本研究探討不同接觸角的表面對冷凝熱傳增益之影響，透過理論分析及實驗比對證實，在滴式冷凝中靜態接觸角越大熱通量越小，並結合親疏水混合表面的設計，提升冷凝熱傳效果。在現今著重於能源利用效率的發展環境下，本研究之結果極具價值，可應用於熱交換器等冷凝熱傳系統中。
疏水表面熱通量的理論分析結果發現，當靜態接觸角越大時，雖然可減少冷凝熱傳表面上的冷凝液滴最大半徑，卻也大幅提升液滴的熱阻，因而使熱通量驟降；本研究亦考量遲滯角對冷凝液滴最大半徑的影響，提出透過力學分析估算冷凝液滴最大半徑之公式。親疏水混合表面熱通量的理論分析則提供了設計上所需之參數參考結果，使搭配的親水寬度和疏水寬度能有最佳的冷凝熱傳效果；本研究亦修正理論中親水表面上冷凝膜厚的公式，使結果更加符合實驗現象。
疏水表面實驗方面，透過表面改質的網印技術，可有效的控制冷凝熱傳表面上的靜態接觸角，本研究設計4組不同靜態接觸角的表面，分別為80°、90°、100°及110°。實驗結果顯示，靜態接觸角為80°和90°的表面在冷凝熱傳過程中不屬於滴式冷凝，因此實驗結果與理論相距甚大，而靜態接觸角為100°和110°的表面在冷凝熱傳過程中屬於滴式冷凝，因此實驗結果與理論相符，且靜態接觸角為100°的冷凝熱傳效果又比110°好，呈現了靜態接觸角越大，熱通量越小的現象。
親疏水混合表面實驗方面，共設計15組不同親水寬度和疏水寬度的搭配，結果以親水表面寬度為200μm，搭配疏水表面寬度為300μm時有最佳的增益比例，與疏水表面相較之下可增加約一成的熱通量。實驗中部份結果與理論值不相符，本研究針對此現象提出無因次化冷凝膜厚的分析，並發現無因次化冷凝膜厚小於0.5時的親疏水寬度設計，實驗結果與理論值吻合，而無因次化冷凝膜厚大於0.5時的親疏水寬度設計，實驗中會出現液滴阻塞於表面的現象，因此實驗值與理論值將不相符。

This study investigates the effect of surface condensation heat transfer (CHT) gain with different contact angles, and confirms through theoretical analysis and experimental comparison that the larger the static contact angle in dropwise condensation is, the smaller the heat flux is. This study also combines the design of the hydrophilic-hydrophobic hybrid surface to enhance the CHT effect. Surface modification technology based on screen printing technique is used to fabricate CHT surfaces, including hydrophobic surfaces with 4 different static contact angles and hydrophilic-hydrophobic hybrid surfaces with 15 sets of different hydrophilic widths and hydrophobic widths of the matching. In terms of hydrophobic surface experiments, the results show that the surface with a static contact angle of 100° has best CHT effect. In terms of hydrophilic-hydrophobic hybrid surface experiments, the results show that the hydrophilic surface width of 200 μm with the hydrophobic surface width of 300 μm has the best gain ratio, compared with the hydrophobic surface can increase the heat flux by about 10%. In today's development environment focusing on energy efficiency, the results of this study are valuable and can be applied to CHT systems such as heat exchangers.

[1] E. J. Le Fevre and J. W. Rose, "A theory of heat transfer by dropwise condensation", International Heat Transfer Conference Digital Library, Begel House Inc., 1966.
[2] I. Tanasawa and J. Ochiai, "Experimental study on dropwise condensation", Bulletin of Japan Society of Mechanical Engineers 16.98 (1973): 1184-1197.
[3] J. W. Rose and L. R. Glicksman, "Dropwise condensation-the distribution of drop sizes", International Journal of Heat and Mass Transfer 16.2 (1973): 411-425.
[4] W. H. Wu and J. R. Maa, "On the heat transfer in dropwise condensation." Chemical Engineering Journal 12.3 (1976): 225-231.
[5] J. W. Rose, "Dropwise condensation theory and experiment: a review", Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 216.2 (2002): 115-128.
[6] B. S. Sikarwar, S. Khandekar and K. Muralidhar "Dropwise condensation underneath chemically textured surfaces: simulation and experiments", Journal of Heat Transfer 133.2 (2011): 021501.
[7] J. W. Westwater, "Gold surfaces for condensation heat transfer", Gold Bulletin 14.3 (1981): 95-101.
[8] S. Vemuri, K. J. Kim, B. D. Wood, S. Govindaraju and T. W. Bell, "Long term testing for dropwise condensation using self-assembled monolayer coatings of n-octadecyl mercaptan", Applied Thermal Engineering 26.4 (2006): 421-429.
[9] S. Vemuri and K. J. Kim, "An experimental and theoretical study on the concept of dropwise condensation," International Journal of Heat and Mass Transfer 49.3-4 (2006): 649-657.
[10] R. W. Bonner, "Dropwise condensation in vapor chambers", 2010 26th Annual IEEE Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM). IEEE, 2010.
[11] 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 (2016): 1-383.
[12] J. Zhang, L. Xue and Y. Han, "Fabrication gradient surfaces by changing polystyrene microsphere topography", Langmuir 21.1 (2005): 5-8.
[13] H. S. Khoo and F. G. Tseng, "Spontaneous high-speed transport of subnanoliter water droplet on gradient nanotextured surfaces", Applied Physics Letters 95.6 (2009): 063108.
[14] 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 71 (2014): 675-681.
[15] 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 68 (2014): 151-160.
[16] H. W. Hu, G. H. Tang and D. Niu, "Experimental investigation of condensation heat transfer on hybrid wettability finned tube with large amount of noncondensable gas", International Journal of Heat and Mass Transfer 85 (2015): 513-523.
[17] 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 77 (2014): 785-794.
[18] 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 83 (2015): 27-38.
[19] T. Young, "An essay on the cohesion of fluids", Philosophical Transactions of the Royal Society of London 95 (1805): 65-87.
[20] R. N. Wenzel, "Resistance of solid surfaces to wetting by water", Industrial & Engineering Chemistry 28.8 (1936): 988-994.
[21] A. B. D. Cassie and S. Baxter, "Wettability of porous surfaces", Transactions of the Faraday Society 40 (1944): 546-551.
[22] J. Lee, B. He and N. A. Patankar, "A roughness-based wettability switching membrane device for hydrophobic surfaces", Journal of Micromechanics and Microengineering 15.3 (2005): 591.
[23] W. C. Nelson, P. Sen and C. J. C. J. Kim, "Dynamic contact angles and hysteresis under electrowetting-on-dielectric", Langmuir 27.16 (2011): 10319-10326.
[24] J. H. Kim, H. P. Kavehpour and J. P. Rothstein, "Dynamic contact angle measurements on superhydrophobic surfaces", Physics of Fluids 27.3 (2015): 032107.
[25] X. Wang, L. Wang and R. Yu, "Dynamic Contact Angle on a Surface with Gradient in Wettability ", International Refrigeration and Air Conditioning Conference (2016)
[26] X. D. Wang, X. F. Peng and B. X. Wang, "動態濕潤與動態接觸角的實驗", 航空動力學報 20.2 (2005): 214-218.
[27] X. D. Wang, X. F. Peng and B. X. Wang, "動態濕潤與動態接觸角研究進展", 應用基礎與工程科學學報 11.4 (2003): 396-404.
[28] W. M. Rohsenow, "Heat transfer and temperature distribution in laminar film condensation", Transactions of the American Society of Mechanical Engineers 78 (1956): 1645-1648.
[29] C. Graham and P. Griffith, "Drop size distributions and heat transfer in dropwise condensation", International Journal of Heat and Mass Transfer 16.2 (1973): 337-346.
[30] J. W. Rose, "Further aspects of dropwise condensation theory", International Journal of Heat and Mass Transfer 19.12 (1976): 1363-1370.
[31] C. W. Extrand and Y. Kumagai, "Liquid drops on an inclined plane: the relation between contact angles, drop shape, and retentive force", Journal of Colloid and Interface Science 170.2 (1995): 515-521.