several different waste materials. Increasing the surface area by chopping or shredding the solids into small pieces more than doubled the rate of oxidation. A greater flow of ozone and agitation of the ozonated water system also increased processing rates. Of the materials investigated, plastics have proven the most difficult to oxidize. The processing of plastics above the glass transition temperatures caused the plastics to clump together which reduced the exposed surface area, while processing at lower temperatures reduced surface reaction kinetics.

  8. Electronic properties of corrugated graphene: the Heisenberg principle and wormhole geometry in the solid state.

    PubMed

    Atanasov, Victor; Saxena, Avadh

    2011-05-01

    Adopting a purely two-dimensional relativistic equation for graphene's carriers contradicts the Heisenberg uncertainty principle since it requires setting the off-the-surface coordinate of a three-dimensional wavefunction to zero. Here we present a theoretical framework for describing graphene's massless relativistic carriers in accordance with this most fundamental of all quantum principles. A gradual confining procedure is used to restrict the dynamics onto a surface and normal to the surface parts, and in the process the embedding of this surface into the three-dimensional world is accounted for. As a result an invariant geometric potential arises in the surface part which scales linearly with the mean curvature and shifts the Fermi energy of the material proportional to bending. Strain induced modification of the electronic properties or 'straintronics' is clearly an important field of study in graphene. This opens an avenue to producing electronic devices: micro- and nano-electromechanical systems (MEMS and NEMS), where the electronic properties are controlled by geometric means and no additional alteration of graphene is necessary. The appearance of this geometric potential also provides us with clues as to how quantum dynamics looks in the curved space-time of general relativity. In this context we explore a two-dimensional cross-section of the wormhole geometry, realized with graphene as a solid state thought experiment. PMID:21474883

  9. Robust volume calculations for Constructive Solid Geometry (CSG) components in Monte Carlo transport calculations

    SciTech Connect

    Millman, D. L.; Griesheimer, D. P.; Nease, B. R.; Snoeyink, J.

    2012-07-01

    In this paper we consider a new generalized algorithm for the efficient calculation of component object volumes given their equivalent constructive solid geometry (CSG) definition. The new method relies on domain decomposition to recursively subdivide the original component into smaller pieces with volumes that can be computed analytically or stochastically, if needed. Unlike simpler brute-force approaches, the proposed decomposition scheme is guaranteed to be robust and accurate to within a user-defined tolerance. The new algorithm is also fully general and can handle any valid CSG component definition, without the need for additional input from the user. The new technique has been specifically optimized to calculate volumes of component definitions commonly found in models used for Monte Carlo particle transport simulations for criticality safety and reactor analysis applications. However, the algorithm can be easily extended to any application which uses CSG representations for component objects. The paper provides a complete description of the novel volume calculation algorithm, along with a discussion of the conjectured error bounds on volumes calculated within the method. In addition, numerical results comparing the new algorithm with a standard stochastic volume calculation algorithm are presented for a series of problems spanning a range of representative component sizes and complexities. (authors)

  10. Drying of solids with irregular geometry: numerical study and application using a three-dimensional model

    NASA Astrophysics Data System (ADS)

    Farias, Vera S. O.; da Silva, Wilton Pereira; e Silva, Cleide M. D. P. S.; Rocha, Vicente P. T.; Lima, Antonio G. B.

    2013-05-01

    This article proposes a numerical solution for the diffusion equation applied to solids with arbitrary geometry using non-orthogonal structured grids for the boundary condition of the first kind. A transient three-dimensional mathematical formulation written in boundary fitted coordinates and numerical formalism to discretize the diffusion equation by using the finite volume method, including numerical analysis of the computational solution are presented. To validate the proposed solution, the results obtained in this work were compared with well-known numerical solution available in literature and good agreement was observed. In order to verify the potential of the proposed numerical solution, it was applied to describe mass transfer inside ceramic roof tiles during drying. For that, it was used experimental data of the drying kinetics at the following temperatures: 55.6; 69.7; 82.7 and 98.6 °C. An optimization technique using experimental dataset has been presented to estimation of transport properties. The obtained statistical indicators enable to conclude that the numerical solution satisfactorily describes the drying processes.

  11. Solid oxide electrochemical cell fabrication process

    DOEpatents

    Dollard, Walter J.; Folser, George R.; Pal, Uday B.; Singhal, Subhash C.

    1992-01-01

    A method to form an electrochemical cell (12) is characterized by the steps of thermal spraying stabilized zirconia over a doped lanthanum manganite air electrode tube (14) to provide an electrolyte layer (15), coating conductive particles over the electrolyte, pressurizing the outside of the electrolyte layer, feeding halide vapors of yttrium and zirconium to the outside of the electrolyte layer and feeding a source of oxygen to the inside of the electrolyte layer, heating to cause oxygen reaction with the halide vapors to close electrolyte pores if there are any and to form a metal oxide coating on and between the particles and provide a fuel electrode (16).

  12. Solid state potentiometric gaseous oxide sensor

    NASA Technical Reports Server (NTRS)

    Wachsman, Eric D. (Inventor); Azad, Abdul Majeed (Inventor)

    2003-01-01

    A solid state electrochemical cell (10a) for measuring the concentration of a component of a gas mixture (12) includes first semiconductor electrode (14) and second semiconductor electrode (16) formed from first and second semiconductor materials, respectively. The materials are selected so as to undergo a change in resistivity upon contacting a gas component, such as CO or NO. An electrolyte (18) is provided in contact with the first and second semiconductor electrodes. A reference cell can be included in contact with the electrolyte. Preferably, a voltage response of the first semiconductor electrode is opposite in slope direction to that of the second semiconductor electrode to produce a voltage response equal to the sum of the absolute values of the control system uses measured pollutant concentrations to direct adjustment of engine combustion conditions.

  13. Modified cermet fuel electrodes for solid oxide electrochemical cells

    DOEpatents

    Ruka, Roswell J.; Spengler, Charles J.

    1991-01-01

    An exterior porous electrode (10), bonded to a solid oxygen ion conducting electrolyte (13) which is in contact with an interior electrode (14), contains coarse metal particles (12) of nickel and/or cobalt, having diameters from 3 micrometers to 35 micrometers, where the coarse particles are coated with a separate, porous, multiphase layer (17) containing fine metal particles of nickel and/or cobalt (18), having diameters from 0.05 micrometers to 1.75 micrometers and conductive oxide (19) selected from cerium oxide, doped cerium oxide, strontium titanate, doped strontium titanate and mixtures thereof.

  14. Method of fabricating a monolithic solid oxide fuel cell

    DOEpatents

    Minh, N.Q.; Horne, C.R.

    1994-03-01

    In a two-step densifying process of making a monolithic solid oxide fuel cell, a limited number of anode-electrolyte-cathode cells separated by an interconnect layer are formed and partially densified. Subsequently, the partially densified cells are stacked and further densified to form a monolithic array. 10 figures.

  15. Method of fabricating a monolithic solid oxide fuel cell

    DOEpatents

    Minh, Nguyen Q.; Horne, Craig R.

    1994-01-01

    In a two-step densifying process of making a monolithic solid oxide fuel cell, a limited number of anode-electrolyte-cathode cells separated by an interconnect layer are formed and partially densified. Subsequently, the partially densified cells are stacked and further densified to form a monolithic array.

  16. Nanofiber Scaffold for Cathode of Solid Oxide Fuel Cell

    SciTech Connect

    Zhi, Mingjia; Mariani, Nicholas; Gemmen, Randall; Gerdes, Kirk; Wu, Nianqiang

    2010-10-01

    A high performance solid oxide fuel cell cathode using the yttria-stabilized zirconia (YSZ) nanofibers scaffold with the infiltrated La1-xSrxMnO3 (LSM) shows an enhanced catalytic activity toward oxygen reduction. Such a cathode offers a continuous path for charge transport and an increased number of triple-phase boundary sites.

  17. A smooth dissipative particle dynamics method for domains with arbitrary-geometry solid boundaries

    NASA Astrophysics Data System (ADS)

    Gatsonis, Nikolaos A.; Potami, Raffaele; Yang, Jun

    2014-01-01

    A smooth dissipative particle dynamics method with dynamic virtual particle allocation (SDPD-DV) for modeling and simulation of mesoscopic fluids in wall-bounded domains is presented. The physical domain in SDPD-DV may contain external and internal solid boundaries of arbitrary geometries, periodic inlets and outlets, and the fluid region. The SDPD-DV method is realized with fluid particles, boundary particles, and dynamically allocated virtual particles. The internal or external solid boundaries of the domain can be of arbitrary geometry and are discretized with a surface grid. These boundaries are represented by boundary particles with assigned properties. The fluid domain is discretized with fluid particles of constant mass and variable volume. Conservative and dissipative force models due to virtual particles exerted on a fluid particle in the proximity of a solid boundary supplement the original SDPD formulation. The dynamic virtual particle allocation approach provides the density and the forces due to virtual particles. The integration of the SDPD equations is accomplished with a velocity-Verlet algorithm for the momentum and a Runge-Kutta for the entropy equation. The velocity integrator is supplemented by a bounce-forward algorithm in cases where the virtual particle force model is not able to prevent particle penetration. For the incompressible isothermal systems considered in this work, the pressure of a fluid particle is obtained by an artificial compressibility formulation for liquids and the ideal gas law for gases. The self-diffusion coefficient is obtained by an implementation of the generalized Einstein and the Green-Kubo relations. Field properties are obtained by sampling SDPD-DV outputs on a post-processing grid that allows harnessing the particle information on desired spatiotemporal scales. The SDPD-DV method is verified and validated with simulations in bounded and periodic domains that cover the hydrodynamic and mesoscopic regimes for

  18. A smooth dissipative particle dynamics method for domains with arbitrary-geometry solid boundaries

    NASA Astrophysics Data System (ADS)

    Gatsonis, Nikolaos A.; Potami, Raffaele; Yang, Jun

    2014-01-01

    A smooth dissipative particle dynamics method with dynamic virtual particle allocation (SDPD-DV) for modeling and simulation of mesoscopic fluids in wall-bounded domains is presented. The physical domain in SDPD-DV may contain external and internal solid boundaries of arbitrary geometries, periodic inlets and outlets, and the fluid region. The SDPD-DV method is realized with fluid particles, boundary particles, and dynamically allocated virtual particles. The internal or external solid boundaries of the domain can be of arbitrary geometry and are discretized with a surface grid. These boundaries are represented by boundary particles with assigned properties. The fluid domain is discretized with fluid particles of constant mass and variable volume. Conservative and dissipative force models due to virtual particles exerted on a fluid particle in the proximity of a solid boundary supplement the original SDPD formulation. The dynamic virtual particle allocation approach provides the density and the forces due to virtual particles. The integration of the SDPD equations is accomplished with a velocity-Verlet algorithm for the momentum and a Runge-Kutta for the entropy equation. The velocity integrator is supplemented by a bounce-forward algorithm in cases where the virtual particle force model is not able to prevent particle penetration. For the incompressible isothermal systems considered in this work, the pressure of a fluid particle is obtained by an artificial compressibility formulation for liquids and the ideal gas law for gases. The self-diffusion coefficient is obtained by an implementation of the generalized Einstein and the Green-Kubo relations. Field properties are obtained by sampling SDPD-DV outputs on a post-processing grid that allows harnessing the particle information on desired spatiotemporal scales. The SDPD-DV method is verified and validated with simulations in bounded and periodic domains that cover the hydrodynamic and mesoscopic regimes for

  19. Oxidation of Haynes 230 alloy in reduced temperature solid oxide fuel cell environments

    NASA Astrophysics Data System (ADS)

    Jian, Li; Jian, Pu; Jianzhong, Xiao; Xiaoliang, Qian

    Haynes 230 alloy was exposed to reducing and oxidizing environments at 750 °C for 1000 h, simulating the conditions in a reduced temperature solid oxide fuel cell (SOFC). The oxidized specimens were characterized in terms of the oxide morphology, composition and crystal structure. The oxide scale in each environment was identified as Cr 2O 3 with the existence of Cr 2MnO 4. Ni remained metallic in the reducing atmosphere, and NiO was detected in the sample exposed to air. The oxide scale is around 1 μm thick after 1000 h of oxidation in both situations. The area specific resistance (ASR) contributed by the oxide scale is expected less than 0.1 Ω cm 2 after 40,000 h of exposure when a parabolic oxide growth rate is assumed, demonstrating the suitability of the interconnect application of this alloy in the reduced temperature SOFCs.

  20. Jet Fuel Based High Pressure Solid Oxide Fuel Cell System

    NASA Technical Reports Server (NTRS)

    Gummalla, Mallika (Inventor); Yamanis, Jean (Inventor); Olsommer, Benoit (Inventor); Dardas, Zissis (Inventor); Bayt, Robert (Inventor); Srinivasan, Hari (Inventor); Dasgupta, Arindam (Inventor); Hardin, Larry (Inventor)

    2015-01-01

    A power system for an aircraft includes a solid oxide fuel cell system which generates electric power for the aircraft and an exhaust stream; and a heat exchanger for transferring heat from the exhaust stream of the solid oxide fuel cell to a heat requiring system or component of the aircraft. The heat can be transferred to fuel for the primary engine of the aircraft. Further, the same fuel can be used to power both the primary engine and the SOFC. A heat exchanger is positioned to cool reformate before feeding to the fuel cell. SOFC exhaust is treated and used as inerting gas. Finally, oxidant to the SOFC can be obtained from the aircraft cabin, or exterior, or both.

  1. Recent anode advances in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Sun, Chunwen; Stimming, Ulrich

    Solid oxide fuel cells (SOFCs) are electrochemical reactors that can directly convert the chemical energy of a fuel gas into electrical energy with high efficiency and in an environment-friendly way. The recent trends in the research of solid oxide fuel cells concern the use of available hydrocarbon fuels, such as natural gas. The most commonly used anode material Ni/YSZ cermet exhibits some disadvantages when hydrocarbons were used as fuels. Thus it is necessary to develop alternative anode materials which display mixed conductivity under fuel conditions. This article reviews the recent developments of anode in SOFCs with principal emphasis on the material aspects. In addition, the mechanism and kinetics of fuel oxidation reactions are also addressed. Various processes used for the cost-effective fabrication of anode have also been summarized. Finally, this review will be concluded with personal perspectives on the future research directions of this area.

  2. Jet fuel based high pressure solid oxide fuel cell system

    NASA Technical Reports Server (NTRS)

    Gummalla, Mallika (Inventor); Yamanis, Jean (Inventor); Olsommer, Benoit (Inventor); Dardas, Zissis (Inventor); Bayt, Robert (Inventor); Srinivasan, Hari (Inventor); Dasgupta, Arindam (Inventor); Hardin, Larry (Inventor)

    2013-01-01

    A power system for an aircraft includes a solid oxide fuel cell system which generates electric power for the aircraft and an exhaust stream; and a heat exchanger for transferring heat from the exhaust stream of the solid oxide fuel cell to a heat requiring system or component of the aircraft. The heat can be transferred to fuel for the primary engine of the aircraft. Further, the same fuel can be used to power both the primary engine and the SOFC. A heat exchanger is positioned to cool reformate before feeding to the fuel cell. SOFC exhaust is treated and used as inerting gas. Finally, oxidant to the SOFC can be obtained from the aircraft cabin, or exterior, or both.

  3. Richtmyer-Meshkov instability for elastic-plastic solids in converging geometries

    NASA Astrophysics Data System (ADS)

    López Ortega, A.; Lombardini, M.; Barton, P. T.; Pullin, D. I.; Meiron, D. I.

    2015-03-01

    for capturing the state of solid and fluid materials close to the origin is achieved by making use of adaptive mesh refinement techniques. Rigid-body rotations contained in the deformation tensor have been shown to have a negative effect on the accuracy of the method in extreme compression conditions and are removed by transforming the deformation tensor into a stretch tensor at each time step. With this methodology, the evolution of the interface can be tracked up to a point at which numerical convergence cannot be achieved due to the inception of numerical Kelvin-Helmholtz instabilities caused by slip between materials. From that point, only qualitative conclusions can be extracted from this analysis. The influence of different geometrical parameters, initial conditions, and material properties on the motion of the interface are investigated. Some major differences are found with respect to the better understood fluid-fluid case. For example, increasing the wave number of the interface perturbations leads to a second phase reversal of the interface (i.e., the first phase reversal of the interface naturally occurs due to the initial negative growth-rate of the instability as the shock wave transitions from the high-density material to the low-density one). This phenomenon is caused by the compressive effect of the converging geometry and the low density of the gas with respect to the solid, which allows for the formation of an incipient spike in the center of an already existing bubble. Multiple solid-gas density ratios are also considered. Results show that the motion of the interface asymptotically converges to the solid-vacuum case. When a higher initial density for the gas is considered, the growth rate of interface perturbations decreases and, in some situations, its sign may reverse, as the fluid becomes more dense than the solid due to having higher compressibility. Finally, the influence of the Mach number of the driving shock and the yield stress on the

  4. Functionally Graded Cathodes for Solid Oxide Fuel Cells

    SciTech Connect

    YongMan Choi; Meilin Liu

    2006-09-30

    This DOE SECA project focused on both experimental and theoretical understanding of oxygen reduction processes in a porous mixed-conducting cathode in a solid oxide fuel cell (SOFC). Elucidation of the detailed oxygen reduction mechanism, especially the rate-limiting step(s), is critical to the development of low-temperature SOFCs (400 C to 700 C) and to cost reduction since much less expensive materials may be used for cell components. However, cell performance at low temperatures is limited primarily by the interfacial polarization resistances, specifically by those associated with oxygen reduction at the cathode, including transport of oxygen gas through the porous cathode, the adsorption of oxygen onto the cathode surface, the reduction and dissociation of the oxygen molecule (O{sub 2}) into the oxygen ion (O{sup 2-}), and the incorporation of the oxygen ion into the electrolyte. In order to most effectively enhance the performance of the cathode at low temperatures, we must understand the mechanism and kinetics of the elementary processes at the interfaces. Under the support of this DOE SECA project, our accomplishments included: (1) Experimental determination of the rate-limiting step in the oxygen reduction mechanism at the cathode using in situ FTIR and Raman spectroscopy, including surface- and tip-enhanced Raman spectroscopy (SERS and TERS). (2) Fabrication and testing of micro-patterned cathodes to compare the relative activity of the TPB to the rest of the cathode surface. (3) Construction of a mathematical model to predict cathode performance based on different geometries and microstructures and analyze the kinetics of oxygen-reduction reactions occurring at charged mixed ionic-electronic conductors (MIECs) using two-dimensional finite volume models with ab initio calculations. (4) Fabrication of cathodes that are graded in composition and microstructure to generate large amounts of active surface area near the cathode/electrolyte interface using a

  5. Novel, benign, solid catalysts for the oxidation of hydrocarbons.

    PubMed

    Ratnasamy, Paul; Raja, Robert; Srinivas, Darbha

    2005-04-15

    The catalytic properties of two classes of solid catalysts for the oxidation of hydrocarbons in the liquid phase are discussed: (i) microporous solids, encapsulating transition metal complexes in their cavities and (ii) titanosilicate molecular sieves. Copper acetate dimers encapsulated in molecular sieves Y, MCM-22 and VPI-5 use dioxygen to regioselectively ortho-hydroxylate L-tyrosine to L-dopa, phenol to catechol and cresols to the corresponding o-dihydroxy and o-quinone compounds. Monomeric copper phthalocyanine and salen complexes entrapped in zeolite-Y oxidize methane to methanol, toluene to cresols, naphthalene to naphthols, xylene to xylenols and phenol to diphenols. Trimeric mu3-oxo-bridged Co/Mn cluster complexes, encapsulated inside Y-zeolite, oxidize para-xylene, almost quantitatively, to terephthalic acid. In almost all cases, the intrinsic catalytic activity (turnover frequency) of the metal complex is enhanced very significantly, upon encapsulation in the porous solids. Spectroscopic and electrochemical studies suggest that the geometric distortions of the complex on encapsulation change the electron density at the metal ion site and its redox behaviour, thereby influencing its catalytic activity and selectivity in oxidation reactions. Titanosilicate molecular sieves can oxidize hydrocarbons using dioxygen when loaded with transition metals like Pd, Au or Ag. The structure of surface Ti ions and the type of oxo-Ti species generated on contact with oxidants depend on several factors including the method of zeolite synthesis, zeolite structure, solvent, temperature and oxidant. Although, similar oxo-Ti species are present on all the titanosilicates, their relative concentrations vary among different structures and determine the product selectivity. PMID:15901549

  6. Specimen geometry effects on graphite/PMR-15 composites during thermo-oxidative aging

    NASA Technical Reports Server (NTRS)

    Bowles, K. J.; Meyers, A.

    1986-01-01

    Studies were conducted to establish the effects of specimen geometry on the thermo-oxidative stability and the mechanical properties retention of unidirectional Celion 12000 graphite fiber reinforced PMR-15 polyimide composites. Weight loss, flexural strength and interlaminar shear strength are measured at isothermal aging times as long as 1639 hr at a temperature of 316 C for three different specimen geometries. It is found that the three different types of specimen surfaces exhibit different values of weight loss/unit area. The mechanical properties retention is also found to be dependent on geometry for these composites. The interlaminar shear strength decreases significantly over the complete range of aging times. The flexural strength retention starts showing geometric dependency after about 1000 hr of aging at 316C. Weight loss fluxes, associated with the three different types of exposed surfaces, are calculated and used to develop an empirical mathematical model for predicting the weight loss behavior of unidirectional composites of arbitrary geometries. Data are presented comparing experimentally determined weight loss with weight loss values predicted using the empirical model.

  7. Realistic prediction of solid pharmaceutical oxidation products by using a novel forced oxidation system.

    PubMed

    Ueyama, Eiji; Tamura, Kousuke; Mizukawa, Kousei; Kano, Kenji

    2014-04-01

    This study investigated a novel solid-state-based forced oxidation system to enable a realistic prediction of pharmaceutical product oxidation, a key consideration in drug development and manufacture. Polysorbate 80 and ferric(III) acetylacetonate were used as an organic hydroperoxide source and a transition metal catalyst, respectively. Homogeneous solutions of target compounds and these reagents were prepared in a mixed organic solvent. The organic solvent was removed rapidly under reduced pressure, and the oxidation of the resulting dried solid was investigated. Analysis of the oxidation products generated in test compounds by this proposed forced oxidation system using HPLC showed a high similarity with those generated during more prolonged naturalistic drug oxidation. The proposed system provided a better predictive performance in prediction of realistic oxidative degradants of the drugs tested than did other established methods. Another advantage of this system was that the generation of undesired products of hydrolysis, solvolysis, and thermolysis was prevented because efficient oxidation was achieved under mild conditions. The results of this study suggest that this system is suitable for a realistic prediction of oxidative degradation of solid pharmaceuticals. PMID:24497072

  8. SOLID STATE ENERGY CONVERSION ALLIANCE (SECA) SOLID OXIDE FUEL CELL PROGRAM

    SciTech Connect

    Unknown

    2003-06-01

    This report summarizes the progress made during the September 2001-March 2002 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program''. The program focuses on the development of a low-cost, high-performance 3-to-10-kW solid oxide fuel cell (SOFC) system suitable for a broad spectrum of power-generation applications. The overall objective of the program is to demonstrate a modular SOFC system that can be configured to create highly efficient, cost-competitive, and environmentally benign power plants tailored to specific markets. When fully developed, the system will meet the efficiency, performance, life, and cost goals for future commercial power plants.

  9. SOLID STATE ENERGY CONVERSION ALLIANCE (SECA) SOLID OXIDE FUEL CELL PROGRAM

    SciTech Connect

    Nguyen Minh; Jim Powers

    2003-10-01

    This report summarizes the work performed for April 2003--September 2003 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U.S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid oxide Fuel Cell Program''. During this reporting period, the conceptual system design activity was completed. The system design, including strategies for startup, normal operation and shutdown, was defined. Sealant and stack materials for the solid oxide fuel cell (SOFC) stack were identified which are capable of meeting the thermal cycling and degradation requirements. A cell module was tested which achieved a stable performance of 0.238 W/cm{sup 2} at 95% fuel utilization. The external fuel processor design was completed and fabrication begun. Several other advances were made on various aspects of the SOFC system, which are detailed in this report.

  10. The effect of chromium oxyhydroxide on solid oxide fuel cells.

    SciTech Connect

    Krumpelt, M.; Cruse, T. A.; Ingram, B. J.; Routbort, J. L.; Wang, S.; Salvador, P. A.; Chen, G.; Carnegie Mellon Univ.; NETL; Ohio Univ.

    2010-01-01

    Hexavalent chromium species like the oxyhydroxide, CrO{sub 2}(OH){sub 2}, or hexoxide, CrO{sub 3}, are electrochemically reduced to Cr{sub 2}O{sub 3} in solid oxide fuel cells and adversely affect the cell operating potentials. Using a narrowly focused beam from the Advanced Photon Source, such chromium oxide deposits were unequivocally identified in the active region of the cathode by X-ray diffraction, suggesting that the triple phase boundaries were partially blocked. Under fuel cell operating conditions, the reaction has an equilibrium potential of about 0.9 V and the rate of chromium oxide deposition is therefore dependent on the operating potential of the cell. It becomes diffusion limited after several hours of steady operation. At low operating potentials, lanthanum manganite cathodes begin to be reduced to MnO, which reacts with the chromium oxide to form the MnCr{sub 2}O{sub 4} spinel.

  11. Are scaling laws on strength of solids related to mechanics or to geometry?

    PubMed

    Carpinteri, Alberto; Pugno, Nicola

    2005-06-01

    One of the largest controversial issues of the materials science community is the interpretation of scaling laws on material strength. In spite of the prevailing view, which considers mechanics as the real cause of such effects, here, we propose a different argument, purely based on geometry. Thus, as happened for relativity, geometry could again hold an unexpected and fundamental role. PMID:15928689

  12. Review on anode material development in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Siong @ Mahmud, Lily; Muchtar, Andanastuti; Somalu, Mahendra Rao

    2015-05-01

    New developments in technology require highly efficient, affordable, and green electrical energy. The materials to be used must also be reusable and environment friendly. These characteristics are among the major factors that may lead to the production of new and highly efficient power generation systems. Solid oxide fuel cells (SOFCs) have become major devices in producing electricity that emphasize the advance usage of material science and technological development. As part of the key elements of SOFCs, anodes have the primary function of stimulating the electrochemical oxidation of fuel. In this review, the progress in developing anode materials for SOFCs is briefly discussed.

  13. Sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

    DOEpatents

    Isenberg, Arnold O.

    1987-01-01

    An electrochemical apparatus is made containing an exterior electrode bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

  14. Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation

    SciTech Connect

    Nguyen Minh

    2004-07-04

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the January to June 2004 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. Also, another activity included in this program focuses on the development of SOFC scale up strategies.

  15. Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation

    SciTech Connect

    Nguyen Minh

    2002-03-31

    This report summarizes the work performed by Honeywell during the January 2002 to March 2002 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a turbogenerator. For this reporting period the following activities have been carried out: {lg_bullet} Conceptual system design trade studies were performed {lg_bullet} System-level performance model was created {lg_bullet} Dynamic control models are being developed {lg_bullet} Mechanical properties of candidate heat exchanger materials were investigated {lg_bullet} SOFC performance mapping as a function of flow rate and pressure was completed

  16. Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation

    SciTech Connect

    Faress Rahman; Nguyen Minh

    2004-01-04

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the July 2003 to December 2003 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. Also, another activity included in this program focuses on the development of SOFC scale up strategies.

  17. Tubular screen electrical connection support for solid oxide fuel cells

    DOEpatents

    Tomlins, Gregory W.; Jaszcar, Michael P.

    2002-01-01

    A solid oxide fuel assembly is made of fuel cells (16, 16', 18, 24, 24', 26), each having an outer interconnection layer (36) and an outer electrode (28), which are disposed next to each other with rolled, porous, hollow, electrically conducting metal mesh conductors (20, 20') between the fuel cells, connecting the fuel cells at least in series along columns (15, 15') and where there are no metal felt connections between any fuel cells.

  18. Rigorous Definition of Oxidation States of Ions in Solids

    NASA Astrophysics Data System (ADS)

    Jiang, Lai; Levchenko, Sergey V.; Rappe, Andrew M.

    2012-04-01

    We present justification and a rigorous procedure for electron partitioning among atoms in extended systems. The method is based on wave-function topology and the modern theory of polarization, rather than charge density partitioning or wave-function projection, and, as such, reformulates the concept of oxidation state without assuming real-space charge transfer between atoms. This formulation provides rigorous electrostatics of finite-extent solids, including films and nanowires.

  19. Finite element analysis of monolithic solid oxide fuel cells

    SciTech Connect

    Saigal, A. . Dept. of Mechanical Engineering); Majumdar, S. )

    1992-01-01

    This paper investigates the stress and fracture behavior of a monolithic solid oxide fuel cell (MSOFC) currently under joint development by Allied Signal Corporation and Argonne National Laboratory. The MSOFC is an all-ceramic fuel cell capable of high power density and tolerant of a variety of hydrocarbon fuels, making it potentially attractive for stationary utility and mobile transportation systems. The monolithic design eliminates inactive structural supports, increases active surface area, and lowers voltage losses caused by internal resistance.

  20. Finite element analysis of monolithic solid oxide fuel cells

    SciTech Connect

    Saigal, A.; Majumdar, S.

    1992-04-01

    This paper investigates the stress and fracture behavior of a monolithic solid oxide fuel cell (MSOFC) currently under joint development by Allied Signal Corporation and Argonne National Laboratory. The MSOFC is an all-ceramic fuel cell capable of high power density and tolerant of a variety of hydrocarbon fuels, making it potentially attractive for stationary utility and mobile transportation systems. The monolithic design eliminates inactive structural supports, increases active surface area, and lowers voltage losses caused by internal resistance.

  1. Open end protection for solid oxide fuel cells

    DOEpatents

    Zafred, Paolo R.; Dederer, Jeffrey T.; Tomlins, Gregory W.; Toms, James M.; Folser, George R.; Schmidt, Douglas S.; Singh, Prabhakar; Hager, Charles A.

    2001-01-01

    A solid oxide fuel cell (40) having a closed end (44) and an open end (42) operates in a fuel cell generator (10) where the fuel cell open end (42) of each fuel cell contains a sleeve (60, 64) fitted over the open end (42), where the sleeve (60, 64) extends beyond the open end (42) of the fuel cell (40) to prevent degradation of the interior air electrode of the fuel cell by fuel gas during operation of the generator (10).

  2. Method to fabricate high performance tubular solid oxide fuel cells

    SciTech Connect

    Chen, Fanglin; Yang, Chenghao; Jin, Chao

    2013-06-18

    In accordance with the present disclosure, a method for fabricating a solid oxide fuel cell is described. The method includes forming an asymmetric porous ceramic tube by using a phase inversion process. The method further includes forming an asymmetric porous ceramic layer on a surface of the asymmetric porous ceramic tube by using a phase inversion process. The tube is co-sintered to form a structure having a first porous layer, a second porous layer, and a dense layer positioned therebetween.

  3. Current status of Westinghouse tubular solid oxide fuel cell program

    SciTech Connect

    Parker, W.G.

    1996-04-01

    In the last ten years the solid oxide fuel cell (SOFC) development program at Westinghouse has evolved from a focus on basic material science to the engineering of fully integrated electric power systems. Our endurance for this cell is 5 to 10 years. To date we have successfully operated at power for over six years. For power plants it is our goal to have operated before the end of this decade a MW class power plant. Progress toward these goals is described.

  4. Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation

    SciTech Connect

    David Deangelis; Rich Depuy; Debashis Dey; Georgia Karvountzi; Nguyen Minh; Max Peter; Faress Rahman; Pavel Sokolov; Deliang Yang

    2004-09-30

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the April to October 2004 reporting period in Task 2.3 (SOFC Scaleup for Hybrid and Fuel Cell Systems) under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL), entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. This study analyzes the performance and economics of power generation systems for central power generation application based on Solid Oxide Fuel Cell (SOFC) technology and fueled by natural gas. The main objective of this task is to develop credible scale up strategies for large solid oxide fuel cell-gas turbine systems. System concepts that integrate a SOFC with a gas turbine were developed and analyzed for plant sizes in excess of 20 MW. A 25 MW plant configuration was selected with projected system efficiency of over 65% and a factory cost of under $400/kW. The plant design is modular and can be scaled to both higher and lower plant power ratings. Technology gaps and required engineering development efforts were identified and evaluated.

  5. Lowering the temperature of solid oxide fuel cells.

    PubMed

    Wachsman, Eric D; Lee, Kang Taek

    2011-11-18

    Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy. PMID:22096189

  6. Energetics of Rare Earth Doped Uranium Oxide Solid Solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Lei

    The physical and chemical properties of UO2 nuclear fuels are affected as fission products accumulate during irradiation. The lanthanides, a main group of fission products, form extensive solid solutions with uranium oxide in the fluorite structure. Thermodynamic studies of such solid solutions had been performed to obtain partial molar free energies of oxygen as a function of dopant concentration and temperature; however, direct measurement of formation enthalpies was hampered by the refractory nature of these oxides. In this work, high temperature oxide melt solution calorimetry was utilized to study the thermochemistry of various rare earth doped uranium oxide LnxU 1-xO2-0.5x+y (Ln = La, Y, Nd) over a wide range of dopant concentrations and oxygen contents. The sintered solid solutions were carefully characterized to determine their phase purity, chemical composition, and uranium oxidation state, with most of the materials in the oxygen excess regime. The enthalpies of formation of LnxU1-xO2-0.5x+y were calculated from the calorimetric data. The oxidation enthalpies of these solid solutions are similar to that of UO2. The formation enthalpies from constituent oxides (LnO1.5, UO2, and UO3) become increasingly negative with addition of dopant cations and appear relatively independent of the uranium oxidation state (oxygen content) when the type and concentration of the dopants are the same. This is valid in the oxygen excess regime; thus an estimation of formation enthalpies of LnxU1-xO2 materials can be made. The formation enthalpies from elements of hyperstoichiometric LnxU1-xO 2-0.5x+y materials obtained from calorimetric measurements are in good agreement with those calculated from free energy data. A direct comparison between the formation enthalpies from calorimetric study and computational research using density functional theory was also performed. The experimental and computational energies of LnxU 1-xO2 (Ln = La, Y, Nd) generally agree within 10 k

  7. Stationary market applications potential of solid oxide and solid polymer fuel cell systems

    SciTech Connect

    Baker, J.N.; Fletcher, W.H.

    1996-12-31

    The UK DTI`s Advanced Fuel Cells Programme currently focuses on two main fuel cell technologies, namely the solid oxide and solid polymer systems (SOFC and SPFC), respectively. The provision of accurate and timely market data is regarded as an important part of the overall programme objectives, such as to assist both Government and industry in their appraisals of the technologies. The present study was therefore commissioned against this background, with a complementary study addressing transportation and mobile applications. The results reported herein relate to the stationary market applications potential of both SOFC and SPFC systems.

  8. Ultra-thin solid oxide fuel cells: Materials and devices

    NASA Astrophysics Data System (ADS)

    Kerman, Kian

    Solid oxide fuel cells are electrochemical energy conversion devices utilizing solid electrolytes transporting O2- that typically operate in the 800 -- 1000 °C temperature range due to the large activation barrier for ionic transport. Reducing electrolyte thickness or increasing ionic conductivity can enable lower temperature operation for both stationary and portable applications. This thesis is focused on the fabrication of free standing ultrathin (<100 nm) oxide membranes of prototypical O 2- conducting electrolytes, namely Y2O3-doped ZrO2 and Gd2O3-doped CeO2. Fabrication of such membranes requires an understanding of thin plate mechanics coupled with controllable thin film deposition processes. Integration of free standing membranes into proof-of-concept fuel cell devices necessitates ideal electrode assemblies as well as creative processing schemes to experimentally test devices in a high temperature dual environment chamber. We present a simple elastic model to determine stable buckling configurations for free standing oxide membranes. This guides the experimental methodology for Y 2O3-doped ZrO2 film processing, which enables tunable internal stress in the films. Using these criteria, we fabricate robust Y2O3-doped ZrO2 membranes on Si and composite polymeric substrates by semiconductor and micro-machining processes, respectively. Fuel cell devices integrating these membranes with metallic electrodes are demonstrated to operate in the 300 -- 500 °C range, exhibiting record performance at such temperatures. A model combining physical transport of electronic carriers in an insulating film and electrochemical aspects of transport is developed to determine the limits of performance enhancement expected via electrolyte thickness reduction. Free standing oxide heterostructures, i.e. electrolyte membrane and oxide electrodes, are demonstrated. Lastly, using Y2O3-doped ZrO2 and Gd2O 3-doped CeO2, novel electrolyte fabrication schemes are explored to develop oxide

  9. Ultrasonic approach for formation of erbium oxide nanoparticles with variable geometries.

    PubMed

    Radziuk, Darya; Skirtach, André; Gessner, Andre; Kumke, Michael U; Zhang, Wei; Möhwald, Helmuth; Shchukin, Dmitry

    2011-12-01

    Ultrasound (20 kHz, 29 W·cm(-2)) is employed to form three types of erbium oxide nanoparticles in the presence of multiwalled carbon nanotubes as a template material in water. The nanoparticles are (i) erbium carboxioxide nanoparticles deposited on the external walls of multiwalled carbon nanotubes and Er(2)O(3) in the bulk with (ii) hexagonal and (iii) spherical geometries. Each type of ultrasonically formed nanoparticle reveals Er(3+) photoluminescence from crystal lattice. The main advantage of the erbium carboxioxide nanoparticles on the carbon nanotubes is the electromagnetic emission in the visible region, which is new and not examined up to the present date. On the other hand, the photoluminescence of hexagonal erbium oxide nanoparticles is long-lived (μs) and enables the higher energy transition ((4)S(3/2)-(4)I(15/2)), which is not observed for spherical nanoparticles. Our work is unique because it combines for the first time spectroscopy of Er(3+) electronic transitions in the host crystal lattices of nanoparticles with the geometry established by ultrasound in aqueous solution of carbon nanotubes employed as a template material. The work can be of great interest for "green" chemistry synthesis of photoluminescent nanoparticles in water. PMID:22022886

  10. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Riley, Brian; Szreders, Bernard E.

    1988-04-01

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approx. 1100 to 1300 C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20 and 50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  11. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Riley, B.; Szreders, B.E.

    1988-04-26

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (/approximately/1100/degree/ /minus/ 1300/degree/C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20--50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  12. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Brian, Riley; Szreders, Bernard E.

    1989-01-01

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approximately 1100.degree.-1300.degree. C.) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20-50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  13. Solid oxide fuel cell having a glass composite seal

    DOEpatents

    De Rose, Anthony J.; Mukerjee, Subhasish; Haltiner, Jr., Karl Jacob

    2013-04-16

    A solid oxide fuel cell stack having a plurality of cassettes and a glass composite seal disposed between the sealing surfaces of adjacent cassettes, thereby joining the cassettes and providing a hermetic seal therebetween. The glass composite seal includes an alkaline earth aluminosilicate (AEAS) glass disposed about a viscous glass such that the AEAS glass retains the viscous glass in a predetermined position between the first and second sealing surfaces. The AEAS glass provides geometric stability to the glass composite seal to maintain the proper distance between the adjacent cassettes while the viscous glass provides for a compliant and self-healing seal. The glass composite seal may include fibers, powders, and/or beads of zirconium oxide, aluminum oxide, yttria-stabilized zirconia (YSZ), or mixtures thereof, to enhance the desirable properties of the glass composite seal.

  14. Serially connected solid oxide fuel cells having monolithic cores

    DOEpatents

    Herceg, Joseph E.

    1987-01-01

    A solid oxide fuel cell for electrochemically combining fuel and oxidant for generating galvanic output, wherein the cell core has an array of cell segments electrically serially connected in the flow direction, each segment consisting of electrolyte walls and interconnect that are substantially devoid of any composite inert materials for support. Instead, the core is monolithic, where each electrolyte wall consists of thin layers of cathode and anode materials sandwiching a thin layer of electrolyte material therebetween. Means direct the fuel to the anode-exposed core passageways and means direct the oxidant to the cathode-exposed core passageways; and means also direct the galvanic output to an exterior circuit. Each layer of the electrolyte composite materials is of the order of 0.002-0.01 cm thick; and each layer of the cathode and anode materials is of the order of 0.002-0.05 cm thick. Between 2 and 50 cell segments may be connected in series.

  15. Nondestructive characterization methods for monolithic solid oxide fuel cells

    SciTech Connect

    Ellingson, W.A.

    1993-01-01

    Monolithic solid oxide fuel cells (MSOFCS) represent a potential breakthrough in fuel cell technology, provided that reliable fabrication methods can be developed. Fabrication difficulties arise in several steps of the processing: First is the fabrication of uniform thin (305 {mu}m) single-layer and trilayer green tapes (the trilayer tapes of anode/electrolyte/cathode and anode/interconnect/cathode must have similar coefficients of thermal expansion to sinter uniformly and to have the necessary electrochemical properties); Second is the development of fuel and oxidant channels in which residual stresses are likely to develop in the tapes; Third is the fabrication of a ``complete`` cell for which the bond quality between layers and the quality of the trilayers must be established; and Last, attachment of fuel and oxidant manifolds and verification of seal integrity. Purpose of this report is to assess nondestructive characterization methods that could be developed for application to laboratory, prototype, and full-scale MSOFCs.

  16. DEGRADATION ISSUES IN SOLID OXIDE CELLS DURING HIGH TEMPERATURE ELECTROLYSIS

    SciTech Connect

    M. S. Sohal; J. E. O'Brien; C. M. Stoots; V. I. Sharma; B. Yildiz; A. Virkar

    2012-02-01

    Idaho National Laboratory (INL) is performing high-temperature electrolysis research to generate hydrogen using solid oxide electrolysis cells (SOECs). The project goals are to address the technical and degradation issues associated with the SOECs. This paper provides a summary of various ongoing INL and INL sponsored activities aimed at addressing SOEC degradation. These activities include stack testing, post-test examination, degradation modeling, and a list of issues that need to be addressed in future. Major degradation issues relating to solid oxide fuel cells (SOFC) are relatively better understood than those for SOECs. Some of the degradation mechanisms in SOFCs include contact problems between adjacent cell components, microstructural deterioration (coarsening) of the porous electrodes, and blocking of the reaction sites within the electrodes. Contact problems include delamination of an electrode from the electrolyte, growth of a poorly (electronically) conducting oxide layer between the metallic interconnect plates and the electrodes, and lack of contact between the interconnect and the electrode. INL's test results on high temperature electrolysis (HTE) using solid oxide cells do not provide a clear evidence whether different events lead to similar or drastically different electrochemical degradation mechanisms. Post-test examination of the solid oxide electrolysis cells showed that the hydrogen electrode and interconnect get partially oxidized and become non-conductive. This is most likely caused by the hydrogen stream composition and flow rate during cool down. The oxygen electrode side of the stacks seemed to be responsible for the observed degradation due to large areas of electrode delamination. Based on the oxygen electrode appearance, the degradation of these stacks was largely controlled by the oxygen electrode delamination rate. University of Utah (Virkar) has developed a SOEC model based on concepts in local thermodynamic equilibrium in systems

  17. DEGRADATION ISSUES IN SOLID OXIDE CELLS DURING HIGH TEMPERATURE ELECTROLYSIS

    SciTech Connect

    J. E. O'Brien; C. M. Stoots; V. I. Sharma; B. Yildiz; A. V. Virkar

    2010-06-01

    Idaho National Laboratory (INL) is performing high-temperature electrolysis research to generate hydrogen using solid oxide electrolysis cells (SOECs). The project goals are to address the technical and degradation issues associated with the SOECs. This paper provides a summary of various ongoing INL and INL sponsored activities aimed at addressing SOEC degradation. These activities include stack testing, post-test examination, degradation modeling, and a list of issues that need to be addressed in future. Major degradation issues relating to solid oxide fuel cells (SOFC) are relatively better understood than those for SOECs. Some of the degradation mechanisms in SOFCs include contact problems between adjacent cell components, microstructural deterioration (coarsening) of the porous electrodes, and blocking of the reaction sites within the electrodes. Contact problems include delamination of an electrode from the electrolyte, growth of a poorly (electronically) conducting oxide layer between the metallic interconnect plates and the electrodes, and lack of contact between the interconnect and the electrode. INL’s test results on high temperature electrolysis (HTE) using solid oxide cells do not provide a clear evidence whether different events lead to similar or drastically different electrochemical degradation mechanisms. Post-test examination of the solid oxide electrolysis cells showed that the hydrogen electrode and interconnect get partially oxidized and become non-conductive. This is most likely caused by the hydrogen stream composition and flow rate during cool down. The oxygen electrode side of the stacks seemed to be responsible for the observed degradation due to large areas of electrode delamination. Based on the oxygen electrode appearance, the degradation of these stacks was largely controlled by the oxygen electrode delamination rate. University of Utah (Virkar) has developed a SOEC model based on concepts in local thermodynamic equilibrium in

  18. Why solid oxide cells can be reversibly operated in solid oxide electrolysis cell and fuel cell modes?

    PubMed

    Chen, Kongfa; Liu, Shu-Sheng; Ai, Na; Koyama, Michihisa; Jiang, San Ping

    2015-12-14

    High temperature solid oxide cells (SOCs) are attractive for storage and regeneration of renewable energy by operating reversibly in solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) modes. However, the stability of SOCs, particularly the deterioration of the performance of oxygen electrodes in the SOEC operation mode, is the most critical issue in the development of high performance and durable SOCs. In this study, we investigate in detail the electrochemical activity and stability of La0.8Sr0.2MnO3 (LSM) oxygen electrodes in cyclic SOEC and SOFC modes. The results show that the deterioration of LSM oxygen electrodes caused by anodic polarization can be partially or completely recovered by subsequent cathodic polarization. Using in situ assembled LSM electrodes without pre-sintering, we demonstrate that the deteriorated LSM/YSZ interface can be repaired and regenerated by operating the cells under cathodic polarization conditions. This study for the first time establishes the foundation for the development of truly reversible and stable SOCs for hydrogen fuel production and electricity generation in cyclic SOEC and SOFC operation modes. PMID:26548929

  19. Advanced materials for solid oxide fuel cells: Hafnium-Praseodymium-Indium Oxide System

    SciTech Connect

    Bates, J.L.; Griffin, C.W.; Weber, W.J.

    1988-06-01

    The HfO/sub 2/-PrO/sub 1.83/-In/sub 2/O/sub 3/ system has been studied at the Pacific Northwest Laboratory to develop alternative, highly electrically conducting oxides as electrode and interconnection materials for solid oxide fuel cells. A coprecipitation process was developed for synthesizing single-phase, mixed oxide powders necessary to fabricate powders and dense oxides. A ternary phase diagram was developed, and the phases and structures were related to electrical transport properties. Two new phases, an orthorhombic PrInO/sub 3/ and a rhombohedral Hf/sub 2/In/sub 2/O/sub 7/ phase, were identified. The highest electronic conductivity is related to the presence of a bcc, In/sub 2/O/sub 3/ solid solution (ss) containing HfO/sub 2/ and PrO/sub 1.83/. Compositions containing more than 35 mol % of the In/sub 2/O/sub 3/ ss have electrical conductivities greater than 10/sup /minus/1/ (ohm-cm)/sup /minus/1/, and the two or three phase structures that contain this phase appear to exhibit mixed electronic-ionic conduction. The high electrical conductivities and structures similar to the Y/sub 2/O/sub 3/-stabilized ZrO/sub 2/(HfO/sub 2/) electrolyte give these oxides potential for use as cathodes in solid oxide fuel cells. 21 refs.

  20. Dynamics of the Rydberg state population of slow highly charged ions impinging a solid surface at arbitrary collision geometry

    NASA Astrophysics Data System (ADS)

    Nedeljković, N. N.; Majkić, M. D.; Božanić, D. K.; Dojčilović, R. J.

    2016-06-01

    We consider the population dynamics of the intermediate Rydberg states of highly charged ions (core charge Z\\gg 1, principal quantum number {n}{{A}}\\gg 1) interacting with solid surfaces at arbitrary collision geometry. The recently developed resonant two-state vector model for the grazing incidence (2012 J. Phys. B: At. Mol. Opt. Phys. 45 215202) is extended to the quasi-resonant case and arbitrary angle of incidence. According to the model, the population probabilities depend both on the projectile parallel and perpendicular velocity components, in a complementary way. A cascade neutralization process for {{{Xe}}}Z+ ions, for Z=15{--}45, interacting with a conductive-surface is considered by taking into account the population dynamics. For an arbitrary collision geometry and given range of ionic velocities, a micro-staircase model for the simultaneous calculation of the kinetic energy gain and the charge state of the ion in front of the surface is proposed. The relevance of the obtained results for the explanation of the formation of nanostructures on solid surfaces by slow highly charged ions for normal incidence geometry is briefly discussed.

  1. The Effects of Geometry and Stability of Solid-state Nanopores on Detecting Single DNA molecules

    PubMed Central

    Rollings, Ryan; Graef, Edward; Walsh, Nathan; Nandivada, Santoshi; Benamara, Mourad

    2014-01-01

    In this work we use a combination of 3D-TEM tomography, energy filtered TEM, single molecule DNA translocation experiments, and numerical modeling to show a more precise relationship between nanopore shape and ionic conductance and show that changes in geometry while in solution can account for most deviations between predicted and measured conductance. We compare the structural stability of Ion Beam Sculpted (IBS), IBS-annealed, and TEM drilled nanopores. We demonstrate that annealing can significantly improve the stability of IBS made pores. Furthermore, the methods developed in this work can be used to predict pore conductance and current drop amplitudes of DNA translocation events for a wide variety of pore geometries. We discuss that chemical dissolution is one mechanism of the geometry change for SiNx nanopores and show that small modification in fabrication procedure can significantly increase the stability of IBS nanopores. PMID:25556317

  2. Scalable nanostructured membranes for solid-oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Masaru; Lai, Bo-Kuai; Ramanathan, Shriram

    2011-05-01

    The use of oxide fuel cells and other solid-state ionic devices in energy applications is limited by their requirement for elevated operating temperatures, typically above 800 °C (ref. 1). Thin-film membranes allow low-temperature operation by reducing the ohmic resistance of the electrolytes. However, although proof-of-concept thin-film devices have been demonstrated, scaling up remains a significant challenge because large-area membranes less than ~100 nm thick are susceptible to mechanical failure. Here, we report that nanoscale yttria-stabilized zirconia membranes with lateral dimensions on the scale of millimetres or centimetres can be made thermomechanically stable by depositing metallic grids on them to function as mechanical supports. We combine such a membrane with a nanostructured dense oxide cathode to make a thin-film solid-oxide fuel cell that can achieve a power density of 155 mW cm-2 at 510 °C. We also report a total power output of more than 20 mW from a single fuel-cell chip. Our large-area membranes could also be relevant to electrochemical energy applications such as gas separation, hydrogen production and permeation membranes.

  3. Electrode Design for Low Temperature Direct-Hydrocarbon Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Chen, Fanglin (Inventor); Zhao, Fei (Inventor); Liu, Qiang (Inventor)

    2015-01-01

    In certain embodiments of the present disclosure, a solid oxide fuel cell is described. The solid oxide fuel cell includes a hierarchically porous cathode support having an impregnated cobaltite cathode deposited thereon, an electrolyte, and an anode support. The anode support includes hydrocarbon oxidation catalyst deposited thereon, wherein the cathode support, electrolyte, and anode support are joined together and wherein the solid oxide fuel cell operates a temperature of 600.degree. C. or less.

  4. Electrode design for low temperature direct-hydrocarbon solid oxide fuel cells

    SciTech Connect

    Chen, Fanglin; Zhao, Fei; Liu, Qiang

    2015-10-06

    In certain embodiments of the present disclosure, a solid oxide fuel cell is described. The solid oxide fuel cell includes a hierarchically porous cathode support having an impregnated cobaltite cathode deposited thereon, an electrolyte, and an anode support. The anode support includes hydrocarbon oxidation catalyst deposited thereon, wherein the cathode support, electrolyte, and anode support are joined together and wherein the solid oxide fuel cell operates a temperature of 600.degree. C. or less.

  5. Solid propellant exhausted aluminum oxide and hydrogen chloride - Environmental considerations

    NASA Technical Reports Server (NTRS)

    Cofer, W. R., III; Winstead, E. L.; Purgold, G. C.; Edahl, R. A.

    1993-01-01

    Measurements of gaseous hydrogen chloride (HCl) and particulate aluminum oxide (Al2O3) were made during penetrations of five Space Shuttle exhaust clouds and one static ground test firing of a shuttle booster. Instrumented aircraft were used to penetrate exhaust clouds and to measure and/or collect samples of exhaust for subsequent analyses. The focus was on the primary solid rocket motor exhaust products, HCl and Al2O3, from the Space Shuttle's solid boosters. Time-dependent behavior of HCl was determined for the exhaust clouds. Composition, morphology, surface chemistry, and particle size distributions were determined for the exhausted Al2O3. Results determined for the exhaust cloud from the static test firing were complicated by having large amounts of entrained alkaline ground debris (soil) in the lofted cloud. The entrained debris may have contributed to neutralization of in-cloud HCl.

  6. Dynamic Modeling in Solid-Oxide Fuel Cells Controller Design

    SciTech Connect

    Lu, Ning; Li, Qinghe; Sun, Xin; Khaleel, Mohammad A.

    2007-06-28

    In this paper, a dynamic model of the solid-oxide fuel cell (SOFC) power unit is developed for the purpose of designing a controller to regulate fuel flow rate, fuel temperature, air flow rate, and air temperature to maintain the SOFC stack temperature, fuel utilization rate, and voltage within operation limits. A lumped model is used to consider the thermal dynamics and the electro-chemial dynamics inside an SOFC power unit. The fluid dynamics at the fuel and air inlets are considered by using the in-flow ramp-rates.

  7. Thermal imaging of solid oxide cells operating under electrolysis conditions

    NASA Astrophysics Data System (ADS)

    Cumming, D. J.; Elder, R. H.

    2015-04-01

    Solid oxide fuel cells remain at the forefront of research into electrochemical energy conversion technology. More recent interest has focused on operating in electrolyser mode to convert steam or carbon dioxide into hydrogen or carbon monoxide, respectively. The mechanism of these reactions is not fully understood, particularly when operated in co-electrolysis mode using both steam and CO2. This contribution reports the use of a thermal camera to directly observe changes in the cell temperature during operation, providing a remote, non-contact and highly sensitive method for monitoring an operational cell.

  8. Corner heating in rectangular solid oxide electrochemical cell generators

    DOEpatents

    Reichner, Philip

    1989-01-01

    Disclosed is an improvement in a solid oxide electrochemical cell generator 1 having a rectangular design with four sides that meet at corners, and containing multiplicity of electrically connected fuel cells 11, where a fuel gas is passed over one side of said cells and an oxygen containing gas is passed into said cells, and said fuel is burned to form heat, electricity, and an exhaust gas. The improvement comprises passing the exhaust gases over the multiplicity of cells 11 in such a way that more of the heat in said exhaust gases flows at the corners of the generator, such as through channels 19.

  9. Glass Mica Composite Seals for Solid Oxide Fuel Cells

    SciTech Connect

    Chou, Y S.; Stevenson, Jeffry W.; Singh, Prabhakar

    2005-07-20

    A novel glass-mica composite seal was developed based on the previous concept of ''infiltrated'' mica seals for solid oxide fuel cells. A Ba-Al-Ca silicate sealing glass was mixed with mica flakes to form the glass-mica composite seals. The glass-mica composite seals were tested thermal cycle stability in terms of the high temperature leakage and compressive stresses. Post mortem analyses were used to characterize the fracture and leak path of the glass-mica composite seals.

  10. Oxygen Production on Mars Using Solid Oxide Electrolysis

    NASA Technical Reports Server (NTRS)

    Sridhar, K. R.

    1997-01-01

    If oxygen for propulsion and life support needs were to be extracted from martian resources, significant savings in launch mass and costs could be attained for both manned and unmanned missions. In addition to reduced cost the ability to produce oxygen from martian resources would decrease the risks associated with long duration stays on the surface of Mars. One method of producing the oxygen from the carbon dioxide rich atmosphere of Mars involves solid oxide electrolysis. A brief summary of the theory of operation will be presented followed by a schematic description of a Mars oxygen production pland and a discussion of its power consumption characteristics.

  11. Lanthanum oxide-coated stainless steel for bipolar plates in solid oxide fuel cells (SOFCs)

    NASA Astrophysics Data System (ADS)

    Yoon, Jong Seol; Lee, Jun; Hwang, Hae Jin; Whang, Chin Myung; Moon, Ji-Woong; Kim, Do-Hyeong

    Solid oxide fuel cells typically operate at temperatures of about 1000 °C. At these temperatures only ceramic interconnects such as LaCrO 3 can be employed. The development of intermediate-temperature solid oxide fuel cells (IT-SOFCs) can potentially bring about reduced manufacturing costs as it makes possible the use of an inexpensive ferritic stainless steel (STS) interconnector. However, the STS suffers from Cr 2O 3 scale formation and a peeling-off phenomenon at the IT-SOFC operating temperature in an oxidizing atmosphere. Application of an oxidation protective coating is an effective means of providing oxidation resistance. In this study, we coated an oxidation protective layer on ferritic stainless steel using a precursor solution prepared from lanthanum nitrate, ethylene glycol, and nitric acid. Heating the precursor solution at 80 °C yielded a spinable solution for coating. A gel film was coated on a STS substrate by a dip coating technique. At the early stage of the heat-treatment, lanthanum-containing oxides such as La 2O 3 and La 2CrO 6 formed, and as the heat-treatment temperature was increased, an oxidation protective perovskite-type LaCrO 3 layer was produced by the reaction between the lanthanum-containing oxide and the Cr 2O 3 scale on the SUS substrate. As the concentration of La-containing precursor solution was increased, the amount of La 2O 3 and La 2CrO 6 phases was gradually increased. The coating layer, which was prepared from a precursor solution of 0.8 M, was composed of LaCrO 3 and small amounts of (Mn,Cr)O 4 spinel. A relatively dense coating layer without pin-holes was obtained by heating the gel coating layer at 1073 K for 2 h. Microstructures and oxidation behavior of the La 2O 3-coated STS444 were investigated.

  12. Spatial Control of Cell-Nanosurface Interactions by Tantalum Oxide Nanodots for Improved Implant Geometry.

    PubMed

    Dhawan, Udesh; Pan, Hsu An; Lee, Chia Hui; Chu, Ying Hao; Huang, Guewha Steven; Lin, Yan Ren; Chen, Wen Liang

    2016-01-01

    Nanotopological cues can be exploited to understand the nature of interactions between cells and their microenvironment to generate superior implant geometries. Nanosurface parameters which modulate the cell behavior and characteristics such as focal adhesions, cell morphology are not clearly understood. Here, we studied the role of different nanotopographic dimensions in modulating the cell behavior, characteristics and ultimately the cell fate and accordingly, a methodology to improve implant surface geometry is proposed. Tantalum oxide nanodots of 50, 100nm dot diameter with an inter-dot spacing of 20, 70nm and heights 40, 100nm respectively, were engineered on Silicon substrates. MG63 cells were cultured for 72 hours and the modulation in morphology, focal adhesions, cell extensible area, cell viability, transcription factors and genes responsible for bone protein secretion as a function of the nanodot diameter, inter-dot distance and nanodot height were evaluated. Nanodots of 50nm diameter with a 20nm inter-dot spacing and 40nm height enhanced cell spreading area by 40%, promoted cell viability by 70% and upregulated transcription factors and genes twice as much, as compared to the 100nm nanodots with 70nm inter-dot spacing and 100nm height. Favorable interactions between cells and all dimensions of 50nm nanodot diameter were observed, determined with Scanning electron microscopy and Immunofluorescence staining. Nanodot height played a vital role in controlling the cell fate. Dimensions of nanodot features which triggered a transition in cell characteristics or behavior was also defined through statistical analysis. The findings of this study provide insights in the parameters of nanotopographic features which can vitally control the cell fate and should therefore be taken into account when designing implant geometries. PMID:27362432

  13. Spatial Control of Cell-Nanosurface Interactions by Tantalum Oxide Nanodots for Improved Implant Geometry

    PubMed Central

    Dhawan, Udesh; Pan, Hsu An; Lee, Chia Hui; Chu, Ying Hao; Huang, Guewha Steven; Lin, Yan Ren

    2016-01-01

    Nanotopological cues can be exploited to understand the nature of interactions between cells and their microenvironment to generate superior implant geometries. Nanosurface parameters which modulate the cell behavior and characteristics such as focal adhesions, cell morphology are not clearly understood. Here, we studied the role of different nanotopographic dimensions in modulating the cell behavior, characteristics and ultimately the cell fate and accordingly, a methodology to improve implant surface geometry is proposed. Tantalum oxide nanodots of 50, 100nm dot diameter with an inter-dot spacing of 20, 70nm and heights 40, 100nm respectively, were engineered on Silicon substrates. MG63 cells were cultured for 72 hours and the modulation in morphology, focal adhesions, cell extensible area, cell viability, transcription factors and genes responsible for bone protein secretion as a function of the nanodot diameter, inter-dot distance and nanodot height were evaluated. Nanodots of 50nm diameter with a 20nm inter-dot spacing and 40nm height enhanced cell spreading area by 40%, promoted cell viability by 70% and upregulated transcription factors and genes twice as much, as compared to the 100nm nanodots with 70nm inter-dot spacing and 100nm height. Favorable interactions between cells and all dimensions of 50nm nanodot diameter were observed, determined with Scanning electron microscopy and Immunofluorescence staining. Nanodot height played a vital role in controlling the cell fate. Dimensions of nanodot features which triggered a transition in cell characteristics or behavior was also defined through statistical analysis. The findings of this study provide insights in the parameters of nanotopographic features which can vitally control the cell fate and should therefore be taken into account when designing implant geometries. PMID:27362432

  14. Iron aluminide alloy container for solid oxide fuel cells

    DOEpatents

    Judkins, Roddie Reagan; Singh, Prabhakar; Sikka, Vinod Kumar

    2000-01-01

    A container for fuel cells is made from an iron aluminide alloy. The container alloy preferably includes from about 13 to about 22 weight percent Al, from about 2 to about 8 weight percent Cr, from about 0.1 to about 4 weight percent M selected from Zr and Hf, from about 0.005 to about 0.5 weight percent B or from about 0.001 to about 1 weight percent C, and the balance Fe and incidental impurities. The iron aluminide container alloy is extremely resistant to corrosion and metal loss when exposed to dual reducing and oxidizing atmospheres at elevated temperatures. The alloy is particularly useful for containment vessels for solid oxide fuel cells, as a replacement for stainless steel alloys which are currently used.

  15. SOLID OXIDE FUEL CELL CATHODES: Polarization Mechanisms and Modeling of the Electrochemical Performance

    NASA Astrophysics Data System (ADS)

    Fleig, Jurgen

    2003-08-01

    Several recent experimental and numerical investigations have contributed to the improved understanding of the electrochemical mechanisms taking place at solid oxide fuel cell (SOFC) cathodes and yielded valuable information on the relationships between alterable parameters (geometry/material) and the cathodic polarization resistance. Efforts to reduce the polarization resistance in SOFCs can benefit from these results, and some important aspects of the corresponding studies are reviewed. Experimental results, particularly measurements using geometrically well-defined Sr-doped LaMnO3 (LSM) cathodes, are discussed. In regard to simulations, the different levels of sophistication used in SOFC electrode modeling studies are summarized and compared. Exemplary simulations of mixed conducting cathodes that show the capabilities and limits of different modeling levels are described.

  16. Molten-Metal Electrodes for Solid Oxide Fuel Cells

    SciTech Connect

    Jayakumar, A.; Vohs, J. M.; Gorte, R. J.

    2010-11-03

    Molten In, Pb, and Sb were examined as anodes in solid oxide fuel cells (SOFC) that operate between 973 and 1173 K. The results for these metals were compared with those reported previously for molten Sn electrodes. Cells were operated under “battery” conditions, with dry He or N2 flow in the anode compartment, to characterize the electrochemical oxidation of the metals at the yttria-stabilized zirconia (YSZ)-electrolyte interface. In most cases, the open-circuit voltages (OCVs) were close to that based on equilibrium between the metals and their oxides. With Sn and In, the cell impedances increased dramatically at all temperatures after drawing current due to formation of insulating, oxide barriers at the electrolyte interface. Similar results were observed for Pb at 973 and 1073 K, but the impedance remained low even after PbO formation at 1173 K because this is above the melting temperature of PbO. Similarly, the impedances of molten Sb electrodes at 973 K were low and unaffected by current flow because of the low melting temperature of Sb{sub 2}O{sub 3}. The potential of using molten-metal electrodes for direct-carbon fuel cells and for energy-storage systems is discussed.

  17. Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program

    SciTech Connect

    Nguyen Minh

    2006-07-31

    This report summarizes the work performed for Phase I (October 2001 - August 2006) under Cooperative Agreement DE-FC26-01NT41245 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled 'Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program'. The program focuses on the development of a low-cost, high-performance 3-to-10-kW solid oxide fuel cell (SOFC) system suitable for a broad spectrum of power-generation applications. During Phase I of the program significant progress has been made in the area of SOFC technology. A high-efficiency low-cost system was designed and supporting technology developed such as fuel processing, controls, thermal management, and power electronics. Phase I culminated in the successful demonstration of a prototype system that achieved a peak efficiency of 41%, a high-volume cost of $724/kW, a peak power of 5.4 kW, and a degradation rate of 1.8% per 500 hours. . An improved prototype system was designed, assembled, and delivered to DOE/NETL at the end of the program. This prototype achieved an extraordinary peak efficiency of 49.6%.

  18. THERMAL AND ELECTROCHEMICAL THREE DIMENSIONAL CFD MODEL OF A PLANAR SOLID OXIDE ELECTROLYSIS CELL

    SciTech Connect

    Grant Hawkes; Jim O'Brien; Carl Stoots; Steve Herring; Mehrdad Shahnam

    2005-07-01

    A three-dimensional computational fluid dynamics (CFD) model has been created to model high-temperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell, as it would exist in an electrolysis stack. Details of the model geometry are specific to a stack that was fabricated by Ceramatec , Inc. and tested at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT2. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with experimental results obtained from an actual ten-cell stack tested at INL.

  19. CFD Model Of A Planar Solid Oxide Electrolysis Cell For Hydrogen Production From Nuclear Energy

    SciTech Connect

    Grant L. Hawkes; James E. O'Brien; Carl M. Stoots; J. Stephen Herring

    2005-10-01

    A three-dimensional computational fluid dynamics (CFD) model has been created to model hightemperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell as it would exist in an electrolysis stack. Details of the model geometry are specific to a stack that was fabricated by Ceramatec2, Inc. and tested at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT2. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with experimental results obtained from an actual ten-cell stack tested at INL.

  20. Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

    NASA Astrophysics Data System (ADS)

    Harthøj, Anders; Holt, Tobias; Møller, Per

    2015-05-01

    This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples are exposed in air at 800 °C for 3000 h and oxidation rates are measured and oxide scale microstructures are investigated. Area-specific resistances (ASR) in air at 850 °C of coated and uncoated samples are also measured. A dual layered oxide scale formed on all coated samples. The outer layer consisted of Co, Mn, Fe and Cr oxide and the inner layer consisted of Cr oxide. The CeO2 was present as discrete particles in the outer oxide layer after exposure. The Cr oxide layer thicknesses and oxidations rates were significantly reduced for Co/CeO2 coated samples compared to for Co coated and uncoated samples. The ASR of all Crofer 22H samples increased significantly faster than of Crofer 22 APU samples which was likely due to the presence of SiO2 in the oxide/metal interface of Crofer 22H.

  1. A metallic interconnect for a solid oxide fuel cell stack

    NASA Astrophysics Data System (ADS)

    England, Diane Mildred

    A solid oxide fuel cell (SOFC) electrochemically converts the chemical energy of reaction into electrical energy. The commercial success of planar, SOFC stack technology has a number of challenges, one of which is the interconnect that electrically and physically connects the cathode of one cell to the anode of an adjacent cell in the SOFC stack and in addition, separates the anodic and cathodic gases. An SOFC stack operating at intermediate temperatures, between 600°C and 800°C, can utilize a metallic alloy as an interconnect material. Since the interconnect of an SOFC stack must operate in both air and fuel environments, the oxidation kinetics, adherence and electronic resistance of the oxide scales formed on commercial alloys were investigated in air and wet hydrogen under thermal cycling conditions to 800°C. The alloy, Haynes 230, exhibited the slowest oxidation kinetics and the lowest area-specific resistance as a function of oxidation time of all the alloys in air at 800°C. However, the area-specific resistance of the oxide scale formed on Haynes 230 in wet hydrogen was unacceptably high after only 500 hours of oxidation, which was attributed to the high resistivity of Cr2O3 in a reducing atmosphere. A study of the electrical conductivity of the minor phase manganese chromite, MnXCr3-XO4, in the oxide scale of Haynes 230, revealed that a composition closer to Mn2CrO4 had significantly higher electrical conductivity than that closer to MnCr 2O4. Haynes 230 was coated with Mn to form a phase closer to the Mn2CrO4 composition for application on the fuel side of the interconnect. U.S. Patent No. 6,054,231 is pending. Although coating a metallic alloy is inexpensive, the stringent economic requirements of SOFC stack technology required an alloy without coating for production applications. As no commercially available alloy, among the 41 alloys investigated, performed to the specifications required, a new alloy was created and designated DME-A2. The oxide scale

  2. A fine organization method of spatial geometry data about three-dimensional geographic solid

    NASA Astrophysics Data System (ADS)

    Li, Jing-wen; Xue, Long-li; Wang, Fang; Wang, Ke

    2015-12-01

    With the rise of the wisdom of urban construction, the intelligent city requirements expression to fine the geometric structure of spatial entity, so as to realize the refined analysis of urban geographic information, to achieve the purpose of intelligent management. But the traditional geographic entity geometric data organization method ignores the express geographic entity's internal geometry information,, and can not meet the requirements of the fine analysis. Therefore, it is a problem to be solved that how to make a thorough physical and geometrical data of its spatial geometry. In this paper, we propose a method of organizing the Tetrahedral Network in the geographic entity and combining with hierarchical representation for B-rep model to solve the problem.

  3. Three-dimensional elastic stress and displacement analysis of finite circular geometry solids containing cracks

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, J. P.; Mendelson, A.; Kring, J.

    1973-01-01

    A seminumerical method is presented for solving a set of coupled partial differential equations subject to mixed and coupled boundary conditions. The use of this method is illustrated by obtaining solutions for two circular geometry and mixed boundary value problems in three-dimensional elasticity. Stress and displacement distributions are calculated in an axisymmetric, circular bar of finite dimensions containing a penny-shaped crack. Approximate results for an annular plate containing internal surface cracks are also presented.

  4. Santa Clara County Planar Solid Oxide Fuel Cell Demonstration Project

    SciTech Connect

    Fred Mitlitsky; Sara Mulhauser; David Chien; Deepak Shukla; David Weingaertner

    2009-11-14

    The Santa Clara County Planar Solid Oxide Fuel Cell (PSOFC) project demonstrated the technical viability of pre-commercial PSOFC technology at the County 911 Communications headquarters, as well as the input fuel flexibility of the PSOFC. PSOFC operation was demonstrated on natural gas and denatured ethanol. The Santa Clara County Planar Solid Oxide Fuel Cell (PSOFC) project goals were to acquire, site, and demonstrate the technical viability of a pre-commercial PSOFC technology at the County 911 Communications headquarters. Additional goals included educating local permit approval authorities, and other governmental entities about PSOFC technology, existing fuel cell standards and specific code requirements. The project demonstrated the Bloom Energy (BE) PSOFC technology in grid parallel mode, delivering a minimum 15 kW over 8760 operational hours. The PSOFC system demonstrated greater than 81% electricity availability and 41% electrical efficiency (LHV net AC), providing reliable, stable power to a critical, sensitive 911 communications system that serves geographical boundaries of the entire Santa Clara County. The project also demonstrated input fuel flexibility. BE developed and demonstrated the capability to run its prototype PSOFC system on ethanol. BE designed the hardware necessary to deliver ethanol into its existing PSOFC system. Operational parameters were determined for running the system on ethanol, natural gas (NG), and a combination of both. Required modeling was performed to determine viable operational regimes and regimes where coking could occur.

  5. LG Solid Oxide Fuel Cell (SOFC) Model Development

    SciTech Connect

    Haberman, Ben; Martinez-Baca, Carlos; Rush, Greg

    2013-05-31

    This report presents a summary of the work performed by LG Fuel Cell Systems Inc. during the project LG Solid Oxide Fuel Cell (SOFC) Model Development (DOE Award Number: DE-FE0000773) which commenced on October 1, 2009 and was completed on March 31, 2013. The aim of this project is for LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) to develop a multi-physics solid oxide fuel cell (SOFC) computer code (MPC) for performance calculations of the LGFCS fuel cell structure to support fuel cell product design and development. A summary of the initial stages of the project is provided which describes the MPC requirements that were developed and the selection of a candidate code, STAR-CCM+ (CD-adapco). This is followed by a detailed description of the subsequent work program including code enhancement and model verification and validation activities. Details of the code enhancements that were implemented to facilitate MPC SOFC simulations are provided along with a description of the models that were built using the MPC and validated against experimental data. The modeling work described in this report represents a level of calculation detail that has not been previously available within LGFCS.

  6. Solid Oxide Fuel Cells Operating on Alternative and Renewable Fuels

    SciTech Connect

    Wang, Xiaoxing; Quan, Wenying; Xiao, Jing; Peduzzi, Emanuela; Fujii, Mamoru; Sun, Funxia; Shalaby, Cigdem; Li, Yan; Xie, Chao; Ma, Xiaoliang; Johnson, David; Lee, Jeong; Fedkin, Mark; LaBarbera, Mark; Das, Debanjan; Thompson, David; Lvov, Serguei; Song, Chunshan

    2014-09-30

    This DOE project at the Pennsylvania State University (Penn State) initially involved Siemens Energy, Inc. to (1) develop new fuel processing approaches for using selected alternative and renewable fuels – anaerobic digester gas (ADG) and commercial diesel fuel (with 15 ppm sulfur) – in solid oxide fuel cell (SOFC) power generation systems; and (2) conduct integrated fuel processor – SOFC system tests to evaluate the performance of the fuel processors and overall systems. Siemens Energy Inc. was to provide SOFC system to Penn State for testing. The Siemens work was carried out at Siemens Energy Inc. in Pittsburgh, PA. The unexpected restructuring in Siemens organization, however, led to the elimination of the Siemens Stationary Fuel Cell Division within the company. Unfortunately, this led to the Siemens subcontract with Penn State ending on September 23rd, 2010. SOFC system was never delivered to Penn State. With the assistance of NETL project manager, the Penn State team has since developed a collaborative research with Delphi as the new subcontractor and this work involved the testing of a stack of planar solid oxide fuel cells from Delphi.

  7. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, L.; Ruka, R.J.; Singhal, S.C.

    1999-08-03

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO{sub 3}. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell. 3 figs.

  8. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, Lewis; Ruka, Roswell J.; Singhal, Subhash C.

    1999-01-01

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

  9. Compressive Mica Seals for Solid Oxide Fuel Cells

    SciTech Connect

    Chou, Y S.; Stevenson, Jeffry W.

    2006-08-01

    Sealing technology is currently considered a top priority task for planar solid oxide fuel cell stack development. Compressive mica seals are among the major candidates for sealing materials due to their thermal, chemical, and electrical properties. In this paper, a comprehensive study of mica seals will be presented. Two natural micas, Muscovite and Phlogopite, were investigated in either a monolithic single crystal sheet form or a paper form composed of discrete mica flakes. A ''hybrid'' mica seal, developed after identification of the major leak paths in compressive mica seals, demonstrated leak rates which were hundreds to thousands times lower than leak rates for conventional mica seals. The hybrid mica seals were further modified by infiltration with wetting materials; these ''infiltrated'' micas showed excellent thermal cycle stability with very low leak rates (10-3 sccm/cm). The micas were also subjected to studies to evaluate thermal stability in a reducing environment as well as the effect of compressive stresses on leak rates. In addition, long-term open circuit voltage measurements versus thermal cycling showed constant voltages over 1000 cycles. The comprehensive study clearly demonstrated the potential of compressive mica seals as sealing candidates for solid oxide fuel cells.

  10. SOLID OXIDE FUEL CELL HYBRID SYSTEM FOR DISTRIBUTED POWER GENERATION

    SciTech Connect

    Faress Rahman; Nguyen Minh

    2003-07-01

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC during the January 2003 to June 2003 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. This report summarizes the results obtained to date on: System performance analysis and model optimization; Reliability and cost model development; System control including dynamic model development; Heat exchanger material tests and life analysis; Pressurized SOFC evaluation; and Pre-baseline system definition for coal gasification fuel cell system concept.

  11. Effect of Substrate Thickness on Oxide Scale Spallation for Solid Oxide Fuel Cells

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2011-07-01

    In this paper, the effect of the ferritic substrate's thickness on the delamination/spallation of the oxide scale was investigated experimentally and numerically. At the high-temperature oxidation environment of solid oxide fuel cells (SOFCs), a combination of growth stress with thermal stresses may lead to scale delamination/buckling and eventual spallation during SOFC stack cooling, even leading to serious degradation of cell performance. The growth stress is induced by the growth of the oxide scale on the scale/substrate interface, and thermal stress is induced by a mismatch of the coefficient of thermal expansion between the oxide scale and the substrate. The numerical results show that the interfacial shear stresses, which are the driving force of scale delamination between the oxide scale and the ferritic substrate, increase with the growth of the oxide scale and also with the thickness of the ferritic substrate; i.e., the thick ferritic substrate can easily lead to scale delamination and spallation. Experimental observation confirmed the predicted results of the delamination and spallation of the oxide scale on the ferritic substrate.

  12. High temperature seals for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Parihar, Shailendra S.

    Solid Oxide Fuel cells (SOFCs) represent a clean and efficient alternative to existing methods of energy production. But, they need hermetic seals to prevent fuel-oxidant mixing within the stack. Glasses are attractive options for fabrication of these high temperature seals but suffer from their inherent brittleness and tend to crack during thermal cycling. In this study, an innovative concept of self-healing glass seals is developed to solve the problem of cracking of glasses in a SOFC seal. Rationale behind this concept is that a glass of suitable viscosity characteristics can flow and heal cracks at SOFC operating temperatures and thus can provide seals which can self-repair. A novel method, based on in-situ video imaging of cracks on the glass surface during high temperature treatment is developed and used to select and evaluate the suitability of different glasses for making self-healing seals. Promising glasses are studied experimentally to determine kinetics of healing of Vickers indented cracks at various temperatures. In addition, the effect of crystallization of glass on its healing kinetics is studied. A model is developed for crack healing behavior and is used to validate the experimental data. Studies on Cracks healing and crystallization of glasses showed that glasses with no crystallization tendency show fast crack healing response, whereas glasses which crystallize display sluggish healing. A glass displaying fast healing kinetics and good stability against crystallization is used to fabricate self healing glass seals for SOFCs. Seals fabricated using this glass not only remained hermetic but also maintained their self i healing ability for as long as 3000 hours at 800°C and 300 thermal cycles between room temperature and 800°C. These results clearly indicated that self-healing glasses are promising candidates for SOFC seals. Key words. Solid Oxide Fuel Cells, Glass Seals, Self-Healing Glasses, Seal Leak Testing.

  13. Versatile Side-Illumination Geometry for Tip-Enhanced Raman Spectroscopy at Solid/Liquid Interfaces.

    PubMed

    Martín Sabanés, Natalia; Driessen, Leonie M A; Domke, Katrin F

    2016-07-19

    In situ characterization of surfaces with tip-enhanced Raman spectroscopy (TERS) provides chemical and topographic information with high spatial resolution and submonolayer chemical sensitivity. To further the versatility of the TERS approach toward more complex systems such as biological membranes or energy conversion devices, adaptation of the technique to solid/liquid working conditions is essential. Here, we present a home-built side-illumination TERS setup design based on a commercial scanning tunneling microscope (STM) as a versatile, cost-efficient solution for TERS at solid/liquid interfaces. Interestingly, the results obtained from showcase resonant dye and nonresonant thiophenol monolayers adsorbed on Au single crystals suggest that excitation beam aberrations due to the presence of the aqueous phase are small enough not to limit TER signal detection. The STM parameters are found to play a crucial role for solid/liquid TERS sensitivity. Raman enhancement factors of 10(5) at μW laser power demonstrate the great potential the presented experimental configuration holds for solid/liquid interfacial spectroscopic studies. PMID:27299508

  14. Ablation and geometry change study of solid armature in a railgun

    NASA Astrophysics Data System (ADS)

    Zhang, Ya-Dong; Ruan, Jiang-Jun; Hu, Yuan-Chao; Gong, Ruo-Han; Wen, Wu

    2013-08-01

    Armature plays an important role in the electromagnetic launch process. Due to the skin effect, the current density distribution is neither uniform on the rail, nor on the armature. High current density centralization in one part could lead to a partial high temperature and make the armature material melt down and be ablated, especially at low velocity. In this paper we try to change the geometry of a Cshaped armature to improve the current density distribution and reduce the ablation. Four variants of C-shaped armatures are designed to study the specific features, including a conventional C-shaped armature (CCA), a rounded leading edge C-shaped armature (LCA), a rounded trailing edge C-shaped armature (TCA), and a rounded incorporate edge C-shaped armature (ICA). A novel low-speed experiment is constructed and tested. The armatures are ablated and recovered to compare the improved effects. Then finite element simulations according to the experimental results are performed to further analyze the experimental results. It is proved that the current density and hence the temperature distribution can be immensely improved by simply changing the armature geometry. LCA and ICA show that the erosion is more uniform on the contact surface due to the rounded leading edge. The curved trailing edge could improve the uniformity of the current on the interface. ICA which combines the effects of LCA and TCA is the best option in the four armatures. How much the leading edge and the trailing edge should be curved involves the geometry of CCA and the posture of the interface on the rail. A saddle shape is a good option to improve the current density and temperature distribution in the throat. Erosion mechanism is analyzed finally. The experiments and simulations support the erosion and transition mechanism. A detailed description of the experiments and simulations is also presented in this paper.

  15. Modeling of thermal expansion coefficient of perovskite oxide for solid oxide fuel cell cathode

    NASA Astrophysics Data System (ADS)

    Heydari, F.; Maghsoudipour, A.; Alizadeh, M.; Khakpour, Z.; Javaheri, M.

    2015-09-01

    Artificial intelligence models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the material science. This study investigates the applicability of adaptive neuro-fuzzy inference system (ANFIS) approach for modeling the performance parameters of thermal expansion coefficient (TEC) of perovskite oxide for solid oxide fuel cell cathode. Oxides (Ln = La, Nd, Sm and M = Fe, Ni, Mn) have been prepared and characterized to study the influence of the different cations on TEC. Experimental results have shown TEC decreases favorably with substitution of Nd3+ and Mn3+ ions in the lattice. Structural parameters of compounds have been determined by X-ray diffraction, and field emission scanning electron microscopy has been used for the morphological study. Comparison results indicated that the ANFIS technique could be employed successfully in modeling thermal expansion coefficient of perovskite oxide for solid oxide fuel cell cathode, and considerable savings in terms of cost and time could be obtained by using ANFIS technique.

  16. Fuel oxidation efficiencies and exhaust composition in solid oxide fuel cells.

    PubMed

    Pomfret, Michael B; Demircan, Oktay; Sukeshini, A Mary; Walker, Robert A

    2006-09-01

    Solid oxide fuel cells (SOFCs) are electrochemical devices that rely on ion migration through a solid-state electrolyte to oxidize fuel and produce electricity. The present study employs Fourier transform infrared spectroscopy to quantify the exhaust of an SOFC operating with fuel flows of methane over Ni/YSZ cermet anodes and butane over Ni/YSZ and Cu/CeO2/YSZ cermet anodes. Data show that hydrocarbon fuels can participate in a variety of different reactions including direct electrochemical oxidation, various reforming processes, and surface-catalyzed carbon deposition. These findings have direct consequences for assessing the environmental impact of SOFCs in terms of the exhaust discharged from devices operating with common hydrocarbon fuel feeds. In the work presented below, a measure of fuel oxidation efficiency is found by comparing the partial pressure of CO2 (P(CO2)) in the SOFC exhaust to the partial pressure of CO (P(CO)). The fuel anode combination with the largest P(CO2)/P(CO) ratio is the C4H10 over Cu/CeO2 combination (0.628 +/- 0.016). The CH4 over Ni cell type has the second highest ratio (0.486 +/- 0.023). The C4H10 over Ni cell type gives a ratio of 0.224 +/- 0.001. Attempts to balance the carbon content of the fuel feed and exhaust lead to predictions of SOFC fuel oxidation mechanisms. PMID:16999142

  17. Strength of an electrolyte supported solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Fleischhauer, Felix; Bermejo, Raul; Danzer, Robert; Mai, Andreas; Graule, Thomas; Kuebler, Jakob

    2015-11-01

    For the proper function of solid oxide fuel cells (SOFC) their structural integrity must be maintained during their whole lifetime. Any cell fracture would cause leakage and partial oxidization of the anode, leading to a reduced performance, if not catastrophic failure of the whole stack. In this study, the mechanical strength of a state of the art SOFC, developed and produced by Hexis AG/Switzerland, was investigated with respect to the influence of temperature and ageing, whilst for the anode side of the cell the strength was measured under reducing and oxidizing atmospheres. Ball-on-3-Ball bending strength tests and fractography conducted on anode and cathode half-cells revealed the underlying mechanisms, which lead to cell fracture. They were found to be different for the cathode and the anode side and that they change with temperature and ageing. Both anode and cathode sides exhibit the lowest strength at T = 850 °C, which is greatly reduced to the initial strength of the bare electrolyte. This reduction is the consequence of the formation of cracks in the electrode layer which either directly penetrate into the electrolyte (anode side) or locally increase the stress intensity level of pre-existing flaws of the electrolytes at the interface (cathode side).

  18. Serially connected solid oxide fuel cells having monolithic cores

    DOEpatents

    Herceg, J.E.

    1985-05-20

    Disclosed is a solid oxide fuel cell for electrochemically combining fuel and oxidant for generating galvanic output. The cell core has an array of cell segments electrically serially connected in the flow direction, each segment consisting of electrolyte walls and interconnect that are substantially devoid of any composite inert materials for support. Instead, the core is monolithic, where each electrolyte wall consists of thin layers of cathode and anode materials sandwiching a thin layer of electrolyte material therebetween. Means direct the fuel to the anode-exposed core passageways and means direct the oxidant to the cathode-exposed core passageways; and means also direct the galvanic output to an exterior circuit. Each layer of the electrolyte composite materials is of the order of 0.002 to 0.01 cm thick; and each layer of the cathode and anode materials is of the order of 0.002 to 0.05 cm thick. Between 2 and 50 cell segments may be connected in series.

  19. Direct oxidation of waste vegetable oil in solid-oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zhou, Z. F.; Kumar, R.; Thakur, S. T.; Rudnick, L. R.; Schobert, H.; Lvov, S. N.

    Solid-oxide fuel cells with ceria, ceria-Cu, and ceria-Rh anode were demonstrated to generate stable electric power with waste vegetable oil through direct oxidation of the fuel. The only pre-treatment to the fuel was a filtration to remove particulates. The performance of the fuel cell was stable over 100 h for the waste vegetable oil without dilution. The generated power was up to 0.25 W cm -2 for ceria-Rh fuel cell. This compares favorably with previously studied hydrocarbon fuels including jet fuels and Pennsylvania crude oil.

  20. Extension of the Test-Area methodology for calculating solid-fluid interfacial tensions in cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Blas, Felipe J.; Mendiboure, Bruno

    2013-04-01

    We extend the well-known Test-Area methodology of Gloor et al. [J. Chem. Phys. 123, 134703 (2005)], 10.1063/1.2038827, originally proposed to evaluate the surface tension of planar fluid-fluid interfaces along a computer simulation in the canonical ensemble, to deal with the solid-fluid interfacial tension of systems adsorbed on cylindrical pores. The common method used to evaluate the solid-fluid interfacial tension invokes the mechanical relation in terms of the tangential and normal components of the pressure tensor relative to the interface. Unfortunately, this procedure is difficult to implement in the case of cylindrical geometry, and particularly complex in case of nonspherical molecules. Following the original work of Gloor et al., we perform free-energy perturbations due to virtual changes in the solid-fluid surface. In this particular case, the radius and length of the cylindrical pore are varied to ensure constant-volume virtual changes of the solid-fluid surface area along the simulation. We apply the modified methodology for determining the interfacial tension of a system of spherical Lennard-Jones molecules adsorbed inside cylindrical pores that interact with fluid molecules through the generalized 10-4-3 Steele potential recently proposed by Siderius and Gelb [J. Chem. Phys. 135, 084703 (2011)], 10.1063/1.3626804. We analyze the effect of pore diameter, density of adsorbed molecules, and fluid-fluid cutoff distance of the Lennard-Jones intermolecular potential on the solid-fluid interfacial tension. This extension, as the original Test-Area formulation, offers clear advantages over the classical mechanical route of computational efficiency, easy of implementation, and generality.

  1. In situ studies of fuel oxidation in solid oxide fuel cells.

    PubMed

    Pomfret, Michael B; Owrutsky, Jeffrey C; Walker, Robert A

    2007-03-15

    Existing electrochemical experiments and models of fuel oxidation postulate about the importance of different oxidation pathways and relative fuel conversion efficiencies, but specific information is often lacking. Experiments described below present the first direct, in situ measurements of relevant chemical species formed on solid oxide fuel cell (SOFC) cermet anodes operating with both butane and CO fuel feeds. Raman spectroscopy is used to acquire vibrational spectra from SOFC anodes at 715 degrees C during operation. Both C4H10 and CO form graphitic intermediates. In the limit of a large oxide flux, excess butane forms ordered graphite but only transiently. At higher cell potentials (e.g., less current being drawn) ordered and disordered graphite form on the Ni cermet anode following exposure to butane, and under open circuit voltage (OCV) conditions the graphite persists indefinitely. The chemistry of CO oxidation is such that ordered graphite and a Ni-COO intermediate form only at intermediate cell potentials. Concurrent voltammetry studies show that the formation of graphite with butane at OCV leads first to decreased cell performance after exposure to 25 cm3 butane, then recovered performance after 75 cm3. CO voltammetry data show that at lower potentials the oxide flux through the YSZ electrolyte is sufficient to oxidize the Ni in the anode especially near the interface with the electrolyte. PMID:17295449

  2. Molten metal electrodes in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Javadekar, Ashay Dileep

    Molten metal electrodes in solid oxide fuel cells are electrochemically characterized for their possible use in direct carbon oxidation and energy storage. The cells were operated in the battery mode at 973 K, without added fuel, in order to understand the oxidation characteristics of Sb alloys as anodes at electrolyte interfaces. The cells using 50-mol% In-Sb and Sn-Sb mixtures exhibited open-circuit voltages (OCV) of 1.0 and 0.93 V, values similar to those of cells with pure In and Sn anodes respectively, and insulating In2O3 and SnO2 layers formed at the electrolyte interface. The 50-mol% Sb-Bi cell had an OCV of 0.73 V initially, close to that with pure Sb anode. The OCV remained constant until all of the Sb had been oxidized, after which it dropped to 0.43 V, similar to the value for pure Bi. SEM analysis of the spent cell showed two distinct phases, with metallic Bi at the bottom and Sb2O3 at the top. The cell with 50-mol% Sb-Pb anode exhibited an OCV that changed continuously with conversion, from 0.73 V initially to 0.67 V following the addition of charge equivalent to oxidation of 120% the Sb. The total cell impedance remained low for this entire period. EDS measurements on the sectioned Sb-Pb cell suggested formation of a mixed oxide of Pb and Sb. An energy-storage concept using molten Sb as the fuel in a reversible solid-oxide electrochemical cell was tested using a button cell with a Sc-stabilized zirconia electrolyte at 973 K, by measuring the impedances under fuel-cell and electrolyzer conditions for a range of stirred Sb-Sb2O 3 compositions. The Sb-Sb2O3 electrode impedances were found to be on the order of 0.15 ohm.cm2 for both fuel-cell and electrolyzer conditions, for compositions up to 30% Sb and 70% Sb2O3. The OCVs were 0.75 V, independent of conversion. The use of molten neat Ag and alloyed Ag-Sb for direct-carbon anodes in SOFCs has been examined at 1273 K. For Ag, an OCV typical of that expected for carbon oxidation, 1.12 V, was observed when

  3. Metal Interconnects for Solid Oxide Fuel Cell Power Systems

    SciTech Connect

    S. Elangovan

    2006-04-01

    Interconnect development is identified by the US Department of energy as a key technical area requiring focused research to meet the performance and cost goals under the Solid State Energy Conversion Alliance initiative. In the Phase I SECA Core Technology Program, Ceramatec investigated a commercial ferritic stainless steel composition for oxidation resistance properties by measuring the weight gain when exposed to air at the fuel cell operating temperature. A pre-treatment process that results in a dense, adherent scale was found to reduce the oxide scale growth rate significantly. A process for coating the surface of the alloy in order to reduce the in-plane resistance and potentially inhibit chromium oxide evaporation was also identified. The combination of treatments provided a very low resistance through the scale. The resistance measured was as low as 10 milliohm-cm2 at 750 C in air. The oxide scale was also found to be stable in humidified air at 750 C. The resistance value was stable over several thermal cycles. A similar treatment and coating for the fuel side of the interconnect also showed an exceptionally low resistance of one milliohm-cm2 in humidified hydrogen at 750 c, and was stable through multiple thermal cycles. Measurement of interconnect resistance when it was exposed to both air and humidified hydrogen on opposite sides also showed low, stable resistance after additional modification to the pre-treatment process. Resistance stacks, using an interconnect stack with realistic gas flows, also provided favorable results. Chromium evaporation issue however requires testing of fuel stacks and was outside of the scope of this project. based on results to-date, the alloy selection and the treatment processes appear to be well suited for SOFC interconnect application.

  4. Two-Dimensional Iron Tungstate: A Ternary Oxide Layer With Honeycomb Geometry

    PubMed Central

    2016-01-01

    The exceptional physical properties of graphene have sparked tremendous interests toward two-dimensional (2D) materials with honeycomb structure. We report here the successful fabrication of 2D iron tungstate (FeWOx) layers with honeycomb geometry on a Pt(111) surface, using the solid-state reaction of (WO3)3 clusters with a FeO(111) monolayer on Pt(111). The formation process and the atomic structure of two commensurate FeWOx phases, with (2 × 2) and (6 × 6) periodicities, have been characterized experimentally by combination of scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD) and understood theoretically by density functional theory (DFT) modeling. The thermodynamically most stable (2 × 2) phase has a formal FeWO3 stoichiometry and corresponds to a buckled Fe2+/W4+ layer arranged in a honeycomb lattice, terminated by oxygen atoms in Fe–W bridging positions. This 2D FeWO3 layer has a novel structure and stoichiometry and has no analogues to known bulk iron tungstate phases. It is theoretically predicted to exhibit a ferromagnetic electronic ground state with a Curie temperature of 95 K, as opposed to the antiferromagnetic behavior of bulk FeWO4 materials. PMID:27110319

  5. Interconnects for intermediate temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Huang, Wenhua

    Presently, one of the principal goals of solid oxide fuel cells (SOFCs) research is to reduce the stack operating temperature to between 600 and 800°C. However, one of the principal technological barriers is the non-availability of a suitable material satisfying all of the stability requirements for the interconnect. In this work two approaches for intermediate temperature SOFC interconnects have been explored. The first approach comprises an interconnect consisting of a bi-layer structure, a p-type oxide (La0.96Sr0.08MnO 2.001/LSM) layer exposed to a cathodic environment, and an n-type oxide (Y0.08Sr0.88Ti0.95Al0.05O 3-delta/YSTA) layer exposed to anodic conditions. Theoretical analysis based on the bi-layer structure has established design criteria to implement this approach. The analysis shows that the interfacial oxygen partial pressure, which determines the interconnect stability, is independent of the electronic conductivities of both layers but dependent on the oxygen ion layer interconnects, the oxygen ion conductivities of LSM and YSTA were measured as a function of temperature and oxygen partial pressure. Based on the measured data, it has been determined that if the thickness of YSTA layer is around 0.1cm, the thickness of LSM layer should be around 0.6 mum in order to maintain the stability of LSM. In a second approach, a less expensive stainless steel interconnect has been studied. However, one of the major concerns associated with the use of metallic interconnects is the development of a semi-conducting or insulating oxide scale and chromium volatility during extended exposure to the SOFC operating environment. Dense and well adhered Mn-Cu spinet oxide coatings were successfully deposited on stainless steel by an electrophoretic deposition (EPD) technique. It was found that the Mn-Cu-O coating significantly reduced the oxidation rate of the stainless steel and the volatility of chromium. The area specific resistance (ASR) of coated Crofer 22 APU is

  6. Electrical contact structures for solid oxide electrolyte fuel cell

    DOEpatents

    Isenberg, Arnold O.

    1984-01-01

    An improved electrical output connection means is provided for a high temperature solid oxide electrolyte type fuel cell generator. The electrical connection of the fuel cell electrodes to the electrical output bus, which is brought through the generator housing to be connected to an electrical load line maintains a highly uniform temperature distribution. The electrical connection means includes an electrode bus which is spaced parallel to the output bus with a plurality of symmetrically spaced transversely extending conductors extending between the electrode bus and the output bus, with thermal insulation means provided about the transverse conductors between the spaced apart buses. Single or plural stages of the insulated transversely extending conductors can be provided within the high temperatures regions of the fuel cell generator to provide highly homogeneous temperature distribution over the contacting surfaces.

  7. Resilient Sealing Materials for Solid Oxide Fuel Cells

    SciTech Connect

    Signo T. Reis; Richard K. Brow

    2006-09-30

    This report describes the development of ''invert'' glass compositions designed for hermetic seals in solid oxide fuel cells (SOFC). Upon sealing at temperatures compatible with other SOFC materials (generally {le}900 C), these glasses transform to glass-ceramics with desirable thermo-mechanical properties, including coefficients of thermal expansion (CTE) over 11 x 10{sup -6}/C. The long-term (>four months) stability of CTE under SOFC operational conditions (e.g., 800 C in wet forming gas or in air) has been evaluated, as have weight losses under similar conditions. The dependence of sealant properties on glass composition are described in this report, as are experiments to develop glass-matrix composites by adding second phases, including Ni and YSZ. This information provides design-guidance to produce desirable sealing materials.

  8. Failure analysis of electrolyte-supported solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Fleischhauer, Felix; Tiefenauer, Andreas; Graule, Thomas; Danzer, Robert; Mai, Andreas; Kuebler, Jakob

    2014-07-01

    For solid oxide fuel cells (SOFCs) one key aspect is the structural integrity of the cell and hence its thermo mechanical long term behaviour. The present study investigates the failure mechanisms and the actual causes for fracture of electrolyte supported SOFCs which were run using the current μ-CHP system of Hexis AG, Winterthur - Switzerland under lab conditions or at customer sites for up to 40,000 h. In a first step several operated stacks were demounted for post-mortem inspection, followed by a fractographic evaluation of the failed cells. The respective findings are then set into a larger picture including an analysis of the present stresses acting on the cell like thermal and residual stresses and the measurements regarding the temperature dependent electrolyte strength. For all investigated stacks, the mechanical failure of individual cells can be attributed to locally acting bending loads, which rise due to an inhomogeneous and uneven contact between the metallic interconnect and the cell.

  9. AlliedSignal solid oxide fuel cell technology

    SciTech Connect

    Minh, N.; Barr, K.; Kelly, P.; Montgomery, K.

    1996-12-31

    AlliedSignal has been developing high-performance, lightweight solid oxide fuel cell (SOFC) technology for a broad spectrum of electric power generation applications. This technology is well suited for use in a variety of power systems, ranging from commercial cogeneration to military mobile power sources. The AlliedSignal SOFC is based on stacking high-performance thin-electrolyte cells with lightweight metallic interconnect assemblies to form a compact structure. The fuel cell can be operated at reduced temperatures (600{degrees} to 800{degrees}C). SOFC stacks based on this design has the potential of producing 1 kW/kg and 1 ML. This paper summarizes the technical status of the design, manufacture, and operation of AlliedSignal SOFCs.

  10. Wet air oxidation of solid waste made of polymers

    SciTech Connect

    Krisner, E.; Ambrosio, M.; Massiani, C.

    2000-03-01

    Wet air oxidation was attempted on synthetic (mixture of plastics of various compositions) and natural (cellulose substances) solid polymers. The temperature was maintained at 270 C and the oxygen pressure varied from 0 to 2 MPa (from understoichiometric conditions to oxygen excess). No valorizable compounds were found, even in runs carried out under an oxygen deficit. Suitable conditions for the total destruction of the initial polymers were temperatures above 270 C, an excess of oxygen, and a residence time of less than 1 h. Only such degradable compounds as acetic and benzoic acids are found at low concentrations. Formation of chlorine and gaseous hydrochloric acid can be limited by adding CaCO{sub 3} as a neutralizing agent.

  11. Functionally graded composite cathodes for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Hart, N. T.; Brandon, N. P.; Day, M. J.; Lapeña-Rey, N.

    Functionally graded solid oxide fuel cell (SOFC) cathodes have been prepared from mixtures of strontium-doped lanthanum manganite (LSM) and gadolinia-doped ceria (CGO) using slurry spraying techniques. Similar samples were also prepared from mixtures of LSM and ytrria-stabilised zirconia (YSZ). A current collector comprising a mixture of LSM and strontium-doped lanthanum cobaltite (LSCO) was then applied to both cathode types. Samples were characterised using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Characterisation using EIS techniques showed that cathodes incorporating CGO into the structure gave improved performance over those fabricated using YSZ. These performance gains were most noticeable as the temperature was decreased towards 700 °C, and were maintained during the testing of three cell membrane electrode assemblies fabricated to the Rolls-Royce design.

  12. Solid Oxide Fuel Cell Seal Glass - BN Nanotubes Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Choi, Sung R.; Hurst, Janet B.; Garg, Anita

    2005-01-01

    Solid oxide fuel cell seal glass G18 composites reinforced with approx.4 weight percent of BN nanotubes were fabricated via hot pressing. Room temperature strength and fracture toughness of the composite were determined by four-point flexure and single edge V-notch beam methods, respectively. The strength and fracture toughness of the composite were higher by as much as 90% and 35%, respectively, than those of the glass G18. Microscopic examination of the composite fracture surfaces using SEM and TEM showed pullout of the BN nanotubes, similar in feature to fiber-reinforced ceramic matrix composites with weak interfaces. Other mechanical and physical properties of the composite will also be presented.

  13. Cost projections for planar solid oxide fuel cell systems

    SciTech Connect

    Krist, K.; Wright, J.D.; Romero, C.; Chen, Tan Ping

    1996-12-31

    The Gas Research Institute (GRI) is funding fundamental research on solid oxide fuel cells (SOFCs) that operate at reduced temperature. As part of this effort, we have carried out engineering analysis to determine what areas of research can have the greatest effect on the commercialization of SOFCs. Previous papers have evaluated the markets for SOFCs and the amount which a customer will be willing to pay for fuel cell systems or stacks in these markets, the contribution of materials costs to the total stack cost, and the benefits and design requirements associated with reduced temperature operation. In this paper, we describe the cost of fabricating SOFC stacks by different methods. The complete analysis is available in report form.

  14. Improved solid oxide fuel cell performance with nanostructured electrolytes.

    PubMed

    Chao, Cheng-Chieh; Hsu, Ching-Mei; Cui, Yi; Prinz, Fritz B

    2011-07-26

    Considerable attention has been focused on solid oxide fuel cells (SOFCs) due to their potential for providing clean and reliable electric power. However, the high operating temperatures of current SOFCs limit their adoption in mobile applications. To lower the SOFC operating temperature, we fabricated a corrugated thin-film electrolyte membrane by nanosphere lithography and atomic layer deposition to reduce the polarization and ohmic losses at low temperatures. The resulting micro-SOFC electrolyte membrane showed a hexagonal-pyramid array nanostructure and achieved a power density of 1.34 W/cm(2) at 500 °C. In the future, arrays of micro-SOFCs with high power density may enable a range of mobile and portable power applications. PMID:21657222

  15. A review of integration strategies for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Xiongwen; Chan, S. H.; Li, Guojun; Ho, H. K.; Li, Jun; Feng, Zhenping

    Due to increasing oil and gas demand, the depletion of fossil resources, serious global warming, efficient energy systems and new energy conversion processes are urgently needed. Fuel cells and hybrid systems have emerged as advanced thermodynamic systems with great promise in achieving high energy/power efficiency with reduced environmental loads. In particular, due to the synergistic effect of using integrated solid oxide fuel cell (SOFC) and classical thermodynamic cycle technologies, the efficiency of the integrated system can be significantly improved. This paper reviews different concepts/strategies for SOFC-based integration systems, which are timely transformational energy-related technologies available to overcome the threats posed by climate change and energy security.

  16. Planar solid oxide fuel cells: the Australian experience and outlook

    NASA Astrophysics Data System (ADS)

    Godfrey, Bruce; Föger, Karl; Gillespie, Rohan; Bolden, Roger; Badwal, S. P. S.

    Since 1992, Ceramic Fuel Cells (CFCL) has grown to what is now the largest focussed program globally for development of planar ceramic (solid oxide) fuel cell, SOFC, technology. A significant intellectual property position in know-how and patents has been developed, with over 80 people involved in the venture. Over $A60 million in funding for the activities of the company has been raised from private companies, government-owned corporations and government business-support programs, including from energy — particularly electricity — industry shareholders that can facilitate access to local markets for our products. CFCL has established state-of-the-art facilities for planar SOFC R&D, with their expansion and scaling-up to pilot manufacturing capability underway. We expect to achieve commercial introduction of our market-entry products in 2002, with prototype systems expected to be available from early 2001.

  17. Five Kilowatt Solid Oxide Fuel Cell/Diesel Reformer

    SciTech Connect

    Dennis Witmer; Thomas Johnson

    2008-12-31

    Reducing fossil fuel consumption both for energy security and for reduction in global greenhouse emissions has been a major goal of energy research in the US for many years. Fuel cells have been proposed as a technology that can address both these issues--as devices that convert the energy of a fuel directly into electrical energy, they offer low emissions and high efficiencies. These advantages are of particular interest to remote power users, where grid connected power is unavailable, and most electrical power comes from diesel electric generators. Diesel fuel is the fuel of choice because it can be easily transported and stored in quantities large enough to supply energy for small communities for extended periods of time. This projected aimed to demonstrate the operation of a solid oxide fuel cell on diesel fuel, and to measure the resulting efficiency. Results from this project have been somewhat encouraging, with a laboratory breadboard integration of a small scale diesel reformer and a Solid Oxide Fuel Cell demonstrated in the first 18 months of the project. This initial demonstration was conducted at INEEL in the spring of 2005 using a small scale diesel reformer provided by SOFCo and a fuel cell provided by Acumentrics. However, attempts to integrate and automate the available technology have not proved successful as yet. This is due both to the lack of movement on the fuel processing side as well as the rather poor stack lifetimes exhibited by the fuel cells. Commercial product is still unavailable, and precommercial devices are both extremely expensive and require extensive field support.

  18. Evaluation of subsurface fracture geometry using fluid pressure response to solid earth tidal strain

    SciTech Connect

    Hanson, J.M.

    1984-09-01

    The nature of solid earth tidal strain and surface load deformation due to the influence of gravitational forces and barometric pressure loading are discussed. The pore pressure response to these types of deformation is investigated in detail, including the cases of a confined aquifer intersected by a well and a discrete fracture intersected by a well. The integration of the tidal response method with conventional pump tests in order to independently calculate the hydraulic parameters of the fracture-formation system is discussed. How advanced spectral analysis methods, coupled with correlation analysis can be used to extract the tidal response signals from the pressure record is shown. Uncertainties in the signals are estimated using various information-theoretic methods in order to place a confidence level at which we can safely assume that the measured signal is indeed of tidal origin. A detailed case study of the method carried out at the Raft River Geothermal Reservoir in Idaho is presented. All of the analyzed tidal data is presented and the results of the computed fracture orientation using the solid earth tidal strain approach are compared with the extensive field work carried out at Raft River over the past decade. The direction that future work in the continuing development of this technology should take is discussed, including: (1) the present need for an expanded data base for the confirmation of present tidal strain response models, and (2) improvement in response models.

  19. Thermal Plasma Spraying Applied on Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Soysal, D.; Arnold, J.; Szabo, P.; Henne, R.; Ansar, S. A.

    2013-06-01

    Solid oxide fuel cells (SOFCs), attractive for diverse applications in a broad range from small portable and auxiliary power units, up to central power systems, are conventionally produced by sintering methods. However, plasma spraying promises some advantages particularly for cells with metal support. In the present paper, research activities conducted in recent years at DLR as well as latest developments on plasma sprayed functional layers for SOFC as cathodes, electrolytes, and anodes are reported. Power densities of more than 800 mW/cm2 were achieved for plasma sprayed single cells of 12.56 cm2 size, and 300 mW/cm2, respectively, with a 250 W stack made of 10 cells. These values were attained at 0.7 V and 800 °C, with H2:N2 = 1:1 as fuel gas and air as oxidizing gas. Furthermore, continuous operation of more than 5000 h was attained with a plasma sprayed metal-supported SOFC stack which could also withstand more than 30 redox and thermal cycles.

  20. Ammonium nitrate as an oxidizer in solid composite propellants

    NASA Astrophysics Data System (ADS)

    Manelis, G. B.; Lempert, D. B.

    2009-09-01

    Despite the fact that ammonium nitrate (AN) has the highest hydrogen content and fairly high oxygen balance (compared to other oxidizers), its extremely low formation enthalpy and relatively low density makes it one of the worst power oxidizers in solid composite propellants (SCP). Nevertheless, AN has certain advantages - the combustion of the compositions containing AN is virtually safe, its combustion products are ecologically clean, it is very accessible and cheap, and also very thermostable (far more stable than ammonium dinitramide (ADN)). Besides, its low density stops being a disadvantage if the propellant has to be used in deep space and therefore, must be carried there with other rocket carriers. The low cost of AN may also become a serious advantage in the AN application even in lower stages of multistage space launchers as well as in one-stage space launchers with low mass fraction of the propellant. The main specific features relevant to the creation of AN-based SCPs with the optimal energetic characteristics are discussed. The use of metals and their hydrides and proper fuel-binders as well as the recent successes in phase stabilization of AN are described.

  1. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    SciTech Connect

    Liaw, B.Y.; Song, S.Y.

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  2. Solid oxide fuel cell having compound cross flow gas patterns

    DOEpatents

    Fraioli, Anthony V.

    1985-01-01

    A core construction for a fuel cell is disclosed having both parallel and cross flow passageways for the fuel and the oxidant gases. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte wall consists of cathode and anode materials sandwiching an electrolyte material. Each interconnect wall is formed as a sheet of inert support material having therein spaced small plugs of interconnect material, where cathode and anode materials are formed as layers on opposite sides of each sheet and are electrically connected together by the interconnect material plugs. Each interconnect wall in a wavy shape is connected along spaced generally parallel line-like contact areas between corresponding spaced pairs of generally parallel electrolyte walls, operable to define one tier of generally parallel flow passageways for the fuel and oxidant gases. Alternate tiers are arranged to have the passageways disposed normal to one another. Solid mechanical connection of the interconnect walls of adjacent tiers to the opposite sides of the common electrolyte wall therebetween is only at spaced point-like contact areas, 90 where the previously mentioned line-like contact areas cross one another.

  3. High-temperature seals for solid oxide fuel cells (SOFC)

    NASA Astrophysics Data System (ADS)

    Singh, Raj N.

    2006-08-01

    A functioning solid oxide fuel-cell (SOFC) may require all types of seals, such as metal-metal, metal-ceramic, and ceramic-ceramic. These seals must function at high temperatures between 600 and 900 °C and in the oxidizing and reducing environments of fuels and air. Among the different types of seals, the metal-metal seals can be readily fabricated using metal joining, soldering, and brazing techniques. However, metal-ceramic and ceramic-ceramic seals require significant research and development because the brittle nature of ceramics/glasses can lead to fracture and loss of seal integrity and functionality. Consequently, any seals involving ceramics/glasses also require significant attention and technology development for reliable SOFC operation. This paper is prepared to primarily address the needs and possible approaches for high-temperature seals for SOFC and seals fabricated using some of these approaches. A new concept of self-healing glass seals is proposed for making seals among material combinations with a significant expansion mismatches.

  4. Robust Joining Technology for Solid Oxide Fuel Cells Applications

    NASA Technical Reports Server (NTRS)

    Shpargel, Tarah P.; Needham, Robert J.; Singh, M.; Kung, S. C.

    2004-01-01

    Recently there has been a great deal of interest in research development and commercialization of solid oxide fuel cells (SOFCs). Joining and sealing are critical issues that will need to be addressed before SOFCs can truly perform as expected. Ceramics and metals can be difficult to join together, especially when the joint must withstand up to 900 C operating temperature of the SOFCs. The goal of the present study is to find the most suitable braze material for joining of yttria stabilized zirconia (YSZ) to stainless steel. A number of commercially available braze materials TiCuSil, TiCuNi, Copper-ABA, Gold-ABA and Gold-ABA-V have been evaluated. The oxidation behavior of the braze materials and steel substrates in air was also examined through thermogravimetric analysis. The microstructure and composition of the brazed regions have been examined by optical and scanning electron microscopy and eDS analysis. Effect of braze composition and processing conditions on the interfacial microstructure and composition of the joint regions will be presented.

  5. Integrating catalytic coal gasifiers with solid oxide fuel cells

    SciTech Connect

    Siefert, N.; Shamsi, A.; Shekhawat, D.; Berry, D.

    2010-01-01

    A review was conducted for coal gasification technologies that integrate with solid oxide fuel cells (SOFC) to achieve system efficiencies near 60% while capturing and sequestering >90% of the carbon dioxide [1-2]. The overall system efficiency can reach 60% when a) the coal gasifier produces a syngas with a methane composition of roughly 25% on a dry volume basis, b) the carbon dioxide is separated from the methane-rich synthesis gas, c) the methane-rich syngas is sent to a SOFC, and d) the off-gases from the SOFC are recycled back to coal gasifier. The thermodynamics of this process will be reviewed and compared to conventional processes in order to highlight where available work (i.e. exergy) is lost in entrained-flow, high-temperature gasification, and where exergy is lost in hydrogen oxidation within the SOFC. The main advantage of steam gasification of coal to methane and carbon dioxide is that the amount of exergy consumed in the gasifier is small compared to conventional, high temperature, oxygen-blown gasifiers. However, the goal of limiting the amount of exergy destruction in the gasifier has the effect of limiting the rates of chemical reactions. Thus, one of the main advantages of steam gasification leads to one of its main problems: slow reaction kinetics. While conventional entrained-flow, high-temperature gasifiers consume a sizable portion of the available work in the coal oxidation, the consumed exergy speeds up the rates of reactions. And while the rates of steam gasification reactions can be increased through the use of catalysts, only a few catalysts can meet cost requirements because there is often significant deactivation due to chemical reactions between the inorganic species in the coal and the catalyst. Previous research into increasing the kinetics of steam gasification will be reviewed. The goal of this paper is to highlight both the challenges and advantages of integrating catalytic coal gasifiers with SOFCs.

  6. New Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

    SciTech Connect

    Allan J. Jacobson

    2005-11-17

    Operation of SOFCs at intermediate temperatures (500-800 C) requires new combinations of electrolyte and electrode materials that will provide both rapid ion transport across the electrolyte and electrode--electrolyte interfaces and efficient electrocatalysis of the oxygen reduction and fuel oxidation reactions. This project concentrates on materials and issues associated with cathode performance that are known to become limiting factors as the operating temperature is reduced. The specific objectives of the proposed research are to develop cathode materials that meet the electrode performance targets of 1.0 W/cm{sup 2} at 0.7 V in combination with YSZ at 700 C and with GDC, LSGM or bismuth oxide based electrolytes at 600 C. The performance targets imply an area specific resistance of {approx}0.5 {Omega}cm{sup 2} for the total cell. The research strategy is to investigate both established classes of materials and new candidates as cathodes, to determine fundamental performance parameters such as bulk diffusion, surface reactivity and interfacial transfer, and to couple these parameters to performance in single cell tests. In this report, the oxygen exchange kinetics of a P2 composition are described in detail. The oxygen exchange kinetics of the oxygen deficient double perovskite LnBaCo{sub 2}O{sub 5.5+{delta}} (Ln=Pr and Nd) have been determined by electrical conductivity relaxation. The high electronic conductivity and rapid diffusion and surface exchange kinetics of PBCO suggest its application as cathode material in intermediate temperature solid oxide fuel cells.

  7. Evaluation of subsurface fracture geometry using fluid pressure response to solid earth tidal strain

    NASA Astrophysics Data System (ADS)

    Hanson, J. M.

    1984-09-01

    The nature of solid earth tidal strain and surface load deformation due to the influence of gravitational forces and barometric pressure loading are discussed. The pore pressure response to these types of deformation is investigated in detail, including the cases of a confined aquifer intersected by a well and a discrete fracture intersected by a well. The integration of the tidal response method with conventional pump tests in order to independently calculate the hydraulic parameters of the fracture formation system is discussed. How advanced spectral analysis methods, coupled with correlation analysis can be used to extract the tidal response signals from the pressure record is shown. Uncertainties in the signals are estimated using various information theoretic methods in order to place a confidence level at which we can safely assume that the measured signal is indeed of tidal origin. A detailed case study of the method carried out at the Raft River Geothermal Reservoir in Idaho is presented.

  8. A Review of Sealing Technologies Applicable to Solid Oxide Electrolysis Cells

    SciTech Connect

    Paul A. Lessing

    2007-05-01

    This article reviews designs and materials investigated for various seals in high temperature solid oxide fuel cell “stacks” and how they might be implemented in solid oxide electrolysis cells that decompose steam into hydrogen and oxygen. Materials include metals, glasses, glass–ceramics, cements, and composites. Sealing designs include rigid seals, compressive seals, and compliant seals.

  9. Solid oxide fuel cell with single material for electrodes and interconnect

    DOEpatents

    McPheeters, C.C.; Nelson, P.A.; Dees, D.W.

    1994-07-19

    A solid oxide fuel cell is described having a plurality of individual cells. A solid oxide fuel cell has an anode and a cathode with electrolyte disposed there between, and the anode, cathode and interconnect elements are comprised of substantially one material. 9 figs.

  10. 46 CFR 194.05-11 - Flammable solids and oxidizing materials-Detail requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 CFR parts 172, 173, and 176. ... 46 Shipping 7 2014-10-01 2014-10-01 false Flammable solids and oxidizing materials-Detail... and Marking § 194.05-11 Flammable solids and oxidizing materials—Detail requirements. (a)...

  11. 46 CFR 194.05-11 - Flammable solids and oxidizing materials-Detail requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 CFR parts 172, 173, and 176. ... 46 Shipping 7 2013-10-01 2013-10-01 false Flammable solids and oxidizing materials-Detail... and Marking § 194.05-11 Flammable solids and oxidizing materials—Detail requirements. (a)...

  12. 46 CFR 194.05-11 - Flammable solids and oxidizing materials-Detail requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 CFR parts 172, 173, and 176. ... 46 Shipping 7 2011-10-01 2011-10-01 false Flammable solids and oxidizing materials-Detail... and Marking § 194.05-11 Flammable solids and oxidizing materials—Detail requirements. (a)...

  13. 46 CFR 194.05-11 - Flammable solids and oxidizing materials-Detail requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 CFR parts 172, 173, and 176. ... 46 Shipping 7 2010-10-01 2010-10-01 false Flammable solids and oxidizing materials-Detail... and Marking § 194.05-11 Flammable solids and oxidizing materials—Detail requirements. (a)...

  14. 46 CFR 194.05-11 - Flammable solids and oxidizing materials-Detail requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 CFR parts 172, 173, and 176. ... 46 Shipping 7 2012-10-01 2012-10-01 false Flammable solids and oxidizing materials-Detail... and Marking § 194.05-11 Flammable solids and oxidizing materials—Detail requirements. (a)...

  15. Development of planar solid oxide fuel cells for power generation applications

    SciTech Connect

    Minh, N.Q.

    1996-04-01

    Planar solid oxide fuel cells (SOFCs) are presently being developed for a variety of electric power generation application. The planar design offers simple cell geometry, high power density, and multiple fabrication and gas manifolding options. Planar SOFC technology has received much attention recently, and significant progress has been made in this area. Recent effort at AlliedSignal has focused on the development of high-performance, lightweight planar SOFCs, having thin-electrolyte films, that can be operated efficiently at reduced temperatures (< 1000{degrees}C). The advantages of reduced-temperature operation include wider material choice (including use of metallic interconnects), expected longer cell life, reduced thermal stress, improved reliability, and reduced fuel cell cost. The key aspect in the development of thin-film SIFCs is to incorporate the thin electrolyte layer into the desired structure of cells in a manner that yields the required characteristics. AlliedSignal has developed a simple and cost-effective method based on tape calendering for the fabrication of thin-electrolyte SOFCs. Thin-electrolyte cells made by tape calendering have shown extraordinary performance, e.g., producing more than 500mW/cm{sup 2} at 700{degrees}C and 800mW/cm{sup 2} at 800{degrees}C with hydrogen as fuel and air is oxidant. thin-electrolyte single cells have been incorporated into a compliant metallic stack structure and operated at reduced and operated at reduced-temperature conditions.

  16. Probing molecular geometry of solids by nuclear magnetic resonance spin exchange at the n=0 rotational-resonance condition

    NASA Astrophysics Data System (ADS)

    Tekely, Piotr; Gardiennet, Carole; Potrzebowski, Marek J.; Sebald, Angelika; Reichert, Detlef; Luz, Zeev

    2002-05-01

    Exploration of the molecular geometry in rotating powder solids on the basis of magnetization exchange between spins with identical isotropic chemical shifts but differing chemical shielding tensor orientations is demonstrated experimentally. For this we take advantage of the potential of the ODESSA (one-dimensional exchange spectroscopy by sidebands alternation) experiment for the accurate measurement of spin exchange rate constants. We also report the observation of oscillatory behavior of the rotor-driven magnetization exchange at this so-called n=0 rotational-resonance condition which, in contrast to n=1,2,3,… rotational-resonance conditions, takes place at nearly arbitrary magic-angle spinning frequencies. The sensitivity of the longitudinal exchange decays to the relevant physical parameters of the spin system under conditions of rotor-driven and proton-driven magnetization exchange is discussed theoretically and demonstrated experimentally. Several 13C and 31P spin-exchange measurements have been performed on a series of model compounds covering a broad range of internuclear distances between carboxyl carbon atoms, and on a series of phosphorylated amino acids with different internuclear distances between phosphorus sites. The capacity of the ODESSA experiment for an unambiguous recognition of distinct internuclear distances is demonstrated. Potential applications of such measurements involve the exploration of intermolecular distances and the determination of the mutual orientation of neighboring molecular fragments in polycrystalline and noncrystalline solids.

  17. The 3SPACE digitizer: A new input device for solid geometry modeling

    NASA Technical Reports Server (NTRS)

    Scully, J.

    1984-01-01

    The 3SPACE Digitizer is a derivation of SPASYN, which is a patented magnetic transducing system offering an accurate method of calculating the location of one object relative to another. SPASYN uses low-frequency magnetic fields to measure both the position and orientation of its sensor relative to its transmitter. The 3SPACE Digitizer unit consists of a system's electronics unit, a model table, a stylus, and a keypad. In operation, the 3SPACE Digitizer determines the X, Y, Z coordinates of any point located on a low-conductive, three-dimensional model. This data, along with the orientation of the Digitizer's stylus, is immediately available for transmission to a host computer or graphics terminal. Digitization is effected by touching the point to be measured with the tip of a handheld stylus. The 3SPACE Digitizer presents new opportunities for interacting with computers in a large number of engineering and scientific applications. Developed from proven military technology, the 3SPACE Digitizer significantly simplifies three-dimensional digitization and overcomes many of the problems that once plagued such procedures. Its ability to digitize solid objects makes it a valuable new tool for computer-aided design and manufacturing.

  18. Solid-state thin-film supercapacitor with ruthenium oxide and solid electrolyte thin films

    NASA Astrophysics Data System (ADS)

    Yoon, Y. S.; Cho, W. I.; Lim, J. H.; Choi, D. J.

    Direct current reactive sputtering deposition of ruthenium oxide thin films (bottom and top electrodes) at 400°C are performed to produce a solid-state thin-film supercapacitor (TFSC). The supercapacitor has a cell structure of RuO 2/Li 2.94PO 2.37N 0.75 (Lipon)/RuO 2/Pt. Radio frequency, reactive sputtering deposition of an Li 2.94PO 2.37N 0.75 electrolyte film is performed on the bottom RuO 2 film at room temperature to separate the bottom and top RuO 2 electrodes electrically. The stoichiometry of the RuO 2 thin film is investigated by Rutherford back-scattering spectrometry (RBS). X-ray diffraction (XRD) shows that the as-deposited RuO 2 thin film is an amorphous phase. Scanning electron microscopy (SEM) measurements reveal that the RuO 2/Lipon/RuO 2 hetero-interfaces have no inter-diffusion problems. Charge-discharge measurements with constant current at room temperature clearly reveal typical supercapacitor behaviour for a RuO 2/Lipon/RuO 2/Pt cell structure. Since the electrolyte thin film has low ionic mobility, the capacity and cycle performance are inferior to those of a bulk type of supercapacitor. These results indicate that a high performance, TFSC can be fabricated by a solid electrolyte thin film with high ionic conductivity.

  19. Formulations for Stronger Solid Oxide Fuel-Cell Electrolytes

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Goldsby, John C.; Choi, Sung R.

    2004-01-01

    Tests have shown that modification of chemical compositions can increase the strengths and fracture toughnesses of solid oxide fuel-cell (SOFC) electrolytes. Heretofore, these solid electrolytes have been made of yttria-stabilized zirconia, which is highly conductive for oxygen ions at high temperatures, as needed for operation of fuel cells. Unfortunately yttria-stabilized zirconia has a high coefficient of thermal expansion, low resistance to thermal shock, low fracture toughness, and low mechanical strength. The lack of strength and toughness are especially problematic for fabrication of thin SOFC electrolyte membranes needed for contemplated aeronautical, automotive, and stationary power-generation applications. The modifications of chemical composition that lead to increased strength and fracture toughness consist in addition of alumina to the basic yttria-stabilized zirconia formulations. Techniques for processing of yttria-stabilized zirconia/alumina composites containing as much as 30 mole percent of alumina have been developed. The composite panels fabricated by these techniques have been found to be dense and free of cracks. The only material phases detected in these composites has been cubic zirconia and a alumina: this finding signifies that no undesired chemical reactions between the constituents occurred during processing at elevated temperatures. The flexural strengths and fracture toughnesses of the various zirconia-alumina composites were measured in air at room temperature as well as at a temperature of 1,000 C (a typical SOFC operating temperature). The measurements showed that both flexural strength and fracture toughness increased with increasing alumina content at both temperatures. In addition, the modulus of elasticity and the thermal conductivity were found to increase and the density to decrease with increasing alumina content. The oxygen-ion conductivity at 1,000 C was found to be unchanged by the addition of alumina.

  20. Materials System for Intermediate Temperature Solid Oxide Fuel Cell

    SciTech Connect

    Uday B. Pal; Srikanth Gopalan

    2006-01-12

    The objective of this work was to obtain a stable materials system for intermediate temperature solid oxide fuel cell (SOFC) capable of operating between 600-800 C with a power density greater than 0.2 W/cm{sup 2}. The solid electrolyte chosen for this system was La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3}, (LSGM). To select the right electrode materials from a group of possible candidate materials, AC complex impedance spectroscopy studies were conducted between 600-800 C on symmetrical cells that employed the LSGM electrolyte. Based on the results of the investigation, LSGM electrolyte supported SOFCs were fabricated with La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3}-La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} (LSCF-LSGM) composite cathode and Nickel-Ce{sub 0.6}La{sub 0.4}O{sub 3} (Ni-LDC) composite anode having a barrier layer of Ce{sub 0.6}La{sub 0.4}O{sub 3} (LDC) between the LSGM electrolyte and the Ni-LDC anode. Electrical performance and stability of these cells were determined and the electrode polarization behavior as a function of cell current was modeled between 600-800 C. The electrical performance of the anode-supported SOFC was simulated assuming an electrode polarization behavior identical to the LSGM-electrolyte-supported SOFC. The simulated electrical performance indicated that the selected material system would provide a stable cell capable of operating between 600-800 C with a power density between 0.2 to 1 W/cm{sup 2}.

  1. Filled glass composites for sealing of solid oxide fuel cells.

    SciTech Connect

    Tandon, Rajan; Widgeon, Scarlett Joyce; Garino, Terry J.; Brochu, Mathieu; Gauntt, Bryan D.; Corral, Erica L.; Loehman, Ronald E.

    2009-04-01

    Glasses filled with ceramic or metallic powders have been developed for use as seals for solid oxide fuel cells (SOFC's) as part of the U.S. Department of Energy's Solid State Energy Conversion Alliance (SECA) Program. The composites of glass (alkaline earth-alumina-borate) and powders ({approx}20 vol% of yttria-stabilized zirconia or silver) were shown to form seals with SOFC materials at or below 900 C. The type and amount of powder were adjusted to optimize thermal expansion to match the SOFC materials and viscosity. Wetting studies indicated good wetting was achieved on the micro-scale and reaction studies indicated that the degree of reaction between the filled glasses and SOFC materials, including spinel-coated 441 stainless steel, at 750 C is acceptable. A test rig was developed for measuring strengths of seals cycled between room temperature and typical SOFC operating temperatures. Our measurements showed that many of the 410 SS to 410 SS seals, made using silver-filled glass composites, were hermetic at 0.2 MPa (2 atm.) of pressure and that seals that leaked could be resealed by briefly heating them to 900 C. Seal strength measurements at elevated temperature (up to 950 C), measured using a second apparatus that we developed, indicated that seals maintained 0.02 MPa (0.2 atm.) overpressures for 30 min at 750 C with no leakage. Finally, the volatility of the borate component of sealing glasses under SOFC operational conditions was studied using weight loss measurements and found by extrapolation to be less than 5% for the projected SOFC lifetime.

  2. CFD Model of a Planar Solid Oxide Electrolysis Cell: Base Case and Variations

    SciTech Connect

    G. L. Hawkes; J. E. O'Brien; C. M. Stoots; J. S. Herring; R. W. Jones

    2007-07-01

    A three-dimensional computational fluid dynamics (CFD) model has been created to model high-temperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell, as it would exist in an electrolysis stack. Details of the model geometry are specific to a stack that was fabricated by Ceramatec, Inc. and tested at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with experimental results obtained from an actual ten-cell stack tested at INL. Mean per-cell area-specific-resistance (ASR) values decrease with increasing current density, consistent with experimental data. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, cathode and anode exchange current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicated the effects of heat transfer, reaction cooling/heating, and change in local gas composition. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.

  3. Solid oxidized fuel cells seals leakage setup and testing

    NASA Technical Reports Server (NTRS)

    Bastrzyk, Marta B.

    2004-01-01

    As the world s reserves of fossil fuels are depleted, the U.S. Government, as well as other countries and private industries, is researching solutions for obtaining power, answers that would be more efficient and environmentally friendly. For a long time engineers have been trying to obtain the benefits of clean electric power without heavy batteries or pollution-producing engines. While some of the inventions proved to be effective (i.e. solar panels or windmills) their applications are limited due to dependency on the energy source (i.e. sun or wind). Currently, as energy concerns increase, research is being carried out on the development of a Solid Oxide Fuel Cell (SOFC). The United States government is taking a proactive role in expanding the technology through the Solid State Energy Conversion Alliance (SECA) Program, which is coordinated by the Department of Energy. into an electrical energy. This occurs by the means of natural tendency of oxygen and hydrogen to chemically react. While controlling the process, it is possible to harvest the energy given off by the reaction. SOFCs use currently available fossil fuels and convert a variety of those fuels with very high efficiency (about 40% more efficient than modem thermal power plants). At the same time they are almost entirely nonpolluting and due to their size they can be placed in remote areas. The main fields where the application of the fuel cells appears to be the most useful for are stationary energy sources, transportation, and military applications. structure and materials must be resolved. All the components must be operational in harsh environments including temperatures reaching 800 C and cyclic thermal- mechanical loading. Under these conditions, the main concern is the requirement for hermetic seals to: (1) prevent mixing of the fuel and oxidant within the stack, (2) prevent parasitic leakage of the fuel from the stack, (3) prevent contamination of the anode by air leaking into the stack, (4

  4. Oxidation of encapsulated oil in tailor-made cellular solid.

    PubMed

    Rassis, D; Nussinovitch, A; Saguy, I S

    2000-05-01

    A cellular alginate solid containing oil was prepared by freeze-drying. The oil was incorporated in the matrix by emulsification in the pre-gel state. The alginate-oil gels were immersed in 60 degrees Brix sucrose solution for various periods, before freeze-drying. The extent of the collapse expressing the reduction in sample volume was affected by immersion duration and freeze-drying conditions. Sucrose diffusion during immersion followed an exponential pattern. Effective diffusivity calculated using nonlinear regression gave a value of 3.64 x 10(-)(10) m(2)/s. The effect of relative humidity on water content calculated on a dry basis excluding sucrose showed a significant increase in water content at 75% RH. Image analysis was utilized to quantify the area of the encapsulated oil droplets. The area of the droplets was divided into four subregions defined as (0.02-0.1) x 10(-)(12), (0. 1-1.0) x 10(-)(12), (1-10) x 10(-)(12), and (10-100) x 10(-)(12) m(2). A distribution resembling a Gaussian bell distribution with a maximum of 54% for the (1-10) x 10(-)(12) m(2) area range was found. The number of oil droplets was almost constant for the first three area regions, and then decreased markedly. Oxidation index was not effected by porosity at 0 and 22% RH. A 75% RH and porosity above a critical value of ca. 0.45 was found to increase oxidation significantly. Samples immersed for less than 5.5 h in sucrose solution were mechanically stronger after equilibration at 0 and 22% RH when compared to their counterpart equilibrated at 75% RH. Immersion for more than 24 h resulted in similar mechanical strength irrespective of the RH. PMID:10820103

  5. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    NASA Astrophysics Data System (ADS)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  6. Protactinium distribution in a fluoride melt in the presence of solid oxide phases

    SciTech Connect

    Alekseev, V.A.; Ziv, V.S.; Morozova, Z.E.

    1989-01-01

    Measurements have been made on protactinium distributions between molten lithium and sodium fluorides and solid lanthanum or zirconium oxides as affected by time, amount of solid, and amount of gas (air of argon) at 1023 K. Protactinium can be extracted quantitatively from LiF-NaF melts by the two oxides. It is found that all the regularities previously reported for actinoid distributions in halide liquids in the presence of oxides apply to protactinium.

  7. Lateral solid-phase epitaxy of oxide thin films on glass substrate seeded with oxide nanosheets.

    PubMed

    Taira, Kenji; Hirose, Yasushi; Nakao, Shoichiro; Yamada, Naoomi; Kogure, Toshihiro; Shibata, Tatsuo; Sasaki, Takayoshi; Hasegawa, Tetsuya

    2014-06-24

    We developed a technique to fabricate oxide thin films with uniaxially controlled crystallographic orientation and lateral size of more than micrometers on amorphous substrates. This technique is lateral solid-phase epitaxy, where epitaxial crystallization of amorphous precursor is seeded with ultrathin oxide nanosheets sparsely (≈10% coverage) deposited on the substrate. Transparent conducting Nb-doped anatase TiO2 thin films were fabricated on glass substrates by this technique. Perfect (001) orientation and large grains with lateral sizes up to 10 μm were confirmed by X-ray diffraction, atomic force microscopy, and electron beam backscattering diffraction measurements. As a consequence of these features, the obtained film exhibited excellent electrical transport properties comparable to those of epitaxial thin films on single-crystalline substrates. This technique is a versatile method for fabricating high-quality oxide thin films other than anatase TiO2 and would increase the possible applications of oxide-based thin film devices. PMID:24867286

  8. PRESSURIZED SOLID OXIDE FUEL CELL/GAS TURBINE POWER SYSTEM

    SciTech Connect

    W.L. Lundberg; G.A. Israelson; R.R. Moritz; S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann

    2000-02-01

    Power systems based on the simplest direct integration of a pressurized solid oxide fuel cell (SOFC) generator and a gas turbine (GT) are capable of converting natural gas fuel energy to electric power with efficiencies of approximately 60% (net AC/LHV), and more complex SOFC and gas turbine arrangements can be devised for achieving even higher efficiencies. The results of a project are discussed that focused on the development of a conceptual design for a pressurized SOFC/GT power system that was intended to generate 20 MWe with at least 70% efficiency. The power system operates baseloaded in a distributed-generation application. To achieve high efficiency, the system integrates an intercooled, recuperated, reheated gas turbine with two SOFC generator stages--one operating at high pressure, and generating power, as well as providing all heat needed by the high-pressure turbine, while the second SOFC generator operates at a lower pressure, generates power, and provides all heat for the low-pressure reheat turbine. The system cycle is described, major system components are sized, the system installed-cost is estimated, and the physical arrangement of system components is discussed. Estimates of system power output, efficiency, and emissions at the design point are also presented, and the system cost of electricity estimate is developed.

  9. Modeling Degradation in Solid Oxide Electrolysis Cells - Volume II

    SciTech Connect

    Manohar Motwani

    2011-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic non-equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential,, within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, non-equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  10. Internal reforming development for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, A. L.

    1987-02-01

    Internal reforming of natural gas within a solid oxide fuel cell (SOFC) should simplify the overall system design and make the SOFC an attractive means for producing electrical power. This program was undertaken to investigate the catalytic properties of nickel cermets, which are prime candidates for SOFC anodes. The initial task in this program was an extensive literature search for information on steam reforming of light hydrocarbons. The second task was to modify and calibrate the reactor systems that were used in the experimental kinetic studies. Two systems were used in this investigation; a continuously stirred tank reactor system (CSTR) and a plug flow reactor system (PFR). In the third task, 16 nickel-zirconia cermets were prepared using four procedures, tape casting, Westinghouse slurry, incorporation of performers, and granulation. The catalytic behavior of three cermets was determined in the fourth task. The reaction was first order with respect to methane and -1.25 for steam. Ethane and propane in the feed did not affect the methane conversion rate. The cermet has a higher initial tolerance for sulfur than standard nickel reforming catalysts. The final task was a mechanistic study of the steam reforming reaction on nickel and nickel-zirconia catalysts.