熱質源壁具雙凸塊之密閉盒的熱質對流現象研究

The Study of Thermosolutal Convection in An Enclosure with Two Blocks

戴延南(Yen-Nan Tai)

指導教授 ： 王立文

元智大學/工程學院/機械工程學系/碩士(2006年)

https://doi.org/10.6838/YZU.2006.00072

摘要

摘 要
本研究主要乃藉實驗方法來探討封閉矩形盒內放置垂直於冷熱質源璧上之雙凸塊，所產生之凸塊(block)效應，在熱質自然對流中所展現的流場型態。
實驗裝置為矩形的封閉盒，盒子左右兩側邊界由銅板與絕緣之電木凸塊(block)組成。上、下板則為絕緣之電木板。前後板則為絕熱之透明壓克力板。
實驗工作流體為硫酸銅水溶液( CuS04 + H2SO4+ H2O )；溫度梯度由兩個不同溫度的恆溫水槽維持；濃度梯度則由電化學系統來建立，於銅板加上端電壓，使其成為電極造成濃度梯度。對於封閉盒內流場現象，乃是採用雷射光暗影(shadowgraphy)來觀察流場，並以相機拍照紀錄以利分析。並針對相關Grt、Grm 無因次參數及不同傾斜角度來探討封閉區域內流場結構影響。為了瞭解流場結構，對流場的溫度及濃度分佈亦做量測。最後，對於質傳遞率Sh值與Grm、Grt之關係做量測與分析。
於本實驗研究發現，流體受凸塊效應的影響，產生複雜的流場型態。於順向流場中均有層化現象產生，逆向流場則觀察到鹽手指現象。探討質傳遞率Sh值則發現，Sh值隨Grt的增加而增加；隨傾斜角度的增大而遞減。

關鍵字

雙凸塊 ； 密閉盒 ； 熱質對流

並列摘要

ABSTRACT
The current study is primarily motivated to gain better a understanding of the flow pattern, the temperature and concentration gradient caused by thermosolutal convection in an electrochemical system with a vertical central partially divided enclosure.
The test cell is a rectangular enclosure formed with acrylic ,Bakelite and copper plates, which is wrapped with block Bakelite insulator to ensure an adiabatic boundary condition.
In this experiment, the temperature and the concentration differences are made between two right and left copper walls and the two blocks are made of Bakelite to simulate. The research area targets the flow pattern, change of Grt. We use copper sulphate-sulfuric acid solution as the working fluid. Two constant temperature baths sustain the temperature gradient. The concentration gradient is controlled via an electrochemical system. In order to visualize the flow, the shadowgraph technique is used.
To understand the flow structure, the temperature distribution and concentration distribution will be investigated. Finally, the correlations between the Sherwood number, and the thermal Grashof number will also need to be analyzed.
It is demonstrated that multilayer structures and finger type flow are found in the cooperating case and the opposing case, respectively. It is also found that Sh increased with increasing Grt for fixed Grm value and decreased with increasing θ(inclination angle).

並列關鍵字

Two Blocks ； Enclosure ； Thermosolutal

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