臺灣博碩士論文加值系統

中文摘要
本文目的是針對二維封閉矩形空間中，研究不同流體受不同長寬比之幾何形狀、不同擺放角度及不同莱利數Ra影響下之自然對流熱傳現象。本文以數值模擬方法來分析矩形空間中之二維穩態流場現象，並與實驗結果做一比較。數值分析所使用之理論模型為左、右壁分別為高溫壁及低溫壁，其餘之壁面皆設為絕熱壁，且理論模型中，分別將空氣、純水、混合流體(水及乙二醇)作為工作流體，來探討受到長寬比、傾斜角度及萊利數Ra等效應影響時溫度場及流場變化及自然對流熱傳Nu值變化。數值模擬所考慮之參數範圍為：萊利數Ra=103~106；普朗特數Pr=0.71, 5.83, 62.1(分別為空氣、純水、混合流體)；長寬比Ar=2, 4, 8；傾斜角度0°~360°。實驗量測方面則考慮有限溫差下，改變旋轉角度(0°, 10°)和不同的長寬比(Ar=2, 4)，以及不同流體(純水、混合流體)時之自然對流現象，並以雷射觀察流體之流場分佈。由研究結果顯示，不同流體之平均紐賽數均隨著萊利數的增加而上升；而在相同萊利數的情況下，隨著長寬比的增加平均紐賽數降低。

Abstract
The problem of two-dimensional steady state natural convection heat transfer in a rectangular enclosure filled with different fluids, different aspect ratio, inclined alignment and Rayleigh number has been investigated numerically and experimentally. Use fortran set up to two-dimensional flow field analyse. It’s about putting the air, water, mixture fluids(water/EG) in a rectangular enclosure container which has two sides. One of it is cooling surface, another is heating surface, and others are adiabatic surfaces. In the numerical formulation, the effects of variable heat transfer of the fluids associated with temperature and gravity. he numerical simulations have been undertaken for the pertinent dimensionless parameters in the following ranges: the Rayleigh number Ra=103~106; the Prandtl number, Pr=0.71, 5.83, 62.1, It is air, water, mixture fluids(water/EG); aspect ratio, Ar=2, 4, 8; degree(0°~360°); experimental consideration limited temperature difference along with angle of tilt (0° and 10°) and different aspect ratio (Ar=2, 4) of natural convection phenomenon to water, mixture fluids. The experimental result is by laser watching stream function. In result, the average Nusselt number increases with improve the Rayleigh number of different fluids. And on the same Rayleigh number, the average Nusselt number decreases with extend the aspect ratio.

目錄
中文摘要…………………………………………………………i
Abstract…………………………………………………………ii
誌謝………………………………………………………………iii
目錄………………………………………………………………iv
表目錄……………………………………………………………vii
圖目錄……………………………………………………………ix
符號說明…………………………………………………………xviii
第一章 緒論………………………………………………1
1-1 研究背景與動機……………………………………1
1-2 文獻回顧……………………………………………3
1-3 研究目的……………………………………………6
1-4 研究流程……………………………………………7
第二章 數值分析……………………………………………8
2-1 物理模型與基本假設………………………………8
2-2 統御方程式…………………………………………9
2-3 數值方法與解題方式………………………………13
2-3-1 數值方法………………………………………13
2-3-2 解題方式………………………………………15
2-4 網格測試……………………………………………17
第三章 實驗量測……………………………………………19
3-1 實驗模型……………………………………………19
3-2 實驗模型主要結構…………………………………20
3-2-1 本體部分………………………………………20
3-2-2 等溫加熱壁……………………………………20
3-2-3 等溫冷卻壁……………………………………21
3-2-4 熱電耦分佈以及溫度量測……………………21
3-3 實驗設備……………………………………………23
3-3-1 直流電供應器…………………………………24
3-3-2 微電腦恆溫循環水槽…………………………25
3-3-3 溫度擷取系統…………………………………26
3-3-4 雷射……………………………………………27
3-3-5 影像擷取系統…………………………………27
3-3-6 熱電耦線校正儀………………………………27
3-3-7 熱傳導係數量測儀……………………………29
3-4 實驗方法與步驟……………………………………31
3-4-1 實驗流體製備…………………………………31
3-4-2 混合流體熱傳導係數實驗……………………31
3-4-3 實驗操作步驟…………………………………32
3-5 實驗數據換算………………………………………33
3-6 實驗不確定度評估…………………………………35
第四章 結果與討論…………………………………………37
4-1 數值模擬結果討論…………………………………37
4-1-1 文獻比較………………………………………37
4-1-2 空氣流體之數值模擬結果討論………………44
4-1-3 純水流體之數值模擬結果討論………………45
4-1-4 混合流體之數值模擬結果討論………………46
4-1-5 不同初始條件之數值模擬結果討論…………48
4-2 實驗量測結果討論…………………………………51
4-2-1 純水流體之結果討論…………………………51
4-2-2 混合流體之結果討論…………………………53
第五章 結論…………………………………………………103
第六章 未來展望……………………………………………104
參考文獻……………………………………………………105
英文論文大綱………………………………………………108
作者簡歷……………………………………………………111

參考文獻
[1] G. DE Vahl Davis, “Natural convection of air in a square cavity : a bench mark numerical solution,” International Journal for Numerical Methods in Fluids, Vol.3, pp.249-264, 1983.
[2] Claudio Cianfrini, Massimo Corcione and Pier Paolo Dell’Omo, “Natural convection in tilted square cavities with differentially heated opposite walls,” International Journal of Thermal Sciences,Vol.44, pp.441-451, 2005.
[3] Wei Tong, “Flow structure and temperature measurements in a 3-D vertical free convective enclosure at high Rayleigh numbers,” International Journal of Heat and Fluid Flow, Vol.20, pp.624-633, 1999.
[4] S. S. Hsieh and S. S. Yang, “Aspect ratio effect on natural convection in water near its density maximum temperature,” International Journal of Heat and Mass Transfer. Vol.40, pp.1467-1480, 1997.
[5] Kline, S. J. and McClintock, F. A., “Describing Uncertainties in Singe-Sample Experiments,” Mechanical Engineering, pp.3-8, 1953.
[6] Wenjiang Wu and Chan Y. Ching, “The Effect of the Top Wall Temperature on the Laminar Natural Convection in Rectangular Cavities With Different Aspect Ratios,” ASME Journal of Heat Transfer, Vol.131, pp.052501(1-11), 2009.
[7] J.L. Wright, H. Jin , K.G.T. Hollands and D. Naylor, “Flow visualization of natural convection in a tall, air-filled vertical cavity,” International Journal of Heat and Mass Transfer. Vol.49, pp.889-904, 2006.
[8] Y.S. Tian and T.G. Karayiannis, “Low turbulence natural convection in an air filled square cavity Part I: the thermal and fluid flow fields,” International Journal of Heat and Mass Transfer. Vol.43, pp.849-866, 2000.
[9] E.M. Sparrow and J.P. Abraham, “A new buoyancy model replacing the standard pseudo-density difference for internal natural convection in gases,” International Journal of Heat and Mass Transfer. Vol.46, pp.3583-3591, 2003.
[10] D. Mukutmoni and K. T. Yang, “Thermal convection in small enclosures: an atypical bifurcation sequence,” International Journal of Heat and Mass Transfer. Vol.38, pp.113-126, 1995.
[11] C. Y. Soong, P. Y. Tzeng, D. C. Chiang and T. S. Sheu, “Numerical study on mode-transition of natural convection in differentially heated inclined enclosures,” International Journal of Heat and Mass Transfer. Vol.39, pp.2869-2882, 1996.
[12] M. Paroncini and F. Corvaro, “Natural convection in a square enclosure with a hot source,” International Journal of Thermal Sciences, pp.1-13, 2009.
[13] A. Müftüoğlu and E. Bilgen, “Natural convection in an open square cavity with discrete heaters at their optimized positions,” International Journal of Thermal Sciences, Vol.47, pp.369-377, 2008.
[14] J. Xamán, J. Arce, G. Álvarez and Y. Chávez, “Laminar and turbulent natural convection combined with surface thermal radiation in a square cavity with a glass wall,” International Journal of Thermal Sciences, Vol.47, pp.1630-1638, 2008.
[15] Xundan Shi and J. M. Khodadadi, “Laminar Fluid Flow and Heat Transfer in a Lid-Driven Cavity Due to a Thin Fin,” ASME Journal of Heat Transfer, Vol.124, pp.1056-1063, 2002.
[16] Xundan Shi and J. M. Khodadadi, “Laminar Natural Convection Heat Transfer in a Differentially Heated Square Cavity Due to a Thin Fin on the Hot Wall,” ASME Journal of Heat Transfer, Vol.124, pp.624-634, 2003.
[17] Amaresh Dalal and Manab Kumar Das, “Laminar natural convection in a complicated cavity with spatially variable upper wall temperature,” ASME Summer Heat Transfer Conference, HT2003-47065, 2003.
[18] Amaresh Dalal and Manab Kumar Das, “ Laminar natural convection inside a wavy enclosure heated from top and uniformly cooled from the bottom and both sides,” IMECE2005-80607, 2005.
[19] El Hassan Ridouane, Antonio Campo and Jane Y. Chang, “Natural convection patterns in Right-Angled triangular cavities with heated vertical sides and cooled hypotenuses,” ASME Journal of Heat Transfer, Vol.127, pp.1181-1186, 2005.
[20] Carslaw, H. S. and J. C. Jaeger, “Conduction of Heat in Solids,2nd Edition,” Oxford, London, 1959.
[21] Catton, I., “Natural Convection in Enclosures,” Proc. 6th Int. Heat Toronto, Canada,Vol.6, pp.13-31, 1978.
[22] Khalil Khanafer, Kambiz Vafai and Marilyn Lightstone, “Buoyancy-driven heat transfer enhancement in a two-dimensional enclosure utilizing nanofluids,” International Journal of Heat and Mass Transfer. Vol.46, pp. 3639-3653, 2003.
[23] 鄭鴻斌, “不同流體再傾斜角度之封閉矩形空間中二維自然對流現象研究,”國立虎尾科技大學機械與機電工程研究所碩士論文, 2006.