垂直濃度梯度與水平溫度梯度之熱質自然對流

Experimental Study of Thermosolutal Convection in Low Aspect Ratio Rectangular Enclosures with Two Perpendicular Driving Forces

王立文(L. W. Wang) ； 呂俊嘉(C. C. Leu) ； 李慶中(C. C. Lee) ； 盧明初(M. C. Lu)

《中國航空太空學會學刊》 28卷3期 (1996/09) Pp. 241-247

https://doi.org/10.6124/TAASRC.199609_28(3).08

摘要

本研究目的是以實驗的方法探討低展弦比之矩形密閉盒內，由上濃下淡的垂直濃度梯度與水平溫度梯度所共同引起的熱質自然對流(thermosolutal convection)流場型態，以及不同流場型態對盒內溶液溫度的影響。
實驗的裝置是以銅板及壓克力板構成各種不同展弦比之炬形盒。工作溶液爲硫酸銅水溶液。實驗中溫度梯度是由恆溫水槽來維持。濃度梯度是由電化學的方法來造成，即利用電解方式在兩銅板附近形成不同濃度的邊界層。對於盒內流場現象採用雷射光暗影法(shadowgraphy)與加入質點(particles)配合光幕的質點光幕法來觀察流場。爲暸解流場結構，對流場的溫度分佈亦需量測。最後，對於質傳遞率Sh值在固定Gr，m下，探討Sh與Gr，t，Sh與Ar之關係。

關鍵字

熱質對流

並列摘要

The purpose of this study is to investigate the transport phenomena of thermosolutal convection in low aspect ratio rectangular enclosures with vertical concentration and horizontal temperature gradients.
The test cell is a rectangular enclosure formed with acrylic and copper plate, which is wrapped with foam insulator to ensure an adiabatic boundary condition. The temperature gradient is maintained uniform and controlled by two separate constant temperature baths, which circulate heated or cooled water through the heat exchanger. The working solution used is aqueous copper sulphate. An electro-chemical method based on a diffusion-controlled electrode reaction will be employed in this work for creating the concentration gradient.
Flow visualization has been accomplished using the particle tracer and shadowgraph technique. Finally, the relations between the dimensionless mass transfer rate Sh and Gr, t as well as Sh and Ar are discussed for a fixed Gr, m. The ranges of the parameters studied in the present work are: Ar=0.125~1, Pr=7~8, Sc=1800~2100, N=2.94~14 and Gr, t=2.89×10^5~1.20×10^6.

並列關鍵字

thermosolutal convection