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Performance Enhancements Of Microfluidic Fuel Cells With Flow Through Porous Electrodes
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Book Synopsis Performance Enhancements of Microfluidic Fuel Cells with Flow-through Porous Electrodes by : Jin Wook Lee
Download or read book Performance Enhancements of Microfluidic Fuel Cells with Flow-through Porous Electrodes written by Jin Wook Lee and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents performance improvements of microfluidic fuel cells with flow-through porous electrodes. The baseline cell is a laminar flow-based, membraneless, microfluidic fuel cell employing vanadium redox species (as electrolytes). The main objective of the current work is to establish a design guideline for microfluidic fuel cells and to propose new design strategies that lead to better performing cells. The fundamental physics including fluid flow, electrochemical reactions in porous media, and convective/diffusive mass transport is closely investigated. Various loss elements during the baseline cell operation such as activation, ohmic, and mass transport losses are identified and compared. Some feasible and practical remedies to reduce the overall losses are proposed and successfully demonstrated: thin film current collector for the overall ohmic loss; nanofoam material as electrodes to reduce the activation loss; and novel concept to overcome mass transport limited performances. Further improvements would be anticipated if both ohmic and fluidic resistances of the nanofoam material are reduced. Uniform distribution of the pore sizes is also important to maximize the utilization of active electrode areas. When combined, the demonstrated technologies and design improvements are anticipated to bring this unique membraneless and catalyst-free fuel cell closer to commercialization as a low-cost power source.
Book Synopsis High Performance Fuel-Breathing Microfluidic Fuel Cells by : Yifei Wang
Download or read book High Performance Fuel-Breathing Microfluidic Fuel Cells written by Yifei Wang and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "High Performance Fuel-breathing Microfluidic Fuel Cells" by Yifei, Wang, 王夷飞, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of the thesis entitled "HIGH PERFORMANCE FUEL-BREATHING MICROFLUIDIC FUEL CELLS" Submitted by Yifei, Wang for the degree of Doctor of Philosophy at The University of Hong Kong in September 2016 Fuel cells are broadly regarded as one of the most promising power sources. A fuel cell is generally composed of a thin membrane electrolyte sandwiched by two porous electrodes, which has a similar structure with batteries. Fuel cells are very advantageous considering their high energy density, uninterrupted operation and environmental friendliness. To date, the application of this technology is vigorously promoted by the government and industry especially for large-power applications. As for applications with small rated power, the progress is, however, impeded by their high cost, leading to less competitiveness against the mature battery technology. To lower down the cost, microfluidic fuel cell (MFC), also known as the membraneless fuel cell or laminar flow fuel cell, has been proposed recently. A MFC generally utilizes two laminar flows in parallel as electrolyte instead of any solid membrane, therefore, lowering the fabrication cost. To prevent the flows from violent mixing, micro-channel, normally with characteristic length less than 1mm, is requisite. In this manner, the mixing process is dominated by slow diffusion, forming a flow interface in the middle of the channel as a virtual membrane. Despite of its cost advantage, there are still many unsolved problems in MFCs such as poor energy density, trade-off between cell performance and fuel utilization, complex fluidic management, etc. In this thesis, research works on MFC development have been done to improve their cell performance, energy efficiency, energy density, long-term stability, etc. In addition, a novel MFC stacking strategy has been proposed, which was proved to be competent for practical applications. First, conventional liquid-feed MFCs with either co-flow or counter-flow configuration were studied. Their cell performance and fuel utilization were optimized, which were used as benchmarks in subsequent studies. To solve the intractable restrictions in liquid-feed MFCs, vapor-feed MFCs were proposed which breathed fuel vapor from outside the cell instead of acquiring dissolved fuel from the inside electrolyte, therefore, -2 achieving both high power density (55.4mWcm ) and high energy efficiency (9.4%) at the same time. To better understand the mechanism behind its performance, numerical (R) simulation on vapor-feed MFCs was also conducted using COMSOL 4.2. To achieve practical power output, a circular stacking strategy was proposed, which was especially suitable for fuel-breathing MFCs. A six- cell stack was designed and tested, proving that such a stacking strategy was not only highly efficient but also potentially robust to external flow disturbance. The same stacking strategy was also applied to H -fueled MFCs to further improve the power output. By utilizing Al-H O reaction for H generation, 2 2 the proposed Al-feed MFC stack achieved a peak power output of 530mW. Meanwhile, difficulties in hydrogen storage and waste electrolyte management were eliminated. In MFCs with enlarged electrode areas, cathode flooding was inevitably aggravated and cell performance dropped significantly. By cracking the cathode catalyst layer, this problem was greatly alleviated, leading to a m
Book Synopsis Comprehensive Numerical Study of Microfluidic Fuel Cells by :
Download or read book Comprehensive Numerical Study of Microfluidic 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: The microfluidic fuel cell or laminar flow-based fuel cell is a membraneless fuel cell which typically consists of two electrodes mounted within a T- or Y-shaped microchannel. Aqueous fuel and oxidant are introduced from the two inlets of the channel and flow together side-by-side toward the end of the channel. The Reynolds number in the microchannel is low, and hence viscous forces are dominant over the inertial forces. This causes the anolyte and catholyte form a co-laminar flow inside the microchannel which is required to maintain the separation of the fuel and oxidant and limit the reactions to the appropriate electrodes. In this work, a comprehensive numerical model of the microfluidic fuel cell is developed using COMSOL Multiphysics. This model accounts for the mass and momentum transport phenomena inside the device as well as the electrochemical reaction kinetics which are described by the Butler-Volmer equations. Potential equations are used to model both the ionic conduction in the electrolyte and the electrical conduction in the solid electrodes. The validity of the developed model is first checked by verifying it against the numerical and experimental results previously reported in the literature. The model is then used to assess the effect of different modifications, which have been applied on the microfluidic fuel cell since its advent, by calculating the polarization curves associated with each modification. In this thesis, a novel design of microfluidic fuel cell with a tapered channel is also proposed. Using the numerical model, it is shown that the tapered geometry improves the fuel utilization by up to four times in addition to a substantial improvement in the power density. A similar numerical model is developed to study the performance of a microfluidic fuel cell with flow-through porous electrodes. Using this model, the effect of porosity on the net power output of the fuel cell is investigated and an optimum value for porosity is calculated. Th.
Download or read book Microfluidic Fuel Cells written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfluidic fuel cell architectures are presented in this thesis. This work represents the mechanical and microfluidic portion of a microfluidic biofuel cell project. While the microfluidic fuel cells developed here are targeted to eventual integration with biocatalysts, the contributions of this thesis have more general applicability. The cell architectures are developed and evaluated based on conventional non-biological electrocatalysts. The fuel cells employ co-laminar flow of fuel and oxidant streams that do not require a membrane for physical separation, and comprise carbon or gold electrodes compatible with most enzyme immobilization schemes developed to date. The demonstrated microfluidic fuel cell architectures include the following: a single cell with planar gold electrodes and a grooved channel architecture that accommodates gaseous product evolution while preventing crossover effects; a single cell with planar carbon electrodes based on graphite rods; a three-dimensional hexagonal array cell based on multiple graphite rod electrodes with unique scale-up opportunities; a single cell with porous carbon electrodes that provides enhanced power output mainly attributed to the increased active area; a single cell with flow-through porous carbon electrodes that provides improved performance and overall energy conversion efficiency; and a single cell with flow-through porous gold electrodes with similar capabilities and reduced ohmic resistance. As compared to previous results, the microfluidic fuel cells developed in this work show improved fuel cell performance (both in terms of power density and efficiency). In addition, this dissertation includes the development of an integrated electrochemical velocimetry approach for microfluidic devices, and a computational modeling study of strategic enzyme patterning for microfluidic biofuel cells with consecutive reactions.
Book Synopsis Microfluidic Fuel Cells and Batteries by : Erik Kjeang
Download or read book Microfluidic Fuel Cells and Batteries written by Erik Kjeang and published by Springer. This book was released on 2014-06-14 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfluidic fuel cells and batteries represent a special type of electrochemical power generators that can be miniaturized and integrated in a microfluidic chip. Summarizing the initial ten years of research and development in this emerging field, this SpringerBrief is the first book dedicated to microfluidic fuel cell and battery technology for electrochemical energy conversion and storage. Written at a critical juncture, where strategically applied research is urgently required to seize impending technology opportunities for commercial, analytical, and educational utility, the intention is for this book to be a ‘one-stop shop’ for current and prospective researchers in the general area of membraneless, microfluidic electrochemical energy conversion. As the overall goal of the book is to provide a comprehensive resource for both research and technology development, it features extensive descriptions of the underlying fundamental theory, fabrication methods, and cell design principles, as well as a thorough review of previous contributions in this field and a future outlook with recommendations for further work. It is hoped that the content will entice and enable new research groups and engineers to rapidly gain traction in their own laboratories towards the development of next generation microfluidic electrochemical cells.
Book Synopsis Advances in Microfluidics by : Xiao-Ying Yu
Download or read book Advances in Microfluidics written by Xiao-Ying Yu and published by BoD – Books on Demand. This book was released on 2016-11-23 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing innovations and applications make microfluidics a versatile choice for researchers in many disciplines. This book consists of multiple review chapters that aim to cover recent advances and new applications of microfluidics in biology, electronics, energy, and materials sciences. It provides comprehensive views of various aspects of microfluidics ranging from fundamentals of fabrication, flow control, and droplet manipulation to the most recent exploration in emerging areas such as material synthesis, imaging and novel spectroscopy, and marriage with electronics. The chapters have many illustrations showcasing exciting results. This book should be useful for those who are eager to learn more about microfluidics as well as researchers who want to pick up new concepts and developments in this fast-growing field.
Book Synopsis Practical Advances in Microfluidic Electrochemical Energy Conversion by : Omar Ibrahim
Download or read book Practical Advances in Microfluidic Electrochemical Energy Conversion written by Omar Ibrahim and published by . This book was released on 2018 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro-fabrication technologies has enabled the inexpensive production of microchannels which has been utilized in electrochemical flow cells like fuel cells and flow batteries. These offer simplicity and cost benefits as they utilize co-laminar flow for flowing streams separation rather than a physical separator or membrane. This thesis aims to identify practical applications for viable utility of microfluidic flow cells and suggests their potential use for analytical platforms, disposable power sources or combined electrolyte functionalities such as cooling and powering of electronics. All advances reported in this work leverage microfluidic cell architectures with flow-through porous electrodes to achieve competitive performance with simplified, inexpensive device solutions. A previously reported microfluidic redox battery design is modified to form an analytical cell that is applied throughout this dissertation. The analytical cell designs have two separate cell portions which, when connected in parallel, enable in-situ characterization of the dual-pass design, allowing deeper understanding of the reactant conversion and crossover. When the two portions are connected in series, quantifying possible losses in flow cell arrays, such as shunt current, is allowed. The technology is also applied to explore flow cells with non-aqueous electrolytes, which generally enable higher cell voltages but have limited performance from high membrane resistance. The proposed membrane-less cell with non-aqueous electrolytes shows comparable performance with aqueous vanadium electrolytes. Moreover, a chemistry evaluation framework is applied to assess redox reactants and supporting electrolytes selection for biodegradable primary batteries. The selected quinone redox chemistry is demonstrated in a novel 1 V paper-based capillary flow cell, with flow-through porous electrodes, that is proven to be powerful, cheap, scalable and biodegradable and demonstrated to directly substitute a coin cell battery for powering a water quality sensor. This new class of batteries thus holds great promise to radically change the portable battery paradigm; from considering it a harmful waste to a source of biodegradable materials that could even nurture the environment by enriching soil and water beyond its life cycle. Lastly, a scaled co-laminar flow cell is shown for the first time and embedded in a printed circuit board for the application of simultaneous thermal and power management of mounted electronics. This demonstration has advantages in future high-density computers and enables new perspectives for near-term adoption.
Book Synopsis Microfluidics for Fuel Cell Applications by : Ian Stewart
Download or read book Microfluidics for Fuel Cell Applications written by Ian Stewart and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, a microfluidics approach is applied to two fuel cell related projects; the study of deformation and contact angle hysteresis on water invasion in porous media and the introduction of bubble fuel cells. This work was carried out as collaboration between the microfluidics and CFCE groups in the Department of Mechanical Engineering at the University of Victoria. Understanding water transport in the porous media of Polymer Electrolyte Membrane fuel cells is crucial to improve performance. One popular technique for both numeric simulations and experimental micromodels is pore network modeling, which predicts flow behavior as a function of capillary number and relative viscosity. An open question is the validity of pore network modeling for the small highly non-wetting pores in fuel cell porous media. In particular, current pore network models do not account for deformable media or contact angle hysteresis. We developed and tested a deformable microfluidic network with an average hydraulic diameter of 5?m, the smallest sizes to date. At a capillary number and relative viscosity for which conventional theory would predict strong capillary fingering behavior, we report almost complete saturation. This work represents the first experimental pore network model to demonstrate the combined effects of material deformation and contact angle hysteresis. Microfluidic fuel cells are small scale energy conversion devices that take advantage of microscale transport phenomena to reduce size, complexity and cost. They are particularly attractive for portable electronic devices, due to their potentially high energy density. The current state of the art microfluidic fuel cell uses the laminar flow of liquid fuel and oxidant as a membrane. Their performance is plagued by a number of factors including mixing, concentration polarization, ohmic polarization and low fuel utilization. In this work, a new type of microfluidic fuel cell is conceptualized and developed that uses bubbles to transport fuel and oxidant within an electrolyte. Bubbles offer a phase boundary to prevent mixing, higher rates of diffusion, and independent electrolyte selection. One particular bubble fuel cell design produces alternating current. This work presents, to our knowledge, the first microfluidic chip to produce bubbles of alternating composition in a single channel, class of fuel cells that use bubbles to transport fuel and oxidant and fuel cell capable of generating alternating current.
Download or read book Micro Fuel Cells written by Tim Zhao and published by Academic Press. This book was released on 2009-07-07 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today's consumers of portable electronics consumers are demanding devices not only deliver more power but also work healthy for the environment. This fact alone has lead major corporations like Intel, BIC, Duracell and Microsoft to believe that Microfuel Cells could be the next-generation power source for electronic products. Compact and readable, Microfuels Principles and Applications, offers engineers and product designers a reference unsurpassed by any other in the market. The book starts with a clear and rigorous exposition of the fundamentals engineering principles governing energy conversion for small electronic devices, followed by self-contained chapters concerning applications. The authors provide original points of view on all types of commercially available micro fuel cells types, including micro proton exchange membrane fuel cells, micro direct methanol fuel cells, micro solid oxide fuel cells and micro bio-fuel cells. The book also contains a detailed introduction to the fabrication of the components and the assembly of the system, making it a valuable reference both in terms of its application to product design and understanding micro engineering principles. An overview of the micro fuel cell systems and applications A detailed introduction to the fabrication of the components and the assembly of the system Original points of view on prospects of micro fuel cells
Book Synopsis Towards a Fuel-flexible Direct Alcohol Microfluidic Fuel Cell with Flow-through Porous Electrodes: Assessment of Methanol, Ethylene Glycol and Glycerol Fuels by :
Download or read book Towards a Fuel-flexible Direct Alcohol Microfluidic Fuel Cell with Flow-through Porous Electrodes: Assessment of Methanol, Ethylene Glycol and Glycerol Fuels written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Microfluidic Platforms for the Investigation of Fuel Cell Catalysts and Electrodes by : Fikile R. Brushett
Download or read book Microfluidic Platforms for the Investigation of Fuel Cell Catalysts and Electrodes written by Fikile R. Brushett and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A clear need exists for novel approaches to producing and utilizing energy in more efficient ways, in light of society0́9s ever increasing demand as well as growing concerns with respect to climate change related to CO2 emissions. The development of low temperature fuel cell technologies will continue to play an important role in many alternative energy conversion strategies, especially for portable electronics and automotive applications. However, widespread commercialization of fuel cell technologies has yet to be achieved due to a combination of high costs, poor durability and, system performance limitations (Chapter 1). Developing a better understanding of the complex interplay of electrochemical, transport, and degradation processes that govern the performance and durability of novel fuel cell components, particularly catalysts and electrodes, within operating fuel cells is critical to designing robust, inexpensive configurations that are required for commercial introduction. Such detailed in-situ investigations of individual electrode processes are complicated by other factors such as water management, uneven performance across electrodes, and temperature gradients. Indeed, too many processes are interdependent on the same few variable parameters, necessitating the development of novel analytical platforms with more degrees of freedom. Previously, membraneless microfluidic fuel cells have been developed to address some of the aforementioned fuel cell challenges (Chapter 2). At the microscale, the laminar nature of fluid flow eliminates the need for a physical barrier, such as a stationary membrane, while still allowing ionic transport between electrodes. This enables the development of many unique and innovative fuel cell designs. In addition to addressing water management and fuel crossover issues, these laminar flow-based systems allow for the independent specification of individual stream compositions (e.g., pH). Furthermore, the use of a liquid electrolyte enables the simple in-situ analysis of individual electrode performance using an off-the-shelf reference electrode. These advantages can be leveraged to develop microfluidic fuel cells as versatile electro-analytical platforms for the characterization and optimization of catalysts and electrodes for both membrane- and membraneless fuel cells applications. To this end, a microfluidic hydrogen-oxygen (H2/O2) fuel cell has been developed which utilizes a flowing liquid electrolyte instead of a stationary polymeric membrane. For analytical investigations, the flowing stream (i) enables autonomous control over electrolyte parameters (i.e., pH, composition) and consequently the local electrode environments, as well as (ii) allows for the independent in-situ analyses of catalyst and/or electrode performance and degradation characteristics via an external reference electrode (e.g., Ag/AgCl). Thus, this microfluidic analytical platform enables a high number of experimental degrees of freedom, previously limited to a three-electrode electrochemical cell, to be employed in the construct of working fuel cell. Using this microfluidic H2/O2 fuel cell as a versatile analytical platform, the focus of this work is to provide critical insight into the following research areas: 0́Ø Identify the key processes that govern the electrode performance and durability in alkaline fuel cells as a function of preparation methods and operating parameters (Chapter 3). 0́Ø Determine the suitability of a novel Pt-free oxygen reduction reaction catalyst embedded in gas diffusion electrodes for acidic and alkaline fuel cell applications (Chapter 4). 0́Ø Establish electrode structure-activity relationships by aligning in-situ electrochemical analyses with ex-situ microtomographic (MicroCT) structural analyses (Chapter 5). 0́Ø Investigate the feasibility and utility of a microfluidic-based vapor feed direct methanol fuel cell (VF-DMFC) configuration as a power source for portable applications (Chapter 6). In all these areas, the information garnered from these in-situ analytical platforms will advance the development of more robust and cost-effective electrode configurations and thus more durable and commercially-viable fuel cell systems (both membrane-based and membraneless).
Author :Marco Aurelio Dos Santos Bernardes Publisher :BoD – Books on Demand ISBN 13 :9533074809 Total Pages :746 pages Book Rating :4.5/5 (33 download)
Book Synopsis Biofuel's Engineering Process Technology by : Marco Aurelio Dos Santos Bernardes
Download or read book Biofuel's Engineering Process Technology written by Marco Aurelio Dos Santos Bernardes and published by BoD – Books on Demand. This book was released on 2011-08-01 with total page 746 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book aspires to be a comprehensive summary of current biofuels issues and thereby contribute to the understanding of this important topic. Readers will find themes including biofuels development efforts, their implications for the food industry, current and future biofuels crops, the successful Brazilian ethanol program, insights of the first, second, third and fourth biofuel generations, advanced biofuel production techniques, related waste treatment, emissions and environmental impacts, water consumption, produced allergens and toxins. Additionally, the biofuel policy discussion is expected to be continuing in the foreseeable future and the reading of the biofuels features dealt with in this book, are recommended for anyone interested in understanding this diverse and developing theme.
Book Synopsis Bioelectrochemical Systems by : Korneel Rabaey
Download or read book Bioelectrochemical Systems written by Korneel Rabaey and published by IWA Publishing. This book was released on 2009-12-01 with total page 525 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the context of wastewater treatment, Bioelectrochemical Systems (BESs) have gained considerable interest in the past few years, and several BES processes are on the brink of application to this area. This book, written by a large number of world experts in the different sub-topics, describes the different aspects and processes relevant to their development. Bioelectrochemical Systems (BESs) use micro-organisms to catalyze an oxidation and/or reduction reaction at an anodic and cathodic electrode respectively. Briefly, at an anode oxidation of organic and inorganic electron donors can occur. Prime examples of such electron donors are waste organics and sulfides. At the cathode, an electron acceptor such as oxygen or nitrate can be reduced. The anode and the cathode are connected through an electrical circuit. If electrical power is harvested from this circuit, the system is called a Microbial Fuel Cell; if electrical power is invested, the system is called a Microbial Electrolysis Cell. The overall framework of bio-energy and bio-fuels is discussed. A number of chapters discuss the basics – microbiology, microbial ecology, electrochemistry, technology and materials development. The book continues by highlighting the plurality of processes based on BES technology already in existence, going from wastewater based reactors to sediment based bio-batteries. The integration of BESs into existing water or process lines is discussed. Finally, an outlook is provided of how BES will fit within the emerging biorefinery area.
Book Synopsis A Microscale Approach to Optimizing the Performance of Microbial Fuel Cells by : Mehran Abbaszadeh Amirdehi
Download or read book A Microscale Approach to Optimizing the Performance of Microbial Fuel Cells written by Mehran Abbaszadeh Amirdehi and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Résumé en anglais
Book Synopsis Membraneless Microfluidic Fuel Cells by : Kamil S. Salloum
Download or read book Membraneless Microfluidic Fuel Cells written by Kamil S. Salloum and published by . This book was released on 2010 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Portable devices rely on battery systems that contribute largely to the overall device form factor and delay portability due to recharging. Membraneless microfluidic fuel cells are considered as the next generation of portable power sources for their compatibility with higher energy density reactants. Microfluidic fuel cells are potentially cost effective and robust because they use low Reynolds number flow to maintain fuel and oxidant separation instead of ion exchange membranes. However, membraneless fuel cells suffer from poor efficiency due to poor mass transport and Ohmic losses. Current microfluidic fuel cell designs suffer from reactant cross-diffusion and thick boundary layers at the electrode surfaces, which result in a compromise between the cell's power output and fuel utilization. This dissertation presents novel flow field architectures aimed at alleviating the mass transport limitations. The first architecture provides a reactant interface where the reactant diffusive concentration gradients are aligned with the bulk flow, mitigating reactant mixing through diffusion and thus crossover. This cell also uses porous electro-catalysts to improve electrode mass transport which results in higher extraction of reactant energy. The second architecture uses porous electrodes and an inert conductive electrolyte stream between the reactants to enhance the interfacial electrical conductivity and maintain complete reactant separation. This design is stacked hydrodynamically and electrically, analogous to membrane based systems, providing increased reactant utilization and power. These fuel cell architectures decouple the fuel cell's power output from its fuel utilization. The fuel cells are tested over a wide range of conditions including variation of the loads, reactant concentrations, background electrolytes, flow rates, and fuel cell geometries. These experiments show that increasing the fuel cell power output is accomplished by increasing reactant flow rates, electrolyte conductivity, and ionic exchange areas, and by decreasing the spacing between the electrodes. The experimental and theoretical observations presented in this dissertation will aid in the future design and commercialization of a new portable power source, which has the desired attributes of high power output per weight and volume and instant rechargeability.
Book Synopsis Microfluidic H2/O2 Fuel Cells for Contaminant and Electrode Analysis by : Matt Naughton
Download or read book Microfluidic H2/O2 Fuel Cells for Contaminant and Electrode Analysis written by Matt Naughton and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Alkaline fuel cells (AFCs) are promising power sources due to superior cathode kinetics as compared to acidic media and the ability to use inexpensive non-noble metal catalysts. However, carbonate formation from carbon dioxide in air has long been considered a significant hurdle for liquid electrolyte-based AFC technologies. Carbonate formation consumes hydroxyl anions, which leads to (i) reduced electrode performance if formed salts precipitate from solution and (ii) lowered electrolyte conductivity, which reduces cell performance and operating lifetime. We have used a microfluidic H2/O2 fuel cell as an analytical platform to determine the effects of the carbonate formation problem in alkaline fuel cells. The microfluidic fuel cell has modular components that can easily be swapped to test electrodes, electrolyte, or other aspects of the fuel cell. A reference electrode placed at the outlet allows for individual electrode analysis, which is not normally possible in conventional membrane-based fuel cells. In this thesis, it is demonstrated that AFC performance can be resilient to a broad range of carbonate concentrations. Furthermore, the effects of carbonate formation rates on projected AFC operational lifetime are determined. A quantitative method to analyze individual electrode performance using single electrode plots and the two parameters Rohmic and Vkinetic is also developed. Results demonstrated that losses from both electrodes are substantial in an alkaline fuel cell, and that ohmic and mass transport losses are shown to only significantly affect Rohmic. IR-corrections were used to isolate individual kinetic and mass transport losses at each electrode within the operating fuel cell. These findings demonstrate great potential to broaden the scope of fuel cell research.
Book Synopsis Fuel Cell Science by : Andrzej Wieckowski
Download or read book Fuel Cell Science written by Andrzej Wieckowski and published by John Wiley & Sons. This book was released on 2010-10-12 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive survey of theoretical andexperimental concepts in fuel cell chemistry Fuel cell science is undergoing significant development, thanks, in part, to a spectacular evolution of the electrocatalysis concepts, and both new theoretical and experimental methods. Responding to the need for a definitive guide to the field, Fuel Cell Science provides an up-to-date, comprehensive compendium of both theoretical and experimental aspects of the field. Designed to inspire scientists to think about the future of fuel cell technology, Fuel Cell Science addresses the emerging field of bio-electrocatalysis and the theory of heterogeneous reactions in fuel cell science and proposes potential applications for electrochemical energy production. The book is thorough in its coverage of the electron transfer process and structure of the electric double layer, as well as the development of operando measurements. Among other subjects, chapters describe: Recently developed strategies for the design, preparation, and characterization of catalytic materials for fuel cell electrodes, especially for new fuel cell cathodes A wide spectrum of theoretical and computational methods, with?the aim of?developing?new fuel cell catalysis concepts and improving existing designs to increase their performance.? Edited by two leading faculty, the book: Addresses the emerging fields of bio-electrocatalysis for fuel cells and theory of heterogeneous reactions for use in fuel cell catalysis Provides a survey of experimental and theoretical concepts in these new fields Shows the evolution of electrocatalysis concepts Describes the chemical physics of fuel cell reactions Forecasts future developments in electrochemical energy production and conversion Written for electrochemists and electrochemistry graduate students, electrocatalysis researchers, surface and physical chemists, chemical engineers, automotive engineers, and fuel cell and energy-related researchers, this modern compendium can help today's best minds meet the challenges in fuel science technology.
