臺灣博碩士論文加值系統

本文是使用數值方法來分析蒸汽腔體內於穩態時其溫度場及流場之狀況。利用計算流體力學軟體FLUENT 6.2來模擬分析。模擬的蒸汽腔體根據Koito等人(2006) 所給定外形大小做三維數值模擬分析，工作流體為水及飽和水蒸汽，分析在不同的冷卻氣溫、加熱量及加熱面積下其溫度分佈和流場變化並和Koito等人(2006)的實驗做比較。
由數值結果可以看出在散熱面的溫度分佈均勻，從剖面圖亦可看到毛細結構靠近熱源的地方溫度梯度最大，而液流壓降遠大於蒸汽壓降和重力壓降，而要使工作流體能回流而不會空燒，毛細壓降要能大於液流壓降；跟Koito等人(2006)的實驗比較，結果相當一致，但當輸入熱量較大其溫度誤差也稍變大。在不同的冷卻氣溫、加熱量下，蒸汽腔體的熱阻變化不大；當冷卻氣溫越高及輸入熱量越大，蒸汽區內的工作流體密度變大其流速變慢；毛細結構的液流壓降在不同的冷卻氣溫下都一樣，但在輸入熱量越大其液流壓降越大；當熱源面積變小則熱阻變大，而毛細結構的溫度梯度也變大，故蒸汽區內流速也變大，而其液流壓降也較大。

This study used numerical method to analyze the thermal and fluid phenomena in a vapor chamber and the CFD software FLUENT 6.2 was used to do the simulation. The shape of vapor chamber was the same as in Koito et al. study (2006). The working fluid was water and the results of the analysis on the thermal and fluid phenomena were compared with the experiment results of Koito et al. (2006) for different cooling air temperatures, heat fluxes, and heat source sizes.
The numerical results showed that temperature of the cooling surface was uniform; from the cross-sectional view, the liquid –wick region near heat source had the largest temperature gradient and liquid flow had the maximum pressure drop in the vapor chamber. The capillary pressure head necessary to circulate the working fluid inside the vapor chamber must be larger than the pressure drop of liquid in the liquid-wick region. The average cooling surface temperature and the maximum temperature on bottom surface was close to the experimental result of Koito et al. (2006), but the larger the heat flux, the more the difference. Thermal resistance remained the same for different cooling air temperatures and heat fluxes. With higher cooling air temperature and heat flux, the velocity magnitude in vapor region was lower. In liquid-wick region, the liquid pressure drop was the same for different cooling air temperatures and was larger for higher heat flux. When the heat source size was smaller, the thermal resistance was found to be higher and the temperature gradient was larger. The pressure drop of liquid in liquid-wick region and velocity magnitude in vapor region was also higher.

中文摘要 I
ABSTRACT II
誌 謝 III
目 錄 IV
圖目錄 VII
表目錄 IX
符號說明 X
第一章 緒論 1
1.1 引言 1
1.2 蒸汽腔體的優點和操作極限 2
1.3 文獻回顧 5
1.4 研究目的 8
第二章 數學及物理模型 11
2.1 蒸汽腔體的實際運作 11
2.2 基本假設和統御方程式 12
2.2.1 基本假設 12
2.2.2 統御方程式 12
2.3 邊界條件 14
2.4 蒸汽腔體其熱阻的（ ）定義 17
2.5 多孔性介質的性質及經驗公式 17
第三章 數值方法 23
3.1概述 23
3.2 格點位置的配置 24
3.3 離散法則 26
3.4 差分方程式 28
3.5 SIMPLE 法 30
3.6 收斂條件 35
3.7 差分方程式的解法 36
3.7.1數值程序 38
第四章 結果與討論 43
4.1 格點獨立測試 43
4.2 蒸汽腔體流場和熱場分析 44
4.2.1 數值與實驗結果比較 46
4.2.3 不同冷卻氣溫下熱場及流場的變化 50
4.2.4 不同熱通量下熱場及流場的變化 51
4.2.5 不同熱源面積下熱場及流場的變化 53
4.2.6 與相同形狀的銅板其熱場比較 54
第五章 結論與建議 80
5.1結論 80
5.2未來研究方向與建議 81
參考文獻 83
作者簡介 86

1.M. Mochizuki, Th. Nguyen, K. Mashiko, Y. Saito, Ti. Nguyen, V. Wuttijumnong, X. Wu, “Practical application of Heat Pipe and Vapor Chamber for Cooling High Performance Personal Computer” , in Proceedings of the 13th International Heat Pipe Conference, 2004, pp. 448–454.

2.R.S. Gaugler, “Heat Transfer Device”, U.S. Patent 2,350,348, 1944.

3.G.M. Grover, “Evaporation-Condensation Heat Transfer Device”, U.S. Patent 3,229,759, 1964.

4.G. Grover , T.P. Cotter , and G.F. Erickson. “ Structure of Very High Thermal Conductance” ,Journal of Applied Physics Vol.35, p1990, Feb 1964.

5.W.S. Chang and G.T. Colwell, “ Mathematical Modeling of the Transient Operating Characteristics of a Low-temperature Heat Pipe”, Numerical Heat Transfer, Vol.8, pp.169-186, 1985.

6.M.N. Chen and A. Faghri, “An Analysis of the Vapor Flow and the Heat Conduction Through the Liquid-Wick and Pipe Wall in a Heat Pipe with Single or Multiple Heat Sources”, Int. J. Heat and Mass Transfer, Vol. 33, No. 9, 1990, pp. 1945-1955.

7.J.M. Tournier and M.S. El-Genk, “A Heat Pipe Transient Analysis Model” , Int. J. Heat Mass Transfer”, Vol. 37, pp. 753-762, 1994.

8.Z.J. Zuo and A. Faghri, “Boundary Element Approach to Transient Heat Pipe Analysis”, Numerical Heat Transfer, PartA, pp205-220, 1997.

9.Z.J. Zuo and A. Faghri , “A Network Thermodynamic Analysis of the Heat Pipe”, Int. J. Heat Mass Transfer, Vol. 41, pp. 1473-1484, 1998.

10.黃柏超，“多孔性介質對三維熱管熱傳效能之數值模擬研究分析”，碩士論文，國立成功大學航空太空學系，2004。

11.N. Zhu and K. Vafai, “Vapor and Liquid Flow in an Asymmetrical Flat Plate Heat Pipe : a Three-dimensional Analytical and Numerical Investigation”. Int. J. Heat Mass Transfer, Vol. 41, pp. 159-174, 1998.

12.U. Vadakkan, S.V. Garimella, and J.Y. Murhty, “Transport in Flat Heat Pipes at High Heat Fluxes from Multiple Discrete Sources”, ASME Journal of Heat Transfer 126 (2004) 347-354.

13.Y. Koito, H. Imura, M. Mochizuki, Y. Saito, and S. Torii, “Numerical Analysis and Experimental Verification on Thermal Fluid Phenomena in a Vapor Chamber”, Applied Thermal Engineering, Vol. 26, pp. 1669-1676, 2006.

14.G. Carbajal, C. B. Sobhan, G. P. Peterson ,D. T. Queheillalt, Haydn N. G. Wadley, “A Quasi-3D Analysis Of the Thermal Performance of a Flat Heat Pipe“, Int. J. Heat and Mass Transfer, Vol.50, No.21-22, 4286-4296, 2007.

15.陳彥旭，“平板式熱管之散熱評估模式建立以及擴散熱阻分析”，博士論文，國立清華大學工程與系統科學系，2007。

16.柯文旺，“多孔性介質中自然對流與強制對流熱質傳現象之研究”，博士論文，國立交通大學機械工程學系，1999。

17.依日光，熱管技術理論實務(HEAT PIPE TECHNOLOGY)。

18.Japan Association for Heat Pipes (JAHP), Jitsuyou Heat Pipe, second ed. (in Japanese), 2001, Nikkan Kogyo Shimbun, Ltd., Tokyo.

19.http://www.qats.com/qpedia/0907_Vapor_Chambers.pdf

20.S.V. Patankar, “Numerical Heat Transfer and Fluid Flow”, Hemisphere Publishing, 1980.

21.S.V. Patankar and D.B. Spalding, “A Calculation Procedure for Heat, Mass and Momentum Transfer in Three-dimensional Parabolic Flows”, Int. J. Heat Mass Transfer, Vol. 15, pp. 1787, 1972.

22.FLUENT 6.2 User’s Guide . Fluent Inc.,2005