A Microstructure-Driven Approach to Characterize Transport Phenomena in Porous Media of Polymer Electrolyte Fuel Cells PDF Download
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Author: Eric Wargo
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 322
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Book Description
The polymer electrolyte fuel cell (PEFC) is an electrochemical device which holds great promise as an alternative power source for use in a wide range of applications. However, improvements in cell performance are necessary for the commercialization of PEFCs. Recently, significant research effort has been placed on understanding the influence of the internal structure (i.e., microstructure) of fuel cell materials on the transport of water and reactant gases in PEFC systems. One component of interest is the porous diffusion media (DM), which has been shown to be vital for achieving necessary water management to maintain efficient fuel cell operation. However, current modeling efforts rely primarily on bulk correlations or idealized/randomly selected structures for these porous materials, which may misrepresent the true morphology of the DM and potentially fail to accurately capture the related effects on transport within this component. The objective of this dissertation work is to establish a framework which combines recent advances in 3-D microstructure quantification and pore-scale analysis to evaluate the structure and related transport characteristics of fuel cell DM. The presented framework includes the following features: i) the microstructures of the materials of interest are quantified rigorously in 3-D; ii) small representative volume elements (RVEs) are selected which capture the important features of the measured microstructure datasets to within high accuracy, for reliable and computationally efficient modeling of transport behavior; and iii) a suite of microstructure analysis tools is developed to determine several difficult-to-measure key structure-related transport properties. Using this approach, an in-depth understanding of the structure-related transport characteristics of a fuel cell DM sample is achieved.
Author: Eric Wargo
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 322
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Book Description
The polymer electrolyte fuel cell (PEFC) is an electrochemical device which holds great promise as an alternative power source for use in a wide range of applications. However, improvements in cell performance are necessary for the commercialization of PEFCs. Recently, significant research effort has been placed on understanding the influence of the internal structure (i.e., microstructure) of fuel cell materials on the transport of water and reactant gases in PEFC systems. One component of interest is the porous diffusion media (DM), which has been shown to be vital for achieving necessary water management to maintain efficient fuel cell operation. However, current modeling efforts rely primarily on bulk correlations or idealized/randomly selected structures for these porous materials, which may misrepresent the true morphology of the DM and potentially fail to accurately capture the related effects on transport within this component. The objective of this dissertation work is to establish a framework which combines recent advances in 3-D microstructure quantification and pore-scale analysis to evaluate the structure and related transport characteristics of fuel cell DM. The presented framework includes the following features: i) the microstructures of the materials of interest are quantified rigorously in 3-D; ii) small representative volume elements (RVEs) are selected which capture the important features of the measured microstructure datasets to within high accuracy, for reliable and computationally efficient modeling of transport behavior; and iii) a suite of microstructure analysis tools is developed to determine several difficult-to-measure key structure-related transport properties. Using this approach, an in-depth understanding of the structure-related transport characteristics of a fuel cell DM sample is achieved.
Author: Bengt Sundén
Publisher: WIT Press
ISBN: 1853128406
Category : Technology & Engineering
Languages : en
Pages : 385
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Book Description
Fuel cells are expected to play a significant role in the next generation of energy systems and road vehicles for transportation. However, substantial progress is required in reducing manufacturing costs and improving performance. This book aims to contribute to the understanding of the transport processes in solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC), which are of current interest. A wide range of topics is covered, featuring contributions from prominent scientists and engineers in the field. A detailed summary of state-of-the-art knowledge and future needs, this text will be of value to graduate students and researchers working on the development of fuel cells within academia and industry.
Author: Christoph Hartnig
Publisher: Elsevier
ISBN: 0857095471
Category : Technology & Engineering
Languages : en
Pages : 437
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Book Description
Polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) technology are promising forms of low-temperature electrochemical power conversion technologies that operate on hydrogen and methanol respectively. Featuring high electrical efficiency and low operational emissions, they have attracted intense worldwide commercialization research and development efforts. These R&D efforts include a major drive towards improving materials performance, fuel cell operation and durability. In situ characterization is essential to improving performance and extending operational lifetime through providing information necessary to understand how fuel cell materials perform under operational loads.This two volume set reviews the fundamentals, performance, and in situ characterization of PEMFCs and DMFCs. Volume 1 covers the fundamental science and engineering of these low temperature fuel cells, focusing on understanding and improving performance and operation. Part one reviews systems fundamentals, ranging from fuels and fuel processing, to the development of membrane and catalyst materials and technology, and gas diffusion media and flowfields, as well as life cycle aspects and modelling approaches. Part two details performance issues relevant to fuel cell operation and durability, such as catalyst ageing, materials degradation and durability testing, and goes on to review advanced transport simulation approaches, degradation modelling and experimental monitoring techniques.With its international team of expert contributors, Polymer electrolyte membrane and direct methanol fuel cell technology Volumes 1 & 2 is an invaluable reference for low temperature fuel cell designers and manufacturers, as well as materials science and electrochemistry researchers and academics. - Covers the fundamental science and engineering of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), focusing on understanding and improving performance and operation - Reviews systems fundamentals, ranging from fuels and fuel processing, to the development of membrane and catalyst materials and technology, and gas diffusion media and flowfields, as well as life cycle aspects and modelling approaches - Details performance issues relevant to fuel cell operation and durability, such as catalyst ageing, materials degradation and durability testing, and reviews advanced transport simulation approaches, degradation modelling and experimental monitoring techniques
Author: Matthew M. Mench
Publisher: Academic Press
ISBN: 0123869366
Category : Technology & Engineering
Languages : en
Pages : 474
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Book Description
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: Joshua Scott Preston
Publisher:
ISBN:
Category :
Languages : en
Pages : 130
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Book Description
Author: Zahra Tayarani Yoosefabadi
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
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Book Description
Polymer electrolyte fuel cells (PEFCs), as promising clean energy power sources, are potential substitutes not only for stationary power generation but also for mobile applications specifically in transportation due to their high power density and performance as well as lack of pollutants. PEFC vehicles are at the dawn of commercialization, but still, cost, performance, and durability of current PEFCs need to be further improved to facilitate vast market integration especially under high current density conditions. Pursuant to this goal, comprehensive multidisciplinary understanding of multiphase transport of mass, heat, and electricity in the PEFC constituents including the gas diffusion layer (GDL), as the centerpiece of this thesis, will help to make progress towards material optimization and subsequently fuel cell performance improvements. The GDL transport capability is determined by its effective transport properties which are strongly dependent on its morphological, microstructural, and physical characteristics. Therefore, accurate knowledge regarding the correlation between the GDL microstructure and its transport properties is essential for improving the performance and durability of PEFCs as well as for material optimization, fuel cell design, and prototyping in the area of fuel cell development and manufacturing. In this context, this thesis aims to develop a fast and cost-effective design tool for GDL microstructural modeling and transport properties simulation. Given the limitations of experimental, analytical, and tomographic techniques, stochastic microstructural model development to retrieve the heterogeneous GDL microstructure is a more reliable and flexible tool for GDL material design and prototyping assignments to reduce cost and time of the design cycle. Inspired by the randomness of the GDL porous media structure and its fabrication process, the GDL microstructure is virtually reconstructed as a collection of stochastic processes to provide a robust representation of the structure. The technique of stochastic microstructural reconstruction relies on statistical correlation functions which describe the probabilities of the porous media constituents' distribution and aim to encompass all the details of the porous media. The obtained 3D digitized realizations of the stochastic model are then used as a domain for numerical computation of transport properties. In this thesis, a unique stochastic GDL microstructural modeling framework inspired by manufacturing information and characterization data is developed in which all GDL substrate and MPL components are resolved, and thoroughly validated with literature and measured data for a variety of MPL-coated GDLs. The effects of PTFE loading and liquid water saturation on the GDL substrate anisotropic transport properties for both gas and liquid phases are found to be highly coupled and are therefore simulated and analyzed jointly. Furthermore, a parametric study is conducted to investigate the effect of MPL pore morphology composition on the MPL and MPL-coated GDL transport properties. The validated stochastic design tool can be used as a fast and accurate framework for reconstructing GDL porous materials and understanding the correlation between the GDL morphology and transport properties. This paves the way for development of improved GDL materials with desired transport properties in modern PEFCs.
Author: Alejandro A. Franco
Publisher: CRC Press
ISBN: 9814364401
Category : Science
Languages : en
Pages : 608
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Book Description
This book focuses on the recent research progress on the fundamental understanding of the materials degradation phenomena in PEFC, for automotive applications. On a multidisciplinary basis, through contributions of internationally recognized researchers in the field, this book provides a complete critical review on crucial scientific topics related
Author: Christoph Hartnig
Publisher: Elsevier
ISBN: 085709548X
Category : Technology & Engineering
Languages : en
Pages : 522
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Book Description
Polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) technology are promising forms of low-temperature electrochemical power conversion technologies that operate on hydrogen and methanol respectively. Featuring high electrical efficiency and low operational emissions, they have attracted intense worldwide commercialization research and development efforts. These R&D efforts include a major drive towards improving materials performance, fuel cell operation and durability. In situ characterization is essential to improving performance and extending operational lifetime through providing information necessary to understand how fuel cell materials perform under operational loads.Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology, Volume 2 details in situ characterization, including experimental and innovative techniques, used to understand fuel cell operational issues and materials performance. Part I reviews enhanced techniques for characterization of catalyst activities and processes, such as X-ray absorption and scattering, advanced microscopy and electrochemical mass spectrometry. Part II reviews characterization techniques for water and fuel management, including neutron radiography and tomography, magnetic resonance imaging and Raman spectroscopy. Finally, Part III focuses on locally resolved characterization methods, from transient techniques and electrochemical microscopy, to laser-optical methods and synchrotron radiography.With its international team of expert contributors, Polymer electrolyte membrane and direct methanol fuel cell technology will be an invaluable reference for low temperature fuel cell designers and manufacturers, as well as materials science and electrochemistry researchers and academics. Polymer electrolyte membrane and direct methanol fuel cell technology is an invaluable reference for low temperature fuel cell designers and manufacturers, as well as materials science and electrochemistry researchers and academics. - Details in situ characterisation of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), including the experimental and innovative techniques used to understand fuel cell operational issues and materials performance - Examines enhanced techniques for characterisation of catalyst activities and processes, such as X-ray absorption and scattering, advanced microscopy and electrochemical mass spectrometry - Reviews characterisation techniques for water and fuel management, including neutron radiography and tomography, and comprehensively covers locally resolved characterisation methods, from transient techniques to laser-optical methods
Author: Jian Zhao
Publisher:
ISBN:
Category : Fuel cells
Languages : en
Pages : 171
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Book Description
The structure of the catalyst layers (CLs) has a decisive impact on the performance, durability, and cost of polymer electrolyte membrane (PEM) fuel cells - these are the main technical challenges to the commercialization of PEM fuel cells. The porous CL conventionally consists of carbon-based platinum (Pt/C) and ionomer (Nafion polymer). An ideal CL should maintain the desired structure with sufficient gas diffusion and water removal channels (pores), proton transport media (ionomer), electron travel pathways (catalyst particles), and optimal three-phase boundaries (TPBs) where electrochemical reaction occurs (reaction sites). Practically, the CL is formed during the fabrication process which determines the physical structures, often represented by porosity, mean pore size, pore size distribution (PSD) and specific surface area. The physical structures, in turn, determine the effective transport properties such as effective mass diffusion coefficient and permeability for the reactant in the CLs. However, there is still no clear understanding of what is the optimal structure for the CLs. To investigate the structure of CLs, three aspects are studied in the present thesis work: (i) the effect of fabrication process on the resulting structure, (ii) the effect of the CL structure on its macro-properties, and (iii) the effect of the structure and macro-properties on the mass transport phenomena and the associated cell performance. Many factors including fabrication techniques and CL compositions have a significant impact on the structure formation of CLs. However, how these factors affect the structure is still unclear. Additionally, there lacks experimental characterization of the structure such as porosity, PSD, specific surface area, mean pore size, and surface fractal dimension, as well as mass transport properties such as effective diffusion coefficient and gas permeability for the CLs in literature. With the experimentally determined structural and mass transport parameters of the CLs and the associated electrodes, the mass transport phenomena in PEM fuel cells can be quantitatively analyzed. In the present thesis work, the CL pore structure is experimentally characterized by the method of standard porosimetry (MSP), which is established based on the phenomenon of capillary equilibrium in the wetted porous materials. By the means of MSP, a comprehensive characterization of the structure in terms of porosity, PSD, specific surface area, mean pore size, and surface fractal dimension is obtained. In addition, the effective diffusion coefficient of the CL is studied by the modified Loschmidt Cell, built based on the Fick's law of diffusion. The parameters including effective diffusion coefficient, diffusion resistivity, and its relation with the porosity and mean pore size is investigated. Further, the permeability is measured based on Darcy's law via a custom-engineered apparatus developed in my thesis work. The effect of Pt loading, temperature, flow rate, and gas species is explored in this thesis study. With the experimentally determined pore structure characterization and mass transport properties, a numerical study is performed for the better understanding of the mass transport mechanisms in the porous electrodes. The cell performance conducted in our lab is also reported in the present thesis for a better understanding of the ex-situ experiment and a comparison with the numerical modeling. The experimental and numerical studies presented in the present thesis work is of great significance to (i) understand the structure of the CLs, (ii) to understand the relation between the structure and the mass transport properties such as the effective diffusion coefficient and permeability, and (iii) to understand the effect of the structural parameters and mass transport properties on the mass transport phenomena and hence the cell performance in the PEM fuel cells.
Author: Qingfeng Li
Publisher: Springer
ISBN: 3319170821
Category : Technology & Engineering
Languages : en
Pages : 561
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Book Description
This book is a comprehensive review of high-temperature polymer electrolyte membrane fuel cells (PEMFCs). PEMFCs are the preferred fuel cells for a variety of applications such as automobiles, cogeneration of heat and power units, emergency power and portable electronics. The first 5 chapters of the book describe rationalization and illustration of approaches to high temperature PEM systems. Chapters 6 - 13 are devoted to fabrication, optimization and characterization of phosphoric acid-doped polybenzimidazole membranes, the very first electrolyte system that has demonstrated the concept of and motivated extensive research activity in the field. The last 11 chapters summarize the state-of-the-art of technological development of high temperature-PEMFCs based on acid doped PBI membranes including catalysts, electrodes, MEAs, bipolar plates, modelling, stacking, diagnostics and applications.
