Carbon paper flow fields made by WEDM for small fuel cells

Müller, Monika Freunek; Müller, Claas; Förster, Ralf; Menz, Wolfgang

doi:10.1007/s00542-004-0409-0

Cited by 7 publications

(3 citation statements)

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“…-creating the integral components of FC: GDL made of fibrous materials + nanofibres as catalyst supports, GDL from nanopaper + a thin layer of nanopaper as a catalyst support [2], GDL made of TEG + GDL from carbon fibres [36], porous fibrous GDL + gas-distribution channels in GDL obtained by electroerosion punching [37], GDL in MEB [38], etc. ;…”

Section: Gdl Design Trends Determined By the Marketmentioning

confidence: 99%

Current trends in the design of gas-diffusion layers for fuel cells

Lysenko

2008

Fibre Chem

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The fundamental trends in the design of porous materials (composites) used as gas-diffusion layers (GDL) for fuel cells (FC) were examined. It was shown that the evolution of the FC market has made it necessary to develop manufacturing processes for production of GDL with optimum specifications that provide for mass production of GDL at low cost. It was shown that the current design of GDL emerged from the technical region of basic functionality into the space defined by the vectors of modern technologies and economic characteristics.Fuel cells (FC) with polymer membranes are increasingly being used in practice as environmentally clean sources of energy. A diagram of the design of FC whose basic components are a polymer membrane, catalyst be d, gas-diffusion layers (GDL), gas-distribution plates, and end plates is shown in Fig. 1 [1]. GDL are one of the most important components of FC [2].Gas-diffusion layers for fuel cells with polymer membranes are primarily made from carbon fibre materialscloth or paper [3]. However, due to the turbulent development of hydrogen energetics, an intensive search is underway for new, designer approaches to the creation, production, and market positioning of GDL [4].Development of GDL as FC design elements (for example, alkaline FC or FC with proton-exchange membranes for astronautics [5]) were basically intended for creating GDL with the required specifications. Cost indexes usually have not been of decisive importance.The specifications -GDL sheet thickness, surface roughness, air permeability, porosity, specific electric resistance in the plane and perpendicular to the surface, etc. -are the reflection of the functions that the GDL must fulfill.In generalizing the opinion of the developers of FC relative to the basic technical functions that the GDL must fulfill, we will talk about the basic functionality of the object of the design.Basic functionality of GDL: delivery of gases and liquid reagents (fuel/oxidant: hydrogen/oxygen, methanol/atmospheric oxygen, etc.) to the necessary electrodes, distribution of the reagents in the necessary and controllable manner; delivery of electrons to the electrodes and catalyst bed and removal from them; mechanical support and protection of membranes and catalyst; assistance in removal of heat; transfer of gas-distribution plate and FC set assembly seal loads; participation of FC set internal parts of both the technically complicated component of the membraneelectrode block (MEB), FC, etc.in the interface, can only be determined in the final unit and in the conditions of use.The basic functionality is an extremely important design element, since it must ensure the specifications and to a great degree the cost indexes which will allow the design product to establish itself in the market.An example of a successful GDL design is the product developed in 1980 by Toray in the form of a fibrous carbon-carbon composite. The structural elements and their mutual position are shown in Fig. 2 [6]. In this material, carbon fibres (CF) 7 μm in diameter are...

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Section: Gdl Design Trends Determined By the Marketmentioning

confidence: 99%

Current trends in the design of gas-diffusion layers for fuel cells

Lysenko

2008

Fibre Chem

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“…The lower velocity leads to a longer residence time and better fuel diffusion. This design was implemented by Cha et al [18] in SU-8, by Hahn et al [15] in polymer/steel composite, by Wozniak et al [44] in silicon, by Müller et al in metal foil [45] and in carbon paper [46].…”

Section: Fuel Delivery Systemmentioning

confidence: 99%

Micromachined polymer electrolyte membrane and direct methanol fuel cells—a review

Nguyen¹,

Chan²

2006

J. Micromech. Microeng.

137

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This review reports recent progress of the development of micromachined membrane-based fuel cells. The review first discusses the scaling law applied to this type of fuel cells. Impacts of miniaturization on the performance of membrane-based fuel cells are highlighted. This review includes only the two most common micro fuel cell types: proton exchange membrane micro fuel cells (PEMµFC) and direct methanol micro fuel cell (DMµFC). Furthermore, we only consider fuel cells with active area of a single cell less then one square inch. Since the working principles of these fuel cell types are well known, the review only focuses on the choice of material and the design consideration of the components in the miniature fuel cell. Next, we compare and discuss the performance of different micro fuel cells published recently in the literature. Finally, the review gives an outlook on possible future development of micro fuel cell research.

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“…As research focus in EDM shifted from basic research to applied research [52], there was growing research interest in new EDM techniques such as micro-machining [53][54][55], machining of insulating ceramic materials [56][57][58], EDM using a powder-mixed dielectric [23][24][25], combining EDM with other machining methods in hybrid processes [59][60][61], dry EDM [62][63][64][65] and near-dry EDM [66,67]. In addition, attempts at widening the scope of EDM application to green-related industries have led to studies in the fabrication of fuel cell [68] and solar cell [69] components.…”

Section: The Development Of Edm As a Reliable Machining Technique Alsmentioning

confidence: 99%

Advancing the micro-EDM technique with powder-mixed dielectric and process modelling

Tan¹

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The electrical discharge machining (EDM) process possesses inherent characteristics that make it a promising micro-machining technique. However, micro electrical discharge machining (micro-EDM) is only used in niche applications due to the lack of an established knowledge base to facilitate process planning. The stochastic nature of material removal, sensitivity of process performance to process parameters and conditions and numerous process parameter permutations available for machining contribute to the difficulties in building a knowledge base for micro-EDM. Compounding to this complication, the process parameters and conditions in EDM and micro-EDM are distinctly different, thereby rendering limited transferability of knowledge base. Thus, focused studies on micro-EDM are needed to improve process reliability and controllability as well as to enhance process capabilities. This research has endeavoured to achieve advancement of the micro-EDM technique through a two-pronged approach of process performance enhancement and process modelling. The proposed use of powder-mixed dielectric in micro-EDM (PMD micro-EDM) is a novel initiative to adopt this established technological development in EDM (PMD-EDM) for micro-EDM. By reproducing the effects of improved machined surface quality and enhanced machined surface functional properties of PMD-EDM in PMD micro-EDM, advancements to the micro-EDM process has been achieved. The realisation of PMD micro-EDM has been achieved through employing discharge energies less than 25 µJ with sub-microsecond pulse on time durations and complemented by the use of nanopowder additives of semi-conductive and non-conductive materials in concentrations below 1 g/l. Initial investigations on the unit removal characteristics of PMD micro-EDM have shown a distinct difference in the morphology of craters produced in a powder-free and powder-mixed dielectric, thereby proving the feasibility of PMD micro-EDM. Furthermore, the observation of craters having smaller peak-to-valley heights when generated under single electrical discharge conditions has been exhibited as reductions in arithmetical mean surface roughness of 14 % to 24 % when processing with PMD micro-EDM. Improvements in machined surface quality have also been displayed through reductions in recast layer thickness of between 15 % and 35 %.

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Carbon paper flow fields made by WEDM for small fuel cells

Cited by 7 publications

References 0 publications

Current trends in the design of gas-diffusion layers for fuel cells

Current trends in the design of gas-diffusion layers for fuel cells

Micromachined polymer electrolyte membrane and direct methanol fuel cells—a review

Advancing the micro-EDM technique with powder-mixed dielectric and process modelling

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