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Sample records for cell stack test

  1. 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...... performed based on test procedures proposed by a European project, Stack-Test. The sensitivity of a Nafion-based low temperature PEMFC stack’s performance to parametric changes was the main objective of the tests. Four crucial parameters for fuel cell operation were chosen; relative humidity, temperature...

  2. Testing of Electrodes, Cells and Short Stacks

    DEFF Research Database (Denmark)

    Hauch, Anne; Mogensen, Mogens Bjerg

    2017-01-01

    electrochemical measurements, and this will be the focus of this chapter. First, the important issue of understanding potential differences and measurements of potentials, which is linked to the choice of proper electrode geometries and test set up configurations for electrode and cell testing, is presented...

  3. 400 W High Temperature PEM Fuel Cell Stack Test

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2006-01-01

    This work demonstrates the operation of a 30 cell high temperature PEM (HTPEM) fuel cell stack. This prototype stack has been developed at the Institute of Energy Technology, Aalborg University, as a proof-of-concept for a low pressure cathode air cooled HTPEM stack. The membranes used are Celtec P...... of the species as in a LTPEM fuel cell system. The use of the HTPEM fuel cell makes it possible to use reformed gas at high CO concentrations, still with a stable efficient performance....

  4. Fuel Cell Stack Testing and Durability in Support of Ion Tiger UAV

    Science.gov (United States)

    2010-06-02

    This report covers efforts by the Hawaii Natural Energy Institute (HNEI) of the University of Hawaii under the ONR-funded Ion Tiger UAV award that included testing of Ion Tiger fuel cell stacks in HNEI’s Hawaii Fuel Cell Test Facility located in Honolulu, Hawaii. Work was focused on steady-state stack characteristics of Protonex fuel cell stacks under various operating conditions. In addition, Hardware-in-the-Loop testing was performed to characterize dynamic

  5. Test of Hydrogen-Oxygen PEM Fuel Cell Stack at NASA Glenn Research Center

    Science.gov (United States)

    Bents, David J.; Scullin, Vincent J.; Chang, Bei-Jiann; Johnson, Donald W.; Garcia, Christopher P.; Jakupca, Ian J.

    2003-01-01

    This paper describes performance characterization tests of a 64 cell hydrogen oxygen PEM fuel cell stack at NASA Glenn Research Center in February 2003. The tests were part of NASA's ongoing effort to develop a regenerative fuel cell for aerospace energy storage applications. The purpose of the tests was to verify capability of this stack to operate within a regenerative fuel cell, and to compare performance with earlier test results recorded by the stack developer. Test results obtained include polarization performance of the stack at 50 and 100 psig system pressure, and a steady state endurance run at 100 psig. A maximum power output of 4.8 kWe was observed during polarization runs, and the stack sustained a steady power output of 4.0 kWe during the endurance run. The performance data obtained from these tests compare reasonably close to the stack developer's results although some additional spread between best to worst performing cell voltages was observed. Throughout the tests, the stack demonstrated the consistent performance and repeatable behavior required for regenerative fuel cell operation.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    far. Besides a summary of existing test procedures a so called “test matrix” was created. This document includes generic test modules, e.g. current-voltage curves, electrochemical impedance spectroscopy, thermal cycling, electrical current cycling and long-term tests both under steady -state......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 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...

  7. Electrochemical cell stack assembly

    Science.gov (United States)

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2010-06-22

    Multiple stacks of tubular electrochemical cells having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films arranged in parallel on stamped conductive interconnect sheets or ferrules. The stack allows one or more electrochemical cell to malfunction without disabling the entire stack. Stack efficiency is enhanced through simplified gas manifolding, gas recycling, reduced operating temperature and improved heat distribution.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    The market penetration of fuel and electrolysis cell energy systems in Europe requires the development of reliable assessment, testing and prediction of performance and durability of solid oxide cells and stacks (SOC). To advance in this field the EU-project “SOCTESQA” was launched in May 2014. P...... will be confirmed by round robin tests....

  9. 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...

  10. 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 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...... 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...

  11. Fuel Cell Stacks

    Science.gov (United States)

    1975-04-01

    AD-A009 587 FUEL CELL STACKS Bernard S. Baker Energy Research Corporation Prepared for: Army Mobility Equipment Research and Development Center April... Mobility Equipment Research and Development Center Unclassified For- Belvoir, Virginia 22060 [15. DE.CLASSIFICATION/L.TWNOGRADING SCREOUJLE 16...the majority of effort has been directed at translating technoilogy for small comn- ponent manufacture on a laboratory scale into large size components

  12. The development of a fuel cell stack electronic simulator for enhanced safety and reliability during test and training

    Energy Technology Data Exchange (ETDEWEB)

    Abdulhadi, M.; Al-Garni, M. [King AbdulAziz City for Science and Technology (KACST), Riyadh (Saudi Arabia). Energy Research Inst.

    1996-12-31

    One of the main sub-tasks of HYSOLAR, a joint Saudi-German research and development program in the field of solar hydrogen, is the investigation and characterization of phosphoric acid fuel cells (PAFC). To facilitate this, a fully automated data acquisition and control (DAC) system for fuel cell stacks was developed at KACST`s Solar Village. In order to ensure that the test and training procedures were as safe and reliable as possible, an electronic simulator for the fuel cell stacks was also developed. This paper discusses the background and concept and describes the development and operational characteristics of the simulator. (Author)

  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

    /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...

  14. Long-term testing of a high-temperature proton exchange membrane fuel cell short stack operated with improved polybenzimidazole-based composite membranes

    Science.gov (United States)

    Pinar, F. Javier; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Lobato, Justo

    2015-01-01

    In this work, the feasibility of a 150 cm2 high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack operated with modified proton exchange membranes is demonstrated. The short fuel cell stack was manufactured using a total of three 50 cm2 membrane electrode assemblies (MEAs). The PEM technology is based on a polybenzimidazole (PBI) membrane. The obtained results were compared with those obtained using a HT-PEMFC stack with unmodified membranes. The membranes were cast from a PBI polymer synthesized in the laboratory, and the modified membranes contained 2 wt.% micro-sized TiO2 as a filler. Long-term tests were performed in both constant and dynamic loading modes. The fuel cell stack with 2 wt.% TiO2 composite PBI membranes exhibited an irreversible voltage loss of less than 2% after 1100 h of operation. In addition, the acid loss was reduced from 2% for the fuel cell stack with unmodified membranes to 0.6% for the fuel cell stack with modified membranes. The results demonstrate that introducing filler into the membranes enhances the durability and stability of this type of fuel cell technology. Moreover, the fuel cell stack system also exhibits very rapid and stable power and voltage output responses under dynamic load regimes.

  15. A look at the current status of the fuel cell technology: Test buying and operation of fuel cell stacks; Wo steht die Brennstoffzellentechnik? Erfahrungen beim Testkauf und -betrieb von BZ-Stacks

    Energy Technology Data Exchange (ETDEWEB)

    Scheppat, Birgit [Hochschule RheinMain, Wiesbaden (Germany)

    2010-10-15

    In a recent projects, scientists of RheinMain university analyzed the challenges facing potential customers who intend to replace a battery or another electric power supply unit by fuel cell stack. (orig.)

  16. Solid Oxide Fuel Cell Stack Diagnostics

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Barfod, Rasmus Gottrup

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

  17. Development of internal reforming carbonate fuel cell stack technology

    Energy Technology Data Exchange (ETDEWEB)

    Farooque, M.

    1990-10-01

    Activities under this contract focused on the development of a coal-fueled carbonate fuel cell system design and the stack technology consistent with the system design. The overall contract effort was divided into three phases. The first phase, completed in January 1988, provided carbonate fuel cell component scale-up from the 1ft{sup 2} size to the commercial 4ft{sup 2} size. The second phase of the program provided the coal-fueled carbonate fuel cell system (CGCFC) conceptual design and carried out initial research and development needs of the CGCFC system. The final phase of the program emphasized stack height scale-up and improvement of stack life. The results of the second and third phases are included in this report. Program activities under Phase 2 and 3 were designed to address several key development areas to prepare the carbonate fuel cell system, particularly the coal-fueled CFC power plant, for commercialization in late 1990's. The issues addressed include: Coal-Gas Related Considerations; Cell and Stack Technology Improvement; Carbonate Fuel Cell Stack Design Development; Stack Tests for Design Verification; Full-Size Stack Design; Test Facility Development; Carbonate Fuel Cell Stack Cost Assessment; and Coal-Fueled Carbonate Fuel Cell System Design. All the major program objectives in each of the topical areas were successfully achieved. This report is organized along the above-mentioned topical areas. Each topical area has been processed separately for inclusion on the data base.

  18. 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.

  19. Routes to a commercially viable PEM fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Newton, J.; Foster, S.E.; Hodgson, D.; Marrett, A.

    2002-07-01

    This report describes the results of a project to design and build a 10 kW{sub e} proton exchange membrane fuel cell (PEMFC) stack, including membrane electrode assemblies (MEAs), bipolar plates and stack hardware. The aim was to prove the design concept and to demonstrate functionality by operating the stack at >1 kW{sub e}/L and 500 W/kg for 200 hours operation. The project was extended to include the assembly and testing of two additional 1 kW{sub e} PEMFC stacks based on coated metal components. Low equivalent weight perfluorinated ionomer ion exchange membranes were prepared and were found to give a superior electrochemical performance to commercial materials. A technique to etch various stainless steel grades and control processes was successfully developed and optimised. Coatings for stainless steel and titanium were successfully developed and met the required performance criteria. All PEMFC stack components were selected and designed to enable subsequent commercial manufacture.

  20. 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

  1. Cosmic ray test of INO RPC stack

    Energy Technology Data Exchange (ETDEWEB)

    Bhuyan, M. [Department of High Energy Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Datar, V.M. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kalmani, S.D.; Lahamge, S.M.; Mondal, N.K.; Nagaraj, P.; Pal, S.; Reddy, L.V.; Redij, A.; Samuel, D.; Saraf, M.N. [Department of High Energy Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Satyanarayana, B., E-mail: bsn@tifr.res.in [Department of High Energy Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Shinde, R.R.; Verma, P. [Department of High Energy Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India)

    2012-01-01

    The India-based Neutrino Observatory (INO) collaboration is planning to build a 50 kt magnetised iron calorimeter (ICAL) detector using glass Resistive Plate Chambers (RPCs) as active detector elements. A stack of 12 such glass RPCs of 1 m Multiplication-Sign 1 m in area is tracking cosmic ray muons for over three years. In this paper, we will review the constructional aspects of the stack and discuss the performance of the RPCs using this cosmic ray data.

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

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    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, runs on pure hydrogen in a dead end anode configuration with a purge valve. The cooling of the stack is managed by running...

  3. Revisiting the Fundamentals and Capabilities of the Stack Compression Test

    DEFF Research Database (Denmark)

    Alves, L.M.; Nielsen, Chris Valentin; Martin, P.A.F.

    2011-01-01

    of understanding for the stack compression test and to evaluate its capability for constructing the flow curves of metal sheets under high strains across the useful range of material testing conditions. The presentation draws from the fundamentals of the stack compression test to the assessment of its overall...... performance by comparing the flow curves obtained from its utilisation with those determined by means of compressive testing carried out on solid cylinder specimens of the same material. Results show that mechanical testing of materials by means of the stack compression test is capable of meeting...

  4. Mechanically stacked concentrator tandem solar cells

    Science.gov (United States)

    Andreev, V. M.; Rumyantsev, V. D.; Karlina, L. B.; Kazantsev, A. B.; Khvostikov, V. P.; Shvarts, M. Z.; Sorokina, S. V.

    1995-01-01

    Four-terminal mechanically stacked solar cells were developed for advanced space arrays with line-focus reflective concentrators. The top cells are based on AlGaAs/GaAs multilayer heterostructures prepared by low temperature liquid phase epitaxy. The bottom cells are based on heteroepitaxial InP/InGaAs liquid phase epitaxy or on homo-junction GaSb, Zn-diffused structures. The sum of the highest reached efficiencies of the top and bottom cells is 29.4 percent. The best four-terminal tandems have an efficiency of 27 to 28 percent. Solar cells were irradiated with 1 MeV electrons and their performances were determined as a function of fluence up to 10(exp 16) cm(exp-2). It was shown that the radiation resistance of developed tandem cells is similar to the most radiative stable AlGaAs/GaAs cells with a thin p-GaAs photoactive layer.

  5. 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...... heating strategies and find a strategy suited for fast startup of the HTPEM fuel cell stacks. Fast start-up of these high temperature systems enables use in a wide range of applications, such as automotive and auxiliary power units, where immediate system response is needed. The development of a dynamic...... model to simulate the temperature development of a fuel cell stack during heating can be used for assistance in system and control design. The heating strategies analyzed and tested reduced the startup time of one of the fuel cell stacks from 1 h to about 6 min....

  6. The first self-sustainable microbial fuel cell stack.

    Science.gov (United States)

    Ledezma, Pablo; Stinchcombe, Andrew; Greenman, John; Ieropoulos, Ioannis

    2013-02-21

    This study reports for the first time on the development of a self-sustainable microbial fuel cell stack capable of self-maintenance (feeding, hydration, sensing & reporting). Furthermore, the stack system is producing excess energy, which can be used for improved functionality. The self-maintenance is performed by the stack powering single and multi-channel peristaltic pumps.

  7. Co-flow planar SOFC fuel cell stack

    Science.gov (United States)

    Chung, Brandon W.; Pham, Ai Quoc; Glass, Robert S.

    2004-11-30

    A co-flow planar solid oxide fuel cell stack with an integral, internal manifold and a casing/holder to separately seal the cell. This construction improves sealing and gas flow, and provides for easy manifolding of cell stacks. In addition, the stack construction has the potential for an improved durability and operation with an additional increase in cell efficiency. The co-flow arrangement can be effectively utilized in other electrochemical systems requiring gas-proof separation of gases.

  8. 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)

  9. 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...

  10. 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)

  11. 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.

  12. RECENT ADVANCES IN HIGH TEMPERATURE ELECTROLYSIS AT IDAHO NATIONAL LABORATORY: STACK TESTS

    Energy Technology Data Exchange (ETDEWEB)

    X, Zhang; J. E. O' Brien; R. C. O' Brien; J. J. Hartvigsen; G. Tao; N. Petigny

    2012-07-01

    High temperature steam electrolysis is a promising technology for efficient sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-term durability of SOECs. Electrolytesupported and electrode-supported SOEC stacks were provided by Ceramatec Inc., Materials and Systems Research Inc. (MSRI), and Saint Gobain Advanced Materials (St. Gobain), respectively for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technology developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, respectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. A three-cell short stack provided by St. Gobain, however, showed rapid degradation in the electrolysis mode. Improvements on electrode materials, interconnect coatings, and electrolyteelectrode interface microstructures contribute to better durability of SOEC stacks.

  13. Full scale phosphoric acid fuel cell stack technology development

    Science.gov (United States)

    Christner, L.; Faroque, M.

    1984-01-01

    The technology development for phosphoric acid fuel cells is summarized. The preparation, heat treatment, and characterization of carbon composites used as bipolar separator plates are described. Characterization included resistivity, porosity, and electrochemical corrosion. High density glassy carbon/graphite composites performed well in long-term fuel cell endurance tests. Platinum alloy cathode catalysts and low-loaded platinum electrodes were evaluated in 25 sq cm cells. Although the alloys displayed an initial improvement, some of this improvement diminished after a few thousand hours of testing. Low platinum loading (0.12 mg/sq cm anodes and 0.3 mg/sq cm cathodes) performed nearly as well as twice this loading. A selectively wetproofed anode backing paper was tested in a 5 by 15 inch three-cell stack. This material may provide for acid volume expansion, acid storage, and acid lateral distribution.

  14. Advances in the development of a hydrogen/oxygen PEM fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Tori, C.; Garaventta, G.; Visintin, A.; Triaca, W.E. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 16, Suc. 4 (1900) La Plata (Argentina); Baleztena, M.; Peralta, C.; Calzada, R.; Jorge, E. [Grupo de Investigacion en Energias Sustentables y Eficiencia Energetica (GIESEE), Departamento de Electrotecnia, Universidad Tecnologica Nacional, Facultad Regional La Plata, Av. 60 esq. 124 (1900) La Plata (Argentina); Barsellini, D. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 16, Suc. 4 (1900) La Plata (Argentina); Grupo de Investigacion en Energias Sustentables y Eficiencia Energetica (GIESEE), Departamento de Electrotecnia, Universidad Tecnologica Nacional, Facultad Regional La Plata, Av. 60 esq. 124 (1900) La Plata (Argentina)

    2008-07-15

    Recent advances in the design and construction of a hydrogen/oxygen PEM fuel cell stack are presented. A test bench including measurement and control devices to monitor the fuel cell operating parameters was mounted. The influence of the characteristics of the membrane electrode assembly, bipolar plates, etc., on the performance of the fuel cell stack was studied. The behavior of the fuel cell stack with a different number of cells in series was evaluated. In order to identify and minimize the energy losses a critical analysis of the results was done. (author)

  15. A Unit Cell Laboratory Experiment: Marbles, Magnets, and Stacking Arrangements

    Science.gov (United States)

    Collins, David C.

    2011-01-01

    An undergraduate first-semester general chemistry laboratory experiment introducing face-centered, body-centered, and simple cubic unit cells is presented. Emphasis is placed on the stacking arrangement of solid spheres used to produce a particular unit cell. Marbles and spherical magnets are employed to prepare each stacking arrangement. Packing…

  16. 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.......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 unexpected...

  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. Optimization Algorithms Testing and Convergence by Using a Stacked Histogram

    Directory of Open Access Journals (Sweden)

    ZAPLATILEK, K.

    2011-02-01

    Full Text Available The article describes an original method of optimization algorithms testing and convergence. The method is based on so-called stacked histogram. Stacked histogram is a histogram with its features marked by a chosen colour scheme. Thus, the histogram maintains the information on the input digital sequence. This approach enables an easy identification of the hidden defects in the random process statistical distribution. The stacked histogram is used for the testing of the convergent quality of various optimization techniques. Its width, position and colour scheme provides enough information on the chosen algorithm optimization trajectory. Both the classic iteration techniques and the stochastic optimization algorithm with the adaptation were used as examples.

  19. Mathematical modeling and simulation of thermal management in polymer electrolyte membrane fuel cell stacks

    Science.gov (United States)

    Amirfazli, Amir; Asghari, Saeed; Koosha, Morteza

    2014-12-01

    The narrow range of operating temperature and small temperature differences between the stack and the ambient have made the fuel cell thermal management as one of the key factors that influence the performance and durability of polymer electrolyte membrane fuel cell (PEMFC) stacks. In the present study, an analytical model is developed to investigate coolant flow and temperature distributions within a PEMFC stack. The model consists of a coolant flow distribution submodel and a thermal submodel for determination of coolant mass flow distribution between different cooling flow fields of the stack and the temperature distribution within the stack, respectively. The coolant mass flow rate and the temperature distributions in stacks with U and Z configurations are compared with each other using the developed model. The test results of two 65-cells stacks are presented to verify the simulation. The results indicate that the Z configuration results in more uniform temperature distribution than the U configuration in low values of the manifold cross sectional area. However, the Z configuration cannot be applied in the stacks with very small manifold sizes. A parametric analysis is also conducted to assess the effects of some parameters on the temperature distribution in a stack.

  20. 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

  1. 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.

  2. Polymer electrolyte fuel cell stack research and development

    Energy Technology Data Exchange (ETDEWEB)

    Squadrito, G.; Barbera, O.; Giacoppo, G.; Urbani, F.; Passalacqua, E. [Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' del CNR (CNR, ITAE), via Salita per, Santa Lucia sopra Contesse 5, Messina (Italy)

    2008-04-15

    The research activity in polymer electrolyte fuel cell (PEFC) is oriented to the evolution of components and devices for the temperature range from 20 to 130{sup o}C, and covers all the aspects of this matter: membranes and electrodes, fuel cell stack engineering (design and manufacturing) and characterization, computational modelling and small demonstration systems prototyping. Particular attention is devoted to portable and automotive application. Membranes research is focused on thermostable polymers (polyetheretherketone, polysulphone, etc.) and composite membranes able to operate at higher temperature (>100{sup o}C) and lower humidification than the commercial Nafion {sup registered}, while Pt load reduction and gas diffusion layer improvement are the main goals for the electrode development. PEFC stack engineering and characterization activity involve different aspects such as the investigation of new materials for stack components, fuel cell modelling and performance optimization by computational techniques, single cell and stack electrochemical characterization, development of investigation tools for stack monitoring and data acquisition. A lot of work has been focused to the fuel cell stack architecture, assembling, gas leakage and cross-over reduction (gasketing), flow field and manifold design. Computational fluid dynamics studies have been performed to investigate and improve reactants distribution inside the cell. A flow field design methodology, developed in this framework and related to serpentine like flow field, is actually under investigation. All of these aspects of PEFC stack research are realized in the framework of National and European research projects, or in collaboration with industries and other research centres. In the present work our stack research activity is reported and the most important results are also considered. (author)

  3. 40 CFR 62.15250 - May I conduct stack testing less often?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false May I conduct stack testing less often..., 1999 Stack Testing § 62.15250 May I conduct stack testing less often? (a) You may test less often if..., opacity, hydrogen chloride, and fugitive ash. (b) You can test less often for dioxins/furans emissions...

  4. 40 CFR 60.1795 - May I conduct stack testing less often?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false May I conduct stack testing less often...-Stack Testing § 60.1795 May I conduct stack testing less often? (a) You may test less often if you own..., hydrogen chloride, and fugitive ash. (b) You can test less often for dioxins/furans emissions if you own...

  5. Study of organic solar cells with stacked bulk heterojunction structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-fang; XU Zheng; ZHAO Su-ling; ZHANG Fu-jun; LI Yan; WU Chun-yu; CHEN Yue-ning

    2008-01-01

    Organic solar cells with stacked bulk heterojunction(BHJ) are investigated based on conjugated polymer. By using the solution spin-coating method, Poly[2-methoxy, 5-(2'-ethyl-hexyloxy) -1,4-phenylene vinylene] (MEH-PPV) and ZnO nanoparticles (50 nm) are mixed as the optical sense layer. Ag is used as inter-layer to connect the upper BILl cell and the lower cell. The structures are ITO/PEDOT:PSS/MEH-PPV/Ag/MEH-PPV:ZnO/Al. The open circuit voltage (Voc) of a stacked cell is about 3.7 times of that of an individual organic solar cell (ITO/PEDOT:PSS/MEH-PPV/A1). The short circuit current (Jsc) of a stacked cell is increased by about 1.6 times of that of individual one.

  6. Mechanisms of accelerated degradation in the front cells of PEMFC stacks and some mitigation strategies

    Science.gov (United States)

    Li, Pengcheng; Pei, Pucheng; He, Yongling; Yuan, Xing; Chao, Pengxiang; Wang, Xizhong

    2013-11-01

    The accelerated degradation in the front cells of a polymer electrolyte membrane fuel cell(PEMFC) stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and configuration of the gas intake manifold, which may lead to the maldistribution of flow and pressure. In order to find out the mechanisms of the accelerated degradation in the front cells, an extensive program of experimental and simulation work is initiated and the results are reported. It is found that after long-term lifetime tests the accelerated degradation in the front cells occurs in all three fuel cell stacks with different flow-fields under the U-type feed configuration. Compared with the rear cells of the stack, the voltage of the front cells is much lower at the same current densities and the membrane electrode assembly(MEA) has smaller active area, more catalyst particle agglomeration and higher ohmic impedance. For further investigation, a series of three dimensional isothermal numerical models are built to investigate the degradation mechanisms based on the experimental data. The simulation results reveal that the dry working condition of the membrane and the effect of high-speed gas scouring the MEA are the main causes of the accelerated degradation in the front cells of a PEM fuel cell stack under the U-type feed configuration. Several mitigation strategies that would mitigate these phenomena are presented: removing cells that have failed and replacing them with those of the same aging condition as the average of the stack; choosing a Z-type feed pattern instead of a U-type one; putting several air flow-field plates without MEA in the front of the stack; or exchanging the gas inlet and outlet alternately at a certain interval. This paper specifies the causes of the accelerated degradation in the front cells and provides the mitigation strategies.

  7. Novel fuel cell stack with coupled metal hydride containers

    Science.gov (United States)

    Liu, Zhixiang; Li, Yan; Bu, Qingyuan; Guzy, Christopher J.; Li, Qi; Chen, Weirong; Wang, Cheng

    2016-10-01

    Air-cooled, self-humidifying hydrogen fuel cells are often used for backup and portable power sources, with a metal hydride used as the hydrogen storage material. To provide a stable hydrogen flow to the fuel cell stack, heat must be provided to the metal hydride. Conventionally, the heat released from the exothermic reaction of hydrogen and oxygen in the fuel cell stack to the exhaust air is used to heat a separate metal hydride container. In this case, the heat is only partially used instead of being more closely coupled because of the heat transfer resistances in the system. To achieve better heat integration, a novel scheme is proposed whereby hydrogen storage and single fuel cells are more closely coupled. Based on this idea, metal hydride containers in the form of cooling plates were assembled between each pair of cells in the stack so that the heat could be directly transferred to a metal hydride container of much larger surface-to-volume ratio than conventional separate containers. A heat coupled fuel cell portable power source with 10 cells and 11 metal hydride containers was constructed and the experimental results show that this scheme is beneficial for the heat management of fuel cell stack.

  8. Transparent contacts for stacked compound photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Tauke-Pedretti, Anna; Cederberg, Jeffrey; Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose Luis

    2016-11-29

    A microsystems-enabled multi-junction photovoltaic (MEM-PV) cell includes a first photovoltaic cell having a first junction, the first photovoltaic cell including a first semiconductor material employed to form the first junction, the first semiconductor material having a first bandgap. The MEM-PV cell also includes a second photovoltaic cell comprising a second junction. The second photovoltaic cell comprises a second semiconductor material employed to form the second junction, the second semiconductor material having a second bandgap that is less than the first bandgap, the second photovoltaic cell further comprising a first contact layer disposed between the first junction of the first photovoltaic cell and the second junction of the second photovoltaic cell, the first contact layer composed of a third semiconductor material having a third bandgap, the third bandgap being greater than or equal to the first bandgap.

  9. 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.

  10. 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...

  11. Performance model of a recirculating stack nickel hydrogen cell

    Science.gov (United States)

    Zimmerman, Albert H.

    1994-01-01

    A theoretical model of the nickel hydrogen battery cell has been utilized to describe the chemical and physical changes during charge and overcharge in a recirculating stack nickel hydrogen cell. In particular, the movement of gas and electrolyte have been examined as a function of the amount of electrolyte put into the cell stack during cell activation, and as a function of flooding in regions of the gas screen in this cell design. Additionally, a two-dimensional variation on this model has been utilized to describe the effects of non-uniform loading in the nickel-electrode on the movement of gas and electrolyte within the recirculating stack nickel hydrogen cell. The type of nonuniform loading that has been examined here is that associated with higher than average loading near the surface of the sintered nickel electrode, a condition present to some degree in many nickel electrodes made by electrochemical impregnation methods. The effects of high surface loading were examined primarily under conditions of overcharge, since the movement of gas and electrolyte in the overcharging condition was typically where the greatest effects of non-uniform loading were found. The results indicate that significant changes in the capillary forces between cell components occur as the percentage of free volume in the stack filled by electrolyte becomes very high. These changes create large gradients in gas-filled space and oxygen concentrations near the boundary between the separator and the hydrogen electrode when the electrolyte fill is much greater than about 95 percent of the stack free volume. At lower electrolyte fill levels, these gaseous and electrolyte gradients become less extreme, and shift through the separator towards the nickel electrode. Similarly, flooding of areas in the gas screen cause higher concentrations of oxygen gas to approach the platinum/hydrogen electrode that is opposite the back side of the nickel electrode. These results illustrate the need for

  12. 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.

  13. 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.

  14. 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...

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

    Science.gov (United States)

    England, Diane Mildred

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

  16. Electricity generation and microbial community in response to short-term changes in stack connection of self-stacked submersible microbial fuel cell powered by glycerol

    DEFF Research Database (Denmark)

    Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

    2017-01-01

    Stack connection (i.e., in series or parallel) of microbial fuel cell (MFC) is an efficient way to boost the power output for practical application. However, there is little information available on short-term changes in stack connection and its effect on the electricity generation and microbial...... community. In this study, a self-stacked submersible microbial fuel cell (SSMFC) powered by glycerol was tested to elucidate this important issue. In series connection, the maximum voltage output reached to 1.15 V, while maximum current density was 5.73 mA in parallel. In both connections, the maximum power...... density increased with the initial glycerol concentration. However, the glycerol degradation was even faster in parallel connection. When the SSMFC was shifted from series to parallel connection, the reactor reached to a stable power output without any lag phase. Meanwhile, the anodic microbial community...

  17. Test impact on the overall die-to-wafer 3D stacked IC cost

    NARCIS (Netherlands)

    Taouil, M.; Hamdioui, S.; Beenakker, K.; Marinissen, E.J.

    2011-01-01

    One of the key challenges in 3D Stacked-ICs (3D-SIC) is to guarantee high product quality at minimal cost. Quality is mostly determined by the applied tests and cost trade-offs. Testing 3D-SICs is very challenging due to several additional test moments for the mid-bond stacks, i.e., partially create

  18. Experimental study and comparison of various designs of gas flow fields to PEM fuel cells and cell stack performance

    Directory of Open Access Journals (Sweden)

    Hong eLiu

    2014-01-01

    Full Text Available In this study, a significant number of experimental tests to 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 all have an effective membrane area of 23.5 cm2. The results showed that the serpentine flow channel design is still favorable, giving the best single fuel cell performance amongst all the studied flow channel designs. A novel symmetric serpentine flow field was proposed for relatively large size fuel cell application. Four fuel cell stacks each including four cells were assembled using different designs of serpentine flow channels. The output power performances of fuel cell stacks were compared and the novel symmetric serpentine flow field design is recommended for its very good performance.

  19. 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)

  20. Two stage bioethanol refining with multi litre stacked microbial fuel cell and microbial electrolysis cell.

    Science.gov (United States)

    Sugnaux, Marc; Happe, Manuel; Cachelin, Christian Pierre; Gloriod, Olivier; Huguenin, Gérald; Blatter, Maxime; Fischer, Fabian

    2016-12-01

    Ethanol, electricity, hydrogen and methane were produced in a two stage bioethanol refinery setup based on a 10L microbial fuel cell (MFC) and a 33L microbial electrolysis cell (MEC). The MFC was a triple stack for ethanol and electricity co-generation. The stack configuration produced more ethanol with faster glucose consumption the higher the stack potential. Under electrolytic conditions ethanol productivity outperformed standard conditions and reached 96.3% of the theoretically best case. At lower external loads currents and working potentials oscillated in a self-synchronized manner over all three MFC units in the stack. In the second refining stage, fermentation waste was converted into methane, using the scale up MEC stack. The bioelectric methanisation reached 91% efficiency at room temperature with an applied voltage of 1.5V using nickel cathodes. The two stage bioethanol refining process employing bioelectrochemical reactors produces more energy vectors than is possible with today's ethanol distilleries.

  1. Evaluation of single and stack membraneless enzymatic fuel cells based on ethanol in simulated body fluids.

    Science.gov (United States)

    Galindo-de-la-Rosa, J; Arjona, N; Moreno-Zuria, A; Ortiz-Ortega, E; Guerra-Balcázar, M; Ledesma-García, J; Arriaga, L G

    2017-02-08

    The purpose of this work is to evaluate single and double-cell membraneless microfluidic fuel cells (MMFCs) that operate in the presence of simulated body fluids SBF, human serum and blood enriched with ethanol as fuels. The study was performed using the alcohol dehydrogenase enzyme immobilised by covalent binding through an array composed of carbon Toray paper as support and a layer of poly(methylene blue)/tetrabutylammonium bromide/Nafion and glutaraldehyde (3D bioanode electrode). The single MMFC was tested in a hybrid microfluidic fuel cell using Pt/C as the cathode. A cell voltage of 1.035V and power density of 3.154mWcm(-2) were observed, which is the highest performance reported to date. The stability and durability were tested through chronoamperometry and polarisation/performance curves obtained at different days, which demonstrated a slow decrease in the power density on day 10 (14%) and day 20 (26%). Additionally, the cell was tested for ethanol oxidation in simulated body fluid (SBF) with ionic composition similar to human blood plasma. Those tests resulted in 0.93V of cell voltage and a power density close to 1.237mWcm(-2). The double cell MMFC (Stack) was tested using serum and human blood enriched with ethanol. The stack operated with blood in a serial connection showed an excellent cell performance (0.716mWcm(-2)), demonstrating the feasibility of employing human blood as energy source.

  2. Electricity generation and microbial community in response to short-term changes in stack connection of self-stacked submersible microbial fuel cell powered by glycerol.

    Science.gov (United States)

    Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

    2017-02-01

    Stack connection (i.e., in series or parallel) of microbial fuel cell (MFC) is an efficient way to boost the power output for practical application. However, there is little information available on short-term changes in stack connection and its effect on the electricity generation and microbial community. In this study, a self-stacked submersible microbial fuel cell (SSMFC) powered by glycerol was tested to elucidate this important issue. In series connection, the maximum voltage output reached to 1.15 V, while maximum current density was 5.73 mA in parallel. In both connections, the maximum power density increased with the initial glycerol concentration. However, the glycerol degradation was even faster in parallel connection. When the SSMFC was shifted from series to parallel connection, the reactor reached to a stable power output without any lag phase. Meanwhile, the anodic microbial community compositions were nearly stable. Comparatively, after changing parallel to series connection, there was a lag period for the system to get stable again and the microbial community compositions became greatly different. This study is the first attempt to elucidate the influence of short-term changes in connection on the performance of MFC stack, and could provide insight to the practical utilization of MFC.

  3. 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.

  4. Stack air-breathing membraneless glucose microfluidic biofuel cell

    Science.gov (United States)

    Galindo-de-la-Rosa, J.; Moreno-Zuria, A.; Vallejo-Becerra, V.; Arjona, N.; Guerra-Balcázar, M.; Ledesma-García, J.; Arriaga, L. G.

    2016-11-01

    A novel stacked microfluidic fuel cell design comprising re-utilization of the anodic and cathodic solutions on the secondary cell is presented. This membraneless microfluidic fuel cell employs porous flow-through electrodes in a “V”-shape cell architecture. Enzymatic bioanodic arrays based on glucose oxidase were prepared by immobilizing the enzyme onto Toray carbon paper electrodes using tetrabutylammonium bromide, Nafion and glutaraldehyde. These electrodes were characterized through the scanning electrochemical microscope technique, evidencing a good electrochemical response due to the electronic transference observed with the presence of glucose over the entire of the electrode. Moreover, the evaluation of this microfluidic fuel cell with an air-breathing system in a double-cell mode showed a performance of 0.8951 mWcm-2 in a series connection (2.2822mAcm-2, 1.3607V), and 0.8427 mWcm-2 in a parallel connection (3.5786mAcm-2, 0.8164V).

  5. 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.

  6. Stack test results at Phelps-Dodge Corporation, Ajo, Arizona. Volume III. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, J.

    1977-03-01

    Contents: Sampling schedules for simultaneous stack tests; Weight versus time curve for glass fiber filter; Sample calculation for statistical analysis; Individual process weight calculations; Individual filter, particulate and residue weight data.

  7. 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.

  8. Manual of phosphoric acid fuel cell stack three-dimensional model and computer program

    Science.gov (United States)

    Lu, C. Y.; Alkasab, K. A.

    1984-01-01

    A detailed distributed mathematical model of phosphoric acid fuel cell stack have been developed, with the FORTRAN computer program, for analyzing the temperature distribution in the stack and the associated current density distribution on the cell plates. Energy, mass, and electrochemical analyses in the stack were combined to develop the model. Several reasonable assumptions were made to solve this mathematical model by means of the finite differences numerical method.

  9. Identifying same-cell contours in image stacks: a key step in making 3D reconstructions.

    Science.gov (United States)

    Leung, Tony Kin Shun; Veldhuis, Jim H; Krens, S F Gabby; Heisenberg, C P; Brodland, G Wayne

    2011-02-01

    Identification of contours belonging to the same cell is a crucial step in the analysis of confocal stacks and other image sets in which cell outlines are visible, and it is central to the making of 3D cell reconstructions. When the cells are close packed, the contour grouping problem is more complex than that found in medical imaging, for example, because there are multiple regions of interest, the regions are not separable from each other by an identifiable background and regions cannot be distinguished by intensity differences. Here, we present an algorithm that uses three primary metrics-overlap of contour areas in adjacent images, co-linearity of the centroids of these areas across three images in a stack, and cell taper-to assign cells to groups. Decreasing thresholds are used to successively assign contours whose membership is less obvious. In a final step, remaining contours are assigned to existing groups by setting all thresholds to zero and groups having strong hour-glass shapes are partitioned. When applied to synthetic data from isotropic model aggregates, a curved model epithelium in which the long axes of the cells lie at all possible angles to the transection plane, and a confocal image stack, algorithm assignments were between 97 and 100% accurate in sets having at least four contours per cell. The algorithm is not particularly sensitive to the thresholds used, and a single set of parameters was used for all of the tests. The algorithm, which could be extended to time-lapse data, solves a key problem in the translation of image data into cell information.

  10. 40 CFR 60.1305 - May I conduct stack testing less often?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false May I conduct stack testing less often... testing less often? (a) You may test less often if you own or operate a Class II municipal waste.... (b) You can test less often for dioxins/furans emissions if you own or operate a municipal...

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

    Science.gov (United States)

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

    2016-12-01

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

  12. Stacked microbial desalination cells to enhance water desalination efficiency.

    Science.gov (United States)

    Chen, Xi; Xia, Xue; Liang, Peng; Cao, Xiaoxin; Sun, Haotian; Huang, Xia

    2011-03-15

    Microbial desalination cell (MDC) is a new method to obtain clean water from brackish water using electricity generated from organic matters by exoelectrogenic bacteria. Anions and cations, derived from salt solution filled in the desalination chamber between the anode and cathode, move to the anode and cathode chambers under the force of electrical field, respectively. On the basis of the primitive single-desalination-chambered MDC, stacked microbial desalination cells (SMDCs) were developed in order to promote the desalination rate in the present study. The effects of desalination chamber number and external resistance were investigated. Results showed that a remarkable increase in the total desalination rate (TDR) could be obtained by means of increasing the desalination cell number and reducing the external resistance, which caused the charge transfer efficiency increased since the SMDCs enabled more pairs of ions separated while one electron passed through the external circuit. The maximum TDR of 0.0252 g/h was obtained using a two-desalination-chambered SMDC with an external resistance of 10 Ω, which was 1.4 times that of single-desalination-chambered MDC. SMDCs proved to be an effective approach to increase the total water desalination rate if provided a proper desalination chamber number and external resistance.

  13. 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.

  14. Evaluation of a single cell and candidate materials with high water content hydrogen in a generic solid oxide fuel cell stack test fixture, Part II: materials and interface characterization

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

    A generic solid oxide fuel cell (SOFC) test fixture was developed to evaluate candidate materials under realistic conditions. A commerical 50 mm x 50 mm NiO-YSZ anode supported thin YSZ electrolyte cell with lanthanum strontium manganite (LSM) cathode was tested to evaluate the stability of candidate materials. The cell was tested in two stages at 800oC: stage I of low (~3% H2O) humidity and stage II of high (~30% H2O) humidity hydrogen fuel at constant voltage or constant current mode. Part I of the work was published earlier with information of the generic test fixture design, materials, cell performance, and optical post-mortem analysis. In part II, detailed microstructure and interfacial characterizations are reported regarding the SOFC candidate materials: (Mn,Co)-spinel conductive coating, alumina coating for sealing area, ferritic stainless steel interconnect, refractory sealing glass, and their interactions with each other. Overall, the (Mn,Co)-spinel coating was very effective in minimizing Cr migration. No Cr was identified in the cathode after 1720h at 800oC. Aluminization of metallic interconnect also proved to be chemically compatible with alkaline-earth silicate sealing glass. The details of interfacial reaction and microstructure development are discussed.

  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. Control-oriented dynamic fuzzy model and predictive control for proton exchange membrane fuel cell stack

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

    Proton exchange membrane fuel cell (PEMFC) stack temperature and cathode stoichiometric oxygen are very important control parameters. The performance and lifespan of PEMFC stack are greatly dependent on the parameters. So, in order to improve the performance index, tight control of two parameters within a given range and reducing their fluctuation are indispensable.However, control-oriented models and control strategies are very weak junctures in the PEMFC development. A predictive control algorithm was presented based on their model established by input-output data and operating experiences. It adjusts the operating temperature to 80 ℃. At the same time, the optimized region of stoichiometric oxygen is kept between 1.8-2.2. Furthermore, the control algorithm adjusts the variants quickly to the destination value and makes the fluctuation of the variants the least. According to the test results, compared with traditional fuzzy and PID controllers, the designed controller shows much better performance.

  17. Dynamic fuel cell stack model for real-time simulation based on system identification

    Science.gov (United States)

    Meiler, M.; Schmid, O.; Schudy, M.; Hofer, E. P.

    The authors have been developing an empirical mathematical model to predict the dynamic behaviour of a polymer electrolyte membrane fuel cell (PEMFC) stack. Today there is a great number of models, describing steady-state behaviour of fuel cells by estimating the equilibrium voltage for a certain set of operating parameters, but models capable of predicting the transient process between two steady-state points are rare. However, in automotive applications round about 80% of operating situations are dynamic. To improve the reliability of fuel cell systems by model-based control for real-time simulation dynamic fuel cell stack model is needed. Physical motivated models, described by differential equations, usually are complex and need a lot of computing time. To meet the real-time capability the focus is set on empirical models. Fuel cells are highly nonlinear systems, so often used auto-regressive (AR), output-error (OE) or Box-Jenkins (BJ) models do not accomplish satisfying accuracy. Best results are achieved by splitting the behaviour into a nonlinear static and a linear dynamic subsystem, a so-called Uryson-Model. For system identification and model validation load steps with different amplitudes are applied to the fuel cell stack at various operation points and the voltage response is recorded. The presented model is implemented in MATLAB environment and has a computing time of less than 1 ms per step on a standard desktop computer with a 2.8 MHz CPU and 504 MB RAM. Lab tests are carried out at DaimlerChrysler R&D Centre with DaimlerChrysler PEMFC hardware and a good agreement is found between model simulations and lab tests.

  18. Dynamic fuel cell stack model for real-time simulation based on system identification

    Energy Technology Data Exchange (ETDEWEB)

    Meiler, M.; Schmid, O.; Schudy, M. [Department of MEA and Stack Technology, DaimlerChrysler AG, Neue Str. 95, D-73230 Kirchheim/Teck (Germany); Hofer, E.P. [Department of Measurement, Control and Microtechnology, University of Ulm, Albert-Einstein-Allee 41, D-89081 Ulm (Germany)

    2008-02-01

    The authors have been developing an empirical mathematical model to predict the dynamic behaviour of a polymer electrolyte membrane fuel cell (PEMFC) stack. Today there is a great number of models, describing steady-state behaviour of fuel cells by estimating the equilibrium voltage for a certain set of operating parameters, but models capable of predicting the transient process between two steady-state points are rare. However, in automotive applications round about 80% of operating situations are dynamic. To improve the reliability of fuel cell systems by model-based control for real-time simulation dynamic fuel cell stack model is needed. Physical motivated models, described by differential equations, usually are complex and need a lot of computing time. To meet the real-time capability the focus is set on empirical models. Fuel cells are highly nonlinear systems, so often used auto-regressive (AR), output-error (OE) or Box-Jenkins (BJ) models do not accomplish satisfying accuracy. Best results are achieved by splitting the behaviour into a nonlinear static and a linear dynamic subsystem, a so-called Uryson-Model. For system identification and model validation load steps with different amplitudes are applied to the fuel cell stack at various operation points and the voltage response is recorded. The presented model is implemented in MATLAB environment and has a computing time of less than 1 ms per step on a standard desktop computer with a 2.8 MHz CPU and 504 MB RAM. Lab tests are carried out at DaimlerChrysler R and D Centre with DaimlerChrysler PEMFC hardware and a good agreement is found between model simulations and lab tests. (author)

  19. 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.

  20. 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.

  1. 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.

  2. Testing the sampling efficiency of a nuclear power station stack monitor

    Energy Technology Data Exchange (ETDEWEB)

    Stroem, L.H. [Instrumentinvest, Nykoeping (Sweden)

    1997-08-01

    The test method comprises the injection of known amounts of monodisperse particles in the stack air stream, at a suitable point upstream of the sampling installation. To find a suitable injection polls, the gas flow was mapped by means of a tracer gas, released in various points in the stack base. The resulting concentration distributions at the stack sampler level were observed by means of an array of gas detectors. An injection point that produced symmetrical distribution over the stack area, and low concentrations at the stack walls was selected for the particle tests. Monodisperse particles of 6, 10, and 19 {mu}m aerodynamic diameter, tagged with dysprosium, were dispersed in the selected injection point. Particle concentration at the sampler level was measured. The losses to the stack walls were found to be less than 10 %. The particle concentrations at the four sampler inlets were calculated from the observed gas distribution. The amount calculated to be aspirated into the sampler piping was compared with the quantity collected by the sampling train ordinary filter, to obtain the sampling line transmission efficiency. 1 ref., 2 figs.

  3. In-situ electrochemically active surface area evaluation of an open-cathode polymer electrolyte membrane fuel cell stack

    Science.gov (United States)

    Torija, Sergio; Prieto-Sanchez, Laura; Ashton, Sean J.

    2016-09-01

    The ability to evaluate the electrochemically active surface area (ECSA) of fuel cell electrodes is crucial toward characterising designs and component suites in-situ, particularly when evaluating component durability in endurance testing, since it is a measure of the electrode area available to take part in the fuel cell reactions. Conventional methods to obtain the ECSA using cyclic voltammetry, however, rely on potentiostats that cannot be easily scaled to simultaneously evaluate all cells in a fuel cell stack of practical size, which is desirable in fuel cell development. In-situ diagnostics of an open-cathode fuel cell stack are furthermore challenging because the cells do not each possess an enclosed cathode compartment; instead, the cathodes are rather open to the environment. Here we report on a diagnostic setup that allows the electrochemically active surface area of each cell anode or cathode in an open-cathode fuel cell stack to be evaluated in-situ and simultaneously, with high resolution and reproducibility, using an easily scalable chronopotentiometry methodology and a gas-tight stack enclosure.

  4. Developments for improved direct methanol fuel cell stacks for portable power

    Energy Technology Data Exchange (ETDEWEB)

    Cremers, C.; Stimming, U. [Bavarian Center for Applied Energy Research, ZAE Bayern, Abteilung 1, Walther-Meissner-Str. 6, D-85748 Garching (Germany); Technische Universitaet Muenchen, Department of Physics E19, James-Franck-Str. 1, D-85748 Garching (Germany); Scholz, M.; Seliger, W. [Bavarian Center for Applied Energy Research, ZAE Bayern, Abteilung 1, Walther-Meissner-Str. 6, D-85748 Garching (Germany); Racz, A. [Technische Universitaet Muenchen, Department of Physics E19, James-Franck-Str. 1, D-85748 Garching (Germany); Knechtel, W.; Rittmayr, J.; Grafwallner, F.; Peller, H. [ET EnergieTechnologie GmbH, Eugen-Saenger-Ring 4, D-85649 Brunnthal-Nord (Germany)

    2007-02-15

    Different aspects of the improvement of direct methanol fuel cell (DMFC) systems for portable power generation are investigated, in a project funded by the Bavarian state. The materials research focuses on the development of improved catalysts, in particular for the oxygen reduction reaction. Some recent results on supported ruthenium selenium catalysts are reported. In parallel, tests on other fuel cell materials are performed using MEAs made from industrial unsupported catalysts as the reference. These standard MEAs have catalyst loadings of about 11 mg cm{sup -2} and, at high air flux, can deliver current densities of about 500 mA cm{sup -2} and 100 mA cm{sup -2} at 110 C and 50 C, respectively. At low air flux and 50 C, current densities between 60 and 80 mA cm{sup -2} are possible rate at 500 mV. Using these MEAs, different commercial gas diffusion materials are tested as the cathode backing. Thus, it is found that the Sigracet materials by SGL Carbon are the most suitable for operation at a low air flux. Finally, a demonstration stack, comprised of up to ten cells, is developed using graphite PVDF compound bipolar plates by SGL Carbon. As will be reported, this stack shows a high homogeneity of cell voltages and stable operation under relevant conditions, using standard MEAs. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  5. Vibration mode analysis of the proton exchange membrane fuel cell stack

    Science.gov (United States)

    Liu, B.; Liu, L. F.; Wei, M. Y.; Wu, C. W.

    2016-11-01

    Proton exchange membrane fuel cell (PEMFC) stacks usually undergo vibration during packing, transportation, and serving time, in particular for those used in the automobiles or portable equipment. To study the stack vibration response, based on finite element method (FEM), a mode analysis is carried out in the present paper. Using this method, we can distinguish the local vibration from the stack global modes, predict the vibration responses, such as deformed shape and direction, and discuss the effects of the clamping configuration and the clamping force magnitude on vibration modes. It is found that when the total clamping force remains the same, increasing the bolt number can strengthen the stack resistance to vibration in the clamping direction, but cannot obviously strengthen stack resistance to vibration in the translations perpendicular to clamping direction and the three axis rotations. Increasing the total clamping force can increase both of the stack global mode and the bolt local mode frequencies, but will decrease the gasket local mode frequency.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Pressurized Operation of a Planar Solid Oxide Cell Stack

    DEFF Research Database (Denmark)

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

    2016-01-01

    (electrode performance) increases for thermodynamic and kinetic reasons, respectively. Further, the summit frequency of the gas concentration impedance arc and the pressure difference across the stack and heat exchangers is seen to decrease with increasing pressure following a power-law expression. Finally...

  11. A new stochastic algorithm for proton exchange membrane fuel cell stack design optimization

    Science.gov (United States)

    Chakraborty, Uttara

    2012-10-01

    This paper develops a new stochastic heuristic for proton exchange membrane fuel cell stack design optimization. The problem involves finding the optimal size and configuration of stand-alone, fuel-cell-based power supply systems: the stack is to be configured so that it delivers the maximum power output at the load's operating voltage. The problem apparently looks straightforward but is analytically intractable and computationally hard. No exact solution can be found, nor is it easy to find the exact number of local optima; we, therefore, are forced to settle with approximate or near-optimal solutions. This real-world problem, first reported in Journal of Power Sources 131, poses both engineering challenges and computational challenges and is representative of many of today's open problems in fuel cell design involving a mix of discrete and continuous parameters. The new algorithm is compared against genetic algorithm, simulated annealing, and (1+1)-EA. Statistical tests of significance show that the results produced by our method are better than the best-known solutions for this problem published in the literature. A finite Markov chain analysis of the new algorithm establishes an upper bound on the expected time to find the optimum solution.

  12. 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.)

  13. Behavioral pattern of a monopolar passive direct methanol fuel cell stack

    Science.gov (United States)

    Kim, Young-Jin; Bae, Byungchan; Scibioh, M. Aulice; Cho, EunAe; Ha, Heung Yong

    A passive, air-breathing, monopolar, liquid feed direct methanol fuel cell (DMFC) stack consisting of six unit cells with no external pump, fan or auxiliary devices to feed the reactants has been designed and fabricated for its possible employment as a portable power source. The configurations of the stack of monopolar passive feed DMFCs are different from those of bipolar active feed DMFCs and therefore its operational characteristics completely vary from the active ones. Our present investigation primarily focuses on understanding the unique behavioral patterns of monopolar stack under the influence of certain operating conditions, such as temperature, methanol concentration and reactants feeding methods. With passive reactants supply, the temperature of the stack and open circuit voltage (OCV) undergo changes over time due to a decrease in concentration of methanol in the reservoir as the reaction proceeds. Variations in performance and temperature of the stack are mainly influenced by the concentration of methanol. Continuous operation of the passive stack is influenced by the supply of methanol rather than air supply or water accumulation at the cathode. The monopolar stack made up of six unit cells exhibits a total power of 1000 mW (37 mW cm -2) with 4 M methanol under ambient conditions.

  14. 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.

  15. A high-performance aluminum-feed microfluidic fuel cell stack

    Science.gov (United States)

    Wang, Yifei; Leung, Dennis Y. C.

    2016-12-01

    In this paper, a six-cell microfluidic fuel cell (MFC) stack is demonstrated. Low-cost aluminum is fed directly to the stack, which produces hydrogen fuel on site, through the Al-H2O reaction. This design is not only cost-efficient, but also eliminates the need for hydrogen storage. Unlike the conventional MFC stacks which generally require complex electrolyte distribution and management, the present Al-feed MFC stack requires only a single electrolyte stream, flowing successively through individual cells, which is finally utilized for hydrogen generation. In this manner, the whole system is greatly simplified while the operational robustness is also improved. With 2 M sodium hydroxide solution as electrolyte and kitchen foil Al as fuel, the present six-cell stack (in series) exhibits an open circuit voltage of nearly 6 V and a peak power density of 180.6 mWcm-2 at room temperature. In addition, an energy density of 1 Whg-1(Al) is achieved, which is quite high and comparable with its proton exchange membrane-based counterparts. Finally, pumpless operation of the present stack, together with its practical applications are successfully demonstrated, including lightening LED lights, driving an electric fan, and cell phone charging.

  16. Stack test results at Phelps-Dodge Corporation, Ajo, Arizona. Volume I. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, J.

    1977-03-01

    In July 1976 at the request of EPA, Region IX, Enforcement Division, the Aerotherm Division of the Acurex Corporation conducted a series of air pollutant mass emissions tests at the new Cornelia Branch copper smelter of the Phelps Dodge Corporation located in Ajo, Arizona. The tests were performed simultaneously at three locations: (1) the main stack, (2) the reverberatory furnace duct and (3) the converter side sulfuric acid plant tail gas duct. Tests for particulate matter (Method 5), sulfur dioxide and sulfuric acid (Method 8) were conducted at each location using a combined sampling train. In addition tests for 'condensable particulate matter' were conducted at the main stack and the reverberatory furnace duct using the combined Method 5 and 8 sampling train with an instack filter added.

  17. Stability of SiNX/SiNX double stack antireflection coating for single crystalline silicon solar cells

    Science.gov (United States)

    Lee, Youngseok; Gong, Daeyeong; Balaji, Nagarajan; Lee, Youn-Jung; Yi, Junsin

    2012-01-01

    Double stack antireflection coatings have significant advantages over single-layer antireflection coatings due to their broad-range coverage of the solar spectrum. A solar cell with 60-nm/20-nm SiNX:H double stack coatings has 17.8% efficiency, while that with a 80-nm SiNX:H single coating has 17.2% efficiency. The improvement of the efficiency is due to the effect of better passivation and better antireflection of the double stack antireflection coating. It is important that SiNX:H films have strong resistance against stress factors since they are used as antireflective coating for solar cells. However, the tolerance of SiNX:H films to external stresses has never been studied. In this paper, the stability of SiNX:H films prepared by a plasma-enhanced chemical vapor deposition system is studied. The stability tests are conducted using various forms of stress, such as prolonged thermal cycle, humidity, and UV exposure. The heat and damp test was conducted for 100 h, maintaining humidity at 85% and applying thermal cycles of rapidly changing temperatures from -20°C to 85°C over 5 h. UV exposure was conducted for 50 h using a 180-W UV lamp. This confirmed that the double stack antireflection coating is stable against external stress.

  18. 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.

  19. 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...

  20. Theoretical simulations of InGaN/Si mechanically stacked two-junction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhidong, E-mail: hlxiao@semi.ac.cn [Key Lab of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China); Xiao, Hongling [Key Lab of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China); Wang, Xiaoliang [Key Lab of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China); ISCAS-XJTU Joint Laboratory of Functional Materials and Devices for Informatics, Beijing (China); Wang, Cuimei; Deng, Qingwen; Jing, Liang; Ding, Jieqin [Key Lab of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China); Hou, Xun [Xi' an Jiaotong University, Xi' an 710049 (China)

    2013-04-01

    In this study, potential efficiency of InGaN/Si mechanically stacked two-junction solar cell is theoretically investigated by optimizing the band gap and thickness of the top InGaN cell. Results show that the optimum conversion efficiency is 35.2% under AM 1.5 G spectral illuminations, with the bandgap and thickness of top InGaN solar cell are 2.0 eV and 600 nm, respectively. The results and discussion would be helpful in designing and fabricating high efficiency InGaN/Si mechanically stacked solar cell in experiment.

  1. 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.

  2. Device for equalizing molten electrolyte content in a fuel cell stack

    Science.gov (United States)

    Smith, J.L.

    1985-12-23

    A device for equalizing the molten electrolyte content throughout the height of a fuel cell stack is disclosed. The device includes a passageway for electrolyte return with electrolyte wettable wicking material in the opposite end portions of the passageway. One end portion is disposed near the upper, negative end of the stack where electrolyte flooding occurs. The second end portion is placed near the lower, positive end of the stack where electrolyte is depleted. Heating means are provided at the upper portion of the passageway to increase electrolyte vapor pressure in the upper wicking material. The vapor is condensed in the lower passageway portion and conducted as molten electrolyte in the lower wick to the positive end face of the stack. An inlet is provided to inject a modifying gas into the passageway and thereby control the rate of electrolyte return.

  3. 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.

  4. Simulation and in situ measurement of stress distribution in a polymer electrolyte membrane fuel cell stack

    Science.gov (United States)

    de la Cruz, Javier; Cano, Ulises; Romero, Tatiana

    2016-10-01

    A critical parameter for PEM fuel cell's electric contact is the nominal clamping pressure. Predicting the mechanical behavior of all components in a fuel cell stack is a very complex task due to the diversity of materials properties. Prior to the integration of a 3 kW PEMFC power plant, a numerical simulation was performed in order to obtain the mechanical stress distribution for two of the most pressure sensitive components of the stack: the membrane, and the graphite plates. The stress distribution of the above mentioned components was numerically simulated by finite element analysis and the stress magnitude for the membrane was confirmed using pressure films. Stress values were found within the elastic zone which guarantees mechanical integrity of fuel cell components. These low stress levels particularly for the membrane will allow prolonging the life and integrity of the fuel cell stack according to its design specifications.

  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...

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

    Science.gov (United States)

    Wang, X.; Tajiri, K.; Ahluwalia, R. K.

    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 (λ, 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 λ (λ 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 λ (λ l), below which the stack can be self-started without forming ice. Between λ l and λ h, the stack can be self-started, but with intermediate formation of ice that melts as the stack warms up to 0 °C. Both λ l and λ 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 λ for a subsequent successful startup. There is an optimum λ for robust and rapid startup and shutdown. Startup and shutdown time and energy may be unacceptable if the λ is much less than the optimum. Conversely, a robust startup from subfreezing temperatures cannot be assured if the λ is much higher than this optimum.

  7. 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)

  8. 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.

  9. Cryogenic Testing of High Current By-pass Diode Stacks for the Protection of the Superconducting Magnets in the LHC

    CERN Document Server

    Brown, D; Fiamozzi-Zignani, C; Gharib, A; Hagedorn, Dietrich; Rout, C; Turtu, S

    2004-01-01

    For the protection of the LHC superconducting magnets, about 2100 specially developed by-pass diodes were manufactured by DYNEX SEMICONDUCTOR LTD (Lincoln, GB) and about 1300 of these diodes were mounted into diode stacks and submitted to tests at cryogenic temperatures. To date about 800 dipole diode stacks and about 250 quadrupole diode stacks for the protection of the superconducting lattice dipole and lattice quadrupole magnets have been assembled at OCEM (Bologna,Italy) and successfully tested in liquid helium at ENEA (Frascati, Italy). This report gives an overview of the test results obtained so far. After a short description of the test installations and test procedures, a statistical analysis is presented for test data during diode production as well as for the performance of the diode stacks during testing in liquid helium, including failure rates and degradation of the diodes.

  10. 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.

  11. 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.

  12. PEM fuel cell stack performance using dilute hydrogen mixture. Implications on electrochemical engine system performance and design

    Energy Technology Data Exchange (ETDEWEB)

    Inbody, M.A.; Vanderborgh, N.E.; Hedstrom, J.C.; Tafoya, J.I. [Los Alamos National Lab., NM (United States)

    1996-12-31

    Onboard fuel processing to generate a hydrogen-rich fuel for PEM fuel cells is being considered as an alternative to stored hydrogen fuel for transportation applications. If successful, this approach, contrasted to operating with onboard hydrogen, utilizes the existing fuels infrastructure and provides required vehicle range. One attractive, commercial liquid fuels option is steam reforming of methanol. However, expanding the liquid methanol infrastructure will take both time and capital. Consequently technology is also being developed to utilize existing transportation fuels, such as gasoline or diesel, to power PEM fuel cell systems. Steam reforming of methanol generates a mixture with a dry gas composition of 75% hydrogen and 25% carbon dioxide. Steam reforming, autothermal reforming, and partial oxidation reforming of C{sub 2} and larger hydrocarbons produces a mixture with a more dilute hydrogen concentration (65%-40%) along with carbon dioxide ({approx}20%) and nitrogen ({approx}10%-40%). Performance of PEM fuel cell stacks on these dilute hydrogen mixtures will affect the overall electrochemical engine system design as well as the overall efficiency. The Los Alamos Fuel Cell Stack Test facility was used to access the performance of a PEM Fuel cell stack over the range of gas compositions chosen to replicate anode feeds from various fuel processing options for hydrocarbon and alcohol fuels. The focus of the experiments was on the anode performance with dilute hydrogen mixtures with carbon dioxide and nitrogen diluents. Performance with other anode feed contaminants, such as carbon monoxide, are not reported here.

  13. 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

  14. 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

    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...

  15. Modular, High-Volume Fuel Cell Leak-Test Suite and Process

    Energy Technology Data Exchange (ETDEWEB)

    Ru Chen; Ian Kaye

    2012-03-12

    Fuel cell stacks are typically hand-assembled and tested. As a result the manufacturing process is labor-intensive and time-consuming. The fluid leakage in fuel cell stacks may reduce fuel cell performance, damage fuel cell stack, or even cause fire and become a safety hazard. Leak check is a critical step in the fuel cell stack manufacturing. The fuel cell industry is in need of fuel cell leak-test processes and equipment that is automatic, robust, and high throughput. The equipment should reduce fuel cell manufacturing cost.

  16. 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.

  17. Rapid self-start of polymer electrolyte fuel cell stacks from subfreezing temperatures

    Science.gov (United States)

    Ahluwalia, R. K.; Wang, X.

    Polymer electrolyte fuel cell (PEFC) systems for light-duty vehicles must be able to start unassisted and rapidly from temperatures below -20 °C. Managing buildup of ice within the porous cathode catalyst and electrode structure is the key to self-starting a PEFC stack from subfreezing temperatures. The stack temperature must be raised above the melting point of ice before the ice completely covers the cathode catalyst and shuts down the electrochemical reaction. For rapid and robust self-start it is desirable to operate the stack near the short-circuit conditions. This mode of operation maximizes hydrogen utilization, favors production of waste heat that is absorbed by the stack, and delays complete loss of effective electrochemical surface area by causing a large fraction of the ice to form in the gas diffusion layer rather than in the cathode catalyst layer. Preheating the feed gases, using the power generated to electrically heat the stack, and operating pressures have only small effect on the ability to self-start or the startup time. In subfreezing weather, the stack shut-down protocol should include flowing ambient air through the hot cathode passages to vaporize liquid water remaining in the cathode catalyst. Self-start is faster and more robust if the bipolar plates are made from metal rather than graphite.

  18. 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.

  19. Physico-chemical study of the degradation of membrane-electrode assemblies in a proton exchange membrane fuel cell stack

    Science.gov (United States)

    Ferreira-Aparicio, P.; Gallardo-López, B.; Chaparro, A. M.; Daza, L.

    A proton exchange membrane fuel cell stack integrated by 8-elements has been evaluated in an accelerated stress test. The application of techniques such as TEM analyses of ultramicrotome-sliced sections of some samples and XRD, XPS and TGA of spent electrodes reveal the effects of several degradation processes contributing to reduce the cells performance. The reduction of the Pt surface area at the cathode is favored by the oxidation of carbon black agglomerates in the catalytic layer, the agglomeration of Pt particles and by the partial dissolution of Pt, which migrates towards the anode and precipitates within the membrane. In the light of the TEM, EDAX and XPS results, two combined effects are probably responsible of the increase of the internal resistance of the stack cells: (i) a lower proton conductivity of the membranes due to the high affinity of the sulfonic acid groups for ions originated from Pt crystallites and other peripherical elements such as the silicone elastomeric gaskets and (ii) the increment of electrically isolated islands in the cathode gas diffusion electrodes resulting from carbon corrosion and the degradation of the perfluorinated polymers. Water accumulation and inhomogeneous gas distribution throughout the stack cells originate different degradation rates in them.

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

    OpenAIRE

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

    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 ex...

  1. Thermally Sprayed Large Tubular Solid Oxide Fuel Cells and Its Stack: Geometry Optimization, Preparation, and Performance

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Liu, Shuai; Li, Chang-Jiu; Yang, Guan-Jun; He, Peng-Jiang; Yun, Liang-Liang; Song, Bo; Xie, Ying-Xin

    2017-02-01

    In this study, we develop a large tubular solid oxide fuel cells design with several cells in series on a porous cermet support, which has many characteristics such as self-sealing, low Ohmic loss, high strength, and good thermal expansion coefficient matching. Here, we investigate aspects of the cell design, manufacture, performance, and application. Firstly, the cell length and number of cells in series are optimized by theoretical analysis. Then, thermal spraying is applied as a cost-effective method to prepare all the cell components. Finally, the performance of different types of cells and two types of stacks is characterized. The maximum output power of one tube, which had 20 cells in series, reaches 31 and 40.5 W at 800 and 900 °C, respectively. Moreover, the output power of a stack assembled with 56 tubes, each with ten cells in series, reaches 800 W at 830 °C. The excellent single tube and cell stack performance suggest that thermally sprayed tubular SOFCs have significant potential for commercialized application.

  2. Thermally Sprayed Large Tubular Solid Oxide Fuel Cells and Its Stack: Geometry Optimization, Preparation, and Performance

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Liu, Shuai; Li, Chang-Jiu; Yang, Guan-Jun; He, Peng-Jiang; Yun, Liang-Liang; Song, Bo; Xie, Ying-Xin

    2017-01-01

    In this study, we develop a large tubular solid oxide fuel cells design with several cells in series on a porous cermet support, which has many characteristics such as self-sealing, low Ohmic loss, high strength, and good thermal expansion coefficient matching. Here, we investigate aspects of the cell design, manufacture, performance, and application. Firstly, the cell length and number of cells in series are optimized by theoretical analysis. Then, thermal spraying is applied as a cost-effective method to prepare all the cell components. Finally, the performance of different types of cells and two types of stacks is characterized. The maximum output power of one tube, which had 20 cells in series, reaches 31 and 40.5 W at 800 and 900 °C, respectively. Moreover, the output power of a stack assembled with 56 tubes, each with ten cells in series, reaches 800 W at 830 °C. The excellent single tube and cell stack performance suggest that thermally sprayed tubular SOFCs have significant potential for commercialized application.

  3. Solid Acid Fuel Cell Stack for APU Applications

    Energy Technology Data Exchange (ETDEWEB)

    Duong, Hau H. [SAFCell, Inc., Pasadena, CA (United States)

    2011-04-15

    Solid acid fuel cell technology affords the opportunity to operate at the 200-300 degree centigrade regime that would allow for more fuel flexibility, compared to polymer electrode membrane fuel cell, while avoiding the relatively more expensive and complex system components required by solid oxide fuel cell. This project addresses many factors such as MEA size scalability, fuel robustness, stability, etc., that are essential for successful commercialization of the technology.

  4. 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 ...... 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....

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

    NARCIS (Netherlands)

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

    2012-01-01

    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

  6. 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.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... the transient behavior of Crofer 22 APU, a typical iron-chromium alloy used in SOFC stacks. The material parameters for the model are determined by measurements involving relaxation and constant strain rate experiments. The constitutive law is implemented into commercial finite element software using a user...

  8. Online estimation of internal stack temperatures in solid oxide fuel cell power generating units

    Science.gov (United States)

    Dolenc, B.; Vrečko, D.; Juričić, Ɖ.; Pohjoranta, A.; Pianese, C.

    2016-12-01

    Thermal stress is one of the main factors affecting the degradation rate of solid oxide fuel cell (SOFC) stacks. In order to mitigate the possibility of fatal thermal stress, stack temperatures and the corresponding thermal gradients need to be continuously controlled during operation. Due to the fact that in future commercial applications the use of temperature sensors embedded within the stack is impractical, the use of estimators appears to be a viable option. In this paper we present an efficient and consistent approach to data-driven design of the estimator for maximum and minimum stack temperatures intended (i) to be of high precision, (ii) to be simple to implement on conventional platforms like programmable logic controllers, and (iii) to maintain reliability in spite of degradation processes. By careful application of subspace identification, supported by physical arguments, we derive a simple estimator structure capable of producing estimates with 3% error irrespective of the evolving stack degradation. The degradation drift is handled without any explicit modelling. The approach is experimentally validated on a 10 kW SOFC system.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Su-Hyun; Walsh, Aron, E-mail: a.walsh@bath.ac.uk [Global E3 Institute, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Butler, Keith T. [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Soon, Aloysius [Global E3 Institute, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Abbas, Ali; Walls, John M., E-mail: j.m.wall@loughborough.ac.uk [Centre for Renewable Energy Systems Technology, School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2014-08-11

    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 CdCl{sub 2} 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.

  10. 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.

  11. 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.)

  12. 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.

  13. 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.

  14. Cassettes for solid-oxide fuel cell stacks and methods of making the same

    Science.gov (United States)

    Weil, K. Scott; Meinhardt, Kerry D; Sprenkle, Vincent L

    2012-10-23

    Solid-oxide fuel cell (SOFC) stack assembly designs are consistently investigated to develop an assembly that provides optimal performance, and durability, within desired cost parameters. A new design includes a repeat unit having a SOFC cassette and being characterized by a three-component construct. The three components include an oxidation-resistant, metal window frame hermetically joined to an electrolyte layer of a multi-layer, anode-supported ceramic cell and a pre-cassette including a separator plate having a plurality of vias that provide electrical contact between an anode-side collector within the pre-cassette and a cathode-side current collector of an adjacent cell. The third component is a cathode-side seal, which includes a standoff that supports a cathode channel spacing between each of the cassettes in a stack. Cassettes are formed by joining the pre-cassette and the window frame.

  15. Evaluation of gas cooling for pressurized phosphoric acid fuel cell stacks

    Science.gov (United States)

    Farooque, M.; Skok, A. J.; Maru, H. C.; Kothmann, R. E.; Harry, R. W.

    1983-01-01

    Gas cooling is a more reliable, less expensive and a more simple alternative to conventional liquid cooling for heat removal from the phosphoric acid fuel cell (PAFC). The feasibility of gas cooling has already been demonstrated in atmospheric pressure stacks. This paper presents theoretical and experimental investigation of gas cooling for pressurized PAFC. Two approaches to gas cooling, Distributed Gas Cooling (DIGAS) and Separated Gas Cooling (SGC) were considered, and a theoretical comparison on the basis of cell performance indicated SGC to be superior to DIGAS. The feasibility of SGC was experimentally demonstrated by operating a 45-cell stack for 700 hours at pressure, and determining thermal response and the effect of other related parameters.

  16. Cost Analysis of Direct Methanol Fuel Cell Stacks for Mass Production

    Directory of Open Access Journals (Sweden)

    Mauro Francesco Sgroi

    2016-11-01

    Full Text Available Fuel cells are very promising technologies for efficient electrical energy generation. The development of enhanced system components and new engineering solutions is fundamental for the large-scale deployment of these devices. Besides automotive and stationary applications, fuel cells can be widely used as auxiliary power units (APUs. The concept of a direct methanol fuel cell (DMFC is based on the direct feed of a methanol solution to the fuel cell anode, thus simplifying safety, delivery, and fuel distribution issues typical of conventional hydrogen-fed polymer electrolyte fuel cells (PEMFCs. In order to evaluate the feasibility of concrete application of DMFC devices, a cost analysis study was carried out in the present work. A 200 W-prototype developed in the framework of a European Project (DURAMET was selected as the model system. The DMFC stack had a modular structure allowing for a detailed evaluation of cost characteristics related to the specific components. A scale-down approach, focusing on the model device and projected to a mass production, was used. The data used in this analysis were obtained both from research laboratories and industry suppliers specialising in the manufacturing/production of specific stack components. This study demonstrates that mass production can give a concrete perspective for the large-scale diffusion of DMFCs as APUs. The results show that the cost derived for the DMFC stack is relatively close to that of competing technologies and that the introduction of innovative approaches can result in further cost savings.

  17. Improved performance of the microbial electrolysis desalination and chemical-production cell using the stack structure.

    Science.gov (United States)

    Chen, Shanshan; Liu, Guangli; Zhang, Renduo; Qin, Bangyu; Luo, Yong; Hou, Yanping

    2012-07-01

    The microbial electrolysis desalination and chemical-production cell (MEDCC) is a device to desalinate seawater, and produce acid and alkali. The objective of this study was to enhance the desalination and chemical-production performance of the MEDCC using two types of stack structure. Experiments were conducted with different membrane spacings, numbers of desalination chambers and applied voltages. Results showed that the stack construction in the MEDCC enhanced the desalination and chemical-production rates. The maximal desalination rate of 0.58 ± 0.02 mmol/h, which was 43% higher than that in the MEDCC, was achieved in the four-desalination-chamber MEDCC with the AEM-CEM stack structure and the membrane spacing of 1.5mm. The maximal acid- and alkali-production rates of 0.079 ± 0.006 and 0.13 ± 0.02 mmol/h, which were 46% and 8% higher than that in the MEDCC, respectively, were achieved in the two-desalination-chamber MEDCC with the BPM-AEM-CEM stack structure and the membrane spacing of 3mm.

  18. Testing of Ni-plated ferritic steel interconnect in SOFC stacks

    DEFF Research Database (Denmark)

    Nielsen, K.A.; Dinesen, A.R.; Korcakova, L.

    2006-01-01

    Stack tests were run at 850 °C for periods from 80 hours to 1,150 hours to develop contacting procedures and at the same time evaluate the performance of a 5 μm electroplated nickel coating on a ferritic Fe22Cr interconnect. The metallic nickel coating reacted relatively quickly during the initial...... heating to 1,030 °C. During this time, 20–70 μm thick surface layers of austenitic steel were formed, which were covered by a 1–4 μm chromia layer on the anode side and by a layer of mixed Cr-Fe-Ni-spinels over a 1–4 μm chromia layer on the cathode side. The microstructure and composition...

  19. 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.

  20. 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%.

  1. 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.

  2. Performance comparison between high temperature and traditional proton exchange membrane fuel cell stacks using electrochemical impedance spectroscopy

    Science.gov (United States)

    Zhu, Ying; Zhu, Wenhua H.; Tatarchuk, Bruce J.

    2014-06-01

    A temperature above 100 °C is always desired for proton exchange membrane (PEM) fuel cell operation. It not only improves kinetic and mass transport processes, but also facilitates thermal and water management in fuel cell systems. Increased carbon monoxide (CO) tolerance at higher operating temperature also simplifies the pretreatment of fuel supplement. The novel phosphoric acid (PA) doped polybenzimidazole (PBI) membranes achieve PEM fuel cell operations above 100 °C. The performance of a commercial high temperature (HT) PEM fuel cell stack module is studied by measuring its impedance under various current loads when the operating temperature is set at 160 °C. The contributions of kinetic and mass transport processes to stack impedance are analyzed qualitatively and quantitatively by equivalent circuit (EC) simulation. The performance of a traditional PEM fuel cell stack module operated is also studied by impedance measurement and EC simulation. The operating temperature is self-stabilized between 40 °C and 65 °C. An enhancement of the HT-PEM fuel cell stack in polarization impedance is evaluated by comparing to the traditional PEM fuel cell stack. The impedance study on two commercial fuel cell stacks reveals the real situation of current fuel cell development.

  3. Effect of load ratio, testing frequency, temperature, moisture, notch and stacking sequence on the fatigue resistance of woven CFRP laminates

    OpenAIRE

    Lani, Frédéric; 6th International Conference on Fatigue of Composite ICFC2015

    2015-01-01

    A woven CFRP composite laminate has been thoroughly characterized under fatigue. Over 150 tests were performed in order to address the effect of sample geometry (Open Hole Tension, Open Hole Compression, Plain Compression, …), testing frequency (5Hz, 30Hz) with and without cooling system, load ratio (R=10., R=-1., R=0.1), temperature (RT and 120°C), moisture intake (50% RH and 85+% RH at RT), notch (Open Hole Vs. Plain Specimen), stacking sequence (3 different stacking sequences) on the measu...

  4. 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.

  5. Performance of a proton exchange membrane fuel cell stack with thermally conductive pyrolytic graphite sheets for thermal management

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Chih-Yung; Lin, Yu-Sheng; Lu, Chien-Heng [Department of Aeronautics and Astronautics, National Cheng-Kung University, Tainan 70101 (China)

    2009-04-15

    This work experimentally investigates the effects of the pyrolytic graphite sheets (PGS) on the performance and thermal management of a proton exchange membrane fuel cell (PEMFC) stack. These PGS with the features of light weight and high thermal conductivity serve as heat spreaders in the fuel cell stack for the first time to reduce the volume and weight of cooling systems, and homogenizes the temperature in the reaction areas. A PEMFC stack with an active area of 100 cm{sup 2} and 10 cells in series is constructed and used in this research. Five PGS of thickness 0.1 mm are cut into the shape of flow channels and bound to the central five cathode gas channel plates. Four thermocouples are embedded on the cathode gas channel plates to estimate the temperature variation in the stack. It is shown that the maximum power of the stack increase more than 15% with PGS attached. PGS improve the stack performance and alleviate the flooding problem at low cathode flow rates significantly. Results of this study demonstrate the feasibility of application of PGS to the thermal management of a small-to-medium-sized fuel cell stack. (author)

  6. End plate for e.g. solid oxide fuel cell stack, sets thermal expansion coefficient of material to predetermined value

    DEFF Research Database (Denmark)

    2011-01-01

    .05-0.3 mm. USE - End plate for solid oxide fuel cell stack (claimed). Can also be used in polymer electrolyte fuel cell stack and direct methanol fuel cell stack. ADVANTAGE - The robustness of the end plate is improved. The structure of the end plate is simplified. The risk of delamination of the stack......NOVELTY - The end plate is made of material whose thermal expansion coefficient is corresponding to that of material of a cell (103). The thermal expansion coefficient of material is 9asterisk10-6 K-1 to 14asterisk10-6 K11. The thickness of the end plate is within the range of 0.001-1 mm and 0...

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

    DEFF Research Database (Denmark)

    Agersted, Karsten; Chen, Ming; Blennow, Peter

    2016-01-01

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

  8. Development and characterisation of a portable direct methanol fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Oedegaard, A.

    2005-11-21

    This thesis deals with the development and characterisation of a portable direct methanol fuel cell stack. In addition, calculations of the transport of methanol and water in the membrane are compared with experimentally determined values. It also includes investigations of the behaviour of single-cells and some of its components, as the anode gas diffusion layer and the anode flow-field. For the addition of methanol to the anode feed loop, a passive concept based on a permeable tube was developed and verified by both experiments and simulations. (orig.)

  9. 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.

  10. Sickle cell test

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003666.htm Sickle cell test To use the sharing features on this page, please enable JavaScript. The sickle cell test looks for the abnormal hemoglobin in the ...

  11. Sickle Cell Tests

    Science.gov (United States)

    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Sickle Cell Tests Share this page: Was this page helpful? ... else I should know? How is it used? Sickle cell tests are used to identify the presence of ...

  12. Effectiveness of heat-integrated methanol steam reformer and polymer electrolyte membrane fuel cell stack systems for portable applications

    Science.gov (United States)

    Lotrič, A.; Sekavčnik, M.; Hočevar, S.

    2014-12-01

    Efficiently combining proton exchange membrane fuel cell (PEMFC) stack with methanol steam reformer (MSR) into a small portable system is still quite a topical issue. Using methanol as a fuel in PEMFC stack includes a series of chemical processes where each proceeds at a unique temperature. In a combined MSR-PEMFC-stack system with integrated auxiliary fuel processors (vaporizer, catalytic combustor, etc.) the processes are both endothermic and exothermic hence their proper thermal integration can help raising the system efficiency. A concept of such fully integrated and compact system is proposed in this study. Three separate systems are designed based on different PEMFC stacks and MSR. Low-temperature (LT) and conventional high-temperature (cHT) PEMFC stack characteristics are based on available data from suppliers. Also, a novel high-temperature (nHT) PEMFC stack is proposed because its operating temperature coincides with that of MSR. A comparative study of modelled systems is performed using a mass and energy balances zero-dimensional model, which is interdependently coupled to a physical model based on finite element method (FEM). The results indicate that a system with nHT PEMFC stack is feasible and has the potential to reach higher system efficiencies than systems with LT or cHT PEMFC stacks.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Analysis of early ageing of PEM fuel cell stacks in a SAM light electric vehicle; Analyse der vorzeitigen Alterung des PEM-Stacks im LEV SAM - Jahresbericht/Schlussbericht 2006

    Energy Technology Data Exchange (ETDEWEB)

    Hoeckel, M.; Ruge, M.

    2006-12-15

    This illustrated final report for the Swiss Federal Office of Energy (SFOE) presents and discusses the results of investigations concerning a PEM fuel cell stack made at the University of Applied Sciences in Bienne, Switzerland. The six-kilowatt stack showed considerable loss of power over a two-year period. The reasons behind these losses are discussed, including those caused by insufficient sealing and long periods of standstill. The measurements made on the fuel cell stack are presented and discussed. The causes of the loss of power are discussed and resulting modifications made to the stack are described. Recommendations concerning the regular use of the fuel cell stack are made in order to ensure correct operation in the future.

  18. A fuel cell balance of plant test facility

    Science.gov (United States)

    Dicks, A. L.; Martin, P. A.

    Much attention is focused in the fuel cell community on the development of reliable stack technology, but to successfully exploit fuel cells, they must form part of integrated power generation systems. No universal test facilities exist to evaluate SOFC stacks and comparatively little research has been undertaken concerning the issues of the rest of the system, or balance of plant (BOP). BG, in collaboration with Eniricerche, has therefore recently designed and built a test facility to evaluate different configurations of the BOP equipment for a 1-5 kWe solid oxide fuel cell (SOFC) stack. Within this BOP project, integrated, dynamic models have been developed. These have shown that three characteristic response times exist when the stack load is changed and that three independent control loops are required to manage the almost instantaneous change in power output from an SOFC stack, maintain the fuel utilisation and control the stack temperature. Control strategies and plant simplifications, arising from the dynamic modelling, have also been implemented in the BOP test facility. An SOFC simulator was designed and integrated into the control system of the test rig to behave as a real SOFC stack, allowing the development of control strategies without the need for a real stack. A novel combustor has been specifically designed, built and demonstrated to be capable of burning the low calorific anode exhaust gas from an SOFC using the oxygen depleted cathode stream. High temperature, low cost, shell and tube heat exchangers have been shown to be suitable for SOFC systems. Sealing of high temperature anode recirculation fans has, however, been shown to be a major issue and identified as a key area for further investigation.

  19. Dynamic model of a micro-tubular solid oxide fuel cell stack including an integrated cooling system

    Science.gov (United States)

    Hering, Martin; Brouwer, Jacob; Winkler, Wolfgang

    2017-02-01

    A novel dynamic micro-tubular solid oxide fuel cell (MT-SOFC) and stack model including an integrated cooling system is developed using a quasi three-dimensional, spatially resolved, transient thermodynamic, physical and electrochemical model that accounts for the complex geometrical relations between the cells and cooling-tubes. The modeling approach includes a simplified tubular geometry and stack design including an integrated cooling structure, detailed pressure drop and gas property calculations, the electrical and physical constraints of the stack design that determine the current, as well as control strategies for the temperature. Moreover, an advanced heat transfer balance with detailed radiative heat transfer between the cells and the integrated cooling-tubes, convective heat transfer between the gas flows and the surrounding structures and conductive heat transfer between the solid structures inside of the stack, is included. The detailed model can be used as a design basis for the novel MT-SOFC stack assembly including an integrated cooling system, as well as for the development of a dynamic system control strategy. The evaluated best-case design achieves very high electrical efficiency between around 75 and 55% in the entire power density range between 50 and 550 mW /cm2 due to the novel stack design comprising an integrated cooling structure.

  20. Development of a charge-transfer distribution model for stack simulation of solid oxide fuel cells

    Science.gov (United States)

    Onaka, H.; Iwai, H.; Kishimoto, M.; Saito, M.; Yoshida, H.; Brus, G.; Szmyd, J. S.

    2016-09-01

    An overpotential model for planar solid oxide fuel cells (SOFCs) is developed and applied to a stack numerical simulation. Charge-transfer distribution within the electrodes are approximated using an exponential function, based on which the Ohmic loss and activation overpotential are evaluated. The predicted current-voltage characteristics agree well with the experimental results, and also the overpotentials within the cell can reproduce the results obtained from a numerical analysis where the distribution of the charge-transfer current within the electrodes is fully solved. The proposed model is expected to be useful to maintain the accuracy of SOFC simulations when the cell components, consisting of anode, electrolyte and cathode, are simplified into one layer element.

  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. 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.

  3. Simulation and Test of a Fuel Cell Hybrid Golf Cart

    Directory of Open Access Journals (Sweden)

    Jingming Liang

    2014-01-01

    Full Text Available This paper establishes the simulation model of fuel cell hybrid golf cart (FCHGC, which applies the non-GUI mode of the Advanced Vehicle Simulator (ADVISOR and the genetic algorithm (GA to optimize it. Simulation of the objective function is composed of fuel consumption and vehicle dynamic performance; the variables are the fuel cell stack power sizes and the battery numbers. By means of simulation, the optimal parameters of vehicle power unit, fuel cell stack, and battery pack are worked out. On this basis, GUI mode of ADVISOR is used to select the rated power of vehicle motor. In line with simulation parameters, an electrical golf cart is refitted by adding a 2 kW hydrogen air proton exchange membrane fuel cell (PEMFC stack system and test the FCHGC. The result shows that the simulation data is effective but it needs improving compared with that of the real cart test.

  4. 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.

  5. Identification of critical parameters for PEMFC stack performance characterization and control strategies for reliable and comparable stack benchmarking

    DEFF Research Database (Denmark)

    Mitzel, Jens; Gülzow, Erich; Kabza, Alexander;

    2016-01-01

    in an average cell voltage deviation of 21 mV. Test parameters simulating different stack applications are summarized. The stack demonstrated comparable average cell voltage of 0.63 V for stationary and portable conditions. For automotive conditions, the voltage increased to 0.69 V, mainly caused by higher...

  6. 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.

  7. Design and High Power Testing of 52.809 MHz RF Cavities for Slip Stacking in the Fermilab Recycler

    CERN Document Server

    Madrak, R

    2014-01-01

    For NOvA and future experiments requiring high intensity proton beams, Fermilab is in the process of upgrading the existing accelerator complex for increased proton production. One such improvement is to reduce the Main Injector cycle time, by performing slip stacking, previously done in the Main Injector, in the now repurposed Recycler Ring. Recycler slip stacking requires two new RF cavities operating at slightly different frequencies (df = 1260Hz). These are copper, coaxial, quarter wave cavities with R/Q =13 ohms. They operate at a peak gap voltage of 150 kV with 150 kW peak drive power (60% duty factor), and are resonant at 52.809 MHz with a 10 kHz tuning range. Two have been completed and installed. The design, high power test results, and status of the cavities are presented.

  8. Stabilized efficiency of stacked a-Si solar cell; Sekisogata a-Si taiyo denchi no anteika koritsu

    Energy Technology Data Exchange (ETDEWEB)

    Takahisa, K.; Kojima, T.; Nakamura, K.; Koyanagi, T.; Yanagisawa, T. [Electrotechnical Laboratory, Tsukuba (Japan)

    1997-11-25

    Different types of tests combining light and temperature were carried out in a laboratory on predicting long-term performance of stacked amorphous silicon solar cells. Cell terminals were left open, xenon was used as an irradiation light source, and cell temperature was controlled within {+-} 2 degC of the setting. The result of the experiment may be summarized as follows: with regard to the deterioration characteristics, the speed in which the efficiency changes reached a maximum within 10 hours, and thereafter the change has slowed down gradually in the case of temperature at 50 degC; in the case of 25 degC, the maximization is reached between 500 and 1000 hours; the stabilization efficiency turns out to be a pessimistic value according to the saturated value derived from an experimental expression, hence the value would have to be expressed by specifying cell temperatures, light intensities and elapsed time; the minimum value of seasonal variation may be estimated at about 85% as a pessimistic value; for recovery characteristics, the saturated value for the recovery tends to become lower as the lower the value immediately before the recovery; and if the light intensity is varied, the deterioration characteristic shifts to that at an individual light intensity. 4 refs., 11 figs., 2 tabs.

  9. 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.

  10. 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.

  11. Performance evaluation of a stack cooling system using CO{sub 2} air conditioner in fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Chul; Won, Jong Phil [Thermal Management Research Center, Korea Automotive Technology Institute, Chungnam 330-912 (Korea); Park, Yong Sun; Lim, Tae Won [Corporate Research and Development Division, Hyundai-Kia Motors, Gyeonggi 449-912 (Korea); Kim, Min Soo [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)

    2009-01-15

    A relation between the heat release from a fuel cell stack and an air conditioning system's performance was investigated. The air conditioning system installed in a fuel cell vehicle can be used for stack cooling when additional stack heat release is required over a fixed radiator capacity during high vehicle power generation. This study investigated the performance of a stack cooling system using CO{sub 2} air conditioner at various operating conditions. Also, the heat releasing effectiveness and mutual interference were analyzed and compared with those for the conventional radiator cooling system with/without cabin cooling. When the radiator coolant inlet temperature and flow rate were 65 C and 80 L/min, respectively, for the outdoor air inlet speed of 5 m/s, the heat release of the stack cooling system with the aid of CO{sub 2} air conditioner increased up to 36% more than that of the conventional radiator cooling system with cabin cooling. Furthermore, this increased by 7% versus the case without cabin cooling. (author)

  12. Effect of elastic network of ceramic fillers on thermal cycle stability of a solid oxide fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Ho; Kim, Hyoungchul; Kim, Sung Moon; Noh, Tae-Wook; Jung, Hwa-Young; Lim, Hyun-Yup; Jung, Hun-Gi; Son, Ji-Won; Kim, Hae-Ryoung; Kim, Byung-Kook; Je, Hae-June; Lee, Hae-Weon [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Lee, Jae-Chun [Department of Materials Science and Engineering, Myungji University, Yongin, Gyunggi (Korea, Republic of); Song, Huesup [Division of Advanced Materials Engineering, Kongju National University, Chonan, Chungnam (Korea, Republic of)

    2012-04-15

    Glass-based seals for planar solid-oxide fuel-cell (SOFC) stacks are open to uncontrolled deformation and mechanical damages, limiting both sealing integrity and stack reliability, particularly in thermal cycle operations. If the glass-based seals work like an elastomer-based compressive seal, SOFC stacks may survive unprecedented numbers of thermal cycles. A novel composite sealing gasket is successfully developed to mimic the unique features of the elastomer-based compressive seal by controlling the composition and packing behavior of binary ceramic fillers. A single-cell SOFC stack undergoes more than 100 thermal cycles with little performance loss, during which the sealing integrity is lost/recovered repeatedly upon cooling and reheating, corresponding to unloading/loading of the elastomer-based compressive seal. The thermal-cycle responses of the SOFC stack are explained in sequence by the concurrent events of elastic deformation/recovery of ceramic filler network and corresponding redistribution of sealing glass. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Fault Localization Method by Partitioning Memory Using Memory Map and the Stack for Automotive ECU Software Testing

    Directory of Open Access Journals (Sweden)

    Kwanhyo Kim

    2016-09-01

    Full Text Available Recently, the usage of the automotive Electronic Control Unit (ECU and its software in cars is increasing. Therefore, as the functional complexity of such software increases, so does the likelihood of software-related faults. Therefore, it is important to ensure the reliability of ECU software in order to ensure automobile safety. For this reason, systematic testing methods are required that can guarantee software quality. However, it is difficult to locate a fault during testing with the current ECU development system because a tester performs the black-box testing using a Hardware-in-the-Loop (HiL simulator. Consequently, developers consume a large amount of money and time for debugging because they perform debugging without any information about the location of the fault. In this paper, we propose a method for localizing the fault utilizing memory information during black-box testing. This is likely to be of use to developers who debug automotive software. In order to observe whether symbols stored in the memory have been updated, the memory is partitioned by a memory map and the stack, thus the fault candidate region is reduced. A memory map method has the advantage of being able to finely partition the memory, and the stack method can partition the memory without a memory map. We validated these methods by applying these to HiL testing of the ECU for a body control system. The preliminary results indicate that a memory map and the stack reduce the possible fault locations to 22% and 19% of the updated memory, respectively.

  14. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  15. 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.

  16. STEM Tomography Imaging of Hypertrophied Golgi Stacks in Mucilage-Secreting Cells.

    Science.gov (United States)

    Kang, Byung-Ho

    2016-01-01

    Because of the weak penetrating power of electrons, the signal-to-noise ratio of a transmission electron micrograph (TEM) worsens as section thickness increases. This problem is alleviated by the use of the scanning transmission electron microscopy (STEM). Tomography analyses using STEM of thick sections from yeast and mammalian cells are of higher quality than are bright-field (BF) images. In this study, we compared regular BF tomograms and STEM tomograms from 500-nm thick sections from hypertrophied Golgi stacks of alfalfa root cap cells. Due to their thickness and intense heavy metal staining, BF tomograms of the thick sections suffer from poor contrast and high noise levels. We were able to mitigate these drawbacks by using STEM tomography. When we performed STEM tomography of densely stained chloroplasts of Arabidopsis cotyledon, we observed similar improvements relative to BF tomograms. A longer time is required to collect a STEM tilt series than similar BF TEM images, and dynamic autofocusing required for STEM imaging often fails at high tilt angles. Despite these limitations, STEM tomography is a powerful method for analyzing structures of large or dense organelles of plant cells.

  17. Enhanced water removal in a fuel cell stack by droplet atomization using structural and acoustic excitation

    Science.gov (United States)

    Palan, Vikrant; Shepard, W. Steve

    This work examines new methods for enhancing product water removal in fuel cell stacks. Vibration and acoustic based methods are proposed to atomize condensed water droplets in the channels of a bipolar plate or on a membrane electrode assembly (MEA). The vibration levels required to atomize water droplets of different sizes are first examined using two different approaches: (1) exciting the droplet at the same energy level required to form that droplet; and (2) by using a method called 'vibration induced droplet atomization', or VIDA. It is shown analytically that a 2 mm radius droplet resting on a bipolar-like plate can be atomized by inducing acceleration levels as low as 250 g at a certain frequency. By modeling the direct structural excitation of a simplified bipolar plate using a realistic source, the response levels that can be achieved are then compared with those required levels. Furthermore, a two-cell fuel cell finite element model and a boundary element model of the MEA were developed to demonstrate that the acceleration levels required for droplet atomization may be achieved in both the bipolar plate as well as the MEA through proper choice of excitation frequency and source strength.

  18. Enhanced water removal in a fuel cell stack by droplet atomization using structural and acoustic excitation

    Energy Technology Data Exchange (ETDEWEB)

    Palan, Vikrant; Shepard, W. Steve [Department of Mechanical Engineering, The University of Alabama, 290 Hardaway Hall, Box 870276, Tuscaloosa, AL 35487 (United States)

    2006-09-22

    This work examines new methods for enhancing product water removal in fuel cell stacks. Vibration and acoustic based methods are proposed to atomize condensed water droplets in the channels of a bipolar plate or on a membrane electrode assembly (MEA). The vibration levels required to atomize water droplets of different sizes are first examined using two different approaches: (1) exciting the droplet at the same energy level required to form that droplet; and (2) by using a method called 'vibration induced droplet atomization', or VIDA. It is shown analytically that a 2mm radius droplet resting on a bipolar-like plate can be atomized by inducing acceleration levels as low as 250g at a certain frequency. By modeling the direct structural excitation of a simplified bipolar plate using a realistic source, the response levels that can be achieved are then compared with those required levels. Furthermore, a two-cell fuel cell finite element model and a boundary element model of the MEA were developed to demonstrate that the acceleration levels required for droplet atomization may be achieved in both the bipolar plate as well as the MEA through proper choice of excitation frequency and source strength. (author)

  19. Layer-by-layer graphene/TCNQ stacked films as conducting anodes for organic solar cells.

    Science.gov (United States)

    Hsu, Chang-Lung; Lin, Cheng-Te; Huang, Jen-Hsien; Chu, Chih-Wei; Wei, Kung-Hwa; Li, Lain-Jong

    2012-06-26

    Large-area graphene grown by chemical vapor deposition (CVD) is a promising candidate for transparent conducting electrode applications in flexible optoelectronic devices such as light-emitting diodes or organic solar cells. However, the power conversion efficiency (PCE) of the polymer photovoltaic devices using a pristine CVD graphene anode is still not appealing due to its much lower conductivity than that of conventional indium tin oxide. We report a layer-by-layer molecular doping process on graphene for forming sandwiched graphene/tetracyanoquinodimethane (TCNQ)/graphene stacked films for polymer solar cell anodes, where the TCNQ molecules (as p-dopants) were securely embedded between two graphene layers. Poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM) bulk heterojunction polymer solar cells based on these multilayered graphene/TCNQ anodes are fabricated and characterized. The P3HT/PCBM device with an anode structure composed of two TCNQ layers sandwiched by three CVD graphene layers shows optimum PCE (∼2.58%), which makes the proposed anode film quite attractive for next-generation flexible devices demanding high conductivity and transparency.

  20. 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;

    2014-01-01

    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...

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

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    2017-01-01

    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...

  2. Cryogenic testing of by-pass diode stacks for the superconducting magnets of the Large Hadron Collider at CERN

    CERN Document Server

    Della Corte, A; Hagedorn, Dietrich; Turtu, S; Basile, G L; Catitti, A; Chiarelli, S; Di Ferdinando, E; Taddia, G; Talli, M; Verdini, L; Viola, R

    2002-01-01

    A dedicated facility prepared by ENEA (Italian Agency for Energy and Environment) for the cryogenic testing of by-pass diodes for the protection of the CERN Large Hadron Collider main magnets will be described. This experimental activity is in the frame of a contract awarded to OCEM, an Italian firm active in the field of electronic devices and power supplies, in collaboration with ENEA, for the manufacture and testing of all the diode stacks. In particular, CERN requests the measurement of the reverse and forward voltage diode characteristics at 300 K and 77 K, and endurance test cycles at liquid helium temperature. The experimental set-up at ENEA and data acquisition system developed for the scope will be described and the test results reported. (3 refs).

  3. Experimental analysis of dynamic characteristics on the PEM fuel cell stack by using Taguchi approach with neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wei-Lung [Department of Vehicle Engineering, Army Academy, No. 113, Sec.4, Chun-San E. Rd., Chun-Li 320 (China); Wu, Sheng-Ju; Shiah, Sheau-Wen [Department of Power Vehicle and Systems Engineering, Chung Cheng Institute of Technology, National Defense University, No. 190, Sanyuan 1st St., Tashi, Taoyuan 335 (China)

    2010-10-15

    This study determines the optimum operating parameters for a proton exchange membrane fuel cell (PEMFC) stack to obtain small variation and maximum electric power output using a robust parameter design (RPD). The operating parameters examined experimentally are operating temperatures, operating pressures, anode/cathode humidification temperatures, and reactant flow rates. First, the dynamic Taguchi method is used to obtain the maximum and stable power density against the different current densities, which are regarded as the systemic inputs considered a signal factor. The relationship between control factors and responses in the PEMFC stack is determined using a neural network. The discrete parameter levels in the dynamic Taguchi method can be divided into desired levels to acquire real optimum operating parameters. Based on these investigations, the PEMFC stack is operated at the current densities of 0.4-0.8 A/cm{sup 2}. Since the voltage shift is quite small (roughly 0.73-0.83 V for each single cell), the efficiency would be higher. In the range of operation, the operating pressure, the cathode humidification temperature and the interactions between operating temperature and operating pressure significantly impact PEMFC stack performance. As the operating pressure increasing, the increments of the electric power decrease, and power stability is enhanced because the variation in responses is reduced. (author)

  4. 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

    2016-03-01

    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.

  5. 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

    The work presented in this paper examines the use of pure hydrogen fuelled high temperature polymer electrolyte membrane (HTPEM) fuel cell stacks in an electrical car, charging a Li-ion battery pack. The car is equipped with two branches of two series coupled 1 kW fuel cell stacks which...... are 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...... losses related to these components and their added system complexity. The new car battery pack consists of 23 Li-ion battery cells and the charging and discharging are monitored by a battery management system (BMS) which ensures safe operating conditions for the batteries. The direct connection...

  6. Four-Terminal Mechanically Stacked GaAs/Si Tandem Solar Cells

    OpenAIRE

    Hassan, S.

    2015-01-01

    This study investigates a four-terminal mechanically stacked double junction photovoltaic device based on GaAs as a top subcell and Si as a bottom subcell. Unlike two terminal monolithically series connected double junction photovoltaics, four-terminal mechanically stacked devices benefit from the ability to choose a combination of materials that are not constrained to lattice matching condition. GaAs top subcell is the best sensitive to visible light and Si bottom subcell is chosen to be gro...

  7. 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.

  8. Review of the micro-tubular solid oxide fuel cell. Part I. Stack design issues and research activities

    Science.gov (United States)

    Lawlor, V.; Griesser, S.; Buchinger, G.; Olabi, A. G.; Cordiner, S.; Meissner, D.

    Fuel cells are devices that convert chemical energy in hydrogen enriched fuels into electricity electrochemically. Micro-tubular solid oxide fuel cells (MT-SOFCs), the type pioneered by K. Kendall in the early 1990s, are a variety of SOFCs that are on the scale of millimetres compared to their much larger SOFC relatives that are typically on the scale of tens of centimetres. The main advantage of the MT-SOFC, over its larger predecessor, is that it is smaller in size and is more suitable for rapid start up. This may allow the SOFC to be used in devices such as auxiliary power units, automotive power supplies, mobile electricity generators and battery re-chargers. The following paper is Part I of a two part series. Part I will introduce the reader to the MT-SOFC stack and its applications, indicating who is researching what in this field and also specifically investigate the design issues related to multi-cell reactor systems called stacks. Part II will review in detail the combinations of materials and methods used to produce the electrodes and electrolytes of MT-SOFC's. Also the role of modelling and validation techniques used in the design and improvement of the electrodes and electrolytes will be investigated. A broad range of scientific and engineering disciplines are involved in a stack design. Scientific and engineering content has been discussed in the areas of thermal-self-sustainability and efficiency, sealing technologies, manifold design, electrical connections and cell performance optimisation.

  9. Solid-State Fault Current Limiter Development : Design and Testing Update of a 15kV SSCL Power Stack

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Ram Adapa; Mr. Dante Piccone

    2012-04-30

    ABSTRACT The Solid-State Fault Current Limiter (SSCL) is a promising technology that can be applied to utility power delivery systems to address the problem of increasing fault currents associated with load growth. As demand continues to grow, more power is added to utility system either by increasing generator capacity or by adding distributed generators, resulting in higher available fault currents, often beyond the capabilities of the present infrastructure. The SSCL is power-electronics based equipment designed to work with the present utility system to address this problem. The SSCL monitors the line current and dynamically inserts additional impedance into the line in the event of a fault being detected. The SSCL is based on a modular design and can be configured for 5kV through 69kV systems at nominal current ratings of 1000A to 4000A. Results and Findings This report provides the final test results on the development of 15kV class SSCL single phase power stack. The scope of work included the design of the modular standard building block sub-assemblies, the design and manufacture of the power stack and the testing of the power stack for the key functional tests of continuous current capability and fault current limiting action. Challenges and Objectives Solid-State Current Limiter technology impacts a wide spectrum of utility engineering and operating personnel. It addresses the problems associated with load growth both at Transmission and Distribution class networks. The design concept is pioneering in terms of developing the most efficient and compact power electronics equipment for utility use. The initial test results of the standard building blocks are promising. The independent laboratory tests of the power stack are promising. However the complete 3 phase system needs rigorous testing for performance and reliability. Applications, Values, and Use The SSCL is an intelligent power-electronics device which is modular in design and can provide current

  10. Fast stack activation procedure and effective long-term storage for high-performance polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Yang, Seung Yong; Seo, Dong-Jun; Kim, Myeong-Ri; Seo, Min Ho; Hwang, Sun-Mi; Jung, Yong-Min; Kim, Beom-Jun; Yoon, Young-Gi; Han, Byungchan; Kim, Tae-Young

    2016-10-01

    Time-saving stack activation and effective long-term storage are one of most important issues that must be resolved for the commercialization of polymer electrolyte membrane fuel cell (PEMFC). Herein, we developed the cost-effective stack activation method to finish the whole activation within 30 min and the long-term storage method by using humidified N2 without any significant decrease in cell's performance for 30 days. Specifically, the pre-activation step with the direct injection of DI water into the stack and storage at 65 or 80 °C for 2 h increases the distinctive phase separation between the hydrophobic and hydrophilic regions in Nafion membrane, which significantly reduces the total activation time within 30 min. Additionally, the long-term storage with humidified N2 has no effect on the Pt oxidation and drying of Nafion membrane for 30 days due to its exergonic reaction in the cell. As a result, the high water content in Nafion membrane and the decrease of Pt oxidation are the critical factors that have a strong influence on the activation and long-term storage for high-performance PEMFC.

  11. 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.

  12. 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

    and 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......Fuel cell systems running on pure hydrogen can efficiently produce electricity and heat for various applications, stationary and mobile. Storage volume can be problematic for stationary fuel cell systems with high run-time demands, but it is especially a challenge when dealing with mobile...

  13. Identification of critical parameters for PEMFC stack performance characterization and control strategies for reliable and comparable stack benchmarking

    DEFF Research Database (Denmark)

    Mitzel, Jens; Gülzow, Erich; Kabza, Alexander;

    2016-01-01

    for the control strategy are summarized. This ensures result comparability as well as stable test conditions. E.g., the stack temperature fluctuation is minimized to about 1 °C. The experiments demonstrate that reactants pressures differ up to 12 kPa if pressure control positions are varied, resulting...... in an average cell voltage deviation of 21 mV. Test parameters simulating different stack applications are summarized. The stack demonstrated comparable average cell voltage of 0.63 V for stationary and portable conditions. For automotive conditions, the voltage increased to 0.69 V, mainly caused by higher...

  14. Adding large EM stack support

    KAUST Repository

    Holst, Glendon

    2016-12-01

    Serial section electron microscopy (SSEM) image stacks generated using high throughput microscopy techniques are an integral tool for investigating brain connectivity and cell morphology. FIB or 3View scanning electron microscopes easily generate gigabytes of data. In order to produce analyzable 3D dataset from the imaged volumes, efficient and reliable image segmentation is crucial. Classical manual approaches to segmentation are time consuming and labour intensive. Semiautomatic seeded watershed segmentation algorithms, such as those implemented by ilastik image processing software, are a very powerful alternative, substantially speeding up segmentation times. We have used ilastik effectively for small EM stacks – on a laptop, no less; however, ilastik was unable to carve the large EM stacks we needed to segment because its memory requirements grew too large – even for the biggest workstations we had available. For this reason, we refactored the carving module of ilastik to scale it up to large EM stacks on large workstations, and tested its efficiency. We modified the carving module, building on existing blockwise processing functionality to process data in manageable chunks that can fit within RAM (main memory). We review this refactoring work, highlighting the software architecture, design choices, modifications, and issues encountered.

  15. 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.

  16. 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.

  17. Antiparietal cell antibody test

    Science.gov (United States)

    APCA; Anti-gastric parietal cell antibody; Atrophic gastritis - anti-gastric parietal cell antibody; Gastric ulcer - anti-gastric parietal cell antibody; Pernicious anemia - anti-gastric parietal cell antibody; ...

  18. Four-Terminal Mechanically Stacked GaAs/Si Tandem Solar Cells

    CERN Document Server

    Hassan, S

    2015-01-01

    This study investigates a four-terminal mechanically stacked double junction photovoltaic device based on GaAs as a top subcell and Si as a bottom subcell. Unlike two terminal monolithically series connected double junction photovoltaics, four-terminal mechanically stacked devices benefit from the ability to choose a combination of materials that are not constrained to lattice matching condition. GaAs top subcell is the best sensitive to visible light and Si bottom subcell is chosen to be grown on Si substrate which has relatively low cost. Moreover, the carriers generated by each subcell is collected independently to the external circuit. This electrical isolation of the subcells ensures higher efficiency, where no current matching nor tunnel junctions and related losses exist. A conversion efficiency of the device with a thickness in the order of 10 microns surpassed 27%.

  19. Measurements of the effects of thermal contact resistance on steady state heat transfer in phosphoric-acid fuel cell stack

    Science.gov (United States)

    Abdul-Aziz, Ali; Alkasab, Kalil A.

    1991-01-01

    The influence of the thermal contact resistance on the heat transfer between the electrode plates, and the cooling system plate in a phosphoric-acid fuel-cell stack was experimentally investigated. The investigation was conducted using a set-up that simulates the operating conditions prevailing in a phosphoric acid fuel-cell stack. The fuel-cell cooling system utilized three types of coolants, water, engine oil, and air, to remove excess heat generated in the cell electrode and to maintain a reasonably uniform temperature distribution in the electrode plate. The thermal contact resistance was measured as a function of pressure at the interface between the electrode plate and the cooling system plate. The interface pressure range was from 0 kPa to 3448 kPa, while the Reynolds number for the cooling limits varied from 15 to 79 for oil, 1165 to 6165 for water, and 700 to 6864 for air. Results showed that increasing the interface pressure resulted in a higher heat transfer coefficient.

  20. Optimization of manifold design for 1 kW-class flat-tubular solid oxide fuel cell stack operating on reformed natural gas

    Science.gov (United States)

    Rashid, Kashif; Dong, Sang Keun; Khan, Rashid Ali; Park, Seung Hwan

    2016-09-01

    This study focuses on optimizing the manifold design for a 1 kW-class flat-tubular solid oxide fuel cell stack by performing extensive three-dimensional numerical simulations on numerous manifold designs. The stack flow uniformity and the standard flow deviation indexes are implemented to characterize the flow distributions in the stack and among the channels of FT-SOFC's, respectively. The results of the CFD calculations demonstrate that the remodeled manifold without diffuser inlets and 6 mm diffuser front is the best among investigated designs with uniformity index of 0.996 and maximum standard flow deviation of 0.423%. To understand the effect of manifold design on the performance of stack, both generic and developed manifold designs are investigated by applying electrochemical and internal reforming reactions modeling. The simulation results of the stack with generic manifold are validated using experimental data and then validated models are adopted to simulate the stack with the developed manifold design. The results reveal that the stack with developed manifold design achieves more uniform distribution of species, temperature, and current density with comparatively lower system pressure drop. In addition, the results also showed ∼8% increase in the maximum output power due to the implementation of uniform fuel velocity distributions in the cells.

  1. Hybridizing grey wolf optimization with differential evolution for global optimization and test scheduling for 3D stacked SoC

    Institute of Scientific and Technical Information of China (English)

    Aijun Zhu; Chuanpei Xu; Zhi Li; Jun Wu; Zhenbing Liu

    2015-01-01

    A new meta-heuristic method is proposed to enhance current meta-heuristic methods for global optimization and test scheduling for three-dimensional (3D) stacked system-on-chip (SoC) by hybridizing grey wolf optimization with differential evo-lution (HGWO). Because basic grey wolf optimization (GWO) is easy to fal into stagnation when it carries out the operation of at-tacking prey, and differential evolution (DE) is integrated into GWO to update the previous best position of grey wolf Alpha, Beta and Delta, in order to force GWO to jump out of the stagnation with DE’s strong searching ability. The proposed algorithm can accele-rate the convergence speed of GWO and improve its performance. Twenty-three wel-known benchmark functions and an NP hard problem of test scheduling for 3D SoC are employed to verify the performance of the proposed algorithm. Experimental results show the superior performance of the proposed algorithm for exploiting the optimum and it has advantages in terms of exploration.

  2. Terrestrial photovoltaic cell process testing

    Science.gov (United States)

    Burger, D. R.

    1985-01-01

    The paper examines critical test parameters, criteria for selecting appropriate tests, and the use of statistical controls and test patterns to enhance PV-cell process test results. The coverage of critical test parameters is evaluated by examining available test methods and then screening these methods by considering the ability to measure those critical parameters which are most affected by the generic process, the cost of the test equipment and test performance, and the feasibility for process testing.

  3. Mesoporous TiO2 Bragg Stack Templated by Graft Copolymer for Dye-sensitized Solar Cells

    OpenAIRE

    Jung Tae Park; Won Seok Chi; Sang Jin Kim; Daeyeon Lee; Jong Hak Kim

    2014-01-01

    Organized mesoporous TiO2 Bragg stacks (om-TiO2 BS) consisting of alternating high and low refractive index organized mesoporous TiO2 (om-TiO2) films were prepared to enhance dye loading, light harvesting, electron transport, and electrolyte pore-infiltration in dye-sensitized solar cells (DSSCs). The om-TiO2 films were synthesized via a sol-gel reaction using amphiphilic graft copolymers consisting of poly(vinyl chloride) backbones and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-...

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

    OpenAIRE

    Liu, Hong; Li, Peiwen; Juarez-Robles, Daniel; Wang, Kai; Hernandez-Guerrero, Abel

    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 ...

  5. Experimental study and comparison of various designs of gas flow fields to PEM fuel cells and cell stack performance

    OpenAIRE

    Hong eLiu; Peiwen eLi; Daniel eJuarez-Robles; Kai eWang; Abel eHernandez-Guerrero

    2014-01-01

    In this study, a significant number of experimental tests to 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 all have an effective membrane area of 23.5 cm2. The results showed that the serpentine flow channel design is still favorable, giving the b...

  6. 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.

  7. Degradation effects in polymer electrolyte membrane fuel cell stacks by sub-zero operation-An in situ and ex situ analysis

    Science.gov (United States)

    Alink, R.; Gerteisen, D.; Oszcipok, M.

    The effect of low temperatures down to -40 °C on the performance and component properties of a polymer electrolyte membrane (PEM) fuel cell stack was investigated. By analyzing the temperature-dependent high-frequency resistance, the mechanism of ice formation within the stack was investigated during freeze/thaw (F/T) cycling while the stack was not operating and during a cold start-up. A step-like change in conductivity at 0 °C indicates that the membranes are dehydrated at sub-zero temperatures due to a change in capillary pressure at the interface membrane/catalyst. Furthermore, it was found that the stack shows little degradation when it is dried out before cooling down. Freezing in a wet state and additional cold start-ups resulted in performance degradation which was mainly attributed to changes in wetting properties. Ex situ environmental scanning electron microscope (ESEM) investigations showed distinct damage and increasing porosity of the electrode in the wet frozen stack, which was most likely the reason for the change in wetting properties. Inductively coupled plasma (ICP) mass spectroscopy showed distinct concentrations of platinum in the exhaust gas of the dry cycled stack, but no additional platinum was found when the stack was cycled in a wet state. Additional ex situ F/T investigations of gas diffusion layers (GDLs) and membrane electrode assemblies (MEAs) within an ESEM confirmed the results, found by in situ investigations of the fuel cell stacks. Serious detachment of electrode material was found without the compressive force applied to an assembly.

  8. Testing pollen of single and stacked insect-resistant Bt-maize on in vitro reared honey bee larvae.

    Science.gov (United States)

    Hendriksma, Harmen P; Härtel, Stephan; Steffan-Dewenter, Ingolf

    2011-01-01

    The ecologically and economic important honey bee (Apis mellifera) is a key non-target arthropod species in environmental risk assessment (ERA) of genetically modified (GM) crops. Honey bee larvae are directly exposed to transgenic products by the consumption of GM pollen. But most ERA studies only consider responses of adult bees, although Bt-proteins primarily affect the larval phases of target organisms. We adopted an in vitro larvae rearing system, to assess lethal and sublethal effects of Bt-pollen consumption in a standardized eco-toxicological bioassay. The effects of pollen from two Bt-maize cultivars, one expressing a single and the other a total of three Bt-proteins, on the survival and prepupae weight of honey bee larvae were analyzed. The control treatments included pollen from three non-transgenic maize varieties and of Heliconia rostrata. Three days old larvae were fed the realistic exposure dose of 2 mg pollen within the semi-artificial diet. The larvae were monitored over 120 h, until the prepupal stage, where larvae terminate feeding and growing. Neither single nor stacked Bt-maize pollen showed an adverse effect on larval survival and the prepupal weight. In contrast, feeding of H. rostrata pollen caused significant toxic effects. The results of this study indicate that pollen of the tested Bt-varieties does not harm the development of in vitro reared A. mellifera larvae. To sustain the ecosystem service of pollination, Bt-impact on A. mellifera should always be a crucial part of regulatory biosafety assessments. We suggest that our approach of feeding GM pollen on in vitro reared honey bee larvae is well suited of becoming a standard bioassay in regulatory risk assessments schemes of GM crops.

  9. Testing pollen of single and stacked insect-resistant Bt-maize on in vitro reared honey bee larvae.

    Directory of Open Access Journals (Sweden)

    Harmen P Hendriksma

    Full Text Available The ecologically and economic important honey bee (Apis mellifera is a key non-target arthropod species in environmental risk assessment (ERA of genetically modified (GM crops. Honey bee larvae are directly exposed to transgenic products by the consumption of GM pollen. But most ERA studies only consider responses of adult bees, although Bt-proteins primarily affect the larval phases of target organisms. We adopted an in vitro larvae rearing system, to assess lethal and sublethal effects of Bt-pollen consumption in a standardized eco-toxicological bioassay. The effects of pollen from two Bt-maize cultivars, one expressing a single and the other a total of three Bt-proteins, on the survival and prepupae weight of honey bee larvae were analyzed. The control treatments included pollen from three non-transgenic maize varieties and of Heliconia rostrata. Three days old larvae were fed the realistic exposure dose of 2 mg pollen within the semi-artificial diet. The larvae were monitored over 120 h, until the prepupal stage, where larvae terminate feeding and growing. Neither single nor stacked Bt-maize pollen showed an adverse effect on larval survival and the prepupal weight. In contrast, feeding of H. rostrata pollen caused significant toxic effects. The results of this study indicate that pollen of the tested Bt-varieties does not harm the development of in vitro reared A. mellifera larvae. To sustain the ecosystem service of pollination, Bt-impact on A. mellifera should always be a crucial part of regulatory biosafety assessments. We suggest that our approach of feeding GM pollen on in vitro reared honey bee larvae is well suited of becoming a standard bioassay in regulatory risk assessments schemes of GM crops.

  10. A ten liter stacked microbial desalination cell packed with mixed ion-exchange resins for secondary effluent desalination.

    Science.gov (United States)

    Zuo, Kuichang; Cai, Jiaxiang; Liang, Shuai; Wu, Shijia; Zhang, Changyong; Liang, Peng; Huang, Xia

    2014-08-19

    The architecture and performance of microbial desalination cell (MDC) have been significantly improved in the past few years. However, the application of MDC is still limited in a scope of small-scale (milliliter) reactors and high-salinity-water desalination. In this study, a large-scale (>10 L) stacked MDC packed with mixed ion-exchange resins was fabricated and operated in the batch mode with a salt concentration of 0.5 g/L NaCl, a typical level of domestic wastewater. With circulation flow rate of 80 mL/min, the stacked resin-packed MDC (SR-MDC) achieved a desalination efficiency of 95.8% and a final effluent concentration of 0.02 g/L in 12 h, which is comparable with the effluent quality of reverse osmosis in terms of salinity. Moreover, the SR-MDC kept a stable desalination performance (>93%) when concentrate volume decreased from 2.4 to 0.1 L (diluate/concentrate volume ratio increased from 1:1 to 1:0.04), where only 0.875 L of nonfresh water was consumed to desalinate 1 L of saline water. In addition, the SR-MDC achieved a considerable desalination rate (95.4 mg/h), suggesting a promising application for secondary effluent desalination through deriving biochemical electricity from wastewater.

  11. Efficiency Enhancement of Nanotextured Black Silicon Solar Cells Using Al2O3/TiO2 Dual-Layer Passivation Stack Prepared by Atomic Layer Deposition.

    Science.gov (United States)

    Wang, Wei-Cheng; Tsai, Meng-Chen; Yang, Jason; Hsu, Chuck; Chen, Miin-Jang

    2015-05-20

    In this study, efficient nanotextured black silicon (NBSi) solar cells composed of silicon nanowire arrays and an Al2O3/TiO2 dual-layer passivation stack on the n(+) emitter were fabricated. The highly conformal Al2O3 and TiO2 surface passivation layers were deposited on the high-aspect-ratio surface of the NBSi wafers using atomic layer deposition. Instead of the single Al2O3 passivation layer with a negative oxide charge density, the Al2O3/TiO2 dual-layer passivation stack treated with forming gas annealing provides a high positive oxide charge density and a low interfacial state density, which are essential for the effective field-effect and chemical passivation of the n(+) emitter. In addition, the Al2O3/TiO2 dual-layer passivation stack suppresses the total reflectance over a broad range of wavelengths (400-1000 nm). Therefore, with the Al2O3/TiO2 dual-layer passivation stack, the short-circuit current density and efficiency of the NBSi solar cell were increased by 11% and 20%, respectively. In conclusion, a high efficiency of 18.5% was achieved with the NBSi solar cells by using the n(+)-emitter/p-base structure passivated with the Al2O3/TiO2 stack.

  12. Enhanced degradation of azo dye by a stacked microbial fuel cell-biofilm electrode reactor coupled system.

    Science.gov (United States)

    Cao, Xian; Wang, Hui; Li, Xiao-Qi; Fang, Zhou; Li, Xian-Ning

    2017-03-01

    In this study, a microbial fuel cell (MFC)-biofilm electrode reactor (BER) coupled system was established for degradation of the azo dye Reactive Brilliant Red X-3B. In this system, electrical energy generated by the MFC degrades the azo dye in the BER without the need for an external power supply, and the effluent from the BER was used as the inflow for the MFC, with further degradation. The results indicated that the X-3B removal efficiency was 29.87% higher using this coupled system than in a control group. Moreover, a method was developed to prevent voltage reversal in stacked MFCs. Current was the key factor influencing removal efficiency in the BER. The X-3B degradation pathway and the types and transfer processes of intermediate products were further explored in our system coupled with gas chromatography-mass spectrometry.

  13. Using CrAIN Multilayer Coatings to Improve Oxidation Resistance of Steel Interconnects for Solid Oxide Fuel Cell Stacks

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Richard J.; Tripp, C.; Knospe, Anders; Ramana, C. V.; Gorokhovsky, Vladimir I.; Shutthanandan, V.; Gelles, David S.

    2004-06-01

    The requirements of low cost and high-tempurature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigatedt he performance of steel plates with multilayer coatings consisting of CrN for electrical conductivity and CrAIN for oxidation resistance. The coatings were deposited usin large area filterd arc deposition technolgy, and subsequently annealed in air for up to 25 hours at 800 degrees celsius. The composition, structer and morphology of the coated plates were characterized using RBS, nuclear reaction analysis, AFM and TEM techniques. By altering the architecture of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitute. Electrical resistance was measured at room temperature.

  14. Using CrAlN multilayer coatings to improve oxidation resistance of steel interconnects for solid oxide fuel cell stacks

    Science.gov (United States)

    Smith, R. J.; Tripp, C.; Knospe, A.; Ramana, C. V.; Kayani, A.; Gorokhovsky, Vladimir; Shutthanandan, V.; Gelles, D. S.

    2004-06-01

    The requirements of low-cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. The performance of steel plates with multilayer coatings, consisting of CrN for electrical conductivity and CrAlN for oxidation resistance, was investigated. The coatings were deposited using large area filtered arc deposition technology, and subsequently annealed in air for up to 25 hours at 800 °C. The composition, structure, and morphology of the coated plates were characterized using Rutherford backscattering, nuclear reaction analysis, atomic force microscopy, and transmission electron microscopy techniques. By altering the architecture of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitude. Electrical resistance was measured at room temperature.

  15. Proposal for the award of a contract for the supply, assembly and testing in liquid helium of bypass-diode stacks for the LHC magnets

    CERN Document Server

    1999-01-01

    This document concerns the award of a contract for the supply, assembly and testing in liquid helium of 1250 dipole and 400 quadrupole bypass-diode stacks. Following a market survey carried out among 61 firms in eleven Member States, a call for tenders (IT-2648/LHC/LHC) was sent on 7 July 1999 to thirteen firms and one consortium consisting of two firms, in six Member States. By the closing date, CERN had received eleven tenders. The Finance Committee is invited to approve the negotiation of a contract with the firm O.C.E.M. (IT), the lowest bidder after realignment, for the supply, assembly and testing in liquid helium of 1250 dipole and 400 quadrupole bypass-diode stacks for a total amount of 6 591 369 Swiss francs, subject to revision, with an option for the supply, assembly and testing in liquid helium of up to 125 dipole and 40 quadrupole bypass-diode stacks, for a total amount of 620 990 Swiss francs, subject to revision, bringing the overall total amount to a maximum of 7 212 359 Swiss francs, subject ...

  16. In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor.

    Science.gov (United States)

    Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

    2016-10-18

    In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery.

  17. In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor

    Directory of Open Access Journals (Sweden)

    Chi-Yuan Lee

    2016-10-01

    Full Text Available In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack, the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery.

  18. 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.

  19. 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;

    2014-01-01

    by infiltration with BaO or La0.85Sr0.15MnO3+δ. The cell stacks were tested in an atmosphere of 1000 ppm NO or NO2 + 10% O2 in Ar with 10% O2 in Ar as reference, and in the temperature range of 250 to 500 °C. The cell stacks were investigated electrochemically with cyclic voltammetry and polarization...

  20. Optimisation on the two-layer stack gamma detectors of CsI(Tl) coupled with a pin photodiode for non-destructive testing.

    Science.gov (United States)

    Bai, Jin Hyoung; Whang, Joo Ho

    2011-07-01

    This paper proposed the two-layer stack scintillator-coupled photodiode detector to improve the measurement accuracy of the gamma-ray scanning. Both MCNPX and DETECT97 code were used to design the detector. The two manufactured two-layer stack gamma detectors were used to measure the density profile of the distillation column of the radiographic non-intrusive process diagnostic area. To compare the measurement accuracy of the density profile through the non-destructive transmission test, the relative error of the four fluids used for the process diagnostics was analysed. To summarise the measurement results with regard to the relative error of the NaI(Tl) detector and the manufactured detector by material as well as the total relative error, the total relative error of the NaI(Tl) detector was about 15.7 %, whereas that of the two-layer stack CsI(Tl) with photodiode detectors were about 5 %. This paper confirmed that the measurement accuracy of the detector proposed was improved by about three times as compared with the NaI(Tl) detector mostly used for non-destructive testing.

  1. 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

    Fuel cells are getting growing interest in both backup systems and electric vehicles. Although these systems are characterized by periods of standby, they must be able to start at any instant in the shortest possible time. However, the membranes of which proton exchange membrane fuel cells are made...... way for estimating the hydration status and the temperature of its membrane before the system is started up. A summarizing table with the complete characterization of the fuel cell stack is included in this article....

  2. Method of operating a molten carbonate fuel cell, a fuel cell, a fuel cell stack and an apparatus provided therewith

    NARCIS (Netherlands)

    Hemmes, K.; Dijkema, G.P.J.

    1998-01-01

    A method of operating a molten carbonate fuel cell having an anode and a cathode and in between a matrix comprising molten carbonate. Carbon dioxide is introduced into the matrix at a distance from the cathode. This greatly reduces the cathode's deterioration and in the system design increases the c

  3. Multi-scale analysis of the diffusion barrier layer of gadolinia-doped ceria in a solid oxide fuel cell operated in a stack for 3000 h

    Science.gov (United States)

    Morales, M.; Miguel-Pérez, V.; Tarancón, A.; Slodczyk, A.; Torrell, M.; Ballesteros, B.; Ouweltjes, J. P.; Bassat, J. M.; Montinaro, D.; Morata, A.

    2017-03-01

    The state-of-the-art materials for SOFCs are yttria-stabilized zirconia as electrolyte and lanthanum strontium cobalt ferrite as cathode. However, the formation of insulating phases between them requires the use of diffusion barriers, typically made of gadolinia doped ceria. The study of the stability of this layer during the fabrication and in operando is currently one of the major goals of the SOFC industry. In this work, the cation inter-diffusion at the cathode/barrier layer/electrolyte region is analysed for an anode-supported cell industrially fabricated by conventional techniques, assembled in a short-stack and tested under real operation conditions for 3000 h. A comprehensive study of this cell, and an equivalent non-operated one, is performed in order to understand the inter-diffusion mechanisms with possible effects on the final performance. The analyses evidence that the cation diffusion is occurring during the fabrication process. Despite the significant diffusion of Ce,Gd, Zr, Y and Sr cations, the formation of typically reported CGO-YSZ solid solution is not observed while the presence of isolated grains of SrZrO3 is proved. All in all, this study presents new insights into the stability of the typically employed diffusion barriers for solid oxide cells that will guide future strategies to improve their performance and durability.

  4. PEM fuel stack dynamics, constraining supervisory control for propulsion systems in fuel cell busses

    NARCIS (Netherlands)

    Tazelaar, Edwin; Veenhuizen, Bram; Middelman, E.; Bosch, P. van den

    2013-01-01

    The last decade several prototypes of fuel cell busses have been presented [1, 2]. A closer observation of these prototypes shows remarkable differences in both sizing and control of the system components. Some busses are essentially electric vehicles with a relative low power fuel cell system used

  5. 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,

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

    DEFF Research Database (Denmark)

    Harthøj, Anders

    Solid oxide fuel Cell (SOFC) technology can with a high efficiency produce environmentally clean electricity by converting the chemical energy in a fuel to electrical energy. SOFC systems have a high operation temperature, approx. 600-850 °C. Advantages compared to other types of fuel cells...... and the gaseous chromium species can poison the cathode. Interconnect coatings are a potential solution to reduce the high temperature corrosion issues. An effective coating must consist of a material with the right properties but equally important is the process used for its deposition. It must enable coatings...

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

    DEFF Research Database (Denmark)

    Nguyen, Gia; Sahlin, Simon Lennart; Andreasen, Søren Juhl;

    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 art...

  8. 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

    Electric energy can be harvested from aquatic sediments by utilizing microbialfuelcells (MFCs). A main challenge of this application is the limited voltage output. In this study, an innovative self-stackedsubmersible MFC (SSMFC) was developed to improve the voltage generation from lakesediments....... The SSMFC successfully produced a maximum power density of 294 mW/m2 and had an open circuit voltage (OCV) of 1.12 V. However, voltage reversal was observed in one cell at high current density. Investigation on the cause for voltage reversal revealed that voltage reversal was occurring only when low...... 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...

  9. Probing Temperature Inside Planar SOFC Short Stack, Modules, and Stack Series

    Science.gov (United States)

    Yu, Rong; Guan, Wanbing; Zhou, Xiao-Dong

    2016-11-01

    Probing temperature inside a solid oxide fuel cell (SOFC) stack lies at the heart of the development of high-performance and stable SOFC systems. In this article, we report our recent work on the direct measurements of the temperature in three types of SOFC systems: a 5-cell short stack, a 30-cell stack module, and a stack series consisting of two 30-cell stack modules. The dependence of temperature on the gas flow rate and current density was studied under a current sweep or steady-state operation. During the current sweep, the temperature inside the 5-cell stack decreased with increasing current, while it increased significantly at the bottom and top of the 30-cell stack. During a steady-state operation, the temperature of the 5-cell stack was stable while it was increased in the 30-cell stack. In the stack series, the maximum temperature gradient reached 190°C when the gas was not preheated. If the gas was preheated and the temperature gradient was reduced to 23°C in the stack series with the presence of a preheating gas and segmented temperature control, this resulted in a low degradation rate.

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

    OpenAIRE

    Chih-Hung Tsai; Yu-Tang Tsai; Tsung-Wei Huang; Sui-Ying Hsu; Yan-Fang Chen; Yuan-Hsuan Jhang; Lun Hsieh; Chung-Chih Wu; Yen-Shan Chen

    2013-01-01

    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 o...

  11. Linearity Testing of Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Pinegar, S.; Nalley, D.; Emery, K.

    2006-01-01

    Photovoltaic devices are rated in terms of their power output or efficiency with respect to a specific spectrum, total irradiance, and temperature. In order to rate photovoltaic devices, a reference detector whose response is linear with total irradiance is needed. This procedure documents a procedure to determine if a detector is linear over the irradiance range of interest. Testing the short circuit current versus the total irradiance is done by illuminating a reference cell candidate with two lamps that are fitted with programmable filter wheels. The purpose is to reject nonlinear samples as determined by national and international standards from being used as primary reference cells. A calibrated linear reference cell tested by the two lamp method yields a linear result.

  12. 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.

  13. 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)

  14. Optimization of Al2O3/SiNx stacked antireflection structures for N-type surfacepassivated crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    Wu Dawei; Jia Rui; Ding Wuchang; Chen Chen; Wu Deqi; Chen Wei; Li Haofeng; Yue Huihui; Liu Xinyu

    2011-01-01

    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.

  15. Molten carbonate fuel cell product development test. Final report, September 30, 1992--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This report summarizes the work performed for manufacturing and demonstrating the performance of its 250-kW molten carbonate fuel cell (MCFC) stack in an integrated system at the Naval Air Station Miramar (NAS Miramar) located in San Diego, California. The stack constructed for the demonstration test at the NAS Miramar consisted of 250 cells. It was manufactured using M-C Power`s patented Internally Manifolded Heat Exchanger (IMHEX{reg_sign}) stack design. The demonstration test at NAS Miramar was designed to operate the 250-kW MCFC stack in a cogeneration mode. This test represented the first attempt to thermally integrate an MCFC stack in a cogeneration system. The test was started on January 10, 1997, and voluntarily terminated on May 12, 1997, after 2,350 hours of operation at temperatures above 1,100 F and at a pressure of three atmospheres. It produced 160 MWh of d.c. power and 346,000 lbs of 110 psig steam for export during 1,566 hours of on-load operations. The test demonstrated a d.c. power output of 206 kW. Most of the balance of the plant (BOP) equipment operated satisfactorily. However, the off-the-shelf automotive turbocharger used for supplying air to the plant failed on numerous occasions and the hot gas blower developed seal leakage problems which impacted continuous plant operations. Overall the demonstration test at NAS Miramar was successful in demonstrating many critical features of the IMHEX technology. Lessons learned from this test will be very useful for improving designs and operations for future MCFC power plants.

  16. Diffractive stacks of metamaterial lattices with a complex unit cell: Self-consistent long-range bianisotropic interactions in experiment and theory

    Science.gov (United States)

    Kwadrin, Andrej; Koenderink, A. Femius

    2014-01-01

    Metasurfaces and metamaterials promise arbitrary rerouting of light using two-dimensional (2D) planar arrangements of electric and magnetic scatterers, respectively, 3D stacks built out of such 2D planes. An important problem is how to self-consistently model the response of these systems in a manner that retains dipole intuition yet does full justice to the self-consistent multiple scattering via near-field and far-field retarded interactions. We set up such a general model for metamaterial lattices of complex 2D unit cells of poly-atomic basis as well as allowing for stacking in a third dimension. In particular, each scatterer is quantified by a magnetoelectric polarizability tensor and Ewald lattice summation deals with all near-field and long-range retarded electric, magnetic, and magnetoelectric couplings self-consistently. We show in theory and experiment that grating diffraction orders of dilute split ring lattices with complex unit cells show a background-free signature of magnetic dipole response. For denser lattices experiment and theory show that complex unit cells can reduce the apparent effect of bianisotropy, i.e., the strong oblique-incidence handed response that was reported for simple split ring lattices. Finally, the method is applied to calculate transmission of finite stacks of lattices. Thereby our simple methodology allows us to trace the emergence of effective material constants when building a 3D metamaterial layer by layer, as well as facilitating the design of metasurfaces.

  17. Performance comparison of portable direct methanol fuel cell mini-stacks based on a low-cost fluorine-free polymer electrolyte and Nafion membrane

    Energy Technology Data Exchange (ETDEWEB)

    Baglio, V., E-mail: baglio@itae.cnr.i [CNR-ITAE, Via Salita S. Lucia sopra Contesse 5, 98126 Messina (Italy); Stassi, A.; Modica, E.; Antonucci, V.; Arico, A.S. [CNR-ITAE, Via Salita S. Lucia sopra Contesse 5, 98126 Messina (Italy); Caracino, P.; Ballabio, O.; Colombo, M.; Kopnin, E. [Pirelli Labs, Viale Sarca, 222, 20126 Milano (Italy)

    2010-08-01

    A low-cost fluorine-free proton conducting polymer electrolyte was investigated for application in direct methanol fuel cell (DMFC) mini-stacks. The membrane consisted of a sulfonated polystyrene grafted onto a polyethylene backbone. DMFC operating conditions specifically addressing portable applications, i.e. passive mode, air breathing, high methanol concentration, room temperature, were selected. The device consisted of a passive DMFC monopolar three-cell stack. Two designs for flow-fields/current collectors based on open-flow or grid-like geometry were investigated. An optimization of the mini-stack structure was necessary to improve utilization of the fluorine-free membrane. Titanium-grid current collectors with proper mechanical stiffness allowed a significant increase of the performance by reducing contact resistance even in the case of significant swelling. A single cell maximum power density of about 18 mW cm{sup -2} was achieved with the fluorine-free membrane at room temperature under passive mode. As a comparison, the performance obtained with Nafion 117 membrane and Ti grids was 31 mW cm{sup -2}. Despite the lower performance, the fluorine-free membrane showed good characteristics for application in portable DMFCs especially with regard to the perspectives of significant cost reduction.

  18. 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

    2014-12-01

    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.

  19. Study on stacking sequence on the flexural properties of basalt/carbon/epoxy hybrid composites using test and finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. H.; Lee, J. I.; Rhee, K. Y. [Kyung Hee University, Yongin (Korea, Republic of); Choi, C. R. [ELSOLTEC Inc., Yongin (Korea, Republic of)

    2015-05-15

    Basalt fiber is widely used in various industries and several studies have been carried out to understand the mechanical behavior of basalt fiber reinforced composites. However, few studies have been made to specifically investigate the mechanical properties of basalt/carbon hybrid composites. In this study, the effect of stacking sequence on the flexural properties of carbon/basalt/epoxy hybrid composites was investigated in order to verify the reliability of this composite model. Two types of carbon/basalt/epoxy hybrid composites with a sandwich form were fabricated: basalt skin-carbon core (BSCC) composites and carbon skin-basalt core (CSBC) composites. After fabrication flexural tests and finite element method (FEM) were conducted. FEM results of flexural analysis are compared with experimental results. A FEA analysis model has been successfully developed in order to predict flexural behavior of basalt/carbon/epoxy hybrid composites. The simulation using the FEA model produces a similar flexural strength to that obtained from the experiment. Therefore, the developed FEA model in general will be highly useful for the prediction of stacking sequence of basalt/carbon/ epoxy hybrid composites for several industrial applications.

  20. Iodine Absorption Cells Purity Testing

    Directory of Open Access Journals (Sweden)

    Jan Hrabina

    2017-01-01

    Full Text Available This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches.

  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...... was applied, and the relationship between module of impedance and relative humidity was found. The results showed that measuring the impedance of a fuel cell during standby can be a viable way for estimating the hydration status of its membrane....

  2. 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.

  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. Method of converting a carbon-comprising material, method of operating a fuel cell stack, and a fuel cell

    NARCIS (Netherlands)

    Hemmes, K.

    1999-01-01

    The invention relates to a method of converting a carbon-comprising material at elevated temperature in the presence of a molecule that comprises at least one oxygen atom. According to the invention the carbon-comprising material in the fuel cell is converted substantially to carbon monoxide in a re

  5. Cell buffer with built-in test

    Science.gov (United States)

    Ott, William E. (Inventor)

    2004-01-01

    A cell buffer with built-in testing mechanism is provided. The cell buffer provides the ability to measure voltage provided by a power cell. The testing mechanism provides the ability to test whether the cell buffer is functioning properly and thus providing an accurate voltage measurement. The testing mechanism includes a test signal-provider to provide a test signal to the cell buffer. During normal operation, the test signal is disabled and the cell buffer operates normally. During testing, the test signal is enabled and changes the output of the cell buffer in a defined way. The change in the cell buffer output can then be monitored to determine if the cell buffer is functioning correctly. Specifically, if the voltage output of the cell buffer changes in a way that corresponds to the provided test signal, then the functioning of the cell buffer is confirmed. If the voltage output of the cell buffer does not change correctly, then the cell buffer is known not to be operating correctly. Thus, the built in testing mechanism provides the ability to quickly and accurately determine if the cell buffer is operating correctly. Furthermore, the testing mechanism provides this functionality without requiring excessive device size and complexity.

  6. Ultra-dark graphene stack metamaterials

    Science.gov (United States)

    Chugh, Sunny; Man, Mengren; Chen, Zhihong; Webb, Kevin J.

    2015-02-01

    We present a fabrication method to achieve a graphene stack metamaterial, a periodic array of unit cells composed of graphene and a thin insulating spacer, that allows accumulation of the strong absorption from individual graphene sheets and low reflectivity from the stack. The complex sheet conductivity of graphene from experimental data models the measured power transmitted as a function of wavelength and number of periods in the stack. Simulated results based on the extracted graphene complex sheet conductivity for thicker stacks suggest that the graphene stack reflectivity and the per-unit-length absorption can be controlled to exceed the performance of competing light absorbers. Furthermore, the electrical properties of graphene coupled with the stack absorption characteristics provide for applications in optoelectronic devices.

  7. 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...

  8. 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.

  9. 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.

  10. Vector Fields and Flows on Differentiable Stacks

    DEFF Research Database (Denmark)

    A. Hepworth, Richard

    2009-01-01

    This paper introduces the notions of vector field and flow on a general differentiable stack. Our main theorem states that the flow of a vector field on a compact proper differentiable stack exists and is unique up to a uniquely determined 2-cell. This extends the usual result on the existence...... of vector fields....

  11. Stacking technology for a space constrained microsystem

    DEFF Research Database (Denmark)

    Heschel, Matthias; Kuhmann, Jochen Friedrich; Bouwstra, Siebe;

    1998-01-01

    In this paper we present a stacking technology for an integrated packaging of an intelligent transducer which is formed by a micromachined silicon transducer and an integrated circuit chip. Transducer and circuitry are stacked on top of each other with an intermediate chip in between. The bonding...... of the transducer and the intermediate chip is done by flip chip solder bump bonding. The bonding between the above two-layer stack and the circuit chip is done by conductive adhesive bonding combined with gold studs. We demonstrate the stacking technologies on passive test chips rather than real devices and report...... on technological details...

  12. Detailed experimental characterization of a reformate fuelled PEM stack

    DEFF Research Database (Denmark)

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

    2006-01-01

    Increasing attention is given to fuel cells for micro combined heat and power systems for local households. Currently, mainly three different types of fuel cells are commercially competitive: SOFC, low- and high-temperature PEM fuel cells. In the present paper the Low Temperature PEM technology...... 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...

  13. Test and approval center for fuel cell and hydrogen technologies: Phase I. Initiation. Final report; Test- og godkendelsescenter for braendselscelle- og brintteknologier. Fase 1. Opstart. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, A. [Technical Univ. of Denmark. DTU Energy Conversion, DTU Risoe Campus, Roskilde (Denmark)

    2012-09-15

    The aim of the present project was to initialize a Test and Approval Center for Fuel Cell and Hydrogen Technologies at the sites of the project partners Risoe DTU (Fuel Cells and Solid State Chemistry Division), and DGC (work package 1). The project furthermore included start-up of first activities with focus on the development of accelerated life-time tests of fuel cell systems, preparations for standardization of these methods, and advising in relation to certification and approval of fuel cell systems (work package 2). The main achievements of the project were: Work package 1: 1) A large national and international network was established comprising of important commercial players, research institutions, and other test centers; 2) The test center is known in large part of the international Fuel Cell and Hydrogen community due to substantial efforts in 'marketing'; 3) New national and international projects have been successfully applied for, with significant roles of the test center, which secure the further establishment and development of the center. Work package 2: 1) Testing equipment was installed and commissioned at DTU (Risoe Campus); 2) A comprehensive survey among international players regarding activities on accelerated SOFC testing was carried out; 3) A test procedure for 'compressed' testing of SOFC in relation to {mu} CHP application was developed and used for one-cell stack and 50-cell-stack testing; 4) Guidelines for Danish authority handling were formulated. (Author)

  14. Non-Flow-Through Fuel Cell System Test Results and Demonstration on the SCARAB Rover

    Science.gov (United States)

    Scheidegger, Brianne, T.; Burke, Kenneth A.; Jakupca, Ian J.

    2012-01-01

    This paper describes the results of the demonstration of a non-flow-through PEM fuel cell as part of a power system on the SCARAB rover. A 16-cell non-flow-through fuel cell stack from Infinity Fuel Cell and Hydrogen, Inc. was incorporated into a power system designed to act as a range extender by providing power to the rover s hotel loads. This work represents the first attempt at a ground demonstration of this new technology aboard a mobile test platform. Development and demonstration were supported by the Office of the Chief Technologist s Space Power Systems Project and the Advanced Exploration System Modular Power Systems Project.

  15. 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.

  16. Quantitative analysis of serotonin secreted by human embryonic stem cells-derived serotonergic neurons via pH-mediated online stacking-CE-ESI-MRM.

    Science.gov (United States)

    Zhong, Xuefei; Hao, Ling; Lu, Jianfeng; Ye, Hui; Zhang, Su-Chun; Li, Lingjun

    2016-04-01

    A CE-ESI-MRM-based assay was developed for targeted analysis of serotonin released by human embryonic stem cells-derived serotonergic neurons in a chemically defined environment. A discontinuous electrolyte system was optimized for pH-mediated online stacking of serotonin. Combining with a liquid-liquid extraction procedure, LOD of serotonin in the Krebs'-Ringer's solution by CE-ESI-MS/MS on a 3D ion trap MS was0.15 ng/mL. The quantitative results confirmed the serotonergic identity of the in vitro developed neurons and the capacity of these neurons to release serotonin in response to stimulus.

  17. 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.

  18. 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.

  19. 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.

  20. Development of amorphous silicon-germanium-alloys for stacked solar cells; Entwicklung von amorphen Silizium-Germanium-Legierungen fuer den Einsatz in Stapelsolarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Lundszien, D.

    2001-01-01

    To obtain high efficiency silicon based thin film solar cells, the concept of stacked solar cells is routinely used. The use of component cells with different optical bandgaps provides a better utilization of the solar spectrum. In a stacked cell structure, a high quality narrow bandgap material is needed for the active layer of the bottom cell. Amorphous silicon-germanium-alloys (a-SiGe:H) have been successfully employed because of their tunable optical bandgap E{sub G} between 1.8 eV (a-Si:H) and 1.1 eV (a-Ge:H). Considerable effort has been put into the development of a-SiGe:H. Still, with increasing Ge content, the material shows a characteristic deterioration of its electronic properties, like an exponential increase of the defect density, thus counteracting the gain in absorption obtained for higher Ge contents. It is the defect density which has the dominant influence on carrier transport and cell efficiency by affecting the mobility lifetime product and the electric field in the devices. The performance of a-SiGe:H pin solar cells with a wide range of Ge contents i.e. a wide range of optical band gaps (E{sub G}=1.3 to 1.6 eV) are compared. It is demonstrated how the deterioration of the material properties can be overcome by careful adjustment of the device design and the use of highly reflective ZnO/Ag back contacts. (orig.)

  1. Al2O3/SiON stack layers for effective surface passivation and anti-reflection of high efficiency n-type c-Si solar cells

    Science.gov (United States)

    Thi Thanh Nguyen, Huong; Balaji, Nagarajan; Park, Cheolmin; Triet, Nguyen Minh; Le, Anh Huy Tuan; Lee, Seunghwan; Jeon, Minhan; Oh, Donhyun; Dao, Vinh Ai; Yi, Junsin

    2017-02-01

    Excellent surface passivation and anti-reflection properties of double-stack layers is a prerequisite for high efficiency of n-type c-Si solar cells. The high positive fixed charge (Q f) density of N-rich hydrogenated amorphous silicon nitride (a-SiNx:H) films plays a poor role in boron emitter passivation. The more the refractive index ( n ) of a-SiNx:H is decreased, the more the positive Q f of a-SiNx:H is increased. Hydrogenated amorphous silicon oxynitride (SiON) films possess the properties of amorphous silicon oxide (a-SiOx) and a-SiNx:H with variable n and less positive Q f compared with a-SiNx:H. In this study, we investigated the passivation and anti-reflection properties of Al2O3/SiON stacks. Initially, a SiON layer was deposited by plasma enhanced chemical vapor deposition with variable n and its chemical composition was analyzed by Fourier transform infrared spectroscopy. Then, the SiON layer was deposited as a capping layer on a 10 nm thick Al2O3 layer, and the electrical and optical properties were analyzed. The SiON capping layer with n = 1.47 and a thickness of 70 nm resulted in an interface trap density of 4.74 = 1010 cm-2 eV-1 and Q f of -2.59 = 1012 cm-2 with a substantial improvement in lifetime of 1.52 ms after industrial firing. The incorporation of an Al2O3/SiON stack on the front side of the n-type solar cells results in an energy conversion efficiency of 18.34% compared to the one with Al2O3/a-SiNx:H showing 17.55% efficiency. The short circuit current density and open circuit voltage increase by up to 0.83 mA cm-2 and 12 mV, respectively, compared to the Al2O3/a-SiNx:H stack on the front side of the n-type solar cells due to the good anti-reflection and front side surface passivation.

  2. Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Zu-Po Yang

    2016-08-01

    Full Text Available Titanium oxide (TiO2 films and TiO2/SiNx stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO2 film by atomic layer deposition, has a surface recombination velocity as low as 14.93 cm/s at the injection level of 1.0 × 1015 cm−3. However, the performance of silicon surface passivation of the deposited TiO2 film declines as its thickness increases, probably because of the stress effects, phase transformation, atomic hydrogen and thermal stability of amorphous TiO2 films. For the characterization of 66-nm-thick TiO2 film, the results of transmission electron microscopy show that the anatase TiO2 crystallinity forms close to the surface of the Si. Secondary ion mass spectrometry shows the atomic hydrogen at the interface of TiO2 and Si which serves for chemical passivation. The crystal size of anatase TiO2 and the homogeneity of TiO2 film can be deduced by the measurements of Raman spectroscopy and spectroscopic ellipsometry, respectively. For the passivating contacts of solar cells, in addition, a stack composed of 8-nm-thick TiO2 film and a plasma-enhanced chemical-vapor-deposited 72-nm-thick SiNx layer has been investigated. From the results of the measurement of the reflectivity and effective carrier lifetime, TiO2/SiNx stacks on Si wafers perform with low reflectivity and some degree of surface passivation for the Si wafer.

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

    OpenAIRE

    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 sele...

  4. On flow maldistribution in PEMFC stacks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. [Xi' an Jiaotong Univ., Xi' an (China). State Key Laboratory of Multiphase Flow in Power Engineering; Lund Univ., Lund (Sweden). Dept. of Energy Sciences, Heat Transfer Div.; Yan, J. [Xi' an Jiaotong Univ., Xi' an (China). State Key Laboratory of Multiphase Flow in Power Engineering; Yuan, J.; Sunden, B. [Lund Univ., Lund (Sweden). Dept. of Energy Sciences, Heat Transfer Div.

    2010-07-01

    Fuel cell devices have technical and environmental advantages over thermal power systems. The advantages include high performance characteristics, reliability, durability and low emissions. In order to increase the voltage in a single PEMFC for practical operations, many single cells are serially connected to fabricate a fuel cell stack. This study focused on the flow maldistribution at stack level. The flow maldistribution in unit cells may significantly influence the fuel cell stack performance, including the uniformity of current density and the voltage. Of the few studies on flow maldistribution in PEMFC stacks, the results are unsystematic, scattered, and even contradictory. As such, it is necessary to review and summarize previous studies to gain insight into methods to reduce the flow maldistribution in PEMFC stacks. This paper therefore reviewed existing literature concerning flow maldistributions in PEMFC stacks and discussed the effects of the arrangement of flow configurations, design parameters and operating conditions on the flow maldistribution. Some suggestions were outlined to reduce the flow maldistribution in PEMFC stacks. 34 refs., 1 tab., 13 figs.

  5. Voltage Reversal Behavior during Stacking Microbial Fuel Cells in Series%串联微生物燃料电池的电压反转行为

    Institute of Scientific and Technical Information of China (English)

    陈禧; 朱能武; 李小虎

    2011-01-01

    Stacking microbial fuel cell (MFC) in series is an effective approach to provide higher voltage. However, voltage reversal (VR) adversely affects performance of the stacked MFCs. In this paper, diodes are introduced into three stacked MFCs so as to investigate the VR behavior and offer a diodes-based explanation of the VR. Results show that VR occurs in the different stacked MFCs systems. VR of the stacked MFCs with forward diodes happens in a similar pattern as that without diodes. However, it only happens at the end of a cycle. This can be analyzed that the resistance of the diodes consume a part of the flowing electrons and the speed of potential changes of the electrodes slows down. In the stacked MFCs with reverse diodes, VR happens in the unit MFC with reverse diodes at the cathode end only and the voltages of each unit MFC approximately equal their open circuit voltages. It implies that the imbalanced consumption of electrons in unit MFCs and the potential changes of specific electrode directly result in VR. An effective approach to avoid VR in stacked MFCs is to provide enough substrate for each unit MFC and allow consecutive electrons flowing in the circuit.%微生物燃料电池是一种处理废水同时产电的具有广阔应用前景的新型水处理技术,其串联是产生更高电压的有效方法之一,但是会产生电压反转现象降低串联微生物燃料电池的性能.文章将二极管引入串联微生物燃料电池中以考察电压反转的行为.结果表明,不同的串联微生物燃料电池中均会发生电压反转.串联正向二极管的微生物燃料电池的电压反转行为与没有串联二极管的微生物燃料电池类似,但是前者仪仪发生在一个周期的结束阶段.这可能是因为电子流经二极管时被其消耗,从而减缓了电极电势的变化速率.当串联反向二极管时,电压反转发生在仅阴极端连接二极管的单体微生物燃料电池上,而且各单体电池的电压

  6. The effect of applied control strategy on the current-voltage correlation of a solid oxide fuel cell stack during dynamic operation

    Directory of Open Access Journals (Sweden)

    Szmyd Janusz S.

    2014-09-01

    Full Text Available This paper discusses the transient characteristics of the planar type SOFC cell stack, of which the standard output is 300 W. The transient response of the voltage to the manipulation of an electric current was investigated. The effects of the response and of the operating condition determined by the operating temperature of the stack were studied by mapping a current-voltage (I-V correlation. The current-based fuel control (CBFC was adopted for keeping the fuel utilization factor at constant while the value of the electric current was ramped at the constant rate. The present experimental study shows that the transient characteristics of the cell voltage are determined by primarily the operating temperature caused by the manipulation of the current. Particularly, the slope of the I-V curve and the overshoot found on the voltage was remarkably influenced by the operating temperature. The different values of the fuel utilization factor influence the height of the settled voltages. The CBFC has significance in determining the slope of the I-V characteristic, but the different values ofthe fuel utilization factor does not affect the slope as the operating temperature does. The CBFC essentially does not alter the amplitude of the overshoot on the voltage response, since this is dominated by the operating temperature and its change is caused by manipulating the current.

  7. Deploying OpenStack

    CERN Document Server

    Pepple, Ken

    2011-01-01

    OpenStack was created with the audacious goal of being the ubiquitous software choice for building public and private cloud infrastructures. In just over a year, it's become the most talked-about project in open source. This concise book introduces OpenStack's general design and primary software components in detail, and shows you how to start using it to build cloud infrastructures. If you're a developer, technologist, or system administrator familiar with cloud offerings such as Rackspace Cloud or Amazon Web Services, Deploying OpenStack shows you how to obtain and deploy OpenStack softwar

  8. Variable conformation of GAP junctions linking bone cells: a transmission electron microscopic study of linear, stacked linear, curvilinear, oval, and annular junctions.

    Science.gov (United States)

    Shapiro, F

    1997-10-01

    There is a marked variability in the conformation of bone cell gap junctions in newborn murine cortical bone as defined by transmission electron microscopy (TEM). Studies were done in newborn BALB/c mouse and Sprague-Dawley rat femurs and tibias. Femoral and tibial cortices were dissected into 1 mm3 fragments and prepared in standardized fashion using modified Karnovsky fixation, 7.5% EDTA decalcification, 1% osmium tetroxide-sym collidine buffer with 1% lanthanum nitrate postfixation, Epon resin, 60 nm sections, lead citrate/uranyl acetate staining, and examination at 60 kV. Previous TEM descriptions of bone junctions have, with rare exceptions, noted only isolated linear or mildly curvilinear structures. In this study we noted gap junctional shapes on thin-section TEM preparations of osteoblasts and osteocytes to be extremely variable and complex encompassing linear, curvilinear, stacked linear, oval, and annular conformations. Multiple observations revealed linear gap junctions linking surface osteoblast cell bodies; linear, curvilinear, stacked linear, and oval junctions linking osteoblast processes in osteoid; linear and curvilinear junctions where cell processes joined with osteocyte cell bodies and each of the five conformations linking osteocyte processes within canaliculi. The annular junctions were found within osteoblast and osteocyte cytoplasm and in osteocyte cell processes within canaliculi. The annular junctions are intracellular, degenerating structures which appear as ultrastructural markers of gap junction involution. The more complex shapes reported here must be considered in (1) interpreting quantitative studies using freeze-fracture replicas, thin sections, and confocal microscopy immunolabeled junction connexin-43 components and (2) assessing gap junction biogenesis and turnover. 3-D reconstruction of bone junctions will enhance our understanding of these complex conformations.

  9. The role of Golgi reassembly and stacking protein 65 phosphorylation in H2O2-induced cell death and Golgi morphological changes.

    Science.gov (United States)

    Ji, Guang; Zhang, Weiwei; Quan, Moyuan; Chen, Yang; Qu, Hui; Hu, Zhiping

    2016-12-01

    This study aimed to investigate the effects of H2O2-induced oxidative stress on cell viability and survival, as well as changes in the distribution of Golgi apparatus and in the level of Golgi reassembly and stacking protein 65 (GRASP65). Cell viability of cultured N2a cells treated with H2O2 was measured by the MTT assay. Apoptosis was measured by flow cytometry analyses. Cells labeled by indirect immunofluorescence were observed under confocal microscope to detect any Golgi morphological alterations; electron microscopy of Golgi apparatus was also done. Expression of GRASP65 and phospho-GRASP65 was examined by immunoblotting. H2O2 treatment reduced the cell viability and raised the cell mortality of N2a cells in a time-dependent manner. Notable changes were only observed in the distribution and morphology of Golgi apparatus at 6 h after H2O2 treatment. The expression of GRASP65 showed no significant changes at different time points; the phosphorylated GRASP65 level was significantly increased after H2O2 treatment, peaked at 3 h, and finally dropped at 6 h. Taken together, GRASP65 phosphorylation may have a critical role in inducing cell death at the early stage after H2O2 treatment, while its role in H2O2-induced Golgi morphological changes may be complex.

  10. 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

  11. 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.

  12. 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.

  13. Development of a novel portable-size PEMFC short stack with electrodeposited Pt hydrogen diffusion anodes

    Energy Technology Data Exchange (ETDEWEB)

    Alcaide, Francisco; Alvarez, Garbine; Blazquez, Jose Alberto; Miguel, Oscar [Dpto. de Energia, CIDETEC-IK4, P Miramon, 196, 20009 San Sebastian (Spain); Cabot, Pere L. [Laboratori d' Electroquimica de Materials i del Medi Ambient, Dept. Quimica Fisica, Universitat de Barcelona, Marti i Franques, 1-11, 08028 Barcelona (Spain)

    2010-06-15

    This paper presents, for the first time, a five-cell polymer electrolyte membrane fuel cell (PEMFC) short stack with electrodeposited hydrogen diffusion anodes. The anodes were manufactured by means of galvanostatic pulse electrodeposition and the cathodes by air-brushing. Nafion {sup registered} 212 was employed as a solid polymer electrolyte membrane in all cases. The short stack, whose cells had an active geometric area of 14 cm{sup 2}, was assembled and tested under different operating conditions. A peak power of about 11 W was obtained at 50 C and atmospheric pressure using hydrogen and air feed, whereas a smaller value of 8.6 W was obtained from a five-cell short PEMFC stack with conventional hydrogen diffusion anodes under the same operating conditions. The better performance of the cells described in this paper has been assigned to the higher utilization of the platinum in the electrodeposited anodes compared to the conventional ones. (author)

  14. 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

  15. Fuel Cell Stations Automate Processes, Catalyst Testing

    Science.gov (United States)

    2010-01-01

    Glenn Research Center looks for ways to improve fuel cells, which are an important source of power for space missions, as well as the equipment used to test fuel cells. With Small Business Innovation Research (SBIR) awards from Glenn, Lynntech Inc., of College Station, Texas, addressed a major limitation of fuel cell testing equipment. Five years later, the company obtained a patent and provided the equipment to the commercial world. Now offered through TesSol Inc., of Battle Ground, Washington, the technology is used for fuel cell work, catalyst testing, sensor testing, gas blending, and other applications. It can be found at universities, national laboratories, and businesses around the world.

  16. Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

    Science.gov (United States)

    Nakajo, Arata; Mueller, Fabian; Brouwer, Jacob; Van herle, Jan; Favrat, Daniel

    2012-10-01

    The degradation of solid oxide fuel cells (SOFC) depends on stack and system design and operation. A methodology to evaluate synergistically these aspects to achieve the lowest production cost of electricity has not yet been developed. A repeating unit model, with as degradation processes the decrease in ionic conductivity of the electrolyte, metallic interconnect corrosion, anode nickel particles coarsening and cathode chromium contamination, is used to investigate the impact of the operating conditions on the lifetime of an SOFC system. It predicts acceleration of the degradation due to the sequential activation of multiple processes. The requirements for the highest system efficiency at start and at long-term differ. Among the selected degradation processes, those on the cathode side here dominate. Simulations suggest that operation at lower system specific power and higher stack temperature can extend the lifetime by a factor up to 10, because the beneficial decrease in cathode overpotential prevails over the higher release of volatile chromium species, faster metallic interconnect corrosion and higher thermodynamic risks of zirconate formation, for maximum SRU temperature below 1150 K. The counter-flow configuration, combined with the beneficial effect of internal reforming on lowering the parasitic air blower consumption, similarly yields longer lifetime than co-flow.

  17. 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.

  18. Nickel hydrogen battery cell storage matrix test

    Science.gov (United States)

    Wheeler, James R.; Dodson, Gary W.

    1993-01-01

    Test were conducted to evaluate post storage performance of nickel hydrogen cells with various design variables, the most significant being nickel precharge versus hydrogen precharge. Test procedures and results are presented in outline and graphic form.

  19. Stacking for machine learning redshifts applied to SDSS galaxies

    OpenAIRE

    Zitlau, Roman; Hoyle, Ben; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-01-01

    We present an analysis of a general machine learning technique called 'stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We shown how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised...

  20. 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.

  1. Summary Report on Solid-oxide Electrolysis Cell Testing and Development

    Energy Technology Data Exchange (ETDEWEB)

    J.E. O' Brien; X. Zhang; R.C. O' Brien; G.L. Hawkes

    2012-01-01

    Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells (SOECs) for large-scale hydrogen production from steam over a temperature range of 800 to 900 C. From 2003 to 2009, this work was sponsored by the United States Department of Energy Nuclear Hydrogen Initiative, under the Office of Nuclear Energy. Starting in 2010, the high-temperature electrolysis (HTE) research program has been sponsored by the INL Next Generation Nuclear Plant Project. This report provides a summaryof program activities performed in Fiscal Year (FY) 2011 and the first quarter of FY-12, with a focus on small-scale testing and cell development activities. HTE research priorities during this period have included the development and testing of SOEC and stack designs that exhibit high-efficiency initial performance and low, long-term degradation rates. This report includes contributions from INL and five industry partners: Materials and Systems Research, Incorporated (MSRI); Versa Power Systems, Incorporated (VPS); Ceramatec, Incorporated; National Aeronautics and Space Administration - Glenn Research Center (NASA - GRC); and the St. Gobain Advanced Materials Division. These industry partners have developed SOEC cells and stacks for in-house testing in the electrolysis mode and independent testing at INL. Additional fundamental research and post-test physical examinations have been performed at two university partners: Massachusetts Institute of Technology (MIT) and the University of Connecticut. Summaries of these activities and test results are also presented in this report.

  2. 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)....

  3. 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.

  4. Propagation testing multi-cell batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Orendorff, Christopher J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lamb, Joshua [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Steele, Leigh Anna Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Spangler, Scott Wilmer [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-10-01

    Propagation of single point or single cell failures in multi-cell batteries is a significant concern as batteries increase in scale for a variety of civilian and military applications. This report describes the procedure for testing failure propagation along with some representative test results to highlight the potential outcomes for different battery types and designs.

  5. PEM fuel cell testing and diagnosis

    CERN Document Server

    Wu, Jifeng; Zhang, Jiujun

    2013-01-01

    PEM Fuel Cell Testing and Diagnosis covers the recent advances in PEM (proton exchange membrane) fuel cell systems, focusing on instruments and techniques for testing and diagnosis, and the application of diagnostic techniques in practical tests and operation. This book is a unique source of electrochemical techniques for researchers, scientists and engineers working in the area of fuel cells. Proton exchange membrane fuel cells are currently considered the most promising clean energy-converting devices for stationary, transportation, and micro-power applications due to their

  6. Startup, testing, and operation of the Santa Clara 2MW direct carbonate fuel cell demonstration plant

    Energy Technology Data Exchange (ETDEWEB)

    Skok, A.J.; Leo, A.J. [Fuel Cell Engineering Corp., Danbury, CT (United States); O`Shea, T.P. [Santa Clara Demonstration Project, CA (United States)

    1996-12-31

    The Santa Clara Demonstration Project (SCDP) is a collaboration between several utility organizations, Fuel Cell Engineering Corporation (FCE), and the U.S. Dept. Of Energy aimed at the demonstration of Energy Research Corporation`s (ERC) direct carbonate fuel cell (DFC) technology. ERC has been pursuing the development of the DFC for commercialization near the end of this decade, and this project is an integral part of the ERC commercialization effort. The objective of the Santa Clara Demonstration Project is to provide the first full, commercial scale demonstration of this technology. The approach ERC has taken in the commercialization of the DFC is described in detail elsewhere. An aggressive core technology development program is in place which is focused by ongoing interaction with customers and vendors to optimize the design of the commercial power plant. ERC has selected a 2.85 MW power plant unit for initial market entry. Two ERC subsidiaries are supporting the commercialization effort: the Fuel Cell Manufacturing Corporation (FCMC) and the Fuel Cell Engineering Corporation (FCE). FCMC manufactures carbonate stacks and multi-stack modules, currently from its production facility in Torrington, CT. FCE is responsible for power plant design, integration of all subsystems, sales/marketing, and client services. FCE is serving as the prime contractor for the design, construction, and testing of the SCDP Plant. FCMC has manufactured the multi-stack submodules used in the DC power section of the plant. Fluor Daniel Inc. (FDI) served as the architect-engineer subcontractor for the design and construction of the plant and provided support to the design of the multi-stack submodules. FDI is also assisting the ERC companies in commercial power plant design.

  7. Vector Fields and Flows on Differentiable Stacks

    DEFF Research Database (Denmark)

    A. Hepworth, Richard

    2009-01-01

    This paper introduces the notions of vector field and flow on a general differentiable stack. Our main theorem states that the flow of a vector field on a compact proper differentiable stack exists and is unique up to a uniquely determined 2-cell. This extends the usual result on the existence...... and uniqueness of flows on a manifold as well as the author's existing results for orbifolds. It sets the scene for a discussion of Morse Theory on a general proper stack and also paves the way for the categorification of other key aspects of differential geometry such as the tangent bundle and the Lie algebra...

  8. Bipolarly stacked electrolyser for energy and space efficient fabrication of supercapacitor electrodes

    Science.gov (United States)

    Liu, Xiaojuan; Wu, Tao; Dai, Zengxin; Tao, Keran; Shi, Yong; Peng, Chuang; Zhou, Xiaohang; Chen, George Z.

    2016-03-01

    Stacked electrolysers with titanium bipolar plates are constructed for electrodeposition of polypyrrole electrodes for supercapacitors. The cathode side of the bipolar Ti plates are pre-coated with activated carbon. In this new design, half electrolysis occurs which significantly lowers the deposition voltage. The deposited electrodes are tested in a symmetrical unit cell supercapacitor and an asymmetrical supercapacitor stack. Both devices show excellent energy storage performances and the capacitance values are very close to the design value, suggesting a very high current efficiency during the electrodeposition. The electrolyser stack offers multi-fold benefits for preparation of conducting polymer electrodes, i.e. low energy consumption, facile control of the electrode capacitance and simultaneous preparation of a number of identical electrodes. Therefore, the stacked bipolar electrolyser is a technology advance that offers an engineering solution for mass production of electrodeposited conducting polymer electrodes for supercapacitors.

  9. TESTING AND PERFORMANCE ANALYSIS OF NASA 5 CM BY 5 CM BI-SUPPORTED SOLID OXIDE ELECTROLYSIS CELLS OPERATED IN BOTH FUEL CELL AND STEAM ELECTROLYSIS MODES

    Energy Technology Data Exchange (ETDEWEB)

    R. C. O' Brien; J. E. O' Brien; C. M. Stoots; X. Zhang; S. C. Farmer; T. L. Cable; J. A. Setlock

    2011-11-01

    A series of 5 cm by 5 cm bi-supported Solid Oxide Electrolysis Cells (SOEC) were produced by NASA for the Idaho National Laboratory (INL) and tested under the INL High Temperature Steam Electrolysis program. The results from the experimental demonstration of cell operation for both hydrogen production and operation as fuel cells is presented. An overview of the cell technology, test apparatus and performance analysis is also provided. The INL High Temperature Steam Electrolysis laboratory has developed significant test infrastructure in support of single cell and stack performance analyses. An overview of the single cell test apparatus is presented. The test data presented in this paper is representative of a first batch of NASA's prototypic 5 cm by 5 cm SOEC single cells. Clearly a significant relationship between the operational current density and cell degradation rate is evident. While the performance of these cells was lower than anticipated, in-house testing at NASA Glenn has yielded significantly higher performance and lower degradation rates with subsequent production batches of cells. Current post-test microstructure analyses of the cells tested at INL will be published in a future paper. Modification to cell compositions and cell reduction techniques will be altered in the next series of cells to be delivered to INL with the aim to decrease the cell degradation rate while allowing for higher operational current densities to be sustained. Results from the testing of new batches of single cells will be presented in a future paper.

  10. 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.

  11. 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.

  12. Cell-Based Genotoxicity Testing

    Science.gov (United States)

    Reifferscheid, Georg; Buchinger, Sebastian

    Genotoxicity test systems that are based on bacteria display an important role in the detection and assessment of DNA damaging chemicals. They belong to the basic line of test systems due to their easy realization, rapidness, broad applicability, high sensitivity and good reproducibility. Since the development of the Salmonella microsomal mutagenicity assay by Ames and coworkers in the early 1970s, significant development in bacterial genotoxicity assays was achieved and is still a subject matter of research. The basic principle of the mutagenicity assay is a reversion of a growth inhibited bacterial strain, e.g., due to auxotrophy, back to a fast growing phenotype (regain of prototrophy). Deeper knowledge of the ­mutation events allows a mechanistic understanding of the induced DNA-damage by the utilization of base specific tester strains. Collections of such specific tester strains were extended by genetic engineering. Beside the reversion assays, test systems utilizing the bacterial SOS-response were invented. These methods are based on the fusion of various SOS-responsive promoters with a broad variety of reporter genes facilitating numerous methods of signal detection. A very important aspect of genotoxicity testing is the bioactivation of ­xenobiotics to DNA-damaging compounds. Most widely used is the extracellular metabolic activation by making use of rodent liver homogenates. Again, genetic engineering allows the construction of highly sophisticated bacterial tester strains with significantly enhanced sensitivity due to overexpression of enzymes that are involved in the metabolism of xenobiotics. This provides mechanistic insights into the toxification and detoxification pathways of xenobiotics and helps explaining the chemical nature of hazardous substances in unknown mixtures. In summary, beginning with "natural" tester strains the rational design of bacteria led to highly specific and sensitive tools for a rapid, reliable and cost effective

  13. Lugol's test reexamined again: buccal cells.

    Science.gov (United States)

    Jones, Edwin L; Leon, Julie A

    2004-01-01

    Lugol's iodine staining technique was used to examine oral samples from 10 men and 10 women. Examination of saliva samples before and after extraction with water shows that the low levels (49 positive cells and 3,951 negative cells) of glycogen in buccal epithelial cells become even lower after water extraction (0 positive cells and 4,000 negative cells). In addition to the 20 samples used in this paper, 40 oral swabs extracted with water were examined under classroom conditions with much less than 1% of the epithelial cells being positive for glycogen. Furthermore, 119 saliva samples from chewed gauze in sexual assault kits were extracted with water and all of them yielded less than 1% glycogen positive cells. This paper proposes that when more than 1% of the nucleated squamous epithelial cells are glycogen positive with Lugol's test after extraction in water, it is reasonable to eliminate the mouth as a source of these glycogen positive cells.

  14. Temperature control of a PEM fuel cell test bench for experimental MEA assessment

    Energy Technology Data Exchange (ETDEWEB)

    More, J.J.; Puleston, P.F.; Kunusch, C. [LEICI, Departamento de Electrotecnia, Universidad Nacional de La Plata (UNLP), calle 1 esq. 47 s/n, 1900 La Plata (Argentina); Consejo de Investigaciones Cientificas y Tecnicas (CONICET), Av. Rivadavia, N 1917, C1033AAJ, Ciudad Autonoma de Buenos Aires (Argentina); Visintin, A. [Consejo de Investigaciones Cientificas y Tecnicas (CONICET), Av. Rivadavia, N 1917, C1033AAJ, Ciudad Autonoma de Buenos Aires (Argentina); Instituto de Investigaciones Fisico-Quimicas Teoricas y Aplicadas (INIFTA), Diag. 113 y 64 s/n, 1900, La Plata (Argentina)

    2010-06-15

    This paper presents the design, implementation and testing of a temperature control for a laboratory PEM fuel cell stack work bench intended for evaluation of experimental MEAs. The controller design is based on a thermal model of the fuel cell stack developed by the authors. The model is extended to the complete temperature range by considering a nonlinear description of the heating resistances. Its parameters are experimentally adjusted and its accuracy is validated in all the temperature operating range. Then, the temperature control is developed, using a proportional-integral structure with anti-windup features. It is implemented in a PC connected to an ad-hoc equipment of acquisition and control, that drives distributed cycles actuators to energize two heating resistances. The controller proved to be capable of regulating the stack temperature in a wide operating range, while eliminating the ripple typical of ON-OFF actuators. Finally, experimental results of closed loop operation are presented, demonstrating the good performance of the proposed control set up and thermal model. (author)

  15. Transport Studies Enabling Efficiency Optimization of Cost-Competitive Fuel Cell Stacks (aka AURORA: Areal Use and Reactant Optimization at Rated Amperage)

    Energy Technology Data Exchange (ETDEWEB)

    Conti, Amedeo [Nuvera Fuel Cells, Inc., Billerica, MA (United States); Dross, Robert [Nuvera Fuel Cells, Inc., Billerica, MA (United States)

    2013-12-06

    Hydrogen fuel cells are recognized as one of the most viable solutions for mobility in the 21st century; however, there are technical challenges that must be addressed before the technology can become available for mass production. One of the most demanding aspects is the costs of present-day fuel cells which are prohibitively high for the majority of envisioned markets. The fuel cell community recognizes two major drivers to an effective cost reduction: (1) decreasing the noble metals content, and (2) increasing the power density in order to reduce the number of cells needed to achieve a specified power level. To date, the majority of development work aimed at increasing the value metric (i.e. W/mg-Pt) has focused on the reduction of precious metal loadings, and this important work continues. Efforts to increase power density have been limited by two main factors: (1) performance limitations associated with mass transport barriers, and (2) the historical prioritization of efficiency over cost. This program is driven by commercialization imperatives, and challenges both of these factors. The premise of this Program, supported by proprietary cost modeling by Nuvera, is that DOE 2015 cost targets can be met by simultaneously exceeding DOE 2015 targets for Platinum loadings (using materials with less than 0.2 mg-Pt/cm2) and MEA power density (operating at higher than 1.0 Watt/cm2). The approach of this program is to combine Nuvera’s stack technology, which has demonstrated the ability to operate stably at high current densities (> 1.5 A/cm2), with low Platinum loading MEAs developed by Johnson Matthey in order to maximize Pt specific power density and reduce stack cost. A predictive performance model developed by PSU/UTK is central to the program allowing the team to study the physics and optimize materials/conditions specific to low Pt loading electrodes and ultra-high current density and operation.

  16. Insights Gained from Testing Alternate Cell Designs

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots; J. S. Herring; G. K. Housley; M. S. Sohal; D. G. Milobar; Thomas Cable

    2009-09-01

    The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cell for large-scale hydrogen production from steam over a temperature range of 800 to 900ºC. The INL has been testing various solid oxide cell designs to characterize their electrolytic performance operating in the electrolysis mode for hydrogen production. Some results presented in this report were obtained from cells, initially developed by the Forschungszentrum Jülich and now manufactured by the French ceramics firm St. Gobain. These cells have an active area of 16 cm2 per cell. They were initially developed as fuel cells, but are being tested as electrolytic cells in the INL test stands. The electrolysis cells are electrode-supported, with ~10 µm thick yttria-stabilized zirconia (YSZ) electrolytes, ~1400 µm thick nickel-YSZ steam-hydrogen electrodes, and manganite (LSM) air-oxygen electrodes. The experiments were performed over a range of steam inlet mole fractions (0.1 to 0.6), gas flow rates, and current densities (0 to 0.6 A/cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. On a molar basis, the steam consumption rate is equal to the hydrogen production rate. Cell performance was evaluated by performing DC potential sweeps at 800, 850, and 900°C. The voltage-current characteristics are presented, along with values of area-specific resistance as a function of current density. Long-term cell performance is also assessed to evaluate cell degradation. Details of the custom single-cell test apparatus developed for these experiments are also presented. NASA, in conjunction with the University of Toledo, has developed another fuel cell concept with the goals of reduced weight and high power density. The NASA cell is structurally symmetrical, with both electrodes supporting the thin electrolyte and containing micro-channels for gas diffusion. This configuration is called a bi

  17. Multistage Force Amplification of Piezoelectric Stacks

    Science.gov (United States)

    Xu, Tian-Bing (Inventor); Siochi, Emilie J. (Inventor); Zuo, Lei (Inventor); Jiang, Xiaoning (Inventor); Kang, Jin Ho (Inventor)

    2015-01-01

    Embodiments of the disclosure include an apparatus and methods for using a piezoelectric device, that includes an outer flextensional casing, a first cell and a last cell serially coupled to each other and coupled to the outer flextensional casing such that each cell having a flextensional cell structure and each cell receives an input force and provides an output force that is amplified based on the input force. The apparatus further includes a piezoelectric stack coupled to each cell such that the piezoelectric stack of each cell provides piezoelectric energy based on the output force for each cell. Further, the last cell receives an input force that is the output force from the first cell and the last cell provides an output apparatus force In addition, the piezoelectric energy harvested is based on the output apparatus force. Moreover, the apparatus provides displacement based on the output apparatus force.

  18. Corrosion test cell for bipolar plates

    Science.gov (United States)

    Weisbrod, Kirk R.

    2002-01-01

    A corrosion test cell for evaluating corrosion resistance in fuel cell bipolar plates is described. The cell has a transparent or translucent cell body having a pair of identical cell body members that seal against opposite sides of a bipolar plate. The cell includes an anode chamber and an cathode chamber, each on opposite sides of the plate. Each chamber contains a pair of mesh platinum current collectors and a catalyst layer pressed between current collectors and the plate. Each chamber is filled with an electrolyte solution that is replenished with fluid from a much larger electrolyte reservoir. The cell includes gas inlets to each chamber for hydrogen gas and air. As the gases flow into a chamber, they pass along the platinum mesh, through the catalyst layer, and to the bipolar plate. The gas exits the chamber through passageways that provide fluid communication between the anode and cathode chambers and the reservoir, and exits the test cell through an exit port in the reservoir. The flow of gas into the cell produces a constant flow of fresh electrolyte into each chamber. Openings in each cell body is member allow electrodes to enter the cell body and contact the electrolyte in the reservoir therein. During operation, while hydrogen gas is passed into one chamber and air into the other chamber, the cell resistance is measured, which is used to evaluate the corrosion properties of the bipolar plate.

  19. FCTESTNET - Testing fuel cells for transportation

    NARCIS (Netherlands)

    Winkel, R.G.; Foster, D.L.; Smokers, R.T.M.

    2006-01-01

    FCTESTNET (Fuel Cell Testing and Standardization Network) is an ongoing European network project within Framework Program 5. It is a three-year project that commenced January 2003, with 55 partners from European research centers, universities, and industry, working in the field of fuel cell R and D.

  20. 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.

  1. Stacked antiaromatic porphyrins

    Science.gov (United States)

    Nozawa, Ryo; Tanaka, Hiroko; Cha, Won-Young; Hong, Yongseok; Hisaki, Ichiro; Shimizu, Soji; Shin, Ji-Young; Kowalczyk, Tim; Irle, Stephan; Kim, Dongho; Shinokubo, Hiroshi

    2016-11-01

    Aromaticity is a key concept in organic chemistry. Even though this concept has already been theoretically extrapolated to three dimensions, it usually still remains restricted to planar molecules in organic chemistry textbooks. Stacking of antiaromatic π-systems has been proposed to induce three-dimensional aromaticity as a result of strong frontier orbital interactions. However, experimental evidence to support this prediction still remains elusive so far. Here we report that close stacking of antiaromatic porphyrins diminishes their inherent antiaromaticity in the solid state as well as in solution. The antiaromatic stacking furthermore allows a delocalization of the π-electrons, which enhances the two-photon absorption cross-section values of the antiaromatic porphyrins. This feature enables the dynamic switching of the non-linear optical properties by controlling the arrangement of antiaromatic π-systems on the basis of intermolecular orbital interactions.

  2. Stack filter classifiers

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Reid B [Los Alamos National Laboratory; Hush, Don [Los Alamos National Laboratory

    2009-01-01

    Just as linear models generalize the sample mean and weighted average, weighted order statistic models generalize the sample median and weighted median. This analogy can be continued informally to generalized additive modeels in the case of the mean, and Stack Filters in the case of the median. Both of these model classes have been extensively studied for signal and image processing but it is surprising to find that for pattern classification, their treatment has been significantly one sided. Generalized additive models are now a major tool in pattern classification and many different learning algorithms have been developed to fit model parameters to finite data. However Stack Filters remain largely confined to signal and image processing and learning algorithms for classification are yet to be seen. This paper is a step towards Stack Filter Classifiers and it shows that the approach is interesting from both a theoretical and a practical perspective.

  3. 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

  4. 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

    2016-01-01

    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...

  5. Detailed Electrochemical Characterisation of Large SOFC Stacks

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Hjelm, Johan; Barfod, R.

    2012-01-01

    application of advanced methods for detailed electrochemical characterisation during operation. An operating stack is subject to steep compositional gradients in the gaseous reactant streams, and significant temperature gradients across each cell and across the stack, which makes it a complex system...... Fuel Cell A/S was characterised in detail using electrochemical impedance spectroscopy. An investigation of the optimal geometrical placement of the current probes and voltage probes was carried out in order to minimise measurement errors caused by stray impedances. Unwanted stray impedances...... are particularly problematic at high frequencies. Stray impedances may be caused by mutual inductance and stray capacitance in the geometrical set-up and do not describe the fuel cell. Three different stack geometries were investigated by electrochemical impedance spectroscopy. Impedance measurements were carried...

  6. Rapid and Semi-Automated Extraction of Neuronal Cell Bodies and Nuclei from Electron Microscopy Image Stacks

    Science.gov (United States)

    Holcomb, Paul S.; Morehead, Michael; Doretto, Gianfranco; Chen, Peter; Berg, Stuart; Plaza, Stephen; Spirou, George

    2016-01-01

    Connectomics—the study of how neurons wire together in the brain—is at the forefront of modern neuroscience research. However, many connectomics studies are limited by the time and precision needed to correctly segment large volumes of electron microscopy (EM) image data. We present here a semi-automated segmentation pipeline using freely available software that can significantly decrease segmentation time for extracting both nuclei and cell bodies from EM image volumes. PMID:27259933

  7. Cu2ZnSnS4 solar cells prepared with sulphurized dc-sputtered stacked metallic precursors

    OpenAIRE

    Fernandes, P. A.; Salomé, P M P; Cunha, A. F. da; Schubert, Björn-Arvid

    2010-01-01

    In the present work we report the details of the preparation and characterization results of Cu2ZnSnS4 (CZTS) based solar cells. The CZTS absorber was obtained by sulphurization of dc magnetron sputtered Zn/Sn/Cu precursor layers. The morphology, composition and structure of the absorber layer were studied by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman scattering. The majority carrier type was identified via a hot point probe analysis....

  8. 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.

  9. Stacked Sequential Learning

    Science.gov (United States)

    2005-07-01

    a constant factor of K + 2. (To see this, note sequential stacking requires training K+2 classifiers: the classifiers f1, . . . , fK used in cross...on the non- sequential learners (ME and VP) but improves per- formance of the sequential learners (CRFs and VPH - MMs) less consistently. This pattern

  10. 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 ...

  11. 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.

  12. Optimized hydrogen generation in a semicontinuous sodium borohydride hydrolysis reactor for a 60 W-scale fuel cell stack

    Science.gov (United States)

    Arzac, G. M.; Fernández, A.; Justo, A.; Sarmiento, B.; Jiménez, M. A.; Jiménez, M. M.

    Catalyzed hydrolysis of sodium borohydride (SBH) is a promising method for the hydrogen supply of fuel cells. In this study a system for controlled production of hydrogen from aqueous sodium borohydride (SBH) solutions has been designed and built. This simple and low cost system operates under controlled addition of stabilized SBH solutions (fuel solutions) to a supported CoB catalyst. The system works at constant temperature delivering hydrogen at 1 L min -1 constant rate to match a 60-W polymer electrolyte membrane fuel cell (PEMFC). For optimization of the system, several experimental conditions were changed and their effect was investigated. A simple model based only on thermodynamic considerations was proposed to optimize system parameters at constant temperature and hydrogen evolution rate. It was found that, for a given SBH concentration, the use of the adequate fuel addition rate can maximize the total conversion and therefore the gravimetric storage capacity. The hydrogen storage capacity was as high as 3.5 wt% for 19 wt% SBH solution at 90% fuel conversion and an operation temperature of 60 °C. It has been demonstrated that these optimized values can also be achieved for a wide range of hydrogen generation rates. Studies on the durability of the catalyst showed that a regeneration step is needed to restore the catalytic activity before reusing.

  13. 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.

  14. 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.

  15. Solid Oxide Fuel Cell Development at Topsoe Fuel Cell A/S and Risø National Laboratory

    DEFF Research Database (Denmark)

    Christiansen, Niels; Hansen, J B.; Larsen, H H.

    2007-01-01

    The consortium of Topsoe Fuel Cell A/S and Riso National Laboratory has up-scaled its production capacity of anode-supported cells to about 1100 per week. Stacks are based on a compact thin plate multilayer design with metallic interconnects and 12x12 cm(2) or 18x18 cm(2) foot print. Larger (500 cm......(2)) cells are currently under evaluation. Stacks have been tested successfully for more than 13000 h. Several 50 or 75 cell stacks in the 1+ kW power range have been tested successfully at a fuel utilisation of up to 92%. Multi stack modules consisting of four 75 cell stacks have been tested...... tolerance towards redox cycling. In collaboration with Wartsila, a 24-stack prototype based on natural gas is being tested. For methanol based systems the methanol is methanated upstream the anode using a newly developed proprietary Haldor Topsoe catalyst. The range of fuels have further been extended...

  16. Cassette less SOFC stack and method of assembly

    Science.gov (United States)

    Meinhardt, Kerry D

    2014-11-18

    A cassette less SOFC assembly and a method for creating such an assembly. The SOFC stack is characterized by an electrically isolated stack current path which allows welded interconnection between frame portions of the stack. In one embodiment electrically isolating a current path comprises the step of sealing a interconnect plate to a interconnect plate frame with an insulating seal. This enables the current path portion to be isolated from the structural frame an enables the cell frame to be welded together.

  17. Effect of operative conditions on a PEFC stack performance

    Energy Technology Data Exchange (ETDEWEB)

    Urbani, Francesco; Barbera, Orazio; Giacoppo, Giosue; Squadrito, Gaetano; Passalacqua, Enza [CNR-ITAE (Istituto di Tecnologie Avanzate per l' Energia ' Nicola Giordano' ), Salita S. Lucia sopra Contesse, 5-98126 Messina (Italy)

    2008-06-15

    The operative conditions influence the performance of a polymer electrolyte fuel cell (PEFC). In particular, when a multi-cell (stack) instead of a single cell is investigated, a proper water management and flow stoichiometric ratio are essential for obtaining high electrical conversion efficiency. In this paper, a five cell air cooled PEM fuel cell stack was designed and realized, and systematic studies on the influence of the reactants humidification have been carried out to optimize the operative conditions. Polarization curves and time test at a fixed current have been conducted for various cathode (RHC) and anode (RHA) inlet humidity conditions. In particular, a small decay and low performance were obtained for RHA and <70% and a considerable decay and low performance for RHA and >70%. A good compromise for water management, in terms of decay and performance, is obtained when a symmetrical RH of 70% was used, because in this case an optimal water balance was probably reached considering that high flow of gases was used. In fact, insufficient water content implies a lower ion conductivity of the membrane whereas excess of water yields to flooding of the electrodes and parasitic losses due to the presence of water in the gas channels. Consequently, these effects lead to a lowering of voltages during lifetime tests. In any case, the cathode RH has a stronger influence on the stack decay compared to the anode one. In the optimal selected conditions of RH a constant and stable power of about 55 W (at 20 A) was obtained during the 15 h of operation. (author)

  18. Demonstration and testing of a stacking system for colliery spoil tips. Demostracion de un sistema de apilado en explotaciones de carbon a cielo abierto; Informe final

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    Coal extraction is associated with the disposal of large quantities of waste which has poor cohesive properties and high moisture content. Problems associated with spoil heaps include: instability due to the poor geomechanical characteristics of the material they contain; and their detrimental impact on the local environment. The project objective is to construct dams using granular material of low moisture content which is obtained from the same mining site. In order to undertake the construction it is proposed to demonstrate a compact stacking system which has been specially designed for the purposes, there is no commercially available equipment which meets the following requirements: compact dimensions (approx. 100 t); low capital cost; stacking capacity 1000 to 3000 t/h; delivery time similar to conventional machines; low centre of gravity allowing the machine to operate on gradients of up to 10 degrees; intermediate conveyor not required; good manoeuvring speed; simple design and high operating reliability, resulting in low running costs; ease of assembly, installation and transport, thus allowing deployment at different sites which will improve machine viability.

  19. 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).

  20. Initiation and Performance of a Coating for Countering Chromium Poisoning in a SOFC-stack

    DEFF Research Database (Denmark)

    Nielsen, Karsten Agersted; Persson, Åsa Helen; Beeaff, Dustin;

    2007-01-01

    Minimising transport of chromium from the metallic interconnect (e.g. of Crofer 22APU) to the cathode in a planar solid oxide fuel cell is done by application of a coating between the two parts. The coating is applied by slurry coating, and taken through stack initialisation it transforms...... into a stable and densely grown barrier layer, which minimises both the evaporation of chromium from the interconnect surface and the electrical contact resistance between the interconnect and the cathode. Between comparable stack element tests with and without coatings at 750 degrees C, the degradation rate...

  1. Precision cosmography with stacked voids

    CERN Document Server

    Lavaux, Guilhem

    2011-01-01

    We present a purely geometrical method for probing the expansion history of the Universe from the observation of the shape of stacked voids in spectroscopic re dshift surveys. Our method is an Alcock-Pasczinsky test based on the average sphericity of voids posited on the local isotropy of the Universe. It works by comparing the temporal extent of cosmic voids along the line of sight with their angular, spatial extent. We describe the algorithm that we use to detect and stack voids in redshift shells on the light cone and test it on mock light cones produced from N-body simulations. We establish a robust statistical model for estimating the average stretching of voids in redshift space and quantify the contamination by peculiar velocities. Finally, we assess the capability of this approach to constrain dark energy parameters in terms of the figure of merit (FoM) of the dark energy task force and in particular of the proposed Euclid mission which is particularly suited for this technique since it is a spectrosc...

  2. 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.

  3. Micro-electroforming metallic bipolar electrodes for mini-DMFC stacks

    CERN Document Server

    Shyu, R F; Lee, J -H

    2008-01-01

    This paper describes the development of metallic bipolar plate fabrication using micro-electroforming process for mini-DMFC (direct methanol fuel cell) stacks. Ultraviolet (UV) lithography was used to define micro-fluidic channels using a photomask and exposure process. Micro-fluidic channels mold with 300 micrometers thick and 500 micrometers wide were firstly fabricated in a negative photoresist onto a stainless steel plate. Copper micro-electroforming was used to replicate the micro-fluidic channels mold. Following by sputtering silver (Ag) with 1.2 micrometers thick, the metallic bipolar plates were completed. The silver layer is used for corrosive resistance. The completed mini-DMFC stack is a 2x2 cm2 fuel cell stack including a 1.5x1.5 cm2 MEA (membrane electrode assembly). Several MEAs were assembly into mini-DMFC stacks using the completed metallic bipolar plates. All test results showed the metallic bipolar plates suitable for mini-DMFC stacks. The maximum output power density is 9.3mW/cm2 and curren...

  4. Development of a small vehicular PEM fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J.J. [Department of Environment and Energy, National University of Tainan, Tainan 700 (China); Chang, W.R. [Department of Landscape and Architecture, Chung-Hua University, Hsinchu 300 (China); Weng, F.B.; Su, A. [Department of Mechanical Engineering and Fuel Cell Center, Yuan Ze University, Taoyuan (China); Chen, C.K. [Department of Mechanical Engineering, National Cheng Kung University, Tainan (China)

    2008-07-15

    This paper reports the development of components in a stack assembly and measurements of electrochemical characteristics of a proton exchange membrane (PEM) fuel cell stack. A novel test fixture together with a superposition approach is utilized to assess the Ohmic resistance across the stack. Then, a Tafel-kinetic equation for describing the voltage and current curve for all processes including electrode activation, Ohmic resistance and mass transfer was reported. It was found that the Ohmic resistance inside the fuel cell stack was markedly impacted by clamping torque of the stack. An optimum clamping torque of 90 kgf cm was determined based on measured Ohmic resistance. Uniformity and stability in the stack was verified by measuring cell voltage and temperature distribution. Finally, stack durability was tested by impelling a buggy over a relatively long duration. (author)

  5. A Novel STACK Generation Technique for MOS Analog Cell Circuit Layout%一个新的MOS模拟单元电路版图的STACK生成方法

    Institute of Scientific and Technical Information of China (English)

    李明原; 曾璇; 唐璞山; 周电

    2001-01-01

    This paper proposes a new technique to automatically generateSTACK layout for MOS analog cell circuits. The circuit net-list is first mapped into a diffusion graph. Based on the diffusion graph, circuit partition, pattern recognition and symmetry searching are carried out to generate sub-graphs, each of which can be implemented by a STACK. The proposed symmetry searching algorithm can find the maximal symmetry structures in a none fully symmetric circuit. To guarantee the generation of a Eularian trail, the Atallah Eularian trail generation algorithm is improved by employing the dummy adding technique. In order to evaluate the performance of a generated STACK, a distributed parasitic capacitance model is applied to calculate the STACK node parasitic capacitance, as well as the calculation of STACK area and shape.%提出了一种新的MOS模拟单元电路的STACK版图自动生成方法.该方法将电路网表映射为扩散图,基于扩散图进行电路划分、模板匹配和对称查找.提出的对称查找算法适用于非全对称电路的最大匹配对称结构查找.文中改进了Atallah欧拉路径生成算法,通过增加哑元条保证欧拉路径的生成.对生成的STACK,采用分布式寄生电容模型计算各个节点的寄生电容,并计算STACK的面积和形状,以确保其能够满足设计要求.

  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. Fungal melanins differ in planar stacking distances.

    Science.gov (United States)

    Casadevall, Arturo; Nakouzi, Antonio; Crippa, Pier R; Eisner, Melvin

    2012-01-01

    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.

  8. 40 CFR 61.33 - Stack sampling.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Stack sampling. 61.33 Section 61.33 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL... sampling. (a) Unless a waiver of emission testing is obtained under § 61.13, each owner or...

  9. 40 CFR 61.53 - Stack sampling.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Stack sampling. 61.53 Section 61.53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL... sampling. (a) Mercury ore processing facility. (1) Unless a waiver of emission testing is obtained...

  10. Simultaneous stack-gas scrubbing and waste water treatment

    Science.gov (United States)

    Poradek, J. C.; Collins, D. D.

    1980-01-01

    Simultaneous treatment of wastewater and S02-laden stack gas make both treatments more efficient and economical. According to results of preliminary tests, solution generated by stack gas scrubbing cycle reduces bacterial content of wastewater. Both processess benefit by sharing concentrations of iron.

  11. Stack Caching Using Split Data Caches

    DEFF Research Database (Denmark)

    Nielsen, Carsten; Schoeberl, Martin

    2015-01-01

    In most embedded and general purpose architectures, stack data and non-stack data is cached together, meaning that writing to or loading from the stack may expel non-stack data from the data cache. Manipulation of the stack has a different memory access pattern than that of non-stack data, showin...

  12. 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

  13. Multilayer Dye Aggregation at Dye/TiO2 Interface via π…π Stacking and Hydrogen Bond and Its Impact on Solar Cell Performance: A DFT Analysis

    Science.gov (United States)

    Zhang, Lei; Liu, Xiaogang; Rao, Weifeng; Li, Jingfa

    2016-10-01

    Multilayer dye aggregation at the dye/TiO2 interface of dye-sensitized solar cells is probed via first principles calculations, using p-methyl red azo dye as an example. Our calculations suggest that the multilayer dye aggregates at the TiO2 surface can be stabilized by π…π stacking and hydrogen bond interactions. Compared with previous two-dimensional monolayer dye/TiO2 model, the multilayer dye aggregation model proposed in this study constructs a three-dimensional multilayer dye/TiO2 interfacial structure, and provides a better agreement between experimental and computational results in dye coverage and dye adsorption energy. In particular, a dimer forms by π…π stacking interactions between two neighboring azo molecules, while one of them chemisorbs on the TiO2 surface; a trimer may form by introducing one additional azo molecule on the dimer through a hydrogen bond between two carboxylic acid groups. Different forms of multilayer dye aggregates, either stabilized by π…π stacking or hydrogen bond, exhibit varied optical absorption spectra and electronic properties. Such variations could have a critical impact on the performance of dye sensitized solar cells.

  14. 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.

  15. 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.

  16. 21 CFR 864.7825 - Sickle cell test.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Sickle cell test. 864.7825 Section 864.7825 Food... DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7825 Sickle cell test. (a) Identification. A sickle cell test is a device used to determine the sickle cell hemoglobin content of...

  17. 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

  18. Indium gallium zinc oxide layer used to decrease optical reflection loss at intermediate adhesive region for fabricating mechanical stacked multijunction solar cells

    Science.gov (United States)

    Sameshima, Toshiyuki; Nimura, Takeshi; Sugawara, Takashi; Ogawa, Yoshihiro; Yoshidomi, Shinya; Kimura, Shunsuke; Hasumi, Masahiko

    2017-01-01

    Reduction of optical reflection loss is discussed in three mechanical stacked samples: top crystalline silicon and bottom crystalline germanium substrates, top crystalline GaAs and bottom crystalline silicon substrates, and top crystalline GaP and bottom crystalline silicon substrates using an epoxy-type adhesive with a reflective index of 1.47. Transparent conductive Indium gallium zinc oxide (IGZO) layers with a refractive index of 1.85 were used as antireflection layers. IGZO layers were formed on the bottom surface of the top substrate and the top surface of the bottom substrate of the three stacked samples with thicknesses of 188, 130, and 102 nm. The insertion of IGZO layers decreased the optical reflectivity of the stacked samples. The IGZO layers provided high effective optical absorbency of bottom substrates of 0.925, 0.943, and 0.931, respectively, for light wavelength regions for light in which the top substrates were transparent and the bottom substrates were opaque.

  19. Effect of Co3O4 and Co3O4/CeO2 infiltration on the catalytic and electro-catalytic activity of LSM15/CGO10 porous cells stacks for oxidation of propene

    DEFF Research Database (Denmark)

    Ippolito, Davide; Kammer Hansen, Kent

    2015-01-01

    The objective of this work was to study the effect of Co3O4 and Co3O4/CeO2 infiltration on the propene oxidation catalytic activity of a La0.85Sr0.15MnO3/Ce0.9Gd0.1O1.95 electrochemical porous cell stack (11 layers, 5 single cells in series). The effect of the infiltration of Co3O4 and Co3O4/CeO2...... on the electrochemical properties of the porous cell stack was also investigated by electrochemical impedance spectroscopy (EIS). Co3O4 and Co3O4/CeO2 exhibited high catalytic activity for propene oxidation. The increase of propene oxidation rate with +4 V (0.8 V/cell) polarization reached 10% for the Co3O4 infiltrated...... reactor and 48% of efficiency at 300 °C. The Co3O4/CeO2 co-infiltration decreased the reactor polarization resistance, while Co3O4 infiltration had negligible effect on reactor electrochemical performance. The beneficial effect of CeO2 on the electrode activity was attributed to the increased...

  20. Assessing Elementary Algebra with STACK

    Science.gov (United States)

    Sangwin, Christopher J.

    2007-01-01

    This paper concerns computer aided assessment (CAA) of mathematics in which a computer algebra system (CAS) is used to help assess students' responses to elementary algebra questions. Using a methodology of documentary analysis, we examine what is taught in elementary algebra. The STACK CAA system, http://www.stack.bham.ac.uk/, which uses the CAS…

  1. Stacking disorder in ice I.

    Science.gov (United States)

    Malkin, Tamsin L; Murray, Benjamin J; Salzmann, Christoph G; Molinero, Valeria; Pickering, Steven J; Whale, Thomas F

    2015-01-07

    Traditionally, ice I was considered to exist in two well-defined crystalline forms at ambient pressure: stable hexagonal ice (ice Ih) and metastable cubic ice (ice Ic). However, it is becoming increasingly evident that what has been called cubic ice in the past does not have a structure consistent with the cubic crystal system. Instead, it is a stacking-disordered material containing cubic sequences interlaced with hexagonal sequences, which is termed stacking-disordered ice (ice Isd). In this article, we summarise previous work on ice with stacking disorder including ice that was called cubic ice in the past. We also present new experimental data which shows that ice which crystallises after heterogeneous nucleation in water droplets containing solid inclusions also contains stacking disorder even at freezing temperatures of around -15 °C. This supports the results from molecular simulations, that the structure of ice that crystallises initially from supercooled water is always stacking-disordered and that this metastable ice can transform to the stable hexagonal phase subject to the kinetics of recrystallization. We also show that stacking disorder in ice which forms from water droplets is quantitatively distinct from ice made via other routes. The emerging picture of ice I is that of a very complex material which frequently contains stacking disorder and this stacking disorder can vary in complexity depending on the route of formation and thermal history.

  2. Susceptibility testing of fish cell lines for virus isolation

    DEFF Research Database (Denmark)

    Ariel, Ellen; Skall, Helle Frank; Olesen, Niels Jørgen

    2009-01-01

    compare susceptibility between cell lines and between lineages within a laboratory and between laboratories (Inter-laboratory Proficiency Test). The objective being that the most sensitive cell line and lineages are routinely selected for diagnostic purposes.In comparing cell lines, we simulated "non......-cell-culture-adapted" virus by propagating the virus in heterologous cell lines to the one tested. A stock of test virus was produced and stored at - 80 °C and tests were conducted biannually. This procedure becomes complicated when several cell lines are in use and does not account for variation among lineages. In comparing...... cell lineages, we increased the number of isolates of each virus, propagated stocks in a given cell line and tested all lineages of that line in use in the laboratory. Testing of relative cell line susceptibility between laboratories is carried out annually via the Inter-laboratory Proficiency Test...

  3. Sickle Cell Trait in Blacks Can Skew Diabetes Test Results

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_163463.html Sickle Cell Trait in Blacks Can Skew Diabetes Test Results ... less accurate in black people who have the sickle cell anemia trait, a new study says. The test ...

  4. planSOEC. R and D and commercialization roadmap for SOEC electrolysis. R and D of SOEC stacks with improved durability. Project report

    Energy Technology Data Exchange (ETDEWEB)

    Richter, A.; Friis Pedersen, C.; Nielsen, Jens Ulrik [Topsoe Fuel Cells A/S, Kgs. Lyngby (Denmark); Mogensen, M.; Hoejgaard Jensen, S.; Ming Chen [Technical Univ. of Denmark. Fuel Cells and Solid State Chemistry Div., DTU Risoe Campus, Roskilde (Denmark); Sloth, M. [H2 Logic A/S, Herning (Denmark)

    2011-05-15

    The project has been divided into two parts: PART 1: Formulation of a R and D and commercialization roadmap for SOEC electrolysis. PART 2: Conducting R and D of SOEC stacks with improved durability. The purpose of Part 1 has been to develop a R and D and commercialisation roadmap for hydrogen and CO production plants based on the solid oxide electrolysis cell (SOEC) technology. SOEC technology is still on an early R and D stage but years of extensive R and D within SOFC technology provides a strong platform for an accelerated commercialisation. However, in order to guide the future SOEC R and D activities towards reaching commercial market requirements a detailed roadmap is necessary. An overall strategy for R and D of various electrolysis technologies in Denmark already exists{sup 2}, formulated in the Hydrogen Production working group in the Danish Hydrogen and Fuel Cell Partnership. The SOEC roadmap developed as part of the planSOEC project supplements the overall strategy, by conducting an updated analysis of state-of-the-art. Also planSOEC provides a detailed analysis of requirements for different market applications for SOEC, which enables formulation of precise and detailed R and D targets. The objectives of Part 2 in this project were multiple: 1) To investigate durability of solid oxide cells (SOCs) and stack components under industrially relevant (''harsh'') electrolysis operating conditions; 2) to investigate performance of standard TOFC (Topsoe Fuel Cell A/S) SOC stacks (based on state-of-the-art solid oxide cells) under mild electrolysis operating conditions ({<=}0.75 A/cm{sup 2}); 3) to further develop SOEC stack computer models available at Riso DTU and TOFC. Accordingly four lines of work were carried out in the here reported project: 1) Investigation of corrosion resistance of interconnect alloys. 2) Cell and stack element testing. 3) SOEC stack testing. 4) SOEC stack modeling. (LN)

  5. Evidence that proliferation of golgi apparatus depends on both de novo generation from the endoplasmic reticulum and formation from pre-existing stacks during the growth of tobacco BY-2 cells.

    Science.gov (United States)

    Abiodun, Moses Olabiyi; Matsuoka, Ken

    2013-04-01

    In higher plants, the numbers of cytoplasmic-distributed Golgi stacks differ based on function, age and cell type. It has not been clarified how the numbers are controlled, whether all the Golgi apparatus in a cell function equally and whether the increase in Golgi number is a result of the de novo formation from the endoplasmic reticulum (ER) or fission of pre-existing stacks. A tobacco prolyl 4-hydroxylase (NtP4H1.1), which is a cis-Golgi-localizing type II membrane protein, was tagged with a photoconvertible fluorescent protein, mKikGR (monomeric Kikume green red), and expressed in tobacco bright yellow 2 (BY-2) cells. Transformed cells were exposed to purple light to convert the fluorescence from green to red. A time-course analysis after the conversion revealed a progressive increase in green puncta and a decrease in the red puncta. From 3 to 6 h, we observed red, yellow and green fluorescent puncta corresponding to pre-existing Golgi; Golgi containing both pre-existing and newly synthesized protein; and newly synthesized Golgi. Analysis of the number and fluorescence of Golgi at different phases of the cell cycle suggested that an increase in Golgi number with both division and de novo synthesis occurred concomitantly with DNA replication. Investigation with different inhibitors suggested that the formation of new Golgi and the generation of Golgi containing both pre-existing and newly synthesized protein are mediated by different machineries. These results and modeling based on quantified results indicate that the Golgi apparatuses in tobacco BY-2 cells are not uniform and suggest that both de novo synthesis from the ER and Golgi division contribute almost equally to the increase in proliferating cells.

  6. Reliability analysis and initial requirements for FC systems and stacks

    Science.gov (United States)

    Åström, K.; Fontell, E.; Virtanen, S.

    In the year 2000 Wärtsilä Corporation started an R&D program to develop SOFC systems for CHP applications. The program aims to bring to the market highly efficient, clean and cost competitive fuel cell systems with rated power output in the range of 50-250 kW for distributed generation and marine applications. In the program Wärtsilä focuses on system integration and development. System reliability and availability are key issues determining the competitiveness of the SOFC technology. In Wärtsilä, methods have been implemented for analysing the system in respect to reliability and safety as well as for defining reliability requirements for system components. A fault tree representation is used as the basis for reliability prediction analysis. A dynamic simulation technique has been developed to allow for non-static properties in the fault tree logic modelling. Special emphasis has been placed on reliability analysis of the fuel cell stacks in the system. A method for assessing reliability and critical failure predictability requirements for fuel cell stacks in a system consisting of several stacks has been developed. The method is based on a qualitative model of the stack configuration where each stack can be in a functional, partially failed or critically failed state, each of the states having different failure rates and effects on the system behaviour. The main purpose of the method is to understand the effect of stack reliability, critical failure predictability and operating strategy on the system reliability and availability. An example configuration, consisting of 5 × 5 stacks (series of 5 sets of 5 parallel stacks) is analysed in respect to stack reliability requirements as a function of predictability of critical failures and Weibull shape factor of failure rate distributions.

  7. SEE on Different Layers of Stacked-SRAMs

    CERN Document Server

    Gupta, V; Tsiligiannis, G; Rousselet, M; Mohammadzadeh, A; Javanainen, A; Virtanen, A; Puchner, H; Saigné, F; Wrobel, F; Dilillo, L

    2015-01-01

    This paper presents heavy-ion and proton radiation test results of a 90 nm COTS SRAM with stacked structure. Radiation tests were made using high penetration heavy-ion cocktails at the HIF (Belgium) and at RADEF (Finland) as well as low energy protons at RADEF. The heavy-ion SEU cross-section showed an unusual profile with a peak at the lowest LET (heavy-ion with the highest penetration range). The discrepancy is due to the fact that the SRAM is constituted of two vertically stacked dice. The impact of proton testing on the response of both stacked dice is presented. The results are discussed and the SEU cross-sections of the upper and lower layers are compared. The impact of the stacked structure on the proton SEE rate is investigated.

  8. Current status and challenges in PEMFC stacks, systems and commercialization

    Institute of Scientific and Technical Information of China (English)

    任远; 曹广益; 朱新坚

    2006-01-01

    The current status of worldwide developments of polymer electrolyte membrane fuel cell (PEMFC) stacks and system,research activities in resent years to analyze the cost of PEMFC stacks and systems, the remaining research and development issues that should be resolved before the PEMFC available for commercial application were discussed. The two main problems that challenge the PEMFC commercialization were cost and fuel supply infrastructure. The ways to lower the cost, to choose the fuel and improve the efficiency and reliability were described. To research the cost target of 125 kW and stack lifetime of 40 000 ~ 100 000h, basic research in PEMFC was indispensable.

  9. 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.

  10. Sport stacking activities in school children's motor skill development.

    Science.gov (United States)

    Li, Yuhua; Coleman, Diane; Ransdell, Mary; Coleman, Lyndsie; Irwin, Carol

    2011-10-01

    This study examined the impact of a 12-wk. sport stacking intervention on reaction time (RT), manual dexterity, and hand-eye coordination in elementary school-aged children. 80 Grade 2 students participated in a 15-min. sport stacking practice session every school day for 12 wk., and were tested on psychomotor performance improvement. Tests for choice RT, manual dexterity, and photoelectric rotary pursuit tracking were conducted pre- and post-intervention for both experimental group (n = 36) and the controls (n = 44) who did no sport stacking. Students who had the intervention showed a greater improvement in two-choice RT. No other group difference was found. Such sport stacking activities may facilitate children's central processing and perceptual-motor integration.

  11. Flexible thermal cycle test equipment for concentrator solar cells

    Science.gov (United States)

    Hebert, Peter H [Glendale, CA; Brandt, Randolph J [Palmdale, CA

    2012-06-19

    A system and method for performing thermal stress testing of photovoltaic solar cells is presented. The system and method allows rapid testing of photovoltaic solar cells under controllable thermal conditions. The system and method presents a means of rapidly applying thermal stresses to one or more photovoltaic solar cells in a consistent and repeatable manner.

  12. Thyristor stack for pulsed inductive plasma generation.

    Science.gov (United States)

    Teske, C; Jacoby, J; Schweizer, W; Wiechula, J

    2009-03-01

    A thyristor stack for pulsed inductive plasma generation has been developed and tested. The stack design includes a free wheeling diode assembly for current reversal. Triggering of the device is achieved by a high side biased, self supplied gate driver unit using gating energy derived from a local snubber network. The structure guarantees a hard firing gate pulse for the required high dI/dt application. A single fiber optic command is needed to achieve a simultaneous turn on of the thyristors. The stack assembly is used for switching a series resonant circuit with a ringing frequency of 30 kHz. In the prototype pulsed power system described here an inductive discharge has been generated with a pulse duration of 120 micros and a pulse energy of 50 J. A maximum power transfer efficiency of 84% and a peak power of 480 kW inside the discharge were achieved. System tests were performed with a purely inductive load and an inductively generated plasma acting as a load through transformer action at a voltage level of 4.1 kV, a peak current of 5 kA, and a current switching rate of 1 kA/micros.

  13. 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.

  14. Unit cell sparger test program and analysis of test results

    Energy Technology Data Exchange (ETDEWEB)

    Park, Choon Kyung; Song, C. H.; Cho, S.; Yoon, Y. J

    2003-11-01

    This report presents the results of test data from CPT-3 test and the effect of important parameters on the IRWST load. The object of CPT-3 test is to determine the influence of air mass in the piping on the IRWST (In-containment Refueling Water Storage Tank) boundary during an operation of Safety Depressurization and Vent System (SDVS). The test was conducted from an initial system pressure of 15.2 MPa, a steam temperature of 343.3 .deg. C, and an air mass of 3.34 lb. Following valve actuation, the pressure within the discharge line underwent pressure transient due to high pressure steam from the pressurizer and the discharged high pressure air formed air bubbles, which expanded and compressed periodically in the simulated IRWST. Air bubble oscillation was terminated within 2 s into the test. The magnitude of the pressure wave during the air clearing period was inversely proportional to the distance and very abrupt pressure spikes were observed in case the distance from the sparger holes to the submerged structure was less than 0.9 m. After the isolation valves were closed, the water in the simulated IRWST was considered to rise up to the 2.4m from the water surface in the quench tank. The amount of air mass in the piping, water temperature in the simulated IRWST, air temperature in the piping had not significant effect on the pressure loading during an air clearing period. However, the opening time of the isolation valve, steam mass flow rate, and submergence of an sparger have been shown to have great effects on the pressure loading during an air clearing period. 2 % of sparger flow area seems to be sufficient for the vacuum breaker area to mitigate the water hammering caused by abrupt water level rising during valve closure.

  15. Stacking for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Zitlau, Roman; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-01-01

    We present an analysis of a general machine learning technique called 'stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We shown how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised machine learning techniques based on self-organising maps (SOMs), and supervised machine learning methods based on decision trees. We explore a range of stacking architectures, such as the number of layers and the number of base learners per layer. Finally we explore the effectiveness of stacking even when using a successful algorithm such as AdaBoost. We observe a significant improvement of between 1.9% and 21% on all computed metrics when stacking is applied to weak learners (such as SOMs and decision trees). When appl...

  16. Stacking for machine learning redshifts applied to SDSS galaxies

    Science.gov (United States)

    Zitlau, Roman; Hoyle, Ben; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-08-01

    We present an analysis of a general machine learning technique called `stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We show how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised machine learning techniques based on self-organizing maps (SOMs), and supervised machine learning methods based on decision trees. We explore a range of stacking architectures, such as the number of layers and the number of base learners per layer. Finally we explore the effectiveness of stacking even when using a successful algorithm such as AdaBoost. We observe a significant improvement of between 1.9 per cent and 21 per cent on all computed metrics when stacking is applied to weak learners (such as SOMs and decision trees). When applied to strong learning algorithms (such as AdaBoost) the ratio of improvement shrinks, but still remains positive and is between 0.4 per cent and 2.5 per cent for the explored metrics and comes at almost no additional computational cost.

  17. Embryonic stem cells: testing the germ-cell theory.

    Science.gov (United States)

    Hochedlinger, Konrad

    2011-10-25

    The exact cellular origin of embryonic stem cells remains elusive. Now a new study provides compelling evidence that embryonic stem cells, established under conventional culture conditions, originate from a transient germ-cell state.

  18. Recent Developments in Cell Vibration Testing at ABSL Space Products

    Science.gov (United States)

    Roberts, Sam; Thwaite, Carl

    2014-08-01

    This paper will describe vibration testing performed at ABSL in recent years on 18650 lithium-ion cells, focussing on work done to expand knowledge of the newest cells (the HCM and NL cells) under random vibration loads. COTS cells as used by ABSL are not necessarily designed for vibration tolerance, and so understanding the conditions that cause failures, and the precise failure modes, is a critical activity.The approach used for cell testing will be described, including the test setup and overall test and analysis flow. In particular, two different approaches (using fixed and resonating interfaces) will be described. The results of survival testing performed on HCM and NL cells will be presented. In addition, the damping behaviour of the HC cell will be described.

  19. 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

  20. Accelerated Life Test for Photovoltaic Cells Using Concentrated Light

    OpenAIRE

    Daniel Tudor Cotfas; Petru Adrian Cotfas; Dan Ion Floroian; Laura Floroian

    2016-01-01

    This paper presents a new method developed to significantly reduce the necessary time for the ageing tests for different types of photovoltaic cells. Two ageing factors have been applied to the photovoltaic cells: the concentrated light and the temperature. The maximum power of the photovoltaic cells was monitored during the ageing process. The electrical dc and ac parameters of the photovoltaic cells were measured and analyzed at 1 sun irradiance, before and after the test stress. During the...

  1. Application of Derrick Corporation's stack sizer technology for slimes reduction in 6 inch clean coal hydrocyclone circuits

    Energy Technology Data Exchange (ETDEWEB)

    Brodzik, P.

    2009-04-15

    The article discusses the successful introduction of Derrick Corporation's Stack Sizer technology for removing minus 200 mesh slimes from 6-inch coal hydrocyclone underflow prior to froth flotation or dewatering by screen bowl centrifuges. In 2006, the James River Coal Company selected the Stack Sizer fitted with Derrick 150 micron and 100 micron urethane screen panels for removal of the minus 100 mesh high ash clay fraction from the clean coal spiral product circuits. After this application proved successful, Derrick Corporation introduced new 75 micron urethane screen panels for use on the Stack Sizer. Evaluation of feed slurry to flotation cells and screen bowl centrifuges showed significant amounts of minus 75 micron that could potentially be removed by efficient screening technology. Removal of the minus 75 micron fraction was sought to reduce ash and moisture content of the final clean coal product. Full-scale lab tests confirmed that the Stack Sizer fitted with Derrick 75 micron urethane screen panels consistently reduced the minus 75 micron percentage in coal slurry from 6-inch clean coal hydrocyclone underflow that is approximately 15 to 20% solid by-weight and 30 to 60% minus 75 micron to a clean coal fraction that is approximately 13 to 16% minus 75 micron. As a result total ash is reduced from approximately 36 to 38% in the hydrocyclone underflow to 14 to 16% in the oversize product fraction form the Stack Sizers. 1 fig., 2 tabs., 5 photos.

  2. Real-time focal stack compositing for handheld mobile cameras

    Science.gov (United States)

    Solh, Mashhour

    2013-03-01

    Extending the depth of field using a single lens camera on a mobile device can be achieved by capturing a set of images each focused at a different depth or focal stack then combine these samples of the focal stack to form a single all-in-focus image or an image refocused at a desired depth of field. Focal stack compositing in real time for a handheld mobile camera has many challenges including capturing, processing power, handshaking, rolling shutter artifacts, occlusion, and lens zoom effect. In this paper, we describe a system for a real time focal stack compositing system for handheld mobile device with an alignment and compositing algorithms. We will also show all-in-focus images captured and processed by a cell phone camera running on Android OS.

  3. High performance PEMFC stack with open-cathode at ambient pressure and temperature conditions

    Energy Technology Data Exchange (ETDEWEB)

    Santa Rosa, D.T.; Pinto, D.G.; Silva, V.S. [SRE - Solucoes Racionais de Energia, S.A., Poligono Industrial do Alto do Ameal, Ramalhal (Portugal); Silva, R.A.; Rangel, C.M. [INETI, Unidade de Electroquimica de Materiais, Lisboa (Portugal)

    2007-12-15

    An open-air cathode proton exchange membrane fuel cell (PEMFC) was developed. This paper presents a study of the effect of several critical operating conditions on the performance of an 8-cell stack. The studied operating conditions such as cell temperature, air flow rate and hydrogen pressure and flow rate were varied in order to identify situations that could arise when the PEMFC stack is used in low-power portable PEMFC applications. The stack uses an air fan in the edge of the cathode manifolds, combining high stoichiometric oxidant supply and stack cooling purposes. In comparison with natural convection air-breathing stacks, the air dual-function approach brings higher stack performances, at the expense of having a lower use of the total stack power output. Although improving the electrochemical reactions kinetics and decreasing the polarization effects, the increase of the stack temperature lead to membrane excessive dehydration (loss of sorbed water), increasing the ohmic resistance of the stack (lower performance). The results show that the stack outputs a maximum power density of 310mW/cm{sup 2} at 790mA/cm{sup 2} when operating at ambient temperature, atmospheric air pressure, self-humidifying, air fan voltage at 5.0 V and 250 mbar hydrogen relative pressure. For the studied range of hydrogen relative pressure (150-750 mbar), it is found that the stack performance is practically not affected by this operation condition, although a slightly higher power output for 150 mbar was observed. On the other hand, it is found that the stack performance increases appreciably when operated with forced air convection instead of natural convection. Finally, the continuous fuel flow operation mode does not improve the stack performance in comparison with the hydrogen dead-end mode, in spite of being preferable to operate the stack with hydrogen flow rates above 0.20 l/min. (author)

  4. Enhanced test methods to characterise automotive battery cells

    Science.gov (United States)

    Mulder, Grietus; Omar, Noshin; Pauwels, Stijn; Leemans, Filip; Verbrugge, Bavo; De Nijs, Wouter; Van den Bossche, Peter; Six, Daan; Van Mierlo, Joeri

    This article evaluates the methods to characterise the behaviour of lithium ion cells of several chemistries and a nickel metal hydride cell for automotive applications like (plug-in) hybrid vehicles and battery electric vehicles. Although existing characterisation test methods are used, it was also indicated to combine test methods in order to speed up the test time and to create an improved comparability of the test results. Also, the existing capacity tests ignore that cells can be charged at several current rates. However, this is of interest for, e.g. fast charging and regenerative braking. Tests for high power and high energy application have been integrated in the enhanced method. The article explains the rationale to ameliorate the test methods. The test plan should make it possible to make an initial division in a group of cells purchased from several suppliers.

  5. 3D Porous Architecture of Stacks of β-TCP Granules Compared with That of Trabecular Bone: A microCT, Vector Analysis, and Compression Study.

    Science.gov (United States)

    Chappard, Daniel; Terranova, Lisa; Mallet, Romain; Mercier, Philippe

    2015-01-01

    The 3D arrangement of porous granular biomaterials usable to fill bone defects has received little study. Granular biomaterials occupy 3D space when packed together in a manner that creates a porosity suitable for the invasion of vascular and bone cells. Granules of beta-tricalcium phosphate (β-TCP) were prepared with either 12.5 or 25 g of β-TCP powder in the same volume of slurry. When the granules were placed in a test tube, this produced 3D stacks with a high (HP) or low porosity (LP), respectively. Stacks of granules mimic the filling of a bone defect by a surgeon. The aim of this study was to compare the porosity of stacks of β-TCP granules with that of cores of trabecular bone. Biomechanical compression tests were done on the granules stacks. Bone cylinders were prepared from calf tibia plateau, constituted high-density (HD) blocks. Low-density (LD) blocks were harvested from aged cadaver tibias. Microcomputed tomography was used on the β-TCP granule stacks and the trabecular bone cores to determine porosity and specific surface. A vector-projection algorithm was used to image porosity employing a frontal plane image, which was constructed line by line from all images of a microCT stack. Stacks of HP granules had porosity (75.3 ± 0.4%) and fractal lacunarity (0.043 ± 0.007) intermediate between that of HD (respectively 69.1 ± 6.4%, p TCP granules than bone trabecule. Stacks of HP granules represent a scaffold that resembles trabecular bone in its porous microarchitecture.

  6. Stacks: an analysis tool set for population genomics.

    Science.gov (United States)

    Catchen, Julian; Hohenlohe, Paul A; Bassham, Susan; Amores, Angel; Cresko, William A

    2013-06-01

    Massively parallel short-read sequencing technologies, coupled with powerful software platforms, are enabling investigators to analyse tens of thousands of genetic markers. This wealth of data is rapidly expanding and allowing biological questions to be addressed with unprecedented scope and precision. The sizes of the data sets are now posing significant data processing and analysis challenges. Here we describe an extension of the Stacks software package to efficiently use genotype-by-sequencing data for studies of populations of organisms. Stacks now produces core population genomic summary statistics and SNP-by-SNP statistical tests. These statistics can be analysed across a reference genome using a smoothed sliding window. Stacks also now provides several output formats for several commonly used downstream analysis packages. The expanded population genomics functions in Stacks will make it a useful tool to harness the newest generation of massively parallel genotyping data for ecological and evolutionary genetics.

  7. Cell overcharge testing inside sodium metal halide battery

    Science.gov (United States)

    Frutschy, Kris; Chatwin, Troy; Bull, Roger

    2015-09-01

    Testing was conducted to measure electrical performance and safety of the General Electric Durathon™ E620 battery module (600 V class 20 kWh) during cell overcharge. Data gathered from this test was consistent with SAE Electric Vehicle Battery Abuse Testing specification J2464 [1]. After cell overcharge failure and 24 A current flow for additional 60 minutes, battery was then discharged at 7.5 KW average power to 12% state of charge (SOC) and recharged back to 100% SOC. This overcharging test was performed on two cells. No hydrogen chloride (HCl) gas was detected during front cell (B1) test, and small amount (6.2 ppm peak) was measured outside the battery after center cell (F13) overcharge. An additional overcharge test was performed per UL Standard 1973 - Batteries for Use in Light Electric Rail (LER) Applications and Stationary Applications[2]. With the battery at 11% SOC and 280 °C float temperature, an individual cell near the front (D1) was deliberately imbalanced by charging it to 62% SOC. The battery was then recharged to 100% SOC. In all three tests, the battery cell pack was stable and individual cell failure did not propagate to other cells. Battery discharge performance, charge performance, and electrical isolation were normal after all three tests.

  8. Feature-Weighted Linear Stacking

    CERN Document Server

    Sill, Joseph; Mackey, Lester; Lin, David

    2009-01-01

    Ensemble methods, such as stacking, are designed to boost predictive accuracy by blending the predictions of multiple machine learning models. Recent work has shown that the use of meta-features, additional inputs describing each example in a dataset, can boost the performance of ensemble methods, but the greatest reported gains have come from nonlinear procedures requiring significant tuning and training time. Here, we present a linear technique, Feature-Weighted Linear Stacking (FWLS), that incorporates meta-features for improved accuracy while retaining the well-known virtues of linear regression regarding speed, stability, and interpretability. FWLS combines model predictions linearly using coefficients that are themselves linear functions of meta-features. This technique was a key facet of the solution of the second place team in the recently concluded Netflix Prize competition. Significant increases in accuracy over standard linear stacking is demonstrated on the Netflix Prize collaborative filtering da...

  9. 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..

  10. Solar-cell testing and evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Stefanakos, E.K.; Collis, W.J.

    1982-04-01

    A two year study of the degradation effects in AlGaAs/GaAs solar cells is described. Illuminated current-voltage measurements were made during temperature and humidity cycling and time dependent degradation measurements were recorded.

  11. 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.

  12. Design and testing of the Series III AMTEC cell

    Energy Technology Data Exchange (ETDEWEB)

    Mital, R.; Sievers, R.K.

    1999-07-01

    This paper describes the design and testing of the Series III (S3) Alkali Metal Thermal to Electric Converter (AMTEC) cell which is capable of high efficiency (15--25%) and high power density (100--150 W/kg). Compared to the Series 2 cell which is being developed primarily for space power systems, the Series III cell design provides a significantly higher beta{double_prime}-alumina solid electrolyte (BASE) tube packing density around the heat source thereby increasing cell power and minimizing heat loss. The prototype S3 cell will have 96 BASE tubes and is expected to produce about 150 We. In this cell design the BASE tube assemblies are mounted on a cylindrical tube support plate. The BASE tubes are arranged like spokes on a wheel. The inner cylinder, concentric to the tube support plate, is the hot side of the cell and the outer cylinder is the condenser. Since the prototype S3 cell will be the first of its kind, an engineering cell with same dimensions as the prototype but with 24 BASE tubes was built first. The purpose of this cell was to identify and resolve structural, thermal, manufacturing and sodium management issues before launching into the build of a complete 96 BASE tube cell. The engineering cell has been successfully built and tested. The data of the engineering cells have been used to calibrate the SINDA/FLUINT code to predict the prototype cell performance more accurately. The build of the prototype 96 BASE tube cells is now in progress. This paper presents the design and development of the prototype S3 cell. The fabrication and testing of the first S3 engineering cell is discussed next. Based on the test data of the engineering cell, the anticipated thermal performance of the prototype cells predicted by the calibrated SINDA model are also presented.

  13. Effects of Reference Performance Testing During Aging Using Commercial Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jon P. Christophersen; Chinh D. Ho; David Howell

    2005-07-01

    The Advanced Technology Development Program, under the oversight of the U.S. Department of Energy’s FreedomCAR and Vehicle Technologies Program, is investigating lithium-ion batteries for hybrid-electric vehicle applications. Cells are aged under various test conditions, including temperatures and states-of-charge. Life testing is interrupted at regular intervals to conduct reference performance tests (RPTs), which are used to measure changes in the electrical performance of the cells and then to determine cell degradation as a function of test time. Although designed to be unobtrusive, data from the Advanced Technology Development Gen 2 cells indicated that RPTs actually contributed to cell degradation and failure. A study was performed at the Idaho National Laboratory using commercially available lithium-ion cells to determine the impact of RPTs on life. A series of partial RPTs were performed at regular intervals during life testing and compared to a control group that was life tested without RPT interruption. It was determined that certain components of the RPT were detrimental, while others appeared to improve cell performance. Consequently, a new "mini" RPT was designed as an unobtrusive alternative. Initial testing with commercial cells indicates that the impact of the mini RPT is significantly less than the Gen 2 cell RPT.

  14. 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.

  15. Molten carbonate fuel cell product design improvement

    Energy Technology Data Exchange (ETDEWEB)

    P. Voyentzie; T. Leo; A. Kush; L. Christner; G. Carlson; C. Yuh

    1998-12-20

    Drawing on the manufacture, field test, and post-test experience of the sixteen Santa Clara Demonstration Project (SCDP) stacks, ERC is finalizing the next generation commercial entry product design. The second generation cells are 50% larger in area, 40% lighter on equal geometric area basis, and 30% thinner than the earlier design. These improvements have resulted in doubling of the full-height stack power. A low-cost and high-strength matrix has also been developed for improving product ruggedness. The low-cost advanced cell design incorporating these improvements has been refined through six short stack tests. Power production per cell of two times the SCDP maximum power operation, over ten thermal cycles, and overall operating flexibility with respect to load and thermal changes have been demonstrated in these short stack tests. An internally insulated stack enclosure has been designed and fabricated to eliminate the need for an inert gas environment during operation. ERC has acquired the capability for testing 400kW full-height direct fuel ceil (DFC) stack and balance-of-plant equipment. With the readiness of the power plant test facility, the cell package design, and the stack module, full-height stack testing has begun. The first full- height stack incorporating the post-SCDP second generation design was completed. The stack reached a power level of 253 kW, setting a world record for the highest power production from the advanced fuel cell system. Excellent performance uniformity at this power level affirmed manufacturing reproducibility of the components at the factory. This unoptimized small size test has achieved pipeline natural gas to DC electricity conversion efficiency of 47% (based on lower heating value - LHV) including the parasitic power consumed by the BOP equipment; that should translate to more than 50% efficiency in commercial operation, before employing cogeneration. The power plant system also operated smoothly. With the success of this

  16. Pressurized electrolysis stack with thermal expansion capability

    Science.gov (United States)

    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.

  17. Li-Ion Cell Lot Testing and Flight Screening Results

    Science.gov (United States)

    2011-02-01

    than \\c7<. Results arc shown in Table 4. Table 4 Moli-Energ) Li-Ion Cell Weights Alter Vaeuun Leak Tesi Initial Final Final Weight Weight...All tested cells were within 95 *5! o\\ their initial capacity. Note: Cells C009 and C023 were misplaced following being weighed after the vac- uum

  18. Tests Of Advanced Nickel/Hydrogen Cells

    Science.gov (United States)

    Smithrick, John J.; Hall, Stephen W.

    1994-01-01

    Individual-pressure-vessel (IPV) nickel-hydrogen technology adanced with intention of improving cycle life and performance. One advancement to use 26 percent potassium hydroxide electrolyte to improve cycle life. Another to modify state-of-art cell design to eliminate identified failure modes.

  19. Assessment of the 296-S-21 Stack Sampling Probe Location

    Energy Technology Data Exchange (ETDEWEB)

    Glissmeyer, John A.

    2006-09-08

    Tests were performed to assess the suitability of the location of the air sampling probe on the 296-S-21 stack according to the criteria of ANSI N13.1-1999, Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities. Pacific Northwest National Laboratory conducted most tests on a 3.67:1 scale model of the stack. CH2MHill also performed some limited confirmatory tests on the actual stack. The tests assessed the capability of the air-monitoring probe to extract a sample representative of the effluent stream. The tests were conducted for the practical combinations of operating fans and addressed: (1) Angular Flow--The purpose is to determine whether the velocity vector is aligned with the sampling nozzle. The average yaw angle relative to the nozzle axis should not be more than 20. The measured values ranged from 5 to 11 degrees on the scale model and 10 to 12 degrees on the actual stack. (2) Uniform Air Velocity--The gas momentum across the stack cross section where the sample is extracted should be well mixed or uniform. The uniformity is expressed as the variability of the measurements about the mean, the coefficient of variance (COV). The lower the COV value, the more uniform the velocity. The acceptance criterion is that the COV of the air velocity must be ?20% across the center two-thirds of the area of the stack. At the location simulating the sampling probe, the measured values ranged form 4 to 11%, which are within the criterion. To confirm the validity of the scale model results, air velocity uniformity measurements were made both on the actual stack and on the scale model at the test ports 1.5 stack diameters upstream of the sampling probe. The results ranged from 6 to 8% COV on the actual stack and 10 to 13% COV on the scale model. The average difference for the eight runs was 4.8% COV, which is within the validation criterion. The fact that the scale model results were slightly higher than the

  20. 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.

  1. Transgene Stacking in Cotton Improvement

    Institute of Scientific and Technical Information of China (English)

    YANG Ye-hua; WANG Xue-kui; YAO Ming-jing; FAN Yu-peng; GAO Da-yu

    2008-01-01

    @@ To date,more and more transgenic varieties of upland cotton (Gossypium hirsuturn L.) generated with transgenes,which derived from varies of alien species,are playing important role in agricultural production.Stacking of multi-transgenes has a potential for combining all the merits of distinct transgenic lines in a cultivar and possibly makes a significant contribution to cultivar improvement.

  2. Transgene Stacking in Cotton Improvement

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To date,more and more transgenic varieties of upland cotton(Gossypium hirsutum L.) generated with transgenes,which derived from varies of alien species,are playing important role in agricultural production.Stacking of multi-transgenes has a potential for combining all the merits of distinct

  3. Standoff Stack Emissions Monitoring Using Short Range Lidar

    Science.gov (United States)

    Gravel, Jean-Francois Y.; Babin, Francois; Allard, Martin

    2016-06-01

    There are well documented methods for stack emissions monitoring. These are all based on stack sampling through sampling ports in well defined conditions. Once sampled, the molecules are quantified in instruments that often use optical techniques. Unfortunately sampling ports are not found on all stacks/ducts or the use of the sampling ports cannot be planned efficiently because of operational constraints or the emissions monitoring equipment cannot be driven to a remote stack/duct. Emissions monitoring using many of the same optical techniques, but at a standoff distance, through the atmosphere, using short range high spatial resolution lidar techniques was thus attempted. Standoff absorption and Raman will be discussed and results from a field campaign will be presented along with short descriptions of the apparatus. In the first phase of these tests, the molecules that were targeted were NO and O2. Spatially resolved optical measurements allow for standoff identification and quantification of molecules, much like the standardized methods, except for the fact that it is not done in the stack, but in the plume formed by the emissions from the stack. The pros and cons will also be discussed, and in particular the problem of mass emission estimates that require the knowledge of the flow rate and the distribution of molecular concentration in the plane of measurement.

  4. Fuel Cell Hydroge Manifold for Lift Trucks

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham

    . The most common type of fuel cell used for automotive applications is PEM fuel cell. They are known for their high efficiency, low emissions and high reliability. However, lack of a hydrogen infrastructure, cost and durability of the stack is considered the biggest obstacles to the introduction of fuel...... cell vehicles. The overall aim of this research is studying different fuel cell systems and find out the system with the highest efficiency and less complexity. This will be achieved by modelling and optimization of the fuel cell system followed by some experimental tests. Efficiency of the stack...... is about 50%. But efficiency of whole the system is less than this value, because some part of electricity produced by the stack would run the auxiliary components. The work deals with development of steady state model of necessary components in the fuel cell system (humidifier, fuel cell stack and ejector...

  5. MFC-cascade stacks maximise COD reduction and avoid voltage reversal under adverse conditions.

    Science.gov (United States)

    Ledezma, Pablo; Greenman, John; Ieropoulos, Ioannis

    2013-04-01

    Six continuous-flow Microbial Fuel Cells (MFCs) configured as a vertical cascade and tested under different electrical connections are presented. When in parallel, stable operation and higher power and current densities than individual MFCs were observed, despite substrate imbalances. The cascading dynamic allowed for a cumulative COD reduction of >95% in approximately 5.7h, equivalent to 7.97 kg COD m(-3) d(-1). Under a series configuration, the stack exhibited considerable losses until correct fluidic/electrical insulation of the units was applied, upon which the stack also exhibited superior performance. In both electrical configurations, the 6 MFC system was systematically starved for up to 15 d, with no significant performance degradation. The results from the 14-month trials, demonstrate that cascade-stacking of small units can result in enhanced electricity production (vs single large units) and treatment rates without using expensive catalysts. It is also demonstrated that substrate imbalances and starvation do not necessarily result in cell-voltage reversal.

  6. 3D Segmentations of Neuronal Nuclei from Confocal Microscope Image Stacks

    Directory of Open Access Journals (Sweden)

    Antonio eLaTorre

    2013-12-01

    Full Text Available In this paper, we present an algorithm to create 3D segmentations of neuronal cells from stacks of previously segmented 2D images. The idea behind this proposal is to provide a general method to reconstruct 3D structures from 2D stacks, regardless of how these 2D stacks have been obtained. The algorithm not only reuses the information obtained in the 2D segmentation, but also attempts to correct some typical mistakes made by the 2D segmentation algorithms (for example, under segmentation of tightly-coupled clusters of cells. We have tested our algorithm in a real scenario --- the segmentation of the neuronal nuclei in different layers of the rat cerebral cortex. Several representative images from different layers of the cerebral cortex have been considered and several 2D segmentation algorithms have been compared. Furthermore, the algorithm has also been compared with the traditional 3D Watershed algorithm and the results obtained here show better performance in terms of correctly identified neuronal nuclei.

  7. FIELD TEST RESEARCH OF MULTI-STAGE STACKED TRAY SOLAR SEAWATER STILLER IN ACTUAL WEATHER%多级迭盘式太阳能蒸馏器典型天气下的实验研究

    Institute of Scientific and Technical Information of China (English)

    谢果; 郑宏飞; 郑子行; 康慧芳

    2013-01-01

    A multi-stage stacked tray solar distiller with folded and enhanced condensation faces was designed.Field test had been carried out in actual weather in order to obtain its characters of temperature variation and water production.Inner temperature and water production variation curves were given.Input sunlight ratio of top stage distillation chamber was deduced and the efficiency of desalination equipment was calculated.Comparison betweenfield test and steady state test was finished.Actual weather working characters and inner mass-heat transfer principle of this muhi-effect distiller was also analyzed.The results showed that the fresh water yield can reach upto 43kg/d and its performance ratio can reach up to 1.54 in fine weather,and this distiller is desired desalination equipment.%设计了一种具有强化凝结面的多级迭盘式太阳能蒸馏器.对其在实际大气下的升温特性及产水性能进行测试,得到其内部各级海水运行温度的全天变化曲线以及全天总产水量的变化曲线.对装置顶层腔体全天进光率进行推导,根据实验数据进一步得到海水淡化主机全天工作效率.实验结果与文献[4]中的稳态实验结果进行对比分析,探索了该类装置在实际天气条件的产水特性,对其内部的热质传递规律进行初步研究.结果表明,该装置的日产水量可达约43kg(晴好天气下),性能系数可达1.54,是一种较理想的小型海水淡化装置.

  8. Development of vacuum underfill technology for a 3D chip stack

    Science.gov (United States)

    Sakuma, Katsuyuki; Kohara, Sayuri; Sueoka, Kuniaki; Orii, Yasumitsu; Kawakami, Mikio; Asai, Kazuo; Hirayama, Yoshikazu; Knickerbocker, John U.

    2011-03-01

    We developed a vacuum underfill technology for 3D chip stacks and for flip chips in high performance system integration. We fabricated a 3D prototype chip stack using the vacuum underfill technology to apply the adhesive. The underfill was injected into each 6 µm gaps in a 3-layer chip stack and no voids were detected in acoustic microscopy images. Electrical tests and thermal reliability tests were used to measure the resistance of the vertical interconnections and the impact of the underfill. The results showed there was minimal difference in the average interconnection resistance of the chip stack with and without underfill.

  9. Expression of cubilin in mouse testes and Leydig cells.

    Science.gov (United States)

    Oh, Y S; Seo, J T; Ahn, H S; Gye, M C

    2016-04-01

    Cubilin (cubn) is a receptor for vitamins and various protein ligands. Cubn lacks a transmembrane domain but anchors to apical membranes by forming complexes with Amnionless or Megalin. In an effort to better understand the uptake of nutrients in testis, we analysed cubn expression in the developing mice testes. In testes, cubn mRNA increased from birth to adulthood. In the inter-stitium and isolated seminiferous tubules, neonatal increase in cubn mRNA until 14 days post-partum (pp) was followed by a marked increase at puberty (28 days pp). Cubn was found in the gonocytes, spermatogonia, spermatocytes and spermatids in the developing testes. In adult testes, strong Cubn immunoreactivity was found in the elongating spermatids, suggesting the role of Cubn in endocytosis during early spermiogenesis. In Sertoli cells and peritubular cells, Cubn immunoreactivity was weak throughout the testis development. In the inter-stitium, Cubn immunoreactivity was found in foetal Leydig cells, was weak to negligible in the stem cells and progenitor Leydig cells and was strong in immature and adult Leydig cells, demonstrating a positive association between Cubn and steroidogenic activity of Leydig cells. Collectively, these results suggest that Cubn may participate in the endocytotic uptake of nutrients in germ cells and somatic cells, supporting the spermatogenesis and steroidogenesis in mouse testes.

  10. Hereditary red cell membrane disorders and laboratory diagnostic testing.

    Science.gov (United States)

    King, M-J; Zanella, A

    2013-06-01

    This overview describes two groups of nonimmune hereditary hemolytic anemias caused by defects in membrane proteins located in distinct layers of the red cell membrane. Hereditary spherocytosis (HS), hereditary elliptocytosis (HE), and hereditary pyropoikilocytosis (HPP) represent disorders of the red cell cytoskeleton. Hereditary stomatocytoses represents disorders of cation permeability in the red cell membrane. The current laboratory screening tests for HS are the osmotic fragility test, acid glycerol lysis time test (AGLT), cryohemolysis test, and eosin-5'-maleimide (EMA)-binding test. For atypical HS, SDS-polyacrylamide gel electrophoresis of erythrocyte membrane proteins is carried out to confirm the diagnosis. The diagnosis of HE/HPP is based on abnormal red cell morphology and the detection of protein 4.1R deficiency or spectrin variants using gel electrophoresis. None of screening tests can detect all HS cases. Some testing centers (a survey of 25 laboratories) use a combination of tests (e.g., AGLT and EMA). No specific screening test for hereditary stomatocytoses is available. The preliminary diagnosis is based on presenting a compensated hemolytic anemia, macrocytosis, and a temperature or time dependent pseudohyperkalemia in some patients. Both the EMA-binding test and the osmotic fragility test may help in differential diagnosis of HS and hereditary stomatocytosis.

  11. Selectable-Tip Corrosion-Testing Electrochemical Cell

    Science.gov (United States)

    Lomness, Janice; Hintze, Paul

    2008-01-01

    The figure depicts aspects of an electrochemical cell for pitting- corrosion tests of material specimens. The cell is designed to generate a region of corrosion having a pit diameter determined by the diameter of a selectable tip. The average depth of corrosion is controlled by controlling the total electric charge passing through the cell in a test. The cell is also designed to produce minimal artifacts associated with crevice corrosion. There are three selectable tips, having diameters of 0.1 in. (0.254 cm), 0.3 in. (0.762 cm), and 0.6 in. (1.524 cm), respectively.

  12. Testing for the maximum cell probabilities in multinomial distributions

    Institute of Scientific and Technical Information of China (English)

    XIONG Shifeng; LI Guoying

    2005-01-01

    This paper investigates one-sided hypotheses testing for p[1], the largest cell probability of multinomial distribution. A small sample test of Ethier (1982) is extended to the general cases. Based on an estimator of p[1], a kind of large sample tests is proposed. The asymptotic power of the above tests under local alternatives is derived. An example is presented at the end of this paper.

  13. Categorical properties of topological and differentiable stacks

    NARCIS (Netherlands)

    Carchedi, D.J.

    2011-01-01

    The focus of this PhD research is on the theory of topological and differentiable stacks. There are two main themes of this research. The first, is the creation of the theory of compactly generated stacks, which solve many categorical shortcomings of the theory of classical topological stacks. In pa

  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......Embedded systems are computing systems for controlling and interacting with physical environments. Embedded systems with special timing constraints where the system needs to meet deadlines are referred to as real-time systems. In hard real-time systems, missing a deadline causes the system to fail...... 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...

  15. Effect of pore architecture and stacking direction on mechanical properties of solid freeform fabrication-based scaffold for bone tissue engineering.

    Science.gov (United States)

    Lee, Jung-Seob; Cha, Hwang Do; Shim, Jin-Hyung; Jung, Jin Woo; Kim, Jong Young; Cho, Dong-Woo

    2012-07-01

    Fabrication of a three-dimensional (3D) scaffold with increased mechanical strength may be an essential requirement for more advanced bone tissue engineering scaffolds. Various material- and chemical-based approaches have been explored to enhance the mechanical properties of engineered bone tissue scaffolds. In this study, the effects of pore architecture and stacking direction on the mechanical and cell proliferation properties of a scaffold were investigated. The 3D scaffold was prepared using solid freeform fabrication technology with a multihead deposition system. Various types of scaffolds with different pore architectures (lattice, stagger, and triangle types) and stacking directions (horizontal and vertical directions) were fabricated with a blend of polycaprolactone and poly lactic-co-glycolic acid. In compression tests, the triangle-type scaffold was the strongest among the experimental groups. Stacking direction affected the mechanical properties of scaffolds. An in vitro cell counting kit-8 assay showed no significant differences in optical density depending on the different pore architectures and stacking directions. In conclusion, mechanical properties of scaffolds can be enhanced by controlling pore architecture and stacking direction.

  16. NOx Conversion of Porous LSF15-CGO10 Cell Stacks

    DEFF Research Database (Denmark)

    Friedberg, Anja Zarah; Kammer Hansen, Kent

    2015-01-01

    A porous electrochemical reactor, made of La0.85Sr0.15FeO3 as electrode and Ce0.9Gd0.1O1.95 as electrolyte, was studied for the electrochemical reduction of NO with Propene. In order to enhance the effect of polarization, the reactor was impregnated with Ce0.9Gd0.1O1.95, CeO2 or Ce0.8Pr0.2O2-d...... nanoparticles. The HC-SCR on the cells was increased on the impregnated cells, but no electrochemical enhancement of this was observed. The applied overpotential on the impregnated cells changed the oxidation reaction of NO into NO2 which is considered an intermediate in the NO reduction to nitrogen....

  17. Anode Material Testing for Marine Sediment Microbial Fuel Cells

    Science.gov (United States)

    2013-09-26

    the plumping centered over billet, and the electrical feed through fitting with connecting wire. The solid graphite plate will be tested by...state conditions, using a liquid bath of glucose as the substrate (17). Chaudhuri and Lovley 2005, showed that the graphite foam increased production...Microbial fuel cells: performances and perspectives. Biofuels for fuel cells: biomass fermentation towards usage in fuel cells. IWA Publishing, London

  18. 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...

  19. Testing of a Buran flight-model fuel cell

    Science.gov (United States)

    Schautz, M.; Dudley, G.; Baron, F.; Popov, V.; Pospelov, B.

    A demonstration test program has been performed at European Space Research & Technology Center (ESTEC) on a flight-model Russian 'Photon' fuel cell. The tests, conducted at various power levels up to 23 kW, included current/voltage characteristics, transient behavior, autothermal startup, and impedance measurements. In addition, the product water and the purge gas were analyzed. All test goals were met and no electrochemical limitations were apparent.

  20. Segmentation of RGB-D indoor scenes by stacking random forests and conditional random fields

    DEFF Research Database (Denmark)

    Thøgersen, Mikkel; Guerrero, Sergio Escalera; Gonzàlez, Jordi;

    2016-01-01

    on stacked classifiers; the benefits are two fold: on one hand, the system scales well to consider different types of complex features and, on the other hand, the use of stacked classifiers makes the performance of the proposed technique more accurate. The proposed method consists of a random forest using...... a stacked random forest which gives the final predictions. The model is tested on the renown NYU-v2 dataset and the recently available SUNRGBD dataset. The approach shows that simple multimodal features with the power of using multi-class multi-scale stacked sequential learners (MMSSL) can achieve slight...

  1. The evolution of pretransfusion testing: from agglutination to solid-phase red cell adherence tests.

    Science.gov (United States)

    Plapp, F V; Sinor, L T; Rachel, J M

    1989-01-01

    Hospital transfusion services and blood centers still use manual hemagglutination tests for most of their serological procedures. Automation of hemagglutination reactions has proven to be difficult, primarily because hemagglutination lacks an objective endpoint which can be easily interpreted by inexpensive instruments. Alternatively, solid-phase red cell adherence assays for ABO cell and serum grouping, Rh typing, red cell and platelet antibody screening, red cell and platelet crossmatching, IgA deficiency screening, hepatitis B surface antigen, and HIV antibody screening have been developed. The performance of these assays compares favorably with current hemagglutination and enzyme immunoassay methods. All of these tests share a common objective endpoint of adherence or nonadherence of indicator red cells. This uniformity allows easy interpretation of results visually, spectrophotometrically, or by image analysis. The latter technique has the potential to revolutionize the reading and interpretation of all agglutination tests. Solid-phase red cell adherence tests in microplates are ideal for batch processing large numbers of specimens. However, adherence tests are not restricted to this format. Therefore, blood grouping dipsticks have been produced, which permit testing of individual blood samples even outside of the laboratory.

  2. Identification of the Hammerstein model of a PEMFC stack based on least squares support vector machines

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Hua; Zhu, Xin-Jian; Cao, Guang-Yi; Sui, Sheng; Hu, Ming-Ruo [Fuel Cell Research Institute, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2008-01-03

    This paper reports a Hammerstein modeling study of a proton exchange membrane fuel cell (PEMFC) stack using least squares support vector machines (LS-SVM). PEMFC is a complex nonlinear, multi-input and multi-output (MIMO) system that is hard to model by traditional methodologies. Due to the generalization performance of LS-SVM being independent of the dimensionality of the input data and the particularly simple structure of the Hammerstein model, a MIMO SVM-ARX (linear autoregression model with exogenous input) Hammerstein model is used to represent the PEMFC stack in this paper. The linear model parameters and the static nonlinearity can be obtained simultaneously by solving a set of linear equations followed by the singular value decomposition (SVD). The simulation tests demonstrate the obtained SVM-ARX Hammerstein model can efficiently approximate the dynamic behavior of a PEMFC stack. Furthermore, based on the proposed SVM-ARX Hammerstein model, valid control strategy studies such as predictive control, robust control can be developed. (author)

  3. Photovoltaic Test and Demonstration Project. [for solar cell power systems

    Science.gov (United States)

    Forestieri, A. F.; Brandhorst, H. W., Jr.; Deyo, J. N.

    1976-01-01

    The Photovoltaic Test and Demonstration Project was initiated by NASA in June, 1975, to develop economically feasible photovoltaic power systems suitable for a variety of terrestrial applications. Objectives include the determination of operating characteristic and lifetimes of a variety of solar cell systems and components and development of methodology and techniques for accurate measurements of solar cell and array performance and diagnostic measurements for solar power systems. Initial work will be concerned with residential applications, with testing of the first prototype system scheduled for June, 1976. An outdoor 10 kW array for testing solar power systems is under construction.

  4. Reliability Testing the Die-Attach of CPV Cell Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, N.; Sweet, C.; Kurtz, S.

    2011-02-01

    Results and progress are reported for a course of work to establish an efficient reliability test for the die-attach of CPV cell assemblies. Test vehicle design consists of a ~1 cm2 multijunction cell attached to a substrate via several processes. A thermal cycling sequence is developed in a test-to-failure protocol. Methods of detecting a failed or failing joint are prerequisite for this work; therefore both in-situ and non-destructive methods, including infrared imaging techniques, are being explored as a method to quickly detect non-ideal or failing bonds.

  5. Embryonic stem cells: An alternative approach to developmental toxicity testing

    Directory of Open Access Journals (Sweden)

    S Tandon

    2012-01-01

    Full Text Available Stem cells in the body have a unique ability to renew themselves and give rise to more specialized cell types having functional commitments. Under specified growth conditions, these cell types remain unspecialized but can be triggered to become specific cell type of the body such as heart, nerve, or skin cells. This ability of embryonic stem cells for directed differentiation makes it a prominent candidate as a screening tool in revealing safer and better drugs. In addition, genetic variations and birth defects caused by mutations and teratogens affecting early human development could also be studied on this basis. Moreover, replacement of animal testing is needed because it involves ethical, legal, and cost issues. Thus, there is a strong requirement for validated and reliable, if achievable, human stem cell-based developmental assays for pharmacological and toxicological screening.

  6. Embryonic stem cells: An alternative approach to developmental toxicity testing.

    Science.gov (United States)

    Tandon, S; Jyoti, S

    2012-04-01

    Stem cells in the body have a unique ability to renew themselves and give rise to more specialized cell types having functional commitments. Under specified growth conditions, these cell types remain unspecialized but can be triggered to become specific cell type of the body such as heart, nerve, or skin cells. This ability of embryonic stem cells for directed differentiation makes it a prominent candidate as a screening tool in revealing safer and better drugs. In addition, genetic variations and birth defects caused by mutations and teratogens affecting early human development could also be studied on this basis. Moreover, replacement of animal testing is needed because it involves ethical, legal, and cost issues. Thus, there is a strong requirement for validated and reliable, if achievable, human stem cell-based developmental assays for pharmacological and toxicological screening.

  7. Stacking Analysis of Binary Systems with HAWC

    Science.gov (United States)

    Brisbois, Chad; HAWC Collaboration

    2017-01-01

    Detecting binary systems at TeV energies is an important problem because only a handful of such systems are currently known. The nature of such systems is typically thought to be composed of a compact object and a massive star. The TeV emission from these systems does not obviously correspond to emission in GeV or X-ray, where many binary systems have previously been found. This study focuses on a stacking method to detect TeV emission from LS 5039, a known TeV binary, to test its efficacy in HAWC data. Stacking is a widely employed method for increasing signal to noise ratio in optical astronomy, but has never been attempted previously with HAWC. HAWC is an ideal instrument to search for TeV binaries, because of its wide field of view and high uptime. Applying this method to the entire sky may allow HAWC to detect binary sources of very short or very long periods not sensitive to current analyses. NSF, DOE, Los Alamos, Michigan Tech, CONACyt, UNAM, BUAP.

  8. Future manufacturing techniques for stacked MCM interconnections

    Science.gov (United States)

    Carson, R. F.; Seigal, P. K.; Craft, D. C.; Lovejoy, M. L.

    1994-06-01

    As multichip modules (MCMs) grow in chip count and complexity, increasingly large numbers of input/output (I/O) channels will be required for connection to other MCMs or printed wiring boards. In applications such as digital signal processing, large increases in processing density (number of operations in a given volume) can be obtained in stacked MCM arrangements. The potential pin counts and required I/O densities in these stacked architectures will push beyond the limits of present interlevel coupling techniques. This problem is particularly acute if easy separation of layers is needed to meet MCM testing and yield requirements. Solutions to this problem include the use of laser-drilled, metal-filled electrical vias in the MCM substrate and also optoelectronic data channels that operate in large arrays. These arrays will emit and detect signals traveling perpendicular to the surface of the MCM. All of these approaches will require packaging and alignment that makes use of advanced MCM manufacturing techniques.

  9. Model development of integrated CPOx reformer and SOFC stack system

    Directory of Open Access Journals (Sweden)

    Pianko-Oprych Paulina

    2016-12-01

    Full Text Available The main purpose of this study was to develop a mathematical model, in a steady state and dynamic mode, of a Catalytic Partial Oxidation (CPOx reformer – Solid Oxide Fuel Cell (SOFC stack integrated system in order to assess the system performance. Mass balance equations were written for each component in the system together with energy equation and implemented into the MATLAB Simulink simulation tool. Temperature, gas concentrations, pressure and current density were computed in the steady-state mode and validated against experimental data. The calculated I–V curve matched well the experimental one. In the dynamic modelling, several different conditions including step changes in fuel flow rates, stack voltage as well as temperature values were applied to estimate the system response against the load variations. Results provide valuable insight into the operating conditions that have to be achieved to ensure efficient CPOx performance for fuel processing for the SOFC stack applications.

  10. In Vitro Endothelialization Test of Biomaterials Using Immortalized Endothelial Cells.

    Directory of Open Access Journals (Sweden)

    Ken Kono

    Full Text Available Functionalizing biomaterials with peptides or polymers that enhance recruitment of endothelial cells (ECs can reduce blood coagulation and thrombosis. To assess endothelialization of materials in vitro, primary ECs are generally used, although the characteristics of these cells vary among the donors and change with time in culture. Recently, primary cell lines immortalized by transduction of simian vacuolating virus 40 large T antigen or human telomerase reverse transcriptase have been developed. To determine whether immortalized ECs can substitute for primary ECs in material testing, we investigated endothelialization on biocompatible polymers using three lots of primary human umbilical vein endothelial cells (HUVEC and immortalized microvascular ECs, TIME-GFP. Attachment to and growth on polymer surfaces were comparable between cell types, but results were more consistent with TIME-GFP. Our findings indicate that TIME-GFP is more suitable for in vitro endothelialization testing of biomaterials.

  11. Dead-ended anode polymer electrolyte fuel cell stack operation investigated using electrochemical impedance spectroscopy, off-gas analysis and thermal imaging

    Science.gov (United States)

    Meyer, Quentin; Ashton, Sean; Curnick, Oliver; Reisch, Tobias; Adcock, Paul; Ronaszegi, Krisztian; Robinson, James B.; Brett, Daniel J. L.

    2014-05-01

    Dead-ended anode operation, with intermittent purge, is increasingly being used in polymer electrolyte fuel cells as it simplifies the mass flow control of feed and improves fuel efficiency. However, performance is affected through a reduction in voltage during dead-ended operation, particularly at high current density. This study uses electrochemical impedance spectroscopy (EIS), off-gas analysis and high resolution thermal imaging to examine the source of performance decay during dead-ended operation. A novel, 'reconstructed impedance' technique is applied to acquire complete EIS spectra with a temporal resolution that allows the dynamics of cell processes to be studied. The results provide evidence that upon entering dead-ended operation, there is an initial increase in performance associated with an increase in anode compartment pressure and improved hydration of the membrane electrolyte. Subsequent reduction in performance is associated with an increase in mass transport losses due to a combination of water management issues and build-up of N2 in the anode. The purge process rapidly recovers performance. Understanding of the processes involved in the dead-end/purge cycle provides a rationale for determining the optimum cycle frequency and duration as a function of current density.

  12. Proton Exchange Membrane Fuel Cell Engineering Model Powerplant. Test Report: Benchmark Tests in Three Spatial Orientations

    Science.gov (United States)

    Loyselle, Patricia; Prokopius, Kevin

    2011-01-01

    Proton exchange membrane (PEM) fuel cell technology is the leading candidate to replace the aging alkaline fuel cell technology, currently used on the Shuttle, for future space missions. This test effort marks the final phase of a 5-yr development program that began under the Second Generation Reusable Launch Vehicle (RLV) Program, transitioned into the Next Generation Launch Technologies (NGLT) Program, and continued under Constellation Systems in the Exploration Technology Development Program. Initially, the engineering model (EM) powerplant was evaluated with respect to its performance as compared to acceptance tests carried out at the manufacturer. This was to determine the sensitivity of the powerplant performance to changes in test environment. In addition, a series of tests were performed with the powerplant in the original standard orientation. This report details the continuing EM benchmark test results in three spatial orientations as well as extended duration testing in the mission profile test. The results from these tests verify the applicability of PEM fuel cells for future NASA missions. The specifics of these different tests are described in the following sections.

  13. Investigation of Indoor Stability Testing of Polymer Solar Cell

    Directory of Open Access Journals (Sweden)

    Pelin Kavak

    2016-01-01

    Full Text Available We have fabricated organic solar cell of a new low bandgap polymer poly[4,4-bis(2-ethylhexyl-4H-cyclopenta[2,1-b:3,4-b′]dithiophene-2,6-diyl-alt-4,7-bis(2-thienyl-2,1,3-benzothiadiazole-5′,5′′-diyl] (PCPDTTBTT. We have investigated for the first time the stability tests, ISOS-L-1 and ISOS-D-3, of PCPDTTBTT solar cells. Thermal annealing of PCPDTTBTT solar cells at 80°C brought about an improvement of photocurrent generation, stability, and efficiency of the solar cells. T80 value of PCPDTTBTT solar cell is about 150 hours which is close to P3HT (235 h. PCPDTTBTT is very promising polymer for both polymer solar cell efficiency and stability.

  14. Stacking the odds for Golgi cisternal maturation.

    Science.gov (United States)

    Mani, Somya; Thattai, Mukund

    2016-01-01

    What is the minimal set of cell-biological ingredients needed to generate a Golgi apparatus? The compositions of eukaryotic organelles arise through a process of molecular exchange via vesicle traffic. Here we statistically sample tens of thousands of homeostatic vesicle traffic networks generated by realistic molecular rules governing vesicle budding and fusion. Remarkably, the plurality of these networks contain chains of compartments that undergo creation, compositional maturation, and dissipation, coupled by molecular recycling along retrograde vesicles. This motif precisely matches the cisternal maturation model of the Golgi, which was developed to explain many observed aspects of the eukaryotic secretory pathway. In our analysis cisternal maturation is a robust consequence of vesicle traffic homeostasis, independent of the underlying details of molecular interactions or spatial stacking. This architecture may have been exapted rather than selected for its role in the secretion of large cargo.

  15. Electrochemical Impedance Spectroscopy on Industrially-Relevant Solid Oxide Electrolyzer Cell Stacks: A Powerful Tool for in-Situ Investigations of Degradation Mechanisms

    DEFF Research Database (Denmark)

    Zielke, Philipp; Høgh, Jens Valdemar Thorvald; Chen, Ming

    2016-01-01

    that energy services can be covered in a stable and affordable manner. One promising solution is the synthetic fuel production by solid oxide electrolyzers. Electricity can be stored in a power-to-gas process during times of excess electricity production and then further converted to liquid fuels for e.......g. transportation, or at high demands converted back to electricity by either conventional power plants or fuel cells. One of today’s biggest hurdles for a successful commercialization of solid oxide electrolyzers is the stack’s lifetime with current industry targets in the order of five to ten years. To identify......In the current efforts of moving energy production to renewable sources, wind and solar energy are widely considered as the key technologies to cover our growing demands. However, the fluctuating nature of these sources requires a flexible energy system and storage technologies to ensure...

  16. Simultaneous multilayer formation of the polymer solar cell stack using roll-to-roll double slot-die coating from water

    DEFF Research Database (Denmark)

    Larsen-Olsen, Thue Trofod; Andreasen, Birgitta; Andersen, Thomas Rieks

    2012-01-01

    Double slot-die coating using aqueous inks was employed for the simultaneous coating of the active layer and the hole transport layer (HTL) in fully roll-to-roll (R2R) processed polymer solar cells. The double layer film was coated directly onto an electron transport layer (ETL) comprising doped...... zinc oxide that was processed by single slot-die coating from water. The active layer comprised poly-3-hexylthiophene:Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) as a dispersion of nanoparticles with a radius of 46 nm in water characterized using small-angle X-ray scattering (SAXS), transmission...... electron microscopy (TEM), and atomic force microscopy (AFM). The HTL was a dispersion of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) in water. The films were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) as chemical probe and X-ray reflectometry...

  17. Testing hot cell shielding in the fuel conditioning facility.

    Science.gov (United States)

    Courtney, J C; Klann, R T

    1997-01-01

    A comprehensive shield test program for a hot cell complex, the Fuel Conditioning Facility at Argonne National Laboratory, has been completed with minimum radiation exposure to participants. The recently modified shielding design for two hot cells and their associated transfer paths for irradiated materials was analyzed and tested for attenuating gamma rays from mixed fission product sources. Testing was accomplished using 0.37 TBq (10 Ci) and 518 TBq (14,000 Ci) 60Co sources. Of specific concern were radiation levels around wall penetrations and the interface between transport casks and the cell floor. Detailed measurements were made for surfaces that bound the hot cells, a transfer tunnel between the two cells, and storage pits that extend below the floors of both cells. In addition to surface measurements, dose equivalent rates in adjacent corridors were determined when the larger source was exposed. Results indicate that with some administrative controls, the facility shields are adequate to meet the design criterion that limits annual dose to less than 10 mSv (1 rem) for facility workers.

  18. Phosphoric and electric utility fuel cell technology development

    Science.gov (United States)

    Breault, R. D.; Briggs, T. A.; Congdon, J. V.; Demarche, T. E.; Gelting, R. L.; Goller, G. J.; Luoma, W. I.; McCloskey, M. W.; Mientek, A. P.; Obrien, J. J.

    1984-01-01

    The advancement of electric utility cell stack technology and reduction of cell stack cost was initiated. The cell stack has a nominal 10 ft (2) active area and operates at 120 psia/405(0)F. The program comprises six parallel phases, which culminate in a full height, 10-ft(2) stack verification test: (1) provides the information and services needed to manage the effort, including definition of the prototype commercial power plant; (2) develops the technical base for long term improvements to the cell stack; (3) develops materials and processing techniques for cell stack components incorporating the best available technology; (4) provides the design of hardware and conceptual processing layouts, and updates the power plant definition of Phase 1 to reflect the results of Phases 2 and 3; Phase 5 manufactures the hardware to verify the achievements of Phases 2 and 3, and analyzes the cost of this hardware; and Phase 6 tests the cell stacks assembled from the hardware of Phase 5 to assess the state of development.

  19. Influence of different sulfur to selenium ratios on the structural and electronic properties of Cu(In,Ga)(S,Se)2 thin films and solar cells formed by the stacked elemental layer process

    Science.gov (United States)

    Mueller, B. J.; Zimmermann, C.; Haug, V.; Hergert, F.; Koehler, T.; Zweigart, S.; Herr, U.

    2014-11-01

    In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se)2 thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, which is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.

  20. Gate stack technology for nanoscale devices

    Directory of Open Access Journals (Sweden)

    Byoung Hun Lee

    2006-06-01

    Full Text Available Scaling of the gate stack has been a key to enhancing the performance of complementary metal-oxide-semiconductor (CMOS field-effect transistors (FETs of past technology generations. Because the rate of gate stack scaling has diminished in recent years, the motivation for alternative gate stacks or novel device structures has increased considerably. Intense research during the last decade has led to the development of high dielectric constant (k gate stacks that match the performance of conventional SiO2-based gate dielectrics. However, many challenges remain before alternative gate stacks can be introduced into mainstream technology. We review the current status of and challenges in gate stack research for planar CMOS devices and alternative device technologies to provide insights for future research.

  1. Demagnetizing effects in stacked rectangular prisms

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...... a direct impact on the design of, e.g., active magnetic regenerators made of stacked rectangular prisms in terms of optimizing the internal field....

  2. Generic effluent monitoring system certification for AP-40 exhauster stack

    Energy Technology Data Exchange (ETDEWEB)

    Glissmeyer, J.A.; Davis, W.E.; Bussell, J.H.; Maughan, A.D.

    1997-09-01

    Tests were conducted to verify that the Generic Effluent Monitoring System (GEMS), as applied to the AP-40 exhauster stack, meets all applicable regulatory performance criteria for air sampling systems at nuclear facilities. These performance criteria address both the suitability of the air sampling probe location and the transport of the sample to the collection devices. The criteria covering air sampling probe location ensure that the contaminants in the stack are well mixed with the airflow at the probe location such that the extracted sample represents the whole. The sample transport criteria ensure that the sampled contaminants are quantitatively delivered to the collection device. The specific performance criteria are described in detail in the report. The tests demonstrated that the GEMS/AP-40 system meets all applicable performance criteria. The contaminant mixing tests were conducted by Pacific Northwest National Laboratory (PNNL) at the wind tunnel facility, 331-H Building, using a mockup of the actual stack. The particle sample transport tests were conducted by PNNL at the Numatec Hanford Company`s 305 Building. The AP-40 stack is typical of several 10-in. diameter stacks that discharge the filtered ventilation air from tank farms at the U.S. Department of Energy`s Hanford Site in Richland, Washington. The GEMS design features a probe with a single shrouded sampling nozzle, a sample delivery line, and sample collection system. The collection system includes a filter holder to collect the sample of record and an in-line detector head and filter for monitoring beta radiation-emitting particles. Unrelated to the performance criteria, it was found that the record sample filter holder exhibited symptoms of sample bypass around the particle collection filter. This filter holder should either be modified or replaced with a different type. 10 refs., 8 figs., 6 tabs.

  3. Environmental tests of metallization systems for terrestrial photovoltaic cells

    Science.gov (United States)

    Alexander, P., Jr.

    1985-01-01

    Seven different solar cell metallization systems were subjected to temperature cycling tests and humidity tests. Temperature cycling excursions were -50 deg C to 150 deg C per cycle. Humidity conditions were 70 deg C at 98% relative humidity. The seven metallization systems were: Ti/Ag, Ti/Pd/Ag, Ti/Pd/Cu, Ni/Cu, Pd/Ni/Solder, Cr/Pd/Ag, and thick film Ag. All metallization systems showed a slight to moderate decrease in cell efficiencies after subjection to 1000 temperature cycles. Six of the seven metallization systems also evidenced slight increases in cell efficiencies after moderate numbers of cycles, generally less than 100 cycles. The copper based systems showed the largest decrease in cell efficiencies after temperature cycling. All metallization systems showed moderate to large decreases in cell efficiencies after 123 days of humidity exposure. The copper based systems again showed the largest decrease in cell efficiencies after humidity exposure. Graphs of the environmental exposures versus cell efficiencies are presented for each metallization system, as well as environmental exposures versus fill factors or series resistance.

  4. The US Army Foreign Comparative Test fuel cell program

    Science.gov (United States)

    Bostic, Elizabeth; Sifer, Nicholas; Bolton, Christopher; Ritter, Uli; Dubois, Terry

    The US Army RDECOM initiated a Foreign Comparative Test (FCT) Program to acquire lightweight, high-energy dense fuel cell systems from across the globe for evaluation as portable power sources in military applications. Five foreign companies, including NovArs, Smart Fuel Cell, Intelligent Energy, Ballard Power Systems, and Hydrogenics, Inc., were awarded competitive contracts under the RDECOM effort. This paper will report on the status of the program as well as the experimental results obtained from one of the units. The US Army has interests in evaluating and deploying a variety of fuel cell systems, where these systems show added value when compared to current power sources in use. For low-power applications, fuel cells utilizing high-energy dense fuels offer significant weight savings over current battery technologies. This helps reduce the load a solider must carry for longer missions. For high-power applications, the low operating signatures (acoustic and thermal) of fuel cell systems make them ideal power generators in stealth operations. Recent testing has been completed on the Smart Fuel Cell A25 system that was procured through the FCT program. The "A-25" is a direct methanol fuel cell hybrid and was evaluated as a potential candidate for soldier and sensor power applications.

  5. Fiscal 1997 report on the results of the international standardization R and D. R and D of the standardization of a method to test acceleration life of phosphorous acid fuel cells; 1997 nendo seika hokokusho kokusai hyojun soseigata kenkyu kaihatsu. Rinsangata nenryo denchi no kasoku jumyo shiken hoho no hyojunka ni kansuru kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    As for fuel cells, which are expected as a new clean energy, the R and D are being proceeded with in various fields of the world, but the standardization has not been made both in Japan and abroad. In Japan, the situation is that the information on technical terms, indication method, performance test method, and environment/safety test methods of the phosphorous acid fuel cell power generation is publicly spread. In relation to the international promotion of fuel cells to be predicted, it is necessary to internationally standardize cells themselves which are a key component of fuel cell power generation facilities. Phosphorous acid fuel cells are expected of the earliest commercialization of all, but the common test method to evaluate life characteristics of the cell stack has not been established yet. In the R and D, for the purpose of internationally standardizing test methods to evaluate life characteristics of the cell stack, a study on the acceleration life test method of phosphoric acid fuel cells was conducted in terms of the technical trend, data, standard, etc. A plan was prepared on general rules of the method to test acceleration life at the cell reaction part of the small cell, and activities also were started for setting up a technical committee for the fuel cell power system in President`s Advisory Committee on Future Technology. 29 figs., 20 tabs.

  6. Monolithic solid oxide fuel cell technology advancement for coal-based power generation

    Science.gov (United States)

    1994-05-01

    This project has successfully advanced the technology for MSOFC's for coal-based power generation. Major advances include: tape-calendering processing technology, leading to 3X improved performance at 1000 C; stack materials formulations and designs with sufficiently close thermal expansion match for no stack damage after repeated thermal cycling in air; electrically conducting bonding with excellent structural robustness; and sealants that form good mechanical seals for forming manifold structures. A stack testing facility was built for high-spower MSOFC stacks. Comprehensive models were developed for fuel cell performance and for analyzing structural stresses in multicell stacks and electrical resistance of various stack configurations. Mechanical and chemical compatibility properties of fuel cell components were measured; they show that the baseline Ca-, Co-doped interconnect expands and weakens in hydrogen fuel. This and the failure to develop adequate sealants were the reason for performance shortfalls in large stacks. Small (1-in. footprint) two-cell stacks were fabricated which achieved good performance (average area-specific-resistance 1.0 ohm-sq cm per cell); however, larger stacks had stress-induced structural defects causing poor performance.

  7. PDMS/glass microfluidic cell culture system for cytotoxicity tests and cells passage

    DEFF Research Database (Denmark)

    Ziolkowska, K.; Jedrych, E.; Kwapiszewski, R.

    2010-01-01

    microdevice was developed and successfully tested. The MCCS microdevice is fully reusable, i.e. it can be used several times for various cell culture and cytotoxic experiments. The suitability of designed MCCS for cell-based cytotoxicity assay application was verified using 1,4-dioxane as a model toxic agent....... The series of cytotoxicity tests in the microdevice as well as in classic way using 96-well cell culture plates were performed to compare results obtained in micro- and macroscale. Fluorescein dibutyrate (FDB) and iodide propidine (PI) were used as viable and dead cells' markers, respectively. Fabricated...... MCCS microdevices were reproducible and apart from cell culture for long period of time, including cell passaging, it allowed cell-based cytotoxicity assays performance. The MCCS can be applied in high-throughput cell-based assays providing important informations on potential drug targets, substances...

  8. A Time-predictable Stack Cache

    DEFF Research Database (Denmark)

    Abbaspourseyedi, Sahar; Brandner, Florian; Schoeberl, Martin

    2013-01-01

    precise results of the cache analysis part of the WCET analysis. Splitting the data cache for different data areas enables composable data cache analysis. The WCET analysis tool can analyze the accesses to these different data areas independently. In this paper we present the design and implementation...... of a cache for stack allocated data. Our port of the LLVM C++ compiler supports the management of the stack cache. The combination of stack cache instructions and the hardware implementation of the stack cache is a further step towards timepredictable architectures....

  9. Ball Bearing Stacking Automation System

    Directory of Open Access Journals (Sweden)

    Shafeequerrahman S . Ahmed

    2013-01-01

    Full Text Available This document is an effort to introduce the concept of automation in small scale industries and or small workshops that are involved in the manufacturing of small objects such as nuts, bolts and ball bearing in this case. This an electromechanical system which includes certain mechanical parts that involves one base stand on which one vertical metallic frame is mounted and hinged to this vertical stand is an in humanized effort seems inadequate in this era making necessary the use of Electronics, Computer in the manufacturing processes leading to the concept of Automated Manufacturing System (AMS.The ball bearing stack automation is an effort in this regard. In our project we go for stack automation for any object for example a ball bearing, be that is still a manual system there. It will be microcontroller based project control system equipped with microcontroller 89C51 from any manufacturer like Atmel or Philips. This could have been easily implemented if a PLC could be used for manufacturing the staking unit but I adopted the microcontroller based system so that some more modification in the system can be effected at will as to use the same hardware .Although a very small object i.e. ball bearig or small nut and fixture will be tried to be stacked, the system with more precision and more power handling capacity could be built for various requirements of the industry. For increasing more control capacity, we can use another module of this series. When the bearing is ready, it will be sent for packing. This is sensed by an inductive sensor. The output will be proceeds by PLC and microcontroller card which will be driving the assembly in order to put it into pads or flaps. This project will also count the total number of bearings to be packed and will display it on a LCD for real time reference and a provision is made using a higher level language using hyper terminal of the computer

  10. Development of molten carbonate fuel cell power plant technology. Quarterly technical progress report No. 5, October 1, 1980-December 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    The overall objective of this program is to develop and verify the design of a prototype molten carbonate fuel cell stack which meets the requirements of a 1990's-competitive coal-fired electrical utility central station or industrial cogeneratin power plants. During this quarter, activity continued in all four task areas: Task 1 - system studies to define the reference power plant design; Task 2 - cell and stack design, development and verification; Task 3 - preparation for fabrication and testing of the full-scale prototype stack; and Task 4 - development of the capability to operate stacks on coal-derived gas.

  11. 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.

  12. Development of a 400 W High Temperature PEM Fuel Cell Power Pack

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Bang, Mads; Korsgaard, Anders

    2006-01-01

    ². The development of the bipolar plates and the stack design itself is an ongoing activity using CFD and optimizing for low pressure drop. Later versions of the stack design is expected to result in a much shorter stack. When using pure H2, the hydrogen circuit is running dead end with occasional purging. Single...... cell life time tests indicate that very infrequent purging does not accelerate degradation severely. This is a great advantage compared to the LTPEM which often has problems with flooding when not purged. The air supply is realized using a low power axial fan with a high turn down ratio. The stack...

  13. CYTOTOXICITY TESTING OF WOUND DRESSINGS USING METHYLCELLULOSE CELL-CULTURE

    NARCIS (Netherlands)

    VANLUYN, MJA; VANWACHEM, PB; NIEUWENHUIS, P; JONKMAN, MF

    1992-01-01

    Wound dressings may induce cytotoxic effects. In this study, we check several, mostly commercially available, wound dressings for cytotoxicity. We used our previously described, newly developed and highly sensitive 7 d methylcellulose cell culture with fibroblasts as the test system. Cytotoxicity is

  14. Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Timothy [Research Engineer; Motupally, Sathya [Research Engineer

    2012-06-01

    UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells. This in-depth investigation will focused on critical fuel cell components (e.g. membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. UTC had access to MEA materials that had accrued significant load time under real-world conditions in PureMotion® 120 power plant used in transit buses. These materials are referred to as end-of-life (EOL) components in the rest of this document. Advanced characterization techniques were used to evaluate degradation mode progress using these critical cell components extracted from both bus power plants and corresponding materials tested using the DOE AST’s. These techniques were applied to samples at beginning-of-life (BOL) to serve as a baseline. These comparisons advised the progress of the various failure modes that these critical components were subjected to, such as membrane degradation, catalyst support corrosion, platinum group metal dissolution, and others. Gaps in the existing ASTs predicted the degradation observed in the field in terms of these modes were outlined. Using the gaps, new AST’s were recommended and tested to better reflect the degradation modes seen in field operation. Also, BOL components were degraded in a test vehicle at UTC designed to accelerate the bus field operation.

  15. TEST RESULTS FOR FUEL CELL OPERATION ON ANAEROBIC DIGESTER GAS

    Science.gov (United States)

    EPA, in conjunction with ONSI Corp., embarked on a project to define, design, test, and assess a fuel cell energy recovery system for application at anaerobic digester waste water (sewage) treatment plants. Anaerobic digester gas (ADG) is produced at these plants during the proce...

  16. Stacks of SPS Dipole Magnets

    CERN Multimedia

    1974-01-01

    Stacks of SPS Dipole Magnets ready for installation in the tunnel. The SPS uses a separated function lattice with dipoles for bending and quadrupoles for focusing. The 6.2 m long normal conducting dipoles are of H-type with coils that are bent-up at the ends. There are two types, B1 (total of 360) and B2 (384). Both are for a maximum field of 1.8 Tesla and have the same outer dimensions (450x800 mm2 vxh) but with different gaps (B1: 39x129 mm2, B2: 52x92 mm2) tailored to the beam size. The yoke, made of 1.5 mm thick laminations, consists of an upper and a lower half joined together in the median plane once the coils have been inserted.

  17. Technique for Outdoor Test on Concentrating Photovoltaic Cells

    Directory of Open Access Journals (Sweden)

    Paola Sansoni

    2015-01-01

    Full Text Available Outdoor experimentation of solar cells is essential to maximize their performance and to assess utilization requirements and limits. More generally tests with direct exposure to the sun are useful to understand the behavior of components and new materials for solar applications in real working conditions. Insolation and ambient factors are uncontrollable but can be monitored to know the environmental situation of the solar exposure experiment. A parallel characterization of the photocells can be performed in laboratory under controllable and reproducible conditions. A methodology to execute solar exposure tests is proposed and practically applied on photovoltaic cells for a solar cogeneration system. The cells are measured with concentrated solar light obtained utilizing a large Fresnel lens mounted on a sun tracker. Outdoor measurements monitor the effects of the exposure of two multijunction photovoltaic cells to focused sunlight. The main result is the continuous acquisition of the V-I (voltage-current curve for the cells in different conditions of solar concentration and temperature of exercise to assess their behavior. The research investigates electrical power extracted, efficiency, temperatures reached, and possible damages of the photovoltaic cell.

  18. Off-line test of the KISS gas cell

    Energy Technology Data Exchange (ETDEWEB)

    Hirayama, Yoshikazu, E-mail: yoshikazu.hirayama@kek.jp [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Watanabe, Yutaka; Imai, Nobuaki; Ishiyama, Hironobu; Jeong, Sun-Chan; Miyatake, Hiroari; Oyaizu, Michihiro [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Kim, Yung Hee [Seoul National University, Seoul 151 742 (Korea, Republic of); Mukai, Momo [Tsukuba University, Ibaraki 305 0006 (Japan); Matsuo, Yukari; Sonoda, Tetsu; Wada, Michiharu [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351 0198 (Japan); Huyse, Mark; Kudryavtsev, Yuri; Van Duppen, Piet [Instituut voor Kern-en Stralingsfysica, KU Leuven, B-3001 Leuven (Belgium)

    2013-12-15

    Highlights: • Construction of the KEK Isotope Separation System (KISS) at RIKEN. • Ionization scheme of an iron. • Measurement of transport time profile in a gas cell. -- Abstract: The KEK Isotope Separation System (KISS) has been constructed at RIKEN to study the β-decay properties of neutron-rich isotopes with neutron numbers around N = 126 for application to astrophysics. A key component of KISS is a gas cell filled with argon gas at a pressure of 50 kPa to stop and collect the unstable nuclei, where the isotopes of interest will be selectively ionized using laser resonance ionization. We have performed off-line tests to study the basic properties of the gas cell and of KISS using nickel and iron filaments placed in the gas cell.

  19. Test of hybrid power system for electrical vehicles using a lithium-ion battery pack and a reformed methanol fuel cell range extender

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Ashworth, Leanne; Sahlin, Simon Lennart

    2014-01-01

    monoxide, the HTPEM fuel cell system can efficiently use a liquid methanol/water mixture of 60%/40% by volume, as fuel instead of compressed hydrogen, enabling potentially a higher volumetric energy density. In order to test the performance of such a system, the experimental validation conducted uses......This work presents the proof-of-concept of an electric traction power system with a high temperature polymer electrolyte membrane fuel cell range extender, usable for automotive class electrical vehicles. The hybrid system concept examined, consists of a power system where the primary power...... is delivered by a lithium ion battery pack. In order to increase the run time of the application connected to this battery pack, a high temperature PEM (HTPEM) fuel cell stack acts as an on-board charger able to charge a vehicle during operation as a series hybrid. Because of the high tolerance to carbon...

  20. Fabrication techniques and stack assembling methods for micro tubular solid oxide fuel cells%微管式固体氧化物燃料电池制备技术及电堆组装工艺

    Institute of Scientific and Technical Information of China (English)

    孟秀霞; 杨乃涛; 尹屹梅; 谭小耀; 马紫峰

    2011-01-01

    微管式固体氧化物燃料电池(MT-SOFC)能显著减小固体氧化物燃料电池(SOFC)的体积,微型化结构使其传质、传热和反应效率明显提高,可实现快速启动与关闭,易于移动和携带.本文概述了微管式固体氧化物燃料电池的结构、关键制备工艺、研究现状、存在问题和应用前景.对电解质支撑型、阳极支撑型及阴极支撑型MT-SOFC结构和性能进行了分析比较,介绍了等静压成型、挤出成型和相转化纺丝法制备陶瓷中空纤维的技术,综述了微管负载型电解质膜技术和微管电池堆组装技术,并对MT-SOFC发展方向及在便携电源、汽车动力电源和微反应器领域的应用进行了展望.%Micro tubular solid oxide fuel cells (MT-SOFCs) have not only the inherent benefits of SOFCs, but exhibit new advantages over conventional SOFCs, such as higher mass transfer/heat transfer, higher reaction efficiency, rapid start-up/shut-down and significantly reduced volume. Therefore, MT-SOFCs show potential applications in portable and mobile power sources. This paper reviews the progress of MT-SOFC studies, focusing on the properties, structures, and fabrications of the cells. The structures and performances of MT-SOFCs supported with electrolyte, anode and cathode respectively are compared and analyzed. The key step for fabrication of MT-SOFCs is the preparation of micro tubes using methods such as isostatic pressing, plastic extrusion and phase inversion spinning methods for hollow fiber ceramics. Preparation of dense electrolyte membrane and assembling of cell stacks are discussed. The challenges and potential applications of MT-SOFCs in portable power sources, electric vehicles and micro reactors are also highlighted.

  1. Test chambers for cell culture in static magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Glinka, Marek, E-mail: mag@iq.pl [Research and Development Centre of Electrical Machines. 188 Rozdzienskiego Street, 40-203 Katowice (Poland); Gawron, Stanisław, E-mail: s.gawron@komel.katowice.pl [Research and Development Centre of Electrical Machines. 188 Rozdzienskiego Street, 40-203 Katowice (Poland); Sieroń, Aleksander, E-mail: sieron1@tlen.pl [Department of Internal Diseases, Angiology and Physical Medicine in Bytom. Medical University of Silesia in Katowice. 15 Batorego Street, 41-902 Bytom (Poland); Pawłowska–Góral, Katarzyna, E-mail: kgoral@sum.edu.pl [Department of Food and Nutrition in Sosnowiec. Medical University of Silesia in Katowice. 8 Jednosci Street, 41-200 Sosnowiec (Poland); Cieślar, Grzegorz, E-mail: cieslar1@tlen.pl [Department of Internal Diseases, Angiology and Physical Medicine in Bytom. Medical University of Silesia in Katowice. 15 Batorego Street, 41-902 Bytom (Poland); Sieroń–Stołtny, Karolina [Department of Internal Diseases, Angiology and Physical Medicine in Bytom. Medical University of Silesia in Katowice. 15 Batorego Street, 41-902 Bytom (Poland)

    2013-04-15

    Article presents a test chamber intended to be used for in vitro cell culture in homogenous constant magnetic field with parametrically variable magnitude. We constructed test chambers with constant parameters of control homeostasis of cell culture for the different parameters of static magnetic field. The next step was the computer calculation of 2D and 3D simulation of the static magnetic field distribution in the chamber. The analysis of 2D and 3D calculations of magnetic induction in the cells' exposition plane reveals, in comparison to the detection results, the greater accuracy of 2D calculations (Figs. 9 and 10). The divergence in 2D method was 2–4% and 8 to 10% in 3D method (reaching 10% only out of the cells′ cultures margins). -- Highlights: ► We present test chamber to be used for in vitro cell culture in static magnetic field. ► The technical data of the chamber construction was presented. ► 2D versus 3D simulation of static magnetic field distribution in chamber was reported. ► We report the accuracy of 2D calculation than 3D.

  2. Pios fuel cell motorcycle in test around the world

    Energy Technology Data Exchange (ETDEWEB)

    Weigl, J.D.; Inayati, I. [Malaysia Technological Univ., Kuala Lumpur (Malaysia). Fuel Cell Vehicle Team; Saidi, H. [Malaysia Technological Univ., Kuala Lumpur (Malaysia)

    2009-07-01

    The Pios fuel cell motorcycle is the latest prototype of a series of hydrogen fuel cell powered vehicles. It was completed in September 2008 at Malaysia's Technological University and has been extensively road tested in the technology class of the South African Solar Challenge 2008. The prototype is now on an endurance journey to be driven in all continents around the world. The paper presented a photo of the motorcycle and discussed the concept, technology and design. The concept was based on a roofed scooter for at least two passengers. The roof provides rain and sun protection. This paper discussed the manufacturing and endurance testing of the motorbike. The portable hydrogen filling station was also discussed. The endurance test results of the fuel cell motorbike were presented with particular reference to efficiency, handling, sitting position, suspension, reliability, maintainability, availability, and drive train variations. It was concluded that the fuel cell motorbike is feasible and reliable, but product maintainability remains to be improved. Costs and infrastructure also require improvement. 9 refs., 14 figs.

  3. Testing of serum atherogenicity in cell cultures: questionable data published

    Directory of Open Access Journals (Sweden)

    Sergei V. Jargin

    2012-01-01

    Full Text Available In a large series of studies was reported that culturing of smooth muscle cells with serum from atherosclerosis patients caused intracellular lipid accumulation, while serum from healthy controls had no such effect. Cultures were used for evaluation of antiatherogenic drugs. Numerous substances were reported to lower serum atherogenicity: statins, trapidil, calcium antagonists, garlic derivatives etc. On the contrary, beta-blockers, phenothiazines and oral hypoglycemics were reported to be pro-atherogenic. Known antiatherogenic agents can influence lipid metabolism and cholesterol synthesis, intestinal absorption or endothelium-related mechanisms. All these targets are absent in cell monocultures. Inflammatory factors, addressed by some antiatherogenic drugs, are also not reproduced. In vivo, relationship between cholesterol uptake by cells and atherogenesis must be inverse rather than direct: in familial hypercholesterolemia, inefficient clearance of LDL-cholesterol by cells predisposes to atherosclerosis. Accordingly, if a pharmacological agent reduces cholesterol uptake by cells in vitro, it should be expected to elevate cholesterol in vivo. Validity of clinical recommendations, based on serum atherogenicity testing in cell monocultures, is therefore questionable. These considerations pertain also to the drugs developed on the basis of the cell culture experiments.

  4. 40 CFR 61.44 - Stack sampling.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Stack sampling. 61.44 Section 61.44 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL... Firing § 61.44 Stack sampling. (a) Sources subject to § 61.42(b) shall be continuously sampled,...

  5. Learning OpenStack networking (Neutron)

    CERN Document Server

    Denton, James

    2014-01-01

    If you are an OpenStack-based cloud operator with experience in OpenStack Compute and nova-network but are new to Neutron networking, then this book is for you. Some networking experience is recommended, and a physical network infrastructure is required to provide connectivity to instances and other network resources configured in the book.

  6. Design, calibration, and operation of 220Rn stack effluent monitoring systems at Argonne National Laboratory.

    Science.gov (United States)

    Munyon, W J; Kretz, N D; Marchetti, F P

    1994-09-01

    A group of stack effluent monitoring systems have been developed to monitor discharges of 220Rn from a hot cell facility at Argonne National Laboratory. The stack monitors use flow-through scintillation cells and are completely microprocessor-based systems. A method for calibrating the stack monitors in the laboratory and in the field is described. A nominal calibration factor for the stack monitoring systems in use is 15.0 cts min-1 per kBq m-3 (0.56 cts min-1 per pCi L-1) +/- 26% at the 95% confidence level. The plate-out fraction of decay products in the stack monitor scintillation cells, without any pre-filtering, was found to be nominally 25% under normal operating conditions. When the sample was pre-filtered upstream of the scintillation cell, the observed cell plate-out fraction ranged from 16-22%, depending on the specific sampling conditions. The instantaneous 220Rn stack concentration can be underestimated or overestimated when the steady state condition established between 220Rn and its decay products in the scintillation cell is disrupted by sudden changes in the monitored 220Rn concentration. For long-term measurements, however, the time-averaged response of the monitor represents the steady state condition and leads to a reasonable estimate of the average 220Rn concentration during the monitoring period.

  7. Non-Small Cell Carcinoma Biomarker Testing: The Pathologist's Perspective.

    Directory of Open Access Journals (Sweden)

    Elisa eBrega

    2014-07-01

    Full Text Available Biomarker testing has become standard of care for patients diagnosed with non-small cell lung cancer. Although it can be successfully performed in circulating tu-mor cells, at present, the vast majority of investigations are carried out using di-rect tumor sampling, either through aspiration methods, which render most often isolated cells, or tissue sampling, that could range from minute biopsies to large resections. Consequently, pathologists play a central role in this process. Recent evidence suggests that refining NSCLC diagnosis might be clinically signifi-cant, particularly in cases of lung adenocarcinomas (ADC, which in turn, has prompted a new proposal for the histologic classification of such pulmonary neo-plasms. These changes, in conjunction with the mandatory incorporation of biomarker testing in routine NSCLC tissue processing, have directly affected the pathologist’s role in lung cancer work-up. This new role pathologists must play is complex and demanding, and requires a close interaction with surgeons, oncologists, radiologists and molecular pathologists. Pathologists often find themselves as the central figure in the coordination of a process, that involves assuring that the tumor samples are properly fixed, but without disruption of the DNA structure, obtaining the proper diagnosis with a minimum of tissue waste, providing pre-analytical evaluation of tumor samples selected for biomarker testing, which includes assessment of the proportion of tumor to normal tissues, as well as cell viability, and assuring that this entire pro-cess happens in a timely fashion. Therefore, it is part of the pathologist’s respon-sibilities to assure that the samples received in their laboratories, be processed in a manner that allows for optimal biomarker testing. This article goal is to discuss the essential role pathologists must play NSCLC bi-omarker testing, as well as to provide a summarized review of the main NSCLC bi-omarkers of

  8. A Time-predictable Stack Cache

    DEFF Research Database (Denmark)

    Abbaspour, Sahar; Brandner, Florian; Schoeberl, Martin

    2013-01-01

    Real-time systems need time-predictable architectures to support static worst-case execution time (WCET) analysis. One architectural feature, the data cache, is hard to analyze when different data areas (e.g., heap allocated and stack allocated data) share the same cache. This sharing leads to less...... precise results of the cache analysis part of the WCET analysis. Splitting the data cache for different data areas enables composable data cache analysis. The WCET analysis tool can analyze the accesses to these different data areas independently. In this paper we present the design and implementation...... of a cache for stack allocated data. Our port of the LLVM C++ compiler supports the management of the stack cache. The combination of stack cache instructions and the hardware implementation of the stack cache is a further step towards timepredictable architectures....

  9. Exact and heuristic solutions to the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann; Archetti, Claudia; Madsen, Oli B.G.;

    The double travelling salesman problem with multiple stacks (DTSPMS) is a pickup and delivery problem where pickups and deliveries are separated, such that all pickup operations are performed before the first delivery takes place. All operations are carried out by one vehicle and no reloading...... is allowed. The vehicle provides several separated (horizontal) stacks/rows for the transportation of the orders, such that each stack is accessed using a LIFO principle, independently of the other stacks. In a real-life setting the dimensions of the problem is 33 orders each consisting of one euro......-pallet, which can be loaded in 3 stacks in a standard 40 foot container. Different exact and heuristic solution approaches to the DTSPMS have been implemented and tested. The exact approaches are based on different mathematical formulations of the problem which are solved using branch-and-cut. One formulation...

  10. Stacking fault probability and stacking fault energy in CoNi alloys

    Institute of Scientific and Technical Information of China (English)

    周伟敏; 江伯鸿; 刘岩; 漆王睿

    2001-01-01

    The stacking fault probability of CoNi alloys with different contents of Ni was measured by X-ray diffraction methods. The results show that the stacking fault decreases with increasing Ni content and with increasing temperature. The thermodynamical calculation has found an equation that can express the stacking fault energy γ of CoNi at temperature T. The phase equilibrium temperature depends on the composition of the certain alloy. The relationship between stacking fault energy γ and stacking fault probability Psf is determined.

  11. From the components to the stack. Developing and designing 5kW HT-PEFC stacks; Von der Komponente zum Stack. Entwicklung und Auslegung von HT-PEFC-Stacks der 5 kW-Klasse

    Energy Technology Data Exchange (ETDEWEB)

    Bendzulla, Anne

    2010-12-22

    The aim of the present project is to develop a stack design for a 5-kW HTPEFC system. First, the state of the art of potential materials and process designs will be discussed for each component. Then, using this as a basis, three potential stack designs with typical attributes will be developed and assessed in terms of practicality with the aid of a specially derived evaluation method. Two stack designs classified as promising will be discussed in detail, constructed and then characterized using short stack tests. Comparing the stack designs reveals that both designs are fundamentally suitable for application in a HT-PEFC system with on-board supply. However, some of the performance data differ significantly for the two stack designs. The preferred stack design for application in a HT-PEFC system is characterized by robust operating behaviour and reproducible high-level performance data. Moreover, in compact constructions (120 W/l at 60 W/kg), the stack design allows flexible cooling with thermal oil or air, which can be adapted to suit specific applications. Furthermore, a defined temperature gradient can be set during operation, allowing the CO tolerance to be increased by up to 10 mV. The short stack design developed within the scope of the present work therefore represents an ideal basis for developing a 5-kW HT-PEFC system. Topics for further research activities include improving the performance by reducing weight and/or volume, as well as optimizing the heat management. The results achieved within the framework of this work clearly show that HTPEFC stacks have the potential to play a decisive role in increasing efficiency in the future, particularly when combined with an on-board supply system. (orig.) [German] Ziel der vorliegenden Arbeit ist die Entwicklung eines Stackkonzeptes fuer ein 5 kW-HT-PEFC System. Dazu wird zunaechst fuer jede Komponente der Stand der Technik moeglicher Materialien und Prozesskonzepte diskutiert. Darauf aufbauend werden drei

  12. In vitro embryotoxicity testing of metals for dental use by differentiation of embryonic stem cell test.

    Science.gov (United States)

    Imai, Koichi; Nakamura, Masaaki

    2006-03-01

    We examined embryotoxicity using the embryonic stem cell test (EST) protocol. Tests were conducted using standard reagents for the atomic absorption measurement of 11 metal ions, silver, cobalt, chromium, copper, mercury, nickel, palladium, antimony, tin, vanadium, and zinc from among metals comprising dental alloys. In addition, for four metals like silver, cobalt, chromium, and nickel, the tests were also conducted using a test solution extracted from powder in the cell culture medium. The embryotoxic potential was obtained from a biostatistics-based prediction model, which was calculated from three endpoints, the ID50, IC50ES and IC(50)3T3. Data with the standard reagents showed that chromium and mercury ions corresponded to class 3, that is, having a strong embryotoxicity, while antimony, tin, and vanadium ions exhibited a weak embryotoxicity. The other metal ions demonstrated no embryotoxicity. On the other hand, when extracts of metal powder in cell culture solutions were used, silver exhibited a weak embryotoxicity while all other metals exhibited no embryotoxicity. In the future, it will be important to clarify the embryotoxicity of the many dental materials that are in use today. In addition, it is necessary to develop substances to ensure they have no toxicity before use in dental applications.

  13. NPS Solar Cell Array Tester Cubesat Flight Testing and Integration

    Science.gov (United States)

    2014-09-01

    them. xvi THIS PAGE INTENTIONALLY LEFT BLANK 1 I. INTRODUCTION A. HISTORY AND MISSION OF NPS-SCAT The Naval Postgraduate School Solar Cell... Luis Obispo, August 2009. [2] D. Sakoda, J. A. Horning, and S. D. Moseley. “Naval Postgraduate School NPSAT1 small satellite,” Naval Postgraduate...Development of CubeSat vibration testing capabilities for the Naval Postgraduate School and Cal Poly San Luis Obispo,” M.S. thesis, Aerospace Engineering

  14. Design and Installation of a Disposal Cell Cover Field Test

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C.H. [University of Wisconsin–Madison, Madison, Wisconsin; Waugh, W.J. [S.M. Stoller Corporation, Grand Junction, Colorado; Albright, W.H. [Desert Research Institute, Reno, Nevada; Smith, G.M. [Geo-Smith Engineering, Grand Junction, Colorado; Bush, R.P. [U.S. Department of Energy, Grand Junction, Colorado

    2011-02-27

    The U.S. Department of Energy’s Office of Legacy Management (LM) initiated a cover assessment project in September 2007 to evaluate an inexpensive approach to enhancing the hydrological performance of final covers for disposal cells. The objective is to accelerate and enhance natural processes that are transforming existing conventional covers, which rely on low-conductivity earthen barriers, into water balance covers, that store water in soil and release it as soil evaporation and plant transpiration. A low conductivity cover could be modified by deliberately blending the upper layers of the cover profile and planting native shrubs. A test facility was constructed at the Grand Junction, Colorado, Disposal Site to evaluate the proposed methodology. The test cover was constructed in two identical sections, each including a large drainage lysimeter. The test cover was constructed with the same design and using the same materials as the existing disposal cell in order to allow for a direct comparison of performance. One test section will be renovated using the proposed method; the other is a control. LM is using the lysimeters to evaluate the effectiveness of the renovation treatment by monitoring hydrologic conditions within the cover profile as well as all water entering and leaving the system. This paper describes the historical experience of final covers employing earthen barrier layers, the design and operation of the lysimeter test facility, testing conducted to characterize the as-built engineering and edaphic properties of the lysimeter soils, the calibration of instruments installed at the test facility, and monitoring data collected since the lysimeters were constructed.

  15. Fabrication of VB2/air cells for electrochemical testing.

    Science.gov (United States)

    Stuart, Jessica; Lopez, Ruben; Lau, Jason; Li, Xuguang; Waje, Mahesh; Mullings, Matthew; Rhodes, Christopher; Licht, Stuart

    2013-08-05

    A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

  16. Assessing corrosion problems in photovoltaic cells via electrochemical stress testing

    Science.gov (United States)

    Shalaby, H.

    1985-01-01

    A series of accelerated electrochemical experiments to study the degradation properties of polyvinylbutyral-encapsulated silicon solar cells has been carried out. The cells' electrical performance with silk screen-silver and nickel-solder contacts was evaluated. The degradation mechanism was shown to be electrochemical corrosion of the cell contacts; metallization elements migrate into the encapsulating material, which acts as an ionic conducting medium. The corrosion products form a conductive path which results in a gradual loss of the insulation characteristics of the encapsulant. The precipitation of corrosion products in the encapsulant also contributes to its discoloration which in turn leads to a reduction in its transparency and the consequent optical loss. Delamination of the encapsulating layers could be attributed to electrochemical gas evolution reactions. The usefulness of the testing technique in qualitatively establishing a reliability difference between metallizations and antireflection coating types is demonstrated.

  17. Development and Testing of Shingle-type Solar Cell Modules

    Science.gov (United States)

    Shepard, N. F., Jr.

    1979-01-01

    The design, development, fabrication and testing of a shingle-type terrestrial solar cell module which produces 98 watts/sq m of exposed module area at 1 kW/sq m insolation and 61 C are reported. These modules make it possible to easily incorporate photovoltaic power generation into the sloping roofs of residential or commercial buildings by simply nailing the modules to the plywood roof sheathing. This design consists of nineteen series-connected 53 mm diameter solar cells arranged in a closely packed hexagon configuration. These cells are individually bonded to the embossed surface of a 3 mm thick thermally tempered hexagon-shaped piece of glass. Polyvinyl butyral is used as the laminating adhesive.

  18. Memory Stacking in Hierarchical Networks.

    Science.gov (United States)

    Westö, Johan; May, Patrick J C; Tiitinen, Hannu

    2016-02-01

    Robust representations of sounds with a complex spectrotemporal structure are thought to emerge in hierarchically organized auditory cortex, but the computational advantage of this hierarchy remains unknown. Here, we used computational models to study how such hierarchical structures affect temporal binding in neural networks. We equipped individual units in different types of feedforward networks with local memory mechanisms storing recent inputs and observed how this affected the ability of the networks to process stimuli context dependently. Our findings illustrate that these local memories stack up in hierarchical structures and hence allow network units to exhibit selectivity to spectral sequences longer than the time spans of the local memories. We also illustrate that short-term synaptic plasticity is a potential local memory mechanism within the auditory cortex, and we show that it can bring robustness to context dependence against variation in the temporal rate of stimuli, while introducing nonlinearities to response profiles that are not well captured by standard linear spectrotemporal receptive field models. The results therefore indicate that short-term synaptic plasticity might provide hierarchically structured auditory cortex with computational capabilities important for robust representations of spectrotemporal patterns.

  19. Pre-stack time migration based on stationary-phase stacking in the dip-angle domain

    Science.gov (United States)

    Xu, Jincheng; Zhang, Hao; Zhang, Jianfeng; Li, Zhengwei; Liu, Wei

    2017-03-01

    The Kirchhoff-type migration approach often suffers from migration noise, aliasing artifacts due to operator error, or weak noise from a truncated aperture or pre-stacked data. These noises can be attenuated by using stationary-phase migration, which only stacks the reflection energy within the Fresnel zone rather than along the whole migration aperture, and therefore obtains a higher signal-to-noise ratio (SNR) for the migration results. This paper proposes a new implementation for the pre-stack time migration (PSTM) approach, which is based on stationary-phase stacking in the dip-angle domain. This implementation generates a pair of migrated dip-angle gathers in the image domain using PSTM. We can obtain the dip-angle field corresponding to the contribution of the Fresnel zones from the migrated dip-angle gathers, which allows us to remove noise outside the Fresnel zones and significantly improves the SNR of the image gathers. The proposed stationary-phase PSTM could effectively handle the problem of low SNR in migrated images, especially in the presence of steeply dipping structures. We test the method by applying stationary-phase PSTM to an overthrust model example and a three-dimensional field data set, and both examples demonstrate that the resulting images are of good quality with the method.

  20. Long Duration Balloon Charge Controller Stack Integration

    Science.gov (United States)

    Clifford, Kyle

    NASA and the Columbia Scientific Balloon Facility are interested in updating the design of the charge controller on their long duration balloon (LDB) in order to enable the charge controllers to be directly interfaced via RS232 serial communication by a ground testing computers and the balloon's flight computer without the need to have an external electronics stack. The design involves creating a board that will interface with the existing boards in the charge controller in order to receive telemetry from and send commands to those boards, and interface with a computer through serial communication. The inputs to the board are digital status inputs indicating things like whether the photovoltaic panels are connected or disconnected; and analog inputs with information such as the battery voltage and temperature. The outputs of the board are 100ms duration command pulses that will switch relays that do things like connect the photovoltaic panels. The main component of this design is a PIC microcontroller which translates the outputs of the existing charge controller into serial data when interrogated by a ground testing or flight computer. Other components involved in the design are an AD7888 12-bit analog to digital converter, a MAX3232 serial transceiver, various other ICs, capacitors, resistors, and connectors.

  1. Corrosion testing of candidates for the alkaline fuel cell cathode

    Science.gov (United States)

    Singer, Joseph; Fielder, William L.

    1989-01-01

    Current/voltage data was obtained for specially made corrosion electrodes of some oxides and of gold materials for the purpose of developing a screening test of catalysts and supports for use at the cathode of the alkaline fuel cell. The data consists of measurements of current at fixed potentials and cyclic voltammograms. These data will have to be correlated with longtime performance data in order to fully evaluate this approach to corrosion screening. Corrosion test screening of candidates for the oxygen reduction electrode of the alkaline fuel cell was applied to two substances, the pyrochlore Pb2Ru2O6.5 and the spinel NiCo2O4. The substrate gold screen and a sample of the IFC Orbiter Pt-Au performance electrode were included as blanks. The pyrochlore data indicate relative stability, although nothing yet can be said about long term stability. The spinel was plainly unstable. For this type of testing to be validated, comparisons will have to be made with long term performance tests.

  2. Performance and Safety Tests on Samsung 18650 Li-ion Cells: Two Cell Designs

    Science.gov (United States)

    Deng, Yi; Jeevarajan, Judith; Rehm, Raymond; Bragg, Bobby; Zhang, Wenlin

    2002-01-01

    In order to meet the applications for space shuttle in future, two types of Samsung cells, with capacity 1800 mAh and 2000 mAh, have been investigated. The studies focused on: (1) Performance tests: completed 250 cycles at various combinations of charge/discharge C rates and discharge capacity measurements at various temperatures; and (2) Safety tests: overcharge and overdischarge, heat abuse, short circuit, internal and external short, and vibration, vacuum, and drop tests

  3. Technology development for phosphoric acid fuel cell powerplant, phase 2

    Science.gov (United States)

    Christner, L.

    1981-01-01

    The development of materials, cell components, and reformers for on site integrated energy systems is described. Progress includes: (1) heat-treatment of 25 sq cm, 350 sq cm and 1200 sq cm cell test hardware was accomplished. Performance of fuel cells is improved by using this material; (2) electrochemical and chemical corrosion rates of heat-treated and as-molded graphite/phenolic resin composites in phosphoric acid were determined; (3) three cell, 5 in. x 15 in. stacks operated for up to 10,000 hours and 12 in. x 17 in. five cell stacks were tested for 5,000 hours; (4) a three cell 5 in. x 15 in. stack with 0.12 mg Pt/sq cm anodes and 0.25 mg Pt/sq cm cathodes was operated for 4,500 hours; and (5) an ERC proprietary high bubble pressure matrix, MAT-1, was tested for up to 10,000 hours.

  4. Butterflies I: morphisms of 2-group stacks

    CERN Document Server

    Aldrovandi, Ettore

    2008-01-01

    Weak morphisms of non-abelian complexes of length 2, or crossed modules, are morphisms of the associated 2-group stacks, or gr-stacks. We present a full description of the weak morphisms in terms of diagrams we call butterflies. We give a complete description of the resulting bicategory of crossed modules, which we show is fibered and biequivalent to the 2-stack of 2-group stacks. As a consequence we obtain a complete characterization of the non-abelian derived category of complexes of length 2. Deligne's analogous theorem in the case of Picard stacks and abelian sheaves becomes an immediate corollary. Commutativity laws on 2-group stacks are also analyzed in terms of butterflies, yielding new characterizations of braided, symmetric, and Picard 2-group stacks. Furthermore, the description of a weak morphism in terms of the corresponding butterfly diagram allows us to obtain a long exact sequence in non-abelian cohomology, removing a preexisting fibration condition on the coefficients short exact sequence.

  5. Hubble Space Telescope solar cell module thermal cycle test

    Science.gov (United States)

    Douglas, Alexander; Edge, Ted; Willowby, Douglas; Gerlach, Lothar

    1992-01-01

    The Hubble Space Telescope (HST) solar array consists of two identical double roll-out wings designed after the Hughes flexible roll-up solar array (FRUSA) and was developed by the European Space Agency (ESA) to meet specified HST power output requirements at the end of 2 years, with a functional lifetime of 5 years. The requirement that the HST solar array remain functional both mechanically and electrically during its 5-year lifetime meant that the array must withstand 30,000 low Earth orbit (LEO) thermal cycles between approximately +100 and -100 C. In order to evaluate the ability of the array to meet this requirement, an accelerated thermal cycle test in vacuum was conducted at NASA's Marshall Space Flight Center (MSFC), using two 128-cell solar array modules which duplicated the flight HST solar array. Several other tests were performed on the modules. The thermal cycle test was interrupted after 2,577 cycles, and a 'cold-roll' test was performed on one of the modules in order to evaluate the ability of the flight array to survive an emergency deployment during the dark (cold) portion of an orbit. A posttest static shadow test was performed on one of the modules in order to analyze temperature gradients across the module. Finally, current in-flight electrical performance data from the actual HST flight solar array will be tested.

  6. New test and characterization methods for PV modules and cells

    Energy Technology Data Exchange (ETDEWEB)

    Van Aken, B.; Sommeling, P. [ECN Solar Energy, Petten (Netherlands); Scholten, H. [Solland, Heerlen (Netherlands); Muller, J. [Moser-Baer, Eindhoven (Netherlands); Grossiord, N. [Holst Centre, Eindhoven (Netherlands); Smits, C.; Blanco Mantecon, M. [Holland Innovative, Eindhoven (Netherlands); Verheijen, M.; Van Berkum, J. [Philips Innovation Services, Eindhoven (Netherlands)

    2012-08-15

    The results of the project geZONd (shared facility for solar module analysis and reliability testing) are described. The project was set up by Philips, ECN, Holst, Solland, OM and T and Holland Innovative. The partners have shared most of their testing and analysis equipment for PV modules and cells, and together developed new or improved methods (including the necessary application know-how). This enables faster and more efficient innovation projects for each partner, and via commercial exploitation for other interested parties. The project has concentrated on five failure modes: corrosion, delamination, moisture ingress, UV irradiation, and mechanical bending. Test samples represented all main PV technologies: wafer based PV and rigid and flexible thin-film PV. Breakthroughs are in very early detection of corrosion, in quantitative characterization of adhesion, in-situ detection of humidity and oxygen inside modules, and ultra-fast screening of materials on UV stability.

  7. Li/SO2 cells and Li/SOCl2 cells: Safe use and testing

    Science.gov (United States)

    Wagner, C. G.

    1992-05-01

    Most lithium/sulfur dioxide (Li/SO2) cells and lithium/thionyl chloride (Li/SOCl2)) cells have pressure relief safety devices called vents built into them. These vents are designed to open under conditions of increasing internal cell pressure. The likelihood of cell venting has been reduced to very low levels by optimizing cell designs. If fully developed Li/SO2 cells or Li/SOCl2 cells (or batteries) are discharged within the intended design limits, they are essentially nonhazardous. In addition, the consequences of cell ventings are being minimized by use of appropriate absorbant materials and protective coatings. During battery assembly and test, detection and monitoring equipment is used to sense the presence of vented gases. Tester data analysis techniques have been developed to foresee either an increasing likelihood of a vent or the presence of a vented cell. Standard cleanup procedures have been developed to safely decontaminate the assembly or test area following a cell vent.

  8. Density of oxidation-induced stacking faults in damaged silicon

    NARCIS (Netherlands)

    Kuper, F.G.; Hosson, J.Th.M. De; Verwey, J.F.

    1986-01-01

    A model for the relation between density and length of oxidation-induced stacking faults on damaged silicon surfaces is proposed, based on interactions of stacking faults with dislocations and neighboring stacking faults. The model agrees with experiments.

  9. 3D porous architecture of stacks of β-TCP granules compared with that of trabecular bone: a microCT, vector analysis and compression study

    Directory of Open Access Journals (Sweden)

    Daniel eCHAPPARD

    2015-10-01

    Full Text Available The 3D arrangement of porous granular biomaterials usable to fill bone defects has received little study. Granular biomaterials occupy 3D space when packed together in a manner that creates a porosity suitable for the invasion of vascular and bone cells. Granules of β-TCP were prepared with either 12.5 or 25g of β-TCP powder in the same volume of slurry. When the granules were placed in a test tube, this produced 3D stacks with a high (HP or low porosity (LP, respectively. Stacks of granules mimic the filling of a bone defect by a surgeon. The aim of this study was to compare the porosity of stacks of β-TCP granules with that of cores of trabecular bone. Biomechanical compression tests were done on the granules stacks. Bone cylinders were prepared from calf tibia plateau, constituted high density (HD blocks. Low density (LD blocks were harvested from aged cadaver tibias. Microcomputed tomography was used on the β-TCP granule stacks and the trabecular bone cores to determine porosity and specific surface. A vector projection algorithm was used to image porosity employing a frontal plane image which was constructed line by line from all images of a microCT stack. Stacks of HP granules had porosity (75.3 ± 0.4% and fractal lacunarity (0.043 ± 0.007 intermediate between that of HD (resp. 69.1 ± 6.4%, p<0.05 and 0.087 ± 0.045, p<0.05 and LD bones (resp. 88.8 ± 1.57% and 0.037 ± 0.014 but exhibited a higher surface density (5.56 ± 0.11 mm2/mm3 vs. 2.06 ± 0.26 for LD, p<0.05. LP granular arrangements created large pores coexisting with dense areas of material. Frontal plane analysis evidenced a more regular arrangement of β-TCP granules than bone trabeculae. Stacks of HP granules represent a scaffold that resembles trabecular bone in its porous microarchitecture.

  10. STREAMLINED APPROACH FOR ENVIRONMENTAL RESTORATION PLAN FOR CORRECTIVE ACTION UNIT 116: AREA 25 TEST CELL C FACILITYNEVADA TEST SITE, NEVADA

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    This Streamlined Approach for Environmental Restoration Plan identifies the activities required for the closure of Corrective Action Unit 116, Area 25 Test Cell C Facility. The Test Cell C Facility is located in Area 25 of the Nevada Test Site approximately 25 miles northwest of Mercury, Nevada.

  11. Refinement of numerical models and parametric study of SOFC stack performance

    Science.gov (United States)

    Burt, Andrew C.

    The presence of multiple air and fuel channels per fuel cell and the need to combine many cells in series result in complex steady-state temperature distributions within Solid Oxide Fuel Cell (SOFC) stacks. Flow distribution in these channels, when non-uniform, has a significant effect on cell and stack performance. Large SOFC stacks are very difficult to model using full 3-D CFD codes because of the resource requirements needed to solve for the many scales involved. Studies have shown that implementations based on Reduced Order Methods (ROM), if calibrated appropriately, can provide simulations of stacks consisting of more than 20 cells with reasonable computational effort. A pseudo 2-D SOFC stack model capable of studying co-flow and counter-flow cell geometries was developed by solving multiple 1-D SOFC single cell models in parallel on a Beowulf cluster. In order to study cross-flow geometries a novel Multi-Component Multi-Physics (MCMP) scheme was instantiated to produce a Reduced Order 3-D Fuel Cell Model. A C++ implementation of the MCMP scheme developed in this study utilized geometry, control volume, component, and model structures allowing each physical model to be solved only for those components for which it is relevant. Channel flow dynamics were solved using a 1-D flow model to reduce computational effort. A parametric study was conducted to study the influence of mass flow distribution, radiation, and stack size on fuel cell stack performance. Using the pseudo 2-D planar SOFC stack model with stacks of various sizes from 2 to 40 cells it was shown that, with adiabatic wall conditions, the asymmetry of the individual cell can produce a temperature distribution where high and low temperatures are found in the top and bottom cells, respectively. Heat transfer mechanisms such as radiation were found to affect the reduction of the temperature gradient near the top and bottom cell. Results from the reduced order 3-D fuel cell model showed that greater

  12. Dynamical Stability of Slip-stacking Particles

    CERN Document Server

    Eldred, Jeffrey

    2014-01-01

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97\\% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  13. Dynamical stability of slip-stacking particles

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-01

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  14. Capping stack: An industry in the making

    Institute of Scientific and Technical Information of China (English)

    Jack Chen; Li Xunke; Xie Wenhui; Kang Yongtian

    2013-01-01

    This paper gives an overview of recent development of the marine well containment system (MWCS)after BP Macondo subsea well blowout occurred on April 20,2010 in the Gulf of Mexico.Capping stack,a hardware utilized to contain blowout well at or near the wellhead is the center piece of MWCS.Accessibility to the dedicated capping stacks is gradually becoming a pre-requirement to obtain the permit for offshore drilling/workover,and the industry for manufacturing,maintenance,transportation and operation of the capping stack is in the making.

  15. Dynamical Stability of Slip-stacking Particles

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, Jeffrey [Fermilab; Zwaska, Robert [Fermilab

    2014-09-04

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  16. Real life testing of a Hybrid PEM Fuel Cell Bus

    Science.gov (United States)

    Folkesson, Anders; Andersson, Christian; Alvfors, Per; Alaküla, Mats; Overgaard, Lars

    Fuel cells produce low quantities of local emissions, if any, and are therefore one of the most promising alternatives to internal combustion engines as the main power source in future vehicles. It is likely that urban buses will be among the first commercial applications for fuel cells in vehicles. This is due to the fact that urban buses are highly visible for the public, they contribute significantly to air pollution in urban areas, they have small limitations in weight and volume and fuelling is handled via a centralised infrastructure. Results and experiences from real life measurements of energy flows in a Scania Hybrid PEM Fuel Cell Concept Bus are presented in this paper. The tests consist of measurements during several standard duty cycles. The efficiency of the fuel cell system and of the complete vehicle are presented and discussed. The net efficiency of the fuel cell system was approximately 40% and the fuel consumption of the concept bus is between 42 and 48% lower compared to a standard Scania bus. Energy recovery by regenerative braking saves up 28% energy. Bus subsystems such as the pneumatic system for door opening, suspension and brakes, the hydraulic power steering, the 24 V grid, the water pump and the cooling fans consume approximately 7% of the energy in the fuel input or 17% of the net power output from the fuel cell system. The bus was built by a number of companies in a project partly financed by the European Commission's Joule programme. The comprehensive testing is partly financed by the Swedish programme "Den Gröna Bilen" (The Green Car). A 50 kW el fuel cell system is the power source and a high voltage battery pack works as an energy buffer and power booster. The fuel, compressed hydrogen, is stored in two high-pressure stainless steel vessels mounted on the roof of the bus. The bus has a series hybrid electric driveline with wheel hub motors with a maximum power of 100 kW. Hybrid Fuel Cell Buses have a big potential, but there are

  17. Analyses of Large Coal-Based SOFCs for High Power Stack Block Development

    Energy Technology Data Exchange (ETDEWEB)

    Recknagle, Kurtis P; Koeppel, Brian J

    2010-10-01

    This report summarizes the numerical modeling and analytical efforts for SOFC stack development performed for the coal-based SOFC program. The stack modeling activities began in 2004, but this report focuses on the most relevant results obtained since August 2008. This includes the latter half of Phase-I and all of Phase-II activities under technical guidance of VPS and FCE. The models developed to predict the thermal-flow-electrochemical behaviors and thermal-mechanical responses of generic planar stacks and towers are described. The effects of cell geometry, fuel gas composition, on-cell reforming, operating conditions, cell performance, seal leak, voltage degradation, boundary conditions, and stack height are studied. The modeling activities to evaluate and achieve technical targets for large stack blocks are described, and results from the latest thermal-fluid-electrochemical and structural models are summarized. Modeling results for stack modifications such as scale-up and component thickness reduction to realize cost reduction are presented. Supporting modeling activities in the areas of cell fabrication and loss of contact are also described.

  18. Contemporary sample stacking in analytical electrophoresis.

    Science.gov (United States)

    Šlampová, Andrea; Malá, Zdena; Pantůčková, Pavla; Gebauer, Petr; Boček, Petr

    2013-01-01

    Sample stacking is a term denoting a multifarious class of methods and their names that are used daily in CE for online concentration of diluted samples to enhance separation efficiency and sensitivity of analyses. The essence of these methods is that analytes present at low concentrations in a large injected sample zone are concentrated into a short and sharp zone (stack) in the separation capillary. Then the stacked analytes are separated and detected. Regardless of the diversity of the stacking electromigration methods, one can distinguish four main principles that form the bases of nearly all of them: (i) Kohlrausch adjustment of concentrations, (ii) pH step, (iii) micellar methods, and (iv) transient ITP. This contribution is a continuation of our previous reviews on the topic and brings an overview of papers published during 2010-2012 and relevant to the mentioned principles (except the last one which is covered by another review in this issue).

  19. The stack on software and sovereignty

    CERN Document Server

    Bratton, Benjamin H

    2016-01-01

    A comprehensive political and design theory of planetary-scale computation proposing that The Stack -- an accidental megastructure -- is both a technological apparatus and a model for a new geopolitical architecture.

  20. Testing Turing’s theory of morphogenesis in chemical cells

    Science.gov (United States)

    Tompkins, Nathan; Li, Ning; Girabawe, Camille; Heymann, Michael; Ermentrout, G. Bard; Epstein, Irving R.; Fraden, Seth

    2014-01-01

    Alan Turing, in “The Chemical Basis of Morphogenesis” [Turing AM (1952) Philos Trans R Soc Lond 237(641):37–72], described how, in circular arrays of identical biological cells, diffusion can interact with chemical reactions to generate up to six periodic spatiotemporal chemical structures. Turing proposed that one of these structures, a stationary pattern with a chemically determined wavelength, is responsible for differentiation. We quantitatively test Turing’s ideas in a cellular chemical system consisting of an emulsion of aqueous droplets containing the Belousov–Zhabotinsky oscillatory chemical reactants, dispersed in oil, and demonstrate that reaction-diffusion processes lead to chemical differentiation, which drives physical morphogenesis in chemical cells. We observe five of the six structures predicted by Turing. In 2D hexagonal arrays, a seventh structure emerges, incompatible with Turing’s original model, which we explain by modifying the theory to include heterogeneity. PMID:24616508

  1. Construction and testing of a hydrogen cracking cell

    Directory of Open Access Journals (Sweden)

    F Sahra Gard

    2011-12-01

    Full Text Available A UHV atomic hydrogen-cracking cell has been constructed to produce atomic hydrogen in order to perform in-situ cleaning of semiconductor samples. The cell was calibrated and tested with the objective of cleaning the III-V semiconductor samples such as GaAs. Mass spectroscopy studies during the atomic hydrogen cleaning of the GaAs samples revealed the chemical process of the hydrogen cleaning. X-ray Photoemission Spectroscopy (XPS was also carried out on the samples at different stages of cleaning. Desorption of the native oxide from GaAs samples resulted in a smooth surface, which was confirmed by Reflection High Energy Electron Diffraction (RHEED.

  2. Stacking fault energy in some single crystals

    Institute of Scientific and Technical Information of China (English)

    Aditya M.Vora

    2012-01-01

    The stacking fault energy of single crystals has been reported using the peak shift method.Presently studied all single crystals are grown by using a direct vapor transport (DVT) technique in the laboratory.The structural characterizations of these crystals are made by XRD.Considerable variations are shown in deformation (α) and growth (β) probabilities in single crystals due to off-stoichiometry,which possesses the stacking fault in the single crystal.

  3. Measuring Structural Parameters Through Stacking Galaxy Images

    Science.gov (United States)

    Li, Yubin; Zheng, Xian Zhong; Gu, Qiu-Sheng; Wang, Yi-Peng; Wen, Zhang Zheng; Guo, Kexin; An, Fang Xia

    2016-12-01

    It remains challenging to detect the low surface brightness structures of faint high-z galaxies, which are key to understanding the structural evolution of galaxies. The technique of image stacking allows us to measure the averaged light profile beneath the detection limit and probe the extended structure of a group of galaxies. We carry out simulations to examine the recovery of the averaged surface brightness profile through stacking model Hubble Space Telescope/Advanced Camera for Surveys images of a set of galaxies as functions of the Sérsic index (n), effective radius (R e) and axis ratio (AR). The Sérsic profile best fitting the radial profile of the stacked image is taken as the recovered profile, in comparison with the intrinsic mean profile of the model galaxies. Our results show that, in general, the structural parameters of the mean profile can be properly determined through stacking, though systematic biases need to be corrected when spreads of R e and AR are counted. We find that the Sérsic index is slightly overestimated and R e is underestimated at {AR}\\lt 0.5 because the stacked image appears to be more compact due to the presence of inclined galaxies; the spread of R e biases the stacked profile to have a higher Sérsic index. We stress that the measurements of structural parameters through stacking should take these biases into account. We estimate the biases in the recovered structural parameters from stacks of galaxies when the samples have distributions of {R}{{e}}, AR and n seen in local galaxies.

  4. Cell-baswd non-invasive prenatal testing

    DEFF Research Database (Denmark)

    Uldbjerg, Niels; Singh, Ripudaman; Christensen, Rikke;

    CONTROL ID: 2520273 ABSTRACT FINAL ID: OC06.03 TITLE: Cell based Non-invasive Prenatal Testing (NIPT) AUTHORS (FIRST NAME, LAST NAME): Niels Uldbjerg2, Ripudaman Singh4, Rikke Christensen3, Palle Schelde4, Ida Vogel1, Else Marie Vestergaard3, Lotte Hatt4, Steen Kølvrå4 INSTITUTIONS (ALL): 1....... Department of Clinical Genetics, Aarhus University Hospital, Aarhus N, none, Denmark. 2. Obstetrics and Gynecology, Aarhus University Hospital Skejby, Aarhus, Denmark. 3. Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark. 4. Arcedi Biotech Aps, Aarhus, Denmark. ABSTRACT BODY: Objectives: NIPT...

  5. Stacking interactions in PUF-RNA complexes

    Energy Technology Data Exchange (ETDEWEB)

    Yiling Koh, Yvonne; Wang, Yeming; Qiu, Chen; Opperman, Laura; Gross, Leah; Tanaka Hall, Traci M; Wickens, Marvin [NIH; (UW)

    2012-07-02

    Stacking interactions between amino acids and bases are common in RNA-protein interactions. Many proteins that regulate mRNAs interact with single-stranded RNA elements in the 3' UTR (3'-untranslated region) of their targets. PUF proteins are exemplary. Here we focus on complexes formed between a Caenorhabditis elegans PUF protein, FBF, and its cognate RNAs. Stacking interactions are particularly prominent and involve every RNA base in the recognition element. To assess the contribution of stacking interactions to formation of the RNA-protein complex, we combine in vivo selection experiments with site-directed mutagenesis, biochemistry, and structural analysis. Our results reveal that the identities of stacking amino acids in FBF affect both the affinity and specificity of the RNA-protein interaction. Substitutions in amino acid side chains can restrict or broaden RNA specificity. We conclude that the identities of stacking residues are important in achieving the natural specificities of PUF proteins. Similarly, in PUF proteins engineered to bind new RNA sequences, the identity of stacking residues may contribute to 'target' versus 'off-target' interactions, and thus be an important consideration in the design of proteins with new specificities.

  6. A critical test of organic P-N photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Bird, G.R. [Rutgers Univ., Piscataway, NJ (United States)

    1996-09-01

    We present an urgent view of the field of organic solid state photovoltaic cells. This is a proper time to select the most promising materials from the Electrophotographic Industry, materials long tried in terms of stability, high quantum yield of charge carriers, but set apart by unusually high quantum yields at low applied fields. Our experience with the candidate dyes has covered new tests for identifiable impurities and removal of these impurities by verifiable methods. A new method of purification, reactive train sublimation, has been developed for DNT, one of the simplest of the outstanding perylene dyes, and the method seems applicable to some of the other promising perylene derivatives. It removes the offending impurity by converting it into the desired pure product. The role of water of hydration in the {open_quotes}wine cellar effect{close_quotes}, the slowly rising performance of newly made phthalocyanine containing cells has been analyzed. Under the concept of feasibility testing before a final refinement for practicality of materials and production methods, the hydration can be controlled for high level testing. At the same time, efforts go forward to eliminate the need. At least one of the best phthalocyanine components, X-H{sub 2}Pc, does not require water for peak performance. Finally, we have attacked BBIP (bis-benzimidazole perylene) one of the best and most enigmatic of the near infrared sensors. It has long been known and used as a mixture of synthetic isomers, and we hypothesize that either of these would be better than the uncontrolled mixture. A partial success in the form of isolating highly enriched crystals for an X-ray structure of the trans-molecule, is first presented here. A simple optical analysis method has been developed to follow enrichment procedures. For all of its difficult history, this material seems closest to a state of readiness for critical feasibility testing.

  7. DIRECT METHANOL FUEL CELLS AT REDUCED CATALYST LOADINGS

    Energy Technology Data Exchange (ETDEWEB)

    P. ZELENAY; F. GUYON; SM. GOTTESFELD

    2001-05-01

    We focus in this paper on the reduction of catalyst loading in direct methanol fuel cells currently under development at Los Alamos National Laboratory. Based on single-cell DMFC testing, we discuss performance vs. catalyst loading trade-offs and demonstrate optimization of the anode performance. We also show test data for a short five-cell DMFC stack with the average total platinum loading of 0.53 mg cm{sup {minus}2} and compare performance of this stack with the performance of a single direct methanol fuel cell using similar total amount of precious metal.

  8. Direct methanol fuel cells at reduced catalyst loadings

    Energy Technology Data Exchange (ETDEWEB)

    Zelenay, P. (Piotr); Guyon, F. (Francois); Gottesfeld, Shimshon

    2001-01-01

    We focus in this paper on the reduction of catalyst loading in direct methanol fuel cells currently under development at Los Alamos National Laboratory. Based on single-cell DMFC testing, we discuss performance vs. catalyst loading trade-offs and demonstrate optimization of the anode performance. We also show test data for a short five-cell DMFC stack with the average total platinum loading of 0.53 mg cm{sup -2} and compare performance of this stack with the performance of a single direct methanol fuel cell using similar total amount of precious metal.

  9. Degree of Polarization and Source Counts of Faint Radio Sources from Stacking Polarized Intensity

    OpenAIRE

    Stil, J. M.; Keller, B. W.; George, S. J.; Taylor, A.R.

    2014-01-01

    We present stacking polarized intensity as a means to study the polarization of sources that are too faint to be detected individually in surveys of polarized radio sources. Stacking offers not only high sensitivity to the median signal of a class of radio sources, but also avoids a detection threshold in polarized intensity, and therefore an arbitrary exclusion of source with a low percentage of polarization. Correction for polarization bias is done through a Monte Carlo analysis and tested ...

  10. Design and fabrication of silver-hydrogen cells

    Science.gov (United States)

    Klein, M. G.

    1975-01-01

    The design and fabrication of silver-hydrogen secondary cells capable of delivering higher energy densities than comparable nickel-cadmium and nickel-hydrogen cells and relatively high cycle life is presented. An experimental task utilizing single electrode pairs for the optimization of the individual electrode components, the preparation of a design for lightweight 20Ahr cells, and the fabrication of four 20Ahr cells in heavy wall test housing containing electrode stacks of the lightweight design are described. The design approach is based on the use of a single cylindrical self-contained cell with a stacked disc sequence of electrodes. The electrode stack design is based on the use of NASA- Astropower Separator Material, PPF fuel cell anodes, an intercell electrolyte reservoir concept and sintered silver electrodes. Results of performance tests are given.

  11. Nonlinear modelling of a SOFC stack by improved neural networks identification

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The solid oxide fuel cell (SOFC) is a nonlinear system that is hard to model by conventional methods. So far, most existing models are based on conversion laws, which are too complicated to be applied to design a control system. To facilitate a valid control strategy design, this paper tries to avoid the internal complexities and presents a modelling study of SOFC performance by using a radial basis function (RBF) neural network based on a genetic algorithm (GA). During the process of modelling, the GA aims to optimize the parameters of RBF neural networks and the optimum values are regarded as the initial values of the RBF neural network parameters. The validity and accuracy of modelling are tested by simulations, whose results reveal that it is feasible to establish the model of SOFC stack by using RBF neural networks identification based on the GA. Furthermore, it is possible to design an online controller of a SOFC stack based on this GA-RBF neural network identification model.

  12. Regenerative Fuel Cells for Space Power and Energy Conversion (NaBH4/H2O2 Fuel Cell Development)

    Science.gov (United States)

    Valdez, Thomas I.; Miley, George H.; Luo, Nie; Burton, Rodney; Mather, Joseph; Hawkins, Glenn; Byrd, Ethan; Gu, Lifeng; Shrestha, Prajakti Joshi

    2006-01-01

    A viewgraph presentation describing hydrogen peroxide and sodium borohydride development is shown. The topics include: 1) Motivation; 2) The Sodium Borohydride Fuel Cell; 3) Fuel Cell Comparisons; 4) MEA Optimization; 5) 500-Watt Stack Testing; 6) System Modeling: Fuel Cell Power Source for Lunar Rovers; and 7) Conclusions

  13. Stabilization of RNA stacking by pseudouridine.

    Science.gov (United States)

    Davis, D R

    1995-01-01

    The effect of the modified nucleoside pseudouridine (psi) on RNA structure was compared with uridine. The extent of base stacking in model RNA oligonucleotides was measured by 1H NMR, UV, and CD spectroscopy. The UV and CD results indicate that the model single-stranded oligoribonucleotides AAUA and AA psi A form stacked structures in solution and the CD results for AA psi A are consistent with a general A-form helical conformation. The AA psi A oligomer exhibits a greater degree of UV hypochromicity over the temperature range 5-55 degrees C, consistent with a better stacked, more A-form structure compared with AAUA. The extent of stacking for each nucleotide residue was inferred from the percent 3'-endo sugar conformation as indicated by the H1'-H2' NMR scalar coupling. This indirect indication of stacking was confirmed by sequential NOE experiments. NMR measurements as a function of temperature indicate that pseudouridine forms a more stable base stacking arrangement than uridine, an effect that is propagated throughout the helix to stabilize stacking of neighboring purine nucleosides. The N1-H imino proton in AA psi A exchanges slowly with solvent, suggesting a role for the extra imino proton in stabilizing the conformation of pseudouridine. These results show that the conformational stabilization is an intrinsic property of pseudouridine occurring at the nucleotide level. The characteristics of pseudouridine in these models are consistent with earlier studies on intact rRNA, indicating that pseudouridine probably performs the same stabilizing function in most structural contexts. PMID:8559660

  14. Polymer electrolyte fuel cell mini power unit for portable application

    Energy Technology Data Exchange (ETDEWEB)

    Urbani, F.; Squadrito, G.; Barbera, O.; Giacoppo, G.; Passalacqua, E. [CNR-ITAE, via Salita S. Lucia sopra Contesse n. 5, 98126 S. Lucia, Messina (Italy); Zerbinati, O. [Universita del Piemonte Orientale, Dip. di Scienze dell' Ambiente e della Vita, via Bellini 25/g, 15100 Alessandria (Italy)

    2007-06-20

    This paper describes the design, realisation and test of a power unit based on a polymer electrolyte fuel cell, operating at room temperature, for portable application. The device is composed of an home made air breathing fuel cell stack, a metal hydride tank for H{sub 2} supply, a dc-dc converter for power output control and a fan for stack cooling. The stack is composed by 10 cells with an active surface of 25 cm{sup 2} and produces a rated power of 15 W at 6 V and 2 A. The stack successfully runs with end-off fed hydrogen without appreciable performance degradation during the time. The final assembled system is able to generate 12 W at 9.5 V, and power a portable DVD player for 3 h in continuous. The power unit has collected about 100 h of operation without maintenance. (author)

  15. Polymer electrolyte fuel cell mini power unit for portable application

    Science.gov (United States)

    Urbani, F.; Squadrito, G.; Barbera, O.; Giacoppo, G.; Passalacqua, E.; Zerbinati, O.

    This paper describes the design, realisation and test of a power unit based on a polymer electrolyte fuel cell, operating at room temperature, for portable application. The device is composed of an home made air breathing fuel cell stack, a metal hydride tank for H 2 supply, a dc-dc converter for power output control and a fan for stack cooling. The stack is composed by 10 cells with an active surface of 25 cm 2 and produces a rated power of 15 W at 6 V and 2 A. The stack successfully runs with end-off fed hydrogen without appreciable performance degradation during the time. The final assembled system is able to generate 12 W at 9.5 V, and power a portable DVD player for 3 h in continuous. The power unit has collected about 100 h of operation without maintenance.

  16. Advances in Metal Supported Cells in the METSOFC EU Consortium

    DEFF Research Database (Denmark)

    McKenna, B. J.; Christiansen, N.; Schauperl, R.;

    2013-01-01

    ). Further success was attained with even larger cell areas of 12 × 12 cm2 squares, which facilitated integration into small stacks at Topsoe Fuel Cell having powers approaching 1/2 kW. Development of MSC stacks showed that the MSCs could achieve similar or better performance, compared to most standard...... industrial anode supported ceramic cells. The best stacked MSCs had power densities approaching 275 mW cm–2 (at 680 °C and 0.8 V). Furthermore, extended testing at AVL determined extra stack performance and reliability characteristics, including behavior toward sulfur and simulated diesel reformate......, and tolerance to thermal cycles and load cycles. These and other key outcomes of the METSOFC consortium are covered, along with associated work supported by the Danish National Advanced Technology Foundation....

  17. The study of portable direct-flame solid oxide fuel cell (DF-SOFC) stack with butane fuel%以丁烷为燃料的便携直接火焰固体氧化物燃料电池堆的研究

    Institute of Scientific and Technical Information of China (English)

    王宇光; 孙良良; 罗凌虹; 吴也凡; 刘丽丽; 石纪军

    2014-01-01

    In this study, a portable direct-flame solid oxide fuel cell ( DF-SOFC ) stack has been demonstrta ed using the conventional butane gas as fuel.The stack is oc nstructed yb bundles of the 3 sni gle cells in a series with conventional Ni/YSZ anode.The fuel cell structure and performance are characterized by scanning electron microscopy ( SEM) and elecrt ochemical workstation, respectively.The er sults show that the stack presents an open cicr uit voltage ( OCV) of about 2.1 V and ano utput power of 0.24 W, which powers an USB fan in 4 h.The cell voltage is quite stable for 4 h, moreover, no cra bno ed positino is found in the anode lya er.This indicates that the DF-SOFC stack can be used for portable applications.%以丁烷液化气为燃料,以固体氧化物燃料电池为电源,可以进行全天候的充电,是未来理想的充电模式。研究了以丁烷为燃料的可以便携的直接火焰燃料电池堆。该电池结构和电性能分别用扫描电子显微镜SEM和电化学工作站进行了表征。该电池堆由3片以Ni/YSZ为阳极支撑形的单电池构成。该电池堆操作开路电压为21.V,最大输出功率为0.24 W,可带动小风扇连续运行超过4h。运行4h后电池阳极没有积炭发生,说明该电池可以连续运行多个小时,可用作便携充电电源。

  18. Molecular dynamics simulations on deformation and fracture of bi-layer graphene with different stacking pattern under tension

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, M.D.; Wang, L. [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China); Wang, C.Y. [Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013 (China); Zhang, Q., E-mail: lxzhangqing@hhu.edu.cn [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China); Ye, S.Y.; Wang, F.Y. [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China)

    2016-02-05

    Based on AIREBO (Adaptive Intermolecular Reactive Empirical Bond Order) potential, molecular dynamics simulations (MDs) are performed to study the mechanical behavior of AB- and AA-stacked bi-layer graphene films (BGFs) under tension. Stress–strain relationship is established and deformation mechanism is investigated via morphology analysis. It is found that AA-stacked BGFs show wavy folds, i.e. the structural instability, and the local structure of AB-stacked BGFs transforms into AA-stacked ones during free relaxation. The values of the Young's modulus obtained for AA-stacked zigzag and armchair BGFs are 797.2 GPa and 727.4 GPa, and those of their AB-stacked counterparts are 646.7 GPa and 603.5 GPa, respectively. In comparison with single-layer graphene, low anisotropy is observed for BGFs, especially AB-stacked ones. During the tensile deformation, hexagonal cells at the edge of BGFs are found to transform into pentagonal rings and the number of such defects increases with the rise of tensile strain. - Highlights: • Molecular dynamics simulations are performed to study the mechanical behavior of AB- and AA-stacked bi-layer graphene films under tension. • Stress–strain relationship is established and deformation mechanism is investigated via morphology analysis. • AA-stacked graphene shows structural instability and the local structure of AB-stacked films transforms into AA-stacked in free relaxation. • Low anisotropy is observed for bi-layer graphene films, especially for AB-stacked ones.

  19. Use of murine embryonic stem cells in embryotoxicity assays: the embryonic stem cell test.

    Science.gov (United States)

    Seiler, Andrea E M; Buesen, Roland; Visan, Anke; Spielmann, Horst

    2006-01-01

    The embryonic stem cell test (EST) takes advantage of the potential of murine embryonic stem (ES) cells to differentiate in culture to test embryotoxicity in vitro. The EST represents a scientifically validated in vitro system for the classification of compounds according to their teratogenic potential based on the morphological analysis of beating cardiomyocytes in embryoid body outgrowths compared to cytotoxic effects on murine ES cells and differentiated 3T3 fibroblasts. Through a number of prevalidation and validation studies, the EST has been demonstrated to be a reliable alternative method for embryotoxicity testing based on the most important mechanisms in embryotoxicity-cytotoxicity and differentiation--as well as on differences in sensitivity between differentiated and embryonic tissues. Improvements of the EST protocol using flow cytometry analysis showed that differential expression of sarcomeric myosin heavy chain and alpha-actinin proteins quantified under the influence of a test compound is a useful marker for detecting potential teratogenicity. The in vitro embryotoxicity test described in this chapter is rapid, simple, and sensitive and can be usefully employed as a component of the risk/hazard assessment process.

  20. EmuStack: An OpenStack-Based DTN Network Emulation Platform (Extended Version

    Directory of Open Access Journals (Sweden)

    Haifeng Li

    2016-01-01

    Full Text Available With the advancement of computing and network virtualization technology, the networking research community shows great interest in network emulation. Compared with network simulation, network emulation can provide more relevant and comprehensive details. In this paper, EmuStack, a large-scale real-time emulation platform for Delay Tolerant Network (DTN, is proposed. EmuStack aims at empowering network emulation to become as simple as network simulation. Based on OpenStack, distributed synchronous emulation modules are developed to enable EmuStack to implement synchronous and dynamic, precise, and real-time network emulation. Meanwhile, the lightweight approach of using Docker container technology and network namespaces allows EmuStack to support a (up to hundreds of nodes large-scale topology with only several physical nodes. In addition, EmuStack integrates the Linux Traffic Control (TC tools with OpenStack for managing and emulating the virtual link characteristics which include variable bandwidth, delay, loss, jitter, reordering, and duplication. Finally, experiences with our initial implementation suggest the ability to run and debug experimental network protocol in real time. EmuStack environment would bring qualitative change in network research works.