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Author : Adam Zev Weber
Publisher :
ISBN 13 :
Total Pages : 880 pages
Book Rating : 4.:/5 (34 download)
Download or read book Modeling Water Management in Polymer-electrolyte Fuel Cells written by Adam Zev Weber and published by . This book was released on 2004 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 205 pages
Book Rating : 4.:/5 (727 download)
Download or read book Modeling Water Management in Polymer-Electrolyte Fuel Cells written by and published by . This book was released on 2007 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cells may become the energy-delivery devices of the 21st century with realization of a carbon-neutral energy economy. Although there are many types of fuel cells, polymerelectrolyte fuel cells (PEFCs) are receiving the most attention for automotive and small stationary applications. In a PEFC, hydrogen and oxygen are combined electrochemically to produce water, electricity, and waste heat. During the operation of a PEFC, many interrelated and complex phenomena occur. These processes include mass and heat transfer, electrochemical reactions, and ionic and electronic transport. Most of these processes occur in the through-plane direction in what we term the PEFC sandwich as shown in Figure 1. This sandwich comprises multiple layers including diffusion media that can be composite structures containing a macroporous gas-diffusion layer (GDL) and microporous layer (MPL), catalyst layers (CLs), flow fields or bipolar plates, and a membrane. During operation fuel is fed into the anode flow field, moves through the diffusion medium, and reacts electrochemically at the anode CL to form hydrogen ions and electrons. The oxidant, usually oxygen in air, is fed into the cathode flow field, moves through the diffusion medium, and is electrochemically reduced at the cathode CL by combination with the generated protons and electrons. The water, either liquid or vapor, produced by the reduction of oxygen at the cathode exits the PEFC through either the cathode or anode flow field. The electrons generated at the anode pass through an external circuit and may be used to perform work before they are consumed at the cathode. The performance of a PEFC is most often reported in the form of a polarization curve, as shown in Figure 2. Roughly speaking, the polarization curve can be broken down into various regions. First, it should be noted that the equilibrium potential differs from the open-circuit voltage due mainly to hydrogen crossover through the membrane (i.e., a mixed potential on the cathode) and the resulting effects of the kinetic reactions. Next, at low currents, the behavior of a PEFC is dominated by kinetic losses. These losses mainly stem from the high overpotential of the oxygen-reduction reaction (ORR). As the current is increased, ohmic losses become a factor in lowering the overall cell potential. These ohmic losses are mainly from ionic losses in the electrodes and separator. At high currents, mass-transport limitations become increasingly important. These losses are due to reactants not being able to reach the electrocatalytic sites. Key among the issues facing PEFCs today is water management. Due to their low operating temperature (
Author : Ugur Pasaogullari
Publisher : Springer Science & Business Media
ISBN 13 : 0387980687
Total Pages : 412 pages
Book Rating : 4.3/5 (879 download)
Download or read book Modeling and Diagnostics of Polymer Electrolyte Fuel Cells written by Ugur Pasaogullari and published by Springer Science & Business Media. This book was released on 2010-07-23 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, presented by leading experts in the field, covers the latest advances in diagnostics and modeling of polymer electrolyte fuel cells, from understanding catalyst layer durability to start-up under freezing conditions.
Author : Reyhan Taspinar
Publisher :
ISBN 13 :
Total Pages : 194 pages
Book Rating : 4.:/5 (958 download)
Download or read book Modeling the Effects of Interfaces on Water Management and Performance of Polymer Electrolyte Fuel Cells written by Reyhan Taspinar and published by . This book was released on 2016 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer electrolyte fuel cells (PEFCs) are of great importance as a clean alternative to conventional heat engines. However, PEFCs need further improvements to be economically utilized in stationary and transport applications. To achieve the highest performance, a delicate water balance in PEFCs must be maintained. The polymer membrane must remain hydrated in order to maximize proton conductivity, while excess liquid water should be removed from the cathode to avoid any flooding issues. This water management issue is hypothesized to be affected by the interfaces of the components. Presently, little is known about the transport through the interfaces and its related effects on the water distribution and performance of the PEFCs. This Ph.D. work addresses this critical gap by exploring the effects of the interfaces on water management and performance of PEFCs through a computational modeling study. The overall objective of this dissertation study is to introduce a modeling framework which incorporates component interfaces in order to evaluate their effects on water transport and performance of PEFCs. To achieve this goal, a series of computational studies were established. First, a 2-D, steady state, multiphase PEFC model for the cathode side was developed. Then, the computational model was integrated with the key interfaces which dominates the overall water transport in PEFCs: (i) the microporous layer (MPL) catalyst layer (CL) interface which governs the mass and ohmic transport losses, (ii) morphologically modified MPL which provides pathways for water transport, and (iii) bipolar plate (BP) gas diffusion layer (GDL) interface where the contact resistance dominates. Using these models, an in-depth understanding of the roles of the interfaces in water transport and performance of PEFCs has been obtained. One of the most important findings is that the interfaces affect the water distribution inside the fuel cell components which leads to a significant drop in the cell performance.
Author : Alhussein Albarbar
Publisher : Springer
ISBN 13 : 3319707272
Total Pages : 172 pages
Book Rating : 4.3/5 (197 download)
Download or read book Proton Exchange Membrane Fuel Cells written by Alhussein Albarbar and published by Springer. This book was released on 2017-11-17 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the characteristics of Proton Exchange Membrane (PEM) Fuel Cells with a focus on deriving realistic finite element models. The book also explains in detail how to set up measuring systems, data analysis, and PEM Fuel Cells’ static and dynamic characteristics. Covered in detail are design and operation principles such as polarization phenomenon, thermodynamic analysis, and overall voltage; failure modes and mechanisms such as permanent faults, membrane degradation, and water management; and modelling and numerical simulation including semi-empirical, one-dimensional, two-dimensional, and three-dimensional models. It is appropriate for graduate students, researchers, and engineers who work with the design and reliability of hydrogen fuel cells, in particular proton exchange membrane fuel cells.
Author :
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (727 download)
Download or read book Modeling Water Content Effects in Polymer Electrolyte Fuel Cells written by and published by . This book was released on 1991 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water content and transport is the key factor in the one-dimensional, steady-state model of a complete polymer electrolyte fuel cell (PEFC) described here. Water diffusion coefficients, electroosmotic drag coefficients, water sorption isotherms, and membrane conductivities, all measured in our laboratory as functions of membrane water content, were used in the model. The model predicts a net-water-per-proton flux ratio of 0.2 H2O/H under typical operating conditions, which is much less than the measured electroosmotic drag coefficient for a fully hydrated membrane. It also predicts an increase in membrane resistance with increased current density and demonstrates the great advantage of thinner membranes in alleviating this resistance problem. Both of these predictions were verified experimentally under certain conditions. We also describe the sensitivity of the water concentration profile and associated observables to variations in the values of some of the transport parameters in anticipation of applying the model to fuel cells employing other membranes. 16 refs., 9 figs.
Author : F. A. Holland
Publisher : Hodder Education
ISBN 13 :
Total Pages : 300 pages
Book Rating : 4.F/5 ( download)
Download or read book Fluid Flow for Chemical Engineers written by F. A. Holland and published by Hodder Education. This book was released on 1973 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: For undergraduates.
Author : Matthew M. Mench
Publisher : Academic Press
ISBN 13 : 0123869366
Total Pages : 474 pages
Book Rating : 4.1/5 (238 download)
Download or read book Polymer Electrolyte Fuel Cell Degradation written by Matthew M. Mench and published by Academic Press. This book was released on 2012 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: For full market implementation of PEM fuel cells to become a reality, two main limiting technical issues must be overcome- cost and durability. This cutting-edge volume directly addresses the state-of-the-art advances in durability within every fuel cell stack component. [...] chapters on durability in the individual fuel cell components -- membranes, electrodes, diffusion media, and bipolar plates -- highlight specific degradation modes and mitigation strategies. The book also includes chapters which synthesize the component-related failure modes to examine experimental diagnostics, computational modeling, and laboratory protocol"--Back cover.
Author : Timothy William Patterson
Publisher :
ISBN 13 :
Total Pages : 382 pages
Book Rating : 4.:/5 (364 download)
Download or read book A Mathematical Model for Water Management in a Polymer Electrolyte Membrane Fuel Cell written by Timothy William Patterson and published by . This book was released on 1996 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Michael Eikerling
Publisher : CRC Press
ISBN 13 : 1439854068
Total Pages : 567 pages
Book Rating : 4.4/5 (398 download)
Download or read book Polymer Electrolyte Fuel Cells written by Michael Eikerling and published by CRC Press. This book was released on 2014-09-23 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a systematic and profound account of scientific challenges in fuel cell research. The introductory chapters bring readers up to date on the urgency and implications of the global energy challenge, the prospects of electrochemical energy conversion technologies, and the thermodynamic and electrochemical principles underlying the op
Author : Christopher David Lee Miller
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (858 download)
Download or read book Liquid Water Dynamics in a Model Polymer Electrolyte Fuel Cell Flow Channel written by Christopher David Lee Miller and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Water management in a polymer electrolyte fuel cell is a critical issue in ensuring high cell performance. The water production, due to both electro-osmotic drag and the chemical reaction, in the cathode side of the fuel cell leads to liquid water formation in the gas diffusion layer and the reactant flow channel. If this water is allowed to accumulate in the fuel cell, the transport of reactants to the membrane assembly will be inhibited and cell performance will suffer. In order to maximize the potential performance of a fuel cell, understanding of the liquid water dynamics is required, and a two-phase flow numerical model has been for this purpose. If an accurate numerical model can be created the development cycle for new flow channel designs can be accelerated. The methodology adopted for the numerical simulation of dynamic two-phase flow is the volume of fluid (VOF) method. The major drawback of current VOF models is in the implementation of the three phase contact line. Current models use a constant static contact angle, which does not take into account real dynamics. This results in non-physical phenomena such as spherical and suspended droplets, instead of the experimentally observed attached semi-spherical droplets with the trailing edge of the droplet forming a tail. To remedy this shortcoming, the implementation of a dynamic contact angle relation is required. The relations used in the current work follows the Hoffman formulation where the dynamic contact angle is obtained as?D. A function of the capillary number, based on the contact line velocity, and of the equilibrium contact angle. The function was implemented within the commercial CFD framework of Fluent using user defined functions. The dynamic contact angle models were able to better predict the droplet dynamics, providing elongated droplet profiles. The dynamic contact angle model was also able to provide more realistic pressure profiles down the channel length. Parametric studies show the dramatic effects that air speed and static contact angle have upon the droplet dynamics. It was also observed that water injection velocity had a relatively small effect on the model. The dynamic contact angle model was found to be consistent with experimental work conducted in our laboratory in which the spinning motion of the fluid within the water droplet was observed [7]. The improved physical representation achieved with the new model results in more reliable simulations and provides a good foundation for the numerical modeling of fuel cell flow channels.
Author : Robert Alink
Publisher :
ISBN 13 : 9783839608173
Total Pages : 159 pages
Book Rating : 4.6/5 (81 download)
Download or read book Water Management in the Porous Transport Layers of PEM Fuel Cells written by Robert Alink and published by . This book was released on 2015-02-10 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Matthew M. Mench
Publisher : John Wiley & Sons
ISBN 13 : 0471689580
Total Pages : 530 pages
Book Rating : 4.4/5 (716 download)
Download or read book Fuel Cell Engines written by Matthew M. Mench and published by John Wiley & Sons. This book was released on 2008-03-07 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel Cell Engines is an introduction to the fundamental principles of electrochemistry, thermodynamics, kinetics, material science and transport applied specifically to fuel cells. It covers scientific fundamentals and provides a basic understanding that enables proper technical decision-making.
Author : Colleen Spiegel
Publisher : Elsevier
ISBN 13 : 0080559018
Total Pages : 454 pages
Book Rating : 4.0/5 (85 download)
Download or read book PEM Fuel Cell Modeling and Simulation Using Matlab written by Colleen Spiegel and published by Elsevier. This book was released on 2011-08-29 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although, the basic concept of a fuel cell is quite simple, creating new designs and optimizing their performance takes serious work and a mastery of several technical areas. PEM Fuel Cell Modeling and Simulation Using Matlab, provides design engineers and researchers with a valuable tool for understanding and overcoming barriers to designing and building the next generation of PEM Fuel Cells. With this book, engineers can test components and verify designs in the development phase, saving both time and money. Easy to read and understand, this book provides design and modelling tips for fuel cell components such as: modelling proton exchange structure, catalyst layers, gas diffusion, fuel distribution structures, fuel cell stacks and fuel cell plant. This book includes design advice and MATLAB and FEMLAB codes for Fuel Cell types such as: polymer electrolyte, direct methanol and solid oxide fuel cells. This book also includes types for one, two and three dimensional modeling and two-phase flow phenomena and microfluidics. *Modeling and design validation techniques *Covers most types of Fuel Cell including SOFC *MATLAB and FEMLAB modelling codes *Translates basic phenomena into mathematical equations
Download or read book Liquid Water Dynamics in a Model Polymer Electrolyte Fuel Cell Flow Channel written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Water management in a polymer electrolyte fuel cell is a critical issue in ensuring high cell performance. The water production, due to both electro-osmotic drag and the chemical reaction, in the cathode side of the fuel cell leads to liquid water formation in the gas diffusion layer and the reactant flow channel. If this water is allowed to accumulate in the fuel cell, the transport of reactants to the membrane assembly will be inhibited and cell performance will suffer. In order to maximize the potential performance of a fuel cell, understanding of the liquid water dynamics is required, and a two-phase flow numerical model has been for this purpose. If an accurate numerical model can be created the development cycle for new flow channel designs can be accelerated. The methodology adopted for the numerical simulation of dynamic two-phase flow is the volume of fluid (VOF) method. The major drawback of current VOF models is in the implementation of the three phase contact line. Current models use a constant static contact angle, which does not take into account real dynamics. This results in non-physical phenomena such as spherical and suspended droplets, instead of the experimentally observed attached semi-spherical droplets with the trailing edge of the droplet forming a tail. To remedy this shortcoming, the implementation of a dynamic contact angle relation is required. The relations used in the current work follows the Hoffman formulation where the dynamic contact angle is obtained as D.A function of the capillary number, based on the contact line velocity, and of the equilibrium contact angle. The function was implemented within the commercial CFD framework of Fluent using user defined functions. The dynamic contact angle models were able to better predict the droplet dynamics, providing elongated droplet profiles. The dynamic contact angle model was also able to provide more realistic pressure profiles down the channel length. Parametric studies show the drama.
Author : Xianguo Li
Publisher : John Wiley & Sons Incorporated
ISBN 13 : 9780470871102
Total Pages : 512 pages
Book Rating : 4.8/5 (711 download)
Download or read book Polymer Electrolyte Membrane Fuel Cells written by Xianguo Li and published by John Wiley & Sons Incorporated. This book was released on 2007-07 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the latest developments in the field, this book provides an up–to–date summary of PEM fuel cell technology and presents the analysis, modeling and simulation of the electrochemical and transport processes. The book explains issues related to performance enhancement and design optimization and discusses the problems of heat and water management in PEM fuel cells. Key features include: researching fuel cells and designing fuel cell systems, this book is also a comprehensive reference for newcomers to the field and advanced university students devoted entirely to the development and applications of polymer electrolyte membrane (PEM) fuel cells provides an essential guide to performance enhancement and design optimization presents the components and configurations of PEM fuel cells. covers the basic principles of operation including electrochemical reactions, the transport of reactants and water discusses carbon monoxide poisoning and mitigation methods also includes illustrative examples and case studies A must have for researchers involved in developing fuel cell systems and designing fuel cell applications. As well as practicing electrical and automotive engineers; industrialists working to develop new fuel cell systems. A useful reference for senior undergraduate and postgraduate students studying fuel cell modules within courses on automotive, chemical or power engineering.
Download or read book Mesoscopic Modeling of Liquid Water Transport in Polymer Electrolyte Fuel Cells written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A key performance limitation in polymer electrolyte fuel cells (PEFC), manifested in terms of mass transport loss, originates from liquid water transport and resulting flooding phenomena in the constituent components. Liquid water leads to the coverage of the electrochemically active sites in the catalyst layer (CL) rendering reduced catalytic activity and blockage of the available pore space in the porous CL and fibrous gas diffusion layer (GDL) resulting in hindered oxygen transport to the active reaction sites. The cathode CL and the GDL therefore playa major role in the mass transport loss and hence in the water management of a PEFC. In this article, we present the development of a mesoscopic modeling formalism coupled with realistic microstructural delineation to study the profound influence of the pore structure and surface wettability on liquid water transport and interfacial dynamics in the PEFC catalyst layer and gas diffusion layer.
