本研究之目的在於探討不同親疏水混合表面對冷凝熱傳增益影響，利用表面改質技術結合圖案的設計在冷凝表面上定義出親水區域與疏水區域，製備出具有濕潤性對比的表面，促進液滴的收集與排開，進而提升熱傳效率。在親疏水混合表面的圖形設計上，鑑於三角形圖案具有一驅動力可使液滴往單一方向傳輸，本研究以三角形圖案為基底設計出不同的親疏水混合表面，所有三角形尖端角度為8°，親疏水混合表面主要分為三角形陣列圖形與聖誕樹圖形，並且在三角形陣列圖形設計中，針對三角形的底部寬度與圖形的左右間距個別進行參數化討論，探討各項參數對熱傳所造成的影響。
三角形的底部寬度設計方面，本研究在固定總親水面積為4%的條件下，設計出7組不同底部寬度的三角形陣列混合表面，發現在固定實驗條件下，相較於其他三角形尺寸，底部寬度為1mm時具有最佳的熱傳表現，其增益比(E)可達約1.3，意味著可提高全疏水表面30%的熱通量，並通過實驗觀察各個混合表面的冷凝現象，發現液滴的滴落直徑與刷新頻率隨著底部寬度增加而上升，代表尺寸小的三角形具有較小的液滴滴落直徑及較慢的液滴刷新速度，反之尺寸大的三角形具有較大的液滴滴落直徑及較快的液滴刷新速度，對此現象本研究將數據整理並定義出無因次化液滴滴落直徑(D*)與無因次化刷新週期(P*)，透過數據分析得出當底部寬度為1mm時，P*與D*的乘積為最小值，並與增益比(E)比較，結果表明，底部寬度為1mm時三角形陣列圖形的最佳尺寸設計。
左右間距(L)優化方面，本研究事先利用實驗的方式，記錄冷凝表面上液滴的滴落直徑，透過實驗觀察記錄到的液滴滴落直徑，分別設計出兩組間距(L)的三角形陣列圖形，實驗結果表明，當底部寬度=1mm，且L=3.5mm時具有較佳的熱傳表現，其增益比(E)可達1.6。
鑑於刷新頻率、液滴滴落直徑與圖形尺寸間的關係，本研究亦在L=3.5mm的情況下設計底部寬度=1.4mm ~ 0.7mm的三角形陣列混合表面，其實驗結果表明增益比為1.06，並發現當三角形尺寸過大時，由於底部寬度增加將使得液滴的滴落直徑增加，導致圖形間疏水區域縮小，容易使橋接現象(bridging phenomenon)發生，造成冷凝表面出現過大尺寸的冷凝液滴，導致熱傳效率下降。
此外，本研究所設計的聖誕樹圖形具有良好傳輸效果，增益比(E)可達1.3，在本研究所有設計的親疏水混合表面中，底部寬度為1mm，且左右間距(L)為3.5mm的三角形陣列圖形具有最佳熱傳增益效果，增益比可達1.6，可提高全疏水表面60%的熱通量。

This study investigates condensation heat transfer enhancement by applying surface modification technology with different wettability pattern designs on a copper surface. The research showed that hydrophilic-hydrophobic hybrid surfaces have better condensation heat transfer performance than fully hydrophobic surfaces, because of water transportation and collection. Therefore, the shape and size of the pattern are especially important. The pattern designs in this study include triangular array pattern and christmas tree pattern. The experimental results of the hydrophilic-hydrophobic hybrid surface show that the triangular array pattern with the bottom width of 1 mm and pattern distance at 3.5mm has the best gain ratio, the heat flux efficiently increases 60% by comparing with the hydrophobic surface. Moreover, the christmas tree pattern can smoothly catch the hydrophobic area condensing droplets into the hydrophilic area and form a water gallery to transport the condensation water quickly, which can increase the heat flux of a fully hydrophobic surface by about 30%. Under current development issues that focus on energy conservation, this research applies to various phase change heat transfer components.

[1] E. Schmidt, W. Schurig, and W. Sellschopp, "Versuche über die Kondensation von Wasserdampf in Film- und Tropfenform", Technische Mechanik und Thermodynamik, vol. 1, no. 2, pp. 53-63, 1930.
[2] B. S. Sikarwar, N. K. Battoo, S. Khandekar, and K. Muralidhar, "Dropwise Condensation Underneath Chemically Textured Surfaces: Simulation and Experiments", Journal of Heat Transfer, vol. 133, no. 2, 2011.
[3] H. W. Wen and R. M. Jer, "On the heat transfer in dropwise condensation", The Chemical Engineering Journal, vol. 12, no. 3, pp. 225-231,1976.
[4] J. W. Rose and L. R. Glicksman, "Dropwise condensation—The distribution of drop sizes", International Journal of Heat and Mass Transfer, vol. 16, no. 2, pp. 411-425, 1973.
[5] E. Le Fevre and J. W. Rose, "A theory of heat transfer by dropwise condensation", International Heat Transfer Conference Digital Library, Begel House Inc, 1966.
[6] C. Graham and P. Griffith, "Drop size distributions and heat transfer in dropwise condensation", International Journal of Heat and Mass Transfer, vol. 16, no. 2, pp. 337-346, 1973.
[7] L. Zhong, M. Xuehu, W. Sifang, W. Mingzhe, and L. Xiaonan, "Effects of surface free energy and nanostructures on dropwise condensation", Chemical Engineering Journal, vol. 156, no. 3, pp. 546-552, 2010.
[8] 吳凱翔, "不同接觸角的親疏水表面於冷凝熱傳增益分析", 成功大學航空太空工程學系學位論文, pp. 1-91, 2019.
[9] G. Koch, D. C. Zhang, A. Leipertz, M. Grischke, K. Trojan, and H. Dimigen, "Study on plasma enhanced CVD coated material to promote dropwise condensation of steam", International Journal of Heat and Mass Transfer, vol. 41, no. 13, pp. 1899-1906, 1998.
[10] A. Bani Kananeh, M. H. Rausch, A. P. Fröba, and A. Leipertz, "Experimental study of dropwise condensation on plasma-ion implanted stainless steel tubes", International Journal of Heat and Mass Transfer, vol. 49, no. 25, pp. 5018-5026, 2006.
[11] S. Lee, K. Cheng, V. Palmre, M. M. H. Bhuiya, K. J. Kim, B. J. Zhang, H. Yoon, "Heat transfer measurement during dropwise condensation using micro/nano-scale porous surface", International Journal of Heat and Mass Transfer, vol. 65, pp. 619-626, 2013.
[12] I. Tanasawa and J. i. Ochiai, "Expeimental Study on Dropwise Condensatioin", Bulletin of JSME, vol. 16, no. 98, pp. 1184-1197, 1973.
[13] R. N. Leach, F. Stevens, S. C. Langford, and J. T. Dickinson, "Dropwise Condensation:  Experiments and Simulations of Nucleation and Growth of Water Drops in a Cooling System", Langmuir, vol. 22, no. 21, pp. 8864-8872, 2006.
[14] C. Yamali and H. Merte Jr, "Influence of sweeping on dropwise condensation with varying body force and surface subcooling", International Journal of Heat and Mass Transfer, vol. 42, no. 15, pp. 2943-2953, 1999.
[15] C. Yamali and H. Merte Jr, "A theory of dropwise condensation at large subcooling including the effect of the sweeping", Heat and mass transfer, vol. 38, no. 3, pp. 191-202, 2002.
[16] J. Rose, "Dropwise condensation theory and experiment: a review", Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, vol. 216, no. 2, pp. 115-128, 2002.
[17] J. W. Westwater, "Gold surfaces for condensation heat transfer", Gold Bulletin, vol. 14, no. 3, pp. 95-101, 1981.
[18] J. Shim, D. Seo, S. Oh, J. Lee, and Y. Nam, "Condensation Heat-Transfer Performance of Thermally Stable Superhydrophobic Cerium-Oxide Surfaces", ACS Applied Materials & Interfaces, vol. 10, no. 37, pp. 31765-31776, 2018.
[19] M. H. Rausch, A. P. Fröba, and A. Leipertz, "Dropwise condensation heat transfer on ion implanted aluminum surfaces", International Journal of Heat and Mass Transfer, vol. 51, no. 5, pp. 1061-1070, 2008.
[20] S. Vemuri and K. J. Kim, "An experimental and theoretical study on the concept of dropwise condensation", International Journal of Heat and Mass Transfer, vol. 49, no. 3, pp. 649-657, 2006.
[21] R. W. Bonner, "Dropwise condensation in vapor chambers", in 2010 26th Annual IEEE Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM, pp. 224-227, 2010.
[22] A. Chatterjee, M. M. Derby, Y. Peles, and M. K. Jensen, "Enhancement of condensation heat transfer with patterned surfaces", International Journal of Heat and Mass Transfer, vol. 71, pp. 675-681, 2014.
[23] M. M. Derby, A. Chatterjee, Y. Peles, and M. K. Jensen, "Flow condensation heat transfer enhancement in a mini-channel with hydrophobic and hydrophilic patterns", International Journal of Heat and Mass Transfer, vol. 68, pp. 151-160, 2014.
[24] B. Peng, X. Ma, Z. Lan, W. Xu, and R. Wen, "Analysis of condensation heat transfer enhancement with dropwise-filmwise hybrid surface: Droplet sizes effect", International Journal of Heat and Mass Transfer, vol. 77, pp. 785-794, 2014.
[25] B. Peng, X. Ma, Z. Lan, W. Xu, and R. Wen, "Experimental investigation on steam condensation heat transfer enhancement with vertically patterned hydrophobic–hydrophilic hybrid surfaces", International Journal of Heat and Mass Transfer, vol. 83, pp. 27-38, 2015.
[26] K. Egab, M. Alwazzan, B. Peng, S. K. Oudah, Z. Guo, X. Dai, and C. Li, "Enhancing filmwise and dropwise condensation using a hybrid wettability contrast mechanism: Circular patterns", International Journal of Heat and Mass Transfer, vol. 154, 2020.
[27] H. S. Khoo and F. G. Tseng, "Spontaneous high-speed transport of subnanoliter water droplet on gradient nanotextured surfaces", Applied Physics Letters, vol. 95, no. 6, 2009.
[28] D. Song and B. Bhushan, "Enhancement of water collection and transport in bioinspired triangular patterns from combined fog and condensation", J Colloid Interface Sci, vol. 557, pp. 528-536, 2019.
[29] H. Bai, L. Wang, J. Ju, R. Sun, Y. Zheng, and L. Jiang, "Efficient water collection on integrative bioinspired surfaces with star-shaped wettability patterns", Advance Material, vol. 26, no. 29, pp. 5025-30, 2014.
[30] 黃鼎鈞, "膜式/滴式混合型表面於冷凝熱傳增益的探討", 成功大學材料科學及工程學系學位論文, pp.1-383, 2016.
[31] K. S. Yang, Y. Y. Huang, Y. H. Liu, S. K. Wu, and C. C. Wang, "Enhanced dehumidification via hybrid hydrophilic/hydrophobic morphology having wedge gradient and drainage channels", Heat and Mass Transfer, vol. 55, no. 11, pp. 3359-3368, 2019.
[32] 王怡婷, "超疏水表面之製備及其學理研究", 交通大學應用化學研究所學位論文, pp.1-96, 2006.
[33] T. Young, "III. An essay on the cohesion of fluids", Philosophical transactions of the royal society of London, no. 95, pp. 65-87, 1805.
[34] R. N. Wenzel, "Resistance of solid surfaces to wetting by water", Industrial & Engineering Chemistry, vol. 28, no. 8, pp. 988-994, 1936.
[35] A. Cassie and S. Baxter, "Wettability of porous surfaces", Transactions of the Faraday society, vol. 40, pp. 546-551, 1944.