本論文利用微機電製程技術開發出數種表面改質技術，並將此技術應用於過熱蒸氣冷凝系統上。本文採用的表面處理原理即在親水性的基材上塗佈疏水性的材料，包括十八烷三氯矽烷(OTS)及十二烷硫醇(Thiol)，並利用黃光微影製程定義疏水性材料塗佈的密度。根據親疏水性分佈的面積密度不同，可得到任意接觸角的表面，其接觸角的變化範圍在親水性基材與疏水性材料之間變動。本文並依據Cassie-Baxter equations的理論基礎，得到一個新的且平坦的複合表面之接觸角理論值，並將理論值與實驗值做比較，誤差在合理的範圍內。本研究將表面改質技術應用在蒸氣冷凝系統的垂直式的冷凝板上。影響冷凝效率有兩個機制，分別是「成核速率」及「液滴移動」機制。本論文將以此二機制作為探討冷凝效率的依據。表面改質冷凝板分成兩類，分別是均勻改質表面及非均勻改質表面。本實驗中冷凝板的架設是垂直式的，因此冷凝液滴可利用重力離開冷凝板表面。在均勻改質表面上冷凝液滴必須完全利用重力做為液滴的驅動力；在非均勻改質表面上將利用表面張力的不平均來協助液滴移動，使冷凝液滴在較小的質量下便能快速移動離開冷凝板。非均勻表面的設計主要有梯度表面及梳狀表面兩種，目的都是在冷凝液滴形成後即開始移動。實驗結果顯示，梳狀表面的冷凝板有助於蒸氣冷凝熱傳量的提升，因此利用特殊設計冷凝板可有效提升冷凝熱傳量。

　In this article, several surface modification technique have been presented, they are applied to supersaturated vapor condensation system. The principle of surface modification technique is to coat a layer of hydrophobic material on a hydrophilic substrate made up of silicon dioxide. Hydrophobic materials include octadecyltrichlorosilane, 1-Dodecanethoil, and the distribution of area ratio of hydrophilic- hydrophobic is defined by MEMS techniques. According to the distribution of area ratio, the contact angle of modified surface changes arbitrarily and ranges between those two materials. Based on the theory of Cassie-Baxter equations, a theoretical contact angle of a new composite surface will be obtained and compared with experimental data, and the error is endurable. The surface modification technique is applied to a vertical condensation system. There are two mechanisms effecting condensation efficiency, the rate of nucleation as well as the movement of droplet. In this article, the discussion is based on those two mechanisms. There are two different types of surface modified condensation plate, and they are homogeneous condensation plates and heterogeneous ones. The experiment setup is vertical, so that the gravity effect will be able to help the droplet to move. On the homogeneous condensation plates, the droplet is driven by gravity effect only, but on the heterogeneous ones the droplet is not only driven by gravity effect, but the unbalanced surface tension. There are two majorities designs of heterogeneous condensation plates, the one is gradient surface, the other is comb surface. The experiment results that the comb surfaces will enhance the condensation heat flux effectively.

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