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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/2754

    Title: 平板式固態氧化物燃料電池氣態多孔管道之速度量測;DPIV Measurements of Gaseous Porous Ducts for Planar SOFC
    Authors: 簡奇偉;Chi-Wei Chien
    Contributors: 機械工程研究所
    Keywords: DPIV量測;滑移速度;雙極板;固態氧化物燃料電池;多孔性流道;slip velocity;Solid oxide fuel cell;porous flow channel;bipolar plate (interconnect);DPIV measurement
    Date: 2006-07-15
    Issue Date: 2009-09-21 11:54:52 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本論文以實驗的方法,研究平板式固態氧化物燃料電池(solid oxide fuel cell, SOFC)內部流體流動的特性。第一個重點,利用實驗室已有之SOFC雙極板流道水力測試平台,使用具雙進氣口與單排氣口設計之雙極板,定性探討流體於不同分流設計概念之流場分佈情形。結果顯示,以鎳網(Ni mesh)來分流模擬陽極端燃料比使用矩形肋條(ribs)之分流設計有較佳的流場均勻性。然而,鎳網流場之速度分佈仍呈一拋物曲線(parabolic curve),經與核能研究所電化學反應所產生之鎳網劣化分佈情形作比對後,發現彼此均具有同樣之拋物線分佈,故分流速度分佈對流場均勻度之提升或可改善鎳網劣化之情形,提昇SOFC之壽命。第二個但同等重要的研究重點,為利用數位質點影像測速儀(DPIV),進行定量量測氣態單一矩形管多孔流道內部及界面處之全場速度分佈。流道模型之尺寸是以核能研究所之SOFC單一流道為參考依據,等比例放大十倍。進行測試的多孔材料包含鎳網、石膏、氧化鋯和氧化鋁等四種,由孔隙分析儀量測所得之孔隙度(ε),分別為43%、40%、17和4%。由DPIV量測所得的數據可以得知,流體與多孔介質材料界面接觸的附近會產生滑移速度,且滑移速度會隨ε值增加而增加。其中在z/D = 0.025處(目前可準確量測到距多孔介質材料界面最近垂直間距為z= 0.2 mm,其中D為流道高度),鎳網材料(ε = 43%)有最大的滑移速度,是固體界面(ε = 0)同一高度之速度的2.73倍,顯示非滑移條件(non-slip condition)完全不適用於多孔介質之邊界條件,此結果對正確預測雙極板流道流速分佈及其相應之壓力分佈有重要的影響。 This thesis investigates experimentally flow transport phenomena in planar solid oxide fuel cell (SOFC). The first objective is to measure flow uniformity in a series of rectangular flow channels with different gas distributors using hydraulic platform. The geometries of the feed and the exhaust headers are kept the same for all experiments using the double-inlet/single outlet design, but different distributors such as ribs and Ni-mesh are applied in attempt to increase flow uniformity. Based on flow visualizations, it is found that a better flow uniformity can be produced when using Ni-mesh than using ribs. But the velocity profile across the transverse of Ni-mesh is nearly parabolic, very similar to the degradation profile of NiO occurred in Ni-mesh after single cell test operation. Probably, the better flow uniformity can lessen the degradation problem and extend the longevity of the cell. The second but equally important objective is to quantitatively measure the flow velocity field in a single gaseous porous rectangular duct using digital particle image velocimetry (DPIV). The porous media used in this study are Ni-mesh, gypsum, chromium oxide (ZrO2), and aluminum oxide (Al2O3), of which individual porosities (ε=pore volume/bulk volume) measured by the porosimeter are 43%, 40%, 17%, and 4%, respectively. It is found that the slip velocity at the interface between the porous surface boundary and the air significant. The slip velocity increases with increasing porosity. The maximum dimensionless slip velocity, defined as U(ε)/U(ε=0) at z/D = 0.025, is equal to 2.73 when the Ni-mesh (ε=43%) was used. Thus, the traditional non-slip condition cannot be used at the interface between the air and the porous medium. This result is important for correct estimations of velocity and pressure distributions in interconnects.
    Appears in Collections:[機械工程研究所] 博碩士論文

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