Microfluidics in Membraneless Fuel Cells PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Microfluidics in Membraneless Fuel Cells PDF full book. Access full book title Microfluidics in Membraneless Fuel Cells by Jesus A. Diaz-Real. Download full books in PDF and EPUB format.
Author: Jesus A. Diaz-Real
Publisher:
ISBN:
Category : Science
Languages : en
Pages :
Get Book Here
Book Description
In the 1990s, the idea of developing miniaturized devices that integrate functions other than what normally are carried out at the laboratory level was conceived, and the so-called "lab-on-a-chip" (LOC) devices emerged as one of the most important research areas. LOC devices exhibit advantages related to the use of microfluidic channels such as small sample and reagent consumption, portability, low-power consumption, laminar flow, and higher surface area/volume ratio that enhances both thermal dissipation and electrochemical kinetics. Fuel cells are electrochemical devices that convert chemical energy to electrical energy. These are considered as one of the greener ways to generate electricity because typical fuel cells produce water and heat as the main reaction byproducts. The technical challenges to develop systems at the microscale and the advantages of microfluidics exhibited an important impact on fuel cells for several reasons, mainly related to avoid inherent problems of gaseous-based fuel cells. As a result, the birth of a new type of fuel cells as microfluidic fuel cells (MFCs) took place. The first microfluidic fuel cell was reported in 2002. This MFC was operated with liquid fuel/oxidant and had the advantage of the low laminar flow generated using a "Y" microfluidic channel to separate the anodic and cathodic streams, resulting in an energy conversion device that did not require a physical barrier to separate both streams. This electrochemical system originated a specific type of MFCs categorized as membraneless also called colaminar microfluidic fuel cells. Since that year, numerous works focused on the nature of fuels, oxidants and anodic/cathodic electrocatalysts, and cell designs have been reported. The limiting parameters of this kind of devices toward their use in portable applications are related to their low cell performances, small mass activity, and partial selectivity/durability of electrocatalysts. On the other hand, it has been observed that the cell design has a high effect on the cell performance due to internal cell resistances and the crossover effect. Furthermore, current technology is growing faster than last centuries and new microfabrication technologies are always emerging, allowing the development of smaller and more powerful microfluidic energy devices. In this chapter, the application of microfluidics in membraneless fuel cells is addressed in terms of evolution of cell designs of miniaturized microfluidic fuel cells as a result of new discoveries in microfabrication technology and the use of several fuels and electrocatalysts for specific and selective applications.
Author: Jesus A. Diaz-Real
Publisher:
ISBN:
Category : Science
Languages : en
Pages :
Get Book Here
Book Description
In the 1990s, the idea of developing miniaturized devices that integrate functions other than what normally are carried out at the laboratory level was conceived, and the so-called "lab-on-a-chip" (LOC) devices emerged as one of the most important research areas. LOC devices exhibit advantages related to the use of microfluidic channels such as small sample and reagent consumption, portability, low-power consumption, laminar flow, and higher surface area/volume ratio that enhances both thermal dissipation and electrochemical kinetics. Fuel cells are electrochemical devices that convert chemical energy to electrical energy. These are considered as one of the greener ways to generate electricity because typical fuel cells produce water and heat as the main reaction byproducts. The technical challenges to develop systems at the microscale and the advantages of microfluidics exhibited an important impact on fuel cells for several reasons, mainly related to avoid inherent problems of gaseous-based fuel cells. As a result, the birth of a new type of fuel cells as microfluidic fuel cells (MFCs) took place. The first microfluidic fuel cell was reported in 2002. This MFC was operated with liquid fuel/oxidant and had the advantage of the low laminar flow generated using a "Y" microfluidic channel to separate the anodic and cathodic streams, resulting in an energy conversion device that did not require a physical barrier to separate both streams. This electrochemical system originated a specific type of MFCs categorized as membraneless also called colaminar microfluidic fuel cells. Since that year, numerous works focused on the nature of fuels, oxidants and anodic/cathodic electrocatalysts, and cell designs have been reported. The limiting parameters of this kind of devices toward their use in portable applications are related to their low cell performances, small mass activity, and partial selectivity/durability of electrocatalysts. On the other hand, it has been observed that the cell design has a high effect on the cell performance due to internal cell resistances and the crossover effect. Furthermore, current technology is growing faster than last centuries and new microfabrication technologies are always emerging, allowing the development of smaller and more powerful microfluidic energy devices. In this chapter, the application of microfluidics in membraneless fuel cells is addressed in terms of evolution of cell designs of miniaturized microfluidic fuel cells as a result of new discoveries in microfabrication technology and the use of several fuels and electrocatalysts for specific and selective applications.
Author: Jon McKechnie
Publisher:
ISBN:
Category : Fuel cells
Languages : en
Pages : 0
Get Book Here
Book Description
This thesis is part of an ongoing collaborative research project focused on the development of microstructured enzymatic fuel cells. Both enzymatic fuel cells and co-laminar fuel cells are, more generally, varieties of microfluidic membraneless fuel cells. A primary goal of this particular work is the establishment of microfabrication capabilities to develop these technologies. Rapid prototyping soft lithography capabilities are established in-house and protocols specific to the lab equipment are developed. These prototyping methods are then adapted for the fabrication of microfluidic membraneless fuel cells. Fabrication techniques using polymeric stencils and photoresist-based channel structures are developed to enable electrode patterning and current collection in the enzymatic and co-laminar fuel cells of interest. A variety of electrode patterning methods are developed. Gold electrode patterning by etching and lift-off techniques are investigated for the patterning of base electrode layers. An in-situ gold electrode patterning methodology is designed and tested, eliminating the need for precision alignment during device assembly. Carbon electrode patterning methods are developed for use in a vanadium-based colaminar fuel cell. Thin-film carbon electrodes are fabricated using a mixture of carbon microparticles and a polymeric binder. Alternatively, graphite rods are investigated for use as electrodes due to their high conductivity and chemical stability. The integration of channel structure and electrode fabrication methods is investigated to establish compatibilities and facilitate the assembly of functional devices. In addition to the development of these methods, the application of co-laminar streaming to microfabrication is explored through the development of a dynamic microfluidic photomasking device.
Author: Jon McKechnie
Publisher:
ISBN:
Category : Fuel cells
Languages : en
Pages :
Get Book Here
Book Description
This thesis is part of an ongoing collaborative research project focused on the development of microstructured enzymatic fuel cells. Both enzymatic fuel cells and co-laminar fuel cells are, more generally, varieties of microfluidic membraneless fuel cells. A primary goal of this particular work is the establishment of microfabrication capabilities to develop these technologies. Rapid prototyping soft lithography capabilities are established in-house and protocols specific to the lab equipment are developed. These prototyping methods are then adapted for the fabrication of microfluidic membraneless fuel cells. Fabrication techniques using polymeric stencils and photoresist-based channel structures are developed to enable electrode patterning and current collection in the enzymatic and co-laminar fuel cells of interest. A variety of electrode patterning methods are developed. Gold electrode patterning by etching and lift-off techniques are investigated for the patterning of base electrode layers. An in-situ gold electrode patterning methodology is designed and tested, eliminating the need for precision alignment during device assembly. Carbon electrode patterning methods are developed for use in a vanadium-based colaminar fuel cell. Thin-film carbon electrodes are fabricated using a mixture of carbon microparticles and a polymeric binder. Alternatively, graphite rods are investigated for use as electrodes due to their high conductivity and chemical stability. The integration of channel structure and electrode fabrication methods is investigated to establish compatibilities and facilitate the assembly of functional devices. In addition to the development of these methods, the application of co-laminar streaming to microfabrication is explored through the development of a dynamic microfluidic photomasking device.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
This thesis is part of an ongoing collaborative research project focused on the development of microstructured enzymatic fuel cells. Both enzymatic fuel cells and co-laminar fuel cells are, more generally, varieties of microfluidic membraneless fuel cells. A primary goal of this particular work is the establishment of microfabrication capabilities to develop these technologies. Rapid prototyping soft lithography capabilities are established in-house and protocols specific to the lab equipment are developed. These prototyping methods are then adapted for the fabrication of microfluidic membraneless fuel cells. Fabrication techniques using polymeric stencils and photoresist-based channel structures are developed to enable electrode patterning and current collection in the enzymatic and co-laminar fuel cells of interest. A variety of electrode patterning methods are developed. Gold electrode patterning by etching and lift-off techniques are investigated for the patterning of base electrode layers. An in-situ gold electrode patterning methodology is designed and tested, eliminating the need for precision alignment during device assembly. Carbon electrode patterning methods are developed for use in a vanadium-based colaminar fuel cell. Thin-film carbon electrodes are fabricated using a mixture of carbon microparticles and a polymeric binder. Alternatively, graphite rods are investigated for use as electrodes due to their high conductivity and chemical stability. The integration of channel structure and electrode fabrication methods is investigated to establish compatibilities and facilitate the assembly of functional devices. In addition to the development of these methods, the application of co-laminar streaming to microfabrication is explored through the development of a dynamic microfluidic photomasking device.
Author: Kamil S. Salloum
Publisher:
ISBN:
Category : Fuel cells
Languages : en
Pages : 111
Get Book Here
Book Description
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.
Author: Yifei Wang
Publisher:
ISBN: 9781361041956
Category :
Languages : en
Pages :
Get Book Here
Book Description
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
Author: 羅詩靜
Publisher:
ISBN:
Category : Fuel cells
Languages : en
Pages : 0
Get Book Here
Book Description
Author: Tim Zhao
Publisher: Academic Press
ISBN: 0080878873
Category : Technology & Engineering
Languages : en
Pages : 312
Get Book Here
Book Description
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
Author: Vimal Katiyar
Publisher: Springer Nature
ISBN: 9813298049
Category : Technology & Engineering
Languages : en
Pages : 483
Get Book Here
Book Description
This book provides a systematic overview of the processing and applications of sustainable polymers. The volume covers recent advances in biomedical, food packaging, fuel cell, membrane, and other emerging applications. The book begins by addressing different sections of biomedical application including use of carbohydrate-based therapeutics, nanohybrids, nanohydrogels, bioresorbable polymers and their composites, polymer-grafted nanobiomaterials for biomedical devices and implants, nanofibres, and others. The second part of this book discusses various processing and packaging materials for food packaging applications. The last section discusses other emerging applications, including using microbial fuel cells for waste water treatment, microfluidic fuel cells for low power applications, among others. This volume will be relevant to researchers working to improve the properties of bio-based materials for their advanced application and wide commercialization.
Author: Andrzej Wieckowski
Publisher: John Wiley & Sons
ISBN: 0470463740
Category : Science
Languages : en
Pages : 722
Get Book Here
Book Description
Wiley Series on Electrocatalysis and Electrochemistry Fuel Cell Catalysis A Surface Science Approach A Core reference on fuel cell catalysis Fuel cells represent an important alternative energy source and a very active area of research. Fuel Cell Catalysis brings together world leaders in this field, providing a unique combination of state-of-the-art theory and computational and experimental methods. With an emphasis on understanding fuel cell catalysis at the molecular level, this text covers fundamental principles, future challenges, and important current research themes. Fuel Cell Catalysis: Provides a molecular-level description of catalysis for low-temperature polymer-electrolyte membrane fuel cells, including both hydrogen-oxygen cells and direct alcohol cells Examines catalysis issues of both anode and cathode such as oxygen reduction, alcohol oxidation, and CO tolerance Features a timely and forward-looking approach through emphasis on novel aspects such as computation and bio-inspiration Reviews the use and potential of surface-sensitive techniques like vibrational spectroscopy (IR, Raman, nonlinear spectroscopy, laser), scanning tunneling microscopy, X-ray scattering, NMR, electrochemical techniques, and more Reviews the use and potential of such modern computational techniques as DFT, ab initio MD, kinetic Monte Carlo simulations, and more Surveys important trends in reactivity and structure sensitivity, nanoparticles, "dynamic" catalysis, electrocatalysis vs. gas-phase catalysis, new experimental techniques, and nontraditional catalysts This cutting-edge collection offers a core reference for electrochemists, electrocatalysis researchers, surface and physical chemists, chemical and automotive engineers, and researchers in academia, research institutes, and industry.
