具下隔板環狀封閉區域中熱質之自然對流現象

Natural Convertion Heat and Mass Transfer within an Annular Enclosure with Under Partition

楊宗達(Chung Da Yang)

指導教授 ： 王立文

元智大學/工程學院/機械工程學系/碩士(2000年)

摘要

具 下 隔 板 環 狀 封 閉 區 域 中 熱 質
之 自 然 對 流 現 象
摘 要
指導教授 : 王 立 文 老師
研 究 生 : 楊 宗 達
本實驗的目的在於藉助實驗方法來探討具下隔板環狀封閉區域中，溫度及濃度梯度所引起的自然對流之流場形態、溫度分佈以及濃度分佈。此研究動機起因於結晶成長過程中組成不均勻的現象非常嚴重，因此對於過程中，熱量及質量的傳遞應作充分了解。
本文所作實驗，將內圓環和外銅環賦予溫度差和濃度差，其它邊界保持絕緣。本研究分成兩部分：
（1）熱質逆向傳遞的研究。
（2）熱質順向傳遞的研究。
工作中改變不同的溫度及濃度梯度，並且放置不同角度隔板，以便觀察比較各種流場結構、溫度分佈以及濃度分佈。
流場型態觀察是使用雷射光束暗影法,在不影響流動的情況下,作流場觀察。流場溫度分布則是將熱偶線接至溫度紀錄器,量得待測位置之溫度。
流場的濃度分布則使用非干擾性(Noninstrusive technology)的方法來測量。此方法是利用光線透過硫酸銅溶液時,被銅離子所吸收的光的強度和濃度成正比的關係,來求出該點的平均濃度。
本實驗中， Ar=0.32, Sc=1700~2300, Pr=6.5~7.0, Gr,t=104~106, N=-10~10, k=3.0, S/Ro=0.625

關鍵字

自然對流 ； 環狀封閉區域 ； 隔板

並列摘要

Natural Convection Heat and Mass Transfer with
An Annular Enclosure with Under Partition
Advisor : Dr. L.W. Wang＊
Student: C.D. Yang
Department of Mechanical Engineering
Yuan-Ze University
ABSTRACT
The purpose of the present study is to investigate flows resulting from buoyancy force due to a combination of temperature and species convection effects in a horizontal annular enclosure with under partition. The knowledge in thermosolutal convection flows in horizontal enclosure is valuable and important in the study of crystal growth processes. The system, which enables opposing or cooperating temperature and concentration gradients to be imposed, is described. The flows have double-diffusive characteristics because of the large difference between the thermal and solutal diffusion rates. The test cell is an annular enclosure formed with under partition that has different angles. Complex flow patterns are observed as the parameters are varied.
To visualize flow structures, the shadowgraph technique is used. The temperature distributions in the annular enclosure can be measured by the thermocouples.
An optical technique used for the concentration measurement of cupric ions is developed. This technique is based on the idea that the intensity of the light beam absorbed by a copper sulphate solution is proportional to the solution concentration when the light beam passed through the solution.
The ranges of the parameters studied in present work are Ar=0.32, Sc=1700~2300, Pr=6.5~7.0,Gr,t=104~106,N=-10~10 and K=3.0, S/Ro=0.625

並列關鍵字

Natural Convertion ； Annular Enclosure ； Partition

參考文獻

1.S. Ostrach,〝Natural Convection with Combined Driving Forces〞,

2. E. H. Bishop, and C. T. Carley,〝Photographic Studies of Natural

Convection between Concentric Cylindders〞, Proc. Heat Transfer

Fluid Mech. Inst. pp. 63-78, (1966).

3.R. E. Powe, C. T. Carley, and E. H. Bishop.〝Free Convective Flow