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Student Number 973203058
Author Chan-Wei Kuo(郭展維)
Author's Email Address kuo.chan.wei@gmail.com
Statistics This thesis had been viewed 803 times. Download 211 times.
Department Mechanical Engineering
Year 2009
Semester 2
Degree Master
Type of Document Master's Thesis
Language zh-TW.Big5 Chinese
Title The improvement of water electrolysis efficiency by magnetic forces
Date of Defense 2010-07-05
Page Count 78
Keyword
  • Lorenz force
  • magnetization
  • MHD(magnetohydrodynamic)
  • water electrolysis
  • Abstract Among the methods of hydrogen production, water electrolysis has many advantages, such as high efficiency, high purity in producing hydrogen, easy in use, etc., and thus becomes one of popular methods. During the process of releasing energy, hydrogen produces no green-house-effect gas and has potential as a energy carrier in the future.
    In this study, we use ferromagnetism material (nickel), paramagnetism material (platinum), and diamagnetism material (graphite) as electrodes, respectively. Experimental set-up are modified to study the effects of working parameters, such as concentration of electrolyte, current, voltage, electrode distance and magnetic field on the water electrolyies. As water electrolysis is conduced with an electric field perpendicular to a magnetic field, Lorenz force will produce magnetohydrodynamic (MHD) convection and effect the gas bubble evolution.
    At 25oC, water electrolysis is operated in a static, uniform magnetic field, which is superimposed perpendicular to the current direction in order to make upward and downward MHD convection. The results of experiment show that magnetization of ferromagnetism material is influenced greatly than the others by magnetic field.The maximum current density enhancement of ferromagnetism material(Ni) is about 14% , while it is about 14% for paramagnetism material(Pt) , The current density enhancement of diamagnetism material (C)is few.
    Table of Content 目錄
    摘要..................................................................................................I
    ABSTRACT..................................................................................................II
    目錄..................................................................................................III
    表目錄..................................................................................................VII
    圖目錄..................................................................................................VIII
    符號說明..................................................................................................XI
    第一章 序論...........................................................................................1
    1-1 前言 ............................................................................................ 1
    1-2 文獻回顧..........................................................................................3
    1-3 研究目的與動機 .................................................................................. 5
    第二章 理論基礎.......................................................................................7
    2-1 電解水產氫之基本原理 ............................................................................ 7
    2-2 電解電壓........................................................................................ 10
    2-3 電解液溫度對電解反應之影響 ..................................................................... 10
    2-4 法拉第電解定律 ................................................................................. 11
    2-5 極化作用........................................................................................ 11
    2-5-1 濃度極化 ..................................................................................... 12
    2-5-2 活性極化(activation polarization) ............................................................ 14
    2-5-3 歐姆極化 ..................................................................................... 16
    2-6 勞侖茲力(Lorentz force) ........................................................................ 17
    2-7 物質之磁化 ..................................................................................... 20
    2-7-1 順磁性材料(paramagnetism) .................................................................... 21
    2-7-2 鐵磁性材料(ferromagnetism) ................................................................... 21
    2-7-3 逆磁性材料(diamagnetism) ..................................................................... 22
    2-7-4 磁滯現象 ..................................................................................... 22
    2-8 電導度 ......................................................................................... 23
    2-9 線性掃描伏安法 ................................................................................. 24
    2-10 塔弗方程式 ........................................................................... 25
    2-11 電流效率 ................................................................................ 25
    2-12 分解電壓之測定 ................................................................... 26
    第三章 實驗裝置......................................................................................27
    3-1 實驗簡述 ................................................................................. 27
    3-2 實驗材料及藥品 ..................................................................... 27
    3-2-1 實驗材料 ...................................................................... 27
    3-2-2 實驗藥品 ...................................................................... 28
    3-3 電極材料 ................................................................................. 28
    3-3-1 鐵磁性電極材料-鎳電極(Ni) .................................... 29
    3-3-2 順磁性電極材料-白金電極(Pt)................................. 29
    3-3-3 逆磁性電極材料-石墨電極(C) ................................. 29
    3-4 實驗儀器 ................................................................................. 30
    3-4-1 恆電位儀 ...................................................................... 30
    3-4-2 導電度測量器 .............................................................. 31
    3-4-3 溫度測量器 .................................................................. 31
    3-5 實驗架構 ................................................................................. 31
    3-6 實驗變因 ................................................................................. 32
    3-7 實驗步驟 ................................................................................. 32
    3-8 注意事項 ................................................................................. 33
    第四章 結果與討論..............................................................................34
    4-1 無磁場效應時各實驗參數對產氫之影響分析 .................... 34
    4-1-1 電極材料之影響 .......................................................... 34
    4-1-2 電極間距之影響 .......................................................... 35
    4-1-3 電解液濃度之影響 ...................................................... 37
    4-2 磁場效應對產氫效率之影響 ................................................ 38
    4-2-1 磁場方向及電極材料對磁場效應之影響 .................. 38
    4-2-2 磁場效應對電極材料之影響 ...................................... 40
    4-2-3 電極間距對磁場效應之影響 ...................................... 41
    4-2-4 電解液濃度對磁場效應之影響 .................................. 43
    4-3 電解產氫中電極材料選用之探討 ........................................ 45
    第五章 結論與建議..............................................................................47
    5-1 結論 ......................................................................................... 47
    5-2 未來研究方向與建議 ............................................................. 48
    參考文獻.......................................................................................49
    表目錄
    表(1-1) 氫氣物理特性表 ........................................................................ 53
    表(1-2) 能量密度 .................................................................................... 53
    表(2-1) 常見逆磁材料之磁化率[27] ...................................................... 54
    表(2-2) 濃度為1N 的電解質溶液分解電壓(Pt 為電極)[20] ................ 54
    表(3-1) 各種材料之導電度 .................................................................... 55
    表(3-2) 各電極在KOH 電解液中氧過電壓與分解電壓[28] ............... 56
    表(4-1) 25℃時KOH 導電度 .................................................................. 57
    圖目錄
    圖(1-1) 水分子磁化後鍵角變化情形 ................................................... 57
    圖(2-1) 不加磁場時,原子磁偶極矩不規則分布之示意圖[24] ........ 58
    圖(2-2) 加一向右之磁場時,原子磁偶極矩順磁場方向排列之示意圖[24] ................................. 58
    圖(2-3) 電子之軌道運動示意圖[24] ..................................................... 59
    圖(2-4) 電子之自旋及自旋磁偶極距之示意圖[24]............................. 59
    圖(2-5) 典型之磁滯曲線[25] ................................................................. 60
    圖(2-6) 磁導率較大之磁滯曲線圖[26]................................................. 60
    圖(2-7) 磁導率較小之磁滯曲線圖[26]................................................. 61
    圖(2-8) 25℃時,KOH 導電度和濃度之關係圖 .................................. 61
    圖(2-9) 極化曲線示意圖[20] ................................................................. 62
    圖(2-10) 分解電壓示意圖 ....................................................................... 62
    圖(3-1) 實際電解槽照片 ....................................................................... 63
    圖(3-2) 恆電位儀 ................................................................................... 63
    圖(3-3) 導電度量測計 ........................................................................... 64
    圖(3-4) 溫度量測計 ............................................................................... 64
    圖(3-5) 實驗架構示意圖 ....................................................................... 65
    圖(3-6) 實驗步驟流程圖 ....................................................................... 66
    圖(4-1) 不同電極之電壓-電流曲線(電極間距2mm、電解液濃度30wt%)....................................................................................... 67
    圖(4-2) 鎳電極在不同間距時的電壓-電流曲線(30wt%) .................... 67
    圖(4-3) 白金電極在不同間距下之電壓-電流曲線(30wt%) ................ 68
    圖(4-4) 石墨電極在不同間距下之電壓-電流曲線(30wt%) ................ 68
    圖(4-5) 鎳電極在不同濃度下之電壓-電流曲線(2mm) ....................... 69
    圖(4-6) 白金電極在不同濃度下時之電壓-電流曲線(2mm) ............... 69
    圖(4-7) 石墨電極在不同濃度下之電壓-電流曲線(2mm) ................... 70
    圖(4-8) 白金電極在不同磁場方向時之電壓-電流曲線圖(2mm、30wt%)............................ 70
    圖(4-9) 白金電極在不同磁場方向之電流差值(2mm、20wt%) ......... 71
    圖(4-10) 鎳電極在不同磁場方向時之電壓-電流曲線圖 (2mm、30wt%)....................... 71
    圖(4-11) 鎳電極在不同磁場方向之電流差值(2mm、20wt%) ............. 72
    圖(4-12) 石墨電極在不同磁場方向之電流差值(2mm、40wt%) ......... 72
    圖(4-13) 在MHD 影響下流場示意圖:(a)勞侖茲力往下時(NS 方向磁場),(b)勞侖茲力往上時(SN 方向磁場) ................................ 73
    圖(4-14) 電極間距10mm、KOH、wt40%、電壓4V 時,實際拍攝電解之氣體流向圖:(a)勞侖茲力往下(b)無磁場狀態下(c)勞侖茲力往上 ................................................................................... 73
    圖(4-15) 鎳電極在不同間距下、勞侖茲力向上之電壓-電流曲線 ...... 74
    圖(4-16) 白金電極在不同間距下、勞侖茲力向上之電壓-電流曲線 .. 74
    圖(4-17) 石墨電極在不同間距下、勞侖茲力向上之電壓-電流曲線 .. 75
    圖(4-18) 不同電極材料、勞侖茲力往上與未加入磁場時電解液濃度與電流值之關係圖(10mm、4V) ................................................. 75
    圖(4-19) 不同電極材料、勞侖茲力往上與未加入磁場時電解液濃度與電流值之關係圖(5mm、4V) ................................................... 76
    圖(4-20) 不同電極材料、勞侖茲力往上與未加入磁場時電解液濃度與電流值之關係圖(2mm、4V) ................................................... 76
    圖(4-21) 不同電極材料在3.5V 與4V 時之電流密度(無磁場、間距2mm、濃度30%) ..................................................................... 77
    圖(4-22) 不同電極材料之電壓-電流曲線(勞侖茲力向上、間距2mm、濃度30%).................................................................................. 77
    圖(4-23) 不同電極材料在3.5V 與4V 時之電流密度(鎳電極加入磁場,白金電極無磁場、間距2mm、濃度30%) .................... 78
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    Advisor
  • Lih-Wu Hourng(洪勵吾)
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    Date of Submission 2010-07-15

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