Preface to the Second Edition
PEM Fuel Cells: Theory and Practice was written seven years ago as a result of my desire to share with younger generations of engineers and scientists knowledge gained from my experience at the forefront of fuel cell research and development. Most of what I have learned about fuel cells I gathered from hands-on experience in designing, building, testing, and evaluating fuel cell stacks and systems and making them work in practical applications. Over the last seven years I have continued to conduct R&D in PEM fuel cells, yet I only reluctantly agreed to prepare this second edition, as I was afraid that the rapidly developing nature of the field would have rendered the book very outdated. However, in going through the original manuscript I realized that although it is indisputable that fuel cell technology has made tremendous progress in the last seven years, at least the basics of PEM fuel cell engineering and operation covered in the book had not changed so much. That said, there were new materials, new designs, new diagnostic methods, and valuable feedback from years of field experience that needed to be added. As a result, we have developed a much more nuanced understanding of the processes impacting choice of materials, construction, performance, and longevity.
In recognition of the multifaceted character of the field’s evolution, the chapter on diagnostics has been rewritten by an expert in this particular area, Dr. Haijiang Wang from the Institute for Fuel Cell Innovation, National Research Council Canada, Vancouver, British Columbia.
Realizing that fuel cell durability is of crucial importance, I decided to add a new chapter on PEM fuel cell durability, and I invited another expert practitioner, Dr. Michael Perry, from United Technologies Research Center, East Hartford, Connecticut, to contribute it. I am taking this opportunity to thank Dr. Wang and Dr. Perry for their valuable contributions.
Advances in new materials, particularly membranes and catalysts, have been addressed in the chapter on main cell components, materials properties, and processes.
In the chapter on fuel cell operating conditions, I have added insights from my colleague Torsten Berning from Aalborg University, Denmark, about dew-point temperature of exhaust gases as a criterion for selection of operating conditions. My thanks are due him as well.
During the last seven years, numerous papers on fuel cell modeling have been published, covering various domains and physical phenomena as well as many new modeling methods and techniques. These models, in conjunction with improved diagnostic techniques, have provided better understanding of the intricacies of fuel cell operation, particularly around the role of water in fuel cell operation. The chapter on fuel cell modeling in the first edition of this book was organized by first presenting the basic governing equations describing conservation of mass, momentum, energy, species, and charge, then by giving their application in modeling examples for various domains, that is, across the membrane, above the channel and land, along the channel, and in three dimensions. I decided to keep the same organization and examples in this revised chapter, since they cover the fundamentals effectively. However, I added an example on modeling water transport in the gas diffusion layer through a pore network model as a representative of the new models that elucidate peculiar water behavior in porous fuel cell structures.
Diagrams, photos, and tables have been updated wherever applicable throughout the book but particularly in the chapter on fuel cell applications. Tables from the U.S. DOE Hydrogen and Fuel Cell Program, showing current status and technical targets for various applications, have been added. All other chapters have been edited once again and corrected or updated where necessary.
I would like to thank my students and post-docs at UNIDO-ICHET, the FESB University of Split, and the University of Wyoming who have pointed out some errors, typos, and unclear statements to help me improve on the content of the first edition.
I use this book as a text to teach a full-semester fuel cell engineering course as well as numerous short courses. In doing so, I have prepared thousands of slides organized to follow the book over the years. These slides will be made available on the book’s Website to those who want to use the book to teach a fuel cell course. My advice is to use these slides as a backbone for lectures and to spice them up with the newest developments in fuel cell technology as they emerge. At the end of each chapter there are numerical problems that may be assigned as homework. Solutions will also be posted in a password-protected instructor section of the book’s Website. In addition, each chapter has a quiz at the end. I have found these quizzes very useful, not only to evaluate students’ progress but also to evaluate my effectiveness as a teacher. After each quiz I perform a statistical analysis to identify the questions that most of the students have not answered correctly. I then revisit that part of the lecture.
It is my hope that the publication of this second edition of the book will increase opportunities for interactively sharing the experiences of instructors and students as well as the scientists and engineers all over the world who are involved in making better and more affordable fuel cells. This book is dedicated to all of them.
Finally, I would like to thank Jill Leonard and Tiffany Gasbarrini at Elsevier for their guidance, support, encouragement, and especially their patience throughout the process of preparing this second edition.
Frano Barbir
FESB University of Split, Split, Croatia
June 2012