臺灣博碩士論文加值系統

水是人類發展與生存不可或缺的重要資源，在西亞和非洲地區，將因為氣候驟變與人口過量，使水資源的取得更加困難。而水資源的獲取，若僅僅依靠不穩定的自然降雨，已無法滿足各方面的供給需求。在較乾旱的地區，露水資源甚至能超越自然降雨量，所以，露水將有潛力作為水資源的供給來源，因此露水凝結的開發與利用，勢必是未來相當重要的工作。
本研究透過表面曲率半徑與接觸角的變化，探討空氣中水分凝結為液滴的物理機制。使用計算流體力學（Computational Fluid Dynamics, CFD）軟體進行研究，以二維的兩相流模型並配合相位場方法進行數值模擬，特別是以亂數分佈的液氣相作為相位場的初始條件來進行相位場轉換。結果顯示，在曲率半徑愈小的表面上，能夠愈快生成液滴，而親水性表面亦比疏水性表面更易於凝結液滴。本研究利用亂數數學模型模擬液滴之凝結達成初步成果，對於往後的露水凝結之研究及優化有著重要的意義。

Water is an indispensable resource for human development and survival. In West Asia and Africa, access to water resources will be made more difficult due to sudden climate change and overpopulation. The acquisition of water resources, if only relying on unstable natural rainfall, can no longer meet the supply demands. In arid areas, dew resources can even surpass natural rainfall. Therefore, dew will have potential as a source of water resources, so the development and utilization of dew condensation is bound to be a very important task in the future.
This study explored the physical mechanism of moisture condensation in the air as droplets through changes in the surface radius of curvature and contact angle. Using computational fluid dynamics (CFD) software, the two-dimensional two-phase flow model is combined with the phase-field method for numerical simulation. In particular, the phase field conversion is performed by using the liquid-vapor phase of the random distribution as initial conditions of the phase field. The results show that on the surface with the smaller radius of curvature, the droplets can be formed faster, and the hydrophilic surface is more likely to condense droplets than the hydrophobic surface.

摘　要 i
ABSTRACT ii
誌　謝 iii
目　錄 iv
表目錄 vii
圖目錄 viii
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 2
1.3 冷凝 3
1.4 表面潤濕性 4
1.4.1 內聚力與附著力 4
1.4.2 表面張力 5
1.4.3 楊式方程式與接觸角 7
1.4.4 蓮花效應 8
1.4.5 粗糙表面與異質表面之接觸角 9
1.5 文獻回顧 12
1.5.1 超疏水表面上冷凝液滴自主掃除 12
1.5.2 在非潤濕性表面上液滴聚合後自主跳離之現象 15
1.5.3 以奈米草微金字塔結構進行連續滴狀冷凝 17
1.5.4 數值模擬在微通道中人造腔體的流動沸騰 19
1.5.5 在光滑不對稱凸起表面上的凝結 20
1.5.6 相位場模型的數值實行所面臨之基準問題 23
1.6 文獻回顧總結 25
第二章 控制方程式與數值方法 26
2.1 簡介 26
2.2 控制方程式 26
2.2.1 連續方程式 27
2.2.2 動量守恆方程式 27
2.2.3 能量守恆方程式 27
2.3 數值方法 28
2.3.1 相位場模型 29
2.3.2 相轉換方程式 31
2.4 離散化方法 32
2.4.1 有限差分法 32
2.4.2 有限體積法 33
2.4.3 有限元素法 33
第三章 模擬步驟與參數設定 34
3.1 數值模型 35
3.2 計算區域與邊界條件 36
3.3 網格建立 38
第四章 結果與討論 39
4.1 模擬結果 39
4.1.1 表面曲率半徑0.53mm及接觸角30° 39
4.1.2 表面曲率半徑0.53mm及接觸角90° 42
4.1.3 表面曲率半徑0.53mm及接觸角150° 45
4.1.4 表面曲率半徑1.5mm及接觸角30° 48
4.1.5 表面曲率半徑1.5mm及接觸角90° 51
4.1.6 表面曲率半徑1.5mm及接觸角150° 54
4.1.7 表面曲率半徑4.2mm及接觸角30° 57
4.1.8 表面曲率半徑4.2mm及接觸角90° 60
4.1.9 表面曲率半徑4.2mm及接觸角150° 63
4.2 討論 66
第五章 結論與未來展望 68
5.1 結論 68
5.2 未來展望 68
參考文獻 69

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