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Sample records for temperature solid oxide

  1. Intermediate Temperature Solid Oxide Fuel Cell Development

    Energy Technology Data Exchange (ETDEWEB)

    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

  2. Low temperature ozone oxidation of solid waste surrogates

    Science.gov (United States)

    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.

  3. Strategies for Lowering Solid Oxide Fuel Cells Operating Temperature

    Directory of Open Access Journals (Sweden)

    Albert Tarancón

    2009-11-01

    Full Text Available Lowering the operating temperature of solid oxide fuel cells (SOFCs to the intermediate range (500–700 ºC has become one of the main SOFC research goals. High operating temperatures put numerous requirements on materials selection and on secondary units, limiting the commercial development of SOFCs. The present review first focuses on the main effects of reducing the operating temperature in terms of materials stability, thermo-mechanical mismatch, thermal management and efficiency. After a brief survey of the state-of-the-art materials for SOFCs, attention is focused on emerging oxide-ionic conductors with high conductivity in the intermediate range of temperatures with an introductory section on materials technology for reducing the electrolyte thickness. Finally, recent advances in cathode materials based on layered mixed ionic-electronic conductors are highlighted because the decreasing temperature converts the cathode into the major source of electrical losses for the whole SOFC system. It is concluded that the introduction of alternative materials that would enable solid oxide fuel cells to operate in the intermediate range of temperatures would have a major impact on the commercialization of fuel cell technology.

  4. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    . On the other hand, low-temperature operation poses serious challenges to the electrode performance. Effective catalysts, redox stable electrodes with improved microstructures are the prime requisite for the development of efficient SOFC anodes. The performance of Nb-doped SrT iO3 (STN) ceramic anodes......An important issue that has limited the potential of Solid Oxide Fuel Cells (SOFCs) for portable applications is its high operating temperatures (800-1000 ºC). Lowering the operating temperature of SOFCs to 400-600 ºC enable a wider material selection, reduced degradation and increased lifetime...... at 400ºC. The potential of using WO3 ceramic as an alternative anode materials has been explored. The relatively high electrode polarization resistance obtained, 11 Ohm cm2 at 600 ºC, proved the inadequate catalytic activity of this system for hydrogen oxidation. At the end of this thesis...

  5. Lowering the temperature of solid oxide fuel cells.

    Science.gov (United States)

    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.

  6. Low temperature solid oxide electrolytes (LT-SOE): A review

    Science.gov (United States)

    Singh, B.; Ghosh, S.; Aich, S.; Roy, B.

    2017-01-01

    Low temperature solid oxide fuel cell (LT-SOFC) can be a source of power for vehicles, online grid, and at the same time reduce system cost, offer high reliability, and fast start-up. A huge amount of research work, as evident from the literature has been conducted for the enhancement of the ionic conductivity of LT electrolytes in the last few years. The basic conduction mechanisms, advantages and disadvantages of different LT oxide ion conducting electrolytes {BIMEVOX systems, bilayer systems including doped cerium oxide/stabilised bismuth oxide and YSZ/DCO}, mixed ion conducting electrolytes {doped cerium oxides/alkali metal carbonate composites}, and proton conducting electrolytes {doped and undoped BaCeO3, BaZrO3, etc.} are discussed here based on the recent research articles. Effect of various material aspects (composition, doping, layer thickness, etc.), fabrication methods (to achieve different microstructures and particle size), design related strategies (interlayer, sintering aid etc.), characterization temperature & environment on the conductivity of the electrolytes and performance of the fuel cells made from these electrolytes are shown in tabular form and discussed. The conductivity of the electrolytes and performance of the corresponding fuel cells are compared. Other applications of the electrolytes are mentioned. A few considerations regarding the future prospects are pointed.

  7. Degradation in Solid Oxide Cells During High Temperature Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Allan J. Jacobson

    2006-09-30

    the perovskite compositions that were being investigated at PNNL, in order to assess the relative importance of the intrinsic properties such as oxygen ion diffusion and surface exchange rates as predictors of performance in cell tests. We then used these measurements to select new materials for scaled up synthesis and performance evaluation in single cell tests. The results of the single cell tests than provided feedback to the materials synthesis and selection steps. In this summary, the following studies are reported: (1) Synthesis, characterization, and DC conductivity measurements of the P1 compositions La{sub 0.8}Sr{sub 0.2}FeO{sub 3-x} and La{sub 0.7}Sr{sub 0.3}FeO{sub 3-x} were completed. A combinational approach for preparing a range P1 (La,Sr)FeO{sub 3} compositions as thin films was investigated. Synthesis and heat treatment of amorphous SrFeO{sub 3-x} and LaFeO{sub 3-x} films prepared by pulsed laser deposition are described. (2) Oxygen transport properties of K1 compositions La{sub x}Pr{sub 2-x}NiO{sub 4+d} (x =2.0, 1.9, 1.2, 1.0 and 0) measured by electrical conductivity relaxation are presented in this report. Area specific resistances determined by ac impedance measurements for La{sub 2}NiO{sub 4+{delta}} and Pr{sub 2}NiO{sub 4+{delta}} on CGO are encouraging and suggest that further optimization of the electrode microstructure will enable the target to be reached. (3) The oxygen exchange kinetics of the oxygen deficient double perovskite LnBaCo{sub 2}O{sub 5.5+{delta}} (Ln=Pr and Nd) were 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. The first complete cell measurements were performed on Ni/CGO/CGO/PBCO/CGO cells. (4) The oxygen exchange kinetics of highly epitaxial thin films of PrBaCo{sub 2}O{sub 5.5+{delta}} (PBCO) has been determined by electrical conductivity

  10. Electrochemical investigation of mixed metal oxide nanocomposite electrode for low temperature solid oxide fuel cell

    Science.gov (United States)

    Abbas, Ghazanfar; Raza, Rizwan; Ashfaq Ahmad, M.; Ajmal Khan, M.; Jafar Hussain, M.; Ahmad, Mukhtar; Aziz, Hammad; Ahmad, Imran; Batool, Rida; Altaf, Faizah; Zhu, Bin

    2017-10-01

    Zinc-based nanostructured nickel (Ni) free metal oxide electrode material Zn0.60/Cu0.20Mn0.20 oxide (CMZO) was synthesized by solid state reaction and investigated for low temperature solid oxide fuel cell (LTSOFC) applications. The crystal structure and surface morphology of the synthesized electrode material were examined by XRD and SEM techniques respectively. The particle size of ZnO phase estimated by Scherer’s equation was 31.50 nm. The maximum electrical conductivity was found to be 12.567 S/cm and 5.846 S/cm in hydrogen and air atmosphere, respectively at 600∘C. The activation energy of the CMZO material was also calculated from the DC conductivity data using Arrhenius plots and it was found to be 0.060 and 0.075 eV in hydrogen and air atmosphere, respectively. The CMZO electrode-based fuel cell was tested using carbonated samarium doped ceria composite (NSDC) electrolyte. The three layers 13 mm in diameter and 1 mm thickness of the symmetric fuel cell were fabricated by dry pressing. The maximum power density of 728.86 mW/cm2 was measured at 550∘C.

  11. HIGH-TEMPERATURE TUBULAR SOLID OXIDE FUEL CELL GENERATOR DEVELOPMENT

    Energy Technology Data Exchange (ETDEWEB)

    S.E. Veyo

    1998-09-01

    During the Westinghouse/USDOE Cooperative Agreement period of November 1, 1990 through November 30, 1997, the Westinghouse solid oxide fuel cell has evolved from a 16 mm diameter, 50 cm length cell with a peak power of 1.27 watts/cm to the 22 mm diameter, 150 cm length dimensions of today's commercial prototype cell with a peak power of 1.40 watts/cm. Accompanying the increase in size and power density was the elimination of an expensive EVD step in the manufacturing process. Demonstrated performance of Westinghouse's tubular SOFC includes a lifetime cell test which ran for a period in excess of 69,000 hours, and a fully integrated 25 kWe-class system field test which operated for over 13,000 hours at 90% availability with less than 2% performance degradation over the entire period. Concluding the agreement period, a 100 kW SOFC system successfully passed its factory acceptance test in October 1997 and was delivered in November to its demonstration site in Westervoort, The Netherlands.

  12. Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Nicholas, Jason Dale [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for Ce0.9Gd0.1O1.95, and to evaluate whether they could be used to produce dense, constrained Ce0.9Gd0.1O1.95 films at temperatures below 1000 C. To find the optimal sintering aid, Ce0.9Gd0.1O1.95 was doped with a variety of elements, of which lithium was found to be the most effective. Dilatometric studies indicated that by doping CGO with 3mol% lithium nitrate, it was possible to sinter pellets to a relative density of 98.5% at 800 C--a full one hundred degrees below the previous low temperature sintering record for CGO. Further, it was also found that a sintering aid's effectiveness could be explained in terms of its size, charge and high temperature mobility. A closer examination of lithium doped Ce0.9Gd0.1O1.95 indicated that lithium affects sintering by producing a Li2O-Gd2O3-CeO2 liquid at the CGO grain boundaries. Due to this liquid phase sintering, it was possible to produce dense, crack-free constrained films of CGO at the record low temperature of 950 C using cheap, colloidal spray deposition processes. This is the first time dense constrained CGO films have been produced below 1000 C and could help commercialize metal supported ceria based solid oxide fuel cells.

  13. Study on Zinc Oxide-Based Electrolytes in Low-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Xia, Chen; Qiao, Zheng; Feng, Chu; Kim, Jung-Sik; Wang, Baoyuan; Zhu, Bin

    2017-12-28

    Semiconducting-ionic conductors have been recently described as excellent electrolyte membranes for low-temperature operation solid oxide fuel cells (LT-SOFCs). In the present work, two new functional materials based on zinc oxide (ZnO)-a legacy material in semiconductors but exceptionally novel to solid state ionics-are developed as membranes in SOFCs for the first time. The proposed ZnO and ZnO-LCP (La/Pr doped CeO₂) electrolytes are respectively sandwiched between two Ni 0.8 Co 0.15 Al 0.05 Li-oxide (NCAL) electrodes to construct fuel cell devices. The assembled ZnO fuel cell demonstrates encouraging power outputs of 158-482 mW cm -2 and high open circuit voltages (OCVs) of 1-1.06 V at 450-550 °C, while the ZnO-LCP cell delivers significantly enhanced performance with maximum power density of 864 mW cm -2 and OCV of 1.07 V at 550 °C. The conductive properties of the materials are investigated. As a consequence, the ZnO electrolyte and ZnO-LCP composite exhibit extraordinary ionic conductivities of 0.09 and 0.156 S cm -1 at 550 °C, respectively, and the proton conductive behavior of ZnO is verified. Furthermore, performance enhancement of the ZnO-LCP cell is studied by electrochemical impedance spectroscopy (EIS), which is found to be as a result of the significantly reduced grain boundary and electrode polarization resistances. These findings indicate that ZnO is a highly promising alternative semiconducting-ionic membrane to replace the electrolyte materials for advanced LT-SOFCs, which in turn provides a new strategic pathway for the future development of electrolytes.

  14. CHALLENGES IN GENERATING HYDROGEN BY HIGH TEMPERATURE ELECTROLYSIS USING SOLID OXIDE CELLS

    Energy Technology Data Exchange (ETDEWEB)

    M. S. Sohal; J. E. O' Brien; C. M. Stoots; M. G. McKellar; J. S. Herring; E. A. Harvego

    2008-03-01

    Idaho National Laboratory’s (INL) high temperature electrolysis research to generate hydrogen using solid oxide electrolysis cells is presented in this paper. The research results reported here have been obtained in a laboratory-scale apparatus. These results and common scale-up issues also indicate that for the technology to be successful in a large industrial setting, several technical, economical, and manufacturing issues have to be resolved. Some of the issues related to solid oxide cells are stack design and performance optimization, identification and evaluation of cell performance degradation parameters and processes, integrity and reliability of the solid oxide electrolysis (SOEC) stacks, life-time prediction and extension of the SOEC stack, and cost reduction and economic manufacturing of the SOEC stacks. Besides the solid oxide cells, balance of the hydrogen generating plant also needs significant development. These issues are process and ohmic heat source needed for maintaining the reaction temperature (~830°C), high temperature heat exchangers and recuperators, equal distribution of the reactants into each cell, system analysis of hydrogen and associated energy generating plant, and cost optimization. An economic analysis of this plant was performed using the standardized H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program, and using realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a cost of $3.23/kg of hydrogen assuming an internal rate of return of 10%. These issues need interdisciplinary research effort of federal laboratories, solid oxide cell manufacturers, hydrogen consumers, and other such stakeholders. This paper discusses research and development accomplished by INL on such issues and highlights associated challenges that need to

  15. High-temperature temporal stability of selected oxidizers as solids and in aqueous solutions. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Pellenbarg, R.E.; Smiroldo

    1986-08-08

    Various potential decontamination agents were examined as solids and in aqueous solutions for long-term stability at high temperatures. The following oxidizers were assayed iodometrically: the hypochlorite salts of calcium and lithium, sodium dischloroisocyanurate (PACE) and the preoxygen compounds sodium perborate, sodium peroxydisulfate, sodium percarbonate, and magnesium monoperoxyphthalate (H-48). The inorganic peroxide solids and the solid sodium dischloroisoyanurate were stable at 80 C, while the organic peroxide solids and the hypochlorite salts deteriorated markedly within 72 hours. In freshwater solutions of 0.01 N or less, the inorganic hypochlorite and peroxide salts decomposed slowly at 60 c. Conversely, the sodium dischloroisocyanurate, magnesium monoperoxyphthalate, and sodium percarbonate solutions exhibited near complete decomposition in 24 hours.

  16. Microwave assisted sintering of gadolinium doped barium cerate electrolyte for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Arumugam Senthil, E-mail: senthu.ramp@gmail.com [Department of Physics, PSG College of Technology, Coimbatore, 641 004, Tamilnadu (India); Balaji, Ramamoorthy [Department of Physics, PSG College of Technology, Coimbatore, 641 004, Tamilnadu (India); Jayakumar, Srinivasalu [Department of Physics, PSG Institute of Technology and Applied Research, Coimbatore, 641 062, Tamilnadu (India); Pradeep, Chandran [Department of Physics, Indian Institute of Technology, Madras, 600 036, Tamilnadu (India)

    2016-10-01

    In Solid Oxide Fuel Cell (SOFC), electrolyte plays a vital role to increase the energy conversion efficiency. The main hurdle of such electrolyte in fuel cell is its higher operating temperature (1000 °C) which results in design limitation and higher fabrication cost. In order to reduce the operating temperature of SOFC, a suitable electrolyte has been prepared through co-precipitation method followed by microwave sintering of solid ceramic. The calcination temperature for the as-prepared powder was identified using Differential Scanning Calorimetry. The crystal structure of the sample was found to exhibit its orthorhombic perovskite structure. The particle size was determined using High-Resolution Transmission Electron Microscope with uniform in shape and size, match with XRD results and confirmed from structural analysis. Thus, the sample prepared via co-precipitation method and the solid ceramic sintered through microwave can be a promising electrolyte for fuel cells operated at intermediate temperature. - Highlights: • To synthesis the composite electrolyte by chemical method and sinter using microwave. • To reduce the operating temperature of electrolyte for high ionic conductivity in SOFC's. • To study the phase purity and to develop nanocomposite at reduced temperature.

  17. Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Raza, Rizwan, E-mail: razahussaini786@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044 (Sweden); Ahmed, Akhlaq; Akram, Nadeem; Saleem, Muhammad; Niaz Akhtar, Majid; Ajmal Khan, M.; Abbas, Ghazanfar; Alvi, Farah; Yasir Rafique, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Sherazi, Tauqir A. [Department of Chemistry, COMSATS Institute of Information Technology, Abbotabad 22060 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) center, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); Mohsin, Munazza [Department of Physics, Lahore College for Women University, Lahore, 54000 (Pakistan); Javed, Muhammad Sufyan [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Zhu, Bin, E-mail: binzhu@kth.se, E-mail: zhubin@hubu.edu.cn [Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044 (Sweden); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science/Faculty of Computer and Information, Hubei University, Wuhan, Hubei 430062 (China)

    2015-11-02

    In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O{sup −2} (oxygen ions) and H{sup +} (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport number of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm{sup 2}, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.

  18. Temporal stability of solid oxidizers at high temperature and humidity. Memorandum report

    Energy Technology Data Exchange (ETDEWEB)

    Pellenbarg, R.E.; Dotson, D.A.

    1985-09-30

    Chemical Warfare/Biological Warfare (CW/BW) decontamination operations may rely on aqueous solutions prepared from stored solid oxidizers. Needed are data defining the shipboard storage stability of candidate oxidizers. Therefore, the stability of a series of potential decontaminants has been examined at high temperature (90 + C) and humidity (95 + % R.H.). The loss of oxidizing capacity in aliquots of the oxidizers was followed with time by iodometric titration. Calcium hypochlorite lost over 99% of its oxidizing capacity in less than two days, whereas lithium hypochlorite retained one-third oxidizing capacity for approximately twenty days. Sodium perborate, and sodium persulfate were very hygroscopic and unstable with time. H-48 decomposed in approximately two days, while sodium isocyanurate lost about 80% of its oxidizing capacity in two weeks. The data presented documents severe stability problems of one sort or another with all the materials tested, although overall the sodium isocyanurate appeared to be the more stable candidate undr extreme conditions. In any case, packaging and storage considerations are shown to be important for any potential decontaminant to be stored under environmentally severe conditions.

  19. High temperature solid oxide regenerative fuel cell for solar photovoltaic energy storage

    Science.gov (United States)

    Bents, David J.

    1987-01-01

    A hydrogen-oxygen regenerative fuel cell energy storage system based on high temperature solid oxide fuel cell technology is discussed which has application to darkside energy storage for solar photovoltaics. The forward and reverse operating cycles are described, and heat flow, mass, and energy balance data are presented to characterize the system's performance and the variation of performance with changing reactant storage pressure. The present system weighs less than nickel hydrogen battery systems after 0.7 darkside operation, and it maintains a specific weight advantage over radioisotope generators for discharge periods up to 72 hours.

  20. Transient deformational properties of high temperature alloys used in solid oxide fuel cell stacks

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kwok, Kawai; Frandsen, Henrik Lund

    2017-01-01

    Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... transients in operation including temporary shut downs. These stresses are highly affected by the transient creep behavior of metallic components in the SOFC stack. This study investigates whether a variation of the so-called Chaboche's unified power law together with isotropic hardening can represent...... to describe the high temperature inelastic deformational behaviors of Crofer 22 APU used for metallic interconnects in SOFC stacks....

  1. Materials and Components for Low Temperature Solid Oxide Fuel Cells – an Overview

    Directory of Open Access Journals (Sweden)

    D. Radhika

    2013-06-01

    Full Text Available This article summarizes the recent advancements made in the area of materials and components for low temperature solid oxide fuel cells (LT-SOFCs. LT-SOFC is a new trend in SOFCtechnology since high temperature SOFC puts very high demands on the materials and too expensive to match marketability. The current status of the electrolyte and electrode materials used in SOFCs, their specific features and the need for utilizing them for LT-SOFC are presented precisely in this review article. The section on electrolytes gives an overview of zirconia, lanthanum gallate and ceria based materials. Also, this review article explains the application of different anode, cathode and interconnect materials used for SOFC systems. SOFC can result in better performance with the application of liquid fuels such methanol and ethanol. As a whole, this review article discusses the novel materials suitable for operation of SOFC systems especially for low temperature operation.

  2. Nanofiber-based composite cathodes for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Ahn, Minwoo; Lee, Jongseo; Lee, Wonyoung

    2017-06-01

    We demonstrate the Sm0.5Sr0.5CoO3-δ (SSC) nanofiber-based composite cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs), showing a cathode area-specific resistance (ASR) value of 0.024 Ωcm2 at 650 °C. The hollow and porous SSC nanofiber layer, fabricated by electrospinning, is sintered at low temperatures to preserve the high specific surface area for facile oxygen surface exchange reactions. The low sintering temperature is enabled by additional SSC powder layer, providing sufficient adhesion between the electrolyte and the nanofiber layer. Our results can provide a design guideline to fully utilize the nanostructured electrodes by engineering the structural properties of the surface and the interface, and hence high-performance IT-SOFCs can be achieved by structural modification with conventional materials.

  3. Structural, morphological, and electrical properties of doped ceria as a solid electrolyte for intermediate-temperature solid oxide fuel cells

    KAUST Repository

    Stojmenović, M.

    2015-03-11

    The solid solutions of CeO2 with one or more rare-earth oxides among Yb2O3, Sm2O3, and Gd2O3 are synthesized by either modified glycine nitrate procedure (MGNP) or self-propagating reaction at room temperature (SPRT). The overall mole fraction of rare-earth oxide dopants was x = 0.2. The characterization was committed by XRPD, TEM, BET, and Raman Spectroscopy methods. According to XRPD and Raman spectroscopy, the obtained products presented the single-phase solid solutions with basic fluorite-type CeO2 structure, regardless on the number and the concentration of dopants. Both XRPD and TEM analysis evidenced the nanometer particle dimensions. The defect model was applied to calculate lattice parameters of single-, co-, and multi-doped solids. The sintering of the sample nanopowders was performed at 1550 °C, in air atmosphere. The sintered samples were characterized by XRPD, SEM, and complex impedance methods. The sintering did not affect the concentration ratios of the constituents. The highest conductivity at 700 °C amounting to 2.14 × 10−2 and 1.92 × 10−2 Ω−1 cm−1 was measured for the sample Ce0.8Sm0.08Gd0.12O2−δ, synthesized by SPRT and MGNP methods, respectively. The corresponding activation energies of conductivity, measured in the temperature range 500–700 °C, amounted to 0.24 and 0.23 eV.

  4. Atomistic study of ternary oxides as high-temperature solid lubricants

    Science.gov (United States)

    Gao, Hongyu

    Friction and wear are important tribological phenomena tightly associated with the performance of tribological components/systems such as bearings and cutting machines. In the process of contact and sliding, friction and wear lead to energy loss, and high friction and wear typically result in shortened service lifetime. To reduce friction and wear, solid lubricants are generally used under conditions where traditional liquid lubricants cannot be applied. However, it is challenging to maintain the functionality of those materials when the working environment becomes severe. For instance, at elevated temperatures (i.e., above 400 °C), most traditional solid lubricants, such as MoS2 and graphite, will easily oxidize or lose lubricity due to irreversible chemical changes. For such conditions, it is necessary to identify materials that can remain thermally stable as well as lubricious over a wide range of temperatures. Among the currently available high-temperature solid lubricants, Ag-based ternary metal oxides have recently drawn attention due to their low friction and ability to resist oxidation. A recent experimental study showed that the Ag-Ta-O ternary exhibited an extremely low coefficient of friction (0.06) at 750 °C. To fully uncover the lubricious nature of this material as a high-temperature solid lubricant, a series of tribological investigations were carried out based on one promising candidate - silver tantalate (AgTaO3). The study was then extended to alternative materials, Cu-Ta-O ternaries, to accommodate a variety of application requirements. We aimed to understand, at an atomic level, the effects of physical and chemical properties on the thermal, mechanical and tribological behavior of these materials at high temperatures. Furthermore, we investigated potassium chloride films on a clean iron surface as a representative boundary lubricating system in a nonextreme environment. This investigation complemented the study of Ag/Cu-Ta-O and enhanced the

  5. High-Temperature Chemistry in Solid Oxide Fuel Cells: In Situ Optical Studies.

    Science.gov (United States)

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

    2012-10-18

    Solid oxide fuels cells (SOFCs) are promising devices for versatile and efficient power generation with fuel flexibility, but their viability is contingent upon understanding chemical and material processes to improve their performance and durability. Newly developed in situ optical methods provide new insight into how carbon deposition varies with different hydrocarbon and alcohol fuels and depends on operating conditions. Some findings, such as heavier hydrocarbon fuels forming more carbon than lighter fuels, are expected, but other discoveries are surprising. For example, methanol shows a greater tendency to form carbon deposits than methane at temperatures below 800 °C, and kinetically controlled steam reforming with ethanol at high temperatures (∼800 °C) is less detrimental to SOFC performance than operating the device with dry methanol as the fuel. In situ optical techniques will continue to provide the chemical information and mechanistic insight that is critical for SOFCs to become a viable energy conversion technology.

  6. Interaction mechanisms between slurry coatings and solid oxide fuel cell interconnect alloys during high temperature oxidation

    DEFF Research Database (Denmark)

    Persson, Åsa Helen; Mikkelsen, L.; Hendriksen, P.V.

    2012-01-01

    oxidation rate constant was reduced with 50–90% of that for uncoated alloy. One coating consisting of MnCo2O4 did not significantly affect the oxidation rate of the alloy, and just as for uncoated samples break-away oxidation occurred for MnCo2O4 coated samples. The interaction mechanisms between...

  7. Shape-Dependent Activity of Ceria for Hydrogen Electro-Oxidation in Reduced-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Tong, Xiaofeng; Luo, Ting; Meng, Xie; Wu, Hao; Li, Junliang; Liu, Xuejiao; Ji, Xiaona; Wang, Jianqiang; Chen, Chusheng; Zhan, Zhongliang

    2015-11-04

    Single crystalline ceria nanooctahedra, nanocubes, and nanorods are hydrothermally synthesized, colloidally impregnated into the porous La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) scaffolds, and electrochemically evaluated as the anode catalysts for reduced temperature solid oxide fuel cells (SOFCs). Well-defined surface terminations are confirmed by the high-resolution transmission electron microscopy--(111) for nanooctahedra, (100) for nanocubes, and both (110) and (100) for nanorods. Temperature-programmed reduction in H2 shows the highest reducibility for nanorods, followed sequentially by nanocubes and nanooctahedra. Measurements of the anode polarization resistances and the fuel cell power densities reveal different orders of activity of ceria nanocrystals at high and low temperatures for hydrogen electro-oxidation, i.e., nanorods > nanocubes > nanooctahedra at T ≤ 450 °C and nanooctahedra > nanorods > nanocubes at T ≥ 500 °C. Such shape-dependent activities of these ceria nanocrystals have been correlated to their difference in the local structure distortions and thus in the reducibility. These findings will open up a new strategy for design of advanced catalysts for reduced-temperature SOFCs by elaborately engineering the shape of nanocrystals and thus selectively exposing the crystal facets. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Anaerobic model for high-solids or high-temperature digestion - additional pathway of acetate oxidation.

    Science.gov (United States)

    Wett, B; Takács, I; Batstone, D; Wilson, C; Murthy, S

    2014-01-01

    Current anaerobic digestion models cannot properly simulate processes that are operated under high solids concentrations or high temperatures. A modification to existing models has been implemented by adding important missing degradation pathways, to accommodate these systems without artificially recalibrating the model parameters. Specifically, we implemented the alternate acetate oxidizing mechanism that is more tolerant to ammonia than the standard aceticlastic pathway. Inhibition values were estimated and an empirical function has been used to apply ammonia inhibition. The model also relates metabolic activity to un-ionised species such as undissociated acetic acid as substrate (although not obligatory for all organisms) and unionised ammonia as inhibitor. The model relies on an equilibrium chemistry module (e.g. including the phosphate buffer), resulting in more accurate pH predictions, which is crucial for proper modeling of CO2 and NH3 stripping. Calibration results from three case-studies modeling thermal hydrolysis and subsequent digestion of sludge are presented.

  9. Low Temperature, High Energy Density Micro Thin Film Solid Oxide Fuel Cell Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new type of solid oxide fuel cell based on thin film technology and ultra-thin electrolyte is being proposed to develop to realize major reductions in fuel cell...

  10. Aggravated test of Intermediate temperature solid oxide fuel cells fed with tar-contaminated syngas

    Science.gov (United States)

    Pumiglia, Davide; Vaccaro, Simone; Masi, Andrea; McPhail, Stephen J.; Falconieri, Mauro; Gagliardi, Serena; Della Seta, Livia; Carlini, Maurizio

    2017-02-01

    In the present work, the effects of a tar-containing simulated syngas on an IT-SOFC (Intermediate Temperature Solid Oxide Fuel Cell) are evaluated. Performance and degradation rate of a planar anode-supported cell, operating under a simulated syngas obtained from steam-enriched air gasification of biomass, have been studied. The simulated syngas was contaminated using toluene as a model tar. Polarization curves and electrochemical impedance spectroscopy have been carried out under different toluene concentrations. A cell was then operated under a constant current density on a long run. EIS measurements were made during the operation to analyze the degradation, and the voltage evolution of the cell was compared to that obtained from another identical cell operated in clean syngas for 1000 h under similar conditions. A deep post-mortem characterization was performed by means of XRD measurements, Raman spectroscopy and SEM/EDS analysis. Results show that the presence of tar dramatically reduces the electrochemical performances of the cell, affecting both activation and mass transport processes. Post-mortem analysis shows the formation of carbon deposits, oxidation of Ni to NiO, segregation of ZrO2 from the YSZ phase, particle coarsening and enhanced fragility of the anode structure, in good agreement with what suggested from the electrochemical results.

  11. A micro-nano porous oxide hybrid for efficient oxygen reduction in reduced-temperature solid oxide fuel cells

    Science.gov (United States)

    Da Han; Liu, Xuejiao; Zeng, Fanrong; Qian, Jiqin; Wu, Tianzhi; Zhan, Zhongliang

    2012-01-01

    Tremendous efforts to develop high-efficiency reduced-temperature (≤ 600°C) solid oxide fuel cells are motivated by their potentials for reduced materials cost, less engineering challenge, and better performance durability. A key obstacle to such fuel cells arises from sluggish oxygen reduction reaction kinetics on the cathodes. Here we reported that an oxide hybrid, featuring a nanoporous Sm0.5Sr0.5CoO3−δ (SSC) catalyst coating bonded onto the internal surface of a high-porosity La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM) backbone, exhibited superior catalytic activity for oxygen reduction reactions and thereby yielded low interfacial resistances in air, e.g., 0.021 Ω cm2 at 650°C and 0.043 Ω cm2 at 600°C. We further demonstrated that such a micro-nano porous hybrid, adopted as the cathode in a thin LSGM electrolyte fuel cell, produced impressive power densities of 2.02 W cm−2 at 650°C and 1.46 W cm−2 at 600°C when operated on humidified hydrogen fuel and air oxidant. PMID:22708057

  12. Advanced Manufacturing of Intermediate Temperature, Direct Methane Oxidation Membrane Electrode Assemblies for Durable Solid Oxide Fuel Cell Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation builds on the successes of the Phase I program by integrating our direct oxidation membrane electrode assembly (MEA) into a monolithic solid...

  13. Advanced manufacturing of intermediate temperature, direct methane oxidation membrane electrode assemblies for durable solid oxide fuel cell Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ITN proposes to create an innovative anode supported membrane electrode assembly (MEA) for solid oxide fuel cells (SOFCs) that is capable of long-term operation at...

  14. Mesoporous NiO-samaria doped ceria for low-temperature solid oxide fuel cells.

    Science.gov (United States)

    Kim, Jin-Yeop; Kim, Ji Hyeon; Choi, Hyung Wook; Kim, Kyung Hwan; Park, Sang Joon

    2014-08-01

    In order to prepare anode material for low-temperature solid oxide fuel cells (SOFCs), the mesoporous NiO-SDC was synthesized using a cationic surfactant (cetyltrimethyl-ammonium bromide; CTAB) for obtaining wide triple-phase boundary (TPB). In addition, Ni-SDC anode-supported SOFC single cells with YSZ electrolyte and LSM cathode were fabricated and the performance of single cells was evaluated at 600 °C. The microstructure of NiO-SDC was characterized by XRD, EDX, SEM, and BET, and the results showed that the mesoporous NiO-SDC with 10 nm pores could be obtained. It was found that the surface area and the electrical performance were strongly influenced by the Ni content in Ni-SDC cermets. After calcined at 600 °C, the surface area of NiO-SDC was between 90-117 m2/g at 35-45 Ni wt%, which was sufficiently high for providing large TPB in SOFC anode. The optimum Ni content for cell performance was around 45 wt% and the corresponding MPD was 0.36 W/cm2. Indeed, the mesoporous NiO-SDC cermet may be of interest for use as an anode for low-temperature SOFCs.

  15. Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    Science.gov (United States)

    Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru; Akbay, Taner; Hosoi, Kei

    The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 °C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 °C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system.

  16. High temperature solid oxide fuel cell integrated with novel allothermal biomass gasification. Part II: Exergy analysis

    Science.gov (United States)

    Panopoulos, K. D.; Fryda, L.; Karl, J.; Poulou, S.; Kakaras, E.

    Biomass gasification derived gas is a renewable fuel, which can be used for SOFC applications. This work investigates the integration of a near atmospheric solid oxide fuel cell (SOFC) with a novel allothermal biomass steam gasification process into a combined heat and power (CHP) system of less than MW e range. Heat for steam gasification is supplied from SOFC depleted fuel in a fluidised bed (FB) combustor via high temperature sodium heat pipes. In the first paper, the integrated system was modelled in Aspen Plus™ and critical aspects for its feasibility were identified. The aim of this second part is the evaluation of the integrated system in exergy terms. Satisfying allothermal gasification heat demand is illustrated by examining each sub-process involved separately as well as combined. For a relatively low STBR = 0.6, the SOFC fuel utilisation for which the system operates under optimum conditions is U f = 0.7. Above that value additional biomass has to be used in the FB combustor to provide gasification heat with considerable exergy losses. For SOFC operation at current density 2500 A m -2, the system uses 90 kg h -1 biomass, operates with electrical exergetic efficiency 32% producing 140 kW e, while the combined electrical and thermal exergetic efficiency is 35%.

  17. High-temperature electrolysis of synthetic seawater using solid oxide electrolyzer cells

    Science.gov (United States)

    Lim, Chee Kuan; Liu, Qinglin; Zhou, Juan; Sun, Qiang; Chan, Siew Hwa

    2017-02-01

    A Ni-YSZ/YSZ/LSCF-GDC solid oxide electrolyzer cell (SOEC) is used to investigate the effects of seawater electrolysis for hydrogen production through electrolyzing steam produced from simulated seawater bath. Steam electrolysis using an SOEC with its fuel electrode contaminated by sea salt is also investigated. Steam produced from seawater is found to be free of contaminants, which are present in the seawater. Similar electrochemical performance is observed from the polarization curves and impedance spectra when using steam produced from pure water and seawater. Their short-term degradation rates are similar, which are registered at 15% 1000 h-1 for both cases. For the case of direct sea salt contamination in an SOEC's fuel electrode, both the uncontaminated and contaminated cells exhibit rather similar performance as observed from the polarization curves and impedance spectra. The difference in ASR values from the polarization curves and impedance spectra between the uncontaminated and contaminated cell are all within a 10% range. Rather similar short-term degradation rates of 15% 1000 h-1 and 16% 1000 h-1 are recorded for the uncontaminated and contaminated cells, respectively. Post-mortem analysis shows that the sea salt impregnated into the cell has been vaporized at a typical SOEC operating temperature of 800 °C over the period of operation.

  18. Novel Electrode Materials for Low-Temperature Solid-Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Shaowu Zha; Meilin Liu

    2005-03-23

    Composites electrodes consisting of silver and bismuth vanadates exhibit remarkable catalytic activity for oxygen reduction at 500-550 C and greatly reduce the cathode-electrolyte (doped ceria) resistances of low temperature SOFCs, down to about 0.53 {omega}cm{sup 2} at 500 C and 0.21 {omega}cm{sup 2} at 550 C. The observed power densities of 231, 332, and 443 mWcm-2 at 500, 525 and 550 C, respectively, make it possible to operate SOFCs at temperatures about 500 C. Fuel cell performance depends strongly on the anode microstructure, which is determined by the anode compositions and fabrication conditions. Four types of anodes with two kinds of NiO and GDC powders were investigated. By carefully adjusting the anode microstructure, the GDC electrolyte/anode interfacial polarization resistances reduced dramatically. The interfacial resistance at 600 C decreased from 1.61 {omega} cm{sup 2} for the anodes prepared using commercially available powders to 0.06 {omega} cm{sup 2} for those prepared using powders derived from a glycine-nitrate process. Although steam reforming or partial oxidation is effective in avoiding carbon deposition of hydrocarbon fuels, it increases the operating cost and reduces the energy efficiency. Anode-supported SOFCs with an electrolyte of 20 {micro}m-thick Gd-doped ceria (GDC) were fabricated by co-pressing. A catalyst (1 %wt Pt dispersed on porous Gd-doped ceria) for pre-reforming of propane was developed with relatively low steam to carbon (S/C) ratio ({approx}0.5), coupled with direct utilization of the reformate in low-temperature SOFCs. Propane was converted to smaller molecules during pre-reforming, including H{sub 2}, CH{sub 4}, CO, and CO{sub 2}. A peak power density of 247 mW/cm{sup 2} was observed when pre-reformed propane was directly fed to an SOFC operated at 600 C. No carbon deposition was observed in the fuel cell for a continuous operation of 10 hours at 600 C. The ability of producing vastly different microstructures and

  19. Advances in medium and high temperature solid oxide fuel cell technology

    CERN Document Server

    Salvatore, Aricò

    2017-01-01

    In this book well-known experts highlight cutting-edge research priorities and discuss the state of the art in the field of solid oxide fuel cells giving an update on specific subjects such as protonic conductors, interconnects, electrocatalytic and catalytic processes and modelling approaches. Fundamentals and advances in this field are illustrated to help young researchers address issues in the characterization of materials and in the analysis of processes, not often tackled in scholarly books.

  20. Thermal effects of planar high temperature heat pipes in solid oxide cell stacks operated with internal methane reforming

    Science.gov (United States)

    Dillig, Marius; Plankenbühler, Thomas; Karl, Jürgen

    2018-01-01

    The presented paper contributes to developing a new thermal control approach for solid oxide cell (SOC) stacks and systems. Integrating planar liquid metal heat pipes to the interconnector structure of the stacks targets a reduction of internal temperature gradients and an enhanced heat extraction from the stack. This work applies 3-D CFD-modelling to discuss the thermal effects of integrated heat pipes in solid oxide cell stacks, in order to evaluate the possible benefits in terms of temperature gradient reduction and heat removal as well as the resulting benefits for stacks and systems. The stack model set-up is described and its functioning is validated with experimental results from thermal short stack measurements with integrated heat pipe interconnectors. The simulation results are discussed with respect to the possible benefits for full-scale stacks of different cell size, in particular regarding internal heat recycling and the beneficial reduction of air ratios.

  1. First Principles Studies of Perovskites for Intermediate Temperature Solid Oxide Fuel Cell Cathodes

    KAUST Repository

    Salawu, Omotayo Akande

    2017-05-15

    Fundamental advances in cathode materials are key to lowering the operating temperature of solid oxide fuel cells (SOFCs). Detailed understanding of the structural, electronic and defect formation characteristics are essential for rational design of cathode materials. In this thesis we employ first principles methods to study La(Mn/Co)O3 and LnBaCo2O5+δ (Ln = Pr, Gd; δ = 0.5, 1) as cathode for SOFCs. Specifically, factors affecting the O vacancy formation and migration are investigated. We demonstrate that for LaMnO3 the anisotropy effects often neglected at high operating temperatures become relevant when the temperature is lowered. We show that this fact has consequences for the material properties and can be further enhanced by strain and Sr doping. Tensile strain promotes both the O vacancy formation and migration in pristine and Sr doped LaMnO3, while Sr doping enhances the O vacancy formation but not the migration. The effect of A-site hole doping (Mg2+, Ca2+ or Ba2+) on the electronic and magnetic properties as well as the O vacancy formation and migration in LaCoO3 are studied. All three dopants are found to facilitate O vacancy formation. Substitution of La3+ with Ba2+/Mg2+ yields the lowest O vacancy formation energy for low/intermediate spin Co, implying that not only the structure, but also the spin state of Co is a key parameter. Only for low spin Co the ionic radius is correlated with the O migration barrier. Enhanced migration for intermediate spin Co is ascribed to the availability of additional space at the transition state. For LnBaCo2O5+δ we compare the O vacancy formation in GdBaCo2O5.5 (Pmmm symmetry) and GdBaCo2O6 (P4/mmm symmetry), and the influence of Sr doping. The O vacancy formation energy is demonstrated to be smaller in the already O deficient compound. This relation is maintained under Sr doping. It turns out that Sr doping can be utilized to significantly enhance the O vacancy formation in both compounds. The observed trends are

  2. High throughput thermal conductivity of high temperature solid phases: The case of oxide and fluoride perovskites

    CERN Document Server

    van Roekeghem, Ambroise; Oses, Corey; Curtarolo, Stefano; Mingo, Natalio

    2016-01-01

    Using finite-temperature phonon calculations and machine-learning methods, we calculate the mechanical stability of about 400 semiconducting oxides and fluorides with cubic perovskite structures at 0 K, 300 K and 1000 K. We find 92 mechanically stable compounds at high temperatures -- including 36 not mentioned in the literature so far -- for which we calculate the thermal conductivity. We demonstrate that the thermal conductivity is generally smaller in fluorides than in oxides, largely due to a lower ionic charge, and describe simple structural descriptors that are correlated with its magnitude. Furthermore, we show that the thermal conductivities of most cubic perovskites decrease more slowly than the usual $T^{-1}$ behavior. Within this set, we also screen for materials exhibiting negative thermal expansion. Finally, we describe a strategy to accelerate the discovery of mechanically stable compounds at high temperatures.

  3. Solid Oxide Electrolyser Cell

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard

    Solid oxide fuel cells (SOFCs) produced at Risø National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 °C and a cell voltage of 1.48V the current density was -3.6A/cm2 with app. 30% H2 + 70% H2O in the inlet...... it is possible to achieve a production price of 0.7 US$/kg H2 with an electricity price of 1.3 US¢/kWh. The cell voltage was measured as function of time. In test ofabout two month of duration a long-term degradation was observed. At 850 °C, -0.5 A/cm2 with 50 vol% H2 the degradation rate was app. 20 mV/1000h...

  4. Influence of temperature and atmosphere on the strength and elastic modulus of solid oxide fuel cell anode supports

    DEFF Research Database (Denmark)

    Ni, De Wei; Charlas, Benoit; Kwok, Kawai

    2016-01-01

    Solid Oxide Fuel Cells are subjected to significant stresses during production and operation. The various stress-generating conditions impose strength requirements on the cell components, and thus the mechanical properties of the critical load bearing materials at relevant operational conditions...... need to be characterized to ensure reliable operation. In this study, the effect of reduction temperature on microstructural stability, high temperature strength and elastic modulus of Ni-YSZ anode supports were investigated. The statistical distribution of strength was determined from a large number...... of samples (∼30) at each condition to ensure high statistical validity. It is revealed that the microstructure and mechanical properties of the Ni-YSZ strongly depend on the reduction temperature. Further studies were conducted to investigate the temperature dependence of the strength and elastic modulus...

  5. Technology data for high temperature solid oxide electrolyser cells, alkali and PEM electrolysers

    DEFF Research Database (Denmark)

    Mathiesen, Brian vad; Ridjan, Iva; Connolly, David

    , by either using it directly in vehicles or indirectly via the production of synthetic fuels. Electrolysers are necessary to convert electricity to hydrogen and so they will have an essential role in the future smart energy system. However, at present there is a lot of uncertainty in relation to the current...... and forecasted development of electrolysers. The aim in this report is to reduce this uncertainty by gathering and aligning current knowledge in relation to the technical and economic potential of electrolysers. The results highlight existing and forecasted costs and efficiencies for alkaline, polymer...... electrolyte membrane (PEM), and solid oxide (SOEC) electrolysers between 2012 and 2050. These inputs can be usedfor analysing energy systems that include electrolysers....

  6. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    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.

  7. Exergy Analysis of an Intermediate Temperature Solid Oxide Fuel Cell-Gas Turbine Hybrid System Fed with Ethanol

    Directory of Open Access Journals (Sweden)

    Fotini Tzorbatzoglou

    2012-10-01

    Full Text Available In the present work, an ethanol fed Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT system has been parametrically analyzed in terms of exergy and compared with a single SOFC system. The solid oxide fuel cell was fed with hydrogen produced from ethanol steam reforming. The hydrogen utilization factor values were kept between 0.7 and 1. The SOFC’s Current-Volt performance was considered in the range of 0.1–3 A/cm2 at 0.9–0.3 V, respectively, and at the intermediate operating temperatures of 550 and 600 °C, respectively. The curves used represent experimental results obtained from the available bibliography. Results indicated that for low current density values the single SOFC system prevails over the SOFC-GT hybrid system in terms of exergy efficiency, while at higher current density values the latter is more efficient. It was found that as the value of the utilization factor increases the SOFC system becomes more efficient than the SOFC-GT system over a wider range of current density values. It was also revealed that at high current density values the increase of SOFC operation temperature leads in both cases to higher system efficiency values.

  8. Technology data for high temperature solid oxide electrolyser cells, alkali and PEM electrolysers

    Energy Technology Data Exchange (ETDEWEB)

    Vad Mathiesen, B.; Ridjan, I.; Connolly, D.; Pagh Nielsen, M. [Aalborg Univ., Aalborg (Denmark); Vang Hendriksen, P.; Bjerg Mogensen, M.; Hoejgaard Jensen, S.; Dalgaard Ebbesen, S. [Technical Univ. of Denmark. DTU Energy Conversion, DTU Risoe Campus, Roskilde (Denmark)

    2013-08-15

    The transition to 100% renewable energy systems will require a more integrated energy system. Connecting the electricity sector to transport is one of the major challenges in this transition, especially for long-distance and heavy-duty transport. Hydrogen is one potential solution to this challenge, by either using it directly in vehicles or indirectly via the production of synthetic fuels. Electrolysers are necessary to convert electricity to hydrogen and so they will have an essential role in the future smart energy system. However, at present there is a lot of uncertainty in relation to the current and forecasted development of electrolysers. The aim in this report is to reduce this uncertainty by gathering and aligning current knowledge in relation to the technical and economic potential of electrolysers. The results highlight existing and forecasted costs and efficiencies for alkaline, polymer electrolyte membrane (PEM), and solid oxide (SOEC) electrolysers between 2012 and 2050. These inputs can be used for analysing energy systems that include electrolysers. (Author)

  9. Solid Oxide Fuel Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The solid oxide fuel cell comprising a metallic support material, an active anode layer consisting of a good hydrocarbon cracking catalyst, an electrolyte layer, an active cathode layer, and a transition layer consisting of preferably a mixture of LSM and a ferrite to the cathode current collector...

  10. Model predictive control of the solid oxide fuel cell stack temperature with models based on experimental data

    Science.gov (United States)

    Pohjoranta, Antti; Halinen, Matias; Pennanen, Jari; Kiviaho, Jari

    2015-03-01

    Generalized predictive control (GPC) is applied to control the maximum temperature in a solid oxide fuel cell (SOFC) stack and the temperature difference over the stack. GPC is a model predictive control method and the models utilized in this work are ARX-type (autoregressive with extra input), multiple input-multiple output, polynomial models that were identified from experimental data obtained from experiments with a complete SOFC system. The proposed control is evaluated by simulation with various input-output combinations, with and without constraints. A comparison with conventional proportional-integral-derivative (PID) control is also made. It is shown that if only the stack maximum temperature is controlled, a standard PID controller can be used to obtain output performance comparable to that obtained with the significantly more complex model predictive controller. However, in order to control the temperature difference over the stack, both the stack minimum and the maximum temperature need to be controlled and this cannot be done with a single PID controller. In such a case the model predictive controller provides a feasible and effective solution.

  11. High-temperature, Knudsen cell-mass spectroscopic studies on lanthanum oxide/uranium dioxide solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sunder, S.; McEachern, R.; LeBlanc, J.C

    2001-07-01

    Knudsen cell-mass spectroscopic experiments were carried out with lanthanum oxide/uranium oxide solid solutions (1%, 2% and 5% (metal at.% basis)) to assess the volatilization characteristics of rare earths present in irradiated nuclear fuel. The oxidation state of each sample used was conditioned to the 'uranium dioxide stage' by heating in the Knudsen cell under an atmosphere of 10% C0{sub 2} in CO. The mass spectra were analyzed to obtain the vapour pressures of the lanthanum and uranium species. It was found that the vapour pressure of lanthanum oxide follows Henry's law, i.e., its value is directly proportional to its concentration in the solid phase. Also, the vapour pressure of lanthanum oxide over the solid solution, after correction for its concentration in the solid phase, is similar to that of uranium dioxide. (author)

  12. LOW-TEMPERATURE, ANODE-SUPPORTED HIGH POWER DENSITY SOLID OXIDE FUEL CELLS WITH NANOSTRUCTURED ELECTRODES

    Energy Technology Data Exchange (ETDEWEB)

    Professor Anil V. Virkar

    2003-05-23

    This report summarizes the work done during the entire project period, between October 1, 1999 and March 31, 2003, which includes a six-month no-cost extension. During the project, eight research papers have, either been, published, accepted for publication, or submitted for publication. In addition, several presentations have been made in technical meetings and workshops. The project also has provided support for four graduate students working towards advanced degrees. The principal technical objective of the project was to analyze the role of electrode microstructure on solid oxide fuel cell performance. Prior theoretical work conducted in our laboratory demonstrated that the particle size of composite electrodes has a profound effect on cell performance; the finer the particle size, the lower the activation polarization, the better the performance. The composite cathodes examined consisted of electronically conducting perovskites such as Sr-doped LaMnO{sub 3} (LSM) or Sr-doped LaCoO{sub 3} (LSC), which is also a mixed conductor, as the electrocatalyst, and yttria-stabilized zirconia (YSZ) or rare earth oxide doped CeO{sub 2} as the ionic conductor. The composite anodes examined were mixtures of Ni and YSZ. A procedure was developed for the synthesis of nanosize YSZ by molecular decomposition, in which unwanted species were removed by leaching, leaving behind nanosize YSZ. Anode-supported cells were made using the as-synthesized powders, or using commercially acquired powders. The electrolyte was usually a thin ({approx}10 microns), dense layer of YSZ, supported on a thick ({approx}1 mm), porous Ni + YSZ anode. The cathode was a porous mixture of electrocatalyst and an ionic conductor. Most of the cell testing was done at 800 C with hydrogen as fuel and air as the oxidant. Maximum power densities as high as 1.8 W/cm{sup 2} were demonstrated. Polarization behavior of the cells was theoretically analyzed. A limited amount of cell testing was done using liquid

  13. Synthesis of quinoxaline 1,4-di-n-oxide derivatives on solid support using room temperature and microwave-assisted solvent-free procedures

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Caro, Lilia C.; Sanchez-Sanchez, Mario; Bocanegra-Garcia, Virgilio; Rivera, Gildardo [Universidad Autonoma de Tamaulipas, Reynosa (Mexico). Dept. de Farmacia y Quimica Medicinal; Monge, Antonio [Universidad de Navarra, Pamplona (Spain). Centro de Investigacion en Farmacobiologia Aplicada. Unidad de Investigacion y Desarrollo de Medicamentos

    2011-07-01

    We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield. (author)

  14. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...

  15. High temperature solid oxide fuel cell integrated with novel allothermal biomass gasification. Part I: Modelling and feasibility study

    Science.gov (United States)

    Panopoulos, K. D.; Fryda, L. E.; Karl, J.; Poulou, S.; Kakaras, E.

    Biomass gasification derived fuel gas is a renewable fuel that can be used by high temperature fuel cells. In this two-part work an attempt is made to investigate the integration of a near atmospheric pressure solid oxide fuel cell (SOFC) with a novel allothermal biomass steam gasification process into a combined heat and power (CHP) system of less than MW e nominal output range. Heat for steam gasification is supplied from SOFC depleted fuel into a fluidised bed combustor via high temperature sodium heat pipes. The integrated system model was built in Aspen Plus™ simulation software and is described in detail. Part I investigates the feasibility and critical aspects of the system based on modelling results. A low gasification steam to biomass ratio (STBR = 0.6) is used to avoid excess heat demands and to allow effective H 2S high temperature removal. Water vapour is added prior to the anode to avoid carbon deposition. The SOFC off gases adequately provide gasification heat when fuel utilisation factors are electrical efficiency is estimated at 36% while thermal efficiency at 14%. An exergy analysis is presented in Part II.

  16. Record-low sintering-temperature (600 °C) of solid-oxide fuel cell electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Dasari, Hari Prasad, E-mail: energyhari@nitk.edu.in [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Chemical Engineering Department, National Institute of Technology Karnataka, Mangalore 575025, Karnataka (India); Ahn, Kiyong; Park, Sun-Young; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Lee, Jong-Ho, E-mail: jongho@kist.re.kr [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2016-07-05

    One of the major problems arising with Solid-Oxide Fuel Cell (SOFC) electrolyte is conventional sintering which requires a very high temperature (>1300 °C) to fully density the electrolyte material. In the present study, the sintering temperature of SOFC electrolyte is drastically decreased down to 600 °C. Combinational effects of particle size reduction, liquid-phase sintering mechanism and microwave sintering resulted in achieving full density in such a record-low sintering temperature. Gadolinium doped Ceria (GDC) nano-particles are synthesized by co-precipitation method, Lithium (Li), as an additional dopant, is used as liquid-phase sintering aid. Microwave sintering of this electrolyte material resulted in decreasing the sintering temperature to 600 °C. Micrographs obtained from Scanning/Transmission Electron Microscopy (SEM/TEM) clearly pointed a drastic growth in grain-size of Li-GDC sample (∼150 nm) than compared to GDC sample (<30 nm) showing the significance of Li addition. The sintered Li-GDC samples displayed an ionic conductivity of ∼1.00 × 10{sup −2} S cm{sup −1} at 600 °C in air and from the conductivity plots the activation energy is found to be 0.53 eV. - Highlights: • Sintering temperature is drastically decreased to 600 °C. • Key factors: Particle size reduction, liquid-phase and microwave sintering. • Nano-Li-GDC sample has ionic conductivity of ∼1.00 × 10{sup −2} S cm{sup −1} at 600 °C in air.

  17. Effects of temperature and pressure on the performance of a solid oxide fuel cell running on steam reformate of kerosene

    Energy Technology Data Exchange (ETDEWEB)

    Chick, Lawrence A.; Marina, Olga A.; Coyle, Christopher A.; Thomsen, Edwin C.

    2013-08-15

    A button solid oxide fuel cell with a La0.6Sr0.4Co0.2Fe0.8O3 cathode and a nickel-YSZ anode was tested over a range of temperatures from 650 to 800°C and a range of pressures from 101 to 724 kPa. The fuel was simulated steam-reformed kerosene and the oxidant was air. The observed increases in open circuit voltages (OCV) were accurately predicted by the Nernst equation. Kinetics also increased, although the power boost due to kinetics was about two thirds as large as the boost due to OCV. The total power boost in going from 101 to 724 kPa at 750°C and 0.8 volts was 66%. Impedance spectroscopy demonstrated a significant decrease in electrodic losses at elevated pressures. Complex impedance spectra were dominated by a combination of low frequency processes that decreased markedly with increasing pressure. A composite of high-frequency processes also decreased with pressure, but to a lesser extent. An empirical algorithm that accurately predicts the increased fuel cell performance at elevated pressures was developed for our results and was also suitable for some, but not all, data reported in the literature.

  18. Optimizing solid oxide fuel cell cathode processing route for intermediate temperature operation

    DEFF Research Database (Denmark)

    Ortiz-Vitoriano, N.; Bernuy-Lopez, Carlos; Ruiz de Larramendi, I.

    2013-01-01

    (∼600°C) and electrode sintering (∼800°C) of LCFN electrodes, making them a cheaper alternative to conventional SOFC cathodes. An electrode polarization resistance as low as 0.10Ωcm2 at 800°C is reported, as determined by impedance spectroscopy studies of symmetrical cells sintered at a range...... of temperatures (800-1000°C). Scanning Electron Microscopy (SEM) studies revealed porous electrode microstructures, even when sintered at a temperature of just 800°C. The competitive performance of the electrodes sintered at low temperatures, combined with the low raw material cost, make these electrodes...

  19. Electrochemical characterization on SDC/Na2CO3 nanocomposite electrolyte for low temperature solid oxide fuel cells.

    Science.gov (United States)

    Gao, Zhan; Raza, Rizwan; Zhu, Bin; Mao, Zongqiang

    2011-06-01

    Our previous work has demonstrated that novel core-shell SDC/Na2CO3 nanocomposite electrolyte possesses great potential for the development of low temperature (300-600 degrees C) solid oxide fuel cells. This work further characterizes the nanocomposite SDC/Na2CO3 electrochemical properties and conduction mechanism. The microstructure of the nanocomposite sintered at different temperatures was analyzed through scanning electron microscope (SEM) and X-ray diffraction (XRD). The electrical and electrochemical properties were studied. Significant conductivity enhancement was observed in the H2 atmosphere compared with that of air atmosphere. The ratiocination of proton conduction rather than electronic conduction has been proposed consequently based on the observation of fuel cell performance. The fuel cell performance with peak power density of 375 mW cm(-2) at 550 degrees C has been achieved. A.C. impedance for the fuel cell under open circuit voltage (OCV) conditions illustrates the electrode polarization process is predominant in rate determination.

  20. Bimetallic Nickel/Ruthenium Catalysts Synthesized by Atomic Layer Deposition for Low-Temperature Direct Methanol Solid Oxide Fuel Cells.

    Science.gov (United States)

    Jeong, Heonjae; Kim, Jun Woo; Park, Joonsuk; An, Jihwan; Lee, Tonghun; Prinz, Fritz B; Shim, Joon Hyung

    2016-11-09

    Nickel and ruthenium bimetallic catalysts were heterogeneously synthesized via atomic layer deposition (ALD) for use as the anode of direct methanol solid oxide fuel cells (DMSOFCs) operating in a low-temperature range. The presence of highly dispersed ALD Ru islands over a porous Ni mesh was confirmed, and the Ni/ALD Ru anode microstructure was observed. Fuel cell tests were conducted using Ni-only and Ni/ALD Ru anodes with approximately 350 μm thick gadolinium-doped ceria electrolytes and platinum cathodes. The performance of fuel cells was assessed using pure methanol at operating temperatures of 300-400 °C. Micromorphological changes of the anode after cell operation were investigated, and the content of adsorbed carbon on the anode side of the operated samples was measured. The difference in the maximum power density between samples utilizing Ni/ALD Ru and Pt/ALD Ru, the latter being the best catalyst for direct methanol fuel cells, was observed to be less than 7% at 300 °C and 30% at 350 °C. The improved electrochemical activity of the Ni/ALD Ru anode compared to that of the Ni-only anode, along with the reduction of the number of catalytically active sites due to agglomeration of Ni and carbon formation on the Ni surface as compared to Pt, explains this decent performance.

  1. A Brief Description of High Temperature Solid Oxide Fuel Cell’s Operation, Materials, Design, Fabrication Technologies and Performance

    Directory of Open Access Journals (Sweden)

    Muneeb Irshad

    2016-03-01

    Full Text Available Today’s world needs highly efficient systems that can fulfill the growing demand for energy. One of the promising solutions is the fuel cell. Solid oxide fuel cell (SOFC is considered by many developed countries as an alternative solution of energy in near future. A lot of efforts have been made during last decade to make it commercial by reducing its cost and increasing its durability. Different materials, designs and fabrication technologies have been developed and tested to make it more cost effective and stable. This article is focused on the advancements made in the field of high temperature SOFC. High temperature SOFC does not need any precious catalyst for its operation, unlike in other types of fuel cell. Different conventional and innovative materials have been discussed along with properties and effects on the performance of SOFC’s components (electrolyte anode, cathode, interconnect and sealing materials. Advancements made in the field of cell and stack design are also explored along with hurdles coming in their fabrication and performance. This article also gives an overview of methods required for the fabrication of different components of SOFC. The flexibility of SOFC in terms fuel has also been discussed. Performance of the SOFC with varying combination of electrolyte, anode, cathode and fuel is also described in this article.

  2. Solid oxide electrolyser cell

    Energy Technology Data Exchange (ETDEWEB)

    Hoejgaard Jensen, S.

    2006-12-15

    Solid oxide fuel cells (SOFCs) produced at Riso National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 deg. C and a cell voltage of 1.48V the current density was -3.6 A/cm{sup 2} with app. 30% H{sub 2} + 70% H{sub 2}O in the inlet gas and a H{sub 2}O utilization of app. 40%. The tested SOECs were also used for CO{sub 2} electrolysis. Economy studies of CO and H2 production show that especially H{sub 2} production can be competitive in areas with cheap electricity. Assuming the above described initial performance and a lifetime of 10 years it is possible to achieve a production price of 0.7 US dollar/kg H{sub 2} with an electricity price of 1.3 US cent/kWh. The cell voltage was measured as function of time. In test of about two month of duration a long-term degradation was observed. At 850 deg. C, -0.5 A/cm{sup 2} with 50 vol% H{sub 2} the degradation rate was app. 20 mV/1000h. It was shown that the degradation happens at Ni/YSZ-electrode. The long term degradation is probably caused by coarsening of the Ni-particles. After onset of electrolysis operation a transient passivation/reactivation phenomena with duration of several days was observed. It was shown that the phenomenon is attributed to the SiO{sub 2} contamination at the Ni/YSZ electrode-electrolyte interface. The SiO{sub 2} arises from the albite glass sealing (NaAlSi{sub 3}O{sub 8}) that surrounds the electrode. Si may enter the Ni/YSZ electrode via the reaction Si(OH){sub 4}(g) {r_reversible} SiO{sub 2}(l)+H{sub 2}O(g). At the active sites of the Ni/YSZ electrode steam is reduced via the reaction H{sub 2}O - 2e {yields} H{sub 2}+O{sup 2-} . This shifts the equilibrium of the first reaction to form SiO{sub 2}(l) at the active sites. After a certain time the sealing crystallizes and the SiO{sub 2}(l) evaporates from the active sites and the cell reactivates. The passivation is shown to relate to a build up of a

  3. In-situ study of the gas-phase composition and temperature of an intermediate-temperature solid oxide fuel cell anode surface fed by reformate natural gas

    Science.gov (United States)

    Santoni, F.; Silva Mosqueda, D. M.; Pumiglia, D.; Viceconti, E.; Conti, B.; Boigues Muñoz, C.; Bosio, B.; Ulgiati, S.; McPhail, S. J.

    2017-12-01

    An innovative experimental setup is used for in-depth and in-operando characterization of solid oxide fuel cell anodic processes. This work focuses on the heterogeneous reactions taking place on a 121 cm2 anode-supported cell (ASC) running with a H2, CH4, CO2, CO and steam gas mixture as a fuel, using an operating temperature of 923 K. The results have been obtained by analyzing the gas composition and temperature profiles along the anode surface in different conditions: open circuit voltage (OCV) and under two different current densities, 165 mA cm-2 and 330 mA cm-2, corresponding to 27% and 54% of fuel utilization, respectively. The gas composition and temperature analysis results are consistent, allowing to monitor the evolution of the principal chemical and electrochemical reactions along the anode surface. A possible competition between CO2 and H2O in methane internal reforming is shown under OCV condition and low current density values, leading to two different types of methane reforming: Steam Reforming and Dry Reforming. Under a current load of 40 A, the dominance of exothermic reactions leads to a more marked increase of temperature in the portion of the cell close to the inlet revealing that current density is not uniform along the anode surface.

  4. Facile synthesis of PbTiO3 truncated octahedra via solid-state reaction and their application in low-temperature CO oxidation by loading Pt nanoparticles

    KAUST Repository

    Yin, Simin

    2014-01-01

    Perovskite PbTiO3 (PTO) nanocrystals with a truncated octahedral morphology have been prepared by a facile solid-state reaction. Pt nanoparticles preferentially nucleated on the {111} facet of PTO nanocrystals exhibit a remarkable low-temperature catalytic activity towards CO oxidation from a temperature as low as 30 °C and achieve 100% conversion at ∼50 °C. © 2014 the Partner Organisations.

  5. Solid Oxide Fuel Cells

    Science.gov (United States)

    Brown, Jack T.

    Solid oxide fuel cells offer the potential for high efficiency, low cost electric power plants for many applications. The fuel cell generator Itself is an all solid state reactor operating at about 1000°C, which produces direct current electricity from the conversion of the energy in gaseous fuel by an electrochemical reaction with the oxygen in air. System studies have shown 50-60 percent efficiency can be obtained in multi-megawatt all electric power plants in which the high quality exhaust heat is used to produce electricity In a bottoming cycle. Alternatively the exhaust heat can be used in Industrial and commercial co-generation systems for space cooling or raising high pressure steam. Space based and military applications for electric power plants have been proposed with high power per unit weight and volume designs which use hydrogen fuel and pure oxygen. Truly significant accomplishments have been made in the 1980's in the technological development of the special materials and processes for producing them for the various cell designs and in the conception of device designs. These advancements were due to the fundamental work of the several decades earlier. In 1986 through 1988 experimental test units in the several hundred to several thousand watt sizes have been designed, fabricated, shipped, and tested for thousands of hours by user organizations in the United States and Japan. The extent of the commercial market for Solid Oxide fuel cells for various applications, vis-a-vis alternate electrical generation options, will depend on what system capital cost can be achieved.

  6. Inkjet-Printed Porous Silver Thin Film as a Cathode for a Low-Temperature Solid Oxide Fuel Cell.

    Science.gov (United States)

    Yu, Chen-Chiang; Baek, Jong Dae; Su, Chun-Hao; Fan, Liangdong; Wei, Jun; Liao, Ying-Chih; Su, Pei-Chen

    2016-04-27

    In this work we report a porous silver thin film cathode that was fabricated by a simple inkjet printing process for low-temperature solid oxide fuel cell applications. The electrochemical performance of the inkjet-printed silver cathode was studied at 300-450 °C and was compared with that of silver cathodes that were fabricated by the typical sputtering method. Inkjet-printed silver cathodes showed lower electrochemical impedance due to their porous structure, which facilitated oxygen gaseous diffusion and oxygen surface adsorption-dissociation reactions. A typical sputtered nanoporous silver cathode became essentially dense after the operation and showed high impedance due to a lack of oxygen supply. The results of long-term fuel cell operation show that the cell with an inkjet-printed cathode had a more stable current output for more than 45 h at 400 °C. A porous silver cathode is required for high fuel cell performance, and the simple inkjet printing technique offers an alternative method of fabrication for such a desirable porous structure with the required thermal-morphological stability.

  7. Influence of temperature and atmosphere on the strength and elastic modulus of solid oxide fuel cell anode supports

    DEFF Research Database (Denmark)

    Ni, De Wei; Charlas, Benoit; Kwok, Kawai

    2016-01-01

    Solid Oxide Fuel Cells are subjected to significant stresses during production and operation. The various stress-generating conditions impose strength requirements on the cell components, and thus the mechanical properties of the critical load bearing materials at relevant operational conditions ...

  8. Strategy towards cost-effective low-temperature solid oxide fuel cells: A mixed-conductive membrane comprised of natural minerals and perovskite oxide

    Science.gov (United States)

    Xia, Chen; Cai, Yixiao; Wang, Baoyuan; Afzal, Muhammad; Zhang, Wei; Soltaninazarlou, Aslan; Zhu, Bin

    2017-02-01

    Our previous work has revealed the feasibility of natural hematite as an electrolyte material for solid oxide fuel cells (SOFCs), tailoring SOFCs to be a more economically competitive energy conversion technology. In the present work, with the aim of exploring more practical uses of natural minerals, a novel composite hematite/LaCePrOx-La0.6Sr0.4Co0.2Fe0.8O3-δ (hematite/LCP-LSCF) has been developed from natural hematite ore, rare-earth mineral LaCePr-carbonate, and perovskite oxide LSCF as a functional membrane in SOFCs. The heterogeneity, nanostructure and mixed-conductive property of the composite were investigated. The results showed that the hematite/LCP-30 wt% LSCF composite possessed balanced ionic and electronic conductivities, with an ionic conductivity as high as 0.153 S cm-1 at 600 °C. The as-designed fuel cell using the hematite/LCP-LSCF membrane exhibited encouraging power outputs of 303 - 662 mW cm-2 at 500 - 600 °C. These findings show that the hematite/LCP-LSCF based fuel cell is a viable strategy for developing cost-effective and practical low-temperature SOFCs (LTSOFCs).

  9. Durability of Solid Oxide Cells

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Hauch, Anne; Hjelm, Johan

    2011-01-01

    In recent years extended focus has been placed on monitoring and understanding degradation mechanisms in both solid oxide fuel cells and solid oxide electrolysis cells. The time-consuming nature of degradation experiments and the disparate conclusions from experiment reproductions indicates...

  10. Improvement of the long term stability in the high temperature solid oxide fuel cell using functional layers

    Energy Technology Data Exchange (ETDEWEB)

    Brueckner, B.; Guenther, C.; Ruckdaeschel, R. [Siemens AG, Erlangen (Germany)] [and others

    1996-12-31

    In the planar Siemens design of the solid oxide fuel cell a metallic interconnector is used to seperate the ceramic single cells. A disadvantage of the metallic bipolar plate which consists of a chromium alloy is the formation of high volatile Cr-oxides and hydroxides at the surface at the cathode side. The reaction products evaporate and are reduced at the cathode/electrolyte interface to form new crystalline phases. This process gives rise to long term cell degradation. Protective coatings might be successful in preventing the chromium oxide evaporation. The required properties of the protective layers are (I) high electrical conductivity, (II) similar coefficients of thermal expansion to the bipolar plate (III), chemical compatibility to the bipolar plate and cathode material, (IV) a low diffusion coefficient of Cr and (V) chemical stability up to 1223K under oxygen atmosphere. Furthermore, during operation at 1223K an electrical contact between the metallic plate and the electrodes has to be maintained. This problem could be solved using ceramic layer between the metallic plate and the single cells.

  11. Ni-Based Solid Oxide Cell Electrodes

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Holtappels, Peter

    2013-01-01

    This paper is a critical review of the literature on nickel-based electrodes for application in solid oxide cells at temperature from 500 to 1000 _C. The applications may be fuel cells or electrolyser cells. The reviewed literature is that of experimental results on both model electrodes...... and practical composite cermet electrodes. A substantially longer three-phase boundary (TPB) can be obtained per unit area of cell in such a composite of nickel and electrolyte material, provided that two interwoven solid networks of the two solid and one gaseous phases are obtained to provide a three...

  12. Electrochemical properties of composite cathodes using Sm doped layered perovskite for intermediate temperature-operating solid oxide fuel cell

    Science.gov (United States)

    Baek, Seung-Wook; Azad, Abul K.; Irvine, John T. S.; Choi, Won Seok; Kang, Hyunil; Kim, Jung Hyun

    2018-02-01

    SmBaCo2O5+d (SBCO) showed the lowest observed Area Specific Resistance (ASR) value in the LnBaCo2O5+d (Ln: Pr, Nd, Sm, and Gd) oxide system for the overall temperature ranges tested. The ASR of a composite cathode (mixture of SBCO and Ce0.9Gd0.1O2-d) on a Ce0.9Gd0.1O2-d (CGO91) electrolyte decreased with respect to the CGO91 content; the percolation limit was also achieved for a 50 wt% SBCO and 50 wt% CGO91 (SBCO50) composite cathode. The ASRs of SBCO50 on the dense CGO91 electrolyte in the overall temperature range of 500-750 °C were relatively lower than those of SBCO50 on the CGO91 coated dense 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte for the same temperature range. From 750 °C and for all higher temperatures tested, however, the ASRs of SBCO50 on the CGO91 coated dense 8YSZ electrolyte were lower than those of the CGO91 electrolyte. The maximum power densities of SBCO50 on the Ni-8YSZ/8YSZ/CGO91 buffer layer were 1.034 W cm-2 and 0.611 W cm-2 at 800 °C and 700 °C.

  13. Nanostructured LnBaCo2O6− (Ln = Sm, Gd with layered structure for intermediate temperature solid oxide fuel cell cathodes

    Directory of Open Access Journals (Sweden)

    Augusto E. Mejía Gómez

    2017-04-01

    Full Text Available In this work, we present the combination of two characteristics that are beneficial for solid oxide fuel cell (SOFC cathodic performance in one material. We developed and evaluated for the first time nanostructured layered perovskites of formulae LnBaCo2O6-d with Ln = Sm and Gd (SBCO and GBCO, respectively as SOFC cathodes, finding promising electrochemical properties in the intermediate temperature range. We obtained those nanostructures by using porous templates to confine the chemical reagents in regions of 200-800 nm. The performance of nanostructured SBCO and GBCO cathodes was analyzed by electrochemical impedance spectroscopy technique under different operating conditions using Gd2O3-doped CeO2 as electrolyte. We found that SBCO cathodes displayed lower area-specific resistance than GBCO ones, because bulk diffusion of oxide ions is enhanced in the former. We also found that cathodes synthesized using smaller template pores exhibited better performance.

  14. Modeling and experimental performance of an intermediate temperature reversible solid oxide cell for high-efficiency, distributed-scale electrical energy storage

    Science.gov (United States)

    Wendel, Christopher H.; Gao, Zhan; Barnett, Scott A.; Braun, Robert J.

    2015-06-01

    Electrical energy storage is expected to be a critical component of the future world energy system, performing load-leveling operations to enable increased penetration of renewable and distributed generation. Reversible solid oxide cells, operating sequentially between power-producing fuel cell mode and fuel-producing electrolysis mode, have the capability to provide highly efficient, scalable electricity storage. However, challenges ranging from cell performance and durability to system integration must be addressed before widespread adoption. One central challenge of the system design is establishing effective thermal management in the two distinct operating modes. This work leverages an operating strategy to use carbonaceous reactant species and operate at intermediate stack temperature (650 °C) to promote exothermic fuel-synthesis reactions that thermally self-sustain the electrolysis process. We present performance of a doped lanthanum-gallate (LSGM) electrolyte solid oxide cell that shows high efficiency in both operating modes at 650 °C. A physically based electrochemical model is calibrated to represent the cell performance and used to simulate roundtrip operation for conditions unique to these reversible systems. Design decisions related to system operation are evaluated using the cell model including current density, fuel and oxidant reactant compositions, and flow configuration. The analysis reveals tradeoffs between electrical efficiency, thermal management, energy density, and durability.

  15. Avoiding chromium transport from stainless steel interconnects into contact layers and oxygen electrodes in intermediate temperature solid oxide electrolysis stacks

    Science.gov (United States)

    Schlupp, Meike V. F.; Kim, Ji Woo; Brevet, Aude; Rado, Cyril; Couturier, Karine; Vogt, Ulrich F.; Lefebvre-Joud, Florence; Züttel, Andreas

    2014-12-01

    We investigated the ability of (La0.8Sr0.2)(Mn0.5Co0.5)O3-δ (LSMC) and La(Ni0.6Fe0.4)O3-δ (LNF) contact coatings to avoid the transport of Cr from steel interconnects to solid oxide electrolysis electrodes, especially to the anode. The transport of chromium from commercial Crofer 22 APU (ThyssenKrupp) and K41X (AISI441, Aperam Isbergues) steels through LSMC and LNF contact coatings into adjacent (La0.8Sr0.2)MnO3-δ (LSM) oxygen electrodes was investigated in an oxygen atmosphere at 700 °C. Chromium concentrations of up to 4 atom% were detected in the contact coatings after thermal treatments for 3000 h, which also lead to the presence of chromium in adjacent LSM electrodes. Introduction of a dense (Co,Mn)3O4 coating between steel and contact coating was necessary to prevent the diffusion of chromium into contact coatings and electrodes and should lead to extended stack performance and lifetime.

  16. Oxidative pyrolysis of solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Senneca, Osvalda; Chirone, Riccardo [Istituto di Ricerche sulla Combustione, C.N.R., P.le Tecchio 80, 80125 Napoli (Italy); Salatino, Piero [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, P.le Tecchio 80, 80125 Napoli (Italy)

    2004-06-01

    This study addresses the dependence of the rate and pattern of pyrolysis of solid fuels from the oxidizing versus inert nature of the gaseous atmosphere. A selection of four solid fuels is considered in the study, namely two plastics (polyethylene and polyethylene terephthalate), one lignocellulosic material (Robinia Pseudoacacia) and a South African bituminous coal. Fuels are pyrolyzed in a thermogravimetric apparatus at different heating rates, under inert conditions or in the presence of oxygen at different concentration.Results indicate that the action exerted by oxygen during pyrolysis depends on the nature of the fuel and on the process conditions such as heating rate and oxygen concentration. Larger heating rates and larger oxygen concentration may indeed emphasize differences between inert and oxidative pyrolysis. Further analysis is directed to check the adequacy of a power low kinetic expression to describe the dependence of the rate of oxidative pyrolysis from the level of oxygen concentration.

  17. Engineered glass seals for solid-oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Surdoval, Wayne; Lara-Curzio, Edgar; Stevenson, Jeffry; Muth, Joseph Thomas; Armstrong, Beth L.; Shyam, Amit; Trejo, Rosa M.; Wang, Yanli; Chou, Yeong Shyung; Shultz, Travis Ray

    2017-02-07

    A seal for a solid oxide fuel cell includes a glass matrix having glass percolation therethrough and having a glass transition temperature below 650.degree. C. A deformable second phase material is dispersed in the glass matrix. The second phase material can be a compliant material. The second phase material can be a crushable material. A solid oxide fuel cell, a precursor for forming a seal for a solid oxide fuel cell, and a method of making a seal for a solid oxide fuel cell are also disclosed.

  18. Composite electrolytes of polyethylene oxides/garnets interfacially wetted by ionic liquid for room-temperature solid-state lithium battery

    Science.gov (United States)

    Huo, Hanyu; Zhao, Ning; Sun, Jiyang; Du, Fuming; Li, Yiqiu; Guo, Xiangxin

    2017-12-01

    Paramount attention has been paid on solid polymer electrolytes due to their potential in enhancement of energy density as well as improvement of safety. Herein, the composite electrolytes consisting of Li-salt-free polyethylene oxides and 200 nm-sized Li6.4La3Zr1.4Ta0.6O12 particles interfacially wetted by [BMIM]TF2N of 1.8 μL cm-2 have been prepared. Such wetted ionic liquid remains the solid state of membrane electrolytes and decreases the interface impedance between the electrodes and the electrolytes. There is no release of the liquid phase from the PEO matrix when the pressure of 5.0 × 104 Pa being applied for 24 h. The interfacially wetted membrane electrolytes show the conductivity of 2.2 × 10-4 S cm-1 at 20 °C, which is one order of magnitude greater than that of the membranes without the wetted ionic liquids. The conduction mechanism is related to a large number of lithium ions releasing from Li6.4La3Zr1.4Ta0.6O12 particles and the improved conductive paths along the ion-liquid-wetted interfaces between the polymer matrix and ceramic grains. When the membranes being used in the solid-state LiFePO4/Li and LiFe0.15Mn0.85PO4/Li cells at 25 °C, the excellent rate capability and superior cycle stability has been shown. The results provide a new prospect for solid polymer electrolytes used for room-temperature solid-state lithium batteries.

  19. Solid oxide fuel cell with monolithic core

    Science.gov (United States)

    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.

  20. Development of high temperature mechanical rig for characterizing the viscoplastic properties of alloys used in solid oxide cells

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Greco, Fabio; Kwok, Kawai

    2017-01-01

    temperature and in controlled atmosphere. The methodology uses a mechanical loading rig designed to apply variable as well as constant loads on samples within a gas-tight high temperature furnace. In addition, a unique remotely installed length measuring setup involving laser micrometer is used to monitor...

  1. Benchmarking the expected stack manufacturing cost of next generation, intermediate-temperature protonic ceramic fuel cells with solid oxide fuel cell technology

    Science.gov (United States)

    Dubois, Alexis; Ricote, Sandrine; Braun, Robert J.

    2017-11-01

    Recent progress in the performance of intermediate temperature (500-600 °C) protonic ceramic fuel cells (PCFCs) has demonstrated both fuel flexibility and increasing power density that approach commercial application requirements. These developments may eventually position the technology as a viable alternative to solid oxide fuel cells (SOFCs) and molten carbonate fuel cells (MCFCs). The PCFCs investigated in this work are based on a BaZr0.8Y0.2O3-δ (BZY20) thin electrolyte supported by BZY20/Ni porous anodes, and a triple conducting cathode material comprised of BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY0.1). These cells are prepared using a low-cost solid-state reactive sintering (SSRS) process, and are capable of power densities of 0.156 W cm-2 at 500 °C operating directly from methane fuel. We develop a manufacturing cost model to estimate the Nth generation production costs of PCFC stack technology using high volume manufacturing processes and compare them to the state-of-the-art in SOFC technology. The low-cost cell manufacturing enabled by the SSRS technique compensates for the lower PCFC power density and the trade-off between operating temperature and efficiency enables the use of lower-cost stainless steel materials. PCFC stack production cost estimates are found to be as much as 27-37% lower at 550 °C than SOFCs operating at 800 °C.

  2. Solid substrate-room temperature phosphorimetry for the determination of residual clenbuterol hydrochloride based on the catalysis of sodium periodate oxidizing eosine Y.

    Science.gov (United States)

    Liu, Jiaming; Zeng, Liqing; Li, Zhiming; Gao, Fei; Huang, Xiaomei; Li, Feiming; Lin, Huiqing

    2009-04-06

    Clenbuterol hydrochloride (CLB) could catalyze NaIO(4) oxidation of eosine Y (R), which caused the room temperature phosphorescence (RTP) signal of R to quench sharply. The DeltaI(P) (= I(P2)-I(P1), I(P2) was RTP intensities of reagent blank and I(P1) was RTP intensities of test solution) of the system was directly proportional to the content of CLB. According to that academic thought, a new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace CLB has been established. This method has high sensitivity (detection limit (LD): 0.021 zg spot(-1), corresponding concentration: 5.2x10(-20) g mL(-1)) and good selectivity (Er = +/-5%, interfering species were of no interference). It has been applied to the determination of residual CLB in the practical samples. The results were verified using HPLC and GC/MS methods. The reaction mechanism of catalytic SS-RTP for the determination of residual CLB was also discussed.

  3. Gas transport in solid oxide fuel cells

    CERN Document Server

    He, Weidong; Dickerson, James

    2014-01-01

    This book provides a comprehensive overview of contemporary research and emerging measurement technologies associated with gas transport in solid oxide fuel cells. Within these pages, an introduction to the concept of gas diffusion in solid oxide fuel cells is presented. This book also discusses the history and underlying fundamental mechanisms of gas diffusion in solid oxide fuel cells, general theoretical mathematical models for gas diffusion, and traditional and advanced techniques for gas diffusivity measurement.

  4. Tubular solid oxide fuel cell development program

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    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

    Energy Technology Data Exchange (ETDEWEB)

    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. Mathematical modeling of solid oxide fuel cells

    Science.gov (United States)

    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.

  7. Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition

    Science.gov (United States)

    2013-01-01

    Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V). PMID:23342963

  8. High-temperature, solid oxide electrolyte fuel cell power generating system. Annual report, June 1, 1980-May 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    1981-10-14

    Closed-end tubes are now being prepared in-house, for use in fabricating and evaluating the FBA cell design. New perovskite-type mixed oxides are being investigated as air electrode materials and some have been identified and are being used in FBA cell test evaluation studies. Initial FBA cells have been fabricated and tested. Although their performance is below target goals, fabrication procedures for all fuel cell components have been verified for cell construction. Areas of investigation for FBA cell performance improvement have been identified and work is proceeding in these areas. Variable-length cells in the series-cell stack design have demonstrated high (85%) fuel utilization with good performance (0.57 anti V at 400 mA/cm/sup 2/ average, simulated coal derived fuel, 1000/sup 0/C).

  9. Solid oxide fuel cell steam reforming power system

    Science.gov (United States)

    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%.

  10. Solid oxide fuel cells fueled with reducible oxides

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Steven S.; Fan, Liang Shih

    2018-01-09

    A direct-electrochemical-oxidation fuel cell for generating electrical energy includes a cathode provided with an electrochemical-reduction catalyst that promotes formation of oxygen ions from an oxygen-containing source at the cathode, a solid-state reduced metal, a solid-state anode provided with an electrochemical-oxidation catalyst that promotes direct electrochemical oxidation of the solid-state reduced metal in the presence of the oxygen ions to produce electrical energy, and an electrolyte disposed to transmit the oxygen ions from the cathode to the solid-state anode. A method of operating a solid oxide fuel cell includes providing a direct-electrochemical-oxidation fuel cell comprising a solid-state reduced metal, oxidizing the solid-state reduced metal in the presence of oxygen ions through direct-electrochemical-oxidation to obtain a solid-state reducible metal oxide, and reducing the solid-state reducible metal oxide to obtain the solid-state reduced metal.

  11. Conversion of hydrocarbons in solid oxide fuel cells

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Kammer Hansen, K.

    2003-01-01

    Recently, a number of papers about direct oxidation of methane and hydrocarbon in solid oxide fuel cells (SOFC) at relatively low temperatures (about 700degreesC) have been published. Even though the conversion of almost dry CH4 at 1000degreesC on ceramic anodes was demonstrated more than 10 years...

  12. Effect of calcination temperature on the activity of solid Ca/Al composite oxide-based alkaline catalyst for biodiesel production.

    Science.gov (United States)

    Meng, Yong-Lu; Wang, Bo-Yang; Li, Shu-Fen; Tian, Song-Jiang; Zhang, Min-Hua

    2013-01-01

    A solid Ca/Al composite oxide-based alkaline catalyst containing Ca(12)Al(14)O(33) and CaO was prepared by chemical synthesis and thermal activation from sodium aluminate solution and calcium hydroxide emulsion. The effect of calcination temperatures ranging from 120 °C to 1000 °C on activity of the catalyst was investigated. The catalyst calcined at 600 °C showed the highest activity with >94% yield of fatty acid methyl esters (i.e. biodiesel) when applied to the transesterification of rapeseed oil at a methanol:oil molar ratio of 15:1 at 65 °C for 3h. Structure and properties of the catalyst were studied and the characterizations with XRD, TGA, FTIR, BET, and SEM demonstrated that the performance of the catalyst was closely related to its specific surface area and crystalline structure. In particular, the generation of crystalline Ca(12)Al(14)O(33) improved the catalytic activity due its synergistic effect with CaO. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Tailoring the activity via cobalt doping of a two-layer Ruddlesden-Popper phase cathode for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Chen, Zezhi; Wang, Jianlin; Huan, Daoming; Sun, Shujie; Wang, Guopeng; Fu, Zhengping; Zhang, Wenhua; Zheng, Xusheng; Pan, Haibin; Peng, Ranran; Lu, Yalin

    2017-12-01

    Co-doped La3Ni2O7 single phase mix-conductors are successfully fabricated and investigated as cathodes for solid oxide fuel cells. Electrochemical measurement suggests that the polarization resistance of the cell using such cathodes reduce largely when increasing the Co content in La3Ni2O7 cathodes, which is about 1.12 Ω cm2 for La3Ni1.9Co0.1O7 and 0.35 Ω cm2 for La3Ni1.6Co0.4O7 both measured at 650 °C. X-ray photoelectron spectroscopy analysis suggests that the Co-doped La3Ni2O7 samples keep much more oxygen vacancies at high temperatures when compared with those undoped samples, which can benefit both oxygen adsorption and oxygen ion diffusion process in the oxygen reduction reaction. Moreover, both conductivity and magnetic measurements indicate that the covalence of B-O bonds in Co-doped samples can be largely improved because of the more localized 3d electrons in the Co substituted samples, which can further help to accelerate the proton diffusion process. The findings in this research demonstrate that the Co-doped La3Ni2O7 with the two-layer structure can be a promising cathode for proton conducting SOFCs, due to its high activity toward the oxygen reduction reaction.

  14. Synthesis of LaCoO{sub 3} nano-powders by aqueous gel-casting for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chia Siang; Zhang, Lan; Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore); Zhang, Yu.Jun [Key Lab for Liquid Structure and Heredity of Ministry of Education, School of Materials Science and Engineering, Shandong University, Jinan (China)

    2008-04-15

    LaCoO{sub 3} (LC) perovskite powders for intermediate temperature solid oxide fuel cells (IT-SOFCs) are synthesized by a simple and cost-effective aqueous gel-casting technique using metal nitrates as raw materials. Effect of the ratio of organic precursors (acrylamide (AM) monomer and N,N'-Methylenebisacrylamide (MBAM) crosslinker) to metal nitrates (lanthanum nitrate, cobalt nitrate) and the ratio of AM to MBAM on the particle size are investigated in detail. TEM results indicate that the particle size of LC nano-powders is in the range of 31-60 nm and decreases with increasing ratio of organic precursor to metal nitrates but is not affected by the ratio of AM to MBAM. Preliminary results show that the nano-structured electrode approach based on wet impregnation is effective to combine the high electrocatalytic activity of LC nano-powders and the structural stability of La{sub 0.72}Sr{sub 0.18}MnO{sub 3} {sub -} {sub {delta}} (LSM) electrodes for the development of IT-SOFC cathodes. (author)

  15. Dopant distribution and influence of sonication temperature on the pure red light emission of mixed oxide phosphor for solid state lighting.

    Science.gov (United States)

    Som, S; Kumar, Vijay; Kumar, Vinod; Gohain, Mukut; Pandey, Anurag; Duvenhage, M M; Terblans, J J; Bezuindenhoud, B C B; Swart, H C

    2016-01-01

    In this study, europium doped yttrium gadolinium (Y1.4Gd0.5Eu0.1O3) mixed oxide phosphors were synthesized by a sonochemical method at different growth temperatures (50°C, 100°C, 150°C and 200°C) for pure red light emission applications. The compositional identification, presence of dopants and the distribution of doping materials in the crystal lattice was studied by TOF-SIMS. The formation and growth mechanisms in the sonochemical synthesis of Y1.4Gd0.5Eu0.1O3 nanophosphors are discussed in detail. Different spectral and Judd-Ofelt parameters were estimated from photoluminescence data. Optical gain and efficiency parameters were calculated with the variation of synthesis environment and an efficient synthesis method to make good red emitting phosphors for solid-state lighting and display applications were proposed. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Stability of solid oxide fuel cell materials

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, T.R.; Bates, J.L.; Coffey, G.W.; Pederson, L.R. [Pacific Northwest National Lab., Richland, WA (United States)] [and others

    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. Trends for Methane Oxidation at Solid Oxide Fuel Cell Conditions

    DEFF Research Database (Denmark)

    Kleis, Jesper; Jones, Glenn; Abild-Pedersen, Frank

    2009-01-01

    First-principles calculations are used to predict a plausible reaction pathway for the methane oxidation reaction. In turn, this pathway is used to obtain trends in methane oxidation activity at solid oxide fuel cell (SOFC) anode materials. Reaction energetics and barriers for the elementary...

  18. Solid oxide materials research accelerated electrochemical testing

    Energy Technology Data Exchange (ETDEWEB)

    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. Solid oxide materials research accelerated electrochemical testing

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, T.R.; Windisch, C.; Arey, B.

    1995-12-31

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

  20. Effect of low temperature in-situ sintering on the impedance and the performance of intermediate temperature solid oxide fuel cell cathodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Hjalmarsson, Per; Hansen, Martin Hangaard

    2014-01-01

    frequency slope of the characteristic Gerischer impedance response of porous mixed ionic and electronically conducting (MIEC) cathodes. In contrast to LSCF, the LSC-based cathodes showed excellent sintering capabilities, electronic conductivity and performance. Scanning electron microscopy investigations......The effect of in-situ sintering temperature and time on the electronic conductivity, impedance and performance of IT-SOFC cathodes were studied. The studied cathodes were for comparison (La0.6Sr0.4)0.99CoO3 (LSC), (La0.6Sr0.4)0.99CoO3:Ce0.9Gd0.1O1.95 (LSC:CGO), La0.58Sr0.4Co0.2Fe0.8O3 (LSCF) and La...

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

    Science.gov (United States)

    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 (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 alloys and nanoscale compositionally graded membranes that are thermomechanically robust and provide added interfacial functionality. The work in this thesis advances experimental state-of-the-art with respect to solid oxide fuel cell operation temperature, provides fundamental boundaries expected for ultrathin electrolytes, develops the ability to integrate highly dissimilar material (such as oxide-polymer) heterostructures, and introduces nanoscale compositionally graded electrolyte membranes that can lead to monolithic materials having multiple functionalities.

  2. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    Energy Technology Data Exchange (ETDEWEB)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed [Sharif University of Technology, Tehran (Iran, Islamic Republic of). Dept. of Chemistry]. E-mail: mhashemi@sharif.edu

    2005-09-15

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  3. MOF-derived iron as an active energy storage material for intermediate-temperature solid oxide iron-air redox batteries.

    Science.gov (United States)

    Zhang, Cuijuan; Huang, Kevin

    2017-09-21

    We here demonstrate that the iron derived from an iron-based metal-organic framework (MOF), with exposed high-density Fe-atom planes, exhibits improved reduction activity, enabling good rechargeability of solid oxide iron-air redox batteries at 500 °C. The discharge mass specific energies are 226.5 W h kg-1-Fe and 214.8 W h kg-1-Fe at C/4 and C/3, respectively, at a constant Fe-utilization of 20%.

  4. Advanced materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Impedance Modeling of Solid Oxide Fuel Cell Cathodes

    DEFF Research Database (Denmark)

    Mortensen, Jakob Egeberg; Søgaard, Martin; Jacobsen, Torben

    2010-01-01

    A 1-dimensional impedance model for a solid oxide fuel cell cathode is formulated and applied to a cathode consisting of 50/50 wt% strontium doped lanthanum cobaltite and gadolinia doped ceria. A total of 42 impedance spectra were recorded in the temperature range: 555-852°C and in the oxygen...

  6. Mechanochemically assisted room temperature solid state ...

    Indian Academy of Sciences (India)

    This communication reports a novel mechanochemically assisted room temperature solid state metathesis reaction for the synthesis of submicron-size alkaline-earth molybdates crystallizing in a tetragonal Scheelite structure. The solids were characterized by powder XRD, FTIR, TGA, DTA, SEM, EDAX and TEM to ascertain ...

  7. Processing temperature tuned interfacial microstructure and protonic and oxide ionic conductivities of well-sintered Sm0.2Ce0.8O1.9- Na2CO3 nanocomposite electrolytes for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Li, Chuanming; Zeng, Yanwei; Wang, Zhentao; Ye, Zhupeng; Zhang, Yuan

    2017-08-01

    Well-sintered SDC-NC (Sm0.2Ce0.8O1.9-Na2CO3) nanocomposites have been prepared through a rare-earth/sodium complex carbonate precipitation, powder prefirings at the temperatures 400, 500 and 600 °C and sintering at 800 °C. Their sintering performances, phase components and microstructures have been characterized by Archimedean method, XRD and FESEM techniques. In particular, the influence of the interfacial interactions between the phases of SDC and NC on the microstructures and electrical conductivities of SDC-NC nanocomposites have been investigated by AC impedance and Raman spectroscopies. It has been found that on the basis of the fitting analysis of AC impedance data, the oxide ionic and protonic conductivities of interfacial and non-interfacial phases in the SDC-NC nanocomposites are found to be strongly dependent upon their prefiring temperatures with the sample of SN-600 showing the highest values of 73.2/33.7 and 51.1/105.4 μS/cm at 300 °C, respectively. The single cell based on the electrolyte of SN-600 presents an OCV of 0.992 V and peak power density of 421 mW/cm2 at 550 °C. The interfacial interactions between the phases of SDC and NC inside SDC-NC nanocomposites are considered responsible for their differences in microstructure and electrical conductivity.

  8. Molten-salt synthesis of oxyapatite La{sub 9.33}Si{sub 6}O{sub 26} powders as electrolytes for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhaoxiang [Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Wenhua College, Huazhong University of Science and Technology, Wuhan 430074 (China); Li, Buyin; Liu, Jia [Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-10-15

    Lanthanum silicate oxy-apatites are thought of as ytrria-stabilized zirconia substitutes in intermediate temperature solid oxide fuel cells. Lanthanum silicate oxy-apatite powders La{sub 9.33}Si{sub 6}O{sub 26} are successfully synthesized at lower temperature by a molten-salt method. X-ray diffraction, scanning electron microscopy, and precision impedance analysis used to characterize the structure, appearance, and conductivity of La{sub 9.33}Si{sub 6}O{sub 26}. The results indicate that the apatite phase has been synthesized. The synthesis method decreases the synthesis temperature by about 300 C in comparison to the conventional solid-state reaction route and obtains homogeneous and nanosize powders. Dense ceramics have been prepared at sintering temperatures around 1450 C. The used of molten-salt powders allows a decrease of the dense ceramic pellet sintering temperature of about 200 C. The ceramic pellets sintering at 1550 C for 4 h have a relative density of 92% and an electrical conductivity of 1.1 x 10{sup -3} S cm{sup -1} at 700 C, higher than the some reported for the solid-state synthesis method and the sol-gel method. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  9. Nanostructured Solid Oxide Fuel Cell Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Sholklapper, Tal Zvi [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    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.

  10. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2017-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s...

  11. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s...

  12. Supercritical water oxidation - Microgravity solids separation

    Science.gov (United States)

    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.

  13. Stability of solid oxide fuel cell materials

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, T.R.; Bates, J.L.; Chick, L.A. [Pacific Northwest Lab., Richland, WA (United States)

    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.

  14. Fabrication and sealing performance of rare-earth containing glass–ceramic seals for intermediate temperature solid oxide fuel cell applications

    DEFF Research Database (Denmark)

    Abdoli, H.; Alizadeh, P.; Agersted, Karsten

    2014-01-01

    The opportunity of using two rare-earth metal oxides in an aluminosilicate glass for seal applications was investigated in this work. Substitution of La2O3 with Y2O3 in the system changed thermal and physical properties such as transition temperature, flowing behavior, and thermal expansion...... containing strontium in the composition, well bonded interface was obtained in contact with 8YSZ and SS430 ferritic stainless steel. The hermeticity of the glass seals was maintained after 100h isothermal aging at 800°C. Also the OCV showed insignificant fluctuations with stable average values after 24...

  15. Low temperature processed MnCo2O4 and MnCo1.8Fe0.2O4 as effective protective coatings for solid oxide fuel cell interconnects at 750 °C

    DEFF Research Database (Denmark)

    Molin, Sebastian; Jasinski, P.; Mikkelsen, Lars

    2016-01-01

    In this study two materials, MnCo2O4 and MnCo1.8Fe0.2O4 are studied as potential protective coatings for Solid Oxide Fuel Cell interconnects working at 750 °C. First powder fabrication by a modified Pechini method is described followed by a description of the coating procedure. The protective...... performed on the coated samples shows good protection against chromium diffusion from the chromia scale ensured by a formation of a dense reaction layer. This study shows, that even without high temperature sintering and/or reactive sintering it is possible to fabricate protective coatings based on Mn...

  16. A review of high temperature co-electrolysis of H2O and CO2to produce sustainable fuels using solid oxide electrolysis cells (SOECs): advanced materials and technology.

    Science.gov (United States)

    Zheng, Yun; Wang, Jianchen; Yu, Bo; Zhang, Wenqiang; Chen, Jing; Qiao, Jinli; Zhang, Jiujun

    2017-03-06

    High-temperature solid oxide electrolysis cells (SOECs) are advanced electrochemical energy storage and conversion devices with high conversion/energy efficiencies. They offer attractive high-temperature co-electrolysis routes that reduce extra CO 2 emissions, enable large-scale energy storage/conversion and facilitate the integration of renewable energies into the electric grid. Exciting new research has focused on CO 2 electrochemical activation/conversion through a co-electrolysis process based on the assumption that difficult C[double bond, length as m-dash]O double bonds can be activated effectively through this electrochemical method. Based on existing investigations, this paper puts forth a comprehensive overview of recent and past developments in co-electrolysis with SOECs for CO 2 conversion and utilization. Here, we discuss in detail the approaches of CO 2 conversion, the developmental history, the basic principles, the economic feasibility of CO 2 /H 2 O co-electrolysis, and the diverse range of fuel electrodes as well as oxygen electrode materials. SOEC performance measurements, characterization and simulations are classified and presented in this paper. SOEC cell and stack designs, fabrications and scale-ups are also summarized and described. In particular, insights into CO 2 electrochemical conversions, solid oxide cell material behaviors and degradation mechanisms are highlighted to obtain a better understanding of the high temperature electrolysis process in SOECs. Proposed research directions are also outlined to provide guidelines for future research.

  17. AN-107 entrained solids - Solubility versus temperature

    Energy Technology Data Exchange (ETDEWEB)

    GJ Lumetta; RC Lettau

    2000-03-31

    This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AN-107 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AN-107 sample using sodium hydroxide and de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AN-107 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions.

  18. Solid oxide fuel cell project

    NARCIS (Netherlands)

    T. Bakker; G. Tijseling; R. van Straten; R. Bijkerk

    2014-01-01

    A trend of increasing overall efficiency when increasing carbon dioxide, hydrogen percentage comparing to pure methane or natural gas. Significantly decreasing Temperature of exhaust gas when increasing carbon dioxide and hydrogen percentage (result graphs 4.2, 4.3, 4.5 & 4.6). The BlueGen

  19. Sealing materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, P.H.

    1999-02-01

    A major obstacle in the achievement of high electrical efficiency for planar solid oxide fuel cell stacks (SOFC) is the need for long term stable seals at the operational temperature between 850 and 1000 deg. C. In the present work the formation and properties of sealing materials for SOFC stacks that fulfil the necessary requirements were investigated. The work comprises analysis of sealing material properties independently, in simple systems as well as tests in real SOFC stacks. The analysed sealing materials were based on pure glasses or glass-ceramic composites having B{sub 2}O{sub 3}, P{sub 2}O{sub 5} or siO{sub 2} as glass formers, and the following four glass systems were investigated: MgO/caO/Cr{sub 2}O{sub 3}-Al{sub 2}O{sub 3}B{sub 2}O{sub 3}-P{sub 2}O{sub 5}, MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}, MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}-SiO{sub 2} and BaO/Na{sub 2}O-Al{sub 2}O{sub 3}-SiO{sub 2}. (au) 32 tabs., 106 ills., 107 refs.

  20. Monolithic Solid Oxide Fuel Cell development

    Science.gov (United States)

    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.

  1. Thin-Film Solid Oxide Fuel Cells

    Science.gov (United States)

    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.

  2. Nanocrystalline cerium oxide materials for solid fuel cell systems

    Science.gov (United States)

    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.

  3. High Temperature Solid Lubricant Coating for High Temperature Wear Applications

    Science.gov (United States)

    DellaCorte, Christopher (Inventor); Edmonds, Brian J (Inventor)

    2014-01-01

    A self-lubricating, friction and wear reducing composite useful over a wide temperature range is described herein. The composite includes metal bonded chromium oxide dispersed in a metal binder having a substantial amount of nickel. The composite contains a fluoride of at least one Group I, Group II, or rare earth metal, and optionally a low temperature lubricant metal.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Solid oxide cell stack and method for preparing same

    DEFF Research Database (Denmark)

    2012-01-01

    A method for producing and reactivating a solid oxide cell stack structure by providing a catalyst precursor in at least one of the electrode layers by impregnation and subsequent drying after the stack has been assembled and initiated. Due to a significantly improved performance and an unexpecte...... voltage improvement this solid oxide cell stack structure is particularly suitable for use in solid oxide fuel cell (SOFC) and solid oxide electrolysing cell (SOEC) applications....

  6. Yttrium and Nickel Co-Doped BaZrO3 as a Proton-Conducting Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

    KAUST Repository

    Shafi, S. P.

    2015-07-17

    High temperature proton conducting oxides, due to their lower activation energy for proton conduction, can achieve high conductivity at relatively low temperatures (500-700°C). Though BaZr0.8Y0.2O3-δ (BZY) perovskite exhibits good chemical stability and high bulk conductivity, high grain boundary resistance decreases its total conductivity. This work focuses on substitution of Zr4+ with Ni2+ in the perovskite B-site in a targeted fashion in order to promote the sinterability of BZY. Powder X-ray diffraction analysis showed the formation of single phases for Ba0.8-xY0.2NixO3-δ compositions up to x = 0.04. Scanning electron microscopy (SEM) image analysis demonstrated that densification is promoted by increasing the Ni-content, reaching a fully dense microstructure for Ba0.76Y0.2Ni0.04O3-δ (BZYNi04). An anode supported single cell based on BZYNi04 electrolyte showed superior power performance, achieving 240 and 428 mW cm-2 at 600 and 700°C, respectively. © The Electrochemical Society.

  7. Promotion on electrochemical performance of a cation deficient SrCo0.7Nb0.1Fe0.2O3-δ perovskite cathode for intermediate-temperature solid oxide fuel cells

    Science.gov (United States)

    Ding, Liming; Wang, Lixi; Ding, Dong; Zhang, Shihua; Ding, Xifeng; Yuan, Guoliang

    2017-06-01

    Solid oxide fuel cells (SOFCs) offer great promise for the most efficient and cost-effective conversion to electricity of a wide variety of fuels. The cathode materials with high electro-catalytic activity for oxygen reduction reaction is vital to the development of commercially-viable SOFCs to be operated at reduced temperatures. In present study, cobalt-based perovskite oxides SrxCo0.7Nb0.1Fe0.2O3-δ (SCNF, x = 0.95 and 1) were comparatively investigated as promising cathode materials for intermediate-temperature SOFCs. The SCNF compounds with a slight Sr deficiency (S0.95CNF) exhibited single phase of primitive cubic structure with Pm-3m symmetry. A small Sr deficiency is demonstrated to greatly enhance the electrochemical performance of stoichiometric SCNF cathode due to significantly increased oxygen vacancy. The polarization resistance of S0.95CNF at 700 °C was 0.11 Ω cm2, only about 61% of SCNF. The rate limiting step for oxygen reduction reaction (ORR) is demonstrated to be oxygen ion transfer within the bulk electrode and/or from electrode to electrolyte through the triple phase boundary. Full cells with the SCNF cathode present good performance and stable output at reduced temperatures, indicating the great potential for enhanced performance of Co-based cathodes with A-site deficiency.

  8. Fabrication of Transparent Conductive Zinc Oxide Co-Doped with Fluorine and Zirconium Thin Solid Films by Ultrasonic Chemical Pyrolysis: Effects of Precursor Solution Aging and Substrate Temperature

    Directory of Open Access Journals (Sweden)

    Luis Castañeda

    2013-01-01

    Full Text Available Highly transparent, conducting zinc oxide [ZnO] thin films co-doped with fluorine and zirconium have been deposited on glass substrates by the ultrasonic chemical spraying technique. The effects of aging of the starting solution and substrate temperature on the structural, morphological, and electrical properties of the ZnO:F:Zr films have been studied. The resistivity of the films decreases with the aging time of the starting solution until the seventeenth day reaching a minimum of about 1.2×10−2 Ω cm and then increases. Though all the samples are of polycrystalline hexagonal wurtzite type and grow preferentially with (002 plane parallel to the substrate, their morphology depends strongly on the aging time of the reaction solution. The optical transmittance of all the films remained around 80% in the visible spectral range. These highly transparent, low resistive thin films are expected to be highly useful as transparent electrodes in the fabrication of thin film solar cells.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Solid oxide electrolysis cells - Performance and durability

    Energy Technology Data Exchange (ETDEWEB)

    Hauch, A.

    2007-10-15

    In this work H2 electrode supported solid oxide cells (SOC) produced at Risoe National Laboratory, DTU, have been used for steam electrolysis. Electrolysis tests have been performed at temperatures from 650AeC to 950AeC, p(H2O)/p(H2) from 0.99/0.01 to 0.30/0.70 and current densities from -0.25 A/cm2 to -2 A/cm2. The solid oxide electrolysis cells (SOEC) have been characterised by iV curves and electrochemical impedance spectroscopy (EIS) at start and end of tests and by EIS under current load during electrolysis testing. The tested SOCs have shown the best initial electrolysis performance reported in literature to date. Area specific resistances of 0.26 Oecm2 at 850AeC and 0.17 Oecm2 at 950AeC were obtained from electrolysis iV curves. The general trend for the SOEC tests was: 1) a short-term passivation in first few hundred hours, 2) then an activation and 3) a subsequent and underlying long-term degradation. The transient phenomenon (passivation/activation) was shown to be a set-up dependent artefact caused by the albite glass sealing with a p(Si(OH)4) of 1.10-7 atm, leading to silica contamination of the triple-phase boundaries (TPBs) of the electrode. The long-term degradation for the SOECs was more pronounced than for fuel cell testing of similar cells. Long-term degradation of 2%/1000 h was obtained at 850AeC, p(H2O)/p(H2) = 0.5/0.5 and -0.5 A/cm2, whereas the degradation rate increased to 6%/1000h at 950AeC, p(H2O)/p(H2) = 0.9/0.1 and -1.0 A/cm2. Both the short-term passivation and the long-term degradation appear mainly to be related to processes in the H2 electrode. Scanning electron microscopy micrographs show that only limited changes occur in the Ni particle size distribution and these are not the main degradation mechanism for the SOECs. Micro and nano analysis using energy dispersive spectroscopy in combination with transmission electron microscopy (TEM) and scanning TEM reveals that glassy phase impurities have accumulated at the TPBs as a result of

  11. Performance and durability of solid oxide electrolysis cells

    DEFF Research Database (Denmark)

    Hauch, Anne; Jensen, Søren H; Ramousse, Severine

    2006-01-01

    Solid oxide fuel cells produced at Riso National Laboratory have been tested as electrolysis cells by applying an external voltage. Results on initial performance and durability of such reversible solid oxide cells at temperatures from 750 to 950 degrees C and current densities from -0.25 A/cm(2......) to -0.50 A/cm(2) are reported. The full cells have an initial area specific resistance as low as 0.27 Omega cm(2) for electrolysis operation at 850 degrees C. During galvanostatic long-term electrolysis tests, the cells were observed to passivate mainly during the first similar to 100 h of electrolysis....... Cells that have been passivated during electrolysis tests can be partly activated again by operation in fuel cell mode or even at constant electrolysis conditions after several hundred hours of testing....

  12. A novel family of Nb-doped Bi0.5Sr0.5FeO3-δ perovskite as cathode material for intermediate-temperature solid oxide fuel cells

    Science.gov (United States)

    Gao, Lei; Li, Qiang; Sun, Liping; Zhang, Xianfa; Huo, Lihua; Zhao, Hui; Grenier, Jean-Claude

    2017-12-01

    Cobalt-free provskite oxides Bi0.5Sr0.5Fe1-xNbxO3-δ (BSFNx, x = 0.05, 0.10 and 0.15) were prepared and evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). In particular, the effects of Nb substitution on phase evolution, thermal expansion behavior and electrochemical performance were systematically investigated. The average thermal expansion coefficient (TEC) of BSFNx decreases from 13.3 × 10-6 K-1 at x = 0.05 to 12.6 × 10-6 K-1 at x = 0.15 within a temperature range of 50-800 °C. Among the BSFNx materials, Bi0.5Sr0.5Fe0.9Nb0.1O3-δ (BSFN0.10) oxide shows the best electrochemical performance. The polarization resistances (Rp) of BSFN0.10 cathode on CGO electrolyte are 0.038, 0.075 and 0.156 Ω cm2 at 700, 650 and 600 °C, respectively. Meanwhile the maximum power densities of the anode-supported single cells are 1.28, 1.54 and 1.34 W cm-2 at 700 °C for BSFNx cathodes with x = 0.05, 0.10, and 0.15, respectively. Furthermore, the relationship study of oxygen partial pressure dependence on Rp indicates that the oxygen reduction reaction (ORR) rate-limiting step is the oxygen adsorption-dissociation on the electrode surface. The desirable electrochemical performance demonstrates that BSFNx oxides are potential cathode materials for IT-SOFCs.

  13. Low temperature processed MnCo2O4 and MnCo1.8Fe0.2O4 as effective protective coatings for solid oxide fuel cell interconnects at 750 °C

    Science.gov (United States)

    Molin, S.; Jasinski, P.; Mikkelsen, L.; Zhang, W.; Chen, M.; Hendriksen, P. V.

    2016-12-01

    In this study two materials, MnCo2O4 and MnCo1.8Fe0.2O4 are studied as potential protective coatings for Solid Oxide Fuel Cell interconnects working at 750 °C. First powder fabrication by a modified Pechini method is described followed by a description of the coating procedure. The protective action of the coating applied on Crofer 22 APU is evaluated by following the area specific resistance (ASR) of the scale/coating for 5500 h including several thermal cycles. The coating is prepared by brush painting and has a porous structure after deposition. Post mortem microstructural characterization performed on the coated samples shows good protection against chromium diffusion from the chromia scale ensured by a formation of a dense reaction layer. This study shows, that even without high temperature sintering and/or reactive sintering it is possible to fabricate protective coatings based on MnCo spinels.

  14. Highly CO2-Tolerant Cathode for Intermediate-Temperature Solid Oxide Fuel Cells: Samarium-Doped Ceria-Protected SrCo0.85Ta0.15O3-δ Hybrid.

    Science.gov (United States)

    Li, Mengran; Zhou, Wei; Zhu, Zhonghua

    2017-01-25

    Susceptibility to CO2 is one of the major challenges for the long-term stability of the alkaline-earth-containing cathodes for intermediate-temperature solid oxide fuel cells. To alleviate the adverse effects from CO2, we incorporated samarium-stabilized ceria (SDC) into a SrCo0.85Ta0.15O3-δ (SCT15) cathode by either mechanical mixing or a wet impregnation method and evaluated their cathode performance stability in the presence of a gas mixture of 10% CO2, 21% O2, and 69% N2. We observed that the CO2 tolerance of the hybrid cathode outperforms the pure SCT15 cathode by over 5 times at 550 °C. This significant enhancement is likely attributable to the low CO2 adsorption and reactivity of the SDC protective layer, which are demonstrated through thermogravimetric analysis, energy-dispersive spectroscopy, and electrical conductivity study.

  15. Highly efficient and robust cathode materials for low-temperature solid oxide fuel cells: PrBa0.5Sr0.5Co2−xFexO5+δ

    Science.gov (United States)

    Choi, Sihyuk; Yoo, Seonyoung; Kim, Jiyoun; Park, Seonhye; Jun, Areum; Sengodan, Sivaprakash; Kim, Junyoung; Shin, Jeeyoung; Jeong, Hu Young; Choi, YongMan; Kim, Guntae; Liu, Meilin

    2013-01-01

    Solid oxide fuel cells (SOFC) are the cleanest, most efficient, and cost-effective option for direct conversion to electricity of a wide variety of fuels. While significant progress has been made in anode materials with enhanced tolerance to coking and contaminant poisoning, cathodic polarization still contributes considerably to energy loss, more so at lower operating temperatures. Here we report a synergistic effect of co-doping in a cation-ordered double-perovskite material, PrBa0.5Sr0.5Co2−xFexO5+δ, which has created pore channels that dramatically enhance oxygen ion diffusion and surface oxygen exchange while maintaining excellent compatibility and stability under operating conditions. Test cells based on these cathode materials demonstrate peak power densities ~2.2 W cm−2 at 600°C, representing an important step toward commercially viable SOFC technologies. PMID:23945630

  16. The TMI regenerable solid oxide fuel cell

    Science.gov (United States)

    Cable, Thomas L.

    1995-04-01

    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

  17. Development of solid oxide fuel cell technology

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Dae Kab; Kim, Sun Jae; Jung, Choong Hwan; Kim, Kyung Hoh; Park, Ji Yun; Oh, Suk Jin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-01-01

    Solid Oxide Fuel Cell (SOFC) technologies that use zirconium oxide as the electrolyte material were studied in this present report. SOFC exhibits a very high power generation efficiency of over 50 %, and does not discharge pollution materials such as dusts, sulfur dioxide, and nitrogen oxide. Zirconia, Ni/YSZ (yttria stabilized zirconia), and La-Sr-Mn-Oxide materials were developed for the electrolyte material, for the anode, and for the cathode, respectively. After making thin zirconia plate using tape casting process, anode and cathode powders were screen printed on the zirconia plate for fabricating unit cells. A test system composed of a vertical tube furnace, digital multimeter, DC current supplier, and measuring circuit was constructed for testing the unit cell performance. This system was controlled by a home-made computer program. Founded on this unit cell technology and system, a multi-stack SOFC system was studied. This system was composed of 10 unit cells each of them had an electrode area of 40 x 40 mm. Based on this system design, large and thin zirconia plates of 70 x 70 mm in area was fabricated for the electrolyte. Different from in the unit cell system, interconnectors are needed in the multi-stack system for connecting unit cells electrically. For this interconnectors, Inconel 750 alloy was selected, sliced into wafers, machined, surface finished, and then Pt-plated. 55 figs, 8 tabs, 51 refs. (Author).

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

    Science.gov (United States)

    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.

  19. Thermoneutral Operation of Solid Oxide Electrolysis Cells in Potentiostatic Mode

    DEFF Research Database (Denmark)

    Chen, Ming; Sun, Xiufu; Chatzichristodoulou, Christodoulos

    2017-01-01

    High temperature electrolysis based on solid oxide electrolysis cells (SOECs) is a promising technology for energy storage and synthetic fuel production. In recent years extensive efforts have been devoted to improving performance and durability of SOEC cells and stacks. Due to historical reasons...... and the convenience of doing constant current tests, (almost) all the reported SOEC tests have been galvanostatic. In this work, we report test results on two types of SOEC cells operated for electrolysis of steam in potentiostatic mode at 1.29 V. Both cells are Ni/YSZ fuel electrode supported type with different...... cause of the degradation. Operation strategies were further proposed for electrolysis operation in potentiostatic mode....

  20. Reversible solid oxide fuel cells (R-SOFCs) with chemically stable proton-conducting oxides

    KAUST Repository

    Bi, Lei

    2015-07-01

    Proton-conducting oxides offer a promising way of lowering the working temperature of solid oxide cells to the intermediate temperate range (500 to 700. °C) due to their better ionic conductivity. In addition, the application of proton-conducting oxides in both solid oxide fuel cells (SOFCs) and sold oxide electrolysis cells (SOECs) provides unique advantages compared with the use of conventional oxygen-ion conducting conductors, including the formation of water at the air electrode site. Since the discovery of proton conduction in some oxides about 30. years ago, the development of proton-conducting oxides in SOFCs and SOECs (the reverse mode of SOFCs) has gained increased attention. This paper briefly summarizes the development in the recent years of R-SOFCs with proton-conducting electrolytes, focusing on discussing the importance of adopting chemically stable materials in both fuel cell and electrolysis modes. The development of electrode materials for proton-conducting R-SOFCs is also discussed. © 2015 Elsevier B.V.

  1. Solid Oxide Electrolysis for Oxygen Production in an ARS Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Paragon Space Development Corporation proposes an innovative, efficient and practical concept that utilizes Solid Oxide Electrolysis for regenerative air...

  2. Solid oxide fuels cells past present and future perspectives for SOFC technologies

    CERN Document Server

    Irvine, John TS

    2012-01-01

    Solid Oxide Fuel Cells (SOFCs) operate at high temperatures allowing more fuel flexibility and also useful heat output and so increase total efficiency, but does give some interesting engineering challenges. Solid Oxide Fuels Cells: Facts and Figures provides clear and accurate data for a selection of SOFC topics from the specific details of Ni cermet anodes, chemical expansion in materials, and the measuring and modelling of mechanical stresses, to the broader scope of the history and present design of cells, to SOFC systems and the future of SOFC. Celebrating Ulf Bossel s work on Solid Oxide

  3. Solid lubricant materials for high temperatures: A review

    Science.gov (United States)

    Sliney, Harold E.

    1985-01-01

    Solid lubricants that can be used above 300 C in air are discussed, including coatings and self-lubricating composite bearing materials. The lubricants considered are representative dichalcogenides, graphite, graphite fluoride, polyimides, soft oxides, oxidatively stable fluorides, and hard coating materials. A few general design considerations revelant to solid lubrication are interspersed.

  4. Durable solid oxide electrolysis cells and stacks

    Energy Technology Data Exchange (ETDEWEB)

    Ming Chen

    2010-08-15

    The purpose of this project was to make a substantial contribution to development of a cost competitive electrolysis technology based on solid oxide cells. The strategy was to address what had been identified as the key issues in previous research projects. Accordingly five lines of work were carried out in the here reported project: 1) Cell and stack element testing and post test characterization to identify major degradation mechanisms under electrolysis operation. 2) Development of interconnects and coatings to allow stable electrolysis operation at approx850 deg. C or above. 3) Development of seals with reduced Si emission. 4) Development of durable SOEC cathodes. 5) Modeling. Good progress has been made on several of the planned activities. The outcome and most important achievements of the current project are listed for the five lines of the work. (LN)

  5. Solid oxide fuel cell process and apparatus

    Science.gov (United States)

    Cooper, Matthew Ellis [Morgantown, WV; Bayless, David J [Athens, OH; Trembly, Jason P [Durham, NC

    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.

  6. Interconnection of bundled solid oxide fuel cells

    Science.gov (United States)

    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.

  7. Tubular solid oxide fuel cell demonstration activities

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Solid oxide fuel cell power system development

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, Rick [Delphi Automotive Systems, LLC., Troy, MI (United States); Wall, Mark [Independent Energy Partners Technology, LLC., Parker, CO (United States); Sullivan, Neal [Colorado School of Mines, Golden, CO (United States)

    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.

  9. Investigation of solid organic waste processing by oxidative pyrolysis

    Science.gov (United States)

    Kolibaba, O. B.; Sokolsky, A. I.; Gabitov, R. N.

    2017-11-01

    A thermal analysis of a mixture of municipal solid waste (MSW) of the average morphological composition and its individual components was carried out in order to develop ways to improve the efficiency of its utilization for energy production in thermal reactors. Experimental studies were performed on a synchronous thermal analyzer NETZSCH STA 449 F3 Jupiter combined with a quadrupole mass spectrometer QMC 403. Based on the results of the experiments, the temperature ranges of the pyrolysis process were determined as well as the rate of decrease of the mass of the sample of solid waste during the drying and oxidative pyrolysis processes, the thermal effects accompanying these processes, as well as the composition and volumes of gases produced during oxidative pyrolysis of solid waste and its components in an atmosphere with oxygen content of 1%, 5%, and 10%. On the basis of experimental data the dependences of the yield of gas on the moisture content of MSW were obtained under different pyrolysis conditions under which a gas of various calorific values was produced.

  10. Thin-film solid-oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Tracking reactive intermediates by FTIR monitoring of reactions in low-temperature sublimed solids: nitric oxide disproportionation mediated by ruthenium(II) carbonyl porphyrin Ru(TPP)(CO).

    Science.gov (United States)

    Azizyan, Arsen S; Kurtikyan, Tigran S; Martirosyan, Garik G; Ford, Peter C

    2013-05-06

    Interaction of NO ((15)NO) with amorphous layers of Ru(II) carbonyl porphyrin (Ru(TPP)(CO), TPP(2-) = meso-tetraphenylporphyrinato dianion) was monitored by FTIR spectroscopy from 80 K to room temperature. An intermediate spectrally characterized at very low temperatures (110 K) with ν(CO) at 2001 cm(-1) and ν(NO) at 1810 cm(-1) (1777 cm(-1) for (15)NO isotopomer) was readily assigned to the mixed carbonyl-nitrosyl complex Ru(TPP)(CO)(NO), which is the logical precursor to CO labilization. Remarkably, Ru(TPP)-mediated disproportionation of NO is seen even at 110 K, an indication of how facile this reaction is. By varying the quantity of supplied NO, it was also demonstrated that the key intermediate responsible for NO disproportionation is the dinitrosyl complex Ru(TPP)(NO)2, supporting the conclusion previously made from solution experiments.

  12. Analysis of equilibrium and kinetic models of internal reforming on solid oxide fuel cell anodes: Effect on voltage, current and temperature distribution

    Science.gov (United States)

    Ahmed, Khaliq; Fӧger, Karl

    2017-03-01

    The SOFC is well-established as a high-efficiency energy conversion technology with demonstrations of micro-CHP systems delivering 60% net electrical efficiency [1]. However, there are key challenges in the path to commercialization. Foremost among them is stack durability. Operating at high temperatures, the SOFC invariably suffers from thermally induced material degradation. This is compounded by thermal stresses within the SOFC stack which are generated from a number of interacting factors. Modelling is used as a tool for predicting undesirable temperature and current density gradients. For an internal reforming SOFC, fidelity of the model is strongly linked to the representation of the fuel reforming reactions, which dictate species concentrations and net heat release. It is critical for simulation of these profiles that the set of reaction rate expressions applicable for the particular anode catalyst are chosen in the model. A relatively wide spectrum of kinetic correlations has been reported in the literature. This work presents a comparative analysis of the internal distribution of temperature, current, voltage and compositions on a SOFC anode, using various combinations of reaction kinetics and equilibrium expressions for the reactions. The results highlight the significance of the fuel reforming chemistry and kinetics in the prediction of cell performance.

  13. Kinetic Studies on State of the Art Solid Oxide Cells

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Introduction The Solid Oxide Fuel Cell (SOFC), which converts hydrogen as well as hydrocarbon fuels directly into electricity, has demonstrated almost comparable performance when operated reversely as Solid Oxide Electrolyser Cell (SOEC) for electrical energy storage as fuels. In both application...

  14. Low Temperature Oxidation of Methane: The Influence of Nitrogen Oxides

    DEFF Research Database (Denmark)

    Bendtsen, Anders Broe; Glarborg, Peter; Dam-Johansen, Kim

    2000-01-01

    An experimental investigation of methane oxidation in the presence of NO and NO2 has been made in an isothermal plug-flow reactor at 750-1250K. The temperature for on-set of oxidation was lowered by 250 K in the presence of NO or NO2 at residence times of 200 ms. At shorter residence times (140 ms......) this enhancement effect is reduced for NO but maintained for NO2. Furthermore two temperature regimes of oxidation separated by an intermediate regime where only little oxidation takes place exist at residence times of 140 ms, if NO is the only nitrogen oxide initially present. The results were explained...

  15. A high-performance, cobalt-free cathode for intermediate-temperature solid oxide fuel cells with excellent CO2 tolerance

    Science.gov (United States)

    Bu, Yun-fei; Zhong, Qin; Chen, Dong-Chang; Chen, Yu; Lai, Samson Yuxiu; Wei, Tao; Sun, Hai-bin; Ding, Dong; Liu, Meilin

    2016-07-01

    Compared with some cobalt-rich cathodes which have been proven to yield high performance in SOFCs, interest in cobalt-free cathodes has increased due to their reduced thermal expansion coefficients (TECs), high structural stability, and CO2 tolerance. In this report, a new robust Co-free complex perovskite oxide PrLa0.4Ba0.6Fe0.8Zn0.2O5+δ (PLBFZ) has been synthesized and evaluated. The TEC is 14.4 × 10-6 K-1. With the introduction of Sm0.2Ce0.8O2 (SDC), the composite cathode PLBFZ-SDC with a mass ratio of 7:3 (PLBFZ-SDC 73) exhibited the best electrocatalytic activity for oxygen reduction under OCV conditions, with polarization values of 0.044, 0.079, 0.124, 0.251, 0.572, and 1.297 Ω cm-2 at 800, 750, 700, 650, 600, and 550 °C, respectively. The power densities of the cell were 1309, 1079, 788 and 586 mW cm-2 at 750, 700, 650, and 600 °C, respectively. Moreover, it appears to have good stability in air containing 1% CO2 (volume ratio) for 150 h based on Raman and polarization resistance (Rp) analysis. These results suggest that PLBFZ and its SDC composite are promising cathodes for IT-SOFCs.

  16. Strength of an electrolyte supported solid oxide fuel cell

    Science.gov (United States)

    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).

  17. A detailed study of Au-Ni bimetal synthesized by the phase separation mechanism for the cathode of low-temperature solid oxide fuel cells

    Science.gov (United States)

    Yang, Tao; Rodrigues de Almeida, Carlos Manuel; Ramasamy, Devaraj; Almeida Loureiro, Francisco José

    2014-12-01

    A facile co-reduction and annealing synthesis route of nanospheric particles of Au-Ni bimetal with adjustable composition was developed. In a typical synthesis, a direct co-reduction of HAuCl4.4H2O and NiCl2 in aqueous solution was performed with the assistance of reductive NaBH4 and an anionic surfactant sodium dodecyl sulfate (SDS) functioned as the structure-directing agent. Ultrasonic mixing was used at the same time to control the size of the particles. The morphology, microstructure and the state of the surface atoms were analyzed in detail. These nanospheres showed enhanced electrocatalytic activity towards oxygen reduction reaction than that of pure Au nanoparticles, demonstrated in the low temperature SOFC as cathode. The maximum power density generated is 810 mW cm-2 at 550 °C. This is a promising route of taking advantages the Phase Separation Mechanism to greatly reduce the use of noble metals in the ORR field without sacrificing the electrocatalytic activity.

  18. Low-temperature preparation by polymeric complex solution synthesis of Cu-Gd-doped ceria cermets for solid oxide fuel cells anodes: Sinterability, microstructures and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Tartaj, J.; Moure, A. [Instituto de Ceramica y Vidrio (CSIC), Electroceramics Department, Kelsen 5, 28049 Madrid (Spain); Gil, V. [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, Pedro Cerbuna 12, E-50009 Zaragoza (Spain)

    2010-05-01

    A homogeneous dispersion of fine CuO in a gadolinia-doped ceria (CGO) ceramic matrix by the polymeric organic complex solution method has been achieved. Highly sinterable powders were prepared by this method after calcining the precursor at 600 C and attrition milled. The powders consist of individual particles of few tens of nanometer in size with a low agglomeration state. The isopressed compacts were sintered in air at 1000 C and reducing in N{sub 2} 90%-H{sub 2} 10% atmosphere to form Cu-CGO cermets. The microstructures showed a uniform distribution of porous metallic Cu particles surrounded by microporous spaces. The influence of Cu content in Cu-CGO cermets on the electrode performance has been investigated in order to create the most suitable microstructure. The electrical properties of Cu-CGO cermets have been also studied using impedance spectroscopy, in the temperature range form 150 to about 700 C in argon atmosphere. These measurements determined a high value of electrical conductivity at 700 C, similar to that corresponded to pure metallic cupper. (author)

  19. A combined SEM and CV Study of Solid Oxide Fuel Cell Interconnect Steels

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent; Ofoegbu, Stanley; Mikkelsen, Lars

    2012-01-01

    Scanning electron microscopy and cyclic voltammetry were used to investigate the high temperature oxidation behavior of two solid oxide fuel cell interconnect steels. One alloy had a low content of manganese; the other alloy had a high content of manganese. Four reduction and four oxidation peaks...... were observed in the voltammograms of the low manganese alloy at a temperature of 800 oC. The voltammograms of the alloy with a high content of manganese were different. At 600 oC three reduction peaks and two oxidation peaks were observed. At 800 oC additional peaks were observed in the voltammogram...... for this alloy....

  20. Modeling Degradation in Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Topology Optimization of Solid Oxide Fuel Cells

    Science.gov (United States)

    Panagakos, Grigorios; Okkels, Fridolin

    2010-11-01

    We present a free form optimization of Solid Oxide Fuel Cell models, using a high-level implementation of topology optimization according to [1]. As a first step towards the cell's full optimization, we focus in the design of the interconnect. The interconnect is a key element of the whole cell as it is responsible for separating the anode of one cell from the cathode of its next one in a stack of cells, thus being responsible for the supply of fuel and cooling gases, securing in the same time the efficient conductance of electrons through the stack. Modeling the steady-state operation of a fuel cell incorporates the coupling between different physics, such as reaction, electronic, ionic, thermal and fluid phenomena, and is adequately described in two dimensions. Different objective functions, guiding the optimization method, are being investigated, such like the cell's and interconnect's efficiency, heat convection rate and the inlet flowrates of fuel and cooling gases. [4pt] [1] L.H. Olesen, F. Okkels, and H. Bruus, Int. J. Num. Meth. Eng. 65, 975 (2006).

  2. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    Hybrid direct carbon fuel cells (HDCFCs) consisting of a solid carbon (carbon black)-molten carbonate ((62-38 wt% Li-K)2CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell (SOFC)-type full-cell (NiO-yttria-stablized zirconia (YSZ)|YSZ|lanthanum strontium manganite (LSM...... data as a function of temperature, anode and cathode atmospheres, and their flow rates are discussed. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4, Fig. 1) and doped-ceria (CeO2, Ce1-xGdxO2, Ce1-x...... in the carbon-carbonate mixture in the anode chamber of an HDCFC. 96-4 vol% N2-CO2 (anode), air (cathode), 755°C, 0-600 mA, 50 mA/step. Power density corrected to cathode geometric surface area. [Formula]...

  3. Low-temperature synthesis of high-melting point metal non-oxide fine powders. Solid state reaction synthesis using active metal and similarity of crystal structure; Koyuten kinzoku hisankabutsu bifunmatsu no teion gosei. Kassei kinzoku to kessho kozo no ruijisei wo riyoshita koso hanno gosei

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, H.; Mitamura, T. [Saitama University, Saitama (Japan). Faculty of Engineering

    1997-11-01

    This paper describes the low-temperature synthesis of metal non-oxide fine powders as fine ceramics. Precursors of the metal non-oxide are prepared using the lower oxide synthesized in oxidation-reduction reaction between metal oxide and active metal and the similarity of crystal structure to the target. The metal non-oxide can be synthesized by extracting oxygen from the precursors using active metal. For example, in the case of synthesis of TiN powders from TiO2-Mg-N2 gaseous system by the thermit method, {alpha}-Ti is synthesized through reduction reaction of TiO2 using active metal Mg via lower oxide of Ti, TiO. Crystal structure of the intermediate TiO is cubic system which is the same as the target TiN. Complete solid solution is formed from TiO and TiN. TiO can be recognized as an active intermediate of the synthesis of TiN. The precursor is prepared by injecting nitrogen into the lattice of TiO for making solid solution. When oxygen is extracted in the form of MgO using Mg, TiN with cubic system structure can be synthesized at lower temperature than the conventional method. Synthesis by the halogenide method is also described. 50 refs., 11 figs., 1 tab.

  4. Low Temperature Synthesis and Properties of Gadolinium-Doped Cerium Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Machado, M. F. S.; Moraes, L. P. R.; Monteiro, N. K.

    2017-01-01

    Gadolinium-doped cerium oxide (GDC) is an attractive ceramic material for solid oxide fuel cells (SOFCs) both as the electrolyte and in composite electrodes operating at low and intermediate temperatures. GDC exhibits high oxygen ion conductivity at a wide range of temperatures and displays a hig...

  5. Alternative anode materials for methane oxidation in solid oxide fuel cells

    OpenAIRE

    Sfeir, Joseph; Grätzel, Michael

    2005-01-01

    Fuel Cells are electrochemical devices that are able to directly convert chemical energy to electrical energy, without any Carnot limitation. Hence, their energy efficiencies are relatively high. Among the various types of fuel cells, solid oxide fuel cells (SOFC) are operated at high temperatures and in principle can run on various fuels such as natural gas and hydrogen. As natural gas is sought to become one of the main fuels of the next decades, its direct feed to a SOFC is desirable as th...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. AlliedSignal solid oxide fuel cell technology

    Energy Technology Data Exchange (ETDEWEB)

    Minh, N.; Barr, K.; Kelly, P.; Montgomery, K. [AlliedSignal Aerospace Equipment Systems, Torrance, CA (United States)

    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.

  9. Novel nano-network cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Fei [Laboratory for Renewable Clean Energy, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, Anhui (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Wang, Zhiyong; Liu, Mingfei; Zhang, Lei; Xia, Changrong [Laboratory for Renewable Clean Energy, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, Anhui (China); Chen, Fanglin [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2008-10-15

    A novel nano-network of Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}} (SSC) is successfully fabricated as the cathodes for intermediate-temperature solid oxide fuel cells (SOFCs) operated at 500-600 C. The cathode is composed of SSC nanowires formed from nanobeads of less than 50 nm thus exhibiting high surface area and porosity, forming straight path for oxygen ion and electron transportation, resulting in high three-phase boundaries, and consequently showing remarkably high electrode performance. An anode-supported cell with the nano-network cathode demonstrates a peak power density of 0.44 W cm{sup -2} at 500 C and displays exceptional performance with cell operating time. The result suggests a new direction to significantly improve the SOFC performance. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    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.

  11. Technoeconomy of different solid oxide fuel cell based hybrid cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    Gas turbine, steam turbine and heat engine (Stirling engine) is used as bottoming cycle for a solid oxide fuel cell plant to compare different plants efficiencies, CO2 emissionsand plants cost in terms of $/kW. Each plant is then integrated with biomass gasification and finally six plants...... configurations are compared with each other. Technoeconomy is used when calculating the cost if the plants. It is found that when a solid oxide fuel cell plant is combined with a gas turbine cycle then the plant efficiency will be the highest one while if a biomass gasification plant is integrated...... with these hybrid cycles then integrated biomass gasification with solid oxide fuel cell and steam cycle will have the highest plant efficiency. The cost of solid oxide fuel cell with steam plant is found to be the lowest one with a value of about 1030$/kW....

  12. Silicon Carbide Nanotube Oxidation at High Temperatures

    Science.gov (United States)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

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

    Science.gov (United States)

    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.

  14. A review of liquid metal anode solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    ALIYA TOLEUOVA

    2013-06-01

    Full Text Available This review discusses recent advances in a solid oxide fuel cell (SOFC variant that uses liquid metal electrodes (anodes with the advantage of greater fuel tolerance and the ability to operate on solid fuel. Key features of the approach are discussed along with the technological and research challenges that need to be overcome for scale-up and commercialisation.

  15. Solid oxide fuel cell material research in SICCAS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.; Ye, X.; Zen, F.; Li, J.; Shi, J.; Wen, T. [Chinese Academy of Sciences, Shanghai Inst. of Ceramics, Shanghai (China). CAS Key Laboratory of Materials for Energy Conversion

    2010-07-01

    A fuel cell is a device that transfers the chemical energy of fuels directly to electricity. Because its high operating temperature enables the further application of the co-generated heat, the solid oxide fuel cell (SOFC) has the highest efficiency in different types of fuel cells. SICCAS has almost 15 years of experience in the research, development and manufacture of planar type SOFCs. In order to reduce the cost, extend the life time, and propel the commercialization of SOFCs, the company is now focusing on intermediate temperature SOFCs following an international tendency in this direction. Two options for reducing the operating temperatures involve decreasing the thickness of the electrolyte or adopting new materials with higher conductivity. This paper presented a study that used both these methods to make nickel (Ni)/yttria stabilized zirconia (YSZ) anode supported scandia-stabilized zirconia electrolyte composite membranes, using an astrocyte-derived extracellullar matrix (ASECM) with the tape casting technique. In order to evaluate various cathodes, single cells were also constructed on the ASECM. It was concluded that a cell with LBSM-GDC cathode could exhibit good activity, and the output power density reached 0.738W/cm2 at 750 degrees Celsius.

  16. Macro Level Modeling of a Tubular Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Farshid Zabihian

    2010-11-01

    Full Text Available This paper presents a macro-level model of a solid oxide fuel cell (SOFC stack implemented in Aspen Plus® for the simulation of SOFC system. The model is 0-dimensional and accepts hydrocarbon fuels such as reformed natural gas, with user inputs of current density, fuel and air composition, flow rates, temperature, pressure, and fuel utilization factor. The model outputs the composition of the exhaust, work produced, heat available for the fuel reformer, and electrochemical properties of SOFC for model validation. It was developed considering the activation, concentration, and ohmic losses to be the main over-potentials within the SOFC, and mathematical expressions for these were chosen based on available studies in the literature. The model also considered the water shift reaction of CO and the methane reforming reaction. The model results were validated using experimental data from Siemens Westinghouse. The results showed that the model could capture the operating pressure and temperature dependency of the SOFC performance successfully in an operating range of 1–15 atm for pressure and 900 °C–1,000 °C for temperature. Furthermore, a sensitivity analysis was performed to identify the model constants and input parameters that impacted the over-potentials.

  17. Metal Interconnects for Solid Oxide Fuel Cell Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. High temperature heterogeneous reaction kinetics and mechanisms of tungsten oxidation

    Science.gov (United States)

    Sabourin, Justin L.

    energy systems. The primary application for this research topic is the migration of erosion processes in solid rocket motor nozzles. Since oxidation is the primary erosion mechanism of tungsten based nozzles, mitigation of this process through improved comprehension of the chemical mechanisms will increase performance of future rocket systems. In this dissertation, results of the high temperature reaction rates of bulk tungsten are studied using TG analysis in oxidizing atmospheres of O2, CO2, and H2O using helium (He) as an inert carrier gas. Isothermal reaction rates were determined at temperatures up to 1970 K, and oxidizing species partial pressures up to 64.6 torr. Kinetic parameters such as activation energies, frequency factors, and pressure exponents were determined for each reactive system. An important contribution of this work was quantifying the effects of carbon monoxide (CO) on the CO2 reaction, and hydrogen (H2) on the H2O reaction. In both cases the non-oxidizing species significantly reduced oxidation rates. Results have led to new interpretations and thought processes for limiting nozzle erosion in rocket motors. Combined with the TG analysis, as well as recent theoretical interpretations of reaction thermodynamics and kinetics, a new mechanism for tungsten and O2 oxidation has been developed using a one-dimensional numerical model of the TG flow reactor. Important chemical processes and species are also identified for reaction systems involving H2O and CO2. In the future, additional studies are needed to improve our understanding of these chemical species and processes so that more advanced kinetic mechanisms may be developed. In addition to a detailed analysis of high temperature tungsten corrosion processes, synthetic graphite corrosion processes are studied in detail as well. Details of these studies are presented in an attached appendix of this dissertation. These studies considered not only oxidation processes, but decomposition of synthetic

  19. Aerobic Oxidation of 5-(Hydroxymethyl)furfural in Ionic Liquids with Solid Ruthenium Hydroxide Catalysts

    DEFF Research Database (Denmark)

    Ståhlberg, Tim Johannes Bjarki; Eyjolfsdottir, Ester; Gorbanev, Yury

    2012-01-01

    The aerobic oxidation of 5-(hydroxymethyl)furfural was investigated over solid ruthenium hydroxide catalysts in ionic liquids at elevated temperatures and pressures. Several different catalyst supports were tested in combination with various ionic liquids. The best result was obtained in [EMIm...

  20. Durability of Solid Oxide Electrolysis Cell and Interconnects for Steam Electrolysis

    DEFF Research Database (Denmark)

    Sun, Xiufu; Chen, Ming; Liu, Yi-Lin

    2013-01-01

    Durability of a solid oxide electrolysis cell tested at -1.5A / cm2 for high temperature steam electrolysis was investigated in the present work under stack relevant conditions. Detailed electrochemical and microstructural analyses were carried out. The results show that both the hydrogen...... and interconnects on cell degradation under harsh electrolysis conditions is further discussed....

  1. Ab initio Defect Energetics in LaBO3 Perovskite Solid Oxide Fuel Cell Materials

    DEFF Research Database (Denmark)

    Lee, Yueh-Lin; Morgan, Dane; Kleis, Jesper

    2009-01-01

    Perovskite materials of the form ABO3 are a promising family of compounds for use in solid oxide fuel cell (SOFC) cathodes. Study of the physics of these compounds under SOFC conditions with ab initio methods is particularly challenging due to high temperatures, exchange of oxygen with O2 gas...

  2. Integration of a municipal solid waste gasification plant with solid oxide fuel cell and gas turbine

    DEFF Research Database (Denmark)

    Bellomare, Filippo; Rokni, Masoud

    2013-01-01

    in landfills. A Municipal Solid Waste Gasification Plant Integrated with Solid Oxide Fuel Cell (SOFC) and Gas Turbine (GT) has been studied and the plant is called IGSG (Integrated Gasification SOFC and GT). Gasification plant is fed by MSW to produce syngas by which the anode side of an SOFC is fed wherein...

  3. Yttria-stabilized zirconia solid oxide electrolyte fuel cells: Monolithic solid oxide fuel cells

    Science.gov (United States)

    1990-10-01

    The monolithic solid oxide fuel cell (MSOFC) is currently under development for a variety of applications including coal-based power generation. The MSOFC is a design concept that places the thin components of a solid oxide fuel cell in lightweight, compact, corrugated structure, and so achieves high efficiency and excellent performance simultaneously with high power density. The MSOFC can be integrated with coal gasification plants and is expected to have high overall efficiency in the conversion of the chemical energy of coal to electrical energy. This report describes work aimed at: (1) assessing manufacturing costs for the MSOFC and system costs for a coal-based plant; (2) modifying electrodes and electrode/electrolyte interfaces to improve the electrochemical performance of the MSOFC; and (3) testing the performance of the MSOFC on hydrogen and simulated coal gas. Manufacturing costs for both the coflow and crossflow MSOFC's were assessed based on the fabrication flow charts developed by direct scaleup of tape calendering and other laboratory processes. Integrated coal-based MSOFC systems were investigated to determine capital costs and costs of electricity. Design criteria were established for a coal-fueled 200-Mw power plant. Four plant arrangements were evaluated, and plant performance was analyzed. Interfacial modification involved modification of electrodes and electrode/electrolyte interfaces to improve the MSOFC electrochemical performance. Work in the cathode and cathode/electrolyte interface was concentrated on modification of electrode porosity, electrode morphology, electrode material, and interfacial bonding. Modifications of the anode and anode/electrolyte interface included the use of additives and improvement of nickel distribution. Single cells have been tested for their electrochemical performance. Performance data were typically obtained with humidified H2 or simulated coal gas and air or oxygen.

  4. Partial oxidation of methane (POM) assisted solid oxide co-electrolysis

    Science.gov (United States)

    Chen, Fanglin; Wang, Yao

    2017-02-21

    Methods for simultaneous syngas generation by opposite sides of a solid oxide co-electrolysis cell are provided. The method can comprise exposing a cathode side of the solid oxide co-electrolysis cell to a cathode-side feed stream; supplying electricity to the solid oxide co-electrolysis cell such that the cathode side produces a product stream comprising hydrogen gas and carbon monoxide gas while supplying oxygen ions to an anode side of the solid oxide co-electrolysis cell; and exposing the anode side of the solid oxide co-electrolysis cell to an anode-side feed stream. The cathode-side feed stream comprises water and carbon dioxide, and the anode-side feed stream comprises methane gas such that the methane gas reacts with the oxygen ions to produce hydrogen and carbon monoxide. The cathode-side feed stream can further comprise nitrogen, hydrogen, or a mixture thereof.

  5. In situ Reduction and Oxidation of Nickel from Solid Oxide Fuel Cells in a Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Faes, Antonin; Jeangros, Quentin; Wagner, Jakob Birkedal

    2009-01-01

    Environmental transmission electron microscopy was used to characterize in situ the reduction and oxidation of nickel from a Ni/YSZ solid oxide fuel cell anode support between 300-500{degree sign}C. The reduction is done under low hydrogen pressure. The reduction initiates at the NiO/YSZ interface...... are formed on the nickel surface. The crystallites fill up the nickel porosity and create an inhomogeneous structure with remaining voids. This change in structure causes the nickel oxide to expand during a RedOx cycle......., then moves to the center of the NiO grain. At higher temperature the reduction occurs also at the free NiO surface and the NiO/NiO grain boundaries. The growth of Ni is epitaxial on its oxide. Due to high volume decrease, nanopores are formed during reduction. During oxidation, oxide nanocrystallites...

  6. One new route to optimize the oxidation resistance of TiC/hastelloy (Ni-based alloy) composites applied for intermediate temperature solid oxide fuel cell interconnect by increasing graphite particle size

    Science.gov (United States)

    Qi, Qian; Liu, Yan; Wang, Lujie; Zhang, Hui; Huang, Jian; Huang, Zhengren

    2017-09-01

    TiC/hastelloy composites with suitable thermal expansion and excellent electrical conductivity are promising candidates for IT-SOFC interconnect. In this paper, the TiC/hastelloy composites are fabricated by in-situ reactive infiltration, and the oxidation resistance of composites is optimized by increasing graphite particle size. Results show that the increase of graphite particles size from 1 μm to 40 μm reduces TiC particle size from 2.68 μm to 2.22 μm by affecting the formation process of TiC. Moreover, the decrease of TiC particles size accelerates the fast formation of dense and continuous TiO2/Cr2O3 oxide layer, which bring down the mass gain (800 °C/100 h) from 2.03 mg cm-2 to 1.18 mg cm-2. Meanwhile, the coefficient of thermal expansion decreases from 11.15 × 10-6 °C-1 to 10.80 × 10-6 °C-1, and electrical conductivity maintains about 5800 S cm-1 at 800 °C. Therefore, the decrease of graphite particle size is one simple and effective route to optimize the oxidation resistance of composites, and meantime keeps suitable thermal expansion and good electrical conductivity.

  7. High Temperature Solid State Lithium Battery Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reliable energy systems with high energy density capable of operating at high temperatures, pressures and radiation levels are needed for certain NASA missions....

  8. Hydrocarbon oxidation at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Warnatz, J.

    1983-11-01

    In this review it is described how, by suitable separation and elimination of unimportant reactions, a mechanism is developed with the aid of the present kinetic data for the elementary reactions involved. This mechanism explains, without fitting, the currently available experimental results for laminar premixed flames of alkanes, alkenes and acetylene. These experimental results are simulated by the solution of the corresponding conservation equations with suitable models describing diffusion and heat conduction in the multicomponent mixture considered. In lean and moderately rich flames the hydrocarbon is attacked by O, H, and OH in the first step. These radicals are produced by the chain-branching steps of the oxyhydrogen reaction. The alkyl radicals formed in this way always decompose to smaller alkyl radicals by fast thermal elimination of alkenes. Only the relatively slow thermal decomposition of the smallest alkyl radicals (CH/sub 3/ and C/sub 2/H/sub 5/) competes with recombination and with oxidation reactions by O atoms and O/sub 2/. This part of the mechanism is rate-controlling in the combustion of alkanes and alkenes, and is therefore the reason for the similarity of all alkane and alkene flames.

  9. The study of flow and proton exchange interactions in the cylindrical solid oxide fuel cell

    CERN Document Server

    Saievar-Iranizad, E

    2002-01-01

    The solid oxide fuel cell operates at high temperature of about 1000 deg C. In this temperature, some known materials such as Ni, ... which is abundant in the nature, can be used as a catalyst in the electrodes. The electrolytes of such cell solid oxide fuel cell can be made through non-porous solid ceramics such as Zircon's (ZrO sub 2). It can be stabilized using a doped Yttrium oxide. The importance of Yttria-stabilised Zirconia at high temperature belongs to the transport of oxygen ions through the electrolyte. Oxygen using in the hot cathode side causes a considerable reduction in the concentration of oxygen molecules. The oxygen ions exchange through the electrolyte relates to the molecular oxygen concentration gradient between the anode and cathode. Applying fuels such as hydrogen or natural gas in the anode and its chemical reaction with oxygen ions transfer from cathode through the electrolyte, produce electricity, water and heat. To study the ion exchange and its interaction into solid oxide fuel cel...

  10. Structure of liquid oxides at very high temperatures

    CERN Document Server

    Landron, C; Thiaudiere, D; Price, D L; Greaves, G N

    2003-01-01

    The structural characterization of condensed matter by synchrotron radiation combined with neutron data constitutes a powerful structural tool in material science. In order to investigate refractory liquids at very high temperatures, we have developed a new analysis chamber for performing combined X-ray absorption and diffraction measurements by using laser heating and aerodynamic levitation. A similar system has been designed for neutron experiments. This high temperature equipment presents several advantages: the container does not physically or chemically perturb the sample, heterogeneous nucleation during cooling is suppressed and pollution by the container is removed. This cell can operate under various gas conditions from room temperature up to 3000 deg. C obtained by means of a sealed 125 W CO sub 2 laser. Experiments have been performed at LURE, ESRF and at ISIS. We have studied the local structure around the cations in several liquid and solid oxides. We have shown that high temperature synchrotron d...

  11. Extruded Self-Lubricating Solid For High-Temperature Use

    Science.gov (United States)

    Sliney, H. E.; Waters, W. J.; Soltis, R. F.; Bemis, K.

    1996-01-01

    "EX-212" denotes high-density extruded form of composite solid material self-lubricating over wide range of temperatures. Properties equal or exceed those of powder-metallurgy version of this material. Developed for use in advanced engines at high temperatures at which ordinary lubricants destroyed.

  12. Effective improvement of interface modified strontium titanate based solid oxide fuel cell anodes by infiltration with nano-sized palladium and gadolinium-doped cerium oxide

    NARCIS (Netherlands)

    Hussain, A.M.; Hogh, J.V.T.; Zhang, W.; Blennow, P.; Bonanos, N.; Boukamp, Bernard A.

    2013-01-01

    The development of low temperature solid oxide fuel cell (SOFC) anodes by infiltration of Pd/Gd-doped cerium oxide (CGO) electrocatalysts in Nb-doped SrTiO3 (STN) backbones has been investigated. Modification of the electrode/electrolyte interface by thin layer of spin-coated CGO (400–500 nm)

  13. Durability of solid oxide electrolysis cells for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Hauch, A.; Hoejgaard Jensen, S.; Dalgaard Ebbesen, S.

    2007-05-15

    In the perspective of the increasing interest in renewable energy and hydrogen economy, the reversible solid oxide cells (SOCs) is a promising technology as it has the potential of providing efficient and cost effective hydrogen production by high temperature electrolysis of steam (HTES). Furthermore development of such electrolysis cells can gain from the results obtained within the R and D of SOFCs. For solid oxide electrolysis cells (SOEC) to become interesting from a technological point of view, cells that are reproducible, high performing and long-term stable need to be developed. In this paper we address some of the perspectives of the SOEC technology i.e. issues such as a potential H2 production price as low as 0.71 US dollar/kg H{sub 2} using SOECs for HTES; is there a possible market for the electrolysers? and what R and D steps are needed for the realisation of the SOEC technology? In the experimental part we present electrolysis test results on SOCs that have been optimized for fuel cell operation but applied for HTES. The SOCs are produced on a pre-pilot scale at Risoe National Laboratory. These cells have been shown to have excellent initial electrolysis performance, but the durability of such electrolysis cells are not optimal and examples of results from SOEC tests over several hundreds of hours are given here. The long-term tests have been run at current densities of -0.5 A/cm{sup 2} and -1 A/cm{sup 2}, temperatures of 850 deg. C and 950 deg. C and p(H{sub 2}O)/p(H{sub 2}) of 0.5/0.5 and 0.9/0.1. Long-term degradation rates are shown to be up to 5 times higher for SOECs compared to similar SOFC testing. Furthermore, hydrogen and synthetic fuel production prices are calculated using the experimental results from long-term electrolysis test as input and a short outlook for the future work on SOECs will be given as well. (au)

  14. Stack configurations for tubular solid oxide fuel cells

    Science.gov (United States)

    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.

  15. Advanced methods of solid oxide fuel cell modeling

    CERN Document Server

    Milewski, Jaroslaw; Santarelli, Massimo; Leone, Pierluigi

    2011-01-01

    Fuel cells are widely regarded as the future of the power and transportation industries. Intensive research in this area now requires new methods of fuel cell operation modeling and cell design. Typical mathematical models are based on the physical process description of fuel cells and require a detailed knowledge of the microscopic properties that govern both chemical and electrochemical reactions. ""Advanced Methods of Solid Oxide Fuel Cell Modeling"" proposes the alternative methodology of generalized artificial neural networks (ANN) solid oxide fuel cell (SOFC) modeling. ""Advanced Methods

  16. Room temperature chemical oxidation of delafossite-type oxides

    Energy Technology Data Exchange (ETDEWEB)

    Trari, M.; Toepfer, J.; Doumerc, J.P.; Pouchard, M.; Hagenmuller, P. (Laboratoire de Chimie du Solide du CNRS, Talence (France)); Ammar, A. (Universite Cadi Ayyad, Marrakech (Morocco))

    1994-07-01

    Examination of the delafossite-type structure of CuLaO[sub 2] and CuYO[sub 2] suggests that there is room enough to accommodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu[sup +] into Cu[sup 2+]. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu[sup 2+] is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: Whereas CuLaO[sub 2+x] appears as a single phase, CuYO[sub 2+x] corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported. Comparison is stressed between the oxides obtained at higher temperatures.

  17. Vapor-solid-solid grown Ge nanowires at integrated circuit compatible temperature by molecular beam epitaxy

    Science.gov (United States)

    Zhu, Zhongyunshen; Song, Yuxin; Zhang, Zhenpu; Sun, Hao; Han, Yi; Li, Yaoyao; Zhang, Liyao; Xue, Zhongying; Di, Zengfeng; Wang, Shumin

    2017-09-01

    We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy at the substrate temperature of ˜180 °C, which is compatible with the temperature window for Si-based integrated circuit. Low temperature grown Ge NWs hold a smaller size, similar uniformity, and better fit with Au tips in diameter, in contrast to Ge NWs grown at around or above the eutectic temperature of Au-Ge alloy in the vapor-liquid-solid (VLS) growth. Six ⟨110⟩ growth orientations were observed on Ge (110) by the VSS growth at ˜180 °C, differing from only one vertical growth direction of Ge NWs by the VLS growth at a high temperature. The evolution of NWs dimension and morphology from the VLS growth to the VSS growth is qualitatively explained by analyzing the mechanism of the two growth modes.

  18. Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    Emiliana Fabbri, Daniele Pergolesi and Enrico Traversa

    2010-01-01

    Full Text Available High temperature proton conductor (HTPC oxides are attracting extensive attention as electrolyte materials alternative to oxygen-ion conductors for use in solid oxide fuel cells (SOFCs operating at intermediate temperatures (400–700 °C. The need to lower the operating temperature is dictated by cost reduction for SOFC pervasive use. The major stake for the deployment of this technology is the availability of electrodes able to limit polarization losses at the reduced operation temperature. This review aims to comprehensively describe the state-of-the-art anode and cathode materials that have so far been tested with HTPC oxide electrolytes, offering guidelines and possible strategies to speed up the development of protonic SOFCs.

  19. Solid oxide fuel cell power plant with an anode recycle loop turbocharger

    Science.gov (United States)

    Saito, Kazuo; Skiba, Tommy; Patel, Kirtikumar H.

    2015-07-14

    An anode exhaust recycle turbocharger (100) has a turbocharger turbine (102) secured in fluid communication with a compressed oxidant stream within an oxidant inlet line (218) downstream from a compressed oxidant supply (104), and the anode exhaust recycle turbocharger (100) also includes a turbocharger compressor (106) mechanically linked to the turbocharger turbine (102) and secured in fluid communication with a flow of anode exhaust passing through an anode exhaust recycle loop (238) of the solid oxide fuel cell power plant (200). All or a portion of compressed oxidant within an oxidant inlet line (218) drives the turbocharger turbine (102) to thereby compress the anode exhaust stream in the recycle loop (238). A high-temperature, automotive-type turbocharger (100) replaces a recycle loop blower-compressor (52).

  20. Room-Temperature Performance of Poly(Ethylene Ether Carbonate)-Based Solid Polymer Electrolytes for All-Solid-State Lithium Batteries.

    Science.gov (United States)

    Jung, Yun-Chae; Park, Myung-Soo; Kim, Duck-Hyun; Ue, Makoto; Eftekhari, Ali; Kim, Dong-Won

    2017-12-13

    Amorphous poly(ethylene ether carbonate) (PEEC), which is a copolymer of ethylene oxide and ethylene carbonate, was synthesized by ring-opening polymerization of ethylene carbonate. This route overcame the common issue of low conductivity of poly(ethylene oxide)(PEO)-based solid polymer electrolytes at low temperatures, and thus the solid polymer electrolyte could be successfully employed at the room temperature. Introducing the ethylene carbonate units into PEEC improved the ionic conductivity, electrochemical stability and lithium transference number compared with PEO. A cross-linked solid polymer electrolyte was synthesized by photo cross-linking reaction using PEEC and tetraethyleneglycol diacrylate as a cross-linking agent, in the form of a flexible thin film. The solid-state Li/LiNi0.6Co0.2Mn0.2O2 cell assembled with solid polymer electrolyte based on cross-linked PEEC delivered a high initial discharge capacity of 141.4 mAh g-1 and exhibited good capacity retention at room temperature. These results demonstrate the feasibility of using this solid polymer electrolyte in all-solid-state lithium batteries that can operate at ambient temperatures.

  1. Pressurized solid oxide fuel cell testing

    Energy Technology Data Exchange (ETDEWEB)

    Basel, R.A.; Pierre, J.F.

    1995-08-01

    The goals of the SOFC pressurized test program are to obtain cell voltage versus current (VI) performance data as a function of pressure; to evaluate the effects of operating parameters such as temperature, air stoichiometry, and fuel utilization on cell performance, and to demonstrate long term stability of the SOFC materials at elevated pressures.

  2. Durable and Robust Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Hjalmarsson, Per; Knibbe, Ruth; Hauch, Anne

    for use within the CHP (Combined Heat and Power) market segment with stationary power plants in the range 1 – 250 kWe in mind. Lowered operation temperature is considered a good way to improve the stack durability since corrosion of the interconnect plates in a stack is lifetime limiting at T > 750 °C...

  3. NATO Advanced Research Workshop on Boron Rich Solids Sensors for Biological and Chemical Detection, Ultra High Temperature Ceramics, Thermoelectrics, Armor

    CERN Document Server

    Orlovskaya, Nina

    2011-01-01

    The objective of this book is to discuss the current status of research and development of boron-rich solids as sensors, ultra-high temperature ceramics, thermoelectrics, and armor. Novel biological and chemical sensors made of stiff and light-weight boron-rich solids are very exciting and efficient for applications in medical diagnoses, environmental surveillance and the detection of pathogen and biological/chemical terrorism agents. Ultra-high temperature ceramic composites exhibit excellent oxidation and corrosion resistance for hypersonic vehicle applications. Boron-rich solids are also promising candidates for high-temperature thermoelectric conversion. Armor is another very important application of boron-rich solids, since most of them exhibit very high hardness, which makes them perfect candidates with high resistance to ballistic impact. The following topical areas are presented: •boron-rich solids: science and technology; •synthesis and sintering strategies of boron rich solids; •microcantileve...

  4. Solid Oxide Fuel Cells coupled with a biomass gasification unit

    Directory of Open Access Journals (Sweden)

    Skrzypkiewicz Marek

    2016-01-01

    Full Text Available A possibility of fuelling a solid oxide fuel cell stack (SOFC with biomass fuels can be realized by coupling a SOFC system with a self-standing gasification unit. Such a solution enables multi-fuel operation, elasticity of the system as well as the increase of the efficiency of small-scale biomass-to-electricity conversion units. A system of this type, consisting of biomass gasification unit, gas purification unit, SOFC stack, anode off-gas afterburner and peripherals was constructed and operated successfully. During the process, biomass fuel (wood chips was gasified with air as gasification agent. The gasifier was capable of converting up to 30 kW of fuel to syngas with efficiencies up to 75%. Syngas leaving the gasification unit is delivered to a medium temperature adsorber for sulphur compounds removal. Steam is added to the purified fuel to maintain steam to carbon ratio higher than 2. The syngas then is passed to a SOFC stack through a fuel preheater. In such a configuration it was possible to operate a commercial 1.3 kW stack within its working regime. Conducted tests confirmed successful operation of a SOFC stack fuelled by biomass-sourced syngas.

  5. Potential of Reversible Solid Oxide Cells as Electricity Storage System

    Directory of Open Access Journals (Sweden)

    Paolo Di Giorgio

    2016-08-01

    Full Text Available Electrical energy storage (EES systems allow shifting the time of electric power generation from that of consumption, and they are expected to play a major role in future electric grids where the share of intermittent renewable energy systems (RES, and especially solar and wind power plants, is planned to increase. No commercially available technology complies with all the required specifications for an efficient and reliable EES system. Reversible solid oxide cells (ReSOC working in both fuel cell and electrolysis modes could be a cost effective and highly efficient EES, but are not yet ready for the market. In fact, using the system in fuel cell mode produces high temperature heat that can be recovered during electrolysis, when a heat source is necessary. Before ReSOCs can be used as EES systems, many problems have to be solved. This paper presents a new ReSOC concept, where the thermal energy produced during fuel cell mode is stored as sensible or latent heat, respectively, in a high density and high specific heat material and in a phase change material (PCM and used during electrolysis operation. The study of two different storage concepts is performed using a lumped parameters ReSOC stack model coupled with a suitable balance of plant. The optimal roundtrip efficiency calculated for both of the configurations studied is not far from 70% and results from a trade-off between the stack roundtrip efficiency and the energy consumed by the auxiliary power systems.

  6. Kinetic Studies on State of the Art Solid Oxide Cells

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Graves, Christopher R.; Mogensen, Mogens Bjerg

    2016-01-01

    Electrochemical reaction kinetics at the electrodes of Solid Oxide Cells (SOCs) were investigated at 700 °C for two cells with different fuel electrode microstructures as well as on a third cell with a reduced active electrode area. Three fuel mixtures were investigated – hydrogen/steam and refor...

  7. Viscous sealing glass compositions for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Woon; Brow, Richard K.

    2016-12-27

    A sealant for forming a seal between at least two solid oxide fuel cell components wherein the sealant comprises a glass material comprising B.sub.2O.sub.3 as a principal glass former, BaO, and other components and wherein the glass material is substantially alkali-free and contains less than 30% crystalline material.

  8. Modeling and Structural Optimization of Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Panagakos, Grigorios

    the setup as continuum) and we combine these scripts with the ones containing the optimization routines like the Method of Moving Asymptotes (MMA). Success in obtaining such a design, would greatly affect the overall cell's efficiency rendering the Solid Oxide Fuel Cell more competitive in the sustainable...

  9. Pressurized Operation of a Planar Solid Oxide Cell Stack

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Sun, Xiufu; Ebbesen, Sune Dalgaard

    2016-01-01

    Solid oxide cells (SOCs) can be operated either as fuel cells (SOFC) to convert fuels to electricity or as electrolyzers (SOEC) to convert electricity to fuels such as hydrogen or methane. Pressurized operation of SOCs provide several benefits on both cell and system level. If successfully matured...

  10. Electrochemical characterisation of solid oxide cell electrodes for hydrogen production

    DEFF Research Database (Denmark)

    Bernuy-Lopez, Carlos; Knibbe, Ruth; He, Zeming

    2011-01-01

    Oxygen electrodes and steam electrodes are designed and tested to develop improved solid oxide electrolysis cells for H2 production with the cell support on the oxygen electrode. The electrode performance is evaluated by impedance spectroscopy testing of symmetric cells at open circuit voltage (OCV...

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

    DEFF Research Database (Denmark)

    Harthøj, Anders; Holt, Tobias; Møller, Per

    2015-01-01

    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......, 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...

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

    Science.gov (United States)

    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.

  13. Stability of solid oxide fuel cell materials

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, T.R.; Pederson, L.R.; Stevenson, J.W.; Raney, P.E. [Pacific Northwest Lab., Richland, WA (United States)

    1995-08-01

    The phase stability and sintering behavior of materials used in SOFCs has been evaluated. The sintering behavior of Ca and Sr doped lanthanum. manganite (the preferred SOFC cathode material) is highly dependent on the relative proportion of A and B site cations in the material. Ca and Sr doped lanthanum chromite (the preferred interconnect material) have been shown to rapidly expand in reducing atmospheres at temperatures as low as 700{degrees}C. This expansion is due to the reduction of Cr{sup 4+} to Cr{sup 3+} in reducing environments.

  14. High temperature lithium cells with solid polymer electrolytes

    Science.gov (United States)

    Yang, Jin; Eitouni, Hany Basam; Singh, Mohit

    2017-03-07

    Electrochemical cells that use electrolytes made from new polymer compositions based on poly(2,6-dimethyl-1,4-phenylene oxide) and other high-softening-temperature polymers are disclosed. These materials have a microphase domain structure that has an ionically-conductive phase and a phase with good mechanical strength and a high softening temperature. In one arrangement, the structural block has a softening temperature of about 210.degree. C. These materials can be made with either homopolymers or with block copolymers. Such electrochemical cells can operate safely at higher temperatures than have been possible before, especially in lithium cells. The ionic conductivity of the electrolytes increases with increasing temperature.

  15. Propene oxidation at low and intermediate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Wilk, R.D.; Cernansky, N.P. (Drexel Univ., Philadelphia, PA (USA). Dept. of Mechanical Engineering); Pitz, W.J.; Westbrook, C.K. (Lawrence Livermore National Lab., CA (USA))

    1989-08-01

    A detailed chemical kinetic mechanism for propene oxidation is developed and used to model reactions in a static reactor at temperatures of 530-740 {Kappa}, equivalence ratios of 0.8-2.0, and a pressure of 600 torr. Modeling of hydrocarbon oxidation in this temperature range is important for the validation of detailed models to be used for performing calculations related to automotive engine knock. The model predicted induction periods and species concentrations for all the species and all conditions measured experimentally in the static reactor. Overall, the calculated concentrations of carbon monoxide and acetaldehyde agreed well with those measured. The calculated concentrations of ethene are low compared to the experimental measurements, and the calculated concentrations of the formaldehyde are high. Agreement for concentrations of carbon dioxide, methane, methanol, acrolein, and propene oxide is mixed. The characteristic s-shape of the fuel concentration history is well predicted. Modeling calculations identified some of the key reaction steps at the present conditions. Addition of OH to propene and H-atom abstraction by OH from propene are important steps in determining the subsequent distributions of intermediate products, such as acetaldehyde, acrolein and formaldehyde. Allyl radicals are very abundant in propene oxidation, and the primary steps found to be responsible for their consumption are reaction with HO/sub 2/ and CH/sub 3/O/sub 2/.

  16. MODELING OF TEMPERATURE FIELDS IN A SOLID HEAT ACCUMULLATORS

    Directory of Open Access Journals (Sweden)

    S. S. Belimenko

    2016-10-01

    Full Text Available Purpose. Currently, one of the priorities of energy conservation is a cost savings for heating in commercial and residential buildings by the stored thermal energy during the night and its return in the daytime. Economic effect is achieved due to the difference in tariffs for the cost of electricity in the daytime and at night. One of the most common types of devices that allow accumulating and giving the resulting heat are solid heat accumulators. The main purpose of the work: 1 software development for the calculation of the temperature field of a flat solid heat accumulator, working due to the heat energy accumulation in the volume of thermal storage material without phase transition; 2 determination the temperature distribution in its volumes at convective heat transfer. Methodology. To achieve the study objectives a heat transfer theory and Laplace integral transform were used. On its base the problems of determining the temperature fields in the channels of heat accumulators, having different cross-sectional shapes were solved. Findings. Authors have developed the method of calculation and obtained solutions for the determination of temperature fields in channels of the solid heat accumulator in conditions of convective heat transfer. Temperature fields over length and thickness of channels were investigated. Experimental studies on physical models and industrial equipment were conducted. Originality. For the first time the technique of calculating the temperature field in the channels of different cross-section for the solid heat accumulator in the charging and discharging modes was proposed. The calculation results are confirmed by experimental research. Practical value. The proposed technique is used in the design of solid heat accumulators of different power as well as full-scale production of them was organized.

  17. Fundamental Material Properties Underlying Solid Oxide Electrochemistry

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Hansen, Karin Vels; Holtappels, Peter

    2012-01-01

    in the TPB region. Also, segregations to the surfaces and interfaces of the electrode materials, which may affect the electrode reaction mechanism, are very dependent on the exact history of fabrication and operation. The positive effects of even small concentrations of nanoparticles in the electrodes may...... place. The length of the TPB is a key factor even though the width and depth of the zone, in which the rate limiting reactions take place, may vary depending of the degree of the electrode materials ability to conduct both electrons and ions, i.e. the TPB zone volume depends on how good a mixed ionic......, and the electrochemical reactions take place at elevated temperatures from 300 and up to 1000 C. This has as consequence that the region around the threephase- boundary (TPB), where the electron conducting electrode, the electrolyte and the gas phase reactants meet, is the region where the electrochemical processes take...

  18. Solid Oxide Fuel Cell Stack Diagnostics

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Barfod, Rasmus Gottrup

    . An operating stack is subject to compositional gradients in the gaseous reactant streams, and temperature gradients across each cell and across the stack, which complicates detailed analysis. Several experimental stacks from Topsoe Fuel Cell A/S were characterized using Electrochemical Impedance Spectroscopy...... and discussed in the following. Parallel acquisition using electrochemical impedance spectroscopy can be used to detect possible minor differences in the supply of gas to the individual cells, which is important when going to high fuel utilizations. The fuel flow distribution was determined and provides...... carried out on an experimental 14-cell SOFC stack at varying frequencies and fuel utilizations. The results illustrated that THD can be used to detect increasing non-linearities in the current-voltage characteristics of the stack when the stack suffers from fuel starvation by monitoring the stack sum...

  19. Diffusion of Nickel into Ferritic Steel Interconnects of Solid Oxide Fuel/Electrolysis Stacks

    DEFF Research Database (Denmark)

    Molin, Sebastian; Chen, Ming; Bowen, Jacob R.

    2013-01-01

    this relatively short time all the metallic nickel in the coating has reacted and formed solid solutions with iron and chromium. Diffusion of Ni into the steel causes formation of the austenite FCC phase. The microstructure and composition of the oxide scale formed on the sample surface after 250 hours is similar......Stainless steels are used as interconnects in Solid Oxide Fuel Cell/Electrolysis stacks. Their high temperature corrosion resistance has been studied mainly to describe oxide scale formation processes. Other corrosion/degradation processes may also be of relevance to overall life time, for example...... diffusion of nickel from the Ni/YSZ electrode or the contact layer into the interconnect plate. Such diffusion can cause austenization of the ferritic structure and could possibly alter corrosion properties of the steel. Whereas this process has already been recognized by SOFC stack developers, only...

  20. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2015-03-05

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH) of ethane to ethylene at a relatively low temperature (T<300°C). These catalysts appear to be much more stable than the corresponding composites prepared by other chemical methods; more than 90% of their original intrinsic activity was retained after 50h with time on-stream. Furthermore, the stability was much less affected by the Nb content than in composites prepared by classical "wet" syntheses. These materials, obtained in a solvent-free way, are thus promising green and sustainable alternatives to the current Ni-Nb candidates for the low-temperature ODH of ethane.

  1. Quality Assurance of Solid Oxide Fuel Cell (SOFC) and Electrolyser (SOEC) Stacks

    DEFF Research Database (Denmark)

    Lang, Michael; Auer, Corinna; Couturier, Karine

    2017-01-01

    In the EU-funded project “Solid oxide cell and stack testing and quality assurance” (SOCTESQA) standardized and industry wide test modules and programs for high temperature solid oxide cells and stacks are being developed. These test procedures can be applied for the fuel cell (SOFC......, electrochemical impedance spectroscopy, reactant utilization, reactant gas composition, temperature sensitivity, operation at constant current, operation at varying current, thermal cycling and shut-down. The test modules were validated by comparing the results in terms of repeatability of the different testing......), the electrolysis (SOEC) and in the combined SOFC/SOEC mode. In order to optimize the test modules the project partners have tested identical SOC stacks with the same test programs in several testing campaigns. Altogether 10 pre-normative test modules were developed: Start-up, current-voltage characteristics...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Analysis of anode functional layer for minimizing thermal stress in solid oxide fuel cell

    Science.gov (United States)

    Xie, Jiamiao; Hao, Wenqian; Wang, Fenghui

    2017-10-01

    Two-dimensional (2D) model is used to analyze the thermo-mechanical behavior of anode-supported solid oxide fuel cell for a given thermal loading. In order to reduce the thermal stress generated during the preparation and operation of solid oxide fuel cell, the optimized anode functional layer is introduced into solid oxide fuel cell. In this work, based on the hierarchical model theory, the anode functional layer is divided into several sub-layers. The thickness and NiO volume fraction of each sub-layer gradient change and are controlled by non-linear thickness gradient exponent and non-linear composition gradient exponent, respectively. The optimization schemes are obtained to minimize the anode axial stress, the electrolyte compressive stress and the layer interface stress significantly, and the change trend of the anode axial stress over the entire temperature range is also analyzed. The research in this paper provides theoretical basis for optimizing the anode-supported solid oxide fuel cell.

  5. Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides.

    Science.gov (United States)

    Bi, Lei; Boulfrad, Samir; Traversa, Enrico

    2014-12-21

    Energy crisis and environmental problems caused by the conventional combustion of fossil fuels boost the development of renewable and sustainable energies. H2 is regarded as a clean fuel for many applications and it also serves as an energy carrier for many renewable energy sources, such as solar and wind power. Among all the technologies for H2 production, steam electrolysis by solid oxide electrolysis cells (SOECs) has attracted much attention due to its high efficiency and low environmental impact, provided that the needed electrical power is generated from renewable sources. However, the deployment of SOECs based on conventional oxygen-ion conductors is limited by several issues, such as high operating temperature, hydrogen purification from water, and electrode stability. To avoid these problems, proton-conducting oxides are proposed as electrolyte materials for SOECs. This review paper provides a broad overview of the research progresses made for proton-conducting SOECs, summarizing the past work and finding the problems for the development of proton-conducting SOECs, as well as pointing out potential development directions.

  6. Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides

    KAUST Repository

    Bi, Lei

    2014-01-01

    Energy crisis and environmental problems caused by the conventional combustion of fossil fuels boost the development of renewable and sustainable energies. H2 is regarded as a clean fuel for many applications and it also serves as an energy carrier for many renewable energy sources, such as solar and wind power. Among all the technologies for H2 production, steam electrolysis by solid oxide electrolysis cells (SOECs) has attracted much attention due to its high efficiency and low environmental impact, provided that the needed electrical power is generated from renewable sources. However, the deployment of SOECs based on conventional oxygen-ion conductors is limited by several issues, such as high operating temperature, hydrogen purification from water, and electrode stability. To avoid these problems, proton-conducting oxides are proposed as electrolyte materials for SOECs. This review paper provides a broad overview of the research progresses made for proton-conducting SOECs, summarizing the past work and finding the problems for the development of proton-conducting SOECs, as well as pointing out potential development directions.

  7. Three dimensional CFD modeling and experimental validation of a single chamber solid oxide fuel cell fed by methane

    Science.gov (United States)

    Nguyen, H. T.; Le, M. V.; Nguyen, T. A.; Nguyen, T. A. N.

    2017-06-01

    The solid oxide fuel cell is one of the promising technologies for future energy demand. Solid oxide fuel cell operated in the single-chamber mode exhibits several advantages over conventional single oxide fuel cell due to the simplified, compact, sealing-free cell structure. There are some studies on simulating the behavior of this type of fuel cell but they mainly focus on the 2D model. In the present study, a three-dimensional numerical model of a single chamber solid oxide fuel cell (SOFC) is reported and solved using COMSOL Multiphysics software. Experiments of a planar button solid oxide fuel cell were used to verify the simulation results. The system is fed by methane and oxygen and operated at 700°C. The cathode is LSCF6482, the anode is GDC-Ni, the electrolyte is LDM and the operating pressure is 1 atm. There was a good agreement between the cell temperature and current voltage estimated from the model and measured from the experiment. The results indicate that the model is applicable for the single chamber solid oxide fuel cell and it can provide a basic for the design, scale up of single chamber solid oxide fuel cell system.

  8. The effect of A-site and B-site substitution on BaFeO3-δ: An investigation as a cathode material for intermediate-temperature solid oxide fuel cells

    Science.gov (United States)

    Wang, Jian; Saccoccio, Mattia; Chen, Dengjie; Gao, Yang; Chen, Chi; Ciucci, Francesco

    2015-11-01

    This work systematically investigates the effects of single A-site dopant (5 mol% La3+, Sm3+ and Gd3+) and single B-site dopant (5 mol% Zr4+ and Ce4+) on the structure and oxygen reduction reaction of BaFeO3-δ (BFO) used as a cathode for solid oxide fuel cells. The materials are prepared by solid-state method and their structural, electronic, electrocatalytic properties are characterized and compared. X-ray diffraction reveals 5 mol% A-site or B-site dopant is sufficient to stabilize the cubic phase of BFO, as predicted by the lattice calculation. X-ray photoelectron spectroscopy and iodometric titration demonstrates that neither of the two doping sites has obvious advantage over the other towards the formation of additional oxygen vacancies. B-site doped BFO shows a lower electrical conductivity than A-site doped ones, however, they have much quicker response to electrical conductivity relaxation, likely originating from the expanded lattice size. With the largest oxygen vacancy concentrations, Ba0.95La0.05FeO3-δ and BaFe0.95Zr0.05O3-δ stand out from the A-site and B-site doped BFO, respectively, and polarization resistances of 0.029 Ω cm2 and 0.020 Ω cm2 are achieved at 700 °C, PO2 = 0.2atm. With a similar amount of oxygen vacancies, B-site doping is more advantageous for enhancing oxygen bulk diffusion kinetics, and thus ORR activity.

  9. Next-Generation Electrochemical Energy Materials for Intermediate Temperature Molten Oxide Fuel Cells and Ion Transport Molten Oxide Membranes.

    Science.gov (United States)

    Belousov, Valery V

    2017-02-21

    High temperature electrochemical devices such as solid oxide fuel cells (SOFCs) and oxygen separators based on ceramic materials are used for efficient energy conversion. These devices generally operate in the temperature range of 800-1000 °C. The high operating temperatures lead to accelerated degradation of the SOFC and oxygen separator materials. To solve this problem, the operating temperatures of these electrochemical devices must be lowered. However, lowering the temperature is accompanied by decreasing the ionic conductivity of fuel cell electrolyte and oxygen separator membrane. Therefore, there is a need to search for alternative electrolyte and membrane materials that have high ionic conductivity at lower temperatures. A great many opportunities exist for molten oxides as electrochemical energy materials. Because of their unique electrochemical properties, the molten oxide innovations can offer significant benefits for improving energy efficiency. In particular, the newly developed electrochemical molten oxide materials show high ionic conductivities at intermediate temperatures (600-800 °C) and could be used in molten oxide fuel cells (MOFCs) and molten oxide membranes (MOMs). The molten oxide materials containing both solid grains and liquid channels at the grain boundaries have advantages compared to the ceramic materials. For example, the molten oxide materials are ductile, which solves a problem of thermal incompatibility (difference in coefficient of thermal expansion, CTE). Besides, the outstanding oxygen selectivity of MOM materials allows us to separate ultrahigh purity oxygen from air. For their part, the MOFC electrolytes show the highest ionic conductivity at intermediate temperatures. To evaluate the potential of molten oxide materials for technological applications, the relationship between the microstructure of these materials and their transport and mechanical properties must be revealed. This Account summarizes the latest results on

  10. Functionally Graded Cathodes for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    Hybrid direct carbon fuel cells consisting of a solid carbon (carbon black)-molten carbonate ((62-38 wt% Li-K)(2)CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell type full-cell are tested for their electrochemical performance between 700 and 800 degrees C. Performance...... was investigated using current-potential-power density curves. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4) and dopedceria (CeO2, Ce1-xGdxO2-x/2, Ce1-xRExO2-delta (RE = Pr, Sm)), the effectiveness...

  13. Evaluation of apatite silicates as solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Martin-Sedeno, M.C.; Aranda, M.A.G. [Dpto. de Quimica Inorganica, Universidad Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C.; Nunez, P. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Ramos-Barrado, J.R. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain)

    2010-05-01

    Apatite-type silicates have been considered as promising electrolytes for Solid Oxide Fuel Cells (SOFC); however studies on the potential use of these materials in SOFC devices have received relatively little attention. The lanthanum silicate with composition La{sub 10}Si{sub 5.5}Al{sub 0.5}O{sub 26.75} has been evaluated as electrolyte with the electrode materials commonly used in SOFC, i.e. manganite, ferrite and cobaltite as cathode materials and NiO-CGO composite, chromium-manganite and Sr{sub 2}MgMoO{sub 6} as anode materials. Chemical compatibility, area-specific resistance and fuel cell studies have been performed. X-ray powder diffraction (XRPD) analysis did not reveal any trace of reaction products between the apatite electrolyte and most of the aforementioned electrode materials. However, the area-specific polarisation resistance (ASR) of these electrodes in contact with apatite electrolyte increased significantly with the sintering temperature, indicating reactivity at the electrolyte/electrode interface. On the other hand, the ASR values are significantly improved using a ceria buffer layer between the electrolyte and electrode materials to prevent reactivity. Maximum power densities of 195 and 65 mWcm{sup -2} were obtained at 850 and 700 C, respectively in H{sub 2} fuel, using an 1 mm-thick electrolyte, a NiO-Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} composite as anode and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} as cathode materials. This fuel cell was tested for 100 h in 5%H{sub 2}-Ar atmosphere showing stable performance. (author)

  14. Functionally Graded Cathodes for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Harry Abernathy; Meilin Liu

    2006-12-31

    One primary suspected cause of long-term performance degradation of solid oxide fuels (SOFCs) is the accumulation of chromium (Cr) species at or near the cathode/electrolyte interface due to reactive Cr molecules originating from Cr-containing components (such as the interconnect) in fuel cell stacks. To date, considerable efforts have been devoted to the characterization of cathodes exposed to Cr sources; however, little progress has been made because a detailed understanding of the chemistry and electrochemistry relevant to the Cr-poisoning processes is still lacking. This project applied multiple characterization methods - including various Raman spectroscopic techniques and various electrochemical performance measurement techniques - to elucidate and quantify the effect of Cr-related electrochemical degradation at the cathode/electrolyte interface. Using Raman microspectroscopy the identity and location of Cr contaminants (SrCrO{sub 4}, (Mn/Cr){sub 3}O{sub 4} spinel) have been observed in situ on an LSM cathode. These Cr contaminants were shown to form chemically (in the absence of current flowing through the cell) at temperatures as low as 625 C. While SrCrO{sub 4} and (Mn/Cr){sub 3}O{sub 4} spinel must preferentially form on LSM, since the LSM supplies the Sr and Mn cations necessary for these compounds, LSM was also shown to be an active site for the deposition of Ag{sub 2}CrO{sub 4} for samples that also contained silver. In contrast, Pt and YSZ do not appear to be active for formation of Cr-containing phases. The work presented here supports the theory that Cr contamination is predominantly chemically-driven and that in order to minimize the effect, cathode materials should be chosen that are free of cations/elements that could preferentially react with chromium, including silver, strontium, and manganese.

  15. Rigorous Definition of Oxidation States of Ions in Solids

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Parker, W.G. [Westinghouse Science and Technology Center, Pittsburgh, PA (United States)

    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.

  18. Solid Oxide Electrolysis Cells: Degradation at High Current Densities

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Traulsen, Marie Lund; Hauch, Anne

    2010-01-01

    The degradation of Ni/yttria-stabilized zirconia (YSZ)-based solid oxide electrolysis cells operated at high current densities was studied. The degradation was examined at 850°C, at current densities of −1.0, −1.5, and −2.0 A/cm2, with a 50:50 (H2O:H2) gas supplied to the Ni/YSZ hydrogen electrode...

  19. Oxide based functional materials through solid state and electrochemical synthesis

    OpenAIRE

    Todorova, Vanya

    2010-01-01

    The presented dissertation combines synthesis and characterization techniques of solid state chemistry and electrochemistry. The work is organized into two main parts. The first part deals with the synthesis, structural characterization and investigation of the physical properties of new ternary and quaternary transition metal oxides with layered structures. Several compounds of delafossite structure ABO2 with silver on A position and different trivalent cation capable of adopting an octa...

  20. Coatings on stainless steel for solid oxide fuel cell interconnects

    OpenAIRE

    Clarke, Richard

    2012-01-01

    Enabling inexpensive and ubiquitous steels for use as solid oxide fuel cell interconnects has two major hurdles to overcome. Firstly, corrosion must be limited such that the interconnect can have longevity. Secondly, the evaporation of chromium from the corrosion layer must also be limited such that the fuel cell can have longevity. The evaporation of chromium from chromia, titanium doped chromia, and chromium cobalt spinels was studied and characterized. Spinels lost the least amount of m...

  1. Ionic conductivity studies of solid oxide fuel cell electrolytes and theoretical modeling of an entire solid oxide fuel cell

    Science.gov (United States)

    Pornprasertsuk, Rojana

    Because of the steep increase in oil prices, the global warming effect and the drive for energy independence, alternative energy research has been encouraged worldwide. The sustainable fuels such as hydrogen, biofuel, natural gas, and solar energy have attracted the attention of researchers. To convert these fuels into a useful energy source, an energy conversion device is required. Fuel cells are one of the energy conversion devices which convert chemical potentials into electricity. Due to their high efficiency, the ease to scale from 1 W range to megawatts range, no recharging requirement and the lack of CO2 and NOx emission (if H2 and air/O 2 are used), fuel cells have become a potential candidate for both stationary power generators and portable applications. This thesis has been focused primarily on solid oxide fuel cell (SOFC) studies due to its high efficiency, varieties of fuel choices, and no water management problem. At the present, however, practical applications of SOFCs are limited by high operating temperatures that are needed to create the necessary oxide-ion vacancy mobility in the electrolyte and to create sufficient electrode reactivities. This thesis introduces several experimental and theoretical approaches to lower losses both in the electrolyte and the electrodes. Yttria stabilized zirconia (YSZ) is commonly used as a solid electrolyte for SOFCs due to its high oxygen-ion conductivity. To improve the ionic conductivity for low temperature applications, an approach that involves dilating the structure by irradiation and introducing edge dislocations into the electrolyte was studied. Secondly, to understand the activation loss in SOFC, the kinetic Monte Carlo (KMC) technique was implemented to model the SOFC operation to determining the rate-limiting step due to the electrodes on different sizes of Pt catalysts. The isotope exchange depth profiling technique was employed to investigate the irradiation effect on the ionic transport in different

  2. Multi scale and physics models for intermediate and low temperatures H+-solid oxide fuel cells with H+/e-/O2- mixed conducting properties: Part A, generalized percolation theory for LSCF-SDC-BZCY 3-component cathodes

    Science.gov (United States)

    Chen, Daifen; Zhang, Qiang; Lu, Liu; Periasamy, Vijay; Tade, Moses O.; Shao, Zongping

    2016-01-01

    H+ based solid oxide fuel cell (SOFC) composite cathodes are generally agreed to be of quite different relationships among the microstructure parameters, electrode properties and detailed working processes from the conventional O2--SOFC composite cathodes. In this paper, the percolation theory is significantly generalized and developed to suit most of the typical H+-SOFC composite cathodes with e-/H+, e-/O2- or e-/H+/O2- mixed conducting characteristics; not just limited to the BCZY, SDC and LSCF materials. It provides an easy way to investigate the effect of microstructure parameters on the H+-SOFC electrode characteristics in quantity. The studied electrode properties include: i) the potential coexisting sites of O2, e-, and O2- transport paths for the oxygen reduction; ii) the potential coexisting sites of O2-, H+ and H2O transport paths for the vapor formation; iii) the effective e-, O2-, and H+ conducting and gas diffusing capabilities of the composite cathodes, and so on. It will be helpful for the H+-SOFC composite cathode manufacture to achieve the expected properties. Furthermore, it is also an important step for the developing of the multiphysics-model in manuscript part B to study the effect of the microstructure parameters on the H+-SOFC working details.

  3. Synthesis, characterization and electrical properties of solid electrolyte for solid oxide fuel cell; Preparacao, caracterizacao e propriedades eletricas de eletrolito solido para celula a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Marco Antonio Coelho; Garcia, Carlos Mario; Matos, Jeferson Hrenechen [Instituto de Tecnologia para o Desenvolvimento (LACTEC), Curitiba, PR (Brazil)], Emails: felsky@latec.org.br, garcia@latec.org.br, jeferson.h@latec.org.br

    2010-04-15

    Solid electrolytes of BaCe{sub 08}Gd{sub O29} were prepared by the polymeric precursor method. X-ray diffraction data shows a single phase with orthorhombic crystalline structure. The densification process was followed by scanning electronic microscopy and apparent density measurements. The apparent density was developed for different temperatures of sintering, reaching > 96% for sintered temperature of 1550 {sup 0}C deg . The electrochemical impedance analysis was development in the temperature of 400-700 deg C, in air atmosphere at 700 deg C a value of 30,6 mS.cm{sup -1} was obtained. The results of conductivity have confirmed the gadolinium doped barium cerate has a great potential for use as solid electrolyte for intermediate temperature solid oxide fuel cell, at experimental controlled conditions. (author)

  4. Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2015-09-01

    The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

  5. Advances in Solid State Joining of High Temperature Alloys

    Science.gov (United States)

    Ding, Jeff; Schneider, Judy

    2011-01-01

    Many of the metals used in the oil and gas industry are difficult to fusion weld including Titanium and its alloys. Solid state joining processes are being pursued as an alternative process to produce robust structures more amenable to high pressure applications. Various solid state joining processes include friction stir welding (FSW) and a patented modification termed thermal stir welding (TSW). The configuration of TSWing utilizes an induction coil to preheat the material minimizing the burden on the weld tool extending its life. This provides the ability to precisely select and control the temperature to avoid detrimental changes to the microstructure. The work presented in this presentation investigates the feasibility of joining various titanium alloys using the solid state welding processes of FSW and TSW. Process descriptions and attributes of each weld process will be presented. Weld process set ]up and welding techniques will be discussed leading to the challenges experienced. Mechanical property data will also be presented.

  6. Synthesis and characterization of La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−δ} oxide as cathode for Intermediate Temperature Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Vázquez, Santiago; Davyt, Sebastián [Laboratorio de Cristalografía, Estado Sólido y Materiales, DETEMA, Facultad de Química, UdelaR, Gral. Flores 2124, Montevideo (Uruguay); Basbus, Juan F.; Soldati, Analía L. [Grupo Caracterización de Materiales, CAB-CNEA, Bustillo 9500, 8400 Bariloche (Argentina); Amaya, Alejandro [Laboratorio de Fisicoquímica de Superficies, DETEMA, Facultad de Química, UdelaR, Gral. Flores 2124, Montevideo (Uruguay); Serquis, Adriana [Grupo Caracterización de Materiales, CAB-CNEA, Bustillo 9500, 8400 Bariloche (Argentina); Faccio, Ricardo [Laboratorio de Cristalografía, Estado Sólido y Materiales, DETEMA, Facultad de Química, UdelaR, Gral. Flores 2124, Montevideo (Uruguay); Suescun, Leopoldo, E-mail: leopoldo@fq.edu.uy [Laboratorio de Cristalografía, Estado Sólido y Materiales, DETEMA, Facultad de Química, UdelaR, Gral. Flores 2124, Montevideo (Uruguay)

    2015-08-15

    Nanocrystalline La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−δ} (LSFCu) material was synthetized by combustion method using EDTA as fuel/chelating agent and NH{sub 4}NO{sub 3} as combustion promoter. Structural characterization using thermodiffraction data allowed to determine a reversible phase transition at 425 °C from a low temperature R-3c phase to a high temperature Pm-3m phase and to calculate the thermal expansion coefficient (TEC) of both phases. Important characteristics for cathode application as electronic conductivity and chemical compatibility with Ce{sub 0.9}Gd{sub 0.1}O{sub 2−δ} (CGO) electrolyte were evaluated. LSFCu presented a p-type conductor behavior with maximum conductivity of 135 S cm{sup −1} at 275 °C and showed a good stability with CGO electrolyte at high temperatures. This work confirmed that as prepared LSFCu has excellent microstructural characteristics and an electrical conductivity between 100 and 60 S cm{sup −1} in the 500–700 °C range which is sufficiently high to work as intermediate temperature Solid Oxide Fuel Cells (IT-SOFCs) cathode. However a change in the thermal expansion coefficient consistent with a small oxygen loss process may affect the electrode-electrolyte interface during fabrication and operation of a SOFC. - Graphical abstract: Nanocrystalline La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−δ} was prepared by gel combustion and characterized by X-ray thermodiffraction and its conductivity was determined. The phase shows a reversible rhombohedral to cubic structural phase transition at 425 °C and a semiconductor to metallic phase transition at 275 °C. - Highlights: • LSFCu was prepared by gel combustion route using EDTA and NH{sub 4}NO{sub 3}. • LSFCu shows a reversible phase transition at 425 °C from R-3c to Pm-3m phase. • The sample has a maximum conductivity value of 135 S cm{sup −1} at 275 °C. • LSFCu shows a good chemical compatibility with CGO at 900 °C.

  7. Enhanced oxygen diffusion in low barium-containing La0.2175Pr0.2175Ba0.145Sr0.4Fe0.8Co0.2O3−δ intermediate temperature solid oxide fuel cell cathodes

    KAUST Repository

    Vert, Vicente B.

    2012-09-01

    Isotopic tracer diffusion studies have been performed on the perovskite composition La 0.2175Pr 0.2175Ba 0.145Sr 0.4Fe 0.8Co 0.2O 3-δ to obtain the diffusion and surface exchange coefficients for oxygen. This material has been identified as a highly active electrocatalytic cathode for intermediate temperature solid oxide fuel cells. The oxygen diffusion coefficients obtained in the 450-650 °C temperature range are higher than the ones measured for most of the cathode materials reported in the literature and they agree with those calculated from electrochemical impedance spectroscopy measurements performed on symmetrical cells. © 2012 Elsevier B.V. All rights reserved.

  8. Persistent-current switch for pancake coils of rare earth-barium-copper-oxide high-temperature superconductor: Design and test results of a double-pancake coil operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K)

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Timing; Michael, Philip C.; Bascuñán, Juan; Iwasa, Yukikazu, E-mail: iwasa@jokaku.mit.edu [Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139 (United States); Voccio, John [Wentworth Institute of Technology, 550 Huntington Ave, Boston, Massachusetts 02115 (United States); Hahn, Seungyong [National High Magnetic Field Laboratory, Florida State University, Tallahassee, 2031 Paul Dirac Drive, Florida 32310 (United States)

    2016-08-22

    We present design and test results of a superconducting persistent current switch (PCS) for pancake coils of rare-earth-barium-copper-oxide, REBCO, high-temperature superconductor (HTS). Here, a REBCO double-pancake (DP) coil, 152-mm ID, 168-mm OD, 12-mm high, was wound with a no-insulation technique. We converted a ∼10-cm long section in the outermost layer of each pancake to a PCS. The DP coil was operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K). Over the operating temperature ranges of this experiment, the normal-state PCS enabled the DP coil to be energized; thereupon, the PCS resumed the superconducting state and the DP coil field decayed with a time constant of 100 h, which would have been nearly infinite, i.e., persistent-mode operation, were the joint across the coil terminals superconducting.

  9. High Performance Nano-Ceria Electrodes for Solid Oxide Cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Martinez Aguilera, Lev; Sudireddy, Bhaskar Reddy

    2016-01-01

    In solid oxide electrochemical cells, the conventional Ni-based fuel-electrodes provide high electrocatalytic activity but they are often a major source of long-term performance degradation due to carbon deposition, poisoning of reaction sites, Ni mobility, etc. Doped-ceria is a promising mixed...... ionic-electronic conducting oxide that could solve these issues if it can be integrated into an appropriate electrode structure. Two new approaches to obtain high-performance nanostructured doped-ceria electrodes are highlighted. The first is an infiltration-based architecture with Ce0.8Pr0.2O2-δ...... forming the active surfaces on a porous backbone with embedded electronic current collector material, yielding one of the highest performances reported for an electrode that operates either on fuel or oxidant. The second is a nano-Ce0.9Gd0.1O2-δ thin film prepared by spin-coating, which provides...

  10. Solid oxide fuel cell having a glass composite seal

    Science.gov (United States)

    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.

  11. Nondestructive characterization methods for monolithic solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Spectroelectrochemical cell for in situ studies of solid oxide fuel cells

    DEFF Research Database (Denmark)

    Hagen, Anke; Traulsen, Marie Lund; Kiebach, Wolff-Ragnar

    2012-01-01

    Solid oxide fuel cells (SOFCs) are able to produce electricity and heat from hydrogen- or carbon-containing fuels with high efficiencies and are considered important cornerstones for future sustainable energy systems. Performance, activation and degradation processes are crucial parameters to con...... and in the presence of relevant gases. Simultaneous spectroscopic and electrochemical evaluation by using X-ray absorption spectroscopy and electrochemical impedance spectroscopy is possible....... on materials and structural properties, preferably at the atomic level. A characterization of these properties under operation is desired. As SOFCs operate at temperatures around 1073 K, this is a challenge. A spectroelectrochemical cell was designed that is able to study SOFCs at operating temperatures...

  13. Mathematical model of a plate fin heat exchanger operating under solid oxide fuel cell working conditions

    Science.gov (United States)

    Kaniowski, Robert; Poniewski, Mieczysław

    2013-12-01

    Heat exchangers of different types find application in power systems based on solid oxide fuel cells (SOFC). Compact plate fin heat exchangers are typically found to perfectly fit systems with power output under 5 kWel. Micro-combined heat and power (micro-CHP) units with solid oxide fuel cells can exhibit high electrical and overall efficiencies, exceeding 85%, respectively. These values can be achieved only when high thermal integration of a system is assured. Selection and sizing of heat exchangers play a crucial role and should be done with caution. Moreover, performance of heat exchangers under variable operating conditions can strongly influence efficiency of the complete system. For that reason, it becomes important to develop high fidelity mathematical models allowing evaluation of heat exchangers under modified operating conditions, in high temperature regimes. Prediction of pressure and temperatures drops at the exit of cold and hot sides are important for system-level studies. Paper presents dedicated mathematical model used for evaluation of a plate fin heat exchanger, operating as a part of micro-CHP unit with solid oxide fuel cells.

  14. Tubular solid oxide fuel cells with porous metal supports and ceramic interconnections

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Kevin [Export, PA; Ruka, Roswell J [Pittsburgh, PA

    2012-05-08

    An intermediate temperature solid oxide fuel cell structure capable of operating at from 600.degree. C. to 800.degree. C. having a very thin porous hollow elongated metallic support tube having a thickness from 0.10 mm to 1.0 mm, preferably 0.10 mm to 0.35 mm, a porosity of from 25 vol. % to 50 vol. % and a tensile strength from 700 GPa to 900 GPa, which metallic tube supports a reduced thickness air electrode having a thickness from 0.010 mm to 0.2 mm, a solid oxide electrolyte, a cermet fuel electrode, a ceramic interconnection and an electrically conductive cell to cell contact layer.

  15. High-temperature oxidation and ignition of metals

    Science.gov (United States)

    Hill, Paul R; Adamson, David; Foland, Douglas H; Bressette, Walter E

    1956-01-01

    A study of the high-temperature oxidation of several aircraft construction materials was undertaken to assess the possibility of ignition under high-temperature flight conditions.Tests have been made both in open and closed jets, and, in addition, the burning of metals has been observed under static conditions in a pressurized vessel containing either air, oxygen, or nitrogen. When heated in an atmosphere of oxygen or when heated and plunged into a supersonic airstream, titanium, iron, carbon steel, and common alloys such as 4130 were found to have spontaneous-ignition temperatures in the solid phase (below melting) and they melted rapidly while burning. Inconel, copper, 18-8 stainless steel, Monel, and aluminum could not be made to ignite spontaneously at temperatures up to melting with the equipment available. Magnesium ignited spontaneously in either type of test at temperatures just above the melting temperature.A theory for the spontaneous ignition of metals, based on the first law of thermodynamics, is presented. Good correlation was obtained between calculated spontaneous-ignition temperatures and values measured in supersonic jet tests. There appears at the present time to be no need for concern regarding the spontaneous ignition of Inconel, the stainless steels, copper, aluminum, or magnesium for ordinary supersonic airplane or missile applications where the material temperature is kept within ordinary structural limits or at least below melting. For hypersonic applications where the material is to be melted away to absorb the heat of convection, the results of the present tests do not apply sufficiently to allow a conclusion.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. High performance fuel electrode for a solid oxide electrochemical cell

    DEFF Research Database (Denmark)

    2013-01-01

    perovskite oxides selected from the group consisting of niobium-doped strontium titanate, vanadium-doped strontium titanate, tantalum-doped strontium titanate and mixtures thereof, thereby obtaining a porous anode backbone, (b) sintering the coated electrolyte at a high temperature, such as 1200 DEG C...

  18. Development of metal supported Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Martinez, L. M.; Alava, I.; Antepara, I.; Castro, U.; Diez-Linaza, E.; Lecanda, N.; Montero, X.; Rivas, M.; Villarreal, I.; Laresgoiti, A.

    2005-07-01

    Metal supported solid oxide fuel cells have been developed by Ikerlan in collaboration with Lawrence Berkeley National Laboratory, as a promising way to reduce materials costs. This, in conjunction with cost-effective processing techniques, is vital for successful commercialisation of SOFC's. In this type of cells, the Ni/YSZ support anode has been replaced by a porous stainless steel support structure, and the Ni/YSZ anode is now limited to a thin catalytically active layer. The basic structure also includes a thin, 5-15 micron YSZ electrolyte and a cathode (LSF, LSCF or similar) of approximately 15-20 microns. This robust metal structure provides both high thermal and electronic conductivity, improves thermal shock resistance and allows for simple, cost effective sealing strategies. Metal supported SOFC technology, first patented in 1966 [1], has only recently received interest but the majority of current research is centred on relatively expensive fabrication techniques such as plasma spray [2] and metalorganic chemical vapour deposition [3]. Ceres Power [4,5] has, conversely, focused on the integration of low cost ceramic processes with metallic materials to develop doped ceria based electrolyte metal supported planar cells operating at 500-600C. Ikerlan, as part of Mondragon Corporacion Cooperativa (MCC), aims to develop metal supported SOFC tubular systems for small stationary applications based on natural gas, propane and similar fuels. The target temperature for operation is 700C, although studies are performed over a wider, 650-800C temperature range. Conventional low-cost processing and coating technologies, such as colloidal spray, dip coating and tape casting, are used to fabricate cofired ferritic supports, anodes and thin electrolytes under reducing atmospheres. The cathode is subsequently deposited and fired in air at temperatures below 1100C. The cofiring process adds several challenging requirements on the properties of the materials

  19. Evolution of thermal stress and failure probability during reduction and re-oxidation of solid oxide fuel cell

    Science.gov (United States)

    Wang, Yu; Jiang, Wenchun; Luo, Yun; Zhang, Yucai; Tu, Shan-Tung

    2017-12-01

    The reduction and re-oxidation of anode have significant effects on the integrity of the solid oxide fuel cell (SOFC) sealed by the glass-ceramic (GC). The mechanical failure is mainly controlled by the stress distribution. Therefore, a three dimensional model of SOFC is established to investigate the stress evolution during the reduction and re-oxidation by finite element method (FEM) in this paper, and the failure probability is calculated using the Weibull method. The results demonstrate that the reduction of anode can decrease the thermal stresses and reduce the failure probability due to the volumetric contraction and porosity increasing. The re-oxidation can result in a remarkable increase of the thermal stresses, and the failure probabilities of anode, cathode, electrolyte and GC all increase to 1, which is mainly due to the large linear strain rather than the porosity decreasing. The cathode and electrolyte fail as soon as the linear strains are about 0.03% and 0.07%. Therefore, the re-oxidation should be controlled to ensure the integrity, and a lower re-oxidation temperature can decrease the stress and failure probability.

  20. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    You, Fu-Tian [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China); Yu, Guang-Wei, E-mail: gwyu@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Wang, Yin, E-mail: yinwang@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Xing, Zhen-Jiao [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Liu, Xue-Jiao; Li, Jie [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China)

    2017-08-15

    Highlights: • Loading manganese oxides on activated carbon effectively promotes NO oxidation. • NO adsorption-desorption on activated carbon is fundamental to NO oxidation. • A high Mn{sup 4+}/Mn{sup 3+} ratio contributes to NO oxidation by promoting lattice O transfer. - Abstract: Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnO{sub x})-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N{sub 2} adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnO{sub x} and the test conditions on the reaction. MLAC with 7.5 wt.% MnO{sub x} (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O{sub 2}, room temperature and GHSV ca. 16000 h{sup −1}. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O{sub 2} concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnO{sub x} loading is assumed to be related to Mn{sup 4+}/Mn{sup 3+} ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnO{sub x} lattice O transfer is proposed.

  1. Solid oxide fuel cell generator with removable modular fuel cell stack configurations

    Science.gov (United States)

    Gillett, J.E.; Dederer, J.T.; Zafred, P.R.; Collie, J.C.

    1998-04-21

    A high temperature solid oxide fuel cell generator produces electrical power from oxidation of hydrocarbon fuel gases such as natural gas, or conditioned fuel gases, such as carbon monoxide or hydrogen, with oxidant gases, such as air or oxygen. This electrochemical reaction occurs in a plurality of electrically connected solid oxide fuel cells bundled and arrayed in a unitary modular fuel cell stack disposed in a compartment in the generator container. The use of a unitary modular fuel cell stack in a generator is similar in concept to that of a removable battery. The fuel cell stack is provided in a pre-assembled self-supporting configuration where the fuel cells are mounted to a common structural base having surrounding side walls defining a chamber. Associated generator equipment may also be mounted to the fuel cell stack configuration to be integral therewith, such as a fuel and oxidant supply and distribution systems, fuel reformation systems, fuel cell support systems, combustion, exhaust and spent fuel recirculation systems, and the like. The pre-assembled self-supporting fuel cell stack arrangement allows for easier assembly, installation, maintenance, better structural support and longer life of the fuel cells contained in the fuel cell stack. 8 figs.

  2. Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

    Science.gov (United States)

    Blinn, Kevin S.; Li, Xiaxi; Liu, Mingfei; Bottomley, Lawrence A.; Liu, Meilin

    2012-01-01

    Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM

  3. Selected topics in high temperature chemistry defect chemistry of solids

    CERN Document Server

    Johannesen, Ø

    2013-01-01

    The properties of materials at high temperature play a vital role in their processing and practical use. The real properties of materials at elevated temperatures are very often governed by defects in their structure. Lattice defects may consist of point defects like vacancies, interstitial atoms or substituted atoms. These classes are discussed in general and specifically for oxides, nitrides, carbides and sulfides. Defect aggregates, shear structures and adaptive structures are also described. Special attention is paid to hydrogen defects which seem to play an important role in several mater

  4. Designing and optimization of a micro CHP system based on Solid Oxide Fuel Cell with different fuel processing technologies

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh; Kær, Søren Knudsen

    2009-01-01

    The development of fuel cell technologies offers the opportunity to achieve significant improvements in energy conversion efficiencies at many scales. The high operating temperature (700-1000 Celsius) of Solid Oxide Fuel Cells (SOFC) has a number of consequences, the most important of which...... will be evaluated in terms of their energetic performance and suitability for meeting residential thermal and electric demand....

  5. Poisoning of Solid Oxide Electrolysis Cells by Impurities

    DEFF Research Database (Denmark)

    Ebbesen, Sune; Graves, Christopher R.; Hauch, Anne

    2010-01-01

    Electrolysis of H2O, CO2, and co-electrolysis of H2O and CO2 was studied in Ni/yttria-stabilized zirconia (YSZ) electrode supported solid oxide electrolysis cells (SOECs) consisting of a Ni/YSZ support, a Ni/YSZ electrode layer, a YSZ electrolyte, and an lanthanum strontium manganite (LSM......)/YSZ oxygen electrode When applying the gases as received, the cells degraded significantly at the Ni/YSZ electrode, whereas only minor (and initial) degradation was observed for either the Ni/YSZ or LSM/YSZ electrode. Application of clean gases to the Ni/YSZ electrode resulted in operation without any long...

  6. Lanthanum Manganate Based Cathodes for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Jørgensen, Mette Juhl

    medium frequency process in the impedance spectra, were observed. A low frequency arc related to gas diffusion limitation in a stagnant gas layer above the composite structure was detected. Finally, an inductive process, assumed to be connected to an activation process involving segregates at the triple......Composite cathodes for solid oxide fuel cells were investigated using electrochemical impedance spectroscopy and scanning electron microscopy. The aim was to study the oxygen reduction process in the electrode in order to minimise the voltage drop in the cathode. The electrodes contained...... phase boundary between electrode, electrolyte and gas phase, was found. Suggestions for further experiments and for modelling of the oxygen reduction mechanism are given....

  7. Performance characterization of solid oxide cells under high pressure

    DEFF Research Database (Denmark)

    Sun, Xiufu; Bonaccorso, Alfredo Damiano; Graves, Christopher R.

    2014-01-01

    Solid oxide electrolysis cells (SOECs) offer a great potential for large scale conversion of renewable electrical energy into chemical energy via electrolysis of H2O and CO2 to produce syngas (H2 + CO). The produced syngas can be further catalytically converted into various gaseous or liquid...... in both fuel cell mode and electrolysis mode. In electrolysis mode at low current density, the performance improvement was counteracted by the increase in open circuit voltage, but it has to be born in mind that the pressurised gas contains higher molar free energy. Operating at high current density...

  8. Oxygen Production on Mars Using Solid Oxide Electrolysis

    Science.gov (United States)

    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.

  9. Gallium Oxide Nanostructures for High Temperature Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Chintalapalle, Ramana V. [Univ. of Texas, El Paso, TX (United States)

    2015-04-30

    Gallium oxide (Ga2O3) thin films were produced by sputter deposition by varying the substrate temperature (Ts) in a wide range (Ts=25-800 °C). The structural characteristics and electronic properties of Ga2O3 films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga2O3 films. XRD and SEM analyses indicate that the Ga2O3 films grown at lower temperatures were amorphous while those grown at Ts≥500 oC were nanocrystalline. RBS measurements indicate the well-maintained stoichiometry of Ga2O3 films at Ts=300-800 °C. The electronic structure determination indicated that the nanocrystalline Ga2O3films exhibit a band gap of ~5 eV. Tungsten (W) incorporated Ga2O3 films were produced by co-sputter deposition. W-concentration was varied by the applied sputtering-power. No secondary phase formation was observed in W-incorporated Ga2O3 films. W-induced effects were significant on the structure and electronic properties of Ga2O3 films. The band gap of Ga2O3 films without W-incorporation was ~5 eV. Oxygen sensor characteristics evaluated using optical and electrical methods indicate a faster response in W-doped Ga2O3 films compared to intrinsic Ga2O3 films. The results demonstrate the applicability of both intrinsic and W-doped Ga-oxide films for oxygen sensor application at temperatures ≥700 °C.

  10. Redox Stable Anodes for Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Guoliang eXiao

    2014-06-01

    Full Text Available Solid oxide fuel cells (SOFCs can convert chemical energy from the fuel directly to electrical energy with high efficiency and fuel flexibility. Ni-based cermets have been the most widely adopted anode for SOFCs. However, the conventional Ni-based anode has low tolerance to sulfur-contamination, is vulnerable to deactivation by carbon build-up (coking from direct oxidation of hydrocarbon fuels, and suffers volume instability upon redox cycling. Among these limitations, the redox instability of the anode is particularly important and has been intensively studied since the SOFC anode may experience redox cycling during fuel cell operations even with the ideal pure hydrogen as the fuel. This review aims to highlight recent progresses on improving redox stability of the conventional Ni-based anode through microstructure optimization and exploration of alternative ceramic-based anode materials.

  11. Strength of Anode‐Supported Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Faes, A.; Frandsen, Henrik Lund; Kaiser, Andreas

    2011-01-01

    Nickel oxide and yttria doped zirconia composite strength is crucial for anode‐supported solid oxide fuel cells, especially during transient operation, but also for the initial stacking process, where cell curvature after sintering can cause problems. This work first compares tensile and ball......‐on‐ring strength measurements of as‐sintered anodes support. Secondly, the strength of anode support sintered alone is compared to the strength of a co‐sintered anode support with anode and electrolyte layers. Finally, the orientation of the specimens to the bending axis of a co‐sintered half‐cell is investigated....... Even though the electrolyte is to the tensile side, it is found that the anode support fails due to the thermo‐mechanical residual stresses....

  12. Effects of temperature, total dissolved solids, and total suspended solids on survival and development rate of larval Arkansas River Shiner

    Science.gov (United States)

    Mueller, Julia S.; Grabowski, Timothy B.; Brewer, Shannon K.; Worthington, Thomas A.

    2017-01-01

    Decreases in the abundance and diversity of stream fishes in the North American Great Plains have been attributed to habitat fragmentation, altered hydrological and temperature regimes, and elevated levels of total dissolved solids and total suspended solids. Pelagic-broadcast spawning cyprinids, such as the Arkansas River Shiner Notropis girardi, may be particularly vulnerable to these changing conditions because of their reproductive strategy. Our objectives were to assess the effects of temperature, total dissolved solids, and total suspended solids on the developmental and survival rates of Arkansas River Shiner larvae. Results suggest temperature had the greatest influence on the developmental rate of Arkansas River Shiner larvae. However, embryos exposed to the higher levels of total dissolved solids and total suspended solids reached developmental stages earlier than counterparts at equivalent temperatures. Although this rapid development may be beneficial in fragmented waters, our data suggest it may be associated with lower survival rates. Furthermore, those embryos incubating at high temperatures, or in high levels of total dissolved solids and total suspended solids resulted in less viable embryos and larvae than those incubating in all other temperature, total dissolved solid, and total suspended solid treatment groups. As the Great Plains ecoregion continues to change, these results may assist in understanding reasons for past extirpations and future extirpation threats as well as predict stream reaches capable of sustaining Arkansas River Shiners and other species with similar early life-history strategies.

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

    Energy Technology Data Exchange (ETDEWEB)

    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%.

  14. Secondary creep of porous metal supports for solid oxide fuel cells by a CDM approach

    DEFF Research Database (Denmark)

    Esposito, L.; Boccaccini, D. N.; Pucillo, G. P.

    2017-01-01

    The creep behaviour of porous iron-chromium alloy used in solid oxide fuel cells (SOFCs) becomes relevant under SOFC operating temperatures. In this paper, the secondary creep stage of infiltrated and non-infiltrated porous metal supports (MS) was investigated and theoretically modelled...... as function of temperature, determined by the high temperature impulse excitation technique, was directly used to account for the porosity and the related effective stress acting during the creep tests. The proposed creep rate formulation was used to extend the Crofer® 22 APU Monkman-Grant diagram...... by a continuum damage mechanics (CDM) approach. The behaviour of the porous metal support, in the range from 1 to 17MPa and temperatures between 650 and 700°C, was combined and compared with data from literature of Crofer® 22 APU, taken as zero porosity reference material. The variation of the elastic modulus...

  15. Room Temperature Solid State Synthesis, Characterization, and Application of a Zinc Complex with Pyromellitic Acid

    Directory of Open Access Journals (Sweden)

    Rong-Gui Yang

    2018-01-01

    Full Text Available The complex [Zn2(btca(H2O4] was synthesized with 1,2,4,5-benzenetetracarboxylic acid (H4btca and zinc acetate as materials via a room-temperature solid state reaction. The composition and structure of the complex were characterized by elemental analyses (EA, Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, and thermogravimetric (TG analysis. The index results of X-ray powder diffraction data showed that the crystal structure of the complex belonged to monoclinic system with cell parameters a = 9.882 Å, b = 21.311 Å, c = 15.746 Å, and β = 100.69°. In order to expand the application of the complex, the nanometer zinc oxide was prepared by using the complex as a precursor, and the effect of the thermal decomposition temperature on the preparation of the nanometer zinc oxide was studied. The results showed that the grain size of zinc oxide gradually grew with the increase of the pyrolysis temperature, the obtained nanometer zinc oxide was spherical, and the diameter of the particles was about 25 nm.

  16. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Science.gov (United States)

    You, Fu-Tian; Yu, Guang-Wei; Wang, Yin; Xing, Zhen-Jiao; Liu, Xue-Jiao; Li, Jie

    2017-08-01

    Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnOx)-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnOx and the test conditions on the reaction. MLAC with 7.5 wt.% MnOx (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O2, room temperature and GHSV ca. 16000 h-1. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O2 concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnOx loading is assumed to be related to Mn4+/Mn3+ ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnOx lattice O transfer is proposed.

  17. EPMA of interfaces applied to the solid oxide fuel cell.

    Science.gov (United States)

    Grübmeier, H; Naoumidis, A; Stochniol, G; Tsoga, A

    1995-10-01

    Chemical interactions at the phase boundaries of materials applied for the solid oxide fuel cell (SOFC) have been studied by EPMA. The chemical reactivity at the interface of La(y-x)Sr(x)MnO(3)/ZrO(2)-Y(2)O(3) is dependent on the stoichiometry (y) and the Sr content (x) of the perovskite. Typical reaction products (zirconates) and a diffusion zone in the ZrO(2)-Y(2)O(3) have been observed. The extension of cation release (Mn) is related to the increasing chemical activity of Mn oxide in the perovskite by the Sr substitution for La. The wettability of the metal/oxide interface in the anode cermet (Ni/ZrO(2)-Y(2)O(3)) has been found to be influenced by chemical reactions resulting from the applied reducing atmosphere with high carbon activity. The disintegration of ZrO(2)-Y(2)O(3) in contact with molten Ni or Ni-Ti and Ni-Cr alloys leads to the redeposition of Y(2)O(3)-enriched oxides and also to Zr-rich intermetallic compounds and eutectics.

  18. Fabrication and characterization of a cathode-supported tubular solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chunhua; Liu, Renzhu; Wang, Shaorong; Wang, Zhenrong; Qian, Jiqin; Wen, Tinglian [CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

    2009-07-15

    A cathode-supported tubular solid oxide fuel cell (CTSOFC) with the length of 6.0 cm and outside diameter of 1.0 cm has been successfully fabricated via dip-coating and co-sintering techniques. A crack-free electrolyte film with a thickness of {proportional_to}14 {mu}m was obtained by co-firing of cathode/cathode active layer/electrolyte/anode at 1250 C. The relative low densifying temperature for electrolyte was attributed to the large shrinkage of the green tubular which assisted the densification of electrolyte. The assembled cell was electrochemically characterized with humidified H{sub 2} as fuel and O{sub 2} as oxidant. The open circuit voltages (OCV) were 1.1, 1.08 and 1.06 V at 750, 800 and 850 C, respectively, with the maximum power densities of 157, 272 and 358 mW cm{sup -2} at corresponding temperatures. (author)

  19. High performance metal-supported solid oxide fuel cells with Gd-doped ceria barrier layers

    DEFF Research Database (Denmark)

    Klemensø, Trine; Nielsen, Jimmi; Blennow Tullmar, Peter

    2011-01-01

    Metal-supported solid oxide fuel cells are believed to have commercial advantages compared to conventional anode (Ni–YSZ) supported cells, with the metal-supported cells having lower material costs, increased tolerance to mechanical and thermal stresses, and lower operational temperatures......, and an electrochemical performance beyond the state-of-the-art anode-supported SOFC is demonstrated possible, by introducing a CGO barrier layer in combination with Sr-doped lanthanum cobalt oxide (LSC) cathode. Area specific resistances (ASR) down to 0.27 Ω cm2, corresponding to a maximum power density of 1.14 W cm−2...... at 650 °C and 0.6 V, were obtained on cells with barrier layers fabricated by magnetron sputtering. The performance is dependent on the density of the barrier layer, indicating Sr2+ diffusion is occurring at the intermediate SOFC temperatures. The optimized design further demonstrate improved durability...

  20. Long-term operation of a solid oxide cell stack for coelectrolysis of steam and CO2

    DEFF Research Database (Denmark)

    Agersted, Karsten; Chen, Ming; Blennow, Peter

    2016-01-01

    High temperature electrolysis based on solid oxide electrolysis cells (SOECs) is a promising technology for production of synthetic fuels. The SOEC units can be used for co-electrolysis of steam and CO2 to produce synthesis gas (syngas, CO+H2), which can be further processed to a variety...... of synthetic fuels such as methane, methanol or DME. Previously we have reported electrolysis operation of solid oxide cell stacks for periods up to about 1000 hours. In this work, operation of a Haldor Topsoe 8-cell stack (stack design of 2014) in co-electrolysis mode for 6000 hours is reported. The stack...

  1. Solid/liquid lubrication of ceramics at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Erck, R.A.; Fenske, G.R. [Argonne National Lab., IL (United States); Hong, H. [Lubrizol Corp., Wickliffe, OH (United States)

    1996-04-01

    This study investigates the effect of solid and liquid lubrication on friction and wear performance of silicon nitride (Si{sub 3}N{sub 4}) and cast iron. The solid lubricant was a thin silver film ({approx}2 {mu}m thick) produced on Si{sub 3}N{sub 4} by ion-beam-assisted deposition. A high-temperature polyol-ester-base synthetic oil served as the liquid lubricant. Friction and wear tests were performed with pin-on-disk and oscillating-slider wear test machines at temperatures up to 300{degrees}C. Without the silver films, the friction coefficients of Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4} test pairs were 0.05 to 0.14, and the average wear rates of Si{sub 3}N{sub 4} pins were {approx}5 x 10{sup -8} mm{sup 3} N{sup -1}. The friction coefficients of Si{sub 3}N{sub 4}/cast iron test pairs ranged from 0.08 to 0.11, depending on test temperature. The average specific wear rates of cast iron pins were {approx}3 x 10{sup -7} mm{sup 3} N{sup -1} m{sup -1}. However, simultaneous use of the solid-lubricant silver and synthetic oil on the sliding surfaces reduced friction coefficients to 0.02 to 0.08. Moreover, the wear of Si{sub 3}N{sub 4} pins and silver-coated Si{sub 3}N{sub 4} disks was so low that it was difficult to assess by a surface profilometer. The wear rates of cast iron pins were {approx}7 x 10{sup -9} mm{sup 3} N{sup -1} m{sup -1} up to 250{degrees}C, but showed a tendency to increase slightly at much higher temperatures. In general, the test results demonstrated that the solid/liquid lubrication of ceramic and/or metallic components is both feasible and effective in controlling friction and wear.

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

    Energy Technology Data Exchange (ETDEWEB)

    Haberman, Ben [LG Fuel Cell Systems Inc., North Canton, OH (United States); Martinez-Baca, Carlos [LG Fuel Cell Systems Inc., North Canton, OH (United States); Rush, Greg [LG Fuel Cell Systems Inc., North Canton, OH (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Durable solid oxide electrolysis cells for hydrogen production

    DEFF Research Database (Denmark)

    Sun, Xiufu; Chen, Ming; Hendriksen, Peter Vang

    2014-01-01

    Solid oxide cell (SOC) for electrolysis application has attracted great interest in recent years due to its high power-to-gas efficiency and capability of co-electrolysis of H2O and CO2 for syngas (H2 + CO) production. The demonstration of durable solid oxide electrolysis cell operation for fuel...... production is required for promoting commercialization of the SOEC technology. In this work, we report a recent 4400 hours test of a state-of-the-art Ni-YSZ electrode supported SOEC cell. The cell consists of a Ni-YSZ (YSZ: yttria stabilized zirconia) support and active fuel electrode, an YSZ electrolyte...... layer, a CGO (Gd doped ceria) inter-diffusion barrier layer and a LSCF-CGO (LSCF: lanthanum ferrite doped with strontium and cobalt) oxygen electrode layer. The electrolysis test was carried out at 800 °C under 1 A/cm2 with 90 % H2O + 10 % H2 supplied to Ni-YSZ electrode compartment. The results show...

  6. Quantum Diffusion-Controlled Chemistry: Reactions of Atomic Hydrogen with Nitric Oxide in Solid Parahydrogen.

    Science.gov (United States)

    Ruzi, Mahmut; Anderson, David T

    2015-12-17

    Our group has been working to develop parahydrogen (pH2) matrix isolation spectroscopy as a method to study low-temperature condensed-phase reactions of atomic hydrogen with various reaction partners. Guided by the well-defined studies of cold atom chemistry in rare-gas solids, the special properties of quantum hosts such as solid pH2 afford new opportunities to study the analogous chemical reactions under quantum diffusion conditions in hopes of discovering new types of chemical reaction mechanisms. In this study, we present Fourier transform infrared spectroscopic studies of the 193 nm photoinduced chemistry of nitric oxide (NO) isolated in solid pH2 over the 1.8 to 4.3 K temperature range. Upon short-term in situ irradiation the NO readily undergoes photolysis to yield HNO, NOH, NH, NH3, H2O, and H atoms. We map the postphotolysis reactions of mobile H atoms with NO and document first-order growth in HNO and NOH reaction products for up to 5 h after photolysis. We perform three experiments at 4.3 K and one at 1.8 K to permit the temperature dependence of the reaction kinetics to be quantified. We observe Arrhenius-type behavior with a pre-exponential factor of A = 0.036(2) min(-1) and Ea = 2.39(1) cm(-1). This is in sharp contrast to previous H atom reactions we have studied in solid pH2 that display definitively non-Arrhenius behavior. The contrasting temperature dependence measured for the H + NO reaction is likely related to the details of H atom quantum diffusion in solid pH2 and deserves further study.

  7. Development of solid electrolytes for water electrolysis at higher temperature

    Energy Technology Data Exchange (ETDEWEB)

    Linkous, C.A. [Florida Solar Energy Center, Cocoa, FL (United States)

    1996-10-01

    This report describes efforts in developing new solid polymer electrolytes that will enable operation of proton exchange membrane electrolyzers at higher temperatures than are currently possible. Several ionomers have been prepared from polyetheretherketone (PEEK), polyethersulfone (PES), and polyphenylquinoxaline (PPQ) by employing various sulfonation procedures. By controlling the extent of sulfonation, a range of proton conductivities could be achieved, whose upper limit actually exceeded that of commercially available perfluoralkyl sulfonates. Thermoconductimetric analysis of samples at various degrees of sulfonation showed an inverse relationship between conductivity and maximum operating temperature. This was attributed to the dual effect of adding sulfonate groups to the polymer: more acid groups produce more protons for increased conductivity, but they also increase water uptake, which mechanically weakens the membrane. This situation was exacerbated by the limited acidity of the aromatic sulfonic acids (pK{sub A} {approx} 2-3). The possibility of using partial fluorination to raise the acid dissociation constant is discussed.

  8. Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Kazunari, E-mail: YAMAURA.Kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

    2016-04-15

    High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO{sub 3}, LiOsO{sub 3}, and Na{sub 2}OsO{sub 4}, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO{sub 3}, a ferroelectric-like transition in LiOsO{sub 3}, and high-temperature ferrimagnetism driven by a local structural distortion in Ca{sub 2}FeOsO{sub 6} may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices. - Graphical Abstract: Flux-grown crystals of NaOsO{sub 3} under high-pressure and high-temperature conditions in a belt-type apparatus. The crystal shows a magnetically driven metal–insulator transition at a temperature of 410 K. - Highlights: • Short review of high-pressure crystal growth of solid-state osmium oxides. • Wide variety of magnetic properties of solid-state osmium oxides. • Perovskite and related dense structures stabilized at 3–17 GPa.

  9. Molecular manipulation of solid state structure: influences of organic components on vanadium oxide architectures

    Science.gov (United States)

    Hagrman, Pamela J.; Finn, Robert C.; Zubieta, Jon

    2001-11-01

    Among the inorganic materials enjoying widespread contemporary interest, the metal oxide based solid phases occupy a prominent position by virtue of their applications to catalysis, sorption, molecular electronics, energy storage, optical materials and ceramics. The diversity of properties associated with these materials reflects the chemical composition, which allows variations in covalency, geometry and oxidation states, and the crystalline architecture, which may provide different pore structures, coordination sites, or juxtapositions of functional groups. Despite such fundamental and practical significance, the design of the structure of such materials remains a challenge in solid state chemistry. While organic materials have been synthesized which self-assemble into ordered arrays at low temperature and which exhibit molecular recognition and biomimetic activity, the ability to synthesize inorganic materials by rational design remains elusive. Small, soluble molecular building blocks with well-defined reaction chemistries which allow their low-temperature assembly into crystalline solid state inorganic materials are not well known. However, the existence of naturally occurring, structurally complex minerals establishes that hydrothermal synthesis can provide a low temperature pathway to produce open-framework and layered metastable structures utilizing inorganic starting materials. Thus, hydrothermal conditions have been used to prepare microporous tetrahedral framework solids that are capable of shape-selective absorption, like zeolites and aluminophosphates, and more recently in the preparation of complex solid arrays of the M/O/PO 3-4 and M/O/RPO 2-3 systems (M=V and Mo). The hydrothermal technique may be combined with the introduction of organic components which may act as charge compensating groups, space-filling units, structure directing agents, templates, tethers between functional groups, or conventional ligands in the preparation of inorganic

  10. Ignition et oxydation des particules de combustible solide pulvérisé Ignition and Oxidation of Pulverized Solid Fuel

    Directory of Open Access Journals (Sweden)

    De Soete G. G.

    2006-11-01

    élais d'ignition ont été déterminés pour un grand nombre de combustibles solides de rang inférieur et supérieur (charbons, cokes, asphaltènes, suies, bois, graphite. L'étude de la vitesse expérimentale de la combustion hétérogène, notamment l'étude de la température apparente d'activation, et sa dépendance par rapport à la taille des particules et à la concentration d'oxygène, montre que, dans les conditions des essais, cette combustion est contrôlée par la désorption du CO et se déroule principalement en régime cinético-diffusionnel mixte. L'étude de la dépendance des délais d'ignition par rapport à la température, la taille des particules et la pression partielle d'oxygène, suggère que, pendant ces délais, les réactions se déroulent en régime cinétique pur et que le produit des réactions de désorption est principalement le CO. The heated-grid method is used to investigate the competition between (1 the devolatilization and subsequent oxidation of pyrolysis products and (2 the ignition of the solid matrix and its rapid combustion. A comparison between the instant of ignition and the start of pyrolysis is used to determine the range in which ignition of a pyrolyzable solid fuel of the whole coal ignitiontype (i. e. when ignition occurs before pyrolysis becomes measurable occurs as a function of temperature, particle size and oxygen concentration. The results suggest that this type of ignition might occur, as a general rule, under conditions involving pulverized solid fuels in industrial flames. In the case of whole coalignition, the rate of combustion of the solid matrix is inhibited during the period following ignition. This inhibition is due partly to the difficulty oxygen has of spreading through the pores during the discharge of pyrolysis products and partly to preferential oxygen consumption during the oxidation of pyrolysis products, mainly when this oxidation develops in the form of flames. t is only when pyrolysis ends that

  11. Microstructural Degradation of Ni/YSZ Electrodes in Solid Oxide Electrolysis Cells under High Current

    DEFF Research Database (Denmark)

    Chen, Ming; Liu, Yi-Lin; Bentzen, Janet Jonna

    2013-01-01

    Ni/yttria stabilized zirconia (YSZ) supported solid oxide electrolysis cells (SOECs) were exposed to long-term galvanostatic electrolysis tests, under different testing conditions (temperature, gas composition, current density etc.) with an emphasis on high current density (above −1 A/cm2...... of Ni-YSZ interfacial reactions, taking place under the conditions prevailing under strong polarization. A mechanism for the formation of ZrO2 nano-particles on the Ni surface under the electrolysis cell testing is proposed and the possibility of Ni-YSZ interfacial reactions under such conditions (T, p...

  12. Thermodynamic analysis of synthetic hydrocarbon fuel production in pressurized solid oxide electrolysis cells

    DEFF Research Database (Denmark)

    Sun, Xiufu; Chen, Ming; Jensen, Søren Højgaard

    2012-01-01

    A promising way to store wind and solar electricity is by electrolysis of H2O and CO2 using solid oxide electrolysis cells (SOECs) to produce synthetic hydrocarbon fuels that can be used in existing fuel infrastructure. Pressurized operation decreases the cell internal resistance and enables...... hydrocarbon fuel and avoiding damage to the cells. The main parameters of cell operating temperature, pressure, inlet gas composition and reactant utilization are varied to examine how they influence cell thermoneutral and reversible potentials, in situ formation of methane and carbon at the Ni–YSZ electrode...

  13. Methane Steam Reforming over an Ni-YSZ Solid Oxide Fuel Cell Anode in Stack Configuration

    DEFF Research Database (Denmark)

    Mogensen, David; Grunwaldt, Jan-Dierk; Hendriksen, Peter Vang

    2014-01-01

    The kinetics of catalytic steam reforming of methane over an Ni-YSZ anode of a solid oxide fuel cell (SOFC) have been investigated with the cell placed in a stack configuration. In order to decrease the degree of conversion, a single cell stack with reduced area was used. Measurements were...... performed in the temperature range 600-800 degrees C and the partial pressures of all reactants and products were varied. The obtained rates could be well fitted with a power law expression (r proportional to P-CH4(0.7)). A simple model is presented which is capable of predicting the methane conversion...

  14. TOF-SIMS characterization of impurity enrichment and redistribution in solid oxide electrolysis cells during operation

    DEFF Research Database (Denmark)

    Kiebach, Wolff-Ragnar; Norrman, Kion; Chatzichristodoulou, Christodoulos

    2014-01-01

    TOF-SIMS analyses of state-of-the-art high temperature solid oxide electrolysis cells before and after testing under different operating conditions were performed. The investigated cells consist of an yttria stabilized zirconia (YSZ) electrolyte, a La1-xSrxMnO3-δ composite anode and a Ni-YSZ cermet...... and Ca, increases. For Si, a concentration gradient is found from the gas inlet to the gas outlet. Additionally, a loss of Ni percolation in the active cathode is observed in the same area where the Si enrichment is found. Based on the obtained TOF-SIMS results, the influence of the operating conditions...

  15. Plant Characteristics of an Integrated Solid Oxide Fuel Cell Cycle and a Steam Cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2010-01-01

    Plant characteristics of a system containing a solid oxide fuel cell (SOFC) cycle on the top of a Rankine cycle were investigated. Natural gas (NG) was used as the fuel for the plant. A desulfurization reactor removes the sulfur content in the fuel, while a pre-reformer broke down the heavier...... recovery steam generator (HRSG). The remaining energy of the off-gases was recycled back to the topping cycle for further utilization. Several parameter studies were carried out to investigate the sensitivity of the suggested plant. It was shown that the operation temperature of the desulfurization unit...

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

    Science.gov (United States)

    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.

  17. Effect of proton-conduction in electrolyte on electric efficiency of multi-stage solid oxide fuel cells

    Science.gov (United States)

    Matsuzaki, Yoshio; Tachikawa, Yuya; Somekawa, Takaaki; Hatae, Toru; Matsumoto, Hiroshige; Taniguchi, Shunsuke; Sasaki, Kazunari

    2015-01-01

    Solid oxide fuel cells (SOFCs) are promising electrochemical devices that enable the highest fuel-to-electricity conversion efficiencies under high operating temperatures. The concept of multi-stage electrochemical oxidation using SOFCs has been proposed and studied over the past several decades for further improving the electrical efficiency. However, the improvement is limited by fuel dilution downstream of the fuel flow. Therefore, evolved technologies are required to achieve considerably higher electrical efficiencies. Here we present an innovative concept for a critically-high fuel-to-electricity conversion efficiency of up to 85% based on the lower heating value (LHV), in which a high-temperature multi-stage electrochemical oxidation is combined with a proton-conducting solid electrolyte. Switching a solid electrolyte material from a conventional oxide-ion conducting material to a proton-conducting material under the high-temperature multi-stage electrochemical oxidation mechanism has proven to be highly advantageous for the electrical efficiency. The DC efficiency of 85% (LHV) corresponds to a net AC efficiency of approximately 76% (LHV), where the net AC efficiency refers to the transmission-end AC efficiency. This evolved concept will yield a considerably higher efficiency with a much smaller generation capacity than the state-of-the-art several tens-of-MW-class most advanced combined cycle (MACC). PMID:26218470

  18. Gradient Meshed and Toughened SOEC (Solid Oxide Electrolyzer Cell) Composite Seal with Self-Healing Capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Kathy Lu; W. T. Reynolds, Jr.

    2010-06-08

    High-temperature electrolysis of water steam is a promising approach for hydrogen production. The potential is even more promising when abundant heat source from nuclear power reactors can be efficiently utilized. Hydrogen production through the above approach also allows for low electric consumption. Overall energy conversion efficiencies for high temperature electrolysis are in the 45-50% range compared to ~30% for the conventional electrolysis. Under such motivation, this research is focused on increasing the operation time and high temperature stability of solid oxide electrolyzer cells (SOEC) for splitting water into hydrogen. Specifically, our focus is to improve the SOEC seal thermal stability and performances by alleviating thermal stress and seal cracking issues.

  19. An experimental investigation of solid oxide fuel cell performance at variable operating conditions

    Directory of Open Access Journals (Sweden)

    Tikiz Ismet

    2016-01-01

    Full Text Available Cell temperature and selection of the reactant gases are crucial parameters for the design and optimization of fuel cell performance. In this study, effect of operating conditions on the performance of Solid Oxide Fuel (SOFC has been investigated. Application of Response Surface Methodology (RSM was applied to optimize operations conditions in SOFC. For this purpose, an experimental set up for testing of SOFC has been established to investigate the effect of Hydrogen, Oxygen, Nitrogen flow rates and cell temperature parameters on cell performance. Hydrogen flow rate, oxygen flow rate, nitrogen flow rate and cell temperature were the main parameters considered and they were varied between 0.25 and 1 L/min, 0.5 and 1 L/min, 0 and 1 L/min and 700-800 oC in the analyses respectively. The maximum power density was found as 0.572 W/cm2 in the experiments.

  20. High-Temperature Oxidation Behavior and Kinetics of Forged 12Cr-MoVW Steel

    Directory of Open Access Journals (Sweden)

    Kim Yong Hwan

    2017-06-01

    Full Text Available The oxidation kinetics of forged 12Cr-MoVW steel was investigated in an air (N2+O2 atmosphere at 873-1073 K (Δ50 K using thermogravimetric analysis. The oxidized samples were characterized using X-ray diffraction, and the surface and cross-sectional morphologies were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The forged 12Cr-MoVW steel samples exhibited parabolic behavior and a low oxidation rate compared with their as-cast counterparts. A protective oxide layer was uniformly formed at relatively low temperature (≤973 K for the forged samples, which thus exhibited better oxidation resistance than the as-cast ones. These oxides are considered solid-solution compounds such as (Fe, Cr2O3.

  1. Carbon and Redox Tolerant Infiltrated Oxide Fuel-Electrodes for Solid Oxide Cells

    DEFF Research Database (Denmark)

    Skafte, Theis Løye; Sudireddy, Bhaskar Reddy; Blennow, P.

    2016-01-01

    To solve issues of coking and redox instability related to the presence of nickel in typical fuel electrodes in solid oxide cells,Gd-doped CeO2 (CGO) electrodes were studied using symmetriccells. These electrodes showed high electro-catalytic activity, butlow electronic conductivity. When...... deposition in a CO/CO2-atmosphere, while none of the non-nickel cells catalyzed carbon.Stability towards redox cycles was also proven....

  2. Novel solidsolid phase change material based on polyethylene glycol and cellulose used for temperature stabilisation

    Directory of Open Access Journals (Sweden)

    Wojda Marta

    2014-01-01

    Full Text Available Thermal management is one of crucial issues in the development of modern electronic devices. In the recent years interest in phase change materials (PCMs as alternative cooling possibility has increased significantly. Preliminary results concerning the research into possibility of the use of solid-solid phase change materials (S-S PCMs for stabilisation temperature of electronic devices has been presented in the paper. Novel solid-solid phase change material based on polyethylene glycol and cellulose has been synthesized. Attempt to improve its thermal conductivity has been taken. Material has been synthesized for the purpose of stabilisation of temperature of electronic devices.

  3. Strong, Tough Glass Composites Developed for Solid Oxide Fuel Cell Seals

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2005-01-01

    A fuel cell is an electrochemical device that continuously converts the chemical energy of a fuel directly into electrical energy. It consists of an electrolyte, an anode, and a cathode. Various types of fuel cells are available, such as direct methanol fuel cells, alkaline fuel cells, proton-exchange-membrane fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, and solid oxide fuel cells (SOFCs). The salient features of an SOFC are all solid construction and high-temperature electrochemical-reaction-based operation, resulting in clean, efficient power generation from a variety of fuels. SOFCs are being developed for a broad range of applications, such as portable electronic devices, automobiles, power generation, and aeronautics.

  4. Potential electrode materials for symmetrical Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Ruiz Morales, J. C.

    2008-08-01

    Full Text Available Chromites, titanates and Pt-YSZ-CeO2 cermets have been investigated as potential electrode materials for an alternative concept of Solid Oxide Fuel Cell (SOFC, the symmetrical SOFCs (SFC. In this configuration, the same electrode material is used simultaneously as anode and cathode. Interconnector materials, such as chromites, could be considered as potential SFC electrodes, at least under pure hydrogen-fed at relatively high temperatures, as they do not exhibit significant catalytic activity towards hydrocarbon oxidation. This may be overcome by partially substituting Cr in the perovskite B-sites by other transition metal cations such as Mn. La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM is a good candidate for such SFCs, rendering fuel cell performances in excess of 500 and 300mW/cm2 using pure H2 and CH4 as fuel, at 950 oC. Similarly, typical n-type electronic conductors traditionally regarded as anode materials, such as strontium titanates, may also operate under oxidising conditions as cathodes by substituting some Ti content for Fe to introduce p-type conductivity. Preliminary electrochemical experiments on La4Sr8Ti12-xFexO38-δ-based SFCs show that they perform reasonably well under humidified H2, at high temperatures. A third group of materials is the support material of any typical cermet anode, i.e. YSZ, CeO2 plus a current collector. It has been found that this combination could be optimised to operate as SFC electrodes, rendering performances of 400mW/cm2 under humidified pure H2 at 950oC.

    Cromitas, titanatos y cermets de Pt-YSZ-CeO2 han sido investigados como potenciales materiales de electrodo para un concepto alternativo de Pilas de Combustible de Óxidos Sólidos (SOFC, las pilas SOFC simétricas (SFC. En

  5. Durability of Solid Oxide Electrolysis Cells for Syngas Production

    DEFF Research Database (Denmark)

    Sun, Xiufu; Chen, Ming; Liu, Yi-Lin

    2013-01-01

    Performance and durability of Ni-YSZ supported solid oxide electrolysis cells (SOECs) for co-electrolysis of H2O and CO2 at high current density was investigated. The cells consist of a Ni-YSZ support, a Ni-YSZ electrode, a YSZ electrolyte, and an LSM-YSZ electrode. The durability was examined...... at 800°C and electrolysis current densities of −1 or −1.5 A/cm2 with 60% reactant (H2O + CO2) utilization. The cell voltage degradation showed a strong dependence on the electrolysis current density. Electrochemical characterization of the cells showed that the degradation was mainly related to the LSM...

  6. A Decade of Solid Oxide Electrolysis Improvements at DTU Energy

    DEFF Research Database (Denmark)

    Hauch, Anne; Brodersen, Karen; Chen, Ming

    2017-01-01

    Solid oxide electrolysis cells (SOECs) can efficiently convert electrical energy (e.g. surplus wind power) to energy stored in fuels such as hydrogen or other synthetic fuels. Performance and durability of the SOEC has increased orders of magnitudes within the last decade. This paper presents....... All together, these improvements have led to a decrease in long-term degradation rate from ∼40 %/kh to ∼0.4 %/kh for steam electrolysis at -1 A/cm2, while the initial area specific resistance has been decreased from 0.44 Ωcm2 to 0.15 Ωcm2 at -0.5 A/cm2 and 750 °C....

  7. Fabrication and characterization of monolithic solid oxide fuel cells

    Science.gov (United States)

    Minh, N. Q.; Horne, C. R.; Liu, F. S.; Moffatt, D. M.; Staszak, P. R.

    The monolithic solid oxide fuel cell (MSOFC) is an all-ceramic structure in which cell components are configured in a compact corrugated array. The MSOFC shows promise for use in a wide range of sizes (kilowatt to megawatt) and a broad spectrum of applications (electric utility, cogeneration, on-site, and aerospace power). A process based on the tape calendering technique is being developed for the fabrication of the MSOFC. MSOFC single cells have been fabricated by this process without cracking or delamination. Stacks of various sizes have been formed and processed to demonstrate fabricability of the monolithic structure. Extensive physical, chemical, electrical, and electrochemical characterization of fabricated samples has been carried out to confirm the required properties of each cell component. The characterization results reported have been used to support material and fabrication improvements.

  8. ALTERNATIVE METHODS OF SEALING PLANAR SOLID OXIDE FUEL CELLS

    Energy Technology Data Exchange (ETDEWEB)

    Weil, K. Scott; Coyle, Christopher A.; Hardy, John S.; Kim, Jin Yong Y.; Xia, Gordon

    2005-03-01

    One of the key limiting issues in designing and fabricating a high performance planar solid oxide fuel cell (pSOFC) stack is the development of the appropriate materials and techniques for hermetically sealing the metal and ceramic components. There are essentially two standard methods of sealing: (1) by forming a rigid joint or (2) by constructing a compressive “sliding” seal. While short-term success has been achieved with both techniques, it is apparent that to meet the long-term operational needs of stack designers, alternative sealing concepts will need to be conceived. Described below are two alternative pSOFC sealing methods that have been developed at Pacific Northwest National Laboratory.

  9. Performance Characterization of Solid Oxide Cells Under High Pressure

    DEFF Research Database (Denmark)

    Sun, Xiufu; Bonaccorso, Alfredo Damiano; Graves, Christopher R.

    2015-01-01

    In this work, recent pressurized test results of a planar Ni- YSZ (YSZ: Yttria stabilized Zirconia) supported solid oxide cell are presented. Measurements were performed at 800 C in both fuel cell and electrolysis mode at different pressures. A comparison of the electrochemical performance...... of the cell at 1 and 3 bar shows a significant and equal performance gain at higher pressure in both fuel cell mode and electrolysis mode. Electrochemical impedance spectroscopy revealed that the serial resistance was not affected by the operation pressure; all the other processes that are dependent...... on partial pressures (oxygen, steam and hydrogen) were affected by increasing the pressure. In electrolysis mode at low current density, the performance improvement was counteracted by the increase in open circuit voltage, but it has to be borne in mind that the pressurized gas contains higher molar free...

  10. Five Kilowatt Solid Oxide Fuel Cell/Diesel Reformer

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Development of Mixed Ion-Electron Conducting Metal Oxides for Solid Oxide Fuel Cells

    Science.gov (United States)

    Kan, Wang Hay

    A solid oxide fuel cell (SOFC) is an energy conversion device, which directly converts chemical fuels (e.g., H2, C xHy) into electricity and heat with high efficiency up to 90%. The by-product of CO2 can be safely sequestrated or subsequently chemically transformed back into fuels (e.g., CO, CH 4) by electrolysis using renewable energy sources such as solar and wind. The state-of-the-art Ni-YSZ anode is de-activated in the presence of ppm level of H2S and forming coke in hydrocarbons. Currently, mixed ion and electron conductors (MIECs) are considered as alternatives for Ni-YSZ in SOFCs. The key goal of the research was to develop mixed ion-electron conducting metal oxides based on B-site disordered perovskite-type Ba(Ca,Nb)1-x MxO3-delta (M = Mn, Fe, Co), the B-site 1:1 ordered perovskite-type (M = Mn, Fe, Co) and the Sr2PbO4-type Sr2Ce1-xPrxO4 for SOFCs. Ba2(Ca,Nb)2-xMxO6-delta was chemically stable in 30 ppm levels of H2S at 600 °C for 24 h and in pure CO2 at 800 °C for 24 h. The thermal expansion coefficients (TEC) of the as-prepared ordered perovskites was found to be comparable to Zr0.84Y0.16O1.92 (YSZ). The near-surface concentration of Fe2+ in Ba2Ca 0.67Fe0.33NbO6-delta was found to be about 3 times higher than that in the bulk sample. The electrochemical performance of Ba2Ca0.67M0.33NbO6-delta was assessed by ac impedance spectroscopy using a YSZ supported half-cell. The area specific polarization resistance (ASR) of all samples was found to decrease with increasing temperature. The ASR for H2 gas oxidation can be correlated to the higher concentration of low valence Fe2+ species near-surface (nano-scale). BaCa0.335M0.165Nb0.5O3-delta crystallizes in the B-site disordered primitive perovskite (space group Pm-3m) at 900 °C in air, which can be converted into the B-site 1:2 ordered perovskite (space group P-3m1) at 1200 °C and the B-site 1:1 ordered double perovskite phase (space group Fm-3m ) at 1300 °C. The chemical stability of the perovskites in CO

  12. Surface strontium enrichment on highly active perovskites for oxygen electrocatalysis in solid oxide fuel cells

    KAUST Repository

    Crumlin, Ethan J.

    2012-01-01

    Perovskite oxides have high catalytic activities for oxygen electrocatalysis competitive to platinum at elevated temperatures. However, little is known about the oxide surface chemistry that influences the activity near ambient oxygen partial pressures, which hampers the design of highly active catalysts for many clean-energy technologies such as solid oxide fuel cells. Using in situ synchrotron-based, ambient pressure X-ray photoelectron spectroscopy to study the surface chemistry changes, we show that the coverage of surface secondary phases on a (001)-oriented La 0.8Sr 0.2CoO 3-δ (LSC) film becomes smaller than that on an LSC powder pellet at elevated temperatures. In addition, strontium (Sr) in the perovskite structure enriches towards the film surface in contrast to the pellet having no detectable changes with increasing temperature. We propose that the ability to reduce surface secondary phases and develop Sr-enriched perovskite surfaces of the LSC film contributes to its enhanced activity for O 2 electrocatalysis relative to LSC powder-based electrodes. © 2012 The Royal Society of Chemistry.

  13. Computational Fluid Dynamics calculation of a planar solid oxide fuel cell design running on syngas

    Directory of Open Access Journals (Sweden)

    Pianko-Oprych Paulina

    2017-12-01

    Full Text Available The present study deals with modelling and validation of a planar Solid Oxide Fuel Cell (SOFC design fuelled by gas mixture of partially pre-reformed methane. A 3D model was developed using the ANSYS Fluent Computational Fluid Dynamics (CFD tool that was supported by an additional Fuel Cell Tools module. The governing equations for momentum, heat, gas species, ion and electron transport were implemented and coupled to kinetics describing the electrochemical and reforming reactions. In the model, the Water Gas Shift reaction in a porous anode layer was included. Electrochemical oxidation of hydrogen and carbon monoxide fuels were both considered. The developed model enabled to predict the distributions of temperature, current density and gas flow in the fuel cell.

  14. Microstructure Sensitive Design and Processing in Solid Oxide Electrolyzer Cell

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Hamid Garmestani; Dr. Stephen Herring

    2009-06-12

    The aim of this study was to develop and inexpensive manufacturing process for deposition of functionally graded thin films of LSM oxides with porosity graded microstructures for use as IT-SOFCs cathode. The spray pyrolysis method was chosen as a low-temperature processing technique for deposition of porous LSM films onto dense YXZ substrates. The effort was directed toward the optimization of the processing conditions for deposition of high quality LSM films with variety of morphologies in the range of dense to porous microstructures. Results of optimization studies of spray parameters revealed that the substrate surface temperature is the most critical parameter influencing the roughness and morphology, porosity, cracking and crystallinity of the film.

  15. Fuel electrode for solid oxide electrolyte fuel cell. Kotai denkaishitsugata nenryo denchi no nenryo denkyoku

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, A.

    1993-03-19

    Cermet mixed with nickel and stabilized zirconia (YSZ) is normally used for the fuel electrode of the high temperature solid oxide electrolyte fuel cell which uses coal gasification gas or natural gas as the primary fuel. When acidic YSZ is used as the aggregate for this electrode, however, carbon tends to precipitate to shorten the life of the fuel cell. This invention relates to means of preventing direct contact of hydrocarbon with the first porous electrode layer, wherein the first porous electrode layer containing YSZ aggregate and nickel metal or its oxide particles is formed on the surface of the solid electrolyte substrate, on which the second porous electrode layer containing basic aggregate and nickel metal or its oxide particles is formed. MgAl2O4, CaAl2O4, MgO[center dot]2TiO2, and MgO[center dot]ZrO2 are used as the basic aggregates which comprise the second porous electrode layer. 12 figs., 2 tabs.

  16. Selected aspects of the design and diagnostics of solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    Lis Bartłomiej

    2016-01-01

    Full Text Available An increased growth in demand for energy accompanied by efforts to limit its negative impact on the environment is forcing society to seek new, more efficient energy sources. Fuel cells are one of the most promising solutions among the widely developed new generation of electrical generators. Fuel cells directly convert chemical fuel into electricity. Water and waste heat are by-products of fuel cell operation. Solid oxide fuel cells (SOFCs have proven to be one of the most interesting solutions among the five types of technologically advanced fuel cells, for their ability to operate at temperatures above 800°C. Furthermore, SOFCs are characterized by other advantages in comparison to PEMFCs, including: (1 no need to use expensive catalysts (e.g. platinum, the price of which is high, and its resources limited, (2 the possibility of direct, internal conversion of hydrocarbon fuels, (3 lower sensitivity to contaminants (in particular, hydrogen fuel containing CO, which is useful for SOFCs instead of the platinum catalyst poisoners, and (4 the possibility of using waste heat in a gas turbine, or for heating or other industrial purposes. The paper discusses selected issues regarding the construction and characteristics of planar solid oxide fuel cells. Selected results of the following electrochemical investigations: Ba0.9Ca0.1Ce0.9Y0.1O3-based proton electrolyte as possible components of SOFCs operating at intermediate temperature range (500-700°C.

  17. Development of solid oxide fuel cells; Desenvolvimento de celulas a combustivel do tipo oxido solido (SOFC)

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, Jaime S.; Alencar, Marcelo Goncalves F. de; Amaral, Alexandre Alves do; Benedicto, Joao Paulo Santos; Silva, Marcos A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica. Dept. de Fisico-Quimica

    2006-07-01

    Fuel cells allow the energy production without the thermodynamic restriction of the conversion of heat into work. Among their various types, the solid oxide fuel cells (SOFC), operating at high temperatures, allow the methane conversion into electricity directly on the anode. The main element of the SOFC is the structure A/E/C: anode/electrolyte/cathode, all sintered at high temperature as resistant ceramic materials. Dense electrolyte (YSZ: zirconia stabilized for Yttria) separates the anode (Ni+Co/YSZ: cobalt promoted nickel, supported on YSZ) and cathode (LSM: strontium-doped lanthanum manganite), both with porosity obtained by graphite addition. To obtain suitable A/E/C pellets, the layer sintering with appropriate mechanical and textural characteristics is essential, requiring excellent electric junctions between them. The cell performance has been evaluated between 850 and 950 degree C, using hydrogen or methane fuel; the tension and current for different resistance values in the electrical circuit have been measured. The cobalt addition to the cell anode significantly increased its activity for the reform reaction. The beneficial effect was probably due to the easier nickel reduction in cobalt presence. This work had the objectives of developing and evaluating electro-catalysts, as well as the solid oxide fuel cells using these catalysts as anode. Five SOFC models (SOFC 1 to SOFC 5) are described; all of them were developed aiming at improving the preparation of the anode/electrolyte/cathode structure (A/E/C). (author)

  18. Zirconium-cerin solid solutions: thermodynamic model and thermal stability at high temperature; Solutions solides de zirconium dans la cerine: modele thermodynamique et stabilite thermique a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Janvier, C.

    1998-04-02

    The oxides-gaseous dioxygen equilibria and the textural thermal stability of six zirconium-cerin solutions Ce{sub 1-x}Zr{sub x}O{sub 2} (0solid solutions and the gaseous oxygen by thermal gravimetric analysis at 600 degrees Celsius has shown that these solutions have not a ideal behaviour. A thermodynamic model where the point defects of solutions are included describe them the best. It becomes then possible to know the variations of the concentrations of the point defects in terms of temperature, oxygen pressure and zirconium concentration. A kinetic study (by calcination at 950 degrees Celsius of the solid solutions) of the specific surface area decrease has revealed a minima (0

  19. Localized Carbon Deposition in Solid Oxide Electrolysis Cells Studied By Multiphysics Modeling

    DEFF Research Database (Denmark)

    Navasa, Maria; Graves, Christopher R.; Frandsen, Henrik Lund

    2016-01-01

    Modeling for optimizing performance has attracted substantial research efforts in the last twenty years with special focus on solid oxide fuel cells (SOFCs). However, limited amount of the modeling work has been focused on the solid oxide electrolysis cell (SOEC) operation mode and even less...

  20. 46 CFR 194.05-11 - Flammable solids and oxidizing materials-Detail requirements.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Flammable solids and oxidizing materials-Detail requirements. 194.05-11 Section 194.05-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... and Marking § 194.05-11 Flammable solids and oxidizing materials—Detail requirements. (a) Flammable...

  1. Solid Oxide Electrolysis Cells: Microstructure and Degradation of the Ni/Yttria-Stabilized Zirconia Electrode

    DEFF Research Database (Denmark)

    Hauch, Anne; Ebbesen, Sune; Jensen, Søren Højgaard

    2008-01-01

    Solid oxide fuel cells produced at Risø DTU have been tested as solid oxide electrolysis cells for steam electrolysis by applying an external voltage. Varying the sealing on the hydrogen electrode side of the setup verifies that the previously reported passivation over the first few hundred hours...

  2. A solid oxide fuel cell with a gadolinia-doped ceria anode: Preparation and performance

    DEFF Research Database (Denmark)

    Marina, O.A.; Bagger, C.; Primdahl, S.

    1999-01-01

    The application of doped ceria as an anode material in high-temperature solid oxide fuel cells (SOFC) is described. Deposition of an anchoring layer of YSZ particles was used to obtain sufficient adhesion between a porous Ce0.6Gd0.4O1.8 (CG4) anode and an yrttria-stabilised zirconia (YSZ) electro......The application of doped ceria as an anode material in high-temperature solid oxide fuel cells (SOFC) is described. Deposition of an anchoring layer of YSZ particles was used to obtain sufficient adhesion between a porous Ce0.6Gd0.4O1.8 (CG4) anode and an yrttria-stabilised zirconia (YSZ......) electrolyte without detrimental reaction. Single SOFCs comprising the CG4 anode, a composite strontium-doped lanthanum manganite-based cathode and the YSZ electrolyte were manufactured and tested in H-2/H2O and CH4/H2O atmospheres vs. air in the temperature range of 800-1015 degrees C, An area specific...... internal resistance of 0.39 Ohm cm(2) at 0.71 V cell voltage and a power density of 470 mW/cm(2) was obtained at 1000 degrees C using H-2/H2O/N-2 = 9/1.2/89.8 as the fuel and air as oxidant. A current density of 0.25 A/cm(2) at an area specific internal resistance of 2 Ohm cm(2) was obtained with CH4/H2O...

  3. Municipal Solid Waste Gasification with Solid Oxide Fuel Cells and Stirling Engine

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    storage in landfills and devote these spaces to other human activities. It is also important to point out that this kind of renewable energy suffers significantly less availabilit y which characterizes other type o f renewable energy sources such as in wind and solar energy. In a gasification process....... The gasification process is usually based on an atmospheric - pressure circulating fluidized bed gasifier coupled to a tar - crac king vessel. Syngas can be used as fuel in different kind of power plant such as gas turbine cycle, steam cycle, combined cycle, internal and external combustion engine and Solid Oxide...... Fuel Cell (SOFC). In the present study, a MSW gasification plant int egrated with SOFC is combined with a Stirling engine to recover the energy of the off - gases from the topping SOFC cycle. Detailed plant design is proposed and thermodynamic analysis is performed. Relevant parameters have been...

  4. A CO2-tolerant La2NiO4+δ-coated PrBa0.5Sr0.5Co1.5Fe0.5O5+δ cathode for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Li, Jin; Zhang, Qian; Qiu, Peng; Jia, Lichao; Chi, Bo; Pu, Jian; Li, Jian

    2017-02-01

    La2NiO4+δ (LN)-coated PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) composite cathode, designated as PBSCF-LN, for the intermediate temperature solid oxide fuel cells (IT-SOFCs) is prepared by solution infiltration, and investigated comparatively with single phase PBSCF cathode in the half and full cells using Ag and/or Pt paste as the current collector. Compared with Pt, Ag current collector results in a decrease of cathode polarization resistance (RP) by an order of magnitude, which suggests that Ag is electrocatalytically active and not suitable for the use of studying the cathode performance of IT-SOFCs. The RP value of PBSCF-LN cathode is significantly lower than that of PBSCF cathode, no matter whether Pt or Ag current collector is used for the measurement. High power densities ranging from 0.24 to 0.94 W cm-2 at temperatures between 600 and 750 °C are achieved using a full cell with PBSCF-LN cathode. Upon exposure to a CO2-rich atmosphere, carbonate particles are formed on the surface of PBSCF cathode, causing irreversible degradation of electrochemical performance. In contrast, the surface of PBSCF-LN cathode remains clean, and its performance degradation due to CO2 adsorption is recoverable.

  5. Synthesis and characterization of lanthanum manganite films for using in solid oxide fuel cells for operation at intermediate temperatures; Sintese e caracterizacao de filmes de manganita de lantanio para utilizacao em pilhas a combustivel de oxido solido para operacao em temperaturas intermediarias

    Energy Technology Data Exchange (ETDEWEB)

    Gama, L.M.; Paes Junior, H.R. [Laboratorio de Materiais Avancados - LAMAV - Universidade Estadual do Norte Fluminense - UENF, Campos dos Goytacazes, RJ (Brazil)

    2010-07-01

    This work aims to investigate the effects of doping and thermal processing of LaMnO{sub 3}, La{sub 0},{sub 8}Sr{sub 0},{sub 2}MnO{sub 3} e La{sub 0},{sub 8}Ca{sub 0},{sub 2}MnO{sub 3} films deposited by spray-pyrolysis technique on their structural, morphological and electrical properties, seeking its application as cathode in solid oxide fuel cells for operation in intermediate temperatures (IT-SOFC). These films were deposited on ferritic stainless steel type AISI 444. The thermal processing of the films was accomplished in air with treatment temperature of 900 degree or 1000 degree during 2 hours. The characterization by Xray diffraction revealed that the thermal processing propitiated the formation of the expected phases with the structure of perovskite. The analysis of surface morphology showed that doping provides an increase in porosity. Electrical characterization showed that Sr-doped films showed higher conductivity values and an activation energy of the conduction process of 0,41 eV. (author)

  6. Modeling and experimental validation of CO heterogeneous chemistry and electrochemistry in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Yurkiv, Vitaly

    2010-12-17

    In the present work experimental and numerical modeling studies of the heterogeneously catalyzed and electrochemical oxidation of CO at Nickel/yttria-stabilized zirconia (YSZ) solid oxide fuel cell (SOFC) anode systems were performed to evaluate elementary charge-transfer reaction mechanisms taking place at the three-phase boundary of CO/CO{sub 2} gas-phase, Ni electrode, and YSZ electrolyte. Temperature-programmed desorption and reaction experiments along with density functional theory calculations were performed to determine adsorption/desorption and surface diffusion kinetics as well as thermodynamic data for the CO/CO{sub 2}/Ni and CO/CO{sub 2}/YSZ systems. Based on these data elementary reaction based models with four different charge transfer mechanisms for the electrochemical CO oxidation were developed and applied in numerical simulations of literature experimental electrochemical data such as polarization curves and impedance spectra. Comparison between simulation and experiment demonstrated that only one of the four charge transfer mechanisms can consistently reproduce the electrochemical data over a wide range of operating temperatures and CO/CO{sub 2} gas compositions. (orig.) [German] In der vorliegenden Arbeit wurden experimentelle und numerische Untersuchungen zur heterogen katalysierten und elektrochemischen Oxidation von CO an Anodensystemen (bestehend aus Nickel und yttriumdotiertem Zirkoniumdioxid, YSZ) von Festoxidbrennstoffzellen (engl. Solid Oxide Fuel Cells, SOFCs) ausgefuehrt, um den mikroskopischen Mechanismus der an der CO/CO{sub 2}-Gasphase/Ni-Elektrode/YSZ-Elektrolyt- Dreiphasen-Grenzflaeche ablaufenden Ladungsuebertragungsreaktion aufzuklaeren. Temperaturprogrammierte Desorptionsmessungen (TPD) und Temperaturprogrammierte Reaktionsmessungen (TPR) sowie Dichtefunktionaltheorierechnungen wurden ausgefuehrt, um adsorptions-, desorptions- und reaktionskinetische sowie thermodynamische Daten fuer die CO/CO{sub 2}/Ni- und CO/CO{sub 2}/YSZ

  7. Low Temperature Processed Complementary Metal Oxide Semiconductor (CMOS) Device by Oxidation Effect from Capping Layer

    KAUST Repository

    Wang, Zhenwei

    2015-04-20

    In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190°C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

  8. Microstructure-scaled active sites imaging of a solid oxide fuel cell composite cathode

    Science.gov (United States)

    Nagasawa, Tsuyoshi; Hanamura, Katsunori

    2017-11-01

    Active sites for oxygen reduction reaction in strontium-doped lanthanum manganite (LSM)/scandia-stabilized zirconia (ScSZ) composite cathode of solid oxide fuel cell (SOFC) is visualized in microstructure scale by oxygen isotope labeling. In order to quench a reaction, a SOFC power generation equipment with a nozzle for direct helium gas impinging jet to the cell is prepared. A typical electrolyte-supported cell is operated by supplying 18O2 at 1073 K and abruptly quenched to room temperature. During the quench, the temperature of the cell is decreased from 1073 K to 673 K in 1 s. The 18O concentration distribution in the cross section of the quenched cathode is obtained by secondary ion mass spectrometry (SIMS) with a spatial resolution of 50 nm. The obtained 18O mapping gives the first visualization of highly distributed active sites in the composite cathode both in macroscopic and particle scales.

  9. Electroplating of Protective Coatings on Interconnects Used for Solid Oxide Fuel Cell Stacks

    DEFF Research Database (Denmark)

    Harthøj, Anders

    , are they can utilize a wide range of fuels, e.g. hydrogen, natural gas and methanol, do not contain noble metals and have a high efficiency. A major obstacle to the commercialization of SOFC technology is the high degradation rates and costs of the systems. A significant source of degradation is high......Solid oxide fuel Cell (SOFC) technology can with a high efficiency produce environmentally clean electricity by converting the chemical energy in a fuel to electrical energy. SOFC systems have a high operation temperature, approx. 600-850 °C. Advantages compared to other types of fuel cells...... temperature corrosion of the so called interconnects, which consists of high chromium ferritic steel. In an SOFC stack, interconnects connects the individual fuel cells electrically and mechanically. An interconnect is exposed to a dual atmosphere, with air on the side facing the SOFC cathode and fuel...

  10. Electrokinetic investigations of solid/organic liquid dispersions: Effects of temperature treatment of the solid and alkyl chain length of adsorbed amines

    Energy Technology Data Exchange (ETDEWEB)

    Jada, A.; Siffert, B.; Eleli-Letsango, J. [Centre de Recherches sur la Physico-Chimie des Surfaces Solides 24, avenue du President Kenedy 68200 MULHOUSE (France)

    1996-01-01

    Zeta potential of two oxides TiO{sub 2} and Al{sub 2}O{sub 3}, dispersed in various organic solvents were measured at room temperature. The inorganic particles were dried at temperatures ranging from 100 to 500{degree}C for several days and were allowed to cool under vacuum just before use. Electrokinetic investigations of TiO{sub 2} particles in n-alkylamine-hexane solutions with various amine chain lengths (C{sub n}H{sub 2n+1}NH{sub 2}, n=1{endash}10) were also done and allowed the determination of the shear plane position in the eventual electric double layer surrounding the solid surface. Furthermore, in order to estimate the thickness {delta} of the electrical double layer surrounding the solid surface, DLVO theory was applied to TiO{sub 2} particles dispersed in n-hexane, in the presence of butylamine. {copyright} {ital 1996 American Institute of Physics.}

  11. High-Temperature Oxide Regrowth on Mechanically-Damaged Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Lowe, Tracie M [ORNL

    2008-01-01

    Here we report the effects of mechanical damage from a sharp stylus on the regrowth of oxide layers on a Ni-based superalloy known as Pyromet 80A . It was found that the oxide that reformed on the damaged portion of a pre-oxidized surface differed from that which formed on undamaged areas after the equal exposures to elevated temperature in air. These findings have broad implications for modeling the processes of material degradation in applications such as exhaust valves in internal combustion engines because they imply that static oxidation data for candidate materials may not adequately reflect their reaction to operating environments that involve both mechanical contact and oxidation.

  12. Performance Comparison on Repowering of a Steam Power Plant with Gas Turbines and Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2016-01-01

    into an existing steam cycle which was built decades ago. Thus, traditional repowering results in combined cycles (CC). High temperature fuel cells (such as solid oxide fuel cell (SOFC)) could also be used as a topping cycle, achieving even higher global plant efficiency and even lower specific CO2 emissions....... Decreasing the operating temperature in a SOFC allows the use of less complex materials and construction methods, consequently reducing plant and the electricity costs. A lower working temperature makes it also suitable for topping an existing steam cycle, instead of gas turbines. This is also the target...

  13. Promotion of water-mediated carbon removal by nanostructured barium oxide/nickel interfaces in solid oxide fuel cells

    Science.gov (United States)

    Yang, Lei; Choi, YongMan; Qin, Wentao; Chen, Haiyan; Blinn, Kevin; Liu, Mingfei; Liu, Ping; Bai, Jianming; Tyson, Trevor A.; Liu, Meilin

    2011-01-01

    The existing Ni-yttria-stabilized zirconia anodes in solid oxide fuel cells (SOFCs) perform poorly in carbon-containing fuels because of coking and deactivation at desired operating temperatures. Here we report a new anode with nanostructured barium oxide/nickel (BaO/Ni) interfaces for low-cost SOFCs, demonstrating high power density and stability in C3H8, CO and gasified carbon fuels at 750°C. Synchrotron-based X-ray analyses and microscopy reveal that nanosized BaO islands grow on the Ni surface, creating numerous nanostructured BaO/Ni interfaces that readily adsorb water and facilitate water-mediated carbon removal reactions. Density functional theory calculations predict that the dissociated OH from H2O on BaO reacts with C on Ni near the BaO/Ni interface to produce CO and H species, which are then electrochemically oxidized at the triple-phase boundaries of the anode. This anode offers potential for ushering in a new generation of SOFCs for efficient, low-emission conversion of readily available fuels to electricity. PMID:21694705

  14. Promotion of water-mediated carbon removal by nanostructured barium oxide/nickel interfaces in solid oxide fuel cells.

    Science.gov (United States)

    Yang, Lei; Choi, YongMan; Qin, Wentao; Chen, Haiyan; Blinn, Kevin; Liu, Mingfei; Liu, Ping; Bai, Jianming; Tyson, Trevor A; Liu, Meilin

    2011-06-21

    The existing Ni-yttria-stabilized zirconia anodes in solid oxide fuel cells (SOFCs) perform poorly in carbon-containing fuels because of coking and deactivation at desired operating temperatures. Here we report a new anode with nanostructured barium oxide/nickel (BaO/Ni) interfaces for low-cost SOFCs, demonstrating high power density and stability in C(3)H(8), CO and gasified carbon fuels at 750°C. Synchrotron-based X-ray analyses and microscopy reveal that nanosized BaO islands grow on the Ni surface, creating numerous nanostructured BaO/Ni interfaces that readily adsorb water and facilitate water-mediated carbon removal reactions. Density functional theory calculations predict that the dissociated OH from H(2)O on BaO reacts with C on Ni near the BaO/Ni interface to produce CO and H species, which are then electrochemically oxidized at the triple-phase boundaries of the anode. This anode offers potential for ushering in a new generation of SOFCs for efficient, low-emission conversion of readily available fuels to electricity.

  15. Novel Mg-Doped SrMoO3 Perovskites Designed as Anode Materials for Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Vanessa Cascos

    2016-07-01

    Full Text Available SrMo1−xMxO3−δ (M = Fe and Cr, x = 0.1 and 0.2 oxides have been recently described as excellent anode materials for solid oxide fuel cells at intermediate temperatures (IT-SOFC with LSGM as the electrolyte. In this work, we have improved their properties by doping with aliovalent Mg ions at the B-site of the parent SrMoO3 perovskite. SrMo1−xMgxO3−δ (x = 0.1, 0.2 oxides have been prepared, characterized and tested as anode materials in single solid-oxide fuel cells, yielding output powers near 900 mW/cm−2 at 850 °C using pure H2 as fuel. We have studied its crystal structure with an “in situ” neutron power diffraction (NPD experiment at temperatures as high as 800 °C, emulating the working conditions of an SOFC. Adequately high oxygen deficiencies, observed by NPD, together with elevated disk-shaped anisotropic displacement factors suggest a high ionic conductivity at the working temperatures. Furthermore, thermal expansion measurements, chemical compatibility with the LSGM electrolyte, electronic conductivity and reversibility upon cycling in oxidizing-reducing atmospheres have been carried out to find out the correlation between the excellent performance as an anode and the structural features.

  16. Lanthanum manganate based cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Juhl Joergensen, M.

    2001-07-01

    Composite cathodes for solid oxide fuel cells were investigated using electrochemical impedance spectroscopy and scanning electron microscopy. The aim was to study the oxygen reduction process in the electrode in order to minimise the voltage drop in the cathode. The electrodes contained a composite layer made from lanthanum strontium manganate (LSM) and yttria stabilised zirconia (YSZ) and a layer of pure LSM aimed for current collection. The performance of the composite electrodes was sensitive to microstructure and thickness. Further, the interface between the composite and the current collecting layer proved to affect the performance. In a durability study severe deg-radation of the composite electrodes was found when passing current through the electrode for 2000 hours at 1000 deg. C. This was ascribed to pore formation along the composite interfaces and densification of the composite and current collector microstructure. An evaluation of the measurement approach indicated that impedance spectroscopy is a very sensitive method. This affects the reproducibility, as small undesirable variations in for instance the microstructure from electrode to electrode may change the impedance. At least five processes were found to affect the impedance of LSM/YSZ composite electrodes. Two high frequency processes were ascribed to transport of oxide ions/oxygen intermediates across LSM/YSZ interfaces and through YSZ in the composite. Several competitive elementary reaction steps, which appear as one medium frequency process in the impedance spectra, were observed. A low frequency arc related to gas diffusion limitation in a stagnant gas layer above the composite structure was detected. Finally, an inductive process, assumed to be connected to an activation process involving segregates at the triple phase boundary between electrode, electrolyte and gas phase, was found. (au)

  17. Tailoring gadolinium-doped ceria-based solid oxide fuel cells to achieve 2 W cm(-2) at 550 °C.

    Science.gov (United States)

    Lee, Jin Goo; Park, Jeong Ho; Shul, Yong Gun

    2014-06-04

    Low-temperature operation is necessary for next-generation solid oxide fuel cells due to the wide variety of their applications. However, significant increases in the fuel cell losses appear in the low-temperature solid oxide fuel cells, which reduce the cell performance. To overcome this problem, here we report Gd0.1Ce0.9O1.95-based low-temperature solid oxide fuel cells with nanocomposite anode functional layers, thin electrolytes and core/shell fibre-structured Ba0.5Sr0.5Co0.8Fe0.2O3-δ-Gd0.1Ce0.9O1.95 cathodes. In particular, the report describes the use of the advanced electrospinning and Pechini process in the preparation of the core/shell-fibre-structured cathodes. The fuel cells show a very high performance of 2 W cm(-2) at 550 °C in hydrogen, and are stable for 300 h even under the high current density of 1 A cm(-2). Hence, the results suggest that stable and high-performance solid oxide fuel cells at low temperatures can be achieved by modifying the microstructures of solid oxide fuel cell components.

  18. Auger electron spectroscopy study of oxidation of a PdCr alloy used for high-temperature sensors

    Science.gov (United States)

    Boyd, Darwin L.; Zeller, Mary V.; Vargas-Aburto, Carlos

    1993-01-01

    A Pd-13 wt. percent Cr solid solution is a promising high-temperature strain gage alloy. In bulk form it has a number of properties that are desirable in a resistance strain gage material, such as a linear electrical resistance versus temperature curve to 1000 C and stable electrical resistance in air at 1000 C. However, unprotected fine wire gages fabricated from this alloy perform well only to 600 C. At higher temperatures severe oxidation degrades their electrical performance. In this work Auger electron spectroscopy was used to study the oxidation chemistry of the alloy wires and ribbons. Results indicate that the oxidation is caused by a complex mechanism that is not yet fully understood. As expected, during oxidation, a layer of chromium oxide is formed. This layer, however, forms beneath a layer of metallic palladium. The results of this study have increased the understanding of the oxidation mechanism of Pd-13 wt. percent Cr.

  19. Inkjet Impregnation for Tailoring Air Electrode Microstructure to Improve Solid Oxide Cells Performance

    KAUST Repository

    Da’as, Eman H.

    2015-09-30

    The urge to lower the operating temperature of solid oxide cells (SOCs) to the intermediate ranges between 500-700°C motivated the research into impregnation processes, which offer highly efficient SOC air electrodes at low operating temperatures. Lack of controllability and reproducibility of this technique in the conventional way is still considered as an inadequacy for industrialization since it is performed manually. Therefore, inkjet-printing technology was proposed as an adequate approach to perform scalable and controllable impregnation for SOC air electrodes, which in turn leads to low operating temperatures. Composite LSM-ionic conductive air electrodes of weight ratio 1:2 were fabricated by inkjet impregnation of lanthanum strontium manganite (La0.8Sr0.2MnO3) precursor nitrates onto a porous ionic conductive backbone structure. First, porous yttria stabilized zirconia (8YSZ) substrates prepared by tape casting were used to study the influence of the printing parameters on the lateral dispersion and penetration of LSM ink inside the pores. XRD analysis confirmed the formation of LSM phase after calcination at 800°C for 2 h, while SEM revealed the formation of LSM nanostructures. It has been found by optical microscope observations that the spacing between the drops and the substrate temperature have a significant role in controlling the printing process. Next, the optimized printing parameters were applied in the inkjet impregnation of the LSM ink into porous YSZ electrodes that were spin coated on both sides of dense YSZ layers. LSM-YSZ composite air electrodes achieved an area specific resistance (ASR) of around 0.29 Ω.cm2 at 700°C. The performance of LSM-YSZ composite electrodes was influenced by the microstructure and the thickness, and by the electrode/electrolyte interface characteristics. As a result, the enhancement in LSM-YSZ composite electrode performance was observed due to the better percolation in LSM, YSZ and oxygen diffusion. Finally

  20. Synthesis, Characterization, and Optimization of Novel Solid Oxide Fuel Cell Anodes

    Science.gov (United States)

    Miller, Elizabeth C.

    This dissertation presents research on the development of novel materials and fabrication procedures for solid oxide fuel cell (SOFC) anodes. The work discussed here is divided into three main categories: all-oxide anodes, catalyst exsolution oxide anodes, and Ni-infiltrated anodes. The all-oxide and catalyst exsolution anodes presented here are further classi?ed as Ni-free anodes operating at the standard 700-800°C SOFC temperature while the Ni-infiltrated anodes operate at intermediate temperatures (≤650°C). Compared with the current state-of-the-art Ni-based cermets, all-oxide, Ni-free SOFC anodes offer fewer coking issues in carbon-containing fuels, reduced degradation due to fuel contaminants, and improved stability during redox cycling. However, electrochemical performance has proven inferior to Ni-based anodes. The perovskite oxide Fe-substituted strontium titanate (STF) has shown potential as an anode material both as a single phase electrode and when combined with Gd-doped ceria (GDC) in a composite electrode. In this work, STF is synthesized using a modified Pechini processes with the aim of reducing STF particle size and increasing the electrochemically active area in the anode. The Pechini method produced particles ? 750 nm in diameter, which is signi°Cantly smaller than the typically micron-sized solid state reaction powder. In the first iteration of anode fabrication with the Pechini powder, issues with over-sintering of the small STF particles limited gas di?usion in the anode. However, after modifying the anode firing temperature, the Pechini cells produced power density comparable to solid state reaction based cells from previous work by Cho et al. Catalyst exsolution anodes, in which metal cations exsolve out of the lattice under reducing conditions and form nanoparticles on the oxide surface, are another Ni-free option for standard operating temperature SOFCs. Little information is known about the onset of nanoparticle formation, which

  1. Reversible Poisoning of the Nickel/Zirconia Solid Oxide Fuel Cell Anodes by Hydrogen Chloride in Coal Gas

    Energy Technology Data Exchange (ETDEWEB)

    Marina, Olga A.; Pederson, Larry R.; Thomsen, Edwin C.; Coyle, Christopher A.; Yoon, Kyung J.

    2010-10-15

    The performance of anode-supported solid oxide fuel cells (SOFC) was evaluated in synthetic coal gas containing HCl in the temperature range 650 to 850oC. Exposure to up to 800 ppm HCl resulted in reversible poisoning of the Ni/zirconia anode by chlorine species adsorption, the magnitude of which decreased with increased temperature. Performance losses increased with the concentration of HCl to ~100 ppm, above which losses were insensitive to HCl concentration. Cell voltage had no effect on poisoning. No evidence was found for long-term degradation that can be attributed to HCl exposure. Similarly, no evidence of microstructural changes or formation of new solid phases as a result of HCl exposure was found. From thermodynamic calculations, solid nickel chloride phase formation was shown to be highly unlikely in coal gas. Further, the presence of HCl at even the highest anticipated concentrations in coal gas would minimally increase the volatility of nickel.

  2. Application of hydrogen injection and oxidation to low temperature solution-processed oxide semiconductors

    Directory of Open Access Journals (Sweden)

    Masashi Miyakawa

    2016-08-01

    Full Text Available Solution-processed oxide semiconductors are promising candidates for the low cost, large scale fabrication of oxide thin-film transistors (TFTs. In this work, a method using hydrogen injection and oxidation (HIO that allows the low temperature solution processing of oxide semiconductors was demonstrated. We found that this method significantly decreases the concentration of residual species while improving the film densification. Additionally, enhanced TFT performance was confirmed following the use of processing temperatures as low as 300 °C. The proposed process is potentially applicable to the fabrication of a wide variety of solution-processed oxide semiconductors.

  3. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  4. Durability of solid oxide fuel cells using sulfur containing fuels

    DEFF Research Database (Denmark)

    Hagen, Anke; Rasmussen, Jens Foldager Bregnballe; Thydén, Karl Tor Sune

    2011-01-01

    The usability of hydrogen and also carbon containing fuels is one of the important advantages of solid oxide fuel cells (SOFCs), which opens the possibility to use fuels derived from conventional sources such as natural gas and from renewable sources such as biogas. Impurities like sulfur compounds...... are critical in this respect. State-of-the-art Ni/YSZ SOFC anodes suffer from being rather sensitive towards sulfur impurities. In the current study, anode supported SOFCs with Ni/YSZ or Ni/ScYSZ anodes were exposed to H2S in the ppm range both for short periods of 24h and for a few hundred hours. In a fuel...... to a loss of percolation of Ni particles in the Ni/YSZ anode layers closest to the electrolyte. Using SOFCs with Ni/ScYSZ anodes improved the H2S tolerance considerably, even at larger H2S concentrations of 10 and 20ppm over a few hundred hours....

  5. Solid oxide fuel cell application in district cooling

    Science.gov (United States)

    Al-Qattan, Ayman; ElSherbini, Abdelrahman; Al-Ajmi, Kholoud

    2014-07-01

    This paper presents analysis of the performance of a combined cooling and power (CCP) system for district cooling. The cogeneration system is designed to provide cooling for a low-rise residential district of 27,300 RT (96 MWc). A solid oxide fuel cell (SOFC) generates electric power to operate chillers, and the exhaust fuel and heat from the SOFC run gas turbines and absorption chillers. Thermal energy storage is utilized to reduce system capacity. Part-load operation strategies target maximizing energy efficiency. The operation of the system is compared through an hourly simulation to that of packaged air-conditioning units typically used to cool homes. The CCP system with the district cooling arrangement improves the cooling-to-fuel efficiency by 346%. The peak power requirement is reduced by 57% (24 MW) and the total fuel energy is reduced by 54% (750 TJ y-1). The system cuts annual carbon dioxide emissions to less than half and reduces other harmful emissions. A cost analysis of the system components and operation resulted in a 53% reduction in the cost per ton-hour of cooling over traditional systems.

  6. Integrated Solid Oxide Fuel Cell Power System Characteristics Prediction

    Directory of Open Access Journals (Sweden)

    Marian GAICEANU

    2009-07-01

    Full Text Available The main objective of this paper is to deduce the specific characteristics of the CHP 100kWe Solid Oxide Fuel Cell (SOFC Power System from the steady state experimental data. From the experimental data, the authors have been developed and validated the steady state mathematical model. From the control room the steady state experimental data of the SOFC power conditioning are available and using the developed steady state mathematical model, the authors have been obtained the characteristic curves of the system performed by Siemens-Westinghouse Power Corporation. As a methodology the backward and forward power flow analysis has been employed. The backward power flow makes possible to obtain the SOFC power system operating point at different load levels, resulting as the load characteristic. By knowing the fuel cell output characteristic, the forward power flow analysis is used to predict the power system efficiency in different operating points, to choose the adequate control decision in order to obtain the high efficiency operation of the SOFC power system at different load levels. The CHP 100kWe power system is located at Gas Turbine Technologies Company (a Siemens Subsidiary, TurboCare brand in Turin, Italy. The work was carried out through the Energia da Ossidi Solidi (EOS Project. The SOFC stack delivers constant power permanently in order to supply the electric and thermal power both to the TurboCare Company and to the national grid.

  7. Use of alternative fuels in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-05-15

    A future sustainable energy system will certainly be based on a variety of environmentally benign energy production technologies. Fuel cells can be a key element in this scenario. One of the fuel cells types the solid oxide fuel cell (SOFC) has a number of advantages that places them in a favorable position: high efficiency, parallel production of electricity and high value heat, prevention of NOx emission, flexibility regarding usable fuels, and certain tolerance towards impurities. It is thus a natural option, to combine such a highly efficient energy conversion tool with a sustainable fuel supply. In the present contribution, the use of alternative compared to conventional fuels in SOFCs was evaluated. Regarding carbon containing, biomass derived fuels, SOFCs showed excellent power output and stability behavior during long-term testing under technologically relevant conditions. Moreover, ammonia can be used directly as fuel. The chemical and structural properties of the SOFC anode makes it even possible, to combine a chemical conversion of the fuel, for example methane into synthesis gas via steam reforming and decomposition of ammonia into hydrogen and nitrogen, with the electrochemical production of electricity in one step. (au)

  8. Solid oxide fuel cell performance under severe operating conditions

    DEFF Research Database (Denmark)

    Koch, Søren; Hendriksen, P.V.; Mogensen, Mogens Bjerg

    2006-01-01

    The performance and degradation of Solid Oxide Fuel Cells (SOFC) were studied under severe operating conditions. The cells studied were manufactured in a small series by ECN, in the framework of the EU funded CORE-SOFC project. The cells were of the anode-supported type with a double layer LSM...... cathode. They were operated at 750 °C or 850 °C in hydrogen with 5% or 50% water at current densities ranging from 0.25 A cm–2 to 1 A cm–2 for periods of 300 hours or more. The area specific cell resistance, corrected for fuel utilisation, ranged between 0.20 Ω cm2 and 0.34 Ω cm2 at 850 °C and 520 m......V, and between 0.51 Ω cm2 and 0.92 Ω cm2 at 750 °C and 520 mV. The degradation of cell performance was found to be low (ranging from 0 to 8%/1,000 hours) at regular operating conditions. Voltage degradation rates of 20 to 40%/1,000 hours were observed under severe operating conditions, depending on the test...

  9. Electrolysis of carbon dioxide in Solid Oxide Electrolysis Cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune; Mogensen, Mogens Bjerg

    2009-01-01

    Carbon dioxide electrolysis was studied in Ni/YSZ electrode supported Solid Oxide Electrolysis Cells (SOECs) consisting of a Ni-YSZ support, a Ni-YSZ electrode layer, a YSZ electrolyte, and a LSM-YSZ O2 electrode (YSZ = Yttria Stabilized Zirconia). The results of this study show that long term CO2...... electrolysis is possible in SOECs with nickel electrodes.The passivation rate of the SOEC was between 0.22 and 0.44 mV h−1 when operated in mixtures of CO2/CO = 70/30 or CO2/CO = 98/02 (industrial grade) at 850 °C and current densities between −0.25 and −0.50 A cm−2. The passivation rate was independent...... in the gas stream, most likely sulphur, adsorbing on some specific nickel sites in the cathode of the SOEC. Activation can be carried out by hydrogen reacting with adsorbed sulphur to form the volatile compound H2S. Because adsorption of sulphur is site specific, only a part of the nickel sites were...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    W.L. Lundberg; G.A. Israelson; R.R. Moritz(Rolls-Royce Allison); S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann (Consultant)

    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.

  12. Development of improved cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, H.U.

    1991-03-01

    The University of Missouri-Rolla conducted a 17 month research program focused on the development and evaluation of improved cathode materials for solid oxide fuel cells (SOFC). The objectives of this program were: (1) the development of cathode materials of improved stability in reducing environments; and (2) the development of cathode materials with improved electrical conductivity. The program was successful in identifying some potential candidate materials: Air sinterable (La,Ca)(Cr,Co)O{sub 3} compositions were developed and found to be more stable than La{sub .8}Sr{sub .2}MnO{sub 3} towards reduction. Their conductivity at 1000{degrees}C ranged between 30 to 60 S/cm. Compositions within the (Y,Ca)(Cr,Co,Mn)O{sub 3} system were developed and found to have higher electrical conductivity than La{sub .8}Sr{sub .2}MnO{sub 3} and preliminary results suggest that their stability towards reduction is superior.

  13. Effective improvement of interface modified strontium titanate based solid oxide fuel cell anodes by infiltration with nano-sized palladium and gadolinium-doped cerium oxide

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei

    2013-01-01

    ) contributed to a significant improvement in performance of the STN backbones and infiltrated electrodes. The improvement is due to the result of CGO enrichment at the interface. The impedance analysis showed that addition of Pd further increased the electrode reaction rate with a factor 10 with respect......The development of low temperature solid oxide fuel cell (SOFC) anodes by infiltration of Pd/Gd-doped cerium oxide (CGO) electrocatalysts in Nb-doped SrTiO3 (STN) backbones has been investigated. Modification of the electrode/electrolyte interface by thin layer of spin-coated CGO (400-500 nm...

  14. Effect of oxidation and annealing temperature on optical and ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 37; Issue 3. Effect of oxidation and ... Keywords. SnO2 thin films; optical properties; optical bandgap; Urbach energy; surface roughness; XRD. ... The effect of oxidation temperature on the optical and structural properties of SnO2 films were investigated. Higher ...

  15. Effect of oxidation and annealing temperature on optical and ...

    Indian Academy of Sciences (India)

    Administrator

    which means that initial oxidation temperature played an important role on surface uniformity of SnO2 thin films. Keywords. SnO2 thin films; optical properties; optical bandgap; Urbach energy; surface roughness; XRD. 1. Introduction. Tin oxide belongs to a class of materials that have suitable electrical conductivity and high ...

  16. Propane Oxidation at High Pressure and Intermediate Temperatures

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Glarborg, Peter

    Propane oxidation at intermediate temperatures (500—900 K) and high pressure (100 bar) has been characterized by conducting experiments in a laminar flow reactor over a wide range of stoichiometries. The onset of fuel oxidation was found to be 600—725 K, depending on mixture stoichiometry...

  17. Electrochemical characterization of Fe-air rechargeable oxide battery in planar solid oxide cell stacks

    Science.gov (United States)

    Fang, Qingping; Berger, Cornelius M.; Menzler, Norbert H.; Bram, Martin; Blum, Ludger

    2016-12-01

    Iron-air rechargeable oxide batteries (ROB) comprising solid oxide cells (SOC) as energy converters and Fe/metal-oxide redox couples were characterized using planar SOC stacks. The charge and discharge of the battery correspond to the operations in the electrolysis and fuel cell modes, respectively, but with a stagnant atmosphere consisting of hydrogen and steam. A novel method was employed to establish the stagnant atmosphere for battery testing during normal SOC operation without complicated modification to the test bench and stack/battery concept. Manipulation of the gas compositions during battery operation was not necessary, but the influence of the leakage current from the testing system had to be considered. Batteries incorporating Fe2O3/8YSZ, Fe2O3/CaO and Fe2O3/ZrO2 storage materials were characterized at 800 °C. A maximum charge capacity of 30.4 Ah per layer (with an 80 cm2 active cell area) with ∼0.5 mol Fe was reached with a current of 12 A. The charge capacity lost 11% after ∼130 ROB cycles due to the increased agglomeration of active materials and formation of a dense oxide layer on the surface. The round trip efficiencies of the tested batteries were ≤84% due to the large internal resistance. With state-of-the-art cells, the round trip efficiency can be further improved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Minh, N.Q. [AlliedSignal Aerospce Equipment Systems, Torrance, CA (United States)

    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.

  19. Process simulation of biomass gasification integrated with a solid oxide fuel cell stack

    Science.gov (United States)

    Doherty, Wayne; Reynolds, Anthony; Kennedy, David

    2015-03-01

    Biomass gasification-solid oxide fuel cell (BG-SOFC) combined heat and power (CHP) systems are of major interest in the context of climate change mitigation, energy security and increasing energy efficiency. Aspen Plus is employed to simulate various BG-SOFC CHP systems. The aim of the research work is to investigate the technical feasibility of these systems and to study the influence of important operating parameters and examine integration options. Systems based on dual fluidised bed steam gasification and tubular SOFC technologies are modelled. The cathode recycle and electric heater integration options are not attractive in comparison to the base case anode recycle system. Thermal integration, i.e. using SOFC flue gas as gasifier oxidant, is desirable. Lowering the syngas preheat temperature (prior to SOFC anodes) is highly recommended and is more practical than lowering the cathode air preheat temperature. Results of the parametric study indicate that: steam to carbon ratio and biomass moisture content should be as low as possible; fuel utilisation factor can change the mode of operation of the plant (focus on electricity or heat); high temperature syngas cleaning is very attractive; gasification air preheating is more attractive than gasification steam superheating. High efficiencies are predicted, proving the technical feasibility of BG-SOFC CHP systems.

  20. Study of Solid Particle Behavior in High Temperature Gas Flows

    Science.gov (United States)

    Majid, A.; Bauder, U.; Stindl, T.; Fertig, M.; Herdrich, G.; Röser, H.-P.

    2009-01-01

    The Euler-Lagrangian approach is used for the simulation of solid particles in hypersonic entry flows. For flow field simulation, the program SINA (Sequential Iterative Non-equilibrium Algorithm) developed at the Institut für Raumfahrtsysteme is used. The model for the effect of the carrier gas on a particle includes drag force and particle heating only. Other parameters like lift Magnus force or damping torque are not taken into account so far. The reverse effect of the particle phase on the gaseous phase is currently neglected. Parametric analysis is done regarding the impact of variation in the physical input conditions like position, velocity, size and material of the particle. Convective heat fluxes onto the surface of the particle and its radiative cooling are discussed. The variation of particle temperature under different conditions is presented. The influence of various input conditions on the trajectory is explained. A semi empirical model for the particle wall interaction is also discussed and the influence of the wall on the particle trajectory with different particle conditions is presented. The heat fluxes onto the wall due to impingement of particles are also computed and compared with the heat fluxes from the gas.

  1. High temperature oxidation resistance of rare earth chromite coated Fe-20Cr and Fe-20Cr-4Al alloys

    Directory of Open Access Journals (Sweden)

    Marina Fuser Pillis

    2007-09-01

    Full Text Available Doped lanthanum chromite has been used in solid oxide fuel cell (SOFC interconnects. The high costs involved in obtaining dense lanthanum chromite have increased efforts to find suitable metallic materials for interconnects. In this context, the oxidation behavior of lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys at SOFC operation temperature was studied. Isothermal oxidation tests were carried out at 1000 °C for 20, 50 and 200 hours. Cyclic oxidation tests were also carried out and each oxidation cycle consisted of 7 hours at 1000/°C followed by cooling to room temperature. The oxidation measurements and the results of SEM/EDS as well as XRD analyses indicated that lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys were significantly more resistant to oxidation compared with the uncoated alloys.

  2. EFFECT SIGNIFICANCE ASSESSMENT OF THE THERMODYNAMICAL FACTORS ON THE SOLID OXIDE FUEL CELL OPERATION

    Directory of Open Access Journals (Sweden)

    V. A. Sednin

    2015-01-01

    Full Text Available Technologies of direct conversion of the fuel energy into electrical power are an upcoming trend in power economy. Over the last decades a number of countries have created industrial prototypes of power plants on fuel elements (cells, while fuel cells themselves became a commercial product on the world energy market. High electrical efficiency of the fuel cells allows predictting their further spread as part of hybrid installations jointly with gas and steam turbines which specifically enables achieving the electrical efficiency greater than 70 %. Nevertheless, investigations in the area of increasing efficiency and reliability of the fuel cells continue. Inter alia, research into the effects of oxidizing reaction thermodynamic parameters, fuel composition and oxidation reaction products on effectiveness of the solid oxide fuel cells (SOFC is of specific scientific interest. The article presents a concise analysis of the fuel type effects on the SOFC efficiency. Based on the open publications experimental data and the data of numerical model studies, the authors adduce results of the statistical analysis of the SOFC thermodynamic parameters effect on the effectiveness of its functioning as well as of the reciprocative factors of these parameters and gas composition at the inlet and at the outlet of the cell. The presented diagrams reflect dimension of the indicated parameters on the SOFC operation effectiveness. The significance levels of the above listed factors are ascertained. Statistical analysis of the effects of the SOFC functionning process thermodynamical, consumption and concentration parameters demonstrates quintessential influence of the reciprocative factors (temperature – flow-rate and pressure – flow-rate and the nitrogen N2 and oxygen O2 concentrations on the operation efficiency in the researched range of its functioning. These are the parameters to be considered on a first-priority basis while developing mathematical models

  3. Temperature and high pressure effects on the structural features of catalytic nanocomposites oxides by Raman spectroscopy

    Science.gov (United States)

    da Silva, Antonio N.; Pinto, Raffael C. F.; Freire, Paulo T. C.; Junior, Jose Alves L.; Oliveira, Alcineia C.; Filho, Josué M.

    2015-03-01

    Structural characterizations of nanostructured oxides were studied by X-ray diffraction (XRD), Raman and infrared spectroscopy. The oxides catalysts namely, SnO2, ZrO2, CeO2, MnOx, Al2O3 and TiO2 were prepared by a nanocasting route and the effect of the temperature and pressure on the stability of the solids was evaluated. Raman spectra showed that ZrO2 and TiO2 exhibited phase transitions at moderate temperatures whereas CeO2, SnO2 and MnOx had an effective creation of defects in their structures upon annealing at elevated temperatures. The results suggested also that the effect of the temperature on the particles growth is related to the type of oxide. In this regard, phase transition by up to 600 °C accelerated the sintering of ZrO2 and CeO2 grains compared to TiO2, SnO2 and MnOx counterparts. Under hydrostatic pressures lower than 10 GPa, rutile TiO2 and tetragonal ZrO2 exhibited pressure induced phase transition whereas CeO2 and SnO2 were stable at pressures close to 15 GPa. The experiments revealed that the nanostructured SnO2 oxide exhibited stable performance at relatively high temperatures without phase transition or sintering, being suitable to be used as catalysts in the range of temperature and pressure studied.

  4. Planar solid oxide fuel cell with staged indirect-internal air and fuel preheating and reformation

    Science.gov (United States)

    Geisbrecht, Rodney A; Williams, Mark C

    2003-10-21

    A solid oxide fuel cell arrangement and method of use that provides internal preheating of both fuel and air in order to maintain the optimum operating temperature for the production of energy. The internal preheat passes are created by the addition of two plates, one on either side of the bipolar plate, such that these plates create additional passes through the fuel cell. This internal preheat fuel cell configuration and method reduce the requirements for external heat exchanger units and air compressors. Air or fuel may be added to the fuel cell as required to maintain the optimum operating temperature through a cathode control valve or an anode control valve, respectively. A control loop comprises a temperature sensing means within the preheat air and fuel passes, a means to compare the measured temperature to a set point temperature and a determination based on the comparison as to whether the control valves should allow additional air or fuel into the preheat or bypass manifolds of the fuel cell.

  5. High temperature oxidation of slurry coated interconnect alloys

    DEFF Research Database (Denmark)

    Persson, Åsa Helen

    with this interaction mechanism mainly give a geometrical protection against oxidation by blocking oxygen access at the surface of the oxide scale. The protecting effect is gradually reduced as the oxide scale grows thicker than the diameter of the coating particles. Interaction mechanism B entails a chemical reaction.......85Sr0.15)CoO3 + 10% Co3O4, LSC, coatings were found to be relatively successful in decreasing the oxidation rate, the chromium content in the outermost part of ii the dense scale, and the electrical resistance in the growing oxide scales when applied onto Crofer 22APU. But, the positive effects......In this project, high temperature oxidation experiments of slurry coated ferritic alloys in atmospheres similar to the atmosphere found at the cathode in an SOFC were conducted. From the observations possible interaction mechanisms between the slurry coatings and the growing oxide scale...

  6. Coprecipitation synthesis and characterization of La0.8Sr0.2Ga(0.8-x)Mg0.2Co(x)O2.8 for intermediate temperature solid oxide fuel cell electrolytes.

    Science.gov (United States)

    Lee, Jin Goo; Yoon, Hyon Hee

    2012-01-01

    La0.8Sr0.2Ga(0.8-x)Mg0.2CO(x)O2.8 (LSGMC) electrolyte powders containing different amount of Co (0 coprecipitation method. The precursors, the calcined powders, and the sintered pellets were characterized by thermogravimetry/differential thermal analysis, X-ray diffractometry, scanning electron microscopy, and an impedance analyzer. The thermal decomposition of the LSGMC precursors was completed at around 900 degrees C with the total weight loss of approximately 35%. The LSGMC samples sintered at 1350 degrees C consisted of the pure perovskite structure. The ionic conductivity was significantly improved by Co doping for the Ga-site of the La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) electrolytes. The ionic conductivity of LSGMC (x = 0.1) exhibited the highest values of 1.6 x 10(-1) S cm(-1) at 700 degrees C with an activation energy for the oxide-ion conduction of 0.29 eV. The results of this study indicated that the Co-doped LSGM electrolytes had excellent properties for use as an electrolyte in an IT-SOFC and the ammonium carbonate coprecipitation process could be employed as the efficient method for the preparation of the Co-doped LSGM electrolytes.

  7. Low temperature solid oxide fuel cells based on Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} films fabricated by slurry spin coating

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Na; Lue, Zhe; Chen, Kongfa; Huang, Xiqiang; Wei, Bo; Zhang, Yaohui; Li, Shuyan; Xin, Xianshuang; Sha, Xueqing; Su, Wenhui [Center for Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2006-09-13

    A simple and effective slurry spin coating approach was developed for fabricating Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} (SDC) films on porous NiO-SDC anode substrates. A dense SDC film with a thickness of {approx}15{mu}m was obtained after sintering at 1400{sup o}C for 4h. With the same approach, the novel Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF)-SDC composite cathode layer was fabricated on the film. When dry hydrogen was used as the fuel and stationary air as the oxidant, maximum power densities of the cell were 648mWcm{sup -2} at 600{sup o}C and 869mWcm{sup -2} at 650{sup o}C, respectively. AC impedance analysis indicated that the resistance of the cell under open-circuit conditions was essentially dominated by the interfacial resistance. The activation energies of the interfacial resistance and the ohmic resistance were 99.49 and 54.30kJmol{sup -1}, respectively. (author)

  8. The evolution of titanium oxidation at elevated temperature and its oxide scale morphology

    Science.gov (United States)

    Imbrie, Peter Kenneth

    The purpose of this study was to experimentally quantify the multi-dimensional growth characteristics of the oxide scale formed on commercially pure titanium at 700°C in a flowing air environment. The geometries considered herein had characteristic dimensions that were appropriately sized to match the thickness of the oxide scale and were fabricated into shapes of solid and hollow cylinders and external and internal wedges. Scanning electron microscopy (SEM) image analysis was used to measure the oxide layer thickness and the Pilling-Bedworth ratio (PBR) as a function of time. An effective diffusion coefficient was determined from one-dimensional planar oxide thickness data and experimentally obtained PBR values served as the necessary input to a solid state diffusion model, which was modified to account for the volumetric expansion of the oxide. Oxidation of the solid cylinder and external wedge geometries were shown to develop a scale morphology similar to that observed on a flat specimen. The oxide had two notable features: (1) at the air-oxide interface, the oxide appeared to be compact and its thickness grew with time and (2) from the metal-oxide interface up to the compact scale, the oxide was found to have a porous-layered arrangement with the pore size being a function of distance from the metal-oxide interface. Conversely, the oxide scale growth on the hollow cylinders and external wedges, while still layered, appeared to be much less porous and had considerably less cracking and spalling damage. The modified solid-state diffusion model and experimentally obtained values of the diffusion coefficient and PBR were used to demonstrate the competing influences of oxide expansion and curvature effects. In addition, the predictive capability of the model, for the case of a solid cylinder, was shown to under predict experimental results, whereas scale growth on the inner surface of a hollow cylinder was over predicted. The differences are primarily attributed to

  9. Effect of binder burnout on the sealing performance of glass ceramics for solid oxide fuel cells

    Science.gov (United States)

    Ertugrul, Tugrul Y.; Celik, Selahattin; Mat, Mahmut D.

    2013-11-01

    The glass ceramics composite sealants are among few materials suitable for the solid oxide fuel cells (SOFC) due to their high operating temperatures (600 °C-850 °C). The glass ceramics chemically bond to both the metallic interconnector and the ceramic electrolyte and provide a gas tight connection. A careful and several stages manufacturing procedure is required to obtain a gas tight sealing. In this study, effects of binder burnout process on the sealing performance are investigated employing commercially available glass ceramic powders. The glass ceramic laminates are produced by mixing glass ceramic powders with the organic binders and employing a tape casting method. The laminates are sandwiched between the metallic interconnectors of an SOFC cell. The burnout and subsequent sealing quality are analyzed by measuring leakage rate and final macrostructure of sealing region. The effects of heating rate, dead weight load, solid loading, carrier gas and their flow rates are investigated. It is found that sealing quality is affected from all investigated parameters. While a slower heating rate is required for a better burnout, the mass flow rate of sweep gas must be adequate for removal of the burned gas. The leakage rate is reduced to 0.1 ml min-1 with 2 °C min-1 + 1 °C min-1 heating rate, 86.25% solid loading, 200 N dead weight load and 500 ml min-1 sweep gas flow rate.

  10. Temperature dependent dielectric properties and ion transportation in solid polymer electrolyte for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sengwa, R. J., E-mail: rjsengwa@rediffmail.com; Dhatarwal, Priyanka, E-mail: dhatarwalpriyanka@gmail.com; Choudhary, Shobhna, E-mail: shobhnachoudhary@rediffmail.com [Dielectric Research Laboratory, Department of Physics, Jai Narain Vyas University, Jodhpur – 342 005 (India)

    2016-05-06

    Solid polymer electrolyte (SPE) film consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrix with lithium tetrafluroborate (LiBF{sub 4}) as dopant ionic salt and poly(ethylene glycol) (PEG) as plasticizer has been prepared by solution casting method followed by melt pressing. Dielectric properties and ionic conductivity of the SPE film at different temperatures have been determined by dielectric relaxation spectroscopy. It has been observed that the dc ionic conductivity of the SPE film increases with increase of temperature and also the decrease of relaxation time. The temperature dependent relaxation time and ionic conductivity values of the electrolyte are governed by the Arrhenius relation. Correlation observed between dc conductivity and relaxation time confirms that ion transportation occurs with polymer chain segmental dynamics through hopping mechanism. The room temperature ionic conductivity is found to be 4 × 10{sup −6} S cm{sup −1} which suggests the suitability of the SPE film for rechargeable lithium batteries.

  11. Electrochemical performance of (Ba{sub 0.5}Sr{sub 0.5}){sub 0.9}Sm{sub 0.1}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} as an intermediate temperature solid oxide fuel cell cathode

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuyan; Lue, Zhe; Ai, Na; Chen, Kongfa [Center for the Condensed-Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Su, Wenhui [Center for the Condensed-Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Department of Condensed Matter Physics, Jilin University, Changchun 130023 (China); International Centre for Materials Physics, Academia Sinica, Shenyang 110015 (China)

    2007-02-25

    This study presents the electrochemical performance of (Ba{sub 0.5}Sr{sub 0.5}){sub 0.9}Sm{sub 0.1}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSSCF) as a cathode material for intermediate temperature solid oxide fuel cells (IT-SOFC). AC-impedance analyses were carried on an electrolyte supported BSSCF/Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} (SDC)/Ag half-cell and a Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF)/SDC/Ag half-cell. In contrast to the BSCF cathode half-cell, the total resistance of the BSSCF cathode half-cell was lower, e.g., at 550 C; the values for the BSSCF and BSCF were 1.54 and 2.33 {omega} cm{sup 2}, respectively. The cell performance measurements were conducted on a Ni-SDC anode supported single cell using a SDC thin film as electrolyte, and BSSCF layer as cathode. The maximum power densities were 681 mW cm{sup -2} at 600 C and 820 mW cm{sup -2} at 650 C. (author)

  12. Cobalt-free perovskite Pr{sub 0.5}Sr{sub 0.5}Fe{sub 1−x}Cu{sub x}O{sub 3−δ} (PSFC) as a cathode material for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Moura, Caroline G., E-mail: caroline.materiais@gmail.com [Materials Science and Engineering Postgraduate Program, UFRN, 59078-970, Natal (Brazil); Grilo, João Paulo de F. [Materials Science and Engineering Postgraduate Program, UFRN, 59078-970, Natal (Brazil); Macedo, Daniel A., E-mail: damaced@gmail.com [Materials Science and Engineering Postgraduate Program, UFPB, 58051-900, João Pessoa (Brazil); Cesário, Moisés R.; Fagg, Duncan Paul [Department of Mechanical Engineering, University of Aveiro, 3810-193, Aveiro (Portugal); Nascimento, Rubens M. [Materials Science and Engineering Postgraduate Program, UFRN, 59078-970, Natal (Brazil)

    2016-09-01

    PSFC (Pr{sub 0.5}Sr{sub 0.5}Fe{sub 1−x}Cu{sub x}O{sub 3−δ}) is a new perovskite-type oxide that has gained considerable attention as cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs), due to its high mixed ionic-electronic conductivity below 800 °C. In this work, PSFC (Pr{sub 0.5}Sr{sub 0.5}Fe{sub 1−x}Cu{sub x}O{sub 3−δ}, x = 0.2 and 0.4) powders were synthesized by the citrate method and structurally characterized by X-ray diffractometry. Screen-printed cathodes were sintered at 1050 °C and electrochemically characterized by impedance spectroscopy at 600–800 °C in pure oxygen. The area specific resistances (ASR) of the Pr{sub 0.5}Sr{sub 0.5}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−δ} material are shown to be competitive with typical values reported for cobalt-based cathodes in the measured temperature range, while, importantly, offering a significantly lower activation energy, 0.62 eV. The thermal expansion coefficients of these Co-free cathodes are in the range of 13–15 × 10{sup −6} °C{sup −1}, in a temperature range 200–650 °C, demonstrating a good thermal compatibility with gadolinia doped ceria (CGO) electrolytes. - Highlights: • Cobalt-free Pr{sub 0.5}Sr{sub 0.5}Fe{sub 1−x}Cu{sub x}O{sub 3−δ} (PSFC) cathodes successfully prepared by the citrate method. • PSFC cathodes are thermally compatible with CGO electrolytes. • Pr{sub 0.5}Sr{sub 0.5}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−δ} presents competitive area specific resistances of low activation energy, 0.62 eV.

  13. Temperature effects on surface activity and application in oxidation ...

    Indian Academy of Sciences (India)

    Correspondingly, the CMC of CTAB-SDS decreases almost by half. The increase of surface activity of CTAB-SDS can be attributed to the relatively weak electrostatic interaction at high temperature, which is supported by the increase of solubility of CTAB-SDS with rise in temperature. Catalytic effect on oxidation of toluene ...

  14. High Temperature Strength of Oxide Dispersion Strengthened Aluminium

    DEFF Research Database (Denmark)

    Clauer, A.H.; Hansen, Niels

    1984-01-01

    The tensile flow stress of coarse-grained dispersion strengthened Al-Al2O3 materials were measured as a function of temperature (77–873 K) and volume fraction (0.19-0.92 vol.%) of aluminium oxide. For the same material, the creep strength was determined as a function of temperature in the range 573...

  15. Pulsed laser deposited MnCo2O4 protective layer on SS430 for solid oxide fuel cell application

    Science.gov (United States)

    Gaur, Anshu; Mohiddon, Md. Ahamad; Prasad, Muvva D.

    2016-05-01

    The growth and oxidation study of pulsed laser deposited MnCo2O4 protective layer on SS430 substrate for solid oxide fuel cell application is demonstrated. MnCo2O4 has been achieved in three different ways including, deposition at higher substrate temperature (700°C), and deposition at room temperature on pre-oxidized and untreated SS430 substrate followed by annealing at 700°C for 2 hrs. X-ray diffraction and Raman spectroscopy has been applied to demonstrate the kind of phases developed in each case. These three samples were subjected to heat treatment at 750°C for 5 hr. The extent of undesired Fe2O3 phase formation in the post deposition heat treated samples is discussed based on Raman spectroscopic results.

  16. Fe-doped 8YSZ at different composition for solid electrolyte in solid oxide fuel cell

    Directory of Open Access Journals (Sweden)

    Johar B.

    2016-01-01

    Full Text Available Pure 8 mol% yttria stabilized zirconia (YSZ and Fe-doped (1 mol%, 2 mol% and 3 mol% YSZ electrolyte were prepared and sintered at 1550°C. Transition metal oxide is added into YSZ as sintering aided has a function to reduce the sintering temperature. The microstructure, crystal structure and ionic conductivity of pure YSZ and Fe-doped YSZ at different composition were investigated. The amount of cubic phase decreased as the amount of Fe increased. Fe-doped 8YSZ had higher conductivity than pure 8YSZ. The ionic conductivity of 3FeYSZ is 9.35×10−8 S/cm higher than 1FeYSZ which is 4.72×10−9 S/cm when operated at 300°C.

  17. Electrochemical degradation, kinetics & performance studies of solid oxide fuel cells

    Science.gov (United States)

    Das, Debanjan

    Linear and Non-linear electrochemical characterization techniques and equivalent circuit modelling were carried out on miniature and sub-commercial Solid Oxide Fuel Cell (SOFC) stacks as an in-situ diagnostic approach to evaluate and analyze their performance under the presence of simulated alternative fuel conditions. The main focus of the study was to track the change in cell behavior and response live, as the cell was generating power. Electrochemical Impedance Spectroscopy (EIS) was the most important linear AC technique used for the study. The distinct effects of inorganic components usually present in hydrocarbon fuel reformates on SOFC behavior have been determined, allowing identification of possible "fingerprint" impedance behavior corresponding to specific fuel conditions and reaction mechanisms. Critical electrochemical processes and degradation mechanisms which might affect cell performance were identified and quantified. Sulfur and siloxane cause the most prominent degradation and the associated electrochemical cell parameters such as Gerisher and Warburg elements are applied respectively for better understanding of the degradation processes. Electrochemical Frequency Modulation (EFM) was applied for kinetic studies in SOFCs for the very first time for estimating the exchange current density and transfer coefficients. EFM is a non-linear in-situ electrochemical technique conceptually different from EIS and is used extensively in corrosion work, but rarely used on fuel cells till now. EFM is based on exploring information obtained from non-linear higher harmonic contributions from potential perturbations of electrochemical systems, otherwise not obtained by EIS. The baseline fuel used was 3 % humidified hydrogen with a 5-cell SOFC sub-commercial planar stack to perform the analysis. Traditional methods such as EIS and Tafel analysis were carried out at similar operating conditions to verify and correlate with the EFM data and ensure the validity of the

  18. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    Science.gov (United States)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic −EO− based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm−1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions. PMID:26791572

  19. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries.

    Science.gov (United States)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-21

    Here we demonstrate that by regulating the mobility of classic -EO- based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm(-1) are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li(+)), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions.

  20. Study on new BaCe{sub 0.7}In{sub 0.3}O{sub 3−δ}–Gd{sub 0.1}Ce{sub 0.9}O{sub 2−δ} composite electrolytes for intermediate-temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fengguang; Dang, Junjie; Hou, Jie; Qian, Jing; Zhu, Zhiwen; Wang, Zhongtao [CAS Key Laboratory of Materials for Energy Conversion, Department of Material Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Liu, Wei, E-mail: wliu@ustc.edu.cn [CAS Key Laboratory of Materials for Energy Conversion, Department of Material Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2015-08-05

    Highlights: • New BCI–GDC composite electrolytes were synthesized using a one-step method for SOFCs. • The sintering temperature decreases as the BCI content increases. • The conductivity and OCV values enhanced as the GDC content increases. • The possible interface effects between BCI and GDC were analyzed. - Abstract: New mixed ionic conductors, BaCe{sub 0.7}In{sub 0.3}O{sub 3−δ}–Gd{sub 0.1}Ce{sub 0.9}O{sub 2−δ} (BCI–GDC, weight ratio, 3:7, 5:5 and 7:3), were synthesized via a one-step citric acid–nitrate gel combustion method as electrolyte materials for solid oxide fuel cells (SOFCs). X-ray diffraction patterns of BCI–GDC indicated that there was no impurity phase formed after sintering at high temperature up to 1400 °C. Scanning electron microscopic study of BCI–GDC depicted dense grain morphology. Single fuel cells were prepared and the corresponding electrochemical performances were tested. The sintering temperature of the dense composite electrolyte membranes decrease as the BCI content increases because of the sintering aids of In element. All samples with the composite electrolyte showed higher open circuit voltage (OCV) values than the single phase GDC. In addition, Electrical conductivity of the composite electrolyte under different atmospheres at different temperatures confirmed that the BCI–GDC exhibited high mixed oxygen ionic and protonic conduction. The test results indicated that the conductivity and OCV values of the composite electrolyte enhanced as the GDC content increases, and the optimum performance was found to be BCI3–GDC7 compared with the pure BCI and GDC electrolyte. The possible interface effects were suggested to explain this phenomenon. Our results not only provide one new promising composite electrolyte material for intermediate-temperature SOFCs but the composition dependence can actually provide a guide for the material design, optimization.

  1. Computational Chemistry of Cyclopentane Low Temperature Oxidation

    KAUST Repository

    El Rachidi, Mariam

    2015-03-30

    Cycloalkanes are significant constituents of conventional fossil fuels, but little is known concerning their combustion chemistry and kinetics, particularly at low temperatures. This study investigates the pressure dependent kinetics of several reactions occurring during low-temperature cyclopentane combustion using theoretical chemical kinetics. The reaction pathways of the cyclopentyl + O2 adduct is traced to alkylhydroperoxide, cyclic ether, β-scission and HO2 elimination products. The calculations are carried out at the UCCSD(T)-F12b/cc-pVTZ-F12//M06-2X/6-311++G(d,p) level of theory. The barrierless entrance channel is treated using variable-reaction-coordinate transition state theory (VRC-TST) at the CASPT2(7e,6o) level of theory, including basis set, geometry relaxation and ZPE corrections. 1-D time-dependent multiwell master equation analysis is used to determine pressure-and temperature-dependent rate parameters of all investigated reactions. Tunneling corrections are included using Eckart barriers. Comparison with cyclohexane is used to elucidate the effect of ring size on the low temperature reactivity of naphthenes. The rate coefficients reported herein are suitable for use in cyclopentane and methylcyclopentane combustion models, even below ~900 K, where ignition is particularly sensitive to these pressure-dependent values.

  2. Numerical analysis of start-up operation of a tubular solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Barzi, Y. Mollayi; Ghassemi, M.; Hamedi, M.H. [Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran)

    2009-02-15

    The purpose of the current study is to numerically predict the start up behavior of a tubular solid oxide fuel cell (SOFC) using a 2-D transient model. The developed model provides the transient response of the start-up mode as well as the steady state operation of the SOFC. A code based on finite volume method is utilized to solve the transient nonlinear transport equations of the cell (momentum, species and energy equations). To account for the Ohmic losses and Joule heating of the current that passes through the cell body, a discretized network circuit is adopted. The local electrochemical parameters are calculated based on the local pressure, temperature, and concentrations of the species. At each time step an iterative procedure is used to solve the electrochemical, electrical and transport equations simultaneously. The model predicts the cell output voltage, the local EMF and the state variables (pressure, temperature and species concentration) during the start up. It also predicts the cell heat-up rate for hot input gases as well as the start up time of the SOFC. The results show that the gases mass flow rate and temperature affect the heat-up rate. Also during the start-up, the cell electrical response is about 2.5 times quicker than the cell temperature response. The start-up time for the cell output voltage is about 50 min. (author)

  3. Size Dependence of a Temperature-Induced Solid-Solid Phase Transition in Copper(I) Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Rivest, Jessy B; Fong, Lam-Kiu; Jain, Prashant K; Toney, Michael F; Alivisatos, A Paul

    2011-07-24

    Determination of the phase diagrams for the nanocrystalline forms of materials is crucial for our understanding of nanostructures and the design of functional materials using nanoscale building blocks. The ability to study such transformations in nanomaterials with controlled shape offers further insight into transition mechanisms and the influence of particular facets. Here we present an investigation of the size-dependent, temperature-induced solid-solid phase transition in copper sulfide nanorods from low- to high-chalcocite. We find the transition temperature to be substantially reduced, with the high chalcocite phase appearing in the smallest nanocrystals at temperatures so low that they are typical of photovoltaic operation. Size dependence in phase trans- formations suggests the possibility of accessing morphologies that are not found in bulk solids at ambient conditions. These other- wise-inaccessible crystal phases could enable higher-performing materials in a range of applications, including sensing, switching, lighting, and photovoltaics.

  4. Fracture toughness of glass sealants for solid oxide fuel cell application

    DEFF Research Database (Denmark)

    Abdoli, Hamid; Alizadeh, Parvin; Boccaccini, Dino

    2014-01-01

    Glass and glass-ceramics are versatile materials and have been widely used for sealing in the ongoing development of intermediate temperature solid oxide fuel cell (SOFC) technology where its integrity is crucial for reliable operation of the stack. The fracture toughness is a key parameter...... required for the prediction of the mechanical performance of a seal glass. A comparative indentation study on two RE-glasses (RE=La and Y) was performed to evaluate their fracture toughness. Indentation toughness was calculated both through measurements of the indentation crack lengths and of crack......-opening displacements in the near regions of a crack tip. Both approaches exhibited good agreement. La-containing glass showed higher stiffness, hardness and fracture toughness, which has been related to the in-situ toughening mechanism caused by devitrification and formation of crystalline phases. © 2013 Elsevier B.V....

  5. Energy recuperation in solid oxide fuel cell (SOFC) and gas turbine (GT) combined system

    Science.gov (United States)

    Kuchonthara, Prapan; Bhattacharya, Sankar; Tsutsumi, Atsushi

    A combined power generation system consisting of a solid oxide fuel cell (SOFC) and a gas turbine (GT) with steam and heat recuperation (HR) was evaluated using a commercial process simulation tool, ASPEN Plus. The effect of steam recuperation (SR) on the overall efficiency of the combined system was investigated by comparing the SOFC-GT during heat and steam recuperation (HSR) against the system during only heat recuperation. At low turbine inlet temperatures (TITs), the overall efficiency of the SOFC-GT combined system with heat and steam recuperation improved by showing an increase in TIT and a reduction in pressure ratio (PR). On the other hand, at high TITs, the opposite trend was observed. The integration of steam recuperation was found to improve the overall efficiency and specific power of SOFC-GT combined systems with a relatively compact SOFC component.

  6. Carbon Deposition during CO2 Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes

    DEFF Research Database (Denmark)

    Skafte, Theis Løye; Graves, Christopher R.; Blennow, P.

    2015-01-01

    of carbon deposition. The outlet gas composition at each current step was estimated based on the inlet gas composition and the reactant conversion using Faraday's law. The increase in voltage was observed at lower pCO/pCO2 ratios than that corresponding to the thermodynamic threshold for carbon formation......Local gradients within an operating solid oxide electrolyzer cell were studied using current-potential measurements and electrochemical impedance spectroscopy. The cells and operating conditions were closely related to commercial applications. The cells with fuel electrodes of nickel and yttria...... conditions for commercial systems. The effect would be even more severe on stack level, where the gas diffusion and temperature gradients are more pronounced. Initial results of the mitigation strategy of infiltrating CGO are negative, but increased performance prior to coking was observed....

  7. A simulation study of Solid Oxide fuel cell for IGCC power generation using Aspen Plus

    DEFF Research Database (Denmark)

    Rudra, Souman; Kim, Hyung Taek

    2010-01-01

    operating conditions and using diverse fuels. The SOFC stack model developed using the chemical process flow sheet simulator Aspen Plus which is of equilibrium type and is based on Gibbs free energy minimization. The SOFC model performs heat and mass balances and considers the ohmic, activation......The solid oxide fuel cell (SOFC) is a promising technology for electricity generation. Sulfur free syngas from the gas cleaning unit serves as a fuel for SOFC in IGFC (Integrated gasification Fuel cell) power plant. It converts the chemical energy of the fuel gas directly to electric energy...... and therefore, very high efficiencies can be achieved. The high operating temperature of the SOFC also provides excellent possibilities for cogeneration application. The outputs from SOFC can be utilized by HRSG which helps to drive steam generator. Recent developments in modeling techniques has resulted...

  8. Nanostructured Gd-CeO2 electrolyte for solid oxide fuel cell by aqueous tape casting

    Science.gov (United States)

    Akbari-Fakhrabadi, A.; Mangalaraja, R. V.; Sanhueza, Felipe A.; Avila, Ricardo E.; Ananthakumar, S.; Chan, S. H.

    2012-11-01

    Gadolinia-doped ceria (Ce0.9Gd0.1O1.95, GDC) electrolyte was fabricated by aqueous-based tape casting method for solid oxide fuel cells (SOFCs). The ceramic powder prepared by combustion synthesis was used with poly acrylic acid (PAA), poly vinyl alcohol (PVA), poly ethylene glycol (PEG), Octanol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate and double distilled water as dispersant, binder, plasticizer, defoamer, surfactant and solvent respectively, to prepare stable GDC slurry. The conditions for preparing stable GDC slurries were studied and optimized by sedimentation, zeta potential and viscosity measurements. Green tapes with smooth surface, flexibility, thickness in the range of 0.35-0.4 mm and 45% relative green density were prepared. Conventional and flash sintering techniques were used and compared for densification which demonstrated the possibility of surpassing sintering at high temperatures and retarding related grain growth.

  9. Elaboration and characterisation of functionally graded cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Simonet, J.; Kapelski, G.; Bouvard, D. [Laboratoire de Genie Physique et Mecanique des Materiaux, Institut National Polytechnique de Grenoble, CNRS UMR 5010, BP 46, 38042 Saint Martin d' Heres cedex (France)

    2005-07-01

    The industrial development of solid oxide fuel cells (SOFC) requires decreasing their operating temperature from 1000 deg. C to 700 deg. C while keeping acceptable mechanical and electrochemical performances. A solution consists in designing composite bulk cathodes with numerous electro-chemical reaction sites. The fabrication of such cathodes has been investigated with classical materials as lanthanum strontium manganese (LSM) and yttrium stabilized zirconia (YSZ), which is also the constitutive material of the electrolyte. A composite cathode with continuous composition gradient has been obtained by co-sedimentation of the powders in a liquid and subsequent firing. The obtained composition is investigated with Scanning Electron Microscope (SEM) and Electron Dispersive Spectrometry (EDS). It is found to be in good agreement with the prediction of a numerical model of the sedimentation process. (authors)

  10. Biodiesel production from wet microalgae by using graphene oxide as solid acid catalyst.

    Science.gov (United States)

    Cheng, Jun; Qiu, Yi; Huang, Rui; Yang, Weijuan; Zhou, Junhu; Cen, Kefa

    2016-12-01

    In order to produce biodiesel from lipids in wet microalgae with graphene oxide (GO) as solid acid catalyst, the effects on lipids conversion efficiencies of catalyst dosage, transesterification temperature, reaction time, methanol dosage and chloroform dosage were investigated. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis revealed that GO contained 0.997mmol SO3H groups per gram and high amounts of OH groups. Scanning electron microscopy showed that wet microalgae cells were adsorbed on hydrophilic GO surfaces covered with many OH groups. Lipids extracted by chloroform from microalgal cells were transformed into fatty acids methyl esters (FAMEs) through transesterification catalyzed by the acid centers (SO3H groups) in GO catalysts. The lipids conversion efficiency into FAMEs was 95.1% in microwave-assisted transesterification reactions of 5wt.% GO catalyst at 90°C for 40min. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Design and development of major balance of plant components in solid oxide fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Wen-Tang; Huang, Cheng-Nan; Tan, Hsueh-I; Chao, Yu [Institute of Nuclear Energy Research Atomic Energy Council, Taoyuan County 32546 (Taiwan, Province of China); Yen, Tzu-Hsiang [Green Technology Research Institute, CPC Corporation, Chia-Yi City 60036 (Taiwan, Province of China)

    2013-07-01

    The balance of plant (BOP) of a Solid Oxide Fuel Cell (SOFC) system with a 2 kW stack and an electric efficiency of 40% is optimized using commercial GCTool software. The simulation results provide a detailed understanding of the optimal operating temperature, pressure and mass flow rate in all of the major BOP components, i.e., the gas distributor, the afterburner, the reformer and the heat exchanger. A series of experimental trials are performed to validate the simulation results. Overall, the results presented in this study not only indicate an appropriate set of operating conditions for the SOFC power system, but also suggest potential design improvements for several of the BOP components.

  12. Testing and improving the redox stability of Ni-based solid oxide fuel cells

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Ramos, Tania; Kaiser, Andreas

    2009-01-01

    Despite active development, solid oxide fuel cells (SOFCs) based on Ni-YSZ anodes still suffer from thermomechanical instability under conditions where the anode side is exposed to oxidising conditions at high temperature. In the first part of the paper, structures and solutions, which could...... improve the redox stability of Ni-YSZ anode supported SOFC's in terms of dimensional and mechanical stability are reported. Porosity is identified as a major microstructural parameter linked to the dimensional and structural stability during redox cycling. The cumulative redox strain (CRS) after three...... isothermal redox cycles at 850 °C increases by a factor of more than 20 when the as-sintered porosity of the composites is reduced from 34 to 9%. The effect of reduction and redox cycling on the Ni-YSZ anode are discussed in light of electrochemical measurements using impedance spectroscopy on symmetric...

  13. Microstructure characterisation of solid oxide electrolysis cells operated at high current density

    DEFF Research Database (Denmark)

    Bowen, Jacob R.; Bentzen, Janet Jonna; Chen, Ming

    High temperature solid oxide cells can be operated either as fuel cells or electrolysis cells for efficient power generation or production of hydrogen from steam or synthesis gas (H2 + CO) from steam and CO2 respectively. When operated under harsh conditions, they often exhibit microstructural......, microstructure evolution of the Ni-yttria stabilized zirconia (YSZ) is followed as a function of galvanostatic steam electrolysis testing at current densities between -0.5 and -1.0 A cm-2 for periods of up to 750 hours at 800 °C. The volume fraction and size of the percolating Ni particles was statistically...... quantified using the mean linear intercept method as a function of current density and correlated to increases in serial resistance. The above structural changes are then compared in terms of electrode degradation observed during the co-electrolysis of steam and CO2 at current densities up to -1.5 A cm-2...

  14. Optimization of spin-coated electrodes for electrolyte-supported solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Nobrega, Shayenne Diniz da; Monteiro, Natalia Kondo; Tabuti, Francisco; Fonseca, Fabio Coral, E-mail: shaynnedn@hotmail.com, E-mail: nataliakm@usp.br, E-mail: fntabuti@ipen.br, E-mail: fabiocf@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil); Florio, Daniel Zanetti de, E-mail: daniel.florio@ufabc.edu.br [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2017-01-15

    Electrodes for electrolyte-supported solid oxide fuel cells (SOFC’s) were fabricated by spin coating. Strontium-doped lanthanum manganite (LSM) cathode and nickel yttria-stabilized zirconia cermet anodes were synthesized and processed for enhanced deposition conditions. The influence of electrode microstructural parameters was investigated by a systematic experimental procedure aiming at optimized electrochemical performance of single cells. Polarization curves showed a strong dependence on both electrode thickness and sintering temperature. By a systematic control of such parameters, the performance of single cells was significantly enhanced due to decreasing of polarization resistance from 26 Ω cm² to 0.6 Ω cm² at 800°C. The results showed that spin-coated electrodes can be optimized for fast and cost effective fabrication of SOFCs. (author)

  15. Novel in situ method (vacuum assisted electroless plating) modified porous cathode for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Su, Ren; Lue, Zhe; Chen, Kongfa; Ai, Na; Li, Shuyan; Wei, Bo [Center for the Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Su, Wenhui [Center for the Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Department of Condensed Matter Physics, Jilin University, Changchun 130023 (China); International Centre for Materials Physics, Academia Sinica, Shenyang 110015 (China)

    2008-06-15

    A novel in situ method - vacuum assisted electroless plating (VA-EP) is developed to modify the porous structure of various materials. The advantage of this method is that it can form a metal network based on the already-given structure. We utilize this method to deposit silver (VA-EPA) in porous perovskite cathode Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) for an intermediate temperature solid oxide fuel cell (IT-SOFC) in the present research. The results of investigation show the performance of the modified cathode (VA-EPA-BSCF) enhances greatly, for example, the polarization resistance of VA-EPA-BSCF decreases by 60% at 600 C compared to BSCF. (author)

  16. Methane Steam Reforming over an Ni-YSZ Solid Oxide Fuel Cell Anode in Stack Configuration

    Directory of Open Access Journals (Sweden)

    D. Mogensen

    2014-01-01

    Full Text Available The kinetics of catalytic steam reforming of methane over an Ni-YSZ anode of a solid oxide fuel cell (SOFC have been investigated with the cell placed in a stack configuration. In order to decrease the degree of conversion, a single cell stack with reduced area was used. Measurements were performed in the temperature range 600–800°C and the partial pressures of all reactants and products were varied. The obtained rates could be well fitted with a power law expression (r ∝PCH40.7. A simple model is presented which is capable of predicting the methane conversion in a stack configuration from intrinsic kinetics of the anode support material. The predictions are compared with the stack measurements presented here, and good agreement is observed.

  17. Thermodynamic Analysis of an Integrated Gasification Solid Oxide Fuel Cell Plant with a Kalina Cycle

    DEFF Research Database (Denmark)

    Pierobon, Leonardo; Rokni, Masoud

    2015-01-01

    A hybrid plant that consists of a gasification system, Solid Oxide Fuel Cells (SOFC) and a Simple Kalina Cycle (SKC) is investigated. Woodchips are introduced into a fixed bed gasification plant to produce syngas, which is then fed into an integrated SOFC-SKC plant to produce electricity. The pre...... system based on a gasification plant, a SOFC plant and a SKC plant is presented and investigated. The system is called IGSKC (Integrated Gasification SOFC Simple Kalina Cycle). The system layout is studied, and the optimal ammonia-water mole fraction is selected. An electrical efficiency of 58......% is achieved; plant size and nominal power are selected based on the required cultivation area. SOFC heat recovery with SKC is compared to a Steam Cycle (SC). Although ammonia-water more accurately fits the temperature profile of the off-gases, the presence of a Hybrid Recuperator enhances the available work...

  18. Engine-integrated solid oxide fuel cells for efficient electrical power generation on aircraft

    Science.gov (United States)

    Waters, Daniel F.; Cadou, Christopher P.

    2015-06-01

    This work investigates the use of engine-integrated catalytic partial oxidation (CPOx) reactors and solid oxide fuel cells (SOFCs) to reduce fuel burn in vehicles with large electrical loads like sensor-laden unmanned air vehicles. Thermodynamic models of SOFCs, CPOx reactors, and three gas turbine (GT) engine types (turbojet, combined exhaust turbofan, separate exhaust turbofan) are developed and checked against relevant data and source material. Fuel efficiency is increased by 4% and 8% in the 50 kW and 90 kW separate exhaust turbofan systems respectively at only modest cost in specific power (8% and 13% reductions respectively). Similar results are achieved in other engine types. An additional benefit of hybridization is the ability to provide more electric power (factors of 3 or more in some cases) than generator-based systems before encountering turbine inlet temperature limits. A sensitivity analysis shows that the most important parameters affecting the system's performance are operating voltage, percent fuel oxidation, and SOFC assembly air flows. Taken together, this study shows that it is possible to create a GT-SOFC hybrid where the GT mitigates balance of plant losses and the SOFC raises overall system efficiency. The result is a synergistic system with better overall performance than stand-alone components.

  19. The Development of Nano-Composite Electrodes for Solid Oxide Electrolyzers

    Energy Technology Data Exchange (ETDEWEB)

    Gorte, Raymond J.; Vohs, John M.

    2014-03-26

    Solid oxide fuel cells (SOFC) and electrolyzers (SOE) offer an attractive means for converting between electrical and chemical energy. Because they operate at high temperatures and are usually based on electrolytes that are oxygen-ion conducting ceramics, such as yttria-stabilized zirconia (YSZ), they are equally capable of converting between CO and CO2 as between H2 and H2O. When operated in the SOFC mode, they are able to operate on hydrocarbon fuels so long as there are no materials within the anode that can catalyze carbon formation. Compared to other types of electrolyzers, SOE can exhibit the highest efficiencies because the theoretical Nernst potential is lower at high temperatures and because the electrode overpotentials in SOE tend to be much lower. Finally, pure H2 can be produced without an external electrical source by electrolysis of steam at one electrode and oxidation of any fuel at the other electrode through a process known as Natural-Gas Assisted Steam Electrolysis. This final report describes results from studies of novel electrodes for SOE and SOFC prepared by infiltration methods.

  20. A high performance cathode for proton conducting solid oxide fuel cells

    KAUST Repository

    Wang, Zhiquan

    2015-01-01

    Intermediate temperature solid-oxide fuel cells (IT-SOFCs)), as one of the energy conversion devices, have attracted worldwide interest for their great fuel efficiency, low air pollution, much reduced cost and excellent longtime stability. In the intermediate temperature range (500-700°C), SOFCs based on proton conducting electrolytes (PSOFCs) display unique advantages over those based on oxygen ion conducting electrolytes. A key obstacle to the practical operation of past P-SOFCs is the poor stability of the traditionally used composite cathode materials in the steam-containing atmosphere and their low contribution to proton conduction. Here we report the identification of a new Ruddlesden-Popper-type oxide Sr3Fe2O7-δ that meets the requirements for much improved long-term stability and shows a superior single-cell performance. With a Sr3Fe2O7-δ-5 wt% BaZr0.3Ce0.5Y0.2O3-δ cathode, the P-SOFC exhibits high power densities (683 and 583 mW cm-2 at 700°C and 650°C, respectively) when operated with humidified hydrogen as the fuel and air as the cathode gas. More importantly, no decay in discharging was observed within a 100 hour test. © The Royal Society of Chemistry 2015.

  1. Miniature Solid-State Sulfur Oxide Sensor for Emissions Measurement Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering Incorporated (MEI) and Case Western Reserve University (CWRU) propose to develop a MEMS based, minature solid state sulfur oxide sensor for use in...

  2. A Compact, Efficient Pyrolysis/Oxidation System for Solid Waste Resource Recovery in Space Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Both pyrolysis and oxidation steps have been considered as the key solid waste processing step for a Controlled Ecological Life Support System (CELSS). Pyrolysis is...

  3. Redox-Reversible Iron Orthovanadate Cathode for Solid Oxide Steam Electrolyzer.

    Science.gov (United States)

    Gan, Lizhen; Ye, Lingting; Ruan, Cong; Chen, Shigang; Xie, Kui

    2016-02-01

    A redox-reversible iron orthovanadate cathode is demonstrated for a solid oxide electrolyser with up to 100% current efficiency for steam electrolysis. The iron catalyst is grown on spinel-type electronic conductor FeV2O4 by in situ tailoring the reversible phase change of FeVO4 to Fe+FeV2O4 in a reducing atmosphere. Promising electrode performances have been obtained for a solid oxide steam electrolyser based on this composite cathode.

  4. SOCTESQA - Solid Oxide Cell and Stack Testing, Safety and Quality Assurance

    OpenAIRE

    Auer, Corinna; Lang, Michael; Couturier, Karine; Nielsen, Eva Ravn; Mc Phail, Stephen; Tsotridis, Georgios; FU, Qingxi

    2014-01-01

    Many research facilities and industrial companies worldwide are engaged in the development and the improvement of solid oxide fuel cells/stacks (SOFC) and also of solid oxide electrolysis cells/stacks (SOEC). However, the successful application of fuel and electrolysis cells/stacks in real world conditions requires reliable assessment, testing and prediction of performance and durability. Therefore the EU-project SOCTESQA will start at the beginning of May with the aim to develop uniform and ...

  5. Experimental study on solid state reduction of chromite with rising temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kekkonen, M.; Syynimaa, A.; Holappa, L.

    1998-07-01

    The solid state reduction of preoxidized sintered chromite pellets, raw pellets, process pellets and lumpy ores have been studied with rising temperature 700-1520 deg C under CO-atmosphere in order to better simulate the conditions in the upper part of a real submerged arc furnace. According to the reduction degree curves the reduction behaviour of chromite pellets seems to be similar. The reduction rate was slow at the beginning but increased rapidly when the temperature reached about 1000 deg C. The final reduction degree was highest in the case of process pellets and lowest in the case of raw pellet. In the case of preoxidized pellets there was not much difference of the reduction rate and final reduction degree between different oxidation states. In the case of lumpy ores the reduction rate and the final reduction degree was much lower compared to the pellets. Optical photographs, phase and microanalysis show that the reduction has proceeded further in the surface of the samples and confirmed also that the reduction degree remained lower in the case of raw pellet and lumpy ores which was also seen from the reduction degree curves. According to the experiments in the case of preoxidized pellets the effect of oxidation state on the reduction rate was not observed due to small difference in the oxidation state of the samples. But when comparing the reduction of preoxidized pellets and unoxidised raw pellet we can say that preoxidation promotes the reduction. The final reduction degree of the raw pellet remained lower than in the case of preoxidized pellets. (orig.)

  6. Influence of oxidation temperature on the oxide scale formation of NiCoCrAl coatings

    Science.gov (United States)

    Sugiarti, E.; Zaini, K. A.; Sundawa, R.; Wang, Y.; Ohnuki, S.; Hayashi, S.

    2017-04-01

    Intermetalic coatings of NiCoCrAl have been successfully developed on low carbon steel substrate to improve oxidation resistance in extreme environments. The influence of oxidation temperature on the oxide scale formation was studied in the temperature range of 600-1000 °C. The measurements were made in air under isothermal oxidation test for 100 h. The surface morphology showed that a cauliflower like structure developed entire the oxide scale of sample oxidized at 800 °C and 1000 °C, while partly distributed on the surface of sample oxidized at 600 °C. The XRD analysis identified Cr2O3 phase predominantly formed on the oxidized sample at 600 °C and meta-stable Al2O3 with several polymorphs crystalline structures: η, δ, θ, κ, and α-Al2O3 at relatively high temperatures, i.e. 800 °C and 1000 °C. A Cross-sectional microstructure showed that complex and porous structures formed on the top surface of 600 °C and 1000 °C samples. In contrast, a very thin oxide scale formed on 800 °C oxidized samples and it appeared to act as a diffusion barrier of oxygen to diffuse inward, hence could increase in the service life of carbon steel substrate.

  7. Molybdenum Disilicide Oxidation Kinetics in High Temperature Steam

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Elizabeth Sooby [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Stephen Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Andrew Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-07

    The Fuel Cycle Research and Development program’s Advanced Fuels Campaign is currently supporting a range of experimental efforts aimed at the development and qualification of ‘accident tolerant’ nuclear fuel forms. One route to enhance the accident tolerance of nuclear fuel is to replace the zirconium alloy cladding, which is prone to rapid oxidation in steam at elevated temperatures, with a more oxidation-resistant cladding. Several cladding replacement solutions have been envisaged. The cladding can be completely replaced with a more oxidation resistant alloy, a layered approach can be used to optimize the strength, creep resistance, and oxidation tolerance of various materials, or the existing zirconium alloy cladding can be coated with a more oxidation-resistant material. Molybdenum is one candidate cladding material favored due to its high temperature creep resistance. However, it performs poorly under autoclave testing and suffers degradation under high temperature steam oxidation exposure. Development of composite cladding architectures consisting of a molybdenum core shielded by a molybdenum disilicide (MoSi2) coating is hypothesized to improve the performance of a Mo-based cladding system. MoSi2 was identified based on its high temperature oxidation resistance in O2 atmospheres (e.g. air and “wet air”). However, its behavior in H2O is less known. This report presents thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and x-ray diffraction (XRD) results for MoSi2 exposed to 670-1498 K water vapor. Synthetic air (80-20%, Ar-O2) exposures were also performed, and those results are presented here for a comparative analysis. It was determined that MoSi2 displays drastically different oxidation behavior in water vapor than in dry air. In the 670-1498 K temperature range, four distinct behaviors are observed. Parabolic oxidation is exhibited in only 670

  8. Biomass-powered Solid Oxide Fuel Cells : Experimental and Modeling Studies for System Integrations

    NARCIS (Netherlands)

    Liu, M.

    2013-01-01

    Biomass is a sustainable energy source which, through thermo-chemical processes of biomass gasification, is able to be converted from a solid biomass fuel into a gas mixture, known as syngas or biosyngas. A solid oxide fuel cell (SOFC) is a power generation device that directly converts the chemical

  9. Hierarchical Load Tracking Control of a Grid-connected Solid Oxide Fuel Cell for Maximum Electrical Efficiency Operation

    DEFF Research Database (Denmark)

    Li, Yonghui; Wu, Qiuwei; Zhu, Haiyu

    2015-01-01

    Based on the benchmark solid oxide fuel cell (SOFC) dynamic model for power system studies and the analysis of the SOFC operating conditions, the nonlinear programming (NLP) optimization method was used to determine the maximum electrical efficiency of the grid-connected SOFC subject to the const......Based on the benchmark solid oxide fuel cell (SOFC) dynamic model for power system studies and the analysis of the SOFC operating conditions, the nonlinear programming (NLP) optimization method was used to determine the maximum electrical efficiency of the grid-connected SOFC subject...... to the constraints of fuel utilization factor, stack temperature and output active power. The optimal operating conditions of the grid-connected SOFC were obtained by solving the NLP problem considering the power consumed by the air compressor. With the optimal operating conditions of the SOFC for the maximum...

  10. Nanocarbon synthesis by high-temperature oxidation of nanoparticles

    Science.gov (United States)

    Nomura, Ken-Ichi; Kalia, Rajiv K.; Li, Ying; Nakano, Aiichiro; Rajak, Pankaj; Sheng, Chunyang; Shimamura, Kohei; Shimojo, Fuyuki; Vashishta, Priya

    2016-04-01

    High-temperature oxidation of silicon-carbide nanoparticles (nSiC) underlies a wide range of technologies from high-power electronic switches for efficient electrical grid and thermal protection of space vehicles to self-healing ceramic nanocomposites. Here, multimillion-atom reactive molecular dynamics simulations validated by ab initio quantum molecular dynamics simulations predict unexpected condensation of large graphene flakes during high-temperature oxidation of nSiC. Initial oxidation produces a molten silica shell that acts as an autocatalytic ‘nanoreactor’ by actively transporting oxygen reactants while protecting the nanocarbon product from harsh oxidizing environment. Percolation transition produces porous nanocarbon with fractal geometry, which consists of mostly sp2 carbons with pentagonal and heptagonal defects. This work suggests a simple synthetic pathway to high surface-area, low-density nanocarbon with numerous energy, biomedical and mechanical-metamaterial applications, including the reinforcement of self-healing composites.

  11. Low Temperature Solid-State Synthesis and Characterization of LaBO3

    Directory of Open Access Journals (Sweden)

    Azmi Seyhun KIPÇAK

    2016-11-01

    Full Text Available Rare earth (lanthanide series borates, possess high vacuum ultraviolet (VUV transparency, large electronic band gaps, chemical and environmental stability and exceptionally large optical damage thresholds and used in the development of plasma display panels (PDPs. In this study the synthesis of lanthanum borates via solid-state method is studied. For this purpose, lanthanum oxide (La2O3 and boric acid (H3BO3 are used for as lanthanum and boron sources, respectively. Different elemental molar ratios of La to B (between 3:1 to 1:6 as La2O3:H3BO3 were reacted by solid-state method at the reaction temperatures between 500°C - 700°C with the constant reaction time of 4 h. Following the synthesis, characterizations of the synthesized products are conducted by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, Raman spectroscopy and scanning electron microscope (SEM. From the results of the experiments, three types of lanthanum borates of; La3BO6, LaBO3 and La(BO23 were observed at different reaction parameters. Among these three types of lanthanum borates LaBO3 phase were obtained as a major phase.

  12. Low temperature oxidation of hydrocarbons using an electrochemical reactor

    DEFF Research Database (Denmark)

    Ippolito, Davide

    at different reaction temperatures. The study of the effect of the infiltration of different electroactive materials on the electrode behavior has been carried on by the use of electrochemical impedance spectroscopy (EIS). Both the methods have been employed to understand the relationship between the catalytic...... the catalytic activity at open circuit voltage and the effect of polarization on propene oxidation rate at low temperature. The future development of this technology will see the infiltration of an active catalyst towards propene oxidation together with a NOx storage compound for the simultaneous oxidation...... high propene conversion at open circuit voltage together high rate enhancement ratio and faradaic efficiency values at low temperatures (300-350 °C). Although some stability problems affected the performance of multiple infiltrated Ce0.9Gd0.1O1.95 on LSM/CGO backbone, the strong activation of LSM upon...

  13. High temperature oxidation in boiler environment of chromized steel

    Science.gov (United States)

    Alia, F. F.; Kurniawan, T.; Asmara, Y. P.; Ani, M. H. B.; Nandiyanto, A. B. D.

    2017-10-01

    The demand for increasing efficiency has led to the development and construction of higher operating temperature power plant. This condition may lead to more severe thickness losses in boiler tubes due to excessive corrosion process. Hence, the research to improve the corrosion resistance of the current operated material is needed so that it can be applied for higher temperature application. In this research, the effect of chromizing process on the oxidation behaviour of T91 steel was investigated under steam condition. In order to deposit chromium, mixture of chromium (Cr) powder as master alloy, halide salt (NH4Cl) powder as activator and alumina (Al2O3) powder as inert filler were inserted into alumina retort together with the steel sample and heated inside furnace at 1050°C for ten hours under argon gas environment. Furthermore, for the oxidation process, steels were exposed at 700°C at different oxidation time (6h-24h) under steam condition. From FESEM/EDX analysis, it was found that oxidation rate of pack cemented steel was lower than the un-packed steel. These results show that Cr from chromizing process was able to become reservoir for the formation of Cr2O3 in high temperature steam oxidation, and its existence can be used for a longer oxidation time.

  14. Platinum redispersion on metal oxides in low temperature fuel cells

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Cerri, Isotta; Nagami, Tetsuo

    2013-01-01

    We have analyzed the aptitude of several metal oxide supports (TiO2, SnO2, NbO2, ZrO2, SiO2, Ta2O5 and Nb2O5) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied...... in detail; however, due to different operating conditions it is not straightforward to link the chemical and the electrochemical environment. The largest differences reflect in (1) the oxidation state of the surface (the oxygen species coverage), (2) temperature and (3) the possibility of platinum...... dissolution at high potentials and the interference of redispersion with normal working potential of the PEMFC cathode. We have calculated the PtOx (x = 0, 1, 2) adsorption energies on different metal oxides' surface terminations as well as inside the metal oxides' bulk, and we have concluded that NbO2 might...

  15. Thin Films of Reduced Hafnium Oxide with Excess Carbon for High-Temperature Oxidation Protection

    Science.gov (United States)

    2010-02-01

    contamination; thus the higher oxygen content found by XPS is partly due to organic impurities (and, possibly, water ) that are mostly concentrated in the...International Service Award, 2007. 25 REFERENCES ’C. B. Bargeron, R. C. Benson, and A. N. Jette , "High-Temperature Diffusion of Oxygen in Oxidizing Hafnium...A. N. Jette , and T. E. Phillips, "Oxidation of Hafnium Carbide in the Temperature Range 1400 ° to 2060 °C," Journal of the American Ceramic Society

  16. Cathodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Samson, Alfred Junio

    that these nanoparticulate infiltrates have good oxygen reduction capabilities. The significance of the choice of ionic conducting backbone was also addressed by replacing the CGO with Bi2V0.9Cu0.1O5.35 (BICUVOX). Cathodes with a BICUVOX backbone exhibit performance degradation not observed in LSC infiltrated - CGO cathodes...

  17. Control of Solid Waste Using Low Temperature Oxidation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In February 2004 NASA released "The Vision for Space Exploration". The important goals include extending human presence in the solar system culminating in the...

  18. Development of low temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Bakker, W.T.; Goldstein, R. [Electric Power Research Institute, Palo Alto, CA (United States)

    1996-12-31

    The historical focus of the electric utility industry has been central station power plants. These plants are usually sited outside urban areas and electricity was delivered via high voltage transmission lines. Several things are beginning to change this historical precedent One is the popular concern with EMF as a health hazard. This has rendered the construction of new lines as well as upgrading old ones very difficult. Installation of power generating equipment near the customer enables the utility to better utilize existing transmission and distribution networks and defer investments. Power quality and lark of disturbances and interruptions is also becoming increasingly more important to many customers. Grid connected, but dedicated small power plants can greatly improve power quality. Finally the development of high efficiency, low emission, modular fuel cells promises near pollution free localized power generation with an efficiency equal to or exceeding that of even the most efficient central power stations.

  19. High Temperature Solid Oxide Fuel Cell Generator Development

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Pierre

    2007-09-30

    This report describes the results of the tubular SOFC development program from August 22, 1997 to September 30, 2007 under the Siemens/U.S. Department of Energy Cooperative Agreement. The technical areas discussed include cell manufacturing development, cell power enhancement, SOFC module and system cost reduction and technology advancement, and our field unit test program. Whereas significant progress has been made toward commercialization, significant effort remains to achieve our cost, performance and reliability targets for successful commercialization.

  20. Effect of the graphene oxide reduction temperature on supercapacitor performance

    Science.gov (United States)

    Choi, Eunmi; Kim, Jaekwang; Cui, Yinhua; Choi, Kyuho; Gao, Yuan; Han, Seunghee; Pyo, Sung Gyu; Yoon, Songhun

    2017-07-01

    In this study, we investigated the influence of the reduction temperature on graphene oxide. After performing the thermal reduction at specific temperatures (200, 600, and 1000 °C), the morphological and crystallographic changes were investigated by several analysis methods. The reduced graphene oxides were used as supercapacitor electrodes and analyzed with various electrochemical techniques. The capacitance exhibited an increase up to 600 °C before decreasing abruptly at 1000 °C. This behavior was ascribed to the limited ionic accessibility into the compact graphene layer.[Figure not available: see fulltext.

  1. Optimal fault-tolerant control strategy of a solid oxide fuel cell system

    Science.gov (United States)

    Wu, Xiaojuan; Gao, Danhui

    2017-10-01

    For solid oxide fuel cell (SOFC) development, load tracking, heat management, air excess ratio constraint, high efficiency, low cost and fault diagnosis are six key issues. However, no literature studies the control techniques combining optimization and fault diagnosis for the SOFC system. An optimal fault-tolerant control strategy is presented in this paper, which involves four parts: a fault diagnosis module, a switching module, two backup optimizers and a controller loop. The fault diagnosis part is presented to identify the SOFC current fault type, and the switching module is used to select the appropriate backup optimizer based on the diagnosis result. NSGA-II and TOPSIS are employed to design the two backup optimizers under normal and air compressor fault states. PID algorithm is proposed to design the control loop, which includes a power tracking controller, an anode inlet temperature controller, a cathode inlet temperature controller and an air excess ratio controller. The simulation results show the proposed optimal fault-tolerant control method can track the power, temperature and air excess ratio at the desired values, simultaneously achieving the maximum efficiency and the minimum unit cost in the case of SOFC normal and even in the air compressor fault.

  2. Reactive co-sputter deposition of nanostructured cermet anodes for solid oxide fuel cells

    Science.gov (United States)

    Ionov, Igor V.; Solovyev, Andrey A.; Shipilova, Anna V.; Lebedynskiy, Alexey M.; Smolyanskiy, Egor A.; Lauk, Alexander L.; Semenov, Vyacheslav A.

    2018-01-01

    The impact of a nanostructured NiO/yttria-stabilized zirconia (NiO/YSZ) and NiO/gadolinia-doped ceria (NiO/GDC) anode functional layers on low- and intermediate-temperature solid oxide fuel cell (SOFC) performance is investigated. NiO/YSZ and NiO/GDC thin films were reactively sputter-deposited by pulsed direct current magnetron sputtering from the Ni, Zr–Y, and Ce–Gd targets onto commercial NiO/YSZ substrates. Anode-supported SOFCs based on magnetron sputtered YSZ and GDC electrolytes (∼4 µm) with and without the nanostructured anode layers are fabricated. A direct comparison of the YSZ- and GDC-based SOFCs in temperature range of 600–800 and 400–600 °C is made. The performance of cells with the nanostructured anode layers significantly increases as compared to that of the cell without it, especially at lower temperatures. Increase of cells performance was achieved by reduction of the total area-specific resistance by 26–30%.

  3. Thermomechanical analysis of porous solid oxide fuel cell by using peridynamics

    Directory of Open Access Journals (Sweden)

    Hanlin Wang

    2017-06-01

    Full Text Available Solid oxide fuel cell (SOFC is widely used in hybrid marine propulsion systems due to its high power output, excellent emission control and wide fuel suitability. However, the operating temperature in SOFC will rise up to 800–1000 ℃ due to redox reaction among hydrogen and oxygen ions. This provides a suitable environment for ions transporting through ceramic materials. Under such operation temperatures, degradation may occur in the electrodes and electrolyte. As a result, unstable voltage, low capacity and cell failure may eventually occur. This study presents thermomechanical analysis of a porous SOFC cell plate which contains electrodes, electrolytes and pores. A microscale specimen in the shape of a plate is considered in order to maintain uniform temperature loading and increase the accuracy of estimation. A new computational technique, peridynamics, is utilized to calculate the deformations and stresses of the cell plate. Moreover, the crack formation and propagation are also obtained by using peridynamics. According to the numerical results, damage evolution depends on the electrolyte/electrode interface strength during the charging process. For weak interface strength case, damage emerges at the electrode/electrolyte interface. On the other hand, for stronger interface cases, damage emerges on pore boundaries especially with sharp corner.

  4. Co-Electrolysis of Steam and Carbon Dioxide in Solid Oxide Cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune Dalgaard; Knibbe, Ruth; Mogensen, Mogens Bjerg

    2012-01-01

    Reduction of H2O and CO2 as well as oxidation of H2 and CO was studied in a Ni/YSZ electrode supported Solid Oxide Cell (SOC) produced at DTU Energy conversion (former Risø DTU). Even though these Ni/YSZ based SOCs were developed and optimized for fuel cell use, they can work as reversible SOCs i...

  5. Role of bond strength on the lattice thermal expansion and oxide ion conductivity in quaternary pyrochlore solid solutions.

    Science.gov (United States)

    Radhakrishnan, A N; Prabhakar Rao, P; Mahesh, S K; Thampi, D S Vaisakhan; Koshy, Peter

    2012-02-20

    Quaternary pyrochlore-type solid solutions, CaGdZrNb(1-x)Ta(x)O(7) (x = 0, 0.2, 0.4, 0.6, 0.8, 1), were prepared by a high-temperature ceramic route. The pyrochlore phases of the compounds were confirmed by powder X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. The crystallographic parameters of the pyrochlore compounds were accurately determined by Rietveld analysis of the powder XRD data. The isovalent substitution of Ta in place of Nb at the B site can reveal the effect of chemical bonding on lattice thermal expansion and oxide ion conductivity because both Nb and Ta have the same ionic radius (0.64 Å). Lattice thermal expansion coefficients of the samples were calculated from high-temperature XRD measurements, and it was found that the thermal expansion coefficient decreases with substitution of Ta. Oxide ion conductivity measured by a two-probe method also shows the same trend with substitution of Ta, and this can be attributed to the high bond strength of the Ta-O bond compared to that of the Nb-O bond. Microstructural characterization using scanning electron microscopy proves that the size of the grains has a small effect on the oxide ion conductivity. Our studies established the role of chemical bonding in deciding the conductivity of pyrochlore oxides and confirmed that the 48f-48f mechanism of oxide ion conduction is dominant in pyrochlore oxides.

  6. Ambient temperature NO oxidation over Cr-based amorphous mixed oxide catalysts: effects from the second oxide components

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Aiyong; Lin, Bo; Zhang, Hanlei; Engelhard, Mark H.; Guo, Yanglong; Lu, Guanzhong; Peden, Charles HF; Gao, Feng

    2017-01-01

    Three series of Cr-based mixed oxides (Cr-Co, Cr-Fe, and Cr-Ni oxides) with high specific surface areas and amorphous textures were synthesized using a novel sol-gel method. These mixed oxides, in comparison to their pure metal oxide (CrOx, Co3O4, FeOx and NiO) counterparts, display enhanced performance for catalytic oxidation of low-concentration NO at room temperature. The best performing catalysts achieve 100% NO conversion for ~30 h of operation at a high space velocity of 45,000 ml g-1 h-1. The amorphous structure was found to be critical for these catalysts to maintain high activity and durability. Control of Cr/M (M=Co, Fe and Ni) molar ratio, nitrate precursor decomposition temperature and catalyst calcination temperature was key to the synthesis of these highly active catalysts.

  7. A method of producing a multilayer barrier structure for a solid oxide fuel cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention provides a method of producing a multilayer barrier structure for a solid oxide cell stack, comprising the steps of: - providing a metal interconnect, wherein the metal interconnect is a ferritic stainless steel layer; - applying a first metal oxide layer on said metal...... oxide; and - reacting the metal oxide in said first metal oxide layer with the metal of said metal interconnect during the SOC-stack initialisation, and a solid oxide stack comprising an anode contact layer and support structure, an anode layer, an electrolyte layer, a cathode layer, a cathode contact...... layer, a metallic interconnect, and a multilayer barrier structure which is obtainable by the above method and through an initialisation step, which is carried out under controlled conditions for atmosphere composition and current load, which depends on the layer composition facilitating the formation...

  8. Gas-Solid Reaction Route toward the Production of Intermetallics from Their Corresponding Oxide Mixtures

    Directory of Open Access Journals (Sweden)

    Hesham Ahmed

    2016-08-01

    Full Text Available Near-net shape forming of metallic components from metallic powders produced in situ from reduction of corresponding pure metal oxides has not been explored to a large extent. Such a process can be probably termed in short as the “Reduction-Sintering” process. This methodology can be especially effective in producing components containing refractory metals. Additionally, in situ production of metallic powder from complex oxides containing more than one metallic element may result in in situ alloying during reduction, possibly at lower temperatures. With this motivation, in situ reduction of complex oxides mixtures containing more than one metallic element has been investigated intensively over a period of years in the department of materials science, KTH, Sweden. This review highlights the most important features of that investigation. The investigation includes not only synthesis of intermetallics and refractory metals using the gas solid reaction route but also study the reaction kinetics and mechanism. Environmentally friendly gases like H2, CH4 and N2 were used for simultaneous reduction, carburization and nitridation, respectively. Different techniques have been utilized. A thermogravimetric analyzer was used to accurately control the process conditions and obtain reaction kinetics. The fluidized bed technique has been utilized to study the possibility of bulk production of intermetallics compared to milligrams in TGA. Carburization and nitridation of nascent formed intermetallics were successfully carried out. A novel method based on material thermal property was explored to track the reaction progress and estimate the reaction kinetics. This method implies the dynamic measure of thermal diffusivity using laser flash method. These efforts end up with a successful preparation of nanograined intermetallics like Fe-Mo and Ni-W. In addition, it ends up with simultaneous reduction and synthesis of Ni-WN and Ni-WC from their oxide mixtures

  9. Interactions of nickel/zirconia solid oxide fuel cell anodes with coal gas containing arsenic

    Energy Technology Data Exchange (ETDEWEB)

    Coyle, C.A.; Marina, O.A.; Thomsen, E.C.; Edwards, D.J.; Cramer, C.D.; Coffey, G.W.; Pederson, L.R. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2009-09-05

    The performance of anode-supported and electrolyte-supported solid oxide fuel cells was investigated in synthetic coal gas containing 0-10 ppm arsenic at 700-800 C. Arsenic was found to interact strongly with nickel, resulting in the formation of nickel-arsenic solid solution, Ni{sub 5}As{sub 2} and Ni{sub 11}As{sub 8}, depending on temperature, arsenic concentration, and reaction time. For anode-supported cells, loss of electrical connectivity in the anode support was the principal mode of degradation, as nickel was converted to nickel arsenide phases that migrated to the surface to form large grains. Cell failure occurred well before the entire anode was converted to nickel arsenide, and followed a reciprocal square root of arsenic partial pressure dependence that is consistent with a diffusion-based rate-limiting step. Failure occurred more quickly with electrolyte-supported cells, which have a substantially smaller nickel inventory. For these cells, time to failure varied linearly with the reciprocal arsenic concentration. Failure occurred when arsenic reached the anode/electrolyte interface, though agglomeration of nickel reaction products may have also contributed. Test performed with nickel/zirconia coupons showed that arsenic was essentially completely captured in a narrow band near the fuel gas inlet. Arsenic concentrations of {proportional_to}10 ppb or less are estimated to result in acceptable rates of fuel cell degradation. (author)

  10. Interactions of nickel/zirconia solid oxide fuel cell anodes with coal gas containing arsenic

    Energy Technology Data Exchange (ETDEWEB)

    Coyle, Christopher A.; Marina, Olga A.; Thomsen, Edwin C.; Edwards, Danny J.; Cramer, Carolyn N.; Coffey, Greg W.; Pederson, Larry R.

    2009-04-01

    The performance of anode-supported and electrolyte-supported solid oxide fuel cells was investigated in synthetic coal gas containing 0 to 10 ppm arsenic introduced as arsine. Arsenic was found to interact strongly with nickel in the anode, resulting in the formation of nickel-arsenic solid solution, Ni5As2 and Ni11As8, depending on temperature, arsenic concentration, and reaction time. For anode-supported cells, loss of electrical connectivity in the anode support was the principal mode of degradation, as nickel was converted to nickel arsenide phases that migrated to the surface to form large grains. Cell failure occurred well before the entire anode was converted to nickel arsenide, and followed a reciprocal square root of arsenic partial pressure dependence consistent with a diffusion-based rate-limiting step. Failure occurred more quickly with electrolyte-supported cells, which have a substantially smaller nickel inventory. For these cells, time to failure varied linearly with the reciprocal arsenic concentration in coal gas, and occurred when arsenic reached the anode/electrolyte interface. Test performed with nickel/zirconia coupons showed that arsenic was essentially completely captured in a narrow band near the fuel gas inlet.

  11. Phase 1 - Evaluation of a Functional Interconnect System for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    James M. Rakowski

    2006-09-30

    This project is focused on evaluating the suitability of materials and complex multi-materials systems for use as solid oxide fuel cell interconnects. ATI Allegheny Ludlum has generated promising results for interconnect materials which incorporate modified surfaces. Methods for producing these surfaces include cladding, which permits the use of novel materials, and modifications via unique thermomechanical processing, which allows for the modification of materials chemistry. The University of Pittsburgh is assisting in this effort by providing use of their in-place facilities for dual atmosphere testing and ASR measurements, along with substantial work to characterize post-exposure specimens. Carnegie Mellon is testing interconnects for chromia scale spallation resistance using macro-scale and nano-scale indentation tests. Chromia spallation can increase electrical resistance to unacceptable levels and interconnect systems must be developed that will not experience spallation within 40,000 hours at operating temperatures. Spallation is one of three interconnect failure mechanisms, the others being excessive growth of the chromia scale (increasing electrical resistance) and scale evaporation (which can poison the cathode). The goal of indentation fracture testing at Carnegie Mellon is to accelerate the evaluation of new interconnect systems (by inducing spalls at after short exposure times) and to use fracture mechanics to understand mechanisms leading to premature interconnect failure by spallation. Tests include bare alloys from ATI and coated systems from DOE Laboratories and industrial partners, using ATI alloy substrates. West Virginia University is working towards developing a cost-effective material for use as a contact material in the cathode chamber of the SOFC. Currently materials such as platinum are well suited for this purpose, but are cost-prohibitive. For the solid-oxide fuel cell to become a commercial reality it is imperative that lower cost

  12. Determination of moisture and low temperature volatiles in solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Jenke, D.R.; Hannifan, M.R.

    1983-09-01

    The reaction of calcium carbide with moisture in a closed reactor to form acetylene, when combined with gas chromatographic analysis of the products and measurement of pressure change during reaction, provides an accurate and rapid determination method for moisture and volatile content of solid fuels.

  13. New Oxide Materials for an Ultra High Temperature Environment

    Energy Technology Data Exchange (ETDEWEB)

    Perepezko, John H. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering

    2017-11-13

    In this project, a new oxide material, Hf6Ta2O17 has been successfully synthesized by the controlled oxidization of Hf-Ta alloys. This oxide exhibits good oxidation resistance, high temperature phase stability up to more than 2000°C, low thermal conductivity and thus could serve as a component or a coating material in an ultrahigh temperature environment. We have examined the microstructure evolution and phase formation sequence during the oxidation exposure of Hf-Ta alloys at 1500°C and identified that the oxidation of a Hf-26.7atomic %Ta alloy leads to the formation of a single phase adherent Hf6Ta2O17 with a complex atomic structure i.e. superstructure. The overall reactive diffusion pathway is consistent with the calculated Hf-Ta-O ternary phase diagram. Besides the synthesis of Hf6Ta2O17 superstructure by oxidizing Hf-Ta alloys, we have also developed a synthesis method based upon the reactive sintering of the correct ratios of mixed powders of HfO2 and Ta2O5 and verified the low thermal conductivity of Hf6Ta2O17 superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf6Ta2O17, which shows an initial parabolic oxidation kinetics.

  14. Decomposition of nitrous oxide at medium temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Loeffler, G.; Wargadalam, V.J.; Winter, F.; Hofbauer, H.

    2000-03-01

    Flow reactor experiments were done to study the decomposition of N{sub 2}O at atmospheric pressure and in a temperature range of 600--1,000 C. Dilute mixtures of N{sub 2}O with H{sub 2}, CH{sub 4}, CO with and without oxygen with N{sub 2} as carrier gas were studied. To see directly the relative importance of the thermal decomposition versus the destruction by free radicals (i.e.: H, O, OH) iodine was added to the reactant mixture suppressing the radicals' concentrations towards their equilibrium concentrations. The experimental results were discussed using a detailed chemistry model. This work shows that there are still some uncertainties regarding the kinetics of the thermal decomposition and the reaction between N{sub 2}O and the O radical. Using the recommendations applied in this work for the reaction N{sub 2}O + M {leftrightarrow} N{sub 2} + O + M and for N{sub 2}O + O {leftrightarrow} products, a good agreement with the experimental data can be obtained over a wide range of experimental conditions. The reaction between N{sub 2}O and OH is of minor importance under present conditions as stated in latest literature. The results show that N{sub 2}O + H {leftrightarrow} N{sub 2} + OH is the most important reaction in the destruction of N{sub 2}O. In the presence of oxygen it competes with H + O{sub 2} + M {leftrightarrow} HO{sub 2} + M and H + O{sub 2} {leftrightarrow} O + OH, respectively. The importance of the thermal decomposition (N{sub 2}O + M {leftrightarrow} N{sub 2} + O + M) increases with residence time. Reducing conditions and a long residence time lead to a high potential in N{sub 2}O reduction. Especially mixtures of H{sub 2}/N{sub 2}O and CO/H{sub 2}O/N{sub 2}O in nitrogen lead to a chain reaction mechanism causing a strong N{sub 2}O reduction.

  15. Comparison of iron and copper doped manganese cobalt spinel oxides as protective coatings for solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Talic, Belma; Molin, Sebastian; Wiik, Kjell

    2017-01-01

    MnCo2O4, MnCo1.7Cu0.3O4 and MnCo1.7Fe0.3O4 are investigated as coatings for corrosion protection of metallic interconnects in solid oxide fuel cell stacks. Electrophoretic deposition is used to deposit the coatings on Crofer 22 APU alloy. All three coating materials reduce the parabolic oxidation...

  16. Investigations into the interactions between sulfur and anodes for solid oxide fuel cells

    Science.gov (United States)

    Cheng, Zhe

    Solid oxide fuel cells (SOFCs) are electrochemical devices based on solid oxide electrolytes that convert chemical energy in fuels directly into electricity via electrode reactions. SOFCs have the advantages of high energy efficiency and low emissions and hold the potential to be the power of the future especially for small power generation systems (1-10 kW). Another unique advantage of SOFCs is the potential to directly utilize hydrocarbon fuels such as natural gas through internal reforming. However, all hydrocarbon fuels contain some sulfur compounds, which transform to hydrogen sulfide (H2S) in the reforming process and dramatically degrade the performance of the existing SOFCs. In this study, the interactions between sulfur contaminant (in the form of H2S) and the anodes for SOFCs were systematically investigated in order to gain a fundamental understanding of the mechanism of sulfur poisoning and ultimately to achieve rational design of sulfur-tolerant anodes. The sulfur poisoning behavior of the state-of-the-art Ni-YSZ cermet anodes was characterized using electrochemical measurements performed on button cells (of different structures) under various operating conditions, including H2S concentration, temperature, cell current density/terminal voltage, and cell structure. Also, the mechanisms of interactions between sulfur and the Ni-YSZ cermet anode were investigated using both ex situ and in situ characterization techniques such as Raman spectroscopy. Results suggest that the sulfur poisoning of Ni-YSZ cermet anodes at high temperatures in fuels with ppm-level H2S is due not to the formation of multi-layer conventional nickel sulfides but to the adsorption of sulfur on the nickel surface. In addition, new sulfur-tolerant anode materials were explored in this study. Thermodynamic principles were applied to predict the stability of candidate sulfur-tolerant anode materials and explain complex phenomena concerning the reactivity of candidate materials with

  17. Energy and exergy analysis of an ethanol reforming process for solid oxide fuel cell applications.

    Science.gov (United States)

    Tippawan, Phanicha; Arpornwichanop, Amornchai

    2014-04-01

    The fuel processor in which hydrogen is produced from fuels is an important unit in a fuel cell system. The aim of this study is to apply a thermodynamic concept to identify a suitable reforming process for an ethanol-fueled solid oxide fuel cell (SOFC). Three different reforming technologies, i.e., steam reforming, partial oxidation and autothermal reforming, are considered. The first and second laws of thermodynamics are employed to determine an energy demand and to describe how efficiently the energy is supplied to the reforming process. Effect of key operating parameters on the distribution of reforming products, such as H2, CO, CO2 and CH4, and the possibility of carbon formation in different ethanol reformings are examined as a function of steam-to-ethanol ratio, oxygen-to-ethanol ratio and temperatures at atmospheric pressure. Energy and exergy analysis are performed to identify the best ethanol reforming process for SOFC applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) for Solid Oxide Fuel Cells

    Science.gov (United States)

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

    2005-01-01

    Recently, there has been a great deal of interest in research, development, and commercialization of solid oxide fuel cells. Joining and sealing are critical issues that will need to be addressed before SOFC's 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 SOFC's. The goal of the present study is to find the most suitable braze material for joining of yttria stabilized zirconia (YSZ) to stainless steels. 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.

  19. High temperature cyclic oxidation and hot corrosion behaviours of ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Oxidation and hot corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75,.

  20. Temperature dependence studies on the electro-oxidation of ...

    Indian Academy of Sciences (India)

    Cyclic voltammetry; electrochemical impedance spectroscopy; activation energy; fuel cell; alcohol. Abstract. Temperature dependence on the electro-oxidation of methanol, ethanol and 1-propanol in 0.5 M H2SO4 were investigated with Pt and PtRu electrodes. Tafel slope and apparent activation energy were evaluated ...

  1. Temperature dependence studies on the electro-oxidation of ...

    Indian Academy of Sciences (India)

    Administrator

    agreed that the electro-oxidation of methanol was improved by raising the temperature and ruthenium modification. Keywords. Cyclic voltammetry; electrochemical impedance spectroscopy; activation energy; fuel cell; alcohol. 1. Introduction. The use of hydrogen carrier like alcohol as alterna- tive fuels in the direct alcohol ...

  2. High temperature cyclic oxidation and hot corrosion behaviours of ...

    Indian Academy of Sciences (India)

    Oxidation and hot corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75, Superni ...

  3. Oxidation resistant iron and nickel alloys for high temperature use

    Science.gov (United States)

    Hill, V. L.; Misra, S. K.; Wheaton, H. L.

    1970-01-01

    Iron-base and nickel-base alloys exhibit good oxidation resistance and improved ductility with addition of small amounts of yttrium, tantalum /or hafnium/, and thorium. They can be used in applications above the operating temperatures of the superalloys, if high strength materials are not required.

  4. Electrical characterization of low temperature deposited oxide films ...

    Indian Academy of Sciences (India)

    Unknown

    Thin films of silicon dioxide are deposited on ZnO/n-Si substrate at a low temperature using tetra- ethylorthosilicate (TEOS). The ZnO/n-Si ... oxygen plasma has been extensively investigated because of its wide ranging applications in ... rapid electrical communication with the ZnO/n-Si sub- strate, whereas the oxide trapped ...

  5. Pressure effects in hollow and solid iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silva, N.J.O., E-mail: nunojoao@ua.pt [Departamento de Física and CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Saisho, S.; Mito, M. [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Millán, A.; Palacio, F. [Instituto de Ciencia de Materiales de Aragón, CSIC - Universidad de Zaragoza. Departamento de Física de la Materia Condensada, Facultad de Ciencias, 50009 Zaragoza (Spain); Cabot, A. [Universitat de Barcelona and Catalonia Energy Research Institute, Barcelona (Spain); Iglesias, Ò.; Labarta, A. [Departament de Física Fonamental, Universitat de Barcelona and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain)

    2013-06-15

    We report a study on the pressure response of the anisotropy energy of hollow and solid maghemite nanoparticles. The differences between the maghemite samples are understood in terms of size, magnetic anisotropy and shape of the particles. In particular, the differences between hollow and solid samples are due to the different shape of the nanoparticles and by comparing both pressure responses it is possible to conclude that the shell has a larger pressure response when compared to the core. - Highlights: ► Study of the pressure response of core and shell magnetic anisotropy. ► Contrast between hollow and solid maghemite nanoparticles. ► Disentanglement of nanoparticles core and shell magnetic properties.

  6. Electrochemical topotactic oxidation of nonstoichiometric perovskites at ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nemudry, A. [Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of Russian Academy of Science, Novosibirsk (Russian Federation); Goldberg, E.L. [Limnological Institute, Russian Academy of Science, Irkutsk (Russian Federation); Aguirre, M.; Alario-Franco, M.A. [Universidad Complytense, Lab. de Quimica del Estado Solido, Madrid (Spain)

    2002-05-01

    Different approaches to describe nonstoichiometry in perovskite-related oxides, oxygen diffusion models and kinetic data on electrochemical intercalation of oxygen in perovskite-related oxides are considered in the present study. It is demonstrated that the formation of micro-heterogeneous systems is characteristic of nonstoichiometric perovskite-related oxides. The adequate models should be considered for the proper characterization of the low temperature oxygen transport in oxides. These models should account for the high concentration of the high diffusivity paths in the sample. For micro-domain textured Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5} perovskite as example, the kinetic analysis of electrochemical oxygen intercalation is carried out. (authors)

  7. Electrochemical performance for the electro-oxidation of ethylene glycol on a carbon-supported platinum catalyst at intermediate temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kosaka, Fumihiko; Oshima, Yoshito [Department of Environment Systems, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563 (Japan); Otomo, Junichiro, E-mail: otomo@k.u-tokyo.ac.jp [Department of Environment Systems, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563 (Japan)

    2011-11-30

    Highlights: > High oxidation current in ethylene glycol electro-oxidation at intermediate temperature. > High C-C bond dissociation ratio of ethylene glycol at intermediate temperature. > Low selectivity for CH{sub 4} in ethylene glycol electro-oxidation. > High selectivity for CO{sub 2} according to an increase in steam to carbon ratios. - Abstract: To determine the kinetic performance of the electro-oxidation of a polyalcohol operating at relatively high temperatures, direct electrochemical oxidation of ethylene glycol on a carbon supported platinum catalyst (Pt/C) was investigated at intermediate temperatures (235-255 {sup o}C) using a single cell fabricated with a proton-conducting solid electrolyte, CsH{sub 2}PO{sub 4}, which has high proton conductivity (>10{sup -2} S cm{sup -1}) in the intermediate temperature region. A high oxidation current density was observed, comparable to that for methanol electro-oxidation and also higher than that for ethanol electro-oxidation. The main products of ethylene glycol electro-oxidation were H{sub 2}, CO{sub 2}, CO and a small amount of CH{sub 4} formation was also observed. On the other hand, the amounts of C{sub 2} products such as acetaldehyde, acetic acid and glycolaldehyde were quite small and were lower by about two orders of magnitude than the gaseous reaction products. This clearly shows that C-C bond dissociation proceeds almost to completion at intermediate temperatures and the dissociation ratio reached a value above 95%. The present observations and kinetic analysis suggest the effective application of direct alcohol fuel cells operating at intermediate temperatures and indicate the possibility of total oxidation of alcohol fuels.

  8. A Reversible Planar Solid Oxide Fuel-Fed Electrolysis Cell and Solid Oxide Fuel Cell for Hydrogen and Electricity Production Operating on Natural Gas/Biomass Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Greg, G.

    2007-03-31

    A solid oxide fuel-assisted electrolysis technique was developed to co-generate hydrogen and electricity directly from a fuel at a reduced cost of electricity. Solid oxide fuel-assisted electrolysis cells (SOFECs), which were comprised of 8YSZ electrolytes sandwiched between thick anode supports and thin cathodes, were constructed and experimentally evaluated at various operation conditions on lab-level button cells with 2 cm2 per-cell active areas as well as on bench-scale stacks with 30 cm2 and 100 cm2 per-cell active areas. To reduce the concentration overpotentials, pore former systems were developed and engineered to optimize the microstructure and morphology of the Ni+8YSZ-based anodes. Chemically stable cathode materials, which possess good electronic and ionic conductivity and exhibit good electrocatalytic properties in both oxidizing and reducing gas atmospheres, were developed and materials properties were investigated. In order to increase the specific hydrogen production rate and thereby reduce the system volume and capital cost for commercial applications, a hybrid system that integrates the technologies of the SOFEC and the solid-oxide fuel cell (SOFC), was developed and successfully demonstrated at a 1kW scale, co-generating hydrogen and electricity directly from chemical fuels.

  9. Oxygen transport in perovskite-type solid oxide fuel cell materials: insights from quantum mechanics.

    Science.gov (United States)

    Muñoz-García, Ana B; Ritzmann, Andrew M; Pavone, Michele; Keith, John A; Carter, Emily A

    2014-11-18

    CONSPECTUS: Global advances in industrialization are precipitating increasingly rapid consumption of fossil fuel resources and heightened levels of atmospheric CO2. World sustainability requires viable sources of renewable energy and its efficient use. First-principles quantum mechanics (QM) studies can help guide developments in energy technologies by characterizing complex material properties and predicting reaction mechanisms at the atomic scale. QM can provide unbiased, qualitative guidelines for experimentally tailoring materials for energy applications. This Account primarily reviews our recent QM studies of electrode materials for solid oxide fuel cells (SOFCs), a promising technology for clean, efficient power generation. SOFCs presently must operate at very high temperatures to allow transport of oxygen ions and electrons through solid-state electrolytes and electrodes. High temperatures, however, engender slow startup times and accelerate material degradation. SOFC technologies need cathode and anode materials that function well at lower temperatures, which have been realized with mixed ion-electron conductor (MIEC) materials. Unfortunately, the complexity of MIECs has inhibited the rational tailoring of improved SOFC materials. Here, we gather theoretically obtained insights into oxygen ion conductivity in two classes of perovskite-type materials for SOFC applications: the conventional La1-xSrxMO3 family (M = Cr, Mn, Fe, Co) and the new, promising class of Sr2Fe2-xMoxO6 materials. Using density functional theory + U (DFT+U) with U-J values obtained from ab initio theory, we have characterized the accompanying electronic structures for the two processes that govern ionic diffusion in these materials: (i) oxygen vacancy formation and (ii) vacancy-mediated oxygen migration. We show how the corresponding macroscopic oxygen diffusion coefficient can be accurately obtained in terms of microscopic quantities calculated with first-principles QM. We find that the

  10. Innovative Self-Healing Seals for Solid Oxide Fuel Cells (SOFC)

    Energy Technology Data Exchange (ETDEWEB)

    Raj Singh

    2012-06-30

    Solid oxide fuel cell (SOFC) technology is critical to several national initiatives. Solid State Energy Conversion Alliance (SECA) addresses the technology needs through its comprehensive programs on SOFC. A reliable and cost-effective seal that works at high temperatures is essential to the long-term performance of the SOFC for 40,000 hours at 800°C. Consequently, seals remain an area of highest priority for the SECA program and its industry teams. An innovative concept based on self-healing glasses was advanced and successfully demonstrated through seal tests for 3000 hours and 300 thermal cycles to minimize internal stresses under both steady state and thermal transients for making reliable seals for the SECA program. The self-healing concept requires glasses with low viscosity at the SOFC operating temperature of 800°C but this requirement may lead to excessive flow of the glass in areas forming the seal. To address this challenge, a modification to glass properties by addition of particulate fillers is pursued in the project. The underlying idea is that a non-reactive ceramic particulate filler is expected to form glass-ceramic composite and increase the seal viscosity thereby increasing the creep resistance of the glass-composite seals under load. The objectives of the program are to select appropriate filler materials for making glass-composite, fabricate glass-composites, measure thermal expansion behaviors, and determine stability of the glass-composites in air and fuel environments of a SOFC. Self-healing glass-YSZ composites are further developed and tested over a longer time periods under conditions typical of the SOFCs to validate the long-term stability up to 2000 hours. The new concepts of glass-composite seals, developed and nurtured in this program, are expected to be cost-effective as these are based on conventional processing approaches and use of the inexpensive materials.

  11. Solid State Joining of High Temperature Alloy Tubes for USC and Heat-Exchanger Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bimal Kad

    2011-12-31

    The principal objective of this project was to develop materials enabling joining technologies for use in forward looking heat-exchanger fabrication in Brayton cycle HIPPS, IGCC, FutureGen concepts capable of operating at temperatures in excess of 1000{degree}C as well as conventional technology upgrades via Ultra Super-Critical (USC) Rankine-cycle boilers capable of operating at 760{degree}C (1400F)/38.5MPa (5500psi) steam, while still using coal as the principal fossil fuel. The underlying mission in Rankine, Brayton or Brayton-Rankine, or IGCC combined cycle heat engine is a steady quest to improving operating efficiency while mitigating global environmental concerns. There has been a progressive move to higher overall cycle efficiencies, and in the case of fossil fuels this has accelerated recently in part because of concerns about greenhouse gas emissions, notably CO{sub 2}. For a heat engine, the overall efficiency is closely related to the difference between the highest temperature in the cycle and the lowest temperature. In most cases, efficiency gains are prompted by an increase in the high temperature, and this in turn has led to increasing demands on the materials of construction used in the high temperature end of the systems. Our migration to new advanced Ni-base and Oxide Dispersion Strengthened (ODS) alloys poses significant fabrication challenges, as these materials are not readily weldable or the weld performs poorly in the high temperature creep regime. Thus the joining challenge is two-fold to a) devise appropriate joining methodologies for similar/dissimilar Ni-base and ODS alloys while b) preserving the near baseline creep performance in the welded region. Our program focus is on solid state joining of similar and dissimilar metals/alloys for heat exchanger components currently under consideration for the USC, HIPPS and IGCC power systems. The emphasis is to manipulate the joining methods and variables available to optimize joint creep

  12. Effect of temperature on the oxidation of soybean biodiesel

    Directory of Open Access Journals (Sweden)

    Pereira, G. G.

    2015-06-01

    Full Text Available This paper proposes to examine the effect of temperature on the oxidation behavior of biodiesel. Soybean biodiesel was oxidized at different temperatures (room temperature, 60, and 110 °C, and the increase in primary and secondary oxidation products was determined based on the peroxide and anisidine values, respectively, during the induction period (IP. The results indicated that the evolution of hydroperoxides followed zero-order reaction kinetics during the IP at all temperatures, and their rate of formation was exponentially affected by temperature. It was also deduced that temperature influenced the ratio between primary and secondary oxidation products formation, which decreased as the temperature increased. Additionally, it was possible to predict the oxidation behavior of the soybean biodiesel at room temperature by an exponential model fitted to the IP values at different temperatures (70, 80, 90, 100, and 110 °C using the Rancimat apparatus.El propósito de este trabajo es evaluar el efecto de la temperatura en el comportamiento oxidativo del biodiesel. Biodiesel derivado de aceite de soja fue oxidado a diferentes temperaturas (temperatura ambiente, 60 y 110 °C y se evaluaron el contenido de compuestos primarios y secundarios de oxidación mediante el índice de peróxidos y de anisidina, respectivamente, a lo largo del periodo de inducción. Los resultados indicaron que el contenido de hidroperóxidos evolucionó siguiendo una cinética de orden cero a lo largo del periodo de inducción a todas las temperaturas y que su velocidad de formación cambió exponencialmente con la temperatura. También se dedujo que la temperatura influyó en la relación entre la formación de los productos de oxidación primarios y secundarios, disminuyendo a medida que aumentaba la temperatura. Además, fue posible predecir el comportamiento oxidativo del biodiesel de soja a temperatura ambiente ajustando a un modelo exponencial los valores de periodo

  13. Thermocouple temperature measurements in shock-compressed solids

    Science.gov (United States)

    Bloomquist, D. D.; Sheffield, S. A.

    1980-10-01

    The emf produced by 5-μm-thick foil thermocouples when subjected to shock loading was studied over a stress range from 0.5 to 10 GPa. Thermocouples of either copper and constantan or chromel and alumel were embedded in the host materials, polymethyl methacrylate (PMMA), Epon 828 epoxy, single-crystal Al2O3, or vitreous SiO2. The observed emf history rises to a plateau in a period that varied from less than 100 ns for Al2O3 to about 500 ns for PMMA. Temperatures inferred from the constant-voltage portion of the records using standard thermocouple tables (corrected for pressure) compare favorably with calculated temperatures for PMMA and epoxy below 2.0 and 4.5 GPa, respectively. Above these threshold stresses, the observed temperatures increase rapidly with compression, which may indicate an exothermic reaction. Inferred temperatures for the two types of thermocouples are in good agreement. The shape of the response history, and agreement with predicted temperatures for PMMA and epoxy, indicate that the thermocouple and host material come to thermal equilibrium during the transient portion of the response. In the elastic materials Al2O3 and SiO2, the observed temperatures are better correlated with temperatures predicted for shock compression of the thermocouple materials than those predicted for the host materials, indicating that thermal equilibration is not achieved in the available test time.

  14. C-104 high-level waste solids: Washing/leaching and solubility versus temperature studies

    Energy Technology Data Exchange (ETDEWEB)

    GJ Lumetta; DJ Bates; JP Bramson; LP Darnell; OT Farmer III; SK Fiskum; LR Greenwood; FV Hoopes; CZ Soderquist; MJ Steele; RT Steele; MW Urie; JJ Wagner

    2000-05-17

    This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing and caustic leaching on the composition of the C-104 HLW solids. The objective of this work was to determine the composition of the C-104 solids remaining after washing with 0.01 M NaOH or leaching with 3 M NaOH. Another objective of this test was to determine the solubility of the C-104 solids as a function of temperature. The work was conducted according to test plan BNFL-TP-29953-8, Rev. 0, ``Determination of the Solubility of HLW Sludge Solids.

  15. Temperature and high pressure effects on the structural features of catalytic nanocomposites oxides by Raman spectroscopy.

    Science.gov (United States)

    da Silva, Antonio N; Pinto, Raffael C F; Freire, Paulo T C; Junior, Jose Alves L; Oliveira, Alcineia C; Filho, Josué M

    2015-03-05

    Structural characterizations of nanostructured oxides were studied by X-ray diffraction (XRD), Raman and infrared spectroscopy. The oxides catalysts namely, SnO2, ZrO2, CeO2, MnOx, Al2O3 and TiO2 were prepared by a nanocasting route and the effect of the temperature and pressure on the stability of the solids was evaluated. Raman spectra showed that ZrO2 and TiO2 exhibited phase transitions at moderate temperatures whereas CeO2, SnO2 and MnOx had an effective creation of defects in their structures upon annealing at elevated temperatures. The results suggested also that the effect of the temperature on the particles growth is related to the type of oxide. In this regard, phase transition by up to 600°C accelerated the sintering of ZrO2 and CeO2 grains compared to TiO2, SnO2 and MnOx counterparts. Under hydrostatic pressures lower than 10GPa, rutile TiO2 and tetragonal ZrO2 exhibited pressure induced phase transition whereas CeO2 and SnO2 were stable at pressures close to 15GPa. The experiments revealed that the nanostructured SnO2 oxide exhibited stable performance at relatively high temperatures without phase transition or sintering, being suitable to be used as catalysts in the range of temperature and pressure studied. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Micro solid oxide fuel cells: a new generation of micro-power sources for portable applications

    Science.gov (United States)

    Chiabrera, Francesco; Garbayo, Iñigo; Alayo, Nerea; Tarancón, Albert

    2017-06-01

    Portable electronic devices are already an indispensable part of our daily life; and their increasing number and demand for higher performance is becoming a challenge for the research community. In particular, a major concern is the way to efficiently power these energy-demanding devices, assuring long grid independency with high efficiency, sustainability and cheap production. In this context, technologies beyond Li-ion are receiving increasing attention, among which the development of micro solid oxide fuel cells (μSOFC) stands out. In particular, μSOFC provides a high energy density, high efficiency and opens the possibility to the use of different fuels, such as hydrocarbons. Yet, its high operating temperature has typically hindered its application as miniaturized portable device. Recent advances have however set a completely new range of lower operating temperatures, i.e. 350-450°C, as compared to the typical <900°C needed for classical bulk SOFC systems. In this work, a comprehensive review of the status of the technology is presented. The main achievements, as well as the most important challenges still pending are discussed, regarding (i.) the cell design and microfabrication, and (ii.) the integration of functional electrolyte and electrode materials. To conclude, the different strategies foreseen for a wide deployment of the technology as new portable power source are underlined.

  17. Summary Report on Solid-oxide Electrolysis Cell Testing and Development

    Energy Technology Data Exchange (ETDEWEB)

    J.E. O' Brien; X. Zhang; R.C. O' Brien; G.L. Hawkes

    2012-01-01

    Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells (SOECs) for large-scale hydrogen production from steam over a temperature range of 800 to 900 C. From 2003 to 2009, this work was sponsored by the United States Department of Energy Nuclear Hydrogen Initiative, under the Office of Nuclear Energy. Starting in 2010, the high-temperature electrolysis (HTE) research program has been sponsored by the INL Next Generation Nuclear Plant Project. This report provides a summaryof program activities performed in Fiscal Year (FY) 2011 and the first quarter of FY-12, with a focus on small-scale testing and cell development activities. HTE research priorities during this period have included the development and testing of SOEC and stack designs that exhibit high-efficiency initial performance and low, long-term degradation rates. This report includes contributions from INL and five industry partners: Materials and Systems Research, Incorporated (MSRI); Versa Power Systems, Incorporated (VPS); Ceramatec, Incorporated; National Aeronautics and Space Administration - Glenn Research Center (NASA - GRC); and the St. Gobain Advanced Materials Division. These industry partners have developed SOEC cells and stacks for in-house testing in the electrolysis mode and independent testing at INL. Additional fundamental research and post-test physical examinations have been performed at two university partners: Massachusetts Institute of Technology (MIT) and the University of Connecticut. Summaries of these activities and test results are also presented in this report.

  18. A Numerical Investigation of the Thermal Stresses of a Planar Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Paulina Pianko-Oprych

    2016-09-01

    Full Text Available A typical operating temperature of a solid oxide fuel cell (SOFC is quite high above 750 °C and affects the thermomechanical behavior of the cell. Thermal stresses may cause microstructural instability and sub-critical cracking. Therefore, a joint analysis by the computational fluid dynamics (CFD and computational structural mechanics based on the finite element method (FEM was carried out to analyze thermal stresses in a planar SOFC and to predict potential failure locations in the cell. A full numerical model was based on the coupling of thermo-fluid model with the thermo-mechanical model. Based on a temperature distribution from the thermo-fluid model, stress distribution including the von Mises stress, shear stress as well as the operating principal stress were derived in the thermo-mechanical model. The FEM calculations were performed under different working conditions of the planar SOFC. The highest total stress was noticed at the lower operating voltage of 0.3 V, while the lowest total stress was determined at the voltage of 0.7 V. The obtained stress distributions allowed a better understanding of details of internal processes occurring within the SOFC and provided helpful guidance in the optimization of a new SOFC design.

  19. Thermodynamic simulation of biomass gas steam reforming for a solid oxide fuel cell (SOFC system

    Directory of Open Access Journals (Sweden)

    A. Sordi

    2009-12-01

    Full Text Available This paper presents a methodology to simulate a small-scale fuel cell system for power generation using biomass gas as fuel. The methodology encompasses the thermodynamic and electrochemical aspects of a solid oxide fuel cell (SOFC, as well as solves the problem of chemical equilibrium in complex systems. In this case the complex system is the internal reforming of biomass gas to produce hydrogen. The fuel cell input variables are: operational voltage, cell power output, composition of the biomass gas reforming, thermodynamic efficiency, electrochemical efficiency, practical efficiency, the First and Second law efficiencies for the whole system. The chemical compositions, molar flows and temperatures are presented to each point of the system as well as the exergetic efficiency. For a molar water/carbon ratio of 2, the thermodynamic simulation of the biomass gas reforming indicates the maximum hydrogen production at a temperature of 1070 K, which can vary as a function of the biomass gas composition. The comparison with the efficiency of simple gas turbine cycle and regenerative gas turbine cycle shows the superiority of SOFC for the considered electrical power range.

  20. Hydrogen Production Performance of a 10-Cell Planar Solid-Oxide Electrolysis Stack

    Energy Technology Data Exchange (ETDEWEB)

    James O& #39; Brien; Carl Stoots; Steve Herring; J. Hartvigsen

    2005-05-01

    An experimental study is under way to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800 to 900ºC. Results presented in this paper were obtained from a ten-cell planar electrolysis stack, with an active area of 64 cm2 per cell. The electrolysis cells are electrolytesupported, with scandia-stabilized zirconia electrolytes (~140 µm thick), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions (0.1 - 0.6), gas flow rates (1000 - 4000 sccm), and current densities (0 to 0.38 A/cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. Cell operating potentials and cell current were varied using a programmable power supply. Hydrogen production rates up to 100 Normal liters per hour were demonstrated. Values of area-specific resistance and stack internal temperatures are presented as a function of current density. Stack performance is shown to be dependent on inlet steam flow rate.

  1. Facile Synthesis of Highly Active and Robust Ni-Mo Bimetallic Electrocatalyst for Hydrocarbon Oxidation in Solid Oxide Fuel Cells

    NARCIS (Netherlands)

    Hua, B.; Li, M.; Zhang, Y.-Q.; Chen, J.; Sun, Y.-F.; Yan, N.; Li, J.; Luo, J.L.

    2016-01-01

    We report a novel Ni–Mo bimetallic alloy decorated with multimicrocrystals as an efficient anode catalyst for hydrocarbon-fueled solid oxide fuel cells (SOFCs). We show that these Ni–Mo bimetallic alloys are highly active, thermally stable, and sulfur/coke tolerant electrocatalysts for hydrocarbon

  2. Iron salts in solid state and in frozen solutions as dosimeters for low irradiation temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, T. [Facultad de Quimica UNAM, Ciudad Universitaria, D.F. Mexico (Mexico); Lartigue, J. [Facultad de Quimica UNAM, Ciudad Universitaria, D.F. Mexico (Mexico); Ramos-Bernal, S. [Instituto de Ciencias Nucleares, UNAM, A.P. 70-543 C.P.4510, Ciudad Universitaria, D.F. Mexico (Mexico); Ramos, A. [Instituto de Ciencias Nucleares, UNAM, A.P. 70-543 C.P.4510, Ciudad Universitaria, D.F. Mexico (Mexico); Mosqueira, G.F. [Direccion General de Divulgacion de la Ciencia de la UNAM, A.P. 70-487, C:P, D.F. Mexico 04510 (Mexico); Negron-Mendoza, A. [Instituto de Ciencias Nucleares, UNAM, A.P. 70-543 C.P.4510, Ciudad Universitaria, D.F. Mexico (Mexico)]. E-mail: negron@nuclecu.unam.mx

    2005-12-01

    The aim of this work is to study the irradiation of iron salts in solid state (heptahydrated ferrous sulfate) and in frozen acid solutions. The study is focused on finding their possible use as dosimeters for low temperature irradiations and high doses. The analysis of the samples was made by UV-visible and Moessbauer spectroscopies. The output signal was linear from 0 to 10 MGy for the solid samples, and 0-600 Gy for the frozen solutions. The obtained data is reproducible and easy to handle. For these reasons, heptahydrate iron sulfate is a suitable dosimeter for low temperature and high irradiation doses, in solid state, and in frozen solution.

  3. Reshaping Lithium Plating/Stripping Behavior via Bifunctional Polymer Electrolyte for Room-Temperature Solid Li Metal Batteries.

    Science.gov (United States)

    Zeng, Xian-Xiang; Yin, Ya-Xia; Li, Nian-Wu; Du, Wen-Cheng; Guo, Yu-Guo; Wan, Li-Jun

    2016-12-14

    High-energy rechargeable Li metal batteries are hindered by dendrite growth due to the use of a liquid electrolyte. Solid polymer electrolytes, as promising candidates to solve the above issue, are expected to own high Li ion conductivity without sacrificing mechanical strength, which is still a big challenge to realize. In this study, a bifunctional solid polymer electrolyte exactly having these two merits is proposed with an interpenetrating network of poly(ether-acrylate) (ipn-PEA) and realized via photopolymerization of ion-conductive poly(ethylene oxide) and branched acrylate. The ipn-PEA electrolyte with facile processing capability integrates high mechanical strength (ca. 12 GPa) with high room-temperature ionic conductance (0.22 mS cm-1), and significantly promotes uniform Li plating/stripping. Li metal full cells assembled with ipn-PEA electrolyte and cathodes within 4.5 V vs Li+/Li operate effectively at a rate of 5 C and cycle stably at a rate of 1 C at room temperature. Because of its fabrication simplicity and compelling characteristics, the bifunctional ipn-PEA electrolyte reshapes the feasibility of room-temperature solid-state Li metal batteries.

  4. Low temperature high density plasma nitriding of stainless steel molds for stamping of oxide glasses

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2016-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a die for mold- and direct-stamping processes of optical oxide glasses. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical oxide-glass elements. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness over 1400 HV within its thickness of 50 μm without any formation of nitrides after plasma nitriding at 693 K for 14.4 ks. This plasma-nitrided mold was utilized for mold-stamping of two colored oxide glass plates at 833 K; these plates were successfully deformed and joined into a single glass plate by this stamping without adhesion or galling of oxide glasses onto the nitrided mold surface.

  5. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    Science.gov (United States)

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-03-02

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  6. Copper-substituted perovskite compositions for solid oxide fuel cell cathodes and oxygen reduction electrodes in other electrochemical devices

    Science.gov (United States)

    Rieke, Peter C [Pasco, WA; Coffey, Gregory W [Richland, WA; Pederson, Larry R [Kennewick, WA; Marina, Olga A [Richland, WA; Hardy, John S [Richland, WA; Singh, Prabhaker [Richland, WA; Thomsen, Edwin C [Richland, WA

    2010-07-20

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells. Also provided are electrochemical devices that include active oxygen reduction electrodes, such as solid oxide fuel cells, sensors, pumps and the like. The compositions comprises a copper-substituted ferrite perovskite material. The invention also provides novel methods for making and using the electrode compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having cathodes comprising the compositions.

  7. Calcium- and Cobalt-doped Yttrium Chromites as an Interconnect Material for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Kyung J.; Cramer, Carolyn N.; Thomsen, Edwin C.; Coyle, Christopher A.; Coffey, Greg W.; Marina, Olga A.

    2010-04-23

    The structural, thermal and electrical characteristics of calcium- and cobalt-doped yttrium chromites were studied for a potential use as the interconnect material in high temperature solid oxide fuel cells (SOFCs) as well as other high temperature electrochemical and thermoelectric devices. The Y0.8Ca0.2Cr1-xCoxO3±δ (x=0, 0.1, 0.2, 0.3) compositions had single phase orthorhombic perovskite structures in the wide range of oxygen pressures. Sintering behavior was remarkably enhanced upon cobalt doping and densities 95% and 97% of theoretical density were obtained after sintering at 1300oC in air, when x was 0.2 and 0.3, respectively. The electrical conductivity in both oxidizing and reducing atmospheres was significantly improved with cobalt content, and values of 49 and 10 S/cm at 850oC and 55 and 14 S/cm at 950oC in air and forming gas, respectively, were reported for x=0.2. The conductivity increase was attributed to the charge carrier density increase upon cobalt substitution for chromium confirmed with Seebeck measurements. The thermal expansion coefficient (TEC) was increased with cobalt content and closely matched to that of an 8 mol% yttria-stabilized zirconia (YSZ) electrolyte for 0.1 ≤ x ≤ 0.2. The chemical compatibility between Y0.8Ca0.2Cr1-xCoxO3±δ and YSZ was evaluated firing the two at 1400oC and no reaction products were found if x value was kept lower than 0.2.

  8. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.

    2015-06-23

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  9. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature.

    Science.gov (United States)

    Balasubramanian, C; Joseph, B; Orpe, P B; Saini, N L; Mukherjee, S; Dziedzic-Kocurek, K; Stanek, J; Di Gioacchino, D; Marcelli, A

    2016-11-04

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  10. Dynamic modeling and predictive control in solid oxide fuel cells first principle and data-based approaches

    CERN Document Server

    Huang, Biao; Murshed, A K M Monjur

    2012-01-01

    The high temperature solid oxide fuel cell (SOFC) is identified as one of the leading fuel cell technology contenders to capture the energy market in years to come. However, in order to operate as an efficient energy generating system, the SOFC requires an appropriate control system which in turn requires a detailed modelling of process dynamics. Introducting state-of-the-art dynamic modelling, estimation, and control of SOFC systems, this book presents original modelling methods and brand new results as developed by the authors. With comprehensive coverage and bringing together many

  11. Steady state creep of Ni-8YSZ substrates for application in solid oxide fuel and electrolysis cells

    Science.gov (United States)

    Wei, J.; Malzbender, J.

    2017-08-01

    Steady state creep was characterized for Ni-8YSZ solid oxide fuel/electrolysis cell (SOFC/SOEC) substrate material. Intrinsic and extrinsic factors affecting creep behavior were assessed, such as compositional ratio, porosity and mechanical loading configuration. Mechanical tests were supported by analytical and numerical calculations. The results indicated a diffusion-dominated creep mechanism under both compressive and tensile creep conditions. Creep appeared to be dominated by the ceramic phase. Porosity significantly reduced creep resistance. The activation energy was discussed based on loading configuration, temperature and porosity.

  12. New Solid State Sensor for Detection of Humidity, Based on Ni, Co, and Mn Oxide Nano Composite Doped with Lithium

    Directory of Open Access Journals (Sweden)

    A. Kazemzadeh

    2008-07-01

    Full Text Available The lithium doped metal oxide nano composite was fabricated by sol-gel method. The metal oxide nano composite was then sintered at 700 °C for 6 h. The metal oxide nano composite was characterized by solid-state electrical measurement, AAS, XRD, fr-IR, SEM, BET, AFM and TEM studies to analyze activation energy for conduction, surface morphology and pore structure of the sensor materials, respectively. The humidity sensing properties of metal oxide nano composite was measured by employing the sensor configuration of a cylindrical disk. The micropores of nano composite have a crucial role in humidity sensing. The materials was subjected to water vapor of different humidity achieve by various water buffers at room temperature and the electrical conductivity was measured as a function of relative humidity (RT. The electrical resistively drastically decreases with increase in humidity and hence proving the materials to be a good water vapor sensor. The sensitivity factor (Sf of Li doped metal oxide nano composite has been increased 9.2 times as compare to the undoped metal oxide nano composite sensitivity factor. The response and recovery time of sensor was also measured.

  13. Development of solid electrolytes for water electrolysis at intermediate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Linkous, C.A.; Kopitzke, R.W. [Florida Solar Energy Center, Cape Canaveral, FL (United States)

    1995-09-01

    If an electrolyzer could operate at higher temperatures, several benefits would accrue. The first is that the thermodynamic electrical energy requirement to drive the reaction would be reduced. Supplying the total enthalpy of reaction at any temperature involves a combination of electrical and thermal energy inputs. Because of the positive entropy associated with water decomposition, the thermal contribution increases as temperature rises, allowing the free energy requirement to decrease. Thus the open circuit voltage, V{sub oc}, for water splitting drops as temperature rises. At room temperature, V{sub oc} for water decomposition is 1.229 V. At 400{degrees}C, voltage requirement has dropped to 1.1 V; at 1000{degrees}C, it is only 0.92 V. Since electricity is a more expensive form of energy on a btu basis, the more energy taken from the thermal surroundings the better. Moreover, this thermal energy content could be solar-derived. While the cost of solar thermal energy varies in the range of $360-900/peak kilowatt, the installed cost of photovoltaic electricity is in the range of $4,000-5,000/peak kilowatt. Thus if one is compelled to erect an array of photovoltaic panels to generate the e.m.f. necessary to split water, substituting as much area with thermal collectors as possible represents a substantial cost savings.

  14. High temperature oxidation of iron-chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, Lars

    2003-06-15

    The high temperature oxidation of the ferritic alloy Fe78Cr22 has been investigated in the present work. The effect of small alloying additions of cerium and/or silicon was also investigated. The alloys were oxidized at 973, 1173 and 1373 K in either air or a hydrogen/argon mixture. The various reaction atmospheres contained between 0.02 and 50% water vapour. The oxide scales formed on the various alloys at 973 K consisted of thin chromia layers. The oxide scales grown on the alloys at 1173 K also consisted of a chromia layer. The microstructure of the chromia scales was found to depend on the reaction atmosphere. The chromia scales grown in hydrogen/argon atmospheres formed oxide whiskers and oxide ridges at the surface of the scales, while the chromia scales grown in air formed larger oxide grains near the surface. This difference in oxide microstructure was due to the vaporization of chromium species from the chromia scales grown in air. Two different growth mechanisms are proposed for the growth of oxide whiskers. The growth rate of the chromia scales was independent of the oxygen activity. This is explained by a growth mechanism of the chromia scales, where the growth is governed by the diffusion of interstitial chromium. The addition of silicon to the iron-chromium alloy resulted in the formation of silica particles beneath the chromia scale. The presence of silicon in the alloy was found to decrease the growth rate of the chromia scale. This is explained by a blocking mechanism, where the silica particles beneath the chromia scale partly block the outwards diffusion of chromium from the alloy to the chromia scale. The addition of cerium to the iron-chromium alloy improved the adhesion of the chromia scale to the alloy and decreased the growth rate of chromia. It was observed that the minimum concentration of cerium in the alloy should be 0.3 at.% in order to observe an effect of the cerium addition. The effect of cerium is explained by the &apos

  15. Thermal properties of solids at room and cryogenic temperatures

    CERN Document Server

    Ventura, Guglielmo

    2014-01-01

    This book is a guide for materials scientists, physicists, chemists and engineers who wish to explore the field of low-temperature material properties. The focus is on heat capacity, thermal expansion and electrical and thermal conductivity. The authors report a wide range of experimental details and data, and have compiled useful tables of low-temperature data. Each chapter of the book starts by addressing the theoretical basis of the phenomena. This is a concise presentation, but it helps the reader to develop a deeper understanding of the experiments. The second part of the chapters is dedicated to describing the main experimental techniques to measure thermal properties at low and very low temperature ranges. The final part of each chapter provides a wealth of relevant experimental data in the form of tables and graphs.

  16. Expanding the Scope of Biocatalysis: Oxidative Biotransformations on Solid-Supported Substrates

    OpenAIRE

    Brooks, Sarah J; Coulombel, Lydie; Ahuja, Disha; Clark, Douglas S.; Dordick, Jonathan S.

    2008-01-01

    Oxidative biocatalytic reactions were performed on solid-supported substrates, thus expanding the repertoire of biotransformations that can be carried out on the solid phase. Various phenylacetic and benzoic acid analogs were attached to controlled pore glass beads via an enzyme-cleavable linker. Reactions catalyzed by peroxidases (soybean and chloro), tyrosinase, and alcohol oxidase/dehydrogenase gave a range of products, including oligophenols, halogenated aromatics, catechols, and aryl ald...

  17. Sorption characteristics of fluoride on to magnesium oxide-rich phases calcined at different temperatures.

    Science.gov (United States)

    Sasaki, Keiko; Fukumoto, Naoyuki; Moriyama, Sayo; Hirajima, Tsuyoshi

    2011-07-15

    The effect of calcination temperature during production of magnesium oxide-rich phases from MgCO(3) on the sorption of F(-) ions in the aqueous phase has been investigated. Magnesium oxide-rich phases were formed by calcination at over 873 K for 1h. Higher calcination temperatures produced more crystalline MgO with smaller specific surface area and provided larger values of the total basicity per unit surface area. The higher calcination temperatures lead to slower F(-) removal rate, and lower equilibrium F(-) concentrations, when the equilibrium F(-) concentrations are less than 1 mmol dm(-3). Larger total basicity per unit surface area made the reactivity with F(-) ions in aqueous phase more feasible, resulting in a greater degree of F(-) sorption. For equilibrium F(-) concentrations more than 1 mmol dm(-3), lower calcination temperatures favored the co-precipitation of F(-) with Mg(OH)(2), probably leading to the formation of Mg(OH)(2-x)F(x), and the achievement of larger sorption density. This is the first paper which describes the relationship between the solid base characteristics obtained by CO(2)-TPD for MgO with different calcination temperatures as a function of the reactivity of F(-) sorption in the aqueous phase. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Effects of thermal aging on thermo-mechanical behavior of a glass sealant for solid oxide cell applications

    DEFF Research Database (Denmark)

    Abdoli, Hamid; Alizadeh, Parvin; Boccaccini, Dino

    2014-01-01

    Thermo-mechanical properties of a silicate based glass and its potential use for sealing application in intermediate temperature solid oxide cell (SOC) are presented in this paper. Effects of thermal aging are discussed on structural and microstructural evolution, thermal expansion, viscosity......, modulus of elasticity, and high-temperature deformation of the glass. The balance between the viscosity and viscous flowing behavior was explored for the non-aged and aged glasses as it is essential to have a successful sealing for a SOC stack. The results reveal a temperature dependence of Young......'s modulus in which a transition between a slow softening (elastic) regime and a rapid softening one was observed. Crystallization induced by thermal aging led to higher creep resistance, but lower capability of crack healing when inspected by electron microscopy. However, potential of stress relaxation...

  19. Effect of pre-oxidation on the oxidation resistance of spinel-coated Fe-Cr ferritic alloy for solid oxide fuel cell applications

    Science.gov (United States)

    Ou, Ding Rong; Cheng, Mojie

    2014-02-01

    Low-temperature-sintered MnCo2O4-MnO2 coatings have been prepared on pre-oxidized SUS430 ferritic alloy by slurry coating. The effect of pre-oxidation treatment before slurry coating is then investigated. Microstructural and electrical characterizations show that 25 h of pre-oxidation at 800 °C could significantly improve the oxidation resistance of the coated alloy and effectively inhibit the increase in area-specific electrical resistance during long-term oxidation. These effects can be explained by the interfacial reactions between the coating and the pre-oxidized alloy during sintering and oxidation tests. Furthermore, this study suggests that the dense reaction layer at the coating-alloy interface could be the key to improving the oxidation resistance of metallic interconnects with low-temperature-sintered spinel coatings.

  20. Reactions of nitrogen oxides with heme models. Spectral and kinetic study of nitric oxide reactions with solid and solute Fe(III)(TPP)(NO3).

    Science.gov (United States)

    Kurtikyan, Tigran S; Gulyan, Gurgen M; Martirosyan, Garik G; Lim, Mark D; Ford, Peter C

    2005-05-04

    The reaction(s) of nitric oxide (nitrogen monoxide) gas with sublimed layers containing the nitrato iron(III) complex Fe(III)(TPP)(eta(2)-O(2)NO) (1, TPP = meso-tetraphenyl porphyrinate(2)(-)) leads to formation of several iron porphyrin species that are ligated by various nitrogen oxides. The eventual products of these low-temperature solid-state reactions are the nitrosyl complex Fe(TPP)(NO), the nitro-nitrosyl complex Fe(TPP)(NO(2))(NO), and 1 itself, and the relative final quantities of these were functions of the NO partial pressure. It is particularly notable that isotope labeling experiments show that the nitrato product is not simply unreacted 1 but is the result of a series of transformations taking place in the layered material. Thus, the nitrato complex formed from solid Fe(TPP)(eta(2)-O(2)NO) maintained under a (15)NO atmosphere was found to be the labeled analogue Fe(TPP)(eta(2)-O(2)(15)NO). The reactivities of the layered solids are compared to the behaviors of the same species in ambient temperature solutions. To interpret the reactions of the labeled nitrogen oxides, the potential exchange reactions between N(2)O(3) and (15)NO were examined, and complete isotope scrambling was observed between these species under the reaction conditions (T = 140 K). Overall it was concluded from isotope labeling experiments that the sequence of reactions is initiated by reaction of 1 with NO to give the nitrato nitrosyl complex Fe(TPP)(eta(1)-ONO(2))(NO) (2) as an intermediate. This is followed by a reaction in the presence of excess NO that is equivalent to the loss of the nitrate radical NO(3)(*)( )()to give Fe(TPP)(NO) as another transient species. A plausible pathway involving NO attack on the coordinated nitrate of 2 resulting in the release of N(2)O(4) concerted with electron transfer to the metal center is proposed.

  1. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    ) constraining the parameter values during fitting to ranges of physically reasonable values. Using these methods, the number of fitting parameters for four impedance spectra measured with isolated changes to the fuel and oxidant gas compositions, has been reduced from 80 to 21-34 depending on the model...

  2. Modelling of Physical, Chemical, and Material Properties of Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Jakub Kupecki

    2015-01-01

    Full Text Available This paper provides a review of modelling techniques applicable for system-level studies to account for physical, chemical, and material properties of solid oxide fuel cells. Functionality of 0D to 3D models is discussed and selected examples are given. Author provides information on typical length scales in evaluation of power systems with solid oxide fuel cells. In each section, proper examples of previous studies done in the field of 0D–3D modelling are recalled and discussed.

  3. Triple phase boundary specific pathway analysis for quantitative characterization of solid oxide cell electrode microstructure

    DEFF Research Database (Denmark)

    Jørgensen, Peter Stanley; Ebbehøj, Søren Lyng; Hauch, Anne

    2015-01-01

    The density and percolation of Triple phase boundary sites are important quantities in analyzing microstructures of solid oxide fuel cell electrodes from tomography data. However, these measures do not provide descriptions of the quality of the TPB sites in terms of the length and radius of the p......The density and percolation of Triple phase boundary sites are important quantities in analyzing microstructures of solid oxide fuel cell electrodes from tomography data. However, these measures do not provide descriptions of the quality of the TPB sites in terms of the length and radius...

  4. Oxygen scrubbing and sensing in plant growth chambers using solid oxide electrolyzers

    Science.gov (United States)

    Sridhar, K. R.; MacElroy, Robert D.

    1997-01-01

    The maintenance of optimal levels of oxygen in the gaseous environment of a plant growth chamber during light and dark periods is an essential criterion for the correct growth of plants. The use of solid oxide electrolyzers to control the oxygen levels by removing the excess gaseous oxygen during periods of illumination and full-scale photosynthesis is described. A part of the oxygen removed can be stored and supplied back to the plants during dark periods. The excess oxygen can be used by the crew. The electrolizer can be additionally used in its open circuit mode, to sense the oxygen concentrations in the plant chamber. The solid oxide electrolysis process is described.

  5. Melting temperature of uranium - plutonium mixed oxide fuel

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Tetsuya; Hirosawa, Takashi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-08-01

    Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960`s and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960`s and that some of the 1960`s data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO{sub 2} - PuO{sub 2} - PuO{sub 1.61} ideal solution model, and then formulized. (J.P.N.)

  6. Performance and Structural Evolution of Nano-Scale Infiltrated Solid Oxide Fuel Cell Cathodes

    Science.gov (United States)

    Call, Ann Virginia

    Nano-structured mixed ionic and electronic conducting (MIEC) materials have garnered intense interest in electrode development for solid oxide fuel cells due to their high surface areas which allow for effective catalytic activity and low polarization resistances. In particular, composite solid oxide fuel cell (SOFC) cathodes consisting of ionic conducting scaffolds infiltrated with MIEC nanoparticles have exhibited some of the lowest reported polarization resistances. In order for cells utilizing nanostructured moRPhologies to be viable for commercial implementation, more information on their initial performance and long term stability is necessary. In this study, symmetric cell cathodes were prepared via wet infiltration of Sr0.5Sm 0.5CoO3 (SSC) nano-particles via a nitrate process into porous Ce0.9Gd0.1O1.95 (GDC) scaffolds to be used as a model system to investigate performance and structural evolution. Detailed analysis of the cells and cathodes was carried out using electrochemical impedance spectroscopy (EIS). Initial polarization resistances (RP) as low as 0.11 O cm2 at 600ºC were obtained for these SSC-GDC cathodes, making them an ideal candidate for studying high performance nano-structured electrodes. The present results show that the infiltrated cathode microstructure has a direct impact on the initial performance of the cell. Small initial particle sizes and high infiltration loadings (up to 30 vol% SSC) improved initial RP. A simple microstructure-based electrochemical model successfully explained these trends in RP. Further understanding of electrode performance was gleaned from fitting EIS data gathered under varying temperatures and oxygen partial pressures to equivalent circuit models. Both RQ and Gerischer impedance elements provided good fits to the main response in the EIS data, which was associated with the combination of oxygen surface exchange and oxygen diffusion in the electrode. A gas diffusion response was also observed at relatively

  7. Kinetic features of the low-temperature oxidation of propane

    Science.gov (United States)

    Sargsyan, G. N.

    2012-11-01

    The results from recording the chemiluminescence in the infrared part of the spectrum that emerges during the oxidation of propane in air under the effect of monotonically increasing pressure within the range 2666 Pa ≤ P ≤ 16000 Pa, both under isothermal conditions and in the 593-600 K temperature range, are presented. It is established that no pulsed chemiluminescence is observed at constant values of pressure within the range 2666 Pa ≤ P ≤ 16000 Pa and temperature within the range of 593-600 K in the reaction mixture.

  8. Cast iron zinc galvanizing improved by high temperature oxidation process

    OpenAIRE

    D. Jędrzejczyk; M. Hajduga

    2010-01-01

    Purpose: To evaluate influence of the high-temperature oxidation, as the preliminary stage previous to coating with zinc on the change of surface layer structure as well as subsurface layer of cast iron with flake, vermicular and nodular graphite.Design/methodology/approach: The experiment was led in the temperature range: 850-1050ºC in ambient air. Samples have been taken out from the furnace separately after: 2-12 hours. After scale layer removal the hot dip zinc coating in industrial condi...

  9. Gas detection using low-temperature reduced graphene oxide sheets

    Science.gov (United States)

    Lu, Ganhua; Ocola, Leonidas E.; Chen, Junhong

    2009-02-01

    We demonstrate a high-performance gas sensor using partially reduced graphene oxide (GO) sheets obtained through low-temperature step annealing (300 °C at maximum) in argon flow at atmospheric pressure. The electrical conductance of GO was measured after each heating cycle to interpret the level of reduction. The thermally reduced GO showed p-type semiconducting behavior in ambient conditions and were responsive to low-concentration NO2 diluted in air at room temperature. The sensitivity is attributed to the electron transfer from the reduced GO to adsorbed NO2, which leads to enriched hole concentration and enhanced electrical conduction in the reduced GO sheet.

  10. Influence of temperature and chemical composition on phase transformations of selected oxide melts

    Directory of Open Access Journals (Sweden)

    J. Dobrovská

    2013-07-01

    Full Text Available The paper deals with structural changes of solid phase of selected oxide systems during their transition into liquid state. Analyses concerned poly-component systems forming basis of casting powders for CCM mould. Industrially used oxide system with prevailing contents of CaO–Al2O3–SiO2 components and with numerous accompanying admixtures was tested. Investigation was focused on temperatures, during which individual phases disappear and precipitate, as well as on influence of CaO content on phase composition at selected temperatures. The experiments were realised with use of original methodology consisting of shock cooling of the tested melt in liquid nitrogen. Thus obtained samples were further investigated by X-ray diffraction phase analyses at ambient temperatures. The obtained results provide additional data on physical-chemical properties of oxide systems, such as surface tension, viscosity, sintering intervals, etc., which can be used in technological practice for appropriate lubrication effect of casting powders in the mould.

  11. Impact of semi-solid formulations on skin penetration of iron oxide nanoparticles

    OpenAIRE

    Musazzi, Umberto M.; Santini, Benedetta; Selmin, Francesca; Marini, Valentina; Corsi, Fabio; Allevi, Raffaele; Ferretti, Anna M.; Prosperi, Davide; Cilurzo, Francesco; Colombo, Miriam; Minghetti, Paola

    2017-01-01

    Background This work aimed to provide useful information on the incidence of the choice of formulation in semi-solid preparations of iron-oxide nanoparticles (IONs). The appropriate analytical methods to assess the IONs physical stability and the effect of the semi-solid preparations on IONs human skin penetration were discussed. The physical stability of IONs (Dh?=?31???4?nm; ??=??65???5?mV) loaded in five semi-solid preparations (0.3% w/v), namely Carbopol gel (CP), hydroxyethyl cellulose g...

  12. Multiferroic iron oxide thin films at room temperature.

    Science.gov (United States)

    Gich, Martí; Fina, Ignasi; Morelli, Alessio; Sánchez, Florencio; Alexe, Marin; Gàzquez, Jaume; Fontcuberta, Josep; Roig, Anna

    2014-07-16

    Multiferroic behaviour at room temperature is demonstrated in ε-Fe2 O3 . The simple composition of this new ferromagnetic ferroelectric oxide and the discovery of a robust path for its thin film growth by using suitable seed layers may boost the exploitation of ε-Fe2 O3 in novel devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Thermal deoxygenation of graphite oxide at low temperature

    Science.gov (United States)

    Kampars, V.; Legzdina, M.

    2015-03-01

    Synthesis of graphene via the deoxygenation of the graphite oxide (GO) is a method for the large-scale production of this nanomaterial possessing exceptional mechanical, electrical and translucent properties. Graphite oxide sheet contains at least four different oxygen atoms connected to the Csp3 and Csp2 atoms of the sheet in the form of hydroxyl, epoxy, carboxyl or carbonyl groups. Some of these functional groups are located at the surface but others situated at the edges of the platelets. To obtain the graphene nanoplatelets or the few-layer graphene the oxygen functionalities must be removed. Exfoliation and deoxygenation can be accomplished by the use of chemical reductants or heat. Thermal deoxygenation as greener and simpler approach is more preferable over chemical reduction approach. Usually a considerable mass loss of GO observed upon heating at temperatures starting at 200 °C and is attributed to the deoxygenation process. In order to avoid the defects of the obtained graphene sheets it is very important to find the methods for lowering the deoxygenation temperature of GO. Herein, we have investigated the way treatment of the Hummer's synthesis product with acetone and methyl tert-butyl ether under ultrasonication in order to lower the thermal stability of the graphite oxide and its deoxygenation temperature. The obtained results indicate that treatment of the graphite oxide with solvents mentioned above substantially reduces the reduction and exfoliation temperature (130 °C) under ambient atmosphere. The investigation of the composition of evolved gases by hyphenated Pyr/GC/MS method at different experimental conditions under helium atmosphere shows that without the expected H2O, CO and CO2 also sulphur dioxide and acetone has been released.

  14. Solid oxide fuel cells, SOFC, in future power generation; Fastoxidbraensleceller, SOFC, i framtida kraftgenerering

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Kent; Baafaelt, M.

    1997-02-01

    Solid Oxide Fuel Cell, SOFC, is a very promising technological area for generating electricity in the future. Especially for small scale cogeneration. SOFC is an excellent choice due to its high efficiencies at small power plant sizes. The expected size of the power plants is 10-20 MWe but larger ones might be built. An important part of the assumptions in this report is the SOFC electric efficiency dependence of the pressure in the process. The electric efficiency is assumed to be 50% at atmospheric pressure and 55% at 10 atmospheres. These assumptions lead to a formula that describes the electric efficiency as a function of the pressure. The parametric study shows that the pressure has a very large influence of the electric efficiency. At low pressure and high Turbine Inlet Temperature (TIT) the electric efficiency will be higher than at high pressure and low TIT. The post intercooler temperature and the pressure drop over the SOFC unit have a moderate effect on the electric efficiency. In the process calculations the TIT is shown to have a very small influence on the plant efficiencies. Consequently, by lowering the TIT, the need for blade cooling and tougher materials can be avoided, with only a small electric efficiency decrease. The recuperator is a central part of the process. It evens out the influence from other parts in the process. This is one of the reasons why the polytropic efficiencies of the compressor and the expander have such a low influence on the process efficiency. The report shows that to receive high efficiencies in a SOFC/GT power plant, the points mentioned below should be taken into consideration: The pressure in the process should be approximately 4 bar; The compressor should have an intercooler; The TIT should be below the temperature where blade cooling is needed; No steam cycle should be connected after the gas turbine at sizes of 5-20 MW. 32 refs, 67 figs, 9 tabs, 15 appendices

  15. Physical Properties of Mixed Conductor Solid Oxide Fuel Cell Anodes of Doped CeO2

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Lindegaard, Thomas; Hansen, Uffe Rud

    1994-01-01

    Samples of CeO2 doped with oxides such as CaO and Gd2O3 were prepared. Their conductivities and expansions onreduction were measured at 1000°C, and the thermal expansion coefficients in the range 50 to 1000°C were determined. Theionic and electronic conductivity were derived from curves of total ...... for solid oxide fuel cell anodes. Not all requirements are fulfilled. Measures to compensate for this arediscussed....

  16. X-ray micro Laue diffraction tomography analysis of a solid oxide fuel cell

    OpenAIRE

    Ferreira Sanchez, D.; Villanova, J.; Laurencin, J.; Micha, J. S.; Montani, A.; Gergaud, P.; P. Bleuet

    2015-01-01

    International audience; The relevance of micro Laue diffraction tomography (mu-LT) to investigate heterogeneous polycrystalline materials has been studied. For this purpose, a multiphase solid oxide fuel cell (SOFC) electrode composite made of yttria-stabilized zirconia and nickel oxide phases, with grains of about a few micrometres in size, has been analyzed. In order to calibrate the Laue data and to test the technique's sensitivity limits, a monocrystalline germanium sample of about 8 x 4 ...

  17. Low-Temperature Oxidation of CO in Smoke: A Review

    Directory of Open Access Journals (Sweden)

    Dyakonov AJ

    2014-12-01

    Full Text Available The low-temperature catalytic oxidation of CO has been reviewed, targeting its possible application to cigarette smoke. The treatment of CO in smoke by using a filter-packed catalyst is extremely complicated by the presence of a variety of chemically active gaseous compounds, a particulate phase, the high velocity of pulsing smoke flow, and ambient temperature. The relevant mechanisms of catalysis and the catalyst preparation variables that could help to overcome these problems are considered. Possible contributors to the overall kinetics that must include variety of diffusion processes were briefly discussed. The chemisorption of O2, CO and CO2 on Pd, Pt and Au and on partially reducible supports, surface reactions and oscillations of the CO oxidation rate were analyzed. The effects of the surface structure and electronic properties of the catalyst support, preparation conditions and presence of a second transition metal on the projected CO oxidation activity of the catalysts in smoke are also discussed. The reviewed catalyst preparation approaches can solve the low-temperature catalyst activity problem. However, more work is required to stabilize this activity of an air-exposed catalyst to provide a necessary shelf life for a cigarette. The greatest challenge seems to be a particular phase - exclusive selectivity that would not contradict with the necessary fast diffusion of gases through the catalyst pores.

  18. Computer Simulations of Composite Electrodes in Solid-Oxide Fuel-Cells

    Energy Technology Data Exchange (ETDEWEB)

    Sunde, Svein

    1999-07-01

    aspects of structure and composition. The thesis is composed of the five papers: (A) Calculation of conductivity and polarization resistance of composite SOFC-electrodes from random resistor networks, (B) Monte Carlo Simulations of Conductivity of Composite Electrodes for Solid Oxide Fuel Cells, (C) Monte Carlo Simulations of the Polarization Resistance of Composite Electrodes for Solid Oxide Fuel Cells (D) Calculations of Impedance of Composite Modes for Solid Oxide Fuel Cells (E) Simulations of Composite Electrodes in Fuel Cells. The major results are: (1) A Monte Carlo method is constructed for electrochemical applications, (2) The Monte Carlo simulations of conductivity with respect to its dependence on composition and temperature are validated quantitatively with respect to experimental results (papers A, B and E), (3) The Monte Carlo method is validated qualitatively with respect polarisation resistance and its thickness dependence (papers A, C, and E), (Considerable scatter in the experimental results prevents a more strict quantitative evaluation of the model.), (4) A dependence of the percolation threshold on particle size in the composite is suggested as a major reason for electrode deactivation in fuel cells employing composite electrodes in which particle aggregation occur (paper B), (5) The range of compositions within which there will be a thickness dependence of the polarisation resistance is calculated as a function of relative ratio of particle radii (paper C), (6) The shapes of impedance-plane plots for composite electrodes will usually differ significantly from their point-contact counterparts exclusively for reasons related structure (paper D), (7) The macroscopic porous-electrode theory is adapted for composite electrodes (papers C and E), (8) A model for internal reforming of methane at a composite fuel-cell anode is formulated, based on the macroscopic porous-electrode theory (paper E). The model includes a description of gas-phase transport and non

  19. Influence of the starting materials on performance of high temperature oxide fuel cells devices

    Directory of Open Access Journals (Sweden)

    Emília Satoshi Miyamaru Seo

    2004-03-01

    Full Text Available High temperature solid oxide fuel cells (SOFCs offer an environmentally friendly technology to convert gaseous fuels such as hydrogen, natural gas or gasified coal into electricity at high efficiencies. Besides the efficiency, higher than those obtained from the traditional energy conversion systems, a fuel cell provides many other advantages like reliability, modularity, fuel flexibility and very low levels of NOx and SOx emissions. The high operating temperature (950-1000 °C used by the current generation of the solid oxide fuel cells imposes severe constraints on materials selection in order to improve the lifetime of the cell. Besides the good electrical, electrochemical, mechanical and thermal properties, the individual cell components must be stable under the fuel cell operating atmospheres. Each material has to perform not only in its own right but also in conjunction with other system components. For this reason, each cell component must fulfill several different criteria. This paper reviews the materials and the methods used to fabricate the different cell components, such as the cathode, the electrolyte, the anode and the interconnect. Some remarkable results, obtained at IPEN (Nuclear Energy Research Institute in São Paulo, have been presented.

  20. Kinetics of oxidation of H2 and reduction of H2O in Ni-YSZ based solid oxide cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2012-01-01

    Reduction of H2O and oxidation of H2 was studied in a Ni-YSZ electrode supported Solid Oxide Cells produced at DTU Energy conversion (former Risø DTU). Polarisation (i-V) and electrochemical impedance spectroscopic characterisation show that the kinetics for reduction of H 2O is slower compared...... to oxidation of H2. The kinetic differences cannot be explained by the reaction mechanisms which are similar in the two cases but are rather an effect of the thermodynamics. The preliminary analysis performed in this study show that the slow kinetic for reduction is partly related to the endothermic nature...... of the reaction, cooling the active electrode, thereby leading to slower kinetics at low current densities. Likewise, the increased kinetic for oxidation was found to be related to the exothermic nature of the reaction, heating the active electrode, and thereby leading to faster kinetics. At higher current...