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博碩士論文 etd-0911107-182249 詳細資訊
Title page for etd-0911107-182249
論文名稱
Title
甲醇在含有Pd/ZnO觸媒之微流道重組器之數值模擬研究
Numerical study for the performance of a methanol micro-channel reformer with Pd/ZnO catalyst.
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
117
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2007-07-25
繳交日期
Date of Submission
2007-09-11
關鍵字
Keywords
數值模擬、甲醇蒸汽重組、微流道熱質傳、燃料電池重組器、微流道重組器、Pd/ZnO觸媒
micro-channel reformer, numerical simulations, methanol steam reforming, Fuel cell reformer, micro-channel heat and mass transfer, Pd/ZnO catalyst
統計
Statistics
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中文摘要
重組器是燃料電池重要的製造氫氣機構,燃料經重組器壁面觸媒催化反應後,生成氫氣及一些化學物質。重組過程需使用觸媒以降低反應氣體活化能,使重組反應得以在微流道結構因氣體和觸媒有充分碰撞機會而快速進行。
本文研究具有Pd/ZnO觸媒之甲醇微流道重組反應過程,以數值模擬探討不同流道長度、流道高度、流道入口速度、流道入口溫度及觸媒使用率(覆蓋壁面之百分比)下之甲醇重組過程之微流道熱質傳及甲醇轉化比例,藉以估算甲醇重組器在該條件下之氫氣產量。
由模擬結果顯示:甲醇轉化比例及氫氣產量隨著流道長度的增加而增加,到3000μm時已幾乎完全轉化;甲醇轉化比例隨流道入口速度增加而遞減,但氫氣產量則還與流速有關;甲醇轉化比例隨流道高度的增加而降低;提高入口溫度可提升甲醇轉化比例,但超過523K後氫氣產量反而出現負成長,此乃因為了提高溫度必須預燃燒較多甲醇,使得甲醇進料量減少而降低氫氣產量;甲醇轉化比例及氫氣產量隨觸媒使用率的增加而遞增,值得注意的是超過50%後氫氣產量成長率不及15%。本文之結果可供研究人員對甲醇重組器設計之參考。
Abstract
Methanol micro-channel reformer is an important device for generating hydrogen to supply micro fuel-cell needs. In the fuel reforming process, the catalyst is adopted to reduce the activation energy and speed up the reforming reaction. Hydrogen and other chemical substance are produced in the reformer catalytic reaction. The micro-channel structure provides more opportunity for molecules of methanol and steam mixture to collide with catalyst for high reforming reaction to take place.
The reforming process of methanol in a micro-channel reformer with Pd/ZnO catalyst is studied numerically in this thesis. The effects of various channel length, channel height, inlet velocity, inlet temperature, and catalyst usage (ratio of wall area covered by catalyst) on the performance of reformer (methanol conversion percentage) are investigated numerically.
The results show that the methanol conversion increases with increased channel length until a channel length of about 3000μm, the conversion approaches 100%. The conversion percentage decreases with increased inlet velocity, however, the production rate of hydrogen depends on flow rate and conversion percentage. Increasing the channel height results in decreased methonal conversion due to less collision opportunity with the catalyst. The methanol conversion percentage increases with the increase of the inlet temperature. However, the production rate of the hydrogen starts to descend when the inlet temperature is higher than about 523 K owing to more methonal preburned in raising the inlet temperature. Methanol conversion increases with the catalyst usage. However, it is worth noting that the increase is only about 15% for catalyst usage from 50% to 100%.
The results in this study provide design data for the fuel cell system designer.
目次 Table of Contents
目 錄 I
圖目錄 IV
表目錄 XIV
中文摘要 XV
英文摘要Abstract XVI
符號說明 XVII
第一章 緒論 1
1-1 前言 1
1-2 研究動機與目的 6
1-3 文獻回顧 7
第二章 理論分析 16
2-1 統御方程式(Governing equation) 16
2-1-1 流場統御方程式 17
2-1-2 化學反應方程式 19
2-2 邊界條件 21
2-2-1 流動邊界條件 21
2-2-2 熱質傳邊界條件 22
2-2-3 物質及混合物性質設定 24
2-3 求解程序和誤差設定 26
第三章 數值方法 27
3-1 數值模擬簡介 27
3-2 模擬軟體簡介 28
3-3 FLUENT離散方法 29
3-4 層流有限率法(Laminar Finite-Rate Model)[37] 30
3-5 速度與壓力連結 33
第四章 結果與討論 36
4-1 流道長度的影響 36
4-2 流道入口速度的影響 37
4-3 流道高度的影響 38
4-4 流道入口溫度的影響 39
4-5 觸媒使用率的影響 39
第五章 結論與建議 84
5-1 結論 84
5-2 建議與展望 86
參考文獻 87
附錄一 92
附錄二 93
附錄三 94
附錄四 96
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