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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/65349


    Title: 磁場對水電解產氫效率增益之機制研究;The investigation on the mechanism of efficiency enhancement for hydrogen production by water electrolysis with magnetic field
    Authors: 吳慶鴻;Wu,Ching-hung
    Contributors: 能源工程研究所
    Keywords: 電解水;勞侖茲力;磁流體動力學;Water electrolysis;Lorenz force;magnetohydrodynamic
    Date: 2014-07-08
    Issue Date: 2014-10-15 15:28:46 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本實驗利用鎳電極,在電解液氫氧化鉀濃度25wt%時,進行電解水產氫,由恆電位儀與高速攝影機所記錄得到的資料,探討不同電流密度、電極間距加入磁場後,氣泡上升速度與氣泡覆蓋率,受到磁流體動力學(MHD)中向上勞侖茲力(Lorentz force)之影響。
    加入磁場狀態下,磁力會形成向上之勞倫茲力,促使氣泡加速脫離電極表面,因此,由拍攝之圖片顯示出,在不同之電極間距、不同之電流密度,氣泡速度皆會增加,而氣泡覆蓋率則是會下降,並且發現,電極表面上之最大顆氣泡較小、分布數量最多的氣泡,其直徑也較小。
    結合氣泡速度與覆蓋率,可得體積流率之結果,加入磁場狀態下,電極間距2 mm、電流密度0.3 A/m^2,體積流率增加率為67.8 %;電極間距5 mm、電流密度0.3 A/m^2,體積流率增加率為42 %,兩者節省之電功率百分比,也皆有極小之增加值。
    水電解產氫是目前製造氫氣常用之方法,而磁場無須耗費額外之能量,卻能使產氫效率增加,也能節省能量之消耗,在未來相當具發展潛力。
    ;As water electrolysis is conducted with an electric field perpendicular to a magnetic field, Lorenz force will produce magnetohydrodynamic (MHD) convection and affect the gas bubble evolution. This experiment uses nickel as electrodes, and the potassium hydroxide electrolyte concentration is 25wt%. Potentiostat and high-speed camera are used to record the bubble evolution.
    The upward Lorentz force can accelerate the speed bubbles to leave the surface of the electrode, which lowers the electrochemical polarization. Therefore, from the bubble behavior shown in the picture. We observe that all the bubbles will be speeded under the action of Lorenz force for different electrode distances and current densities. However, the coverage of bubbles is reduced. The biggest bubble on the electrode surface is smaller. The bubble diameter of the maximum amount of bubbles distribution is smaller.
    Bubble flow rate can be obtained by combing the bubble speed and coverage. In a upward Lorentz force, the electrode distance 2 mm and current density 0.3 A/m^2, the flow rate increases about 67.8%. While it is about 42% for the electrode distance 5 mm and current density 0.3 A/m^2. The economic power efficiency was also saved a little.
    Water electrolysis is a commonly used method to produce Hydrogen. Magnetic field does not need to consume additional energy. However, it can increase hydrogen production efficiency and reduce energy consumption. Water electrolysis adds magnetic field has development potential in the future.
    Appears in Collections:[能源工程研究所 ] 博碩士論文

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