本研究之目的為探討氮氣與氧氣於邊界阻礙物微混合器中之混合效應，同時透過數值模擬與實驗量測來相互驗證及比對。首先以數值軟體ANSYS CFX針對入口及主流道皆為長10 mm、寬1 mm、深125 μm之T型微混合器進行流場模擬，之後在主流道加入數種不同邊界阻礙物結構，形成對齊式、交錯式、三角型微混合器，討論雷諾數範圍1~150的區間，阻礙物結構對氣體流場、混合效率、壓降之影響。除此之外，改變阻礙物長度及寬度，找出最佳的尺寸為長400 μm、寬400 μm之阻礙物，作為後續實驗設計的參考依據。
實驗量測方面，使用PET基材雙面膠帶製作出微混合器，並利用PSP (Pressure-Sensitive Paints)螢光壓力感測技術搭配顯微鏡影像擷取系統得到四種微混合器內部的全域二維氧氣濃度分佈。實驗結果顯示於入口雷諾數在10~150範圍內，T型微混合器中的流體僅透過擴散作用來達到混合，流速的增加(雷諾數增加)會縮短流體的滯留時間，出口處之混合效率會由74.63%降低為24.41%。對齊式微混合器中的流體會因為對齊結構而產生集中後分散接連循環的現象，能縮小兩流體間的擴散距離以提升混合效率。然而緊縮擴結構會加速流體並減少擴散時間，混合效率會隨著雷諾數而下降，壓降則會高於其他三組流道。交錯式流道能使流體產生橫向的速度及動量，產生更多接觸面積以促使流體混合，混合效率為四組微混合器中最高的，能有效改善T型微混合器在高流量時的低混合效率。當Re=50 (Pe=38.19)時，出口處的混合效率為所有雷諾數中最差的86.21%，當Re＜50 (Pe＜38.19)，混合機制先是由擴散來主導；不過當Re＞50 (Pe＞38.19)，阻礙物後方開始產生渦漩，對流開始主導兩流體的混合，混合效率隨著雷諾數增加會先下降而又上升。三角型流道與交錯式流道的混合效果相類似，流體會左右擺動且在高流速時會在阻礙物後方產生渦漩，混合效率也會有先下降而上升的現象，Re=75 (Pe=57.28)時會產生斜率改變的轉折點。而因為實際製程上在尖角處會產生導角，混合效率會較交錯式流道差，在Re=150時，出口端的混合效率減少了21.75%，不過三角型流道能有效降低2.69 kPa的壓降。
本研究成功利用PSP螢光壓力感測技術來量測微混合器中之全域氧氣濃度分佈，以可視化及定量化的方式與數值模擬的結果進行比對及驗證，藉由改變邊界阻礙物的幾何尺寸及入口流速，探討對於氧氣及氮氣之流場特性及混合效應的影響，以達到提升混合效率之目的，有助於微尺度下氣體混合效應之研究。

The aim of this study is to investigate the mixing effects of oxygen and nitrogen gases in micromixers with different designs of boundary obstructions. Numerical simulation and experimental measurement are used to verify and compare at various Reynolds numbers. At first, Numerical software ANSYS CFX is applied to simulate the flow field inside the T-type micromixers. The inlet of two gases and main (mixing) channels are 10 mm long, 1 mm wide, and 125 μm deep. After two gas flow intersecting at the T-junction, rib structures with different designs of symmetric, staggered or triangular are positioned in the main channel to form the micromixers with boundary obstructions. The flow field as well as the mixing efficiency and pressure drop due to these obstructions are investigated and discussed in the Reynolds numbers (Re) ranging from 1 to 150. In addition, different geometrical parameters of aspect ratio of length/width in the obstruction are discussed with simulation and the optimal parameters of obstructions of 400 μm long and 400 μm wide is found to be used in the following experiments.
For the experiment of oxygen and nitrogen gases mixing, Pressure-Sensitive Paint (PSP) and the fluorescence microscope system are utilized to acquire the image of global oxygen concentration inside the four micromixers. The experimental results indicate that the mixing effect in T-type micromixers is merely dominated by diffusion in the range of inlet Re number from 10 to 150. The increase of flow velocity will shorten the residence time of fluid therefore decrease the mixing efficiency at the outlet from 74.63% to 24.41%. For the micromixers with symmetric obstructions, the gas flow passes through the obstructions with accelerating/decelerating while the flow contracts/expands. The distance for diffusion between two gas flows is reduced and mixing efficiency is improved. However, the flow is also accelerated due to constricted structures and reduces the diffused time, and mixing efficiency becomes lower if Re number increases. The pressure drop in the micromixer with symmetric obstructions is higher than the other three designs. Staggered micromixers provide better mixing efficiency by introducing the secondary flow while the gas flow passing the obstructions and generating transverse velocity and momentum, which increase the interfacial area between gases. For the Re number less than 50 (Pe number less than 38.19), mixing mechanism is dominated by diffusion. When Re number equals to 50 (Pe number equals to 38.19), the mixing efficiency reaches the lowest values among all Re number conditions. For the Re number greater than 50 (Pe number greater than 38.19), convection mass transfer dominates the mixing effect with the help of vortices formation behind the obstructions. The mixing efficiency is lower at Re number of 50 (Pe number of 38.19) and then increases with increase in Re number. Staggered obstruction can improve the mixing efficiency effectively at higher velocity and provides the best mixing efficiency among these four designs. Triangular micromixers have the similar mixing efficiency as the staggered one. The triangular obstructions will introduce agitation to the gas flow and generate vortices behind the obstructions at high flow velocity. The mixing efficiency in triangular obstruction has the same trend of staggered one and the minimum mixing efficiency is observed at Re number of 75 (Pe number of 57.28). However, the results might be deviated due to the imperfections of the sharp corners in the triangular obstruction due to manufacturing processes. The mixing efficiency reduces 21.75% compare to that in the staggered micromixers when Re number of 150, but the pressure drop is reduced by 2.69 kPa.
In this study, global oxygen concentrations in micromixers with four different obstruction designs are successfully measured by PSP technique. The visualization and quantitative results are compared to simulation results with ANSYS CFX. This study provides detailed investigation of the gas mixing effects in microscale.

摘要 I
Abstract III
誌謝 VI
目錄 VIII
圖目錄 XI
表目錄 XVIII
第一章、 緒論 1
1.1 研究動機 1
1.2 文獻回顧 3
1.2.1 微混合器的分類 3
1.2.2 被動式微混合器 4
1.2.3 氣體微混合器 9
1.2.4 PSP螢光壓力感測技術於微尺度之發展與應用 13
1.2.5 螢光分子於氣體濃度感測之應用 17
1.3 研究目的 19
1.4 研究架構 21
第二章、 數值模擬分析 22
2.1 微混合器數值模擬 22
2.1.1 數值模擬基本條件設定 22
2.1.2 統御方程式 24
2.1.3 重要計算參數 26
2.1.4 微混合器結構 28
2.1.5 網格獨立測試 32
2.2 數值模擬結果 33
2.2.1 雷諾數對於微混合器的混合效率之影響 33
2.2.2 交錯式流道壁面阻礙物長度(l)對於混合效率之影響 40
2.2.3 交錯式流道壁面阻礙物寬度(w)對於混合效率之影響 44
2.2.4 三角型流道對混合效率及壓降之影響 48
第三章、 實驗原理 53
3.1 PSP螢光壓力感測塗料之基礎理論 53
3.2 螢光壓力感測塗料量測原理 55
第四章、 實驗方法 58
4.1 PSP螢光壓力感測塗料配製 58
4.2 PET雙面膠帶 59
4.3 微混合器製作 61
4.4 實驗儀器架設 63
4.5 實驗操作方法及影像處理 65
4.5.1 影像平均 65
4.5.2 氧氣濃度校正曲線 67
4.5.3 逐點影像校正 69
4.5.4 中位數濾波 70
4.6 實驗誤差分析 72
第五章、 微混合器全域氧氣濃度實驗量測結果與討論 74
5.1 T型微混合器 74
5.2 對齊式微混合器 83
5.3 交錯式微混合器 91
5.4 三角型微混合器 99
5.5 四種微混合器比較 106
第六章、 結論與未來工作建議 109
6.1 結論 109
6.2 未來工作及建議 111
參考文獻 113

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