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姓名 楊雲忠(Yun-Chung Yang) 查詢紙本館藏 畢業系所 機械工程學系 論文名稱 數值模擬電液動熱傳增益技術
(Numerical Simulation of the Electrohydrodynamic Techniques in Heat Transfer Enhancement)相關論文 檔案 [Endnote RIS 格式]
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摘要(中) 近年來由於電子產業發展的進步，電子元件體積與重量的減少使得單位面積之熱量增加，因此，發展出有效之散熱裝置是目前最重要的目標。本數值研究利用電液動(electrohydrodynamic, EHD)產生的電暈風增強流道中之熱對流能力，以提升熱傳效果。本文藉由數值模擬及與實驗數據作比對，以驗證本文的數值模式，也釐清EHD技術的物理機制與散熱效果。
首先以針式-平板式與線式-網格式兩種幾何外型之電極，針對電壓與電流、流體流速、熱對流係數作驗證，證明模式建立之正確性。接著以線式-平板式EHD電極，在不同之供應電壓(3~6 kV)、放電電極至收集電極之間距(0.00175、0.00275 m)與入口端為圓柱狀(例1)與一般平板狀(例2)之收集電極幾何外型，作數值模擬分析，探討其對熱傳效果之影響。數值模擬顯示最佳熱傳增強效率其熱對流通量，約為無EHD效應的一般流場的1.6倍。數值模擬顯示供應電壓與流體流速、熱對流係數、紐塞數與熱傳增加量成正比。例1的電極安置之散熱效能會較例2的電極安置高約14.2 %，但前者的電極消耗功率高於後者約18 mW。電極間距會與流體流速、熱對流係數、紐塞數與熱傳增加量成反比。依據本文研究，EHD技術確實能對管流的熱傳效果有顯著的改善。
摘要(英) This numerical study utilized the electrohydrodynamics (EHD) techniques to generate the corona wind to enhance the heat convection inside the channe, so that the heat transfer . Numerical simulations results were used to compared with experiments to validate present numerical model, also, to clarify the physical mechanism and heat dissipation induced by EHD techniques.
First, two kind of electrode geometries setup including the needle-to-plate and the wire-to-grid were implemented. By comparing the applied voltage, corona current, flow velocity and heat transfer coefficient with the experimental data to validate the accuracy of the models. Next, the wire-to-plate geometry was simulated and the effects of different applied voltages (3~6 kV), different electrode separations (0.00175 and 0.00275 m) and different collecting electrode geometries on heat transfer were discussed, including cylindrical (case 1) and normal plate (case 2) inlet geometry. The results showed that the best convective flux efficiency could reached to 1.6 times of that of the traditional chanel flow without EHD effect. Numerical results show that the applied voltage is directly proportional to the flow velocity, convective coefficient, Nu (Nusselt no.) and heat transfer enhancement. The electrode separation is inversely proportional to the flow velocity, convective coefficient, Nu (Nusselt number) and heat transfer enhancement. The heat transfer efficiency in case 1 were 14.2 % better than that of case 2, however, the former consumes 18 mW higher than the latter. The space of electrode is inversely proportional to the flow velocity, heat convection coefficeint, Nu and heat transfer enhancement. Base on present study, EHD technology indeed provide a significant cooling effect on the channel flow.
關鍵字(中) ★ 計算流體力學
★ 電暈效應
★ 電液動技術關鍵字(英) ★ Computational fluid dynamics
★ Corona effect
★ Electrohydrodynamics technique論文目次 中文摘要....................................................................................................................................I
英文摘要.................................................................................................................................. II
致謝.........................................................................................................................................III
目錄.........................................................................................................................................IV
圖目錄.....................................................................................................................................VI
表目錄.....................................................................................................................................IX
符號說明.................................................................................................................................. X
第一章 緒論..............................................................................................................................1
1.1 電液動力學之簡介.....................................................................................................1
1.1.1 EHD 原理介紹..................................................................................................2
1.1.2 電暈現象..........................................................................................................3
1.1.3 電極簡介..........................................................................................................5
1.2 文獻回顧.....................................................................................................................6
1.2.1 EHD 電暈現象..................................................................................................6
1.2.2 EHD 應用於散熱模擬......................................................................................7
1.2.3 EHD 應用於散熱實驗......................................................................................7
1.3 研究目的.....................................................................................................................9
1.4 論文架構.....................................................................................................................9
第二章 理論分析....................................................................................................................10
2.1 物理模型...................................................................................................................10
2.1.1 針式-平板電極(needle-to-plate) ....................................................................10
2.1.2 線式-網格式電極(wire-to-grid)..................................................................... 11
2.1.3 線式-平板式電極(wire-to-plate) ...................................................................13
2.2 基本假設...................................................................................................................15
2.3 統御方程式...............................................................................................................15
2.3.1 流場之統御方程式........................................................................................15
2.3.2 電場統御方程式............................................................................................16
2.3.3 溫度場統御方程式........................................................................................17
2.4 邊界條件....................................................................................................................17
2.4.1 針式-平板電極(needle-to-plate) .....................................................................17
2.4.2 線式-網格式電極(wire-to-grid).....................................................................20
2.4.3 線式-平板式電極(wire-to-plate) ...................................................................22
2.5 物理量之計算...........................................................................................................25
2.6 計算方法...................................................................................................................26
第三章 結果與討論................................................................................................................28
3.1 驗證工作...................................................................................................................28
3.1.1 針式-平板式電極(needle-to-plate) ................................................................28
3.1.2 線式-網格式電極(wire-to-grid).....................................................................33
3.3 EHD 參數分析...........................................................................................................52
3.3.1 電壓與電流之關係分析................................................................................52
3.3.2 電壓與流速之關係分析.................................................................................54
3.3.3 電壓與熱對流係數之關係分析.....................................................................58
3.3.4 電壓與紐塞數之關係分析............................................................................60
3.3.5 電壓與熱傳量之關係分析............................................................................62
3.3.6 電壓與熱傳效率之關係分析........................................................................63
第四章 結論與建議................................................................................................................67
4.1 結論...........................................................................................................................67
4.2 未來改進方向...........................................................................................................68
參考文獻.................................................................................................................................69
參考文獻 黃政德，「以EHD技術增加LED散熱效率之研究」，國立清華大學，碩士論文，民國94年。
Bondar H., Bastein F. (1986), “Effect of neutral fluid velocity on direct conversion from electrical to fluid kinetic energy in an electro-fluid-dynamics device,” J. Phys. D. Appl. Phys. 19, 1657-1663.
Bhattacharyya S., Peterson A. (2002), “Corona wind-augmented convection-part1 Single electrode studies”, J. Enhanced Heat Transfer 9, 209-212.
Benamar B., Favre E., Donnot A., Rigo M.O. (2007), “Finite element solution for ionized fields in DC electrostatic precipitator,” Proceedings of the COMSOL Users Conference.
Cooperman P. (1960), “A theory for space charge limited currents with application to electrical precipitation,” AIEE Trans. 79, 47-50.
Chang J. S., Ueno J., Tsubone H., Harvel G. D., Minami S., Urashima K. (2007), “Electrohydrodynamically induced flow direction in a wire-non-parallel plate electrode corona discharge,” J. Physics Dynamic 40, 5109-5110.
Darabi J., Ekula K. (2003), “Development of a chip-integrated micro cooling device,” J. Microelectronics 34, 1067-1074.
Grassi W., Testi D., Saputelli M. (2005), “Heat transfer enhancement in a vertical annulus by electrophoretic forces acting on a dielectric liquid,” Inter. J. Thermal Sciences 42, 1072-1077.
Hauksbee F. (1719), Physico-Mechnical Experiments on Various Subjects, 1st ed., London, 46-47.
Hsu C. P., Jewell-Larsen N. E., Krichtafovitch I. A., Montgomery S. W., Dibene J. T., Mamishev A. V. (2007), “Miniaturization of electrostatic fluid accelerators,” J. Microelectromechanical Systems 16(4), 809-815.
Jewell-Larsen N. E., Tran E., Krichtafovitch I. A., Mamishev A. V., “Design and optimization of electrostatic fluid accelerators,” IEEE Transactions on Dielectrics and Electrical Insulation 13(1), 191-203, 2006.
Jewell-Larsen N. E., Hsu C. P., Krichtafovitch I. A., Montgomery S. W., Dibene J. T., Mamishev A. V. (2008a), “CFD analysis of electrostatic fluid accelerators for forced convection cooling,” IEEE Trans. on Dielectrics and Electrical Insulation 15(6).
Jewell-Larsen N. E., Karpov S. V., Krichtafovitch I. A., Jayanty V., Hsu C. P., Alexander M. V. (2008b), “Modeling of corona-induced electrohydrodynamic flow with COMSOL,” Proc. ESA Annual Meeting on Electrostatics.
Kasayapanand N. T., Kiatsiriroat T. (2005), “EHD enhanced heat transfer in wavy channel,” Inter. Communications in Heat and Mass Transfer 32, 809-821.
Lin C. W., Jang J. Y. (2005), “3D numerical micro-cooling analysis for an EHD micro-pump,” Sensors and Actuators A. 122, 167–176.
Li H. Y., Huang R. T., Sheu W. J., Wang C. C. (2007), “EHD Enhanced Heat Transfer with Needle-Arrayed Electrodes,” 23rd IEEE SEMI-THERM Symposium, 149-154.
Moreau E., Touchard G. (2007), “Enhancing the mechanical efficiency of electric wind in corona discharges,” J. Electrostatics 66, 39-44.
Nelson D. A., Shaughnessy E. J. (1986), “Electric field effects on natural convection in enclosures,” J. Heat Transfer 108, 749-754.
Ogata J., Iwafuji Y., Shimada Y., Yamazaki T. (1992), “Boiling heat transfer enhancement in tube-bundle evaporators utilizing electric field effects,” ASHRAE Transactions. 98(2), 435-444.
Peek F. W. (1929), Dielectric Phenomena in High Voltage Engineering, McGraw-Hill.
Rickard M., Dunn-Rankin D. (2007), “Numerical simulation of a tubular ion-driven wind generator,” J. Electrostatics 65, 646–654.
Steutzer O. M. (1959), “Ion drag pressure generation,” J. Appl. Phys. 30, 984-994.
Tsubone H., Ueno J., Komeili B., Minami S., Harvel G. D., Urashima K., Ching C.Y., Chang J. S. (2008), “Flow characteristics of dc wire-non-parallel plate electrohydrodynamic gas pumps,” J. Electrostatics 66, 115–121.
Yabe A. (1991), “Active heat transfer enhancement by applying electric fields,” ASME/JSME Thermal Engineering Proceedings 3, XV-XXIII ASME.
Yan Y. Y., Zhang H. B., Hull J. B. (2004), “Numerical modeling of electrohydrodynamic (EHD) effect on natural convection in an enclosure,” Numerical Heat Transfer 46, 453–471.
Zhao L., Adamiak K. (2005), “EHD flow in air produced by electric corona discharge in pin–plate configuration,” J. Electrostatics 63, 337–350.
New cooling method for CPU, http://pathways.cu.edu.eg/news/news/uf/15328_New_cooling_method_for_CPU.doc, accessed 14 Feb, 2009.
指導教授 吳俊諆(Jiunn-chi Wu) 審核日期 2009-7-9 推文 plurk
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