本研究擬探討改變不同的二氧化碳雪花形成腔體對雪花粒徑的控制與其之機制，並且將其應用於清洗方面等研究。使用不同雪花形成腔體內部檔體的設計，探討其對雪花粒徑、雪花轉換率與雪花形成機制的影響，此外，外接加速氣體使二氧化碳雪花噴流加速並清洗基板。初級雪花由Malvern粒子分析儀進行量測，而流場以高速攝影機拍攝，以觀察流場與噴霧品質。由(Lin，2014)研究發現雪花形成腔體達到啟動長度，便能夠團聚大型雪花，並提出二氧化碳雪花團聚模型，說明雪花形成腔體內部的回流團聚機制。由研究結果顯示，檔體設計對二氧化碳雪花形成腔體出口的雪花粒徑有顯著的影響。適當的選擇檔體位置、大小及數量，可形成壁面檔體堆疊的壁面團聚機制，可有效的倍增團聚雪花粒徑至400微米。本研究亦提出一二氧化碳雪花團聚模型嘗試說明壁面團聚之機制，其中檔體位置在下游3L/4處時，對回流團聚機制干擾最小，可與壁面團聚機制產生最大加乘效應，隨著檔體往上游設置，其加乘效益遞減，且檔體的面積越大，檔體的數量越多，都能夠使雪花粒徑提高。不同檔體面積與檔體數量配對出不同檔體總面積並轉換成檔體遮蔽率可以將其視為連續噴流與非連續噴流的指標，結果也顯示檔體遮蔽率越高，雪花粒徑越大。在雪花形成腔體內部加入檔體裝置，能夠提高雪花轉換率，在相同的二氧化碳消耗量之下，產出粒徑更大的雪花。清洗實驗結果顯示，雪花粒徑越大，動能越大更容易突破粉塵與基板之邊界層效應，故清洗效果也會越好，當雪花粒徑變為原來的2倍，可以清除3倍的粉塵量，使用加速氣體噴流加速二氧化碳雪花噴流增加動能轉換，提高加速氣體壓力4倍，清除4倍的粉塵量。研究結果也顯示，提高加速氣體壓力，可以有效提高清洗效率，並縮短將基板清洗乾淨的時間，將壓力提高4倍的條件下，可以使清洗速度提高10倍。本實驗亦嘗試以二氧化碳雪花噴流外接加速氣體噴流清理市面販售手機背殼面板之加工半成品，結果顯示藉由動量轉換可以有效清除金屬圓孔與塑膠孔之毛邊，說明二氧化碳雪花噴流其應用價值可望取代人工清理之製程。

In recent years, carbon dioxide (CO2) snow jets are widely used in medical and industrial applications, such as particle removal, surface cleaning, pharmaceutical granulation, cryogenic therapy and food processing. In semiconductor fabrication, CO2 snow cleaning has unique organic and particle removal abilities. Besides being better than traditional surface cleaning methods, it is also eco-friendly. A model for the agglomeration of CO2 snow particle was derived by our research team in 2014, and it provided clear evidence of the agglomeration of CO2 snow inside a CO2 formation chamber that has never been published in previous literature. Prolonging the research of agglomeration mechanism of primary snow, the aim of this research is about controlling the size of the snow particle. This includes the onset length of agglomeration of the snow particle and a newly designed formation chamber. This paper experimentally investigates into improving the particle agglomeration upon the wall of the chamber. With the additive manufacturing method by 3D printer, a complicated design with converging-diverging configurations and curved surfaces can easily be realized. Results show that a complicated particle motion in the upper portion of the chamber is responsible for the formation of a larger snow particle, and the blockages are added in the formation chamber can occur a second agglomeration mechanism. It may improve the particle agglomeration upon the wall in the downstream field according to the setting position, area, and number of the blockage. In this research, the snow particle size can be increased by 200%, and a maximum snow conversion ratio of 18% has been achieved in this paper.

[1] Al-Hakim et al. K. Al-Hakim, G. Wigley, A.G.F. Stapley, Phase doppler anemometry studies of spray freezing. Chemical Engineering Research and Design, 84 (2006), pp. 1142–1151

[2] HOENIG, Stuart A. Cleaning surfaces with dry ice. Compressed Air Magazine, 1986, 91.8 22-25.

[3] SHERMAN, Robert. Carbon dioxide snow cleaning. Particulate Science and Technology, 2007, 25.1: 37-57.

[4] YANG, Sheng-Chung; HUANG, Keng-Shiang; LIN, Yu-Cheng. Optimization of a pulsed carbon dioxide snow jet for cleaning CMOS image sensors by using the Taguchi method. Sensors and Actuators A: Physical, 2007, 139.1: 265-271.

[5] HU, Chih-Yuan. 二氧化碳雪花對生物體之冷凍機制及其在內視鏡冷凍治療術之應用. 成功大學航空太空工程學系學位論文, 2012, 1-111.

[6] Lien, Chun-Han, Designing formation chamber of Carbon Dioxide Snow for Endoscopic Cryotherapy Application

[7] HOENIG, S. A. ‘Dry Ice Snow as a Cleaning Media for Hybrids and Integrated Circuits. Hybrid Circuit Technology, 1990, 7: 34.

[8] SHERMAN, Robert; GROB, John; WHITLOCK, Walter. Dry surface cleaning using CO2 snow. Journal of Vacuum Science & Technology B, 1991, 9.4: 1970-1977.

[9] HILL, E. 1994. Prec. Clean., February, p. 36.

[10] HILLS, M. M. Carbon dioxide jet spray cleaning of molecular contaminants. Journal of Vacuum Science & Technology A, 1995, 13.1: 30-34.

[11] BANERJEE, Souvik; CAMPBELL, Andrea. Principles and mechanisms of sub-micrometer particle removal by CO2 cryogenic technique. Journal of Adhesion Science and Technology, 2005, 19.9: 739-751.

[12] THEERACHAISUPAKIJ, W., et al. Reentrainment of deposited particles by drag and aerosol collision. Journal of Aerosol Science, 2003, 34.3: 261-274.

[13] YellowBook, 2005 CPR, ‘Yellow Book’ methods for the calculation of physical effects – Due to releases of hazardous materials (liquids and gases), Committee for the Prevention of Disasters (CPR)

[14] ELKOTB, M. M. Fuel atomization for spray modelling. Progress in Energy and Combustion Science, 1982, 8.1: 61-91.

[15] BOOK, TNO Yellow. Methods for the calculation of physical effects due to releases of hazardous materials (liquids and gases). Committee for the Prevention of Disasters, CRP E, 1997, 14: 870.

[16] KOLEV, N. I. Fragmentation and coalescence dynamics in multiphase flows. Experimental Thermal and Fluid Science, 1993, 6.3: 211-251.

[17] RAZZAGHI, Minoo. Droplet size estimation of two-phase flashing jets. Nuclear Engineering and Design, 1989, 114.1: 115-124.

[18] PILCH, M.; ERDMAN, C. A. Use of breakup time data and velocity history data to predict the maximum size of stable fragments for acceleration-induced breakup of a liquid drop. International journal of multiphase flow, 1987, 13.6: 741-757.

[19] SHUSSER, M.; WEIHS, D. Explosive boiling of a liquid droplet. International journal of multiphase flow, 1999, 25.8: 1561-1573.

[20] ZENG, Yangbing; CHIA-FON, F. Lee. Modeling droplet breakup processes under micro-explosion conditions. Proceedings of the Combustion Institute, 2007, 31.2: 2185-2193.

[21] FAETH, G. M.; HSIANG, L.-P.; WU, P.-K. Structure and breakup properties of sprays. International Journal of Multiphase Flow, 1995, 21: 99-127.

[22] KAY, Peter J.; BOWEN, Phillip J.; WITLOX, Henk WM. Sub-cooled and flashing liquid jets and droplet dispersion II. Scaled experiments and derivation of droplet size correlations. Journal of Loss Prevention in the Process Industries, 2010, 23.6: 849-856.

[23] HERVIEU, E.; VENEAU, T. Experimental determination of the droplet size and velocity distributions at the exit of the bottom discharge pipe of a liquefied propane storage tank during a sudden blowdown. Journal of Loss Prevention in the Process Industries, 1996, 9.6: 413-425.

[24] WITLOX, Henk, et al. Flashing liquid jets and two-phase droplet dispersion: II. Comparison and validation of droplet size and rainout formulations. Journal of hazardous materials, 2007, 142.3: 797-809.

[25] 陳軍佑,”Influence of Secondary Atomization on CO2 Snow Jet Flow Field,” 中華民國航空太空學會/中華民用航空學會聯合學術研討會,2009.

[26] LIU, Yi-Hung, et al. Size measurement of dry ice particles produced from liquid carbon dioxide. Journal of Aerosol Science, 2012, 48: 1-9.

[27] LIN, Tien-Chu; SHEN, Yi-Jun; WANG, Muh-Rong. Agglomeration Processes and Mechanisms of CO2 Snow Inside a Tube. Aerosol Science and Technology, 2014, 48.2: 228-237.

[28] Lourenco, L. M., Krothapalli, A., and Smith, C. A, “Particle Image Velocimetry,” Advances in Fluid Mechanics Measurements, Lecture Notes in Engineering-45, Springer-Verlag, pp. 127-200 , 1989.

[29] Lourenco, L. M., Krothapalli, A., Buchlin, J. M., and Riethmuller, M.L, “A Non-Invasive Experimental Technique for the Measurement of Unsteady Velocity and Vorticity Fields,” AIAA Jornal, 24, pp. 1715-1717, 1986.
[30] Lourenco, L. M., and Krothapalli A, “Stereoscopic and Time Resolved PIV Measurements in High-Speed Flows,” AIAA, 2180-2194, 2004.

[31] Raffel, M., Willert, C. E., Kompenhans, J “Particle Image Velocimetry–A Practical Guide,” Springer, ISBN 3-540-63683-8, 1998.

[32] Willert, C., Raffel, M., Kompenhans, J., Stasicki, B., and La’’hler, C “Recent Applications of Particle Image Velocimetry in Aerodynamic Research”, Flow Meas. Instrum., 7(3/4). pp. 247-256, 1996.

[33] Newbery, A. P., Rayment, T., and Grant, P. S, “A Particle Image Velocimetry Investigation of In-Flight and Deposition Behavior of Steel Droplets During Electric Arc Sprayforming,” Materials Science and Engineering A, 383, pp. 137-145, 2004.

[34] Adrian, R. J, “Twenty Years of Particle Image Velocimetry,” Experiments in Fluids, 39, pp. 159-169, 2005.

[35] Menon, M., and Lai, W. T., “Key Considerations in the Selection of Seed Particles for LDV measurements,” Laser Anemometry Advances and Applications, ASME, pp. 719-730, 1991.

[36]Menon, M., and Lai, W. T., “Key Considerations in the Selection of Seed Particles for LDV measurements,” Laser Anemometry Advances and Applications, ASME, pp. 719-730, 1991. 127-132, 1994.

[37] Nishigaki, M., Ippommatsu, M., Ikeda, Y., and Nakajima, T., “New High-Performance Tracer Particle for Optical Gas Flow Diagnostics,” Meas. Sci. Technol., 3, pp. 619-621, 1992.

[38] Lee, K. H., Lee, C. H., and Lee, C. S, “An Experimental Study on the Spray Behavior and Fuel Distribution of GDI Injectors Using the Entropy Analysis and PIV Method,” Fuel, 83, pp. 971-980, 2004.

[39] Richter, B., Rottenkolber, G., Hehle, M., Dullenkopf, K., and Wittig,S., “Investigation of Fuel Sprays by Means of Stereoscopic Particle Image Velocimetry and Highspeed Visualization,” ILASS-Europe 2001, Zurich, 2-6 September, 2001