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Sample records for reversible solid oxide

  1. Durability evaluation of reversible solid oxide cells

    Science.gov (United States)

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

    2013-11-01

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

  2. Potential of reversible solid oxide cells as electricity storage system

    OpenAIRE

    Di Giorgio, Paolo; Desideri, Umberto

    2016-01-01

    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 ...

  3. 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.

  4. Redox?Reversible Iron Orthovanadate Cathode for Solid Oxide Steam Electrolyzer

    OpenAIRE

    Gan, Lizhen; Ye, Lingting; Ruan, Cong; Chen, Shigang; Xie, Kui

    2015-01-01

    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.

  5. 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.

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

    KAUST Repository

    Bi, Lei; Boulfrad, Samir; Traversa, Enrico

    2015-01-01

    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

  7. Enhanced reversibility and durability of a solid oxide Fe-air redox battery by carbothermic reaction derived energy storage materials.

    Science.gov (United States)

    Zhao, Xuan; Li, Xue; Gong, Yunhui; Huang, Kevin

    2014-01-18

    The recently developed solid oxide metal-air redox battery is a new technology capable of high-rate chemistry. Here we report that the performance, reversibility and stability of a solid oxide iron-air redox battery can be significantly improved by nanostructuring energy storage materials from a carbothermic reaction.

  8. Final Technical Report, Oct 2004 - Nov. 2006, High Performance Flexible Reversible Solid Oxide Fuel Cell

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Jie; Minh, Nguyen

    2007-02-21

    This report summarizes the work performed for the program entitled “High Performance Flexible Reversible Solid Oxide Fuel Cell” under Cooperative Agreement DE-FC36-04GO14351 for the U. S. Department of Energy. The overall objective of this project is to demonstrate a single modular stack that generates electricity from a variety of fuels (hydrogen and other fuels such as biomass, distributed natural gas, etc.) and when operated in the reverse mode, produces hydrogen from steam. This project has evaluated and selected baseline cell materials, developed a set of materials for oxygen and hydrogen electrodes, and optimized electrode microstructures for reversible solid oxide fuel cells (RSOFCs); and demonstrated the feasibility and operation of a RSOFC multi-cell stack. A 10-cell reversible SOFC stack was operated over 1000 hours alternating between fuel cell (with hydrogen and methane as fuel) and steam electrolysis modes. The stack ran very successfully with high power density of 480 mW/cm2 at 0.7V and 80% fuel utilization in fuel cell mode and >6 SLPM hydrogen production in steam electrolysis mode using about 1.1 kW electrical power. The hydrogen generation is equivalent to a specific capability of 2.59 Nm3/m2 with electrical energy demand of 3 kWh/Nm3. The performance stability in electrolysis mode was improved vastly during the program with a degradation rate reduction from 8000 to 200 mohm-cm2/1000 hrs. This was accomplished by increasing the activity and improving microstructure of the oxygen electrode. Both cost estimate and technology assessment were conducted. Besides the flexibility running under both fuel cell mode and electrolysis mode, the reversible SOFC system has the potentials for low cost and high efficient hydrogen production through steam electrolysis. The cost for hydrogen production at large scale was estimated at ~$2.7/kg H2, comparing favorably with other electrolysis techology.

  9. Reversible solid oxide fuel cell for natural gas/renewable hybrid power generation systems

    Science.gov (United States)

    Luo, Yu; Shi, Yixiang; Zheng, Yi; Cai, Ningsheng

    2017-02-01

    Renewable energy (RE) is expected to be the major part of the future energy. Presently, the intermittence and fluctuation of RE lead to the limitation of its penetration. Reversible solid oxide fuel cell (RSOFC) as the energy storage device can effectively store the renewable energy and build a bidirectional connection with natural gas (NG). In this paper, the energy storage strategy was designed to improve the RE penetration and dynamic operation stability in a distributed system coupling wind generators, internal combustion engine, RSOFC and lithium-ion batteries. By compromising the relative deviation of power supply and demand, RE penetration, system efficiency and capacity requirement, the strategy that no more than 36% of the maximum wind power output is directly supplied to users and the other is stored by the combination of battery and reversible solid oxide fuel cell is optimal for the distributed system. In the case, the RE penetration reached 56.9% and the system efficiency reached 55.2%. The maximum relative deviation of power supply and demand is also lower than 4%, which is significantly superior to that in the wind curtailment case.

  10. Redox-reversible perovskite ferrite cathode for high temperature solid oxide steam electrolyser

    International Nuclear Information System (INIS)

    Li, Zhe; Li, Shisong; Tseng, Chung-Jen; Tao, Shanwen; Xie, Kui

    2017-01-01

    Highlights: • Redox reversible ferrite cathode is demonstrated for solid oxide electrolyser. • Promising electrical conductivity is obtained with Pr doping in hydrogen. • High performance of steam electrolysis is achieved with ferrite cathode. - Abstract: In this work, perovskite Sr 1−x Pr x FeO 3-δ (SPF) (x = 0.02, 0.04, 0.06, 0.08 and 0.10) are investigated and employed as solid oxide steam electrolyser cathode at 800 °C. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM) analysis together indicate that the Sr 1−x Pr x FeO 3-δ is redox reversible with a phase transition from cubic to orthorhombic structure in redox cycles. The doping of Pr in A site has remarkably enhanced the electronic conduction to 1.0–1.2 S cm −1 at intermediate temperatures in reducing atmosphere. Electrochemical measurements demonstrate that the polarization resistance with Sr 0.96 Pr 0.04 FeO 3-δ electrode shows the lowest values of 0.25 Ω cm 2 in symmetric cells in reducing atmosphere at 800 °C. Direct steam electrolysis with Sr 0.96 Pr 0.04 FeO 3-δ cathode shows a current density of 1.64 A cm −2 at 2.0 V when fed with 5%H 2 O/Ar. The hydrogen production rate reaches 4.73, 6.68, 8.35 and 10.23 mL min −1 cm −2 at 1.4, 1.6, 1.8, 2.0 V, respectively, while the highest Faraday efficiency is as high as 97.16% at 1.8 V.

  11. Computational analysis on the electrode geometric parameters for the reversible solid oxide cells

    International Nuclear Information System (INIS)

    Lee, Seoung-Ju; Jung, Chi-Young; Yi, Sung-Chul

    2017-01-01

    Increasing global energy demands have been accelerating the research and development of reversible electrochemical systems that can realize an efficient use of the intermittent renewable energy resources. This paper thus describes a numerical investigation of reversible solid oxide cells (RSOCs), for their high energy efficiency delivered from the high operating temperatures ranging from 600 to 1000 °C. Unlike the previous studies, a model-based strategy is applied for the simultaneous integration of different operating modes (namely, fuel cell and electrolysis cell modes) to enable more realistic predictions on the trade-off behavior of the effects of electrode design parameters on the cell performance. This approach was taken to investigate the effects of various geometric designs and operating parameters (electrode backing layer thickness; interconnector rib size; fuel gas composition) on the current-potential characteristic and the round-trip efficiency. The cell performance was significantly affected by the rib size, particularly when the backing layer was thin, because of the uneven distribution of the reactant species. Overall, this study provides insights into key geometric design parameters that dominate the performance of dual-mode RSOCs.

  12. Stability and Performance of Oxygen Electrodes for Reversible Solid Oxide Cells

    Science.gov (United States)

    Railsback, Justin Gary

    Worldwide, governments are beginning to take action to reduce anthropogenic CO2 emissions in order to mitigate the extent of global climate change. The largest fraction of global CO2 emission comes from electrical power generation, which is rapidly being converted to wind and solar installations. The intermittent nature of renewable resources requires that large scale energy storage be implemented to ensure grid stability. Pumped hydro storage is currently the only technology available for large scale energy storage; however, pumped hydro remains geographically confined and susceptible to seasonal fluctuations and offers limited discharge hours. Recent system level models predict that reversible solid oxide cells may be a competitive solution, but two key advancements are required to realize the technology: low cell resistance (cell resistance, and when a cell is operated in electrolysis the oxygen electrode is known to degrade quickly. This work focuses on both aspects of the oxygen electrode. A Pr2NiO4 based electrode is developed that has improved phase stability and good polarization resistance ( 0.1 O•cm2 at 650 °C). The electrode is prepared by wet chemical impregnation (infiltration) of Pr2NiO4 precursors into a La0.9Sr 0.1Ga0.8Mg0.2O3 scaffold. Electrochemical data for a number cells is presented and the number of infiltrations is optimized. Preliminary life tests and x-ray data are presented. Pressurization of the oxygen electrode is predicted to decrease its polarization resistance and pressurization of the reversible solid oxide cell system is desirable to achieve high round-trip efficiency. The electrochemical performance of mixed electronic-ionic conducting electrodes has not been reported above 1 atm. Four candidate electrodes are examined under pressurization up to 10 atm: Pr2NiO4 infiltrated La0.9Sr0.1 Ga0.8Mg0.2O3, Sm0.5Sr 0.5CoO3 infiltrated Ce0.9Gd0.1O 2, single phase La0.6Sr0.4Co0.2Fe 0.8O3, and single phase Nd2NiO4. The role of the ion

  13. Novel electrical energy storage system based on reversible solid oxide cells: System design and operating conditions

    Science.gov (United States)

    Wendel, C. H.; Kazempoor, P.; Braun, R. J.

    2015-02-01

    Electrical energy storage (EES) is an important component of the future electric grid. Given that no other widely available technology meets all the EES requirements, reversible (or regenerative) solid oxide cells (ReSOCs) working in both fuel cell (power producing) and electrolysis (fuel producing) modes are envisioned as a technology capable of providing highly efficient and cost-effective EES. However, there are still many challenges and questions from cell materials development to system level operation of ReSOCs that should be addressed before widespread application. This paper presents a novel system based on ReSOCs that employ a thermal management strategy of promoting exothermic methanation within the ReSOC cell-stack to provide thermal energy for the endothermic steam/CO2 electrolysis reactions during charging mode (fuel producing). This approach also serves to enhance the energy density of the stored gases. Modeling and parametric analysis of an energy storage concept is performed using a physically based ReSOC stack model coupled with thermodynamic system component models. Results indicate that roundtrip efficiencies greater than 70% can be achieved at intermediate stack temperature (680 °C) and elevated stack pressure (20 bar). The optimal operating condition arises from a tradeoff between stack efficiency and auxiliary power requirements from balance of plant hardware.

  14. New, Efficient, and Reliable Air Electrode Material for Proton-Conducting Reversible Solid Oxide Cells.

    Science.gov (United States)

    Huan, Daoming; Shi, Nai; Zhang, Lu; Tan, Wenzhou; Xie, Yun; Wang, Wanhua; Xia, Changrong; Peng, Ranran; Lu, Yalin

    2018-01-17

    Driven by the demand to minimize fluctuation in common renewable energies, reversible solid oxide cells (RSOCs) have drawn increasing attention for they can operate either as fuel cells to produce electricity or as electrolysis cells to store electricity. Unfortunately, development of proton-conducting RSOCs (P-RSOCs) faces a major challenge of poor reliability because of the high content of steam involved in air electrode reactions, which could seriously decay the lifetime of air electrode materials. In this work, a very stable and efficient air electrode, SrEu 2 Fe 1.8 Co 0.2 O 7-δ (SEFC) with layer structure, is designed and deployed in P-RSOCs. X-ray diffraction analysis and High-angle annular dark-filed scanning transmission electron microscopy images of SEFC reveal that Sr atoms occupy the center of perovskite slabs, whereas Eu atoms arrange orderly in the rock-salt layer. Such a special structure of SEFC largely depresses its Lewis basicity and therefore its reactivity with steam. Applying the SEFC air electrode, our button switches smoothly between both fuel cell and electrolysis cell (EC) modes with no obvious degradation over a 135 h long-term test under wet H 2 (∼3% H 2 O) and 10% H 2 O-air atmospheres. A record of over 230 h is achieved in the long-term stability test in the EC mode, doubling the longest test that had been previously reported. Besides good stability, SEFC demonstrates great catalytic activity toward air electrode reactions when compared with traditional La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ air electrodes. This research highlights the potential of stable and efficient P-RSOCs as an important part in a sustainable new energy power system.

  15. Improving the Efficiency and Durability of Reversible Solid Oxide Cells for Energy Storage

    Science.gov (United States)

    Hughes, Gareth Allen

    This thesis presents research on the use of solid oxide cells (SOCs) as energy storage devices, and covers methods to improve their efficiency and durability for this use. It specifically covers two main topics: the durability of the oxygen electrode under forced alternating current, and the effect of pressurization on various oxygen electrode materials. Additionally, research was completed on thermodynamic modeling of a pressurized SOC energy storage system, and a new experimental testing apparatus was constructed to enable investigation of SOC samples operating under pressure. Forced alternating current using a symmetric sample structure was used to simulate the operation of a reversible SOC, effectively isolating the measurement of the performance response of the oxygen electrode. Cells consisting of La 0.8Sr0.2MnO3-delta - 8mol% Y2O 3-stabilized ZrO2 (LSM-YSZ) oxygen electrodes on YSZ electrolytes were tested. Early testing utilizing Ag current collectors showed that forced currents and the elevated operating temperature of SOCs cause silver to vaporize and deposit at the active region of the electrode. To avoid this artifact, a new test setup utilizing LSM current collectors was created. It was found that a shorter current cycling time of 1 hour helps prevent degradation compared to 12 hour cycles. Additionally, both cycling times showed improvement compared cells operated with dc current. Further study showed that operating at current densities of 0.8 A/cm2 and below can prevent degradation entirely. Pressurization of oxygen electrodes showed, as expected, that polarization resistance decreases with increasing oxygen pressure. The materials tested were LSM-YSZ and La0.6Sr0.4Fe0.8Co0.2 O3-d - Ce0.8Gd0.2O1.95 (LSCF-GDC), both in single-phase and composite electrode structures. Additionally, LSM-infiltrated YSZ was tested. The resistance typically decreased following power-law behavior with exponents ranging from -0.17 to -0.30, with similar trends found in all

  16. Correction: Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Graves, Christopher R.; Mogensen, Mogens Bjerg

    2017-01-01

    Correction for ‘Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4’ by S. H. Jensen et al., Energy Environ. Sci., 2015, 8, 2471–2479.......Correction for ‘Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4’ by S. H. Jensen et al., Energy Environ. Sci., 2015, 8, 2471–2479....

  17. 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...

  18. Reversing and Repairing Microstructure Degradation in Solid Oxide Cells During Operation

    DEFF Research Database (Denmark)

    Graves, Christopher R.

    2013-01-01

    density by reversible battery-like operation, cycling between electrolysis mode and fuel-cell mode. Also reported are new examples of beneficial effects of (2) redox cycling, (3) exsolution of nano-catalysts, and (4) high cathodic polarization, all of which can be used to maintain or even improve...

  19. A thermodynamic approach for selecting operating conditions in the design of reversible solid oxide cell energy systems

    Science.gov (United States)

    Wendel, Christopher H.; Kazempoor, Pejman; Braun, Robert J.

    2016-01-01

    Reversible solid oxide cell (ReSOC) systems are being increasingly considered for electrical energy storage, although much work remains before they can be realized, including cell materials development and system design optimization. These systems store electricity by generating a synthetic fuel in electrolysis mode and subsequently recover electricity by electrochemically oxidizing the stored fuel in fuel cell mode. System thermal management is improved by promoting methane synthesis internal to the ReSOC stack. Within this strategy, the cell-stack operating conditions are highly impactful on system performance and optimizing these parameters to suit both operating modes is critical to achieving high roundtrip efficiency. Preliminary analysis shows the thermoneutral voltage to be a useful parameter for analyzing ReSOC systems and the focus of this study is to quantitatively examine how it is affected by ReSOC operating conditions. The results reveal that the thermoneutral voltage is generally reduced by increased pressure, and reductions in temperature, fuel utilization, and hydrogen-to-carbon ratio. Based on the thermodynamic analysis, many different combinations of these operating conditions are expected to promote efficient energy storage. Pressurized systems can achieve high efficiency at higher temperature and fuel utilization, while non-pressurized systems may require lower stack temperature and suffer from reduced energy density.

  20. Investigation of the Reversible Lithiation of an Oxide Free Aluminum Anode by a LiBH4 Solid State Electrolyte

    Directory of Open Access Journals (Sweden)

    Jason A. Weeks

    2017-11-01

    Full Text Available In this study, we analyze and compare the physical and electrochemical properties of an all solid-state cell utilizing LiBH4 as the electrolyte and aluminum as the active anode material. The system was characterized by galvanostatic lithiation/delithiation, cyclic voltammetry (CV, X-ray diffraction (XRD, energy dispersive X-ray spectroscopy (EDS, Raman spectroscopy, electrochemical impedance spectroscopy (EIS, and scanning electron microscopy (SEM. Constant current cycling demonstrated that the aluminum anode can be reversibly lithiated over multiple cycles utilizing a solid-state electrolyte. An initial capacity of 895 mAh/g was observed and is close to the theoretical capacity of aluminum. Cyclic voltammetry of the cell was consistent with the constant current cycling data and showed that the reversible lithiation/delithiation of aluminum occurs at 0.32 V and 0.38 V (vs. Li+/Li respectively. XRD of the aluminum anode in the initial and lithiated state clearly showed the formation of a LiAl (1:1 alloy. SEM-EDS was utilized to examine the morphological changes that occur within the electrode during cycling. This work is the first example of reversible lithiation of aluminum in a solid-state cell and further emphasizes the robust nature of the LiBH4 electrolyte. This demonstrates the possibility of utilizing other high capacity anode materials with a LiBH4 based solid electrolyte in all-solid-state batteries.

  1. Process modeling of a reversible solid oxide cell (r-SOC) energy storage system utilizing commercially available SOC reactor

    International Nuclear Information System (INIS)

    Mottaghizadeh, Pegah; Santhanam, Srikanth; Heddrich, Marc P.; Friedrich, K. Andreas; Rinaldi, Fabio

    2017-01-01

    Highlights: • An electric energy storage system was developed based on a commercially available SOC reactor. • Heat generated in SOFC mode of r-SOC is utilized in SOEC operation of r-SOC using latent heat storage. • A round trip efficiency of 54.3% was reached for the reference system at atmospheric pressure. • An improved process system design achieved a round-trip efficiency of 60.4% at 25 bar. - Abstract: The increase of intermittent renewable energy contribution in power grids has urged us to seek means for temporal decoupling of electricity production and consumption. A reversible solid oxide cell (r-SOC) enables storage of surplus electricity through electrochemical reactions when it is in electrolysis mode. The reserved energy in form of chemical compounds is then converted to electricity when the cell operates as a fuel cell. A process system model was implemented using Aspen Plus® V8.8 based on a commercially available r-SOC reactor experimentally characterized at DLR. In this study a complete self-sustaining system configuration is designed by optimal thermal integration and balance of plant. Under reference conditions a round trip efficiency of 54.3% was achieved. Generated heat in fuel cell mode is exploited by latent heat storage tanks to enable endothermic operation of reactor in its electrolysis mode. In total, out of 100 units of thermal energy stored in heat storage tanks during fuel cell mode, 90% was utilized to offset heat demand of system in its electrolysis mode. Parametric analysis revealed the significance of heat storage tanks in thermal management even when reactor entered its exothermic mode of electrolysis. An improved process system design demonstrates a system round-trip efficiency of 60.4% at 25 bar.

  2. Effect of reverse Boudouard reaction catalyst on the performance of solid oxide carbon fuel cells integrated with a dry gasifier

    International Nuclear Information System (INIS)

    Kim, Sun-Kyung; Mehran, Muhammad Taqi; Mushtaq, Usman; Lim, Tak-Hyoung; Lee, Jong-Won; Lee, Seung-Bok; Park, Seok-Joo; Song, Rak-Hyun

    2016-01-01

    Highlights: • The addition of K_2CO_3 catalyst in carbon fuel improves the performance of SO-CFC. • Thermal and electrochemical analyses done to elucidate the catalytic enhancement. • Material characterization of SO-CFC performed after long-term degradation test. - Abstract: A solid oxide carbon fuel cell (SO-CFC) integrated with a dry gasifier was operated on activated carbon fuel and the effect of adding a reverse Boudouard gasification catalyst on the performance and long-term operation characteristics of the SO-CFC was investigated. The reactivity of the carbon fuels for the Boudouard gasification reaction was analyzed by a thermal analysis at various operating conditions. The SO-CFC was then operated on gasified fuel gas consisting of CO_2 and CO obtained from the integrated dry gasifier. The SO-CFC operated on activated carbon fuel with 5 wt.% K_2CO_3 achieved a maximum power density of 202, 262, and 271 mW/cm"2 at 750, 800, and 850 °C, respectively; the SO-CFC fueled with activated carbon fuel without a catalyst meanwhile yielded maximum power density of 168 mW/cm"2 at 850 °C. By using electrochemical impedance spectroscopy, the effect of adding the catalyst on the gasification products and subsequently on the performance of the SO-CFC was studied. A long-term degradation test was conducted by continuously operating the SO-CFC at 50 mA/cm"2 for 518 h at 750 °C. During the long-term degradation test, the average degradation rate of the SO-CFC was found to be 183 mV/kh. The post-mortem SEM and XRD analyses of the SO-CFC after the long-term test revealed the presence of carbon deposits and oxidation of Ni at the anode, causing a relatively higher degree of degradation in the SO-CFC integrated with the dry gasifier during the long-term operation. The addition of the K_2CO_3 based dry gasification catalyst significantly enhances the performance of the SO-CFC integrated with dry gasification, but during long-term operation, the degradation rate is found

  3. 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.

  4. Solid phase synthesis of mitochondrial triphenylphosphonium-vitamin E metabolite using a lysine linker for reversal of oxidative stress.

    Directory of Open Access Journals (Sweden)

    Mohanad Mossalam

    Full Text Available Mitochondrial targeting of antioxidants has been an area of interest due to the mitochondria's role in producing and metabolizing reactive oxygen species. Antioxidants, especially vitamin E (α-tocopherol, have been conjugated to lipophilic cations to increase their mitochondrial targeting. Synthetic vitamin E analogues have also been produced as an alternative to α-tocopherol. In this paper, we investigated the mitochondrial targeting of a vitamin E metabolite, 2,5,7,8-tetramethyl-2-(2'-carboxyethyl-6-hydroxychroman (α-CEHC, which is similar in structure to vitamin E analogues. We report a fast and efficient method to conjugate the water-soluble metabolite, α-CEHC, to triphenylphosphonium cation via a lysine linker using solid phase synthesis. The efficacy of the final product (MitoCEHC to lower oxidative stress was tested in bovine aortic endothelial cells. In addition the ability of MitoCEHC to target the mitochondria was examined in type 2 diabetes db/db mice. The results showed mitochondrial accumulation in vivo and oxidative stress decrease in vitro.

  5. 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.

  6. Synthesis and characterization of a Sr0.95Y0.05TiO3-δ-based hydrogen electrode for reversible solid oxide cells

    KAUST Repository

    Ling, Yihan

    2015-01-01

    Reversible solid oxide cells (RSOCs) can generate electricity as solid oxide fuel cells (SOFC) facing a shortage of electricity and can also store the electricity as solid oxide electrolysis cells (SOEC) at the time of excessive electricity. The composite Sr0.95Y0.05TiO3-δ-Sm0.2Ce0.8O1.9 (SYT-SDC) as the hydrogen electrode provides a promising alternative for a conventional Ni/YSZ. The possible charge compensation mechanism of SYT is described as Sr0.95Y0.05Ti0.95-2δ 4+Ti2δ+0.05 3+O3-δ. The Ti3+ is approximately 11.73% in the reduced SYT by XRD Rietveld refinement, electron paramagnetic resonance (EPR) and thermogravimetry (TG) analysis. Voltage-current curves and impedance spectra are measured as a function of applied voltages to characterize the cells. The bulk resistance (Ro) and the electrode polarization resistance (Rp) at open circuit voltages (OCV) at 750 °C are 9.06 Ω cm2 and 10.57 Ω cm2, respectively. The Ro values have a small amount of changes with small slopes both in the SOFC (-0.29 Ω cm2 V-1) and SOEC mode (0.5 Ω cm2 V-1), whereas the Rp values decrease all the time with the increasing voltages at both the SOFC (-2.59 Ω cm2 V-1) and SOEC mode (-9.65 Ω cm2 V-1), indicating that the electrical conductivity and electro-catalytic property of the SYT-based hydrogen electrode can be improved under the SOEC mode. This journal is

  7. Preparation of functional layers for anode-supported solid oxide fuel cells by the reverse roll coating process

    Science.gov (United States)

    Mücke, R.; Büchler, O.; Bram, M.; Leonide, A.; Ivers-Tiffée, E.; Buchkremer, H. P.

    The roll coating technique represents a novel method for applying functional layers to solid oxide fuel cells (SOFCs). This fast process is already used for mass production in other branches of industry and offers a high degree of automation. It was utilized for coating specially developed anode (NiO + 8YSZ, 8YSZ: 8 mol% yttria-stabilized zirconia) and electrolyte (8YSZ) suspensions on green and pre-sintered tape-cast anode supports (NiO + 8YSZ). The layers formed were co-fired in a single step at 1400 °C for 5 h. As a result, the electrolyte exhibited a thickness of 14-18 μm and sufficient gas tightness. Complete cells with a screen-printed and sintered La 0.65Sr 0.3MnO 3- δ (LSM)/8YSZ cathode yielded a current density of 0.9-1.1 A cm -2 at 800 °C and 0.7 V, which is lower than the performance of non-co-fired slip-cast or screen-printed Jülich standard cells with thinner anode and electrolyte layers. The contribution of the cell components to the total area-specific resistance (ASR) was calculated by analyzing the distribution function of the relaxation times (DRTs) of measured electrochemical impedance spectra (EIS) and indicates the potential improvement in the cell performance achievable by reducing the thickness of the roll-coated layers. The results show that the anode-supported planar half-cells can be fabricated cost-effectively by combining roll coating with subsequent co-firing.

  8. Multi-objective optimization of a pressurized solid oxide fuel cell – gas turbine hybrid system integrated with seawater reverse osmosis

    International Nuclear Information System (INIS)

    Eveloy, Valerie; Rodgers, Peter; Al Alili, Ali

    2017-01-01

    To improve the capacity and efficiency of distributed power and fresh water generation in coastal industrial facilities affected by regional water scarcity, a natural gas-fueled, pressurized solid oxide fuel cell-gas turbine (SOFC-GT) hybrid is integrated with a bottoming organic Rankine cycle (ORC) and seawater reverse osmosis (RO) desalination plant. This power and water co-generation system is optimized in terms of two objectives, maximum exergy efficiency and minimum cost rate, using a genetic algorithm. The exergetic and economic performance of three solutions representing maximum exergy efficiency, minimum cost rate, and a compromise between efficiency and cost rate, are compared. When imposing a water production requirement (reference case), the selected compromise multi-objective optimization solution delivers a net power output of 2.4 MWe and 636 m"3/day of permeate, at a co-generation exergy efficiency and cost rate of 71.3% and 0.0256 USD/s, respectively. The system payback time is estimated to be less than six years for typical economic parameters, but would become unprofitable in the most unfavorable economic scenario considered. Overall, the results indicate the thermodynamic and economic benefits of reverse osmosis over thermal desalination processes for integration with high-efficiency power generation systems in coastal regions impacted by domestic gas shortages and water scarcity. - Highlights: • Integration of a pressurized SOFC-GT hybrid system with a reverse osmosis unit. • Multi-objective, exergetic and economic optimization using a genetic algorithm. • Optimum solution delivers 2.4 MWe and 636 m"3/day of desalinated water. • Overall exergy efficiency and cost rate of 71.3% and 0.0256 USD/s, respectively. • System payback time estimated at less than six years for typical economic conditions.

  9. Reversible Operation of Solid Oxide Cells for Sustainable Fuel Production and Solar/Wind Load-Balancing

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Villarreal, D.; Mýrdal, Jón Steinar Garðarsson

    2016-01-01

    with focus onfundamentals or applications of bi-directional operation. This presentation will highlight ourrecent developments in applying reversible SOCs (RSOCs) for renewable energy storagewith respect to cell and stack testing, cell and system design, and techno-economicanalysis.At the cell level, long...... exceeds the wind power supply.At the system level, techno-economic analyses and system designs for different scalesand applications have been realized. A simulation of an RSOC system that uses real-worldtime-series market prices for electricity and natural gas in Denmark to decide when tooperate...... in electrolysis mode (buying electricity and selling methane) or fuel-cell mode(buying gas and selling electricity) shows the advantage of a reversible system and thechanging operating profile as the fraction of wind power supply grows. Finally, we discussthe potential for systems with novel chemistries...

  10. 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...

  11. 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

  12. 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...

  13. Solid Oxide Fuel Cell Experimental Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s Solid Oxide Fuel Cell Experimental Laboratory in Morgantown, WV, gives researchers access to models and simulations that predict how solid oxide fuel cells...

  14. 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...... that not all degradation mechanisms are fully understood. Traditionally, cell degradation has been attributed to the materials, processing and cell operating conditions. More recently, focus has been placed on the effect of raw material and gas impurities and their long-term effect on cell degradation. Minor...... impurities have been found to play a significant role in degradation and in some cases can overshadow the cell operation condition related degradation phenomenon. In this review, several degradation diagnostic tools are discussed, a benchmark for a desirable degradation rate is proposed and degradation...

  15. Impedance Spectra of Activating/Passivating Solid Oxide Electrodes

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Sun, Xiufu; Koch, Søren

    2014-01-01

    The aim of this paper is to show that the inductive arcs seen in electrochemical impedance spectra of solid oxide cells (SOCs) are real electrochemical features that in several cases can be qualitatively explained by passivation/activation processes. Several degradation processes of Solid Oxide...... Fuel Cells (SOFC) and Electrolyser Cells (SOEC) exist. Not all of them are irreversible, especially not over short periods. A reversible degradation is termed “passivation” and the reverse is then “activation”. These processes may exhibit themselves in the Electrochemical Impedance Spectra (EIS...

  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. In Situ Insight into Reversible O2 Gas-Solid Reactions

    DEFF Research Database (Denmark)

    Wegeberg, Christina

    2016-01-01

    Non-porous crystalline solids containing a series of cationic tetracobalt complexes reversibly, selectively and stoichiometrically chemisorb dioxygen in temperature/O2 partial pressure induced processes involving the oxidation of cobalt with concurrent reduction of two equivalents of sorbed O2 to...

  18. 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.

  19. Solid oxide fuel cells fueled with reducible oxides

    Science.gov (United States)

    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.

  20. Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials

    KAUST Repository

    Mutoro, Eva

    2012-01-05

    Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically/ionically conducting, and thus, they have been used in a number of solid-state devices such as solid oxide fuel cells (SOFCs) and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface compositions is crucial to enhance device performance. In this study, we demonstrate that the surface strontium (Sr) and cobalt (Co) concentrations of perovskite-based thin films can be controlled reversibly at elevated temperatures by applying small electrical potential biases. The surface compositional changes of La 0.8Sr 0.2CoO 3-δ (LSC 113), (La 0.5Sr 0.5) 2CoO 4±δ (LSC 214), and LSC 214-decorated LSC 113 films (LSC 113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr were found for the LSC 113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites. © 2011 American Chemical Society.

  1. Electrode Kinetics and Gas Conversion in Solid Oxide Cells

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude

    The solid oxide fuel cell (SOFC) converts hydrogen, carbon monoxide and hydrocarbon fuels (directly) into electricity with very high efficiencies and has demonstrated almost comparable performance when operated in reverse mode as a solid oxide electrolysis cell (SOEC). In this case electrical (and...... thermal) energy is stored as chemical energy of reaction products. To this end, the cells are fed with steam (H2O electrolysis), carbon dioxide (CO2 electrolysis) or a mixture of both (H2O/CO2 co-electrolysis) and of course electrical (ΔG) and thermal (TΔS) energies for the splitting of reactant compounds...... of the solid oxide cell (SOC) and independent of polarization mode (fuel cell mode or electrolysis mode), the current flowing through the cell is limited by processes such as adsorption and desorption of reactants or products, diffusion through the porous electrodes, activation or charge transfer...

  2. Electrolytes for solid oxide fuel cells

    Science.gov (United States)

    Fergus, Jeffrey W.

    The high operating temperature of solid oxide fuel cells (SOFCs), as compared to polymer electrolyte membrane fuel cells (PEMFCs), improves tolerance to impurities in the fuel, but also creates challenges in the development of suitable materials for the various fuel cell components. In response to these challenges, intermediate temperature solid oxide fuel cells (IT-SOFCs) are being developed to reduce high-temperature material requirements, which will extend useful lifetime, improve durability and reduce cost, while maintaining good fuel flexibility. A major challenge in reducing the operating temperature of SOFCs is the development of solid electrolyte materials with sufficient conductivity to maintain acceptably low ohmic losses during operation. In this paper, solid electrolytes being developed for solid oxide fuel cells, including zirconia-, ceria- and lanthanum gallate-based materials, are reviewed and compared. The focus is on the conductivity, but other issues, such as compatibility with electrode materials, are also discussed.

  3. Electrolytes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Fergus, Jeffrey W. [Auburn University, Materials Research and Education Center, 275 Wilmore Laboratories, Auburn, AL 36849 (United States)

    2006-11-08

    The high operating temperature of solid oxide fuel cells (SOFCs), as compared to polymer electrolyte membrane fuel cells (PEMFCs), improves tolerance to impurities in the fuel, but also creates challenges in the development of suitable materials for the various fuel cell components. In response to these challenges, intermediate temperature solid oxide fuel cells (IT-SOFCs) are being developed to reduce high-temperature material requirements, which will extend useful lifetime, improve durability and reduce cost, while maintaining good fuel flexibility. A major challenge in reducing the operating temperature of SOFCs is the development of solid electrolyte materials with sufficient conductivity to maintain acceptably low ohmic losses during operation. In this paper, solid electrolytes being developed for solid oxide fuel cells, including zirconia-, ceria- and lanthanum gallate-based materials, are reviewed and compared. The focus is on the conductivity, but other issues, such as compatibility with electrode materials, are also discussed. (author)

  4. Solid oxide fuel cells and hydrogen production

    International Nuclear Information System (INIS)

    Dogan, F.

    2009-01-01

    'Full text': A single-chamber solid oxide fuel cell (SC-SOFC), operating in a mixture of fuel and oxidant gases, provides several advantages over the conventional SOFC such as simplified cell structure (no sealing required). SC-SOFC allows using a variety of fuels without carbon deposition by selecting appropriate electrode materials and cell operating conditions. The operating conditions of single chamber SOFC was studied using hydrocarbon-air gas mixtures for a cell composed of NiO-YSZ / YSZ / LSCF-Ag. The cell performance and catalytic activity of the anode was measured at various gas flow rates. The results showed that the open-circuit voltage and the power density increased as the gas flow rate increased. Relatively high power densities up to 660 mW/cm 2 were obtained in a SC-SOFC using porous YSZ electrolytes instead of dense electrolytes required for operation of a double chamber SOFC. In addition to propane- or methane-air mixtures as a fuel source, the cells were also tested in a double chamber configuration using hydrogen-air mixtures by controlling the hydrogen/air ratio at the cathode and the anode. Simulation of single chamber conditions in double chamber configurations allows distinguishing and better understanding of the electrode reactions in the presence of mixed gases. Recent research efforts; the effect of hydrogen-air mixtures as a fuel source on the performance of anode and cathode materials in single-chamber and double-chamber SOFC configurations,will be presented. The presentation will address a review on hydrogen production by utilizing of reversible SOFC systems. (author)

  5. The TMI Regenerative Solid Oxide Fuel Cell

    Science.gov (United States)

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

    1996-01-01

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

  6. 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......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 slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance...... bituminous coal (73 mW/cm2). © 2015 ECS - The Electrochemical Society...

  7. 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......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 slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance...... bituminous coal (73 mW/cm2)....

  8. 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...

  9. 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.

  10. 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...

  11. Exceptional Durability of Solid Oxide Cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune; Mogensen, Mogens Bjerg

    2010-01-01

    Extensive efforts to resolve the degradation normally associated with solid oxide electrolysis cells (SOECs) have been conducted during the past decade. To date, the degradation is assumed to be caused by adsorption of impurities in the cathode, although no firm evidence for this degradation...

  12. Towards solid oxide electrolysis plants in 2020

    DEFF Research Database (Denmark)

    Chen, Ming; Blennow, Peter; Mathiesen, Brian Vad

    The goal of the project is to further improve performance and durability of solid oxide electrolysis cells (SOECs) and stacks targeting applications specifically for regulating the future Danish power system with a high amount of fluctuating renewable energies, and at the same time enhance the co...

  13. Liquid flow along a solid surface reversibly alters interfacial chemistry.

    Science.gov (United States)

    Lis, Dan; Backus, Ellen H G; Hunger, Johannes; Parekh, Sapun H; Bonn, Mischa

    2014-06-06

    In nature, aqueous solutions often move collectively along solid surfaces (for example, raindrops falling on the ground and rivers flowing through riverbeds). However, the influence of such motion on water-surface interfacial chemistry is unclear. In this work, we combine surface-specific sum frequency generation spectroscopy and microfluidics to show that at immersed calcium fluoride and fused silica surfaces, flow leads to a reversible modification of the surface charge and subsequent realignment of the interfacial water molecules. Obtaining equivalent effects under static conditions requires a substantial change in bulk solution pH (up to 2 pH units), demonstrating the coupling between flow and chemistry. These marked flow-induced variations in interfacial chemistry should substantially affect our understanding and modeling of chemical processes at immersed surfaces. Copyright © 2014, American Association for the Advancement of Science.

  14. Effect of samaria-doped ceria (SDC) interlayer on the performance of La0.6Sr0.4Co0.2Fe0.8O3-δ/SDC composite oxygen electrode for reversible solid oxide fuel cells

    International Nuclear Information System (INIS)

    Shimura, Kazuki; Nishino, Hanako; Kakinuma, Katsuyoshi; Brito, Manuel E.; Uchida, Hiroyuki

    2017-01-01

    In order to establish clear criteria for designing highly active and highly durable oxygen electrode for reversible solid oxide fuel cells, we have focused on the effect of samaria-doped ceria (SDC) interlayers prepared on YSZ solid electrolyte surface on the performances of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF)-SDC composite oxygen electrode. Symmetrical cells with the configuration, LSCF-SDC|SDC interlayer|YSZ|SDC interlayer|LSCF-SDC, were constructed. We prepared two kinds of SDC interlayers, one from a mixed solution of cerium 2-ethylhexanoate (denoted as octoate) and samarium octoates (o-interlayer) and another from a mixed solution of cerium and samarium nitrates (n-interlayer). The LSCF-SDC electrodes with o-interlayer and n-interlayer exhibited very similar performances in both the anodic and cathodic reactions at 900 °C. When temperature was decreased to 800 °C, an increase in overpotentials was observed. However, the LSCF-SDC electrode with o-interlayer exhibited superior performance to that with n-interlayer. It was found that the entire surface of the YSZ electrolyte disk was well covered with a dense o-interlayer of uniform thickness. Such an interlayer enables uniform transport of oxide ions to and from the LSCF-SDC electrode, resulting in an enlarged effective reaction zone (ERZ). The I-E performance of the LSCF-SDC|o-interlayer|YSZ cell was found to be comparable to that of the identical electrode prepared on a dense SDC sintered electrolyte disk (as a reference). This observation supports our views regarding the essential role of a dense interlayer with uniform thickness in enhancing the performance of reversible solid oxide cells.

  15. 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...... the Ni surfaces to other metals of interest. This allows the reactivity over the different metals to be understood in terms of two reactivity descriptors, namely, the carbon and oxygen adsorption energies. By combining a simple free-energy analysis with microkinetic modeling, activity landscapes of anode...

  16. 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.

  17. 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.

  18. Effect of Reverse Bias Stress on Leakage Currents and Breakdown Voltages of Solid Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2011-01-01

    The majority of solid tantalum capacitors are produced by high-temperature sintering of a fine tantalum powder around a tantalum wire followed by electrolytic anodization that forms a thin amorphous Ta2O5 dielectric layer and pyrolysis of manganese nitrite on the oxide to create a conductive manganese dioxide electrode. A contact to tantalum wire is used as anode terminal and to the manganese layer as a cathode terminal of the device. This process results in formation of an asymmetric Ta -- Ta2O5 -- MnO2 capacitor that has different characteristics at forward (positive bias applied to tantalum) and reverse (positive bias applied to manganese cathode) voltages. Reverse bias currents might be several orders of magnitude larger than forward leakage currents so I-V characteristics of tantalum capacitors resemble characteristics of semiconductor rectifiers. Asymmetric I-V characteristics of Ta -- anodic Ta2O5 systems have been observed at different top electrode materials including metals, electrolytes, conductive polymers, and manganese oxide thus indicating that this phenomenon is likely related to the specifics of the Ta -- Ta2O5 interface. There have been multiple attempts to explain rectifying characteristics of capacitors employing anodic tantalum pentoxide dielectrics. A brief review of works related to reverse bias (RB) behavior of tantalum capacitors shows that the mechanism of conduction in Ta -- Ta2O5 systems is still not clear and more testing and analysis is necessary to understand the processes involved. If tantalum capacitors behave just as rectifiers, then the assessment of the safe reverse bias operating conditions would be a relatively simple task. Unfortunately, these parts can degrade with time under reverse bias significantly, and this further complicates analysis of the I-V characteristics and establishing safe operating areas of the parts. On other hand, time dependence of reverse currents might provide additional information for investigation of

  19. Biotin Switch Assays for Quantitation of Reversible Cysteine Oxidation.

    Science.gov (United States)

    Li, R; Kast, J

    2017-01-01

    Thiol groups in protein cysteine residues can be subjected to different oxidative modifications by reactive oxygen/nitrogen species. Reversible cysteine oxidation, including S-nitrosylation, S-sulfenylation, S-glutathionylation, and disulfide formation, modulate multiple biological functions, such as enzyme catalysis, antioxidant, and other signaling pathways. However, the biological relevance of reversible cysteine oxidation is typically underestimated, in part due to the low abundance and high reactivity of some of these modifications, and the lack of methods to enrich and quantify them. To facilitate future research efforts, this chapter describes detailed procedures to target the different modifications using mass spectrometry-based biotin switch assays. By switching the modification of interest to a biotin moiety, these assays leverage the high affinity between biotin and avidin to enrich the modification. The use of stable isotope labeling and a range of selective reducing agents facilitate the quantitation of individual as well as total reversible cysteine oxidation. The biotin switch assay has been widely applied to the quantitative analysis of S-nitrosylation in different disease models and is now also emerging as a valuable research tool for other oxidative cysteine modifications, highlighting its relevance as a versatile, robust strategy for carrying out in-depth studies in redox proteomics. © 2017 Elsevier Inc. All rights reserved.

  20. 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.

  1. Tubular solid oxide fuel cell development program

    Energy Technology Data Exchange (ETDEWEB)

    Ray, E.R.; Cracraft, C.

    1995-12-31

    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.

  2. Solid oxide fuel cell field trial evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, C.P.; Winstanley, R.; Nietsch, T.; Smith, C.; Knight, R.; Seymore, C.

    2000-07-01

    This report focuses on issues relating to a field trial of a solid oxide fuel cell (SOFC). Aspects examined include markets for SOFC systems, the choice of systems for demonstration in year 2002, the assessment of industrial interest, and evaluation and ranking of candidate systems. The identification and evaluation of interest in field trials, the estimation of the capital and running costs of a field trial, and identification of the benefits to the UK and barriers to implementation of SOFC systems are discussed. (UK)

  3. 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).

  4. Development of solid oxide fuel cell technology

    International Nuclear Information System (INIS)

    Kang, Dae Kab; Kim, Sun Jae; Jung, Choong Hwan; Kim, Kyung Hoh; Park, Ji Yun; Oh, Suk Jin

    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)

  5. Durable and Robust Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Hjalmarsson, Per; Knibbe, Ruth; Hauch, Anne

    project had as one of its’ overarching goals to improve durability and robustness of the Danish solid oxide fuel cells. The project focus was on cells and cell components suitable for SOFC operation in the temperature range 600 – 750 °C. The cells developed and/or studied in this project are intended......The solid oxide fuel cell (SOFC) is an attractive technology for the generation of electricity with high efficiency and low emissions. Risø DTU (now DTU Energy Conversion) works closely together with Topsoe Fuel Cell A/S in their effort to bring competitive SOFC systems to the market. This 2-year...... 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...

  6. Highly Efficient, Durable Regenerative Solid Oxide Stack, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes to develop a highly efficient regenerative solid oxide stack design. Novel structural elements allow direct internal...

  7. 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.

  8. Reversible operation of microtubular solid oxide cells using La0.6Sr0.4Co0.2Fe0.8O3-δ-Ce0.9Gd0.1O2-δ oxygen electrodes

    Science.gov (United States)

    López-Robledo, M. J.; Laguna-Bercero, M. A.; Larrea, A.; Orera, V. M.

    2018-02-01

    Yttria stabilized zirconia (YSZ) based microtubular solid oxide fuel cells (mT-SOFCs) using La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Ce0.9Gd0.1O2-δ (GDC) as the oxygen electrode, along with a porous GDC electrolyte-electrode barrier layer, were fabricated and characterized in both fuel cell (SOFC) and electrolysis (SOEC) operation modes. The cells were anode-supported, the NiO-YSZ microtubular supports being made by Powder Extrusion Moulding (PEM). The cells showed power densities of 695 mW cm-2 at 800 °C and 0.7 V in SOFC mode, and of 845 mA cm-2 at 800 °C and 1.3 V in SOEC mode. AC impedance experiments performed under different potential loads demonstrated the reversibility of the cells. These results showed that these cells, prepared with a method suitable for using on an industrial scale, are highly reproducible and reliable, as well as very competitive as reversible SOFC-SOEC devices operating at intermediate temperatures.

  9. 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)

  10. 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.

  11. Medium-temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Maffei, N.; Kuriakose, A.K. [Natural Resources Canada, Ottawa, ON (Canada). Materials Technology Lab

    2000-07-01

    The Materials Technology Laboratory (MTL) of Natural Resources Canada has been conducting research on the development of a solid oxide fuel cell (SOFC) for the past decade. Fuel cells convert chemical energy directly into electric energy in an efficient and environmentally friendly manner. SOFCs are considered to be good stationary power sources for commercial and residential applications and will likely be commercialized in the near future. The research at MTL has focused on the development of new electrolytes for use in SOFCs. In the course of this research, monolithic planar single cell SOFCs based on doubly doped ceria and lanthanum gallate have been fabricated and tested at 700 degrees C. This paper compared the performance characteristics of both these systems. The data suggested the presence of a significant electronic conductivity in the SOFC incorporating doubly doped ceria, resulting in lower than expected voltage output. The stability of the SOFC, however, did not appear to be negatively affected. The lanthanum gallate based SOFC performed well. It was concluded that reducing the operating temperature of SOFCs would improve their reliability and enhance their operating life. First generation commercial SOFCs will use a zirconium oxide-based electrolytes while second generation units might possibly use ceria-based and/or lanthanum gallate electrolytes. 24 refs., 6 figs.

  12. 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.

  13. Reversible Energy Transfer and Fluorescence Decay in Solid Solutions

    Science.gov (United States)

    Shealy, David L.; Hoover, Richard B.; Gabardi, David R.

    1988-07-01

    The article deals with the influence of reversible excitation energy transfer on the fluorescence decay in systems with random distribution of molecules. On the basis of a hopping model, we have obtained an expression for the Laplace transform of the decay function and an expression for the average decay time. The case of dipole-dipole interaction is discussed in detail.

  14. Solid Oxide Fuel Cell Systems PVL Line

    International Nuclear Information System (INIS)

    Shearer, Susan; Rush, Gregory

    2012-01-01

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

  15. Thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell in combined heat and power applications

    Science.gov (United States)

    Abraham, F.; Dincer, I.

    2015-12-01

    This paper presents a comprehensive steady state modelling and thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell integrated with Gas Turbine power cycle (DU-SOFC/GT). The use of urea as direct fuel mitigates public health and safety risks associated with the use of hydrogen and ammonia. The integration scheme in this study covers both oxygen ion-conducting solid oxide fuel cells (SOFC-O) and hydrogen proton-conducting solid oxide fuel cells (SOFC-H). Parametric case studies are carried out to investigate the effects of design and operating parameters on the overall performance of the system. The results reveal that the fuel cell exhibited the highest level of exergy destruction among other system components. Furthermore, the SOFC-O based system offers better overall performance than that with the SOFC-H option mainly due to the detrimental reverse water-gas shift reaction at the SOFC anode as well as the unique configuration of the system.

  16. Fabrication of cathode supported tubular solid oxide electrolysis cell for high temperature steam electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Le; Wang, Shaorong; Qian, Jiqin; Xue, Yanjie; Liu, Renzhu

    2011-01-15

    In recent years, hydrogen has been identified as a potential alternative fuel and energy carrier for the future energy supply. Water electrolysis is one of the important hydrogen production technologies which do not emit carbon dioxide. High temperature steam electrolysis (HTSE) consumes even less electrical energy than low temperature water electrolysis. Theoretically, HTSE using solid oxide electrolysis cells (SOEC) can efficiently utilize renewable energy to produce hydrogen, and it is also possible to operate the SOEC in reverse mode as the solid oxide fuel cell (SOFC) to produce electricity. Tubular SOFC have been widely investigated. In this study, tubular solid oxide cells were fabricated by dip-coating and cosintering techniques. In SOEC mode, results suggested that steam ratio had a strong impact on the performance of the tubular cell; the tubular SOEC preferred to be operated at high steam ratio in order to avoid concentration polarization. The microstructure of the tubular SOEC should therefore be optimized for high temperature steam electrolysis.

  17. Reviews on Solid Oxide Fuel Cell Technology

    Directory of Open Access Journals (Sweden)

    Apinan Soottitantawat

    2009-02-01

    Full Text Available Solid Oxide Fuel Cell (SOFC is one type of high temperature fuel cell that appears to be one of the most promising technology to provide the efficient and clean energy production for wide range of applications (from small units to large scale power plants. This paper reviews the current status and related researches on SOFC technologies. In details, the research trend for the development of SOFC components(i.e. anode, electrolyte, cathode, and interconnect are presented. Later, the current important designs of SOFC (i.e. Seal-less Tubular Design, Segmented Cell in Series Design, Monolithic Design and Flat Plate Design are exampled. In addition, the possible operations of SOFC (i.e. external reforming, indirect internal reforming, and direct internal reforming are discussed. Lastly, the research studies on applications of SOFCs with co-generation (i.e. SOFC with Combined Heat and Power (SOFC-CHP, SOFC with Gas Turbine (SOFC-GT and SOFC with chemical production are given.

  18. Learning curves for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Tinoco, R.; Schoots, K. [Energy research Centre of the Netherlands (Netherlands). Policy Studies; Zwaan, B.C.C. van der [Energy research Centre of the Netherlands (Netherlands). Policy Studies; Columbia Univ., New York City, NY (United States). Lenfest Center for Sustainable Energy

    2010-07-01

    We present learning curves for solid oxide fuel cells (SOFCs) and combined heat and power (CHP) SOFC systems with an electric capacity between 1 and 250 kW. On the basis of the cost breakdown of production cost data from fuel cell manufacturers, we developed a bottom-up model that allows for determining overall manufacturing costs from their respective cost components, among which material, energy, labor, and capital charges. The results obtained from our model prove to deviate by at most 13% from total cost figures quoted in the literature. For the early pilot stage of development, we find for SOFC manufacturing a learning rate between 14% and 17%, and for total SOFC system fabrication between 16% and 19%. We argue that the corresponding cost reductions result largely from learning-by-searching effects (R and D) rather than learning-by-doing. When considering a longer time frame that includes the early commercial production stage, we find learning rates between 14% and 39%, which represent a mix of phenomena such as learning-by-doing, learning-by-searching, economies-of-scale and automation. (orig.)

  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. 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. 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.

  2. Solid Oxide Fuel Cells Canada (SOFCC)

    International Nuclear Information System (INIS)

    Birss, V.; Borglum, B.

    2006-01-01

    Vision: To enhance co-ordination and to ensure sustainable funding of research, development, and commercialization of solid oxide fuel cells and related technologies in Canada in order to create products that serve the world. Current Research Areas of Investigation: Mission: To provide cleaner air, reduce CO 2 emissions, better utilize fuel resources, increase economic prosperity, and enhance the quality of life in Canada and the world by enabling and accelerating development of the Canadian SOFC industry. To achieve this, we will: 1. Establish national priorities for the research, development, design, demonstration, and the innovation process; commercialization of SOFC and related technologies; 2. Develop a strategy to produce commercial products within 5 years; 3. Co-ordinate activities as one integrated Canada-wide initiative; 4. Facilitate effective access to funding by providing a venue for funders to directly participate in; 5. Provide an integrating and interdisciplinary function to maximize the collective knowledge, expertise, and capacity of the alliance partners; 6. Maintain strategic relevance within an ever changing global context by providing high-quality intelligence. (author)

  3. Nanoscale Phase Stability Reversal During the Nucleation and Growth of Titanium Oxide Minerals

    Science.gov (United States)

    Hummmer, D. R.; Heaney, P. J.; Kubicki, J. D.; Kent, P. R.; Post, J. E.

    2008-12-01

    Fine-grained titanium oxide minerals are important in soils, where they affect a variety of geochemical processes. They are also industrially important as catalysts, pigments, food additives, and dielectrics. Recent research has indicated an apparent reversal of thermodynamic stability between TiO2 phases at the nanoscale thought to be caused by an increased contribution of surface energy to the total free energy. Time-resolved X-ray diffraction (XRD) experiments in which titanium oxides crystallize from aqueous TiCl4 solutions confirm that anatase, a metastable phase, is always the first phase to nucleate under our range of initial conditions. Rutile peaks are observed only minutes after the first appearance of anatase, after which anatase abundance slowly decreases while rutile continues to form. Whole pattern refinement of diffraction data reveals that lattice constants of both phases increase throughout the crystallization process. In addition, transmission electron microscope (TEM) observations and kinetic modeling indicate that anatase does not undergo a solid-state transformation to the rutile structure as once thought. Instead, anatase appears to re-dissolve and then feed the growth of already nucleated rutile nanocrystals. Density functional theory (DFT) calculations were employed to model 1, 2, and 3 nm particles of both mineral phases. The total surface energies calculated from these models did yield lower values for anatase than for rutile by 8-13 kJ/mol depending on particle size, indicating that surface free energy is sufficient to account for stability reversal. However, these whole-particle surface energies were much higher than the sum of energies of each particle's constituent crystallographic surfaces. We attribute the excess energy to defects associated with the edges and corners of nanoparticles, which are not present on a 2-D periodic surface. This previously unreported edge and corner energy may play a dominant role in the stability reversal

  4. 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

  5. Learning curves for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Rivera-Tinoco, Rodrigo; Schoots, Koen; Zwaan, Bob van der

    2012-01-01

    Highlights: ► We present learning curves for fuel cells based on empirical data. ► We disentangle different cost reduction mechanisms for SOFCs. ► We distinguish between learning-by-doing, R and D, economies-of-scale and automation. - Abstract: In this article we present learning curves for solid oxide fuel cells (SOFCs). With data from fuel cell manufacturers we derive a detailed breakdown of their production costs. We develop a bottom-up model that allows for determining overall SOFC manufacturing costs with their respective cost components, among which material, energy, labor and capital charges. The results obtained from our model prove to deviate by at most 13% from total cost figures quoted in the literature. For the R and D stage of development and diffusion, we find local learning rates between 13% and 17% and we demonstrate that the corresponding cost reductions result essentially from learning-by-searching effects. When considering periods in time that focus on the pilot and early commercial production stages, we find regional learning rates of 27% and 1%, respectively, which we assume derive mainly from genuine learning phenomena. These figures turnout significantly higher, approximately 44% and 12% respectively, if also effects of economies-of-scale and automation are included. When combining all production stages we obtain lr = 35%, which represents a mix of cost reduction phenomena. This high learning rate value and the potential to scale up production suggest that continued efforts in the development of SOFC manufacturing processes, as well as deployment and use of SOFCs, may lead to substantial further cost reductions.

  6. Understanding the processes governing performance and durability of solid oxide electrolysis cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune Dalgaard; Sun, Xiufu; Mogensen, Mogens Bjerg

    2015-01-01

    Operation of a Ni–YSZ electrode supported Solid Oxide Cell (SOC) was studied in both fuel cell mode (FC-mode) and electrolysis cell mode (EC-mode) in mixtures of H2O/H2, CO2/CO, H2O/H2O/CO2/CO at 750 °C, 800 °C and 850 °C. Although the SOCs are reversible, the polarisation characterisation shows ...

  7. Application of the monolithic solid oxide fuel cell to space power systems

    International Nuclear Information System (INIS)

    Myles, K.M.; Bhattacharyya, S.K.

    1991-01-01

    The monolithic solid-oxide fuel cell (MSOFC) is a promising electrochemical power generation device that is currently under development at Argonne National Laboratory. The extremely high power density of the MSOFC leads to MSOFC systems that have sufficiently high energy densities that they are excellent candidates for a number of space missions. The fuel cell can also be operated in reverse, if it can be coupled to an external power source, to regenerate the fuel and oxidant from the water product. This feature further enhances the potential mission applications of the MSOFC. In this paper, the current status of the fuel cell development is presented---the focus being on fabrication and currently achievable performance. In addition, a specific example of a space power system, featuring a liquid metal cooled fast spectrum nuclear reactor and a monolithic solid oxide fuel cell, is presented to demonstrate the features of an integrated system

  8. Application of the monolithic solid oxide fuel cell to space power systems

    Science.gov (United States)

    Myles, Kevin M.; Bhattacharyya, Samit K.

    1991-01-01

    The monolithic solid-oxide fuel cell (MSOFC) is a promising electrochemical power generation device that is currently under development at Argonne National Laboratory. The extremely high power density of the MSOFC leads to MSOFC systems that have sufficiently high energy densities that they are excellent candidates for a number of space missions. The fuel cell can also be operated in reverse, if it can be coupled to an external power source, to regenerate the fuel and oxidant from the water product. This feature further enhances the potential mission applications of the MSOFC. In this paper, the current status of the fuel cell development is presented—the focus being on fabrication and currently achievable performance. In addition, a specific example of a space power system, featuring a liquid metal cooled fast spectrum nuclear reactor and a monolithic solid oxide fuel cell, is presented to demonstrate the features of an integrated system.

  9. 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...

  10. Transformation features in solid nitrous oxide

    International Nuclear Information System (INIS)

    Drobyshev, A.; Aldiyarov, A.; Korshikov, E.; Sokolov, D.; Kurnosov, V.

    2012-01-01

    The transformation features in cryocondensates of nitrous oxide were studied in the process of thermal cycling in the vicinity of the temperature T = 40 K. The research was aimed at figuring out the response of deformation and translational vibrational subsystems of the condensed nitrous oxide to these transformations. The temperature and the nature of thermally stimulated reactions in the films of nitrous oxide cryocondensates were determined. By measuring the vibrational spectra of the samples and by recording the changes in amplitude and position of the absorption bands characteristic of vibrations. Analysis of the IR spectra suggests that the transition from the amorphous state of nitrous oxide to the crystalline one is carried out in several stages, which account for the implementation of relaxation processes related to a particular type of vibrations of a nitrous oxide molecule. The difference in the temperatures of the transitions is determined by activation energies that are typical of this type of oscillation.

  11. Modeling and parametric simulations of solid oxide fuel cells with methane carbon dioxide reforming

    International Nuclear Information System (INIS)

    Ni, Meng

    2013-01-01

    Highlights: ► A 2D model is developed for solid oxide fuel cells (SOFCs). ► CH 4 reforming by CO 2 (MCDR) is included. ► SOFC with MCDR shows comparable performance with methane steam reforming SOFC. ► Increasing CO electrochemical oxidation greatly enhances the SOFC performance. ► Effects of potential and temperature on SOFC performance are also discussed. - Abstract: A two-dimensional model is developed to simulate the performance of solid oxide fuel cells (SOFCs) fed with CO 2 and CH 4 mixture. The electrochemical oxidations of both CO and H 2 are included. Important chemical reactions are considered in the model, including methane carbon dioxide reforming (MCDR), reversible water gas shift reaction (WGSR), and methane steam reforming (MSR). It’s found that at a CH 4 /CO 2 molar ratio of 50/50, MCDR and reversible WGSR significantly influence the cell performance while MSR is negligibly small. The performance of SOFC fed with CO 2 /CH 4 mixture is comparable to SOFC running on CH 4 /H 2 O mixtures. The electric output of SOFC can be enhanced by operating the cell at a low operating potential or at a high temperature. In addition, the development of anode catalyst with high activity towards CO electrochemical oxidation is important for SOFC performance enhancement. The model can serve as a useful tool for optimization of the SOFC system running on CH 4 /CO 2 mixtures

  12. 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)

  13. A novel accelerated oxidative stability screening method for pharmaceutical solids.

    Science.gov (United States)

    Zhu, Donghua Alan; Zhang, Geoff G Z; George, Karen L S T; Zhou, Deliang

    2011-08-01

    Despite the fact that oxidation is the second most frequent degradation pathway for pharmaceuticals, means of evaluating the oxidative stability of pharmaceutical solids, especially effective stress testing, are still lacking. This paper describes a novel experimental method for peroxide-mediated oxidative stress testing on pharmaceutical solids. The method utilizes urea-hydrogen peroxide, a molecular complex that undergoes solid-state decomposition and releases hydrogen peroxide vapor at elevated temperatures (e.g., 30°C), as a source of peroxide. The experimental setting for this method is simple, convenient, and can be operated routinely in most laboratories. The fundamental parameter of the system, that is, hydrogen peroxide vapor pressure, was determined using a modified spectrophotometric method. The feasibility and utility of the proposed method in solid form selection have been demonstrated using various solid forms of ephedrine. No degradation was detected for ephedrine hydrochloride after exposure to the hydrogen peroxide vapor for 2 weeks, whereas both anhydrate and hemihydrate free base forms degraded rapidly under the test conditions. In addition, both the anhydrate and the hemihydrate free base degraded faster when exposed to hydrogen peroxide vapor at 30°C under dry condition than at 30°C/75% relative humidity (RH). A new degradation product was also observed under the drier condition. The proposed method provides more relevant screening conditions for solid dosage forms, and is useful in selecting optimal solid form(s), determining potential degradation products, and formulation screening during development. Copyright © 2011 Wiley-Liss, Inc.

  14. Solid Oxide Galvanic Cell to determine thermochemical data of Dy6UO12(s)

    International Nuclear Information System (INIS)

    Sahu, Manjulata; Dash, Smruti; Sen, B.K.; Venugopal, V.

    2010-01-01

    The rare earth elements such as Sm, Eu, Gd, and Dy have very high thermal neutron absorption cross sections and their oxides are utilized as burnable poisons in nuclear reactor to maintain constant reactivity of the core. These oxides form solid solution with urania as their ionic radii are within 20% of that of urania. Rare earth oxides-urania solid solutions are also beneficial in preventing oxidation of UO 2 (s). RE 6 UO I2 (s) (RE = rare earth) type of compounds are known to exist in RE-U-O system and their formation cannot be ruled out under transient conditions. The data on Gibbs energy of formation of compounds in RE-U-O system is therefore essential to predict the feasibility. Theoretically, the measurement of the e.m.f. of a suitable galvanic cell is one of the most accurate methods to obtain Gibbs energy of formation of compounds if e.m.f cell operates reversibly. In this study, the standard molar Gibbs energy of formation of Dy 6 UO I2 (s) was determined using solid oxide galvanic cell technique. The Gibbs energy of formation of Dy 6 UO 12 (s) is reported for the first time

  15. A development of solid oxide fuel cell technology

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hee Chun; Lee, Chang Woo [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Kwy Youl; Yoon, Moon Soo; Kim, Ho Ki; Kim, Young Sik; Mun, Sung In; Eom, Sung Wuk [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of)

    1995-12-31

    Solid oxide fuel cell which was consisted of ceramics has high power density and is very simple in shape. The project named A development of SOFC(Solid Oxide Fuel Cell) technology is to develop the unit cell fabrication processing and to evaluate the unit cell of solid oxide full cell. In this project, a manufacturing process of cathode by citrate method and polymeric precursor methods were established. By using tape casting method, high density thin electrolyte was manufactured and has high performance. Unit cell composed with La{sub 17}Sr{sub 13}Mn{sub 3} as cathode, 8YSZ electrolyte and 50% NiYSZ anode had a performance of O.85 W/cm{sup 2} and recorded 510 hours operation time. On the basis of these results. 100 cm{sup 2} class unit cell will be fabricated and tests in next program (author). 59 refs., 120 figs.

  16. A development of solid oxide fuel cell technology

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hee Chun; Lee, Chang Woo [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Kwy Youl; Yoon, Moon Soo; Kim, Ho Ki; Kim, Young Sik; Mun, Sung In; Eom, Sung Wuk [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of)

    1996-12-31

    Solid oxide fuel cell which was consisted of ceramics has high power density and is very simple in shape. The project named A development of SOFC(Solid Oxide Fuel Cell) technology is to develop the unit cell fabrication processing and to evaluate the unit cell of solid oxide full cell. In this project, a manufacturing process of cathode by citrate method and polymeric precursor methods were established. By using tape casting method, high density thin electrolyte was manufactured and has high performance. Unit cell composed with La{sub 17}Sr{sub 13}Mn{sub 3} as cathode, 8YSZ electrolyte and 50% NiYSZ anode had a performance of O.85 W/cm{sup 2} and recorded 510 hours operation time. On the basis of these results. 100 cm{sup 2} class unit cell will be fabricated and tests in next program (author). 59 refs., 120 figs.

  17. 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

  18. 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....... Even though the electrolyte is to the tensile side, it is found that the anode support fails due to the thermo‐mechanical residual stresses....

  19. 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.

  20. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries.

    Science.gov (United States)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-12-23

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn 4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g -1 based on solid-state redox reaction of oxide ions.

  1. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries

    Science.gov (United States)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-01-01

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g−1 based on solid-state redox reaction of oxide ions. PMID:28008955

  2. Hydrogen sulfide-powered solid oxide fuel cells

    Science.gov (United States)

    Liu, Man

    2004-12-01

    The potential utilization of hydrogen sulfide as fuel in solid oxide fuel cells has been investigated using an oxide-ion conducting YSZ electrolyte and different kinds of anode catalysts at operating temperatures in the range of 700--900°C and at atmospheric pressure. This technology offers an economically attractive alternative to present methods for removing toxic and corrosive H2S gas from sour gas streams and a promising approach for cogenerating electrical energy and useful chemicals. The primary objective of the present research was to find active and stable anode materials. Fuel cell experimental results showed that platinum was a good electrocatalyst for the conversion of H2S, but the Pt/YSZ interface was physically unstable due to the reversible formation and decomposition of PtS in H 2S streams at elevated temperatures. Moreover, instability of the Pt/YSZ interface was accelerated significantly by electrochemical reactions, and ultimately led to the detachment of the Pt anode from the electrolyte. It has been shown that an interlayer of TiO2 stabilized the Pt anode on YSZ electrolyte, thereby prolonging cell lifetime. However, the current output for a fuel cell using Pt/TiO2 as anode was not improved compared to using Pt alone. It was therefore necessary to investigate novel anode systems for H 2S-air SOFCs. New anode catalysts comprising composite metal sulfides were developed. These catalysts exhibited good electrical conductivity and better catalytic activity than Pt. In contrast to MoS2 alone, composite catalysts (M-Mo-S, M = Fe, Co, Ni) were not volatile and had superior stability. However, when used for extended periods of time, detachment of Pt current collecting film from anodes comprising metal sulfides alone resulted in a large increase in contact resistance and reduction in cell performance. Consequently, a systematic investigation was conducted to identify alternative electronic conductors for use with M-Mo-S catalysts. Anode catalysts

  3. Kinetics and reversibility of radiocaesium solid/liquid partitioning in sediments

    International Nuclear Information System (INIS)

    Comans, R.N.J.

    1998-01-01

    The kinetics and reversibility of radiocaesium solid/liquid partitioning in sediments have been reviewed and interpreted in terms of a mechanistic framework. This framework is based on the premise that radiocaesium is almost exclusively and highly-selectively bound to the frayed particle edges of illitic clay minerals in the sediments. Several processes with distinctly different rates can be distinguished in radiocaesium sorption to sediments. 2- and 3-box kinetic models can describe both the overall solid/liquid partitioning in sediments and the reversible (exchangeable) and irreversible (nonexchangeable or 'fixed') fractions of radiocaesium in sediments over time scales relevant for natural aquatic systems. The obtained rate parameters indicate that reversible partitioning of radiocaesium dominates over the first few days following a contamination event, whereas irreversible kinetics becomes important over time scales of weeks to months. The slow process, which reduces the exchangeability of sediment-bound radiocaesium over time, is believed to result from a migration of radiocaesium from exchangeable sites on the frayed edges of illite towards less-exchangeable interlayer sites. Long-term extraction of radiocaesium from historically contaminated sediments has given evidence for a reverse (remobilization) process with a half-life of the order of tens of years. These findings suggest that the long-term exchangeability of radiocaesium in sediments may be higher than the few % which is generally assumed. (orig.)

  4. Modified cermet fuel electrodes for solid oxide electrochemical cells

    Science.gov (United States)

    Ruka, Roswell J.; Spengler, Charles J.

    1991-01-01

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

  5. Structure and high-piezoelectricity in lead oxide solid solutions

    NARCIS (Netherlands)

    Noheda, B.

    2002-01-01

    A review of the recent advances in the understanding of piezoelectricity in lead oxide solid solutions is presented, giving special attention to the structural aspects. It has now become clear that the very high electromechanical response in these materials is directly related to the existence of

  6. 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...

  7. 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...

  8. Kinetic and geometric aspects of solid oxide fuel cell electrodes

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Skaarup, Steen

    1996-01-01

    The paper gives an overview of the main factors controlling the performance of the solid oxide fuel cell (SOFC) electrodes, emphasizing the most widely chosen anodes and cathodes, Ni-YSZ and LSM-YSZ. They are often applied as composites (mixtures) of the electron conducting electrode material...

  9. Performance Evaluation of Solid Oxide Fuel Cell by Computer ...

    African Journals Online (AJOL)

    The search for sustainable energy source that can compete with the existing one led to the discovery and acceptance of fuel cell technologies as a perfect replacement for fossil fuel. The ability of Solid Oxide Fuel Cells (SOFC) to capture the heat generation during the process of energy generation from electrochemical ...

  10. Concentration Impedance in Testing of Solid Oxide Cells Revisited

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Ebbesen, Sune Dalgaard; Jensen, Søren Højgaard

    2017-01-01

    The concentration impedance originating from diffusion and reactant conversion impedance of the Ni-YSZ supported fuel electrode in solid oxide cell has been treated many times during the latest couple of decades. In spite of this, the separation of the diffusion impedance from the conversion...

  11. 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 ox...

  12. 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

    An interesting source of producing energy with low pollutants emission and reduced environmental impact are the biomasses; particularly using Municipal Solid Waste (MSW) as fuel, can be a competitive solution not only to produce energy with negligible costs but also to decrease the storage...... 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...

  13. 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.

  14. Characterisation of a Planar Solid Oxide Cell Stack Operated at Elevated Pressure

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Graves, Christopher R.; Chen, Ming

    2016-01-01

    As the global and local energy production becomes more dependent on intermittent renewable sources like wind and solar, efficient and reversible conversion of electricity to storable fuels becomes increasingly important. Solid oxide cells (SOCs) are interesting in this context since they can...... be operated either as electrolysers (SOEC) to convert electricity to fuels such as hydrogen or methane, and as fuel cells (SOFC) to convert fuels to electricity. Both productivity and conversion efficiency can be improved if the SOC operation pressure can be increased from ambient pressure to 10-30 bar. Here...... and heat exchangers is analyzed and the expected impact of pressurization on the hydrogen production cost is evaluated....

  15. Characterization of a Planar Solid Oxide Cell Stack Operated at Elevated Pressure

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Graves, Christopher R.; Chen, Ming

    2016-01-01

    As global and local energy production becomes more dependent on intermittent renewable sources like wind and solar, efficient and reversible conversion of electricity to storable fuels becomes increasingly important. Solid oxide cells (SOCs) are interesting in this context since they can...... be operated either as electrolyzers (SOEC) to convert electricity to fuels such as hydrogen or methane, and as fuel cells (SOFC) to convert fuels to electricity. Both productivity and conversion efficiency can be improved if the SOC operation pressure can be increased from ambient pressure to 10–30 bar...... in this paper. Additionally, the expected impact on the hydrogen production efficiency and cost is discussed....

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

    Science.gov (United States)

    Bents, David J.

    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.

  17. 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.

  18. Safety analysis of switching between reductive and oxidative conditions in a reaction coupling reverse flow reactor.

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2001-01-01

    A new reverse flow reactor is developed where endothermic reactants (propane dehydrogenation) and exothermic reactants (fuel combustion) are fed sequentially to a monolithic catalyst, while periodically alternating the inlet and outlet positions. Upon switching from reductive to oxidative conditions

  19. 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.

  20. 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.

  1. An inexact reverse logistics model for municipal solid waste management systems.

    Science.gov (United States)

    Zhang, Yi Mei; Huang, Guo He; He, Li

    2011-03-01

    This paper proposed an inexact reverse logistics model for municipal solid waste management systems (IRWM). Waste managers, suppliers, industries and distributors were involved in strategic planning and operational execution through reverse logistics management. All the parameters were assumed to be intervals to quantify the uncertainties in the optimization process and solutions in IRWM. To solve this model, a piecewise interval programming was developed to deal with Min-Min functions in both objectives and constraints. The application of the model was illustrated through a classical municipal solid waste management case. With different cost parameters for landfill and the WTE, two scenarios were analyzed. The IRWM could reflect the dynamic and uncertain characteristics of MSW management systems, and could facilitate the generation of desired management plans. The model could be further advanced through incorporating methods of stochastic or fuzzy parameters into its framework. Design of multi-waste, multi-echelon, multi-uncertainty reverse logistics model for waste management network would also be preferred. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Isenberg, Arnold O.

    1987-01-01

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

  3. Lanthanum Manganate Based Cathodes for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Jørgensen, Mette Juhl

    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...... 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...

  4. Solid-phase vibrational redox reactions in coordinated oxides

    International Nuclear Information System (INIS)

    Kostikova, G.P.; Korol'kov, D.V.; Kostikov, Yu.P.

    1996-01-01

    The properties of multicomponent oxides (YBa 2 Cu 3 O 7-x , etc.), incorporating different valency forms of each of two (or more) different elements have been compared with the properties of the known chemical systems, where vibrational (periodic) redox-reactions are realized a fortiori. The essence of the new theoretical concept suggested consists in the following: high-T c superconductivity of the complex oxides and similar compounds originates from vibrational redox reaction proceeding in solid phase and involving different valency atoms of every element

  5. 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

    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......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...

  6. Materials for high temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    Singhal, S.C.

    1987-01-01

    High temperature solid oxide fuel cells show great promise for economical production of electricity. These cells are based upon the ability of stabilized zirconia to operate as an oxygen ion conductor at elevated temperatures. The design of the tubular solid oxide fuel cell being pursued at Westinghouse is illustrated. The cell uses a calcia-stabilized zironcia porous support tube, which acts both as a structural member onto which the other cell components are fabricated in the form of thin layers, and as a functional member to allow the passage, via its porosity, of air (or oxygen) to the air electrode. This paper summarizes the materials and fabrication processes for the various cell components

  7. 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.

  8. 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...

  9. Reversing Size-Dependent Trends in the Oxidation of Copper Clusters through Support Effects: Reversing Size-Dependent Trends in the Oxidation of Copper Clusters through Support Effects

    Energy Technology Data Exchange (ETDEWEB)

    Mammen, Nisha [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, -560064 Bangalore India; Spanu, Leonardo [Shell Technology Center, Shell India Markets Private Limited, -560048 Bangalore India; Tyo, Eric C. [Materials Science Division, Argonne National Laboratory, 60439 Argonne IL USA; Yang, Bing [Materials Science Division, Argonne National Laboratory, 60439 Argonne IL USA; Halder, Avik [Materials Science Division, Argonne National Laboratory, 60439 Argonne IL USA; Seifert, Sönke [X-ray Science Division, Argonne National Laboratory, 60439 Argonne IL USA; Pellin, Michael J. [Materials Science Division, Argonne National Laboratory, 60439 Argonne IL USA; Vajda, Stefan [Materials Science Division, Argonne National Laboratory, 60439 Argonne IL USA; Institute for Molecular Engineering, The University of Chicago, 60637 Chicago IL USA; Narasimhan, Shobhana [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, -560064 Bangalore India

    2017-12-22

    Having the ability to tune the oxidation state of Cu nanoparticles is essential for their utility as catalysts. The degree of oxidation that maximizes product yield and selectivity is known to vary, depending on the particular reaction. Using first principles calculations and XANES measurements, we show that for subnanometer sizes in the gas phase, smaller Cu clusters are more resistant to oxidation. However, this trend is reversed upon deposition on an alumina support. We are able to explain this result in terms of strong cluster-support interactions, which differ significantly for the oxidized and elemental clusters. The stable cluster phases also feature novel oxygen stoichiometries. Our results suggest that one can tune the degree of oxidation of Cu catalysts by optimizing not just their size, but also the support they are deposited on.

  10. C18, C8, and perfluoro reversed phases on diamond for solid-phase extraction.

    Science.gov (United States)

    Saini, Gaurav; Wiest, Landon A; Herbert, David; Biggs, Katherine N; Dadson, Andrew; Vail, Michael A; Linford, Matthew R

    2009-04-17

    In spite of advances in solid-phase extraction (SPE) technology there are certain disadvantages to current SPE silica-based, column packings. The pH range over which extraction can occur is limited and each column is generally only used once. New diamond-based reversed SPE phases (C(18), C(8), and perfluorinated) were developed in our laboratories. Studies were done which show that these phases do not have the same limitations as traditional silica-based stationary phases. The synthesis and properties of these diamond-based phases are presented, and the stability, percent recovery, and column capacity are given for the C(18) phase.

  11. 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.

  12. Improving the performance of solid oxide fuel cell systems

    OpenAIRE

    Halinen, Matias

    2015-01-01

    Solid oxide fuel cell (SOFC) systems can provide power production at a high electrical efficiency and with very low emissions. Furthermore, they retain their high electrical efficiency over a wide range of output power and offer good fuel flexibility, which makes them well suited for a range of applications. Currently SOFC systems are under investigation by researchers as well as being developed by industrial manufacturers. The first commercial SOFC systems have been on the market for some...

  13. 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.

  14. High Reversibility of Soft Electrode Materials in All-solid-state Batteries

    Directory of Open Access Journals (Sweden)

    Atsushi eSakuda

    2016-05-01

    Full Text Available All-solid-state batteries using inorganic solid electrolytes (SEs are considered to be ideal batteries for electric vehicles (EVs and plug-in hybrid electric vehicles (PHEVs because they are potentially safer than conventional lithium-ion batteries (LIBs. In addition, all-solid-state batteries are expected to have long battery lives owing to the inhibition of chemical side reactions because only lithium ions move through the typically used inorganic SEs. The development of high-energy (more than 300 Wh kg-1 secondary batteries has been eagerly anticipated for years. The application of high-capacity electrode active materials is essential for fabricating such batteries. Recently, we proposed metal polysulfides as new electrode materials. These materials show higher conductivity and density than sulfur, which is advantageous for fabricating batteries with relatively higher energy density. Lithium niobium sulfides, such as Li3NbS4, have relatively high density, conductivity, and rate capability among metal polysulfide materials, and batteries with these materials have capacities high enough to potentially exceed the gravimetric energy density of conventional LIBs.Favorable solid-solid contact between the electrode and electrolyte particles is a key factor for fabricating high performance all-solid-state batteries. Conventional oxide-based positive electrode materials tend to be given rise to cracks during fabrication and/or charge-discharge processes. Here we report all-solid-state cells using lithium niobium sulfide as a positive electrode material, where favorable solid-solid contact was established by using lithium sulfide electrode materials because of their high processability. Cracks were barely observed in the electrode particles in the all-solid-state cells before or after charging and discharging with a high capacity of approx. 400 mAh g-1, suggesting that the lithium niobium sulfide electrode charged and discharged without experiencing

  15. 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.

  16. Thermal imaging of solid oxide fuel cell anode processes

    Energy Technology Data Exchange (ETDEWEB)

    Pomfret, Michael B.; Kidwell, David A.; Owrutsky, Jeffrey C. [Chemistry Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Steinhurst, Daniel A. [Nova Research Inc., Alexandria, VA 22308 (United States)

    2010-01-01

    A Si-charge-coupled device (CCD), camera-based, near-infrared imaging system is demonstrated on Ni/yttria-stabilized zirconia (YSZ) fragments and the anodes of working solid oxide fuel cells (SOFCs). NiO reduction to Ni by H{sub 2} and carbon deposition lead to the fragment cooling by 5 {+-} 2 C and 16 {+-} 1 C, respectively. When air is flowed over the fragments, the temperature rises 24 {+-} 1 C as carbon and Ni are oxidized. In an operational SOFC, the decrease in temperature with carbon deposition is only 4.0 {+-} 0.1 C as the process is moderated by the presence of oxides and water. Electrochemical oxidation of carbon deposits results in a {delta}T of +2.2 {+-} 0.2 C, demonstrating that electrochemical oxidation is less vigorous than atmospheric oxidation. While the high temperatures of SOFCs are challenging in many respects, they facilitate thermal imaging because their emission overlaps the spectral response of inexpensive Si-CCD cameras. Using Si-CCD cameras has advantages in terms of cost, resolution, and convenience compared to mid-infrared thermal cameras. High spatial ({proportional_to}0.1 mm) and temperature ({proportional_to}0.1 C) resolutions are achieved in this system. This approach provides a convenient and effective analytical technique for investigating the effects of anode chemistry in operating SOFCs. (author)

  17. Thermal imaging of solid oxide fuel cell anode processes

    Science.gov (United States)

    Pomfret, Michael B.; Steinhurst, Daniel A.; Kidwell, David A.; Owrutsky, Jeffrey C.

    A Si-charge-coupled device (CCD), camera-based, near-infrared imaging system is demonstrated on Ni/yttria-stabilized zirconia (YSZ) fragments and the anodes of working solid oxide fuel cells (SOFCs). NiO reduction to Ni by H 2 and carbon deposition lead to the fragment cooling by 5 ± 2 °C and 16 ± 1 °C, respectively. When air is flowed over the fragments, the temperature rises 24 ± 1 °C as carbon and Ni are oxidized. In an operational SOFC, the decrease in temperature with carbon deposition is only 4.0 ± 0.1 °C as the process is moderated by the presence of oxides and water. Electrochemical oxidation of carbon deposits results in a Δ T of +2.2 ± 0.2 °C, demonstrating that electrochemical oxidation is less vigorous than atmospheric oxidation. While the high temperatures of SOFCs are challenging in many respects, they facilitate thermal imaging because their emission overlaps the spectral response of inexpensive Si-CCD cameras. Using Si-CCD cameras has advantages in terms of cost, resolution, and convenience compared to mid-infrared thermal cameras. High spatial (∼0.1 mm) and temperature (∼0.1 °C) resolutions are achieved in this system. This approach provides a convenient and effective analytical technique for investigating the effects of anode chemistry in operating SOFCs.

  18. Alternative anode materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B.; Huang, Yun-Hui [Texas Materials Institute, ETC 9.102, 1 University Station, C2200, The University of Texas at Austin, Austin, TX 78712 (United States)

    2007-11-08

    The electrolyte of a solid oxide fuel cell (SOFC) is an O{sup 2-}-ion conductor. The anode must oxidize the fuel with O{sup 2-} ions received from the electrolyte and it must deliver electrons of the fuel chemisorption reaction to a current collector. Cells operating on H{sub 2} and CO generally use a porous Ni/electrolyte cermet that supports a thin, dense electrolyte. Ni acts as both the electronic conductor and the catalyst for splitting the H{sub 2} bond; the oxidation of H{sub 2} to H{sub 2}O occurs at the Ni/electrolyte/H{sub 2} triple-phase boundary (TPB). The CO is oxidized at the oxide component of the cermet, which may be the electrolyte, yttria-stabilized zirconia, or a mixed oxide-ion/electron conductor (MIEC). The MIEC is commonly a Gd-doped ceria. The design and fabrication of these anodes are evaluated. Use of natural gas as the fuel requires another strategy, and MIECs are being explored for this application. The several constraints on these MIECs are outlined, and preliminary results of this on-going investigation are reviewed. (author)

  19. Global reverse supply chain design for solid waste recycling under uncertainties and carbon emission constraint.

    Science.gov (United States)

    Xu, Zhitao; Elomri, Adel; Pokharel, Shaligram; Zhang, Qin; Ming, X G; Liu, Wenjie

    2017-06-01

    The emergence of concerns over environmental protection, resource conservation as well as the development of logistics operations and manufacturing technology has led several countries to implement formal collection and recycling systems of solid waste. Such recycling system has the benefits of reducing environmental pollution, boosting the economy by creating new jobs, and generating income from trading the recyclable materials. This leads to the formation of a global reverse supply chain (GRSC) of solid waste. In this paper, we investigate the design of such a GRSC with a special emphasis on three aspects; (1) uncertainty of waste collection levels, (2) associated carbon emissions, and (3) challenges posed by the supply chain's global aspect, particularly the maritime transportation costs and currency exchange rates. To the best of our knowledge, this paper is the first attempt to integrate the three above-mentioned important aspects in the design of a GRSC. We have used mixed integer-linear programming method along with robust optimization to develop the model which is validated using a sample case study of e-waste management. Our results show that using a robust model by taking the complex interactions characterizing global reverse supply chain networks into account, we can create a better GRSC. The effect of uncertainties and carbon constraints on decisions to reduce costs and emissions are also shown. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Naringin Reverses Hepatocyte Apoptosis and Oxidative Stress Associated with HIV-1 Nucleotide Reverse Transcriptase Inhibitors-Induced Metabolic Complications

    Directory of Open Access Journals (Sweden)

    Oluwafeyisetan O. Adebiyi

    2015-12-01

    Full Text Available Nucleoside Reverse Transcriptase Inhibitors (NRTIs have not only improved therapeutic outcomes in the treatment of HIV infection but have also led to an increase in associated metabolic complications of NRTIs. Naringin’s effects in mitigating NRTI-induced complications were investigated in this study. Wistar rats, randomly allotted into seven groups (n = 7 were orally treated daily for 56 days with 100 mg/kg zidovudine (AZT (groups I, II III, 50 mg/kg stavudine (d4T (groups IV, V, VI and 3 mL/kg of distilled water (group VII. Additionally, rats in groups II and V were similarly treated with 50 mg/kg naringin, while groups III and VI were treated with 45 mg/kg vitamin E. AZT or d4T treatment significantly reduced body weight and plasma high density lipoprotein concentrations but increased liver weights, plasma triglycerides and total cholesterol compared to controls, respectively. Furthermore, AZT or d4T treatment significantly increased oxidative stress, adiposity index and expression of Bax protein, but reduced Bcl-2 protein expression compared to controls, respectively. However, either naringin or vitamin E significantly mitigated AZT- or d4T-induced weight loss, dyslipidemia, oxidative stress and hepatocyte apoptosis compared to AZT- or d4T-only treated rats. Our results suggest that naringin reverses metabolic complications associated with NRTIs by ameliorating oxidative stress and apoptosis. This implies that naringin supplements could mitigate lipodystrophy and dyslipidemia associated with NRTI therapy.

  1. National Policy for solid waste and reverse logistics of fluorescent lamps after consumption: a case study

    Directory of Open Access Journals (Sweden)

    William Cestari

    2016-03-01

    Full Text Available Fluorescent lamps are used increasingly today. Considered energy-saving lamps, they become hazardous waste at the end of their life cycle. They are composed partly of mercury, considered harmful to human health. Fluorescent lamps, together with tires and pesticide containers, fall under federal legislation that establishes and regulates their proper disposal. In 2010, Federal Law 12.305 / 2010 was created, establishing the National Policy on Solid Waste (PNRS, making businesses and consumers responsible for the proper disposal of their waste. This article aims to analyze the reverse logistics process of fluorescent lamps post-consumption, in a public education institution. The research used case studies and interviews with managers of the materials administration and warehouse departments of the institution. It was identified that since 2010, the educational institution has not been performing reverse logistics and has been accumulating hazardous material in its warehouses. This paper contributes a suggestion to improve the reverse logistics process and worker safety, and to prevent environmental risks.

  2. 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.

  3. High Reversibility of “Soft” Electrode Materials in All-Solid-State Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sakuda, Atsushi, E-mail: a.sakuda@aist.go.jp; Takeuchi, Tomonari, E-mail: a.sakuda@aist.go.jp; Shikano, Masahiro; Sakaebe, Hikari; Kobayashi, Hironori [Department of Energy and Environment, Research Institute for Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda (Japan)

    2016-05-10

    All-solid-state batteries using inorganic solid electrolytes (SEs) are considered to be ideal batteries for electric vehicles and plug-in hybrid electric vehicles because they are potentially safer than conventional lithium-ion batteries (LIBs). In addition, all-solid-state batteries are expected to have long battery life owing to the inhibition of chemical side reactions because only lithium ions move through the typically used inorganic SEs. The development of high-energy density (more than 300 Wh kg{sup −1}) secondary batteries has been eagerly anticipated for years. The application of high-capacity electrode active materials is essential for fabricating such batteries. Recently, we proposed metal polysulfides as new electrode materials. These materials show higher conductivity and density than sulfur, which is advantageous for fabricating batteries with relatively higher energy density. Lithium niobium sulfides, such as Li{sub 3}NbS{sub 4}, have relatively high density, conductivity, and rate capability among metal polysulfide materials, and batteries with these materials have capacities high enough to potentially exceed the gravimetric-energy density of conventional LIBs. Favorable solid–solid contact between the electrode and electrolyte particles is a key factor for fabricating high performance all-solid-state batteries. Conventional oxide-based positive electrode materials tend to give rise to cracks during fabrication and/or charge–discharge processes. Here, we report all-solid-state cells using lithium niobium sulfide as a positive electrode material, where favorable solid–solid contact was established by using lithium sulfide electrode materials because of their high processability. Cracks were barely observed in the electrode particles in the all-solid-state cells before or after charging and discharging with a high capacity of approximately 400 mAh g{sup −1} suggesting that the lithium niobium sulfide electrode charged and discharged without

  4. High Reversibility of “Soft” Electrode Materials in All-Solid-State Batteries

    International Nuclear Information System (INIS)

    Sakuda, Atsushi; Takeuchi, Tomonari; Shikano, Masahiro; Sakaebe, Hikari; Kobayashi, Hironori

    2016-01-01

    All-solid-state batteries using inorganic solid electrolytes (SEs) are considered to be ideal batteries for electric vehicles and plug-in hybrid electric vehicles because they are potentially safer than conventional lithium-ion batteries (LIBs). In addition, all-solid-state batteries are expected to have long battery life owing to the inhibition of chemical side reactions because only lithium ions move through the typically used inorganic SEs. The development of high-energy density (more than 300 Wh kg −1 ) secondary batteries has been eagerly anticipated for years. The application of high-capacity electrode active materials is essential for fabricating such batteries. Recently, we proposed metal polysulfides as new electrode materials. These materials show higher conductivity and density than sulfur, which is advantageous for fabricating batteries with relatively higher energy density. Lithium niobium sulfides, such as Li 3 NbS 4 , have relatively high density, conductivity, and rate capability among metal polysulfide materials, and batteries with these materials have capacities high enough to potentially exceed the gravimetric-energy density of conventional LIBs. Favorable solid–solid contact between the electrode and electrolyte particles is a key factor for fabricating high performance all-solid-state batteries. Conventional oxide-based positive electrode materials tend to give rise to cracks during fabrication and/or charge–discharge processes. Here, we report all-solid-state cells using lithium niobium sulfide as a positive electrode material, where favorable solid–solid contact was established by using lithium sulfide electrode materials because of their high processability. Cracks were barely observed in the electrode particles in the all-solid-state cells before or after charging and discharging with a high capacity of approximately 400 mAh g −1 suggesting that the lithium niobium sulfide electrode charged and discharged without experiencing

  5. 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.

  6. 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.

  7. 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.

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

    Science.gov (United States)

    Chen, Fanglin; Zhao, Fei; Liu, Qiang

    2015-10-06

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

  9. Leukotriene B4 catabolism: quantitation of leukotriene B4 and its omega-oxidation products by reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Shak, S

    1987-01-01

    LTB4 and its omega-oxidation products may be rapidly, sensitively, and specifically quantitated by the methods of solid-phase extraction and reversed-phase high-performance liquid chromatography (HPLC), which are described in this chapter. Although other techniques, such as radioimmunoassay or gas chromatography-mass spectrometry, may be utilized for quantitative analysis of the lipoxygenase products of arachidonic acid, only the technique of reversed-phase HPLC can quantitate as many as 10 metabolites in a single analysis, without prior derivatization. In this chapter, we also reviewed the chromatographic theory which we utilized in order to optimize reversed-phase HPLC analysis of LTB4 and its omega-oxidation products. With this information and a gradient HPLC system, it is possible for any investigator to develop a powerful assay for the potent inflammatory mediator, LTB4, or for any other lipoxygenase product of arachidonic acid.

  10. Mechanistic modelling of a cathode-supported solid oxide fuel cell. Paper no. IGEC-1-103

    International Nuclear Information System (INIS)

    Suwanwarangkul, R.; Croiset, E.; Pritzker, M.D.; Fowler, M.W.; Douglas, P.L.; Entchev, E.

    2005-01-01

    A model for a cathode-supported tubular solid oxide fuel cell operating with humidified H 2 has been developed. Momentum-, mass-, energy- and charge-transport equations coupled with electrochemical reactions (H 2 oxidation and O 2 reduction) are considered in the model. The model also takes into account the radiative heat transfer between the cell and air-preheating tube. The model is validated against published experimental data ands shows a good agreement. The distributions of temperature, current density, reversible cell voltage, overpotential and species mole fractions within the cell are discussed in detail. (author)

  11. Identification of total reversible cysteine oxidation in an atherosclerosis model using a modified biotin switch assay.

    Science.gov (United States)

    Li, Ru; Huang, Jiqing; Kast, Juergen

    2015-05-01

    Oxidative stress due to the imbalance of reactive oxygen species (ROS) and the resulting reversible cysteine oxidation (CysOX) are involved in the early proatherogenic aspect of atherosclerosis. Given that the corresponding redox signaling pathways are still unclear, a modified biotin switch assay was developed to quantify the reversible CysOX in an atherosclerosis model established by using a monocytic cell line treated with platelet releasate. The accumulation of ROS was observed in the model system and validated in human primary monocytes. Through the application of the modified biotin switch assay, we obtained the first reversible CysOX proteome for this model. A total of 75 peptides, corresponding to 53 proteins, were quantified with oxidative modification. The bioinformatics analysis of these CysOX-containing proteins highlighted biological processes including glycolysis, cytoskeleton arrangement, and redox regulation. Moreover, the reversible oxidation of three glycolysis enzymes was observed using this method, and the regulation influence was verified by an enzyme activity assay. NADPH oxidase (NOX) inhibition treatment, in conjunction with the modified biotin switch method, was used to evaluate the global CysOX status. In conclusion, this versatile modified biotin switch assay provides an approach for the quantification of all reversible CysOX and for the study of redox signaling in atherosclerosis as well as in diseases in other biological systems.

  12. Solid oxide electrolysis cell for decomposition of tritiated water

    International Nuclear Information System (INIS)

    Konishi, S.; Ohno, H.; Yoshida, H.; Katsuta, H.; Naruse, Y.

    1986-01-01

    The decomposition of tritiated water vapor by means of solid oxide electrolysis cells has been proposed for the application to the D-T fusion reactor system. This method is essentially free from problems such as large tritium inventory, radiation damage, and generation of solid waste, so it is expected to be a promising one. Electrolysis of water vapor in an argon carrier was performed using a tube-type stabilized zirconia cell with porous platinum electrodes over the temperature range 500-950 0 C. High conversion ratios from water to hydrogen, of up to 99.9%, were achieved. The characteristics of the cell were deduced from the Nernst equation and the conversion ratios expressed as a function of the IR-free voltage. Experimental results agreed with the equation. The isotope effect in electrolysis is also discussed and experiments with heavy water were carried out. The obtained separation factor was slightly higher than the theoretical value. (author)

  13. Solid oxide electrolysis cell for decomposition of tritiated water

    International Nuclear Information System (INIS)

    Konishi, S.; Katsuta, H.; Naruse, Y.; Ohno, H.; Yoshida, H.

    1984-01-01

    The decomposition of tritiated water vapor with solid oxide electrolysis cell was proposed for the application to the D-T fusion reactor system. This method is essentially free from problems such as large tritium inventory, radiation damage, and generation of solid waste, so it is expected to be a promising one. Electrolysis of water vapor in argon carrier was performed using tube-type stabilized zirconia cell with porous platinum electrodes in the temperature range of 500 0 C to 950 0 C. High conversion ratio from water to hydrogen up to 99.9% was achieved. The characteristics of the cell is deduced from the Nernst's equation and conversion ratio is described as the function of the open circuit voltage. Experimental results agreed with the equation. Isotope effect in electrolysis is also discussed and experiments with heavy water were carried out. Obtained separation factor was slightly higher than the theoretical value

  14. Non-destructive delamination detection in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gazzarri, J.I.; Kesler, O. [Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada)

    2007-05-15

    A finite element model has been developed to simulate the steady state and impedance behaviour of a single operating solid oxide fuel cell (SOFC). The model results suggest that electrode delamination can be detected minimally-invasively by using electrochemical impedance spectroscopy. The presence of cathode delamination causes changes in the cell impedance spectrum that are characteristic of this type of degradation mechanism. These changes include the simultaneous increase in both the series and polarization resistances, in proportion to the delaminated area. Parametric studies show the dependence of these changes on the extent of delamination, on the operating point, and on the kinetic characteristics of the fuel cell under study. (author)

  15. 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...... partial pressure range 0.028-1.00 atm. The recorded impedance spectra were successfully analyzed using the developed impedance model in the investigated temperature and oxygen partial pressure range. It is also demonstrated that the model can be used to predict how impedance spectra evolve with different...

  16. Pressurized Operation of a Planar Solid Oxide Cell Stack

    DEFF Research Database (Denmark)

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

    2016-01-01

    , pressurized SOEC based electrolyzers can become more efficient both energy- and cost-wise than PEM and Alkaline systems. Pressurization of SOFCs can significantly increase the cell power density and reduce the size of auxiliary components. In the present study, a SOC stack was successfully operated......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...

  17. 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...

  18. Multi-metallic anodes for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    Restivo, T.A. Guisard; Mello-Castanho, S.R.H.; Leite, D. Will

    2009-01-01

    A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

  19. 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.

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

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    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....... 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...... 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...

  1. Rapidly reversible redox transformation in nanophase manganese oxides at room temperature triggered by changes in hydration.

    Science.gov (United States)

    Birkner, Nancy; Navrotsky, Alexandra

    2014-04-29

    Chemisorption of water onto anhydrous nanophase manganese oxide surfaces promotes rapidly reversible redox phase changes as confirmed by calorimetry, X-ray diffraction, and titration for manganese average oxidation state. Surface reduction of bixbyite (Mn2O3) to hausmannite (Mn3O4) occurs in nanoparticles under conditions where no such reactions are seen or expected on grounds of bulk thermodynamics in coarse-grained materials. Additionally, transformation does not occur on nanosurfaces passivated by at least 2% coverage of what is likely an amorphous manganese oxide layer. The transformation is due to thermodynamic control arising from differences in surface energies of the two phases (Mn2O3 and Mn3O4) under wet and dry conditions. Such reversible and rapid transformation near room temperature may affect the behavior of manganese oxides in technological applications and in geologic and environmental settings.

  2. Study on the solid state chemistry of ternary uranium oxides

    International Nuclear Information System (INIS)

    Yamashita, Toshiyuki

    1988-03-01

    With the increase of burnup of uranium oxide fuels, various kinds of fission products are formed, and the oxygen atoms combined with the consumed heavy atoms are freed. The solid state chemical and/or thermodynamic properties of these elements at high temperatures are complex, and have not been well clarified. In the present report, an approach was taken that the chemical interactions between UO 2 and these fission products can be regarded as causing overlapped effects of composing ternary uranium oxides, and formation reactions and phase behavior were studied for several ternary uranium oxides with typical fission product elements such as alkaline earth metals and rare earth elements. Precise determination methods for the composition of ternary uranium oxides were developed. The estimated accuracies for x and y values in M y U 1-y O 2+x were ± 0.006 and ± 0.004, respectively. The thermodynamic properties and the lattice parameters of the phases in the Ca-U-O and Pr-U-O systems were discussed in relation to the composition determined by the methods. Crystal structure analyses of cadmium monouranates were made with X-ray diffraction method. (author) 197 refs

  3. 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%.

  4. On the theory of the electroreduction of solid oxide electrolytes

    International Nuclear Information System (INIS)

    Chebotin, V.N.; Brajnin, M.I.; Solov'eva, L.M.; Pakhnutov, I.A.; Lukach, Yu.S.

    1986-01-01

    The process of direct current passage through the cell with MOsub(2)+MeOsub(r) solid electrolyte (M-Zr, Hf, Ce, Th; Me-Ca, Sr, Sc, Y, lanthanides), a blockage cathode and a reversible anode is considered; it leads to electrolyte deviation from stoichiometric composition to insufficient oxygen content. The degree of this deviation and n-type electron conductivity proportional to it, depending on coordinate and time, is described by the nonlinear differential equation of the diffusion type. Electron conductivity of the electrolyte near the cathode increases in time approximating to the limiting value proportional to current conducted. As the distance to the cathode increases electron conductivity reduces by the exponential law, which transforms to a linear one in due course

  5. Formation of Reversible Solid Electrolyte Interface on Graphite Surface from Concentrated Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Dongping; Tao, Jinhui; Yan, Pengfei; Henderson, Wesley A.; Li, Qiuyan; Shao, Yuyan; Helm, Monte L.; Borodin, Oleg; Graff, Gordon L.; Polzin, Bryant; Wang, Chong-Min; Engelhard, Mark; Zhang, Ji-Guang; De Yoreo, James J.; Liu, Jun; Xiao, Jie

    2017-02-10

    Interfacial phenomena have always been key determinants for the performance of energy storage technologies. The solid electrolyte interfacial (SEI) layer, pervasive on the surfaces of battery electrodes for numerous chemical couples, directly affects the ion transport, charge transfer and lifespan of the entire energy system. Almost all SEI layers, however, are unstable resulting in the continuous consumption of the electrolyte. Typically, this leads to the accumulation of degradation products on/restructuring of the electrode surface and thus increased cell impedance, which largely limits the long-term operation of the electrochemical reactions. Herein, a completely new SEI formation mechanism has been discovered, in which the electrolyte components reversibly self-assemble into a protective surface coating on a graphite electrode upon changing the potential. In contrast to the established wisdom regarding the necessity of employing the solvent ethylene carbonate (EC) to form a protective SEI layer on graphite, a wide range of EC-free electrolytes are demonstrated for the reversible intercalation/deintercalation of Li+ cations within a graphite lattice, thereby providing tremendous flexibility in electrolyte tailoring for battery couples. This novel finding is broadly applicable and provides guidance for how to control interfacial reactions through the relationship between ion aggregation and solvent decomposition at polarized interfaces.

  6. ''reverse'' solid-phase radioimmunoasssay for IgM-antibodies to hepatitis A virus

    Energy Technology Data Exchange (ETDEWEB)

    Meurman, O H; Matter, L; Krishna, R V; Krech, U H [Institute of Medical Microbiology, St. Gallen, Switzerland

    1981-01-01

    A ''reverse'' solid-phase radio-immuno-assay for IgM antibodies to hepatitis A virus (HAV) was developed. Anti-human IgM immunoglobulins were bound on the wells of polyvinylchloride microtiter plates. Serum specimens were incubated in the anti-human IgM coated wells and bound IgM antibodies were then assayed for antigen specificity by subsequent incubations with HAV antigen and /sup 125/I-labelled human anti-HAV IgG. The test showed a high sensitivity and specificity for anti-HAV IgM antibodies. No false-positive reactions were observed either in the sera from patients with hepatobiliary disorders other than HAV infection or in the sera containing both rheumatoid factor and anti-HAV IgG antibodies. In acute HAV infections specific IgM antibodies were present already in the first specimens taken within a few days after the onset of jaundice. The persistence of the IgM antibodies was from 4 to 6 months. IgM antibody titers up to 1,000,000 were observed in the acute phase of HAV infection. In routine diagnostic work the titration of the sera was not necessary, since a reliable qualitative result was obtained by testing the sera in a single dilution of 1:100. A similar reverse immuno-assay principle may be adaptable for the diagnostic determination of IgM antibodies to different viral and microbial antigens.

  7. 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.

  8. 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.

  9. A solid oxide fuel cell system for buildings

    International Nuclear Information System (INIS)

    Zink, Florian; Lu, Yixin; Schaefer, Laura

    2007-01-01

    This paper examines an integrated solid oxide fuel cell (SOFC) absorption heating and cooling system used for buildings. The integrated system can provide heating/cooling and/or hot water for buildings while consuming natural gas. The aim of this study is to give an overall description of the system. The possibility of such an integrated system is discussed and the configuration of the system is described. A system model is presented, and a specific case study of the system, which consists of a pre-commercial SOFC system and a commercial LiBr absorption system, is performed. In the case study, the detailed configuration of an integrated system is given, and the heat and mass balance and system performance are obtained through numerical calculation. Based on the case study, some considerations with respect to system component selection, system configuration and design are discussed. Additionally, the economic and environmental issues of this specific system are evaluated briefly. The results show that the combined system demonstrates great advantages in both technical and environmental aspects. With the present development trends in solid oxide fuel cells and the commercial status of absorption heating and cooling systems, it is very likely that such a combined system will become increasingly feasible within the following decade

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

    Energy Technology Data Exchange (ETDEWEB)

    Faress Rahman; Nguyen Minh

    2003-07-01

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

  11. Complementary techniques for solid oxide cell characterisation on micro- and nano-scale

    International Nuclear Information System (INIS)

    Wiedenmann, D.; Hauch, A.; Grobety, B.; Mogensen, M.; Vogt, U.

    2009-01-01

    High temperature steam electrolysis by solid oxide electrolysis cells (SOEC) is a way with great potential to transform clean and renewable energy from non-fossil sources to synthetic fuels such as hydrogen, methane or dimethyl ether, which have been identified as promising alternative energy carriers. Also, as SOEC can operate in the reverse mode as solid oxide fuel cells (SOFC), during high peak hours e.g. hydrogen can be used in a very efficient way to reconvert chemically stored energy into electrical energy. As solid oxide cells (SOC) are working at high temperatures (700-900 o C), material degradation and evaporation can occur e.g. from the cell sealing material, leading to poisoning effects and aging mechanisms which are decreasing the cell efficiency and long-term durability. In order to investigate such cell degradation processes, thorough examination on SOC often requires the chemical and structural characterisation on the microscopic and the nanoscopic level. The combination of different microscope techniques like conventional scanning electron microscopy (SEM), electron-probe microanalysis (EPMA) and the focused ion-beam (FIB) preparation technique for transmission electron microscopy (TEM) allows performing post mortem analysis on a multi scale level of cells after testing. These complementary techniques can be used to characterize structural and chemical changes over a large and representative sample area (micro-scale) on the one hand, and also on the nano-scale level for selected sample details on the other hand. This article presents a methodical approach for the structural and chemical characterisation of changes in aged cathode-supported electrolysis cells produced at Riso DTU, Denmark. Also, results from the characterisation of impurities at the electrolyte/hydrogen interface caused by evaporation from sealing material are discussed. (author)

  12. Tilts, dopants, vacancies and non-stoichiometry: Understanding and designing the properties of complex solid oxide perovskites from first principles

    Science.gov (United States)

    Bennett, Joseph W.

    Perovskite oxides of formula ABO3 have a wide range of structural, electrical and mechanical properties, making them vital materials for many applications, such as catalysis, ultrasound machines and communication devices. Perovskite solid solutions with high piezoelectric response, such as ferroelectrics, are of particular interest as they can be employed as sensors in SONAR devices. Ferroelectric materials are unique in that their chemical and electrical properties can be non-invasively and reversibly changed, by switching the bulk polarization. This makes ferroelectrics useful for applications in non-volatile random access memory (NVRAM) devices. Perovskite solid solutions with a lower piezoelectric response than ferroelectrics are important for communication technology, as they function well as electroceramic capacitors. Also of interest is how these materials act as a component in a solid oxide fuel cell, as they can function as an efficient source of energy. Altering the chemical composition of these solid oxide materials offers an opportunity to change the desired properties of the final ceramic, adding a degree of flexibility that is advantageous for a variety of applications. These solid oxides are complex, sometimes disordered systems that are a challenge to study experimentally. However, as it is their complexity which produces favorable properties, highly accurate modeling which captures the essential features of the disordered structure is necessary to explain the behavior of current materials and predict favorable compositions for new materials. Methodological improvements and faster computer speeds have made first-principles and atomistic calculations a viable tool for understanding these complex systems. Offering a combination of accuracy and computational speed, the density functional theory (DFT) approach can reveal details about the microscopic structure and interactions of complex systems. Using DFT and a combination of principles from both

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

    Science.gov (United States)

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

    2015-09-01

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

  14. Solid oxide fuel cell having a monolithic core

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  15. Carbonate-linked poly(ethylene oxide) polymer electrolytes towards high performance solid state lithium batteries

    International Nuclear Information System (INIS)

    He, Weisheng; Cui, Zili; Liu, Xiaochen; Cui, Yanyan; Chai, Jingchao; Zhou, Xinhong; Liu, Zhihong; Cui, Guanglei

    2017-01-01

    The classic poly(ethylene oxide) (PEO) based solid polymer electrolyte suffers from poor ionic conductivity of ambient temperature, low lithium ion transference number and relatively narrow electrochemical window (<4.0 V vs. Li + /Li). Herein, the carbonate-linked PEO solid polymer such as poly(diethylene glycol carbonate) (PDEC) and poly(triethylene glycol carbonate) (PTEC) were explored to find out the feasibility of resolving above issues. It was proven that the optimized ionic conductivity of PTEC based electrolyte reached up to 1.12 × 10 −5 S cm −1 at 25 °C with a decent lithium ion transference number of 0.39 and a wide electrochemical window about 4.5 V vs. Li + /Li. In addition, the PTEC based Li/LiFePO 4 cell could be reversibly charged and discharged at 0.05 C-rates at ambient temperature. Moreover, the higher voltage Li/LiFe 0.2 Mn 0.8 PO 4 cell (cutoff voltage 4.35 V) possessed considerable rate capability and excellent cycling performance even at ambient temperature. Therefore, these carbonate-linked PEO electrolytes were demonstrated to be fascinating candidates for the next generation solid state lithium batteries simultaneously with high energy and high safety.

  16. 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)

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

    International Nuclear Information System (INIS)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed

    2005-01-01

    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)

  18. Cathodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Samson, Alfred Junio

    . High performance cathodes were obtained from strontium-doped lanthanum cobaltite (LSC) infiltrated - Ce0.9Gd0.1O1.95 (CGO) ionic conducting backbone. Systematic tuning of the CGO and LSC firing temperatures and LSC loading resulted in a cathode with low polarization resistance, Rp = 0.044 cm2 at 600......This dissertation focuses on the development of nanostructured cathodes for solid oxide fuel cells (SOFCs) and their performance at low operating temperatures. Cathodes were mainly fabricated by the infiltration method, whereby electrocatalysts are introduced onto porous, ionic conducting backbones...... with increasing LSC firing temperature, highlighting the importance of materials compability over higher ionic conductivity. The potential of Ca3Co4O9+delta as an electrocatalyst for SOFCs has also been explored and encouraging results were found i.e., Rp = 0.64 cm2 for a Ca3Co4O9+delta/CGO 50 vol % composite...

  19. Structural design considerations for micromachined solid-oxide fuel cells

    Science.gov (United States)

    Srikar, V. T.; Turner, Kevin T.; Andrew Ie, Tze Yung; Spearing, S. Mark

    Micromachined solid-oxide fuel cells (μSOFCs) are among a class of devices being investigated for portable power generation. Optimization of the performance and reliability of such devices requires robust, scale-dependent, design methodologies. In this first analysis, we consider the structural design of planar, electrolyte-supported, μSOFCs from the viewpoints of electrochemical performance, mechanical stability and reliability, and thermal behavior. The effect of electrolyte thickness on fuel cell performance is evaluated using a simple analytical model. Design diagrams that account explicitly for thermal and intrinsic residual stresses are presented to identify geometries that are resistant to fracture and buckling. Analysis of energy loss due to in-plane heat conduction highlights the importance of efficient thermal isolation in microscale fuel cell design.

  20. 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.

  1. Performance Characterization of Solid Oxide Cells Under High Pressure

    DEFF Research Database (Denmark)

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

    2015-01-01

    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......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...

  2. 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.

  3. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling...... electrode and 2-D gas transport models which have fewer unknown parameters for the same number of processes, (ii) use of a new model fitting algorithm, “multi-fitting”, in which multiple impedance spectra are fit simultaneously with parameters linked based on the variation of measurement conditions, (iii...

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

    Science.gov (United States)

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

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

  5. Thermal radiation modelling in a tubular solid oxide fuel cell

    International Nuclear Information System (INIS)

    Austin, M.E.; Pharoah, J.G.; Vandersteen, J.D.J.

    2004-01-01

    Solid Oxide Fuel Cells (SOFCs) are becoming the fuel cell of choice among companies and research groups interested in small power generation units. Questions still exist, however, about the operating characteristics of these devices; in particular the temperature distribution in the fuel cell. Using computational fluid dynamics (CFD) a model is proposed that incorporates conduction, convection and radiation. Both surface-to-surface and participating media are considered. It is hoped that a more accurate account of the temperature field in the various flow channels and cell components will be made to assist work on design of fuel cell components and reaction mechanisms. The model, when incorporating radiative heat transfer with participating media, predicts substantially lower operating temperatures and smaller temperature gradients than it does without these equations. It also shows the importance of the cathode air channel in cell cooling. (author)

  6. Performance characterization of solid oxide cells under high pressure

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...... hydrocarbon fuels, which is normally performed at high pressure to achieve a high yield. Operation of SOECs at elevated pressure will therefore facilitate integration with the downstream fuel synthesis and is furthermore advantageous as it increases the cell performance. In this work, recent pressurised test...... results of a planar Ni-YSZ (YSZ: Yttria stabilized Zirconia) supported solid oxide cell are presented. The test was performed at 800 °C at pressures up to 15 bar. A comparison of the electrochemical performance of the cell at 1 and 3 bar shows a significant and equal performance gain at higher pressure...

  7. High-temperature Raman spectroscopy of solid oxide fuel cell materials and processes.

    Science.gov (United States)

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

    2006-09-07

    Chemical and material processes occurring in high temperature environments are difficult to quantify due to a lack of experimental methods that can probe directly the species present. In this letter, Raman spectroscopy is shown to be capable of identifying in-situ and noninvasively changes in material properties as well as the formation and disappearance of molecular species on surfaces at temperatures of 715 degrees C. The material, yttria-stabilized zirconia or YSZ, and the molecular species, Ni/NiO and nanocrystalline graphite, factor prominently in the chemistry of solid oxide fuel cells (SOFCs). Experiments demonstrate the ability of Raman spectroscopy to follow reversible oxidation/reduction kinetics of Ni/NiO as well as the rate of carbon disappearance when graphite, formed in-situ, is exposed to a weakly oxidizing atmosphere. In addition, the Raman active phonon mode of YSZ shows a temperature dependent shift that correlates closely with the expansion of the lattice parameter, thus providing a convenient internal diagnostic for identifying thermal gradients in high temperature systems. These findings provide direct insight into processes likely to occur in operational SOFCs and motivate the use of in-situ Raman spectroscopy to follow chemical processes in these high-temperature, electrochemically active environments.

  8. Evaluation of oxidative DNA damage promoted by storage in sperm from sex-reversed rainbow trout.

    Science.gov (United States)

    Pérez-Cerezales, S; Martínez-Páramo, S; Cabrita, E; Martínez-Pastor, F; de Paz, P; Herráez, M P

    2009-03-01

    Short-term storage and cryopreservation of sperm are two common procedures in aquaculture, used for routine practices in artificial insemination reproduction and gene banking, respectively. Nevertheless, both procedures cause injuries affecting sperm motility, viability, cell structure and DNA stability, which diminish reproductive success. DNA modification is considered extremely important, especially when sperm storage is carried out with gene banking purposes. DNA damage caused by sperm storage is not well characterized and previous studies have reported simple and double strand breaks that have been attributed to oxidative events promoted by the generation of free radicals during storage. The objective of this study was to reveal DNA fragmentation and to explore the presence of oxidized bases that could be produced by oxidative events during short-term storage and cryopreservation in sex-reversed rainbow trout (Oncorhynchus mykiss) spermatozoa. Sperm from six males was analyzed separately. Different aliquots of the samples were stored 2h (fresh) or 5 days at 4 degrees C or were cryopreserved. Then spermatozoa were analyzed using the Comet assay, as well as combining this method with digestion with two endonucleases from Escherichia coli (Endonuclease III, that cut in oxidized cytosines, and FPG, cutting in oxidized guanosines). Both storage procedures yielded DNA fragmentation, but only short-term storage oxidative events were clearly detected, showing that oxidative processes affect guanosines rather than cytosines. Cryopreservation increases DNA fragmentation but the presence of oxidized bases was not noticed, suggesting that mechanisms other than oxidative stress could be involved in DNA fragmentation promoted by freezing.

  9. Small Systems Use of a Solid Arsenic Oxidizing Media in Place of Chemical Oxidation to Enhance Arsenic Removal

    Science.gov (United States)

    Presentation provides information on the need to oxidize As III to As V to increase arsenic removal followed by information on the results of an arsenic demonstration project (Plainview CDS) using a solid oxidizing media (Filox) to oxidize As III. The presentation includes a sho...

  10. Solid oxide fuel cells with bi-layered electrolyte structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinge; Robertson, Mark; Deces-Petit, Cyrille; Xie, Yongsong; Hui, Rob; Qu, Wei; Kesler, Olivera; Maric, Radenka; Ghosh, Dave [Institute for Fuel Cell Innovation, National Research Council Canada, 4250 Wesbrook Mall, Vancouver, B.C. V6T 1W5 (Canada)

    2008-01-10

    In this work, we have developed solid oxide fuel cells with a bi-layered electrolyte of 2 {mu}m SSZ and 4 {mu}m SDC using tape casting, screen printing, and co-firing processes. The cell reached power densities of 0.54 W cm{sup -2} at 650 C and 0.85 W cm{sup -2} at 700 C, with open circuit voltage (OCV) values larger than 1.02 V. The electrical leaking between anode and cathode through an SDC electrolyte has been blocked in the bi-layered electrolyte structure. However, both the electrolyte resistance (R{sub el}) and electrode polarization resistance (R{sub p,a+c}) increased in comparison to cells with single-layered SDC electrolytes. The formation of a solid solution of (Ce, Zr)O{sub 2-x} during sintering process and the flaws in the bi-layered electrolyte structure seem to be the main causes for the increase in the R{sub el} value (0.32 {omega} cm{sup 2}) at 650 C, which is almost one order of magnitude higher than the calculated value. (author)

  11. Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

    Science.gov (United States)

    Talic, Belma; Falk-Windisch, Hannes; Venkatachalam, Vinothini; Hendriksen, Peter Vang; Wiik, Kjell; Lein, Hilde Lea

    2017-06-01

    Manganese cobalt spinel oxides are promising materials for protective coatings for solid oxide fuel cell (SOFC) interconnects. To achieve high density such coatings are often sintered in a two-step procedure, involving heat treatment first in reducing and then in oxidizing atmospheres. Sintering the coating inside the SOFC stack during heating would reduce production costs, but may result in a lower coating density. The importance of coating density is here assessed by characterization of the oxidation kinetics and Cr evaporation of Crofer 22 APU with MnCo1.7Fe0.3O4 spinel coatings of different density. The coating density is shown to have minor influence on the long-term oxidation behavior in air at 800 °C, evaluated over 5000 h. Sintering the spinel coating in air at 900 °C, equivalent to an in-situ heat treatment, leads to an 88% reduction of the Cr evaporation rate of Crofer 22 APU in air-3% H2O at 800 °C. The air sintered spinel coating is initially highly porous, however, densifies with time in interaction with the alloy. A two-step reduction and re-oxidation heat treatment results in a denser coating, which reduces Cr evaporation by 97%.

  12. 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.

  13. Purification of reversibly oxidized proteins (PROP reveals a redox switch controlling p38 MAP kinase activity.

    Directory of Open Access Journals (Sweden)

    Dennis J Templeton

    2010-11-01

    Full Text Available Oxidation of cysteine residues of proteins is emerging as an important means of regulation of signal transduction, particularly of protein kinase function. Tools to detect and quantify cysteine oxidation of proteins have been a limiting factor in understanding the role of cysteine oxidation in signal transduction. As an example, the p38 MAP kinase is activated by several stress-related stimuli that are often accompanied by in vitro generation of hydrogen peroxide. We noted that hydrogen peroxide inhibited p38 activity despite paradoxically increasing the activating phosphorylation of p38. To address the possibility that cysteine oxidation may provide a negative regulatory effect on p38 activity, we developed a biochemical assay to detect reversible cysteine oxidation in intact cells. This procedure, PROP, demonstrated in vivo oxidation of p38 in response to hydrogen peroxide and also to the natural inflammatory lipid prostaglandin J2. Mutagenesis of the potential target cysteines showed that oxidation occurred preferentially on residues near the surface of the p38 molecule. Cysteine oxidation thus controls a functional redox switch regulating the intensity or duration of p38 activity that would not be revealed by immunodetection of phosphoprotein commonly interpreted as reflective of p38 activity.

  14. System Tb-Fe-O: thermodynamic properties of ternary oxides using solid-state electrochemical cells

    International Nuclear Information System (INIS)

    Rakshit, S.K.; Parida, S.C.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2003-01-01

    The standard molar Gibbs free energies of formation of TbFeO 3 (s) and Tb 3 Fe 5 O 12 (s) have been determined using solid-state electrochemical cell employing different solid electrolytes. The reversible emfs of the following solid-state electrochemical cells have been measured in the temperature range 1050≤T/K≤1250. Cell (I):(-)Pt/{TbFeO 3 (s)+Tb 2 O 3 (s)+Fe(s)}//YDT/CSZ//{Fe(s)+Fe 0.95 O(s)}/Pt(+))) (Cell (II):(-)Pt/{Fe(s)+Fe 0.95 O(s)}//CSZ//{TbFeO 3 (s)+Tb 3 Fe 5 O 12 (s)+Fe 3 O 4 (s)}/Pt(+) The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the emf data. The standard molar Gibbs free energies of formation of solid TbFeO 3 and Tb 3 Fe 5 O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by {Δ f G compfn m (TbFeO 3 ,s)/(kJ·mol -1 )±3.2}=-1357.5+0.2531·(T/K); (1050≤T/K≤1548);))and({Δ f G compfn m (Tb 3 Fe 5 O 12 ,s)/(kJ·mol -1 )±3.5}=-4901.7+ 0.9997·(T/K); (1050≤T/K≤1250).)) The uncertainty estimates for Δ f G compfn m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams were computed for the system Tb-Fe-O at T=1250 K

  15. Hydrogen Oxidation Reaction at the Ni/YSZ Anode of Solid Oxide Fuel Cells from First Principles

    Science.gov (United States)

    Cucinotta, Clotilde S.; Bernasconi, Marco; Parrinello, Michele

    2011-11-01

    By means of ab initio simulations we here provide a comprehensive scenario for hydrogen oxidation reactions at the Ni/zirconia anode of solid oxide fuel cells. The simulations have also revealed that in the presence of water chemisorbed at the oxide surface, the active region for H oxidation actually extends beyond the metal/zirconia interface unraveling the role of water partial pressure in the decrease of the polarization resistance observed experimentally.

  16. Proposal for processes map of post-consumption reverse logistics under the perspective of the national solid waste policy

    Directory of Open Access Journals (Sweden)

    Emmily Caroline Cabral da Fonseca

    2017-03-01

    Full Text Available The National Policy on Solid Waste (NPSW points to the Reverse Logistics (RL as an instrument that enables actions and strategies that allow adequate management of Urban Solid Waste (USW according to their guidelines. After more than five years of its publication, studies of RL in Brazil haven´t met the demands for defining procedures in the implementation of proper management of MSW in accordance with the NPSW. This class of waste is the result of post-consumer and it is relevant to clarify the relationship in their reverse processes in order to help the structuring and management of reverse channels that drive the waste to proper destination, in compliance with the law. Therefore, the objective of this research was to formalize, by means of theoretical study, the necessary processes, according to the literature research and legal guidelines, for the reverse channels through the proposal for a map of RL processes. For such, literature research, detailed reading of Law number 12.305 (NPSW and interviews with professionals working in the USW reverse channels were performed. The results converged on the proposition of a map of RL macro processes in which the processes identified were: collection, processing and delivery.

  17. 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.

  18. Fabrication and characterization of solid oxide cells for energy conversion and storage

    Science.gov (United States)

    Yang, Chenghao

    2011-12-01

    There has been an increasing interest in clean and renewable energy generation for highlighted energy and environmental concerns. Solid oxide cells (SOCs) have been considered as one of the promising technologies, since they can be operated efficiently both in electrolysis mode by generating hydrogen through steam electrolysis and fuel cell mode by electrochemically combining fuel with oxidant. The present work is devoted to performing a fundamental study of SOC in both fuel cell mode for power generation and electrolysis mode for fuel production. The research work on SOCs that can be operated reversibly for power generation and fuel production has been conducted in the following six projects: (1) High performance solid oxide electrolysis cell (SOEC) Fabrication of novel structured SOEC oxygen electrode with the conventional and commercial solid oxide fuel cell materials by screen-printing and infiltration fabrication methods. The microstructure, electrochemical properties and durability of SOECs has been investigated. It was found that the LSM infiltrated cell has an area specific resistance (ASR) of 0.20 Ω cm2 at 900°C at open circuit voltage with 50% absolute humidity (AH), which is relatively lower than that of the cell with LSM-YSZ oxygen electrode made by a conventional mixing method. Electrolysis cell with LSM infiltrated oxygen electrode has demonstrated stable performance under electrolysis operation with 0.33 A/cm2 and 50 vol.% AH at 800°C. (2) Advanced performance high temperature micro-tubular solid oxide fuel cell (MT-SOFC) Phase-inversion, dip-coating, high temperature co-sintering process and impregnation method were used to fabricate micro-tubular solid oxide fuel cell. The micro-structure of the micro-tubular fuel cell will be investigated and the power output and thermal robustness has been evaluated. High performance and rapid start-up behavior have been achieved, indicates that the MT-SOFC developed in this work can be a promising technology

  19. Studies on mixed metal oxides solid solutions as heterogeneous catalysts

    Directory of Open Access Journals (Sweden)

    H. R. Arandiyan

    2009-03-01

    Full Text Available In this work, a series of perovskite-type mixed oxide LaMo xV1-xO3+δ powder catalysts (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0, with 0.5 < δ < 1.5, prepared by the sol-gel process and calcined at 750ºC, provide an attractive and effective alternative means of synthesizing materials with better control of morphology. Structures of resins obtained during the gel formation process by FT-IR spectroscopy and XRD analysis showed that all the LaMo xV1-xO3+δ samples are single phase perovskite-type solid solutions. The surface area (BET between 2.5 - 5.0 m²/g (x = 0.1 and 1.0 respectively increases with increasing Mo ratio in the samples. They show high purity, good chemical homogeneity, and lower calcinations temperatures as compared with the solid-state chemistry route. SEM coupled to EDS and thermogravimetric analysis/differential thermal analyses (TGA/DTA have been carried out in order to evaluate the homogeneity of the catalyst. Finally, the experimental studies show that the calcination temperature and Mo content exhibited a significant influence on catalytic activity. Among the LaMo xV1-xO3+δ samples, LaMo0.7V0.3O4.2 showed the best catalytic activity for the topic reaction and the best activity and stability for ethane reforming at 850ºC under 8 bar.

  20. Advanced manufacturing of intermediate temperature, direct methane oxidation membrane electrode assemblies for durable solid oxide fuel cell, Phase I

    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...

  1. 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)

  2. Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    Xia Changrong; Zhang Yuelan; Liu Meilin

    2003-01-01

    Composites consisting of silver and yttria stabilized bismuth oxide (YSB) have been investigated as cathodes for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolytes. At 600 deg. C, the interfacial polarization resistances of a porous YSB-Ag cathode is about 0.3 Ω cm 2 , more than one order of magnitude smaller than those of other reported cathodes on stabilized zirconia. For example, the interfacial resistances of a traditional YSZ-lanthanum maganites composite cathode is about 11.4 Ω cm 2 at 600 deg. C. Impedance analysis indicated that the performance of an YSB-Ag composite cathode fired at 850 deg. C for 2 h is severely limited by gas transport due to insufficient porosity. The high performance of the YSB-Ag cathodes is very encouraging for developing honeycomb fuel cells to be operated at temperatures below 600 deg. C

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

    Science.gov (United States)

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

    2012-07-01

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

  4. Proposal for processes map of post-consumption reverse logistics under the perspective of the national solid waste policy

    OpenAIRE

    Emmily Caroline Cabral da Fonseca; Eriton Carlos Martins Barreiros; Paulo Vitor dos Santos Gonçalves; André Cristiano Silva Melo; Denilson Ricardo de Lucena Nunes

    2017-01-01

    The National Policy on Solid Waste (NPSW) points to the Reverse Logistics (RL) as an instrument that enables actions and strategies that allow adequate management of Urban Solid Waste (USW) according to their guidelines. After more than five years of its publication, studies of RL in Brazil haven´t met the demands for defining procedures in the implementation of proper management of MSW in accordance with the NPSW. This class of waste is the result of post-consumer and it is relev...

  5. Nitric oxide-related species-induced protein oxidation: reversible, irreversible, and protective effects on enzyme function of papain.

    Science.gov (United States)

    Väänänen, Antti J; Kankuri, Esko; Rauhala, Pekka

    2005-04-15

    Protein oxidation, irreversible modification, and inactivation may play key roles in various neurodegenerative disorders. Therefore, we studied the effects of the potentially in vivo occurring nitric oxide-related species on two different markers of protein oxidation: protein carbonyl generation on bovine serum albumine (BSA) and loss of activity of a cysteine-dependent protease, papain, in vitro by using Angeli's salt, papanonoate, SIN-1, and S-nitrosoglutathione (GSNO) as donors of nitroxyl, nitric oxide, peroxynitrite, and nitrosonium ions, respectively. Angeli's salt, SIN-1, and papanonoate (0-1000 microM) all generated a concentration-dependent increase in carbonyl formation on BSA (107, 60, and 45%, respectively). GSNO did not affect carbonyl formation. Papain was inhibited by Angeli's salt, SIN-1, papanonoate, and GSNO with IC50 values of 0.62, 2.3, 54, and 80 microM, respectively. Angeli's salt (3.16 microM)-induced papain inactivation was only partially reversible, while the effects of GSNO (316 microM) and papanonoate (316 microM) were reversible upon addition of excess DTT. The Angeli's salt-mediated DTT-irreversible inhibition of papain was prevented by GSNO or papanonoate pretreatment, hypothetically through mixed disulfide formation or S-nitrosylation of the catalytically critical thiol group of papain. These results, for the first time, compare the generation of carbonyls in proteins by Angeli's salt, papanonoate, and SIN-1. Furthermore, these results suggest that S-nitrosothiols may have a novel function in protecting critical thiols from irreversible oxidative damage.

  6. Extensively Reversible Thermal Transformations of a Bistable, Fluorescence-Switchable Molecular Solid: Entry into Functional Molecular Phase-Change Materials.

    Science.gov (United States)

    Srujana, P; Radhakrishnan, T P

    2015-06-15

    Functional phase-change materials (PCMs) are conspicuously absent among molecular materials in which the various attributes of inorganic solids have been realized. While organic PCMs are primarily limited to thermal storage systems, the amorphous-crystalline transformation of materials like Ge-Sb-Te find use in advanced applications such as information storage. Reversible amorphous-crystalline transformations in molecular solids require a subtle balance between robust supramolecular assembly and flexible structural elements. We report novel diaminodicyanoquinodimethanes that achieve this transformation by interlinked helical assemblies coupled with conformationally flexible alkoxyalkyl chains. They exhibit highly reversible thermal transformations between bistable (crystalline/amorphous) forms, along with a prominent switching of the fluorescence emission energy and intensity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 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.

  8. Zirconium oxide based ceramic solid electrolytes for oxygen detection

    International Nuclear Information System (INIS)

    Caproni, Erica

    2007-01-01

    Taking advantage of the high thermal shock resistance of zirconia-magnesia ceramics and the high oxide ion conductivity of zirconia-yttria ceramics, composites of these ceramics were prepared by mixing, pressing and sintering different relative concentrations of ZrO 2 : 8.6 mol% MgO and ZrO 2 : 3 mol% Y 2 O 3 solid electrolytes. Microstructural analysis of the composites was carried out by X-ray diffraction and scanning electron microscopy analyses. The thermal behavior was studied by dilatometric analysis. The electrical behavior was evaluated by the impedance spectroscopy technique. An experimental setup was designed for measurement the electrical signal generated as a function of the amount of oxygen at high temperatures. The main results show that these composites are partially stabilized (monoclinic, cubic and tetragonal) and the thermal behavior is similar to that of ZrO 2 : 8.6 mol% MgO materials used in disposable high temperature oxygen sensors. Moreover, the results of analysis of impedance spectroscopy show that the electrical conductivity of zirconia:magnesia is improved with zirconia-yttria addition and that the electrical signal depends on the amount of oxygen at 1000 deg C, showing that the ceramic composites can be used in oxygen sensors. (author)

  9. Solid state solubility of copper oxides in hydroxyapatite

    Science.gov (United States)

    Zykin, Mikhail A.; Vasiliev, Alexander V.; Trusov, Lev A.; Dinnebier, Robert E.; Jansen, Martin; Kazin, Pavel E.

    2018-06-01

    Samples containing copper oxide doped hydroxyapatite with the composition Ca10(PO4)6(CuxOH1-x-δ)2, x = 0.054 - 0.582, in the mixture with CuO/Cu2O were prepared by a solid-state high-temperature treatment at varying annealing temperatures and at different partial water vapor and oxygen pressures. The crystal structures of the apatite compounds were refined using powder X-ray diffraction patterns and the content of copper ions x in the apatite was determined. Copper ions enter exclusively into the apatite trigonal channels formally substituting protons of OH-groups and the hexagonal cell parameters grow approximately linearly with x, the channel volume mostly expanding while the remaining volume of the crystal lattice changing only slightly. The equilibrium copper content in the apatite increases drastically, by almost a factor of 10 with the annealing temperature rising from 800° to 1200°C. The reduction of the water partial pressure leads to a further increase of x, while the dependence of x on the oxygen partial pressure exhibits a maximum. The observed relations are consistent with the proposed chemical reactions implying the copper introduction is followed by the release of a considerable quantity of gaseous products - water and oxygen. The analysis of interatomic distances suggests that the maximum content of copper ions in the channel cannot exceed 2/3.

  10. 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.

  11. Performance Analysis and Development Strategies for Solid Oxide Fuel Cells

    International Nuclear Information System (INIS)

    Ivers-Tiffee, E; Leonide, A; Weber, A

    2011-01-01

    Solid oxide fuel cells (SOFC) are of great interest for a diverse range of applications. Within the past 10 years, an increase in power density by one order of magnitude, a lowering of the operating temperature by 200 K, and degradation rates lowered by a factor of 10 have been achieved on the cell and stack level. However, there is still room for further enhancement of the overall performance by suitably tailoring the cell components on a micro- and nanostructural level. The efficiency of the electrochemically active single cell is characterized by the linear ohmic losses within the electrolyte and by nonlinear polarization losses at the electrode-electrolyte interfaces. Both depend on material composition and operation conditions (temperature and time, fuel utilisation and gas composition). The area-specific resistance (ASR) is considered as the figure of merit for overall performance. ASR values of anode supported cells (ASC) were determined by means of impedance spectroscopy and subsequently separated into ohmic losses (mainly electrolyte) and nonlinear polarisation losses resulting from gas diffusion and activation polarization in the cathode and anode. The efficiencies of ASCs will be discussed for various material combinations in the temperature range of technological interest (between 550 deg. C and 850 deg. C).

  12. Investigation of aluminosilicate refractory for solid oxide fuel cell applications

    Science.gov (United States)

    Gentile, Paul Steven

    Stationary solid oxide fuel cells (SOFCs) have been demonstrated to provide clean and reliable electricity through electro-chemical conversion of various fuel sources (CH4 and other light hydrocarbons). To become a competitive conversion technology the costs of SOFCs must be reduced to less than $400/kW. Aluminosilicate represents a potential low cost alternative to high purity alumina for SOFC refractory applications. The objectives of this investigation are to: (1) study changes of aluminosilicate chemistry and morphology under SOFC conditions, (2) identify volatile silicon species released by aluminosilicates, (3) identify the mechanisms of aluminosilicate vapor deposition on SOFC materials, and (4) determine the effects of aluminosilicate vapors on SOFC electrochemical performance. It is shown thermodynamically and empirically that low cost aluminosilicate refractory remains chemically and thermally unstable under SOFC operating conditions between 800°C and 1000°C. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) of the aluminosilicate bulk and surface identified increased concentrations of silicon at the surface after exposure to SOFC gases at 1000°C for 100 hours. The presence of water vapor accelerated surface diffusion of silicon, creating a more uniform distribution. Thermodynamic equilibrium modeling showed aluminosilicate remains stable in dry air, but the introduction of water vapor indicative of actual SOFC gas streams creates low temperature (active anode interface.

  13. Thermal stress analysis of sulfur deactivated solid oxide fuel cells

    Science.gov (United States)

    Zeng, Shumao; Parbey, Joseph; Yu, Guangsen; Xu, Min; Li, Tingshuai; Andersson, Martin

    2018-03-01

    Hydrogen sulfide in fuels can deactivate catalyst for solid oxide fuel cells, which has become one of the most critical challenges to stability. The reactions between sulfur and catalyst will cause phase changes, leading to increase in cell polarization and mechanical mismatch. A three-dimensional computational fluid dynamics (CFD) approach based on the finite element method (FEM) is thus used to investigate the polarization, temperature and thermal stress in a sulfur deactivated SOFC by coupling equations for gas-phase species, heat, momentum, ion and electron transport. The results indicate that sulfur in fuels can strongly affect the cell polarization and thermal stresses, which shows a sharp decrease in the vicinity of electrolyte when 10% nickel in the functional layer is poisoned, but they remain almost unchanged even when the poisoned Ni content was increased to 90%. This investigation is helpful to deeply understand the sulfur poisoning effects and also benefit the material design and optimization of electrode structure to enhance cell performance and lifetimes in various hydrocarbon fuels containing impurities.

  14. 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.

  15. Coupling Solid Oxide Electrolyser (SOE) and ammonia production plant

    International Nuclear Information System (INIS)

    Cinti, Giovanni; Frattini, Domenico; Jannelli, Elio; Desideri, Umberto; Bidini, Gianni

    2017-01-01

    Highlights: • An innovative NH 3 production plant was designed. • CO 2 emissions and energy consumption are studied in three different designs. • High temperature electrolysis allows to achieve high efficiency and heat recovery. • The coupling permits storage of electricity into a liquid carbon free chemical. - Abstract: Ammonia is one of the most produced chemicals worldwide and is currently synthesized using nitrogen separated from air and hydrogen from natural gas reforming with consequent high consumption of fossil fuel and high emission of CO 2 . A renewable path for ammonia production is desirable considering the potential development of ammonia as energy carrier. This study reports design and analysis of an innovative system for the production of green ammonia using electricity from renewable energy sources. This concept couples Solid Oxide Electrolysis (SOE), for the production of hydrogen, with an improved Haber Bosch Reactor (HBR), for ammonia synthesis. An air separator is also introduced to supply pure nitrogen. SOE operates with extremely high efficiency recovering high temperature heat from the Haber-Bosch reactor. Aspen was used to develop a model to study the performance of the plant. Both the SOE and the HBR operate at 650 °C. Ammonia production with zero emission of CO 2 can be obtained with a reduction of 40% of power input compared to equivalent plants.

  16. 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...

  17. Internal reforming of methane in solid oxide fuel cell systems

    Science.gov (United States)

    Peters, R.; Dahl, R.; Klüttgen, U.; Palm, C.; Stolten, D.

    Internal reforming is an attractive option offering a significant cost reduction, higher efficiencies and faster load response of a solid oxide fuel cell (SOFC) power plant. However, complete internal reforming may lead to several problems which can be avoided with partial pre-reforming of natural gas. In order to achieve high total plant efficiency associated with low energy consumption and low investment costs, a process concept has been developed based on all the components of the SOFC system. In the case of anode gas recycling an internal steam circuit exists. This has the advantage that there is no need for an external steam generator and the steam concentration in the anode gas is reduced. However, anode gas recycling has to be proven by experiments in a pre-reformer and for internal reforming. The addition of carbon dioxide clearly shows a decrease in catalyst activity, while for temperatures higher than 1000 K hydrogen leads to an increase of the measured methane conversion rates.

  18. Constrained Sintering in Fabrication of Solid Oxide Fuel Cells.

    Science.gov (United States)

    Lee, Hae-Weon; Park, Mansoo; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook

    2016-08-09

    Solid oxide fuel cells (SOFCs) are inevitably affected by the tensile stress field imposed by the rigid substrate during constrained sintering, which strongly affects microstructural evolution and flaw generation in the fabrication process and subsequent operation. In the case of sintering a composite cathode, one component acts as a continuous matrix phase while the other acts as a dispersed phase depending upon the initial composition and packing structure. The clustering of dispersed particles in the matrix has significant effects on the final microstructure, and strong rigidity of the clusters covering the entire cathode volume is desirable to obtain stable pore structure. The local constraints developed around the dispersed particles and their clusters effectively suppress generation of major process flaws, and microstructural features such as triple phase boundary and porosity could be readily controlled by adjusting the content and size of the dispersed particles. However, in the fabrication of the dense electrolyte layer via the chemical solution deposition route using slow-sintering nanoparticles dispersed in a sol matrix, the rigidity of the cluster should be minimized for the fine matrix to continuously densify, and special care should be taken in selecting the size of the dispersed particles to optimize the thermodynamic stability criteria of the grain size and film thickness. The principles of constrained sintering presented in this paper could be used as basic guidelines for realizing the ideal microstructure of SOFCs.

  19. Challenge for lowering concentration polarization in solid oxide fuel cells

    Science.gov (United States)

    Shimada, Hiroyuki; Suzuki, Toshio; Yamaguchi, Toshiaki; Sumi, Hirofumi; Hamamoto, Koichi; Fujishiro, Yoshinobu

    2016-01-01

    In the scope of electrochemical phenomena, concentration polarization at electrodes is theoretically inevitable, and lowering the concentration overpotential to improve the performance of electrochemical cells has been a continuing challenge. Electrodes with highly controlled microstructure, i.e., high porosity and uniform large pores are therefore essential to achieve high performance electrochemical cells. In this study, state-of-the-art technology for controlling the microstructure of electrodes has been developed for realizing high performance support electrodes of solid oxide fuel cells (SOFCs). The key is controlling the porosity and pore size distribution to improve gas diffusion, while maintaining the integrity of the electrolyte and the structural strength of actual sized electrode supports needed for the target application. Planar anode-supported SOFCs developed in this study realize 5 μm thick dense electrolyte (yttria-stabilized zirconia: YSZ) and the anode substrate (Ni-YSZ) of 53.6 vol.% porosity with a large median pore diameter of 0.911 μm. Electrochemical measurements reveal that the performance of the anode-supported SOFCs improves with increasing anode porosity. This Ni-YSZ anode minimizes the concentration polarization, resulting in a maximum power density of 3.09 W cm-2 at 800 °C using humidified hydrogen fuel without any electrode functional layers.

  20. Constrained Sintering in Fabrication of Solid Oxide Fuel Cells

    Science.gov (United States)

    Lee, Hae-Weon; Park, Mansoo; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook

    2016-01-01

    Solid oxide fuel cells (SOFCs) are inevitably affected by the tensile stress field imposed by the rigid substrate during constrained sintering, which strongly affects microstructural evolution and flaw generation in the fabrication process and subsequent operation. In the case of sintering a composite cathode, one component acts as a continuous matrix phase while the other acts as a dispersed phase depending upon the initial composition and packing structure. The clustering of dispersed particles in the matrix has significant effects on the final microstructure, and strong rigidity of the clusters covering the entire cathode volume is desirable to obtain stable pore structure. The local constraints developed around the dispersed particles and their clusters effectively suppress generation of major process flaws, and microstructural features such as triple phase boundary and porosity could be readily controlled by adjusting the content and size of the dispersed particles. However, in the fabrication of the dense electrolyte layer via the chemical solution deposition route using slow-sintering nanoparticles dispersed in a sol matrix, the rigidity of the cluster should be minimized for the fine matrix to continuously densify, and special care should be taken in selecting the size of the dispersed particles to optimize the thermodynamic stability criteria of the grain size and film thickness. The principles of constrained sintering presented in this paper could be used as basic guidelines for realizing the ideal microstructure of SOFCs. PMID:28773795

  1. 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.

  2. 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.

  3. 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...

  4. Reverse logistics network for municipal solid waste management: The inclusion of waste pickers as a Brazilian legal requirement.

    Science.gov (United States)

    Ferri, Giovane Lopes; Chaves, Gisele de Lorena Diniz; Ribeiro, Glaydston Mattos

    2015-06-01

    This study proposes a reverse logistics network involved in the management of municipal solid waste (MSW) to solve the challenge of economically managing these wastes considering the recent legal requirements of the Brazilian Waste Management Policy. The feasibility of the allocation of MSW material recovery facilities (MRF) as intermediate points between the generators of these wastes and the options for reuse and disposal was evaluated, as well as the participation of associations and cooperatives of waste pickers. This network was mathematically modelled and validated through a scenario analysis of the municipality of São Mateus, which makes the location model more complete and applicable in practice. The mathematical model allows the determination of the number of facilities required for the reverse logistics network, their location, capacities, and product flows between these facilities. The fixed costs of installation and operation of the proposed MRF were balanced with the reduction of transport costs, allowing the inclusion of waste pickers to the reverse logistics network. The main contribution of this study lies in the proposition of a reverse logistics network for MSW simultaneously involving legal, environmental, economic and social criteria, which is a very complex goal. This study can guide practices in other countries that have realities similar to those in Brazil of accelerated urbanisation without adequate planning for solid waste management, added to the strong presence of waste pickers that, through the characteristic of social vulnerability, must be included in the system. In addition to the theoretical contribution to the reverse logistics network problem, this study aids in decision-making for public managers who have limited technical and administrative capacities for the management of solid wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Reverse Stability Kinetics of Meat Pigment Oxidation in Aqueous Extract from Fresh Beef.

    Science.gov (United States)

    Frelka, John C; Phinney, David M; Wick, Macdonald P; Heldman, Dennis R

    2017-12-01

    The use of kinetic models is an evolving approach to describing quality changes in foods during processes, including storage. Previous studies indicate that the oxidation rate of myoglobin is accelerated under frozen storage conditions, a phenomenon termed reverse stability. The goal of this study was to develop a model for meat pigment oxidation to incorporate the phenomenon of reverse stability. In this investigation, the model system was an aqueous extract from beef which was stored under a range of temperatures, both unfrozen and frozen. The kinetic analysis showed that in unfrozen solutions, the temperature dependence of oxidation rate followed Arrhenius kinetics. However, under in frozen solutions the rate of oxidation increased with decreasing temperature until reaching a local maximum around -20 °C. The addition of NaCl to the model system increased oxidation rates at all temperatures, even above the initial freezing temperature. This observation suggests that this reaction is dependent on the ionic strength of the solution as well as temperature. The mechanism of this deviant kinetic behavior is not fully understood, but this study shows that the interplay of temperature and composition on the rate of oxidation of meat pigments is complicated and may involve multiple mechanisms. A better understanding of the kinetics of quality loss in a meat system allows for a re-examination of the current recommendations for frozen storage. The deviant kinetic behavior observed in this study indicates that the relationship between quality loss and temperature in a frozen food is not as simple as once thought. Product-specific recommendations could be implemented in the future that would allow for a decrease in energy consumption without a significant loss of quality. © 2017 Institute of Food Technologists®.

  6. Electro-oxidation of reverse osmosis concentrates generated in tertiary water treatment.

    Science.gov (United States)

    Pérez, G; Fernández-Alba, A R; Urtiaga, A M; Ortiz, I

    2010-05-01

    This work investigates the application of the electro-oxidation technology provided with boron doped diamond (BDD), an electrode material which has shown outstanding properties in oxidation of organic and inorganic compounds, for the treatment of reverse osmosis (RO) concentrates generated in tertiary wastewater treatment plants (WWTP). Chemical oxygen demand (COD), ammonium and several anions were measured during the electro-oxidation process, and the influence of the applied current density (20-200A/m(2)) was analysed on process kinetics. Analytical assessment showed that several emerging pollutants (pharmaceuticals, personal care products, stimulants, etc.) were presented both in the effluent of the secondary WWTP as well as in the RO concentrate. For this reason, a group of 10 emerging pollutants, those found with higher concentrations, was selected in order to test whether electro-oxidation can be also applied for their mitigation. In the removal of emerging pollutants the electrical current density in the range 20-100A/m(2) did not show influence likely due to the mass transfer resistance developed in the process when the oxidized solutes are present in such low concentrations. Their removal rates were fitted to first order expressions, and the apparent kinetic constants for the anodic oxidation of each compound were calculated. Finally, the formation of trihalomethanes (THMs) has been checked; concluding that after selecting the appropriate operational conditions the attained concentration is lower than the standards for drinking water established in European and EPA regulations. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  7. Recycling of end-of-life reverse osmosis membranes by oxidative treatment: a technical evaluation.

    Science.gov (United States)

    Coutinho de Paula, Eduardo; Gomes, Júlia Célia Lima; Amaral, Míriam Cristina Santos

    2017-07-01

    The adverse impacts caused by the disposal of thousands of tonnes per annum of reverse osmosis (RO) membranes modules have grown dramatically around the world. The objective of this study was to evaluate the technical feasibility of recycling by chemical oxidation of end-of-life RO membranes for applications in other separation processes with specifications less rigorous. The recycling technique consisted in to cause a membrane exposition with oxidant solutions in order to remove its aromatic polyamide layer and subsequent conversion to a porous membrane. The recycling technique was evaluated by water permeability and salt rejection tests before and after the oxidative treatments. Initially, membranes' chemical cleaning and pretreatment procedures were assessed. Among factors evaluated, the oxidizing agent, its concentration and pH, associated with the oxidative treatment time, showed important influence on the oxidation of the membranes. Results showed that sodium hypochlorite and potassium permanganate are efficient agents for the membrane recycling. The great increased permeability and decreased salt rejection indicated changes on membranes' selective properties. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and contact angle characterization techniques revealed marked changes on the main membranes' physical-chemical properties, such as morphology, roughness and hydrophobicity. Reuse of produced effluents and fouling tendency of recycled membranes were also evaluated.

  8. Properties of Copper Doped Neodymium Nickelate Oxide as Cathode Material for Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Lee Kyoung-Jin

    2016-06-01

    Full Text Available Mixed ionic and electronic conducting K2NiF4-type oxide, Nd2Ni1-xCuxO4+δ (x=0~1 powders were synthesized by solid state reaction technique and solid oxide fuel cells consisting of a Nd2Ni1-xCuxO4+δ cathode, a Ni-YSZ anode and ScSZ as an electrolyte were fabricated. The effect of copper substitution for nickel on the electrical and electrochemical properties was examined. Small amount of copper doping (x=0.2 resulted in the increased electrical conductivity and decreased polarization resistance. It appears that this phenomenon was associated with the high mean valence of nickel and copper and the resulting excess oxygen (δ. It was found that power densities of the cell with the Nd2Ni1-xCuxO4+δ (x=0.1 and 0.2 cathode were higher than that of the cell with the Nd2NiO4+δ cathode.

  9. Structural analysis of nickel doped cerium oxide catalysts for fuel reforming in solid oxide fuel cells

    Science.gov (United States)

    Cavendish, Rio

    As world energy demands increase, research into more efficient energy production methods has become imperative. Heterogeneous catalysis and nanoscience are used to promote chemical transformations important for energy production. These concepts are important in solid oxide fuel cells (SOFCs) which have attracted attention because of their potential to provide an efficient and environmentally favorable power generation system. The SOFC is also fuel-flexible with the ability to run directly on many fuels other than hydrogen. Internal fuel reforming directly in the anode of the SOFC would greatly reduce the cost and complexity of the device. Methane is the simplest hydrocarbon and a main component in natural gas, making it useful when testing catalysts on the laboratory scale. Nickel (Ni) and gadolinium (Gd) doped ceria (CeO 2) catalysts for potential use in the SOFC anode were synthesized with a spray drying method and tested for catalytic performance using partial oxidation of methane and steam reforming. The relationships between catalytic performance and structure were then investigated using X-ray diffraction, transmission electron microscopy, and environmental transmission electron microscopy. The possibility of solid solutions, segregated phases, and surface layers of Ni were explored. Results for a 10 at.% Ni in CeO2 catalyst reveal a poor catalytic behavior while a 20 at.% Ni in CeO2 catalyst is shown to have superior activity. The inclusion of both 10 at.% Gd and 10 at.% Ni in CeO2 enhances the catalytic performance. Analysis of the presence of Ni in all 3 samples reveals Ni heterogeneity and little evidence for extensive solid solution doping. Ni is found in small domains throughout CeO2 particles. In the 20 at.% Ni sample a segregated, catalytically active NiO phase is observed. Overall, it is found that significant interaction between Ni and CeO2 occurs that could affect the synthesis and functionality of the SOFC anode.

  10. 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...

  11. Verapamil reverses PTH- or CRF-induced abnormal fatty acid oxidation in muscle

    International Nuclear Information System (INIS)

    Perna, A.F.; Smogorzewski, M.; Massry, S.G.

    1988-01-01

    Chronic renal failure (CRF) is associated with impaired long chain fatty acids (LCFA) oxidation by skeletal muscle mitochondria. This is due to reduced activity of carnitine palmitoyl transferase (CPT). These derangements were attributed to the secondary hyperparathyroidism of CRF, since prior parathyroidectomy in CRF rats reversed these abnormalities and PTH administration to normal rats reproduced them. It was proposed that these effects of PTH are mediated by its ionophoric property leading to increased entry of calcium into skeletal muscle. A calcium channel blocker may, therefore, correct these derangements. The present study examined the effects of verapamil on LCFA oxidation, CPT activity by skeletal muscle mitochondria, and 45 Ca uptake by skeletal muscle obtained from CRF rats and normal animals treated with PTH with and without verapamil. Both four days of PTH administration and 21 days of CRF produced significant (P less than 0.01) reduction in LCFA oxidation and CPT activity of skeletal muscle mitochondria, and significant (P less than 0.01) increment in 45 Ca uptake by skeletal muscle. Simultaneous treatment with verapamil corrected all these derangements. Administration of verapamil alone to normal rats did not cause a significant change in any of these parameters. The data are consistent with the proposition that the alterations in LCFA in CRF or after PTH treatment are related to the ionophoric action of the hormone and could be reversed by a calcium channel blocker

  12. High Temperature Oxidation of Ferritic Steels for Solid Oxide Electrolysis Stacks

    DEFF Research Database (Denmark)

    Molin, Sebastian; Chen, Ming; Bentzen, Janet Jonna

    2013-01-01

    atmospheres at 800°C. Four commercially available alloys: Crofer 22 APU, Crofer 22 H, AL29-4, E-Brite were characterized in humidified hydrogen. One alloy, Crofer 22 APU was also characterized in pure oxygen both in the as-prepared state and after application of a protective coating. Best corrosion resistance......Oxidation rates of ferritic steels used as interconnector plates in Solid Oxide Electrolysis Stacks are of concern as they may be determining for the life time of the technology. In this study oxidation experiments were carried out for up to 1000 hours in hydrogen-side and oxygen-side simulated...... in humidified hydrogen atmosphere was observed for Crofer 22 APU and Crofer 22 H alloys. Corrosion rates for Crofer 22 APU measured in humidified hydrogen are similar to the corrosion rates measured in air. Both coatings of plasma sprayed LSM and dual layer coatings (Co3O4/LSM-Co3O4) applied by wet spraying...

  13. Development of Lithium Stuffed Garnet-Type Oxide Solid Electrolytes with High Ionic Conductivity for Application to All-Solid-State Batteries

    Directory of Open Access Journals (Sweden)

    Ryoji Inada

    2016-07-01

    Full Text Available All-solid-state lithium-ion battery (LiB is expected as one of the next generation energy storage devices because of their high energy density, high safety and excellent cycle stability. Although oxide-based solid electrolyte materials have rather lower conductivity and poor deformability than sulfide-based one, they have other advantages such as their chemical stability and easiness for handling. Among the various oxide-based SEs, lithium stuffed garnet-type oxide with the formula of Li7La3Zr2O12 (LLZ have been widely studied because of their high conductivity above 10-4 Scm-1 at room temperature, excellent thermal performance and stability against Li metal anode.Here, we present our recent progress for the development of garnet-type solid electrolytes with high conductivity by simultaneous substitution of Ta5+ into Zr4+ site and Ba2+ into La3+ site in LLZ. Li+ concentration was fixed to 6.5 per chemical formulae, so that the formulae of our Li garnet-type oxide is expressed as Li6.5La3-xBaxZr1.5-xTa0.5+xO12 (LLBZT and Ba contents x are changed from 0 to 0.3. As results, all LLBZT samples have cubic garnet structure without containing any secondary phases. The lattice parameters of LLBZT decrease with increasing Ba2+ contents x < 0.10 while increase with x from 0.10 to 0.30, possibly due to the simultaneous change of Ba2+ and Ta5+ substitution levels. Relative densities of LLBZT are in the range between 89% and 93% and not influenced so much by the compositions. From AC impedance spectroscopy measurements, the total (bulk + grain conductivity at 27ºC of LLBZT shows its maximum value of 8.34 x 10-4 S cm-1 at x = 0.10, which is slightly higher than the conductivity (= 7.94 x 10-4 S cm-1 of LLZT without substituting Ba (x = 0. Activation energy of the conductivity tends to become lower by Ba substation, while excess Ba substitution degrades the conductivity in LLBZT. LLBZT has wide electrochemical potential window of 0-6 V vs. Li+/Li and

  14. 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)

  15. Mathematical modeling of oxygen transport in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Ann Mari

    1997-12-31

    This thesis develops mathematical models to describe the electrochemical performance of a solid oxide fuel cell cathode based on electrochemical kinetics and mass transfer. The individual effects of various coupled processes are investigated. A one-dimensional model is developed based on porous electrode theory. Two different mechanisms are investigated for the charge transfer reaction. One of these assumes that intermediately adsorbed oxygen atoms are reduced at the electrode/electrolyte interface, similar to the models proposed for metal electrodes. Simulated polarization curves exhibit limited currents due to depletion of oxygen adsorbates at high cathodic overvoltages. An empirical correlation is confirmed to exist between the limiting current an the oxygen partial pressure, however, a similar correlation often assumed to exist between the measured polarization resistance and the oxygen partial pressure could not be justified. For the other model, oxygen vacancies are assumed to be exchanged directly at the electrode/electrolyte interface. The electrochemical behaviour is improved by reducing the oxygen partial pressure, due to increased vacancy concentration of the electrode material. Simulated polarization curves exhibit Tafel-like slopes in the cathodic direction, which are due to polarization concentration, and not activation polarization in the conventional sense. Anodic limiting currents are predicted due to lack of available free sites for vacancy exchange at the cathode side. The thesis also presents a theoretical treatment of current and potential distributions in simple two-dimensional cell geometries, and a two-dimensional model for a porous electrode-electrolyte system for investigation of the effect of interfacial diffusion of adsorbates along the electrode/electrolyte interface. 172 refs., 60 figs., 11 tabs.

  16. Solid oxide fuel cells towards real life applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    2010-07-01

    Solid Oxide Fuel Cells offer a clean and efficient way of producing electricity and heat from a wide selection of fuels. The project addressed three major challenges to be overcome by the technology to make commercialisation possible. (1) At the cell level, increased efficiency combined with production cost reduction has been achieved through an optimization of the manufacturing processes, b) by using alternative raw materials with a lower purchase price and c) by introducing a new generation of fuel cells with reduced loss and higher efficiency. (2) At the stack level, production cost reduction is reduced and manufacturing capacity is increased through an optimization of the stack production. (3) At the system level, development of integrated hotbox concepts for the market segments distributed generation (DG), micro combined heat and power (mCHP), and auxiliary power units (APU) have been developed. In the mCHP segment, two concepts have been developed and validated with regards to market requirements and scalability. In the APU-segment, different types of reformers have been tested and it has been proven that diesel can be reformed through appropriate reformers. Finally, operation experience and feedback has been gained by deployment of stacks in the test facility at the H.C. OErsted Power Plant (HCV). This demonstration has been carried out in collaboration between TOFC and DONG Energy Power A/S (DONG), who has participated as a subcontractor to TOFC. The demonstration has given valuable knowledge and experience with design, start-up and operation of small power units connected to the grid and future development within especially the mCHP segment will benefit from this. In this report, the project results are described for each of the work packages in the project. (Author)

  17. 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

  18. Efficient and Scalable Fabrication of Solid Oxide Fuel Cells via 3D-Printing

    Data.gov (United States)

    National Aeronautics and Space Administration — Although solid oxide fuel cells (SOFCs) are a source of both efficient and clean electricity, the brittle ceramic materials which comprise them are difficult to form...

  19. Novel quasi-symmetric solid oxide fuel cells with enhanced electrochemical performance

    KAUST Repository

    Chen, Yonghong; Cheng, Zhuanxia; Yang, Yang; Gu, Qingwen; Tian, Dong; Lu, Xiaoyong; Yu, Weili; Lin, Bin

    2016-01-01

    Symmetrical solid oxide fuel cell (SSOFC) using same materials as both anode and cathode simultaneously has gained extensively attentions, which can simplify fabrication process, minimize inter-diffusion between components, enhance sulfur and coking

  20. Solid Oxide Fuel Cell Based Upon Colloidal Deposition of Thin Films for Lower Temperature Operation (Preprint)

    National Research Council Canada - National Science Library

    Reitz, T. L; Xiao, H

    2006-01-01

    In order to reduce the operating temperature of solid oxide fuel cells (SOFCs), anode-supported cells incorporating thin film electrolytes in conjunction with anode/electrolyte and cathode/electrolyte interlayers were studied...

  1. Microstructural evolution of nanograin nickel-zirconia cermet anode materials for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    Nayak, Bibhuti Bhusan

    2012-01-01

    The aim of the study is to study the structure, microstructure, porosity, thermal expansion, electrical conductivity and electrochemical behavior of the anode material thus synthesized in order to find its suitability for solid oxide fuel cell (SOFC) anode application

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

    KAUST Repository

    Da’ as, Eman H.

    2015-01-01

    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

  3. A Compact, Efficient Pyrolysis/Oxidation System for Solid Waste Resource Recovery in Space, Phase I

    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...

  4. Electrode Reaction Pathway in Oxide Anode for Solid Oxide Fuel Cells

    Science.gov (United States)

    Li, Wenyuan

    Oxide anodes for solid oxide fuel cells (SOFC) with the advantage of fuel flexibility, resistance to coarsening, small chemical expansion and etc. have been attracting increasing interest. Good performance has been reported with a few of perovskite structure anodes, such as (LaSr)(CrMn)O3. However, more improvements need to be made before meeting the application requirement. Understanding the oxidation mechanism is crucial for a directed optimization, but it is still on the early stage of investigation. In this study, reaction mechanism of oxide anodes is investigated on doped YCrO 3 with H2 fuel, in terms of the origin of electrochemical activity, rate-determining steps (RDS), extension of reactive zone, and the impact from overpotential under service condition to those properties. H2 oxidation on the YCs anodes is found to be limited by charge transfer and H surface diffusion. A model is presented to describe the elementary steps in H2 oxidation. From the reaction order results, it is suggested that any models without taking H into the charge transfer step are invalid. The nature of B site element determines the H2 oxidation kinetics primarily. Ni displays better adsorption ability than Co. However, H adsorption ability of such oxide anode is inferior to that of Ni metal anode. In addition, the charge transfer step is directly associated with the activity of electrons in the anode; therefore it can be significantly promoted by enhancement of the electron activity. It is found that A site Ca doping improves the polarization resistance about 10 times, by increasing the activity of electrons to promote the charge transfer process. For the active area in the oxide anode, besides the traditional three-phase boundary (3PB), the internal anode surface as two-phase boundary (2PB) is proven to be capable of catalytically oxidizing the H2 fuel also when the bulk lattice is activated depending on the B site elements. The contribution from each part is estimated by switching

  5. 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...... infiltrated with Sr0.99Fe0.75Mo0.25O3-δ (SFM), the electronic conductivity wasenhanced. However, polarization resistance of the cells increased,suggesting that the infiltrated material is less electro-catalyticallyactive and was partly blocking the CGO surface reaction sites. Theactivity could be regained...... by infiltrating nano-sized CGO orNiCGO on top of SFM, while still sustaining the high electronicconductivity. Ohmic resistance of the electrodes was thuspractically eliminated and performance comparable to, or betterthan, state-of-the-art fuel electrodes was achieved. The Nicontaining cells were damaged by carbon...

  6. Reverse logistics network for municipal solid waste management: The inclusion of waste pickers as a Brazilian legal requirement

    Energy Technology Data Exchange (ETDEWEB)

    Ferri, Giovane Lopes, E-mail: giovane.ferri@aluno.ufes.br [Department of Engineering and Technology, Federal University of Espírito Santo – UFES, Rodovia BR 101 Norte, Km 60, Bairro Litorâneo, São Mateus, ES, 29.932-540 (Brazil); Diniz Chaves, Gisele de Lorena, E-mail: gisele.chaves@ufes.br [Department of Engineering and Technology, Federal University of Espírito Santo – UFES, Rodovia BR 101 Norte, Km 60, Bairro Litorâneo, São Mateus, ES, 29.932-540 (Brazil); Ribeiro, Glaydston Mattos, E-mail: glaydston@pet.coppe.ufrj.br [Transportation Engineering Programme, Federal University of Rio de Janeiro – UFRJ, Centro de Tecnologia, Bloco H, Sala 106, Cidade Universitária, Rio de Janeiro, 21949-900 (Brazil)

    2015-06-15

    Highlights: • We propose a reverse logistics network for MSW involving waste pickers. • A generic facility location mathematical model was validated in a Brazilian city. • The results enable to predict the capacity for screening and storage centres (SSC). • We minimise the costs for transporting MSW with screening and storage centres. • The use of SSC can be a potential source of revenue and a better use of MSW. - Abstract: This study proposes a reverse logistics network involved in the management of municipal solid waste (MSW) to solve the challenge of economically managing these wastes considering the recent legal requirements of the Brazilian Waste Management Policy. The feasibility of the allocation of MSW material recovery facilities (MRF) as intermediate points between the generators of these wastes and the options for reuse and disposal was evaluated, as well as the participation of associations and cooperatives of waste pickers. This network was mathematically modelled and validated through a scenario analysis of the municipality of São Mateus, which makes the location model more complete and applicable in practice. The mathematical model allows the determination of the number of facilities required for the reverse logistics network, their location, capacities, and product flows between these facilities. The fixed costs of installation and operation of the proposed MRF were balanced with the reduction of transport costs, allowing the inclusion of waste pickers to the reverse logistics network. The main contribution of this study lies in the proposition of a reverse logistics network for MSW simultaneously involving legal, environmental, economic and social criteria, which is a very complex goal. This study can guide practices in other countries that have realities similar to those in Brazil of accelerated urbanisation without adequate planning for solid waste management, added to the strong presence of waste pickers that, through the

  7. Reverse logistics network for municipal solid waste management: The inclusion of waste pickers as a Brazilian legal requirement

    International Nuclear Information System (INIS)

    Ferri, Giovane Lopes; Diniz Chaves, Gisele de Lorena; Ribeiro, Glaydston Mattos

    2015-01-01

    Highlights: • We propose a reverse logistics network for MSW involving waste pickers. • A generic facility location mathematical model was validated in a Brazilian city. • The results enable to predict the capacity for screening and storage centres (SSC). • We minimise the costs for transporting MSW with screening and storage centres. • The use of SSC can be a potential source of revenue and a better use of MSW. - Abstract: This study proposes a reverse logistics network involved in the management of municipal solid waste (MSW) to solve the challenge of economically managing these wastes considering the recent legal requirements of the Brazilian Waste Management Policy. The feasibility of the allocation of MSW material recovery facilities (MRF) as intermediate points between the generators of these wastes and the options for reuse and disposal was evaluated, as well as the participation of associations and cooperatives of waste pickers. This network was mathematically modelled and validated through a scenario analysis of the municipality of São Mateus, which makes the location model more complete and applicable in practice. The mathematical model allows the determination of the number of facilities required for the reverse logistics network, their location, capacities, and product flows between these facilities. The fixed costs of installation and operation of the proposed MRF were balanced with the reduction of transport costs, allowing the inclusion of waste pickers to the reverse logistics network. The main contribution of this study lies in the proposition of a reverse logistics network for MSW simultaneously involving legal, environmental, economic and social criteria, which is a very complex goal. This study can guide practices in other countries that have realities similar to those in Brazil of accelerated urbanisation without adequate planning for solid waste management, added to the strong presence of waste pickers that, through the

  8. SOCTESQA - Solid Oxide Cell and Stack Testing, Safety and Quality Assurance

    OpenAIRE

    Lang, Michael; Auer, Corinna; Couturier, Karine; Nielsen, Eva Ravn; Mc Phail, Stephen; Kotsionopoulos, Nikolaos; FU, Qingxi; Liu, Qinglin

    2015-01-01

    For the successful market penetration of high temperature solid oxide fuel/electrolysis cell energy systems it is necessary to increase the quality assurance and the reliable assessment of the corresponding cells and stacks. Therefore in May 2014 the EU-funded project SOCTESQA was launched. Partners from different countries in Europe and one external party from Singapore are working together to develop uniform and industry wide test procedures and programs for solid oxide cell/stack (SOC) ass...

  9. On the intrinsic transient capability and limitations of solid oxide fuel cell systems

    OpenAIRE

    Mueller, F; Jabbari, F; Brouwer, J

    2009-01-01

    The intrinsic transient performance capability and limitation of integrated solid oxide fuel cell (SOFC) systems is evaluated based on the system balance-of-plant response and fuel cell operating requirements (i.e., allowable deviation from nominal operation). Specifically, non-dimensional relations are derived from conservation principles that quantify the maximum instantaneous current increase that a solid oxide fuel cell system can safely manage based on (1) the desired fuel cell operating...

  10. Three-phase boundary length in solid-oxide fuel cells: A mathematical model

    Science.gov (United States)

    Janardhanan, Vinod M.; Heuveline, Vincent; Deutschmann, Olaf

    A mathematical model to calculate the volume specific three-phase boundary length in the porous composite electrodes of solid-oxide fuel cell is presented. The model is exclusively based on geometrical considerations accounting for porosity, particle diameter, particle size distribution, and solids phase distribution. Results are presented for uniform particle size distribution as well as for non-uniform particle size distribution.

  11. 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

  12. Reversible anionic redox chemistry in high-capacity layered-oxide electrodes

    Science.gov (United States)

    Sathiya, M.; Rousse, G.; Ramesha, K.; Laisa, C. P.; Vezin, H.; Sougrati, M. T.; Doublet, M.-L.; Foix, D.; Gonbeau, D.; Walker, W.; Prakash, A. S.; Ben Hassine, M.; Dupont, L.; Tarascon, J.-M.

    2013-09-01

    Li-ion batteries have contributed to the commercial success of portable electronics and may soon dominate the electric transportation market provided that major scientific advances including new materials and concepts are developed. Classical positive electrodes for Li-ion technology operate mainly through an insertion-deinsertion redox process involving cationic species. However, this mechanism is insufficient to account for the high capacities exhibited by the new generation of Li-rich (Li1+xNiyCozMn(1-x-y-z)O2) layered oxides that present unusual Li reactivity. In an attempt to overcome both the inherent composition and the structural complexity of this class of oxides, we have designed structurally related Li2Ru1-ySnyO3 materials that have a single redox cation and exhibit sustainable reversible capacities as high as 230 mA h g-1. Moreover, they present good cycling behaviour with no signs of voltage decay and a small irreversible capacity. We also unambiguously show, on the basis of an arsenal of characterization techniques, that the reactivity of these high-capacity materials towards Li entails cumulative cationic (Mn+→M(n+1)+) and anionic (O2-→O22-) reversible redox processes, owing to the d-sp hybridization associated with a reductive coupling mechanism. Because Li2MO3 is a large family of compounds, this study opens the door to the exploration of a vast number of high-capacity materials.

  13. 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.

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

    KAUST Repository

    Bi, Lei; Boulfrad, Samir; Traversa, Enrico

    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.

  15. High-performance micro-solid oxide fuel cells fabricated on nanoporous anodic aluminum oxide templates

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Chang-Woo; Kim, Hyun-Mi; Kim, Ki-Bum [WCUHybrid Materials Program, Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-742 (Korea, Republic of); Son, Ji-Won; Lee, Jong-Ho; Lee, Hae-Weon [High Temperature Energy Materials Center, Korea Institute of Science and Technology, 39-1, Hawolgok-dong, Seongbuk-gu, Seoul, 136-791 (Korea, Republic of)

    2011-03-22

    Micro-solid oxide fuel cells ({mu}-SOFCs) are fabricated on nanoporous anodic aluminum oxide (AAO) templates with a cell structure composed of a 600-nm-thick AAO free-standing membrane embedded on a Si substrate, sputter-deposited Pt electrodes (cathode and anode) and an yttria-stabilized zirconia (YSZ) electrolyte deposited by pulsed laser deposition (PLD). Initially, the open circuit voltages (OCVs) of the AAO-supported {mu}-SOFCs are in the range of 0.05 V to 0.78 V, which is much lower than the ideal value, depending on the average pore size of the AAO template and the thickness of the YSZ electrolyte. Transmission electron microscopy (TEM) analysis reveals the formation of pinholes in the electrolyte layer that originate from the porous nature of the underlying AAO membrane. In order to clog these pinholes, a 20-nm thick Al{sub 2}O{sub 3} layer is deposited by atomic layer deposition (ALD) on top of the 300-nm thick YSZ layer and another 600-nm thick YSZ layer is deposited after removing the top intermittent Al{sub 2}O{sub 3} layer. Fuel cell devices fabricated in this way manifest OCVs of 1.02 V, and a maximum power density of 350 mW cm{sup -2} at 500 C. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Method for in situ carbon deposition measurement for solid oxide fuel cells

    Science.gov (United States)

    Kuhn, J.; Kesler, O.

    2014-01-01

    Previous methods to measure carbon deposition in solid oxide fuel cell (SOFC) anodes do not permit simultaneous electrochemical measurements. Electrochemical measurements supplemented with carbon deposition quantities create the opportunity to further understand how carbon affects SOFC performance and electrochemical impedance spectra (EIS). In this work, a method for measuring carbon in situ, named here as the quantification of gasified carbon (QGC), was developed. TGA experiments showed that carbon with a 100 h residence time in the SOFC was >99.8% gasified. Comparison of carbon mass measurements between the TGA and QGC show good agreement. In situ measurements of carbon deposition in SOFCs at varying molar steam/carbon ratios were performed to further validate the QGC method, and suppression of carbon deposition with increasing steam concentration was observed, in agreement with previous studies. The technique can be used to investigate in situ carbon deposition and gasification behavior simultaneously with electrochemical measurements for a variety of fuels and operating conditions, such as determining conditions under which incipient carbon deposition is reversible.

  17. Long-term Steam Electrolysis with Electrolyte-Supported Solid Oxide Cells

    International Nuclear Information System (INIS)

    Schefold, Josef; Brisse, Annabelle; Poepke, Hendrik

    2015-01-01

    Steam electrolysis over 11000 h with an electrolyte-supported solid oxide cell is discussed. The cell of 45 cm"2 area consists of a scandia/ceria doped zirconia electrolyte (6Sc1CeSZ), CGO diffusion-barrier/adhesion layers, a lanthanum strontium cobaltite ferrite (LSCF) oxygen electrode, and a nickel steam/hydrogen electrode. After initial 2500 h operation with lower current-density magnitude, the current density was set to j = -0.9 A cm"−"2 and the steam conversion rate to 51%. This led to a cell voltage of 1.185 V at 847 °C cell temperature. Average voltage degradation was 7.3 mV/1000 h ( 100% throughout the test (with an external heat source for evaporation). Impedance spectroscopic measurements revealed a degradation almost entirely due to increasing ohmic resistance. The rate of resistance increase was initially faster (up to 40 mΩ cm"2/1000 h) and stabilised after several 1000 h operation. After 9000 h a small (non-ohmic) electrode degradation became detectable (<2 mV/1000 h), superimposed to ohmic degradation. The small electrode degradation is understood as indication for largely reversible (electrolysis cell/fuel cell) behaviour.

  18. Enhanced performance of solid oxide electrolysis cells by integration with a partial oxidation reactor: Energy and exergy analyses

    International Nuclear Information System (INIS)

    Visitdumrongkul, Nuttawut; Tippawan, Phanicha; Authayanun, Suthida; Assabumrungrat, Suttichai; Arpornwichanop, Amornchai

    2016-01-01

    Highlights: • Process design of solid oxide electrolyzer integrated with a partial oxidation reactor is studied. • Effect of key operating parameters of partial oxidation reactor on the electrolyzer performance is presented. • Exergy analysis of the electrolyzer process is performed. • Partial oxidation reactor can enhance the solid oxide electrolyzer performance. • Partial oxidation reactor in the process is the highest exergy destruction unit. - Abstract: Hydrogen production without carbon dioxide emission has received a large amount of attention recently. A solid oxide electrolysis cell (SOEC) can produce pure hydrogen and oxygen via a steam electrolysis reaction that does not emit greenhouse gases. Due to the high operating temperature of SOEC, an external heat source is required for operation, which also helps to improve SOEC performance and reduce operating electricity. The non-catalytic partial oxidation reaction (POX), which is a highly exothermic reaction, can be used as an external heat source and can be integrated with SOEC. Therefore, the aim of this work is to study the effect of operating parameters of non-catalytic POX (i.e., the oxygen to carbon ratio, operating temperature and pressure) on SOEC performance, including exergy analysis of the process. The study indicates that non-catalytic partial oxidation can enhance the hydrogen production rate and efficiency of the system. In terms of exergy analysis, the non-catalytic partial oxidation reactor is demonstrated to be the highest exergy destruction unit due to irreversible chemical reactions taking place, whereas SOEC is a low exergy destruction unit. This result indicates that the partial oxidation reactor should be improved and optimally designed to obtain a high energy and exergy system efficiency.

  19. Cathode and electrolyte materials for solid oxide fuel cells and ion transport membranes

    Science.gov (United States)

    Jacobson, Allan J; Wang, Shuangyan; Kim, Gun Tae

    2014-01-28

    Novel cathode, electrolyte and oxygen separation materials are disclosed that operate at intermediate temperatures for use in solid oxide fuel cells and ion transport membranes based on oxides with perovskite related structures and an ordered arrangement of A site cations. The materials have significantly faster oxygen kinetics than in corresponding disordered perovskites.

  20. The importance of solid waste management and its reverse logistics in fuel gas city of Campina Grande – PB

    Directory of Open Access Journals (Sweden)

    Joselia Fernandes Nascimento

    2016-04-01

    Full Text Available This research aimed to identify the importance of controlling the solid waste management process generated in the posts of Campina Grande-PB fuels, still checking the current level of adequacy of the same with respect to Reverse Logistics for the proper disposal of lubricating oils used and / or contaminated, their waste and packaging. The population consisted of 56 gas stations, authorized by the National Agency of Petroleum, Natural Gas and Biofuels (ANP, and resulted in a sample, for this study, 35 stations, representing 62.50% of the universe. Data collection was carried out with the use of questionnaires and research is characterized exploratory and descriptive. The results show that 51.43% of respondents know the important role of controlling, but most do not have enough knowledge regarding PNRS, LR and management of solid waste, however, has actions that are appropriate for the proper disposal waste.

  1. 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...

  2. Solid-phase synthesis of protein-polymers on reversible immobilization supports.

    Science.gov (United States)

    Murata, Hironobu; Carmali, Sheiliza; Baker, Stefanie L; Matyjaszewski, Krzysztof; Russell, Alan J

    2018-02-27

    Facile automated biomacromolecule synthesis is at the heart of blending synthetic and biologic worlds. Full access to abiotic/biotic synthetic diversity first occurred when chemistry was developed to grow nucleic acids and peptides from reversibly immobilized precursors. Protein-polymer conjugates, however, have always been synthesized in solution in multi-step, multi-day processes that couple innovative chemistry with challenging purification. Here we report the generation of protein-polymer hybrids synthesized by protein-ATRP on reversible immobilization supports (PARIS). We utilized modified agarose beads to covalently and reversibly couple to proteins in amino-specific reactions. We then modified reversibly immobilized proteins with protein-reactive ATRP initiators and, after ATRP, we released and analyzed the protein polymers. The activity and stability of PARIS-synthesized and solution-synthesized conjugates demonstrated that PARIS was an effective, rapid, and simple method to generate protein-polymer conjugates. Automation of PARIS significantly reduced synthesis/purification timelines, thereby opening a path to changing how to generate protein-polymer conjugates.

  3. Kinetics of CO/CO2 and H2/H2O reactions at Ni-based and ceria-based solid-oxide-cell electrodes

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2015-01-01

    The solid oxide electrochemical cell (SOC) is an energy conversion technology that can be operated reversibly, to efficiently convert chemical fuels to electricity (fuel cell mode) as well as to store electricity as chemical fuels (electrolysis mode). The SOC fuel-electrode carries out the electr...

  4. Electrolysis of carbon dioxide in Solid Oxide Electrolysis Cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune; Mogensen, Mogens Bjerg

    2009-01-01

    of the current density and irreversible when operated at conditions that would oxidise carbon. This clearly shows that the passivation was not caused by coke formation. On the other hand, the passivation was partly reversible when introducing hydrogen. The passivation may be a consequence of impurities...

  5. 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

  6. Doxorubicin-loaded micelles of reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers as efficient "active" chemotherapeutic agents.

    Science.gov (United States)

    Cambón, A; Rey-Rico, A; Mistry, D; Brea, J; Loza, M I; Attwood, D; Barbosa, S; Alvarez-Lorenzo, C; Concheiro, A; Taboada, P; Mosquera, V

    2013-03-10

    Five reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers, BOnEOmBOn, with BO ranging from 8 to 21 units and EO from 90 to 411 were synthesized and evaluated as efficient chemotherapeutic drug delivery nanocarriers and inhibitors of the P-glycoprotein (P-gp) efflux pump in a multidrug resistant (MDR) cell line. The copolymers were obtained by reverse polymerization of poly(butylene oxide), which avoids transfer reaction and widening of the EO block distribution, commonly found in commercial poly(ethylene oxide)-poly(propylene oxide) block copolymers (poloxamers). BOnEOmBOn copolymers formed spherical micelles of 10-40 nm diameter at lower concentrations (one order of magnitude) than those of equivalent poloxamers. The influence of copolymer block lengths and BO/EO ratios on the solubilization capacity and protective environment for doxorubicin (DOXO) was investigated. Micelles showed drug loading capacity ranging from ca. 0.04% to 1.5%, more than 150 times the aqueous solubility of DOXO, and protected the cargo from hydrolysis for more than a month due to their greater colloidal stability in solution. Drug release profiles at various pHs, and the cytocompatibility and cytotoxicity of the DOXO-loaded micelles were assessed in vitro. DOXO loaded in the polymeric micelles accumulated more slowly inside the cells than free DOXO due to its sustained release. All copolymers were found to be cytocompatible, with viability extents larger than 95%. In addition, the cytotoxicity of DOXO-loaded micelles was higher than that observed for free drug solutions in a MDR ovarian NCI-ADR-RES cell line which overexpressed P-gp. The inhibition of the P-gp efflux pump by some BOnEOmBOn copolymers, similar to that measured for the common P-gp inhibitor verapamil, favored the retention of DOXO inside the cell increasing its cytotoxic activity. Therefore, poly(butylene oxide)-poly(ethylene oxide) block copolymers offer interesting features as cell

  7. 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.

  8. Reversibility of oxidation and aggregation of impurity in the system of potassium halide monocrystal-phosphite molecular centre

    International Nuclear Information System (INIS)

    Lebedev, A.V.; Bogdanova, T.G.; Vasil'ev, I.A.; Mel'nikova, I.N.

    1980-01-01

    Thermo- and radiation-stimulated reversible reaction of oxidation and aggregation of phosphorus in the composition of phosphite molecular centre in the matrix of potassium iodide are studied. It is shown that in the process of isothermal annealing and γ-radiolysis in the matrix of potassium iodide destruction of phosphite molecular centre takes place. It is established that it is accompanied by oxidation of trivalent phosphorus and aggregation of the formed phosphorus-oxygen anions. Reduction of the initial phosphite centre during the sample hardening is explained by the reverse reaction as a result of which electron-exceeding centres of the base are destructed and reduction of phosphorus takes place

  9. Ab initio study of perovskite type oxide materials for solid oxide fuel cells

    Science.gov (United States)

    Lee, Yueh-Lin

    2011-12-01

    Perovskite type oxides form a family of materials of significant interest for cathodes and electrolytes of solid oxide fuel cells (SOFCs). These perovskites not only are active catalysts for surface oxygen reduction (OR) reactions but also allow incorporating the spilt oxygen monomers into their bulk, an unusual and poorly understood catalytic mechanism that couples surface and bulk properties. The OR mechanisms can be influenced strongly by defects in perovskite oxides, composition, and surface defect structures. This thesis work initiates a first step in developing a general strategy based on first-principles calculations for detailed control of oxygen vacancy content, transport rates of surface and bulk oxygen species, and surface/interfacial reaction kinetics. Ab initio density functional theory methods are used to model properties relevant for the OR reactions on SOFC cathodes. Three main research thrusts, which focus on bulk defect chemistry, surface defect structures and surface energetics, and surface catalytic properties, are carried to investigate different level of material chemistry for improved understanding of key physics/factors that govern SOFC cathode OR activity. In the study of bulk defect chemistry, an ab initio based defect model is developed for modeling defect chemistry of LaMnO 3 under SOFC conditions. The model suggests an important role for defect interactions, which are typically excluded in previous defect models. In the study of surface defect structures and surface energetics, it is shown that defect energies change dramatically (1˜2 eV lower) from bulk values near surfaces. Based on the existing bulk defect model with the calculated ab initio surface defect energetics, we predict the (001) MnO 2 surface oxygen vacancy concentration of (La0.9Sr0.1 )MnO3 is about 5˜6 order magnitude higher than that of the bulk under typical SOFC conditions. Finally, for surface catalytic properties, we show that area specific resistance, oxygen

  10. Fundamentally Addressing Bromine Storage through Reversible Solid-State Confinement in Porous Carbon Electrodes: Design of a High-Performance Dual-Redox Electrochemical Capacitor.

    Science.gov (United States)

    Yoo, Seung Joon; Evanko, Brian; Wang, Xingfeng; Romelczyk, Monica; Taylor, Aidan; Ji, Xiulei; Boettcher, Shannon W; Stucky, Galen D

    2017-07-26

    Research in electric double-layer capacitors (EDLCs) and rechargeable batteries is converging to target systems that have battery-level energy density and capacitor-level cycling stability and power density. This research direction has been facilitated by the use of redox-active electrolytes that add faradaic charge storage to increase energy density of the EDLCs. Aqueous redox-enhanced electrochemical capacitors (redox ECs) have, however, performed poorly due to cross-diffusion of soluble redox couples, reduced cycle life, and low operating voltages. In this manuscript, we propose that these challenges can be simultaneously met by mechanistically designing a liquid-to-solid phase transition of oxidized catholyte (or reduced anolyte) with confinement in the pores of electrodes. Here we demonstrate the realization of this approach with the use of bromide catholyte and tetrabutylammonium cation that induces reversible solid-state complexation of Br 2 /Br 3 - . This mechanism solves the inherent cross-diffusion issue of redox ECs and has the added benefit of greatly stabilizing the reactive bromine generated during charging. Based on this new mechanistic insight on the utilization of solid-state bromine storage in redox ECs, we developed a dual-redox EC consisting of a bromide catholyte and an ethyl viologen anolyte with the addition of tetrabutylammonium bromide. In comparison to aqueous and organic electric double-layer capacitors, this system enhances energy by factors of ca. 11 and 3.5, respectively, with a specific energy of ∼64 W·h/kg at 1 A/g, a maximum power density >3 kW/kg, and cycling stability over 7000 cycles.

  11. Modified calcium oxide as stable solid base catalyst for Aldol

    Indian Academy of Sciences (India)

    A highly efficient and stable solid-base catalyst for Aldol condensation was prepared by modifying commercial CaO with benzyl bromide in a simple way. It was found that modified CaO can effectively catalyse the Aldol condensation of cyclohexanone and benzaldehyde, as well as various benzaldehydes, to produce ...

  12. Modified calcium oxide as stable solid base catalyst for Aldol ...

    Indian Academy of Sciences (India)

    A highly efficient and stable solid-base catalyst for Aldol condensation was ... was bonded on surface of CaO chemically and almost no Ca(OH)2 formed during the modification process. ... cation, corrosion and waste generation attract great.

  13. On the absence of reverse running waves in general displacement of lattice vibration in popular books on solid state theory

    Science.gov (United States)

    Xia, Shangda; Lou, Liren

    2018-05-01

    In this article we point out that there is a deficiency in the presentation of the general solution of harmonic lattice vibration, the omission of half of the allowed running waves, in many popular textbooks published since 1940, e.g. O Madelung’s 1978 Introduction to Solid-State Theory and J Solyom’s 2007 Fundamentals of the Physics of Solids, vol 1. So we provide a revised presentation, which gives a complete general solution and demonstrates clearly that the conventional complex normal coordinate should be a superposition of two coordinates (multiplied by a factor \\sqrt{1/2}) of running waves travelling oppositely along q and -q, not only a coordinate of a unidirectional running wave as many books considered. It is noticed that the book, Quantum Theory of the Solid State: An Introduction, by L Kantorovich, published in 2004, and the review article, ‘Phonons in perfect crystals’ by W Cochran and R A Cowly, published in 1967, for a one-dimensional single-atom chain gave correct (but not normalized) formulae for the general solution of lattice vibration and the normal coordinate. However, both of them stated still that each normal coordinate describes an independent mode of vibration, which in our opinion needs to be further discussed. Moreover, in books such as Fundamentals of the Physics of Solids, vol 1, by J Solyom, and The Physics and Chemistry of Solids, by S R Elliott, published in 2006 and 2007, respectively, the reverse waves were still lost. Hence, we also discuss a few related topics. In quantization of the lattice vibration, the introduction of the conventional two (not one) independent phonon operators in a normal coordinate is closely related to the ‘independence’ of the two constituent waves mentioned above, and we propose a simple propositional relation between the phonon operator and the corresponding running wave coordinate. Moreover, only the coordinate of the superposition wave (not the running wave), as the normal coordinate can

  14. Solid oxide fuel cell systems for residential micro-combined heat and power in the UK: Key economic drivers

    Science.gov (United States)

    Hawkes, Adam; Leach, Matthew

    The ability of combined heat and power (CHP) to meet residential heat and power demands efficiently offers potentially significant financial and environmental advantages over centralised power generation and heat-provision through natural-gas fired boilers. A solid oxide fuel cell (SOFC) can operate at high overall efficiencies (heat and power) of 80-90%, offering an improvement over centralised generation, which is often unable to utilise waste heat. This paper applies an equivalent annual cost (EAC) minimisation model to a residential solid oxide fuel cell CHP system to determine what the driving factors are behind investment in this technology. We explore the performance of a hypothetical SOFC system—representing expectations of near to medium term technology development—under present UK market conditions. We find that households with small to average energy demands do not benefit from installation of a SOFC micro-CHP system, but larger energy demands do benefit under these conditions. However, this result is sensitive to a number of factors including stack capital cost, energy import and export prices, and plant lifetime. The results for small and average dwellings are shown to reverse under an observed change in energy import prices, an increase in electricity export price, a decrease in stack capital costs, or an improvement in stack lifetime.

  15. Identification of a Methane Oxidation Intermediate on Solid Oxide Fuel Cell Anode Surfaces with Fourier Transform Infrared Emission.

    Science.gov (United States)

    Pomfret, Michael B; Steinhurst, Daniel A; Owrutsky, Jeffrey C

    2013-04-18

    Fuel interactions on solid oxide fuel cell (SOFC) anodes are studied with in situ Fourier transform infrared emission spectroscopy (FTIRES). SOFCs are operated at 800 °C with CH4 as a representative hydrocarbon fuel. IR signatures of gas-phase oxidation products, CO2(g) and CO(g), are observed while cells are under load. A broad feature at 2295 cm(-1) is assigned to CO2 adsorbed on Ni as a CH4 oxidation intermediate during cell operation and while carbon deposits are electrochemically oxidized after CH4 operation. Electrochemical control provides confirmation of the assignment of adsorbed CO2. FTIRES has been demonstrated as a viable technique for the identification of fuel oxidation intermediates and products in working SOFCs, allowing for the elucidation of the mechanisms of fuel chemistry.

  16. Feasibility of municipal solid waste (MSW as energy sources for Saudi Arabia’s future Reverse osmosis (RO desalination plants

    Directory of Open Access Journals (Sweden)

    Agboola Phillips O.

    2016-12-01

    Full Text Available The Kingdom of Saudi Arabia (KSA generates between 1.4–1.75 kg/person/day of Municipal Solid Waste (MSW that accounts for over 16 million tons of MSW/year. The solid waste collected from different sources is dumped in landfills, thereby creating environmental concerns. In this paper, the potential of solid waste as an energy source (Waste to Energy (WTE for Reverse Osmosis (RO water purification was evaluated. The KSA is known for its acute fresh water shortages and uses desalination technology in meeting its daily water requirements; a process that is energy intensive. The evaluation of the energy content of MSW shows a potential to produce about 927 MW in 2015, based on a total mass burn, and about 1,692 MW in 2032. The MSW-WTE plants can produce about 1.5% of the targeted 120 GW of energy for 2032. For the R.O system, it will give approximately 16.8% of the daily fresh water needed for total mass burn and 2.4% with the recycling option.

  17. Electro-Fenton oxidation of reverse osmosis concentrate from sanitary landfill leachate: Evaluation of operational parameters.

    Science.gov (United States)

    Fernandes, Annabel; Labiadh, Lazhar; Ciríaco, Lurdes; Pacheco, Maria José; Gadri, Abdellatif; Ammar, Salah; Lopes, Ana

    2017-10-01

    The electro-Fenton oxidation of a concentrate from reverse osmosis of a sanitary landfill leachate, with an initial chemical oxygen demand (COD) of 42 g L -1 , was carried out using a carbon-felt cathode and a boron doped diamond anode. The influence of the applied current intensity, initial pH and dissolved iron initial concentration on the electro-Fenton process was assessed. For the experimental conditions used, results showed that the initial pH is the parameter that more strongly influences the current efficiency of the electro-Fenton process, being this influence more pronounced on the oxidation rate than on the mineralization rate of the organic matter. The increase in iron initial concentration was found to be detrimental, since the natural amount of iron present in the effluent, 73 mg L -1 of total iron and 61 mg L -1 of dissolved iron, was sufficient to ensure the electro-Fenton process at the applied intensities - 0.2-1.4 A. For the more favourable conditions studied, initial pH of 3 and natural iron concentration, it was found an increase in the organic load and nitrogen removals with the applied current intensity. For the highest current intensity applied, a COD removal of 16.7 g L -1 was achieved after 8-h experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. 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.

  19. Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

    Science.gov (United States)

    Lee, Kyu Hyung; Jung, Hyuk Joon; Lee, Ju Hee; Kim, Kyungtae; Lee, Byeongno; Nam, Dohyun; Kim, Chung Man; Jung, Myung-Hwa; Hur, Nam Hwi

    2018-05-01

    A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

  20. Solid state chemistry of rare earth oxides. Final report, September 1, 1950--July 31, 1977

    International Nuclear Information System (INIS)

    Eyring, L.

    1977-07-01

    Work under Contract E(11-1)-1109 and its antecedents has been primarily for the purpose of obtaining detailed thermodynamic, kinetic and structural information on the complex rare earth oxides of praseodymium and terbium. These systems exhibit homologous series of ordered phases, order-disorder transformations, wide-range nonstoichiometric phases, chemical hysteresis in two-phase regions and many other solid state reaction phenomena. Fluorite-related materials of importance to ERDA occur as nuclear fuels, radiation power sources, insulators and solid electrolytes. The rare earth oxides serve directly as model systems for such similar materials and, in a more general sense, they serve as models of solids in general since they exhibit nearly the full range of solid state properties

  1. Sulfur Poisoning of the Water Gas Shift Reaction on Anode Supported Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Hagen, Anke

    2013-01-01

    resistance increased both in the high and low frequency region, which indicates a strong poisoning of the water gas shift reaction and thus a lack of hydrogen fuel in addition to the poisoning of the electrochemical hydrogen oxidation. All poisoning effects are reversible under the applied operating...

  2. Solid Waste Decontamination by Thermal Desorption and Catalytic Oxidation Methods

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Topka, Pavel; Soukup, Karel; Jirátová, Květa; Váňová, H.; Kaštánek, František

    2014-01-01

    Roč. 68, č. 9 (2014), s. 1279-1282 ISSN 0366-6352 R&D Projects: GA MPO FR-TI1/059 Institutional support: RVO:67985858 Keywords : thermal desorption * catalytic oxidation * soil decontamination Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.468, year: 2014

  3. 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...

  4. Oxidation Kinetics of Copper: An Experiment in Solid State Chemistry.

    Science.gov (United States)

    Ebisuzaki, Y.; Sanborn, W. B.

    1985-01-01

    Oxidation kinetics in metals and the role defects play in diffusion-controlled reactions are discussed as background for a junior/senior-level experiment in the physical or inorganic chemistry laboratory. Procedures used and typical data obtained are provided for the experiment. (JN)

  5. Three-phase boundary length in solid-oxide fuel cells: A mathematical model

    Energy Technology Data Exchange (ETDEWEB)

    Janardhanan, Vinod M. [Institutefor Chemical Technology and Polymer Chemistry, University of Karlsruhe (TH), Kaiserstr. 12, D-76128 Karlsruhe (Germany); Heuveline, Vincent; Deutschmann, Olaf [Institute for Applied and Numerical Mathematics, University of Karlsruhe (TH), Kaiserstr. 12, D-76128 Karlsruhe (Germany)

    2008-03-15

    A mathematical model to calculate the volume specific three-phase boundary length in the porous composite electrodes of solid-oxide fuel cell is presented. The model is exclusively based on geometrical considerations accounting for porosity, particle diameter, particle size distribution, and solids phase distribution. Results are presented for uniform particle size distribution as well as for non-uniform particle size distribution. (author)

  6. Thermal expansion studies on uranium-neodymium mixed oxide solid solutions

    International Nuclear Information System (INIS)

    Panneerselvam, G.; Venkata Krishnan, R.; Antony, M.P.; Nagarajan, K.

    2012-01-01

    Uranium-Neodymium mixed oxides solid solutions (U 1-y Nd y ) O 2 (y=0.2-0.95) were prepared by combustion synthesis using citric acid as fuel. Structural characterization and computation of lattice parameter was carried out from room temperature X-ray diffraction measurements. Single-phase fluorite structure was observed up to y=0.80. For solid solutions with y>0.80 additional Nd 2 O 3 lines were visible

  7. Use of wastewater treatment plant biogas for the operation of Solid Oxide Fuel Cells (SOFCs).

    Science.gov (United States)

    Lackey, Jillian; Champagne, Pascale; Peppley, Brant

    2017-12-01

    Solid Oxide Fuel Cells (SOFCs) perform well on light hydrocarbon fuels, and the use of biogas derived from the anaerobic digestion (AD) of municipal wastewater sludges could provide an opportunity for the CH 4 produced to be used as a renewable fuel. Greenhouse gas (GHG), NO x , SO x , and hydrocarbon pollutant emissions would also be reduced. In this study, SOFCs were operated on AD derived biogas. Initially, different H 2 dilutions were tested (N 2 , Ar, CO 2 ) to examine the performance of tubular SOFCs. With inert gases as diluents, a decrease in cell performance was observed, however, the use of CO 2 led to a higher decrease in performance as it promoted the reverse water-gas shift (WGS) reaction, reducing the H 2 partial pressure in the gas mixture. A model was developed to predict system efficiency and GHG emissions. A higher electrical system efficiency was noted for a steam:carbon ratio of 2 compared to 1 due to the increased H 2 partial pressure in the reformate resulting from higher H 2 O concentration. Reductions in GHG emissions were estimated at 2400 tonnes CO 2 , 60 kg CH 4 and 18 kg N 2 O. SOFCs were also tested using a simulated biogas reformate mixture (66.7% H 2 , 16.1% CO, 16.5% CO 2 , 0.7% N 2 , humidified to 2.3 or 20 mol% H 2 O). Higher humidification yielded better performance as the WGS reaction produced more H 2 with additional H 2 O. It was concluded that AD-derived biogas, when cleaned to remove H 2 S, Si compounds, halides and other contaminants, could be reformed to provide a clean, renewable fuel for SOFCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. 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......), 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...

  9. Solid Oxide Cell and Stack Testing, Safety and Quality Assurance (SOCTESQA)

    DEFF Research Database (Denmark)

    Auer, C.; Lang, M.; Couturier, K.

    2015-01-01

    In the EU-funded project “SOCTESQA” partners from Europe and Singapore are working together to develop uniform and industry wide test procedures and protocols for solid oxide cells and stacks SOC cell/stack assembly. New application fields which are based on the operation of the SOC cell/stack as......In the EU-funded project “SOCTESQA” partners from Europe and Singapore are working together to develop uniform and industry wide test procedures and protocols for solid oxide cells and stacks SOC cell/stack assembly. New application fields which are based on the operation of the SOC cell...

  10. Tuneable diode laser gas analyser for methane measurements on a large scale solid oxide fuel cell

    Science.gov (United States)

    Lengden, Michael; Cunningham, Robert; Johnstone, Walter

    2011-10-01

    A new in-line, real time gas analyser is described that uses tuneable diode laser spectroscopy (TDLS) for the measurement of methane in solid oxide fuel cells. The sensor has been tested on an operating solid oxide fuel cell (SOFC) in order to prove the fast response and accuracy of the technology as compared to a gas chromatograph. The advantages of using a TDLS system for process control in a large-scale, distributed power SOFC unit are described. In future work, the addition of new laser sources and wavelength modulation will allow the simultaneous measurement of methane, water vapour, carbon-dioxide and carbon-monoxide concentrations.

  11. Laser induced densification of cerium gadolinium oxide: Application to single-chamber solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mariño, Mariana [École Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF, F-42023 Saint-Étienne (France); Rieu, Mathilde, E-mail: rieu@emse.fr [École Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF, F-42023 Saint-Étienne (France); Viricelle, Jean-Paul [École Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF, F-42023 Saint-Étienne (France); Garrelie, Florence [Université Jean Monnet, Laboratoire Hubert Curien, CNRS: UMR 5516, 42000 Saint-Etienne (France)

    2016-06-30

    Graphical abstract: - Highlights: • CGO surface densifications were induced by UV and IR laser irradiations. • Grain growth or densified cracked surfaces were observed by SEM. • UV laser treatments allow a decrease of gas permeation through electrolyte layer. • Electrical conductivity of the electrolyte was modified by laser treatments. • Grain growth of electrolyte induced by UV laser improved cell performances. - Abstract: In single-chamber solid oxide fuel cells (SC-SOFC), anode and cathode are placed in a gas chamber where they are exposed to a fuel/air mixture. Similarly to conventional dual-chamber SOFC, the anode and the cathode are separated by an electrolyte. However, as in the SC-SOFC configuration the electrolyte does not play tightness role between compartments, this one can be a porous layer. Nevertheless, it is necessary to have a diffusion barrier to prevent the transportation of hydrogen produced locally at the anode to the cathode that reduces fuel cell performances. This study aims to obtain directly a diffusion barrier through the surface densification of the electrolyte Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (CGO) by a laser treatment. KrF excimer laser and Yb fiber laser irradiations were used at different fluences and number of pulses to modify the density of the electrolyte coating. Microstructural characterizations confirmed the modifications on the surface of the electrolyte for appropriate experimental conditions showing either grain growth or densified but cracked surfaces. Gas permeation and electrical conductivities of the modified electrolyte were evaluated. Finally SC-SOFC performances were improved for the cells presenting grain growth at the electrolyte surface.

  12. Nanotubes of rare earth cobalt oxides for cathodes of intermediate-temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sacanell, Joaquin [Departamento de Fisica, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, 1650 San Martin, Buenos Aires (Argentina); CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Buenos Aires (Argentina); Leyva, A. Gabriela [Departamento de Fisica, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, UNSAM. Av. Gral. Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Bellino, Martin G.; Lamas, Diego G. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Buenos Aires (Argentina)

    2010-04-02

    In this work we studied the electrochemical properties of cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) prepared with nanotubes of La{sub 0.6}Sr{sub 0.4}CoO{sub 3} (LSCO). Their nanostructures consist of agglomerated nanoparticles in tubular structures of sub-micrometric diameter. The resulting cathodes are highly porous both at the micro- and the nanoscale. This fact increases significantly the access to active sites for the oxygen reduction. We investigated the influence of the diameter of the precursor nanotubes on the polarization resistance of the LSCO cathodes on CeO{sub 2}-10 mol.% Sm{sub 2}O{sub 3} (SDC) electrolytes under air atmosphere, evaluated in symmetrical [LSCO/SDC/LSCO] cells. Our results indicate an optimized performance when the diameter of precursor nanotubes is sufficiently small to become dense nanorods after cathode sintering. We present a phenomenological model that successfully explains the behavior observed and considers that a small starting diameter acts as a barrier that prevents grains growth. This is directly related with the lack of contact points between nanotubes in the precursor, which are the only path for the growth of ceramic grains. We also observed that a conventional sintering process (of 1 h at 1000 C with heating and cooling rates of 10 C min{sup -1}) has to be preferred against a fast firing one (1 or 2 min at 1100 C with heating and cooling rates of 100 C min{sup -1}) in order to reach a higher performance. However, a good adhesion of the cathode can be achieved with both methods. Our results suggest that oxygen vacancy diffusion is enhanced while decreasing LSCO particle size. This indicates that the high performance of our nanostructured cathodes is not only related with the increase of the number of active sites for oxygen reduction but also to the fact that the nanotubes are formed by nanoparticles. (author)

  13. Reversibility effects in disordered and ordered solids leading to scattered-ion yield enhancements near 1800

    International Nuclear Information System (INIS)

    Appleton, B.R.; Holland, O.W.; Barrett, J.H.

    1981-01-01

    A general review is given of the recently discovered phenomenon of enhanced ion backscattering near 180 0 . Examples of experimental results are presented that illustrate the nature of the enhancement and its basic dependences on angle and depth. It is shown that the various aspects of the effect can be reproduced by computer simulations that include the effects of trajectory reversibility, nuclear recoils and detector depth resolution. Measured and calculated results are given that illustrate the dependences of the enhancement on ion and target parameters. Results are presented of the enhancement observed in amorphous Ge and in single crystal of Ge rotated to create a reference spectrum. The enhancement is greater for the rotating crystal case demonstrating crystalline effects on the enhancement. Also presented are some results for the enhancement of the surface yield in a channeling direction of a crystal in the 180 0 geometry; possible application for surface studies is discussed. (orig.)

  14. Polarization reversal of proton spins in solid-state targets by superradiance effects

    International Nuclear Information System (INIS)

    Reichertz, L.A.

    1991-02-01

    Scattering experiments with polarized targets are prepared at the Bonn accelerator ELSA. The new Bonn frozen spin target (BOFROST) developed for real photon experiments at the PHOENICS detector has been tested in the laboratory. Proton polarization values of -99% and +94% in ammonia, -96% and +90% in butanol have been achieved at a magnetic field of 3.5 Tesla. At a temperature of 70 mK and a magnetic field of 0.35 Tesla a very fast spontaneous polarization reversal has been observed. This effect occured at negative polarization only and has been identified as a self-induced superradiance effect in the proton spin system. This work describes the polarization and relaxation measurements at BOFROST and detailed experiments concerning the superradiance effect. (orig.) [de

  15. Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

  16. Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions.

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

  17. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  18. Fermi Potential across Working Solid Oxide Cells with Zirconia or Ceria Electrolytes

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    A solid electrolyte will always possess a finite electronic conductivity, in particular electrolytes like doped ceria that easily get reduced and become mixed ionic and electronic conductors. This given rise too high leak currents through the solid oxide cell (SOC). Especially, problems have been...... driving the O2-ions is not the Fermi potential, which is the potential of the electrons, but the Galvani potential (or inner potential) (1). The concepts of potentials describing the electrical situation of a solid electrolyte is shown i Fig. 1, and an example of the Fermi potential (π) and Galvani...

  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. The calcium oxide influence on formation of manganese, calcium pyrovanadate solid solutions

    International Nuclear Information System (INIS)

    Vatolin, N.A.; Volkova, P.I.; Sapozhnikova, T.V.; Ovchinnikova, L.A.

    1988-01-01

    The X-ray graphic, derivatographic, microscopic and chemical methods are used to study solid solutions of manganese, calcium pyrovanadates containing 1-10 mass% CaO and the products of interaction of reprocessing charges of vanadium-containing converter slags intended for he formation of manganese and calcium pyrovanadates with additions of calcium oxide within 10-90 mass%. It is established that in the case of 1-6 mass% CaO content in manganese pyrovanadate solid interstitial solutions appear, while at 6-20 mass% CaO - solid substitution solutions form. The results of calculating elementary cell parameters as well as melting temperatures and pyrovanadate solid solution solubility depending on CaO content are presented. The best solubility of introduction solid solutions during vanadium extraction according to the lime technology is found

  1. Exfoliation and reassembly of cobalt oxide nanosheets into a reversible lithium-ion battery cathode.

    Science.gov (United States)

    Compton, Owen C; Abouimrane, Ali; An, Zhi; Palmeri, Marc J; Brinson, L Catherine; Amine, Khalil; Nguyen, SonBinh T

    2012-04-10

    An exfoliation-reassembly-activation (ERA) approach to lithium-ion battery cathode fabrication is introduced, demonstrating that inactive HCoO(2) powder can be converted into a reversible Li(1-x) H(x) CoO(2) thin-film cathode. This strategy circumvents the inherent difficulties often associated with the powder processing of the layered solids typically employed as cathode materials. The delamination of HCoO(2) via a combination of chemical and mechanical exfoliation generates a highly processable aqueous dispersion of [CoO(2) ](-) nanosheets that is critical to the ERA approach. Following vacuum-assisted self-assembly to yield a thin-film cathode and ion exchange to activate this material, the generated cathodes exhibit excellent cyclability and discharge capacities approaching that of low-temperature-prepared LiCoO(2) (~83 mAh g(-1) ), with this good electrochemical performance attributable to the high degree of order in the reassembled cathode. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Biomineralization associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals

    Science.gov (United States)

    Zhang, G.; Dong, H.; Jiang, H.; Kukkadapu, R.K.; Kim, J.; Eberl, D.; Xu, Z.

    2009-01-01

    Iron-reducing and oxidizing microorganisms gain energy through reduction or oxidation of iron, and by doing so play an important role in the geochemical cycling of iron. This study was undertaken to investigate mineral transformations associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals. A fluid sample from the 2450 m depth of the Chinese Continental Scientific Drilling project was collected, and Fe3+-reducing and Fe2+-oxidizing microorganisms were enriched. The enrichment cultures displayed reduction of Fe3+ in nontronite and ferric citrate, and oxidation of Fe2+ in vivianite, siderite, and monosulfide (FeS). Additional experiments verified that the iron reduction and oxidation was biological. Oxidation of FeS resulted in the formation of goethite, lepidocrocite, and ferrihydrite as products. Although our molecular microbiological analyses detected Thermoan-aerobacter ethanolicus as a predominant organism in the enrichment culture, Fe3+ reduction and Fe2+ oxidation may be accomplished by a consortia of organisms. Our results have important environmental and ecological implications for iron redox cycling in solid minerals in natural environments, where iron mineral transformations may be related to the mobility and solubility of inorganic and organic contaminants.

  3. 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...

  4. A ''reverse'' solid-phase radio-immuno-assay for IgM-antibodies to hepatitis A virus

    International Nuclear Information System (INIS)

    Meurman, O.H.; Matter, L.; Krishna, R.V.; Krech, U.H.

    1981-01-01

    A ''reverse'' solid-phase radio-immuno-assay for IgM antibodies to hepatitis A virus (HAV) was developed. Anti-human IgM immunoglobulins were bound on the wells of polyvinylchloride microtiter plates. Serum specimens were incubated in the anti-human IgM coated wells and bound IgM antibodies were then assayed for antigen specificity by subsequent incubations with HAV antigen and 125 I-labelled human anti-HAV IgG. The test showed a high sensitivity and specificity for anti-HAV IgM antibodies. No false-positive reactions were observed either in the sera from patients with hepatobiliary disorders other than HAV infection or in the sera containing both rheumatoid factor and anti-HAV IgG antibodies. In acute HAV infections specific IgM antibodies were present already in the first specimens taken within a few days after the onset of jaundice. The persistence of the IgM antibodies was from 4 to 6 months. IgM antibody titers up to 1,000,000 were observed in the acute phase of HAV infection. In routine diagnostic work the titration of the sera was not necessary, since a reliable qualitative result was obtained by testing the sera in a single dilution of 1:100. A similar ''reverse'' immuno-assay principle may be adaptable for the diagnostic determination of IgM antibodies to different viral and microbial antigens. (author)

  5. B4C solid target boronization of the MST reversed-field pinch

    International Nuclear Information System (INIS)

    Den Hartog, D.J.; Cekic, M.; Fiksel, G.; Hokin, S.A.; Kendrick, R.D.; Prager, S.C.; Stoneking, M.R.

    1992-10-01

    A solid rod of hot-pressed boron carbide is being used as the source of boron during boronization of MST. The most striking result of this procedure is the reduction in oxygen contamination of the plasma (O III radiation, characteristic of oxygen at the edge, falls by about a factor of 3 after boronization.). The radiated power fraction drops to about half its initial value. Particle reflux from the wall is also lowered, making density control simpler. The rod (12.7 mm diameter) is inserted into the edge plasma of normal high-power RFP discharges. B 4 C is ablated from the surface of the rod and deposited in a thin film (a-B/C:H) on the walls and limiters. The energy flux carried by ''superthermal'' (not ''runaway'') electrons at the edge of MST appears to enhance the efficient, non-destructive ablation of the boron carbide rod

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

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    Municipal Solid Waste (MSW) can be considered a valid biomass to be used in a power plant. The major advantage is the reduction of pollutants and greenhouse gases emissions not only within large cities but also globally. Another advantage is that by th eir use it is possible to reduce the waste...... studied to optimize the plant efficiency in terms of operating conditions. Compared with modern waste incinerators with heat recovery, the gasification process integrated with SOFC and Stirling engine permits an increase in electricity output up of 50%, which means that the solid waste gasification......, waste is subject to chemical treatments through air or/and steam utilization; the result is a synthesis gas, called “Syngas” which is principally composed of hydrogen and carbon monoxide. Traces of hydrogen sulfide could also be present which can easily be separated in a desulfurization reactor...

  7. A detailed approach to model transport, heterogeneous chemistry, and electrochemistry in solid-oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Janardhanan, V.

    2007-07-01

    This dissertation layes out detailed descriptions for heterogeneous chemistry, electrochemistry, and porous media transport models to simulate solid oxide fuel cells (SOFCs). An elementary like heterogeneous reaction mechanism for the steam reforming of CH4 developed in our research group is used throughout this work. Based on assumption of hydrogen oxidation as the only electrochemical reaction and single step electron transfer reaction as rate limiting, a modified Butler-Volmer equation is used to model the electrochemistry. The pertinence of various porous media transport models such as Modified Fick Model (MFM), Dusty Gas Model (DGM), Mean Transport Pore Model, Modified Maxwell Stefan Model, and Generalized Maxwell Stefan Model under reaction conditions are studied. In general MFM and DGM predictions are in good agreement with experimental data. Physically realistic electrochemical model parameters are very important for fuel cell modeling. Button cell simulations are carried out to deduce the electrochemical model parameters, and those parameters are further used in the modeling of planar cells. Button cell simulations are carried out using the commercial CFD code FLUENT coupled with DETCHEM. For all temperature ranges the model works well in predicting the experimental observations in the high current density region. However, the model predicts much higher open circuit potentials than that observed in the experiments, mainly due to the absence of coking model in the elementary heterogeneous mechanism leading to nonequilibrium compositions. Furthermore, the study presented here employs Nernst equation for the calculation of reversible potential which is strictly valid only for electrochemical equilibrium. It is assumed that the electrochemical charge transfer reaction involving H2 is fast enough to be in equilibrium. However, the comparison of model prediction with thermodynamic equilibrium reveals that this assumption is violated under very low current

  8. Reversible oxidative modification: a key mechanism of Na+-K+ pump regulation.

    Science.gov (United States)

    Figtree, Gemma A; Liu, Chia-Chi; Bibert, Stephanie; Hamilton, Elisha J; Garcia, Alvaro; White, Caroline N; Chia, Karin K M; Cornelius, Flemming; Geering, Kaethi; Rasmussen, Helge H

    2009-07-17

    Angiotensin II (Ang II) inhibits the cardiac sarcolemmal Na(+)-K(+) pump via protein kinase (PK)C-dependent activation of NADPH oxidase. We examined whether this is mediated by oxidative modification of the pump subunits. We detected glutathionylation of beta(1), but not alpha(1), subunits in rabbit ventricular myocytes at baseline. beta(1) Subunit glutathionylation was increased by peroxynitrite (ONOO(-)), paraquat, or activation of NADPH oxidase by Ang II. Increased glutathionylation was associated with decreased alpha(1)/beta(1) subunit coimmunoprecipitation. Glutathionylation was reversed after addition of superoxide dismutase. Glutaredoxin 1, which catalyzes deglutathionylation, coimmunoprecipitated with beta(1) subunit and, when included in patch pipette solutions, abolished paraquat-induced inhibition of myocyte Na(+)-K(+) pump current (I(p)). Cysteine (Cys46) of the beta(1) subunit was the likely candidate for glutathionylation. We expressed Na(+)-K(+) pump alpha(1) subunits with wild-type or Cys46-mutated beta(1) subunits in Xenopus oocytes. ONOO(-) induced glutathionylation of beta(1) subunit and a decrease in Na(+)-K(+) pump turnover number. This was eliminated by mutation of Cys46. ONOO(-) also induced glutathionylation of the Na(+)-K(+) ATPase beta(1) subunit from pig kidney. This was associated with a approximately 2-fold decrease in the rate-limiting E(2)-->E(1) conformational change of the pump, as determined by RH421 fluorescence. We propose that kinase-dependent regulation of the Na(+)-K(+) pump occurs via glutathionylation of its beta(1) subunit at Cys46. These findings have implications for pathophysiological conditions characterized by neurohormonal dysregulation, myocardial oxidative stress and raised myocyte Na(+) levels.

  9. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    International Nuclear Information System (INIS)

    Da, B.; Sun, Y.; Ding, Z. J.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.

    2013-01-01

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO 2 in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  10. Nickel/Yttria-stabilised zirconia cermet anodes for solid oxide fuel cells

    NARCIS (Netherlands)

    Primdahl, Søren

    1999-01-01

    This thesis deals with the porous Ni/yttria-stabilized zirconia (YSZ) cermet anode on a YSZ electrolyte for solid oxide fuel cells (SOFC). Such anodes are predominantly operated in moist hydrogen at 700°C to 1000°C, and the most important technological parameters are the polarization resistance and

  11. Ni-YSZ solid oxide fuel cell anode behavior upon redox cycling based on electrical characterization

    DEFF Research Database (Denmark)

    Klemensø, Trine; Mogensen, Mogens Bjerg

    2006-01-01

    Ni-YSZ cermets are a prevalent material used for solid oxide fuel cells. However, the cermet degrades upon redox cycling. The degradation is related to microstructural changes, but knowledge of the mechanisms has been limited. DC conductivity measurements were performed on cermets and cermets...

  12. Ni-YSZ solid oxide fuel cell anode behavior upon redox cycling based on electrical characterization

    DEFF Research Database (Denmark)

    Klemensø, Trine; Mogensen, Mogens Bjerg

    2007-01-01

    Nickel (Ni)—yttria-stabilized zirconia (YSZ) cermets are a prevalent material used for solid oxide fuel cells. The cermet degrades upon redox cycling. The degradation is related to microstructural changes, but knowledge of the mechanisms has been limited. Direct current conductivity measurements...

  13. 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...

  14. Crystalline structure and microstructural characteristics of the cathode/electrolyte solid oxide half-cells

    International Nuclear Information System (INIS)

    Chiba, Rubens; Vargas, Reinaldo Azevedo; Andreoli, Marco; Santoro, Thais Aranha de Barros; Seo, Emilia Satoshi Miyamaru

    2009-01-01

    The solid oxide fuel cell (SOFC) is an electrochemical device generating of electric energy, constituted of cathode, electrolyte and anode; that together they form a unity cell. The study of the solid oxide half-cells consisting of cathode and electrolyte it is very important, in way that is the responsible interface for the reduction reaction of the oxygen. These half-cells are ceramic materials constituted of strontium-doped lanthanum manganite (LSM) for the cathode and yttria-stabilized zirconia (YSZ) for the electrolyte. In this work, two solid oxide half-cells have been manufactured, one constituted of LSM cathode thin film on YSZ electrolyte substrate (LSM - YSZ half-cell), and another constituted of LSM cathode and LSM/YSZ composite cathode thin films on YSZ electrolyte substrate (LSM - LSM/YSZ - YSZ half cell). The cathode/electrolyte solid oxide half-cells were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results have been presented with good adherence between cathode and electrolyte and, LSM and YSZ phases were identified. (author)

  15. 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...

  16. Prediction of solid oxide fuel cell cathode activity with first-principles descriptors

    DEFF Research Database (Denmark)

    Lee, Yueh-Lin; Kleis, Jesper; Rossmeisl, Jan

    2011-01-01

    In this work we demonstrate that the experimentally measured area specific resistance and oxygen surface exchange of solid oxide fuel cell cathode perovskites are strongly correlated with the first-principles calculated oxygen p-band center and vacancy formation energy. These quantities...... are therefore descriptors of catalytic activity that can be used in the first-principles design of new SOFC cathodes....

  17. Thermodynamic Performance Study of Biomass Gasification, Solid Oxide Fuel Cell and Micro Gas Turbine Hybrid Systems

    DEFF Research Database (Denmark)

    Bang-Møller, Christian; Rokni, Masoud

    2010-01-01

    A system level modelling study of three combined heat and power systems based on biomass gasification is presented. Product gas is converted in a micro gas turbine (MGT) in the first system, in a solid oxide fuel cell (SOFC) in the second system and in a combined SOFC–MGT arrangement in the third...

  18. Quantitative review of degradation and lifetime of solid oxide cells and stacks

    DEFF Research Database (Denmark)

    Skafte, Theis Løye; Hjelm, Johan; Blennow, Peter

    2016-01-01

    A comprehensive review of degradation and lifetime for solid oxide cells and stacks hasbeen conducted. Based on more than 50 parameters from 150 publications and 1 000 000hours of accumulated testing, this paper presents a quantitative analysis of the currentinternational status of degradation...

  19. Strontium Titanate-based Composite Anodes for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L.R.

    2008-01-01

    Surfactant-assisted infiltration of Gd-doped ceria (CGO) in Nb-doped SrTiO3 (STN) was investigated as a potential fuel electrode for solid oxide fuel cells (SOFC). An electronically conductive backbone structure of STN was first fabricated at high temperatures and then combined with the mixed con...

  20. Determination of the bonding strength in solid oxide fuel cells' interfaces by Schwickerath crack initiation test

    DEFF Research Database (Denmark)

    Boccaccini, D. N.; Sevecek, O.; Frandsen, Henrik Lund

    2017-01-01

    An adaptation of the Schwickerath crack initiation test (ISO 9693) was used to determine the bonding strength between an anode support and three different cathodes with a solid oxide fuel cell interconnect. Interfacial elemental characterization of the interfaces was carried out by SEM/EDS analys...

  1. Magnetron sputtered gadolinia-doped ceria diffusion barriers for metal-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Sønderby, Steffen; Klemensø, Trine; Christensen, Bjarke H.

    2014-01-01

    Gadolinia-doped ceria (GDC) thin films are deposited by reactive magnetron sputtering in an industrial-scale setup and implemented as barrier layers between the cathode and electrolyte in metal-based solid oxide fuel cells consisting of a metal support, an electrolyte of ZrO2 co-doped with Sc2O3...

  2. An initial applications study of ceria-gadolinia solid oxide fuel cells: V. 1

    Energy Technology Data Exchange (ETDEWEB)

    Bauen, A.; Hart, D.; Mould, B.

    1998-11-01

    Fuel cells are categorised by their electrolytes, and the solid oxide fuel cell is so called because its electrolyte consists of a solid ceramic oxide. Commonly this has been a form of zirconia, though other materials are now being considered for their different electrical properties. One of these, ceria doped with gadolinia, shows promise for use in lower temperature regimes than zirconia, and may open up different areas of a future market for consideration. This report considers the opportunities for ceria-gadolinia solid oxide fuel cell systems by comparing them with the application requirements in markets where fuel cells may have potential. The advantages and disadvantages of the technology are analysed, together with the state of the art in research and development. The direction in which research effort needs to move to address some of the issues is assessed. The report then draws conclusions regarding the potential of ceria-gadolinia in solid oxide fuel cell systems and in the energy markets as a whole. It should be noted that while this report is an applications study, some technology assessment has been included. Much of this is found in Volume 2. (author)

  3. Operation of real landfill gas fueled solid oxide fuel cell (SOFC) using internal dry reforming

    DEFF Research Database (Denmark)

    Langnickel, Hendrik; Hagen, Anke

    2017-01-01

    Biomass is one renewable energy source, which is independent from solar radiation and wind effect. Solid oxide fuel cells (SOFC’s) are able to convert landfill gas derived from landfill directly into electricity and heat with a high efficiency. In the present work a planar 16cm2 SOFC cell...... was necessary to prevent poisoning and thereby to decrease the degradation rate....

  4. 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...

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

    International Nuclear Information System (INIS)

    Saievar-Iranizad, E.; Malekifar, A.

    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 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 cell, a mathematical model had been considered in this article. This model simulates and illustrates the interaction, diffusion and oxygen ions exchange into fuel cell. The electrical power of fuel cell due to the ion exchange can be obtained using a simulation method. The ion exchange simulation, diffusion of molecules, their interactions and system development through the mathematical model has been discussed in this paper

  6. Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Persson, Åsa H.; Muhl, Thuy Thanh

    2018-01-01

    For use of metal supported solid oxide fuel cell (MS-SOFC) in mobile applications it is important to reduce the thermal mass to enable fast startup, increase stack power density in terms of weight and volume and reduce costs. In the present study, we report on the effect of reducing the Technical...

  7. Ni modified ceramic anodes for direct-methane solid oxide fuel cells

    Science.gov (United States)

    Xiao, Guoliang; Chen, Fanglin

    2016-01-19

    In accordance with certain embodiments of the present disclosure, a method for fabricating a solid oxide fuel cell is described. The method includes synthesizing a composition having a perovskite present therein. The method further includes applying the composition on an electrolyte support to form an anode and applying Ni to the composition on the anode.

  8. 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...

  9. Investigation of Novel Electrocatalysts for Metal Supported Solid Oxide Fuel Cells - Ru:GDC

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Nielsen, Jimmy; Thydén, Karl Tor Sune

    2015-01-01

    The electrochemical performance and stability of the planar metal supported solid oxide fuel cells (MS-SOFC) with two different electrocatalytically active materials, namely, Ni:GDC and Ru:GDC were investigated. Ru:GDC with an ASR of 0.322 Ωcm2 performed better than Ni:GDC with an ASR of 0.453 Ωc...

  10. A novel reverse osmosis membrane by ferrous sulfate assisted controlled oxidation of polyamide layer

    Science.gov (United States)

    Raval, Hiren D.; Raviya, Mayur R.; Gauswami, Maulik V.

    2017-11-01

    With growing desalination capacity, it is very important to evaluate the performance of thin film composite reverse osmosis (TFC RO) membrane in terms of energy consumption for desalination. There is a trade-off between salt rejection and water-flux of TFC RO membrane. This article presents a novel approach of analyzing the effect of mixture of an oxidizing agent sodium hypochlorite and a reducing agent ferrous sulfate on virgin TFC RO membrane. Experiments were carried out by varying the concentrations of both sodium hypochlorite and ferrous sulfate. The negative charge was induced on the membrane due to the treatment of combination of sodium hypochlorite and ferrous sulfate, thereby resulting in higher rejection of negative ions due to repulsive force. Membrane treated with 1000 mg l-1 sodium hypochlorite and 2000 mg l-1 ferrous sulfate showed the best salt rejection i.e. 96.23%. The characterization was carried out to understand the charge on the membrane surface by Zeta potential, morphology of membrane surface by scanning electron microscope (SEM), surface roughness features by atomic force microscope (AFM) and chemical structural changes by nuclear magnetic resonance (NMR) analysis.

  11. A Singular Perturbation Problem for Steady State Conversion of Methane Oxidation in Reverse Flow Reactor

    Directory of Open Access Journals (Sweden)

    Aang Nuryaman

    2012-11-01

    Full Text Available The governing equations describing the methane oxidation process in reverse flow reactor are given by a set of convective-diffusion equations with a nonlinear reaction term, where temperature and methane conversion are dependent variables. In this study, the process is assumed to be one-dimensional pseudo homogeneous model and takes place with a certain reaction rate in which the whole process of reactor is still workable. Thus, the reaction rate can proceed at a fixed temperature. Under this condition, we restrict ourselves to solve the equations for the conversion only. From the available data, it turns out that the ratio of the diffusion term to the reaction term is small. Hence, this ratio is considered as small parameter in our model and this leads to a singular perturbation problem. In the vicinity of small parameter in front of higher order term, the numerical difficulties will be found. Here, we present an analytical solution by means of matched asymptotic expansions. Result shows that, up to and including the first order of approximation, the solution is in agreement with the exact and numerical solutions of the boundary value problem.

  12. Reverse osmosis desalination of chitosan cross-linked graphene oxide/titania hybrid lamellar membranes.

    Science.gov (United States)

    Deng, Hui; Sun, Penzhan; Zhang, Yingjiu; Zhu, Hongwei

    2016-07-08

    With excellent mass transport properties, graphene oxide (GO)-based lamellar membranes are believed to have great potential in water desalination. In order to quantify whether GO-based membranes are indeed suitable for reverse osmosis (RO) desalination, three sub-micrometer thick GO-based lamellar membranes: GO-only, reduced GO (RGO)/titania (TO) nanosheets and RGO/TO/chitosan (CTS) are prepared, and their RO desalination performances are evaluated in a home-made RO test apparatus. The photoreduction of GO by TO improves the salt rejection, which increases slowly with the membrane thickness. The RGO/TO/CTS hybrid membranes exhibit higher rejection rates of only about 30% (greater than threefold improvement compared with a GO-only membrane) which is still inferior compared to other commercial RO membranes. The low rejection rates mainly arise from the pressure-induced weakening of the ion-GO interlayer interactions. Despite the advantages of simple, low-cost preparation, high permeability and selectivity of GO-based lamellar membranes, as the current desalination performances are not high enough to afford practical application, there still remains a great challenge to realize high performance separation membranes for water desalination applications.

  13. Oxidation Characteristics and Electrical Properties of Doped Mn-Co Spinel Reaction Layer for Solid Oxide Fuel Cell Metal Interconnects

    Directory of Open Access Journals (Sweden)

    Pingyi Guo

    2018-01-01

    Full Text Available To prevent Cr poisoning of the cathode and to retain high conductivity during solid oxide fuel cell (SOFC operation, Cu or La doped Co-Mn coatings on a metallic interconnect is deposited and followed by oxidation at 750 °C. Microstructure and composition of coatings after preparation and oxidation is analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM. High energy micro arc alloying process, a low cost technique, is used to prepare Cu or La doped Co-Mn coatings with the metallurgical bond. When coatings oxidized at 750 °C in air for 20 h and 100 h, Co3O4 is the main oxide on the surface of Co-38Mn-2La and Co-40Mn coatings, and (Co,Mn3O4 spinel continues to grow with extended oxidation time. The outmost scales of Co-33Mn-17Cu are mainly composed of cubic MnCo2O4 spinel with Mn2O3 after oxidation for 20 h and 100 h. The average thickness of oxide coatings is about 60–70 μm after oxidation for 100 h, except that Co-40Mn oxide coatings are a little thicker. Area-specific resistance of Cu/La doped Co-Mn coatings are lower than that of Co-40Mn coating. (Mn,Co3O4/MnCo2O4 spinel layer is efficient at blocking the outward diffusion of chromium and iron.

  14. Solid oxide fuel cell cathode with oxygen-reducing layer

    Science.gov (United States)

    Surdoval, Wayne A.; Berry, David A.; Shultz, Travis

    2018-04-03

    The disclosure provides a SOFC comprised of an electrolyte, anode, and cathode, where the cathode comprises an MIEC and an oxygen-reducing layer. The oxygen-reducing layer is in contact with the MIEC, and the MIEC is generally between and separating the oxygen-reducing layer and the electrolyte. The oxygen-reducing layer is comprised of single element oxides, single element carbonates, or mixtures thereof, and has a thickness of less than about 30 nm. In a particular embodiment, the thickness is less than 5 nm. In another embodiment, the thickness is about 3 monolayers or less. The oxygen-reducing layer may be a continuous film or a discontinuous film with various coverage ratios. The oxygen-reducing layer at the thicknesses described may be generated on the MIEC surface using means known in the art such as, for example, ALD processes.

  15. Ion-reversibility studies in amorphous solids using the two-atom scattering model

    International Nuclear Information System (INIS)

    Oen, O.S.

    1981-06-01

    An analytical two-atom scattering model has been developed to treat the recent discovery of the enhancement near 180 0 of Rutherford backscattering yields from disordered solids. In contrast to conventional calculations of Rutherford backscattering that treat scattering from a single atom only (the backscattering atom), the present model includes the interaction of a second atom lying between the target surface and the backscattering plane. The projectile ion makes a glancing collision with this second atom both before and after it is backscattered. The model predicts an enhancement effect whose physical origin arises from the tolerance of path for those ions whose inward and outward trajectories lie in the vicinity of the critical impact parameter. Results using Moliere scattering show how the yield enhancement depends on ion energy, backscattering depth, exit angle, scattering potential, atomic numbers of the projectile and target, and target density. In the model the critical impact parameter and critical angle play important roles. It is shown that these quantities depend on a single dimensionless parameter and analytical expressions for them are given which are accurate to better than 1%

  16. 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

  17. A novel direct carbon fuel cell by approach of tubular solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Renzhu; Zhao, Chunhua; Li, Junliang; Zeng, Fanrong; Wang, Shaorong; Wen, Tinglian; Wen, Zhaoyin [CAS Key Laboratory of Materials for Energy Conversion, Shanghai Inorganic Energy Materials and Power Source Engineering Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

    2010-01-15

    A direct carbon fuel cell based on a conventional anode-supported tubular solid oxide fuel cell, which consisted of a NiO-YSZ anode support tube, a NiO-ScSZ anode functional layer, a ScSZ electrolyte film, and a LSM-ScSZ cathode, has been successfully achieved. It used the carbon black as fuel and oxygen as the oxidant, and a preliminary examination of the DCFC has been carried out. The cell generated an acceptable performance with the maximum power densities of 104, 75, and 47 mW cm{sup -2} at 850, 800, and 750 C, respectively. These results demonstrate the feasibility for carbon directly converting to electricity in tubular solid oxide fuel cells. (author)

  18. Ceramic membrane as a pretreatment for reverse osmosis: Interaction between marine organic matter and metal oxides

    KAUST Repository

    Dramas, Laure

    2013-02-01

    Scaling and (bio)fouling phenomena can severely alter the performance of the reverse osmosis process during desalination of seawater. Pretreatments must be applied to efficiently remove particles, colloids, and also precursors of the organic fouling and biofouling. Ceramic membranes offer a lot of advantages for micro and ultrafiltration pretreatments because their initial properties can be recovered using more severe cleaning procedure. The study focuses on the interaction between metal oxides and marine organic matter. Experiments were performed at laboratory scale. The first series of experiments focus on the filtration of different fractions of natural organic matter and model compounds solutions on flat disk ceramic membranes (47 mm of diameter) characterized with different pore size and composition. Direct filtration experiments were conducted at 0.7 bar or 2 bars and at room temperature (20 ± 0.5 °C). The efficiency of backflush and alkaline cleaning were eval, and titanium oxides. Each metal oxide corresponds to a specific pore size for the disk ceramic membranes: 80, 60, and 30 nm. Different sizes of metal oxide particles are used to measure the impact of the surface area on the adsorption of the organic matter. Seawaters from the Arabian Gulf and from the Red Sea were collected during algal blooms. Cultures of algae were also performed in the laboratory and in cooperation with woods hole oceanographic institute. Solutions of algal exudates were obtained after a couple of weeks of cultivation followed by sonication. Solutions were successively filtered through GFF (0.7 lm) and 0.45 lm membrane filters before use. The dissolved organic carbon (DOC) concentration of final solution was between 1 and 4 mg/L and showed strong hydrophilic character. These various solutions were prepared with the objective to mimic the dissolved organic matter composition of seawater subjected to algal bloom. Characterization of the solutions of filtration experiments (feed

  19. Innovative Seals for Solid Oxide Fuel Cells (SOFC)

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Raj

    2008-06-30

    A functioning SOFC requires different type of seals such as metal-metal, metal-ceramic, and ceramic-ceramic. These seals must function at high temperatures between 600--900{sup o}C and in oxidizing and reducing environments of the fuels and air. Among the different type of seals, the metal-metal seals can be readily fabricated using metal joining, soldering, and brazing techniques. However, the metal-ceramic and ceramic-ceramic seals require significant research and development because the brittle nature of ceramics/glasses can lead to fracture and loss of seal integrity and functionality. Consequently, any seals involving ceramics/glasses require a significant attention and technology development for reliable SOFC operation. This final report is prepared to describe the progress made in the program on the needs, approaches, and performance of high temperature seals for SOFC. In particular, a new concept of self-healing glass seals is pursued for making seals between metal-ceramic material combinations, including some with a significant expansion mismatch.

  20. 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.

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

    KAUST Repository

    Stojmenović, M.; Zunic, Milan; Gulicovski, J.; Bajuk-Bogdanović, D.; Holclajtner-Antunović, I.; Dodevski, V.; Mentus, S.

    2015-01-01

    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.

  2. An Aurivillius Oxide Based Cathode with Excellent CO2 Tolerance for Intermediate-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Zhu, Yinlong; Zhou, Wei; Chen, Yubo; Shao, Zongping

    2016-07-25

    The Aurivillius oxide Bi2 Sr2 Nb2 MnO12-δ (BSNM) was used as a cobalt-free cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). To the best of our knowledge, the BSNM oxide is the only alkaline-earth-containing cathode material with complete CO2 tolerance that has been reported thus far. BSNM not only shows favorable activity in the oxygen reduction reaction (ORR) at intermediate temperatures but also exhibits a low thermal expansion coefficient, excellent structural stability, and good chemical compatibility with the electrolyte. These features highlight the potential of the new BSNM material as a highly promising cathode material for IT-SOFCs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. 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.

  4. Zinc oxide crystal whiskers as a novel sorbent for solid-phase extraction of flavonoids.

    Science.gov (United States)

    Wang, Licheng; Shangguan, Yangnan; Hou, Xiudan; Jia, Yong; Liu, Shujuan; Sun, Yingxin; Guo, Yong

    2017-08-15

    As a novel solid-phase extraction material, zinc oxide crystal whiskers were used to extract flavonoid compounds and showed good extraction abilities. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and surface area/pore volume characterized the sorbent. The zinc oxide was packed into a solid-phase extraction micro-column and its extraction ability was evaluated by four model flavonoid compounds. The sample loading and elution parameters were optimized and the zinc oxide based analytical method for flavonoids was established. It showed that the method has wide linearities from 1 to 150μg/L and low limits of detection at 0.25μg/L. The relative standard deviations of a single column repeatability and column to column reproducibility were less than 6.8% and 10.6%. Several real samples were analyzed by the established method and satisfactory results were obtained. The interactions between flavonoids and zinc oxide were calculated and proved to be from the Van der Waals' forces between the 4p and 5d orbitals from zinc atom and the neighboring π orbitals from flavonoid phenyl groups. Moreover, the zinc oxide crystal whiskers showed good stability and could be reused more than 50 times under the operation conditions. This work proves that the zinc oxide crystal whiskers are a good candidate for flavonoids enrichment. Copyright © 2017. Published by Elsevier B.V.

  5. Process for forming a homogeneous oxide solid phase of catalytically active material

    Science.gov (United States)

    Perry, Dale L.; Russo, Richard E.; Mao, Xianglei

    1995-01-01

    A process is disclosed for forming a homogeneous oxide solid phase reaction product of catalytically active material comprising one or more alkali metals, one or more alkaline earth metals, and one or more Group VIII transition metals. The process comprises reacting together one or more alkali metal oxides and/or salts, one or more alkaline earth metal oxides and/or salts, one or more Group VIII transition metal oxides and/or salts, capable of forming a catalytically active reaction product, in the optional presence of an additional source of oxygen, using a laser beam to ablate from a target such metal compound reactants in the form of a vapor in a deposition chamber, resulting in the deposition, on a heated substrate in the chamber, of the desired oxide phase reaction product. The resulting product may be formed in variable, but reproducible, stoichiometric ratios. The homogeneous oxide solid phase product is useful as a catalyst, and can be produced in many physical forms, including thin films, particulate forms, coatings on catalyst support structures, and coatings on structures used in reaction apparatus in which the reaction product of the invention will serve as a catalyst.

  6. PREPARATION OF NICKEL - COBALT SPINEL OXIDES NixCO3 ...

    African Journals Online (AJOL)

    degree of crystallinity give rise to reversible nickel incorporation. Pellets ... are of interest in solid oxide fuel cell and this is one of the features which make them attractive ... oxide system can only be obtained in a limited composition extent.

  7. A Novel Drug Delivery Vesicle Development to Reverse Neurodegeneration: Analysis of the Interactions among Protein, Graphene Oxide and Liposome

    Science.gov (United States)

    Miraz, Md Alamin

    In this study, Liposome was decorated with graphene oxide (GO) to synthesize fully-biocompatible theranostic vesicle that can carry bovine serum albumin (BSA) as a model protein. Graphene oxide has been studied as one of the most promising platforms for promoting the growth and repair of neurons. Our graphene oxide based structure could account for the high efficiency of protein loading and deliver to the damaged neuron cell which can reverse the neurodegeneration associated with Alzheimer's disease. The resultant vesicle exhibited high stability in aqueous solution. We investigated the protein adsorption capacity and protein interaction to carbon-based nanomaterials. The Liposome, graphene oxide and bovine serum albumin (BSA) are all biocompatible and hence will not trigger an immune response in vivo.

  8. On the nanostructuring and catalytic promotion of intermediate temperature solid oxide fuel cell (IT-SOFC) cathodes

    Science.gov (United States)

    Serra, José M.; Buchkremer, Hans-Peter

    Solid oxide fuel cells (SOFCs) are highly efficient energy converters for both stationary and mobile purposes. However, their market introduction still demands the reduction of manufacture costs and one possible way to reach this goal is the decrease of the operating temperatures, which entails the improvement of the cathode electrocatalytic properties. An ideal cathode material may have mixed ionic and electronic conductivity as well as proper catalytic properties. Nanostructuring and catalytic promotion of mixed conducting perovskites (e.g. La 0.58Sr 0.4Fe 0.8Co 0.2O 3- δ) seem to be promising approaches to overcoming cathode polarization problems and are briefly illustrated here. The preparation of nanostructured cathodes with relatively high surface area and enough thermal stability enables to improve the oxygen exchange rate and therefore the overall SOFC performance. A similar effect was obtained by catalytic promoting the perovskite surface, allowing decoupling the catalytic and ionic-transport properties in the cathode design. Noble metal incorporation may improve the reversibility of the reduction cycles involved in the oxygen reduction. Under the cathode oxidizing conditions, Pd seems to be partially dissolved in the perovskite structure and as a result very well dispersed.

  9. Solid oxide fuel cell bi-layer anode with gadolinia-doped ceria for utilization of solid carbon fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kellogg, Isaiah D. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 290A Toomey Hall, 400 West 13th Street, Rolla, MO 65409 (United States); Department of Materials Science and Engineering, Missouri University of Science and Technology, 223 McNutt Hall, 1400 N. Bishop, Rolla, MO 65409 (United States); Koylu, Umit O. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 290A Toomey Hall, 400 West 13th Street, Rolla, MO 65409 (United States); Dogan, Fatih [Department of Materials Science and Engineering, Missouri University of Science and Technology, 223 McNutt Hall, 1400 N. Bishop, Rolla, MO 65409 (United States)

    2010-11-01

    Pyrolytic carbon was used as fuel in a solid oxide fuel cell (SOFC) with a yttria-stabilized zirconia (YSZ) electrolyte and a bi-layer anode composed of nickel oxide gadolinia-doped ceria (NiO-GDC) and NiO-YSZ. The common problems of bulk shrinkage and emergent porosity in the YSZ layer adjacent to the GDC/YSZ interface were avoided by using an interlayer of porous NiO-YSZ as a buffer anode layer between the electrolyte and the NiO-GDC primary anode. Cells were fabricated from commercially available component powders so that unconventional production methods suggested in the literature were avoided, that is, the necessity of glycine-nitrate combustion synthesis, specialty multicomponent oxide powders, sputtering, or chemical vapor deposition. The easily-fabricated cell was successfully utilized with hydrogen and propane fuels as well as carbon deposited on the anode during the cyclic operation with the propane. A cell of similar construction could be used in the exhaust stream of a diesel engine to capture and utilize soot for secondary power generation and decreased particulate pollution without the need for filter regeneration. (author)

  10. Improving metabolic efficiency of the reverse beta-oxidation cycle by balancing redox cofactor requirement.

    Science.gov (United States)

    Wu, Junjun; Zhang, Xia; Zhou, Peng; Huang, Jiaying; Xia, Xiudong; Li, Wei; Zhou, Ziyu; Chen, Yue; Liu, Yinghao; Dong, Mingsheng

    2017-11-01

    Previous studies have made many exciting achievements on pushing the functional reversal of beta-oxidation cycle (r-BOX) to more widespread adoption for synthesis of a wide variety of fuels and chemicals. However, the redox cofactor requirement for the efficient operation of r-BOX remains unclear. In this work, the metabolic efficiency of r-BOX for medium-chain fatty acid (C 6 -C 10 , MCFA) production was optimized by redox cofactor engineering. Stoichiometric analysis of the r-BOX pathway and further experimental examination identified NADH as a crucial determinant of r-BOX process yield. Furthermore, the introduction of formate dehydrogenase from Candida boidinii using fermentative inhibitor byproduct formate as a redox NADH sink improved MCFA titer from initial 1.2g/L to 3.1g/L. Moreover, coupling of increasing the supply of acetyl-CoA with NADH to achieve fermentative redox balance enabled product synthesis at maximum titers. To this end, the acetate re-assimilation pathway was further optimized to increase acetyl-CoA availability associated with the new supply of NADH. It was found that the acetyl-CoA synthetase activity and intracellular ATP levels constrained the activity of acetate re-assimilation pathway, and 4.7g/L of MCFA titer was finally achieved after alleviating these two limiting factors. To the best of our knowledge, this represented the highest titer reported to date. These results demonstrated that the key constraint of r-BOX was redox imbalance and redox engineering could further unleash the lipogenic potential of this cycle. The redox engineering strategies could be applied to acetyl-CoA-derived products or other bio-products requiring multiple redox cofactors for biosynthesis. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  11. Nitric oxide treatment for the control of reverse osmosis membrane biofouling.

    Science.gov (United States)

    Barnes, Robert J; Low, Jiun Hui; Bandi, Ratnaharika R; Tay, Martin; Chua, Felicia; Aung, Theingi; Fane, Anthony G; Kjelleberg, Staffan; Rice, Scott A

    2015-04-01

    Biofouling remains a key challenge for membrane-based water treatment systems. This study investigated the dispersal potential of the nitric oxide (NO) donor compound, PROLI NONOate, on single- and mixed-species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis (RO) membranes. The potential of PROLI NONOate to control RO membrane biofouling was also examined. Confocal microscopy revealed that PROLI NONOate exposure induced biofilm dispersal in all but two of the bacteria tested and successfully dispersed mixed-species biofilms. The addition of 40 μM PROLI NONOate at 24-h intervals to a laboratory-scale RO system led to a 92% reduction in the rate of biofouling (pressure rise over a given period) by a bacterial community cultured from an industrial RO membrane. Confocal microscopy and extracellular polymeric substances (EPS) extraction revealed that PROLI NONOate treatment led to a 48% reduction in polysaccharides, a 66% reduction in proteins, and a 29% reduction in microbial cells compared to the untreated control. A reduction in biofilm surface coverage (59% compared to 98%, treated compared to control) and average thickness (20 μm compared to 26 μm, treated compared to control) was also observed. The addition of PROLI NONOate led to a 22% increase in the time required for the RO module to reach its maximum transmembrane pressure (TMP), further indicating that NO treatment delayed fouling. Pyrosequencing analysis revealed that the NO treatment did not significantly alter the microbial community composition of the membrane biofilm. These results present strong evidence for the application of PROLI NONOate for prevention of RO biofouling. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. Long term performance degradation analysis and optimization of anode supported solid oxide fuel cell stacks

    International Nuclear Information System (INIS)

    Parhizkar, Tarannom; Roshandel, Ramin

    2017-01-01

    Highlights: • A degradation based optimization framework is developed. • The cost of electricity based on degradation of solid oxide fuel cells is minimized. • The effects of operating conditions on degradation mechanisms are investigated. • Results show 7.12% lower cost of electricity in comparison with base case. • Degradation based optimization is a beneficial concept for long term analysis. - Abstract: The main objective of this work is minimizing the cost of electricity of solid oxide fuel cell stacks by decelerating degradation mechanisms rate in long term operation for stationary power generation applications. The degradation mechanisms in solid oxide fuel cells are caused by microstructural changes, reactions between lanthanum strontium manganite and electrolyte, poisoning by chromium, carburization on nickel particles, formation of nickel sulfide, nickel coarsening, nickel oxidation, loss of conductivity and crack formation in the electrolyte. The rate of degradation mechanisms depends on the cell operating conditions (cell voltage and fuel utilization). In this study, the degradation based optimization framework is developed which determines optimum operating conditions to achieve a minimum cost of electricity. To show the effectiveness of the developed framework, optimization results are compared with the case that system operates at its design point. Results illustrate optimum operating conditions decrease the cost of electricity by 7.12%. The performed study indicates that degradation based optimization is a beneficial concept for long term performance degradation analysis of energy conversion systems.

  13. A new class of solid oxide metal-air redox batteries for advanced stationary energy storage

    Science.gov (United States)

    Zhao, Xuan

    study, the constituted battery of which is termed solid oxide iron-air redox battery (or SOFeARB). The first objective of this PhD work is aimed at demonstrating the proof-of-concept. By combining a commercial anode-supported tubular RSOFC and Fe-based redox couple, the first generation SOFeARB operated at 800°C has been demonstrated to produce an energy capacity of 348Wh/kg-Fe and round-trip efficiency of 91.5% over twenty stable charge/discharge cycles. Further system optimization leads to an 800°C-SOFeARB comprised of a commercial electrolyte-supported planar RSOFC and Fe-based redox couple; this configuration has become a standard testing system for later studies. The 800°C planar SOFeARBs have been investigated under various current densities and cycle durations. The results show that metal utilization plays a determining role in balancing the energy capacity and round-trip efficiency. Increasing metal utilization increases the energy capacity, but at the expense of lowered round-trip efficiency. The second objective of this work is to lower the operating temperature of SOMARBs to intermediate temperature (IT) range (e.g. 550-650°C). Two changes were made in order to enable operation at IT range: introduction of optimized Sr- and Mg- doped LaGaO3 (LSGM) based RSOFC by tape-casting and infiltration techniques, and optimization of morphology of ESU through innovative synthesis methods. The optimized battery can reach a round-trip efficiency as high as 82.5% and specific energy 91% of the theoretical value in the IT range. The third objective of this work is to improve the cyclic durability and stability of IT-SOFeARBs. The results show that the performance, reversibility and stability of a 550°C-SOFeARB can be significantly improved by nanostructuring energy storage materials synthesized from a low-cost carbothermic reaction. The 100-cycle test explicitly shows an improvement of 12.5%, 27.8% and 214% in specific energy, round-trip efficiency and stability

  14. Highly Reversible Electrochemical Insertion of Lithium, Accompanied With a Marked Color Change, Occuring in Microcrystalline Lithium Nickel Oxide Films

    OpenAIRE

    Campet, G.; Portier, J.; Morel, B.; Ferry, D.; Chabagno, J. M.; Benotmane, L.; Bourrel, M.

    1992-01-01

    Thin films of lithium-nickel oxide, whose texture consists of microcrystallites with an average grain size of 50 Å, permit highly reversible electrochemical insertion of lithium ions in Li+ conducting electrolytes. Therefore, the corresponding materials would be of great interest for energy storage applications. In addition, the lithium insertion/extraction reactions in the nickel-based layers are accompanied with a marked color change, making these films of interest for the devel...

  15. Solid-state electrochromic cell with anodic iridium oxide film electrodes

    International Nuclear Information System (INIS)

    Dautremont-Smith, W.C.; Beni, G.; Schiavone, L.M.; Shay, J.L.

    1979-01-01

    A new solid-state electrochromic cell has been fabricated using an anodic iridium oxide film (AIROF) display electrode. The cell has the symmetric sandwich structure AIROFvertical-barNafionvertical-barAIROF, with the Nafion solid electrolyte opacified by an in situ precipitation technique. A symmetric square-wave voltage of 1.5 V amplitude produces clearly perceivable color changes from pale to dark blue-gray in approx. =1 sec when viewed in diffuse reflection. Good open-circuit optical memory is exhibited:

  16. Immobilization of Radioactive Rare Earth oxide Waste by Solid Phase Sintering

    International Nuclear Information System (INIS)

    Ahn, Byung Gil; Park, Hwan Seo; Kim, Hwan Young; Lee, Han Soo; Kim, In Tae

    2010-01-01

    In the pyroprocessing of spent nuclear fuels, LiCl-KCl waste salt containing radioactive rare earth chlorides are generated. The radioactive rare earth oxides are recovered by co-oxidative precipitation of rare earth elements. The powder phase of rare earth oxide waste must be immobilized to produce a monolithic wasteform suitable for storage and ultimate disposal. The immobilization of these waste developed in this study involves a solid state sintering of the waste with host borosilicate glass and zinc titanate based ceramic matrix (ZIT). And the rare-earth monazite which synthesised by reaction of ammonium di-hydrogen phosphate with the rare earth oxides waste, were immobilized with the borosilicate glass. It is shown that the developed ZIT ceramic wasteform is highly resistant the leaching process, high density and thermal conductivity.

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

    DEFF Research Database (Denmark)

    Harthøj, Anders

    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......, 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...... on the side facing its anode. Two high temperature corrosion issues, which both affect the air side of the interconnect, are especially significant, both of: Formation of thick oxide scales on its surface and evaporation of chromium species from the oxide. The oxide scales increases the electrical resistance...

  18. Reversible switching of wetting properties and erasable patterning of polymer surfaces using plasma oxidation and thermal treatment

    Science.gov (United States)

    Rashid, Zeeshan; Atay, Ipek; Soydan, Seren; Yagci, M. Baris; Jonáš, Alexandr; Yilgor, Emel; Kiraz, Alper; Yilgor, Iskender

    2018-05-01

    Polymer surfaces reversibly switchable from superhydrophobic to superhydrophilic by exposure to oxygen plasma and subsequent thermal treatment are demonstrated. Two inherently different polymers, hydrophobic segmented polydimethylsiloxane-urea copolymer (TPSC) and hydrophilic poly(methyl methacrylate) (PMMA) are modified with fumed silica nanoparticles to prepare superhydrophobic surfaces with roughness on nanometer to micrometer scale. Smooth TPSC and PMMA surfaces are also used as control samples. Regardless of their chemical structure and surface topography, all surfaces display completely reversible wetting behavior changing from hydrophobic to hydrophilic and back for many cycles upon plasma oxidation followed by thermal annealing. Influence of plasma power, plasma exposure time, annealing temperature and annealing time on the wetting behavior of polymeric surfaces are investigated. Surface compositions, textures and topographies are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and white light interferometry (WLI), before and after oxidation and thermal annealing. Wetting properties of the surfaces are determined by measuring their static, advancing and receding water contact angle. We conclude that the chemical structure and surface topography of the polymers play a relatively minor role in reversible wetting behavior, where the essential factors are surface oxidation and migration of polymer molecules to the surface upon thermal annealing. Reconfigurable water channels on polymer surfaces are produced by plasma treatment using a mask and thermal annealing cycles. Such patterned reconfigurable hydrophilic regions can find use in surface microfluidics and optofluidics applications.

  19. Synthesis, characterization and thermal expansion studies on thorium-praseodymium mixed oxide solid solutions

    International Nuclear Information System (INIS)

    Panneerselvam, G.; Antony, M.P.; Srinivasan, T.G.; Vasudeva Rao, P.R.

    2010-01-01

    Full text: Thorium-praseodymium mixed oxide solid solutions containing 15, 25, 40 and 55 mole percent of praseodymia were synthesized by mixing the solutions of thorium nitrate in water and praseodymium oxide (Pr 6 O 11 ) in conc. HNO 3 . Subsequently, their hydroxides were co-precipitated by the addition of aqueous ammonia. Further the precipitate was dried at 50 deg C, calcined at 600 deg C for 4 hours and sintered at 1200 deg C for 6 h in air. X-ray diffraction measurements were performed for phase identification and lattice parameter derivation. Single-phase fluorite structure was observed for all the compositions. Bulk and theoretical densities of solid solutions were also determined by immersion and X-ray techniques. Thermal expansion coefficients and percentage linear thermal expansion of the solid solutions were determined using high temperature X-ray diffraction technique in the temperature range 300 to 1700 K for the first time. The room temperature lattice constants estimated for above compositions are 0.5578, 0.5565, 0.5545 and 0.5526 nm, respectively. The mean linear thermal expansion coefficients for the solid solutions are 15.48 x 10 -6 K -1 , 18.35 x 10 -6 K -1 , 22.65 x 10 -6 K -1 and 26.95 x 10 -6 K -1 , respectively. The percentage linear thermal expansions in this temperature range are 1.68, 1.89, 2.21 and 2.51 respectively. It is seen that the solid solutions are stable up to 1700 K. It is also seen that the effect and nature of the dopant are the important parameters influencing the thermal expansion of the ThO 2 . The lattice parameter of the solid solutions exhibited a decreasing trend with respect to praseodymia addition. The percentage linear thermal expansion of the solid solutions increases steadily with increasing temperature

  20. 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...... rate in air at 900 °C and 800 °C. At 700 °C there is no significant difference in oxidation rate between coated samples and uncoated pre-oxidized Crofer 22 APU. The cross-scale area specific resistance (ASR) is measured in air at 800 °C using La0.85Sr0.1Mn1.1O3 (LSM) contact plates to simulate...... contain significant amounts of Cr after aging, while all three coatings effectively prevent Cr diffusion into the LSM. A complex Cr-rich reaction layer develops at the coating-alloy interface during oxidation. Cu and Fe doping reduce the extent of this reaction layer at 900 °C, while at 800 °C the effect...

  1. Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Talic, Belma; Falk-Windisch, Hannes; Venkatachalam, Vinothini

    2017-01-01

    •Protective action of dense and porous spinel coatings on Crofer 22 APU was compared. •Reduction and re-oxidation produces denser coatings than heat treating in air only. •Coating density has minor influence on oxidation resistance at 800 °C in air. •Dense coating resulted in three times lower Cr...... evaporation rate than porous coating....

  2. Direct electrochemical reduction of solid uranium oxide in molten fluoride salts

    Science.gov (United States)

    Gibilaro, Mathieu; Cassayre, Laurent; Lemoine, Olivier; Massot, Laurent; Dugne, Olivier; Malmbeck, Rikard; Chamelot, Pierre

    2011-07-01

    The direct electrochemical reduction of UO 2 solid pellets was carried out in LiF-CaF 2 (+2 mass.% Li 2O) at 850 °C. An inert gold anode was used instead of the usual reactive sacrificial carbon anode. In this case, oxidation of oxide ions present in the melt yields O 2 gas evolution on the anode. Electrochemical characterisations of UO 2 pellets were performed by linear sweep voltammetry at 10 mV/s and reduction waves associated to oxide direct reduction were observed at a potential 150 mV more positive in comparison to the solvent reduction. Subsequent, galvanostatic electrolyses runs were carried out and products were characterised by SEM-EDX, EPMA/WDS, XRD and microhardness measurements. In one of the runs, uranium oxide was partially reduced and three phases were observed: nonreduced UO 2 in the centre, pure metallic uranium on the external layer and an intermediate phase representing the initial stage of reduction taking place at the grain boundaries. In another run, the UO 2 sample was fully reduced. Due to oxygen removal, the U matrix had a typical coral-like structure which is characteristic of the pattern observed after the electroreduction of solid oxides.

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

    International Nuclear Information System (INIS)

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

    2001-01-01

    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% CO 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. (authors)

  4. Solid-to-solid oxidation of a vanadium(IV) to a vanadium(V) compound: chemisty of a sulfur-containing siderophore.

    Science.gov (United States)

    Chatterjee, Pabitra B; Crans, Debbie C

    2012-09-03

    Visible light facilitates a solid-to-solid photochemical aerobic oxidation of a hunter-green microcrystalline oxidovanadium(IV) compound (1) to form a black powder of cis-dioxidovanadium(V) (2) at ambient temperature. The siderophore ligand pyridine-2,6-bis(thiocarboxylic acid), H(2)L, is secreted by a microorganism from the Pseudomonas genus. This irreversible transformation of a metal monooxo to a metal dioxo complex in the solid state in the absence of solvent is unprecedented. It serves as a proof-of-concept reaction for green chemistry occurring in solid matrixes.

  5. Method of making sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

    Science.gov (United States)

    Isenberg, Arnold O.

    1989-01-01

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

  6. A solid dietary fat containing fish oil redistributes lipoprotein subclasses without increasing oxidative stress in men

    DEFF Research Database (Denmark)

    Tholstrup, T.; Hellgren, Lars; Petersen, M.

    2004-01-01

    , a solid dietary fat containing (n-3) PUFA decreased plasma TAG, VLDL, and IDL cholesterol, and redistributed lipoprotein subclasses in LDL and HDL, with a higher concentration of the larger and less atherogenic subfractions. These changes took place without an increase in oxidative stress as measured...... of F than O fat (P oxidation measured as the ratio of plasma isoprostanes F-2 to arachidonic acid and urinary isoprostanes, whereas the vitamin E activity/plasma total lipids ratio was higher after intake of F than O (P = 0.008). In conclusion...

  7. Direct ethanol solid oxide fuel cell operating in gradual internal reforming

    Science.gov (United States)

    Nobrega, S. D.; Galesco, M. V.; Girona, K.; de Florio, D. Z.; Steil, M. C.; Georges, S.; Fonseca, F. C.

    2012-09-01

    An electrolyte supported solid oxide fuel cell (SOFC) using standard electrodes, doped-lanthanum manganite cathode and Ni-cermet anode, was operated with direct (anhydrous) ethanol for more than 100 h, delivering essentially the same power output as running on hydrogen. A ceria-based layer provides the catalytic activity for the gradual internal reforming, which uses the steam formed by the electrochemical oxidation of hydrogen for the decomposition of ethanol. Such a concept opens up the way for multi-fuel SOFCs using standard components and a catalytic layer.

  8. Thermodynamic Analysis of an Integrated Solid Oxide Fuel Cell Cycle with a Rankine Cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2010-01-01

    Hybrid systems consisting of Solid Oxide Fuel Cells (SOFC) on the top of a Steam Turbine (ST) are investigated. The plants are fired by natural gas (NG). A desulfurization reactor removes the sulfur content in the fuel while a pre-reformer breaks down the heavier hydrocarbons. The pre-treated fuel......% are achieved which is considerably higher than the conventional Combined Cycles (CC). Both ASR (Adiabatic Steam Reformer) and CPO (Catalytic Partial Oxidation) fuel pre-reformer reactors are considered in this investigation....

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

    Science.gov (United States)

    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.

  10. Participation of the Third Order Optical Nonlinearities in Nanostructured Silver Doped Zinc Oxide Thin Solid Films

    Directory of Open Access Journals (Sweden)

    C. Torres-Torres

    2012-01-01

    Full Text Available We report the transmittance modulation of optical signals in a nanocomposite integrated by two different silver doped zinc oxide thin solid films. An ultrasonic spray pyrolysis approach was employed for the preparation of the samples. Measurements of the third-order nonlinear optical response at a nonresonant 532 nm wavelength of excitation were performed using a vectorial two-wave mixing. It seems that the separated contribution of the optical nonlinearity associated with each film noticeable differs in the resulting nonlinear effects with respect to the additive response exhibited by the bilayer system. An enhancement of the optical Kerr nonlinearity is predicted for prime number arrays of the studied nanoclusters in a two-wave interaction. We consider that the nanostructured morphology of the thin solid films originates a strong modification of the third-order optical phenomena exhibited by multilayer films based on zinc oxide.

  11. Some regularities in aging of solid oxide electrolytes ZrO2+Y2O3

    International Nuclear Information System (INIS)

    Vlasov, A.N.

    1983-01-01

    A study was made on the temperature effect on the rate and depth of aging of solid oxide electrolytes ZrO 2 +Y 2 O 3 and ZrO 2 +Ho 2 O 3 , stabilized by 10-15 mol.% R 2 O 3 following isothermal hold-up during 2000-3000 h in the 725-1550 deg C range in oxidizing medium. It was shown that solid electrolyte aging proceeds only at temperatures below a certain boundary value. The depth of complete aging at that increases with the R 2 O 3 concentration and a temperature decrease. The aging rate depends substantially on both temperature and concentration of a stabilizing addition. A decrease in the electric conductivity with time is accompanied by an increase in the conductivity activation energy

  12. An afterburner-powered methane/steam reformer for a solid oxide fuel cells application

    Science.gov (United States)

    Mozdzierz, Marcin; Chalusiak, Maciej; Kimijima, Shinji; Szmyd, Janusz S.; Brus, Grzegorz

    2018-04-01

    Solid oxide fuel cell (SOFC) systems can be fueled by natural gas when the reforming reaction is conducted in a stack. Due to its maturity and safety, indirect internal reforming is usually used. A strong endothermic methane/steam reforming process needs a large amount of heat, and it is convenient to provide thermal energy by burning the remainders of fuel from a cell. In this work, the mathematical model of afterburner-powered methane/steam reformer is proposed. To analyze the effect of a fuel composition on SOFC performance, the zero-dimensional model of a fuel cell connected with a reformer is formulated. It is shown that the highest efficiency of a solid oxide fuel cell is achieved when the steam-to-methane ratio at the reforming reactor inlet is high.

  13. Method and system for purification of gas streams for solid oxide cells

    DEFF Research Database (Denmark)

    2011-01-01

    of: - providing at least one scrubber in the gas stream at the inlet side of the first electrode of the solid oxide cell; and/or providing at least one scrubber in the gas stream at the inlet side of the second electrode of the solid oxide cell; and - purifying the gas streams towards the first...... and second electrode; wherein the at least one scrubber in the gas stream at the inlet side of the first electrode and/or the at least one scrubber in the gas stream at the inlet side of the second electrode comprises a material suitable as an electrolyte material and a material suitable as an electrode...... material, and wherein the material suitable as an electrolyte material and a material suitable as an electrode material form triple phase boundaries similar to or identical to the triple phase boundaries of the electrode for which the gas stream is purified with the at least one scrubber....

  14. Effects of accelerated degradation on metal supported thin film-based solid oxide fuel cell

    DEFF Research Database (Denmark)

    Reolon, R. P.; Sanna, S.; Xu, Yu

    2018-01-01

    A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte and nanostruct......A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte......, electrochemical performances are steady, indicating the stability of the cell. Under electrical load, a progressive degradation is activated. Post-test analysis reveals both mechanical and chemical degradation of the cell. Cracks and delamination of the thin films promote a significant nickel diffusion and new...

  15. Operation strategy for solid oxide fuel cell systems for small-scale stationary applications

    DEFF Research Database (Denmark)

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

    2009-01-01

    Solid oxide fuel cell micro cogeneration systems have the potential to reduce domestic energy consumption by providing both heat and power on site without transmission losses. The high grade heat produced during the operation of the power causes high thermal transients during startup/shutdown pha......Solid oxide fuel cell micro cogeneration systems have the potential to reduce domestic energy consumption by providing both heat and power on site without transmission losses. The high grade heat produced during the operation of the power causes high thermal transients during startup....../shutdown phases and degrades the fuel cells. To counteract the degradation, the system has not to be stressed with rapid load variation during the operation. The analysis will consider an average profile for heat and power demand of a family house. Finally data analysis and power system limitations will be used...

  16. 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...... to describe the high temperature inelastic deformational behaviors of Crofer 22 APU used for metallic interconnects in SOFC stacks.......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...

  17. Feasibility of solid oxide fuel cell dynamic hydrogen coproduction to meet building demand

    Science.gov (United States)

    Shaffer, Brendan; Brouwer, Jacob

    2014-02-01

    A dynamic internal reforming-solid oxide fuel cell system model is developed and used to simulate the coproduction of electricity and hydrogen while meeting the measured dynamic load of a typical southern California commercial building. The simulated direct internal reforming-solid oxide fuel cell (DIR-SOFC) system is controlled to become an electrical load following device that well follows the measured building load data (3-s resolution). The feasibility of the DIR-SOFC system to meet the dynamic building demand while co-producing hydrogen is demonstrated. The resulting thermal responses of the system to the electrical load dynamics as well as those dynamics associated with the filling of a hydrogen collection tank are investigated. The DIR-SOFC system model also allows for resolution of the fuel cell species and temperature distributions during these dynamics since thermal gradients are a concern for DIR-SOFC.

  18. 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

  19. Spray pyrolysis of doped-ceria barrier layers for solid oxide fuel cells

    DEFF Research Database (Denmark)

    Szymczewska, Dagmara; Chrzan, Aleksander; Karczewski, Jakub

    2017-01-01

    Gadolinium doped ceria (Ce0.8Gd0.2O2 − x-CGO) layer fabricated by spray pyrolysis is investigated as the diffusion barrier for solid oxide fuel cell. It is deposited between the La0.6Sr0.4FeO3 − δ cathode and the yttria stabilized zirconia electrolyte to mitigate harmful interdiffusion...

  20. Design and performance of tubular flat-plate solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Matsushima, T.; Ikeda, D.; Kanagawa, H. [NTT Integrated Information & Energy Systems Labs., Tokyo (Japan)] [and others

    1996-12-31

    With the growing interest in conserving the environmental conditions, much attention is being paid to Solid Oxide Fuel Cell (SOFC), which has high energy-conversion efficiency. Many organizations have conducted studies on tubular and flat type SOFCs. Nippon Telegraph and Telephone Corporation (NTT) has studied a combined tubular flat-plate SOFC, and already presented the I-V characteristics of a single cell. Here, we report the construction of a stack of this SOFC cell and successful generation tests results.

  1. Nature of the activates places of the acid solid catalysts of the sulphated metallic oxides type

    International Nuclear Information System (INIS)

    Gomez, Miguel A; Fontalvo Javier

    1998-01-01

    In this revision the state of the knowledge is presented with respect to the understanding of the nature of the active places for the strongly acid solid catalysts of the type sulphated metallic oxides. The results presented by means of models are based on the characterization of the properties physicochemical carried out by means of technical as XPS, to GO, NMR etc., and the evaluation of the catalytic activity in different applications

  2. Solid Oxide Cell and Stack Testing, Safety and Quality Assurance (SOCTESQA)

    OpenAIRE

    Auer, Corinna; Lang, Michael; Couturier, Karine; Nielsen, Eva Ravn; Mc Phail, Stephen; Tsotridis, Georgios; FU, Qingxi; Chan, Siew Hwa

    2015-01-01

    The market penetration of fuel and electrolysis cell energy systems in Europe requires the development of reliable assessment, testing and prediction of performance and durability of solid oxide cells and stacks (SOC). To advance in this field the EU-project “SOCTESQA” was launched in May 2014. Partners from different countries in Europe and one external party from Singapore are working together to develop uniform and industry wide test procedures and protocols for SOC cell/stack assembly. In...

  3. Electron paramagnetic resonance response and magnetic interactions in ordered solid solutions of lithium nickel oxides

    Energy Technology Data Exchange (ETDEWEB)

    Azzoni, C.B. [Istituto Nazionale di Fisica della Materia, Dipartimento di Fisica ' Alessandro Volta' , Universita di Pavia, Pavia (Italy); Paleari, A. [Istituto Nazionale di Fisica della Materia, Dipartimento di Fisica, Universita di Milano, Milan (Italy); Massarotti, V.; Capsoni, D. [Dipartimento di Chimica-Fisica, Universita di Pavia, Pavia (Italy)

    1996-09-23

    EPR data of ordered solid solutions of lithium nickel oxides are reported as a function of the lithium content. The features of the signal and the EPR centre density are analysed by a model of dynamical trapping of holes in [(Ni{sup 2+}-O-Ni{sup 2+})-h{sup +}] complexes. The possible origin of the interactions responsible for the magnetic ordering and some features of the transport properties are also discussed. (author)

  4. Life Time Performance Characterization of Solid Oxide Electrolysis Cells for Hydrogen Production

    DEFF Research Database (Denmark)

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

    2015-01-01

    Solid oxide electrolysis cells (SOECs) offer a promising technological solution for efficient energy conversion and production of hydrogen or syngas. The commercialization of the SOEC technology can be promoted if SOECs can be operated at high current density with stable performance over ~5 years...... - 3 years (continuous operation, setting 1.5 V as the upper voltage defining “end of life”). The results provide technological input to future design of electrolysis plants for hydrogen production. © 2015 ECS - The Electrochemical Society...

  5. 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.

  6. Solid State Electrochemical Sensors for Nitrogen Oxide (NOx) Detection in Lean Exhaust Gases

    OpenAIRE

    Rheaume, Jonathan Michael

    2010-01-01

    Solid state electrochemical sensors that measure nitrogen oxides (NOx) in lean exhaust have been investigated in order to help meet future on-board diagnostic (OBD) regulations for diesel vehicles. This impedancemetric detection technology consists of a planar, single cell sensor design with various sensing electrode materials and yttria-stabilized zirconia (YSZ) as the electrolyte. No reference to ambient air is required. An impedance analysis method yields a signal that is proportional to t...

  7. Effect on Cs removal of solid-phase metal oxidation in metal ferrocyanides

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Keun-Young; Kim, Jimin; Oh, Maengkyo; Lee, Eil-Hee; Kim, Kwang-Wook; Chung, Dong-Yong; Moon, Jei-Kwon [Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of).

    2017-07-01

    Metal ferrocyanides (MFCs) have been studied for many years and are regarded as efficient adsorbents for the selective removal of radioactive cesium (Cs) from contaminated aqueous solutions. Although their efficiency has been demonstrated, various investigations on the physicochemical, thermal, and radiological stability of the solids of MFCs are required to enhance the applicability of MFCs in the treatment process. We observed that the Cs adsorption efficiencies of cobalt and nickel ferrocyanides decreased as their aging period increased, while the Cs adsorption efficiencies of copper and zinc ferrocyanides did not decrease. The tendencies of these ferrocyanides were accelerated by exposure of the solids at a higher temperature for a longer time. Our comprehensive analyses demonstrated that only the oxidizable metals in the MFCs can be oxidized by aging time and increasing temperature; also, this affects the Cs removal efficiency by decreasing the exchangeable sites in the solids. The chemical stability of MFCs is very important for the optimization of the synthesis and storage conditions.

  8. A novel approach to model the transient behavior of solid-oxide fuel cell stacks

    Science.gov (United States)

    Menon, Vikram; Janardhanan, Vinod M.; Tischer, Steffen; Deutschmann, Olaf

    2012-09-01

    This paper presents a novel approach to model the transient behavior of solid-oxide fuel cell (SOFC) stacks in two and three dimensions. A hierarchical model is developed by decoupling the temperature of the solid phase from the fluid phase. The solution of the temperature field is considered as an elliptic problem, while each channel within the stack is modeled as a marching problem. This paper presents the numerical model and cluster algorithm for coupling between the solid phase and fluid phase. For demonstration purposes, results are presented for a stack operated on pre-reformed hydrocarbon fuel. Transient response to load changes is studied by introducing step changes in cell potential and current. Furthermore, the effect of boundary conditions and stack materials on response time and internal temperature distribution is investigated.

  9. First-Principles Modeling of ThO2 Solid Solutions with Oxides of Trivalent Cations

    Science.gov (United States)

    Alexandrov, Vitaly; Asta, Mark; Gronbech-Jensen, Niels

    2010-03-01

    Solid solutions formed by doping ThO2 with oxides of trivalent cations, such as Y2O3 and La2O3, are suitable for solid electrolyte applications, similar to doped zirconia and ceria. ThO2 has also been gaining much attention as an alternative to UO2 in nuclear energy applications, the aforementioned trivalent cations being important fission products. In both cases the mixing energetics and short-range ordering/clustering are key to understanding structural and transport properties. Using first-principles atomistic calculations, we address intra- and intersublattice interactions for both cation and anion sublattices in ThO2-based fluorite-type solid solutions and compare the results with similar modeling studies for related trivalent-doped zirconia systems.

  10. Thermodynamic analysis of combined Solid Oxide Electrolyzer and Fischer–Tropsch processes

    International Nuclear Information System (INIS)

    Stempien, Jan Pawel; Ni, Meng; Sun, Qiang; Chan, Siew Hwa

    2015-01-01

    In this paper a thermodynamic analysis and simple optimization of a combined Solid Oxide Electrolyzer Cell and Fisher–Tropsch Synthesis processes for sustainable hydrocarbons fuel production is reported. Comprehensive models are employed to describe effects of temperature, pressure, reactant composition and molar flux and flow on the system efficiency and final production distribution. The electrolyzer model was developed in-house and validated with experimental data of a typical Solid Oxide Electrolyzer. The Fischer–Tropsch Synthesis model employed lumped kinetics of syngas utilization, which includes inhibiting effect of water content and kinetics of Water–Gas Shift reaction. Product distribution model incorporated olefin re-adsorption and varying physisorption and solubility of hydrocarbons with their carbon number. The results were compared with those reported by Becker et al. with simplified analysis of such process. In the present study an opposite effect of operation at elevated pressure was observed. Proposed optimized system achieved overall efficiency of 66.67% and almost equal spread of light- (31%wt), mid-(36%wt) and heavy-hydrocarbons (33%wt). Paraffins contributed the majority of the yield. - Highlights: • Analysis of Solid Oxide Electrolyzer combined with Fisher Tropsch process. • Efficiency of converting water and carbon dioxide into synthetic fuels above 66%. • Effects of process temperature, pressure, gas flux and compositions were analyzed

  11. PPARγ agonist pioglitazone reverses pulmonary hypertension and prevents right heart failure via fatty acid oxidation.

    Science.gov (United States)

    Legchenko, Ekaterina; Chouvarine, Philippe; Borchert, Paul; Fernandez-Gonzalez, Angeles; Snay, Erin; Meier, Martin; Maegel, Lavinia; Mitsialis, S Alex; Rog-Zielinska, Eva A; Kourembanas, Stella; Jonigk, Danny; Hansmann, Georg

    2018-04-25

    Right ventricular (RV) heart failure is the leading cause of death in pulmonary arterial hypertension (PAH). Peroxisome proliferator-activated receptor γ (PPARγ) acts as a vasoprotective metabolic regulator in smooth muscle and endothelial cells; however, its role in the heart is unclear. We report that deletion of PPARγ in cardiomyocytes leads to biventricular systolic dysfunction and intramyocellular lipid accumulation in mice. In the SU5416/hypoxia (SuHx) rat model, oral treatment with the PPARγ agonist pioglitazone completely reverses severe PAH and vascular remodeling and prevents RV failure. Failing RV cardiomyocytes exhibited mitochondrial disarray and increased intramyocellular lipids (lipotoxicity) in the SuHx heart, which was prevented by pioglitazone. Unbiased ventricular microRNA (miRNA) arrays, mRNA sequencing, and lipid metabolism studies revealed dysregulation of cardiac hypertrophy, fibrosis, myocardial contractility, fatty acid transport/oxidation (FAO), and transforming growth factor-β signaling in the failing RV. These epigenetic, transcriptional, and metabolic alterations were modulated by pioglitazone through miRNA/mRNA networks previously not associated with PAH/RV dysfunction. Consistently, pre-miR-197 and pre-miR-146b repressed genes that drive FAO ( Cpt1b and Fabp4 ) in primary cardiomyocytes. We recapitulated our major pathogenic findings in human end-stage PAH: (i) in the pressure-overloaded failing RV (miR-197 and miR-146b up-regulated), (ii) in peripheral pulmonary arteries (miR-146b up-regulated, miR-133b down-regulated), and (iii) in plexiform vasculopathy (miR-133b up-regulated, miR-146b down-regulated). Together, PPARγ activation can normalize epigenetic and transcriptional regulation primarily related to disturbed lipid metabolism and mitochondrial morphology/function in the failing RV and the hypertensive pulmonary vasculature, representing a therapeutic approach for PAH and other cardiovascular/pulmonary diseases. Copyright

  12. Strong and reversible modulation of carbon nanotube-silicon heterojunction solar cells by an interfacial oxide layer.

    Science.gov (United States)

    Jia, Yi; Cao, Anyuan; Kang, Feiyu; Li, Peixu; Gui, Xuchun; Zhang, Luhui; Shi, Enzheng; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai

    2012-06-21

    Deposition of nanostructures such as carbon nanotubes on Si wafers to make heterojunction structures is a promising route toward high efficiency solar cells with reduced cost. Here, we show a significant enhancement in the cell characteristics and power conversion efficiency by growing a silicon oxide layer at the interface between the nanotube film and Si substrate. The cell efficiency increases steadily from 0.5% without interfacial oxide to 8.8% with an optimal oxide thickness of about 1 nm. This systematic study reveals that formation of an oxide layer switches charge transport from thermionic emission to a mixture of thermionic emission and tunneling and improves overall diode properties, which are critical factors for tailoring the cell behavior. By controlled formation and removal of interfacial oxide, we demonstrate oscillation of the cell parameters between two extreme states, where the cell efficiency can be reversibly altered by a factor of 500. Our results suggest that the oxide layer plays an important role in Si-based photovoltaics, and it might be utilized to tune the cell performance in various nanostructure-Si heterojunction structures.

  13. Oxidation of volatile organic vapours in air by solid potassium permanganate.

    Science.gov (United States)

    Mahmoodlu, Mojtaba Ghareh; Hartog, Niels; Majid Hassanizadeh, S; Raoof, Amir

    2013-06-01

    Volatile organic compounds (VOCs) may frequently contaminate groundwater and pose threat to human health when migrating into the unsaturated soil zone and upward to the indoor air. The kinetic of chemical oxidation has been investigated widely for dissolved VOCs in the saturated zone. But, so far there have been few studies on the use of in situ chemical oxidation (ISCO) of vapour phase contaminants. In this study, batch experiments were carried out to evaluate the oxidation of trichloroethylene (TCE), ethanol, and toluene vapours by solid potassium permanganate. Results revealed that solid potassium permanganate is able to transform the vapour of these compounds into harmless oxidation products. The degradation rates for TCE and ethanol were higher than for toluene. The degradation process was modelled using a kinetic model, linear in the gas concentration of VOC [ML(-3)] and relative surface area of potassium permanganate grains (surface area of potassium permanganate divided by gas volume) [L(-1)]. The second-order reaction rate constants for TCE, ethanol, and toluene were found to be equal to 2.0×10(-6) cm s(-1), 1.7×10(-7) cm s(-1), and 7.0×10(-8) cm s(-1), respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Curvature and Strength of Ni-YSZ Solid Oxide Half-Cells After Redox Treatments

    DEFF Research Database (Denmark)

    Faes, Antonin; Frandsen, Henrik Lund; Pihlatie, Mikko

    2010-01-01

    One of the main drawbacks of anode-supported solid oxide fuel cell technology is the limited capability to withstand reduction and oxidation (“RedOx”) of the Ni phase. This study compares the effect of RedOx cycles on curvature and strength of half-cells, composed of a nickel-yttria-stabilized-zi......One of the main drawbacks of anode-supported solid oxide fuel cell technology is the limited capability to withstand reduction and oxidation (“RedOx”) of the Ni phase. This study compares the effect of RedOx cycles on curvature and strength of half-cells, composed of a nickel...... it is calculated analytically from the force. In this calculation the thermal stresses are estimated from the curvature of the half-cell. For each treatment, more than 30 samples are tested. About 20 ball-on-ring samples are laser cut from one original 12×12 cm2 half-cell. Curvature and porosity are measured...

  15. 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.

  16. Variable valence of praseodymium in rare-earth oxide solid solutions

    International Nuclear Information System (INIS)

    Kravchinskaya, M.V.; Merezhinskii, K.Y.; Tikhonov, P.A.

    1986-01-01

    Solid solutions of elevated praseodymium oxide content have interesting electrical properties, making them the basis for the manufacture of high-temperature electrically conducting materials. Establishment of the composition-structure-valence state relationships enables control of the material properties. The authors performed investigations using a thermogravimetric apparatus with an electronic microbalance of type EM-5-3M, and using x-ray phase analysis of powders (DRON-1 diffractometer, CuK /SUB alpha/ -radiation). The authors also studied the kinetics of praseodymium oxidation with a thermogravimetric apparatus under isothermal conditions. Evaluation of the results with the equation of Kolmogorov, Erofeev, and Avraam indicates that the process is limited by the chemical oxidation of praseodymium and not by diffusion

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

    International Nuclear Information System (INIS)

    Fabbri, Emiliana; Pergolesi, Daniele; Traversa, Enrico

    2010-01-01

    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 0 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. (topical review)

  18. Creep behaviour of porous metal supports for solid oxide fuel cells

    DEFF Research Database (Denmark)

    Boccaccini, Dino; Frandsen, Henrik Lund; Sudireddy, Bhaskar Reddy

    2014-01-01

    The creep behaviour of porous ironechromium alloy used as solid oxide fuel cell support was investigated, and the creep parameters are compared with those of dense strips of similar composition under different testing conditions. The creep parameters were determined using a thermo......-mechanical analyser with applied stresses in the range from 1 to 15 MPa and temperatures between 650 and 800 _C. The GibsoneAshby and Mueller models developed for uniaxial creep of open-cell foams were used to analyse the results. The influence of scale formation on creep behaviour was assessed by comparing the creep...... data for the samples tested in reducing and oxidising atmospheres. The influence of preoxidation on creep behaviour was also investigated. In-situ oxidation during creep experiments increases the strain rate while pre-oxidation of samples reduces it. Debonding of scales at high stress regime plays...

  19. Reversible aqueous zinc/manganese oxide energy storage from conversion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Huilin; Shao, Yuyan; Yan, Pengfei; Cheng, Yingwen; Han, Kee Sung; Nie, Zimin; Wang, Chongmin; Yang, Jihui; Li, Xiaolin; Bhattacharya, Priyanka; Mueller, Karl T.; Liu, Jun

    2016-04-18

    Rechargeable aqueous batteries are attracting growing interest for energy storage due to their low cost and high safety. Fundamental understanding of highly reversible aqueous reactions is critical for building high-performance batteries. Herein, we studied the reversibility of Zn/MnO2 battery chemistry in mild aqueous MnSO4 electrolytes. α-MnO2 nanofibers were used as a high performance cathode. Our study provides good evidence for a conversion reaction mechanism through reversible formation of short nanorods and nanoparticle aggregates. This reversible conversion reaction provides an operating voltage of 1.44 V, high capacity of 285 mAh g-1, excellent rate and capacity retention of 92% after 5000 cycles. Zn metal anode also shows high reversibility in the mild aqueous MnSO4 electrolytes. The highly reversible and stable chemistries in aqueous Zn/MnO2 batteries open new opportunity for energy storage technologies with potentially high energy density, high safety, and low cost.

  20. Numerical modelling of emissions of nitrogen oxides in solid fuel combustion.

    Science.gov (United States)

    Bešenić, Tibor; Mikulčić, Hrvoje; Vujanović, Milan; Duić, Neven

    2018-06-01

    Among the combustion products, nitrogen oxides are one of the main contributors to a negative impact on the environment, participating in harmful processes such as tropospheric ozone and acid rains production. The main source of emissions of nitrogen oxides is the human combustion of fossil fuels. Their formation models are investigated and implemented with the goal of obtaining a tool for studying the nitrogen-containing pollutant production. In this work, numerical simulation of solid fuel combustion was carried out on a three-dimensional model of a drop tube furnace by using the commercial software FIRE. It was used for simulating turbulent fluid flow and temperature field, concentrations of the reactants and products, as well as the fluid-particles interaction by numerically solving the integro-differential equations describing these processes. Chemical reactions mechanisms for the formation of nitrogen oxides were implemented by the user functions. To achieve reasonable calculation times for running the simulations, as well as efficient coupling with the turbulent mixing process, the nitrogen scheme is limited to sufficiently few homogeneous reactions and species. Turbulent fluctuations that affect the reaction rates of nitrogen oxides' concentration are modelled by probability density function approach. Results of the implemented model for nitrogen oxides' formation from coal and biomass are compared to the experimental data. Temperature, burnout and nitrogen oxides' concentration profiles are compared, showing satisfactory agreement. The new model allows the simulation of pollutant formation in the real-world applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Models for solid oxide fuel cell systems exploitation of models hierarchy for industrial design of control and diagnosis strategies

    CERN Document Server

    Marra, Dario; Polverino, Pierpaolo; Sorrentino, Marco

    2016-01-01

    This book presents methodologies for optimal design of control and diagnosis strategies for Solid Oxide Fuel Cell systems. A key feature of the methodologies presented is the exploitation of modelling tools that balance accuracy and computational burden.

  2. Solid oxide galvanic cell for determination of Gibbs energy of formation of Tb6UO12(s)

    International Nuclear Information System (INIS)

    Sahu, Manjulata; Dash, Smruti

    2013-01-01

    Citrate-nitrate combustion method was used to synthesise Tb 6 UO 12 (s). Gibbs energy of formation of Tb 6 UO 12 (s) was measured using solid oxide galvanic cell in the temperature range 957-1175 K. (author)

  3. Solid Oxide Fuel Cell/Turbine Hybrid Power System for Advanced Aero-propulsion and Power, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Solid oxide fuel cell (SOFC)/ gas turbine hybrid power systems (HPSs) have been recognized by federal agencies and other entities as having the potential to operate...

  4. Solid-state ionics: Studies of lithium-conducting sulfide glasses and a superconducting oxide compound

    International Nuclear Information System (INIS)

    Ahn, Byung Tae.

    1989-01-01

    The first part of this work studies lithium-conducting sulfide glasses for battery applications, while the second part studies the thermodynamic properties of a superconducting oxide compound by using an oxide electrolyte. Lithium conducting glasses based on the SiS 2 -Li 2 S system are possible solid electrolytes for high-energy-density lithium batteries. The foremost requirement for solid electrolytes is that they should have high ionic conductivities. Unfortunately, most crystalline lithium conductors have low ionic conductivities at room temperature. However, glass ionic conductors show higher ionic conductivities than do crystalline forms of the same material. In addition to higher ionic conductivities, glasses appear to have several advantages over crystalline materials. These advantages include isotropic conductivity, absence of grain boundary effects, ease of glass forming, and the potential for a wide range of stability to oxidizing and reducing conditions. Using pyrolitic graphite-coated quartz ampoules, new ternary compounds and glasses in the SiS 2 -Li 2 S system were prepared. Several techniques were used to characterize the materials: powder x-ray diffraction, differential thermal analysis, differential scanning calorimetry, and AC impedance spectroscopy. The measured lithium conductivity of the sulfide glasses was one of the highest among the known solid lithium conductors. Measuring the equilibrium open circuit voltages assisted in determining the electrochemical stabilities of the ternary compounds and glasses with respect to pure Li. A solid-state ionic technique called oxygen coulometric titration was used to measure the thermodynamic stability, the oxygen stoichiometry, and the effects of the oxygen stoichiometry, and the effects of the oxygen stoichiometry and the cooling rate on superconductivity of the YBa 2 Cu 3 O 7-x compound were investigated

  5. Reaction of hydrogen peroxide with uranium zirconium oxide solid solution - Zirconium hinders oxidative uranium dissolution

    Science.gov (United States)

    Kumagai, Yuta; Takano, Masahide; Watanabe, Masayuki

    2017-12-01

    We studied oxidative dissolution of uranium and zirconium oxide [(U,Zr)O2] in aqueous H2O2 solution to estimate (U,Zr)O2 stability to interfacial reactions with H2O2. Studies on the interfacial reactions are essential for anticipating how a (U,Zr)O2-based molten fuel may chemically degrade after a severe accident. The fuel's high radioactivity induces water radiolysis and continuous H2O2 generation. Subsequent reaction of the fuel with H2O2 may oxidize the fuel surface and facilitate U dissolution. We conducted our experiments with (U,Zr)O2 powder (comprising Zr:U mole ratios of 25:75, 40:60, and 50:50) and quantitated the H2O2 reaction via dissolved U and H2O2 concentrations. Although (U,Zr)O2 reacted more quickly than UO2, the dissolution yield relative to H2O2 consumption was far less for (U,Zr)O2 compared to that of UO2. The reaction kinetics indicates that most of the H2O2 catalytically decomposed to O2 at the surface of (U,Zr)O2. We confirmed the H2O2 catalytic decomposition via O2 production (quantitative stoichiometric agreement). In addition, post-reaction Raman scattering spectra of the undissolved (U,Zr)O2 showed no additional peaks (indicating a lack of secondary phase formation). The (U,Zr)O2 matrix is much more stable than UO2 against H2O2-induced oxidative dissolution. Our findings will improve understanding on the molten fuels and provide an insight into decommissioning activities after a severe accident.

  6. Reproductive toxicity of chromium in adult bonnet monkeys (Macaca radiata Geoffrey). Reversible oxidative stress in the semen

    International Nuclear Information System (INIS)

    Subramanian, Senthivinayagam; Rajendiran, Gopalakrishnan; Sekhar, Pasupathi; Gowri, Chandrahasan; Govindarajulu, Pera; Aruldhas, Mariajoseph Michael

    2006-01-01

    The present study was designed to test the hypothesis that oxidative stress mediates chromium-induced reproductive toxicity. Monthly semen samples were collected from adult monkeys (Macaca radiata), which were exposed to varying doses (50, 100, 200 and 400 ppm) of chromium (as potassium dichromate) for 6 months through drinking water. Chromium treatment decreased sperm count, sperm forward motility and the specific activities of antioxidant enzymes, superoxide dismutase and catalase, and the concentration of reduced glutathione in both seminal plasma and sperm in a dose- and duration-dependent manner. On the other hand, the quantum of hydrogen peroxide in the seminal plasma/sperm from monkeys exposed to chromium increased with increasing dose and duration of chromium exposure. All these changes were reversed after 6 months of chromium-free exposure period. Simultaneous supplementation of vitamin C (0.5 g/L; 1.0 g/L; 2.0 g/L) prevented the development of chromium-induced oxidative stress. Data support the hypothesis and show that chronic chromium exposure induces a reversible oxidative stress in the seminal plasma and sperm by creating an imbalance between reactive oxygen species and antioxidant system, leading to sperm death and reduced motility of live sperm

  7. Internal steam reforming in solid oxide fuel cells: Status and opportunities of kinetic studies and their impact on modelling

    DEFF Research Database (Denmark)

    Mogensen, David; Grunwaldt, J.-D.; Hendriksen, Peter Vang

    2011-01-01

    Solid oxide fuel cells (SOFC) systems with internal steam reforming have the potential to become an economically competitive technology for cogeneration power plants, exploiting its significantly higher electrical efficiency compared to existing technologies. Optimal design and operation of such ......Solid oxide fuel cells (SOFC) systems with internal steam reforming have the potential to become an economically competitive technology for cogeneration power plants, exploiting its significantly higher electrical efficiency compared to existing technologies. Optimal design and operation...

  8. 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

    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) con...

  9. Effect of Co deposition on oxidation behavior and electrical properties of ferritic steel for solid oxide fuel cell interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Kruk, A.; Adamczyk, A.; Gil, A. [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Krakow (Poland); Kąc, S. [AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science, al. Mickiewicza 30, 30-059 Krakow (Poland); Dąbek, J.; Ziąbka, M. [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Krakow (Poland); Brylewski, T., E-mail: brylew@agh.edu.pl [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Krakow (Poland)

    2015-09-01

    In this work, a Co layer deposited on DIN 50049 steel by means of pulsed laser deposition was applied for the protection of solid oxide fuel cell (SOFC) interconnects operating on the cathode side. The coated and uncoated steel samples were oxidized in air at 1073 K for 500 h, and their microstructures as well as electrical resistances were evaluated using X-ray diffraction, atomic force microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and the 2-probe 4-point direct current method. It was demonstrated that the Co coating had reduced the oxidation rate of the steel by nearly a half. The area-specific resistance value of the coated steel was 5 × 10{sup −6} Ω·m{sup 2}, which was significantly lower than that of bare steel after 350 h of oxidation at 1073 K. Cr vaporization tests showed that the Co coating was efficient at blocking the outward diffusion of Cr. The obtained results prove that steel coated with a thin film of cobalt was suitable for use as metallic interconnect material in SOFCs operating at intermediate temperatures. - Highlights: • Co layer was deposited on ferritic steel by means of pulsed laser deposition. • Coated and bare ferritic steel samples were exposed to air at 1073 K for 500 h. • Scale growth rate on bare steel is higher than that on coated steel. • Electrical resistance for oxidized coated steel was lower than for bare steel. • Co-coated steel effectively reduced the formation of volatile Cr species.

  10. Comparison of iron and copper doped manganese cobalt spinel oxides as protective coatings for solid oxide fuel cell interconnects

    Science.gov (United States)

    Talic, Belma; Molin, Sebastian; Wiik, Kjell; Hendriksen, Peter Vang; Lein, Hilde Lea

    2017-12-01

    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 rate in air at 900 °C and 800 °C. At 700 °C there is no significant difference in oxidation rate between coated samples and uncoated pre-oxidized Crofer 22 APU. The cross-scale area specific resistance (ASR) is measured in air at 800 °C using La0.85Sr0.1Mn1.1O3 (LSM) contact plates to simulate the interaction with the cathode in a SOFC stack. All coated samples have three times lower ASR than uncoated Crofer 22 APU after 4370 h aging. The ASR increase with time is lowest with the MnCo2O4 coating, followed by the MnCo1.7Fe0.3O4 and MnCo1.7Cu0.3O4 coatings. LSM plates contacted to uncoated Crofer 22 APU contain significant amounts of Cr after aging, while all three coatings effectively prevent Cr diffusion into the LSM. A complex Cr-rich reaction layer develops at the coating-alloy interface during oxidation. Cu and Fe doping reduce the extent of this reaction layer at 900 °C, while at 800 °C the effect of doping is insignificant.

  11. Reverse Engineering Applied to Red Human Hair Pheomelanin Reveals Redox-Buffering as a Pro-Oxidant Mechanism

    Science.gov (United States)

    Kim, Eunkyoung; Panzella, Lucia; Micillo, Raffaella; Bentley, William E.; Napolitano, Alessandra; Payne, Gregory F.

    2015-01-01

    Pheomelanin has been implicated in the increased susceptibility to UV-induced melanoma for people with light skin and red hair. Recent studies identified a UV-independent pathway to melanoma carcinogenesis and implicated pheomelanin’s pro-oxidant properties that act through the generation of reactive oxygen species and/or the depletion of cellular antioxidants. Here, we applied an electrochemically-based reverse engineering methodology to compare the redox properties of human hair pheomelanin with model synthetic pigments and natural eumelanin. This methodology exposes the insoluble melanin samples to complex potential (voltage) inputs and measures output response characteristics to assess redox activities. The results demonstrate that both eumelanin and pheomelanin are redox-active, they can rapidly (sec-min) and repeatedly redox-cycle between oxidized and reduced states, and pheomelanin possesses a more oxidative redox potential. This study suggests that pheomelanin’s redox-based pro-oxidant activity may contribute to sustaining a chronic oxidative stress condition through a redox-buffering mechanism. PMID:26669666

  12. The gas-solid trickle-flow reactor for the catalytic oxidation of hydrogen sulphide: a trickle-phase model

    NARCIS (Netherlands)

    Verver, A.B.; van Swaaij, Willibrordus Petrus Maria

    1987-01-01

    The oxidation of H2S by O2 producing elemental sulphur has been studied at temperatures of 100–300°C and at atmospheric pressure in a laboratory-scale gas-solid trickle-flow reactor. In this reactor one of the reaction products, i.e. sulphur, is removed continuously by flowing solids. A porous,

  13. Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors

    Science.gov (United States)

    Qifeng Zheng; Zhiyong Cai; Zhenqiang Ma; Shaoqin Gong

    2015-01-01

    A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4 poly (vinyl alcohol) PVA gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors...

  14. Synthesis and characterization of novel electrolyte materials for intermediate temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    Chaubey, Nityanand; Chattopadhyaya, M.C.; Wani, B.N.; Bharadwaj, S.R.

    2008-01-01

    The high operating temperature of SOFCs using zirconia based electrolyte have several restrictions on materials used as interconnect and sealing and also requires use of expensive ceramics. Lowering the operating temperature of SOFCs to 600-800 deg C will enable to use cheaper materials and reduce the cost of fabrication while keeping the high power density. Lanthanide gallates are considered to be very promising solid electrolytes for intermediate temperature (600-800 deg C) solid oxide fuel cells (IT-SOFCs) due to their high ionic conductivity at lower temperatures. Phase purity of this material is a concern for the researchers for a long time. These materials are prepared at very high temperature (∼1400 deg C), since it is known that at around 1100 deg C, solubilities of Sr and Mg in LaGaO 3 were close to zero. Hence in the present work perovskite oxides of Ln 1-x Sr x Ga 1-y Mg y O 3-δ (Ln= Sm, Gd and x = 0.10, y=0.20) have been prepared by different methods i.e. solid state reaction, gel combustion and co-precipitation methods

  15. Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

    International Nuclear Information System (INIS)

    Zhou, Dayu; Guan, Yan; Vopson, Melvin M.; Xu, Jin; Liang, Hailong; Cao, Fei; Dong, Xianlin; Mueller, Johannes; Schenk, Tony; Schroeder, Uwe

    2015-01-01

    HfO 2 -based binary lead-free ferroelectrics show promising properties for non-volatile memory applications, providing that their polarization reversal behavior is fully understood. In this work, temperature-dependent polarization hysteresis measured over a wide applied field range has been investigated for Si-doped HfO 2 ferroelectric thin films. Our study indicates that in the low and medium electric field regimes (E < twofold coercive field, 2E c ), the reversal process is dominated by the thermal activation on domain wall motion and domain nucleation; while in the high-field regime (E > 2E c ), a non-equilibrium nucleation-limited-switching mechanism dominates the reversal process. The optimum field for ferroelectric random access memory (FeRAM) applications was determined to be around 2.0 MV/cm, which translates into a 2.0 V potential applied across the 10 nm thick films

  16. Modeling and optimization of proton-conducting solid oxide electrolysis cell: Conversion of CO2 into value-added products

    Science.gov (United States)

    Namwong, Lawit; Authayanun, Suthida; Saebea, Dang; Patcharavorachot, Yaneeporn; Arpornwichanop, Amornchai

    2016-11-01

    Proton-conducting solid oxide electrolysis cells (SOEC-H+) are a promising technology that can utilize carbon dioxide to produce syngas. In this work, a detailed electrochemical model was developed to predict the behavior of SOEC-H+ and to prove the assumption that the syngas is produced through a reversible water gas-shift (RWGS) reaction. The simulation results obtained from the model, which took into account all of the cell voltage losses (i.e., ohmic, activation, and concentration losses), were validated using experimental data to evaluate the unknown parameters. The developed model was employed to examine the structural and operational parameters. It is found that the cathode-supported SOEC-H+ is the best configuration because it requires the lowest cell potential. SOEC-H+ operated favorably at high temperatures and low pressures. Furthermore, the simulation results revealed that the optimal S/C molar ratio for syngas production, which can be used for methanol synthesis, is approximately 3.9 (at a constant temperature and pressure). The SOEC-H+ was optimized using a response surface methodology, which was used to determine the optimal operating conditions to minimize the cell potential and maximize the carbon dioxide flow rate.

  17. Facile and efficient room temperature solid state reaction enabled synthesis of antimony nanoparticles embedded within reduced graphene oxide for enhanced sodium-ion storage

    Science.gov (United States)

    Zhang, Xiukui; Wu, Ping; Jiang, Li; Zhang, Xiaofang; Shi, Hongxia; Zhu, Xiaoshu; Wei, Shaohua; Zhou, Yiming

    2018-06-01

    Herein, a very simple and cost-effective solid state reaction method is employed to obtain, for the first time, the antimony nanoparticles embedded within reduced graphene oxide matrices (designated as Sb/rGO). By directly grinding antimony chloride and sodium hydroxide together at room temperature in the presence of graphene oxide (GO), Sb4O5Cl2 precursor was quickly obtained, which is evenly incorporated in the graphene oxide matrices. After subsequent chemical reduction by NaBH4, the Sb/rGO composite was successfully synthesized. The as-prepared Sb/rGO composite consists of uniform Sb nanoparticles of sub-20 nm, all of which have been wrapped in and protected by the rGO matrices. The Sb nanoparticles serve as a sufficient sodium ion reservoir while the rGO matrices provide highly efficient pathways for transport of sodium ions and electrons. Moreover, the volume expansion of Sb during sodiation can be buffered in the rGO matrices. As a result, the Sb/rGO composite exhibits excellent electrochemical performance in sodium-ion batteries (SIBs), including an enhanced cycling stability with a highly reversible charge capacity of 455 mA h g-1 after 45 cycles at 100 mA g-1, and a coulombic efficiency exceeding 98% during cycling. The findings in the present work pave the way to not only synthesize the designated promising electrode materials for high performance SIBs, but also thoroughly understand the solid-state reaction.

  18. Oxygen optical gas sensing by reversible fluorescence quenching in photo-oxidized poly(9,9-dioctylfluorene) thin films.

    Science.gov (United States)

    Anni, M; Rella, R

    2010-02-04

    We investigated the fluorescence (FL) dependence on the environment oxygen content of poly(9,9-dioctylfluorene) (PF8) thin films. We show that the PF8 interactions with oxygen are not limited to the known irreversible photo-oxidation, resulting in the formation of Keto defects, but also reversible FL quenching is observed. This effect, which is stronger for the Keto defects than for the PF8, has been exploited for the realization of a prototype oxygen sensor based on FL quenching. The sensing sensitivity of Keto defects is comparable with the state of the art organic oxygen sensors based on phosphorescence quenching.

  19. Pore-scale investigation of mass transport and electrochemistry in a solid oxide fuel cell anode

    Energy Technology Data Exchange (ETDEWEB)

    Grew, Kyle N.; Joshi, Abhijit S.; Peracchio, Aldo A.; Chiu, Wilson K.S. [Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, Storrs, CT 06269-3139 (United States)

    2010-04-15

    The development and validation of a model for the study of pore-scale transport phenomena and electrochemistry in a Solid Oxide Fuel Cell (SOFC) anode are presented in this work. This model couples mass transport processes with a detailed reaction mechanism, which is used to model the electrochemical oxidation kinetics. Detailed electrochemical oxidation reaction kinetics, which is known to occur in the vicinity of the three-phase boundary (TPB) interfaces, is discretely considered in this work. The TPB regions connect percolating regions of electronic and ionic conducting phases of the anode, nickel (Ni) and yttria-stabilized zirconia (YSZ), respectively; with porous regions supporting mass transport of the fuel and product. A two-dimensional (2D), multi-species lattice Boltzmann method (LBM) is used to describe the diffusion process in complex pore structures that are representative of the SOFC anode. This diffusion model is discretely coupled to a kinetic electrochemical oxidation mechanism using localized flux boundary conditions. The details of the oxidation kinetics are prescribed as a function of applied activation overpotential and the localized hydrogen and water mole fractions. This development effort is aimed at understanding the effects of the anode microstructure within TPB regions. This work describes the methods used so that future studies can consider the details of SOFC anode microstructure. (author)

  20. High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

    Science.gov (United States)

    Gannon, Paul; Amendola, Roberta

    2012-12-01

    High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

  1. Persulfate Oxidation Regeneration of Granular Activated Carbon: Reversible Impacts on Sorption Behavior

    Science.gov (United States)

    Chemical oxidation regeneration of granular activated carbon (GAC) is a developing technology that can be carried out utilizing thermally-activated persulfate. During chemical regeneration of GAC, aggressive oxidative conditions lead to high acidity (pH < 2) and the accumulation ...

  2. Oxygen Reduction Kinetics Enhancement on a Heterostructured Oxide Surface for Solid Oxide Fuel Cells

    KAUST Repository

    Crumlin, Ethan J.

    2010-11-04

    Heterostructured interfaces of oxides, which can exhibit transport and reactivity characteristics remarkably different from those of bulk oxides, are interesting systems to explore in search of highly active cathodes for the oxygen reduction reaction (ORR). Here, we show that the ORR of ∼85 nm thick La0.8Sr0.2CoO3-δ (LSC113) films prepared by pulsed laser deposition on (001)-oriented yttria-stabilized zirconia (YSZ) substrates is dramatically enhanced (∼3-4 orders of magnitude above bulk LSC113) by surface decorations of (La 0.5Sr0.5)2CoO4±δ (LSC214) with coverage in the range from ∼0.1 to ∼15 nm. Their surface and atomic structures were characterized by atomic force, scanning electron, and scanning transmission electron microscopy, and the ORR kinetics were determined by electrochemical impedance spectroscopy. Although the mechanism for ORR enhancement is not yet fully understood, our results to date show that the observed ORR enhancement can be attributed to highly active interfacial LSC113/LSC214 regions, which were shown to be atomically sharp. © 2010 American Chemical Society.

  3. Oxygen Reduction Kinetics Enhancement on a Heterostructured Oxide Surface for Solid Oxide Fuel Cells

    KAUST Repository

    Crumlin, Ethan J.; Mutoro, Eva; Ahn, Sung-Jin; la O’ , Gerardo Jose; Leonard, Donovan N.; Borisevich, Albina; Biegalski, Michael D.; Christen, Hans M.; Shao-Horn, Yang

    2010-01-01

    Heterostructured interfaces of oxides, which can exhibit transport and reactivity characteristics remarkably different from those of bulk oxides, are interesting systems to explore in search of highly active cathodes for the oxygen reduction reaction (ORR). Here, we show that the ORR of ∼85 nm thick La0.8Sr0.2CoO3-δ (LSC113) films prepared by pulsed laser deposition on (001)-oriented yttria-stabilized zirconia (YSZ) substrates is dramatically enhanced (∼3-4 orders of magnitude above bulk LSC113) by surface decorations of (La 0.5Sr0.5)2CoO4±δ (LSC214) with coverage in the range from ∼0.1 to ∼15 nm. Their surface and atomic structures were characterized by atomic force, scanning electron, and scanning transmission electron microscopy, and the ORR kinetics were determined by electrochemical impedance spectroscopy. Although the mechanism for ORR enhancement is not yet fully understood, our results to date show that the observed ORR enhancement can be attributed to highly active interfacial LSC113/LSC214 regions, which were shown to be atomically sharp. © 2010 American Chemical Society.

  4. 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.

  5. Photodegradation of polycyclic aromatic hydrocarbon pyrene by iron oxide in solid phase

    International Nuclear Information System (INIS)

    Wang, Y.; Liu, C.S.; Li, F.B.; Liu, C.P.; Liang, J.B.

    2009-01-01

    To better understand the photodegradation of polycyclic aromatic hydrocarbons (PAH) in solid phase in natural environment, laboratory experiments were conducted to study the influencing factors, kinetics and intermediate compound of pyrene photodegradation by iron oxides. The results showed that the pyrene photodegradation rate followed the order of α-FeOOH > α-Fe 2 O 3 > γ-Fe 2 O 3 > γ-FeOOH at the same reaction conditions. Lower dosage of α-FeOOH and higher light intensity increased the photodegradation rate of pyrene. Iron oxides and oxalic acid can set up a photo-Fenton-like system without additional H 2 O 2 in solid phase to enhance the photodegradation of pyrene under UV irradiation. All reaction followed the first-order reaction kinetics. The half-life (t 1/2 ) of pyrene in the system showed the higher efficiencies of using iron oxide as photocatalyst to degrade pyrene. Intermediate compound pyreno was found during photodegradation reactions by gas chromatography-mass spectrometry (GC-MS). The photodegradation efficiency for PAHs in this photo-Fenton-like system was also confirmed by using the contaminated soil samples. This work provides some useful information to understand the remediation of PAHs contaminated soils by photochemical techniques under practical condition

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

    Science.gov (United States)

    Raza, Rizwan; Ahmed, Akhlaq; Akram, Nadeem; Saleem, Muhammad; Niaz Akhtar, Majid; Sherazi, Tauqir A.; Ajmal Khan, M.; Abbas, Ghazanfar; Shakir, Imran; Mohsin, Munazza; Alvi, Farah; Javed, Muhammad Sufyan; Yasir Rafique, M.; Zhu, Bin

    2015-11-01

    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-2 (oxygen ions) and H+ (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/cm2, 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.

  7. Macrophage mitochondrial damage from StAR transport of 7-hydroperoxycholesterol: implications for oxidative stress-impaired reverse cholesterol transport.

    Science.gov (United States)

    Korytowski, Witold; Wawak, Katarzyna; Pabisz, Pawel; Schmitt, Jared C; Girotti, Albert W

    2014-01-03

    StAR family proteins in vascular macrophages participate in reverse cholesterol transport (RCT). We hypothesize that under pathophysiological oxidative stress, StARs will transport not only cholesterol to macrophage mitochondria, but also pro-oxidant cholesterol hydroperoxides (7-OOHs), thereby impairing early-stage RCT. Upon stimulation with dibutyryl-cAMP, RAW264.7 macrophages exhibited a strong time-dependent induction of mitochondrial StarD1 and plasma membrane ABCA1, which exports cholesterol. 7α-OOH uptake by stimulated RAW cell mitochondria (like cholesterol uptake) was strongly reduced by StarD1 knockdown, consistent with StarD1 involvement. Upon uptake by mitochondria, 7α-OOH (but not redox-inactive 7α-OH) triggered lipid peroxidation and membrane depolarization while reducing ABCA1 upregulation. These findings provide strong initial support for our hypothesis. Copyright © 2013. Published by Elsevier B.V.

  8. Radiation oxidation of polypropylene: A solid-state 13C NMR study using selective isotopic labeling

    International Nuclear Information System (INIS)

    Mowery, Daniel M.; Assink, Roger A.; Derzon, Dora K.; Klamo, Sara B.; Bernstein, Robert; Clough, Roger L.

    2007-01-01

    Polypropylene samples, in which the three different carbon atoms along the chain were selectively labeled with carbon-13, were subjected to radiation under inert and air atmospheres, and to post-irradiation exposure in air at various temperatures. By using solid-state 13 C NMR measurements at room temperature, we have been able to identify and quantify the oxidation products. The isotopic labeling provides insight into chemical reaction mechanisms, since oxidation products can be traced back to their positions of origin on the macromolecule. The major products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of products arising from reactions at the methyl side chain. Significant temperature-dependent differences are apparent; for example much higher yields of chain-end methyl ketones, which are the indicator product of chain scission, are generated for both elevated temperature irradiation and for post-irradiation treatment at elevated temperatures. Time-dependent plots of yields of the various oxidation products have been obtained under a wide range of conditions, including the post-irradiation oxidation of a sample at room temperature in air that has been monitored for 2 years. Radiation-oxidation products of polypropylene are contrasted to products measured for 13 C-labeled polyethylene in an earlier investigation: the peroxides formed in irradiated polypropylene are remarkably longer lived, the non-peroxidic products are significantly different, and the overall ratios of oxidation products in polypropylene change relatively little as a function of the extent of oxidation

  9. Selective Aerobic Oxidation of 5-Hydroxymethylfurfural in Water Over Solid Ruthenium Hydroxide Catalysts with Magnesium-Based Supports

    DEFF Research Database (Denmark)

    Gorbanev, Yury; Kegnæs, Søren; Riisager, Anders

    2011-01-01

    Solid catalyst systems comprised of ruthenium hydroxide supported on magnesium-based carrier materials (spinel, magnesium oxide and hydrotalcite) were investigated for the selective, aqueous aerobic oxidation of the biomass-derived chemical 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid...

  10. Methods for using novel cathode and electrolyte materials for solid oxide fuel cells and ion transport membranes

    Science.gov (United States)

    Jacobson, Allan J.; Wang, Shuangyan; Kim, Gun Tae

    2016-01-12

    Methods using novel cathode, electrolyte and oxygen separation materials operating at intermediate temperatures for use in solid oxide fuel cells and ion transport membranes include oxides with perovskite related structures and an ordered arrangement of A site cations. The materials have significantly faster oxygen kinetics than in corresponding disordered perovskites.

  11. Air purification by catalytic oxidation in a reactor with periodic flow reversal

    NARCIS (Netherlands)

    van de Beld, L.; van de Beld, Bert; Westerterp, K.R.

    1994-01-01

    The behaviour of an adiabatic packed bed reactor with periodic flow reversal has been studied by means of model calculations. A heterogeneous model as well as a pseudo-homogeneous model have been developed. It is shown that a high degree of conversion can be obtained in an autothermal process even

  12. Interleukin 37 reverses the metabolic cost of inflammation, increases oxidative respiration, and improves exercise tolerance

    NARCIS (Netherlands)

    Cavalli, G.; Justice, J.N.; Boyle, K.E.; d'Alessandro, A.; Eisenmesser, E.Z.; Herrera, J.J.; Hansen, K.C.; Nemkov, T.; Stienstra, R.; Garlanda, C.; Mantovani, A.; Seals, D.R.; Dagna, L.; Joosten, L.A.B.; Ballak, D.B.; Dinarello, C.A.

    2017-01-01

    IL-1 family member interleukin 37 (IL-37) has broad antiinflammatory properties and functions as a natural suppressor of innate inflammation. In this study, we demonstrate that treatment with recombinant human IL-37 reverses the decrease in exercise performance observed during systemic inflammation.

  13. THYROID HORMONE REVERSES AGING-INDUCED MYOCARDIAL FATTY ACID OXIDATION DEFECTS AND IMPROVES THE RESPONSE TO ACUTELY INCREASED AFTERLOAD

    Energy Technology Data Exchange (ETDEWEB)

    Ledee, Dolena; Portman, Michael A.; Kajimoto, Masaki; Isern, Nancy G.; Olson, Aaron

    2013-06-07

    Background: Subclinical hypothyroidism occurs during aging in humans and mice and may contribute to development of heart failure. Aging also impairs myocardial fatty acid oxidation, causing increased reliance on flux through pyruvate dehydrogenase (PDH) to maintain function. We hypothesize that the metabolic changes in aged hearts make them less tolerant to acutely increased work and that thyroid hormone reverses these defects. Methods: Studies were performed on young (Young, 4-6 months) and aged (Old, 22-24 months) C57/BL6 mice at standard (50 mmHg) and high afterload (80 mmHg). Another aged group received thyroid hormone for 3 weeks (Old-TH, high afterload only). Function was measured in isolated working hearts along with substrate fractional contributions (Fc) to the citric acid cycle (CAC) using perfusate with 13C labeled lactate, pyruvate, glucose and unlabeled palmitate and insulin. Results: Cardiac function was similar between Young and Old mice at standard afterload. Palmitate Fc was reduced but no individual carbohydrate contributions differed. CAC and individual substrate fluxes decreased in aged. At high afterload, -dP/dT was decreased in Old versus Young. Similar to low afterload, palmitate Fc was decreased in Old. Thyroid hormone reversed aging-induced changes in palmitate Fc and flux while significantly improving cardiac function. Conclusion: The aged heart shows diminished ability to increase cardiac work due to substrate limitations, primarily impaired fatty acid oxidation. The heart accommodates slightly by increasing efficiency through oxidation of carbohydrate substrates. Thyroid hormone supplementation in aged mice significantly improves cardiac function potentially through restoration of fatty acid oxidation.

  14. The effect of interfaces on solid-state reactions between oxides

    International Nuclear Information System (INIS)

    Johnson, M.T.; Carter, C.B.

    1998-01-01

    A thin-film geometry has been used to study fundamental solid-state reaction processes occurring at interfaces in two spinel-forming oxide systems. In the first system, NiO/Al 2 O 3 , epitactic NiO films were deposited on various orientations of single-crystal α-Al 2 O 3 . In this case, the reaction kinetics were studied and correlated with the interfacial structure (or substrate orientation). In the second, In 2 O 3 /MgO, solid-state reactions were studied under the influence of an electric field. The electric field provides a driving force for mass transport that affects both the reaction process and the morphological stability of an interface

  15. Three-dimensional ionic conduction in the strained electrolytes of solid oxide fuel cells

    International Nuclear Information System (INIS)

    Han, Yupei; Zou, Minda; Lv, Weiqiang; He, Weidong; Mao, Yiwu; Wang, Wei

    2016-01-01

    Flexible power sources including fuel cells and batteries are the key to realizing flexible electronic devices with pronounced foldability. To understand the bending effects in these devices, theoretical analysis on three-dimensional (3-D) lattice bending is necessary. In this report, we derive a 3-D analytical model to analyze the effects of electrolyte crystal bending on ionic conductivity in flexible solid-state batteries/fuel cells. By employing solid oxide fuel cells as a materials' platform, the intrinsic parameters of bent electrolyte materials, including lattice constant, Young's modulus, and Poisson ratio, are evaluated. Our work facilitates the rational design of highly efficient flexible electrolytes for high-performance flexible device applications.

  16. Alternative materials for solid oxide fuel cells: Factors affecting air-sintering of chromite interconnections

    International Nuclear Information System (INIS)

    Chick, L.A.; Bates, J.L.

    1992-01-01

    The purpose of this research is to develop alternative materials for solid oxide fuel cell (SOFC) interconnections and electrodes with improved electrical, thermal and electrochemical properties. Another objective is to develop synthesis and fabrication processes for these materials whereby they can be consolidated in air into SOFC's. The approach is to (1) develop modifications of the current, state-of-the-art materials used in SOFC's, (2) minimize the number of cations used in the SOFC materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabrication and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component compositions and processing on those reactions

  17. Solid-State Electrochromic Device Consisting of Amorphous WO3 and Various Thin Oxide Layers

    Science.gov (United States)

    Shizukuishi, Makoto; Shimizu, Isamu; Inoue, Eiichi

    1980-11-01

    A mixed oxide containing Cr2O3 was introduced into an amorphous WO3 solid-state electrochromic device (ECD) in order to improve its colour memory effect. The electrochromic characteristics were greatly affected by the chemical constituents of a dielectric layer on the a-WO3 layer. Particularly, long memory effect and low power dissipation were attained in a solid-state ECD consisting of a-WO3 and Cr2O3\\cdotV2O5(50 wt.%). Some electrochromic characteristics of the a-WO3/Cr2O3\\cdotV2O5 ECD and the role of V2O5 were investigated.

  18. Trace and surface analysis of ceramic layers of solid oxide fuel cells by mass spectrometry.

    Science.gov (United States)

    Becker, J S; Breuer, U; Westheide, J; Saprykin, A I; Holzbrecher, H; Nickel, H; Dietze, H J

    1996-06-01

    For the trace analysis of impurities in thick ceramic layers of a solid oxide fuel cell (SOFC) sensitive solid-state mass spectrometric methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and radiofrequency glow discharge mass spectrometry (rf-GDMS) have been developed and used. In order to quantify the analytical results of LA-ICP-MS, the relative sensitivity coefficients of elements in a La(0.6)Sr(0.35)MnO(3) matrix have been determined using synthetic standards. Secondary ion mass spectrometry (SIMS) - as a surface analytical method - has been used to characterize the element distribution and diffusion profiles of matrix elements on the interface of a perovskite/Y-stabilized ZrO(2) layer. The application of different mass spectrometric methods for process control in the preparation of ceramic layers for the SOFC is described.

  19. A study on production of biodiesel using a novel solid oxide catalyst derived from waste.

    Science.gov (United States)

    Majhi, Samrat; Ray, Srimanta

    2016-05-01

    The issues of energy security, dwindling supply and inflating price of fossil fuel have shifted the global focus towards fuel of renewable origin. Biodiesel, having renewable origin, has exhibited great potential as substitute for fossil fuels. The most common route of biodiesel production is through transesterification of vegetable oil in presence of homogeneous acid or base or solid oxide catalyst. But, the economics of biodiesel is not competitive with respect to fossil fuel due to high cost of production. The vegetable oil waste is a potential alternative for biodiesel production, particularly when disposal of used vegetable oil has been restricted in several countries. The present study evaluates the efficacy of a low-cost solid oxide catalyst derived from eggshell (a food waste) in transesterification of vegetable oil and simulated waste vegetable oil (SWVO). The impact of thermal treatment of vegetable oil (to simulate frying operation) on transesterification using eggshell-derived solid oxide catalyst (ESSO catalyst) was also evaluated along with the effect of varying reaction parameters. The study reported that around 90 % biodiesel yield was obtained with vegetable oil at methanol/oil molar ratio of 18:1 in 3 h reaction time using 10 % ESSO catalyst. The biodiesel produced with ESSO catalyst from SWVO, thermally treated at 150 °C for 24 h, was found to conform with the biodiesel standard, but the yield was 5 % lower compared to that of the untreated oil. The utilization of waste vegetable oil along with waste eggshell as catalyst is significant for improving the overall economics of the biodiesel in the current market. The utilization of waste for societal benefit with the essence of sustainable development is the novelty of this work.

  20. DEVELOPMENT OF LOW-COST MANUFACTURING PROCESSES FOR PLANAR, MULTILAYER SOLID OXIDE FUEL CELL ELEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Scott Swartz; Matthew Seabaugh; William Dawson; Harlan Anderson; Tim Armstrong; Michael Cobb; Kirby Meacham; James Stephan; Russell Bennett; Bob Remick; Chuck Sishtla; Scott Barnett; John Lannutti

    2004-06-12

    This report summarizes the results of a four-year project, entitled, ''Low-Cost Manufacturing Of Multilayer Ceramic Fuel Cells'', jointly funded by the U.S. Department of Energy, the State of Ohio, and by project participants. The project was led by NexTech Materials, Ltd., with subcontracting support provided by University of Missouri-Rolla, Michael A. Cobb & Co., Advanced Materials Technologies, Inc., Edison Materials Technology Center, Gas Technology Institute, Northwestern University, and The Ohio State University. Oak Ridge National Laboratory, though not formally a subcontractor on the program, supported the effort with separate DOE funding. The objective of the program was to develop advanced manufacturing technologies for making solid oxide fuel cell components that are more economical and reliable for a variety of applications. The program was carried out in three phases. In the Phase I effort, several manufacturing approaches were considered and subjected to detailed assessments of manufacturability and development risk. Estimated manufacturing costs for 5-kW stacks were in the range of $139/kW to $179/kW. The risk assessment identified a number of technical issues that would need to be considered during development. Phase II development work focused on development of planar solid oxide fuel cell elements, using a number of ceramic manufacturing methods, including tape casting, colloidal-spray deposition, screen printing, spin-coating, and sintering. Several processes were successfully established for fabrication of anode-supported, thin-film electrolyte cells, with performance levels at or near the state-of-the-art. The work in Phase III involved scale-up of cell manufacturing methods, development of non-destructive evaluation methods, and comprehensive electrical and electrochemical testing of solid oxide fuel cell materials and components.

  1. Micro-Solid Oxide Fuel Cell: A multi-fuel approach for portable applications

    International Nuclear Information System (INIS)

    Patil, Tarkeshwar C.; Duttagupta, Siddhartha P.

    2016-01-01

    Highlights: • We report the oxygen ion transport properties at the electrode–electrolyte interface (EEI) of the SOFC for the first time. • This ion transport plays a key role in the overall performance of SOFCs with different fuels. • The GIIB mechanism is also studied for the first time. • GIIB is assumed to be the prime reason for low power density and ion conductivity at the EEI when using hydrocarbon fuels. • Due to its scalability, a fuel cell can serve as a power source for on-chip applications and all portable equipment. - Abstract: The impact of oxygen ion transport at the electrolyte–electrode interface of a micro-solid oxide fuel cell using different fuels is investigated. Model validation is performed to verify the results versus the reported values. Furthermore, as the hydrogen-to-carbon ratio decreases, the diffusivity of the oxygen ion increases. This increase in diffusivity is observed because the number of hydrogen atoms available as the reacting species increases in fuels with lower hydrogen-to-carbon ratios. The oxygen ion conductivity and output power density decrease as the hydrogen-to-carbon ratio of the fuels decreases. The reason behind this impact is the formation of a gas-induced ion barrier at the electrode–electrolyte interface by the CO_2 molecules formed during the reaction at the interface, thus blocking the flow of oxygen ions. As the oxygen ions become blocked, the output current contribution from the reaction also decreases and thereby affects the overall performance of the micro-solid oxide fuel cell. The experimental verification confirms this because of a significant decrease in the output power density. Furthermore, as per the application in portable devices, the appropriate choice of fuel can be chosen so that the micro-solid oxide fuel cell operates at the maximum power density.

  2. Solid-state supercapacitors with ionic liquid gel polymer electrolyte based on poly (3, 4-ethylenedioxythiophene), carbon nanotubes, and metal oxides nanocomposites for electrical energy storage

    Science.gov (United States)

    Obeidat, Amr M.

    Clean and renewable energy systems have emerged as an important area of research having diverse and significant new applications. These systems utilize different energy storage methods such as the batteries and supercapacitors. Supercapacitors are electrochemical energy storage devices that are designed to bridge the gap between batteries and conventional capacitors. Supercapacitors which store electrical energy by electrical double layer capacitance are based on large surface area structured carbons. The materials systems in which the Faradaic reversible redox reactions store electrical energy are the transition metal oxides and electronically conducting polymers. Among the different types of conducting polymers, poly (3, 4- ethylenedioxythiophene) (PEDOT) is extensively investigated owing to its chemical and mechanical stability. Due to instability of aqueous electrolytes at high voltages and toxicity of organic electrolytes, potential of supercapacitors has not been fully exploited. A novel aspect of this work is in utilizing the ionic liquid gel polymer electrolyte to design solid-state supercapacitors for energy storage. Various electrochemical systems were investigated including graphene, PEDOT, PEDOT-carbon nanotubes, PEDOT-manganese oxide, and PEDOT-iron oxide nanocomposites. The electrochemical performance of solid-state supercapacitor devices was evaluated based on cyclic voltammetry (CV), charge-discharge (CD), prolonged cyclic tests, and electrochemical impedance spectroscopy (EIS) techniques. Raman spectroscopy technique was also utilized to analyze the bonding structure of the electrode materials. The graphene solid-state supercapacitor system displayed areal capacitance density of 141.83 mF cm-2 based on high potential window up to 4V. The PEDOT solid-state supercapacitor system was synthesized in acetonitrile and aqueous mediums achieving areal capacitance density of 219.17 mF cm-2. The hybrid structure of solid-state supercapacitors was also

  3. Advanced oxidation of iodinated X-ray contrast media in reverse osmosis brines: the influence of quenching.

    Science.gov (United States)

    Azerrad, Sara P; Gur-Reznik, Shirra; Heller-Grossman, Lilly; Dosoretz, Carlos G

    2014-10-01

    Among the main restrictions for the implementation of advanced oxidation processes (AOPs) for removal of micropollutants present in reverse osmosis (RO) brines of secondary effluents account the quenching performed by background organic and inorganic constituents. Natural organic matter (NOM) and soluble microbial products (SMP) are the main effluent organic matter constituents. The inorganic fraction is largely constituted by chlorides and bicarbonate alkalinity with sodium and calcium as main counterions. The quenching influence of these components, separately and their mixture, in the transformation of model compounds by UVA/TiO2 was studied applying synthetic brines solutions mimicking 2-fold concentrated RO secondary effluents brines. The results were validated using fresh RO brines. Diatrizoate (DTZ) and iopromide (IOPr) were used as model compound. They have been found to exhibit relative high resistance to oxidation process and therefore represent good markers for AOPs techniques. Under the conditions applied, oxidization of DTZ in the background of RO brines was strongly affected by quenching effects. The major contribution to quenching resulted from organic matter (≈70%) followed by bicarbonate alkalinity (≈30%). NOM displayed higher quenching than SMP in spite of its relative lower concentration. Multivalent cations, i.e., Ca(+2), were found to decrease effectiveness of the technique due to agglomeration of the catalyst. However this influence was lowered in presence of NOM. Different patterns of transformation were found for each model compound in which a delayed deiodination was observed for iopromide whereas diatrizoate oxidation paralleled deiodination. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Solid oxide fuel cells for transportation: A clean, efficient alternative for propulsion

    International Nuclear Information System (INIS)

    Kumar, R.; Krumpelt, M.; Myles, K.M.

    1993-01-01

    Fuel cells show great promise for providing clean and efficient transportation power. Of the fuel cell propulsion systems under investigation, the solid oxide fuel cell (SOFC) is particularly attractive for heavy duty transportation applications that have a relatively long duty cycle, such as locomotives, trucks, and barges. Advantages of the SOFC include a simple, compact system configuration; inherent fuel flexibility for hydrocarbon and alternative fuels; and minimal water management. The specific advantages of the SOFC for powering a railroad locomotive are examined. Feasibility, practicality, and safety concerns regarding SOFCs in transportation applications are discussed, as am the major R ampersand D issues

  5. Thermodynamic analysis of SOFC (solid oxide fuel cell) - Stirling hybrid plants using alternative fuels

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2013-01-01

    A novel hybrid power system (∼10 kW) for an average family home is proposed. The system investigated contains a solid oxide fuel cell (SOFC) on top of a Stirling engine. The off-gases produced in the SOFC cycle are fed to a bottoming Stirling engine, at which additional power is generated...... to that of a stand-alone Stirling engine or SOFC plant. For the combined SOFC and Stirling configuration, the overall power production was increased by approximately 10% compared to that of a stand-alone SOFC plant. System efficiencies of approximately 60% are achieved, which is remarkable for such small plant sizes...

  6. Biomass gasification integrated with a solid oxide fuel cell and Stirling engine

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    An integrated gasification solid oxide fuel cell (SOFC) and Stirling engine for combined heat and power application is analyzed. The target for electricity production is 120 kW. Woodchips are used as gasification feedstock to produce syngas, which is then used to feed the SOFC stacks...... for electricity production. Unreacted hydrocarbons remaining after the SOFC are burned in a catalytic burner, and the hot off-gases from the burner are recovered in a Stirling engine for electricity and heat production. Domestic hot water is used as a heat sink for the Stirling engine. A complete balance...

  7. Real-time thermal imaging of solid oxide fuel cell cathode activity in working condition

    DEFF Research Database (Denmark)

    Montanini, Roberto; Quattrocchi, Antonino; Piccolo, Sebastiano

    2016-01-01

    Electrochemical methods such as voltammetry and electrochemical impedance spectroscopy are effective for quantifying solid oxide fuel cell (SOFC) operational performance, but not for identifying and monitoring the chemical processes that occur on the electrodes’ surface, which are thought...... to be strictly related to the SOFCs’ efficiency. Because of their high operating temperature, mechanical failure or cathode delamination is a common shortcoming of SOFCs that severely affects their reliability. Infrared thermography may provide a powerful tool for probing in situ SOFC electrode processes...... in detecting the onset of cell failure during normal operation and in monitoring cathode activity when the cell is fed with different types of fuels....

  8. Break‐down of Losses in High Performing Metal‐Supported Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Kromp, A.; Nielsen, Jimmi; Blennow Tullmar, Peter

    2013-01-01

    in the metal support, the electrochemical fuel oxidation at the anode and the oxygen reduction in the mixed ionic electronic conducting cathode. An additional process with a rather high relaxation frequency was attributed to the formation of insulating interlayers at the cathode/electrolyte‐interface. Based...... on these results, selective measures to improve performance and stability, such as (i) PVD‐deposited CGO buffer layer preventing solid state reaction between cathode and the zirconia‐based electrolyte, (ii) LSC‐CGO based in‐situ sintered cathodes and (iii) reduced corrosion of the metal support, were adopted...

  9. Solid oxide fuel cells having porous cathodes infiltrated with oxygen-reducing catalysts

    Science.gov (United States)

    Liu, Meilin; Liu, Ze; Liu, Mingfei; Nie, Lifang; Mebane, David Spencer; Wilson, Lane Curtis; Surdoval, Wayne

    2014-08-12

    Solid-oxide fuel cells include an electrolyte and an anode electrically coupled to a first surface of the electrolyte. A cathode is provided, which is electrically coupled to a second surface of the electrolyte. The cathode includes a porous backbone having a porosity in a range from about 20% to about 70%. The porous backbone contains a mixed ionic-electronic conductor (MIEC) of a first material infiltrated with an oxygen-reducing catalyst of a second material different from the first material.

  10. Thermodynamic Analysis of a Woodchips Gasification Integrated with Solid Oxide Fuel Cell and Stirling Engine

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2013-01-01

    Integrated gasification Solid Oxide Fuel Cell (SOFC) and Stirling engine for combined heat and power application is analysed. The target for electricity production is 120 kW. Woodchips are used as gasification feedstock to produce syngas which is utilized for feeding the SOFC stacks for electricity...... and suggested. Thermodynamic analysis shows that a thermal efficiency of 42.4% based on LHV (lower heating value) can be achieved. Different parameter studies are performed to analysis system behaviour under different conditions. The analysis show that increasing fuel mass flow from the design point results...

  11. Hydrogen and synthetic fuel production using pressurized solid oxide electrolysis cells

    DEFF Research Database (Denmark)

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

    2010-01-01

    Wind and solar power is troubled by large fluctuations in delivery due to changing weather. The surplus electricity can be used in a Solid Oxide Electrolyzer Cell (SOEC) to split CO2 + H2O into CO + H2 (+O2). The synthesis gas (CO + H2) can subsequently be catalyzed into various types of synthetic...... fuels using a suitable catalyst. As the catalyst operates at elevated pressure the fuel production system can be simplified by operating the SOEC at elevated pressure. Here we present the results of a cell test with pressures ranging from 0.4 bar to 10 bar. The cell was tested both as an SOEC...

  12. Performance of planar single cell lanthanum gallate based solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Maffei, N.; Kuriakose, A.K. [Materials Technology Labs., CANMET, Natural Resources Canada, Ottawa, ON (Canada)

    1998-09-01

    A novel synthesis of high purity, single phase strontium-magnesium doped lanthanum gallate through a nitrate route is described. The prepared powder is formed into planar monolithic elements by uniaxial pressing followed by isostatic pressing and sintering. XRD analysis of the sintered elements reveal no detectable secondary phases. The performance of the electrolyte in solid oxide fuel cells (SOFC) with three different anode/cathode combinations tested at 700 C with respect to the J-V and power density is reported. The data show that the characteristics of this SOFC are strongly dependent on the particular anode/cathode system chosen. (orig.)

  13. Performance of planar single cell lanthanum gallate based solid oxide fuel cells

    Science.gov (United States)

    Maffei, N.; Kuriakose, A. K.

    A novel synthesis of high purity, single phase strontium-magnesium doped lanthanum gallate through a nitrate route is described. The prepared powder is formed into planar monolithic elements by uniaxial pressing followed by isostatic pressing and sintering. XRD analysis of the sintered elements reveal no detectable secondary phases. The performance of the electrolyte in solid oxide fuel cells (SOFC) with three different anode/cathode combinations tested at 700°C with respect to the J- V and power density is reported. The data show that the characteristics of this SOFC are strongly dependent on the particular anode/cathode system chosen.

  14. Hydrogen production through high-temperature electrolysis in a solid oxide cell

    International Nuclear Information System (INIS)

    Herring, J.St.; Lessing, P.; O'Brien, J.E.; Stoots, C.; Hartvigsen, J.; Elangovan, S.

    2004-01-01

    An experimental research programme is being conducted by the INEEL and Ceramatec, Inc., to test the high-temperature, electrolytic production of hydrogen from steam using a solid oxide cell. The research team is designing and testing solid oxide cells for operation in the electrolysis mode, producing hydrogen rising a high-temperature heat and electrical energy. The high-temperature heat and the electrical power would be supplied simultaneously by a high-temperature nuclear reactor. Operation at high temperature reduces the electrical energy requirement for electrolysis and also increases the thermal efficiency of the power-generating cycle. The high-temperature electrolysis process will utilize heat from a specialized secondary loop carrying a steam/hydrogen mixture. It is expected that, through the combination of a high-temperature reactor and high-temperature electrolysis, the process will achieve an overall thermal conversion efficiency of 40 to 50%o while avoiding the challenging chemistry and corrosion issues associated with the thermochemical processes. Planar solid oxide cell technology is being utilised because it has the best potential for high efficiency due to minimized voltage and current losses. These losses also decrease with increasing temperature. Initial testing has determined the performance of single 'button' cells. Subsequent testing will investigate the performance of multiple-cell stacks operating in the electrolysis mode. Testing is being performed both at Ceramatec and at INEEL. The first cells to be tested were single cells based on existing materials and fabrication technology developed at Ceramatec for production of solid oxide fuel cells. These cells use a relatively thick (∼ 175 μm) electrolyte of yttria- or scandia-stabilised zirconia, with nickel-zirconia cermet anodes and strontium-doped lanthanum manganite cathodes. Additional custom cells with lanthanum gallate electrolyte have been developed and tested. Results to date have

  15. Thermodynamic Investigation of an Integrated Gasification Plant with Solid Oxide Fuel Cell and Steam Cycles

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2012-01-01

    A gasification plant is integrated on the top of a solid oxide fuel cell (SOFC) cycle, while a steam turbine (ST) cycle is used as a bottoming cycle for the SOFC plant. The gasification plant was fueled by woodchips to produce biogas and the SOFC stacks were fired with biogas. The produced gas...... generator (HRSG). The steam cycle was modeled with a simple single pressure level. In addition, a hybrid recuperator was used to recover more energy from the HRSG and send it back to the SOFC cycle. Thus two different configurations were investigated to study the plants characteristic. Such system...

  16. Integration of A Solid Oxide Fuel Cell into A 10 MW Gas Turbine Power Plant

    Directory of Open Access Journals (Sweden)

    Denver F. Cheddie

    2010-04-01

    Full Text Available Power generation using gas turbine power plants operating on the Brayton cycle suffers from low efficiencies. In this work, a solid oxide fuel cell (SOFC is proposed for integration into a 10 MW gas turbine power plant, operating at 30% efficiency. The SOFC system utilizes four heat exchangers for heat recovery from both the turbine outlet and the fuel cell outlet to ensure a sufficiently high SOFC temperature. The power output of the hybrid plant is 37 MW at 66.2% efficiency. A thermo-economic model predicts a payback period of less than four years, based on future projected SOFC cost estimates.

  17. Solid Oxide Cell and Stack Testing, Safety and Quality Assurance (SOCTESQA)

    DEFF Research Database (Denmark)

    Auer, C.; Lang, M.; Couturier, K.

    2015-01-01

    The market penetration of fuel and electrolysis cell energy systems in Europe requires the development of reliable assessment, testing and prediction of performance and durability of solid oxide cells and stacks (SOC). To advance in this field the EU-project “SOCTESQA” was launched in May 2014...... and dynamic operating conditions. The application specific test programs are created by combining several of these test modules. In a next step defined test modules will be applied for the initial test bench validation, which will be improved by several validation loops. The final test protocols...

  18. 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...

  19. Solid oxide cell R&D at Riso National Laboratory-and its transfer to technology

    DEFF Research Database (Denmark)

    Linderoth, Søren

    2009-01-01

    Risø National Laboratory has conducted R&D on solid oxide cells for almost 20 years—all the time together with industries with interest in deploying the technology when mature. Risø National Laboratory (Risø) and Topsoe Fuel Cell A/S (TOFC) have for several years jointly carried out a development...... programme focusing on low cost manufacturing of flat planar anode-supported cells and stacks employing metallic interconnects. The consortium of Risø and TOFC has up-scaled its production capacity of anode-supported cells to about 1,100 per week. New generations of SOFCs are being developed...

  20. Analysis of Gas Leakage and Current Loss of Solid Oxide Fuel Cells by Screen Printing

    DEFF Research Database (Denmark)

    Jia, Chuan; Han, Minfang; Chen, Ming

    2017-01-01

    Two types of anode supported solid oxide fuel cell (SOFC) NiO-YSZ/YSZ/GDC/LSCF with the same structure and different manufacturing process were tested. Gas leakage was suspected for cells manufactured with screen printing technique. Effective leak current densities for both types of cells were...... calculated. Their performances of electrochemical impedance spectroscopy (EIS) were compared and distribution function of relaxation times (DRT) technique was also used to find the clue of gas leakage. Finally, thinning and penetrating holes were observed in electrolyte layer, which confirmed the occurrence...

  1. Study of Seal Glass for Solid Oxide Fuel/Electrolyzer Cells

    OpenAIRE

    Mahapatra, Manoj Kumar

    2009-01-01

    Seal glass is essential and plays a crucial role in solid oxide fuel/electrolyzer cell performance and durability. A seal glass should have a combination of thermal, chemical, mechanical, and electrical properties in order to seal different cell components and stacks and prevent gas leakage. All the desired properties can simultaneously be obtained in a seal glass by suitable compositional design. In this dissertation, SrO-La₂O₃-A₂O₃-B₂O₃3-SiO₂ based seal glasses have been developed and compo...

  2. Sensing sulfur oxides and other sulfur bearing pollutants with solid electrolyte pellets. I. Gas concentration cells

    Energy Technology Data Exchange (ETDEWEB)

    Chamberland, A M; Gauthier, J M

    1977-01-01

    A new sensing technique using a solid electrolyte has been demonstrated for sulfur-bearing pollutants. Based on potentiometric measurements across a pellet of potassium sulfate, this sensor allows concentrations of sulfur dioxides, sulfur trioxide, hydrogen sulfide, methyl mercaptan and carbonyl sulfide in air to be measured with accuracy. Its operational concentration range at the present time is 0.1 ppM up to at least 10,000 ppM. The presence of other common pollutants such as carbon dioxide, methane, nitric oxide and nitrogen dioxide does not interfere with the measurement of air samples containing sulfur-bearing pollutants.

  3. Fuzzy Logic Based Controller for a Grid-Connected Solid Oxide Fuel Cell Power Plant.

    Science.gov (United States)

    Chatterjee, Kalyan; Shankar, Ravi; Kumar, Amit

    2014-10-01

    This paper describes a mathematical model of a solid oxide fuel cell (SOFC) power plant integrated in a multimachine power system. The utilization factor of a fuel stack maintains steady state by tuning the fuel valve in the fuel processor at a rate proportional to a current drawn from the fuel stack. A suitable fuzzy logic control is used for the overall system, its objective being controlling the current drawn by the power conditioning unit and meet a desirable output power demand. The proposed control scheme is verified through computer simulations.

  4. Morphology Control of the Electrode for Solid Oxide Fuel Cells by Using Nanoparticles

    International Nuclear Information System (INIS)

    Fukui, Takehisa; Ohara, Satoshi; Naito, Makio; Nogi, Kiyoshi

    2001-01-01

    LSM(La(Sr)MnO 3 )/YSZ(Y 2 O 3 stabilized ZrO 2 ) composite cathode for Solid Oxide Fuel Cells (SOFCs) was fabricated by using the composite particle consisting of well-dispersed nano-size grains of LSM and YSZ. The composite cathode had a porous structure as well as uniformly dispersed fine LSM and YSZ grains. Such unique morphology of the composite cathode led high electrochemical activity at 800 deg. C. It suggests that the intermediate temperature (less than 800 o C) operation of SOFCs will be achieved by using composite particles

  5. Nonlinear Model Predictive Control for Solid Oxide Fuel Cell System Based On Wiener Model

    OpenAIRE

    T. H. Lee; J. H. Park; S. M. Lee; S. C. Lee

    2010-01-01

    In this paper, we consider Wiener nonlinear model for solid oxide fuel cell (SOFC). The Wiener model of the SOFC consists of a linear dynamic block and a static output non-linearity followed by the block, in which linear part is approximated by state-space model and the nonlinear part is identified by a polynomial form. To control the SOFC system, we have to consider various view points such as operating conditions, another constraint conditions, change of load current and so on. A change of ...

  6. Feed-forward control of a solid oxide fuel cell system with anode offgas recycle

    Science.gov (United States)

    Carré, Maxime; Brandenburger, Ralf; Friede, Wolfgang; Lapicque, François; Limbeck, Uwe; da Silva, Pedro

    2015-05-01

    In this work a combined heat and power unit (CHP unit) based on the solid oxide fuel cell (SOFC) technology is analysed. This unit has a special feature: the anode offgas is partially recycled to the anode inlet. Thus it is possible to increase the electrical efficiency and the system can be operated without external water feeding. A feed-forward control concept which allows secure operating conditions of the CHP unit as well as a maximization of its electrical efficiency is introduced and validated experimentally. The control algorithm requires a limited number of measurement values and few deterministic relations for its description.

  7. Addressing fuel recycling in solid oxide fuel cell systems fed by alternative fuels

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2017-01-01

    An innovative study on anode recirculation in solid oxide fuel cell systems with alternative fuels is carried out and investigated. Alternative fuels under study are ammonia, pure hydrogen, methanol, ethanol, DME and biogas from biomass gasification. It is shown that the amount of anode off......%. Furthermore, it is founded that for the case with methanol, ethanol and DME then at high utilization factors, low anode recirculation is recommended while at low utilization factors, high anode recirculation is recommended. If the plant is fed by biogas from biomass gasification then for each utilization...

  8. Oxides with polyatomic anions considered as new electrolyte materials for solid oxide fuel cells (SOFCs)

    Energy Technology Data Exchange (ETDEWEB)

    Bin Hassan, Oskar Hasdinor

    2010-10-21

    Materials with Polyatomic anions of [Al{sub 2}O{sub 7}]{sup -8}, [Ti{sub 2}O{sub 8}]{sup -8} and [P{sub 2}O{sub 7}]{sup -4} were investigated with respect to their ionic conductivity properties as well as its thermal expansion properties with the aim to use them as SOFCs electrolytes. The polyatomic anion groups selected from the oxy-cuspidine family of Gd{sub 4}Al{sub 2}O{sub 9} and Gd{sub 4}Ti{sub 2}O{sub 10} as well as from pyrophosphate SnP{sub 2}O{sub 7}. The pure oxy-cuspidine Gd{sub 4}Al{sub 2}O{sub 9}, the series of Gd{sub 4}Al{sub 2-x}Mg{sub x}O{sub 9-x/2} with x=0.10-1.0 and Gd{sub 4-x}M{sub x}Al{sub 2}O{sub 9-x/2} (M=Ca, Sr) with x = 0.05-0.5 were prepared successfully by the citrate complexation method. All samples showed the crystal structure of monoclinic oxycuspidine structure with space group of P2{sub 1/c} and Z=4. No solid solution was observed for Gd{sub 4}Al{sub 2-x}Mg{sub x}O{sub 9-x/2} where additional phases of Gd{sub 2}O{sub 3} and MgO were presence. XRD semiquantitative analysis together with SEM-EDX analysis revealed that Mg{sup 2+} was not able to substitute the Al{sup 3+} ions even at low Mg{sup 2+} concentration. The solid solution limit of Gd{sub 4-x}Ca{sub x}Al{sub 2}O{sub 9-x/2} and Gd{sub 4-x}Sr{sub x}Al{sub 2}O{sub 9-x/2} was determined between 0.05-0.10 and 0.01-0.05 mol for Ca and Sr, respectively. Beyond the substitution limit Gd{sub 4}Al{sub 2}O{sub 9}, GdAlO{sub 3} and SrGd{sub 2}Al{sub 2}O{sub 7} appeared as additional phases. The highest electrical conductivity obtained at 900 C yielded {sigma}= 1.49 x 10{sup -4}Scm{sup -1} for Gd{sub 3.95}Ca{sub 0.05}Al{sub 2}O{sub 8.98}. In comparison, the conductivity of pure Gd{sub 4}Al{sub 2}O{sub 9} was {sigma}= 1.73 x 10{sup -5} Scm{sup -1}. The conductivities determined were in a similar range as those of other cuspidine materials investigated previously. The thermal expansion coefficient of Gd{sub 4}Al{sub 2}O{sub 9} at 1000 C was 7.4 x 10{sup -6}K{sup -1}. The earlier reported

  9. Oxidation rates of carbon and nitrogen in char residues from solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Karlstroem, O.

    2013-06-01

    Computational fluid dynamics (CFD) modeling is an important tool in designing new combustion systems. By using CFD modeling, entire combustion systems can be modeled and the emissions and the performance can be predicted. CFD modeling can also be used to develop new and better combustion systems from an economical and environmental point of view. In CFD modeling of solid fuel combustion, the combustible fuel is generally treated as single fuel particles. One of the limitations with the CFD modeling concerns the sub-models describing the combustion of single fuel particles. Available models in the scientific literature are in many cases not suitable as submodels for CFD modeling since they depend on a large number of input parameters and are computationally heavy. In this thesis CFD-applicable models are developed for the combustion of single fuel particles. The single particle models can be used to improve the combustion performance in various combustion devices or develop completely new technologies. The investigated fields are oxidation of carbon (C) and nitrogen (N) in char residues from solid fuels. Modeled char-C oxidation rates are compared to experimental oxidation rates for a large number of pulverized solid fuel chars under relevant combustion conditions. The experiments have been performed in an isothermal plug flow reactor operating at 1123-1673 K and 3-15 vol.% O{sub 2}. In the single particle model, the char oxidation is based on apparent kinetics and depends on three fuel specific parameters: apparent pre-exponential factor, apparent activation energy, and apparent reaction order. The single particle model can be incorporated as a sub-model into a CFD code. The results show that the modeled char oxidation rates are in good agreement with experimental char oxidation rates up to around 70% of burnout. Moreover, the results show that the activation energy and the reaction order can be assumed to be constant for a large number of bituminous coal chars

  10. Microstructural and electrical characterization of Mn-Co spinel protective coatings for solid oxide cell interconnects

    DEFF Research Database (Denmark)

    Molin, S.; Sabato, A. G.; Bindi, M.

    2017-01-01

    Electrophoretic deposition, thermal co-evaporation and RF magnetron sputtering methods are used for the preparation of Mn-Co based ceramic coatings for solid oxide fuel cell steel interconnects. Both thin and relatively thick coatings (1–15 μm) are prepared and characterised for their potential...... protective behaviour. Mn-Co coated Crofer22APU samples are electrically tested for 5000 h at 800 °C under a 500 mA cm−2 current load to determine their Area Specific Resistance increase due to a growing chromia scale. After tests, samples are analysed by scanning and transmission electron microscopy....... Analysis is focused on the potential chromium diffusion to or through the coating, the oxide scale thickness and possible reactions at the interfaces. The relationships between the coating type, thickness and effectiveness are reviewed and discussed. Out of the three Mn-Co coatings compared in this study...

  11. Short-stack modeling of degradation in solid oxide fuel cells. Part I. Contact degradation

    Energy Technology Data Exchange (ETDEWEB)

    Gazzarri, J.I. [Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, ON M5S 3G8 (Canada)

    2008-01-21

    As the first part of a two paper series, we present a two-dimensional impedance model of a working solid oxide fuel cell (SOFC) to study the effect of contact degradation on the impedance spectrum for the purpose of non-invasive diagnosis. The two dimensional modeled geometry includes the ribbed interconnect, and is adequate to represent co- and counter-flow configurations. Simulated degradation modes include: cathode delamination, interconnect oxidation, and interconnect-cathode detachment. The simulations show differences in the way each degradation mode impacts the impedance spectrum shape, suggesting that identification is possible. In Part II, we present a sensitivity analysis of the results to input parameter variability that reveals strengths and limitations of the method, as well as describing possible interactions between input parameters and concurrent degradation modes. (author)

  12. Short-stack modeling of degradation in solid oxide fuel cells. Part I. Contact degradation

    Science.gov (United States)

    Gazzarri, J. I.; Kesler, O.

    As the first part of a two paper series, we present a two-dimensional impedance model of a working solid oxide fuel cell (SOFC) to study the effect of contact degradation on the impedance spectrum for the purpose of non-invasive diagnosis. The two dimensional modeled geometry includes the ribbed interconnect, and is adequate to represent co- and counter-flow configurations. Simulated degradation modes include: cathode delamination, interconnect oxidation, and interconnect-cathode detachment. The simulations show differences in the way each degradation mode impacts the impedance spectrum shape, suggesting that identification is possible. In Part II, we present a sensitivity analysis of the results to input parameter variability that reveals strengths and limitations of the method, as well as describing possible interactions between input parameters and concurrent degradation modes.

  13. Molybdate Based Ceramic Negative-Electrode Materials for Solid Oxide Cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Reddy Sudireddy, Bhaskar; Mogensen, Mogens Bjerg

    2010-01-01

    Novel molybdate materials with varying Mo valence were synthesized as possible negative-electrode materials for solid oxide cells. The phase, stability, microstructure and electrical conductivity were characterized. The electrochemical activity for H2O and CO2 reduction and H2 and CO oxidation...... enhanced the electrocatalytic activity and electronic conductivity. The polarization resistances of the best molybdates were two orders of magnitude lower than that of donor-doped strontium titanates. Many of the molybdate materials were significantly activated by cathodic polarization, and they exhibited...... higher performance for cathodic (electrolysis) polarization than for anodic (fuel cell) polarization, which makes them especially interesting for use in electrolysis electrodes. ©2010 COPYRIGHT ECS - The Electrochemical Society...

  14. Performance of a novel type of electrolyte-supported solid oxide fuel cell with honeycomb structure

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Morales, Juan Carlos; Savvin, Stanislav N.; Nunez, Pedro [Departmento de Quimica Inorganica, Universidad de La Laguna, 38200 Tenerife (Spain); Marrero-Lopez, David [Departamento de Fisica Aplicada I, Universidad de Malaga, 29071 Malaga (Spain); Pena-Martinez, Juan; Canales-Vazquez, Jesus [Instituto de Energias Renovables-Universidad de Castilla la Mancha, 02006 Albacete (Spain); Roa, Joan Josep; Segarra, Merce [DIOPMA, Departamento de Ciencia de los Materiales e Ing. Metalurgica, 08028 Barcelona (Spain)

    2010-01-15

    A novel design, alternative to the conventional electrolyte-supported solid oxide fuel cell (SOFC) is presented. In this new design, a honeycomb-electrolyte is fabricated from hexagonal cells, providing high mechanical strength to the whole structure and supporting the thin layer used as electrolyte of a SOFC. This new design allows a reduction of {proportional_to}70% of the electrolyte material and it renders modest performances over 320 mW cm{sup -2} but high volumetric power densities, i.e. 1.22 W cm{sup -3} under pure CH{sub 4} at 900 C, with a high OCV of 1.13 V, using the standard Ni-YSZ cermet as anode, Pt as cathode material and air as the oxidant gas. (author)

  15. Development of a solid oxide fuel cell (SOFC) automotive auxiliary power unit (APU) fueled by gasoline

    International Nuclear Information System (INIS)

    DeMinco, C.; Mukerjee, S.; Grieve, J.; Faville, M.; Noetzel, J.; Perry, M.; Horvath, A.; Prediger, D.; Pastula, M.; Boersma, R.; Ghosh, D.

    2000-01-01

    This paper describes the design and the development progress of a 3 to 5 auxiliary power unit (APU) based on a gasoline fueled solid oxide fuel cell (SOFC). This fuel cell was supplied reformate gas (reactant) by a partial oxidation (POx) catalytic reformer utilizing liquid gasoline and designed by Delphi Automotive Systems. This reformate gas consists mainly of hydrogen, carbon monoxide and nitrogen and was fed directly in to the SOFC stack without any additional fuel reformer processing. The SOFC stack was developed by Global Thermoelectric and operates around 700 o C. This automotive APU produces power to support future 42 volt vehicle electrical architectures and loads. The balance of the APU, designed by Delphi Automotive Systems, employs a packaging and insulation design to facilitate installation and operation on-board automobiles. (author)

  16. Anode protection system for shutdown of solid oxide fuel cell system

    Science.gov (United States)

    Li, Bob X; Grieves, Malcolm J; Kelly, Sean M

    2014-12-30

    An Anode Protection Systems for a SOFC system, having a Reductant Supply and safety subsystem, a SOFC anode protection subsystem, and a Post Combustion and slip stream control subsystem. The Reductant Supply and safety subsystem includes means for generating a reducing gas or vapor to prevent re-oxidation of the Ni in the anode layer during the course of shut down of the SOFC stack. The underlying ammonia or hydrogen based material used to generate a reducing gas or vapor to prevent the re-oxidation of the Ni can be in either a solid or liquid stored inside a portable container. The SOFC anode protection subsystem provides an internal pressure of 0.2 to 10 kPa to prevent air from entering into the SOFC system. The Post Combustion and slip stream control subsystem provides a catalyst converter configured to treat any residual reducing gas in the slip stream gas exiting from SOFC stack.

  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

    % 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......-treated fuel then enters the anode side of the SOFC. Complete fuel oxidation is ensured in a burner by off-gases exiting the SOFC stacks. Off-gases are utilized as heat source for a SKC where a mixture of ammonia and water is expanded in a turbine to produce additional electric power. Thus, a triple novel......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...

  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. Thermodynamic analysis of an integrated solid oxide fuel cell cycle with a rankine cycle

    International Nuclear Information System (INIS)

    Rokni, Masoud

    2010-01-01

    Hybrid systems consisting of solid oxide fuel cells (SOFC) on the top of a steam turbine (ST) are investigated. The plants are fired by natural gas (NG). A desulfurization reactor removes the sulfur content in the fuel while a pre-reformer breaks down the heavier hydro-carbons. The pre-treated fuel enters then into the anode side of the SOFC. The remaining fuels after the SOFC stacks enter a burner for further burning. The off-gases are then used to produce steam for a Rankine cycle in a heat recovery steam generator (HRSG). Different system setups are suggested. Cyclic efficiencies up to 67% are achieved which is considerably higher than the conventional combined cycles (CC). Both adiabatic steam reformer (ASR) and catalytic partial oxidation (CPO) fuel pre-reformer reactors are considered in this investigation.

  20. System modeling of an air-independent solid oxide fuel cell system for unmanned undersea vehicles

    Science.gov (United States)

    Burke, A. Alan; Carreiro, Louis G.

    To examine the feasibility of a solid oxide fuel cell (SOFC)-powered unmanned undersea vehicle (UUV), a system level analysis is presented that projects a possible integration of the SOFC stack, fuel steam reformer, fuel/oxidant storage and balance of plant components into a 21-in. diameter UUV platform. Heavy hydrocarbon fuel (dodecane) and liquid oxygen (LOX) are chosen as the preferred reactants. A maximum efficiency of 45% based on the lower heating value of dodecane was calculated for a system that provides 2.5 kW for 40 h. Heat sources and sinks have been coupled to show viable means of thermal management. The critical design issues involve proper recycling of exhaust steam from the fuel cell back into the reformer and effective use of the SOFC stack radiant heat for steam reformation of the hydrocarbon fuel.

  1. 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...... in the viscous creep regime. The influence of oxide scale formation on creep behaviour of the porous MS was assessed by comparing the creep data of pre-oxidised samples tested in reducing atmosphere....

  2. Functional integrity of flexible n-channel metal-oxide-semiconductor field-effect transistors on a reversibly bistable platform

    Science.gov (United States)

    Alfaraj, Nasir; Hussain, Aftab M.; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Rojas, Jhonathan P.; Aljedaani, Abdulrahman B.; Hussain, Muhammad M.

    2015-10-01

    Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal-oxide-semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties.

  3. The SNO/SOH TMT strategy for combinatorial analysis of reversible cysteine oxidations

    DEFF Research Database (Denmark)

    Wojdyla, Katarzyna; Williamson, James; Roepstorff, Peter

    2015-01-01

    UNLABELLED: Redox homeostasis is essential for normal function of cells and redox imbalance has been recognised as a pathogenic factor of numerous human diseases. Oxidative modifications of cysteine thiols modulate function of many proteins, mediate signalling, and fine-tune transcriptional...... on commercially available reagents. The method has proven precise and sensitive enough to detect and quantify endogenous levels of oxidative stress on proteome-wide scale....

  4. Silver Nanowire Embedded Colorless Polyimide Heater for Wearable Chemical Sensors: Improved Reversible Reaction Kinetics of Optically Reduced Graphene Oxide.

    Science.gov (United States)

    Choi, Seon-Jin; Kim, Sang-Joon; Jang, Ji-Soo; Lee, Ji-Hyun; Kim, Il-Doo

    2016-09-14

    Optically reduced graphene oxide (ORGO) sheets are successfully integrated on silver nanowire (Ag NW)-embedded transparent and flexible substrate. As a heating element, Ag NWs are embedded in a colorless polyimide (CPI) film by covering Ag NW networks using polyamic acid and subsequent imidization. Graphene oxide dispersed aqueous solution is drop-coated on the Ag NW-embedded CPI (Ag NW-CPI) film and directly irradiated by intense pulsed light to obtain ORGO sheets. The heat generation property of Ag NW-CPI film is investigated by applying DC voltage, which demonstrates unprecedentedly reliable and stable characteristics even in dynamic bending condition. To demonstrate the potential application in wearable chemical sensors, NO 2 sensing characteristic of ORGO is investigated with respect to the different heating temperature (22.7-71.7 °C) of Ag NW-CPI film. The result reveals that the ORGO sheets exhibit high sensitivity of 2.69% with reversible response/recovery sensing properties and minimal deviation of baseline resistance of around 1% toward NO 2 molecules when the temperature of Ag NW-CPI film is 71.7 °C. This work first demonstrates the improved reversible NO 2 sensing properties of ORGO sheets on flexible and transparent Ag NW-CPI film assisted by Ag NW heating networks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. [Separation of p-aminobenzenearsonic acid and its oxide by ion-pair reversed-phase high performance liquid chromatography].

    Science.gov (United States)

    Kang, J; Ma, X; Meng, L; Ma, D

    1999-05-01

    To study the separation of p-aminobenzenearsonic acid (PABAA) and its oxide, p-aminophenylarsine oxide (PAPAO), both the absorption spectra were scanned at the wavelengths from 200 nm to 380 nm. PABAA had absorption maximum at 254 nm and PAPAO 258 nm. The effects of salt concentration, column temperature, methanol and ion-pair agent concentrations on the capacity factor were investigated. Compounds of high polarity showed almost no retention on reversed-phase column; as the volume fraction of the methanol decreased from 90% to 10%, the retention time of PABAA gradually increased with broad peak, and partially eluted when methanol volume fraction being below 20%. With temperature rising, the retention time of PABAA was decreased. But PABAA capacity factor can be increased by selecting an appropriate salt concentration for the mobile phase. The cetyltrimethyl and tetrabutyl ammonium ions were separately added as ion-pair agents to the mobile phase containing methanol in phosphate buffer of 10 mmol/L, the changes of retention time were observed. The mechanism of retention based on reversed phase ion-pair model is proposed. Besides, the retention behaviour is also influenced by size exclusion in stationary phase as well as polar interactions with residual silanol group on the silica surface.

  6. 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

  7. Does the conductivity of interconnect coatings matter for solid oxide fuel cell applications?

    Science.gov (United States)

    Goebel, Claudia; Fefekos, Alexander G.; Svensson, Jan-Erik; Froitzheim, Jan

    2018-04-01

    The present work aims to quantify the influence of typical interconnect coatings used for solid oxide fuel cells (SOFC) on area specific resistance (ASR). To quantify the effect of the coating, the dependency of coating thickness on the ASR is examined on Crofer 22 APU at 600 °C. Three different Co coating thicknesses are investigated, 600 nm, 1500 nm, and 3000 nm. Except for the reference samples, the material is pre-oxidized prior to coating to mitigate the outward diffusion of iron and consequent formation of poorly conducting (Co,Fe)3O4 spinel. Exposures are carried out at 600 °C in stagnant laboratory air for 500 h and subsequent ASR measurements are performed. Additionally the microstructure is investigated with scanning electron microscopy (SEM). On all pre-oxidized samples, a homogenous dense Co3O4 top layer is observed beneath which a thin layer of Cr2O3 is present. As the ASR values range between 7 and 12 mΩcm2 for all pre-oxidized samples, even though different Co3O4 thicknesses are observed, the results strongly suggest that for most applicable cases the impact of the coating on ASR is negligible and the main contributor is Cr2O3.

  8. Nitric-phosphoric acid oxidation of solid and liquid organic materials

    International Nuclear Information System (INIS)

    Pierce, R.A.; Smith, J.R.; Poprik, D.C.

    1995-01-01

    Nitric-phosphoric acid oxidation has been developed specifically to address issues that face the Savannah River Site, other defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate SRS solid, Pu-contaminated job-control waste, the technology has also exhibited potential for remediating hazardous and mixed-hazardous waste forms. The process is unique to Savannah River and offers a valuable alternative to other oxidation processes that require extreme temperatures and/or elevated pressures. To address the broad categories of waste, many different organic compounds which represent a cross-section of the waste that must be treated have been successfully oxidized. Materials that have been quantitatively oxidized at atmospheric pressure below 180 degrees C include neoprene, cellulose, EDTA, tributylphosphate, and nitromethane. More stable compounds such as benzoic acid, polyethylene, oils, and resins have been completely decomposed below 200 degrees C and 10 psig. The process uses dilute nitric acid in a concentrated phosphoric acid media as the main oxidant for the organic compounds. Phosphoric acid allow nitric acid to be retained in solution well above its normal boiling point. The reaction forms NOx vapors which can be reoxidized and recycled using air and water. The addition of 0.001M Pd(II) reduces CO generation to near 1% of the released carbon gases. The advantages of this process are that it is straightforward, uses relatively inexpensive reagents, operates at relatively low temperature and pressure, and produces final solutions which are compatible with stainless steel equipment. For organic wastes, all carbon, hydrogen, and nitrogen are converted to gaseous products. If interfaced with an acid recovery system which converts NOx back to nitric acid, the net oxidizer would be oxygen from air

  9. Shape and size transformation of gold nanorods (GNRs) via oxidation process: A reverse growth mechanism

    International Nuclear Information System (INIS)

    Chandrasekar, Govindasamy; Mougin, Karine; Haidara, Hamidou; Vidal, Loic; Gnecco, Enrico

    2011-01-01

    The anisotropic shape transformation of gold nanorods (GNRs) with H 2 O 2 was observed in the presence of 'cethyl trimethylammonium bromide' (CTAB). The adequate oxidative dissolution of GNR is provided by the following autocatalytic scheme with H 2 O 2 : Au 0 → Au + , Au 0 + Au n+ → 2Au 3+ , n = 1 and 3. The shape transformation of the GNRs was investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). As-synthesised GNRs exhibit transverse plasmon band (TPB) at 523 nm and longitudinal plasmon band (LPB) at 731 nm. Upon H 2 O 2 oxidation, the LPB showed a systematic hypsochromic (blue) shift, while TPB stays at ca. 523 nm. In addition, a new emerging peak observed at ca. 390 nm due to Au(III)-CTAB complex formation during the oxidation. TEM analysis of as-synthesised GNRs with H 2 O 2 confirmed the shape transformation to spherical particles with 10 nm size in 2 h, whereas centrifuged nanorod solution showed no changes in the aspect ratio under the same condition. Au 3+ ions produced from oxidation, complex with excess free CTAB and approach the nanorods preferentially at the end, leading to spatially directed oxidation. This work provides some information to the crystal stability and the growth mechanism of GNRs, as both growth and shortening reactions occur preferentially at the edge of single-crystalline GNRs, all directed by Br - ions.

  10. Energy-Efficient and Environmentally Friendly Solid Oxide Membrane Electrolysis Process for Magnesium Oxide Reduction: Experiment and Modeling

    Science.gov (United States)

    Guan, Xiaofei; Pal, Uday B.; Powell, Adam C.

    2014-06-01

    This paper reports a solid oxide membrane (SOM) electrolysis experiment using an LSM(La0.8Sr0.2MnO3-δ)-Inconel inert anode current collector for production of magnesium and oxygen directly from magnesium oxide at 1423 K (1150 °C). The electrochemical performance of the SOM cell was evaluated by means of various electrochemical techniques including electrochemical impedance spectroscopy, potentiodynamic scan, and electrolysis. Electronic transference numbers of the flux were measured to assess the magnesium dissolution in the flux during SOM electrolysis. The effects of magnesium solubility in the flux on the current efficiency and the SOM stability during electrolysis are discussed. An inverse correlation between the electronic transference number of the flux and the current efficiency of the SOM electrolysis was observed. Based on the experimental results, a new equivalent circuit of the SOM electrolysis process is presented. A general electrochemical polarization model of SOM process for magnesium and oxygen gas production is developed, and the maximum allowable applied potential to avoid zirconia dissociation is calculated as well. The modeling results suggest that a high electronic resistance of the flux and a relatively low electronic resistance of SOM are required to achieve membrane stability, high current efficiency, and high production rates of magnesium and oxygen.

  11. 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.

  12. 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

  13. TAPE CALENDERING MANUFACTURING PROCESS FOR MULTILAYER THIN-FILM SOLID OXIDE FUEL CELLS

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Minh; Kurt Montgomery

    2004-10-01

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC during the Phases I and II under Contract DE-AC26-00NT40705 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Tape Calendering Manufacturing Process For Multilayer Thin-Film Solid Oxide Fuel Cells''. The main objective of this project was to develop the manufacturing process based on tape calendering for multilayer solid oxide fuel cells (SOFC's) using the unitized cell design concept and to demonstrate cell performance under specified operating conditions. Summarized in this report is the development and improvements to multilayer SOFC cells and the unitized cell design. Improvements to the multilayer SOFC cell were made in electrochemical performance, in both the anode and cathode, with cells demonstrating power densities of nearly 0.9 W/cm{sup 2} for 650 C operation and other cell configurations showing greater than 1.0 W/cm{sup 2} at 75% fuel utilization and 800 C. The unitized cell design was matured through design, analysis and development testing to a point that cell operation at greater than 70% fuel utilization was demonstrated at 800 C. The manufacturing process for both the multilayer cell and unitized cell design were assessed and refined, process maps were developed, forming approaches explored, and nondestructive evaluation (NDE) techniques examined.

  14. Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Li Shuai; Li Zhicheng; Bergman, Bill

    2010-01-01

    The composite of doped lanthanum gallate (La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 , LSGM) and doped ceria (Ce 0.8 Sm 0.2 O 1.9 , CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO 2 phase and a minority impurity phase, Sm 3 Ga 5 O 12 . The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 o C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.

  15. Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li Shuai, E-mail: shuail@kth.s [Department of Materials Science and Engineering, School of Industrial Engineering and Management, Royal Institute of Technology, SE 10044 Stockholm (Sweden); Li Zhicheng [School of Materials Science and Engineering, Central South University, 410083 Changsha, Hunan (China); Bergman, Bill [Department of Materials Science and Engineering, School of Industrial Engineering and Management, Royal Institute of Technology, SE 10044 Stockholm (Sweden)

    2010-03-04

    The composite of doped lanthanum gallate (La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85}, LSGM) and doped ceria (Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9}, CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO{sub 2} phase and a minority impurity phase, Sm{sub 3}Ga{sub 5}O{sub 12}. The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 {sup o}C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  17. High pressure operation of tubular solid oxide fuel cells and their intergration with gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Haynes, C.; Wepfer, W.J. [Georgia Institute of Technology, Atlanta, GA (United States)

    1996-12-31

    Fossil fuels continue to be used at a rate greater than that of their natural formation, and the current byproducts from their use are believed to have a detrimental effect on the environment (e.g. global warming). There is thus a significant impetus to have cleaner, more efficient fuel consumption alternatives. Recent progress has led to renewed vigor in the development of fuel cell technology, which has been shown to be capable of producing high efficiencies with relatively benign exhaust products. The tubular solid oxide fuel cell developed by Westinghouse Electric Corporation has shown significant promise. Modeling efforts have been and are underway to optimize and better understand this fuel cell technology. Thus far, the bulk of modeling efforts has been for operation at atmospheric pressure. There is now interest in developing high-efficiency integrated gas turbine/solid oxide fuel cell systems. Such operation of fuel cells would obviously occur at higher pressures. The fuel cells have been successfully modeled under high pressure operation and further investigated as integrated components of an open loop gas turbine cycle.

  18. Thermodynamic analysis of SOFC (solid oxide fuel cell)–Stirling hybrid plants using alternative fuels

    International Nuclear Information System (INIS)

    Rokni, Masoud

    2013-01-01

    A novel hybrid power system (∼10 kW) for an average family home is proposed. The system investigated contains a solid oxide fuel cell (SOFC) on top of a Stirling engine. The off-gases produced in the SOFC cycle are fed to a bottoming Stirling engine, at which additional power is generated. Simulations of the proposed system were conducted using different fuels, which should facilitate the use of a variety of fuels depending on availability. Here, the results for natural gas (NG), ammonia, di-methyl ether (DME), methanol and ethanol are presented and analyzed. The system behavior is further investigated by comparing the effects of key factors, such as the utilization factor and the operating conditions under which these fuels are used. Moreover, the effect of using a methanator on the plant efficiency is also studied. The combined system improves the overall electrical efficiency relative to that of a stand-alone Stirling engine or SOFC plant. For the combined SOFC and Stirling configuration, the overall power production was increased by approximately 10% compared to that of a stand-alone SOFC plant. System efficiencies of approximately 60% are achieved, which is remarkable for such small plant sizes. Additionally, heat is also produced to heat the family home when necessary. - Highlights: • Integrating a solid oxide fuel with a Stirling engine • Design of multi-fuel hybrid plants • Plants running on alternative fuels; natural gas, methanol, ethanol, DME and ammonia • Thermodynamic analysis of hybrid SOFC–Stirling engine plants

  19. 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)

  20. Generator module architecture for a large solid oxide fuel cell power plant

    Science.gov (United States)

    Gillett, James E.; Zafred, Paolo R.; Riggle, Matthew W.; Litzinger, Kevin P.

    2013-06-11

    A solid oxide fuel cell module contains a plurality of integral bundle assemblies, the module containing a top portion with an inlet fuel plenum and a bottom portion receiving air inlet feed and containing a base support, the base supports dense, ceramic exhaust manifolds which are below and connect to air feed tubes located in a recuperator zone, the air feed tubes passing into the center of inverted, tubular, elongated, hollow electrically connected solid oxide fuel cells having an open end above a combustion zone into which the air feed tubes pass and a closed end near the inlet fuel plenum, where the fuel cells comprise a fuel cell stack bundle all surrounded within an outer module enclosure having top power leads to provide electrical output from the stack bundle, where the fuel cells operate in the fuel cell mode and where the base support and bottom ceramic air exhaust manifolds carry from 85% to all 100% of the weight of the stack, and each bundle assembly has its own control for vertical and horizontal thermal expansion control.