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研究生:林建中
研究生(外文):Chien-Chung Lin
論文名稱:矩形容器內奈米流體之自然對流熱傳現象之研究
論文名稱(外文):A Study of Natural Convection Heat Transfer in a Rectangular Enclosure Filled with Nanofluids
指導教授:何清政
指導教授(外文):Ching-Jenq Ho
學位類別:碩士
校院名稱:國立成功大學
系所名稱:機械工程學系碩博士班
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2004
畢業學年度:92
語文別:中文
論文頁數:74
中文關鍵詞:矩形容器奈米流體自然對流
外文關鍵詞:Natural ConvectionRectangular EnclosureNanofluids
相關次數:
  • 被引用被引用:15
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  • 下載下載:33
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  本文係以實驗量測與數值模擬方式探討矩形容器內奈米流體之自然對流熱傳現象。所探討之理論模型為一左邊加熱及右邊冷卻的矩形容器,而其餘邊界皆為絕熱壁。理論模式關係式中,將奈米流體之熱傳導係數隨溫度及濃度變化效應以及奈米粒子間的相對速度效應列入考慮,而數值模擬主要考慮參數範圍為:萊利數(Ra=1.E+04 ~1.E+07 );普蘭特數(Pr=6.5);奈米粒子質量濃度(Cm=3.52%、6.86%、10.04% )、奈米粒子無因次粒徑(Dp=2.55.E-06 )及有效粒徑修正倍數( Rc=1、10、100)。就數值模擬結果顯示,在上述萊利數範圍下,其奈米流體熱傳率皆較純水為佳,並且隨濃度之增加而提升。實驗之物理模形,考慮五組不同之奈米流體質量濃度,及其相對應之不同萊利數變化,就實驗結果和數值模擬相互比較發現,奈米流體熱傳率會有明顯的降低,而矩形容器內之熱傳現象,取決於萊利數及濃度。
  The problem of two-dimensional steady state natural convection heat transfer in a square enclosure filled with nanofluids has been investigated numerically and experimentally. The enclosure is differentially heated across two vertical walls of the enclosure while the remaining side walls are assumed adiabatic. In the numerical formulation, the effects of variable thermal conductivity of the nanofluids associated with temperature and particle fraction as well as of the settling velocity of the nanoparticles with respect to the bulk fluid have been accounted. The numerical simulations have been undertaken for the pertinent dimensionless parameters in the following ranges: the Rayleigh number,Ra=1.E+04 ~1.E+07 ; the Prandtl number,Pr =6.5; the mass fraction of the nanoparticles,Cm= 3.52%, 6.86%, 10.04%; the dimensionless particle diameter,Dp=2.55.E-06 ; the effective particle clustering factor, Rc=1,10,100. Numerical results clearly indicate that in comparison with the heat transfer results of the pure fluid for the range of Rayleigh number considered, incorporating the nanofluids of various mass fractions can always result in significant heat transfer enhancement. On the other hand, experiments mimicking the physical configuration considered have been conducted mainly for five different mass fractions under various Rayleigh numbers. Contrary to the numerical findings, the experimental measurements reveal that using the nanofluids may result in marked reduction, instead of enhancement, of the transfer across the enclosure, depending on the Rayleigh number and the mass fraction.
第一章 序論………………………………………………...1
1-1 文獻回顧…………………………………………....2
1-2 研究目的…………………………………………....7
1-3 本文架構…………………………………………....7
第二章 數值模擬分析與結果…………………….........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……………….............18
2-3-1 數值方法…………………………...........18
2-3-2 解題方式………………………………….....20
2-4 格點測試…………………………………….......21
2-5 數值模擬結果與討論………………………….....22
2-5-1 文獻比較………………………………….....23
2-5-2 容器內含氧化鋁奈米流體之自然對流熱傳現象.................................................24
第三章 實驗量測與結果…………………………………..41
3-1 奈米流體製備………………………………….....41
3-1-1 界面活性劑……………………………….....41
3-1-2 製程…………………………………………...42
3-1-3製備實驗與結果………………………………..42
3-1-4 粒徑量測………………………………….....43
3-2 實驗模型…………………………………………...43
3-2-1 實驗模型之主要結構………………………….44
3-3 實驗周邊裝置……………………………………...45
3-4 實驗方法與步驟……………………………….....46
3-5 實驗數據換算……………………………………...47
3-6 不準度分析………………………………………...50
3-7 實驗結果與討論……………………………….....50
3-7-1 容器內自然對流熱傳係數........………...50
3-7-2 奈米流體熱傳導係數之探討…………….....54
3-8 實驗與數值模擬結果之比較……………………...56
第四章 結論與未來方向…………………………………..63

參考文獻…………………………………………………...65
Choi, S. U. S, “Enhancing Thermal Conductivity of Fluids with Nanoparticles”, Developments and Applications of Non-Newtonian Flows, Siginer DA, Wang HP (eds) FED vol. 231/MD-vol. 66, ASME, New York, pp 99-105, 1995.

Das, S. K., Putra, N., Thiesen, P., Wilfried, R., “Temperature Dependence of Thermal Conductivity Enhancement for Nanofluids”, ASME J. Heat Transfer, Vol. 125, pp. 567-574, 2003.

Khanafer, K., Vafai, K., Lightstone, M., “Buoyancy-Driven Heat Transfer Enhancement in a Two-Dimensional Enclosure Utilizing Nanofluids”, Int. J. Heat Mass Transfer, Vol. 46, pp. 3639-3653, 2003.

Putra, N., Roetzel, W., Das, S. K., “Natural Convection of Nano-Fluids”, Heat and Mass Transfer, Vol. 39 , pp. 775-784, 2003.

Tannehill, J. C., Anderson, D. A., Pletcher, R. H., “Computation Fluid Mechanics and Heat Transfer”, Taylor and Francis, 1978.

Xuan, Y., Li, Q., “Heat Transfer Enhancement of Nanofluids”, Int. J. Heat and Fluid Flow, Vol. 21, pp. 58-64, 2000.

Xuan, Y., Li, Q., “Investigation on Convective Heat Transfer and Flow Features of Nanofluids”, ASME J. Heat Transfer, Vol. 125, pp. 151-155, 2003.

Xuan, Y., Li, Q., Hu, W., “Aggregation Structure and Thermal Conductivity of Nanofluids”, AIChE Journal, Vol. 49, No. 4, April 2003.

Zhou, D. W., “Heat Transfer Enhancement of Copper Nanofluid with Acoustic Cavitation,” Int. J. Heat Mass Transfer, Vol. 47, pp. 3109-3117, 2004.


何泰安, “矩形容器內含懸浮相變化微粒之自然對流熱傳之特性實驗研究,” 國立成功大學機械工程研究所碩士論文,1999.

林宗慶, “相變化懸浮微粒之過冷現象對直立矩形容器自然對流熱傳之影響,” 國立成功大學機械工程研究所碩士論文,2003.

張純, “水平矩形容器內含相變化微粒懸浮液體自然對流熱傳特性之探討,” 國立成功大學機械工程研究所碩士論文,2002.

夏志豪, “矩形容器內含懸浮相變化微粒之自然對流熱傳之數值模擬,” 國立成功大學機械工程研究所碩士論文,2000
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