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Sample records for cell stack temperature

  1. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    The present work involves the development of a model for predicting the dynamic temperature of a high temperature PEM (HTPEM) fuel cell stack. The model is developed to test different thermal control strategies before implementing them in the actual system. The test system consists of a prototype...... stack at a high stoichiometric air flow. This is possible because of the PBI fuel cell membranes used, and the very low pressure drop in the stack. The model consists of a discrete thermal model dividing the stack into three parts: inlet, middle and end and predicting the temperatures in these three...... parts, where also the temperatures are measured. The heat balance of the system involves a fuel cell model to describe the heat added by the fuel cells when a current is drawn. Furthermore the model also predicts the temperatures, when heating the stack with external heating elements for start-up, heat...

  2. Real-time Monitoring of Internal Temperature and Voltage of High-temperature Fuel Cell Stack

    International Nuclear Information System (INIS)

    The nonuniform local temperature and voltage in the chemical reaction process of high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack can affect the reaction of membrane electrode assembly (MEA) and the performance and life of fuel cell stack. The effectiveness and internal information of fuel cell stack can be discussed by using external measurement, invasive, theoretical modeling, and single temperature, or voltage measurement. But there are some problems, such as mm scale sensor, inaccurate measurement, influencing the fuel cell stack performance, and failing to know internal actual reactive state instantly. This study uses micro-electro-mechanical systems (MEMS) technology to develop a new generation flexible micro temperature and voltage sensors applicable to high-temperature electrochemical environment. Micro sensors have embedded in the cathode channel plate of HT-PEMFC stack. At the operating temperature of 170 °C and constant current (2, 10, 20 A), the curvilinear trends of local temperature and voltage inside the fuel cell stack measured by flexible micro sensors are consistent, proving the reliability of micro sensors. The test result also shows that the heat distribution in the fuel cell stack is nonuniform

  3. Modelling and Evaluation of Heating Strategies for High Temperature Polymer Electrolyte Membrane Fuel Cell Stacks

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2008-01-01

    Experiments were conducted on two different cathode air cooled high temperature PEM (HTPEM) fuel cell stacks; a 30 cell 400W prototype stack using two bipolar plates per cell, and a 65 cell 1 kW commercial stack using one bipolar plate per cell. The work seeks to examine the use of different...

  4. Dynamic Model of the High Temperature Proton Exchange Membrane Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2009-01-01

    consists of a prototype cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes and runs on pure hydrogen in a dead-end anode configuration with a purge valve. The cooling of the stack...

  5. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature of...

  6. Characterisation and modelling of a high temperature PEM fuel cell stack using electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jespersen, J.L. [Danish Technological Institute, Kongsvang Alle 29, DK-8000 Arhus C (Denmark); Schaltz, E.; Kaer, S.K. [Department of Energy Technology, Aalborg University, Pontoppidanstraede 101, DK-9220 Aalborg East (Denmark); Andreasen, S.J.

    2009-08-15

    In designing and controlling fuel cell systems, it is advantageous to have models which predict fuel cell behaviour in steady-state as well as in dynamic operation. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterising and developing an impedance model for a high temperature PEM (HT-PEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell is a Nyquist plot, which shows the imaginary and real parts of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  7. Design and experimental characterization of a 350 W High Temperature PEM fuel cell stack

    Directory of Open Access Journals (Sweden)

    Nicola Zuliani

    2011-01-01

    Full Text Available High Temperature Proton Exchange Membrane (HT PEM fuel cell based on polybenzimidazole (PBI polymer and phosphoric acid, can be operated at temperature between 120 °C and 180 °C. Reactants humidification is not required and CO content up to 2% in the fuel can be tolerated, affecting only marginally performance. This is what makes HT PEM very attractive, as low quality reformed hydrogen can be used and water management problems are avoided. Till nowadays, from experimental point of view, only few studies relate to the development and characterization of high temperature stacks. The aim of this work is to present the main design features and the performance curves of a 25 cells HT PEM stack based on PBI and phosphoric acid membranes. Performance curves refer to the stack operating with two type of fuels: pure hydrogen and a gas mixture simulating a typical steam reformer output. The stack voltage distribution analysis and the stack temperature distribution analysis suggest that cathode air could be used as coolant leading to a better thermal management. This could simplify stack design and system BOP, thus increasing system performance.

  8. Dynamic modeling and experimental investigation of a high temperature PEM fuel cell stack

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    2016-01-01

    High temperature polymer fuel cells operating at 100 to 200◦C require simple fuel processing and produce high quality heat that can integrate well with domestic heating systems. Because the transportation of hydrogen is challenging, an alternative option is to reform natural gas on site. This...... article presents the development of a dynamic model and the comparison with experimental data from a high temperature proton exchange membrane fuel cell stack operating on hydrogen with carbon monoxide concentrations up to 0.8%, and temperatures from 155 to 175◦C. The dynamic response of the fuel cell is...... investigated with simulated reformate gas. The dynamic response of the fuel cell stack was compared with a step change in current from 0.09 to 0.18 and back to 0.09 A/cm2 . This article shows that the dynamic model calculates the voltage at steady state well. The dynamic response for a change in current shows...

  9. Characterisation and Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Schaltz, Erik;

    2009-01-01

    In designing and controlling fuel cell systems it is advantageous having models predicting fuel cell behavior in steady-state as well as in dynamic operation. This work examines the use of Electro-chemical Impedance Spectroscopy (EIS) for characterizing and developing an impedance model for a high...... used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics....... temperature PEM (HTPEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell, is a Nyquist plot, which shows the imaginary and real part of the impedance of...

  10. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    OpenAIRE

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    In designing and controlling fuel cell sys-tems it is advantageous having models predicting the behavior of the fuel cells in steady-state as well as in dynamic ope-ration. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterizing and developing a model for a high temperature PEM (HTPEM) fuel cell stack. A Labview virtual interface has been developed to perform the signal generation and acquisition which is needed to perform EIS. In designing and contro...

  11. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    In designing and controlling fuel cell sys-tems it is advantageous having models predicting the behavior of the fuel cells in steady-state as well as in dynamic ope-ration. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterizing and developing a model for a ...... high temperature PEM (HTPEM) fuel cell stack. A Labview virtual interface has been developed to perform the signal generation and acquisition which is needed to perform EIS.......In designing and controlling fuel cell sys-tems it is advantageous having models predicting the behavior of the fuel cells in steady-state as well as in dynamic ope-ration. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterizing and developing a model for a...

  12. Parametric Characterization of Reformate-operated PBI-based High Temperature PEM Fuel Cell Stack

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    2016-01-01

    This paper presents an experimental characterization of a HT-PEMFC short stack performed by means of impedance spectroscopy. Selected operating parameters; temperature, stoichiometry and reactant compositions were varied to investigate their effects on a reformate operated stack. Polarization...

  13. High temperature operation of a solid polymer electrolyte fuel cell stack based on a new ionomer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Arico, A.S.; Di Blasi, A.; Brunaccini, G.; Sergi, F.; Dispenza, G.; Andaloro, L.; Ferraro, M.; Antonucci, V. [CNR-ITAE, Messina (Italy); Asher, P.; Buche, S.; Fongalland, D.; Hards, G.A.; Sharman, J.D.B. [Johnson Matthey Fuel Cells Ltd, Blounts Court, Sonning Common, Reading, Berks (United Kingdom); Bayer, A.; Heinz, G.; Zandona, N. [SolviCore GmbH and Co KG, Hanau (Germany); Zuber, R. [Umicore AG and Co KG, Dept. RD-EP, Hanau (Germany); Gebert, M.; Corasaniti, M.; Ghielmi, A. [Solvay Solexis, Bollate (Italy)

    2010-12-15

    Polymer electrolyte fuel cell stacks assembled with Johnson Matthey Fuel Cells and SolviCore MEAs based on the Aquivion trademark E79-03S short-side chain (SSC), chemically stabilised perfluorosulphonic acid membrane developed by Solvay Solexis were investigated at CNR-ITAE in the EU Sixth Framework 'Autobrane' project. Electrochemical experiments in fuel cell short stacks were performed under practical automotive operating conditions at pressures of 1-1.5 bar abs. over a wide temperature range, up to 130 C, with varying levels of humidity (down to 18% R. H.). The stacks using large area (360 cm{sup 2}) MEAs showed elevated performance in the temperature range from ambient to 100 C (cell power density in the range of 600-700 mWcm{sup -2}) with a moderate decrease above 100 C. The performances and electrical efficiencies achieved at 110 C (cell power density of about 400 mWcm{sup -2} at an average cell voltage of about 0.5-0.6 V) are promising for automotive applications. Duty-cycle and steady-state galvanostatic experiments showed excellent stack stability for operation at high temperature. A performance comparison of Aquivion trademark and Nafion trademark -based MEAs under practical operating conditions showed a significantly better capability for the Solvay Solexis membrane to sustain high temperature operation. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. TEST RESULTS OF HIGH TEMPERATURE STEAM/CO2 CO-ELECTROLYSIS IN A 10-CELL STACK

    Energy Technology Data Exchange (ETDEWEB)

    James E. O' Brien; Joseph J. Hartvigsen

    2007-06-01

    High temperature coelectrolysis experiments with CO2 / H2O mixtures were performed in a 10-cell planar solid oxide stack. Results indicated that stack apparent ASR values were shown not to vary significantly between pure steam electrolysis and steam / CO2 coelectrolysis values. Product gas compositions measured via an online micro gas chromatograph (GC) showed excellent agreement to predictions obtained from a chemical equilibrium coelectrolysis model developed for this study. Experimentally determined open cell potentials and thermal neutral voltages for coelectrolysis compared favorably to predictions obtained from a chemical equilibrium coelectrolysis and energy balance model, also developed for this study.

  15. Small stack performance of intermediate temperature-operating solid oxide fuel cells using stainless steel interconnects and anode-supported single cell

    Science.gov (United States)

    Bae, Joongmyeon; Lim, Sungkwang; Jee, Hyunjin; Kim, Jung Hyun; Yoo, Young-Sung; Lee, Taehee

    We are developing 1 kW class solid oxide fuel cell (SOFC) system for residential power generation (RPG) application supported by Korean Government. Anode-supported single cells with thin electrolyte layer of YSZ (yttria-stabilized zirconia) or ScSZ (scandia-stabilized zirconia) for intermediate temperature operation (650-750 °C), respectively, were fabricated and small stacks were built and evaluated. The LSCF/ScSZ/Ni-YSZ single cell showed performance of 543 mW cm -2 at 650 °C and 1680 mW cm -2 at 750 °C. The voltage of 15-cell stack based on 5 cm × 5 cm single cell (LSM/YSZ/Ni-YSZ) at 150 mW was 12.5 V in hydrogen as fuel of 120 sccm per cell at 750 °C and decreased to about 10.9 V at 500 h operation time. A 5-cell stack based on the LSCF/YSZ/FL/Ni-YSZ showed the maximum power density of 30 W, 25 W and 20 W at 750 °C, 700 °C and 650 °C, respectively. LSCF/ScSZ/Ni-YSZ-based stack showed better performance than LSCF/YSZ/Ni-YSZ stack from the experiment temperature range. I- V characteristics by using hydrogen gas and reformate gas of methane as fuel were investigated at 750 °C in LSCF/ScSZ/FL/Ni-YSZ-based 5-cell stack.

  16. Small stack performance of intermediate temperature-operating solid oxide fuel cells using stainless steel interconnects and anode-supported single cell

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Joongmyeon; Lim, Sungkwang; Kim, Jung Hyun [Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea); Jee, Hyunjin [Agency for Defense Development (ADD), Jochiwongil 462, Yuseong, Daejeon (Korea); Yoo, Young-Sung; Lee, Taehee [Korea Electric Power Research Institute (KEPRI), Daejeon 305-380 (Korea)

    2007-10-11

    We are developing 1 kW class solid oxide fuel cell (SOFC) system for residential power generation (RPG) application supported by Korean Government. Anode-supported single cells with thin electrolyte layer of YSZ (yttria-stabilized zirconia) or ScSZ (scandia-stabilized zirconia) for intermediate temperature operation (650-750 C), respectively, were fabricated and small stacks were built and evaluated. The LSCF/ScSZ/Ni-YSZ single cell showed performance of 543 mW cm{sup -2} at 650 C and 1680 mW cm{sup -2} at 750 C. The voltage of 15-cell stack based on 5 cm x 5 cm single cell (LSM/YSZ/Ni-YSZ) at 150 mW was 12.5 V in hydrogen as fuel of 120 sccm per cell at 750 C and decreased to about 10.9 V at 500 h operation time. A 5-cell stack based on the LSCF/YSZ/FL/Ni-YSZ showed the maximum power density of 30 W, 25 W and 20 W at 750 C, 700 C and 650 C, respectively. LSCF/ScSZ/Ni-YSZ-based stack showed better performance than LSCF/YSZ/Ni-YSZ stack from the experiment temperature range. I-V characteristics by using hydrogen gas and reformate gas of methane as fuel were investigated at 750 C in LSCF/ScSZ/FL/Ni-YSZ-based 5-cell stack. (author)

  17. Estimation of Membrane Hydration Status for Standby Proton Exchange Membrane Fuel Cell Systems by Impedance Measurement: First Results on Variable Temperature Stack Characterization

    DEFF Research Database (Denmark)

    Bidoggia, Benoit; Kær, Søren Knudsen

    2013-01-01

    , the measurement of the complex impedance of a fuel cell stack during standby is used as an index of its membrane hydration status. In this article, the complex impedance of a fuel cell stack has been measured and characterized as a function of relative humidity and temperature. A non-conventional electrochemical...

  18. Evaluation of a 2.5 kWel automotive low temperature PEM fuel cell stack with extended operating temperature range up to 120 °C

    Science.gov (United States)

    Ruiu, Tiziana; Dreizler, Andreas M.; Mitzel, Jens; Gülzow, Erich

    2016-01-01

    Nowadays, the operating temperature of polymer electrolyte membrane fuel cell stacks is typically limited to 80 °C due to water management issues of membrane materials. In the present work, short-term operation at elevated temperatures up to 120 °C and long-term steady-state operation under automotive relevant conditions at 80 °C are examined using a 30-cell stack developed at DLR. The high temperature behavior is investigated by using temperature cycles between 90 and 120 °C without adjustment of the gases dew points, to simulate a short-period temperature increase, possibly caused by an extended power demand and/or limited heat removal. This galvanostatic test demonstrates a fully reversible performance decrease of 21 ± 1% during each thermal cycle. The irreversible degradation rate is about a factor of 6 higher compared to the one determined by the long-term test. The 1200-h test at 80 °C demonstrates linear stack voltage decay with acceptable degradation rate, apart from a malfunction of the air compressor, which results in increased catalyst degradation effects on individual cells. This interpretation is based on an end-of-life characterization, aimed to investigate catalyst, electrode and membrane degradation, by determining hydrogen crossover rates, high frequency resistances, electrochemically active surface areas and catalyst particle sizes.

  19. Development of a 400 W High Temperature PEM Fuel Cell Power Pack:Fuel Cell Stack Test

    OpenAIRE

    Andreasen, Søren Juhl; Bang, Mads; Korsgaard, Anders; Nielsen, Mads Pagh; Kær, Søren Knudsen

    2006-01-01

    When using pressurized hydrogen to fuel a fuel cell, much space is needed for fuel storage. This is undesirable especially with mobile or portable fuel cell systems, where refuelling also often is inconvenient. Using a reformed liquid carbonhydrate can reduce this fuel volume considerably. Nafion based low temperature PEM (LTPEM) fuel cells are very intolerant to reformate gas because of the presence of CO. PBI based high temperature PEM (HTPEM) fuel cells can operate stable at much higher CO...

  20. Modular fuel-cell stack assembly

    Science.gov (United States)

    Patel, Pinakin; Urko, Willam

    2008-01-29

    A modular multi-stack fuel-cell assembly in which the fuel-cell stacks are situated within a containment structure and in which a gas distributor is provided in the structure and distributes received fuel and oxidant gases to the stacks and receives exhausted fuel and oxidant gas from the stacks so as to realize a desired gas flow distribution and gas pressure differential through the stacks. The gas distributor is centrally and symmetrically arranged relative to the stacks so that it itself promotes realization of the desired gas flow distribution and pressure differential.

  1. Description of gasket failure in a 7 cell PEMFC stack

    Energy Technology Data Exchange (ETDEWEB)

    Husar, Attila; Serra, Maria [Institut de Robotica i Informatica Industrial, Parc Tecnologic de Barcelona, Edifici U, C. Llorens i Artigas, 4-6, 2a Planta, 08028 Barcelona (Spain); Kunusch, Cristian [Laboratorio de Electronica Industrial Control e Instrumentacion, Facultad de Ingenieria, UNLP (Argentina)

    2007-06-10

    This article presents the data and the description of a fuel cell stack that failed due to gasket degradation. The fuel cell under study is a 7 cell stack. The unexpected change in several variables such as temperature, pressure and voltage indicated the possible failure of the stack. The stack was monitored over a 6 h period in which data was collected and consequently analyzed to conclude that the fuel cell stack failed due to a crossover leak on the anode inlet port located on the cathode side gasket of cell 2. This stack failure analysis revealed a series of indicators that could be used by a super visional controller in order to initiate a shutdown procedure. (author)

  2. 质子交换膜燃料电池电堆的动态热模型及其温度控制%Dynamic Thermal Model and Temperature Control of Proton Exchange Membrane Fuel Cell Stack

    Institute of Scientific and Technical Information of China (English)

    邵庆龙; 卫东; 曹广益; 朱新坚

    2005-01-01

    A dynamic thermal transfer model of a proton exchange membrane fuel cell (PEMFC) stack is developed based on energy conservation in order to reach better temperature control of PEMFC stack. Considering its uncertain parameters and disturbance, we propose a robust adaptive controller based on backstepping algorithm of Lyaponov function. Numerical simulations indicate the validity of the proposed controller.

  3. Nonlinear Predictive Control for PEMFC Stack Operation Temperature

    Institute of Scientific and Technical Information of China (English)

    LI Xi; CAO Guang-yi; ZHU Xin-jian

    2005-01-01

    Operating temperature of proton exchange membrane fuel cell stack should be controlled within a special range. The input-output data and operating experiences were used to establish a PEMFC stack model and operating temperature control system. A nonlinear predictive control algorithm based on fuzzy model was presented for a family of complex system with severe nonlinearity such as PEMFC. Based on the obtained fuzzy model, a discrete optimization of the control action was carried out according to the principle of Branch and Bound method. The test results demonstrate the effectiveness and advantage of this approach.

  4. Temperature and flow distribution in planar SOFC stacks

    Directory of Open Access Journals (Sweden)

    Monica Østenstad

    1995-07-01

    Full Text Available Simulation of a planar Solid Oxide Fuel Cell stack requires the solution of the mass balances of the chemical species, the energy balances, the charge balance and the channel flow equations in order to compute the species concentrations, the temperature distributions, the current density and the channel flows. The unit cell geometry can be taken into account by combining detailed modeling of a unit cell with a homogenized model of a whole stack. In this study the effect of the asymmetric temperature distribution on the channel flows in a conventional cross-flow design has been investigated. The bidirectional cross-flow design is introduced, for which we can show more directional temperature and flow distributions.

  5. Modular fuel-cell stack assembly

    Science.gov (United States)

    Patel, Pinakin

    2010-07-13

    A fuel cell assembly having a plurality of fuel cells arranged in a stack. An end plate assembly abuts the fuel cell at an end of said stack. The end plate assembly has an inlet area adapted to receive an exhaust gas from the stack, an outlet area and a passage connecting the inlet area and outlet area and adapted to carry the exhaust gas received at the inlet area from the inlet area to the outlet area. A further end plate assembly abuts the fuel cell at a further opposing end of the stack. The further end plate assembly has a further inlet area adapted to receive a further exhaust gas from the stack, a further outlet area and a further passage connecting the further inlet area and further outlet area and adapted to carry the further exhaust gas received at the further inlet area from the further inlet area to the further outlet area.

  6. High temperature steam electrolysis stack with enhanced performance and durability

    International Nuclear Information System (INIS)

    High Temperature Steam Electrolysis (HTSE) is one of the most promising ways for hydrogen production. If coupled to a CO2-free electricity and low cost heat sources, this process is liable to a high efficiency. The present study describes recent promising results obtained in terms of performance and durability in stack environment, thanks to the use of protective coatings on one hand, and of advanced cells on the other hand. As for Solid Oxide Fuel Cells, it has been demonstrated that the integration of protective coatings was mandatory to decrease the degradation rate in HTSE stacks, and that with optimized coatings, (CoMn)3O4 in the present case, the same durability as the one of the single cell tested in a ceramic housing could be reached. The type of cell was also shown to play a major role on the degradation rate. With advanced cells, degradations below 2%/kh could be reached. The higher is the current density, the higher is the degradation rate, with a mostly reversible effect. These degradation rates are close to the objectives, even if a bit higher than in SOFC mode. Finally a low-weight stack has been designed, targeting high performance and durability while reducing the cost by the use of thin interconnects. An electrochemical performance similar to the previous stack design has been obtained for a 3-cell stack (-1 A/cm2) at 1.3 V at 800 degrees C), with degradation rates below 3%/1000 h in the testing conditions. The thermal cyclability of stacks has been demonstrated, from 800 degrees C to 20 degrees C, as well as electrical load cycling. The results showed that the HTSE stacks considered in the present study can cycle very rapidly, and that the cycles considered do not induce any degradation. Therefore it can be concluded that these results makes HTSE technology getting closer to the objectives of performance, durability, thermal and electrical cyclability and cost, and that HTSE is a candidate to produce hydrogen as a mean to store renewable

  7. Solid Oxide Fuel Cell Stack Diagnostics

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Barfod, Rasmus Gottrup

    time was cut down significantly and it was demonstrated parallel acquisition of 16 repeating units (cells) and the total stack impedance could be made fully automated. The performance and degradation of a 13-cell cross-flow stack was monitored for more than 2500 hours at steady operating conditions...... using the sequential impedance measurement setup. Impedance measurements was used to examine the long-term behavior and monitor the evolution of the series and polarization resistances for four out of the 13 repeating units during the first 1400 hours of operation. The losses for the four selected...... repeating units are reported and discussed. The performance and degradation of a 14-cell co-flow stack was monitored for more than 667 hours at steady operating conditions using the sequential impedance measurement setup. The stack was tested galvanostatically (at constant current) with 50% steam in the...

  8. A metallic seal for high-temperature electrolysis stacks

    International Nuclear Information System (INIS)

    Gas tightness over a long period of time is a real challenge in high-temperature electrolysis. The seals must indeed be able to run at high temperature between metals and brittle ceramic materials, which is a major issue to be solved. The common sealing solution relies on glass-made seals, despite their low mechanical strength at high temperature. Metallic seals have seldom been used in this field, because their stiffness and their hardness require a much higher load to achieve the appropriate tightness. In the French project ANR Pan-H/SEMIEHT, two different sealing solutions were investigated in two different locations of the GENHEPIS-G1 stack. Experiments were carried out with a glass-made seal between the cell and its ceramic support, and with metallic seals between the interconnect and the cell support, in order to seal the gas input and output as well as the cathodic chamber. An initial Garlock seal design has been optimised in order to decrease the seating load. Seals were also manufactured by Garlock. The C-shaped seals are made of two components: an Inconel-X750-made elastic inner part, and a specially profiled Fecralloy-made 'soft' outer lining. The use of Fecralloy enables the generation of an alumina thin layer, which both protects the seal and eases disassembly. In this study, these seals were tested on specific equipments and on actual stacks. It is shown that they are tight enough to achieve the electrolysis tests at 800 deg. C. Therefore a significant breakthrough in high-temperature electrolysis sealing has been achieved. It sheds new light on the actual potential of metallic seals and constitutes a basis for ongoing studies, such as another French project, namely ANR/Pan-H/EMAIL. (authors)

  9. Solid oxide cell stack and method for preparing same

    DEFF Research Database (Denmark)

    2012-01-01

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

  10. Thermal and Electrochemical Performance of a High-Temperature Steam Electrolysis Stack

    Energy Technology Data Exchange (ETDEWEB)

    J. O' Brien; C. Stoots; G. Hawkes; J. Hartvigsen

    2006-11-01

    A research program is under way at the Idaho National Laboratory (INL) to simultaneously address the research and scale-up issues associated with the implementation of solid-oxide electrolysis cell technology for hydrogen production from steam. We are conducting a progression of electrolysis stack testing activities, at increasing scales, along with a continuation of supporting research activities in the areas of materials development, single-cell testing, detailed computational fluid dynamics (CFD) and systems modeling. This paper will present recent experimental results obtained from testing of planar solid-oxide stacks operating in the electrolysis mode. The hydrogen-production and electrochemical performance of these stacks will be presented, over a range of operating conditions. In addition, internal stack temperature measurements will be presented, with comparisons to computational fluid dynamic predictions.

  11. Electrochemical removal of NOx with porous cell stacks

    DEFF Research Database (Denmark)

    Werchmeister, Rebecka Maria Larsen; Kammer Hansen, Kent; Mogensen, Mogens Bjerg

    2010-01-01

    In this study porous cell stacks were investigated for their ability to remove NOx electrochemically. The cell stacks were made from laminated tapes of porous electrolyte Ce0.9Gd0.1O1.95 and composite electrodes of La1−xSrxMnO3 (x = 0.15, and 0.5) and ceria doped with Gd or Pr. The cell stacks were...... infiltrated with nano-particles of pure ceria, Ce0.9Gd0.1O1.95 and Ce0.8Pr0.2O2−δ after sintering. A gas stream containing NO were sent through the cell stack. When the cell stacks were polarised with 0.75 V per cell then it was possible to remove some of the NOx in the temperature interval of 250–400 °C. The...

  12. Simple Stacking Methods for Silicon Micro Fuel Cells

    Directory of Open Access Journals (Sweden)

    Gianmario Scotti

    2014-08-01

    Full Text Available We present two simple methods, with parallel and serial gas flows, for the stacking of microfabricated silicon fuel cells with integrated current collectors, flow fields and gas diffusion layers. The gas diffusion layer is implemented using black silicon. In the two stacking methods proposed in this work, the fluidic apertures and gas flow topology are rotationally symmetric and enable us to stack fuel cells without an increase in the number of electrical or fluidic ports or interconnects. Thanks to this simplicity and the structural compactness of each cell, the obtained stacks are very thin (~1.6 mm for a two-cell stack. We have fabricated two-cell stacks with two different gas flow topologies and obtained an open-circuit voltage (OCV of 1.6 V and a power density of 63 mW·cm−2, proving the viability of the design.

  13. Compact bipolar plate-free direct methanol fuel cell stacks.

    Science.gov (United States)

    Dong, Xue; Takahashi, Motohiro; Nagao, Masahiro; Hibino, Takashi

    2011-05-14

    Fuel cells with a PtAu/C anode and a Pr-doped Mn(2)O(3)/C cathode were stacked without using a bipolar plate, and their discharge properties were investigated in a methanol aqueous solution bubbled with air. A three-cell stack exhibited a stack voltage of 2330 mV and a power output of 21 mW. PMID:21451850

  14. Nondestructive cell evaluation techniques in SOFC stack manufacturing

    Science.gov (United States)

    Wunderlich, C.

    2016-04-01

    Independent from the specifics of the application, a cost efficient manufacturing of solid oxide fuel cells (SOFC), its electrolyte membranes and other stack components, leading to reliable long-life stacks is the key for the commercial viability of this fuel cell technology. Tensile and shear stresses are most critical for ceramic components and especially for thin electrolyte membranes as used in SOFC cells. Although stack developers try to reduce tensile stresses acting on the electrolyte by either matching CTE of interconnects and electrolytes or by putting SOFC cells under some pressure - at least during transient operation of SOFC stacks ceramic cells will experience some tensile stresses. Electrolytes are required to have a high Weibull characteristic fracture strength. Practical experiences in stack manufacturing have shown that statistical fracture strength data generated by tests of electrolyte samples give limited information on electrolyte or cell quality. In addition, the cutting process of SOFC electrolytes has a major influence on crack initiation. Typically, any single crack in one the 30 to 80 cells in series connection will lead to a premature stack failure drastically reducing stack service life. Thus, for statistical reasons only 100% defect free SOFC cells must be assembled in stacks. This underlines the need for an automated inspection. So far, only manual processes of visual or mechanical electrolyte inspection are established. Fraunhofer IKTS has qualified the method of optical coherence tomography for an automated high throughput inspection. Alternatives like laser speckle photometry and acoustical methods are still under investigation.

  15. Micro PEM Fuel Cells and Stacks

    Institute of Scientific and Technical Information of China (English)

    Shou-shing; Hsieh

    2007-01-01

    1 Results The effects of different operating parameters on micro proton exchange membrane (PEM) fuel cell performance were experimentally studied for three different flow field configurations (interdigitated,mesh,and serpentine).Experiments with different cell operating temperatures and different backpressures on the H2 flow channels,as well as various combinations of these parameters,have been conducted for three different flow geometries.The micro PEM fuel cells were designed and fabricated in-house t...

  16. High-temperature steam electrolysis for hydrogen production: From material development to stack operation

    International Nuclear Information System (INIS)

    High-temperature steam electrolysis (HTSE) coupled with nuclear energy is one of the most promising options for hydrogen mass production. CEA (the French Atomic Energy Commission) is carrying out research in this field, from materials, cells and components developments to stack design including components and stack testing. One stack design among those developed at CEA will be addressed in this paper. This stack design is targeting high compactness, easy assembling and simple operation. The reliability of this design has been demonstrated through two tests of three cells short stacks, cells being commercial 225 cm2 electrolyte supported cells. Stacks have been operated in pure water vapour (no hydrogen introduced on the cathode side) at 820 deg. C. Hydrogen was produced at a flow rate of 7 mg/h/cm2 for the two stacks. The first stack was operated successfully for 170 hours. The test of the second one was extended up to 650 hours. Details about performance and durability of this second stack will be presented. Besides these activities on stack design, CEA is carrying out researches on new materials and cells in order to increase the cell and stack performances. For that purpose, alternative materials are studied, and among them layered perovskites used as oxygen electrode. This research, carried out jointly by ICMCB-CNRS and CEA highlighted the great potential of nickelates. It has been shown, on button cells at this stage, that the nickelate formulated Nd2NiO4+δ, represents a promising alternative to regular LSM anode (Patent CNRS-EDF (F) 'Procede et dispositif d'electrolyse de l'eau comprenant un materiau oxyde d'electrode particulier', P. Stevens, C. Lalanne, J.M. Bassat, F. Mauvy, J.C. Grenier. French patent: FR 2872174 2005-12-30). This material has been deposited on commercial half electrolyte supported cells, and three times higher performance has been obtained when operated in HTSE mode at 800 deg. C compared to an identical commercial cell containing the

  17. Development of a 100 W PEM fuel cell stack for portable applications

    Energy Technology Data Exchange (ETDEWEB)

    Eroglu, Inci; Erkan, Serdar [Middle East Technical Univ., Ankara (Turkey). Dept. of Chemical Engineering

    2010-07-01

    In this work, an air cooled 100 W stack was designed, manufactured and tested. The bipolar plates were manufactured by CNC machining of graphite. Membrane electrode assemblies (MEAs) were produced by spraying catalyst ink onto the gas diffusion layer (GDL). A fuel cell stack was assembled with 20 cells each having 12.25 cm{sup 2} active area. The test was carried out with H{sub 2} at anode and air at cathode side both at 100% relative humidity having 1.2 and 2 stoichiometric ratios, respectively. The operating temperature of the stack was kept at 60 C during the test. The results indicated that the stack has a maximum power of 60 W at 12 V operation. Cell numbers 1, 2, 3 and 20 always had less potential than the 0.6 V average cell voltage. Uniform cell voltage distribution has been achieved by improving thermal management and reactant distribution. (orig.)

  18. Identification and analysis based on genetic algorithm for proton exchange membrane fuel cell stack

    Institute of Scientific and Technical Information of China (English)

    LI Xi; CAO Guang-yi; ZHU Xin-jian; WEI Dong

    2006-01-01

    The temperature of proton exchange membrane fuel cell stack and the stoichiometric oxygen in cathode have relationship with the performance and life span of fuel cells closely. The thermal coefficients were taken as important factors affecting the temperature distribution of fuel cells and components. According to the experimental analysis, when the stoichiometric oxygen in cathode is greater than or equal to 1.8, the stack voltage loss is the least. A novel genetic algorithm was developed to identify and optimize the variables in dynamic thermal model of proton exchange membrane fuel cell stack, making the outputs of temperature model approximate to the actual temperature, and ensuring that the maximal error is less than 1℃. At the same time, the optimum region of stoichiometric oxygen is obtained, which is in the range of 1.8 -2.2 and accords with the experimental analysis results. The simulation and experimental results show the effectiveness of the proposed algorithm.

  19. Electrolytic cell stack with molten electrolyte migration control

    Science.gov (United States)

    Kunz, H. Russell; Guthrie, Robin J.; Katz, Murray

    1988-08-02

    An electrolytic cell stack includes inactive electrolyte reservoirs at the upper and lower end portions thereof. The reservoirs are separated from the stack of the complete cells by impermeable, electrically conductive separators. Reservoirs at the negative end are initially low in electrolyte and the reservoirs at the positive end are high in electrolyte fill. During stack operation electrolyte migration from the positive to the negative end will be offset by the inactive reservoir capacity. In combination with the inactive reservoirs, a sealing member of high porosity and low electrolyte retention is employed to limit the electrolyte migration rate.

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

    Directory of Open Access Journals (Sweden)

    D. Mogensen

    2014-01-01

    Full Text Available The kinetics of catalytic steam reforming of methane over an Ni-YSZ anode of a solid oxide fuel cell (SOFC have been investigated with the cell placed in a stack configuration. In order to decrease the degree of conversion, a single cell stack with reduced area was used. Measurements were performed in the temperature range 600–800°C and the partial pressures of all reactants and products were varied. The obtained rates could be well fitted with a power law expression (r ∝PCH40.7. A simple model is presented which is capable of predicting the methane conversion in a stack configuration from intrinsic kinetics of the anode support material. The predictions are compared with the stack measurements presented here, and good agreement is observed.

  1. Ablation of film stacks in solar cell fabrication processes

    Science.gov (United States)

    Harley, Gabriel; Kim, Taeseok; Cousins, Peter John

    2013-04-02

    A dielectric film stack of a solar cell is ablated using a laser. The dielectric film stack includes a layer that is absorptive in a wavelength of operation of the laser source. The laser source, which fires laser pulses at a pulse repetition rate, is configured to ablate the film stack to expose an underlying layer of material. The laser source may be configured to fire a burst of two laser pulses or a single temporally asymmetric laser pulse within a single pulse repetition to achieve complete ablation in a single step.

  2. Water transport during startup and shutdown of polymer electrolyte fuel cell stacks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Tajiri, K.; Ahluwalia, R.K. [Argonne National Laboratory, 9700 S Cass Avenue, Argonne, IL 60439 (United States)

    2010-10-01

    A dynamic three-phase transport model is developed to analyze water uptake and transport in the membrane and catalyst layers of polymer electrolyte fuel cells during startup from subfreezing temperatures and subsequent shutdown. The initial membrane water content ({lambda}, the number of water molecules per sulfonic acid site) is found to be an important parameter that determines whether a successful unassisted self-start is possible. For a given initial subfreezing temperature at startup, there is a critical {lambda} ({lambda}{sub h}), above which self-start is not possible because the product water completely engulfs the catalyst layers with ice before the stack can warm-up to 0 C. There is a second value of {lambda} ({lambda}{sub l}), below which the stack can be self-started without forming ice. Between {lambda}{sub l} and {lambda}{sub h}, the stack can be self-started, but with intermediate formation of ice that melts as the stack warms up to 0 C. Both {lambda}{sub l} and {lambda}{sub h} are functions of the initial stack temperature, cell voltage at startup, membrane thickness, catalyst loading, and stack heat capacity. If the stack is purged during the previous shutdown by flowing air in the cathode passages, then depending on the initial amount of water in the membrane and gas diffusion layers and the initial stack temperature, it may not be possible to dry the membrane to the critical {lambda} for a subsequent successful startup. There is an optimum {lambda} for robust and rapid startup and shutdown. Startup and shutdown time and energy may be unacceptable if the {lambda} is much less than the optimum. Conversely, a robust startup from subfreezing temperatures cannot be assured if the {lambda} is much higher than this optimum. (author)

  3. Water transport during startup and shutdown of polymer electrolyte fuel cell stacks.

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Tajiri, K.; Ahluwalia, R.; Nuclear Engineering Division

    2010-10-01

    A dynamic three-phase transport model is developed to analyze water uptake and transport in the membrane and catalyst layers of polymer electrolyte fuel cells during startup from subfreezing temperatures and subsequent shutdown. The initial membrane water content (?, the number of water molecules per sulfonic acid site) is found to be an important parameter that determines whether a successful unassisted self-start is possible. For a given initial subfreezing temperature at startup, there is a critical ? (?h), above which self-start is not possible because the product water completely engulfs the catalyst layers with ice before the stack can warm-up to 0 C. There is a second value of ? (?l), below which the stack can be self-started without forming ice. Between ?l and ?h, the stack can be self-started, but with intermediate formation of ice that melts as the stack warms up to 0 C. Both ?l and ?h are functions of the initial stack temperature, cell voltage at startup, membrane thickness, catalyst loading, and stack heat capacity. If the stack is purged during the previous shutdown by flowing air in the cathode passages, then depending on the initial amount of water in the membrane and gas diffusion layers and the initial stack temperature, it may not be possible to dry the membrane to the critical ? for a subsequent successful startup. There is an optimum ? for robust and rapid startup and shutdown. Startup and shutdown time and energy may be unacceptable if the ? is much less than the optimum. Conversely, a robust startup from subfreezing temperatures cannot be assured if the ? is much higher than this optimum.

  4. Continued SOFC cell and stack technology and improved production methods

    Energy Technology Data Exchange (ETDEWEB)

    Wandel, M.; Brodersen, K.; Phair, J. (and others)

    2009-05-15

    Within this project significant results are obtained on a number of very diverse areas ranging from development of cell production, metallic creep in interconnect to assembling and test of stacks with foot print larger than 500 cm2. Out of 38 milestones 28 have been fulfilled and 10 have been partly fulfilled. This project has focused on three main areas: 1) The continued cell development and optimization of manufacturing processes aiming at production of large foot-print cells, improving cell performance and development environmentally more benign production methods. 2) Stack technology - especially stacks with large foot print and improving the stack design with respect to flow geometry and gas leakages. 3) Development of stack components with emphasis on sealing (for 2G as well as 3G), interconnect (coat, architecture and creep) and test development. Production of cells with a foot print larger than 500 cm2 is very difficult due to the brittleness of the cells and great effort has been put into this topic. Eight cells were successfully produced making it possible to assemble and test a real stack thereby giving valuable results on the prospects of stacks with large foot print. However, the yield rate is very low and a significant development to increase this yield lies ahead. Several lessons were learned on the stack level regarding 'large foot print' stacks. Modelling studies showed that the width of the cell primarily is limited by production and handling of the cell whereas the length (in the flow direction) is limited by e.g. pressure drop and necessary manifolding. The optimal cell size in the flow direction was calculated to be between approx20 cm and < 30 cm. From an economical point of view the production yield is crucial and stacks with large foot print cell area are only feasible if the cell production yield is significantly enhanced. Co-casting has been pursued as a production technique due to the possibilities in large scale production

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

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

    OpenAIRE

    Mogensen, D.; J.-D. Grunwaldt; Hendriksen, P. V.; J. U. Nielsen; K. Dam-Johansen

    2014-01-01

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

  7. High specific power, direct methanol fuel cell stack

    Science.gov (United States)

    Ramsey, John C.; Wilson, Mahlon S.

    2007-05-08

    The present invention is a fuel cell stack including at least one direct methanol fuel cell. A cathode manifold is used to convey ambient air to each fuel cell, and an anode manifold is used to convey liquid methanol fuel to each fuel cell. Tie-bolt penetrations and tie-bolts are spaced evenly around the perimeter to hold the fuel cell stack together. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet manifold with an integral flow restrictor to the outlet manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold. Located between the two plates is the fuel cell active region.

  8. Monitoring and Modeling Temperature Variations Inside Silage Stack Using Novel Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Green, Ole; Shahrak Nadimi, Esmaeil; Blanes-Vidal, Victoria;

    2009-01-01

    the temperature inside silage stacks; (2) to design a suitable sensor protection housing that prevents physical and chemical damage to the sensor; and (3) to mathematically model temperature variations inside a silage stack, using system identification techniques. The designed wireless nodes were used......Abstract: By monitoring silage temperature at different locations inside silage stacks, it is possible to detect any significant increases in temperature occurring during silage decomposition. The objectives of this study were: (1) to develop novel noninvasive wireless sensor nodes for measuring...... to monitor temperatures in a full-sized silage stack over 53 days. Results showed that the wireless sensor nodes accurately monitored the temperature inside the silage stack at depths of 25 and 50 cm and reliably transmitted the measured data through the network; between 98.9% and 99.4% of the...

  9. Optimum design of bipolar plates for separate air flow cooling system of PEM fuel cells stacks

    Science.gov (United States)

    Franco, Alessandro

    2015-12-01

    The paper discusses about thermal management of PEM fuel cells. The objective is to define criteria and guidelines for the design of the air flow cooling system of fuel cells stacks for different combination of power density, bipolar plates material, air flow rate, operating temperature It is shown that the optimization of the geometry of the channel permits interesting margins for maintaining the use of separate air flow cooling systems for high power density PEM fuel cells.

  10. Parametric Sensitivity Tests- European PEM Fuel Cell Stack Test Procedures

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2014-01-01

    As fuel cells are increasingly commercialized for various applications, harmonized and industry-relevant test procedures are necessary to benchmark tests and to ensure comparability of stack performance results from different parties. This paper reports the results of parametric sensitivity tests...

  11. Experimental 1 kW 20 cell PEFC stack

    Energy Technology Data Exchange (ETDEWEB)

    Buechi, F.N.; Marmy, C.A.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ruge, M. [Swiss Federal Inst. of Technology (ETH), Zuerich (Switzerland)

    1999-08-01

    A 20-cell PEFC stack was designed and built. Resin impregnated graphite was used as bipolar plate material. The air cooling of the stack was optimized by introducing high surface structures into the open space of the cooling plates. At {eta} (H{sub 2} LHV) = 0.5 a power of 880 W was obtained under conditions of low gas-pressures of 1.15 bar{sub a}. The auxiliary power for process air supply and cooling at 880 W power is less than 7% of the power output, indicating that the described system may be operated at a high efficiency. (author) 5 figs., 2 refs.

  12. A polymer electrolyte fuel cell stack for stationary power generation from hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Gottesfeld, S. [Los Alamos National Lab., NM (United States)

    1995-09-01

    The fuel cell is the most efficient device for the conversion of hydrogen fuel to electric power. As such, the fuel cell represents a key element in efforts to demonstrate and implement hydrogen fuel utilization for electric power generation. The low temperature, polymer electrolyte membrane fuel cell (PEMFC) has recently been identified as an attractive option for stationary power generation, based on the relatively simple and benign materials employed, the zero-emission character of the device, and the expected high power density, high reliability and low cost. However, a PEMFC stack fueled by hydrogen with the combined properties of low cost, high performance and high reliability has not yet been demonstrated. Demonstration of such a stack will remove a significant barrier to implementation of this advanced technology for electric power generation from hydrogen. Work done in the past at LANL on the development of components and materials, particularly on advanced membrane/electrode assemblies (MEAs), has contributed significantly to the capability to demonstrate in the foreseeable future a PEMFC stack with the combined characteristics described above. A joint effort between LANL and an industrial stack manufacturer will result in the demonstration of such a fuel cell stack for stationary power generation. The stack could operate on hydrogen fuel derived from either natural gas or from renewable sources. The technical plan includes collaboration with a stack manufacturer (CRADA). It stresses the special requirements from a PEMFC in stationary power generation, particularly maximization of the energy conversion efficiency, extension of useful life to the 10 hours time scale and tolerance to impurities from the reforming of natural gas.

  13. Development of Bipolar Plate Stack Type Microbial Fuel Cells

    International Nuclear Information System (INIS)

    Microbial fuel cells (MFC) stacked with bipolar plates have been constructed and their performance was tested. In this design, single fuel cell unit was connected in series by bipolar plates where an anode and a cathode were made in one graphite block. Two types of bipolar plate stacked MFCs were constructed. Both utilized the same glucose oxidation reaction catalyzed by Gram negative bacteria, Proteus vulgaris as a biocatalyst in an anodic compartment, but two different cathodic reactions were employed: One with ferricyanide reduction and the other with oxygen reduction reactions. In both cases, the total voltage was the mathematical sum of individual fuel cells and no degradation in performance was found. Electricity from these MFCs was stored in a supercapacitor to drive external loads such as a motor and electric bulb

  14. Modelling the impact of creep on the probability of failure of a solid oxidefuel cell stack

    DEFF Research Database (Denmark)

    Greco, Fabio; Frandsen, Henrik Lund; Nakajo, Arata; Madsen, Mads Find; Van herle, Jan

    2014-01-01

    In solid oxide fuel cell (SOFC) technology a major challenge lies in balancing thermal stresses from an inevitable thermal field. The cells are known to creep, changing over time the stress field. The main objective of this study was to assess the influence of creep on the failure probability of an...... SOFC stack. A finite element analysis on a single repeating unit of the stack was performed, in which the influence of the mechanical interactions,the temperature-dependent mechanical properties and creep of the SOFC materials are considered. Moreover, stresses from the thermo-mechanical simulation of...... sintering of the cells have been obtained and were implemented into the model of the single repeating unit. The significance of the relaxation of the stresses by creep in the cell components and its influence on the probability of cell survival was investigated. Finally, the influence of cell size on the...

  15. Unsteady 2D PEM fuel cell modeling for a stack emphasizing thermal effects

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Yuyao; Choe, Song-Yul [Department of Mechanical Engineering, Auburn University, Auburn (United States); Choi, Seo-Ho [Fuel Cell Vehicle Team, Hyundai Motor Company and Kia Motors Corporation (United States)

    2007-02-25

    Models currently used for analyses of thermal and water behavior of a PEM fuel cell are based 3D computational fluid dynamics (CFD). However, the analyses are limited to a single cell with static behavior. Thus, these models cannot be used for analyses of dynamic behavior of a stack that continuously varies according to operating conditions. The model proposed describes dynamic behavior of a stack with two adjoining cells and endplate assembly, and work as a current controlled voltage source that can be used for optimization of BOPs and the associated controls. Simulations have been conducted to analyze start-up behaviors and the performance of the stack. Our analyses deliver following results: (1) dynamic temperature distribution in both the through-plane direction and the along channel direction of the fuel cell stack, (2) effects influencing the source terms of current density, and (3) dynamic oxygen concentration distribution. The temperature profile and its variation propensity are comparable to the previous results [Y. Shan, S.Y. Choe, J. Power Sources, 145 (1) (2005) 30-39; Y. Shan, S.Y. Choe, J. Power Sources, in press]. (author)

  16. Dynamic cell performance of kW-grade proton exchange membrane fuel cell stack with dead-ended anode

    International Nuclear Information System (INIS)

    Highlights: • A kW-grade fuel cell stack with anode dead-ended mode was examined. • The dead-ended anode is achieved by controlling the anode outlet solenoid valve. • Results indicated an optimal purge interval and duration for cell performance. - Abstract: This paper examines the dynamic cell performance of a kW-grade proton exchange membrane fuel cell stack with anode dead-ended mode fuel supply. A self-made kW-grade 40 cells stack with reaction area of 112.85 cm2 has been used in the experiment. A single-chip (DSPIC30F4011) is utilized for establishing a control circuit to monitor the voltage and current with constant-current loading. The stack temperature is controlled at a low-level temperature rise. To enhance the hydrogen utilization and reduce the water flooding in the fuel cell stack, the dead-ended anode operation is accomplished by controlling the open or close of the anode outlet solenoid valve. As the loading is heavy, the anode outlet solenoid valve is purged frequently to force the water to flow out. While a light load, the anode outlet solenoid valve is shut down for a period time for hydrogen saving. The solenoid valve is controlled to be opened, referred as purge interval, reaching the discharge amount for 1000 C, 1500 C, and 2000 C as parameter, respectively. The open period of solenoid valve, referred as purge duration, is set as 1 s, 3 s, and 5 s for this study. Experimental results indicate an optimal purge interval and duration for water management and cell performance of the fuel cell stack

  17. Engineering aspects and hardware verification of a volume producable solid oxide fuel cell stack design for diesel auxiliary power units

    Science.gov (United States)

    Stelter, Michael; Reinert, Andreas; Mai, Björn Erik; Kuznecov, Mihail

    A solid oxide fuel cell (SOFC) stack module is presented that is designed for operation on diesel reformate in an auxiliary power unit (APU). The stack was designed using a top-down approach, based on a specification of an APU system that is installed on board of vehicles. The stack design is planar, modular and scalable with stamped sheet metal interconnectors. It features thin membrane electrode assemblies (MEAs), such as electrolyte supported cells (ESC) and operates at elevated temperatures around 800 °C. The stack has a low pressure drop in both the anode and the cathode to facilitate a simple system layout. An overview of the technical targets met so far is given. A stack power density of 0.2 kW l -1 has been demonstrated in a fully integrated, thermally self-sustaining APU prototype running with diesel and without an external water supply.

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

    DEFF Research Database (Denmark)

    Auer, C.; Lang, M.; Couturier, K.; Ravn Nielsen, Eva; J. McPhail, S.; Tsotridis, G.; Fu, Q.; H. Chan, S.

    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...

  19. Maturing of SOFC cell and stack production technology and preparation for demonstration of SOFC stacks. Part 2

    Energy Technology Data Exchange (ETDEWEB)

    2006-07-01

    The TOFC/Riso pilot plant production facility for the manufacture of anode-supported cells has been further up-scaled with an automated continuous spraying process and an extra sintering capacity resulting in production capacity exceeding 15,000 standard cells (12x12 cm2) in 2006 with a success rate of about 85% in the cell production. All processing steps such as tape-casting, spraying, screen-printing and atmospheric air sintering in the cell production have been selected on condition that up-scaling and cost effective, flexible, industrial mass production are feasible. The standard cell size is currently being increased to 18x18 cm2, and 150 cells of this size have been produced in 2006 for our further stack development. To improve quality and lower production cost, a new screen printing line is under establishment. TOFC's stack design is an ultra compact multilayer assembly of cells (including contact layers), metallic interconnects, spacer frames and glass seals. The compactness ensures minimized material consumption and low cost. Standard stacks with cross flow configuration contains 75 cells (12x12cm2) delivering about 1.2 kW at optimal operation conditions with pre-reformed NG as fuel. Stable performance has been demonstrated for 500-1000 hours. Significantly improved materials, especially concerning the metallic interconnect and the coatings have been introduced during the last year. Small stacks (5-10 cells) exhibit no detectable stack degradation using our latest cells and stack materials during test periods of 500-1000 hours. Larger stacks (50-75 cells) suffer from mal-distribution of gas and air inside the stacks, gas leakage, gas cross-over, pressure drop, and a certain loss of internal electrical contact during operation cycles. Measures have been taken to find solutions during the following development work. The stack production facilities have been improved and up-scaled. In 2006, 5 standard stacks have been assembled and burned in based on

  20. Durable SOC stacks for production of hydrogen and synthesis gas by high temperature electrolysis

    DEFF Research Database (Denmark)

    Ebbesen, Sune Dalgaard; Høgh, Jens Valdemar Thorvald; Nielsen, Karsten Agersted;

    2011-01-01

    Electrolysis of steam and co-electrolysis of steam and carbon dioxide was studied in Solid Oxide Electrolysis Cell (SOEC) stacks composed of Ni/YSZ electrode supported SOECs. The results of this study show that long-term electrolysis is feasible without notable degradation in these SOEC stacks. T...

  1. Experiment and numerical simulation on the performance of a kw-scale molten carbonate fuel cell stack

    Directory of Open Access Journals (Sweden)

    L. J. Yu

    2007-12-01

    Full Text Available A high-temperature molten carbonate fuel cell stack was studied experimentally and computationally. Experimental data for fuel cell temperature was obtained when the stack was running under given operational conditions. A 3-D CFD numerical model was set up and used to simulate the central fuel cell in the stack. It includes the mass, momentum and energy conservation equations, the ideal gas law and an empirical equation for cell voltage. The model was used to simulate the transient behavior of the fuel cell under the same operational conditions as those of the experiment. Simulation results show that the transient temperature and current and power densities reach their maximal values at the channel outlet. A comparison of the modeling results and the experimental data shows the good agreement.

  2. Hybrid Dynamic Modeling and Control of Molten Carbonate Fuel Cell Stack Shutdown

    Institute of Scientific and Technical Information of China (English)

    LI Yong; CAO Guang-yi; ZHU Xin-jian

    2007-01-01

    A hybrid automaton modeling approach that incorporates state space partitioning, phase dynamic modeling and control law synthesis by control strategy is utilized to develop a hybrid automaton model of molten carbonate fuel cell (MCFC) stack shutdown. The shutdown operation is divided into several phases and their boundaries are decided according to a control strategy, which is a set of specifications about the dynamics of MCFC stack during shutdown. According to the control strategy, the specification of increasing stack temperature is satisfied in a phase that can be modeled accurately. The model for phase that has complex dynamic is approximated. The duration of this kind of phase is decreased to minimize the error caused by model approximation.

  3. LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; R. C. O' Brien; X. Zhang; G. Tao; B. J. Butler

    2011-11-01

    Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cell and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.

  4. Final Report - MEA and Stack Durability for PEM Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yandrasits, Michael A.

    2008-02-15

    Proton exchange membrane fuel cells are expected to change the landscape of power generation over the next ten years. For this to be realized one of the most significant challenges to be met for stationary systems is lifetime, where 40,000 hours of operation with less than 10% decay is desired. This project conducted fundamental studies on the durability of membrane electrode assemblies (MEAs) and fuel cell stack systems with the expectation that knowledge gained from this project will be applied toward the design and manufacture of MEAs and stack systems to meet DOE’s 2010 stationary fuel cell stack systems targets. The focus of this project was PEM fuel cell durability – understanding the issues that limit MEA and fuel cell system lifetime, developing mitigation strategies to address the lifetime issues and demonstration of the effectiveness of the mitigation strategies by system testing. To that end, several discoveries were made that contributed to the fundamental understanding of MEA degradation mechanisms. (1) The classically held belief that membrane degradation is solely due to end-group “unzipping” is incorrect; there are other functional groups present in the ionomer that are susceptible to chemical attack. (2) The rate of membrane degradation can be greatly slowed or possibly eliminated through the use of additives that scavenge peroxide or peroxyl radicals. (3) Characterization of GDL using dry gases is incorrect due to the fact that fuel cells operate utilizing humidified gases. The proper characterization method involves using wet gas streams and measuring capillary pressure as demonstrated in this project. (4) Not all Platinum on carbon catalysts are created equally – the major factor impacting catalyst durability is the type of carbon used as the support. (5) System operating conditions have a significant impact of lifetime – the lifetime was increased by an order of magnitude by changing the load profile while all other variables remain

  5. Materials for low-temperature fuel cells

    CERN Document Server

    Ladewig, Bradley; Yan, Yushan; Lu, Max

    2014-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in Low-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in low-temperature fuel cells. A related book will cover key materials in high-temperature fuel cells. The two books form part

  6. System for adding sulfur to a fuel cell stack system for improved fuel cell stability

    Science.gov (United States)

    Mukerjee, Subhasish; Haltiner, Jr., Karl J; Weissman, Jeffrey G

    2013-08-13

    A system for adding sulfur to a reformate stream feeding a fuel cell stack, having a sulfur source for providing sulfur to the reformate stream and a metering device in fluid connection with the sulfur source and the reformate stream. The metering device injects sulfur from the sulfur source to the reformate stream at a predetermined rate, thereby providing a conditioned reformate stream to the fuel cell stack. The system provides a conditioned reformate stream having a predetermined sulfur concentration that gives an acceptable balance of minimal drop in initial power with the desired maximum stability of operation over prolonged periods for the fuel cell stack.

  7. Modeling of a PEM Fuel Cell Stack using Partial Least Squares and Artificial Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Han, In-Su; Shin, Hyun Khil [GS Caltex Corp, Daejeon (Korea, Republic of)

    2015-04-15

    We present two data-driven modeling methods, partial least square (PLS) and artificial neural network (ANN), to predict the major operating and performance variables of a polymer electrolyte membrane (PEM) fuel cell stack. PLS and ANN models were constructed using the experimental data obtained from the testing of a 30 kW-class PEM fuel cell stack, and then were compared with each other in terms of their prediction and computational performances. To reduce the complexity of the models, we combined a variables importance on PLS projection (VIP) as a variable selection method into the modeling procedure in which the predictor variables are selected from a set of input operation variables. The modeling results showed that the ANN models outperformed the PLS models in predicting the average cell voltage and cathode outlet temperature of the fuel cell stack. However, the PLS models also offered satisfactory prediction performances although they can only capture linear correlations between the predictor and output variables. Depending on the degree of modeling accuracy and speed, both ANN and PLS models can be employed for performance predictions, offline and online optimizations, controls, and fault diagnoses in the field of PEM fuel cell designs and operations.

  8. Modeling of a PEM Fuel Cell Stack using Partial Least Squares and Artificial Neural Networks

    International Nuclear Information System (INIS)

    We present two data-driven modeling methods, partial least square (PLS) and artificial neural network (ANN), to predict the major operating and performance variables of a polymer electrolyte membrane (PEM) fuel cell stack. PLS and ANN models were constructed using the experimental data obtained from the testing of a 30 kW-class PEM fuel cell stack, and then were compared with each other in terms of their prediction and computational performances. To reduce the complexity of the models, we combined a variables importance on PLS projection (VIP) as a variable selection method into the modeling procedure in which the predictor variables are selected from a set of input operation variables. The modeling results showed that the ANN models outperformed the PLS models in predicting the average cell voltage and cathode outlet temperature of the fuel cell stack. However, the PLS models also offered satisfactory prediction performances although they can only capture linear correlations between the predictor and output variables. Depending on the degree of modeling accuracy and speed, both ANN and PLS models can be employed for performance predictions, offline and online optimizations, controls, and fault diagnoses in the field of PEM fuel cell designs and operations

  9. Materials for high-temperature fuel cells

    CERN Document Server

    Jiang, San Ping; Lu, Max

    2013-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in High-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in high-temperature fuel cells with emphasis on the most important solid oxide fuel cells. A related book will cover key mater

  10. PEM Fuel Cells from Single Cell to Stack - Fundamental, Modeling, Analysis, and Applications

    OpenAIRE

    Maher A.R. Sadiq Al-Baghdadi

    2015-01-01

    Part I: Fundamentals Chapter 1: Introduction. Chapter 2: PEM fuel cell thermodynamics, electrochemistry, and performance. Chapter 3: PEM fuel cell components. Chapter 4: PEM fuel cell failure modes. Part II: Modeling and Simulation Chapter 5: PEM fuel cell models based on semi-empirical simulation. Chapter 6: PEM fuel cell models based on computational fluid dynamics (CFD). Part III: Analysis Chapter 7: PEM fuel cell analysis. Chapter 8: PEM fuel cell stack desig...

  11. Modeling and simulation of a reformate supplied PEM fuel cell stack, application to fault detection

    OpenAIRE

    Najafi, Masoud; Dipenta, Damiano; Bencherif, Karim; Sorine, Michel

    2007-01-01

    A method to reduce the model of a nonlinear dynamic fuel cell stack, which is suitable for control and fault detection studies, is presented. In order to model the fuel cell stack, we have assumed that the fuel cells are arranged in a stack, electrically in series, with thermal and electrical contacts. Since in practical applications a stack may be composed of several (at least fifty) fuel cells, such model will be a large set of differential equations which may be difficult to simulate espec...

  12. Mechanically Stacked Four-Junction Concentrator Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, Myles A.; Geisz, John F.; Ward, J. Scott; Garcia, Ivan; Friedman, Daniel J.; King, Richard R.; Chiu, Philip T.; France, Ryan M.; Duda, Anna; Olavarria, Waldo J.; Young, Michelle; Kurtz, Sarah R.

    2015-06-14

    Multijunction solar cells can be fabricated by bonding together component cells that are grown separately. Because the component cells are each grown lattice-matched to suitable substrates, this technique allows alloys of different lattice constants to be combined without the structural defects introduced when using metamorphic buffers. Here we present results on the fabrication and performance of four-junction mechanical stacks composed of GaInP/GaAs and GaInAsP/GaInAs tandems, grown on GaAs and InP substrates, respectively. The two tandems were bonded together with a low-index, transparent epoxy that acts as an omni-directional reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the sub-bandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subcell demonstrates a higher internal radiative limit and thus higher subcell voltage, compared with GaAs subcells without enhanced internal optics; all four subcells exhibit excellent material quality. The device was fabricated with four contact terminals so that each tandem can be operated at its maximum power point, which raises the cumulative efficiency and decreases spectral sensitivity. Efficiencies exceeding 38% at one-sun have been demonstrated. Eliminating the series resistance is the key challenge for the concentrator cells. We will discuss the performance of one-sun and concentrator versions of the device, and compare the results to recently fabricated monolithic four-junction cells.

  13. Experiences from design and testing of a small PEM fuel cell stack

    International Nuclear Information System (INIS)

    'Full text:' Introduction The Proton Exchange Membrane Fuel Cell (PEMFC) technology is considered the most promising candidate for mobile applications, due to its high power density, short start-up times and immediate response to changes in power demand. PEMFC systems tend, however, to become rather complex in order to provide for optimum water and thermal management, and facilitate stable operation. Auxiliary components add to cost and volume, and may reduce reliability. Pressurized operation may increase system power density, but to the sacrifice of efficiency. The atmospheric systems are inferior to pressurized systems with respect to water self-sufficiency and usually demand voluminous water condenser systems. At high power densities the amount of waste heat becomes considerable, and for larger systems liquid cooling is usually inevitable. But even for smaller, air-cooled systems, thermal management is challenging because of the relatively small temperature difference between the fuel cell and the surroundings. Over more than a decade there has been a trend towards simpler PEMFC systems holding a minimum number of auxiliary components, operating at atmospheric pressure and utilizing various self-humidifying techniques. However, due to the complexity of PEMFC operation, the degree of simplification becomes a trade-off between system cost and volume, and controllability. Experimental In the present work a small 10 cell PEMFC stack for demonstrational purposes was designed, assembled and tested. Commercial MEAs (Gore) and GDLs (E-TEK) were used. Thermocouples were inserted into the cathode air channels. Based on a total of 300 temperature measurements a semi-3-dimensional temperature distribution in the stack was obtained. Cell performance was characterized by obtaining polarization curves for each cell and measuring the steady state temperature distribution at a current density of 0.10 A/cm2. Results and Discussion Stable performance was obtained at 0.10 A/cm2

  14. Occurrence and implications of voltage reversal in stacked microbial fuel cells.

    Science.gov (United States)

    An, Junyeong; Lee, Hyung-Sool

    2014-06-01

    Voltage reversal in stacked microbial fuel cells (MFCs) is a significant challenge that must be addressed, and the information on its definite cause and occurrence process is still obscure. In this work, we first demonstrated that different anodic reaction rates caused voltage reversal in a stacked MFC. Sluggish reaction rates on the anode in unit 1 of the stacked MFC resulted in a significantly increased anode overpotential of up to 0.132 V, as compared to negligible anode overpotential (0.0247 V) in unit 2. This work clearly verified the process of voltage reversal in the stacked MFC. As the current was gradually increased in the stacked MFC, the voltage in the stacked unit 1 decreased to 0 V prior to that of the stacked unit 2. Then, when the voltage in unit 1 became 0 V, it was converted from a galvanic cell to an electrochemical cell powered by unit 2. We found that the stacked unit 2 provided electrical energy for the stacked unit 1 as a power supply. Finally, the anode potential of the stacked unit 1 significantly increased over cathode potential as current increased further, which caused voltage reversal in unit 1. Voltage reversal occurs in stacked MFCs as a result of non-spontaneous anode overpotential in a unit MFC that has sluggish anode kinetics compared to the other unit MFCs. PMID:24771553

  15. Fade to Green: A Biodegradable Stack of Microbial Fuel Cells.

    Science.gov (United States)

    Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Stinchcombe, Andrew; Walter, X Alexis; Greenman, John; Ieropoulos, Ioannis

    2015-08-24

    The focus of this study is the development of biodegradable microbial fuel cells (MFCs) able to produce useful power. Reactors with an 8 mL chamber volume were designed using all biodegradable products: polylactic acid for the frames, natural rubber as the cation-exchange membrane and egg-based, open-to-air cathodes coated with a lanolin gas diffusion layer. Forty MFCs were operated in various configurations. When fed with urine, the biodegradable stack was able to power appliances and was still operational after six months. One useful application for this truly sustainable MFC technology includes onboard power supplies for biodegradable robotic systems. After operation in remote ecological locations, these could degrade harmlessly into the surroundings to leave no trace when the mission is complete. PMID:26212495

  16. Recent Progress and Spectral Robustness Study for Mechanically Stacked Multi-junction Solar Cells

    Science.gov (United States)

    Zhao, Lu; Flamand, Giovanni; Poortmans, Jef

    2010-10-01

    Multi-terminal mechanically stacked multi-junction solar cells are an attractive candidate for terrestrial concentrator photovoltaics applications. Unlike monolithically integrated multi-junction solar cells which require current matching, all the available photon currents can be fully extracted from each junction of a mechanically stacked solar cell. Therefore, it has a high performance potential, and more importantly is less sensitive to spectrum variations. Lower losses due to current mismatch translate into a higher annual energy output for the mechanical stack. This paper presents the baseline processing developed at imec for the mechanical stacking process, and the most recent cell results by means of this technology. A GaAs-Ge dual-junction mechanically stacked multi-junction solar cell is demonstrated, with 24.7% plus 2.52% under AM1.5g, and 27.7% plus 4.42% under 30Suns concentration. In addition, spectral sensitivity is studied for both monolithically stacked and mechanically stacked solar cells, to learn the influence of spectrum variations on multi-junction solar cell performance. SMARTS model is used to predict the spectral irradiances, with solar radiation and meteorological elements from typical meteorological year 3 (TMY3) data set. The generated spectra are then fed into TCAD numerical simulation tool, to simulate the device performance. The simulation results show a reduced spectral sensitivity for mechanically stacked cell, and there is a 6% relative gain in annual energy production for the site studied (Las Vegas), compared with the monolithic stack.

  17. Documentation of Short Stack and Button Cell Experiments Performed at INL and Ceramatec during FY07

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots; J. J. Hartvigsen; J. S. Herring

    2007-09-01

    This report provides documentation of experimental research activities performed at the Idaho National Laboratory and at Ceramatec, Inc. during FY07 under the DOE Nuclear Hydrogen Initiative, High Temperature Electrolysis Program. The activities discussed in this report include tests on single (button) cells, short planar stacks and tubular cells. The objectives of these small-scale tests are to evaluate advanced electrode, electrolyte, and interconnect materials, alternate modes of operation (e.g., coelectrolysis), and alternate cell geometries over a broad range of operating conditions, with the aim of identifying the most promising material et, cell and stack geometry, and operating conditions for the high-temperature electrolysis application. Cell performance is characterized in erms of initial area-specific resistance and long-term stability in the electrolysis mode. Some of the tests were run in the coelectrolysis mode. Research into coelectrolysis was funded by Laboratory Directed Research and Development (LDRD). Coelectrolysis simultaneously converts steam to hydrogen and carbon dioxide to carbon monoxide. This process is complicated by the reverse shift reaction. An equilibrium model was developed to predict outlet compositions of steam, hydrogen, carbon dioxide, and carbon monoxide resulting from coelectrolysis. Predicted ompositions were compared to measurements obtained with a precision micro-channel gas chromatograph.

  18. Improved solid oxide fuel cell stacks: Power density, durability and modularity. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Lund Frandsen, H.; Kiebach, W.R.; Hoeegh, J. (Technical Univ. of Denmark. Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)) (and others)

    2010-10-15

    This report presents the work performed within the project PSO2009-1-10207 during the period from 01-04-2009 - 31-06-2010. The report is divided into three parts covering the three work packages: Stack components; Stacks and durability; and Large SOFC systems: modularity and scalability. The project contains 38 milestones and all milestones in the project have been either fully or partly fulfilled. Two major achievements within this project concern the robustness towards dynamic operations and implementation of cells with more active cathodes: Within this project tools to evaluate and test SOFC stacks with respect to robustness during dynamic operations has been developed. From stack tests performed under dynamic conditions it was observed that the effect on degradation and failure seemed to be very little. The thermo-mechanical models developed in this project in combination with the dynamic stack model was used in combination to understand why. The results clearly showed that the hardest stress field applied to the cells arises from the steady state operating point rather than from the dynamic conditions. This is a very promising result concerning the fact that especially small CHP units in a commercial system will experience dynamic conditions from load cycling and thermal cycling. A new type of cell with a more active cathode has been formulated and introduced into the TOFC stacks in this project. The aim was to improve the effect of the stack by 25 %. However, compared to a standard stack with the ''old'' cells, the stack effect was increased by 44% - from a cross flow stack with standard 2G cells to a cross flow stack with 2.5G cells. The new type of cells also show an excellent stability towards moisture in the cathode feed, and a stack with 2.5G cells has been tested for 12.000 hrs with a degradation rate of 30 mOMEGAcm2/1000 hr. (Author)

  19. A double-fuzzy diagnostic methodology dedicated to online fault diagnosis of proton exchange membrane fuel cell stacks

    Science.gov (United States)

    Zheng, Zhixue; Péra, Marie-Cécile; Hissel, Daniel; Becherif, Mohamed; Agbli, Kréhi-Serge; Li, Yongdong

    2014-12-01

    To improve the performance and lifetime of the low temperature polymer electrolyte membrane fuel cell (PEMFC) stack, water management is an important issue. This paper aims at developing an online diagnostic methodology with the capability of discriminating different degrees of flooding/drying inside the fuel cell stack. Electrochemical impedance spectroscopy (EIS) is utilized as a basis tool and a double-fuzzy method consisting of fuzzy clustering and fuzzy logic is developed to mine diagnostic rules from the experimental data automatically. Through online experimental verification, a high interpretability and computational efficiency of the proposed methodology can be achieved.

  20. Thermal modeling and temperature control of a PEM fuel cell system for forklift applications

    DEFF Research Database (Denmark)

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

    2014-01-01

    Temperature changes in PEM fuel cell stacks are considerably higher during load variations and have a negative impact as they generate thermal stresses and stack degradation. Cell hydration is also of vital importance in fuel cells and it is strongly dependent on operating temperature. A combinat......Temperature changes in PEM fuel cell stacks are considerably higher during load variations and have a negative impact as they generate thermal stresses and stack degradation. Cell hydration is also of vital importance in fuel cells and it is strongly dependent on operating temperature. A...... combination of high temperature and reduced humidity increases the degradation rate. Stack thermal management and control are, thus, crucial issues in PEM fuel cell systems especially in automotive applications such as forklifts. In this paper we present a control–oriented dynamic model of a liquid–cooled PEM...... designers in choosing the required coolant mass flow rate and radiator size to minimize the stack temperature gradients....

  1. Cell and stack design alternatives. Second quarterly report, November 1, 1978-January 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-02-14

    Progress on a program to develop commercially viable phosphoric acid fuel cell driven on-site integration energy systems is presented. A mass and energy balance was completed for one operating point of a selected power generation sub-system with a power output of 119 kW. Potentially, 87% of the LHV of the input fuel is available as bus bar electricity or useful heat. A 2 kW stack of conventional design and a 0.5 kW DIGAS cooled stack have been constructed and are on test at ERC. Renovation of a space for the Westinghouse stack test facility is underway and procurement of equipment has been initiated. The coupled cell temperature - current density analysis has been modified to include the effects of turbulent coolant flow and extended to permit analysis of up to 10 process plates between cooling plates. The REFORM computer program was verified by comparison with data received from the government project manager. A method for predicting carbon deposition was developed and compared with data from the literature.

  2. Cell and stack design alternatives. Second quarterly report, November 1, 1978-January 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Hoover, D.Q.

    1979-02-14

    Work on the design of an on-site fuel cell total energy system for an apartment building is described. A mass and energy balance was completed for one operating point of a selected power generation sub-system with a power output of 119 kW. Potentially, 87 percent of the LHV of the input fuel is available as bus bar electricity or useful heat. A 2 kW stack of conventional design and a 0.5 kW DIGAS cooled stack have been constructed and are on test at ERC. Renovation of a space for the Westinghouse stack test facility is underway and procurement of equipment has been initiated. The coupled cell temperature - current density analysis has been modified to include the effects of turbulent coolant flow and extended to permit analysis of up to 10 process plates between cooling plates. The REFORM computer program was verified by comparison with data received from the government project manager. A method for predicting carbon deposition was developed and compared with data from the literature.

  3. High Temperature Co‐Electrolysis of Steam and CO2 in an SOC Stack: Performance and Durability

    DEFF Research Database (Denmark)

    Chen, Ming; Høgh, Jens Valdemar Thorvald; Nielsen, J. U.;

    2013-01-01

    In this work, co‐electrolysis of steam and carbon dioxide was studied in a Topsoe Fuel Cell (TOFC®) 10‐cell stack, containing three different types of Ni/yttria stabilized zirconia (YSZ) electrode supported solid oxide electrolysis cells with a footprint of 12 × 12 cm. The stack was operated at 8...

  4. Fabrication of highly porous LSM/CGO cell stacks for electrochemical flue gas purification

    DEFF Research Database (Denmark)

    Andersen, Kjeld Bøhm; Bræstrup, Frantz Radzik; Kammer Hansen, Kent

    2013-01-01

    In this study porous cell stacks for electrochemical flue gas purification were fabricated using tape casting and lamination followed by sintering. Two different mixtures of pore formers were used; either a mixture of two types of graphite or a mixture of graphite with polymethyl methacrylate micro......-particles. It was shown that the porous cell stacks fabricated with polymethyl methacrylate had a higher porosity but a similar back pressure compared to the porous cell stacks fabricated with only graphite as a pore former. This was due to a high back pressure of the electrolyte layer. The porous cell stacks...... polymethyl methacrylate pore former, especially in the electrolyte layer, is needed, in order to lower the back pressure of the porous cell stack....

  5. Continued maturing of SOFC cell production technology and development and demonstration of SOFC stacks. Final report

    Energy Technology Data Exchange (ETDEWEB)

    2008-08-15

    The overall objective of the 6385 project was to develop stack materials, components and stack technology including industrial relevant manufacturing methods for cells components and stacks. Furthermore, the project should include testing and demonstration of the stacks under relevant operating conditions. A production of 6.829 cells, twenty 75-cell stacks and a number of small stacks was achieved. Major improvements were also made in the manufacturing methods and in stack design. Two test and demonstration activities were included in the project. The first test unit was established at H.C. OErsted power plant at the Copenhagen waterfront in order to perform test of SOFC stacks. The unit will be used for tests in other projects. The second demonstration unit is the alpha prototype demonstration in a system running on natural gas in Finland. The alpha prototype demonstration system with 24 TOFC (Topsoe Fuel Cell) stacks was established and started running in October 2007 and operational experience was gained in the period from October 2007 to February 2008. (auther)

  6. Development and testing of a hybrid system with a sub-kW open-cathode type PEM (proton exchange membrane) fuel cell stack

    International Nuclear Information System (INIS)

    In this study, the performance of a polymer electrolyte membrane fuel cell stack has been evaluated for a hybrid power system test platform. To simulate vehicle acceleration, the stack was operated under dynamic-loading, and to demonstrate the exchange of power flow between two power sources the hybrid power system was tested under three different modes. A unit cell was fabricated for high stack performance and the stack was constructed with 18 open-cathode type fuel cells. Air which acts as a coolant as well as an oxidant for electrochemical reactions is provided by a pair of fans. The capabilities of the stack for hybrid power system test platform were validated by successful dynamic-loading tests. The performance of the stack for various air fan voltage was evaluated and an optimal value was concluded. The conditions like inlet temperature of H2 and the stack current were established for maximum power. It was also found that humidification of hydrogen at anode inlet degrades the stack performance and stability due to flooding. Evidence shows that for the higher overall performance, the fuel cell acts continuously on constant current output. The study contributes to the design of mobility hybrid system to get better performance and reliability. - Highlights: • An open-cathode type PEMFC (polymer electrolyte membrane fuel cell) stack (rated output 300 W) was fabricated. • The open-cathode configuration simplifies the design of a stack system. • Assess the feasibility of combining a fuel cell stack in a hybrid system. • The study contributes to the design of mobility hybrid system to get better performance and reliability

  7. Development of a polymer electrolyte membrane fuel cell stack for an underwater vehicle

    Science.gov (United States)

    Han, In-Su; Kho, Back-Kyun; Cho, Sungbaek

    2016-02-01

    This paper presents a polymer electrolyte membrane (PEM) fuel cell stack that is specifically designed for the propulsion of an underwater vehicle (UV). The stack for a UV must be continuously operated in a closed space using hydrogen and pure oxygen; it should meet various performance requirements such as high hydrogen and oxygen utilizations, low hydrogen and oxygen consumptions, a high ramp-up rate, and a long lifetime. To this end, a cascade-type stack design is employed and the cell components, including the membrane electrode assembly and bipolar plate, are evaluated using long-term performance tests. The feasibility of a fabricated 4-kW-class stack was confirmed through various performance evaluations. The proposed cascade-type stack exhibited a high efficiency of 65% and high hydrogen and oxygen utilizations of 99.89% and 99.68%, respectively, resulting in significantly lesser purge-gas emissions to the outside of the stack. The load-following test was successfully performed at a high ramp-up rate. The lifetime of the stack was confirmed by a 3500-h performance test, from which the degradation rate of the cell voltage was obtained. The advantages of the cascade-type stack were also confirmed by comparing its performance with that of a single-stage stack operating in dead-end mode.

  8. Cell and stack design alternatives. First quarterly report, August 1, 1978-October 31, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Hoover, D.Q.

    1979-01-01

    An apartment house in Albany, New York with HUD minimum insulation was selected as the application to be used in evaluating various system configurations of on-site fuel cell total energy systems. Methods for calculating the static and dynamic thermal loads for a simulated season were developed. Computer models of some major subsystems are now being developed. Finite element models of the electrochemistry, thermodynamics and heat transfer relationships for fuel cells were developed and have been used to calculate current density and temperature distributions for sets of large cells and cooling plates. The results obtained led to several innovative ideas for advanced stack designs. A single lump model of a fuel cell stack was developed for use in the systems study. The available information on methane conditioning was collected and reviewed and a plan for attaining the missing design data has been developed. Simple models of reformer and water-gas shift reactors were developed for use in the systems study. The lines of communication among technical tasks were established, required documentation of plans and progress was prepared and delivered and the monthly review meetings were held as planned.

  9. Cell separator for use in bipolar-stack energy storage devices

    Science.gov (United States)

    Mayer, Steven T.; Feikert, John H.; Kachmitter, James L.; Pekala, Richard W.

    1995-01-01

    An improved multi-cell electrochemical energy storage device, such as a battery, fuel cell, or double layer capacitor using a cell separator which allows cells to be stacked and interconnected with low electrical resistance and high reliability while maximizing packaging efficiency. By adding repeating cells, higher voltages can be obtained. The cell separator is formed by applying an organic adhesive on opposing surfaces of adjacent carbon electrodes or surfaces of aerogel electrodes of a pair of adjacent cells prior to or after pyrolysis thereof to form carbon aerogel electrodes. The cell separator is electronically conductive, but ionically isolating, preventing an electrolytic conduction path between adjacent cells in the stack.

  10. LINEARITY AND ANALOG PERFORMANCE ANALYSIS OF DOUBLE GATE TUNNEL FET: EFFECT OF TEMPERATURE AND GATE STACK

    Directory of Open Access Journals (Sweden)

    Rakhi Narang

    2011-09-01

    Full Text Available The linearity and analog performance of a Silicon Double Gate Tunnel Field Effect Transistor (DG-TFETis investigated and the impact of elevated temperature on the device performance degradation has been studied. The impact on the device performance due to the rise in temperature and a gate stack (GSarchitecture has also been investigated for the case of Silicon DG-MOSFET and a comparison with DGTFET is made. The parameters governing the analog performance and linearity have been studied, and high frequency simulations are carried out to determine the cut-off frequency of the device and its temperature dependence.

  11. Cooling Performance Characteristics of the Stack Thermal Management System for Fuel Cell Electric Vehicles under Actual Driving Conditions

    Directory of Open Access Journals (Sweden)

    Ho-Seong Lee

    2016-04-01

    Full Text Available The cooling performance of the stack radiator of a fuel cell electric vehicle was evaluated under various actual road driving conditions, such as highway and uphill travel. The thermal stability was then optimized, thereby ensuring stable operation of the stack thermal management system. The coolant inlet temperature of the radiator in the highway mode was lower than that associated with the uphill mode because the corresponding frontal air velocity was higher than obtained in the uphill mode. In both the highway and uphill modes, the coolant temperatures of the radiator, operated under actual road driving conditions, were lower than the allowable limit (80 °C; this is the maximum temperature at which stable operation of the stack thermal management system of the fuel cell electric vehicle could be maintained. Furthermore, under actual road driving conditions in uphill mode, the initial temperature difference (ITD between the coolant temperature and air temperature of the system was higher than that associated with the highway mode; this higher ITD occurred even though the thermal load of the system in uphill mode was greater than that corresponding to the highway mode. Since the coolant inlet temperature is expected to exceed the allowable limit (80 °C in uphill mode under higher ambient temperature with air conditioning system operation, the FEM design layout should be modified to improve the heat capacity. In addition, the overall volume of the stack cooling radiator is 52.2% higher than that of the present model and the coolant inlet temperature of the improved radiator is 22.7% lower than that of the present model.

  12. Consideration of Numerical Simulation Parameters and Heat Transfer Models for a Molten Carbonate Fuel Cell Stack

    Energy Technology Data Exchange (ETDEWEB)

    Koh, J.H.; Seo, H.K.; Lim, H.C. [Korea Electric Power Research Institute, Taejon (Korea)

    2001-07-01

    A fuel cell stack model based on differential heat balance equations was solved numerically with a computational fluid dynamics code. Theoretical aspects in the simulation of a molten carbonate fuel cell (MCFC) performance model were discussed with regard to numerical accuracy of temperature prediction. The effect of grid setting for gas channel depth was studied to ensure how coarse it can be. A single computational element was sufficient for temperature prediction, while more grid elements are required for calculation of flow field and pressure distribution. The use of constant velocities is not recommended because it cannot account for the change of linear velocity within fuel cells, indicating the momentum equations have to be solved together with the heat balance equations. Thermal radiation has little effect on calculation of temperature field from the model. Gas properties vary within fuel cells, but most of them can be treated constant except for specific heat capacity of anode gas. Convection heat transfer by anode gas can be overestimated when a constant specific heat capacity is used, resulting in prediction of lower temperature curves. (author). 18 refs., 12 figs., 4 tabs.

  13. Series assembly of microbial desalination cells containing stacked electrodialysis cells for partial or complete seawater desalination.

    Science.gov (United States)

    Kim, Younggy; Logan, Bruce E

    2011-07-01

    A microbial desalination cell (MDC) is a new approach for desalinating water based on using the electrical current generated by exoelectrogenic bacteria. Previously developed MDCs have used only one or two desalination chambers with substantial internal resistance, and used low salinity catholytes containing a buffered or acid solution. Here we show that substantially improved MDC performance can be obtained even with a nonbuffered, saline catholyte, by using an electrodialysis stack consisting of 5 pairs of desalting and concentrating cells. When 4 stacked MDCs were used in series (20 total pairs of desalination chambers), the salinity of 0.06 L of synthetic seawater (35 g/L NaCl) was reduced by 44% using 0.12 L of anode solution (2:1). The resistive loss in the electrodialysis stack was negligible due to minimization of the intermembrane distances, and therefore the power densities produced by the MDC were similar to those produced by single chamber microbial fuel cells (MFCs) lacking desalination chambers. The observed current efficiency was 86%, indicating separation of 4.3 pairs of sodium and chloride ions for every electron transferred through the circuit. With two additional stages (total of 3.8 L of anolyte), desalination was increased to 98% salt removal, producing 0.3 L of fresh water (12.6:1). These results demonstrate that stacked MDCs can be used for efficient desalination of seawater while at the same time achieving power densities comparable to those obtained in MFCs. PMID:21671676

  14. Series Assembly of Microbial Desalination Cells Containing Stacked Electrodialysis Cells for Partial or Complete Seawater Desalination

    KAUST Repository

    Kim, Younggy

    2011-07-01

    A microbial desalination cell (MDC) is a new approach for desalinating water based on using the electrical current generated by exoelectrogenic bacteria. Previously developed MDCs have used only one or two desalination chambers with substantial internal resistance, and used low salinity catholytes containing a buffered or acid solution. Here we show that substantially improved MDC performance can be obtained even with a nonbuffered, saline catholyte, by using an electrodialysis stack consisting of 5 pairs of desalting and concentrating cells. When 4 stacked MDCs were used in series (20 total pairs of desalination chambers), the salinity of 0.06 L of synthetic seawater (35 g/L NaCl) was reduced by 44% using 0.12 L of anode solution (2:1). The resistive loss in the electrodialysis stack was negligible due to minimization of the intermembrane distances, and therefore the power densities produced by the MDC were similar to those produced by single chamber microbial fuel cells (MFCs) lacking desalination chambers. The observed current efficiency was 86%, indicating separation of 4.3 pairs of sodium and chloride ions for every electron transferred through the circuit. With two additional stages (total of 3.8 L of anolyte), desalination was increased to 98% salt removal, producing 0.3 L of fresh water (12.6:1). These results demonstrate that stacked MDCs can be used for efficient desalination of seawater while at the same time achieving power densities comparable to those obtained in MFCs. © 2011 American Chemical Society.

  15. Correlating variability of modeling parameters with non-isothermal stack performance: Monte Carlo simulation of a portable 3D planar solid oxide fuel cell stack

    International Nuclear Information System (INIS)

    Highlights: • A Monte Carlo simulation of a SOFC stack model is conducted for sensitivity analysis. • The non-isothermal stack model allows fast computation for statistical modeling. • Modeling parameters are ranked in view of their correlations with stack performance. • Rankings are different when varying the parameters simultaneously and individually. • Rankings change with the variability of the parameters and positions in the stack. - Abstract: The development of fuel cells has progressed to portable applications recently. This paper conducts a Monte Carlo simulation (MCS) of a spatially-smoothed non-isothermal model to correlate the performance of a 3D 5-cell planar solid oxide fuel cell (P-SOFC) stack with the variability of modeling parameters regarding material and geometrical properties and operating conditions. The computationally cost-efficient P-SOFC model for the MCS captures the leading-order transport phenomena and electrochemical mechanics of the 3D stack. Sensitivity analysis is carried out in two scenarios: first, by varying modeling parameters individually, and second by varying them simultaneously. The stochastic parameters are ranked according to the strength of their correlations with global and local stack performances. As a result, different rankings are obtained for the two scenarios. Moreover, in the second scenario, the rankings change with the nominal values and variability of the stochastic parameters as well as local positions within the stack, because of compensating or reinforcing effects between the varying parameters. Apart from the P-SOFCs, the present MCS can be extended to other types of fuel cells equipped with parallel flow channels. The fast stack model allows statistical modeling of a large stack of hundreds of cells for high-power applications without a prohibitive computational cost

  16. Experimental study on the influence of the porosity of parallel plate stack on the temperature decrease of a thermoacoustic refrigerator

    International Nuclear Information System (INIS)

    Thermoacoustic refrigerators are cooling devices which are environmentally friendly because they don't use hazardous gases like chlorofuorocarbons (CFCs) or hydrofuorocarbons (HFCs) but rather air or inert gases as working medium. They apply sound wave with high intensity to pump heat from the cold to hot the regions through a stack in a resonator tube. One of the important parameters of thermoacoustic refrigerators is the porosity (blockage ratio) of stack which is a fraction of cross sectional area of the resonator unblocked for the gas movement by the stack. This paper describes an experimental study on how the porosity of parallel plate stack affects the temperature decrease of a thermoacoustic refrigerator. The porosity of parallel plate stack is specified by the thickness of plates and the spacing between plates. We measured the maximum temperature decreases of thermacoustic refrigerator using stacks with various porosities in the range of 0.5 – 0.85, with plate spacing from 0.5 mm to 1.5 mm and plate thicknesses 0.3 mm, 0.4 mm, and 0.5 mm. The measurements were done with two resonators with length of 0.8 m and 1.0 m, with air at atmospheric pressure and room temperature, correspond to thermal penetration depths (δκ) of 0.26 mm and 0.29 mm, respectively. It was found that there is an optimum porosity which gives the largest temperature decreases, and there is a tendency that the optimum porosity shifts to a larger value and the temperature decrease become larger when we used a stack with thinner plates. On the other hand, the study on the dependence of the temperature decrease on the plate thickness and the plate spacing reveals more useful information than that on the stack porosity itself. We found that stack with thinner plates tends to give larger temperature decrease, and the plate spacing of around 4δκ leads to the largest temperature decrease.

  17. Development of internal manifold heat exchanger (IMHEX reg-sign) molten carbonate fuel cell stacks

    International Nuclear Information System (INIS)

    The Institute of Gas Technology (IGT) has been in the forefront of molten carbonate fuel cell (MCFC) development for over 25 years. Numerous cell designs have been tested and extensive tests have been performed on a variety of gas manifolding alternatives for cells and stacks. Based upon the results of these performance tests, IGT's development efforts started focusing on an internal gas manifolding concept. This work, initiated in 1988, is known today as the IMHEX reg-sign concept. MCP has developed a comprehensive commercialization program loading to the sale of commercial units in 1996. MCP's role is in the manufacture of stack components, stack assembly, MCFC subsystem testing, and the design, marketing and construction of MCFC power plants. Numerous subscale (1 ft2) stacks have been operated containing between 3 and 70 cells. These tests verified and demonstrated the viability of internal manifolding from technical (no carbonate pumping), engineering (relaxed part dimensional tolerance requirements), and operational (good gas sealing) aspects. Simplified fabrication, ease of assembly, the elimination of external manifolds and all associated clamping requirements has significantly lowered anticipated stack costs. Ongoing 1 ft2 stack testing is generating performance and endurance characteristics as a function of system specified operating conditions. Commercial-sized, full-area stacks (10 ft2) are in the process of being assembled and will be tested in November. This paper will review the recent developments the MCFC scale-up and manufacture work of MCP, and the research and development efforts of IGT which support those efforts. 17 figs

  18. Low temperature sol-gel metal oxide and fluoride layer stacks for optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, H., E-mail: hannes.krueger@bam.d [Institut fuer Chemie, Humboldt-Universitaet zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin (Germany); BAM - Federal Institute for Materials Research and Testing, Division VI.4 Surface Technologies, Unter den Eichen 87, D-12205 Berlin (Germany); Hertwig, A., E-mail: andreas.hertwig@bam.d [BAM - Federal Institute for Materials Research and Testing, Division VI.4 Surface Technologies, Unter den Eichen 87, D-12205 Berlin (Germany); Beck, U., E-mail: uwe.beck@bam.d [BAM - Federal Institute for Materials Research and Testing, Division VI.4 Surface Technologies, Unter den Eichen 87, D-12205 Berlin (Germany); Kemnitz, E., E-mail: erhard.kemnitz@chemie.hu-berlin.d [Institut fuer Chemie, Humboldt-Universitaet zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin (Germany)

    2010-08-31

    MgF{sub 2} and TiO{sub 2} single layers and layer stacks were produced by a spin-coating sol-gel process. The final temperature treatment was carried out at 100 {sup o}C. The layers were deposited onto silicon and fused silica substrates and were analysed by means of atomic force microscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, ellipsometry, and UV-vis transmission spectroscopy. MgF{sub 2} and TiO{sub 2} single layers have morphological and optical properties comparable with physical vapour deposited layers. By using spectroscopic mapping ellipsometry, a good inter- and intra-sample homogeneity was confirmed. Multiple deposition steps result in a linear increase of layer thickness. Various films were deposited with thicknesses between 25 nm and 350 nm. It was shown that the low temperature sol-gel process results in films of optical quality. Anti-reflective and high reflective layer stacks consisting of MgF{sub 2} and TiO{sub 2} were designed and can be produced now by a sol-gel process, whereas the MgF{sub 2} layers in the layer stacks contains also traces of MgF{sub 2-2x}O{sub x}.

  19. LINEARITY AND ANALOG PERFORMANCE ANALYSIS OF DOUBLE GATE TUNNEL FET: EFFECT OF TEMPERATURE AND GATE STACK

    Directory of Open Access Journals (Sweden)

    RAKHI NARANG

    2011-10-01

    Full Text Available The linearity and analog performance of a Silicon Double Gate Tunnel Field Effect Transistor (DG-TFETis investigated and the impact of elevated temperature on the device performance degradation has beenstudied. The impact on the device performance due to the rise in temperature and a gate stack (GSarchitecture has also been investigated for the case of Silicon DG-MOSFET and a comparison with DGTFETis made. The parameters governing the analog performance and linearity have been studied, andhigh frequency simulations are carried out to determine the cut-off frequency of the device and itstemperature dependence.

  20. Dynamics of dislocation interactions with stacking-fault tetrahedra at high temperature

    International Nuclear Information System (INIS)

    The interaction process between dislocations and large stacking-fault tetrahedra was observed in real time at high temperature during deformation experiments in situ in the transmission electron microscope. Dislocation interactions with tetrahedra resulted in them being annihilated and converted to another defect type. Dislocation bypass of the tetrahedra occurred by cross-slip. The latter interaction occurred slowly and halted the progress of the dislocation. Annihilation versus bypass by dislocation cross-slip was dictated by the location at which the slip plane intersected the tetrahedron – on the face or along the edges with the stair-rod dislocations. In general, the interactions, at best, were weakly temperature dependent

  1. Dynamics of dislocation interactions with stacking-fault tetrahedra at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Briceño, M.; Kacher, J. [Department of Materials Science and Engineering, University of Illinois, 1304 W. Green St., Urbana, IL 61801 (United States); Robertson, I.M., E-mail: ianr@illinois.edu [Department of Materials Science and Engineering, University of Illinois, 1304 W. Green St., Urbana, IL 61801 (United States)

    2013-02-15

    The interaction process between dislocations and large stacking-fault tetrahedra was observed in real time at high temperature during deformation experiments in situ in the transmission electron microscope. Dislocation interactions with tetrahedra resulted in them being annihilated and converted to another defect type. Dislocation bypass of the tetrahedra occurred by cross-slip. The latter interaction occurred slowly and halted the progress of the dislocation. Annihilation versus bypass by dislocation cross-slip was dictated by the location at which the slip plane intersected the tetrahedron – on the face or along the edges with the stair-rod dislocations. In general, the interactions, at best, were weakly temperature dependent.

  2. Dynamics of dislocation interactions with stacking-fault tetrahedra at high temperature

    Science.gov (United States)

    Briceño, M.; Kacher, J.; Robertson, I. M.

    2013-02-01

    The interaction process between dislocations and large stacking-fault tetrahedra was observed in real time at high temperature during deformation experiments in situ in the transmission electron microscope. Dislocation interactions with tetrahedra resulted in them being annihilated and converted to another defect type. Dislocation bypass of the tetrahedra occurred by cross-slip. The latter interaction occurred slowly and halted the progress of the dislocation. Annihilation versus bypass by dislocation cross-slip was dictated by the location at which the slip plane intersected the tetrahedron - on the face or along the edges with the stair-rod dislocations. In general, the interactions, at best, were weakly temperature dependent.

  3. Design, fabrication and performance test of a planar array module-type micro fuel cell stack

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A new and novel planar array module. • Easy handling/assembling as well as fast fabrication upon its commercialization. • Compact configuration design and geometry could be secured. - Abstract: We proposed and tested a new and novel planar array module (4 N style; N is an integer) consisting of 4, 8, 12 and 16 single polymer electrotype membrane (PEM) fuel cells connected in series on a plane with two different pin electrode flowfield configurations. This module has the potential to be not only easily handled and assembled but also to be fabricated quickly upon its commercialization. Using a Lithography Galvanic Abformung (LIGA)-like microfabrication technique, copper metal sheets were used to make two different flowfield plates with serpentine flow channels. A 4-cell (short stack), 8-cell, 12-cell and 16-cell (long stack) stack were developed and tested for performance study under different operating conditions. These were connected in a series of micro fuel cells consisting of an anode/cathode and Membrane Electrode Assembly (MEA). Performance results for a short stack/unit module (4 cells), 8 cells, 12 cells and a long stack/four modules (16 cells) were presented; it was found that significant improvements in VI/PI characteristics could be attained due to uniform and compact configuration design and geometry

  4. Improved electrochemical in-situ characterization of polymer electrolyte membrane fuel cell stacks

    Science.gov (United States)

    Hartung, I.; Kirsch, S.; Zihrul, P.; Müller, O.; von Unwerth, T.

    2016-03-01

    In-situ diagnostics for single polymer electrolyte membrane fuel cells are well known and established. Comparable stack level techniques are urgently needed to enhance the understanding of degradation during real system operation, but have not yet reached a similar level of sophistication. We have therefore developed a new method for the quantification of the hydrogen crossover current in stacks, which in combination with a previously published technique now allows a clear quantitative characterization of the individual cells' membranes and electrodes. The limits of the reported methods are theoretically assessed and application is then demonstrated on automotive short stacks. The results prove to be highly reproducible and are validated for individual cells of the respective stacks by direct comparison with cyclic voltammetry results, showing good quantitative agreement for the hydrogen crossover current, the double layer capacitance and the electrochemically active surface area.

  5. A polymer electrolyte fuel cell stack for stationary power generation from hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Zawodzinski, C.; Wilson, M.; Gottesfeld, S. [Los Alamos National Lab., NM (United States)

    1996-10-01

    The fuel cell is the most efficient device for the conversion of hydrogen fuel to electric power. As such, the fuel cell represents a key element in efforts to demonstrate and implement hydrogen fuel utilization for electric power generation. A central objective of a LANL/Industry collaborative effort supported by the Hydrogen Program is to integrate PEM fuel cell and novel stack designs at LANL with stack technology of H-Power Corporation (H-Power) in order to develop a manufacturable, low-cost/high-performance hydrogen/air fuel cell stack for stationary generation of electric power. A LANL/H-Power CRADA includes Tasks ranging from exchange, testing and optimization of membrane-electrode assemblies of large areas, development and demonstration of manufacturable flow field, backing and bipolar plate components, and testing of stacks at the 3-5 cell level and, finally, at the 4-5 kW level. The stack should demonstrate the basic features of manufacturability, overall low cost and high energy conversion efficiency. Plans for future work are to continue the CRADA work along the time line defined in a two-year program, to continue the LANL activities of developing and testing stainless steel hardware for longer term stability including testing in a stack, and to further enhance air cathode performance to achieve higher energy conversion efficiencies as required for stationary power application.

  6. Solid oxide fuel cells SOFCRoll single cell and stack design and development

    OpenAIRE

    Tesfai, Alem T.

    2013-01-01

    This study has focused on the implementation of a stack system for a novel design of solid oxide fuel cell (SOFCRoll). The issues affecting the commercialization of SOFCs are mainly based on durability and cost. The new design offers a number of advantages over the existing designs; it seeks to retain the specific advantages of both the tubular (high unit strength, no sealing problems) and planar arrangements (high power density). This design also aims to achieve low manufac...

  7. A polymer electrolyte fuel cell stack for stationary power generation from hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.S.; Moeller-Holst, S.; Webb, D.M.; Zawodzinski, C.; Gottesfeld, S. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

    1998-08-01

    The objective is to develop and demonstrate a 4 kW, hydrogen-fueled polymer electrolyte fuel cell (PEFC) stack, based on non-machined stainless steel hardware and on membrane/electrode assemblies (MEAs) of low catalyst loadings. The stack is designed to operate at ambient pressure on the air-side and can accommodate operation at higher fuel pressures, if so required. This is to be accomplished by working jointly with a fuel cell stack manufacturer, based on a CRADA. The performance goals are 57% energy conversion efficiency hydrogen-to-electricity (DC) at a power density of 0.9 kW/liter for a stack operating at ambient inlet pressures. The cost goal is $600/kW, based on present materials costs.

  8. The Role of Temperature and Magnetic Effects on the Stacking-fault Energy in Austenitic Iron

    CERN Document Server

    Hashemi, Seyed Arsalan; Gholizadeh, Hojjat; Hashemifar, Seyed Javad

    2015-01-01

    We have investigated the role of temperature and magnetic effects on the stacking-fault energy (SFE) in pure austenitic iron based on Density Functional Theory (DFT) calculations. Using the axial next-nearest-neighbor Ising (ANNNI) model, the SFE is expanded in terms of the free energiesof bulk with face-centered cubic (fcc), hexagonal close-packed (hcp), and double-hcp (dhcp) structures. The free-energy calculations require the lattice constant and the local magnetic moments at various temperatures. The earlier is obtained from the available experimental data, while the later is calculated by accounting for the thermal magnetic excitations using the Monte-Carlo tech- niques. Our results demonstrate a strong dependence of the SFE on the magnetic effects in pure iron. Moreover, we found that the SFE increases with temperature.

  9. Optimized scalable stack of fluorescent solar concentrator systems with bifacial silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Martínez Díez, Ana Luisa, E-mail: a.martinez@itma.es [Fundación ITMA, Parque Empresarial Principado de Asturias, C/Calafates, Parcela L-3.4, 33417 Avilés (Spain); Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg (Germany); Gutmann, Johannes; Posdziech, Janina; Rist, Tim; Goldschmidt, Jan Christoph [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg (Germany); Plaza, David Gómez [Fundación ITMA, Parque Empresarial Principado de Asturias, C/Calafates, Parcela L-3.4, 33417 Avilés (Spain)

    2014-10-21

    In this paper, we present a concentrator system based on a stack of fluorescent concentrators (FCs) and a bifacial solar cell. Coupling bifacial solar cells to a stack of FCs increases the performance of the system and preserves its efficiency when scaled. We used an approach to optimize a fluorescent solar concentrator system design based on a stack of multiple fluorescent concentrators (FC). Seven individual fluorescent collectors (20 mm×20 mm×2 mm) were realized by in-situ polymerization and optically characterized in regard to their ability to guide light to the edges. Then, an optimization procedure based on the experimental data of the individual FCs was carried out to determine the stack configuration that maximizes the total number of photons leaving edges. Finally, two fluorescent concentrator systems were realized by attaching bifacial silicon solar cells to the optimized FC stacks: a conventional system, where FC were attached to one side of the solar cell as a reference, and the proposed bifacial configuration. It was found that for the same overall FC area, the bifacial configuration increases the short-circuit current by a factor of 2.2, which is also in agreement with theoretical considerations.

  10. Optimized scalable stack of fluorescent solar concentrator systems with bifacial silicon solar cells

    Science.gov (United States)

    Martínez Díez, Ana Luisa; Gutmann, Johannes; Posdziech, Janina; Rist, Tim; Plaza, David Gómez; Goldschmidt, Jan Christoph

    2014-10-01

    In this paper, we present a concentrator system based on a stack of fluorescent concentrators (FCs) and a bifacial solar cell. Coupling bifacial solar cells to a stack of FCs increases the performance of the system and preserves its efficiency when scaled. We used an approach to optimize a fluorescent solar concentrator system design based on a stack of multiple fluorescent concentrators (FC). Seven individual fluorescent collectors (20 mm × 20 mm × 2 mm) were realized by in-situ polymerization and optically characterized in regard to their ability to guide light to the edges. Then, an optimization procedure based on the experimental data of the individual FCs was carried out to determine the stack configuration that maximizes the total number of photons leaving edges. Finally, two fluorescent concentrator systems were realized by attaching bifacial silicon solar cells to the optimized FC stacks: a conventional system, where FC were attached to one side of the solar cell as a reference, and the proposed bifacial configuration. It was found that for the same overall FC area, the bifacial configuration increases the short-circuit current by a factor of 2.2, which is also in agreement with theoretical considerations.

  11. Optimized scalable stack of fluorescent solar concentrator systems with bifacial silicon solar cells

    International Nuclear Information System (INIS)

    In this paper, we present a concentrator system based on a stack of fluorescent concentrators (FCs) and a bifacial solar cell. Coupling bifacial solar cells to a stack of FCs increases the performance of the system and preserves its efficiency when scaled. We used an approach to optimize a fluorescent solar concentrator system design based on a stack of multiple fluorescent concentrators (FC). Seven individual fluorescent collectors (20 mm × 20 mm × 2 mm) were realized by in-situ polymerization and optically characterized in regard to their ability to guide light to the edges. Then, an optimization procedure based on the experimental data of the individual FCs was carried out to determine the stack configuration that maximizes the total number of photons leaving edges. Finally, two fluorescent concentrator systems were realized by attaching bifacial silicon solar cells to the optimized FC stacks: a conventional system, where FC were attached to one side of the solar cell as a reference, and the proposed bifacial configuration. It was found that for the same overall FC area, the bifacial configuration increases the short-circuit current by a factor of 2.2, which is also in agreement with theoretical considerations.

  12. Analysis and Improvement of a Scaled-Up and Stacked Microbial Fuel Cell

    NARCIS (Netherlands)

    Dekker, A.J.G.; Heijne, ter A.; Saakes, M.; Hamelers, H.V.M.; Buisman, C.J.N.

    2009-01-01

    Scaling up microbial fuel cells (MFCs) is inevitable when power outputs have to be obtained that can power electrical devices other than small sensors. This research has used a bipolar plate MFC stack of four cells with a total working volume of 20 L and a total membrane surface area of 2 m2. The ca

  13. Fuel cell system including a unit for electrical isolation of a fuel cell stack from a manifold assembly and method therefor

    Science.gov (United States)

    Kelley; Dana A. , Farooque; Mohammad , Davis; Keith

    2007-10-02

    A fuel cell system with improved electrical isolation having a fuel cell stack with a positive potential end and a negative potential, a manifold for use in coupling gases to and from a face of the fuel cell stack, an electrical isolating assembly for electrically isolating the manifold from the stack, and a unit for adjusting an electrical potential of the manifold such as to impede the flow of electrolyte from the stack across the isolating assembly.

  14. Using qualimetric engineering and extremal analysis to optimize a proton exchange membrane fuel cell stack

    International Nuclear Information System (INIS)

    Highlights: • We consider the optimal configuration of a PEMFC stack. • We utilize qualimetric engineering tools (Taguchi screening, regression analysis). • We achieve analytical solution on a restructured power-law fitting. • We discuss the Pt-cost involvement in the unit and area minimization scope. - Abstract: The optimal configuration of the proton exchange membrane fuel-cell (PEMFC) stack has received attention recently because of its potential use as an isolated energy distributor for household needs. In this work, the original complex problem for generating an optimal PEMFC stack based on the number of cell units connected in series and parallel arrangements as well as on the cell area is revisited. A qualimetric engineering strategy is formulated which is based on quick profiling the PEMFC stack voltage response. Stochastic screening is initiated by employing an L9(33) Taguchi-type OA for partitioning numerically the deterministic expression of the output PEMFC stack voltage such that to facilitate the sizing of the magnitude of the individual effects. The power and current household specifications for the stack system are maintained at the typical settings of 200 W at 12 V, respectively. The minimization of the stack total-area requirement becomes explicit in this work. The relationship of cell voltage against cell area is cast into a power-law model by regression fitting that achieves a coefficient of determination value of 99.99%. Thus, the theoretical formulation simplifies into a non-linear extremal problem with a constrained solution due to a singularity which is solved analytically. The optimal solution requires 22 cell units connected in series where each unit is designed with an area value of 151.4 cm2. It is also demonstrated how to visualize the optimal solution using the graphical method of operating lines. The total area of 3270.24 cm2 becomes a new benchmark for the optimal design of the studied PEMFC stack configuration. It is

  15. Pressurized Testing of Solid Oxide Electrolysis Stacks with Advanced Electrode-Supported Cells

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; X. Zhang; G. K. Housley; K. DeWall; L. Moore-McAteer; G. Tao

    2012-06-01

    A new facility has been developed at the Idaho National Laboratory for pressurized testing of solid oxide electrolysis stacks. Pressurized operation is envisioned for large-scale hydrogen production plants, yielding higher overall efficiencies when the hydrogen product is to be delivered at elevated pressure for tank storage or pipelines. Pressurized operation also supports higher mass flow rates of the process gases with smaller components. The test stand can accommodate cell dimensions up to 8.5 cm x 8.5 cm and stacks of up to 25 cells. The pressure boundary for these tests is a water-cooled spool-piece pressure vessel designed for operation up to 5 MPa. The stack is internally manifolded and operates in cross-flow with an inverted-U flow pattern. Feed-throughs for gas inlets/outlets, power, and instrumentation are all located in the bottom flange. The entire spool piece, with the exception of the bottom flange, can be lifted to allow access to the internal furnace and test fixture. Lifting is accomplished with a motorized threaded drive mechanism attached to a rigid structural frame. Stack mechanical compression is accomplished using springs that are located inside of the pressure boundary, but outside of the hot zone. Initial stack heatup and performance characterization occurs at ambient pressure followed by lowering and sealing of the pressure vessel and subsequent pressurization. Pressure equalization between the anode and cathode sides of the cells and the stack surroundings is ensured by combining all of the process gases downstream of the stack. Steady pressure is maintained by means of a backpressure regulator and a digital pressure controller. A full description of the pressurized test apparatus is provided in this paper.

  16. A parametric study of the natural vibration and mode shapes of PEM fuel cell stacks

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2016-01-01

    Full Text Available A PEM fuel cell stack is laminated with a number of plate-type cells, and the latest model is assembled by compression from both ends of plates.PEM fuel cells are exposed to high magnitude vibrations, shocks, and cyclic loads in many applications. Vibrations during operation show significant impact in the longer run of the fuel cells. Frequencies which are not close to the resonant frequencies or natural frequencies show very little effect on the overall performance. However, if the frequency ranges of operation approaches the resonant frequency range, the probability of component failure increases. It is possible that there will be lateral transition of cells or leakage of fuel gas and coolant water. Therefore, it is necessary to evaluate the effects vibration has on the fuel cell. This work aims to understand the vibration characteristics of a PEM fuel cell stack and to evaluate their seismic resistance under a vibration environment. Natural frequencies and mode shapes of the PEM fuel cell stack are modelling using finite element methods (FEM.A parametric study is conducted to investigate how the natural frequency varies as a function of thickness, Young’s modulus, and density for each component layer. In addition, this work provides insight into how the natural frequencies of the PEM fuel cell stack should be tuned to avoid high amplitude vibrations by modifying the material and geometric properties of individual components. The mode shapes of the PEM fuel cell stack provide insight into the maximum displacement exhibited under vibration conditions that should be considered for transportation and stationary applications.

  17. Pressurized Operation of a Planar Solid Oxide Cell Stack

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  18. Stack configurations for tubular solid oxide fuel cells

    Science.gov (United States)

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

    2010-08-31

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

  19. Investigation of sulfonated polysulfone membranes as electrolyte in a passive-mode direct methanol fuel cell mini-stack

    Energy Technology Data Exchange (ETDEWEB)

    Lufrano, F.; Baglio, V.; Staiti, P.; Stassi, A.; Arico, A.S.; Antonucci, V. [CNR - ITAE, Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' , Via Salita S. Lucia sopra Contesse n. 5 - 98126 S. Lucia - Messina (Italy)

    2010-12-01

    This paper reports on the development of polymer electrolyte membranes (PEMs) based on sulfonated polysulfone for application in a DMFC mini-stack operating at room temperature in passive mode. The sulfonated polysulfone (SPSf) with two degrees of sulfonation (57 and 66%) was synthesized by a well-known sulfonation process. SPSf membranes with different thicknesses were prepared and investigated. These membranes were characterized in terms of methanol/water uptake, proton conductivity, and fuel cell performance in a DMFC single cell and mini-stack operating at room temperature. The study addressed (a) control of the synthesis of sulfonated polysulfone, (b) optimization of the assembling procedure, (c) a short lifetime investigation and (d) a comparison of DMFC performance in active-mode operation vs. passive-mode operation. The best passive DMFC performance was 220 mW (average cell power density of about 19 mW cm{sup -2}), obtained with a thin SPSf membrane (70 {mu}m) at room temperature, whereas the performance of the same membrane-based DMFC in active mode was 38 mW cm{sup -2}. The conductivity of this membrane, SPSf (IEC = 1.34 mequiv. g{sup -1}) was 2.8 x 10{sup -2} S cm{sup -1}. A preliminary short-term test (200 min) showed good stability during chrono-amperometry measurements. (author)

  20. Parametric Sensitivity Tests—European Polymer Electrolyte Membrane Fuel Cell Stack Test Procedures

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2014-01-01

    As fuel cells are increasingly commercialized for various applications, harmonized and industry-relevant test procedures are necessary to benchmark tests and to ensure comparability of stack performance results from different parties. This paper reports the results of parametric sensitivity tests...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    /stack assembly in the fuel cell (SOFC), in the electrolysis (SOEC) and in the combined SOFC/SOEC mode are addressed. This covers the wide field of power generation systems, e.g. stationary SOFC µ-CHP, mobile SOFC APU and SOFC/SOEC power-to-gas systems. This paper presents the results which have been achieved so...

  2. Prognostics of Proton Exchange Membrane Fuel Cells stack using an ensemble of constraints based connectionist networks

    Science.gov (United States)

    Javed, Kamran; Gouriveau, Rafael; Zerhouni, Noureddine; Hissel, Daniel

    2016-08-01

    Proton Exchange Membrane Fuel Cell (PEMFC) is considered the most versatile among available fuel cell technologies, which qualify for diverse applications. However, the large-scale industrial deployment of PEMFCs is limited due to their short life span and high exploitation costs. Therefore, ensuring fuel cell service for a long duration is of vital importance, which has led to Prognostics and Health Management of fuel cells. More precisely, prognostics of PEMFC is major area of focus nowadays, which aims at identifying degradation of PEMFC stack at early stages and estimating its Remaining Useful Life (RUL) for life cycle management. This paper presents a data-driven approach for prognostics of PEMFC stack using an ensemble of constraint based Summation Wavelet- Extreme Learning Machine (SW-ELM) models. This development aim at improving the robustness and applicability of prognostics of PEMFC for an online application, with limited learning data. The proposed approach is applied to real data from two different PEMFC stacks and compared with ensembles of well known connectionist algorithms. The results comparison on long-term prognostics of both PEMFC stacks validates our proposition.

  3. Accelerated testing of solid oxide fuel cell stacks for micro combined heat and power application

    DEFF Research Database (Denmark)

    Hagen, Anke; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

    2015-01-01

    State-of-the-art (SoA) solid oxide fuel cell (SOFC) stacks are tested using profiles relevant for use in micro combined heat and power (CHP) units. Such applications are characterised by dynamic load profiles. In order to shorten the needed testing time and to investigate potential acceleration of...

  4. Analysis and modeling of PEM fuel cell stack performance: Effect of in situ reverse water gas shift reaction and oxygen bleeding

    Science.gov (United States)

    Karimi, G.; Li, Xianguo

    In this study the performance of a polymer electrolyte membrane (PEM) fuel cell stack is analyzed with a mathematical model when the stack operates on hydrocarbon reformate gas as the anode feed stream. It is shown that the effect of carbon dioxide dilution of the hydrogen dominated reformate gas has a minimal impact on the stack performance. However, the CO-poisoning effect due to the in situ reverse water gas shift reaction in the anode feed stream could have a very serious adverse impact on the stack performance, especially at high current densities. Thermodynamic calculations indicate that the equilibrium concentrations of CO could be as high as 100 ppm, generated by the in situ reverse water gas shift reaction, under the typical conditions of PEM fuel cell operation; and are influenced by the stack operating temperature and water content of the reformate anode feed. This CO-poisoning of the stack performance is shown mitigated effectively by introducing about 0.5-1% oxygen to the anode feed.

  5. Comparison of a One-Dimensional Model of a High-Temperature Solid-Oxide Electrolysis Stack with CFD and Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O& #39; Brien; C. M. Stoots; G. L. Hawkes

    2005-11-01

    A one-dimensional model has been developed to predict the thermal and electrochemical behavior of a high-temperature steam electrolysis stack. This electrolyzer model allows for the determination of the average Nernst potential, cell operating voltage, gas outlet temperatures, and electrolyzer efficiency for any specified inlet gas flow rates, current density, cell active area, and external heat loss or gain. The model includes a temperature-dependent area-specific resistance (ASR) that accounts for the significant increase in electrolyte ionic conductivity that occurs with increasing temperature. Model predictions are shown to compare favorably with results obtained from a fully 3-D computational fluid dynamics model. The one-dimensional model was also employed to demonstrate the expected trends in electrolyzer performance over a range of operating conditions including isothermal, adiabatic, constant steam utilization, constant flow rate, and the effects of operating temperature.

  6. A “4-cell” modular passive DMFC (direct methanol fuel cell) stack for portable applications

    International Nuclear Information System (INIS)

    A “4-cell” modular passive DMFC (direct methanol fuel cell) stack, which can be freely combined and applied to various electronic devices, is designed, fabricated and tested. Two PCB (printed circuit board) based accessories are designed and fabricated for electrically connecting and mechanically assembling the “4-cell” modules. The maximum power density of the “4-cell” module is 27 mW cm−2 at 5 M methanol concentration. The steady-state performances of the modular stacks with different numbers of modules are tested. The extra power loss of the multiple module stacks due to inter-module electrical connections is predicted by mathematical fitting method. The fitting results indicate that the efficiencies of the multiple module stacks are all above 90% up to 10 modules. The dynamic performances of the modular stacks are also investigated for portable applications. The results show that the modular stacks exhibit good responsiveness and reproducibility at high loading current (>100 mA). Finally, the modular stacks are successfully applied to drive the experimental fan and charge the mobile phone. - Highlights: • A “4-cell” modular passive DMFC (direct methanol fuel cell) stack is designed, fabricated and tested. • This modular DMFC stack can assemble more single cells with high efficiency. • The modular stack exhibit good responsiveness and reproducibility for portable application

  7. Carrier recombination effects in strain compensated quantum dot stacks embedded in solar cells

    OpenAIRE

    Alonso Alvarez, Diego; González Taboada, Alfonso; Ripalda Cobián, Jose María; Alén Millán, Benito; González Diez, M. Yolanda; González Soto, Luisa; García Martín, Jorge Miguel; Martí Vega, Antonio; Luque López, Antonio; Briones Fernández-Pola, Fernando; Sanchez, A. M.; Molina Rubio, Sergio Ignacio

    2008-01-01

    In this work we report the stacking of 50 InAs/GaAs quantum dot layers with a GaAs spacer thickness of 18 nm using GaP monolayers for strain compensation. We find a good structural and optical quality of the fabricated samples including a planar growth front across the whole structure, a reduction in the quantum dot size inhomogeneity, and an enhanced thermal stability of the emission. The optimized quantum dot stack has been embedded in a solar cell structure and we discuss the benefits and ...

  8. Identification of critical stacking faults in thin-film CdTe solar cells

    International Nuclear Information System (INIS)

    Cadmium telluride (CdTe) is a p-type semiconductor used in thin-film solar cells. To achieve high light-to-electricity conversion, annealing in the presence of CdCl2 is essential, but the underlying mechanism is still under debate. Recent evidence suggests that a reduction in the high density of stacking faults in the CdTe grains is a key process that occurs during the chemical treatment. A range of stacking faults, including intrinsic, extrinsic, and twin boundary, are computationally investigated to identify the extended defects that limit performance. The low-energy faults are found to be electrically benign, while a number of higher energy faults, consistent with atomic-resolution micrographs, are predicted to be hole traps with fluctuations in the local electrostatic potential. It is expected that stacking faults will also be important for other thin-film photovoltaic technologies

  9. Scaled-up dual anode/cathode microbial fuel cell stack for actual ethanolamine wastewater treatment.

    Science.gov (United States)

    An, Byung-Min; Heo, Yoon; Maitlo, Hubdar-Ali; Park, Joo-Yang

    2016-06-01

    The aim of this work was to develop the scale-up microbial fuel cell technology for actual ethanolamine wastewater treatment, dual anode/cathode MFC stacks connected in series to achieve any desired current, treatment capacity, and volume capacity. However, after feeding actual wastewater into the MFC, maximum power density decreased while the corresponding internal resistance increased. With continuous electricity production, a stack of eight MFCs in series achieved 96.05% of COD removal and 97.30% of ammonia removal at a flow rate of 15.98L/d (HRT 12h). The scaled-up dual anode/cathode MFC stack system in this research was demonstrated to treat actual ETA wastewater with the added benefit of harvesting electricity energy. PMID:26888335

  10. A novel pilot-scale stacked microbial fuel cell for efficient electricity generation and wastewater treatment.

    Science.gov (United States)

    Wu, Shijia; Li, Hui; Zhou, Xuechen; Liang, Peng; Zhang, Xiaoyuan; Jiang, Yong; Huang, Xia

    2016-07-01

    A novel stacked microbial fuel cell (MFC) which had a total volume of 72 L with granular activated carbon (GAC) packed bed electrodes was constructed and verified to present remarkable power generation and COD removal performance due to its advantageous design of stack and electrode configuration. During the fed-batch operation period, a power density of 50.9 ± 1.7 W/m(3) and a COD removal efficiency of 97% were achieved within 48 h. Because of the differences among MFC modules in the stack, reversal current occurred in parallel circuit connection with high external resistances (>100 Ω). This reversal current consequently reduced the electrochemical performance of some MFC modules and led to a lower power density in parallel circuit connection than that in independent circuit connection. While increasing the influent COD concentrations from 200 to 800 mg/L at hydraulic retention time of 1.25 h in continuous operation mode, the power density of stacked MFC increased from 25.6 ± 2.5 to 42.1 ± 1.2 W/m(3) and the COD removal rates increased from 1.3 to 5.2 kg COD/(m(3) d). This study demonstrated that this novel MFC stack configuration coupling with GAC packed bed electrode could be a feasible strategy to effectively scale up MFC systems. PMID:27131320

  11. Analysis of Entropy Generation for the Performance Improvement of a Tubular Solid Oxide Fuel Cell Stack

    Directory of Open Access Journals (Sweden)

    Vittorio Verda

    2009-03-01

    Full Text Available The aim of the paper is to investigate possible improvements in the design and operation of a tubular solid oxide fuel cell. To achieve this purpose, a CFD model of the cell is introduced. The model includes thermo-fluid dynamics, chemical reactions and electrochemistry. The fluid composition and mass flow rates at the inlet sections are obtained through a finite difference model of the whole stack. This model also provides boundary conditions for the radiation heat transfer. All of these conditions account for the position of each cell within the stack. The analysis of the cell performances is conducted on the basis of the entropy generation. The use of this technique makes it possible to identify the phenomena provoking the main irreversibilities, understand their causes and propose changes in the system design and operation.

  12. Flow distribution measurements at the exit of bipolar plates in a PEM fuel cell stack; Messung der Stroemungsverteilung am Austritt der Bipolarplatten eines Brennstoffzellen-Stacks

    Energy Technology Data Exchange (ETDEWEB)

    Klinner, Joachim; Willert, Christian [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Koeln (Germany). Abt. Triebwerksmesstechnik; Schneider, Armin; Mack-Gardner, Andre [Adam Opel GmbH, Ruesselsheim (Germany). Alternative Propulsion Center Europe

    2011-07-01

    This paper presents two different experimental approaches which concentrate on capturing the flow distribution close to the anode exit header of a prototype 8-12 KW fuel cell stack operated with air at realistic flow rates. The first approach intends to visualize the penetration depth of millimeter-sized jets towards the exit manifold. The second one is focused on obtaining the exit jet velocity field downstream of the bipolar plate exit header across the entire stack height by repeated 2C-PIV measurements on densely spaced adjacent light sheet planes. An overview of the experimental setup and the data evaluation is given. (orig.)

  13. Temperature-and field dependent characterization of a twisted stacked-tape cable

    Science.gov (United States)

    Barth, C.; Takayasu, M.; Bagrets, N.; Bayer, C. M.; Weiss, K.-P.; Lange, C.

    2015-04-01

    The twisted stacked-tape cable (TSTC) is one of the major high temperature superconductor cable concepts combining scalability, ease of fabrication and high current density making it a possible candidate as conductor for large scale magnets. To simulate the boundary conditions of such a magnets as well as the temperature dependence of TSTCs a 1.16 m long sample consisting of 40, 4 mm wide SuperPower REBCO tapes is characterized using the ‘FBI’ (force-field-current) superconductor test facility of the Institute for Technical Physics of the Karlsruhe Institute of Technology. In a first step, the magnetic background field is cycled while measuring the current carrying capabilities to determine the impact of Lorentz forces on the TSTC sample performance. In the first field cycle, the critical current of the TSTC sample is tested up to 12 T. A significant Lorentz force of up to 65.6 kN m-1 at the maximal magnetic background field of 12 T result in a 11.8% irreversible degradation of the current carrying capabilities. The degradation saturates (critical cable current of 5.46 kA at 4.2 K and 12 T background field) and does not increase in following field cycles. In a second step, the sample is characterized at different background fields (4-12 T) and surface temperatures (4.2-37.8 K) utilizing the variable temperature insert of the ‘FBI’ test facility. In a third step, the performance along the length of the sample is determined at 77 K, self-field. A 15% degradation is obtained for the central part of the sample which was within the high field region of the magnet during the in-field measurements.

  14. The use of additive manufacture for metallic bipolar plates in polymer electrolyte fuel cell stacks

    OpenAIRE

    Dawson, Richard; Patel, Anant; Rennie, Allan; White, Simon

    2014-01-01

    The bipolar plate is of critical importance to the efficient and long lasting operation of a polymer electrolyte fuel cell (PEMFC) stack. With advances in membrane electrode assembly (MEA) design greater attention has been focused on the bipolar plate and the important role it plays in performance and durability. Although carbon composite plates are a likely candidate for the mass introduction of fuel cells, it is metallic plates made from thin strip materials (typically 0.2 mm thick stainles...

  15. On-line and real-time diagnosis method for proton membrane fuel cell (PEMFC) stack by the superposition principle

    Science.gov (United States)

    Lee, Young-Hyun; Kim, Jonghyeon; Yoo, Seungyeol

    2016-09-01

    The critical cell voltage drop in a stack can be followed by stack defect. A method of detecting defective cell is the cell voltage monitoring. The other methods are based on the nonlinear frequency response. In this paper, the superposition principle for the diagnosis of PEMFC stack is introduced. If critical cell voltage drops exist, the stack behaves as a nonlinear system. This nonlinearity can explicitly appear in the ohmic overpotential region of a voltage-current curve. To detect the critical cell voltage drop, a stack is excited by two input direct test-currents which have smaller amplitude than an operating stack current and have an equal distance value from the operating current. If the difference between one voltage excited by a test current and the voltage excited by a load current is not equal to the difference between the other voltage response and the voltage excited by the load current, the stack system acts as a nonlinear system. This means that there is a critical cell voltage drop. The deviation from the value zero of the difference reflects the grade of the system nonlinearity. A simulation model for the stack diagnosis is developed based on the SPP, and experimentally validated.

  16. Note: A heated-air curtain design using the Coanda effect to protect optical access windows in high-temperature, condensing, and corrosive stack environments

    Science.gov (United States)

    Williams, Gustavious Paul; Keenan, Thomas L.; Herning, James; Kimblin, Clare; DiBenedetto, John; Anthony, Glen

    2011-01-01

    We present an air knife design for creating a heated air curtain to protect optical infrared access windows in high-temperature, condensing, and corrosive stack environments. The design uses the Coanda effect to turn the air curtain and to attach the air curtain to the window surface. The design was tested and verified on our 24 m stack and used extensively over a 6 yr period on several release stacks. During testing and subsequent use no detrimental changes to access window materials have been noted. This design allows stack monitoring without significantly affecting the stack flow profile or chemical concentration.

  17. Linear identification and model adjustment of a PEM fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Kunusch, C.; Puleston, P.F.; More, J.J. [LEICI, Departamento de Electrotecnia, Universidad Nacional de La Plata, calle 1 esq. 47 s/n, 1900 La Plata (Argentina); Consejo de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Husar, A. [Institut de Robotica i Informatica Industrial (CSIC-UPC), c/ Llorens i Artigas 4-6, 08028 Barcelona (Spain); Mayosky, M.A. [LEICI, Departamento de Electrotecnia, Universidad Nacional de La Plata, calle 1 esq. 47 s/n, 1900 La Plata (Argentina); Comision de Investigaciones Cientificas (CIC), Provincia de Buenos Aires (Argentina)

    2008-07-15

    In the context of fuel cell stack control a mayor challenge is modeling the interdependence of various complex subsystem dynamics. In many cases, the states interaction is usually modeled through several look-up tables, decision blocks and piecewise continuous functions. Many internal variables are inaccessible for measurement and cannot be used in control algorithms. To make significant contributions in this area, it is necessary to develop reliable models for control and design purposes. In this paper, a linear model based on experimental identification of a 7-cell stack was developed. The procedure followed to obtain a linear model of the system consisted in performing spectroscopy tests of four different single-input single-output subsystems. The considered inputs for the tests were the stack current and the cathode oxygen flow rate, while the measured outputs were the stack voltage and the cathode total pressure. The resulting model can be used either for model-based control design or for on-line analysis and errors detection. (author)

  18. Flow network analysis in PEM fuel cell stacks incorporating minor losses. Paper no. IGEC-1-062

    International Nuclear Information System (INIS)

    The performance of a polymer electrolyte membrane (PEM) fuel cell stack consisting 51 cells has been analyzed using a flow network model incorporating the minor losses. The distributions of pressure, molar flow rate and concentration for the fuel and oxidant streams in the stack are determined. The distributions are used in the single cell model developed previously to evaluate the stack voltage and the cell-to-cell voltage distributions. Analysis has been carried out for a variety of flow configurations and bipolar plate designs. It was found that the minor losses increase the stack operating pressure and the power requirement for oxidant supply and change the cell-to-cell voltage variations in the stack. A symmetric double inlet-single outlet topology provides optimal stack performance with reasonably low compressor power requirement for the reactant flow and minimum cell-to-cell voltage variations. The stack performance is considerably affected by the size and the number of flow channels on bipolar plate. (author)

  19. Miniaturized polymer electrolyte fuel cell (PEFC) stack using micro structured bipolar plate

    Energy Technology Data Exchange (ETDEWEB)

    Veziridis, Z.; Scherer, G.G.; Marmy, Ch.; Glaus, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    In Polymer Electrolyte Fuel Cell (PEFC) technology the reducing of volume and mass of the fuel cell stack and the improvement of catalyst utilization are of great interest. These parameters affect applicability and system cost. In this work we present an alternative way for reducing the stack volume by combining gas distribution and catalytic active area in one plate. Micro machined glassy carbon electrodes serve as support material for the platinum catalyst, as well as gas distributor at the same time. A comparison of these electrodes with conventional platinum-black gas diffusion electrodes under fuel cell conditions shows that the new system is a promising electrode type for enhanced power density and catalyst utilization. (author) 3 figs., 5 refs.

  20. Validation of a novel method for detecting and stabilizing malfunctioning areas in fuel cell stacks

    Science.gov (United States)

    Müller, Martin; Hirschfeld, Julian; Lambertz, Rita; Schulze Lohoff, Andreas; Lustfeld, Hans; Pfeifer, Heinz; Reißel, Martin

    2014-12-01

    In this paper a setup for detecting malfunctioning areas of MEAs in fuel cell stacks is described. Malfunctioning areas generate electric cross currents inside bipolar plates. To exploit this we suggest bipolar plates consisting not of two but of three layers. The third one is a highly conducting layer and segmented such that the cross currents move along the segments to the surface of the stack where they can be measured by an inductive sensor. With this information a realistic model can be used to detect the malfunctioning area. Furthermore the third layer will prevent any current inhomogeneity of a malfunctioning cell to spread to neighbouring cells in the stack. In this work the results of measurements in a realistic cell setup will be compared with the results obtained in simulation studies with the same configuration. The basis for the comparison is the reliable characterisation of the electrical properties of the cell components and the implication of these results into the simulation model. The experimental studies will also show the limits in the maximum number of segments, which can be used for a reliable detection of cross currents.

  1. Estimation of Membrane Hydration Status for Standby Proton Exchange Membrane Fuel Cell Systems by Impedance Measurement: First Results on Stack Characterization

    DEFF Research Database (Denmark)

    Bidoggia, Benoit; Kær, Søren Knudsen

    Fuel cells have started replacing traditional lead-acid battery banks in backup systems. Although these systems are characterized by long periods of standby, they must be able to start at any instant in the shortest time. In the case of low temperature proton exchange membrane fuel cell systems, a...... precise estimation of hydration status of the fuel cell during standby is important for a fast and safe startup. In this article, the measurement of the complex impedance of the fuel cell is suggested as a method to estimate the membrane hydration status. A 56-cell fuel cell stack has been symmetrically...

  2. Temperature dependence of intra-stack defect spin-conduction-electron spin interaction in fluoranthene and perylene radical cation salts

    International Nuclear Information System (INIS)

    The electron spin resonance line-width anisotropy and intensity are analysed for the quasi-one-dimensional organic conductors (fluoranthene)2PF6 and (perylene)2PF6·2/3 tetrahydrofurane in the metallic phase above the Peierls transition temperature. Based on the bottleneck model of relaxation, the temperature dependence of the intra-stack exchange constant between conduction-electron spins and localized defect spins is derived and discussed

  3. 400 W High Temperature PEM Fuel Cell Stack Test

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2006-01-01

    -1000 series MEAs by Pemeas, with an active area of 45cm2. The low pressure gas channels enable the use of low power blowers instead of a compressor which increases the overall system efficiency. This initial system was made to test the bipolar plate design, and there is no need for humidification of...

  4. Study of the distribution of air flow in a proton exchange membrane fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Mustata, Radu; Valino, Luis; Barreras, Felix; Gil, Maria Isabel; Lozano, Antonio [LITEC, CSIC - Univ. Zaragoza - DGA Maria de Luna 10, 50018, Zaragoza (Spain)

    2009-07-01

    The flow of air to feed oxygen to the cathode of each plate in a proton exchange membrane fuel cell (PEMFC) is studied for a 300 W stack in a realistic 3D configuration. Two configurations for gas income are solved, a ''U'' shape, where both the inlet and outlet of the air collectors are at the same end plate, and a ''Z'' shape, where inlet and outlet are at opposite sides of the stack. Under a simplified assumption for the flow of oxygen entering the gas diffusion layer of each cell, detailed mass flow and pressure distributions are shown, including the possibility of a turbulent flow inside the main collectors. (author)

  5. Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack

    Science.gov (United States)

    Carter, J. David; Mawdsley, Jennifer R.; Niyogi, Suhas; Wang, Xiaoping; Cruse, Terry; Santos, Lilia

    2010-04-20

    A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

  6. Development and characterization of a novel air-breathing micro direct methanol fuel cell stack for portable applications

    International Nuclear Information System (INIS)

    An air-breathing 10-cell micro direct methanol fuel cell (µDMFC) stack with four anode feeding patterns is designed, fabricated and tested. For a better understanding of the operational characteristics of both the single cell and the stack, a two-dimensional numerical model is established and calculated. Employing micro-stamping technology, the current collectors of each single cell are microfabricated on the stainless steel plate with a thickness of 300 µm. The single µDMFC is first tested under various operating parameters. On the basis of the simulation and experimental observation of the single cell performance, the µDMFC stack performance is thoroughly analyzed with different anode feeding patterns. The results indicate that the µDMFC stack with pattern B can ensure the uniform performance of each single cell and generate the highest power output. With pattern B, further experiments are carried out to investigate the influence of the anode flow rate on the stack performance. As a result, the µDMFC stack achieves the best performance with the maximum power density of about 24.75 mW cm−2 at 5.0 ml min−1. Finally, the stack is successfully applied to two electronic devices of different rated power

  7. Efficiency Enhancement of InGaN-Based Solar Cells via Stacking Layers of Light-Harvesting Nanospheres.

    Science.gov (United States)

    Al-Amri, Amal M; Fu, Po-Han; Lai, Kun-Yu; Wang, Hsin-Ping; Li, Lain-Jong; He, Jr-Hau

    2016-01-01

    An effective light-harvesting scheme for InGaN-based multiple quantum well solar cells is demonstrated using stacking layers of polystyrene nanospheres. Light-harvesting efficiencies on the solar cells covered with varied stacks of nanospheres are evaluated through numerical and experimental methods. The numerical simulation reveals that nanospheres with 3 stacking layers exhibit the most improved optical absorption and haze ratio as compared to those obtained by monolayer nanospheres. The experimental demonstration, agreeing with the theoretical analyses, shows that the application of 3-layer nanospheres improves the conversion efficiency of the solar cell by ~31%. PMID:27339612

  8. Efficiency Enhancement of InGaN-Based Solar Cells via Stacking Layers of Light-Harvesting Nanospheres

    Science.gov (United States)

    Al-Amri, Amal M.; Fu, Po-Han; Lai, Kun-Yu; Wang, Hsin-Ping; Li, Lain-Jong; He, Jr-Hau

    2016-01-01

    An effective light-harvesting scheme for InGaN-based multiple quantum well solar cells is demonstrated using stacking layers of polystyrene nanospheres. Light-harvesting efficiencies on the solar cells covered with varied stacks of nanospheres are evaluated through numerical and experimental methods. The numerical simulation reveals that nanospheres with 3 stacking layers exhibit the most improved optical absorption and haze ratio as compared to those obtained by monolayer nanospheres. The experimental demonstration, agreeing with the theoretical analyses, shows that the application of 3-layer nanospheres improves the conversion efficiency of the solar cell by ~31%. PMID:27339612

  9. Efficiency Enhancement of InGaN-Based Solar Cells via Stacking Layers of Light-Harvesting Nanospheres

    KAUST Repository

    Al-Amri, Amal M.

    2016-06-24

    An effective light-harvesting scheme for InGaN-based multiple quantum well solar cells is demonstrated using stacking layers of polystyrene nanospheres. Light-harvesting efficiencies on the solar cells covered with varied stacks of nanospheres are evaluated through numerical and experimental methods. The numerical simulation reveals that nanospheres with 3 stacking layers exhibit the most improved optical absorption and haze ratio as compared to those obtained by monolayer nanospheres. The experimental demonstration, agreeing with the theoretical analyses, shows that the application of 3-layer nanospheres improves the conversion efficiency of the solar cell by ~31%.

  10. Dynamics of the phase formation process upon the low temperature selenization of Cu/In-multilayer stacks

    International Nuclear Information System (INIS)

    Phase reactions occurring during a low temperature selenization of thin In/Cu-multilayer stacks were investigated by ex-situ x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS). Therefore, dc-sputtered In/Cu-multilayers onto molybdenum coated soda lime glass were selenized in a high vacuum system at temperatures between 260 and 340 °C with different dwell times and selenium supply. The combination of the results of the phase analysis by XRD and the measurements of the in-depth elemental distribution by EDS allowed a conclusion on the occurring reactions within the layer depth. We found two CuInSe2 formation processes depending on the applied temperature. Already, at a heater temperature of 260 °C, the CuInSe2 formation can occur by the reaction of Cu2−xSe with In4Se3 and Se. At 340 °C, CuInSe2 is formed by the reaction of Cu2−xSe with InSe and Se. Because both reactions need additional selenium, the selenium supply during the selenization can shift the reaction equilibria either to the metal binaries side or to the CuInSe2 side. Interestingly, a lower selenium supply shifts the equilibrium to the CuInSe2 side, because the amount of selenium incorporated into the metallic layer is higher for a lower selenium supply. Most likely, a larger number of grain boundaries are the reason for the stronger selenium incorporation. The results of the phase formation studies were used to design a two stage selenization process to get a defined structure of an indium selenide- and a copper selenide-layer at low temperatures as the origin for a controlled interdiffusion to form the CuInSe2-absorber-layer at higher temperatures. The approach delivers a CuInSe2 absorber which reach total area efficiencies of 11.8% (13.0% active area) in a CuInSe2-thin-film solar cell. A finished formation of CuInSe2 at low temperature was not observed in our experiments but is probably possible for longer dwell times

  11. Dynamics of the phase formation process upon the low temperature selenization of Cu/In-multilayer stacks

    Energy Technology Data Exchange (ETDEWEB)

    Oertel, M., E-mail: michael.oertel@uni-jena.de; Ronning, C. [Institute of Solid State Physics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2015-03-14

    Phase reactions occurring during a low temperature selenization of thin In/Cu-multilayer stacks were investigated by ex-situ x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS). Therefore, dc-sputtered In/Cu-multilayers onto molybdenum coated soda lime glass were selenized in a high vacuum system at temperatures between 260 and 340 °C with different dwell times and selenium supply. The combination of the results of the phase analysis by XRD and the measurements of the in-depth elemental distribution by EDS allowed a conclusion on the occurring reactions within the layer depth. We found two CuInSe{sub 2} formation processes depending on the applied temperature. Already, at a heater temperature of 260 °C, the CuInSe{sub 2} formation can occur by the reaction of Cu{sub 2−x}Se with In{sub 4}Se{sub 3} and Se. At 340 °C, CuInSe{sub 2} is formed by the reaction of Cu{sub 2−x}Se with InSe and Se. Because both reactions need additional selenium, the selenium supply during the selenization can shift the reaction equilibria either to the metal binaries side or to the CuInSe{sub 2} side. Interestingly, a lower selenium supply shifts the equilibrium to the CuInSe{sub 2} side, because the amount of selenium incorporated into the metallic layer is higher for a lower selenium supply. Most likely, a larger number of grain boundaries are the reason for the stronger selenium incorporation. The results of the phase formation studies were used to design a two stage selenization process to get a defined structure of an indium selenide- and a copper selenide-layer at low temperatures as the origin for a controlled interdiffusion to form the CuInSe{sub 2}-absorber-layer at higher temperatures. The approach delivers a CuInSe{sub 2} absorber which reach total area efficiencies of 11.8% (13.0% active area) in a CuInSe{sub 2}-thin-film solar cell. A finished formation of CuInSe{sub 2} at low temperature was not observed in our experiments but is probably

  12. High Temperature Co-electrolysis of Steam and CO2 in an SOC stack: Performance and Durability

    DEFF Research Database (Denmark)

    Chen, Ming; Høgh, Jens Valdemar Thorvald; Nielsen, Jens Ulrik;

    2012-01-01

    units can be used for co-electrolysis of steam and CO2 to produce synthesis gas (CO+H2), which can be further processed to a variety of synthetic fuels such as methane, methanol or DME [2]. Previously we have shown at stack level that Ni/YSZ electrode supported SOEC cells can be operated at 850 oC and....... The stack was operated at 800 oC and -0.75 A/cm2 with 60% conversion for a period of 1000 hours. One type of the cells showed no long term degradation but actually activation during the entire electrolysis period, while the other two types degraded. The performance and durability of the different cell...

  13. Intermediate Temperature Solid Oxide Fuel Cell Development

    Energy Technology Data Exchange (ETDEWEB)

    S. Elangovan; Scott Barnett; Sossina Haile

    2008-06-30

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

  14. Accelerated testing of solid oxide fuel cell stacks for micro combined heat and power application

    Science.gov (United States)

    Hagen, Anke; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

    2015-12-01

    State-of-the-art (SoA) solid oxide fuel cell (SOFC) stacks are tested using profiles relevant for use in micro combined heat and power (CHP) units. Such applications are characterised by dynamic load profiles. In order to shorten the needed testing time and to investigate potential acceleration of degradation, the profiles are executed faster than required for real applications. Operation with fast load cycling, both using hydrogen and methane/steam as fuels, does not accelerate degradation compared to constant operation, which demonstrates the maturity of SoA stacks and enables transferring knowledge from testing at constant conditions to dynamic operation. 7.5 times more cycles than required for 80,000 h lifetime as micro CHP are achieved on one-cell-stack level. The results also suggest that degradation mechanisms that proceed on a longer time-scale, such as creep, might have a more dominating effect for long life-times than regular short time changes of operation. In order to address lifetime testing it is suggested to build a testing program consisting of defined modules that represent different application profiles, such as one module at constant conditions, followed by modules at one set of dynamic conditions etc.

  15. Enhanced water desalination efficiency in an air-cathode stacked microbial electrodeionization cell (SMEDIC)

    KAUST Repository

    Chehab, Noura A.

    2014-11-01

    A microbial desalination cell was developed that contained a stack of membranes packed with ion exchange resins between the membranes to reduce ohmic resistances and improve performance. This new configuration, called a stacked microbial electro-deionization cell (SMEDIC), was compared to a control reactor (SMDC) lacking the resins. The SMEDIC+S reactors contained both a spacer and 1.4±0.2. mL of ion exchange resin (IER) per membrane channel, while the spacer was omitted in the SMEDIC-S reactors and so a larger volume of resin (2.4±0.2. mL) was used. The overall extent of desalination using the SMEDIC with a moderate (brackish water) salt concentration (13. g/L) was 90-94%, compared to only 60% for the SMDC after 7 fed-batch cycles of the anode. At a higher (seawater) salt concentration of 35. g/L, the extent of desalination reached 61-72% (after 10 cycles) for the SMEDIC, compared to 43% for the SMDC. The improved performance was shown to be due to the reduction in ohmic resistances, which were 130. Ω (SMEDIC-S) and 180. Ω (SMEDIC+S) at the high salt concentration, compared to 210. Ω without resin (SMDC). These results show that IERs can improve performance of stacked membranes for both moderate and high initial salt concentrations. © 2014 Elsevier B.V.

  16. Yield behaviour associated with stacking faults in a high-temperature annealed ultra-low carbon high manganese steel

    International Nuclear Information System (INIS)

    This paper investigated the tensile behaviour of high-temperature annealed ultra-low carbon high manganese steel with 42 vol% delta-ferrite. The results show that the tensile stress-strain curve of plastic deformation exhibits three distinct stages of deformation: a yielding stage with a remarkably large elongation and a positive strain-hardening rate, a second stage in which the strain-hardening rate rapidly increases, and a third stage in which the strain-hardening rate slowly increase. The yield plateau is intrinsically associated with the increasing formation of strain-induced stacking faults. The stacking faults quickly form during yield deformation, and the yield elongation monotonically increases with the extent of the stacking faults. The localised strain concentration of delta-ferrite and the heterogeneous strain partitioning between harder delta-ferrite and softer austenite play important roles in the rapid formation of stacking faults during strain at the yield plateau, which is an important prerequisite for this yielding phenomenon. The results and analysis demonstrate that the rapid and then slow hardening deformation after the yield plateau result from strain-induced transformation and deformation twinning, respectively

  17. Influence of Ring Oxidation-Induced Stack Faults on Efficiency in Silicon Solar Cells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chun-Lan; WANG Wen-Jing; LI Hai-Ling; ZHAO Lei; DIAO Hong-Wei; LI Xu-Dong

    2008-01-01

    @@ We observe a strong correlation between the ring oxidation-induced stack faults (OISF) formed in the course of phosphor diffusion and the efficiency of Czochralski-grown silicon solar cells. The main reason for ring-OISF formation and growth in substrate is the silicon oxidation and phosphorus diffusion process induced silicon self-interstitial point defect during POCl3 diffusion. The decreasing of minority carrier diffusion length in crystal silicon solar cell induced by ring-OISF defects is identified to be one of the major causes of efficiency loss.

  18. High temperature PEM fuel cell. Final report. Public part

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Jens Oluf (DTU (DK)); Yde Andersen, S.; Rycke, T. de (IRD Fuel Cells A/S (DK)); Nilsson, M. (Danish Power Systems ApS (DK)); Christensen, Torkild, (DONG Energy (DK))

    2006-07-01

    The main outcome of the project is the development of stacking technology for high temperature PEMFC stacks based on phosphoric acid doped polybenzimidazole membranes (PBI-membranes) and a study of the potential of a possible accommodation of HT-PEMFC in the national energy system. Stacks of different lengths (up to 40 cells) have been built using two different approaches in terms of plate materials and sealing. The stacks still need maturing and further testing to prove satisfactory reliability, and a steady reduction of production cost is also desired (as in general for fuel cells). However, during the project the process has come a long way. The survey of HT-PEM fuel cells and their regulatory power in the utility system concludes that fuel cells will most likely not be the dominating technique for regulation, but as no other technique has that potential alone, fuel cells are well suited to play a role in the system provided that the establishment of a communication system is not too complicated. In order to maintain an efficient power system with high reliability in a distributed generation scenario, it is important that communication between TSO (Transmission System Operator) and fuel cells is included in the fuel cell system design at an early stage. (au)

  19. Optimal design and operational tests of a high-temperature PEM fuel cell for a combined heat and power unit

    OpenAIRE

    Barreras Toledo, Felix Manuel; Lozano Fantoba, Antonio; Roda Serrat, Vicente; Barroso Estébanez, Jorge Angel; Martin Yagüe, Jesus Joaquín

    2014-01-01

    Development of new materials for polymer electrolyte membranes has allowed increasing the operational temperature of PEM fuel cell stacks above 120 degrees C. The present paper summarizes the main results obtained in a research devoted to the design, fabrication and operational tests performed on a high-temperature PEMFC prototype. A 5-cell stack has been assembled with commercial Celtec P-1000 high-temperature MEAs from BASF Fuel Cells, but the rest of elements and processes have been develo...

  20. MCFC燃料电池的非线性建模及基于FGA的模糊控制%Nonlinear modeling of molten carbonate fuel cell stack and FGA-based fuzzy control

    Institute of Scientific and Technical Information of China (English)

    戚志东; 朱新坚; 曹广益

    2006-01-01

    To improve the performance of fuel cells, the operating temperature of molten carbonate fuel cell (MCFC) stack should be controlled within a specified range. In this paper, with the RBF neural network's ability of identifying complex nonlinear systems, a neural network identification model of MCFC stack is developed based on the sampled input-output data. Also, a novel online fuzzy control procedure for the temperature of MCFC stack is developed based on the fuzzy genetic algorithm (FGA). Parameters and rules of the fuzzy controller are optimized. With the neural network identification model, simulation of MCFC stack control is carried out. Validity of the model and the superior performance of the fuzzy controller are demonstrated.

  1. Thermal modeling and temperature control of a PEM fuel cell system for forklift applications

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh; Kær, Søren Knudsen; Mortensen, Henrik H.

    2014-01-01

    fuel cell system for studying temperature variations over fast load changes. A temperature dependent cell polarization and hydration model integrated with the compressor, humidifier and cooling system are simulated in dynamic condition. A feedback PID control was implemented for stack cooling. The...... stack energy balance was reduced to a first order differential equation using a lumped approach. The first-order Linear Time-Invariant system was used to obtain the transfer function which was determined based on experimental data at different stack loads. The developed model approach can assist...

  2. Nonlinear modelling of polymer electrolyte membrane fuel cell stack using nonlinear cancellation technique

    International Nuclear Information System (INIS)

    Fuel cells are promising new energy conversion devices that are friendly to the environment. A set of control systems are required in order to operate a fuel cell based power plant system optimally. For the purpose of control system design, an accurate fuel cell stack model in describing the dynamics of the real system is needed. Currently, linear model are widely used for fuel cell stack control purposes, but it has limitations in narrow operation range. While nonlinear models lead to nonlinear control implemnetation whos more complex and hard computing. In this research, nonlinear cancellation technique will be used to transform a nonlinear model into a linear form while maintaining the nonlinear characteristics. The transformation is done by replacing the input of the original model by a certain virtual input that has nonlinear relationship with the original input. Then the equality of the two models is tested by running a series of simulation. Input variation of H2, O2 and H2O as well as disturbance input I (current load) are studied by simulation. The error of comparison between the proposed model and the original nonlinear model are less than 1 %. Thus we can conclude that nonlinear cancellation technique can be used to represent fuel cell nonlinear model in a simple linear form while maintaining the nonlinear characteristics and therefore retain the wide operation range

  3. Optimization of membrane stack configuration in enlarged microbial desalination cells for efficient water desalination

    Science.gov (United States)

    Chen, Xi; Sun, Haotian; Liang, Peng; Zhang, Xiaoyuan; Huang, Xia

    2016-08-01

    Microbial desalination cells are considered a low-energy-consumption, clean technology to simultaneously purify wastewater and desalinate saline water by utilizing the in situ energy source contained in wastewater. To enhance desalination performance and achieve an optimal membrane stack configuration, an enlarged stacked microbial desalination cell (SMDC) has been developed and tested with 6-14 desalination cells. The cross-membrane area of the enlarged SMDC is 100 cm2. The anode and cathode volumes are both 200 mL. To reduce internal resistance, the width of desalination cells is kept as <0.5 mm. The optimal configuration with 10 desalination cells achieves the highest total desalination rate (TDR) of 423 mg/h and the highest charge transfer efficiency (CTE) of 836% when treating the 20 g/L NaCl solution. During this process, the junction potential across membranes increases from 0 to 374 mV, and occupies up to 74% of the total potential loss inside the SMDC. This shows that the SMDC used in this work achieves the highest TDR and CTE among the reported studies, and the junction potential should be effectively controlled to achieve the desired desalination performance in future practical applications.

  4. Optimization of membrane stack configuration in enlarged microbial desalination cells for efficient water desalination

    Science.gov (United States)

    Chen, Xi; Sun, Haotian; Liang, Peng; Zhang, Xiaoyuan; Huang, Xia

    2016-08-01

    Microbial desalination cells are considered a low-energy-consumption, clean technology to simultaneously purify wastewater and desalinate saline water by utilizing the in situ energy source contained in wastewater. To enhance desalination performance and achieve an optimal membrane stack configuration, an enlarged stacked microbial desalination cell (SMDC) has been developed and tested with 6-14 desalination cells. The cross-membrane area of the enlarged SMDC is 100 cm2. The anode and cathode volumes are both 200 mL. To reduce internal resistance, the width of desalination cells is kept as cells achieves the highest total desalination rate (TDR) of 423 mg/h and the highest charge transfer efficiency (CTE) of 836% when treating the 20 g/L NaCl solution. During this process, the junction potential across membranes increases from 0 to 374 mV, and occupies up to 74% of the total potential loss inside the SMDC. This shows that the SMDC used in this work achieves the highest TDR and CTE among the reported studies, and the junction potential should be effectively controlled to achieve the desired desalination performance in future practical applications.

  5. Nonlinear modelling of polymer electrolyte membrane fuel cell stack using nonlinear cancellation technique

    Energy Technology Data Exchange (ETDEWEB)

    Barus, R. P. P., E-mail: rismawan.ppb@gmail.com [Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung and Centre for Material and Technical Product, Jalan Sangkuriang No. 14 Bandung (Indonesia); Tjokronegoro, H. A.; Leksono, E. [Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung (Indonesia); Ismunandar [Chemistry Study, Faculty of Mathematics and Science, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung (Indonesia)

    2014-09-25

    Fuel cells are promising new energy conversion devices that are friendly to the environment. A set of control systems are required in order to operate a fuel cell based power plant system optimally. For the purpose of control system design, an accurate fuel cell stack model in describing the dynamics of the real system is needed. Currently, linear model are widely used for fuel cell stack control purposes, but it has limitations in narrow operation range. While nonlinear models lead to nonlinear control implemnetation whos more complex and hard computing. In this research, nonlinear cancellation technique will be used to transform a nonlinear model into a linear form while maintaining the nonlinear characteristics. The transformation is done by replacing the input of the original model by a certain virtual input that has nonlinear relationship with the original input. Then the equality of the two models is tested by running a series of simulation. Input variation of H2, O2 and H2O as well as disturbance input I (current load) are studied by simulation. The error of comparison between the proposed model and the original nonlinear model are less than 1 %. Thus we can conclude that nonlinear cancellation technique can be used to represent fuel cell nonlinear model in a simple linear form while maintaining the nonlinear characteristics and therefore retain the wide operation range.

  6. Calculation of alternating current losses in stacks and coils made of second generation high temperature superconducting tapes for large scale applications

    DEFF Research Database (Denmark)

    Zermeno, Victor M. R.; Abrahamsen, Asger Bech; Mijatovic, Nenad; Jensen, Bogi Bech; Sørensen, Mads Peter

    2013-01-01

    A homogenization method to model a stack of second generation High Temperature Superconducting tapes under AC applied transport current or magnetic field has been obtained. The idea is to find an anisotropic bulk equivalent for the stack such that the geometrical layout of the internal alternatin...

  7. A hybrid microbial fuel cell stack based on single and double chamber microbial fuel cells for self-sustaining pH control

    Science.gov (United States)

    Yang, Wei; Li, Jun; Ye, Dingding; Zhang, Liang; Zhu, Xun; Liao, Qiang

    2016-02-01

    Proton accumulation in the anode chamber is the major problem that affects the operational stability and electricity generation performance of double chamber microbial fuel cells (MFCs). In this study, a hybrid microbial fuel cell stack (DS-DS stack) based on single (SCMFCs) and double chamber MFCs (DCMFCs) is proposed for self-sustaining pH control in the MFC stack. It is found that the aerobic microbial oxidation of acetate by the biofilm that is attached to the air cathode of SCMFCs is responsible for the self-sustaining removal of accumulated H+ in the effluent of DCMFCs. Compared with the stack that solely consists of SCMFCs (SS-SS stack) or DCMFCs (DD-DD stack), the hybrid stack exhibits the highest electricity output performance and the most effective conversion of acetate into electricity at high power levels. Furthermore, the hybrid stack demonstrates the operation time of 15.7 ± 1.1 h when the operating voltage is above 0.8 V. This value is much higher than that of the DD-DD (8.5 ± 2.4 h) and SS-SS (8.1 ± 1.4 h) stacks, which suggests that the hybrid stack had a good operational stability.

  8. Numerical study of a buoyant plume from a multi-flue stack into a variable temperature gradient atmosphere.

    Science.gov (United States)

    Velamati, Ratna Kishore; Vivek, M; Goutham, K; Sreekanth, G R; Dharmarajan, Santosh; Goel, Mukesh

    2015-11-01

    Air pollution is one of the major global hazards and industries have been one of its major contributors. This paper primarily focuses on analyzing the dispersion characteristics of buoyant plumes of the pollutant released from a multi-flue vertical stack into a variable temperature gradient atmosphere (α) in a constant-velocity cross wind using two stack configurations-inline and parallel. The study is conducted for different Froude numbers, Fr = 12.64, 9.55, and 8.27. The atmospheric temperature gradients considered for the study are 0, +1, +1.5, and +2 K/100 m. The numerical study is done using the commercial computational fluid dynamics (CFD) code FLUENT. The effects of stack configuration, α, and Fr on the plume characteristics are presented. It is observed that the plume rises higher and disperses over a larger area with the inline configuration due to better mixing and shielding effect. With higher α, it is seen that the plume rises initially and then descends due to variation of the buoyant force. The plume rise initially is strongly influenced by the momentum of the jet, and as it moves downstream, it is influenced by the cooling rate of the plume. Furthermore, the plume rises higher and disperses over a larger area with a decrease in Fr. PMID:26099599

  9. Low-temperature growth of multiple-stack high-density ZnO nanoflowers/nanorods on plastic substrates

    International Nuclear Information System (INIS)

    Reported here is the low-temperature growth of multiple-stack high-density ZnO nanoflower/nanorod structures on polyethylene naphthalate (PEN) substrates derived from the surface modification of ZnO seed layers using an atmospheric-pressure plasma jet (APPJ) treatment. The plasma treatment could provide several advantages to the growth of multiple-stack ZnO nanoflower/nanorod structures: (i) the surface wettability of the seed layers changes from hydrophobic to hydrophilic, resulting in higher surface energies for the growth of high-density ZnO nanoflowers, (ii) the nucleation sites increase due to the increased surface roughness caused by the plasma etching, and (iii) there is no thermal damage to the plastic substrate from the plasma treatment due to its low-temperature weakly ionized discharge. It was also confirmed that multiple stacks of ZnO nanoflowers were obtained without degradation of the crystal quality or modification to the crystal shape or phase. The ZnO nanoflower/nanorod structures grew by lengths up to 4 μm due to an increased surface roughness of 10% and surface energy 5.5 times that of the seed layers. As shown, the APPJ is a very good method to obtain high-density ZnO nanostructures on plastic substrates below 150 °C, as is critical for flexible electronics. (paper)

  10. Low-temperature growth of multiple-stack high-density ZnO nanoflowers/nanorods on plastic substrates

    Science.gov (United States)

    Kim, Do Yeob; Kim, Jae Young; Chang, Hyuk; Kim, Min Su; Leem, Jae-Young; Ballato, John; Kim, Sung-O.

    2012-12-01

    Reported here is the low-temperature growth of multiple-stack high-density ZnO nanoflower/nanorod structures on polyethylene naphthalate (PEN) substrates derived from the surface modification of ZnO seed layers using an atmospheric-pressure plasma jet (APPJ) treatment. The plasma treatment could provide several advantages to the growth of multiple-stack ZnO nanoflower/nanorod structures: (i) the surface wettability of the seed layers changes from hydrophobic to hydrophilic, resulting in higher surface energies for the growth of high-density ZnO nanoflowers, (ii) the nucleation sites increase due to the increased surface roughness caused by the plasma etching, and (iii) there is no thermal damage to the plastic substrate from the plasma treatment due to its low-temperature weakly ionized discharge. It was also confirmed that multiple stacks of ZnO nanoflowers were obtained without degradation of the crystal quality or modification to the crystal shape or phase. The ZnO nanoflower/nanorod structures grew by lengths up to 4 μm due to an increased surface roughness of 10% and surface energy 5.5 times that of the seed layers. As shown, the APPJ is a very good method to obtain high-density ZnO nanostructures on plastic substrates below 150 °C, as is critical for flexible electronics.

  11. On modifying the condition for the local current density decoupling in fuel cell stacks for moderate perturbations

    International Nuclear Information System (INIS)

    Two adjacent cells in a fuel cell stack are said to be decoupled when they do not affect each other's local current density distribution. This paper proposes a condition for local current density decoupling between two adjacent cells with arbitrary degree of perturbations. The proposed condition in the form of a bound comprising some measure of the perturbation on a dimensionless number comprising the design, operating conditions, and material properties of the bipolar plate is correlated with the current redistribution between cells and verified with a non-isothermal proton exchange membrane fuel cell stack model

  12. Monopolar fuel cell stack coupled together without use of top or bottom cover plates or tie rods

    Science.gov (United States)

    Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

    2009-01-01

    A monopolar fuel cell stack comprises a plurality of sealed unit cells coupled together. Each unit cell comprises two outer cathodes adjacent to corresponding membrane electrode assemblies and a center anode plate. An inlet and outlet manifold are coupled to the anode plate and communicate with a channel therein. Fuel flows from the inlet manifold through the channel in contact with the anode plate and flows out through the outlet manifold. The inlet and outlet manifolds are arranged to couple to the inlet and outlet manifolds respectively of an adjacent one of the plurality of unit cells to permit fuel flow in common into all of the inlet manifolds of the plurality of the unit cells when coupled together in a stack and out of all of the outlet manifolds of the plurality of unit cells when coupled together in a stack.

  13. A new stack effluent monitoring system at the Risoe Hot Cell plant

    International Nuclear Information System (INIS)

    This report describes a new stack effluent monitoring system that has been installed at the Hot Cell facility. It is an integrating iodine/particulate system consisting of a γ-shielded flow house in which a continous air sample from the ventilation channel ia sucked through coal and glass filter papers. Activity is accumulated on the filter papers and a thin plastic scintillator detects the β-radiation from the trapped iodine or particulate activity. The stack effluent monitoring system has a two-step regulating function as applied to the ventilation system, first switching it to a recirculating mode, and finally to building-seal after given releases of 131I. The collection efficiency for iodine in form of elementary iodine (I2) and methyliodide (CH3I) has been determined experimentally. The unwanted response from a noble gas release has also been determined from experiments. The noble gas response was determined from puff releases of the nuclide 41Ar in the concrete cells. It is concluded that the iodine/particulate system is extremely sensitive and that it can easily detect iodine or particulate releases as low as a few MBq. A gamma monitor placed in connection with the iodine/particulate system detects Xe/Kr-releases as low as a few tens of MBq per second. (author)

  14. Annealing temperature modulated interfacial chemistry and electrical characteristics of sputtering-derived HfO2/Si gate stack

    International Nuclear Information System (INIS)

    Sputtering-derived HfO2 high-k gate dielectric thin films have been deposited on Si substrate by means of high vacuum physics vapor deposition method. Via characterization from x-ray photoelectron spectroscopy (XPS) and electrical measurements, the effect of post-deposition annealing temperature on the interfacial and electrical properties of HfO2/Si gate stack has been investigated. XPS analyses show that an interfacial layer between HfO2 and silicon substrate has been found in the post-deposition annealing process. Increase in Hf-silicate layer and reduction in SiO2 low-k interface layer have been detected. Electrical measurements of MOS capacitor based on Al/HfO2/Si gate stacks indicate that annealing HfO2 sample at 300 °C demonstrated the improved electrical performance. As a result, the leakage current of 3.60 × 10−5 A/cm2 at applied substrate voltage of 2 V, which is much lower than those samples annealed at other temperature, has been obtained. The leakage current mechanism for different annealing temperature has been discussed systematically. - Highlights: • Sputtering-derived HfO2/Si gate stack has been deposited on Si substrate. • Annealing lead to the increase in Hf silicate layer and reduction in SiO2 interface layer. • For substrate injection, Schottky emission dominates the conduction mechanism at the low fields. • For gate injection, Poole–Frenkle emission dominates the conduction mechanism at the high field

  15. Annealing temperature modulated interfacial chemistry and electrical characteristics of sputtering-derived HfO{sub 2}/Si gate stack

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); School of Sciences, Anhui University of Science and Technology, Huainan 232001 (China); He, G., E-mail: ganghe01@issp.ac.cn [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); Zhang, J.W.; Deng, B.; Liu, Y.M. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China)

    2015-10-25

    Sputtering-derived HfO{sub 2} high-k gate dielectric thin films have been deposited on Si substrate by means of high vacuum physics vapor deposition method. Via characterization from x-ray photoelectron spectroscopy (XPS) and electrical measurements, the effect of post-deposition annealing temperature on the interfacial and electrical properties of HfO{sub 2}/Si gate stack has been investigated. XPS analyses show that an interfacial layer between HfO{sub 2} and silicon substrate has been found in the post-deposition annealing process. Increase in Hf-silicate layer and reduction in SiO{sub 2} low-k interface layer have been detected. Electrical measurements of MOS capacitor based on Al/HfO{sub 2}/Si gate stacks indicate that annealing HfO{sub 2} sample at 300 °C demonstrated the improved electrical performance. As a result, the leakage current of 3.60 × 10{sup −5} A/cm{sup 2} at applied substrate voltage of 2 V, which is much lower than those samples annealed at other temperature, has been obtained. The leakage current mechanism for different annealing temperature has been discussed systematically. - Highlights: • Sputtering-derived HfO{sub 2}/Si gate stack has been deposited on Si substrate. • Annealing lead to the increase in Hf silicate layer and reduction in SiO{sub 2} interface layer. • For substrate injection, Schottky emission dominates the conduction mechanism at the low fields. • For gate injection, Poole–Frenkle emission dominates the conduction mechanism at the high field.

  16. Segregation at stacking faults within the γ′ phase of two Ni-base superalloys following intermediate temperature creep

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, G. B. [The Ohio State Univ., Columbus, OH (United States); Shi, R. [The Ohio State Univ., Columbus, OH (United States); Genc, A. [FEI Company, Hillsboro, OR (United States); Vorontsov, V. A. [Univ. of Cambridge (United Kingdom); Kovarik, L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rae, C. M. F. [Univ. of Cambridge (United Kingdom); Mills, M. J. [The Ohio State Univ., Columbus, OH (United States)

    2015-01-01

    Using state-of-the-art energy dispersive spectroscopy, it has been established for the first time that there exists significant compositional variation (enrichment of Co and Cr and deficiency of Ni and Al) associated with superlattice intrinsic stacking faults created in the ordered γ' precipitates following intermediate temperature deformation of two commercial superalloys. The results indicate that long range diffusion of these elements is intimately involved in the precipitate shearing process and is therefore closely linked to the time-dependent deformation of the alloys.

  17. Experimental study on the 300W class planar type solid oxide fuel cell stack: Investigation for appropriate fuel provision control and the transient capability of the cell performance

    International Nuclear Information System (INIS)

    The present paper reports the experimental study on the dynamic behavior of a solid oxide fuel cell (SOFC). The cell stack consists of planar type cells with standard power output 300W. A Major subject of the present study is characterization of the transient response to the electric current change, assuming load-following operation. The present studies particularly focus on fuel provision control to the load change. Optimized fuel provision improves power generation efficiency. However, the capability of SOFC must be restricted by a few operative parameters. Fuel utilization factor, which is defined as the ratio of the consumed fuel to the supplied fuel is adopted for a reference in the control scheme. The fuel flow rate was regulated to keep the fuel utilization at 50%, 60% and 70% during the current ramping. Lower voltage was observed with the higher fuel utilization, but achieved efficiency was higher. The appropriate mass flow control is required not to violate the voltage transient behavior. Appropriate fuel flow manipulation can contribute to moderate the overshoot on the voltage that may appear to the current change. The overshoot on the voltage response resulted from the gradual temperature behavior in the SOFC stack module.

  18. Reducing the layer number of AB stacked multilayer graphene grown on nickel by annealing at low temperature

    Science.gov (United States)

    Marquez Velasco, J.; Giamini, S. A.; Kelaidis, N.; Tsipas, P.; Tsoutsou, D.; Kordas, G.; Raptis, Y. S.; Boukos, N.; Dimoulas, A.

    2015-10-01

    Controlling the number of layers of graphene grown by chemical vapor deposition is crucial for large scale graphene application. We propose here an etching process of graphene which can be applied immediately after growth to control the number of layers. We use nickel (Ni) foil at high temperature (T = 900 °C) to produce multilayer-AB-stacked-graphene (MLG). The etching process is based on annealing the samples in a hydrogen/argon atmosphere at a relatively low temperature (T = 450 °C) inside the growth chamber. The extent of etching is mainly controlled by the annealing process duration. Using Raman spectroscopy we demonstrate that the number of layers was reduced, changing from MLG to few-layer-AB-stacked-graphene and in some cases to randomly oriented few layer graphene near the substrate. Furthermore, our method offers the significant advantage that it does not introduce defects in the samples, maintaining their original high quality. This fact and the low temperature our method uses make it a good candidate for controlling the layer number of already grown graphene in processes with a low thermal budget.

  19. Investigation of InGaP/(In)AlGaAs/GaAs triple-junction top cells for smart stacked multijunction solar cells grown using molecular beam epitaxy

    Science.gov (United States)

    Sugaya, Takeyoshi; Mochizuki, Toru; Makita, Kikuo; Oshima, Ryuji; Matsubara, Koji; Okano, Yoshinobu; Niki, Shigeru

    2015-08-01

    We report high-quality InGaP/(In)AlGaAs/GaAs triple-junction solar cells fabricated using solid-source molecular beam epitaxy (MBE) for the first time. The triple-junction cells can be used as top cells for smart stacked multijunction solar cells. A growth temperature of 480 °C was found to be suitable for an (In)AlGaAs second cell to obtain high-quality tunnel junctions. The properties of AlGaAs solar cells were better than those of InAlGaAs solar cells when a second cell was grown at 480 °C. The high-quality InGaP/AlGaAs/GaAs solar cell had an impressive open-circuit voltage of 3.1 V. This result indicates that high-performance InGaP/AlGaAs/GaAs triple-junction solar cells can be fabricated using solid-source MBE.

  20. Mechanically Stacked Triple-junction GaInP / GaAs / Si Solar Cell Simulation

    Directory of Open Access Journals (Sweden)

    A.B. Gnilenko

    2014-01-01

    Full Text Available Mechanically stacked triple-junction GaInP / GaAs / Si solar cell is simulated by Silvaco TCAD computer software and compared to more conventional GaInP / GaAs / Ge mechanically stacked configuration. External quantum efficiency, I-V characteristics and basic I-V parameters are obtained to demonstrate the advantages of using the silicon active substrate as the bottom sub-cell instead of the germanium substrate based bottom sub-cell.

  1. Design of low power SRAM Cell with combined effect of sleep stack and variable body bias technique

    Directory of Open Access Journals (Sweden)

    Anjana R1 , Dr. Ajay kumar somkuwar

    2013-06-01

    Full Text Available Power consumption has become major concern in Very Large Scale Integration circuit and according to International technology roadmap of semiconductors (ITRS leakage power dissipation may dominate more of total power dissipation [1]. Sub threshold leakage power tends to increase as the leakage power increases. Variable sleepy biased keeper is compared with previously available technique like Sleep, Stack, Sleepy Stack, Sleepy Keeper, and Zigzag. In this paper, we design SRAM cell by combining two techniques, namely sleep stack and body biasing technique. The sleepy stack reduces leakage power, but loses its logic state during sleep mode. And body biasing technique reduces the static power consumption and maintains the logic state of the circuit. One main advantage of using variable sleepy biased keeper is, it can also use high Vth transistors

  2. Weibull strength variations between room temperature and high temperature Ni-3YSZ half-cells

    DEFF Research Database (Denmark)

    Curran, Declan; Frandsen, Henrik Lund; Hendriksen, Peter Vang

    2013-01-01

    800°C in a reducing atmosphere. The strength of an as sintered half-cell was also measured at room temperature for comparison. Weibull analysis was performed on large sample sets of 30 for statistical viability. The Weibull strength and elastic modulus of the room temperature tested reduced samples...... show a decrease of approximately 33% and 51% respectively, when compared to the oxidized samples tested at room temperature. When tested at elevated temperatures both Weibull strength and elastic modulus decrease further when compared to the room temperature reduced samples. However these further...... efficiency, increased degradation and/or the complete termination of a functioning stack. This paper investigates the effects of temperature on the mechanical strength of 3% yttria-stabilised zirconia half-cells. Strength was measured using a four-point bend method at room temperature and at 600°C, 700°C and...

  3. Post-experimental analysis of a solid oxide fuel cell stack using hybrid seals

    Science.gov (United States)

    Thomann, O.; Rautanen, M.; Himanen, O.; Tallgren, J.; Kiviaho, J.

    2015-01-01

    A post-experimental analysis of a SOFC stack is presented. The stack was operated for 1800 h at 700 °C with air and hydrogen and contained hybrid glass-Thermiculite 866 seals. The goal of this work was to investigate the sealing microstructure and possible corrosion during mid-term operation. It was found that hybrid seals could effectively compensate for manufacturing tolerances of cells and other components due to the compliance of the glass layer. Additionally, different interfaces were investigated for corrosion. Corrosion was not observed at two-phase interfaces such as Crofer 22 APU/glass, glass/electrolyte and glass/Thermiculite 866. The three-phase interface between Crofer 22 APU/glass/hydrogen exhibited no corrosion. Some evidence of non-systematic corrosion was found at the Crofer 22 APU/glass/air interface. The possible reasons for the corrosion are discussed. Lastly, dual exposure to humid hydrogen and air of the 0.2 mm Crofer 22 APU interconnect had no detrimental effect on the corrosion compared to air exposure. Overall the hybrid seals used in combination with the thin interconnects were found to be a promising solution due to the low leak rate and limited material interactions.

  4. Optimization of membrane stack configuration for efficient hydrogen production in microbial reverse-electrodialysis electrolysis cells coupled with thermolytic solutions.

    Science.gov (United States)

    Luo, Xi; Nam, Joo-Youn; Zhang, Fang; Zhang, Xiaoyuan; Liang, Peng; Huang, Xia; Logan, Bruce E

    2013-07-01

    Waste heat can be captured as electrical energy to drive hydrogen evolution in microbial reverse-electrodialysis electrolysis cells (MRECs) by using thermolytic solutions such as ammonium bicarbonate. To determine the optimal membrane stack configuration for efficient hydrogen production in MRECs using ammonium bicarbonate solutions, different numbers of cell pairs and stack arrangements were tested. The optimum number of cell pairs was determined to be five based on MREC performance and a desire to minimize capital costs. The stack arrangement was altered by placing an extra low concentration chamber adjacent to anode chamber to reduce ammonia crossover. This additional chamber decreased ammonia nitrogen losses into anolyte by 60%, increased the coulombic efficiency to 83%, and improved the hydrogen yield to a maximum of 3.5 mol H2/mol acetate, with an overall energy efficiency of 27%. These results improve the MREC process, making it a more efficient method for renewable hydrogen gas production. PMID:23711946

  5. Optimization of membrane stack configuration for efficient hydrogen production in microbial reverse-electrodialysis electrolysis cells coupled with thermolytic solutions

    KAUST Repository

    Luo, Xi

    2013-07-01

    Waste heat can be captured as electrical energy to drive hydrogen evolution in microbial reverse-electrodialysis electrolysis cells (MRECs) by using thermolytic solutions such as ammonium bicarbonate. To determine the optimal membrane stack configuration for efficient hydrogen production in MRECs using ammonium bicarbonate solutions, different numbers of cell pairs and stack arrangements were tested. The optimum number of cell pairs was determined to be five based on MREC performance and a desire to minimize capital costs. The stack arrangement was altered by placing an extra low concentration chamber adjacent to anode chamber to reduce ammonia crossover. This additional chamber decreased ammonia nitrogen losses into anolyte by 60%, increased the coulombic efficiency to 83%, and improved the hydrogen yield to a maximum of 3.5mol H2/mol acetate, with an overall energy efficiency of 27%. These results improve the MREC process, making it a more efficient method for renewable hydrogen gas production. © 2013 Elsevier Ltd.

  6. Thermal and water management of low temperature Proton Exchange Membrane Fuel Cell in fork-lift truck power system

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Rokni, Masoud; Rabbani, Raja Abid;

    2013-01-01

    stack and BOP has been investigated in this study. The results show that humidification of the inlet air is of great importance. By decreasing the relative humidity of inlet air from 95% to 25%, the voltage can drop by 29%. In addition, elevated stack temperature can lead to a higher average cell...

  7. Stacking Defects in Synthetic and Meteoritic Hibonites: Implications for High-Temperature Processes in the Solar Nebula

    Science.gov (United States)

    Han, J.; Keller, L. P.; Brearley, A. J.; Danielson, L. R.

    2016-01-01

    Hibonite (CaAl12O19) is a primary, highly refractory phase occurring in many Ca-Al-rich inclusions (CAIs) from different chondrite groups, except CI chondrites. Hibonite is predicted to be one of the earliest minerals to condense during cooling of the solar nebula at higher temperatures than any other major CAI mineral. Therefore, hibonite has great potential to reveal the processes and conditions of the very early, high-temperature stages of the solar nebular evolution. Previous microstructural studies of hibonite in CAIs and their Wark-Lovering (WL) rims showed the presence of numerous stacking defects in hibonite. These defects are interpreted as the modification of the stacking sequences of spinel and Ca-containing blocks within the ideal hexagonal hibonite structure, as shown by experimental studies of reaction-sintered ceramic CaO-Al2O3 compounds. We performed preliminary experiments in the CaO-Al2O3-MgO system to understand the formation processes and conditions of defect-structured hibonite found in meteorites.

  8. Fuel cells multi-stack power architectures and experimental validation of 1 kW parallel twin stack PEFC generator based on high frequency magnetic coupling dedicated to on board power unit

    International Nuclear Information System (INIS)

    This paper presents a study of a polymer electrolyte fuel cell (PEFC) multi-stack generator and its power electronic interface dedicated to an on board vehicle power unit. A parallel electric architecture has been designed and tested. First, a dynamic model of the PEFC stack, valid for high frequencies and compatible with power converter interactions, has been developed. This model is used for simulations of the global fuel cell and power converter behaviors. Second, an inventory of generic multi-stack fuel cells architectures is presented in order to couple electrically the fuel cell stacks to an on board DC bus (in series, parallel, through magnetic coupling..). This state of the art is completed by an overview of several candidate power converter topologies for fuel cells. Then, among all the possible technical solutions, an original power converter architecture using a high frequency planar transformer is proposed, which allows parallel and series magnetic couplings of two fuel cell stacks. Then, the study focuses on a first step, which is the association of two PEFC stacks. Such a structure, having good efficiency, is well adapted for testing and operation of fuel cells in normal and degraded working modes, which correspond to real constraints on board a vehicle. Finally, experimental validations on a 2 x 500 W twin stack PEFC with power converter interface demonstrate the technological feasibility for the embarked multi-stack fuel cells generator. The 1 kW power level chosen for the experimentation is close to that of a small on board PEFC auxiliary power unit (APU)

  9. Compact Design of 10 kW Proton Exchange Membrane Fuel Cell Stack Systems with Microcontroller Units

    Directory of Open Access Journals (Sweden)

    Hsiaokang Ma

    2014-04-01

    Full Text Available In this study, fuel, oxidant supply and cooling systems with microcontroller units (MCU are developed in a compact design to fit two 5 kW proton exchange membrane fuel cell (PEMFC stacks. At the initial stage, the testing facility of the system has a large volume (2.0 m × 2.0 m × 1.5 m with a longer pipeline and excessive control sensors for safe testing. After recognizing the performance and stability of stack, the system is redesigned to fit in a limited space (0.4 m × 0.5 m × 0.8 m. Furthermore, the stack performance is studied under different hydrogen recycling modes. Then, two similar 5 kW stacks are directly coupled with diodes to obtain a higher power output and safe operation. The result shows that the efficiency of the 5 kW stack is 43.46% with a purge period of 2 min with hydrogen recycling and that the hydrogen utilization rate µf is 66.31%. In addition, the maximum power output of the twin-coupled module (a power module with two stacks in electrical cascade/parallel arrangement is 9.52 kW.

  10. Reconstitution of vesiculated Golgi membranes into stacks of cisternae: requirement of NSF in stack formation

    OpenAIRE

    1995-01-01

    We have developed an in vitro system to study the biochemical events in the fusion of ilimaquinone (IQ) induced vesiculated Golgi membranes (VGMs) into stacks of cisternae. The Golgi complex in intact normal rat kidney cells (NRK) is vesiculated by treatment with IQ. The cells are washed to remove the drug and then permeabilized by a rapid freeze-thaw procedure. VGMs of 60 nm average diameter assemble into stacks of Golgi cisternae by a process that is temperature dependent, requires ATP and ...

  11. Experimental Dynamic Performance of a 30kW 90Cell PEFC Stack under Transportation Load Cycle Constraints

    OpenAIRE

    DE-BERNARDINIS, A; Harel, F.; Candusso, D.; Coquery, G.; GIRARDOT,L; Hissel, D.; Francois, X.; BESSE, S

    2009-01-01

    The paper presents a synthesis with analysis of different experiments performed on a 30kW PEFC (Polymer Electrolyte Fuel Cell) stack in order to evaluate its dynamic performance. The PEFC stack is a pilot prototype manufactured by the French company HELION and is composed of 90 cells, 800cm2 MEA area (Membrane Electrode Assembly) fed by dry hydrogen and compressed air. The tests were performed in the framework of the French SPACT-80 research project which concerns the study, the realization a...

  12. Solid oxide fuel cell anode degradation by the effect of hydrogen chloride in stack and single cell environments

    Science.gov (United States)

    Madi, Hossein; Lanzini, Andrea; Papurello, Davide; Diethelm, Stefan; Ludwig, Christian; Santarelli, Massimo; Van herle, Jan

    2016-09-01

    The poisoning effect by hydrogen chloride (HCl) on state-of-the-art Ni anode-supported solid oxide fuel cells (SOFCs) at 750 °C is evaluated in either hydrogen or syngas fuel. Experiments are performed on single cells and short stacks and HCl concentration in the fuel gas is increased from 1 ppm(v) up to 1000 ppm(v) at different current densities. Characterization methods such as cell voltage monitoring vs. time and electrochemical impedance response analysis (distribution of relaxation times (DRT), equivalent electrical circuit) are used to identify the prevailing degradation mechanism. Single cell experiments revealed that the poisoning is more severe when feeding with hydrogen than with syngas. Performance loss is attributed to the effects of HCl adsorption onto nickel surfaces, which lowered the catalyst activity. Interestingly, in syngas HCl does not affect stack performance even at concentrations up to 500 ppm(v), even when causing severe corrosion of the anode exhaust pipe. Furthermore, post-test analysis suggests that chlorine is present on the nickel particles in the form of adsorbed chlorine, rather than forming a secondary phase of nickel chlorine.

  13. The influence of strain rate, deformation temperature and stacking fault energy on the mechanical properties of Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Y.L. [Faculty of Science, Kunming University of Science and Technology, Kunming, Yunnan (China); Wen, C.E. [Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, John Street, Hawthorn, Victoria 3122 (Australia); Wu, X.X.; Ren, S.Y.; Cheng, L.P. [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan (China); Zhu, X.K., E-mail: xk_zhu@hotmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan (China)

    2013-10-20

    Cu–Ge alloys with different stacking fault energies (SFEs) were prepared by induction melting and processed by severe plastic deformation (SPD) using three different deformation techniques, including rolling at room temperature (RTR), rolling at the liquid nitrogen temperature (LNR), and Split Hopkinson Pressure Bar (SHPB) impact followed by room temperature rolling (HK+RTR). The effects of SFE, strain rate and deformation temperature on the microstructures and mechanical properties were systematically investigated by X-ray diffraction analyses and tensile tests. It was found that the dislocation density and twin density of all the Cu alloys after the SPD processing increased with decreasing SFE, increasing strain rate or reducing deformation temperature, which led to simultaneously enhanced strength and improved ductility due to effective grain refinement. The mechanical properties of the Cu alloys can be optimized to a combination of high strength and excellent ductility by lowering the SFE, the intrinsic property of metals, or manipulating the extrinsic deformation conditions, that is, increasing strain rate, and/or decreasing deformation temperature.

  14. Analysis and improvement of a scaled-up and stacked microbial fuel cell.

    Science.gov (United States)

    Dekker, Arjan; Ter Heijne, Annemiek; Saakes, Michel; Hamelers, Hubertus V M; Buisman, Cees J N

    2009-12-01

    Scaling up microbial fuel cells (MFCs) is inevitable when power outputs have to be obtained that can power electrical devices other than small sensors. This research has used a bipolar plate MFC stack of four cells with a total working volume of 20 L and a total membrane surface area of 2 m(2). The cathode limited MFC performance due to oxygen reduction rate and cell reversal. Furthermore, residence time distribution curves showed that bending membranes resulted in flow paths through which the catholyte could flow from inlet to outlet, while leaving the reactants unconverted. The cathode was improved by decreasing the pH, purging pure oxygen, and increasing the flow rate, which resulted in a 13-fold power density increase to 144 W m(-3) and a volumetric resistivity of only 1.2 mOmega m(3) per cell. Both results are major achievements compared to results currently published for laboratory and scaled-up MFCs. When designing a scaled-up MFC, it is important to ensure optimal contact between electrodes and substrate and to minimize the distances between electrodes. PMID:19943685

  15. Design and development of a 7kW polymer electrolyte membrane fuel cell stack for UPS application

    Energy Technology Data Exchange (ETDEWEB)

    Squadrito, G.; Giacoppo, G.; Barbera, O.; Urbani, F.; Passalacqua, E. [CNR - Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' (CNR-ITAE), Salita S. Lucia sopra Contesse 5, 98126 Messina (Italy); Borello, L.; Musso, A.; Rosso, I. [Electro Power Systems spa (EPS), Via Grange Palmero 104, 10091 Alpignano (Italy)

    2010-09-15

    This work presents the PEMFC stack design methodology developed at CNR-ITAE, in the frame of a collaboration with an industrial partner, Electro Power Systems (EPS), operating in the Uninterruptable Power Supply (UPS) market. A detailed description of the design procedure of a 7 kW PEMFC stack is reported, starting from technical requirements of the UPS system to experimental tests. Bipolar plate layout, active area surface and shape, maximum (OCV) and minimum voltage, maximum cooling circuit pressure drop, maximum cathodic flow-field pressure drop, were the main constraint that influenced the constructive solutions. The electrochemical performances of Gore Primea 5621 MEA with SGL Sigracet GDL were chosen as reference to select the appropriate operating point in terms of current density and single cell voltage. A current density of 800 mA/cm{sup 2} was imposed as operating point of the stack, subsequently main stack parameters were calculated. Three different cathodic flow fields, that were designed to fulfill UPS system requirements, were tested in a single cell arrangement, to find the best gas flow path in terms of compromise between cell performance and pressure drop. Also a specific study was dedicated to the selection of gasket material to find the best compromise between cell performance and limited mechanical stress. The assembled 70 cells unit was tested in a test bench simulating the power system. Preliminary tests of the full unit yielded to a power of 6.2kW at 36 V. (author)

  16. Low cost CuInSe2 thin films production by stacked elemental layers process for large area fabrication of solar cell application

    International Nuclear Information System (INIS)

    Highlights: ► CuInSe2 (CIS) thin film has deposited by stacked elemental layer technique (SEL). ► CuInSe2 phase have been obtained after annealing at temperature 350 °C. ► The structural, morphology and electrical properties have been obtained. ► The red shift in energy band gap of CIS thin films are found due to annealing. - Abstract: Low cost deposition of large area CuInSe2 (CIS) thin films have been grown on Mo-coated glass substrate by simple and economic stacked elemental layer deposition technique in vacuum. The grown parameters such as concentration of Cu, In and Se elements have been optimized to achieve uniform thin film in vacuum chamber. The as-grown Cu/In/Se stacked layers have been annealed at 200 °C and 350 °C for 1 h in air ambient. The as-grown and annealed films have been further subjected to characterization by X-ray diffraction (XRD), optical absorption, atomic force microscopy (AFM) and I–V measurement techniques. XRD patterns revealed that as-grown Cu/In/Se stacked layers represent amorphous nature while annealed CIS film reproduces nano-polycrystalline nature with chalcopyrite structure. The optical band gap of annealed films increases with respect to air annealing which confirms the reduction of crystallite size. Surface morphology of as-grown Cu/In/Se stacked layers and annealed CIS thin films have been confirmed by AFM images. The electrical measurements show enhancement of conductivity which is useful for solar cell application.

  17. In-situ diagnostic tools for hydrogen transfer leak characterization in PEM fuel cell stacks part II: Operational applications

    Science.gov (United States)

    Niroumand, Amir M.; Homayouni, Hooman; DeVaal, Jake; Golnaraghi, Farid; Kjeang, Erik

    2016-08-01

    This paper describes a diagnostic tool for in-situ characterization of the rate and distribution of hydrogen transfer leaks in Polymer Electrolyte Membrane (PEM) fuel cell stacks. The method is based on reducing the air flow rate from a high to low value at a fixed current, while maintaining an anode overpressure. At high air flow rates, the reduction in air flow results in lower oxygen concentration in the cathode and therefore reduction in cell voltages. Once the air flow rate in each cell reaches a low value at which the cell oxygen-starves, the voltage of the corresponding cell drops to zero. However, oxygen starvation results from two processes: 1) the electrochemical oxygen reduction reaction which produces current; and 2) the chemical reaction between oxygen and the crossed over hydrogen. In this work, a diagnostic technique has been developed that accounts for the effect of the electrochemical reaction on cell voltage to identify the hydrogen leak rate and number of leaky cells in a fuel cell stack. This technique is suitable for leak characterization during fuel cell operation, as it only requires stack air flow and voltage measurements, which are readily available in an operational fuel cell system.

  18. Synthesis of Stacked-Cup Carbon Nanotubes in a Metal Free Low Temperature System

    Science.gov (United States)

    Kimura, Yuki; Nuth, Joseph A.; Johnson, Natasha M.; Farmer, Kevin D.; Roberts, Kenneth P.; Hussaini, Syed R.

    2011-01-01

    Stacked-cup carbon nanotubes were formed by either Fischer-Tropsch type or Haber Bosch type reactions in a metal free system. Graphite particles were used as the catalyst. The samples were heated at 600 C in a gas mixture of CO 75 Torr, N2 75 Torr and H2 550 Torr for three days. Trans mission electron microscope analysis of the catalyst surface at the completion of the experiment recognized the growth of nanotubes. They were 10-50 nm in diameter and approximately 1 micrometer in length. They had a hollow channel of 5-20 nm in the center. The nanotubes may have grown on graphite surfaces by the CO disproportionation reaction and the surface tension of the carbon nucleus may have determined the diameter. Although, generally, the diameter of a carbon nanotube depends on the size of the cataly1ic particles, the diameter of the nanotubes on graphite particles was independent of the particle size and significantly confined within a narrow range compared with that produced using catalytic amorphous iron-silicate nanoparticles. Therefore, they must have an unknown formation process that is different than the generally accepted mechanism.

  19. Water recovery and air humidification by condensing the moisture in the outlet gas of a proton exchange membrane fuel cell stack

    International Nuclear Information System (INIS)

    Humidification is one of the most important factors for the operation of proton exchange membrane fuel cell (PEMFC). To maintain the membrane at hydrated state, plenty of water is needed for the state-of-the-art of PEMFC technology, especially in large power applications or long time operation. A condenser is introduced to separate liquid water from the air outlet for air self-sufficient in water of the stack in this study. The condensed temperature at the outlet of the condenser and water recovered amount for air self-sufficient in water are investigated theoretically and experimentally. It is shown that the condensed temperature for air self-sufficient in water is irrelevant with the working current of the stack. When the condenser outlet temperature was above the theoretical line, recovery water was not sufficient for the air humidification. On the contrary, it is sufficient while the temperature was below the theoretical line. It is also shown that when the moisture is sufficiently cooled, large amount water can be separated from the outlet gas, and it increased almost linearly with the time. With the introduction of the condenser, the recovered amount of water can easily satisfy the air self-sufficient in water by condensing the outlet gas to a proper temperature. - Highlights: ► We introduce a condenser to separate liquid water from the air outlet in the stack. ► The mechanism of air self-sufficient in water by condensing gas is presented. ► The condensed temperature and water recovered amount are investigated. ► An experiment is present to validate simplicity and feasibility of the criterion. ► The criterion for air humidification is used for choosing the condenser.

  20. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan;

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...

  1. Experimental Evaluation of a Pt-based Heat Exchanger Methanol Reformer for a HTPEM Fuel Cell Stack

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Nielsen, Mads Pagh

    2008-01-01

    automotive applications. Using a liquid hydrocarbon as e.g. methanol as the hydrogen carrier and reforming it to a hydrogen rich gas can solve some of these storage issues. The work presented here examines the use of a heat exchanger methanol reformer for use with a HTPEM fuel cell stack. Initial...

  2. Temperature dependent optical properties of stacked InGaAs/GaAs quantum rings

    International Nuclear Information System (INIS)

    In this paper we describe the results of temperature dependent photoluminescence intensity and decay time measurements of In(Ga)As/GaAs quantum rings where the depth of barrier is varied from sample to sample. The activation energy found for the reduction of the exciton decay time as a function of the temperature is approximately half the value of the thermionic escape energy of excitons. The temperature dependant behaviour is ascribed to the carriers lost via the excited state to the WL. The time resolved PL study indicates that thermal escape mechanisms is not so affected by reducing the spacer thickness, but it's influenced essentially by the excited state recombination

  3. Monitoring and modeling temperature variations inside silage stacks using novel wireless sensor networks

    DEFF Research Database (Denmark)

    Green, O.; Nadimi, E.S.; Blanes-Vidal, V.;

    2009-01-01

    of withstanding the high loads that occurred during ensiling, storage, and feed-out. Mathematical models estimating the relations between the silage temperatures (at depths of 25 and 50cm) and air and soil temperatures were obtained. Black-box modeling using the prediction error method (PEM) was selected...... as the identification method. Among different black-box models such as ARX, ARMAX, output-error (OE), and Box-Jenkins (BJ), with different model orders, a third-order Box-Jenkins model structure gave the best performance in terms of prediction accuracy. The success rate of the models proposed for silage temperature...

  4. The performance of a grid-tied microgrid with hydrogen storage and a hydrogen fuel cell stack

    International Nuclear Information System (INIS)

    Highlights: • Two microgrids with different structure are simulated. • Their performance are comprehensively evaluated and compared. • The one with DES and a FC stack has high environmental and quality indexes. - Abstract: In a heat-power system, the use of distributed energy generation and storage not only improves system’s efficiency and reliability but also reduce the emission. This paper is focused on the comprehensive performance evaluation of a grid-tied microgrid, which consists of a PV system, a hydrogen fuel cell stack, a PEM electrolyzer, and a hydrogen tank. Electricity and heat are generated in this system, to meet the local electric and heat demands. The surplus electricity can be stored as hydrogen, which is supplied to the fuel cell stack to generate heat and power as needed. The performance of the microgrid is comprehensively evaluated and is compared with another microgrid without a fuel cell stack. As a result, the emission and the service quality in the first system are higher than those in the second one. But they both have the same overall performance

  5. High temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    and motivated extensive research activity in the field. The last 11 chapters summarize the state-of-the-art of technological development of high temperature-PEMFCs based on acid doped PBI membranes including catalysts, electrodes, MEAs, bipolar plates, modelling, stacking, diagnostics and applications....

  6. Development of on-site PAFC stacks

    Energy Technology Data Exchange (ETDEWEB)

    Hotta, K.; Matsumoto, Y. [Kansai Electric Power Co., Amagasaki (Japan); Horiuchi, H.; Ohtani, T. [Mitsubishi Electric Corp., Kobe (Japan)

    1996-12-31

    PAFC (Phosphoric Acid Fuel Cell) has been researched for commercial use and demonstration plants have been installed in various sites. However, PAFC don`t have a enough stability yet, so more research and development must be required in the future. Especially, cell stack needs a proper state of three phases (liquid, gas and solid) interface. It is very difficult technology to keep this condition for a long time. In the small size cell with the electrode area of 100 cm{sup 2}, gas flow and temperature distributions show uniformity. But in the large size cell with the electrode area of 4000 cm{sup 2}, the temperature distributions show non-uniformity. These distributions would cause to be shorten the cell life. Because these distributions make hot-spot and gas poverty in limited parts. So we inserted thermocouples in short-stack for measuring three-dimensional temperature distributions and observed effects of current density and gas utilization on temperature.

  7. Temperature dependent optical properties of stacked InGaAs/GaAs quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Ouerghui, W. [Unite de Recherche Des Physiques des Semiconducteurs et Capteurs, Institut Preparatoire aux Etudes Scientifiques et Techniques, La Marsa 2070, Tunis (Tunisia)], E-mail: ouerghuiwalid@yahoo.fr; Martinez-Pastor, J.; Gomis, J. [Instituto de Ciencia de los Materials, Universidad de Valencia, P.O. Box 22085, 46071 Valencia (Spain); Maaref, M. [Unite de Recherche Des Physiques des Semiconducteurs et Capteurs, Institut Preparatoire aux Etudes Scientifiques et Techniques, La Marsa 2070, Tunis (Tunisia); Granados, D.; Garcia, J.M. [Instituto de Microelectronica de Madrid, Isaac newton 8, 28760 Tres Cantos, Madrid (Spain)

    2008-07-01

    In this paper we describe the results of temperature dependent photoluminescence intensity and decay time measurements of In(Ga)As/GaAs quantum rings where the depth of barrier is varied from sample to sample. The activation energy found for the reduction of the exciton decay time as a function of the temperature is approximately half the value of the thermionic escape energy of excitons. The temperature dependant behaviour is ascribed to the carriers lost via the excited state to the WL. The time resolved PL study indicates that thermal escape mechanisms is not so affected by reducing the spacer thickness, but it's influenced essentially by the excited state recombination.

  8. Computation of the time-averaged temperature fields and energy fluxes in a thermally isolated thermo-acoustic stack at low acoustic Mach numbers

    Energy Technology Data Exchange (ETDEWEB)

    Piccolo, A. [Department of Civil Engineering, University of Messina, Contrada di Dio - 98166 S. Agata (Messina) (Italy); Pistone, G. [Department of Matter Physics and Advanced Physical Technologies, University of Messina, Contrada Papardo, Salita Sperone, 31-98166 S. Agata (Messina) (Italy)

    2007-03-15

    A simplified calculus model to investigate on the transverse heat transport near the edges of a thermally isolated thermo-acoustic stack in the low acoustic Mach number regime is presented. The proposed methodology relies on the well-known results of the classical linear thermo-acoustic theory which are implemented into an energy balance calculus-scheme through a finite difference technique. Details of the time-averaged temperature and heat flux density distributions along a pore cross-section of the stack are given. It is shown that a net heat exchange between the fluid and the solid walls takes place only near the edges of the stack plates, at distances from the ends not exceeding the peak-to-peak particle displacement amplitude. The structure of the mean temperature field within a stack plate is also investigated; this last results not uniform near its terminations giving rise to a smaller temperature difference between the plate extremities than that predicted by the standard linear theory. This result, when compared with experimental measurements available in literature, suggests that thermal effects localized at the stack edges may play an important role as sources of the deviations found between linear theory predictions and experiments at low and moderate Mach numbers. (author)

  9. High efficiency,high power 808nm laser array and stacked arrays optimized for elevated temperature operation

    Institute of Scientific and Technical Information of China (English)

    Crump P A; Wise D; Crum T R; DeVito M; Farmer J; Grimshaw M; Huang Z; Igl S A; Macomber S; Thiagarajan P

    2004-01-01

    Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) threshold at elevated temperature range. We demonstrated high efficiency and high power operation at elevated temperature with high COMD power. These results were achieved through device design optimization such as growth conditions, doping profile, and materials composition of the quantum-well and other layers. Electrical-to-optical efficiency as high as 62% was obtained through lowered threshold current, lowered series resistance and increased slope efficiency. The performance of single broad-area laser diodes scales to that of high power single bars on water-cooled copper micro-channel heatsinks or conductively-cooled CS heatsinks. No reduction in bar performance or significant spectral broadening is seen when these micro-channel coolers are assembled into 6-bar and 18-bar CW stacks for the highest power levels.

  10. Doping Evolution and Junction Formation in Stacked Cyanine Dye Light-Emitting Electrochemical Cells.

    Science.gov (United States)

    Jenatsch, Sandra; Wang, Lei; Bulloni, Matia; Véron, Anna C; Ruhstaller, Beat; Altazin, Stéphane; Nüesch, Frank; Hany, Roland

    2016-03-16

    Cyanine dyes are fluorescent organic salts with intrinsic conductivity for ionic and electronic charges. Recently ( J. Am. Chem. Soc. 2013 , 135 , 18008 - 18011 ), these features have been exploited in cyanine light-emitting electrochemical cells (LECs). Here, we demonstrate that stacked, constant-voltage driven trimethine cyanine LECs with various counteranions develop a p-i-n junction that is composed of p- and n-doped zones and an intrinsic region where light-emission occurs. We introduce a method that combines spectral photocurrent response measurements with optical modeling and find that at maximum current the intrinsic region is centered at ∼37% away from the anode. Transient capacitance, photoluminescence and attenuance experiments indicate a device situation with a narrow p-doped region, an undoped region that occupies ∼72% of the dye layer thickness and an n-doped region with a maximum doping concentration of 0.08 dopant/cyanine molecule. Finally, we observe that during device relaxation the parent cyanines are not reformed. We ascribe this to irreversible reactions between doped cyanine radicals. For sterically conservative cyanine dyes, this suggests that undesired radical decomposition pathways limit the LEC long-term stability in general. PMID:26914281

  11. NOx conversion on LSM15-CGO10 cell stacks with BaO impregnation

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund; Andersen, Kjeld Bøhm; Kammer Hansen, Kent

    2012-01-01

    The electrochemical conversion of NOx on non-impregnated and BaO-impregnated LSM15-CGO10 (La0.85Sr0.15MnO3-Ce0.9Gd0.1O1.95) porous cell stacks has been investigated, and extensive impedance analysis have been performed to identify the effect of the BaO on the electrode processes. The investigation......O impregnation greatly enhanced the NOx conversion and at 400 degrees C and 9 V polarisation a BaO-impregnated cell stack showed 60% NOx conversion into N-2 with 8% current efficiency in 1000 ppm NO + 10% O-2. This demonstrates high NOx conversion can be achieved on an entirely ceramic cell without expensive...

  12. Experimental investigation of dynamic performance and transient responses of a kW-class PEM fuel cell stack under various load changes

    International Nuclear Information System (INIS)

    The dynamic performance is a very important evaluation index of proton exchange membrane (PEM) fuel cells used for real application, which is mostly related with water, heat and gas management. A commercial PEM fuel cell system of Nexa module is employed to experimentally investigate the dynamic behavior and transient response of a PEM fuel cell stack and reveal involved influential factors. Five groups of dynamic tests are conducted and divided into different stage such as start-up, shut-down, step-up load, regular load variation and irregular load variation. It is observed that the external load changes the current output proportionally and reverses stack voltage accordingly. The purge operation benefits performance recovery and enhancement during a constant load and its time strongly depends on the operational current level. Overshoot and undershoot behaviors are observed during transience. But the current undershoot does not appear due to charge double-layer effect. Additionally, magnitudes of the peaks of the voltage overshoot and undershoot vary at different current levels. The operating temperature responds fast to current load but changes slowly showing an arc-like profile without any overshoot and undershoot events. The air flow rate changes directly following the dynamic load demand. But the increased amount of air flow rate during different step-change is not identical, which depends on the requirement of internal reaction and flooding intensity. The results can be utilized for validation of dynamic fuel cell models, and regarded as reference for effective control and management strategies.

  13. Embedded LTPS flash cells with oxide-nitride-oxynitride stack structure for realization of multi-function mobile flat panel displays

    International Nuclear Information System (INIS)

    In this paper, embedded flash (eFlash) cells were fabricated for realization of multi-functions, such as systems on panels (SOPs) and threshold voltage (VTH) stabilization of flat panel displays (FPDs). Fabrication was via low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) technology and an oxide-nitride-oxynitride (ONOn) stack structure on glass. Poly-silicon (poly-Si) on glass, which was annealed via an excimer laser, has a very rough surface. To fabricate LTPS eFlash cells on glass with a very rough poly-Si surface, plasma-assisted oxynitridation was performed; nitrous oxide (N2O) served as a reactive gas. LTPS eFlash cells have excellent TFT electrical properties, such as VTH, a high On/Off current ratio and a low sub-threshold swing (S). The results demonstrate that eFlash cells fabricated on glass with a rough silicon surface, via an ONOn stack structure, have switching characteristics suitable for data storage, such as a low operating voltage (TH, which exceeds 2.3 V, between the programming and erasing (P/E) states, over a period of 10 years, and the capacity to retain the initial ΔVTH over a period of 105 P/E operations. (fast track communication)

  14. Embedded LTPS flash cells with oxide-nitride-oxynitride stack structure for realization of multi-function mobile flat panel displays

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sungwook; Kim, Jaehong; Son, Hyukjoo; Jang, Kyungsoo; Cho, Jaehyun; Kim, Kyunghae; Choi, Byoungdeog; Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)], E-mail: yi@yurim.skku.ac.kr

    2008-09-07

    In this paper, embedded flash (eFlash) cells were fabricated for realization of multi-functions, such as systems on panels (SOPs) and threshold voltage (V{sub TH}) stabilization of flat panel displays (FPDs). Fabrication was via low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) technology and an oxide-nitride-oxynitride (ONOn) stack structure on glass. Poly-silicon (poly-Si) on glass, which was annealed via an excimer laser, has a very rough surface. To fabricate LTPS eFlash cells on glass with a very rough poly-Si surface, plasma-assisted oxynitridation was performed; nitrous oxide (N{sub 2}O) served as a reactive gas. LTPS eFlash cells have excellent TFT electrical properties, such as V{sub TH}, a high On/Off current ratio and a low sub-threshold swing (S). The results demonstrate that eFlash cells fabricated on glass with a rough silicon surface, via an ONOn stack structure, have switching characteristics suitable for data storage, such as a low operating voltage (<{+-}10 V) suitable for mobile FPDs, a threshold voltage window, {delta}V{sub TH}, which exceeds 2.3 V, between the programming and erasing (P/E) states, over a period of 10 years, and the capacity to retain the initial {delta}V{sub TH} over a period of 10{sup 5} P/E operations. (fast track communication)

  15. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan; Gang, Xiao; Gao, Ji-An; Bjerrum, Niels

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...... temperature allows for utilization of the excess heat for fuel processing. Moreover, it provides an excellent CO tolerance of several percent, and the system needs no purification of hydrogen from a reformer. Continuous service for over 6 months at 150°C has been demonstrated....

  16. Low Temperature Deposition of High-k/Metal Gate Stacks on High-Sn Content (Si)GeSn-Alloys.

    Science.gov (United States)

    Schulte-Braucks, C; von den Driesch, N; Glass, S; Tiedemann, A T; Breuer, U; Besmehn, A; Hartmann, J-M; Ikonic, Z; Zhao, Q T; Mantl, S; Buca, D

    2016-05-25

    (Si)GeSn is an emerging group IV alloy system offering new exciting properties, with great potential for low power electronics due to the fundamental direct band gap and prospects as high mobility material. In this Article, we present a systematic study of HfO2/TaN high-k/metal gate stacks on (Si)GeSn ternary alloys and low temperature processes for large scale integration of Sn based alloys. Our investigations indicate that SiGeSn ternaries show enhanced thermal stability compared to GeSn binaries, allowing the use of the existing Si technology. Despite the multielemental interface and large Sn content of up to 14 atom %, the HfO2/(Si)GeSn capacitors show small frequency dispersion and stretch-out. The formed TaN/HfO2/(Si)GeSn capacitors present a low leakage current of 2 × 10(-8) A/cm(2) at -1 V and a high breakdown field of ∼8 MV/cm. For large Sn content SiGeSn/GeSn direct band gap heterostructures, process temperatures below 350 °C are required for integration. We developed an atomic vapor deposition process for TaN metal gate on HfO2 high-k dielectric and validated it by resistivity as well as temperature and frequency dependent capacitance-voltage measurements of capacitors on SiGeSn and GeSn. The densities of interface traps are deduced to be in the low 10(12) cm(-2) eV(-1) range and do not depend on the Sn-concentration. The new processes developed here are compatible with (Si)GeSn integration in large scale applications. PMID:27149260

  17. Effect of number of stack on the thermal escape and non-radiative and radiative recombinations of photoexcited carriers in strain-balanced InGaAs/GaAsP multiple quantum-well-inserted solar cells

    Science.gov (United States)

    Aihara, Taketo; Fukuyama, Atsuhiko; Suzuki, Hidetoshi; Fujii, Hiromasa; Sugiyama, Masakazu; Nakano, Yoshiaki; Ikari, Tetsuo

    2015-02-01

    Three non-destructive methodologies, namely, surface photovoltage (SPV), photoluminescence, and piezoelectric photothermal (PPT) spectroscopies, were adopted to detect the thermal carrier escape from quantum well (QW) and radiative and non-radiative carrier recombinations, respectively, in strain-balanced InGaAs/GaAsP multiple-quantum-well (MQW)-inserted GaAs p-i-n solar cell structure samples. Although the optical absorbance signal intensity was proportional to the number of QW stack, the signal intensities of the SPV and PPT methods decreased at high number of stack. To explain the temperature dependency of these signal intensities, we proposed a model that considers the three carrier dynamics: the thermal escape from the QW, and the non-radiative and radiative carrier recombinations within the QW. From the fitting procedures, it was estimated that the activation energies of the thermal escape ΔEb a r r and non-radiative recombination ΔEN R were 68 and 29 meV, respectively, for a 30-stacked MQW sample. The estimated ΔEb a r r value agreed well with the difference between the first electron subband and the top of the potential barrier in the conduction band. We found that ΔEb a r r remained constant at approximately 70 meV even with increasing QW stack number. However, the ΔENR value monotonically increased with the increase in the number of stack. Since this implies that non-radiative recombination becomes improbable as the number of stack increases, we found that the radiative recombination probability for electrons photoexcited within the QW increased at a large number of QW stack. Additional processes of escaping and recapturing of carriers at neighboring QW were discussed. As a result, the combination of the three non-destructive methodologies provided us new insights for optimizing the MQW components to further improve the cell performance.

  18. Effect of number of stack on the thermal escape and non-radiative and radiative recombinations of photoexcited carriers in strain-balanced InGaAs/GaAsP multiple quantum-well-inserted solar cells

    International Nuclear Information System (INIS)

    Three non-destructive methodologies, namely, surface photovoltage (SPV), photoluminescence, and piezoelectric photothermal (PPT) spectroscopies, were adopted to detect the thermal carrier escape from quantum well (QW) and radiative and non-radiative carrier recombinations, respectively, in strain-balanced InGaAs/GaAsP multiple-quantum-well (MQW)-inserted GaAs p-i-n solar cell structure samples. Although the optical absorbance signal intensity was proportional to the number of QW stack, the signal intensities of the SPV and PPT methods decreased at high number of stack. To explain the temperature dependency of these signal intensities, we proposed a model that considers the three carrier dynamics: the thermal escape from the QW, and the non-radiative and radiative carrier recombinations within the QW. From the fitting procedures, it was estimated that the activation energies of the thermal escape ΔEbarr and non-radiative recombination ΔENR were 68 and 29 meV, respectively, for a 30-stacked MQW sample. The estimated ΔEbarr value agreed well with the difference between the first electron subband and the top of the potential barrier in the conduction band. We found that ΔEbarr remained constant at approximately 70 meV even with increasing QW stack number. However, the ΔENR value monotonically increased with the increase in the number of stack. Since this implies that non-radiative recombination becomes improbable as the number of stack increases, we found that the radiative recombination probability for electrons photoexcited within the QW increased at a large number of QW stack. Additional processes of escaping and recapturing of carriers at neighboring QW were discussed. As a result, the combination of the three non-destructive methodologies provided us new insights for optimizing the MQW components to further improve the cell performance

  19. Effect of number of stack on the thermal escape and non-radiative and radiative recombinations of photoexcited carriers in strain-balanced InGaAs/GaAsP multiple quantum-well-inserted solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, Taketo; Fukuyama, Atsuhiko; Ikari, Tetsuo [Faculty of Engineering, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 889-2192 (Japan); Suzuki, Hidetoshi [Interdisciplinary Research Organization, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 889-2192 (Japan); Fujii, Hiromasa; Nakano, Yoshiaki [Research Center for Advanced Science and Technology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan); Sugiyama, Masakazu [School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2015-02-28

    Three non-destructive methodologies, namely, surface photovoltage (SPV), photoluminescence, and piezoelectric photothermal (PPT) spectroscopies, were adopted to detect the thermal carrier escape from quantum well (QW) and radiative and non-radiative carrier recombinations, respectively, in strain-balanced InGaAs/GaAsP multiple-quantum-well (MQW)-inserted GaAs p-i-n solar cell structure samples. Although the optical absorbance signal intensity was proportional to the number of QW stack, the signal intensities of the SPV and PPT methods decreased at high number of stack. To explain the temperature dependency of these signal intensities, we proposed a model that considers the three carrier dynamics: the thermal escape from the QW, and the non-radiative and radiative carrier recombinations within the QW. From the fitting procedures, it was estimated that the activation energies of the thermal escape ΔE{sub barr} and non-radiative recombination ΔE{sub NR} were 68 and 29 meV, respectively, for a 30-stacked MQW sample. The estimated ΔE{sub barr} value agreed well with the difference between the first electron subband and the top of the potential barrier in the conduction band. We found that ΔE{sub barr} remained constant at approximately 70 meV even with increasing QW stack number. However, the ΔE{sub NR} value monotonically increased with the increase in the number of stack. Since this implies that non-radiative recombination becomes improbable as the number of stack increases, we found that the radiative recombination probability for electrons photoexcited within the QW increased at a large number of QW stack. Additional processes of escaping and recapturing of carriers at neighboring QW were discussed. As a result, the combination of the three non-destructive methodologies provided us new insights for optimizing the MQW components to further improve the cell performance.

  20. A low-temperature fabricated gate-stack structure for Ge-based MOSFET with ferromagnetic epitaxial Heusler-alloy/Ge electrodes

    Science.gov (United States)

    Fujita, Yuichi; Yamada, Michihiro; Nagatomi, Yuta; Yamamoto, Keisuke; Yamada, Shinya; Sawano, Kentarou; Kanashima, Takeshi; Nakashima, Hiroshi; Hamaya, Kohei

    2016-06-01

    A possible low-temperature fabrication process of a gate-stack for Ge-based spin metal–oxide–semiconductor field-effect transistor (MOSFET) is investigated. First, since we use epitaxial ferromagnetic Heusler alloys on top of the phosphorous doped Ge epilayer as spin injector and detector, we need a dry etching process to form Heusler-alloy/n+-Ge Schottky-tunnel contacts. Next, to remove the Ge epilayers damaged by the dry etching process, the fabricated structures are dipped in a 0.03% diluted H2O2 solution. Finally, Al/SiO2/GeO2/Ge gate-stack structures are fabricated at 300 °C as a top gate-stack structure. As a result, the currents in the Ge-MOSFET fabricated here can be modulated by applying gate voltages even by using the low-temperature formed gate-stack structures. This low-temperature fabrication process can be utilized for operating Ge spin MOSFETs with a top gate electrode.

  1. Algebraic Stacks

    Indian Academy of Sciences (India)

    Tomás L Gómez

    2001-02-01

    This is an expository article on the theory of algebraic stacks. After introducing the general theory, we concentrate in the example of the moduli stack of vector bundles, giving a detailed comparison with the moduli scheme obtained via geometric invariant theory.

  2. Simulation of a tubular solid oxide fuel cell stack using AspenPlusTM unit operation models

    International Nuclear Information System (INIS)

    The design of a fuel cell system involves both optimization of the fuel cell stack and the balance of plant with respect to efficiency and economics. Many commercially available process simulators, such as AspenPlusTM, can facilitate the analysis of a solid oxide fuel cell (SOFC) system. A SOFC system may include fuel pre-processors, heat exchangers, turbines, bottoming cycles, etc., all of which can be very effectively modelled in process simulation software. The current challenge is that AspenPlusTM or any other commercial process simulators do not have a model of a basic SOFC stack. Therefore, to enable performing SOFC system simulation using one of these simulators, one must construct an SOFC stack model that can be implemented in them. The most common approach is to develop a complete SOFC model in a programming language, such as Fortran, Visual Basic or C++, first and then link it to a commercial process simulator as a user defined model or subroutine. This paper introduces a different approach to the development of a SOFC model by utilizing existing AspenPlusTM functions and existing unit operation modules. The developed ''AspenPlusTM SOFC'' model is able to provide detailed thermodynamic and parametric analyses of the SOFC operation and can easily be extended to study the entire power plant consisting of the SOFC and the balance of plant without the requirement for linking with other software. Validation of this model is performed by comparison to a Siemens-Westinghouse 100 kW class tubular SOFC stack. Sensitivity analyses of major operating parameters, such as utilization factor (Uf), current density (Ic) and steam-carbon ratio (S/C), were performed using the developed model, and the results are discussed in this paper

  3. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf

    The strategic developments of the FURIM are in three steps: (1) further improvement of the high temperature polymer membranes and related materials; (2) development of technological units including fuel cell stack, hydrocarbon reformer and afterburner, that are compatible with the HT-PEMFC; and (3...... hydrocarbon reformer and a catalytic burner are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability, conductivity, mechanical and other properties. For this purpose, basic polymers...

  4. Stress compensation by gap monolayers for stacked InAs/GaAs quantum dots solar cells

    OpenAIRE

    Alonso Alvarez, Diego; González Taboada, Alfonso; González Diez, M. Yolanda; Ripalda Cobián, Jose María; Alén Millán, Benito; González Soto, Luisa; García Martín, Jorge Miguel; Luque López, Antonio; Martí Vega, Antonio; Briones Fernández-Pola, Fernando; Sánchez, Almudena M.; Molina Rubio, Sergio Ignacio

    2008-01-01

    In this work we report the stacking of 10 and 50 InAs quantum dots layers using 2 monolayers of GaP for stress compensation and a stack period of 18 nm on GaAs (001) substrates. Very good structural and optical quality is found in both samples. Vertical alignment of the dots is observed by transmission electron microscopy suggesting the existence of residual stress around them. Photocurrent measurements show light absorption up to 1.2 μm in the nanostructures together with a reduction in the ...

  5. Current density and catalyst-coated membrane resistance distribution of hydro-formed metallic bipolar plate fuel cell short stack with 250 cm2 active area

    Science.gov (United States)

    Haase, S.; Moser, M.; Hirschfeld, J. A.; Jozwiak, K.

    2016-01-01

    An automotive fuel cell with an active area of 250 cm2 is investigated in a 4-cell short stack with a current and temperature distribution device next to the bipolar plate with 560 current and 140 temperature segments. The electrical conductivities of the bipolar plate and gas diffusion layer assembly are determined ex-situ with this current scan shunt module. The applied fuel cell consists of bipolar plates constructed of 75-μm-thick, welded stainless-steel foils and a graphitic coating. The electrical conductivities of the bipolar plate and gas diffusion layer assembly are determined ex-situ with this module with a 6% deviation in in-plane conductivity. The current density distribution is evaluated up to 2.4 A cm-2. The entire cell's investigated volumetric power density is 4.7 kW l-1, and its gravimetric power density is 4.3 kW kg-1 at an average cell voltage of 0.5 V. The current density distribution is determined without influencing the operating cell. In addition, the current density distribution in the catalyst-coated membrane and its effective resistivity distribution with a finite volume discretisation of Ohm's law are evaluated. The deviation between the current density distributions in the catalyst-coated membrane and the bipolar plate is determined.

  6. Optical properties of multi-stacked InGaAs/GaNAs quantum dot solar cell fabricated on GaAs (311)B substrate

    International Nuclear Information System (INIS)

    Quantum dot solar cells (QDSCs) comprised of 10 stacked pairs of strain-compensated InGaAs/GaNAs QD structure have been fabricated by atomic hydrogen-assisted molecular beam epitaxy. A homogeneous and high-density QD array structure with improved in-plane ordering and total density of ∼1012 cm−2 has been achieved on GaAs (311)B grown at 460 °C after stacking. The external quantum efficiency (EQE) of InGaAs/GaNAs QDSC increases in the longer wavelength range due to additive contribution from QD layers inserted in the intrinsic region. The short-circuit current density measured for QDSC is 17.2 mA/cm2 compared to 14.8 mA/cm2 of GaAs reference cell. Further, an increase in EQE due to photocurrent production by 2-step photon absorption has been observed at room temperature though it is still small at around 0.1%.

  7. CZTSe solar cells prepared by electrodeposition of Cu/Sn/Zn stack layer followed by selenization at low Se pressure.

    Science.gov (United States)

    Yao, Liyong; Ao, Jianping; Jeng, Ming-Jer; Bi, Jinlian; Gao, Shoushuai; He, Qing; Zhou, Zhiqiang; Sun, Guozhong; Sun, Yun; Chang, Liann-Be; Chen, Jian-Wun

    2014-01-01

    Cu2ZnSnSe4 (CZTSe) thin films are prepared by the electrodeposition of stack copper/tin/zinc (Cu/Sn/Zn) precursors, followed by selenization with a tin source at a substrate temperature of 530°C. Three selenization processes were performed herein to study the effects of the source of tin on the quality of CZTSe thin films that are formed at low Se pressure. Much elemental Sn is lost from CZTSe thin films during selenization without a source of tin. The loss of Sn from CZTSe thin films in selenization was suppressed herein using a tin source at 400°C (A2) or 530°C (A3). A copper-poor and zinc-rich CZTSe absorber layer with Cu/Sn, Zn/Sn, Cu/(Zn + Sn), and Zn/(Cu + Zn + Sn) with metallic element ratios of 1.86, 1.24, 0.83, and 0.3, respectively, was obtained in a selenization with a tin source at 530°C. The crystallized CZTSe thin film exhibited an increasingly (112)-preferred orientation at higher tin selenide (SnSe x ) partial pressure. The lack of any obvious Mo-Se phase-related diffraction peaks in the X-ray diffraction (XRD) diffraction patterns may have arisen from the low Se pressure in the selenization processes. The scanning electron microscope (SEM) images reveal a compact surface morphology and a moderate grain size. CZTSe solar cells with an efficiency of 4.81% were produced by the low-cost fabrication process that is elucidated herein. PMID:25593559

  8. Live-Cell Imaging of Dual-Labeled Golgi Stacks in Tobacco BY-2 Cells Reveals Similar Behaviors for Different Cisternae during Movement and Brefeldin A Treatment

    Institute of Scientific and Technical Information of China (English)

    Stephanie L. Madison; Andreas Nebenführ

    2011-01-01

    In plant cells,the Golgi apparatus consists of numerous stacks that,in turn,are composed of several flattened cisternae with a clear cis-to-trans polarity.During normal functioning within living cells,this unusual organelle displays a wide range of dynamic behaviors such as whole stack motility,constant membrane flux through the cisternae,and Golgi enzyme recycling through the ER.In order to further investigate various aspects of Golgi stack dynamics and integrity,we co-expressed pairs of established Golgi markers in tobacco BY-2 cells to distinguish sub-compartments of the Golgi during monensin treatments,movement,and brefeldin A (BFA)-induced disassembly.A combination of cis and trans markers revealed that Golgi stacks remain intact as they move through the cytoplasm.The Golgi stack orientation during these movements showed a slight preference for the cis side moving ahead,but trans cisternae were also found at the leading edge.During BFA treatments,the different sub-compartments of about half of the observed stacks fused with the ER sequentially; however,no consistent order could be detected.In contrast,the ionophore monensin resulted in swelling of trans cisternae while medial and particularly cis cisternae were mostly unaffected.Our results thus demonstrate a remarkable equivalence of the different cisternae with respect to movement and BFA-induced fusion with the ER.In addition,we propose that a combination of dual-label fluorescence microscopy and drug treatments can provide a simple alternative approach to the determination of protein localization to specific Golgi sub-compartments.

  9. Directly connected series coupled HTPEM fuel cell stacks to a Li-ion battery DC bus for a fuel cell electrical vehicle

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Ashworth, Leanne; Remón, Ian Natanael;

    2008-01-01

    connected directly parallel to the battery pack during operation. This enables efficient charging of the batteries for increased driving range. With no power electronics used, the fuel cell stacks follow the battery pack voltage, and charge the batteries passively. This saves the electrical and economical...

  10. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Li, Qingfeng

    Polymer electrolyte membrane fuel cell (PEMFC) technology based on Nafion membranes can operate at temperatures around 80°C. The new development in the field is high temperature PEMFC for operation above 100°C, which has been successfully demonstrated through the previous EC Joule III and the 5th...... system integration of the high temperature PEMFC. The strategic developments of the FURIM are in three steps: (1) further improvement of the high temperature polymer membranes and related materials; (2) development of technological units including fuel cell stack, hydrocarbon reformer, afterburner and......, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized and optimized. Different routes to functionalize the polymers will be explored to increate proton conductivity. By the development of advanced materials, demonstration of the high temperature PEMFC stack...

  11. Employing Hot Wire Anemometry to Directly Measure the Water Balance of a Commercial Proton Exchange Membrane Fuel Cell Stack

    DEFF Research Database (Denmark)

    Shakhshir, Saher Al; Berning, Torsten

    increased degradation rates. Clearly, a fundamental understanding of all aspects of water management in PEMFC is imperative. This includes the fuel cell water balance, i.e. which fraction of the product water leaves the fuel cell via the anode channels versus the cathode channel. Our research group is...... currently developing a novel technique to obtain an ad-hoc and real time electrical signal of the fuel cell water balance by employing hot wire anemometry. In this work, the hot wire sensor is placed in the anode outlet of a commercial air-cooled fuel cell stack by Ballard Power Systems, and the voltage......Proton exchange membrane fuel cells (PEMFC’s) are currently being commercialized for various applications ranging from automotive (e.g. the Toyota Mirai) to stationary such as powering telecom backup units. In PEMFC’s, oxygen from air is internally combined with hydrogen to form water and produce...

  12. Temperature modeling and control of Direct Methanol Fuel Cell based on adaptive neural fuzzy technology

    Institute of Scientific and Technical Information of China (English)

    Qi Zhidong; Zhu Xinjian; Cao Guangyi

    2006-01-01

    Aiming at on-line controlling of Direct Methanol Fuel Cell (DMFC) stack, an adaptive neural fuzzy inference technology is adopted in the modeling and control of DMFC temperature system. In the modeling process, an Adaptive Neural Fuzzy Inference System (ANFIS) identification model of DMFC stack temperature is developed based on the input-output sampled data, which can avoid the internal complexity of DMFC stack. In the controlling process, with the network model trained well as the reference model of the DMFC control system, a novel fuzzy genetic algorithm is used to regulate the parameters and fuzzy rules of a neural fuzzy controller. In the simulation, compared with the nonlinear Proportional Integral Derivative (PID) and traditional fuzzy algorithm, the improved neural fuzzy controller designed in this paper gets better performance, as demonstrated by the simulation results.

  13. Testing of a De Nora polymer electrolyte fuel cell stack of 1 kW for naval applications

    Science.gov (United States)

    Schmal, D.; Kluiters, C. E.; Barendregt, I. P.

    In a previous study calculations were carried out for a navy frigate with respect to the energy consumption of a propulsion/electricity generation system based on fuel cells. The fuel consumption for the 'all-fuel cell' ship was compared with the consumption of the current propulsion/electricity generation system based on gas turbines and diesel engines; it showed potential energy savings of a fuel cell based system amounting from 25 to 30%. On the basis of these results and taking into account various military aspects it was decided to start tests with a polymer electrolyte fuel cell (PEFC) stack. For this purpose a De Nora 1 kW PEFC was chosen. Results of the first tests after installation are satisfying.

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

    Science.gov (United States)

    Doherty, Wayne; Reynolds, Anthony; Kennedy, David

    2015-03-01

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

  15. Investigation of the flow field inside the manifold of a real operated fuel cell stack using optical measurements and Computational Fluid Mechanics

    Science.gov (United States)

    Schmieder, Felix; Kinaci, Mustafa E.; Wartmann, Jens; König, Jörg; Büttner, Lars; Czarske, Jürgen; Burgmann, Sebastian; Heinzel, Angelika

    2016-02-01

    The versatility of fuel cells enables a wide range of applications. Usually fuel cells are combined to stacks such that the reactant supply of the single cells is achieved via a pipe branching system, the manifold. The overall performance significantly depends on cell flow rates which are related to the fluidic interaction of the manifold and the cells. Computational Fluid Dynamics (CFD) simulations, which are often used to find a suitable design, lack experimental flow data for validation of the numerical results. To enable flow measurements within the small geometries of the manifold and to provide reliable velocity information inside a real fuel cell stack, a low-coherence Laser Doppler Anemometer (LDA) is applied, which uses multi-mode laser light to achieve a spatial resolution of <100 μm. The use of fluorescent particles and backward scatter mode make the sensor highly suitable for the application in small manifold geometries like in fuel cell stacks. Sensor and measurement technique are validated in simplified stack models and the applicability to air flows is demonstrated. Finally, for the first time, velocity profiles with high spatial resolution inside an operated fuel cell stack are presented, which serve as benchmark for CFD to find an optimal geometry.

  16. Evaluation of in-plane local stress distribution in stacked IC chip using dynamic random access memory cell array for highly reliable three-dimensional IC

    Science.gov (United States)

    Tanikawa, Seiya; Kino, Hisashi; Fukushima, Takafumi; Koyanagi, Mitsumasa; Tanaka, Tetsu

    2016-04-01

    As three-dimensional (3D) ICs have many advantages, IC performances can be enhanced without scaling down of transistor size. However, 3D IC has mechanical stresses inside Si substrates owing to its 3D stacking structure, which induces negative effects on transistor performances such as carrier mobility changes. One of the mechanical stresses is local bending stress due to organic adhesive shrinkage among stacked IC chips. In this paper, we have proposed an evaluation method for in-plane local stress distribution in the stacked IC chips using retention time modulation of a dynamic random access memory (DRAM) cell array. We fabricated a test structure composed of a DRAM chip bonded on a Si interposer with dummy Cu/Sn microbumps. As a result, we clarified that the DRAM cell array can precisely evaluate the in-plane local stress distribution in the stacked IC chips.

  17. Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Carrington, Peter James, E-mail: p.carrington@lancaster.ac.uk [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Mahajumi, Abu Syed [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Wagener, Magnus C.; Botha, Johannes Reinhardt [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Zhuang Qian; Krier, Anthony [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2012-05-15

    We report on the fabrication of GaAs based p-i-n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented.

  18. Theoretical and experimental analysis of high temperature solid oxide fuel cells (SOFC)

    OpenAIRE

    Restuccia, Giulio

    2008-01-01

    The technology of solid oxide fuel cells (SOFC) at high temperature represents a particularly promising solution in the realization of innovative systems for energetic conversion at high efficiency, in particular for systems destined to the distributed energetic production on small-medium scale. In such ambit has been carried out a theoretical analysis for the development of a one-dimensional simulation model of a solid oxide fuel cell stack, capable to predict the course and the variatio...

  19. Temperature and current dependencies of terahertz emission from stacks of intrinsic Josephson junctions with thin electrodes revealed by a high-resolution FT-IR spectrometer

    Science.gov (United States)

    Kakeya, Itsuhiro; Hirayama, Nobuo; Nakagawa, Takuto; Omukai, Yuta; Suzuki, Minoru

    2013-08-01

    We report on emission of electromagnetic wave in a frequency range of 1012 hertz (THz) from stacks of intrinsic Josephson junctions (IJJ) made of superconducting Bi2Sr2CaCu2O8+δ single crystals. A home-built high-resolution Fourier-transfer-infrared spectrometer reveals that the emission spectrum is monochromatic and the width is as sharp as its resolution limit (∼1 GHz). The THz emission is obtained in a broad temperature and current range depending on the mesa. The emission frequency is tuned from 0.55 to 0.45 THz by changing temperature from 20 to 55 K.

  20. An experimental study of the dynamic behavior of a 2 kW proton exchange membrane fuel cell stack under various loading conditions

    International Nuclear Information System (INIS)

    The dynamic behavior of the PEM (proton exchange membrane) fuel cell stack has great effect on the safety and effective operation of its applications. In this paper, a self-designed bulb-array is used to simulate the various loading conditions and study the dynamic behavior of a 2 kW PEM fuel cell stack. An evaluation index, including oscillation rate, pressure variation and dynamic resistance factor, is used to analyze the transient response of the PEM fuel cell stack. It is observed that the stack current increases about 8.6%, and the Oscillation rate decreases more rapidly after activation. In the step-up load stage, the oscillation rate and the dynamic resistance decrease more rapidly as the external load increases. Due to the periodic anodic purge process, a periodic voltage fluctuation can be seen. In addition, when the stack works in the open-loop state (working without the external load), the transient response of the stack current is significantly affected by the hydrogen humidity and the charge double-layer. - Highlights: • The working time of open-loop state significantly affects the transient response. • Oscillation rate decreases faster as the external load increases. • Dynamic resistance factor decreases as the external load increases. • The periodic anodic purge process leads to a slight periodic oscillation of voltage

  1. A review of high-temperature polymer electrolyte membrane fuel-cell (HT-PEMFC)-based auxiliary power units for diesel-powered road vehicles

    Science.gov (United States)

    Liu, Yongfeng; Lehnert, Werner; Janßen, Holger; Samsun, Remzi Can; Stolten, Detlef

    2016-04-01

    This paper presents an extensive review of research on the development of auxiliary power units with enhanced reformate tolerance for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Developments in diesel reforming for fuel cells as auxiliary power units (APUs), single fuel cells and stacks and systems are outlined in detail and key findings are presented. Summaries of HT-PEMFC APU applications and start-up times for HT-PEMFC systems are then given. A summary of cooling HT-PEMFC stacks using a classic schematic diagram of a 24-cell HT-PEMFC stack, with a cooling plate for every third cell, is also presented as part of a stack analysis. Finally, a summary of CO tolerances for fuel cells is given, along with the effects of different CO volume fractions on polarization curves, the fraction of CO coverage, hydrogen coverage, anode overpotential and cell potential.

  2. Understanding the effect of reformate gas components and stack component impurities on the performance of PEM fuel cells

    Science.gov (United States)

    Gu, Tao

    The performance can be lost depending on the concentration and type of reformate components. Gas crossover in PEMFCs can also cause performance loss and these effects are also presented. Impurities such as acetone coming from composite stack components and sealants can also deteriorate the performance severely. Electrochemical impedance spectroscopy (EIS) is used as a diagnostic tool to study the impurity poisoning. Reformate contains N2 and CO2 and these components affect performance differently. These effects were quantified using anode overvoltage. Data for anode overvoltage shows that CO2 yields a significant poisoning effect (about 30 mV) on a Pt electrode. Cyclic voltammetry (CV) data showed that CO was produced in-situ from CO2 and H 2 (reverse water gas shift (RWGS) reaction) on both Pt and Pt/Ru electrodes. The coverage of CO achieved by RWGS can reach 5 x 10-7 mol/cm2 on an electrode with 0.4 mg/cm2 Pt under open circuit with normal operating conditions. This work also investigated how pressure, gas composition, and temperature affect the RWGS reaction in a PEMFC for both Pt and Pt/Ru alloy catalysts. The data are shown to be consistent with a kinetic catalytic model and not with an equilibrium model. Data was presented on H2 and O2 crossover in PEMFCs. Electrochemical techniques and mass balance measurements were used to quantify the crossover under typical working conditions. Mixed potential theory was applied to analyze the effect of gas crossover on open circuit voltage (OCV) of PEMFCs. Off-gassing from bipolar plates previously identified styrene, acetone, t-butyl alcohol, and dimethyl succinate as impurities. The effects of those impurities were quantified with both poisoning-recovery transient curves and steady state VI curves before, during, and after poisoning on anode and cathode side respectively. The poisoning effects of them to the anode side are smaller than to the cathode side. Cyclic voltammetry and electrochemical impedance spectroscopy

  3. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf

    The new development in the field of polymer electrolyte membrane fuel cell (PEMFC) is high temperature PEMFC for operation above 100°C, which has been successfully demonstrated through the previous EC Joule III and the 5th framework programme. New challenges are encountered, bottlenecks for the new...... of the FURIM are in three steps: (1) further improvement of the high temperature polymer membranes and related materials; (2) development of technological units including fuel cell stack, hydrocarbon reformer and afterburner, that are compatible with the HT-PEMFC; and (3) integration of the HT...... catalytic burner are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-01

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

  5. Channeling of electron transport to improve collection efficiency in mesoporous titanium dioxide dye sensitized solar cell stacks

    Energy Technology Data Exchange (ETDEWEB)

    Fakharuddin, Azhar; Ahmed, Irfan; Yusoff, Mashitah M.; Jose, Rajan, E-mail: rjose@ump.edu.my, E-mail: joserajan@gmail.com [Nanostructured Renewable Energy Materials Laboratory, Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300 Pahang (Malaysia); Khalidin, Zulkeflee [Faculty of Electrical and Electronics Engineering, Universiti Malaysia Pahang, 26300 Pahang (Malaysia)

    2014-02-03

    Dye-sensitized solar cell (DSC) modules are generally made by interconnecting large photoelectrode strips with optimized thickness (∼14 μm) and show lower current density (J{sub SC}) compared with their single cells. We found out that the key to achieving higher J{sub SC} in large area devices is optimized photoelectrode volume (V{sub D}), viz., thickness and area which facilitate the electron channeling towards working electrode. By imposing constraints on electronic path in a DSC stack, we achieved >50% increased J{sub SC} and ∼60% increment in photoelectric conversion efficiency in photoelectrodes of similar V{sub D} (∼3.36 × 10{sup −4} cm{sup 3}) without using any metallic grid or a special interconnections.

  6. Performance of a 1 kW Class Nafion-PTFE Composite Membrane Fuel Cell Stack

    Directory of Open Access Journals (Sweden)

    Pattabiraman Krishnamurthy

    2012-01-01

    Full Text Available Composite membranes have been prepared by impregnation of Nafion into the expanded polytetrafluoroethylene (EPTFE matrix. Nafion loading in the composite membranes was kept constant at 2 mg/cm2. The lower amount of electrolyte per unit area in the composite membranes offers cost advantages compared to conventional membrane of 50 μm thickness with an electrolyte loading of ~9 mg/cm2. Composite membranes (30 μm thickness were found to have higher thermal stability and mechanical strength compared to the conventional membranes (50 μm thickness. The performance of the membrane electrode assembly made with these composite membranes was comparable to that of the conventional membranes. Single cells fabricated from these MEAs were tested for their performance and durability before scaling them up for large area. The performance of a 20-cell stack of active area 330 cm2 fabricated using these membranes is reported.

  7. Channeling of electron transport to improve collection efficiency in mesoporous titanium dioxide dye sensitized solar cell stacks

    International Nuclear Information System (INIS)

    Dye-sensitized solar cell (DSC) modules are generally made by interconnecting large photoelectrode strips with optimized thickness (∼14 μm) and show lower current density (JSC) compared with their single cells. We found out that the key to achieving higher JSC in large area devices is optimized photoelectrode volume (VD), viz., thickness and area which facilitate the electron channeling towards working electrode. By imposing constraints on electronic path in a DSC stack, we achieved >50% increased JSC and ∼60% increment in photoelectric conversion efficiency in photoelectrodes of similar VD (∼3.36 × 10−4 cm3) without using any metallic grid or a special interconnections

  8. 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

  9. Sustainable water desalination and electricity generation in a separator coupled stacked microbial desalination cell with buffer free electrolyte circulation.

    Science.gov (United States)

    Chen, Xi; Liang, Peng; Wei, Zhimou; Zhang, Xiaoyuan; Huang, Xia

    2012-09-01

    A separator coupled circulation stacked microbial desalination cell (c-SMDC-S) was constructed to stabilize the pH imbalances in MDCs without buffer solution and achieved the stable desalination. The long-term operation of c-SMDC-S, regular stacked MDC (SMDC) and no separator coupled circulation SMDC (c-SMDC) were tested. The SMDC and c-SMDC could only stably operate for 1 week and 1 month owing to dramatic anolyte pH decrease and serious biofilm growth on the air cathode, respectively. The c-SMDC-S gained in anolyte alkalinity and operated stably for about 60 days without the thick biofilm growth on cathode. Besides, the chemical oxygen demand removal and coulombic efficiency were 64 ± 6% and 30 ± 2%, higher than that of SMDC and c-SMDC, respectively. It was concluded that the circulation of alkalinity could remove pH imbalance while the separator could expand the operation period and promote the conversion of organic matter to electricity. PMID:22728187

  10. Air-Cooled Stack Freeze Tolerance Freeze Failure Modes and Freeze Tolerance Strategies for GenDriveTM Material Handling Application Systems and Stacks Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, David, W.

    2012-02-14

    Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below freezing, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was freeze tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology for air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve freeze tolerance and mitigate freeze-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. Freeze tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack freeze tolerance. At this time, the most cost effective solutions are at the system level. The freeze mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.

  11. Development and durability of SOFC stacks

    Energy Technology Data Exchange (ETDEWEB)

    Beeaff, D.; Dinesen, A.R.; Mikkelsen, Lars; Nielsen, Karsten A.; Solvang, M.; Hendriksen, Peter V.

    2004-12-01

    The present project is a part of the Danish SOFC programme, which has the overall aim of establishing a Danish production of SOFC - cells, stacks and systems for economical and environmentally friendly power production. The aim of the present project was to develop and demonstrate (on a small scale, few cells, few thousand hours) a durable, thermally cyclable stack with high performance at 750 deg. C. Good progress towards this target has been made and demonstrated at the level of stack-elements (one cell between two interconnects) or small stacks (3 5 cells). Three different stacks or stack-elements have been operated for periods exceeding 3000 hr. The work has covered development of stack-components (seals, interconnects, coatings, contact layers), establishment of procedures for stack assembly and initiation, and detailed electrical characterisation with the aims of identifying performance limiting factors as well as long term durability. Further, post test investigations have been carried out to identify possible degradation mechanisms. (BA)

  12. Charge–discharge performance of carbon fiber-based electrodes in single cell and short stack for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Highlights: • Carbon-fiber based electrodes are investigated in a zero-gap flow field cell configuration. • Charge–discharge curves are carried out in single cell and short stack for VRB application. • Three electrode half-cell data are corroborated both in single cell and short stack for VRB. - Abstract: Electrode materials, having a different graphitic character, are investigated by using a zero-gap flow field cell configuration for vanadium redox flow battery applications (VRFBs). Carbon felt (CF) and carbon paper (CP) are used as electrodes for the membrane–electrode assemblies (MEAs) realization. The samples are electrochemically characterized both as-received and after chemical treatment by using a 5 cm2 single cell. A Nafion 117 membrane is used as polymer electrolyte separators. A MEAs scale-up from 5 to 25 cm2 is carried out in order to assembly a 3-cells short stack in series connected. Charge–discharge cycles are carried out both in a small area single cell and in a 3-cells short stack for all samples. CF treated and untreated samples show SOC values of 45% vs. 22% at 60 mA cm−2, respectively. After the chemical treatment, the worst performance of the CF sample is attributed to the mass transport issues due to the beginning of corrosion phenomena. On the contrary, CP treated electrode shows a better energy efficiency values than raw sample (72% vs. 67% at 60 mA cm−2) without any morphology change on the electrode surface. A proper stack assembly and flow field scale-up record similar performance to the small single cell configuration

  13. Optimization of Al2O3/SiNx stacked antireflection structures for N-type surface-passivated crystalline silicon solar cells

    International Nuclear Information System (INIS)

    In the case of N-type solar cells, the anti-reflection property, as one of the important factors to further improve the energy-conversion efficiency, has been optimized using a stacked Al2O3/SiNx layer. The effect of SiNx layer thickness on the surface reflection property was systematically studied in terms of both experimental and theoretical measurement. In the stacked Al2O3/SiNx layers, results demonstrated that the surface reflection property can be effectively optimized by adding a SiNx layer, leading to the improvement in the final photovoltaic characteristic of the N-type solar cells. (semiconductor devices)

  14. Control and Experimental Characterization of a Methanol Reformer for a 350 W High Temperature Polymer Electrolyte Membrane Fuel Cell system

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Jensen, Hans-Christian Becker; Sahlin, Simon Lennart

    high temperature waste gas from a cathode air cooled 45 cell HTPEM fuel cell stack. The MEAs used are BASF P2100 which use phosphoric acid doped polybenzimidazole type membranes; an MEA with high CO tolerance and no complex humidity requirements. The methanol reformer used is integrated into a compact...... unit that allows the use of waste heat from the fuel cell stack in the reformer system, and a burner unit is also integrated to supplement provide heat using the stack anode hydrogen. The reformer is initially placed in an experimental system capable of emulating the interfaces to the fuel cell system...... and burner and the behaviour of the CO concentration of the reformate gas....

  15. 15-µm-pitch Cu/Au interconnections relied on self-aligned low-temperature thermosonic flip-chip bonding technique for advanced chip stacking applications

    Science.gov (United States)

    Thanh Tung, Bui; Kato, Fumiki; Watanabe, Naoya; Nemoto, Shunsuke; Kikuchi, Katsuya; Aoyagi, Masahiro

    2014-01-01

    In this paper, we report the development of reliable fine-pitch micro bump interconnections that used a high-precision room-temperature bonding approach. The accuracy of the bonding process is improved by modifying conventional bump/planar-bonding-pad interconnections to form self-aligned micro bumps/truncated inverted pyramid (TIP) bonding pads, i.e., misalignment self-correction elements (MSCEs). Thermosonic flip-chip bonding (FCB) is utilized to form reliable bonds between these MSCEs at acceptable low temperatures. By applying the proposed bonding approach, the demonstration of fine-pitch Cu bump to Au bonding pad interconnects chip stacking has been realized. Microstructure analyses reveal that 15-µm-pitch micro bump joints are fabricated at room temperature.

  16. Temperature and current dependencies of terahertz emission from stacks of intrinsic Josephson junctions with thin electrodes revealed by a high-resolution FT-IR spectrometer

    International Nuclear Information System (INIS)

    Highlights: ► Terahertz emission was found in Bi2212 mesas with electrodes thickness p is ∼0.5 THz. ► The linewidth of the emission was found to be less than 1 GHz. ► fp decreases up to 20% with increased temperature and bias current. -- Abstract: We report on emission of electromagnetic wave in a frequency range of 1012 hertz (THz) from stacks of intrinsic Josephson junctions (IJJ) made of superconducting Bi2Sr2CaCu2O8+δ single crystals. A home-built high-resolution Fourier-transfer-infrared spectrometer reveals that the emission spectrum is monochromatic and the width is as sharp as its resolution limit (∼1 GHz). The THz emission is obtained in a broad temperature and current range depending on the mesa. The emission frequency is tuned from 0.55 to 0.45 THz by changing temperature from 20 to 55 K

  17. Long-term evaluation of solid oxide fuel cell candidate materials in a 3-cell generic short stack fixture, Part II: sealing glass stability, microstructure and interfacial reactions.

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Y. S.; Stevenson, Jeffry W.; Choi, Jung-Pyung

    2014-03-15

    A generic solid oxide fuel cell stack test fixture was developed to evaluate candidate materials and processing methods under realistic conditions. Part I of the work addressed the stack fixture, seal system and cell performance of a 3-cell short stack tested at 800oC for 6000h. Commercial NiO-YSZ anode-supported thin YSZ electrolyte cells with LSM cathodes were used for assessment and were tested in constant current mode with dilute (~50% H2) fuel versus air. Part II of the work examined the sealing glass stability, microstructure development, interfacial reactions, and volatility issues. Part III of the work investigated the stability of Ce-(Mn,Co) spinel coating, AISI441 metallic interconnect, alumina coating, and cell degradation. After 6000h of testing, the refractory sealing glass YSO77 (Ba-Sr-Y-B-Si) showed desirable chemical compatibility with YSZ electrolyte in that no discernable interfacial reaction was identified, consistent with thermodynamic calculations. In addition, no glass penetration into the thin electrolyte was observed. At the aluminized AISI441 interface, the protective alumina coating appeared to be corroded by the sealing glass. Air side interactions appeared to be more severe than fuel side interactions. Metal species such as Cr, Mn, and Fe were detected in the glass, but were limited to the vicinity of the interface. No alkaline earth chromates were found at the air side. Volatility was also studied in a similar glass and weight loss in a wet reducing environment was determined. Using the steady-state volatility data, the life time (40,000h) weight loss of refractory sealing glass YSO77 was estimated to be less than 0.1 wt%.

  18. Cu2ZnSn(S,Se)4 solar cells processed by rapid thermal processing of stacked elemental layer precursors

    International Nuclear Information System (INIS)

    In this contribution we report on the development of a two-step process for the formation of Cu2ZnSn(S,Se)4 thin films for solar cells. The two-step formation process of the pentanary kesterite consists of (i) sputter deposition of the metals Cu, Zn and Sn followed by thermal evaporation of chalcogen and (ii) rapid thermal processing of the metal/chalcogen precursors in chalcogen containing ambient. After the absorber formation process, solar cells were processed by deposition of CdS buffer, window layer and metal grid. We evaluated different metal precursor compositions in the ternary Cu–Zn–Sn metal systems regarding their behavior as appropriate precursors for the crystallization of Cu2ZnSn(S,Se)4 absorbers. X-ray diffraction analyses show the presence of secondary chalcogenide phases in absorbers with Cu-poor composition. In combination with Raman spectroscopy, the efficient sulfoselenization could be demonstrated. A broad compositional region is found giving cell efficiencies above 6% via this process route and the potentials for further improvements are discussed. The best solar cell measured so far reached 6.6% efficiency on 1.34 cm2 cell size. - Highlights: ► Kesterite absorber layers via rapid thermal process from stacked elemental layers ► Relative sulfur content of 7–28% was deduced from Raman measurements. ► Identification of secondary phases via X-ray diffraction ► Best cell with 6.6% efficiency on a cell size of 1.34 cm2 ► Best cell performance was found for either low Cu-content or high Zn-content

  19. Research on high-power metal bipolar plate PEM fuel cell stack%高功率薄型金属双极板PEM燃料电池堆研究

    Institute of Scientific and Technical Information of China (English)

    王东; 王涛; 张伟; 刘向; 张新荣

    2009-01-01

    对高功率车用薄型金属双极板PEM燃料电池堆模块进行测试研究.电池堆模块可在空气压力110~300 kPa条件下工作,表现出良好的高、低压兼容特性.当空气压力300 kPa,电池堆温度70℃,工作电流350 A时,电池堆输出功率可达27.2 kW,其质量和体积比功率分别为777 W/kg和1 015 W/L.单电池电压方差求和计算结果显示,在工作电流50~120A的窗口区间内,单池电压具有相对最好的均匀一致性.在320A(约为1 A/cm~2)放电电流下,使用纯氢/氧气的电池堆输出功率比使用氢/空气高出约10%.空气相对湿度影响测试结果,电池堆较低功率下,空气的相对湿度80%~100%为佳;而当高功率下,空气相对湿度80%为佳.另外,对4单体薄型金属双极板燃料电池短堆进行耐久性测试,累计超过2 900 h,平均单池电压衰减率约为10 mV/1000 h.%In this paper, a thin metal bipolar-plate PEM fuel cell stack module for transportation was developed and validated. It was verified that the stack could be operated in a wide air pressure range from 110-300 kPa by air pressure compatibility test. The stack electrical power reached 27.2 kW operated at 350 A and 70 ℃ with 300 kPa pressurized air. So the mass specific power and volume specific power of the stack approached 777 W/kg and 1 015 W/L respectively. Variance analysis was adopted to evaluate the uniformity of individual cell voltages in the stack. The calculated results showed the stack had a lower cell to cell voltage variation at load current range from 50 A to 120 A. The stack electrical power operated using pure H_2 and O_2 was about 10% higher than using H_2 and air at a current of 320 A, which corresponds to the current density of 1 A/cm~2. In addition, durability test on the stack was performed for more than 2 900 h with a 4-cell short stack at a given test condition of temperature, pressure and stoichiometry by starting at 100 A. The durability test results indicated that the

  20. Preparation and Photovoltaic Properties of Dye Sensitized Solar Cells Using ZnO Nanorods Stacking Films on AZO Substrate as Photoanode.

    Science.gov (United States)

    Xu, Yang; Wang, Xina; Liu, Rong; Wang, Hao

    2016-04-01

    Three-dimensional stacking of ZnO nanorods on conducting aluminum-doped ZnO (AZO) glass were studied as efficient photoanodes of dye sensitized solar cells (DSSCs). By changing hydrothermal growth time and cycle times, the thickness of ZnO nanorods stacking films varied from 30 µm to 64 µm, and its influence on the energetic conversion efficiency of the DSSCs based on the stacking films photoanodes was investigated. The loading density of N719 on the surface of ZnO nanorods was studied to increase the efficiency of the cells. Annealing experiments showed that the AZO substrates remained good conductors until heated above 350 °C. A photoelectric conversion efficiency as high as ~2.0% together with ISC of ~9.5 mA/cm2, VOC of ~0.5 V and FF of ~41.4% was achieved for the DSSC using 50 µm-thick film stacking by ZnO nanorods as photoanode and N719 as sensitizer under illumination of AM1.5G solar light (power density of 100 mW/cm2). A charge separation and transfer mechanism was proposed for the ZnO nanorods stacking electrode-based DSSCs. PMID:27451677

  1. A novel method of hotspot temperature reduction for a 3D stacked CMOS IC chip device fabricated on an ultrathin substrate

    International Nuclear Information System (INIS)

    A high-performance thermal management method for three-dimensional integrated circuit (IC) integration has been developed for use in conjunction with a three-dimensional (3D) large-scale integration (LSI) technology. By depositing a 10 µm thick high thermal conductivity (HTC) film consisting of 1680 alternating layers of silicon and graphite nano-films directly onto the backside of a Si substrate via an automatic sequencing sputtering method, reduction in the transient hotspot temperature in a thin-substrate CMOS IC chip is achieved. It is shown that this novel HTC film is able to overcome the thermal problems associated with thin substrates and allow the cooling of stacked ICs. In the work described in this paper, we demonstrated the performance of the HTC using a 100 µm thick substrate IC chip consisting of a complementary metal-oxide semiconductor (CMOS) ring oscillator circuit film. Our experimental results, which were confirmed in simulation, reveal a 28% reduction in the hotspot temperature rise owing to the presence of the HTC film. This technology is applicable to future developments in the 3D ultrathin substrate LSI chip stacking technology utilizing through-silicon vias (TSVs) and micro-bumps. (paper)

  2. A novel method of hotspot temperature reduction for a 3D stacked CMOS IC chip device fabricated on an ultrathin substrate

    Science.gov (United States)

    Kato, Fumiki; Nakagawa, Hiroshi; Aoyagi, Masahiro

    2013-02-01

    A high-performance thermal management method for three-dimensional integrated circuit (IC) integration has been developed for use in conjunction with a three-dimensional (3D) large-scale integration (LSI) technology. By depositing a 10 µm thick high thermal conductivity (HTC) film consisting of 1680 alternating layers of silicon and graphite nano-films directly onto the backside of a Si substrate via an automatic sequencing sputtering method, reduction in the transient hotspot temperature in a thin-substrate CMOS IC chip is achieved. It is shown that this novel HTC film is able to overcome the thermal problems associated with thin substrates and allow the cooling of stacked ICs. In the work described in this paper, we demonstrated the performance of the HTC using a 100 µm thick substrate IC chip consisting of a complementary metal-oxide semiconductor (CMOS) ring oscillator circuit film. Our experimental results, which were confirmed in simulation, reveal a 28% reduction in the hotspot temperature rise owing to the presence of the HTC film. This technology is applicable to future developments in the 3D ultrathin substrate LSI chip stacking technology utilizing through-silicon vias (TSVs) and micro-bumps.

  3. Impact of power converter current ripple on the durability of a fuel cell stack

    OpenAIRE

    WAHDAME, B; GIRARDOT, L; Hissel, D.; Harel, F.; Francois, X.; Candusso, D.; PERA, MC; DUMERCY, L

    2008-01-01

    The durability and performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC) have a major impact on the most important challenges facing fuel cell commercialization including final cost, mass production, system integration, functionality and reliability. This work is supported by French Government via an ANR' project (PAN'H) named SPACT80. The global objective is to develop and validate the use of a fuel cell based power system for heavy-duty vehicles (dedicated to railway applications or...

  4. NASA Glenn Research Center's Fuel Cell Stack, Ancillary and System Test and Development Laboratory

    Science.gov (United States)

    Loyselle, Patricia L.; Prokopius, Kevin P.; Becks, Larry A.; Burger, Thomas H.; Dick, Joseph F.; Rodriguez, George; Bremenour, Frank; Long, Zedock

    2011-01-01

    At the NASA Glenn Research Center, a fully operational fuel cell test and evaluation laboratory is available which is capable of evaluating fuel cell components and systems for future NASA missions. Components and subsystems of various types can be operated and monitored under a variety of conditions utilizing different reactants. This fuel cell facility can test the effectiveness of various component and system designs to meet NASA's needs.

  5. Cell integrated multi-junction thermocouple array for solid oxide fuel cell temperature sensing: N+1 architecture

    Science.gov (United States)

    Ranaweera, Manoj; Kim, Jung-Sik

    2016-05-01

    Understanding the cell temperature distribution of solid oxide fuel cell (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFCs measure only the gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding a cell's performance and its temperature-related degradation. The authors propose a cell-integrated, multi-junction thermocouple array for in-situ cell surface temperature monitoring of an operational SOFC. The proposed thermocouple array requires far fewer numbers of thermoelements than that required by sets of thermocouples for the same number of temperature sensing points. Hence, the proposed array causes lower disturbance to cell performance than thermocouples. The thermoelement array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si - 95:2:2:1 by wt.) and chromel (Ni:Cr - 90:10 by wt.). The thermocouple array was tested in a furnace over the entire operating temperature range of a typical SOFC. The individual sensing points of the array were shown to measure temperature independently from each other with equivalent accuracy to a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.

  6. Sizing stack and battery of a fuel cell hybrid distribution truck

    NARCIS (Netherlands)

    Bosch, P.P.J. van den; Hofman, T.; Veenhuizen, Bram; Shen, Y.; Tazelaar, Edwin

    2012-01-01

    Fuel cell hybrid vehicles are believed to provide a solution to cut down emissions in the long term. They provide local zero-emission propulsion and when the hydrogen as fuel is derived from renewable energy sources, fuel cell hybrids enable well-to-wheel zero-emission transportation,

  7. Stability of long-period stacking ordered structures at elevated temperatures examined by multicolor synchrotron radiation X-ray scattering/diffraction measurements

    International Nuclear Information System (INIS)

    Stability of long-period stacking ordered (LPSO) structures of Mg-Zn-Y ternary alloys at elevated temperatures was examined by multicolor synchrotron radiation small- and medium-angle scattering/diffraction. The LPSO structures directly melted during heating, and the formation of LPSO was observed from supercooled liquid. The temperatures of complete dissolution and the onset of formation of LPSO phases were measured by monitoring the first diffraction peak of 14H, 18R and 10H compositional modulation. The stability of composition modulation in c axis direction was found to be the same as that of Ll2 cluster ordering in the segregation layer in both heating and cooling processes, i.e., dissolution and formation. Supercooling of LPSO was obtained for the heating/cooling rate of 10 K/min. (author)

  8. Long-term evaluation of solid oxide fuel cell candidate materials in a 3-cell generic short stack fixture, Part II: Sealing glass stability, microstructure and interfacial reactions

    Science.gov (United States)

    Chou, Yeong-Shyung; Stevenson, Jeffry W.; Choi, Jung-Pyung

    2014-03-01

    A generic solid oxide fuel cell stack test fixture was developed to evaluate candidate materials and processing methods under realistic conditions. Part II of the work examined the sealing glass stability, microstructure development, interfacial reaction, and volatility issues of a 3-cell stack with LSM-based cells. After 6000 h of testing, the refractory sealing glass YSO7 showed desirable chemical compatibility with YSZ electrolyte in that no discernable interfacial reaction was identified. In addition, no glass penetration into the thin electrolyte was observed. At the aluminized AISI441 interface, the protective alumina coating appeared to be corroded by the sealing glass. Air side interactions appeared to be more severe than fuel side interactions. Metal species such as Cr, Mn, and Fe were detected in the glass, but were limited to the vicinity of the interface. No alkaline earth chromates were found at the air side. Volatility was also studied in a similar glass and weight loss in a wet reducing environment was determined. Using the steady-state volatility data, the life time weight loss of refractory sealing glass YSO77 was estimated to be less than 0.1 wt%.

  9. A model-based approach for current voltage analyses to quantify degradation and fuel distribution in solid oxide fuel cell stacks

    Science.gov (United States)

    Linder, Markus; Hocker, Thomas; Meier, Christoph; Holzer, Lorenz; Friedrich, K. Andreas; Iwanschitz, Boris; Mai, Andreas; Schuler, J. Andreas

    2015-08-01

    Reliable quantification and thorough interpretation of the degradation of solid oxide fuel cell (SOFC) stacks under real conditions is critical for the improvement of its long-term stability. The degradation behavior is often analyzed based on the evolution of current-voltage (V,I) curves. However, these overall resistances often contain unavoidable fluctuations in the fuel gas amount and composition and hence are difficult to interpret. Studying the evolution of internal repeat unit (RU) resistances is a more appropriate measure to assess stack degradation. RU-resistances follow from EIS-data through subtraction of the gas concentration impedance from the overall steady-state resistance. In this work a model-based approach where a local equilibrium model is used for spatial discretization of a SOFC stack RU running on hydrocarbon mixtures such as natural gas. Since under stack operation, fuel leakages, uneven fuel distribution and varying natural gas composition can influence the performance, they are taken into account by the model. The model extracts the time-dependent internal resistance from (V,I)-data and local species concentration without any fitting parameters. RU resistances can be compared with the sum of the resistances of different components that allows one to make links between laboratory degradation experiments and the behavior of SOFC stacks during operation.

  10. Multi-stacked InAs/GaAs quantum dots grown with different growth modes for quantum dot solar cells

    International Nuclear Information System (INIS)

    We have studied the material properties and device performance of InAs/GaAs quantum dot solar cells (QDSCs) made using three different QD growth modes: Stranski-Krastanov (S-K), quasi-monolayer (QML), and sub-monolayer (SML) growth modes. All QDSCs show an extended external quantum efficiency (EQE) at near infrared wavelengths of 950–1070 nm from the QD absorption. Compared to the S-K and SML QDSCs, the QML QDSC with a higher strain exhibits a poor EQE response in the wavelength region of 300–880 nm due to increased non-radiative recombination. The conversion efficiency of the S-K and SML QDSCs exceeds that of the reference cell (13.4%) without QDs due to an enhanced photocurrent (>16% increase) produced by the silicon doped QD stacks. However, as expected from the EQE of the QML QDSC, the increase of strain-induced crystalline defects greatly degrades the photocurrent and open-circuit voltage, leading to the lowest conversion efficiency (8.9%)

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

    Science.gov (United States)

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

    2014-12-01

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

  12. Comprehensive molecular dynamics simulations of the stacking fault tetrahedron interacting with a mixed dislocation at elevated temperature

    Science.gov (United States)

    Fan, Haidong; Wang, Qingyuan; Ouyang, Chaojun

    2015-10-01

    The defect-free channels were frequently observed in irradiated materials, i.e. copper, as a result of the stacking fault tetrahedron (SFT) interactions with dislocations. However, the underlying mechanisms for this process are still unclear to date. To address them, a comprehensive study on the interactions between SFTs and mixed dislocations was performed using molecular dynamics simulations. In particular, eight interaction geometries were considered, in terms of the dislocation Burgers vector directions, dislocation gliding directions and intersection positions on SFT. Various interaction outcomes were revealed after dislocation detachment. (1) SFT is fully absorbed through the transformation into Lomer dislocations, and subsequently moves out of free surfaces along the dislocation. (2) SFT is partially absorbed with the absorbed SFT base moving out of free surfaces along the dislocation. (3) SFT is not absorbed but sheared with ledges left on the SFT faces. (4) SFT is unaffected by the mixed dislocation. The current simulations, especially the full SFT absorption, provide important insights into the forming mechanisms of defect-free channels in irradiated materials.

  13. 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 fuel cell (SOFC), in the electrolysis (SOEC) and in the reversible SOFC/SOEC mode are addressed. This covers the wide field of power generation systems, e.g. stationary SOFC µ-CHP, mobile SOFC APU and SOFC/SOEC power-to-gas systems. The paper presents the results which have been achieved so far...

  14. Self-stacked submersible microbial fuel cell (SSMFC) for improved remote power generation from lake sediments

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2012-01-01

    external resistance (≤400 Ω in this study) was applied. In addition, the internal resistance and OCV were the most important parameters for predicting which cell unit had the highest probability to undergo voltage reversal. Use of a capacitor was found to be an effective way to prevent voltage reversal and...

  15. 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 fuel cell (SOFC), in the electrolysis (SOEC) and in the reversible SOFC/SOEC mode are addressed. This covers the wide field of power generation systems, e.g. stationary SOFC µ-CHP, mobile SOFC APU and SOFC/SOEC power-to-gas systems. The paper presents the results which have been achieved so far in...

  16. High performance PEM fuel cells - from electrochemistry and material science to engineering development of a multicell stack. Monthly report No. 19

    Energy Technology Data Exchange (ETDEWEB)

    Appleby, A.J.; Inivasan, S.

    1996-07-01

    Several 50 sq cm MEAs were prepared to test the reproducibility of the authors techniques for electrodes and MEAs manufacture. At low current densities the performance of the cells is identical in the range of current densities of practical interest differences of up to 40 mV can be observed. During this month a four cell stack with MEAs provided by BCS Technology was assembled and tested. The MEAs were with electrodes with catalyst loading of 4.5 mg Pt/sq cm, area 50 sq cm, and Nafion(R) 112 membrane. The uncatalyzed gas diffusion substrate for these MEAs was provided by CESHR. The cell stack was operated with dry reactant gases at atmospheric pressure and at 50 deg C continuously for 600 hours at different power levels. The average cell voltage at a current density of 300 mA/sq cm was 0.61 V.

  17. High-Temperature Solar Cell Development

    Science.gov (United States)

    Landis, Geoffrey A.; Raffaelle, Ryne P.; Merritt, Danielle

    2004-01-01

    The vast majority of satellites and near-earth probes developed to date have relied upon photovoltaic power generation. If future missions to probe environments close to the sun will be able to use photovoltaic power, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. For example, the equilibrium temperature of a Mercury surface station will be about 450 C, and the temperature of solar arrays on the proposed "Solar Probe" mission will extend to temperatures as high as 2000 C (although it is likely that the craft will operate on stored power rather than solar energy during the closest approach to the sun). Advanced thermal design principles, such as replacing some of the solar array area with reflectors, off-pointing, and designing the cells to reflect rather than absorb light out of the band of peak response, can reduce these operating temperature somewhat. Nevertheless, it is desirable to develop approaches to high-temperature solar cell design that can operate under temperature extremes far greater than today's cells. Solar cells made from wide bandgap (WBG) compound semiconductors are an obvious choice for such an application. In order to aid in the experimental development of such solar cells, we have initiated a program studying the theoretical and experimental photovoltaic performance of wide bandgap materials. In particular, we have been investigating the use of GaP, SiC, and GaN materials for space solar cells. We will present theoretical results on the limitations on current cell technologies and the photovoltaic performance of these wide-bandgap solar cells in a variety of space conditions. We will also give an overview of some of NASA's cell developmental efforts in this area and discuss possible future mission applications.

  18. An investigation into the use of additive manufacture for the production of metallic bipolar plates for polymer electrolyte fuel cell stacks

    OpenAIRE

    Dawson, Richard; Patel, Anant; Rennie, Allan; White, Simon

    2015-01-01

    The bipolar plate is of critical importance to the efficient and long lasting operation of a polymer electrolyte fuel cell (PEMFC) stack. With advances in membrane electrode assembly design, greater attention has been focused on the bipolar plate and the important role it plays. Although carbon composite plates are a likely candidate for the mass introduction of fuel cells, it is metallic plates made from thin strip materials which could deliver significant advantages in terms of part cost, e...

  19. Modeling and simulation of high-temperature polymer electrolyte fuel cells; Modellierung und Simulation von Hochtemperatur-Polymerelektrolyt-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Kvesic, Mirko

    2012-07-01

    Fuel cells are electrochemical energy converters that convert chemical energy of constantly fed reactants directly into electricity. The most commonly used fuel gas in this respect is hydrogen, which is either produced in pure form by electrolysis, for example, or as a hydrogen-rich gas mixture (reformate gas), produced by reforming diesel or kerosene e.g. However, a disadvantage of reformate gas is that it contains additional carbon monoxide (CO), which leads to catalyst poisoning in the fuel cell. Since higher operating temperatures also lead to a higher CO tolerance, the use of high-temperature Polymer-Electrolyte-Fuel-Cells (HT-PEFCs) is particularly suitable for reformate operation. The aim of the presented work is the modeling and CFD-simulation of HT-PEFC stacks with the intention of gaining a better understanding of multi-physical processes in the stack operation as well as the optimization and analysis of existing stack designs. The geometric modeling used is based on the Porous Volume Model, which significantly reduces the required number of computing elements. Furthermore, the electrochemical models for hydrogen / air and reformate / air operation, which were taking the CO poisoning effects into account, are developed in this work and implemented in the software ANSYS / Fluent. The resulting simulations indicated the optimal flow configuration for the stack operation in terms of the homogeneous current density distribution, which has a positive effect on the stack aging. Thus, the current densities showed a strong homogeneity regarding the stack configuration anode / cathode in counter-flow and anode / cooling in co-flow. The influence of cooling strategies was examined for the stack performance in a similar way. In the following, the local temperature distribution as well as temperature peaks within the stack could be predicted and validated with experimental measurements. Further on, the model scalability and thus the general validity of the developed

  20. Optimization of a thermoelectric generator subsystem for high temperature PEM fuel cell exhaust heat recovery

    DEFF Research Database (Denmark)

    Gao, Xin; Andreasen, Søren Juhl; Kær, Søren Knudsen;

    2014-01-01

    In previous work, a thermoelectric (TE) exhaust heat recovery subsystem for a high temperature polymer electrolyte membrane (HT-PEM) fuel cell stack was developed and modeled. Numerical simulations were conducted and have identified an optimized subsystem configuration and 4 types of compact heat...... exchangers with superior performance for further analysis. In this work, the on-design performances of the 4 heat exchangers are more thoroughly assessed on their corresponding optimized subsystem configurations. Afterward, their off-design performances are compared on the whole working range of the fuel...... cell stack. All through this study, different electrical connection styles of all the thermoelectric generator (TEG) modules in the subsystem and their influences are also discussed. In the end, the subsystem configuration is further optimized and a higher subsystem power output is achieved. All TEG...

  1. Simulation and experiments of Stacks of High Temperature Superconducting Coated Conductors Magnetized by Pulsed Field Magnetization with Multi-Pulse Technique

    CERN Document Server

    Zou, Shengnan; Baskys, A; Patel, A; Grilli, Francesco; Glowacki, B A

    2016-01-01

    High temperature superconducting (HTS) bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (<2 T), so they show potential for improving the performance of many electrical applications that use permanent magnets like rotating machines. Towards practical or commercial use of TFMs, effective in situ magnetization is one of the key issues. The pulsed field magnetization (PFM) is among the most promising magnetization methods in virtue of its compactness, mobility and low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electrom...

  2. Stacked Cu1.8S nanoplatelets as Counter Electrode for Quantum Dot-Sensitized Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Savariraj, Dennyson A.; Rajendrakumar, G.; Selvam, Samayanan; Karthick, S. N.; Balamuralitharan, B.; Kim, Hee-Je; Viswanathan, Kodakkal K.; Vijayakumar, M.; Prabakar, Kandasamy

    2015-11-09

    It is found that electrocatalytic activity of Cu2-xS thin films used in quantum dots sensitized solar cells (QDSSC) as countner electrode (CE) for the reduction of polysulfide electrolyte depends on the the surface active sulfur species and defficiency of Cu. The preferential bonding between Cu2+ and S2- leading to the selective formation of Cu1.8S stacked platelets like morphology is determined by Cetyl Trimethyl Ammonium Bromide surfactant with temperature and crab like Cu-S coordination bond formed dictates the surface area to volume ratio of the Cu1.8S thin films and the electrocatalytic activity. The Cu deficiency enhances the conductivity of the Cu1.8S thin films and exhibits near- infrared localized surface plasmon resonanc due to free carrier intraband absorption and UV-VIS absorption spectra shows excitonic effect due to quantum size effect. When these Cu1.8S thin films were employed as CE in QDSSC, robust photoconversion efficiency of 5.2 % is yielded by the film deposited at 60°C by a sinlge step chemical bath deposition method.

  3. Treatment of colour industry wastewaters with concomitant bioelectricity production in a sequential stacked mono-chamber microbial fuel cells-aerobic system.

    Science.gov (United States)

    Fernando, Eustace; Keshavarz, Taj; Kyazze, Godfrey; Fonseka, Keerthi

    2016-01-01

    The scalability of any microbial fuel cell (MFC)-based system is of vital importance if it is to be utilized for potential field applications. In this study, an integrated MFC-aerobic bioreactor system was investigated for its scalability with the purpose of treating a simulated dye wastewater and industrial wastewaters originated from textile dyebaths and leather tanning. The influent containing real wastewater was fed into the reactor in continuous mode at ambient temperature. Three MFC units were integrated to act in unison as a single module for wastewater treatment and a continuously stirred aerobic bioreactor operating downstream to the MFC module was installed in order to ensure more complete degradation of colouring agents found in the wastewater. Total colour removal in the final effluent exceeded 90% in all experiments where both synthetic (AO-7 containing) and real wastewater were used as the influent feed. The chemical oxygen demand reduction also exceeded 80% in all experiments under the same conditions. The MFC modules connected in parallel configuration allowed obtaining higher current densities than that can be obtained from a single MFC unit. The maximum current density of the MFC stack reached 1150 mA m(-2) when connected in a parallel configuration. The outcome of this work implies that suitably up-scaled MFC-aerobic integrated bioprocesses could be used for colour industry wastewater treatment under industrially relevant conditions with possible prospects of bioelectricity generation. PMID:26212183

  4. Sobol's sensitivity analysis for a fuel cell stack assembly model with the aid of structure-selection techniques

    Science.gov (United States)

    Zhang, Wei; Cho, Chongdu; Piao, Changhao; Choi, Hojoon

    2016-01-01

    This paper presents a novel method for identifying the main parameters affecting the stress distribution of the components used in assembly modeling of proton exchange membrane fuel cell (PEMFC) stack. This method is a combination of an approximation model and Sobol's method, which allows a fast global sensitivity analysis for a set of uncertain parameters using only a limited number of calculations. Seven major parameters, i.e., Young's modulus of the end plate and the membrane electrode assembly (MEA), the contact stiffness between the MEA and bipolar plate (BPP), the X and Y positions of the bolts, the pressure of each bolt, and the thickness of the end plate, are investigated regarding their effect on four metrics, i.e., the maximum stresses of the MEA, BPP, and end plate, and the stress distribution percentage of the MEA. The analysis reveals the individual effects of each parameter and its interactions with the other parameters. The results show that the X position of a bolt has a major influence on the maximum stresses of the BPP and end plate, whereas the thickness of the end plate has the strongest effect on both the maximum stress and the stress distribution percentage of the MEA.

  5. Modelling of tandem cell temperature coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, D.J. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    This paper discusses the temperature dependence of the basic solar-cell operating parameters for a GaInP/GaAs series-connected two-terminal tandem cell. The effects of series resistance and of different incident solar spectra are also discussed.

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

    DEFF Research Database (Denmark)

    Harthøj, Anders

    of cobalt. The purpose of the cobalt was to act as a dense diffusion barrier for chromium in order to prevent chromium evaporation.  The coatings were deposited on the steels Crofer 22 APU and Crofer 22 H. The coatings were tested in a simulated cathode environment (air at 800, 820 or 850 °C). Coatings....... The area specific resistance (ASR) of a Ni/YSZ anode in contact and a preoxidized sample of Crofer 22 APU was measured in a simulated anode atmosphere. The ASR was very low (0.2 mΩcm2). It exhibited a temperature dependence typical for a metal. The microstructure of the Crofer 22 APU in the region affected...... by nickel diffusion was characterized with electron backscatter diffraction and other electron microscopy techniques.  The ASR of a Ni/YSZ anode with a CeO2 nickel diffusion barrier layer in contact with Crofer 22 APU was also measured and it was two orders of magnitude higher than without a CeO2 barrier...

  7. Demonstration of high efficiency intermediate-temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    International Nuclear Information System (INIS)

    The Kansai Electric Power Co., Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been jointly developing intermediate-temperature solid oxide fuel cells (SOFCs). The operation temperatures between 600 and 800 oC were set as the target, which enable SOFC to use less expensive metallic separators for cell-stacking and to carry out internal reforming of hydrocarbon fuels. The electrolyte-supported planar-type cells were fabricated using highly conductive lanthanum gallate-based electrolyte, La(Sr)Ga(Mg,Co)O3-δ, Ni-(CeO2)1-x(SmO1.5) x cermet anode, and Sm(Sr)CoO3-δ cathode. The 1 kW-class power generation modules were fabricated using a seal-less stack of the cells and metallic separators. The 1 kW-class prototype power generation system with the module was developed with the high performance cell, which showed the thermally self-sustainability. The system included an SOFC module, a dc-ac inverter, a desulfurizer, and a heat recovery unit. It provided stable ac power output of 1 kW with the electrical efficiency of 45% LHV based on ac output by using city gas as a fuel, which was considered to be excellent for such a small power generation system. And the hot water of 90 oC was obtained using high temperature off-gas from SOFC

  8. Temperature and thickness dependence of tunneling anisotropic magnetoresistance in exchange-biased Py/IrMn/MgO/Ta stacks

    Science.gov (United States)

    Reichlová, H.; Novák, V.; Kurosaki, Y.; Yamada, M.; Yamamoto, H.; Nishide, A.; Hayakawa, J.; Takahashi, H.; Maryško, M.; Wunderlich, J.; Marti, X.; Jungwirth, T.

    2016-07-01

    We investigate the thickness and temperature dependence of a series of Ni{}0.8Fe{}0.2/Ir{}0.2Mn{}0.8 bilayer samples with varying thickness ratio of the ferromagnet/antiferromagnet ({{t}}{{FM}}/{{t}}{{AFM}}) in order to explore the exchange coupling strengths in tunneling anisotropic magnetoresistance (TAMR) devices. Specific values of {{t}}{{FM}}/{{t}}{{AFM}} lead to four distinct scenarios with specific electric responses to moderate magnetic fields. The characteristic dependence of the measured TAMR signal on applied voltage allows us to confirm its persistence up to room temperature despite an overlapped contribution by a thermal magnetic noise.

  9. Temperature and current dependencies of terahertz emission from stacks of intrinsic Josephson junctions with thin electrodes revealed by a high-resolution FT-IR spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kakeya, Itsuhiro, E-mail: kakeya@kuee.kyoto-u.ac.jp [Department of Electronic Science and Engineering, Kyoto University, Nishikyo, Kyoto 615-8510 (Japan); Hirayama, Nobuo; Nakagawa, Takuto; Omukai, Yuta; Suzuki, Minoru [Department of Electronic Science and Engineering, Kyoto University, Nishikyo, Kyoto 615-8510 (Japan)

    2013-08-15

    Highlights: ► Terahertz emission was found in Bi2212 mesas with electrodes thickness <100 nm. ► We built an FT-IR spectrometer with the frequency resolution of ∼1 GHz. ► The spectrometer reveals that the emission frequency f{sub p} is ∼0.5 THz. ► The linewidth of the emission was found to be less than 1 GHz. ► f{sub p} decreases up to 20% with increased temperature and bias current. -- Abstract: We report on emission of electromagnetic wave in a frequency range of 10{sup 12} hertz (THz) from stacks of intrinsic Josephson junctions (IJJ) made of superconducting Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} single crystals. A home-built high-resolution Fourier-transfer-infrared spectrometer reveals that the emission spectrum is monochromatic and the width is as sharp as its resolution limit (∼1 GHz). The THz emission is obtained in a broad temperature and current range depending on the mesa. The emission frequency is tuned from 0.55 to 0.45 THz by changing temperature from 20 to 55 K.

  10. Thermal and water management of low temperature Proton Exchange Membrane Fuel Cell in fork-lift truck power system

    International Nuclear Information System (INIS)

    Highlights: ► Developing a general zero dimensional Proton Exchange Membrane Fuel Cell (PEMFC) model for a forklift. ► System performance with different cooling fluids. ► Water and thermal management of fuel cell system. ► Effect of inlet temperature, outlet temperature and temperature gradient on system performance. - Abstract: A general zero-dimensional Proton Exchange Membrane Fuel Cell (PEMFC) model has been developed for forklift truck application. The balance of plant (BOP) comprises of a compressor, an air humidifier, a set of heat exchangers and a recirculation pump. Water and thermal management of the fuel cell stack and BOP has been investigated in this study. The results show that humidification of the inlet air is of great importance. By decreasing the relative humidity of inlet air from 95% to 25%, the voltage can drop by 29%. In addition, elevated stack temperature can lead to a higher average cell voltage when membrane is fully hydrated otherwise it causes a drastic voltage drop in the stack. Furthermore, by substituting liquid water with water–ethylene glycol mixture of 50%, the mass flow of coolant increases by about 32–33% in the inner loop and 60–65% in the outer loop for all ranges of current. The system can then be started up at about −25 °C with negligible change in the efficiency

  11. 大跨叠箱渡槽施工期温度场测试及数值模拟研究%Temperature Field Test and Numerical Simulation of Large Span Stacked Box Aqueduct During Construction Period

    Institute of Scientific and Technical Information of China (English)

    董国桢

    2015-01-01

    以黔中水利焦家大跨叠式箱形渡槽为例,进行了温度场分布连续测试及相应的有限元数值模拟,系统研究了叠箱渡槽的温度分布特点,为大跨度叠箱渡槽的设计与施工提供技术支持。%Taking Jiaojia large span stacked box aqueduct of Qianzhong water conservancy project in Guizhou as an exam-ple,this paper made a continuous test on temperature field distribution and corresponding finite element numerical simula-tion,and then a systematic study on the temperature distribution characteristics of the stacked box aqueduct was made, which could provide a technical support for the design and construction of large span stacked box aqueduct.

  12. Effect of GeO2 deposition temperature in atomic layer deposition on electrical properties of Ge gate stack

    Science.gov (United States)

    Kanematsu, Masayuki; Shibayama, Shigehisa; Sakashita, Mitsuo; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

    2016-08-01

    We investigated the effect of GeO2 deposition temperature (T depo) on electronic properties of Al/Al2O3/GeO2/Ge MOS capacitors. Capacitance–voltage characteristics show frequency dispersions under depletion and strong inversion conditions, which can be attributed from the interface states at the atomic layer deposition (ALD)-GeO2/Ge interface and from the defect states in the quasi-neutral region in the Ge substrate, respectively. We found that the interface state density (D it) shows similar values and energy distributions as T depo decreases to 200 from 300 °C, while a higher D it is observed at a T depo of 150 °C. Also, from the temperature dependence of conductance, the frequency dispersion under the strong inversion condition can be related to the minority carrier diffusion to the quasi-neutral region of the Ge substrate. The frequency dependence of conductance reveals that the undesirable increment of the bulk defect density can be suppressed by decreasing T depo. In this study, the bulk defect density in a MOS capacitor prepared at a T depo of 200 °C decreases one tenth compared with that at a T depo of 300 °C. The ALD of GeO2 at a low temperature of around 200 °C is effective for both obtaining a low D it and preventing the undesirable introduction of bulk defect density.

  13. Experimental Study and Comparison of Various Designs of Gas Flow Fields to PEM Fuel Cells and Cell Stack Performance

    OpenAIRE

    PeiwenLi

    2014-01-01

    In this study, a significant number of experimental tests to proton exchange membrane (PEM) fuel cells were conducted to investigate the effect of gas flow fields on fuel cell performance. Graphite plates with various flow field or flow channel designs, from literature survey and also novel designs by the authors, were used for the PEM fuel cell assembly. The fabricated fuel cells have an effective membrane area of 23.5 cm2. The results showed that the serpentine flow channel design is still ...

  14. Top-down fabrication of very-high density vertically stacked silicon nanowire arrays with low temperature budget

    OpenAIRE

    Zervas, Michail; Sacchetto, Davide; De Micheli, Giovanni; Leblebici, Yusuf

    2011-01-01

    We report on a top-down complementary metal oxide semiconductor (CMOS) compatible fabrication method of ultra-high density Si nanowire (SiNW) arrays using a time multiplexed alternating process (TMAP) with low temperature budget. The flexibility of the fabrication methodology is demonstrated for curved and straight SiNW arrays with different shapes and levels. Ultra-high density SiNW arrays with round or rhombic cross-sections diameters as low as 10 nm are demonstrated for vertical and horizo...

  15. Layer-by-layer paper-stacking nanofibrous membranes to deliver adipose-derived stem cells for bone regeneration

    Directory of Open Access Journals (Sweden)

    Wan W

    2015-02-01

    Full Text Available Wenbing Wan,1–3,* Shiwen Zhang,2–4,* Liangpeng Ge,2,3,5 Qingtao Li,1 Xingxing Fang,1 Quan Yuan,4 Wen Zhong,6 Jun Ouyang,1 Malcolm Xing1,2,7 1Department of Anatomy, Guangdong Provincial Medical Biomechanical Key Laboratory, Southern Medical University, Guangzhou, People’s Republic of China; 2Department of Mechanical Engineering, University of Manitoba, Winnipeg, MB, Canada; 3Manitoba Institute of Child Health, Winnipeg, MB, Canada; 4Sichuan University, Chengdu, People’s Republic of China; 5Chongqing Academy of Animal Sciences, Chongqing, People’s Republic of China; 6Department of Textile Sciences, University of Manitoba, Winnipeg, MB, Canada; 7Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada *These authors contributed equally to this work Abstract: Bone tissue engineering through seeding of stem cells in three-dimensional scaffolds has greatly improved bone regeneration technology, which historically has been a constant challenge. In this study, we researched the use of adipose-derived stem cell (ADSC-laden layer-by-layer paper-stacking polycaprolactone/gelatin electrospinning nanofibrous membranes for bone regeneration. Using this novel paper-stacking method makes oxygen distribution, nutrition, and waste transportation work more efficiently. ADSCs can also secrete multiple growth factors required for osteogenesis. After the characterization of ADSC surface markers CD29, CD90, and CD49d using flow cytometry, we seeded ADSCs on the membranes and found cells differentiated, with significant expression of the osteogenic-related proteins osteopontin, osteocalcin, and osteoprotegerin. During 4 weeks in vitro, the ADSCs cultured on the paper-stacking membranes in the osteogenic medium exhibited the highest osteogenic-related gene expressions. In vivo, the paper-stacking scaffolds were implanted into the rat calvarial defects (5 mm diameter, one defect per parietal bone for 12 weeks. Investigating

  16. Control and experimental characterization of a methanol reformer for a 350 W high temperature polymer electrolyte membrane fuel cell system

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Sahlin, Simon Lennart

    2013-01-01

    This work presents a control strategy for controlling the methanol reformer temperature of a 350 W high temperature polymer electrolyte membrane fuel cell system, by using a cascade control structure for reliable system operation. The primary states affecting the methanol catalyst bed temperature...... is the water and methanol mixture fuel flow and the burner fuel/air ratio and combined flow. An experimental setup is presented capable of testing the methanol reformer used in the Serenergy H3 350 Mobile Battery Charger; a high temperature polymer electrolyte membrane (HTPEM) fuel cell system. The...... experimental system consists of a fuel evaporator utilizing the high temperature waste gas from the cathode air cooled 45 cell HTPEM fuel cell stack. The fuel cells used are BASF P1000 MEAs which use phosphoric acid doped polybenzimidazole membranes. The resulting reformate gas output of the reformer system is...

  17. High temperature polymer electrolyte membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    K.Scott; M. Mamlouk

    2006-01-01

    One of the major issues limiting the introduction of polymer electrolyte membrane fuel cells (PEMFCs) is the low temperature of operation which makes platinum-based anode catalysts susceptible to poisoning by the trace amount of CO, inevitably present in reformed fuel. In order to alleviate the problem of CO poisoning and improve the power density of the cell, operating at temperature above 100 ℃ is preferred. Nafion(R) -type perfluorosulfonated polymers have been typically used for PEMFC. However, the conductivity of Nafion(R) -type polymers is not high enough to be used for fuel cell operations at higher temperature ( > 90 ℃) and atmospheric pressure because they dehydrate under these condition.An additional problem which faces the introduction of PEMFC technology is that of supplying or storing hydrogen for cell operation,especially for vehicular applications. Consequently the use of alternative fuels such as methanol and ethanol is of interest, especially if this can be used directly in the fuel cell, without reformation to hydrogen. A limitation of the direct use of alcohol is the lower activity of oxidation in comparison to hydrogen, which means that power densities are considerably lower. Hence to improve activity and power output higher temperatures of operation are preferable. To achieve this goal, requires a new polymer electrolyte membrane which exhibits stability and high conductivity in the absence of liquid water.Experimental data on a polybenzimidazole based PEMFC were presented. A simple steady-state isothermal model of the fuel cell is also used to aid in fuel cell performance optimisation. The governing equations involve the coupling of kinetic, ohmic and mass transport. This paper also considers the advances made in the performance of direct methanol and solid polymer electrolyte fuel cells and considers their limitations in relation to the source and type of fuels to be used.

  18. Montagem e caracterização elétrica de pilhas a combustível de óxido sólido (PaCOS Assembly and electrical characterization of solid oxide fuel cell stacks

    Directory of Open Access Journals (Sweden)

    Hosane Aparecida Tarôco

    2009-01-01

    Full Text Available This paper is focused on a review of the design features and the electrochemistry characterization of anode-supported planar SOFC. Studies and results of metallic alloy interconnectors and recovery for protection against corrosion and for contact layer are showed. Moreover a discussion of examples of measurements of impedance spectrometry, according to the literature and our experimental results are made. For the anode supported fuel cells the power density varies from 0.1 to 0.5 Wcm², according to results in the literature (showed in this paper. For electrolyte supported fuel cell the power density can be 10 Wcm-2 for high temperatures. An English-Portuguese glossary of most used terms in SOFC stack is given for greater clarity and to introduce new terms to the reader.

  19. Numerical evaluation of various gas and coolant channel designs for high performance liquid-cooled proton exchange membrane fuel cell stacks

    International Nuclear Information System (INIS)

    A careful design of gas and coolant channel is essential to ensure high performance and durability of proton exchange membrane (PEM) fuel cell stack. The channel design should allow for good thermal, water and gas management whilst keeping low pressure drop. This study evaluates numerically the performance of various gas and coolant channel designs simultaneously, e.g. parallel, serpentine, oblique-fins, coiled, parallel-serpentine and a novel hybrid parallel-serpentine-oblique-fins designs. The stack performance and local distributions of key parameters are investigated with regards to the thermal, water and gas management. The results indicate that the novel hybrid channel design yields the best performance as it constitutes to a lower pumping power and good thermal, water and gas management as compared to conventional channels. Advantages and limitation of the designs are discussed in the light of present numerical results. Finally, potential application and further improvement of the design are highlighted. -- Highlights: ► We evaluate various gas and coolant channel designs in liquid-cooled PEM fuel cell stack. ► The model considers coupled electrochemistry, channel design and cooling effect simultaneously. ► We propose a novel hybrid channel design. ► The novel hybrid channel design yields the best thermal, water and gas management which is beneficial for long term durability. ► The novel hybrid channel design exhibits the best performance.

  20. Validation of a HT-PEMFC stack for CHP applications

    Energy Technology Data Exchange (ETDEWEB)

    Pasupathi, S.; Ulleberg, Oe. [Western Cape Univ. (South Africa). HySA Systems, SAIAMC; Bujlo, P. [Western Cape Univ. (South Africa). HySA Systems, SAIAMC; Electrotechnical Institute Wroclaw Division (Poland); Scholta, J. [Centre for Solar Energy and Hydrogen Research (ZSW) (Germany)

    2010-07-01

    Fuel cell systems are very attractive for stationary co-generation applications as they can produce heat and electricity efficiently in a decentralized and environmentally friendly manner. PEMFC stacks operating at temperatures above 120 C, specifically in the range of 140-180 C, are ideal for co-generation purposes. In this study, preliminary results from a HTPEMFC stack designed for CHP applications is presented and discussed. A short, five-cell, HT-PEMFC stack was assembled with Celtec- P-2100 MEAs and validated in terms of electrical performance. The stack was operated with hydrogen and air at 160 C and the utilization curves for anode and cathode were recorded for a wide range of gas utilization at a current density of 0.52 A/cm{sup 2}. The current voltage characteristic was measured at optimal utilization values at 160 C. A 1kW stack is assembled and is currently being validated for its performance under various operating conditions for use in CHP applications. (orig.)

  1. Evolution and interaction of twins, dislocations and stacking faults in rolled α-brass during nanostructuring at sub-zero temperature

    Directory of Open Access Journals (Sweden)

    Barna Roy

    2014-06-01

    Full Text Available The effect of cryorolling (CR strain at 153 K on the evolution of structural defects and their interaction in α−brass (Cu–30 wt.% Zn during nanostructuring has been evaluated. Even though the lattice strain increases up to 2.1 × 10−3 at CR strain of 0.6 initially, but it remains constant upon further rolling. Whereas, the twin density (β increases to a maximum value of 5.9 × 10−3 at a CR strain of 0.7 and reduces to 1.1 × 10−5 at 0.95. Accumulation of stacking faults (SFs and lattice disorder at the twin boundaries causes dynamic recrystallization, promotes grain refinement and decreases the twin density by forming subgrains. Detailed investigations on the formation and interaction of defects have been done through resistivity, positron lifetime and Doppler broadening measurements in order to understand the micro-mechanism of nanostructuring at sub-zero temperatures.

  2. High performance PEM fuel cells - from electrochemistry and material science to engineering development of a multicell stack. Quarterly report No. 6, April-June 1996

    Energy Technology Data Exchange (ETDEWEB)

    Appleyby, A.J.; Inivasan, S.

    1996-08-16

    To increase the electrocatalytic activity of the air electrode and simultaneously minimize the transport limitations, mixture of a 10 wt.% alloy supported on carbon and a high platinum loading (40 wt.%) on carbon was used as the electrocatalyst. The presence of the alloy electrocatalyst enhances the electrocatalytic activity at low current densities and the presence of the Pt electrocatalyst preserves the open structure of the electrode in this way the performance enhancement is evident over the entire range of current densities. This experiment was repeated with 20 micrometers thick GORE-SELECT (TM) membrane and a similar effect was observed. One 3-cell stack of area 50 sq cm was assembled at BCS Technology, Inc. with MEAs prepared using a Nafion 112 membrane and electrodes containing a Pt loading of 4.5 mg/sq cm. At 2.1 V (0.7 V per cell), the current density was about 0.48 A/sq cm with air and about 0.65 A/sq cm with oxygen. The cells required slight pressurization on the air side of the cell. The performance of the third cell was found to be slightly lower, and required a rapid flow (flushing) of hydrogen periodically. This problem did not result from the quality of the MEAs used, but was probably due to a design problem associated with stacking or the internal manifolding. The stack was tested at CESHR for performance verification and approximately the same performance was observed as that at BCS. However, problems similar to those noted at BCS were also seen at CESHR.

  3. Time-resolved photoluminescence for evaluating laser-induced damage during dielectric stack ablation in silicon solar cells

    Science.gov (United States)

    Parola, Stéphanie; Blanc-Pélissier, Danièle; Barbos, Corina; Le Coz, Marine; Poulain, Gilles; Lemiti, Mustapha

    2016-06-01

    Selective laser ablation of dielectric layers on crystalline silicon wafers was investigated for solar cell fabrication. Laser processing was performed on Al2O3, and bi-layers Al2O3/SiNX:H with a nanosecond UV laser at various energy densities ranging from 0.4 to 2 J cm-2. Ablation threshold was correlated to the simulated temperature at the interface between the dielectric coatings and the silicon substrate. Laser-induced damage to the silicon substrate was evaluated by time-resolved photoluminescence. The minority carrier lifetime deduced from time-resolved photoluminescence was related to the depth of the heat affected zone in the substrate.

  4. Gas and water management system in a 5 kW PEM fuel cell stack%5 kW质子交换膜燃料电池堆之气体与水管理系统

    Institute of Scientific and Technical Information of China (English)

    马小康; 郑为阳; 方富民

    2012-01-01

    A gas and water management system has been developed to increase the performance of the 5 kW proton exchange membrane fuel cell stack used for a small on board PEMFC auxiliary power unit(APU).The gas and water management system included four subsystems: oxidant supply subsystem,hydrogen supply subsystem,water cooling subsystem and control subsystem.The original design combined with excessive sensors and over-length pipes would cause the higher heat dissipation and decrease the inlet air temperature.The new compact design with less sensors and shorter pipe length could keep the higher inlet gas flow temperature and better performance of the fuel cell stack.In addition,stack performance could be influenced by the gas relative humidity and the hydrogen consumption under different loads.Hydrogen consumption under high load of 100 A might have 1.44 times more than that under low load of 10 A.Thus,the analysis of the hydrogen consumption under different loads and the gas relative humidity could help us to have an optimal design of the hydrogen recycling and increase the stack efficiency.Another 5 kW PEM fuel cell stack system is fabricated to couple with the original fuel cell stack system to have a 10 kW power output.The two stacks are electrically parallel or cascade;and the diodes are adopted in the circuit to avoid reverse current.The whole system should deliver a high power output stably in a long time because the performances of the two stacks are controlled to be almost identical to one another.The experimental results show that the stack ideal efficiency could reach 65.5% under the input air temperature of 51℃ and relative humidity of 54%.%开发了一个气体与水管理系统,藉以配合5kW质子交换膜燃料电池堆(Ballard 1310),使燃料电池的发电效率提升,并应用在小型运输工具之辅助动力装置(APU).气体与水管理系统包含4个子系统:氧化物供应系统、氢气供应系统、冷却系统与控制系统.

  5. Multibeam collimator uses prism stack

    Science.gov (United States)

    Minott, P. O.

    1981-01-01

    Optical instrument creates many divergent light beams for surveying and machine element alignment applications. Angles and refractive indices of stack of prisms are selected to divert incoming laser beam by small increments, different for each prism. Angles of emerging beams thus differ by small, precisely-controlled amounts. Instrument is nearly immune to vibration, changes in gravitational force, temperature variations, and mechanical distortion.

  6. Multilayer Piezoelectric Stack Actuator Characterization

    Science.gov (United States)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  7. Amorphous Silicon Carbide Passivating Layers to Enable Higher Processing Temperature in Crystalline Silicon Heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Boccard, Mathieu [Arizona State Univ., Mesa, AZ (United States); Holman, Zachary [Arizona State Univ., Mesa, AZ (United States)

    2015-04-06

    "Very efficient crystalline silicon (c-Si) solar cells have been demonstrated when thin layers of intrinsic and doped hydrogenated amorphous silicon (a-Si:H) are used for passivation and carrier selectivity in a heterojunction device. One limitation of this device structure is the (parasitic) absorption in the front passivation/collection a-Si:H layers; another is the degradation of the a-Si:H-based passivation upon temperature, limiting the post-processes to approximately 200°C thus restricting the contacting possibilities and potential tandem device fabrication. To alleviate these two limitations, we explore the potential of amorphous silicon carbide (a-SiC:H), a widely studied material in use in standard a-Si:H thin-film solar cells, which is known for its wider bandgap, increased hydrogen content and stronger hydrogen bonding compared to a-Si:H. We study the surface passivation of solar-grade textured n-type c-Si wafers for symmetrical stacks of 10-nm-thick intrinsic a-SiC:H with various carbon content followed by either p-doped or n-doped a-Si:H (referred to as i/p or i/n stacks). For both doping types, passivation (assessed through carrier lifetime measurements) is degraded by increasing the carbon content in the intrinsic a-SiC:H layer. Yet, this hierarchy is reversed after annealing at 350°C or more due to drastic passivation improvements upon annealing when an a-SiC:H layer is used. After annealing at 350°C, lifetimes of 0.4 ms and 2.0 ms are reported for i/p and i/n stacks, respectively, when using an intrinsic a-SiC:H layer with approximately 10% of carbon (initial lifetimes of 0.3 ms and 0.1 ms, respectively, corresponding to a 30% and 20-fold increase, respectively). For stacks of pure a-Si:H material the lifetimes degrade from 1.2 ms and 2.0 ms for i/p and i/n stacks, respectively, to less than 0.1 ms and 1.1 ms (12-fold and 2-fold decrease, respectively). For complete solar cells using pure a-Si:H i/p and i/n stacks, the open-circuit voltage (Voc

  8. Novel Low Temperature Solid State Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chonglin; Nash, Patrick; Liu, Jian; Collins, Gregory

    2009-12-15

    We have successfully fabricated (PrBa)Co{sub 2}O{sub 5+{delta}} and (LaBa)Co{sub 2}O{sub 5+{deleta}} epitaxial thin film on various single crystal substrates. Physical and electrochemical properties characterizations were carried out. Highly conductive oxygen-deficient double perovskite LnBaCo2O5+? thin films were grown on single crystal (001) SrTiO{sub 3} (STO), (001) MgO, (001) LaAlO{sub 3} and (110) NdGaO{sub 3} substrate by pulsed laser deposition. Microstructure studies from synchrotron X-ray diffraction and Transmission electron microscopy. High temperature transport properties was carried in different atmosphere (O{sub 2},Air, N{sub 2}) up to ~900K. Resistance response of (LaBa)Co{sub 2}O{sub 5+{delta}} epitaxial thin film was characterized in oxygen, nitrogen and 4% hydrogen over a wide range of temperature from 400�C up to 800�C. To determine the electrode performance and oxygen exchange kinetics of PrBaCo{sub 2}O{sub 5+{delta}}, multi-layered thin film based half cell was deposited on LaAlO{sub 3}(001) substrate. The temperature dependence of the resistance of this half ?cell structure was characterized by electrochemical impedance spectroscopy (EIS) within different temperature and gas environments. Anode supported fuel cells, with GCO:YSZ multilayer thin film as electrolyte and PBCO thin film as electrode, are fabricated on tape casted NiO/YSZ substrate. Full cell performance is characterized up to 800�C.

  9. Demagnetizing effects in stacked rectangular prisms

    DEFF Research Database (Denmark)

    Christensen, Dennis; Nielsen, Kaspar Kirstein; Bahl, Christian Robert Haffenden;

    2011-01-01

    configuration, temperature distribution and applied magnetic field. In this paper the model is applied to the case of a stack of parallel, ferromagnetic rectangular prisms and the resulting internal field is found as a function of the orientation of the applied field, the number of prisms in the stack, the...... spacing between the prisms and the packing density of the stack. The results show that the resulting internal field is far from being equal to the applied field and that the various stack configurations investigated affect the resulting internal field significantly and non-linearly. The results have a...

  10. Influences of Stacking Architectures of TiO2 Nanoparticle Layers on Characteristics of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Chih-Hung Tsai

    2013-01-01

    Full Text Available We investigated the influences of stacking architectures of the TiO2 nanoparticle layers on characteristics and performances of DSSCs. TiO2 nanoparticles of different sizes and compositions were characterized for their morphological and optical/scattering properties in thin films. They were used to construct different stacking architectures of the TiO2 nanoparticle layers for use as working electrodes of DSSCs. Characteristics and performances of DSSCs were examined to establish correlation of the stacking architectures of TiO2 nanoparticle layers with characteristics of DSSCs. The results suggest that the three-layer DSSC architecture, with sandwiching a 20 nm TiO2 nanoparticle layer between a 37 nm TiO2 nanoparticle layer and a hundred nm sized TiO2 back scattering/reflection layer, is effective in enhancing DSSC efficiencies. The high-total-transmittance 37 nm TiO2 nanoparticle layer with a larger haze can serve as an effective front scattering layer to scatter a portion of the incident light into larger oblique angles and therefore increase optical paths and absorption.

  11. CZTS absorber layer for thin film solar cells from electrodeposited metallic stacked precursors (Zn/Cu-Sn)

    Science.gov (United States)

    Khalil, M. I.; Atici, O.; Lucotti, A.; Binetti, S.; Le Donne, A.; Magagnin, L.

    2016-08-01

    In the present work, Kesterite-Cu2ZnSnS4 (CZTS) thin films were successfully synthesized from stacked bilayer precursor (Zn/Cu-Sn) through electrodeposition-annealing route. Adherent and homogeneous Cu-poor, Zn-rich stacked metal Cu-Zn-Sn precursors with different compositions were sequentially electrodeposited, in the order of Zn/Cu-Sn onto Mo foil substrates. Subsequently, stacked layers were soft annealed at 350 °C for 20 min in flowing N2 atmosphere in order to improve intermixing of the elements. Then, sulfurization was completed at 585 °C for 15 min in elemental sulfur environment in a quartz tube furnace with N2 atmosphere. Morphological, compositional and structural properties of the films were investigated using SEM, EDS and XRD methods. Raman spectroscopy with two different excitation lines (514.5 and 785 nm), has been carried out on the sulfurized films in order to fully characterize the CZTS phase. Higher excitation wavelength showed more secondary phases, but with low intensities. Glow discharge optical emission spectroscopy (GDOES) has also been performed on films showing well formed Kesterite CZTS along the film thickness as compositions of the elements do not change along the thickness. In order to investigate the electronic structure of the CZTS, Photoluminescence (PL) spectroscopy has been carried out on the films, whose results matched up with the literatures.

  12. Simulation and Optimization of Air-Cooled PEMFC Stack for Lightweight Hybrid Vehicle Application

    Directory of Open Access Journals (Sweden)

    Jingming Liang

    2015-01-01

    Full Text Available A model of 2 kW air-cooled proton exchange membrane fuel cell (PEMFC stack has been built based upon the application of lightweight hybrid vehicle after analyzing the characteristics of heat transfer of the air-cooled stack. Different dissipating models of the air-cooled stack have been simulated and an optimal simulation model for air-cooled stack called convection heat transfer (CHT model has been figured out by applying the computational fluid dynamics (CFD software, based on which, the structure of the air-cooled stack has been optimized by adding irregular cooling fins at the end of the stack. According to the simulation result, the temperature of the stack has been equally distributed, reducing the cooling density and saving energy. Finally, the 2 kW hydrogen-air air-cooled PEMFC stack is manufactured and tested by comparing the simulation data which is to find out its operating regulations in order to further optimize its structure.

  13. A High-Gain Three-Port Power Converter with Fuel Cell, Battery Sources and Stacked Output for Hybrid Electric Vehicles and DC-Microgrids

    OpenAIRE

    Ching-Ming Lai; Ming-Ji Yang

    2016-01-01

    This paper proposes a novel high-gain three-port power converter with fuel cell (FC), battery sources and stacked output for a hybrid electric vehicle (HEV) connected to a dc-microgrid. In the proposed power converter, the load power can be flexibly distributed between the input sources. Moreover, the charging or discharging of the battery storage device can be controlled effectively using the FC source. The proposed converter has several outputs in series to achieve a high-voltage output, wh...

  14. Interface optimization and modification of band offsets of ALD-derived Al2O3/HfO2/Al2O3/Ge gate stacks by annealing temperature

    International Nuclear Information System (INIS)

    Highlights: • Al2O3/HfO2/Al2O3 gate stacks have been deposited on Ge substrate by ALD. • Reduction in GeOx component and formation of HfAlO have been detected. • Increase in ΔEc and reductions in Eg and ΔEv have been observed. - Abstract: Interfacial thermal stability and band alignment of ALD-derived Al2O3/HfO2/Al2O3/Ge gate stacks have been investigated by X-ray photoelectron spectroscopy (XPS) and spectroscopy ellipsometry (SE) as a function of annealing temperature. It has been found that reduction in interfacial GeOx component and formation of HfAlO alloy layer have been detected with increasing the annealing temperature from 500 to 700 °C. Combined with analysis from XPS and SE, the increase in conduction band offset and reductions in band gap and valence band offset have been observed. When annealing temperature reaches 700 °C, the valence band offset has been reduced to 0.88 eV, which is smaller than the minimal requirement of ΔEv values for high-k dielectrics and, thus, leads to unacceptably high leakage currents. Therefore, annealing temperature should be carefully controlled to guarantee excellent properties of Al2O3/HfO2/Al2O3/Ge gate stacks in future Ge-based MOS devices

  15. Interconnects for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Huang, Wenhua

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

  16. Stacking with stochastic cooling

    International Nuclear Information System (INIS)

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles 'seen' by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly 'protected' from the Schottky noise of the stack. Vice versa the stack has to be efficiently 'shielded' against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105 the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters). In the 'old AA', where the antiproton collection and stacking was done in one single ring, the injected beam was further shielded during cooling by means of a movable shutter. The complexity of these systems is very high. For more modest stacking ratios, one might use azimuthal rather than radial separation of stack and injected beam. Schematically half of the circumference would be used to accept and cool new beam and the remainder to house the stack. Fast gating is then required between the high gain cooling of the injected beam and the low gain stack cooling. RF-gymnastics are used to merge the pre-cooled batch with the stack, to re-create free space for the next injection, and to capture the new batch. This scheme is less demanding for the storage ring lattice, but at the expense of some reduction in stacking rate. The talk reviews the 'radial' separation schemes and also gives some considerations to the 'azimuthal' schemes

  17. Effect of caffeine and reduced temperature (20 degrees C) on the organization of the pre-Golgi and the Golgi stack membranes

    OpenAIRE

    1993-01-01

    In the present study we have dissected the transport pathways between the ER and the Golgi complex using a recently introduced (Kuismanen, E., J. Jantti, V. Makiranta, and M. Sariola. 1992. J. Cell Sci. 102:505- 513) inhibition of transport by caffeine at 20 degrees C. Recovery of the Golgi complex from brefeldin A (BFA) treatment was inhibited by caffeine at reduced temperature (20 degrees C) suggesting that caffeine inhibits the membrane traffic between the ER and the Golgi complex. Caffein...

  18. Horizontal high speed stacking for batteries with prismatic cans

    Energy Technology Data Exchange (ETDEWEB)

    Bartos, Andrew L.; Lin, Yhu-Tin; Turner, III, Raymond D.

    2016-06-14

    A system and method for stacking battery cells or related assembled components. Generally planar, rectangular (prismatic-shaped) battery cells are moved from an as-received generally vertical stacking orientation to a generally horizontal stacking orientation without the need for robotic pick-and-place equipment. The system includes numerous conveyor belts that work in cooperation with one another to deliver, rotate and stack the cells or their affiliated assemblies. The belts are outfitted with components to facilitate the cell transport and rotation. The coordinated movement between the belts and the components promote the orderly transport and rotation of the cells from a substantially vertical stacking orientation into a substantially horizontal stacking orientation. The approach of the present invention helps keep the stacked assemblies stable so that subsequent assembly steps--such as compressing the cells or attaching electrical leads or thermal management components--may proceed with a reduced chance of error.

  19. The nature of excited states in dipolar donor/fullerene complexes for organic solar cells: evolution with the donor stack size.

    Science.gov (United States)

    Shen, Xingxing; Han, Guangchao; Yi, Yuanping

    2016-06-21

    Electronic delocalization at donor/acceptor (D/A) interfaces can play an important role in photocurrent generation for organic solar cells. Here, we have investigated the nature of local excited and interfacial charge transfer (CT) states in model complexes including one to four anti-parallel stacking dipolar donor (DTDCTB) molecules and one fullerene (C60) molecule by means of density functional theory (DFT) and time-dependent DFT (TDDFT). For all the donor-to-acceptor CT states, despite the number of DTDCTB molecules in the complexes, the hole is mainly localized on a single DTDCTB, and moves farther away from C60 for the energy higher level. However, the highest occupied molecular orbitals (HOMOs) and the excitonic states (EX) including the bright and dark EX are delocalized over the whole donor stacks in the complexes. This implies that the formation of ordered DTDCTB arrangements can substantially shorten the exciton diffusion process and facilitate ultrafast charge generation. Interestingly, owing to strong intermolecular Coulomb attraction, the donor-to-donor CT states are situated below the local excited states, but can approach the donor-to-acceptor CT states, indicating a weak role as charge traps. Our work would be helpful for understanding the electronic delocalization effects in organic solar cells. PMID:27241621

  20. Status of MCFC stack technology at IHI

    Energy Technology Data Exchange (ETDEWEB)

    Hosaka, M.; Morita, T.; Matsuyama, T.; Otsubo, M. [Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo (Japan)

    1996-12-31

    The molten carbonate fuel cell (MCFC) is a promising option for highly efficient power generation possible to enlarge. IHI has been studying parallel flow MCFC stacks with internal manifolds that have a large electrode area of 1m{sup 2}. IHI will make two 250 kW stacks for MW plant, and has begun to make cell components for the plant. To improve the stability of stack, soft corrugated plate used in the separator has been developed, and a way of gathering current from stacks has been studied. The DC output potential of the plant being very high, the design of electric insulation will be very important. A 20 kW short stack test was conducted in 1995 FY to certificate some of the improvements and components of the MW plant. These activities are presented below.

  1. Investigation of low temperature solid oxide fuel cells for air-independent UUV applications

    Science.gov (United States)

    Moton, Jennie Mariko

    Unmanned underwater vehicles (UUVs) will benefit greatly from high energy density (> 500 Wh/L) power systems utilizing high-energy-density fuels and air-independent oxidizers. Current battery-based systems have limited energy densities (UUV energy densities, and the current study explores how SOFCs based on gadolinia-doped ceria (GDC) electrolytes with operating temperatures of 650°C and lower may operate in the unique environments of a promising UUV power plant. The plant would contain a H 2O2 decomposition reactor to supply humidified O2 to the SOFC cathode and exothermic aluminum/H2O combustor to provide heated humidified H2 fuel to the anode. To characterize low-temperature SOFC performance with these unique O2 and H2 source, SOFC button cells based on nickel/GDC (Gd0.1Ce0.9O 1.95) anodes, GDC electrolytes, and lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-δ or LSCF)/GDC cathodes were fabricated and tested for performance and stability with humidity on both the anode and the cathode. Cells were also tested with various reactant concentrations of H2 and O2 to simulate gas depletion down the channel of an SOFC stack. Results showed that anode performance depended primarily on fuel concentration and less on the concentration of the associated increase in product H2O. O 2 depletion with humidified cathode flows also caused significant loss in cell current density at a given voltage. With the humidified flows in either the anode or cathode, stability tests of the button cells at 650 °C showed stable voltage is maintained at low operating current (0.17 A/cm2) at up to 50 % by mole H2O, but at higher current densities (0.34 A/cm2), irreversible voltage degradation occurred at rates of 0.8-3.7 mV/hour depending on exposure time. From these button cell results, estimated average current densities over the length of a low-temperature SOFC stack were estimated and used to size a UUV power system based on Al/H 2O oxidation for fuel and H2O2 decomposition

  2. Sizing Stack and Battery of a Fuel Cell Hybrid Distribution Truck Dimensionnement pile et batterie d’un camion hybride à pile à combustible de distribution

    Directory of Open Access Journals (Sweden)

    Tazelaar E.

    2012-08-01

    Full Text Available An existing fuel cell hybrid distribution truck, built for demonstration purposes, is used as a case study to investigate the effect of stack (kW and battery (kW, kWh sizes on the hydrogen consumption of the vehicle. Three driving cycles, the NEDC for Low Power vehicles, CSC and JE05 cycle, define the driving requirements for the vehicle. The Equivalent Consumption Minimization Strategy (ECMS is used for determining the control setpoint for the fuel cell and battery system. It closely approximates the global minimum in fuel consumption, set by Dynamic Programming (DP. Using DP the sizing problem can be solved but ECMS can also be implemented real-time. For the considered vehicle and hardware, all three driving cycles result in optimal sizes for the fuel cell stack of approximately three times the average drive power demand. This demonstrates that sizing the fuel cell stack the average or maximum power demand is not necessarily optimal with respect to a minimum fuel consumption. The battery is sized to deliver the difference between specified stack power and the peak power in the total power demand. The sizing of the battery is dominated by its power handling capabilities. Therefore, a higher maximum C-rate leads to a lower battery weight which in turn leads to a lower hydrogen consumption. The energy storage capacity of the battery only becomes an issue for C-rates over 30. Compared to a Range Extender (RE configuration, where the stack size is comparable to the average power demand and the stack is operated on a constant power level, optimal stack and battery sizes with ECMS as EnergyManagement Strategy significantly reduce the fuel consumption. Compared to a RE strategy, ECMS makes much better use of the combined power available from the fuel cell stack and the battery, resulting in a lower fuel consumption but also enabling a lower battery weight which consequently leads to improved payload capabilities. Un camion hybride, utilisant une pile

  3. A High-Gain Three-Port Power Converter with Fuel Cell, Battery Sources and Stacked Output for Hybrid Electric Vehicles and DC-Microgrids

    Directory of Open Access Journals (Sweden)

    Ching-Ming Lai

    2016-03-01

    Full Text Available This paper proposes a novel high-gain three-port power converter with fuel cell (FC, battery sources and stacked output for a hybrid electric vehicle (HEV connected to a dc-microgrid. In the proposed power converter, the load power can be flexibly distributed between the input sources. Moreover, the charging or discharging of the battery storage device can be controlled effectively using the FC source. The proposed converter has several outputs in series to achieve a high-voltage output, which makes it suitable for interfacing with the HEV and dc-microgrid. On the basis of the charging and discharging states of the battery storage device, two power operation modes are defined. The proposed power converter comprises only one boost inductor integrated with a flyback transformer; the boost and flyback circuit output terminals are stacked to increase the output voltage gain and reduce the voltage stress on the power devices. This paper presents the circuit configuration, operating principle, and steady-state analysis of the proposed converter, and experiments conducted on a laboratory prototype are presented to verify its effectiveness.

  4. 2010 Manufacturing Readiness Assessment Update to the 2008 Report for Fuel Cell Stacks and Systems for the Backup Power and Materials Handling Equipment Markets

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, D.; Ulsh, M.

    2012-08-01

    In 2008, the National Renewable Energy Laboratory (NREL), under contract to the US Department of Energy (DOE), conducted a manufacturing readiness assessment (MRA) of fuel cell systems and fuel cell stacks for back-up power and material handling applications (MHE). To facilitate the MRA, manufacturing readiness levels (MRL) were defined that were based on the Technology Readiness Levels previously established by the US Department of Energy (DOE). NREL assessed the extensive existing hierarchy of MRLs developed by Department of Defense (DoD) and other Federal entities, and developed a MRL scale adapted to the needs of the Fuel Cell Technologies Program (FCTP) and to the status of the fuel cell industry. The MRL ranking of a fuel cell manufacturing facility increases as the manufacturing capability transitions from laboratory prototype development through Low Rate Initial Production to Full Rate Production. DOE can use MRLs to address the economic and institutional risks associated with a ramp-up in polymer electrolyte membrane (PEM) fuel cell production. In 2010, NREL updated this assessment, including additional manufacturers, an assessment of market developments since the original report, and a comparison of MRLs between 2008 and 2010.

  5. In-operando temperature measurement across the interfaces of a lithium-ion battery cell

    International Nuclear Information System (INIS)

    In this work an experimental setup for in-operando temperature measurements across the interfaces anode – separator/electrolyte – cathode of a lithium-ion battery cell is developed to get a better understanding of the heat generating mechanisms. The results show differences in the heat evolution rates of the anode, the separator and the cathode according to the electrochemical reactions, the state of charge, the overvoltage and the electric current density. The LiCoO2 cathode was identified as the most decisive component for the heat evolution in the investigated battery stack. Changes of the ohmic resistance and the entropy of LiCoO2 with the state of charge were reflected by the temperature measurements

  6. Detailed experimental characterization of a reformate fuelled PEM stack

    DEFF Research Database (Denmark)

    Korsgaard, Anders; Nielsen, Mads Pagh; Kær, Søren Knudsen

    2006-01-01

    performance and process input variations need to be carefully accounted for. Such data will additionally provide valuable input for system modeling and optimization. The paper presents an advanced experimental test facility capable of performing static as well as dynamic tests on fuel cell stacks with...... electric power output from 1-3-kW. All process inputs for the stack can be altered to provide realistic performance analyses, corresponding to those encountered in field applications. These include cathode/anode dew point control, cathode flow rate, cooling water temperature control as well as synthesis...... gas mixing (CO, CO2, N2, Air and H2). The control system includes 12 thermocouple inputs, up to 60 cell voltages, more than 10 flow measurements and 10 pressure measurements, all at sample rates up to 1 kHz. The system design is thoroughly explained to provide valuable information for system...

  7. Demagnetizing effects in stacked rectangular prisms

    International Nuclear Information System (INIS)

    A numerical, magnetostatic model of the internal magnetic field of a rectangular prism is extended to the case of a stack of rectangular prisms. The model enables the calculation of the spatially resolved, three-dimensional internal field in such a stack given any magnetic state function, stack configuration, temperature distribution and applied magnetic field. In this paper the model is applied to the case of a stack of parallel, ferromagnetic rectangular prisms and the resulting internal field is found as a function of the orientation of the applied field, the number of prisms in the stack, the spacing between the prisms and the packing density of the stack. The results show that the resulting internal field is far from being equal to the applied field and that the various stack configurations investigated affect the resulting internal field significantly and non-linearly. The results have a direct impact on the design of, e.g., active magnetic regenerators made of stacked rectangular prisms in terms of optimizing the internal field.

  8. Non-radiative carrier recombination mechanism in the InGaAs/GaAsP strain-balanced quantum well solar cells with different number of stacks by using a piezoelectric photothermal method

    Science.gov (United States)

    Fukuyama, Atsuhiko; Nakano, Yosuke; Aihara, Taketo; Fujii, Hiroaki; Sugiyama, Masakazu; Nakano, Yoshiaki; Ikari, Tetsuo

    2012-10-01

    To optimize the multiple quantum well (QW) structure of the strain-balanced InGaAs/GaAsP inserted into GaAs p-i-n solar cell, carrier escaping process from QW, carrier radiative and non-radiative recombination processes in QW were investigated by using surface photovoltage (SPV), photoluminescence (PL) and piezoelectric photothermal (PPT) spectroscopies, respectively. Distinctive peaks at 1.19 eV were observed for all spectra below the bandgap of GaAs substrate (1.42 eV) and concluded that the peak was arisen from the excitonic transitions associated between the 1st order subbband in QWs. Although the optical absorption intensity of this transition was proportional to the number of QW stacks, SPV and PPT signals showed saturation above the QW stacks of 20. Band diagram calculation showed that an entire region of 10-stacked QWs was located in the flat band potential area, whereas a part of 20-stacked QWs was placed in an internal electric field. It was then suggested that the potential barrier height of 20-stacked QWs is small than that of 10-stacked QW.

  9. Mastering OpenStack

    CERN Document Server

    Khedher, Omar

    2015-01-01

    This book is intended for system administrators, cloud engineers, and system architects who want to deploy a cloud based on OpenStack in a mid- to large-sized IT infrastructure. If you have a fundamental understanding of cloud computing and OpenStack and want to expand your knowledge, then this book is an excellent checkpoint to move forward.

  10. OpenStack essentials

    CERN Document Server

    Radez, Dan

    2015-01-01

    If you need to get started with OpenStack or want to learn more, then this book is your perfect companion. If you're comfortable with the Linux command line, you'll gain confidence in using OpenStack.

  11. Stacking with stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Caspers, Fritz E-mail: Fritz.Caspers@cern.ch; Moehl, Dieter

    2004-10-11

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles 'seen' by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly 'protected' from the Schottky noise of the stack. Vice versa the stack has to be efficiently 'shielded' against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 10{sup 5} the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters). In the 'old AA', where the antiproton collection and stacking was done in one single ring, the injected beam was further shielded during cooling by means of a movable shutter. The complexity of these systems is very high. For more modest stacking ratios, one might use azimuthal rather than radial separation of stack and injected beam. Schematically half of the circumference would be used to accept and cool new beam and the remainder to house the stack. Fast gating is then required between the high gain cooling of the injected beam and the low gain stack cooling. RF-gymnastics are used to merge the pre-cooled batch with the stack, to re-create free space for the next injection, and to capture the new batch. This scheme is less demanding for the storage ring lattice, but at the expense of some reduction in stacking rate. The talk reviews the 'radial' separation schemes and also gives some

  12. Development of the electric utility dispersed use PAFC stack

    Energy Technology Data Exchange (ETDEWEB)

    Horiuchi, Hiroshi; Kotani, Ikuo [Mitsubishi Electric Co., Kobe (Japan); Morotomi, Isamu [Kansai Electric Power Co., Hyogo (Japan)] [and others

    1996-12-31

    Kansai Electric Power Co. and Mitsubishi Electric Co. have been developing the electric utility dispersed use PAFC stack operated under the ambient pressure. The new cell design have been developed, so that the large scale cell (1 m{sup 2} size) was adopted for the stack. To confirm the performance and the stability of the 1 m{sup 2} scale cell design, the short stack study had been performed.

  13. An Experimental Cell for High-Temperature

    Science.gov (United States)

    Giordano, D.; Robert, G.; Rodway, R.; Rust, A.; Russell, J. K.

    2005-12-01

    The Volcanology-Deformation-Rig (VDR) was developed for exploring the high-T rheological properties of volcanic materials [1]. The VDR is designed to perform high-T, low-load (< 1136 kg) deformation experiments at constant load, or displacement rate, or at controlled load rates. The rig is ideal for determining the rheological response of volcanic products within a wide range of natural conditions: T up to 1000oC, applied stresses up to 150 MPa, and strain rates between 10-6 and 10-2 s-1. The resulting data provide a powerful means of developing constitutive equations governing the multiphase (liquids ± vesicles ± solids) rheology of volcanic material during flow and deformation [2]. Many seminal issues in volcanology involve the behaviour of the volatile phase during flow and deformation and its effect on magma rheology and volcanic behaviour. Thus, we have designed and built a high-T resistant, sealed fluid pressure cell. The cell gives us the capacity to run controlled high-T deformation experiments at controlled H2O pressures that simulate nature (0-150 MPa). Deformation experiments can be run on consolidated and unconsolidated samples up to 3 cm in diameter and 10 cm in length. Fluid pressure in the cell can either be a dependent or independent variable. The former corresponds to a closed-system where fluid pressure is monitored throughout the experiment, whereas the latter is an open-system experiment with a fixed fluid pressure. By means of varying temperature and strain rate our experiments can explore the viscous to brittle transition of the investigated volcanic products at controlled conditions (e.g., water-bearing and/or water pressurized systems). We plan to use high-T experiments on natural volcanic materials (e.g., cores of sintered ash, obsidian, or pumice) to elucidate the rheology of multiphase volcanic products and to study feedback mechanisms between porosity and permeability evolution. References Cited: [1] Quane S, Russell JK & Kennedy LA

  14. Diagnosis of PEMFC stack failures via electrochemical impedance spectroscopy

    Science.gov (United States)

    Merida-Donis, Walter Roberto

    Two failure modes related to water management in Proton Exchange Membrane fuel cells (dehydration and flooding) were investigated using electrochemical impedance spectroscopy as a diagnosis tool. It was hypothesised that each failure mode corresponds to changes in the overall stack impedance that are observable in different frequency ranges. This hypothesis was corroborated experimentally. The experimental implementation required new testing hardware and techniques. A four-cell stack capable of delivering individually conditioned reactants to each cell was designed, built, tested, and characterised under a variety of operating conditions. This stack is the first reported prototype of its type. The stack was used to perform galvanostatic, impedance measurements in situ. The measurements were made at three different temperatures (62, 70 and 80°C), covering the current density range 0.1 to 1.0 A cm-2 , and the frequency range 0.1 to 4 x 105 Hz. The recorded data represent the first reported set of measurements covering these ranges. The failure modes were simulated on individual cells within the stack. The effects on individual cell and stack impedance were studied by measuring the changes in stack and cell impedances under flooding or dehydration conditions. Dehydration effects were measurable over a wide frequency range (0.5 to 105 Hz). In contrast, flooding effects were measurable in a narrower frequency range (0.5 to 102 Hz). Using these results, separate or concurrent impedance measurements in these frequency ranges (or narrow bands thereof) can be used to discern and identify the two failure modes quasi-instantaneously. Such detection was not possible with pre-existing, do techniques. The measured spectra were modelled by a simple equivalent circuit whose time constants corresponded to ideal (RC) and distributed (Warburg) components. The model was robust enough to fit all the measured spectra (for single cells and the stack), under normal and simulated

  15. Stacking with Stochastic Cooling

    CERN Document Server

    Caspers, Friedhelm

    2004-01-01

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles seen by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly protected from the Schottky noise of the stack. Vice versa the stack has to be efficiently shielded against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105, the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters)....

  16. MD study of the finite temperature effects on the phase ordering, stacking fault energy, and edge dislocation core structure in elemental Pu and Pu–Ga alloys

    International Nuclear Information System (INIS)

    The Modified Embedded Atom Model (MEAM) of elemental plutonium and plutonium–gallium alloys has been tested for its ability to reproduce the correct ordering of the hcp and fcc phases that is crucial from the point of view of molecular dynamics simulation of elastic–plastic phenomena in the material. Stacking fault energy obtained with the MEAM is in agreement with experimental data. Results of the edge dislocation modeling at the ambient conditions evidence for rather wide dislocation core, namely, 5–6 Burgers vectors. The results of the MD simulation have been compared with those obtained early with recently developed Multi State-MEAM potential

  17. Temperature dependence of photovoltaic cells, modules, and systems

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Burdick, J.; Caiyem, Y. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    Photovoltaic (PV) cells and modules are often rated in terms of a set of standard reporting conditions defined by a temperature, spectral irradiance, and total irradiance. Because PV devices operates over a wide range of temperatures and irradiances, the temperature and irradiance related behavior must be known. This paper surveys the temperature dependence of crystalline and thin-film, state-of-the-art, research-size cells, modules, and systems measured by a variety of methods. The various error sources and measurement methods that contribute to cause differences in the temperature coefficient for a given cell or module measured with various methods are discussed.

  18. Experimental study and modelling of degradation phenomena in HTPEM fuel cell stacks for use in CHP systems

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl

    2009-01-01

    Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modelling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing the...

  19. Experimental study and modeling of degradation phenomena in HTPEM fuel cell stacks for use in CHP systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh; Andreasen, Søren Juhl; Rasmussen, Peder Lund;

    2009-01-01

    Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modeling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing the...

  20. Temperature dependence of hydrogenated amorphous silicon solar cell performances

    OpenAIRE

    Riesen, Y.; Stuckelberger, M.; Haug, F. -J.; Ballif, C.; N. Wyrsch

    2016-01-01

    Thin-film hydrogenated amorphous silicon solar (a-Si:H) cells are known to have better temperature coefficients than crystalline silicon cells. To investigate whether a-Si:H cells that are optimized for standard conditions (STC) also have the highest energy yield, we measured the temperature and irradiance dependence of the maximum power output (Pmpp), the fill factor (FF), the short-circuit current density (Jsc), and the open-circuit voltage (Voc) for four series of cells fabricated with dif...

  1. Electrolytes for Wide Operating Temperature Lithium-Ion Cells

    Science.gov (United States)

    Smart, Marshall C. (Inventor); Bugga, Ratnakumar V. (Inventor)

    2016-01-01

    Provided herein are electrolytes for lithium-ion electrochemical cells, electrochemical cells employing the electrolytes, methods of making the electrochemical cells and methods of using the electrochemical cells over a wide temperature range. Included are electrolyte compositions comprising a lithium salt, a cyclic carbonate, a non-cyclic carbonate, and a linear ester and optionally comprising one or more additives.

  2. Laser processing of Al2O3/a-SiCx:H stacks: a feasible solution for the rear surface of high-efficiency p-type c-Si solar cells

    OpenAIRE

    Martín García, Isidro; Ortega Villasclaras, Pablo Rafael; Colina, Monica; Orpella García, Alberto; López, Gema; Alcubilla González, Ramón

    2012-01-01

    We explore the potential of laser processing aluminium oxide (Al2O3)/amorphous silicon carbide (a-SiCx:H) stacks to be used at the rear surface of p-type crystalline silicon (c-Si) solar cells. For this stack, excellent quality surface passivation is measured with effective surface recombination velocities as low as 2 cm/s. By means of an infrared laser, the dielectric film is locally opened. Simultaneously, part of the aluminium in the Al2O3 film is introduced into the c-Si, creating p+ regi...

  3. Annotated Stack Trees

    OpenAIRE

    Hague, Matthew; Penelle, Vincent

    2015-01-01

    Annotated pushdown automata provide an automaton model of higher-order recursion schemes, which may in turn be used to model higher-order programs for the purposes of verification. We study Ground Annotated Stack Tree Rewrite Systems -- a tree rewrite system where each node is labelled by the configuration of an annotated pushdown automaton. This allows the modelling of fork and join constructs in higher-order programs and is a generalisation of higher-order stack trees recently introduced by...

  4. Decoding Stacked Denoising Autoencoders

    OpenAIRE

    Sonoda, Sho; Murata, Noboru

    2016-01-01

    Data representation in a stacked denoising autoencoder is investigated. Decoding is a simple technique for translating a stacked denoising autoencoder into a composition of denoising autoencoders in the ground space. In the infinitesimal limit, a composition of denoising autoencoders is reduced to a continuous denoising autoencoder, which is rich in analytic properties and geometric interpretation. For example, the continuous denoising autoencoder solves the backward heat equation and transpo...

  5. Modeling of PEM Fuel Cell Stack System using Feed-forward and Recurrent Neural Networks for Automotive Applications

    Directory of Open Access Journals (Sweden)

    Mr. M. Karthik

    2014-05-01

    Full Text Available Artificial Neural Network (ANN has become a significant modeling tool for predicting the performance of complex systems that provide appropriate mapping between input-output variables without acquiring any empirical relationship due to the intrinsic properties. This paper is focussed towards the modeling of Proton Exchange Membrane (PEM Fuel Cell system using Artificial Neural Networks especially for automotive applications. Three different neural networks such as Static Feed Forward Network (SFFN, Cascaded Feed Forward Network (CFFN & Fully Connected Dynamic Recurrent Network (FCRN are discussed in this paper for modeling the PEM Fuel Cell System. The numerical analysis is carried out between the three Neural Network architectures for predicting the output performance of the PEM Fuel Cell. The performance of the proposed Networks is evaluated using various error criteria such as Mean Square Error, Mean Absolute Percentage Error, Mean Absolute Error, Coefficient of correlation and Iteration Values. The optimum network with high performance indices (low prediction error values and iteration values can be used as an ancillary model in developing the PEM Fuel Cell powered vehicle system. The development of the fuel cell driven vehicle model also incorporates the modeling of DC-DC Power Converter and Vehicle Dynamics. Finally the Performance of the Electric vehicle model is analyzed for two different drive cycle such as M-NEDC & M-UDDS.

  6. Characterization of Piezoelectric Stacks for Space Applications

    Science.gov (United States)

    Sherrit, Stewart; Jones, Christopher; Aldrich, Jack; Blodget, Chad; Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to actuate mechanisms to precision levels in the nanometer range and below. Co-fired multilayer piezoelectric stacks offer the required actuation precision that is needed for such mechanisms. To obtain performance statistics and determine reliability for extended use, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and high temperatures and voltages. In order to study the lifetime performance of these stacks, five actuators were driven sinusoidally for up to ten billion cycles. An automated data acquisition system was developed and implemented to monitor each stack's electrical current and voltage waveforms over the life of the test. As part of the monitoring tests, the displacement, impedance, capacitance and leakage current were measured to assess the operation degradation. This paper presents some of the results of this effort.

  7. Interface engineering of layer-by-Layer stacked graphene anodes for high-performance organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Tong, Shi Wun; Loh, Kian Ping [Department of Chemistry, National University of Singapore (Singapore); Xu, Xiang Fan; Oezyilmaz, Barbaros [Department of Physics, National University of Singapore (Singapore)

    2011-04-05

    An interface engineering process to deploy graphene film as the anode in poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM)-based polymer solar cells is demonstrated. By modifying the interface between the graphene anode and the photoactive layer with MoO{sub 3} and poly(3,4-ethylenedioythiophene):poly(styrenesulfonate) (PEDOT:PSS), the power conversion efficiency of the solar cells reaches {approx}83.3% of control devices that use an indium tin oxide (ITO) anode. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Tetrazole substituted polymers for high temperature polymer electrolyte fuel cells

    DEFF Research Database (Denmark)

    Henkensmeier, Dirk; My Hanh Duong, Ngoc; Brela, Mateusz;

    2015-01-01

    interesting for use in a high temperature fuel cell (HT PEMFC). Based on these findings, two polymers incorporating the proposed TZ groups were synthesised, formed into membranes, doped with PA and tested for fuel cell relevant properties. At room temperature, TZ-PEEN and commercial meta-PBI showed an...

  9. The Variation of Electrochemical Cell Potentials with Temperature

    Science.gov (United States)

    Peckham, Gavin D.; McNaught, Ian J.

    2011-01-01

    Electrochemical cell potentials have no simple relationship with temperature but depend on the interplay between the sign and magnitude of the isothermal temperature coefficient, dE[degrees]/dT, and on the magnitude of the reaction quotient, Q. The variations in possible responses of standard and non-standard cell potentials to changes in the…

  10. Controlled Delivery of Human Cells by Temperature Responsive Microcapsules

    Directory of Open Access Journals (Sweden)

    W.C. Mak

    2015-06-01

    Full Text Available Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line—human umbilical vein endothelial cells (HUVECs. While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

  11. Burst annealing of high temperature GaAs solar cells

    Science.gov (United States)

    Brothers, P. R.; Horne, W. E.

    1991-01-01

    One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles.

  12. Progress of MCFC stack technology at Toshiba

    Energy Technology Data Exchange (ETDEWEB)

    Hori, M.; Hayashi, T.; Shimizu, Y. [Toshiba Corp., Tokyo (Japan)

    1996-12-31

    Toshiba is working on the development of MCFC stack technology; improvement of cell characteristics, and establishment of separator technology. For the cell technology, Toshiba has concentrated on both the restraints of NiO cathode dissolution and electrolyte loss from cells, which are the critical issues to extend cell life in MCFC, and great progress has been made. On the other hand, recognizing that the separator is one of key elements in accomplishing reliable and cost-competitive MCFC stacks, Toshiba has been accelerating the technology establishment and verification of an advanced type separator. A sub-scale stack with such a separator was provided for an electric generating test, and has been operated for more than 10,000 hours. This paper presents several topics obtained through the technical activities in the MCFC field at Toshiba.

  13. High performance PEM fuel cells - from electrochemistry and material science to engineering development of a multicell stack. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Appleby, A.J.

    1997-03-04

    Under Task 1, it was shown that apparently identical MEAs of 50 Cm2 active area with 1.4 mg/cm2 Pt./C cathodes (20 wt % Pt on C) and 0.3 mg/cm2 Pt/C anodes with 40 microns thickness Gore-Select(TM) PEM material did not give identical performance, except in the Tafel region. This indicates that their overall active surface areas at low current density were identical, and that performance suffered at high current density in the range of interest. In all cases, this is shown as a change in polarization slope in the linear region. The slope of the best of these cells was 0.25 ohms cm2, and that of the worst was ca. 0.36 ohms cm2. In consequence, the performance of the best cell at 0.7 V with humidified gases was 0.44 A/cm2, and that of the worst was 0.3 A/cm2. These are substantially less than 0.7 A/cm2 at 0.7 V, which has been achieved in 5 cm2 cells. This is the fuel cell performance level required to achieve the overall system` performance goals (i.e., 0.7 A/cm2 and 0.7 V on hydrogen and air at atmospheric pressure). The variable polarization slope gives the impression of an internal resistance component, but the internal resistance measured at high frequency is rather low, about 0.12 ohms cm2. Thus, the differences in performance observed are either due to problems with the flow-field, or to dispersion in performance between individual MEAs, which otherwise contain identical components made by identical methods.

  14. A stack-based flex-compressive piezoelectric energy harvesting cell for large quasi-static loads

    Science.gov (United States)

    Wang, Xianfeng; Shi, Zhifei; Wang, Jianjun; Xiang, Hongjun

    2016-05-01

    In this paper, a flex-compressive piezoelectric energy harvesting cell (F-C PEHC) is proposed. This cell has a large load capacity and adjustable force transmission coefficient assembled from replaceable individual components. A statically indeterminate mechanical model for the cell is established and the theoretical force transmission coefficient is derived based on structural mechanics. An inverse correlation between the force transmission coefficient and the relative stiffness of Element 1’s limbs is found. An experimental study is also conducted to verify the theoretical results. Both weakened and enhanced modes are achieved for this experiment. The maximum power output approaches 4.5 mW at 120 kΩ resistive load under a 4 Hz harmonic excitation with 600 N amplitude for the weakened mode, whereas the maximum power output approaches 17.8 mW at 120 kΩ under corresponding load for the enhanced mode. The experimental measurements of output voltages are compared with the theoretical ones in both weakened and enhanced modes. The experimental measurements of open-circuit voltages are slightly smaller for harmonic excitations with amplitudes that vary from 400 N to 800 N and the errors are within 14%. During the experiment, the maximum load approaches 2.8 kN which is quite large but not the ultimate bearing capacity of the present device. The mechanical model and theoretical transmission coefficient can be used in other flex-compressive mode energy transducers.

  15. Innovative High Temperature Fuel Cell systems

    NARCIS (Netherlands)

    Au, Siu Fai

    2003-01-01

    The world's energy consumption is growing extremely rapidly. Fuel cell systems are of interest by researchers and industry as the more efficient alternative to conventional thermal systems for power generation. The principle of fuel cell conversion does not involve thermal combustion and hence in th

  16. Detailed Electrochemical Characterisation of Large SOFC Stacks

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Hjelm, Johan; Barfod, R.;

    2012-01-01

    As solid oxide fuel cell (SOFC) technology is moving closer to a commercial break through, lifetime limiting factors, determination of the limits of safe operation and methods to measure the “state-of-health” of operating cells and stacks are becoming of increasing interest. This requires...

  17. On Stack Reconstruction Problem

    Directory of Open Access Journals (Sweden)

    V. D. Аkeliev

    2014-06-01

    Full Text Available The paper describes analytical investigations that study relation of fuel combustion regimes with concentration values of sulphur anhydride in flue gases and acid dew point. Coefficients of convective heat transfer at internal and external surfaces of stacks have been determined in the paper. The paper reveals the possibility to reconstruct stacks while using gas discharging channel made of composite material on the basis of glass-reinforced plastic which permits to reduce thermo-stressed actions on reinforced concrete and increase volume of released gases due to practically two-fold reduction of gas-dynamic pressure losses along the pipe length.

  18. TARN rf stacking system

    International Nuclear Information System (INIS)

    Repetitive rf stacking system for the TARN was developed. The developed system consists of ferrite loaded rf cavity, rf power amplifier, ferrite bias power supply and low level rf electronics. Ferrite material and rf signal source were studied to obtain a high-duty and precise moving rf bucket. Phase lock technic worked at a low intensity beam was also studied. Repetition rate of 50 Hz and final stacking number of 50 were attained at the injection beam energy of 7 MeV/u. (author)

  19. Effects of cooling system parameters on heat transfer in PAFC stack

    Science.gov (United States)

    Abdul-Aziz, Ali A.

    1985-08-01

    Analytical and experimental study for the effects of cooling system parameters on the heat transfer and temperature distribution in the electrode plates of a phosphoric acid fuel-cell has been conducted. An experimental set-up that simulates the operating conditions prevailing in a phosphoric-acid fuel-cell stack was designed and constructed. The set-up was then used to measure the overall heat transfer coefficient, the thermal contact resistance, and the electrode temperature distribution for two different cooling plate configurations. Two types of cooling plate configurations, serpentine and straight, were tested. Air, water, and oil were used as coolants. Measurements for the heat transfer coefficient and the thermal contact resistance were made for various flow rates ranging from 16 to 88 Kg/hr, and stack clamping pressure ranging from O to 3448 Kpa. The experimental results for the overall heat transfer coefficient were utilized to derive mathematical relations for the overall heat transfer coefficient as a function of stack clamping pressure and Reynolds number for the three coolants. The empirically derived formulas were incorporated in a previously developed computer program to predict electrodes temperature distribution and the performance of the stack cooling system. The results obtained were then compared with those available in the literature. The comparison showed maximum deviation of +/- 11%.

  20. Effects of cooling system parameters on heat transfer in PAFC stack. Ph.D. Thesis

    Science.gov (United States)

    Abdul-Aziz, Ali A.

    1985-01-01

    Analytical and experimental study for the effects of cooling system parameters on the heat transfer and temperature distribution in the electrode plates of a phosphoric acid fuel-cell has been conducted. An experimental set-up that simulates the operating conditions prevailing in a phosphoric-acid fuel-cell stack was designed and constructed. The set-up was then used to measure the overall heat transfer coefficient, the thermal contact resistance, and the electrode temperature distribution for two different cooling plate configurations. Two types of cooling plate configurations, serpentine and straight, were tested. Air, water, and oil were used as coolants. Measurements for the heat transfer coefficient and the thermal contact resistance were made for various flow rates ranging from 16 to 88 Kg/hr, and stack clamping pressure ranging from O to 3448 Kpa. The experimental results for the overall heat transfer coefficient were utilized to derive mathematical relations for the overall heat transfer coefficient as a function of stack clamping pressure and Reynolds number for the three coolants. The empirically derived formulas were incorporated in a previously developed computer program to predict electrodes temperature distribution and the performance of the stack cooling system. The results obtained were then compared with those available in the literature. The comparison showed maximum deviation of +/- 11%.

  1. Structural color-tunable mesoporous bragg stack layers based on graft copolymer self-assembly for high-efficiency solid-state dye-sensitized solar cells

    Science.gov (United States)

    Lee, Chang Soo; Park, Jung Tae; Kim, Jong Hak

    2016-08-01

    We present a facile fabrication route for structural color-tunable mesoporous Bragg stack (BS) layers based on the self-assembly of a cost-effective graft copolymer. The mesoporous BS layers are prepared through the alternating deposition of organized mesoporous-TiO2 (OM-TiO2) and -SiO2 (OM-SiO2) films on the non-conducting side of the counter electrode in dye-sensitized solar cells (DSSCs). The OM layers with controlled porosity, pore size, and refractive index are templated with amphiphilic graft copolymers consisting of poly(vinyl chloride) backbones and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM. The morphology and properties of the structural color-tunable mesoporous BS-functionalized electrodes are characterized using energy filtered transmission electron microscopy (EF-TEM), field emission-scanning electron microscopy (FE-SEM), spectroscopic ellipsometry, and reflectance spectroscopy. The solid-state DSSCs (ssDSSCs) based on a structural color-tunable mesoporous BS counter electrode with a single-component solid electrolyte show an energy conversion efficiency (η) of 7.1%, which is much greater than that of conventional nanocrystalline TiO2-based cells and one of the highest values for N719 dye-based ssDSSCs. The enhancement of η is due to the enhancement of current density (Jsc), attributed to the improved light harvesting properties without considerable decrease in fill factor (FF) or open-circuit voltage (Voc), as confirmed by incident photon-to-electron conversion efficiency (IPCE) and electrochemical impedance spectroscopy (EIS).

  2. Design of high temperature irradiation materials inspection cells. (Spent fuel inspection cells) in the High Temperature Engineering Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ino, Hiroichi; Ueta, Shouhei; Suzuki, Hiroshi; Sawa, Kazuhiro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tobita, Tsutomu [Nuclear Engineering Company, Ltd., Tokai, Ibaraki (Japan)

    2002-01-01

    This report summarizes design requirements and design results for shields, ventilation system and fuel handling devices for the high temperature irradiation materials inspection cells (spent fuel inspection cells). These cells are small cells to carry out few post-irradiation examinations of spent fuels, specimen, etc., which are irradiated in the High Temperature Engineering Test Reactor, since the cells should be built in limited space in the HTTR reactor building, the cells are designed considering relationship between the cells and the reactor building to utilize the limited space effectively. The cells consist of three partitioned hot cells with wall for neutron and gamma-ray shields, ventilation system including filtering units and fuel handling devices. The post-irradiation examinations of the fuels and materials are planed by using the cells and the Hot Laboratory of the Japan Materials Testing Reactor to establish the technology basis on high temperature gas-cooled reactors (HTGRs). In future, irradiation tests and post-irradiation examinations will be carried out with the cells to upgrade present HTGR technologies and to make the innovative basic research on high-temperature engineering. (author)

  3. Design of high temperature irradiation materials inspection cells. (Spent fuel inspection cells) in the High Temperature Engineering Test Reactor

    International Nuclear Information System (INIS)

    This report summarizes design requirements and design results for shields, ventilation system and fuel handling devices for the high temperature irradiation materials inspection cells (spent fuel inspection cells). These cells are small cells to carry out few post-irradiation examinations of spent fuels, specimen, etc., which are irradiated in the High Temperature Engineering Test Reactor, since the cells should be built in limited space in the HTTR reactor building, the cells are designed considering relationship between the cells and the reactor building to utilize the limited space effectively. The cells consist of three partitioned hot cells with wall for neutron and gamma-ray shields, ventilation system including filtering units and fuel handling devices. The post-irradiation examinations of the fuels and materials are planed by using the cells and the Hot Laboratory of the Japan Materials Testing Reactor to establish the technology basis on high temperature gas-cooled reactors (HTGRs). In future, irradiation tests and post-irradiation examinations will be carried out with the cells to upgrade present HTGR technologies and to make the innovative basic research on high-temperature engineering. (author)

  4. Learning SaltStack

    CERN Document Server

    Myers, Colton

    2015-01-01

    If you are a system administrator who manages multiple servers, then you know how difficult it is to keep your infrastructure in line. If you've been searching for an easier way, this book is for you. No prior experience with SaltStack is required.

  5. Deformations of algebroid stacks

    DEFF Research Database (Denmark)

    Bressler, Paul; Gorokhovsky, Alexander; Nest, Ryszard; Tsygan, Boris

    2011-01-01

    In this paper we consider deformations of an algebroid stack on an étale groupoid. We construct a differential graded Lie algebra (DGLA) which controls this deformation theory. In the case when the algebroid is a twisted form of functions we show that this DGLA is quasiisomorphic to the twist of ...

  6. po_stack_movie

    DEFF Research Database (Denmark)

    2009-01-01

    po_stack® er et reolsystem, hvis enkle elementer giver stor flexibilitet, variation og skulpturel virkning. Elementerne stables og forskydes frit, så reolens rum kan vendes til begge sider, være åbne eller lukkede og farvekombineres ubegrænset. Reolen kan let ombygges, udvides eller opdeles, når ...

  7. Wolfram technology stack

    CERN Multimedia

    2013-01-01

    Stephen Wolfram gives a personal account of his vision for the "Wolfram technology stack" and how it developed, starting with his work in particle physics. The talk was presented at the 2013 ROOT Users' Meeting and followed a talk, earlier in the day, on "Mathematica with ROOT".

  8. Stacking with No Planarity?

    Science.gov (United States)

    Gunaydin, Hakan; Bartberger, Michael D

    2016-04-14

    This viewpoint describes the results obtained from matched molecular pair analyses and quantum mechanics calculations that show unsaturated rings found in drug-like molecules may be replaced with their saturated counterparts without losing potency even if they are engaged in stacking interactions with the side chains of aromatic residues. PMID:27096037

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

    Science.gov (United States)

    Kilner, John A.; Burriel, Mónica

    2014-07-01

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

  10. InGaN High Temperature Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I project is to demonstrate InGaN materials are appropriate for high operating temperature single junction solar cells. Single junction...

  11. InGaN High Temperature Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objectives of this Phase II project are to develop InGaN photovoltaic cells for high temperature and/or high radiation environments to TRL 4 and to define the...

  12. Novel High Temperature Membrane for PEM Fuel Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation proposed in this STTR program is a high temperature membrane to increase the efficiency and power density of PEM fuel cells. The NASA application is...

  13. Influence of CuO addition and sintering temperature on microwave dielectric properties of Ca0.99Zn0.01La4Ti5O17 ceramics for application in stacked patch antenna

    International Nuclear Information System (INIS)

    In this study, the microwave dielectric properties of Ca0.99Zn0.01La4Ti5O17 (CZLTO) ceramics have been investigated. It is found that the X-ray diffraction pattern exhibited no phase difference with 0.5 wt % CuO additive at different sintering temperatures. The maximum value of the dielectric constant and the quality factor Q x f can be obtained with 0.5 wt % CuO additive and sintered at 1450degC for 4 h. A πf of -8.16 ppm/degC was measured for CZLTO ceramics with 0.5 wt % CuO sintered at 1450degC for 4 h. The measurement results for a stacked patch antenna at 2.45 GHz are presented. With this technique, a 3.3% bandwidth (return loss 11 bandwidth. (author)

  14. Quantum fluctuations of mesoscopic biological cell at finite temperature

    Institute of Scientific and Technical Information of China (English)

    LI Hong-qi; XU Xing-lei

    2005-01-01

    On the basis of the quantization of mesoscopic biological cell equivalent circuit,we studied the quantum fluctuations of voltage and current of mesoscopic biological cell equivalent circuit as finite temperature by Bogoliuov transformation.The result shows that the quantum fluctuations of voltage and current not only relate with the parameters of equivalent circuit,temperature,but also decay with time.This result may have significant value on the design and application of the bio-electronic apparatus.

  15. NOx-conversion on Porous LSF15-CGO10 Cell Stacks with KNO3 or K2O Impregnation

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund; Bræstrup, Frantz Radzik; Kammer Hansen, Kent

    2012-01-01

    In the present work, it was investigated how addition of KNO3 or K2O affected the NOx conversion on LSF15–CGO10 (La0.85Sr15FeO3–Ce0.9Gd0.1O1.95) composite electrodes during polarization. The LSF15–CGO10 electrodes were part of a porous 11-layer cell stack with alternating layers of LSF15–CGO10...... observed during polarization, but the impregnations altered the conversion between NO and NO2 on the electrodes. Both impregnations caused increased degradation of the cell stack, but the exact cause of the degradation has not been identified yet....

  16. Electrode Kinetics in High Temperature Fuel Cells

    DEFF Research Database (Denmark)

    Bay, Lasse

    1998-01-01

    ^3s and 10^5s for a cathodic current. For the deactivation is the time constant about 10^4s. The origin for the hysteresis is not clear, but expansion of the three phase boundary (TPB) or change of the catalytic properties due to surface segregation are suggested.The hysteresis phenomenon is also......-electrolyte interface show dynamics of the YSZ surface and formation of a bank of YSZ along the TPB. These changes are induced by passage of current. The origin of the dynamics behaviour may be a localised temperature increase or it might be driven by segregation. The dynamics of the YSZ surface seems to be...

  17. Temperature-dependent imaging of living cells by AFM

    International Nuclear Information System (INIS)

    Characterization of lateral organization of plasma membranes is a prerequisite to the understanding of membrane structure-function relationships in living cells. Lipid-lipid and lipid-protein interactions are responsible for the existence of various membrane microdomains involved in cell signalization and in numerous pathologies. Developing approaches for characterizing microdomains associate identification tools like recognition imaging with high-resolution topographical imaging. Membrane properties are markedly dependent on temperature. However, mesoscopic scale topographical information of cell surface in a temperature range covering most of cell biology experimentation is still lacking. In this work we have examined the possibility of imaging the temperature-dependent behavior of eukaryotic cells by atomic force microscopy (AFM). Our results establish that the surface of living CV1 kidney cells can be imaged by AFM, between 5 and 37 deg. C, both in contact and tapping modes. These first temperature-dependent data show that large cell structures appeared essentially stable at a microscopic scale. On the other hand, as shown by contact mode AFM, the surface was highly dynamic at a mesoscopic scale, with marked changes in apparent topography, friction, and deflection signals. When keeping the scanning conditions constant, a progressive loss in the image contrast was however observed, using tapping mode, on decreasing the temperature

  18. Temperature dependence of hydrogenated amorphous silicon solar cell performances

    Science.gov (United States)

    Riesen, Y.; Stuckelberger, M.; Haug, F.-J.; Ballif, C.; Wyrsch, N.

    2016-01-01

    Thin-film hydrogenated amorphous silicon solar (a-Si:H) cells are known to have better temperature coefficients than crystalline silicon cells. To investigate whether a-Si:H cells that are optimized for standard conditions (STC) also have the highest energy yield, we measured the temperature and irradiance dependence of the maximum power output (Pmpp), the fill factor (FF), the short-circuit current density (Jsc), and the open-circuit voltage (Voc) for four series of cells fabricated with different deposition conditions. The parameters varied during plasma-enhanced chemical vapor deposition (PE-CVD) were the power and frequency of the PE-CVD generator, the hydrogen-to-silane dilution during deposition of the intrinsic absorber layer (i-layer), and the thicknesses of the a-Si:H i-layer and p-type hydrogenated amorphous silicon carbide layer. The results show that the temperature coefficient of the Voc generally varies linearly with the Voc value. The Jsc increases linearly with temperature mainly due to temperature-induced bandgap reduction and reduced recombination. The FF temperature dependence is not linear and reaches a maximum at temperatures between 15 °C and 80 °C. Numerical simulations show that this behavior is due to a more positive space-charge induced by the photogenerated holes in the p-layer and to a recombination decrease with temperature. Due to the FF(T) behavior, the Pmpp (T) curves also have a maximum, but at a lower temperature. Moreover, for most series, the cells with the highest power output at STC also have the best energy yield. However, the Pmpp (T) curves of two cells with different i-layer thicknesses cross each other in the operating cell temperature range, indicating that the cell with the highest power output could, for instance, have a lower energy yield than the other cell. A simple energy-yield simulation for the light-soaked and annealed states shows that for Neuchâtel (Switzerland) the best cell at STC also has the best energy

  19. Solar cell junction temperature measurement of PV module

    KAUST Repository

    Huang, B.J.

    2011-02-01

    The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

  20. Cone Penetrometer Load Cell Temperature and Radiation Testing Results

    Energy Technology Data Exchange (ETDEWEB)

    Follett, Jordan R.

    2013-08-28

    This report summarizes testing activities performed at the Pacific Northwest National Laboratory to verify the cone penetrometer load cell can withstand the tank conditions present in 241-AN-101 and 241-AN-106. The tests demonstrated the load cell device will operate under the elevated temperature and radiation levels expected to be encountered during tank farm deployment of the device.

  1. Waste to energy: Exploitation of biogas from organic waste in a 500 Wel solid oxide fuel cell (SOFC) stack

    International Nuclear Information System (INIS)

    Organic waste collection from local municipal areas with subsequent energy valorization through CHP systems allows for a reduction of waste disposal in landfill. Pollutant emissions released into the atmosphere are also reduced in this way. Solid oxide fuel cell (SOFC) systems are among the most promising energy generators, due to their high electrical efficiency (>50%), even at part loads. In this work, the local organic fraction of municipal solid waste has been digested in a dry anaerobic digester pilot plant and a biogas stream with methane and carbon dioxide concentrations ranging from 60–70 and 30–40% vol., respectively, has been obtained. Trace compounds from the digester and after the gas clean-up section have been detected by means of a new technique that exploits the protonation reactions between the volatile compounds of interest and the ion source. Sulfur, chlorine and siloxane compounds have been removed from as-produced biogas through the use of commercial sorbent materials, such as activated carbons impregnated with metals. A buffer gas cylinder tank has been inserted downstream from the filtering section to compensate for the biogas fluctuations from the digester. The technical feasibility of the dry anaerobic process of the organic fraction of municipal solid waste, coupled with a gas cleaning section and an SOFC system, has been proved experimentally with an electrical efficiency ranging from 32 to 36% for 400 h under POx conditions. - Highlights: • Biogas trace compounds were monitored with the innovative PTR-MS technique. • VOCs removal of a filter section was investigated with PTR-MS. • The treated biogas fed a SOFC stack with stable performance for more than 400 h

  2. Performance and durability of PEM fuel cells operated at sub-freezing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Rangachary [Los Alamos National Laboratory; Davey, John R [Los Alamos National Laboratory; Lujan, Roger W [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory

    2008-01-01

    The durability of polymer electrolyte membrane (PEM) fuel cells operated at sub-freezing temperatures has received increasing attention in recent years. The Department of Energy's PEM fuel cell stack technical targets for the year 2010 include unassisted start-up from -40 {sup o}C and startup from -20 {sup o}C ambient in as low as 30 seconds with < 5 MJ energy consumption. Moreover, the sub-freezing operations should not have any impact on acieving other technical targets including 5000 hours durability. The effect of MEA preparation on the performance of single-PEM fuel cells operated at sub-freezing temperatures is presented. The cell performance and durability are dependent on the MEA and are probably influenced by the porosity of the catalyst layers. When a cell is operated isothermally at -10 {sup o}C in constant current mode, the voltage gradually decreases over time and eventually drops to zero. AC impedance analysis indicated that the rate of voltage loss is initially due to an increase in the charge transfer resistance and is gradual. After a period, the rate of decay accelerates rapidly due to mass transport limitations at the catalyst and/or gas diffusion layers. The high frequency resistance also increases over time during the isothermal operation at sub-freezing temperatures and was a function of the initial membrane water content. LANL prepared MEAs showed very little loss in the catalyst surface area with multiple sub-freezing operations, whereas the commercial MEAs exhibited significant loss in cathode surface area with the anode being unaffected. These results indicate that catalyst layer ice formation is influenced strongly by the MEA and is responsible for the long-term degradation of fuel cells operated at sub-freezing temperatures. This ice formation was monitored using neutron radiography and was found to be concentrated near cell edges at the flow field turns. The water distribution also indicated that ice may be forming mainly in the

  3. Temperature dependence of critical shear stress of monocrystals of Kh18N15 metastable alloy with low energy of stacking faults

    International Nuclear Information System (INIS)

    A study was made on temperature dependence of tau0 critical shear stress of monocrystals of Kh18n15 metastable alloy in 1.8-300 K range. For crystals of certain orientations to tau0(T) dependence in 150-70 K range a plateau was observed. It was determined that occurance of plateau on tau0(T) dependence is related to epsilon-phase formation during loading, disappearing during crystal warming up to room temperature. Revealed sharp growth of tau0 values below 60 K, which is not typical of Fcc crystals is probably related to delaying #betta→#epsilon-transformation and change of austenite magnetic structure in this temperature range

  4. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    Science.gov (United States)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  5. OpenStack cloud security

    CERN Document Server

    Locati, Fabio Alessandro

    2015-01-01

    If you are an OpenStack administrator or developer, or wish to build solutions to protect your OpenStack environment, then this book is for you. Experience of Linux administration and familiarity with different OpenStack components is assumed.

  6. Energy Expenditure of Sport Stacking

    Science.gov (United States)

    Murray, Steven R.; Udermann, Brian E.; Reineke, David M.; Battista, Rebecca A.

    2009-01-01

    Sport stacking is an activity taught in many physical education programs. The activity, although very popular, has been studied minimally, and the energy expenditure for sport stacking is unknown. Therefore, the purposes of this study were to determine the energy expenditure of sport stacking in elementary school children and to compare that value…

  7. Operating Cell Temperature Determination in Flat-Plate Photovoltaic Modules

    International Nuclear Information System (INIS)

    Two procedures (simplified and complete) to determine me operating cell temperature in photovoltaic modules operating in real conditions assuming isothermal stationary modules are presented in this work. Some examples are included that show me dependence of this temperature on several environmental (sky, ground and ambient temperatures, solar irradiance, wind speed, etc.) and structural (module geometry and size, encapsulating materials, anti reflexive optical coatings, etc.) factors and also on electrical module performance. In a further step temperature profiles for non-isothermal modules are analysed besides transitory effects due to variable irradiance and wind gusts. (Author) 27 refs

  8. Analytic stacks and hyperbolicity

    OpenAIRE

    Borghesi, Simone; Tomassini, Giuseppe

    2012-01-01

    The classical Brody's theorem asserts the equivalence between two notions of hyperbolicity for compact complex spaces, one named after Kobayashi and one expressed in terms of lack of non constant holomorphic entire functions (compactness is only used to prove the harder implication). We extend this theorem to Deligne-Mumford analytic stacks, by first providing definitions of what we think of Kobayashi and Brody hyperbolicity for such objects and then proving the equivalence of these concepts ...

  9. Toric Stacks II: Intrinsic Characterization of Toric Stacks

    CERN Document Server

    Geraschenko, Anton

    2011-01-01

    The purpose of this paper and its prequel (Toric Stacks I) is to introduce and develop a theory of toric stacks which encompasses and extends the notions of toric stacks defined in [Laf02, BCS05, FMN09, Iwa09, Sat09, Tyo10], as well as classical toric varieties. While the focus of the prequel is on how to work with toric stacks, the focus of this paper is how to show a stack is toric. For toric varieties, a classical result says that any normal variety with an action of a dense open torus arises from a fan. In [FMN09, Theorem 7.24], it is shown that a smooth separated DM stack with an action of a dense open stacky torus arises from a stacky fan. In the same spirit, the main result of this paper is that any Artin stack with an action of a dense open torus arises from a stacky fan under reasonable hypotheses.

  10. Levitation characteristics of HTS tape stacks

    Energy Technology Data Exchange (ETDEWEB)

    Pokrovskiy, S. V.; Ermolaev, Y. S.; Rudnev, I. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2015-03-15

    Due to the considerable development of the technology of second generation high-temperature superconductors and a significant improvement in their mechanical and transport properties in the last few years it is possible to use HTS tapes in the magnetic levitation systems. The advantages of tapes on a metal substrate as compared with bulk YBCO material primarily in the strength, and the possibility of optimizing the convenience of manufacturing elements of levitation systems. In the present report presents the results of the magnetic levitation force measurements between the stack of HTS tapes containing of tapes and NdFeB permanent magnet in the FC and ZFC regimes. It was found a non- linear dependence of the levitation force from the height of the array of stack in both modes: linear growth at small thickness gives way to flattening and constant at large number of tapes in the stack. Established that the levitation force of stacks comparable to that of bulk samples. The numerical calculations using finite element method showed that without the screening of the applied field the levitation force of the bulk superconductor and the layered superconductor stack with a critical current of tapes increased by the filling factor is exactly the same, and taking into account the screening force slightly different.

  11. Temperature distribution in a stack of intrinsic Josephson junctions with their CuO-plane electrodes oriented perpendicular to supporting substrate

    Science.gov (United States)

    Yurgens, A.; Bulaevskii, L. N.

    2011-01-01

    We numerically study Joule heating in a THz emitter made of Bi2Sr2CaCu2O8 + δ (Bi2212) single crystal with its CuO planes oriented perpendicular to supporting substrate. The single crystal is glued to the substrate by a layer of PMMA. The electrical current is applied in the c-axis direction across many intrinsic Josephson junctions (IJJ's) in Bi2212. The calculations show that the internal temperature increases to an acceptable 10-20 K only above the bath temperature for a Joule power density of ~ 105 W cm - 3 typical for experiments on THz emission from IJJ's. This makes the suggested geometry promising for boosting the output power of the emitter.

  12. Policies for dynamic stack composition

    OpenAIRE

    Sora, Ioana; Michiels, Sam; Matthijs, Frank

    2001-01-01

    Currently, protocol stacks operate in various contexts and it is therefore not possible to know the required properties of a stack (both functional and non-functional) in advance. The stack has to be dynamically built up from components, based on the requirements and the momentary situation. The first step in building the stack is to determine the component types to be used and the stack architecture that has to define the way building blocks are connected. In this document we report on how t...

  13. 全钒液流电池10kW单元电堆性能研究%Performance of 10kW cell stack of vanadium redox flow battery

    Institute of Scientific and Technical Information of China (English)

    陈伟; 孟凡明; 李晓兵; 刘效疆; 马海波

    2013-01-01

    详细研究了全钒液流电池10kW单元电堆的功率输出特性和单体电压一致性及不同充放电电流密度与库仑效率和能量效率的关系.研究了电堆长期运行时,库仑效率、能量效率及电压平台的变化.%The power output characteristics and single voltage consistency of 10 kW cell stack of vanadium redox flow battery,as well as the coulombic efficiency and energy efficiency for different charge and discharge current density were studied.The variety of coulombic and energy efficiency and voltage platform of the stack was researched in a long-term operation.

  14. Temperature dependent electroreflectance study of CdTe solar cells

    International Nuclear Information System (INIS)

    Cadmium telluride is a promising material for large scale photovoltaic applications. In this paper we study CdS/CdTe heterojunction solar cells with electroreflectance spectroscopy. Both CdS and CdTe layers in solar cells were grown sequentially without intermediate processing by the close-space sublimation method. Electroreflectance measurements were performed in the temperature range of T = 100–300 K. Two solar cells were investigated with conversion efficiencies of 4.1% and 9.6%. The main focus in this work was to study the temperature dependent behavior of the broadening parameter and the bandgap energy of CdTe thin film in solar cells. Room temperature bandgap values of CdTe were Eg = 1.499 eV and Eg = 1.481 eV for higher and lower efficiency solar cells, respectively. Measured bandgap energies are lower than for single crystal CdTe. The formation of CdTe1−xSx solid solution layer on the surface of CdTe is proposed as a possible cause of lower bandgap energies. - Highlights: ► Temperature dependent electroreflectance measurements of CdS/CdTe solar cells ► Investigation of junction properties between CdS and CdTe ► Formation of CdTe1− xSx solid solution layer in the junction area

  15. Temperature-Responsive Polymer Modified Surface for Cell Sheet Engineering

    Directory of Open Access Journals (Sweden)

    Teruo Okano

    2012-08-01

    Full Text Available In the past two decades, as a novel approach for tissue engineering, cell sheet engineering has been proposed by our laboratory. Poly(N-isopropylacrylamide (PIPAAm, which is a well-known temperature-responsive polymer, has been grafted on tissue culture polystyrene (TCPS surfaces through an electron beam irradiated polymerization. At 37 °C, where the PIPAAm modified surface is hydrophobic, cells can adhere, spread on the surface and grow to confluence. By decreasing temperature to 20 °C, since the surface turns to hydrophilic, cells can detach themselves from the surface spontaneously and form an intact cell sheet with extracellular matrix. For obtaining a temperature-induced cell attachment and detachment, it is necessary to immobilize an ultra thin PIPAAm layer on the TCPS surfaces. This review focuses on the characteristics of PIAPAm modified surfaces exhibiting these intelligent properties. In addition, PIPAAm modified surfaces giving a rapid cell-sheet recovery has been further developed on the basis of the characteristic of the PIPAAm surface. The designs of temperature-responsive polymer layer have provided an enormous potential to fabricate clinically applicable regenerative medicine.

  16. Fungal melanins differ in planar stacking distances.

    Directory of Open Access Journals (Sweden)

    Arturo Casadevall

    Full Text Available Melanins are notoriously difficult to study because they are amorphous, insoluble and often associated with other biological materials. Consequently, there is a dearth of structural techniques to study this enigmatic pigment. Current models of melanin structure envision the stacking of planar structures. X ray diffraction has historically been used to deduce stacking parameters. In this study we used X ray diffraction to analyze melanins derived from Cryptococcus neoformans, Aspergillus niger, Wangiella dermatitides and Coprinus comatus. Analysis of melanin in melanized C. neoformans encapsulated cells was precluded by the fortuitous finding that the capsular polysaccharide had a diffraction spectrum that was similar to that of isolated melanin. The capsular polysaccharide spectrum was dominated by a broad non-Bragg feature consistent with origin from a repeating structural motif that may arise from inter-molecular interactions and/or possibly gel organization. Hence, we isolated melanin from each fungal species and compared diffraction parameters. The results show that the inferred stacking distances of fungal melanins differ from that reported for synthetic melanin and neuromelanin, occupying intermediate position between these other melanins. These results suggest that all melanins have a fundamental diffracting unit composed of planar graphitic assemblies that can differ in stacking distance. The stacking peak appears to be a distinguishing universal feature of melanins that may be of use in characterizing these enigmatic pigments.

  17. Direct dimethyl ether high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Vassiliev, Anton; Jensen, Jens Oluf; Li, Qingfeng;

    A high temperature polybenzimidazole (PBI) polymer fuel cell was fed with dimethyl ether (DME) and water vapour mixture on the anode at ambient pressure with air as oxidant. A peak power density of 79 mW/cm2 was achieved at 200°C. A conventional polymer based direct DME fuel cell is liquid fed and...... suffers from low DME solubility in water. When the DME - water mixture is fed as vapour miscibility is no longer a problem. The increased temperature is more beneficial for the kinetics of the direct oxidation of DME than of methanol. The Open Circuit Voltage (OCV) with DME operation was 50 to 100 m...

  18. Low temperature electrolytes for lithium/silver vanadium oxide cells

    Science.gov (United States)

    Tuhovak, Denise R.; Takeuchi, Esther S.

    1991-01-01

    Combinations of methyl formate (MF) and propylene carbonate (PC) using salt concentrations of 0.6 to 2.4 M, with lithium hexafluoroarsenate and lithium tetrafluoroborate in a five to one molar ratio, were investigated as electrolytes in lithium/silver vanadium oxide batteries. The composition of the electrolyte affected cell performance at low temperature, self-discharge and abuse resistance as characterized by short circuit and crush testing. The electrolyte that provided the best combination of good low temperature performance, low cell self-discharge and abuse resistance was 0.6 M salt in 10:90 PC/MF.

  19. Status and prospects of intermediate temperature solid oxide fuel cells

    Institute of Scientific and Technical Information of China (English)

    Bangwu Liu; Yue Zhang

    2008-01-01

    Compared with conventional electric power generation systems, the solid oxide fuel cell (SOFC) has many advantages because of its unique features. High temperature SOFC has been successfully developed to its commercial applications, but it still faces many problems which hamper large-scale commercial applications of SOFC. To reduce the cost of SOFC, intermediate tem-perature solid oxide fuel cell (IT-SOFC) is presently under rapid development. The status of IT-SOFC was reviewed with emphasis on discussion of their component materials.

  20. 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.

  1. Sensitivity analysis of anode overpotential during start-up process of a high temperature proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Highlights: • Low initial start-up temperature increases sensitivity of other parameters. • Reducing initial start-up temperature reduces warm-up time and energy consumption. • Critical temperature range of maximum sensitivity lies between 125 and 135 °C. - Abstract: This paper investigates the sensitivity of start-up parameters during the start-up or warm-up process of a high temperature proton exchange membrane fuel cell (HT-PEMFC), where carbon monoxide (CO) contaminated hydrogen is used as fuel. The heating strategy considered in this study involves external heating of the HT-PEMFC to an initial start-up temperature (above 100 °C), after which current is extracted, where the external heating still remains. A transient three-dimensional isothermal anode model is developed to determine the sensitivity of operational start-up parameters such as temperature increase rate, initial start-up temperature, CO volume fraction and extracted current density, on the anode overpotential during the start-up process. The results indicate that having a low initial start-up temperature is the key reason that makes the other parameters such as the current density, CO mole fraction and temperature increase rate, sensitive, especially at 108 °C. In addition, temperature range of 130 ± 5 °C is most critical as the sensitivity reaches a peak for all parameters at the three considered initial start-up temperatures. In addition, a system-level energy analysis considered for the start-up process of a 1-kW stack, suggests that having low initial start-up temperature can reduce warm-up time and energy consumption

  2. Die-stacking architecture

    CERN Document Server

    Xie, Yuan

    2015-01-01

    The emerging three-dimensional (3D) chip architectures, with their intrinsic capability of reducing the wire length, promise attractive solutions to reduce the delay of interconnects in future microprocessors. 3D memory stacking enables much higher memory bandwidth for future chip-multiprocessor design, mitigating the ""memory wall"" problem. In addition, heterogenous integration enabled by 3D technology can also result in innovative designs for future microprocessors. This book first provides a brief introduction to this emerging technology, and then presents a variety of approaches to design

  3. A computer model for a high temperature fuel cell

    OpenAIRE

    E. Hernández-Pacheco; Mann, M D

    2006-01-01

    A computer model is developed for determining the performance characteristics (e.g., current-voltage curves) of a solid oxide fuel cell. The model determines the fuel/oxidant concentration, the temperature profiles and the current density along the fuel and oxidant channels, respectively. Then, the average of the local current density distribution is used to determine the current-voltage curves (IV curves) over the entire range of cell potential, i.e., from open circuit voltage to short circu...

  4. Technology stacks and frameworks for full-stack application development

    OpenAIRE

    Ušaj, Erik

    2016-01-01

    This work aims providing a comprehensive overview and analysis of current JavaScript (JS) technology stacks and frameworks for full-stack application development: from web clients, mobile and desktop applications to server applications and cloud-connected services. Analysis shall focus on MEAN technology stack and frameworks such as Meteor which also tries to leverage mobile app development using Apache Cordova framework. We will include an overview of available JS build tools for desktop app...

  5. Optimization of a fuel cell system based on empirical data of a PEM fuel cell stack and the generalized electrochemical model. Paper no. IGEC-1-126

    International Nuclear Information System (INIS)

    A fuel cell system model is implemented in MATLAB in order to optimize the system operating conditions. The implemented fuel cell model is a modified version of the semi-empirical model introduced by researchers at the Royal Military College of Canada. In addition, in order to model the whole fuel cell system, heat transfer and gas flow considerations and the associated Balance of Plant (BOP) components are incorporated into the model. System design optimizations are carried out using three different methods, including the sequential quadratic programming (SQP) local optimization algorithm and simulated annealing (SA) and genetic algorithm (GA) global optimization algorithms. Using the operating conditions of the fuel cell system as the design variables, the net output power of the system is optimized. The three methods are used in order to gain some insight into the nature of the objective function and the performance of the different algorithms. The optimization results show a good agreement and provide useful information on the design optimization problem. This study prepares us for more complex modeling and system optimization research. (author)

  6. Asymmetric Flexible Supercapacitor Stack

    Directory of Open Access Journals (Sweden)

    Leela Mohana Reddy A

    2008-01-01

    Full Text Available AbstractElectrical double layer supercapacitor is very significant in the field of electrical energy storage which can be the solution for the current revolution in the electronic devices like mobile phones, camera flashes which needs flexible and miniaturized energy storage device with all non-aqueous components. The multiwalled carbon nanotubes (MWNTs have been synthesized by catalytic chemical vapor deposition technique over hydrogen decrepitated Mischmetal (Mm based AB3alloy hydride. The polymer dispersed MWNTs have been obtained by insitu polymerization and the metal oxide/MWNTs were synthesized by sol-gel method. Morphological characterizations of polymer dispersed MWNTs have been carried out using scanning electron microscopy (SEM, transmission electron microscopy (TEM and HRTEM. An assymetric double supercapacitor stack has been fabricated using polymer/MWNTs and metal oxide/MWNTs coated over flexible carbon fabric as electrodes and nafion®membrane as a solid electrolyte. Electrochemical performance of the supercapacitor stack has been investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.

  7. Stacked Extreme Learning Machines.

    Science.gov (United States)

    Zhou, Hongming; Huang, Guang-Bin; Lin, Zhiping; Wang, Han; Soh, Yeng Chai

    2015-09-01

    Extreme learning machine (ELM) has recently attracted many researchers' interest due to its very fast learning speed, good generalization ability, and ease of implementation. It provides a unified solution that can be used directly to solve regression, binary, and multiclass classification problems. In this paper, we propose a stacked ELMs (S-ELMs) that is specially designed for solving large and complex data problems. The S-ELMs divides a single large ELM network into multiple stacked small ELMs which are serially connected. The S-ELMs can approximate a very large ELM network with small memory requirement. To further improve the testing accuracy on big data problems, the ELM autoencoder can be implemented during each iteration of the S-ELMs algorithm. The simulation results show that the S-ELMs even with random hidden nodes can achieve similar testing accuracy to support vector machine (SVM) while having low memory requirements. With the help of ELM autoencoder, the S-ELMs can achieve much better testing accuracy than SVM and slightly better accuracy than deep belief network (DBN) with much faster training speed. PMID:25361517

  8. New polymer electrolytes for low temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sundholm, F.; Elomaa, M.; Ennari, J.; Hietala, S.; Paronen, M. [Univ. of Helsinki (Finland). Lab. of Polymer Chemistry

    1998-12-31

    Proton conducting polymer membranes for demanding applications, such as low temperature fuel cells, have been synthesised and characterised. Pre-irradiation methods are used to introduce sulfonic acid groups, directly or using polystyrene grafting, in stable, preformed polymer films. The membranes produced in this work show promise for the development of cost-effective, highly conducting membranes. (orig.)

  9. A long-term stable power supply µDMFC stack for wireless sensor node applications

    International Nuclear Information System (INIS)

    In this paper, a passive, air-breathing four-cell micro direct methanol fuel cell (µDMFC) stack featuring a fuel delivery structure for long-term and stable power supply is designed, fabricated and tested. The fuel is reserved in a T-shaped tank and diffuses through the porous diffusion layer to the catalyst at the anode. A peak power density of 25.7 mW cm−2 and a maximum power output of 113 mW are achieved with 3 M methanol at room temperature, and the stack can produce 60 mW of power, even though only 5% fuel remains in the reservoir. Combined with a low-input dc–dc convertor, the stack can realize a stable and optional constant voltage output from 1 V–6 V. The stack successfully powered a heavy metal sensor node for water environment monitoring 12 d continuously, with consumption of 10 mL 5 M methanol solution. As such, it is believed to be applicable for powering wireless sensor nodes. (paper)

  10. A long-term stable power supply µDMFC stack for wireless sensor node applications

    Science.gov (United States)

    Wu, Zonglin; Wang, Xiaohong; Li, Xiaozhao; Xu, Manqi; Liu, Litian

    2014-10-01

    In this paper, a passive, air-breathing four-cell micro direct methanol fuel cell (µDMFC) stack featuring a fuel delivery structure for long-term and stable power supply is designed, fabricated and tested. The fuel is reserved in a T-shaped tank and diffuses through the porous diffusion layer to the catalyst at the anode. A peak power density of 25.7 mW cm-2 and a maximum power output of 113 mW are achieved with 3 M methanol at room temperature, and the stack can produce 60 mW of power, even though only 5% fuel remains in the reservoir. Combined with a low-input dc-dc convertor, the stack can realize a stable and optional constant voltage output from 1 V-6 V. The stack successfully powered a heavy metal sensor node for water environment monitoring 12 d continuously, with consumption of 10 mL 5 M methanol solution. As such, it is believed to be applicable for powering wireless sensor nodes.

  11. Lowering the temperature of solid oxide fuel cells.

    Science.gov (United States)

    Wachsman, Eric D; Lee, Kang Taek

    2011-11-18

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

  12. Stacking in the Fermilab doubler

    Energy Technology Data Exchange (ETDEWEB)

    Month, M.

    1976-07-14

    The feasibility of stacking beam in a storage ring by the phase displacement technique, i.e. by the accumulation of momentum strips, is determined by a complicated interplay of many factors. Some of these factors are discussed, especially as they relate to stacking beam in the Fermilab doubler ring, but no attempt is made to present a consistent solution. An arbitrary division is made into five subject categories connected with the stacking process: (1) momentum dilution, that is, the dilution of the longitudinal phase space area; (2) rebunching the stack for acceleration; (3) the physical aperture used to create a stack of given current; (4) beam loss during stacking in a superconducting environment; and (5) field errors due to random errors in the placement and support of the superconducting coils, including the amplification of the field errors for orbits displaced from the magnet center. The basic theory is given and applied using doubler parameters.

  13. Note: A variable temperature cell for spectroscopy of thin films

    Science.gov (United States)

    Brock-Nannestad, T.; Nielsen, C. B.; Bak, H. Ø.; Pittelkow, M.

    2013-04-01

    We report the design and construction of a cell that enables precisely controlled measurement of UV/Vis spectra of thin films on transparent substrates at temperatures up to 800 K. The dimensions of the setup are accommodated by a standard Varian Cary 5E spectrophotometer allowing for widespread use in standard laboratory settings. The cell also fits in a Bio-Rad IR-spectrometer. The cell is constructed with an outer water cooled heat shield of aluminum and an inner sample holder with heating element, thermo-resistor and windows, made from nickel coated copper. The cell can operate both in air, and with an inert gas filling. We illustrate the utility of the cell by characterization of three commercially available near infrared absorbers that are commonly used for laser welding of plastics and are known to possess high thermal stability.

  14. Advanced anodes for high-temperature fuel cells

    DEFF Research Database (Denmark)

    Atkinson, A.; Barnett, S.; Gorte, R.J.;

    2004-01-01

    Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity-generation applications. The solid-oxide fuel cell (SOFC) is one of the most exciting of these...... energy technologies; it is an all-ceramic device that operates at temperatures in the range 500-1,000degreesC. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use carbon monoxide as a fuel rather than being poisoned by it, and the availability of high......-grade exhaust heat for combined heat and power, or combined cycle gas-turbine applications. Although cost is clearly the most important barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or...

  15. Beam stacking experiments at TARN

    International Nuclear Information System (INIS)

    After the first success of beam injection in TARN, August of 1979, beam experiments have been performed in succession to show the overall stacking number of around -- 300 turns, 15 RF stackings and 20 multi-turns. These results are in the close agreements with the theoretical calculations and we are now convinced that the stacking method used at TARN is quite useful for the accelerators of protons and heavy ions. (author)

  16. Optimization of Storage Temperature for Cultured ARPE-19 Cells

    Directory of Open Access Journals (Sweden)

    Lara Pasovic

    2013-01-01

    Full Text Available Purpose. The establishment of future retinal pigment epithelium (RPE replacement therapy is partly dependent on the availability of tissue-engineered RPE cells, which may be enhanced by the development of suitable storage methods for RPE. This study investigates the effect of different storage temperatures on the viability, morphology, and phenotype of cultured RPE. Methods. ARPE-19 cells were cultured under standard conditions and stored in HEPES-buffered MEM at nine temperatures (4°C, 8°C, 12°C, 16°C, 20°C, 24°C, 28°C, 32°C, and 37°C for seven days. Viability and phenotype were assessed by a microplate fluorometer and epifluorescence microscopy, while morphology was analyzed by scanning electron microscopy. Results. The percentage of viable cells preserved after storage was highest in the 16°C group (48.7%±9.8%; P<0.01 compared to 4°C, 8°C, and 24°C–37°C; P<0.05 compared to 12°C. Ultrastructure was best preserved at 12°C, 16°C, and 20°C. Expression of actin, ZO-1, PCNA, caspase-3, and RPE65 was maintained after storage at 16°C compared to control cells that were not stored. Conclusion. Out of nine temperatures tested between 4°C and 37°C, storage at 12°C, 16°C, and 20°C was optimal for maintenance of RPE cell viability, morphology, and phenotype. The preservation of RPE cells is critically dependent on storage temperature.

  17. Low Temperature Plasma Kills SCaBER Cancer Cells

    Science.gov (United States)

    Barekzi, Nazir; van Way, Lucas; Laroussi, Mounir

    2013-09-01

    Squamous cell carcinoma of the bladder is a rare type of bladder cancer that forms as a result of chronic irritation of the epithelial lining of the bladder. The cell line used in this study is SCaBER (ATCC® HTB-3™) derived from squamous cell carcinoma of the human urinary bladder. Current treatments of bladder cancer include surgery, radiation and chemotherapy. However, the cost of these treatments, the potential toxicity of the chemotherapeutic agents and the systemic side-effects warrant an alternative to current cancer treatment. This paper represents preliminary studies to determine the effects of biologically tolerant plasma (BTP) on a cell line of human bladder cancer cells. Previous work by our group using the plasma pencil revealed the efficacy of BTP on leukemia cells suspended in solution. Based on these earlier findings we hypothesized that the plasma exposure would elicit a similar programmed cell death in the SCaBER cells. Trypan blue exclusion and MTT assays revealed the cell killing after exposure to BTP. Our study indicates that low temperature plasma generated by ionizing helium gas and the reactive species may be a suitable and safe alternative for cancer therapy.

  18. Combined current and temperature mapping in an air-cooled, open-cathode polymer electrolyte fuel cell under steady-state and dynamic conditions

    Science.gov (United States)

    Meyer, Q.; Ronaszegi, K.; Robinson, J. B.; Noorkami, M.; Curnick, O.; Ashton, S.; Danelyan, A.; Reisch, T.; Adcock, P.; Kraume, R.; Shearing, P. R.; Brett, D. J. L.

    2015-11-01

    In situ diagnostic techniques provide a means of understanding the internal workings of fuel cells so that improved designs and operating regimes can be identified. Here, for the first time, a combined current density and temperature distributed measurement system is used to generate an electro-thermal performance map of an air-cooled, air-breathing polymer electrolyte fuel cell stack operating in an air/hydrogen cross-flow configuration. Analysis is performed in low- and high-current regimes and a complex relationship between localised current density, temperature and reactant supply is identified that describes the way in which the system enters limiting performance conditions. Spatiotemporal analysis was carried out to characterise transient operations in dead-ended anode/purge mode which revealed extensive current density and temperature gradients.

  19. An experimental and simulation study of novel channel designs for open-cathode high-temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Thomas, Sobi; Bates, Alex; Park, Sam;

    2016-01-01

    A minimum balance of plant (BOP) is desired for an open-cathode high temperature polymer electrolyte membrane (HTPEM) fuel cell to ensure low parasitic losses and a compact design. The advantage of an open-cathode system is the elimination of the coolant plate and incorporation of a blower for...... oxidant and coolant supply, which reduces the overall size of the stack, power losses, and results in a lower system volume. In the present study, we present unique designs for an open-cathode system which offers uniform temperature distribution with a minimum temperature gradient and a uniform flow...... distribution through each cell. Design studies were carried out to increase power density. An experimental and simulation approach was carried out to design the novel open-cathode system. Two unique parallel serpentine flow designs were developed to yield a low pressure drop and uniform flow distribution, one...

  20. Duality for commutative group stacks

    OpenAIRE

    Brochard, Sylvain

    2014-01-01

    We study in this article the dual of a (strictly) commutative group stack $G$ and give some applications. Using the Picard functor and the Picard stack of $G$, we first give some sufficient conditions for $G$ to be dualizable. Then, for an algebraic stack $X$ with suitable assumptions, we define an Albanese morphism $a_X : X\\to A^1(X)$ where $A^1(X)$ is a torsor under the dual commutative group stack $A^0(X)$ of $Pic_{X/S}$. We prove that $a_X$ satisfies a natural universal property. We give ...

  1. File list: His.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.20.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  2. File list: His.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.05.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  3. File list: His.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.50.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  4. File list: His.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.10.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  5. Highly efficient organic solar Cells based on a robust room-temperature solution-processed copper iodide hole transporter

    KAUST Repository

    Zhao, Kui

    2015-07-30

    Achieving high performance and reliable organic solar cells hinges on the development of stable and energetically suitable hole transporting buffer layers in tune with the electrode and photoactive materials of the solar cell stack. Here we have identified solution-processed copper(I) iodide (CuI) thin films with low-temperature processing conditions as an effective hole–transporting layer (HTL) for a wide range of polymer:fullerene bulk heterojunction (BHJ) systems. The solar cells using CuI HTL show higher power conversion efficiency (PCE) in standard device structure for polymer blends, up to PCE of 8.8%, as compared with poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, for a broad range of polymer:fullerene systems. The CuI layer properties and solar cell device behavior are shown to be remarkably robust and insensitive to a wide range of processing conditions of the HTL, including processing solvent, annealing temperature (room temperature up to 200 °C), and film thickness. CuI is also shown to improve the overall lifetime of solar cells in the standard architecture as compared to PEDOT:PSS. We further demonstrate promising solar cell performance when using CuI as top HTL in an inverted device architecture. The observation of uncommon properties, such as photoconductivity of CuI and templating effects on the BHJ layer formation, are also discussed. This study points to CuI as being a good candidate to replace PEDOT:PSS in solution-processed solar cells thanks to the facile implementation and demonstrated robustness of CuI thin films.

  6. Effect of elevated temperatures on cell cycle kinetics of rat gliosarcoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Ross-Riveros, P.

    1978-07-01

    9L rat gliosarcoma cells were examined in vitro for survival response to hyperthermic temperatures ranging from 39.0/sup 0/ to 45.0/sup 0/C for graded exposure times. At 43.0/sup 0/C, the split exposure response was also studied. Changes in cell cycle kinetics resulting from hyperthermia were compared for isosurvival levels achieved by appropriate exposure time to either 42.5/sup 0/C or 43.0/sup 0/C. After heat treatment, cells were held at 37.0/sup 0/C for varying recovery periods. Cells were then either prepared for flow microfluorometry (FMF), or exposed to tritiated thymidine (/sup 3/HTdR) for autoradiography. The survival studies indicated that the rate of change in cell killing for each increasing degree centigrade was greater for temperatures below 43.0/sup 0/C than for temperatures above 43.0/sup 0/C. The shoulder width of the survival curves was maximal at 42.5/sup 0/C. The shoulder width represents an important parameter since it describes a threshold time after which significant cell killing occurs. Thus both 43.0/sup 0/C, the temperature at which mortality kinetics changed, and 42.5/sup 0/C, the temperature at which the shoulder width was maximum, represent critical temperatures for the 9L cells. When 9L cells were given an initial conditioning exposure to 43.0/sup 0/C, then returned to 37/sup 0/C for 3 hrs, followed by graded exposure intervals at 43.0/sup 0/, the resulting survival curve indicated that cells required longer times for equal cell killing than for the single exposure condition, suggesting that the cells possess a capability to adapt to the higher temperature.

  7. Revisiting Stacking Fault Energy of Steels

    Science.gov (United States)

    Das, Arpan

    2016-02-01

    The stacking fault energy plays an important role in the transition of deformation microstructure. This energy is strongly dependent on the concentration of alloying elements and the temperature under which the alloy is exposed. Extensive literature review has been carried out and investigated that there are inconsistencies in findings on the influence of alloying elements on stacking fault energy. This may be attributed to the differences in chemical compositions, inaccuracy in measurements, and the methodology applied for evaluating the stacking fault energy. In the present research, a Bayesian neural network model is created to correlate the complex relationship between the extent of stacking fault energy with its influencing parameters in different austenitic grade steels. The model has been applied to confirm that the predictions are reasonable in the context of metallurgical principles and other data published in the open literature. In addition, it has been possible to estimate the isolated influence of particular variables such as nickel concentration, which exactly cannot in practice be varied independently. This demonstrates the ability of the method to investigate a new phenomenon in cases where the information cannot be accessed experimentally.

  8. The LSST Software Stack

    Science.gov (United States)

    Jenness, Timothy; LSST Data Management Team

    2016-01-01

    The Large Synoptic Survey Telescope (LSST) is an 8-m optical ground-based telescope being constructed on Cerro Pachon in Chile. LSST will survey half the sky every few nights in six optical bands. The data will be transferred to the data center in North America and within 60 seconds it will be reduced using difference imaging and an alert list be generated for the community. Additionally, annual data releases will be constructed from all the data during the 10-year mission, producing catalogs and deep co-added images with unprecedented time resolution for such a large region of sky. In the paper we present the current status of the LSST stack including the data processing components, Qserv database and data visualization software, describe how to obtain it, and provide a summary of the development road map.

  9. Instant BlueStacks

    CERN Document Server

    Judge, Gary

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. A fast-paced, example-based approach guide for learning BlueStacks.This book is for anyone with a Mac or PC who wants to run Android apps on their computer. Whether you want to play games that are freely available for Android but not your computer, or you want to try apps before you install them on a physical device or use it as a development tool, this book will show you how. No previous experience is needed as this is written in plain English

  10. Improved Wide Operating Temperature Range of Li-Ion Cells

    Science.gov (United States)

    Smart, Marshall C.; Bugga, Ratnakumar V.

    2013-01-01

    Future NASA missions aimed at exploring the Moon, Mars, and the outer planets require rechargeable batteries that can operate over a wide temperature range (-60 to +60 C) to satisfy the requirements of various applications including landers, rovers, penetrators, CEV, CLV, etc. This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. The Department of Energy (DoE) has identified a number of technical barriers associated with the development of Liion rechargeable batteries for PHEVs. For this reason, DoE has interest in the development of advanced electrolytes that will improve performance over a wide range of temperatures, and lead to long life characteristics (5,000 cycles over a 10-year life span). There is also interest in improving the high-voltage stability of these candidate electrolyte systems to enable the operation of up to 5 V with high specific energy cathode materials. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-40 to +40 C); however, the rate capability at the lower temperatures is very poor. In addition, the low-temperature performance typically deteriorates rapidly upon being exposed to high temperatures. A number of electrolyte formulations were developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl propionate (MP)-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalate borate) (LiBOB), which have previously been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. These MP-based electrolytes with additives have been shown to have improved performance in experiments with MCMB-LiNiCoAlO2 cells.

  11. A Late Pleistocene sea level stack

    OpenAIRE

    Spratt, R. M.; L. E. Lisiecki

    2015-01-01

    Late Pleistocene sea level has been reconstructed from ocean sediment core data using a wide variety of proxies and models. However, the accuracy of individual reconstructions is limited by measurement error, local variations in salinity and temperature, and assumptions particular to each technique. Here we present a sea level stack (average) which increases the signal-to-noise ratio of individual reconstructions. Specifically, we perform principal componen...

  12. Cell asymmetry correction for temperature modulated differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ishikiriyama, K.; Wunderlich, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States)

    1996-12-31

    The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on strict symmetry of the twin calorimeter, which is important for temperature-modulated DSC. Heat capacities for sapphire-filled and empty aluminium calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured. In addition, positive and negative signs of asymmetry were explored by analyzing the phase-shift between temperature and heat flow for sapphire and empty runs. The phase shifts change by more than 18{degree} depending on asymmetry sign. Once the asymmetry sign is determined, the asymmetry correction for modulated DSC can be made.

  13. Quantification of in situ temperature measurements on a PBI-based high temperature PEMFC unit cell

    DEFF Research Database (Denmark)

    Lebæk, Jesper; Ali, Syed Talat; Møller, Per;

    2010-01-01

    sensors showed minimal influence on cell performance, this difference seen in performance is believed to be caused by different bipolar plate materials. The measurement method is suitable for obtaining detailed data for validation of computational models, moreover the results indicate that the method can...... anode and cathode flow plates. The purpose of this study is to investigate the feasibility of the proposed temperature characterization method and to identify the temperature distribution on an operating HT-PEM in various modes of operation, including a 700 h sensors durability test. The embedded...

  14. Development of HT-PEMFC components and stack for CHP unit

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Jens Oluf; Li, Q. (Technical Univ. of Denmark, Dept. of Chemistry, Kgs. Lyngby (Denmark)); Terkelsen, C.; Rudbech, H.C.; Steenberg, T. (Danish Power System Aps, Charlottenlund (Denmark)); Thibault de Rycke (IRD Fuel Cell A/S, Svendborg (Denmark))

    2009-10-15

    The aim of the project has been to further develop components for an all Danish high temperature PEM fuel cells stack for application in combined heat and power units (CHP units). The final product aimed at was a 1.5-2 kW stack for operation at 150-200 deg. C. The project follows the previous PSO project 4760, 'High Temperature PEM Fuel Cell'. The project has addressed the HT-PEM fuel cells form a components point of view and the materials here for. The main areas were polymer and membrane development, electrode and MEA development (MEA = membrane electrode assembly, i.e. the cells.) and stack development. The membrane development begins with the polymer. The polymerization technique was improved significantly in two ways. Better understanding of the process and the critical issues has led to more reproducible results with repeated high molecular weights. The molecular weight is decisive for the membrane strength and durability. The process was also scaled up to 100-200 g polymer pr. batch in a new polymerization facility build during the project. It is dimensioned for larger batches too, but this was not verified during the project. The polymer cannot be purchased in the right quality for fuel cell membranes and it is important that it manufacture is not a limiting factor at the present state. Experiments with other membrane casting techniques were also made. The traditional PBI doped with phosphoric acid is still the state of art membrane for the HT-PEM fuel cells, but progress was also made with modified membranes. Different variants of PBI were synthesized and tested. Electrodes have been manufactured by a spray technique in contrast to the previously applied tape casting. The hand held spray gun previously led to an improvement of the electrodes, but the reproducibility was limited. Subsequently the construction of a semi automated spray machine was started and results like of the best hand sprayed electrodes were obtained. A viable way of MEA rim

  15. Polybenzimidazoles based on high temperature polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Linares Leon, Jose Joaquin; Camargo, Ana Paula M.; Ashino, Natalia M.; Morgado, Daniella L.; Frollini, Elisabeth; Paganin, Valdecir A.; Gonzalez, Ernesto Rafael [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil); Bajo, Justo Lobato [University of Castilla-La Mancha, Ciudad Real (Spain). Dept. of Chemical Engineering

    2010-07-01

    This work presents an interesting approach in order to enhance the performance of Polymer Electrolyte Membrane Fuel Cells (PEMFC) by means of an increase in the operational temperature. For this, two polymeric materials, Poly(2,5-bibenzimidazole) (ABPBI) and Poly[2,2'-(m-phenyl en)-5,5' bib enzimidazol] (PBI), impregnated with phosphoric acid have been utilized. These have shown excellent properties, such as thermal stability above 500 deg C, reasonably high conductivity when impregnated with H{sub 3}PO{sub 4} and a low permeability to alcohols compared to Nafion. Preliminary fuel cells measurements on hydrogen based Polymer Electrolyte Membrane Fuel Cell (PEMFC) displayed an interestingly reasonable good fuel cell performance, a quite reduced loss when the hydrogen stream was polluted with carbon monoxide, and finally, when the system was tested with an ethanol/water (E/W) fuel, it displayed quite promising results that allows placing this system as an attractive option in order to increase the cell performance and deal with the typical limitations of low temperature Nafion-based PEMFC. (author)

  16. High Temperature Polymers for use in Fuel Cells

    Science.gov (United States)

    Peplowski, Katherine M.

    2004-01-01

    NASA Glenn Research Center (GRC) is currently working on polymers for fuel cell and lithium battery applications. The desire for more efficient, higher power density, and a lower environmental impact power sources has led to interest in proton exchanges membrane fuels cells (PEMFC) and lithium batteries. A PEMFC has many advantages as a power source. The fuel cell uses oxygen and hydrogen as reactants. The resulting products are electricity, heat, and water. The PEMFC consists of electrodes with a catalyst, and an electrolyte. The electrolyte is an ion-conducting polymer that transports protons from the anode to the cathode. Typically, a PEMFC is operated at a temperature of about 80 C. There is intense interest in developing a fuel cell membrane that can operate at higher temperatures in the range of 80 C- 120 C. Operating the he1 cell at higher temperatures increases the kinetics of the fuel cell reaction as well as decreasing the susceptibility of the catalyst to be poisoned by impurities. Currently, Nafion made by Dupont is the most widely used polymer membrane in PEMFC. Nafion does not function well above 80 C due to a significant decrease in the conductivity of the membrane from a loss of hydration. In addition to the loss of conductivity at high temperatures, the long term stability and relatively high cost of Nafion have stimulated many researches to find a substitute for Nafion. Lithium ion batteries are popular for use in portable electronic devices, such as laptop computers and mobile phones. The high power density of lithium batteries makes them ideal for the high power demand of today s advanced electronics. NASA is developing a solid polymer electrolyte that can be used for lithium batteries. Solid polymer electrolytes have many advantages over the current gel or liquid based systems that are used currently. Among these advantages are the potential for increased power density and design flexibility. Automobiles, computers, and cell phones require

  17. Spherical Torus Center Stack Design

    Energy Technology Data Exchange (ETDEWEB)

    C. Neumeyer; P. Heitzenroeder; C. Kessel; M. Ono; M. Peng; J. Schmidt; R. Woolley; I. Zatz

    2002-01-18

    The low aspect ratio spherical torus (ST) configuration requires that the center stack design be optimized within a limited available space, using materials within their established allowables. This paper presents center stack design methods developed by the National Spherical Torus Experiment (NSTX) Project Team during the initial design of NSTX, and more recently for studies of a possible next-step ST (NSST) device.

  18. High Temperature PEM Fuel Cells and Organic Fuels

    DEFF Research Database (Denmark)

    Vassiliev, Anton

    harvested from the cells. This is completely avoided at the elevated temperatures with the additional benefit of increased kinetics. In the presented work an experimental setup for testing direct dimethyl ether high temperature fuel cells is described, proposing a novel design of an evaporator for a burst...... the experiments have been conducted at atmospheric pressure. Experiments with varying amounts of PBI in the cathode catalyst layer has shown that there is a minimum content limit for the preparation of a well dispersed catalyst ink of 15 carbon to PBI weight ratio in the currently used ink formulation......Modern way of life demands enormous amounts of energy, which so far has been mainly produced by combustion of various types of fossil fuel. Increased amounts of atmospheric CO2 and global warming leading to severe climate changes are the consequence. There is a need to make the energy production...

  19. High Temperature PEM Fuel Cell Systems, Control and Diagnostics

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Justesen, Kristian Kjær; Sahlin, Simon Lennart

    fuels utilizes one of the main advantages of the high temperature PEM fuel cell: robustness to fuel quality and impurities. In order for such systems to provide efficient, robust, and reliable energy, proper control strategies are needed. The complexity and nonlinearity of many of the components in such......Various system topologies are available when it comes to designing high temperature PEM fuel cell systems. Very simple system designs are possible using pure hydrogen, and more complex system designs present themselves when alternative fuels are desired, using reformer systems. The use of reformed...... systems allow the development of both simple linear and also advanced fuzzy logic and neural network controllers able to adapt system performance to the ever changing conditions which the systems operate in over their entire lifetime....

  20. Enhanced intervalley scattering in artificially stacked double-layer graphene

    International Nuclear Information System (INIS)

    We fabricated artificially stacked double-layer graphene by sequentially transferring graphene grown by chemical vapor deposition. The double-layer graphene was characterized by Raman spectroscopy and transport measurements. A weak localization effect was observed for different charge carrier densities and temperatures. The obtained intervalley scattering rate was unusually high compared to normal Bernal-stacked bilayer or single-layer graphene. The sharp point defects, local deformation, or bending of graphene plane required for intervalley scattering from one Dirac cone to another seemed to be enhanced by the artificially stacked graphene layers. (paper)

  1. Photo-Activated Low Temperature, Micro Fuel Cell Power Source

    Energy Technology Data Exchange (ETDEWEB)

    Harry L. Tuller

    2007-03-30

    A Key objective of this program is to identify electrodes that will make it possible to significantly reduce the operating temperature of micro-SOFC and thin film-based SOFCs. Towards this end, efforts are directed towards: (a) identifying the key rate limiting steps which limit presently utilized electrodes from performing at reduced temperatures, as well as, (b) investigating the use of optical, as opposed to thermal energy, as a means for photocatalyzing electrode reactions and enabling reduced operating temperatures. During Phase I, the following objectives were achieved: (a) assembly and testing of our unique Microprobe Thin Film Characterization System; (b) fabrication of the model cathode materials system in thin film form by both PLD and ink jet printing; and (c) the successful configuration and testing of the model materials as cathodes in electrochemical cells. A further key objective (d) to test the potential of illumination in enhancing electrode performance was also achieved.

  2. 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...

  3. Evaluation and application of PEMFC fuel cell's technologies developed at IPEN applied to a 500 W{sub e} fuel cell stack; Avaliacao e aplicacao de tecnologias de celulas a combustivel tipo PEMFC desenvolvida no IPEN em um modulo de 500 W{sub e} de potencia nominal

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Edgar Ferrari da

    2009-07-01

    This work is part of a research project on PEMFC technologies carried out in IPEN to develop and optimize a 500 W{sub e} fuel cell stack. The MEAs scaling up from 25 cm{sup 2} to 144 cm{sup 2} produced by the method of sieve printing; computational fluid dynamics by computer simulation of gas flow channels in bipolar plates using COMSOL{sup R} program and the use of Pt/C electrodes developed by alcohol reduction method in single cells were used to build a stack of 500 W{sub e} nominal power for possible commercial applications, produced with national technology and industrial support. A 100 hours fuel cell's test was carried out in a 144 cm{sup 2} single cell to study the stability of the MEA fabricated by sieve printing method. This single cell showed good stability within this period of time. The developed stack has reached the maximum power of 574 W{sub e} at 100 A (694.4 mA cm{sup -2}). The operating power of 500 W{sub e} was obtained at 77.7 A (540.1 mA cm{sup -2}) and potential of 6.43 V, with efficiency of 43.3%. In terms of cogeneration, the thermal power or generated heat by the stack was 652 W{sub t}. The initial estimated cost for the 500 W{sub e} stack was about R$ 4,500.00, considering only the used materials for its construction. (author)

  4. Dynamic Thermal Model And Control Of A Pem Fuel Cell System

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh

    2013-01-01

    A lumped parameter dynamic model is developed for predicting the stack performance, temperatures of the exit reactant gases and coolant liquid outlet in a proton-exchange membrane fuel cell (PEMFC) system. The air compressor, humidifier and cooling heat exchanger models are integrated to study the...... fuel cell system. A PID temperature control is implemented to study the effect of stack temperature on settling times of other variables such as stack voltage, air flow rate, oxygen excess ratio and net power of the stack. The model allows an assessment of the effect of operating parameters (stack...... power output, cooling water flow rate, air flow rate, and environmental temperature) and parameter interactions on the system thermal performance. The model represents a useful tool to determine the operating temperatures of the various components of the thermal system, and thus to fully assess the...

  5. Sensor-less control of the methanol concentration of direct methanol fuel cells at varying ambient temperatures

    International Nuclear Information System (INIS)

    Highlights: • A new algorithm is proposed for the sensor-less control of methanol concentration. • Two different strategies are used depending on the ambient temperatures. • Energy efficiency of the DMFC system has been improved by using the new algorithm. - Abstract: A new version of an algorithm is used to control the methanol concentration in the feed of DMFC systems without using methanol sensors under varying ambient temperatures. The methanol concentration is controlled indirectly by controlling the temperature of the DMFC stack, which correlates well with the methanol concentration. Depending on the ambient temperature relative to a preset reference temperature, two different strategies are used to control the stack temperature: either reducing the cooling rate of the methanol solution passing through an anode-side heat exchanger; or, lowering the pumping rate of the pure methanol to the depleted feed solution. The feasibility of the algorithm is evaluated using a DMFC system that consists of a 200 W stack and the balance of plant (BOP). The DMFC system includes a sensor-less methanol controller that is operated using a LabView system as the central processing unit. The algorithm is experimentally confirmed to precisely control the methanol concentration and the stack temperature at target values under an environment of varying ambient temperatures

  6. Seismic qualification of ventilation stack

    International Nuclear Information System (INIS)

    This paper describes the method to be used to qualify the 105 K ventilation stack at the U.S. Department of Energy's Hanford Site, near Richland, Washington, under seismic and wind loadings. The stack stands at 175 ft (53.34 m), with a diameter tapering from 22 ft (6.71 m) at the foundation to 12.83 ft (3.91 m) at the top. Although the stack is classified as Safety Class 3 (low hazard), it is treated as a Safety Class 1 (high hazard) component, as failure could damage a Safety Class 1 facility (the irradiated fuel storage basin). The evaluation used U.S. Department of Energy criteria specified in UCRL 15910 (1990). The seismic responses of the stack under earthquake loading were obtained from modal analyses with response spectrum input that used the ANSYS (1989) finite-element computer code. The moments and shear forces from the results of seismic analysis were used to qualify the reinforcement capacity of the stack structure by the ultimate-strength method. The wind forces acting on the stack in both along-wind and crosswind directions were also calculated. Presented are evaluations of the soil bearing pressure, the moment, and the shear capacity of the stack foundation

  7. Seismic qualification of ventilation stack

    International Nuclear Information System (INIS)

    This paper describes the method to be used to qualify the 105 K ventilation stack at the US Department of Energy's Hanford Site, near Richland, Washington, under seismic and wind loadings. The stack stands at 175 ft (53.34 m), with a diameter tapering from 22 ft (6.71 m) at the foundation to 12.83 ft (3.91 m) at the top. Although the stack is classified as Safety Class 3 (low hazard), it is treated as a Safety Class 1 (high hazard) component, as failure could damage a Safety Class 1 facility (the irradiated fuel storage basin). The evaluation used US Department of Energy criteria specified in UCRL 15910 (1990). The seismic responses of the stack under earthquake loading were obtained from modal analyses with response spectrum input that used the ANSYS (1989) finite-element computer code. The moments and shear forces from the results of seismic analysis were used to qualify the reinforcement capacity of the stack structure by the ultimate-strength method. The wind forces acting on the stack in both along-wind and are evaluations of the soil bearing pressure, the moment, and the shear capacity of the stack foundation

  8. Environmental assessment of phosphogypsum stacks

    International Nuclear Information System (INIS)

    Phosphogypsum is one of the most important by-products of phosphate fertilizer industry. It is kept in large stacks to the west of Homs city. Storing Phosphogypsum as open stacks exposed to various environmental effects, wind and rain, may cause pollution of the surrounding ecosystem (soil, plant, water and air). This study was carried out in order to assess the environmental impact of Phosphogypsum stacks on the surrounding ecosystem. The obtained results show that Phosphogypsum stacks did not increase the concentration of radionuclides, i.e. Radon-222 and Radium-226, the external exposed dose of gamma rays, as well as the concentration of heavy metals in the components of the ecosystem, soil, plant, water and air, as their concentrations did not exceed the permissible limits. However, the concentration of fluorine in the upper layer of soil, located to the east of the Phosphogypsum stacks, increased sufficiently, especially in the dry period of the year. Also, the concentration of fluoride in plants growing up near-by the Phosphogypsum stacks was too high, exceeded the permissible levels. This was reflected in poising plants and animals, feeding on the plants. Consequently, increasing the concentration of fluoride in soil and plants is the main impact of Phosphogypsum stacks on the surrounding ecosystem. Minimising this effect could be achieved by establishing a 50 meter wide protection zone surrounding the Phosphogypsum stacks, which has to be planted with non palatable trees, such as pine and cypress, forming wind barriers. Increasing the concentrations of heavy metals and fluoride in infiltrated water around the stacks was high; hence cautions must be taken to prevent its usage in any application or disposal in adjacent rivers and leaks.(author)

  9. High temperature PEM fuel cells - Degradation and durability

    Energy Technology Data Exchange (ETDEWEB)

    Araya, S.S.

    2012-12-15

    This work analyses the degradation issues of a High Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC). It is based on the assumption that given the current challenges for storage and distribution of hydrogen, it is more practical to use liquid alcohols as energy carriers for fuel cells. Among these, methanol is very attractive, as it can be obtained from a variety of renewable sources and has a relatively low reforming temperature for the production of hydrogen rich gaseous mixture. The effects on HT-PEMFC of the different constituents of this gaseous mixture, known as a reformate gas, are investigated in the current work. For this, an experimental set up, in which all these constituents can be fed to the anode side of a fuel cell for testing, is put in place. It includes mass flow controllers for the gaseous species, and a vapor delivery system for the vapor mixture of the unconverted reforming reactants. Electrochemical Impedance Spectroscopy (EIS) is used to characterize the effects of these impurities. The effects of CO were tested up to 2% by volume along with other impurities. All the reformate impurities, including ethanol-water vapor mixture, cause loss in the performance of the fuel cell. In general, CO{sub 2} dilutes the reactants, if tested alone at high operating temperatures (180 C), but tends to exacerbate the effects of CO if they are tested together. On the other hand, CO and methanol-water vapor mixture degrade the fuel cell proportionally to the amounts in which they are tested. In this dissertation some of the mechanisms with which the impurities affect the fuel cell are discussed and interdependence among the effects is also studied. This showed that the combined effect of reformate impurities is more than the arithmetic sum of the individual effects of reformate constituents. The results of the thesis help to understand better the issues of degradation and durability in fuel cells, which can help to make them more durable and

  10. “国井”芝麻香高温堆积过程中微生物与香味成分的变化规律研究%Study on the Change Rules of Microflora and Flavoring Compositions of "Guojing" Sesame-flavor Liquor during High-temperature Stacking

    Institute of Scientific and Technical Information of China (English)

    许玲; 张秋月

    2012-01-01

    运用传统的微生物培养技术与气相色谱分析技术相结合,对扳倒井芝麻香高温堆积过程中微生物与香味成分的变化规律进行了研究,为深入揭示高温堆积在芝麻香型白酒生产中的重要作用奠定了基础。%A study of the change rules of microflora and flavoring compositions of Sesame-flavor liquor during high-temperature stacking was carded out by use of traditional microbe culture methods coupled with GC analytic techniques, which could lay solid foundation for revealing the important roles of high-temperature stacking in Sesame-flavour liquor production.

  11. Proton Exchange Membrane Fuel Cells Applied for Transport Sector

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Rokni, Masoud

    2010-01-01

    A thermodynamic analysis of a PEMFC (proton exchange membrane fuel cell) is investigated. PEMFC may be the most promising technology for fuel cell automotive systems, which is operating at quite low temperatures, (between 60 to 80℃). In this study the fuel cell motive power part of a lift truck has...... been investigated. The fuel cell stack used in this model is developed using a Ballard PEMFC [1], so that the equations used in the stack modeling are derived from the experimental data. The stack can produce 3 to 15 kilowatt electricity depending on the number of cells used in the stack. Some of the...... investigated. In addition, different stack design schemes have been proposed and their effect on system efficiency has been investigated....

  12. Silicon Heterojunction Solar Cells: Temperature Impact on Passivation and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Seif, J.; Krishnamani, G.; Demaurex, B.; Martin de Nicholas, S.; Holm, N.; Ballif, C.; De Wolf, S.

    2015-03-23

    Photovoltaic devices deployed in the field can reach operation temperatures (T) as high as 90 °C [1]. Hence, their temperature coefficients (TC1) are of great practical importance as they determine their energy yield. In this study we concentrate on T-related lifetime variations of amorphous/crystalline interfaces and study their influence on the TCs of the individual solar cell parameters. We find that both the open-circuit voltage (Voc) and fill factor (FF) are influenced by these lifetime variations. However, this is only a minor effect compared to the dominant increase of the intrinsic carrier density and the related increase in dark saturation current density. Additionally, in this paper we will show that the TCVoc does not depend solely on the initial value of the Voc [2, 3], but that the structure of the device has to be considered as well.

  13. Electrolytes For Intermediate Temperature Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Rękas M.

    2015-06-01

    Full Text Available Solid electrolytes for construction of the intermediate-temperature solid oxide fuel cells, IT-SOFC, have been reviewed. Yttrium stabilized tetragonal zirconia polycrystals, YTZP, as a potential electrolyte of IT-SOFC have been highlighted. The experimental results involving structural, microstructural, electrical properties based on our own studies were presented. In order to study aluminum diffusion in YTZP, aluminum oxide was deposited on the surface of 3 mol.% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP. The samples were annealed at temperatures from 1523 to 1773 K. Diffusion profiles of Al in the form of mean concentration vs. depth in B-type kinetic region were investigated by secondary ion mass spectroscopy (SIMS. Both the lattice (DB and grain boundary (DGB diffusion were determined.

  14. Time-predictable Stack Caching

    DEFF Research Database (Denmark)

    Abbaspourseyedi, Sahar

    complicated and less imprecise. Time-predictable computer architectures provide solutions to this problem. As accesses to the data in caches are one source of timing unpredictability, devising methods for improving the timepredictability of caches are important. Stack data, with statically analyzable...... addresses, provides an opportunity to predict and tighten the WCET of accesses to data in caches. In this thesis, we introduce the time-predictable stack cache design and implementation within a time-predictable processor. We introduce several optimizations to our design for tightening the WCET while...... keeping the timepredictability of the design intact. Moreover, we provide a solution for reducing the cost of context switching in a system using the stack cache. In design of these caches, we use custom hardware and compiler support for delivering time-predictable stack data accesses. Furthermore, for...

  15. On the influence of temperature on PEM fuel cell operation

    Science.gov (United States)

    Coppo, M.; Siegel, N. P.; Spakovsky, M. R. von

    The 3D implementation of a previously developed 2D PEMFC model [N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, A two-dimensional computational model of a PEMFC with liquid water transport, J. Power Sources 128 (2) (2004) 173-184; N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81-89] has been used to analyze the various pathways by which temperature affects the operation of a proton exchange membrane fuel cell [M. Coppo, CFD analysis and experimental investigation of proton exchange membrane fuel cells, Ph.D. Dissertation, Politecnico di Torino, Turin, Italy, 2005]. The original model, implemented in a specially modified version of CFDesign ® [CFDesign ® V5.1, Blue Ridge Numerics, 2003] , accounts for all of the major transport processes including: (i) a three-phase model for water transport in the liquid, vapor and dissolved phases, (ii) proton transport, (iii) gaseous species transport and reaction, (iv) an agglomerate model for the catalyst layers and (v) gas phase momentum transport. Since the details of it have been published earlier [N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, A two-dimensional computational model of a PEMFC with liquid water transport, J. Power Sources 128 (2) (2004) 173-184; N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81-89; N.P. Siegel, Development and validation of a computational model for a proton exchange membrane fuel cell, Ph.D. Dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA, 2003], only new features are briefly discussed in the present work. In particular, the model has been extended in order to account for the temperature dependence of all of the physical properties involved in the model formulation. Moreover, a novel model has been developed to describe liquid

  16. Identification of a novel temperature sensitive promoter in cho cells

    Directory of Open Access Journals (Sweden)

    Hesse Friedemann

    2011-05-01

    Full Text Available Abstract Background The Chinese hamster ovary (CHO expression system is the leading production platform for manufacturing biopharmaceuticals for the treatment of numerous human diseases. Efforts to optimize the production process also include the genetic construct encoding the therapeutic gene. Here we report about the successful identification of an endogenous highly active gene promoter obtained from CHO cells which shows conditionally inducible gene expression at reduced temperature. Results Based on CHO microarray expression data abundantly transcribed genes were selected as potential promoter candidates. The S100a6 (calcyclin and its flanking regions were identified from a genomic CHO-K1 lambda-phage library. Computational analyses showed a predicted TSS, a TATA-box and several TFBSs within the 1.5 kb region upstream the ATG start signal. Various constructs were investigated for promoter activity at 37°C and 33°C in transient luciferase reporter gene assays. Most constructs showed expression levels even higher than the SV40 control and on average a more than two-fold increase at lower temperature. We identified the core promoter sequence (222 bp comprising two SP1 sites and could show a further increase in activity by duplication of this minimal sequence. Conclusions This novel CHO promoter permits conditionally high-level gene expression. Upon a shift to 33°C, a two to three-fold increase of basal productivity (already higher than SV40 promoter is achieved. This property is of particular advantage for a process with reduced expression during initial cell growth followed by the production phase at low temperature with a boost in expression. Additionally, production of toxic proteins becomes feasible, since cell metabolism and gene expression do not directly interfere. The CHO S100a6 promoter can be characterized as cold-shock responsive with the potential for improving process performance of mammalian expression systems.

  17. Recent Progress At The Idaho National Laboratory In High Temperature Electrolysis For Hydrogen And Syngas Production

    Energy Technology Data Exchange (ETDEWEB)

    C. Stoots; J. O' Brien; J. Herring; J. Hartvigsen

    2008-11-01

    This paper presents the most recent results of experiments conducted at the Idaho National Laboratory (INL) studying electrolysis of steam and coelectrolysis of steam / carbon dioxide in solid-oxide electrolysis stacks. Single button cell tests as well as multi-cell stack testing have been conducted. Multi-cell stack testing used 10 x 10 cm cells (8 x 8 cm active area) supplied by Ceramatec, Inc (Salt Lake City, Utah, USA) and ranged from 10 cell short stacks to 240 cell modules. Tests were conducted either in a bench-scale test apparatus or in a newly developed 5 kW Integrated Laboratory Scale (ILS) test facility. Gas composition, operating voltage, and operating temperature were varied during testing. The tests were heavily instrumented, and outlet gas compositions were monitored with a gas chromatograph. The ILS facility is currently being expanded to 15 kW testing capacity (H2 production rate based upon lower heating value).

  18. Direct Utilization of Coal Syngas in High Temperature Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Ismail B. [West Virginia University, Morgantown, WV (United States)

    2014-10-30

    This EPSCoR project had two primary goals: (i) to build infrastructure and work force at WVU to support long-term research in the area of fuel cells and related sciences; (ii) study effects of various impurities found in coal-syngas on performance of Solid Oxide Fuel Cells (SOFC). As detailed in this report the WVU research team has made significant accomplishments in both of these areas. What follows is a brief summary of these accomplishments: State-of-the-art test facilities and diagnostic tools have been built and put into use. These include cell manufacturing, half-cell and full-cell test benches, XPS, XRD, TEM, Raman, EDAX, SEM, EIS, and ESEM equipment, unique in-situ measurement techniques and test benches (Environmental EM, Transient Mass-Spectrometer-MS, and IR Optical Temperature measurements). In addition, computational capabilities have been developed culminating in a multi-scale multi-physics fuel cell simulation code, DREAM-SOFC, as well as a Beowulf cluster with 64 CPU units. We have trained 16 graduate students, 10 postdoctoral fellows, and recruited 4 new young faculty members who have actively participated in the EPSCoR project. All four of these faculty members have already been promoted to the tenured associate professor level. With the help of these faculty and students, we were able to secure 14 research awards/contracts amounting to a total of circa $5.0 Million external funding in closely related areas of research. Using the facilities mentioned above, the effects of PH3, HCl, Cl2, and H2S on cell performance have been studied in detail, mechanisms have been identified, and also remedies have been proposed and demonstrated in the laboratory. For example, it has been determined that PH3 reacts rapidly with Ni to from secondary compounds which may become softer or even melt at high temperature and then induce Ni migration to the surface of the cell changing the material and micro-structural properties of the cell drastically. It is found that

  19. Development of novel proton exchange membrane fuel cells using stamped metallic bipolar plates

    Science.gov (United States)

    Jung, Shiauh-Ping; Lee, Chun-I.; Chen, Chi-Chang; Chang, Wen-Sheng; Yang, Chang-Chung

    2015-06-01

    This study presents the development of novel proton exchange membrane fuel cells using stamped metallic bipolar plates. To achieve uniformly distributed and low pressure-drop flow fields within fuel cells, a novel bipolar plate with straight channels is designed and verification of a fuel-cell short stack using this bipolar plate is performed. In the experiments, low-temperature and low-humidity operations and high-temperature and high-humidity operations are adopted to evaluate effects of stack temperature and inlet relative humidity on performance at various outlet pressures. Experimental results show that under low-temperature and low-humidity operations, increasing the outlet pressure enhances stack performance and reduces performance differences between various stack temperatures. Under high-temperature and high-humidity operations, stack performance increases with increasing outlet pressures, while the extent of their increase becomes smaller. Compared to low-temperature and low-humidity operations, high-temperature and high-humidity operations have better electrochemical reactions and membrane hydration and, thus, better stack performance. In this study, the operation with a stack temperature of 80 °C and outlet pressure of 4 atm produces the best performance of 1100 mA cm-2 at 0.646 V.

  20. Design and Fabrication of Stack Micro-Direct Methanol Fuel Cell Using Silicon and PDMS%采用硅和PDMS的堆栈式微型直接甲醇燃料电池的设计和制作

    Institute of Scientific and Technical Information of China (English)

    曾毅波; 陈观生; 赵祖光; 刘畅; 刘俊; 王婷婷; 郭航

    2013-01-01

    In order to avoid cracks of the silicon flow field plate caused by high package pressure, silicon and PDMS (Polydimethylsiloxane) are used as anodic and cathode flow field plate respectively in the stack μ-DMFC ( Micro-direct methanol fuel cell). The anodic flow field plate based on silicon is fabricated with MEMS( Micro-Electro-Mechanical Systems)technology,and cathode flow field plate is fabricated using PDMS and its metallic performance is evidently improved by means of integral shaping of copper foil and cathode flow field plate, organic cleaning and activation on PDMS surface. The output of stack μ-DMFC is tested and analyzed, in which 3 different flow channel structures on the anodic plate are introduced. Tested results verify that adhesive capability and strengthen between post-activated PDMS and Cr/Au are greatly improved, and when micro blocks and through holes are introduced alternately in the flow channel of anodic flow field plate the stack μ-DMFC can obtain the maximum output, with voltage of 0. 5 V,current density of 81. 25 mA/cm2 and output power density of 7. 73 mW/cm2. This study shows that using silicon and PDMS as flow field plate respectively not only simplifies the structure of stack μ-DMFC but also cushions clamping force and effectively protects anodic flow field plate,and furthermore to increase the output of stack μ-DMFC by optimizing structure of flow channels on the anodic flow field plate.%在堆栈式微型直接甲醇燃料电池μ-DMFC(Micro-Direct Methanol Fuel Cell)中,为了避免硅基流场板因为封装压力过大而破裂,采用了硅和PDMS(Polydimethylsiloxane,聚二甲基硅氧烷)材料分别制作阳极和阴极流场板.首先,采用微机电系统MEMS(Micro-Electro-Mechanical Systems)技术制作硅基阳极流场板.其次,通过铜箔与阴极流场板一体成型、有机清洗和PDMS表面活化等改进措施显著提升了PDMS阴极流场板金属化的能力.最后,比较和分析阳极流场板上3

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  14. File list: DNS.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

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  15. File list: Pol.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

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  16. Low temperature tolerance of human embryonic stem cells

    Directory of Open Access Journals (Sweden)

    Boon Chin Heng, Kumar Jayaseelan Vinoth, Hua Liu, Manoor Prakash Hande, Tong Cao

    2006-01-01

    Full Text Available This study investigated the effects of exposing human embryonic stem cells (hESC to 4oC and 25oC for extended durations of 24h and 48h respectively. Cell survivability after low temperature exposure was assessed through the MTT assay. The results showed that hESC survivability after exposure to 25oC and 4oC for 24h was 77.3 ± 4.8 % and 64.4 ± 4.4 % respectively (significantly different, P < 0.05. The corresponding survival rates after 48h exposure to 25oC and 4oC was 71.0 ± 0.5 % and 69.0 ± 2.3 % respectively (not significantly different, P > 0.05. Spontaneous differentiation of hESC after low temperature exposure was assessed by morphological observations under bright-field and phase-contrast microscopy, and by immunocytochemical staining for the pluripotency markers SSEA-3 and TRA-1-81. hESC colonies were assigned into 3 grades according to their degree of spontaneous differentiation: (1 Grade A which was completely or mostly undifferentiated, (2 Grade B which was partially differentiated, and (3 Grade C which was mostly differentiated. In all low temperature exposed groups, about 95% of colonies remain undifferentiated (Grade A, which was not significantly different (P > 0.05 from the unexposed control group maintained at 37oC. Additionally, normal karyotype was maintained in all low temperature-exposed groups, as assessed by fluorescence in situ hybridization (FISH of metaphase spreads with telomere and centromere-specific PNA probes. Further analysis with m-FISH showed that chromosomal translocations were absent in all experimental groups. Hence, hESC possess relatively high-tolerance to extended durations of low temperature exposure, which could have useful implications for the salvage of hESC culture during infrequent occurrences of incubator break-down and power failure.

  17. Stacking-dependent electronic property of trilayer graphene epitaxially grown on Ru(0001)

    International Nuclear Information System (INIS)

    The growth, atomic structure, and electronic property of trilayer graphene (TLG) on Ru(0001) were studied by low temperature scanning tunneling microscopy and spectroscopy in combined with tight-binding approximation (TBA) calculations. TLG on Ru(0001) shows a flat surface with a hexagonal lattice due to the screening effect of the bottom two layers and the AB-stacking in the top two layers. The coexistence of AA- and AB-stacking in the bottom two layers leads to three different stacking orders of TLG, namely, ABA-, ABC-, and ABB-stacking. STS measurements combined with TBA calculations reveal that the density of states of TLG with ABC- and ABB-stacking is characterized by one and two sharp peaks near to the Fermi level, respectively, in contrast to the V-shaped feature of TLG with ABA-stacking. Our work demonstrates that TLG on Ru(0001) might be an ideal platform for exploring stacking-dependent electronic properties of graphene

  18. Stacking-dependent electronic property of trilayer graphene epitaxially grown on Ru(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Que, Yande; Xiao, Wende, E-mail: wdxiao@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn; Chen, Hui; Wang, Dongfei; Du, Shixuan; Gao, Hong-Jun, E-mail: wdxiao@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn [Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-12-28

    The growth, atomic structure, and electronic property of trilayer graphene (TLG) on Ru(0001) were studied by low temperature scanning tunneling microscopy and spectroscopy in combined with tight-binding approximation (TBA) calculations. TLG on Ru(0001) shows a flat surface with a hexagonal lattice due to the screening effect of the bottom two layers and the AB-stacking in the top two layers. The coexistence of AA- and AB-stacking in the bottom two layers leads to three different stacking orders of TLG, namely, ABA-, ABC-, and ABB-stacking. STS measurements combined with TBA calculations reveal that the density of states of TLG with ABC- and ABB-stacking is characterized by one and two sharp peaks near to the Fermi level, respectively, in contrast to the V-shaped feature of TLG with ABA-stacking. Our work demonstrates that TLG on Ru(0001) might be an ideal platform for exploring stacking-dependent electronic properties of graphene.

  19. Status of the Solid Oxide Fuel Cell Development at Topsoe Fuel Cell A/S and DTU Energy Conversion

    DEFF Research Database (Denmark)

    Christiansen, N.; Primdahl, S.; Wandel, Marie; Ramousse, Severine; Hagen, Anke

    2013-01-01

    manufacturing of materials, cells and stacks based on state of the art as well as innovative strategies. Today TOFC provides the SOFC technology platform: Cells, stacks, integrated multi stack module and PowerCore units that integrate stack modules with hot fuel processing units for high electrical efficiency....... TOFC collaborates with integrator partners to develop, test and demonstrate possibilities and challenges in case of CHP, distributed generation, transportation application and electrolysis. Aiming at improved reliability, robustness and low material cost, TOFC has in the collaboration with DTU...... increased the efforts on development of next generation cells with metallic support including novel infiltrated nano-structured electrodes for operation in the temperature range 600-700 oC. Recently, record-breaking results have been obtained on cell level as well as on stack level....

  20. High Temperature Alkaline Electrolysis Cells with Metal Foam Based Gas Diffusion Electrodes

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2016-01-01

    Alkaline electrolysis cells operating at 250°C and 40 bar are able to convert electrical energy into hydrogen at very high efficiencies and power densities. In the present work we demonstrate the application of a PTFE hydrophobic network and Ag nanowires as oxygen evolution electrocatalyst in the...... metal foam based gas diffusion electrodes. A novel cell production method, based on tape casting and hot pressing, was developed which allows to increase the cell size from lab scale (1 cm2) to areas of 25 cm2 or larger. The thickness of the electrolyte matrix could be adjusted to only 200 μm, achieving...... novel cell concept promises more than a 10-fold improvement in power density, compared to conventional alkaline electrolysis cells, and thereby equivalent reduction in stack size and cost....

  1. Permanent cell lines established from ts-COS cells that regulate by temperature the amplification and expression of cloned genes.

    OpenAIRE

    de la Luna, S; A. Portela; Martínez, C; Ortín, J

    1987-01-01

    Temperature-sensitive COS cells have been transformed at restrictive temperature with SV40 replicons containing the neo or pac markers. Puromycin-resistant cell clones maintained at the restrictive temperature contain the pac gene integrated into the cell DNA. However, when the cells are shifted to the permissive temperature the pac gene is amplified in episomal forms up to 2-4 X 10(4) copies per cell. Concomitant with this, an induction of 35-300 fold in the levels of puromycin acetyl transf...

  2. High Temperature Steam Electrolysis: Demonstration of Improved Long-Term Performance

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; X. Zhang; R. C. O' Brien; G. Tao

    2011-11-01

    Long-term performance is an ongoing issue for hydrogen production based on high-temperature steam electrolysis (HTSE). For commercial deployment, solid-oxide electrolysis stacks must achieve high performance with long-term degradation rates of {approx}0.5%/1000 hours or lower. Significant progress has been achieved toward this goal over the past few years. This paper will provide details of progress achieved under the Idaho National Laboratory high temperature electrolysis research program. Recent long-term stack tests have achieved high initial performance with degradation rates less than 5%/khr. These tests utilize internally manifolded stacks with electrode-supported cells. The cell material sets are optimized for the electrolysis mode of operation. Details of the cells and stacks will be provided along with details of the test apparatus, procedures, and results.

  3. Carbon Neutral Production Of Syngas Via High Temperature Electrolytic Reduction Of Steam And CO2

    Energy Technology Data Exchange (ETDEWEB)

    C. Stoots; J. O' Brien; J. Hartvigsen

    2007-11-01

    This paper presents the most recent results of experiments conducted at the Idaho National Laboratory (INL) studying coelectrolysis of steam and carbon dioxide in solid-oxide electrolysis stacks. Two 10-cell planar stacks were tested under various gas compositions, operating voltages, and operating temperatures. The tests were heavily instrumented, and outlet gas compositions were monitored with a gas chromatograph. Measured outlet compositions, open cell potentials, and coelectrolysis thermal neutral voltages compared reasonably well with a coelectrolysis computer model developed at the INL. Stack ASRs did not change significantly when switching from electrolysis to coelectrolysis operation.

  4. A Total Cost of Ownership Model for Low Temperature PEM Fuel Cells in Combined Heat and Power and Backup Power Applications

    Energy Technology Data Exchange (ETDEWEB)

    University of California, Berkeley; Wei, Max; Lipman, Timothy; Mayyas, Ahmad; Chien, Joshua; Chan, Shuk Han; Gosselin, David; Breunig, Hanna; Stadler, Michael; McKone, Thomas; Beattie, Paul; Chong, Patricia; Colella, Whitney; James, Brian

    2014-06-23

    A total cost of ownership model is described for low temperature proton exchange membrane stationary fuel cell systems for combined heat and power (CHP) applications from 1-250kW and backup power applications from 1-50kW. System designs and functional specifications for these two applications were developed across the range of system power levels. Bottom-up cost estimates were made for balance of plant costs, and detailed direct cost estimates for key fuel cell stack components were derived using design-for-manufacturing-and-assembly techniques. The development of high throughput, automated processes achieving high yield are projected to reduce the cost for fuel cell stacks to the $300/kW level at an annual production volume of 100 MW. Several promising combinations of building types and geographical location in the U.S. were identified for installation of fuel cell CHP systems based on the LBNL modelling tool DER CAM. Life-cycle modelling and externality assessment were done for hotels and hospitals. Reduced electricity demand charges, heating credits and carbon credits can reduce the effective cost of electricity ($/kWhe) by 26-44percent in locations such as Minneapolis, where high carbon intensity electricity from the grid is displaces by a fuel cell system operating on reformate fuel. This project extends the scope of existing cost studies to include externalities and ancillary financial benefits and thus provides a more comprehensive picture of fuel cell system benefits, consistent with a policy and incentive environment that increasingly values these ancillary benefits. The project provides a critical, new modelling capacity and should aid a broad range of policy makers in assessing the integrated costs and benefits of fuel cell systems versus other distributed generation technologies.

  5. The Golgi apparatus in the endomembrane-rich gastric parietal cells exist as functional stable mini-stacks dispersed throughout the cytoplasm

    OpenAIRE

    Gunn, Priscilla A.; Gliddon, Briony L.; Londrigan, Sarah L.; Lew, Andrew M.; van Driel, Ian R.; Gleeson, Paul A.

    2011-01-01

    Background information. Acid-secreting gastric parietal cells are polarized epithelial cells that harbour highly abundant and specialized, H+,K+ ATPase-containing, tubulovesicular membranes in the apical cytoplasm. The Golgi apparatus has been implicated in the biogenesis of the tubulovesicular membranes; however, an unanswered question is how a typical Golgi organization could regulate normal membrane transport within the membrane-dense cytoplasm of parietal cells. Results. Here, we demonstr...

  6. Glassy carbon based supercapacitor stacks

    Energy Technology Data Exchange (ETDEWEB)

    Baertsch, M.; Braun, A.; Koetz, R.; Haas, O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Considerable effort is being made to develop electrochemical double layer capacitors (EDLC) that store relatively large quantities of electrical energy and possess at the same time a high power density. Our previous work has shown that glassy carbon is suitable as a material for capacitor electrodes concerning low resistance and high capacity requirements. We present the development of bipolar electrochemical glassy carbon capacitor stacks of up to 3 V. Bipolar stacks are an efficient way to meet the high voltage and high power density requirements for traction applications. Impedance and cyclic voltammogram measurements are reported here and show the frequency response of a 1, 2, and 3 V stack. (author) 3 figs., 1 ref..

  7. Removal of NOx with Porous Cell Stacks with La0.85Sr0.15CoxMn1-xO3+δ-Ce0.9Gd0.1O1.95 Electrodes Infiltrated with BaO

    DEFF Research Database (Denmark)

    Werchmeister, Rebecka Maria Larsen; Bentzen, Janet Jonna; Andersen, Kjeld Bøhm; Kammer Hansen, Kent

    2014-01-01

    Porous cell stacks with composite electrodes of La0.85Sr0.15CoxMn1-xO3-Ce0.9Gd0.1O1.95 were tested for activity toward selective electrochemical reduction of NOx to N2 in the presence of 10% O2. The cell stacks were produced by tape casting, laminating and sintering the backbone structure followed...

  8. Attachment method for stacked integrated circuit (IC) chips

    Science.gov (United States)

    Bernhardt, Anthony F.; Malba, Vincent

    1999-01-01

    An attachment method for stacked integrated circuit (IC) chips. The method involves connecting stacked chips, such as DRAM memory chips, to each other and/or to a circuit board. Pads on the individual chips are rerouted to form pads on the side of the chip, after which the chips are stacked on top of each other whereby desired interconnections to other chips or a circuit board can be accomplished via the side-located pads. The pads on the side of a chip are connected to metal lines on a flexible plastic tape (flex) by anisotropically conductive adhesive (ACA). Metal lines on the flex are likewise connected to other pads on chips and/or to pads on a circuit board. In the case of a stack of DRAM chips, pads to corresponding address lines on the various chips may be connected to the same metal line on the flex to form an address bus. This method has the advantage of reducing the number of connections required to be made to the circuit board due to bussing; the flex can accommodate dimensional variation in the alignment of chips in the stack; bonding of the ACA is accomplished at low temperature and is otherwise simpler and less expensive than solder bonding; chips can be bonded to the ACA all at once if the sides of the chips are substantially coplanar, as in the case for stacks of identical chips, such as DRAM.

  9. Planar array stack design aided by rapid prototyping in development of air-breathing PEMFC

    Science.gov (United States)

    Chen, Chen-Yu; Lai, Wei-Hsiang; Weng, Biing-Jyh; Chuang, Huey-Jan; Hsieh, Ching-Yuan; Kung, Chien-Chih

    The polymer electrolyte membrane fuel cell (PEMFC) is one of the most important research topics in the new and clean energy area. The middle or high power PEMFCs can be applied to the transportation or the distributed power system. But for the small power application, it is needed to match the power requirement of the product generally. On the other hand, the direct methanol fuel cell (DMFC) is one of the most common type that researchers are interested in, but recently the miniature or the micro-PEMFCs attract more attention due to their advantages of high open circuit voltage and high power density. The objective of this study is to develop a new air-breathing planar array fuel cell stacked from 10 cells made by rapid prototyping technology which has potential for fast commercial design, low cost manufacturing, and even without converters/inverters for the system. In this paper, the main material of flow field plates is acrylonitrile-butadiene-styrene (ABS) which allows the fuel cell be mass-manufactured by plastic injection molding technology. The rapid prototyping technology is applied to construct the prototype and verify the practicability of the proposed stack design. A 10-cell air-breathing miniature PEMFC stack with a volume of 6 cm × 6 cm × 0.9 cm is developed and tested. Its segmented membrane electrode assembly (MEA) is designed with the active surface area of 1.3 cm × 1.3 cm in each individual MEA. The platinum loading at anode and cathode are 0.2 mg cm -2 and 0.4 mg cm -2, respectively. Results show that the peak power densities of the parallel connected and serial connected stack are 99 mW cm -2 at 0.425 V and 92 mW cm -2 at 4.25 V, respectively under the conditions of 70 °C relative saturated humidity (i.e., dew point temperature), ambient temperature and free convection air. Besides, the stack performance is increased under forced convection. If the cell surface air is blown by an electric fan, the peak power densities of parallel connected and

  10. Multiple Segmentation of Image Stacks

    DEFF Research Database (Denmark)

    Smets, Jonathan; Jaeger, Manfred

    2014-01-01

    We propose a method for the simultaneous construction of multiple image segmentations by combining a recently proposed “convolution of mixtures of Gaussians” model with a multi-layer hidden Markov random field structure. The resulting method constructs for a single image several, alternative...... segmentations that capture different structural elements of the image. We also apply the method to collections of images with identical pixel dimensions, which we call image stacks. Here it turns out that the method is able to both identify groups of similar images in the stack, and to provide segmentations...

  11. Simulating Small-Scale Object Stacking Using Stack Stability

    DEFF Research Database (Denmark)

    Kronborg Thomsen, Kasper; Kraus, Martin

    2015-01-01

    This paper presents an extension system to a closed-source, real-time physics engine for improving structured stacking behavior with small-scale objects such as wooden toy bricks. The proposed system was implemented and evaluated. The tests showed that the system is able to simulate several common...

  12. Key Materials and Micro-Stack Systems of Single Chamber Solid Oxide Fuel Cells%单气室固体氧化物燃料电池关键材料与微堆系统

    Institute of Scientific and Technical Information of China (English)

    吕喆; 魏波; 田彦婷; 王志红; 苏文辉

    2011-01-01

    单气室固体氧化物燃料电池(SC-SOFC)是一种与传统的双气室结构燃料电池不同的新型燃料电池.SC-SOFC的阴极和阳极都暴露在单一气室中,在工作时通入含有燃料和氧化剂的混合气体,利用阳极和阴极的选择催化作用实现发电.SC-SOFC具有结构简单、无需密封、易于进行堆叠等很多独特的优点.本文介绍了SC-SOFC近期的研究进展,内容包括工作原理的介绍、SC-SOFC的关键材料选择与研究现状、影响SC-SOFC运行的主要因素的讨论,以及微堆(电池组)系统结构设计和试验等.着重介绍了本课题组在SC-SOFC的研究工作,包括对复合阴极材料、Ni修饰氧化物阳极的研究,以及星型和阵列式等多种新型SC-SOFC微堆结构设计与实验等.最后,基于对其优缺点的分析,展望了SC-SOFC各种潜在的应用.%Single chamber solid oxide fuel cell (SC-SOFC) is different from the conventional solid oxide fuel cell with dual gas chamber structure.Both cathode and anode of SC-SOFC are exposed to the only one gas chamber.Mixed gas containing fuel and oxidant is fed during operation and it can generate electric energy by the selectively catalytic activities of cathode and anode.SC-SOFC has many particular advatages, such as more simple structure, eliminating the need for sealing and easy stacking etc.In this paper, the recent research advances of SC-SOFC are reviewed, including brief introduction of operational principle of SC-SOFC, the selection of key materials for SC-SOFC, the discussion of main influencing factors on SC-SOFC, as well as the design and test of micro-stack (battery) system.The investigation results on SC-SOFC of our research group are highlighted, including composite cathode, oxide anode with Ni modification, and some novel designs for SC-SOFC micro stacks, such as star-type and array-type stacks, and so on.Finally, an outlook about the potential applications of SC-SOFC is given according to the analysis of

  13. The measurement of power reactor stack releases under accident conditions

    International Nuclear Information System (INIS)

    The performance of a typical Swedish monitor for ventilation stack radioactivity releases is examined critically with respect to accident generated radioactive particles. The conditions in the stack, particle character, and the monitor design are considered. A large LOCA outside the containment leads to high relative humidity, and high temperature, or mist in the stack. A small external LOCA results in a moderate increase in temperature and humidity, and condensing conditions only with reduced ventilation. Particle size and stickiness are estimated for different types of accident. A particle is sticky if it adheres after contact with a solid, smooth, dry, and clean surface. The monitor performance is concluded to be poor for large, sticky particles, like mist droplets. Dense aerosols, like fire smoke, will plug the sampling filter. Non-sticky particles are generally sampled with acceptable accuracy. (au)

  14. Materials, Proton Conductivity and Electrocatalysis in High-Temperature PEM Fuel Cells

    Science.gov (United States)

    Daletou, Maria K.; Kallitsis, Joannis; Neophytides, Stylianos G.

    Fuel cells (FCs) are interesting alternatives to existing power conversion systems since they combine high efficiency with the usage of renewable fuels. Fuel cells can generate power from a fraction of a watt to hundreds of kilowatts and can be used in automotive, stationary or portable applications.1,2,3,4,5,6 A FC is an electrochemical device that converts in a continuous manner the free energy of a chemical reaction into electrical energy (via an electrical current). This galvanic cell consists of an electrolyte (liquid or solid) sandwiched between two porous electrodes. In order to reach desirable amounts of energy power, single cell assemblies can be mechanically compressed across electrically conductive separators to fabricate stacks.

  15. Pressurized electrolysis stack with thermal expansion capability

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, Richard Scott

    2015-07-14

    The present techniques provide systems and methods for mounting an electrolyzer stack in an outer shell so as to allow for differential thermal expansion of the electrolyzer stack and shell. Generally, an electrolyzer stack may be formed from a material with a high coefficient of thermal expansion, while the shell may be formed from a material having a lower coefficient of thermal expansion. The differences between the coefficients of thermal expansion may lead to damage to the electrolyzer stack as the shell may restrain the thermal expansion of the electrolyzer stack. To allow for the differences in thermal expansion, the electrolyzer stack may be mounted within the shell leaving a space between the electrolyzer stack and shell. The space between the electrolyzer stack and the shell may be filled with a non-conductive fluid to further equalize pressure inside and outside of the electrolyzer stack.

  16. Temperature Characteristics Analysis of Triple-Junction Solar Cell under Concentrated Conditions using Spice Diode Model

    Science.gov (United States)

    Sakurada, Yuya; Ota, Yasuyuki; Nishioka, Kensuke

    2011-12-01

    Using spice diode model, the temperature characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under concentrated light conditions were analyzed in detail. The current-voltage (I-V) characteristics of the single-junction solar cells (InGaP, InGaAs, and Ge solar cells) were measured at various temperatures. From dark I-V characteristics of each single-junction solar cell, the diode parameters and temperature exponents were extracted. The extracted diode parameters and temperature exponents were applied to the equivalent circuit model for the triple-junction solar cell, and the solar cell performance was calculated with considering the temperature characteristics of series resistance. There was good agreement between the measured and calculated I-V characteristics of the triple-junction solar cell at various temperatures under concentrated light conditions.

  17. Solar cell contact pull strength as a function of pull-test temperature

    Science.gov (United States)

    Yasui, R. K.; Berman, P. A.

    1972-01-01

    Four types of solar cell contacts were given pull-strength tests at temperatures between -173 and +165 C. Contacts tested were: (1) solder-coated titanium-silver contacts on n-p cells, (2) palladium-containing titanium-silver contacts on n-p cells, (3) titanium-silver contacts on 0.2-mm-thick n-p cells, and (4) solder-coated electroless-nickel-plated contacts on p-n cells. Maximum pull strength was demonstrated at temperatures significantly below the air mass zero cell equilibrium temperature of +60 C. At the lowest temperatures, the chief failure mechanism was silicon fracture along crystallographic planes; at the highest temperatures, it was loss of solder strength. In the intermediate temperatures, many failure mechanisms operated. Pull-strength tests give a good indication of the suitability of solar cell contact systems for space use. Procedures used to maximize the validity of the results are described.

  18. File list: ALL.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.50.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...811237 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  19. File list: ALL.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.10.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...811238 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  20. File list: ALL.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.05.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...699108 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.05.AllAg.Temperature_sensitive_cells.bed ...