This thesis deals to optimize the performance of PEMFC fuel cells, through the development of new flow-field plate designs. Tools such as water balance and electrochemical noise analysis have been used to diagnose water management within a PEMFC single cell. Optimal management of the water transport enables an increase of the performance and durability of fuel cells. Water balance method was used to measure and frame the value of the effective water diffusion coefficient within the membranes of fuel cells. New flow-flied plate geometries have been developed and characterized by conventional polarization curve and pressure measurements. The electrochemical noise technique was used to detect phenomena related to the behavior of water during fuel cell operation for each geometry developed. Electrochemical noise measurements have been associated with source mechanisms through an experimental approach and an appropriate signal processing based on frequency and time analysis. The descriptors obtained by time and frequency analysis shows that it possible to obtain the signature in normal operation of a fuel cell using a classical serpentine. This signature was compared to the new developed designs allowing to characterize the influence of these new geometries on the water transport. Finally, to complete the experimental approach carried out on the water diffusion coefficient within the membranes of PEMFC fuel cells, a model based on polarization curve, considering this coefficient, was developed and compared to the experimental curves of performances. In perspective, the impact of the new developed geometries has been extended in a stack utilization and a prognosis model based on artificial neural networks has been proposed.

Polymer Electrolyte Membrane (PEM) fuel cells convert chemical energy in hydrogen into electrical energy with water as the only by-product. Thus, PEM fuel cells hold great promise to reduce both pollutant emissions and dependency on fossil fuels, especially for transportation—passenger cars, utility vehicles, and buses—and small-scale stationary and portable power generators. But one of the greatest challenges to realizing the high efficiency and zero emissions potential of PEM fuel cells technology is heat and water management. This book provides an introduction to the essential concepts for effective thermal and water management in PEM fuel cells and an assessment on the current status of fundamental research in this field. The book offers you: • An overview of current energy and environmental challenges and their imperatives for the development of renewable energy resources, including discussion of the role of PEM fuel cells in addressing these issues; • Reviews of basic principles pertaining to PEM fuel cells, including thermodynamics, electrochemical reaction kinetics, flow, heat and mass transfer; and • Descriptions and discussions of water transport and management within a PEM fuel cell, including vapor- and liquid-phase water removal from the electrodes, the effects of two-phase flow, and solid water or ice dynamics and removal, particularly the specialized case of starting a PEM fuel cell at sub-freezing temperatures (cold start) and the various processes related to ice formation.

Water and Thermal Management of Proton Exchange Membrane Fuel Cells introduces the main research methods and latest advances in the water and thermal management of PEMFCs. The book introduces the transport mechanism of each component, including modeling methods at different scales, along with practical exercises. Topics include PEMFC fundamentals, working principles and transport mechanisms, characterization tests and diagnostic analysis, the simulation of multiphase transport and electrode kinetics, cell-scale modeling, stack-scale modeling, and system-scale modeling. This volume offers a practical handbook for researchers, students and engineers in the fields of proton exchange membrane fuel cells. Proton exchange membrane fuel cells (PEMFCs) are high-efficiency and low-emission electrochemical energy conversion devices. Inside the PEMFC complex, physical and chemical processes take place, such as electrochemical reaction, multiphase flow and heat transfer. This book explores these topics, and more. - Introduces the transport mechanism for each component of PEMFCs - Presents modeling methods at different scales, including component, cell, stack and system scales - Provides exercises in PEMFC modeling, along with examples of necessary codes - Covers the latest advances in PEMFCs in a convenient and structured manner - Offers a solution to researchers, students and engineers working on proton exchange membrane fuel cells

Increasing global energy demand, growing carbon emissions and the depletion of fossil fuel sources are some of the most important driving forces for the development of sustainable energy solutions. Proton Exchange Membrane (PEM) fuel cells have been demonstrated to be a potential candidate for clean energy conversion in a wide range of applications reaching from highly dynamic transportation systems to stationary systems. Despite their benefits, such as high efficiency and wide operating range, PEM fuel cells must still meet or exceed the technological advantages, such as durability and cost, of conventional power systems in order to be truly competitive. Thus, current research is focused on improving these aspects. This doctoral thesis combines experimental and model-based studies in order to improve performance and durability of PEM fuel cells, that work without external humidification, as demanded by recent government-supported research programs. Improved performance and durability can be obtained by proper system control. The key factor for the development of successful control strategies is adequate thermal and water management considering their interconnections. Therefore, this work investigates the important links between performance, efficiency and lifetime with respect to fuel cell temperature and humidification. The experimental evaluation of temperature-related and purge-related effects shows the great potential of improving the system performance by proper thermal management. In-situ and ex-situ experiments, such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), gas chromatography (GC), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized in order to explore short-term and long-term effects of operation modes on performance and durability. To provide a better understanding of the experimentally observed phenomena and their different dynamics with respect to the development of efficient controllers, mathematical models have been derived. The dynamic models allow for relating electrode structure to the cell voltage transient behavior during changes in fuel cell temperature and humidification, including important phase change and ionomer sorption dynamics of water. The experimentally validated, model-based analysis provides recommendations of proper operating conditions and catalyst structure, such as optimal fuel cell temperature and adequate pore-size-distribution, in order to improve the PEM fuel cell performance. The modular character and inherent adaptability of the models has been successfully demonstrated in the study of water transport in a high temperature PEM fuel cell stack. It is shown how mathematical modeling can improve the interpretation of experimental results and provide insight into experimentally non-observable interactions. In conclusion, the presented laboratory and model-based work, including the developed experimental and mathematical tools, contribute to current international research targets for advancing sustainable energy solutions.

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.

PEM Fuel Cell Diagnostic Tools presents various tools for diagnosing PEM fuel cells and stacks, including in situ and ex situ diagnostic tools, electrochemical techniques, and physical/chemical methods. The text outlines the principles, experimental implementation, data processing, and application of each technique, along with its capabilities and weaknesses. The book covers many diagnostics employed in the characterization and determination of fuel cell performance. It discusses commonly used conventional tools, such as cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, and transmission electron microscopy. It also examines special tools developed specifically for PEM fuel cells, including transparent cells, cathode discharge, and current mapping, as well as recent advanced tools for diagnosis, such as magnetic resonance imaging and atomic force microscopy. For clarity, the book splits these diagnostic methodologies into two parts—in situ and ex situ. To better understand the tools, PEM fuel cell testing is also discussed. Each self-contained chapter provides cross-references to other chapters. Written by international scientists active in PEM fuel cell research, this volume incorporates state-of-the-art technical advances in PEM fuel cell diagnosis. The diagnostic tools presented help readers to understand the physical and chemical phenomena involved in PEM fuel cells.

Demand for fuel cell technology is growing rapidly. Fuel cells are being commercialized to provide power to buildings like hospitals and schools, to replace batteries in portable electronic devices, and as replacements for internal combustion engines in vehicles. PEM (Proton Exchange Membrane) fuel cells are lighter, smaller, and more efficient than other types of fuel cell. As a result, over 80% of fuel cells being produced today are PEM cells. This new edition of Dr. Barbir's groundbreaking book still lays the groundwork for engineers, technicians and students better than any other resource, covering fundamentals of design, electrochemistry, heat and mass transport, as well as providing the context of system design and applications. Yet it now also provides invaluable information on the latest advances in modeling, diagnostics, materials, and components, along with an updated chapter on the evolving applications areas wherein PEM cells are being deployed. Comprehensive guide covers all aspects of PEM fuel cells, from theory and fundamentals to practical applications Provides solutions to heat and water management problems engineers must face when designing and implementing PEM fuel cells in systems Hundreds of original illustrations, real-life engineering examples, and end-of-chapter problems help clarify, contextualize, and aid understanding

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.

This book focuses on water content estimation and control of the PEM fuel cell stack and the individual cell in vehicle. Firstly, the mathematical connection between polarization curve and equivalent circuit model proves importance of MEA and its feasibility to study water content. Optimizing structure of MEA realizes the internal water content recirculation of a fuel cell and improves its performance under middle or lower current density. The influence of water content on performance of MEA is quantified, and variation of equivalent circuit model is an excellent indicator of water content. Secondly, the comprehensive online AC impedance measurement method is put forward, including current excitation method, weak voltage and current signal processing method, and method for analyzing measurement error, and experiment validates measurement accuracy. The high-frequency impedance and statistical characteristic are proposed as indicator of water content. Finally, the dynamic model of the air supply system of a fuel cell engine is established and the closed-loop control of the air supply system and the water content estimation are decoupled. The experiment on a fuel cell system validates the proposed method for searching optimized operating conditions and the water management strategy.