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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/35474


    Title: 碎形幾何應用於直接甲醇燃料電池之集電板開口設計與其效能探討
    Other Titles: The design and performance investigation of the current collector openings for the direct methanol fuel cell with application of the fractal geometry
    Authors: 張靜怡;Chang, Jing-yi
    Contributors: 淡江大學機械與機電工程學系博士班
    李世鳴;Lee, Shi-min;管衍德;Kuan, Yean-der
    Keywords: 直接甲醇燃料電池;集電板;碎形;交流阻抗分析;Direct Methanol Fuel Cell;Current Collector;Fractal;Electrochemical Impedance Spectroscopy
    Date: 2009
    Issue Date: 2010-01-11 06:38:06 (UTC+8)
    Abstract: 碎形理論是一種有系統的空間切割方法,在工程應用上有許多實例,如熱傳、冷卻、散熱器鰭片設計、以及自動加工路徑等。本文採用碎形幾何圖形,應用於直接甲醇燃料電池之集電板幾何設計,探討集電板其開口方式、開口面積、以及開口周長,對電池性能的影響與電化學交流阻抗分析。
    本文提出三種集電板幾何設計,第一種集電板設計使用Sierpinski Carpets碎形幾何生成,其幾何形狀設計可以對集電板作有系統的切割,其開口率最大為30%。隨著碎形階數越大,可以具有較大的開口率與開口周長,使電池性能較佳,電化學阻抗較低。
    第二種集電板設計使用Hilbert Curve碎形幾何生成,其幾何形狀是對集電板做有系統的連續性切割,開口型態可以在平面區域中進行有效的伸展與平均分佈,開口率最大可達50%。隨著碎形階數越大,可以提供更大的開口率與開口周長,使電池性能提升,電化學阻抗較低。
    第三種集電板設計使用對稱排列矩形開口幾何設計,開口率分別為30%、40%、50%與60%,開口分佈型態設計為對稱式排列,排列方式為,5×5之開口排列,7×7之開口排列與10×10之開口排列。選用適當的開口設計,可以使甲醇與空氣能均勻的分佈於膜電極組中進行電化學反應,並且在陽極端所產生的二氧化碳與陰極端所產生的水得以順利排出,進而提高電池性能。
    The fractal theory is a methodology to systematically segment the space. There are many real examples in the engineering applications, such as heat transfer, cooling, fin design of heatsink, and automatic polishing path. This dissertation adopts fractal geometries to apply on the design of the current collectors of the direct methanol fuel cell and discuss the effect on the cell performance as well as the electrochemical spectroscopy impedance by the free open style, the total free open ratio, and total perimeter length of openings on the current collectors.
    This dissertation presents three geometric designs on the current collectors. The first design is to adopt the Sierpinski carpet fractal geometry to systematically make separate segments on the current collectors. The maximum total free open ratio is 30% by this design. The higher fractal order could provide the current collectors larger total free open ratio as well as longer total perimeter length of openings, such leads the cell have better performance and lower electrochemical impedance.
    The second design is to adopt the Hilbert curve fractal geometry to systematically make continuous segments on the current collectors. Such open style could give effective line extension and average openings spread in the planar area. The maximum free open ratio could reach 50% by this design. The higher fractal order could further provide larger total free open ratio as well as longer total perimeter length of openings, such leads the cell have better performance and lower electrochemical impedance.
    The third design is to adopt the regular rectangle free openings design on the current collectors. The free open ratio is 30%, 40%, 50%, and 60%, respectively. The arrangement of the free openings distribution is 5x5, 7x7, and 10x10, respectively. The proper free openings design could allow the methanol and air uniformly distribute to the membrane electrolyte assembly, such that the electrochemical reactions are able to proceed and the carbon dioxide produced at the anode side could drain successfully, and the cell performance would be further enhanced.
    Appears in Collections:[Graduate Institute & Department of Mechanical and Electro-Mechanical Engineering] Thesis

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