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Design and Optimization of Chromium Getter for SOFC Systems through Computational Modeling

ECS Meeting Abstracts 2017年第1期MA2017-03卷

作者： Md Aman Uddin Charles Joseph Banas Chiying Liang Ugur Pasaogullari Kurt P Recknagle Brian J Koeppel Jeffry W Stevenson Prabhakar Singh Center for Clean Energy Engineering Univ. of Connecticut Dept. of Mechanical Engineering Univ. of Connecticut Materials Science and Engineering UConn Pacific Northwest National Laboratory Materials Science and Engineering Univ. of Connecticut

Chromium poisoning is one of the major causes of cathode degradation in high temperature electrochemical systems such as solid oxide fuel cells, electrolyzers and oxygen transport membranes. Chromium species, evaporating from the chromia forming metallic balance of plant and cell interconnect components, deposit at the exposed electrode surface and triple phase boundaries resulting in irrecoverable performance degradation. Chromium capture approach comprising of the use of non-noble and non- strategic getter materials and conventional ceramic support, currently being developed and tested in our laboratory, will be presented and discussed. Simulation of the chromium getter under nominal SOFC system operating conditions include a single channel with porous region at the wall to simulate the getter coating on cordierite honeycomb support (400 cells per square inch) with a coating thickness of 10µm and 50% porosity. The model is validated against experimental data and utilized to study the effects of the key parameters such as chromium partial pressure, air flow rate, geometric surface area, porosity, and thickness of coating materials.

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In-Cell Chromium Getters to Mitigate Cathode Poisoning in SOFC Stack

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ECS Transactions 2017年第1期78卷

作者： Md Aman Uddin Ashish N Aphale Boxun Hu Ugur Pasaogullari Prabhakar Singh Center for Clean Energy Engineering Univ. of Connecticut Dept. of Mechanical Engineering Univ. of Connecticut Center for Clean Energy Engineering UConn Materials Science and Engineering Univ of Connecticut Materials Science and Engineering Univ. of Connecticut

Incorporation of a porous and electrically conducting chromium getter layer, comprising of a mixture of complex metal oxide getter and electrically conducting perovskite phase, has been examined as a cost-effective approach for the capture of gaseous chromium species originating from the metallic interconnect alloys conventionally used in SOFC stacks. Getter layer deposited on the cathode surface or placed away from the cathode, was electrically tested in a half cell configuration (3%H2O-Air/Pt//YSZ//LSM/Getter/3%H2O-Air-CrOx) at 850 ºC for 100 hours. Post tested cells were analyzed for composition of reaction products and changes in the morphology. Our observations indicate that getter placed away from the cathode and conductive getter paste deposited on cathode surface successfully capture all chromium incoming with air stream thus mitigating the poisoning of the cathode without performance degradation. The gaseous chromium predominantly concentrated at the impinging getter surface and the bulk electrode and electrode-electrolyte interface remained free of chromium.

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In-Cell Chromium Getters to Mitigate Cathode Poisoning in SOFC Stack

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ECS Meeting Abstracts 2017年第1期MA2017-03卷

Incorporation of a porous and electrically conducting chromium getter layer consisting of a mixture of complex metal oxide getter and electrically conducting perovskite phases has been examined as a potential cost effective approach for the capture of gaseous chromium species originating from the metallic interconnect alloys conventionally used in SOFC stacks. Screen printed/ brush coated SrxNiyOz and conventional LSM/LSCF containing porous layer, deposited on the cathode surface, was electrically tested in a half cell configuration (3%H2O-Air/Pt//YSZ//LSM/Getter/3% H2O-Air-CrOx) at 850 °C for 100 hours. Cell current at 0.5 V bias was monitored and electrochemical impedance spectra (EIS) in frequency range of 0.5 Hz to 200 kHz were obtained at 1-hour interval with 10 mV sinusoidal amplitude. Post tested cells were analyzed for chromium concentration profile, reaction products chemistry and morphological changes. Our observations indicate that the gaseous chromium predominantly concentrates in the getter layer. The bulk electrode and electrode-electrolyte interface remain free of chromium. The electrical performance remains largely stable as evidenced by I-t and EIS data obtained during the test. Experimental details and results will be presented and discussed.

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An overview of the NIST FIBERS roadmap to advance the state of composites manufacturing in the U.S. 31

An overview of the NIST FIBERS roadmap to advance the state ...

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31st Annual Technical Conference of the American Society for Composites, ASC 2016

作者： Sherwood, J. Hansen, C. Drane, P. Gorczyca, J. White, K. Reynaud, E. Walczyk, D. Advani, S. Dayal, V. Overcash, M. Kinsey, B. Gross, T. Lashmore, D. Tsukrov, I. Nutt, S. Boeman, R. Dobbins, T. Coughlin, D. Schoenberg, A. Von Vogt, S. Dept. of Mechanical Engineering U. of Massachusetts Lowell LowellMA01854 United States Rensselaer Polytechnic Institute School of Engineering TroyNY12180 United States Dept. of Mechanical Engineering U. of Delaware NewarkDE19716 United States Dept. of Aerospace Engineering Iowa State U. AmesIA50011 United States Environmental Clarity RaleighNC27607 United States Dept. of Mechanical Engineering U. of New Hampshire DurhamNH03824 United States Dept. of Chemical Engineering and Materials Science U. of Southern California Los AngelesCA90089 United States Michigan48216 United States American Composites Manufacturers Association ArlingtonVA22201 United States Maine Composites Alliance PortlandME04112 United States

ISBN: (纸本)9781605953168

The FIBERS (Facilitating Industry By engineering Roadmapping and science) roadmap encompasses all sectors of composites manufacturing and will be a valuable tool to assist in developing pathways that can lead to new and expanded markets for composites and to guide future calls for research programs on composites manufacturing. This paper summarizes the current state-of-the-art, drivers and barriers for five topical areas associated with the U.S. Composites Manufacturing industry and actions that can be taken to address the associated barriers. The major topics presented include (1) materials, (2) Processing methods, (3) Recycling, (4) Predictive models and (5) Workforce development.

关键词： Industrial research

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Low-Temperature Chromium Poisoning of SOFC Cathode

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ECS Meeting Abstracts 2017年第1期MA2017-03卷

作者： Su Jeong Heo Boxun Hu Ashish N Aphale Md Aman Uddin Prabhakar Singh Materials Science & Engineering Univ. of Connecticut Center for Clean Energy Engineering Univ. of Connecticut Center for Clean Energy Engineering UConn Material Science & Engineering Univ. of Connecticut Dept. of Mechanical Engineering Univ. of Connecticut

Low-Temperature Solid Oxide Fuel Cells (LT-SOFCs), operating in 500-700 °C temperature range on fossil derived hydrocarbon fuels, are widely viewed as the 'next generation' of clean and efficient electrochemical power generation technology that may also remain prone to gaseous chromium assisted cathode poisoning. Chromium poisoning of strontium doped lanthanum manganite (LSM) and lanthanum strontium cobalt ferrite (LSCF) cathodes have been studied in half-cell configuration at 650 °C in gaseous chromium vapor containing humidified air. The electrochemical performance of LSM/YSZ/Pt half-cell shows faster degradation in chromium containing air with a rapid change in the polarization resistance compared to LSCF/GDC/Pt half-cell. Electrode chemistry, morphology and elemental distribution have been studied using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX) and X-ray Diffraction (XRD) techniques. A thermodynamic analysis of the degradation process was also conducted. Our observations show that lowering of cell operating temperature may not significantly lower the cell performance degradation. Possible approaches for mitigating above degradation will be discussed.

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Low-Temperature Chromium Poisoning of SOFC Cathode

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ECS Transactions 2017年第1期78卷

Chromium poisoning of SOFC cathode has been studied at 650 °C utilizing an electrochemical half-cell configuration (Air-3%H2O-CrOxHy /LSM//YSZ/Ag/Air). While the cell performance and electrode impedance show continued improvement with time under standard conditions (3% H2O-air), cell performance degrades rapidly in the presence of gaseous chromium as indicated by increase in the electrode polarization and reduction in the current with time. Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) analyses for the cell exposed to chromium vapor shows chromium deposition on the cathode/electrolyte interface, no chromium was detected on the cathode surface and the interface of the cathode/electrolyte for the standard cell. Calculated equilibrium vapor pressures of chromium vapor species formed from pure chromium oxide (Cr2O3) under flowing humidified air (3% H2O-air) show that the partial pressure of major chromium specie namely CrO2(OH)2 at low temperature still remains appreciable and a cause for concern during long term operation of low-temperature SOFC.

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The association among injury metrics for different events in ice hockey goaltender impacts

The association among injury metrics for different events in...

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2016 International Research Council on the Biomechanics of Injury, IRCOBI 2016

作者： Clark, James Michio Post, Andrew Hoshizaki, Thomas Blaine Gilchrist, Michael D. University College Dublin Ireland Children's Hospital of Eastern Ontario University of Ottawa Neurotrauma Impact Science Laboratory Ottawa Canada Dept. of Human Kinetics University of Ottawa Canada School of Mechanical and Materials Engineering University College Dublin Ireland

Current ice hockey goaltender helmet standards use a drop test and peak linear acceleration to evaluate performance. However, ice hockey goaltenders are exposed to impacts from collisions, falls and pucks which each create unique loading conditions. As a result, the use of peak linear acceleration as a predictor for brain trauma in current ice hockey standards may not be most appropriate. The purpose of this study was to determine how kinematic response measures correlate to maximum principal strain and von Mises stress for different impact events. A NOCSAE headform was fitted with three ice hockey goaltender helmet models and impacted under conditions representing these three different impact events (fall, puck, collision). Peak resultant linear acceleration, rotational acceleration and rotational velocity of the headform were measured. Resulting accelerations were input into the University College Dublin Brain Trauma Model, which calculated maximum principal strain and von Mises stress in the cerebrum. The results demonstrated that the relationship between injury metrics in ice hockey goaltender impacts is dependent on the impact event and velocity. As a result of these changing relationships, the inclusion of finite element analysis in test protocols may provide a more practical representation of brain loading in evaluating the performance of ice hockey goaltender helmets.

关键词： Acceleration

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A low-cost, open-source, compliant hand for enabling sensorimotor control for people with transradial amputations

A low-cost, open-source, compliant hand for enabling sensori...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Aadeel Akhtar Kyung Yun Choi Michael Fatina Jesse Cornman Edward Wu Joseph Sombeck Chris Yim Patrick Slade Jason Lee Jack Moore Daniel Gonzales Alvin Wu Garrett Anderson David Rotter Cliff Shin Timothy Bretl Neuroscience Program and Medical Scholars Program Dept. of Aerospace Engineering Dept. of Electrical & Computer Engineering Dept. of Mechanical Science & Engineering Rehabilitation Counseling Program Center for Wounded Veterans Scheck & Siress Prosthetics Orthotics Chicago IL USA Industrial Design Program University of Illinois at Urbana-Champaign Urbana IL USA

In this paper, we describe the design and implementation of a low-cost, open-source prosthetic hand that enables both motor control and sensory feedback for people with transradial amputations. We integrate electromyographic pattern recognition for motor control along with contact reflexes and sensory substitution to provide feedback to the user. Compliant joints allow for robustness to impacts. The entire hand can be built for around $550. This low cost makes research and development of sensorimotor prosthetic hands more accessible to researchers worldwide, while also being affordable for people with amputations in developing nations. We evaluate the sensorimotor capabilities of our hand with a subject with a transradial amputation. We show that using contact reflexes and sensory substitution, when compared to standard myoelectric prostheses that lack these features, improves grasping of delicate objects like an eggshell and a cup of water both with and without visual feedback. Our hand is easily integrated into standard sockets, facilitating long-term testing of sensorimotor capabilities.

关键词： Visualization Grasping Electromyography Sockets Motor drives Pattern recognition Prosthetics

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Simultaneous Millimeter-wave, Gamma-ray, and Optical Monitoring of the Blazar PKS 2326-502 During a Flaring State

arXiv

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arXiv 2023年

作者： Hood, J.C. Simpson, A. McDaniel, A. Foster, A. Ade, P.A.R. Ajello, M. Anderson, A.J. Austermann, J.E. Beall, J.A. Bender, A.N. Benson, B.A. Bianchini, F. Bleem, L.E. Carlstrom, J.E. Chang, C.L. Chaubal, P. Chiang, H.C. Chou, T.-L. Citron, R. Corbett Moran, C. Crawford, T.M. Crites, A.T. De Haan, T. Dobbs, M.A. Everett, W. Gallicchio, J. George, E.M. Gupta, N. Halverson, N.W. Hilton, G.C. Holder, G.P. Holzapfel, W.L. Hrubes, J.D. Huang, N. Hubmayr, J. Irwin, K.D. Knox, L. Lee, A.T. Li, D. Lowitz, A. Madejski, G. Malkan, M. McMahon, J.J. Meyer, S.S. Montgomery, J. Natoli, T. Nibarger, J.P. Noble, G. Novosad, V. Omori, Y. Padin, S. Patil, S. Pryke, C. Reichardt, C.L. Ruhl, J.E. Saliwanchik, B.R. Schaffer, K.K. Sievers, C. Smecher, G. Stark, A.A. Tucker, C. Veach, T. Vieira, J.D. Wang, G. Whitehorn, N. Wu, W.L.K. Yefremenko, V. Zebrowski, J.A. Zhang, L. Kavli Institute for Cosmological Physics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Astronomy and Astrophysics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Physics and Astronomy Vanderbilt University NashvilleTN37235 United States Department of Physics Rensselaer Polytechnic Institute TroyNY12180 United States Department of Physics and Astronomy Clemson University ClemsonSC29631 United States Department of Physics Case Western Reserve University ClevelandOH44106 United States Cardiff University CardiffCF10 3XQ United Kingdom Fermi National Accelerator Laboratory MS209 P.O. Box 500 BataviaIL60510 United States Nist Quantum Devices Group 325 Broadway Mailcode 817.03 BoulderCO80305 United States Department of Physics University of Colorado BoulderCO80309 United States High Energy Physics Division Argonne National Laboratory 9700 S. Cass Avenue ArgonneIL60439 United States School of Physics University of Melbourne VIC Parkville3010 Australia Department of Physics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Enrico Fermi Institute University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Physics McGill University 3600 Rue University QC MontrealH3A 2T8 Canada School of Mathematics Statistics & Computer Science University of KwaZulu-Natal Durban South Africa University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Tapir Walter Burke Institute for Theoretical Physics California Institute of Technology 1200 E California Blvd PasadenaCA91125 United States Dunlap Institute for Astronomy & Astrophysics University of Toronto 50 St George St ON TorontoM5S 3H4 Canada Department of Astronomy & Astrophysics University of Toronto 50 St George St ON TorontoM5S 3H4 Canada Ibaraki Tsukuba305-0801 Japan Ibaraki Tsukuba305-0801 Japan Canadian Institute f

Including millimeter-wave (mm-wave) data in multi-wavelength studies of the variability of active galactic nuclei (AGN) can provide insights into AGN physics that are not easily accessible at other wavelengths. We demonstrate in this work the potential of cosmic microwave background (CMB) telescopes to provide long-term, high-cadence mm-wave AGN monitoring over large fractions of sky. We report on a pilot study using data from the SPTpol instrument on the South Pole Telescope (SPT), which was designed to observe the CMB at arcminute and larger angular scales. Between 2013 and 2016, SPTpol was used primarily to observe a single 500 deg2field, covering the entire field several times per day with detectors sensitive to radiation in bands centered at 95 and 150 GHz. We use SPT 150 GHz observations to create AGN light curves, and we compare these mm-wave light curves to those at other wavelengths, in particular γ-ray and optical. In this Letter, we focus on a single source, PKS 2326-502, which has extensive, day-timescale monitoring data in gamma-ray, optical, and now mm-wave between 2013 and 2016. We find PKS 2326-502 to be in a flaring state in the first two years of this monitoring, and we present a search for evidence of correlated variability between mm-wave, optical R band, and γ-ray observations. This pilot study is paving the way for AGN monitoring with current and upcoming CMB experiments such as SPT-3G, Simons Observatory, and CMB-S4, including multi-wavelength studies with facilities such as VRO-LSST. © 2023, CC BY.

关键词： Active Galactic Nuclei

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Surface morphology and flammability of two flame resistant fibers and their blended nonwoven fabrics

Surface morphology and flammability of two flame resistant f...

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SAMPE Long Beach 2016 Conference and Exhibition

作者： Yao, Lan Koo, Joseph H. Wu, Hao Krifa, Mourad Donghua University Department of High-tech Textiles College of Textiles No. 2999 North Renmin Road Shanghai201620 China University of Texas at Austin Dept. of Mechanical Engineering 204 E. Dean Keeton-C2200 AustinTX78712 United States Materials Science and Engineering Materials and Science Program University of Texas at Austin AustinTX78712 United States School of Human Ecology-Textile and Apparel Technology University of Texas at Austin A270 AustinTX78712 United States

ISBN: (纸本)9781934551233

Protective clothing is essential for fire and heat protection in numerous professions. Instead of using flame resistant (FR) fabric finishing, the inherently FR fibers can be considered due to their long wear-life and durability. In this study, polybenzimidazole (PBI) fiber and Lenzing FR® fiber were selected to form FR nonwoven fabrics. The fiber surface structures were observed by Scanning Electron Microscopy (SEM) showing different structures for the two types of fibers. Typical flammability parameters including heat release rate (HRR) and heat release capacity (HRC) were tested for the two fibers using the Microscale Combustion Calorimeter (MCC). Both PBI and Lenzing FR® fibers show their high flame and heat resistance properties using MCC. In addition, the 20/80 PBI/Lenzing FR® blended nonwoven fabric was designed, fabricated, and tested. In general, the measured HRR results from MCC test showed relatively good agreement with the calculated peaks of Lenzing FR® and PBI fibers, showing the rule of mixtures for the HRRs for the blending fabrics. In the flame resistance test, the after-flame time of the fabric from the test is approximately 0.5s. The mean value of the char length of the as-received fabric is 3.8±0.89 inches. No melting or dripping were observed during the combustion. Copyright 2016. Used by the Society of the Advancement of Material and Process engineering with permission.

关键词： Fibers

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