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研究生:郭進倫
研究生(外文):Chin-Lun Kuo
論文名稱:絕緣壁具雙凸塊封閉盒之熱質自然對流現象探討
論文名稱(外文):Natural Convection Heat and Mass Transfer in an Enclosure with Two Blocks along the Adiabatic Walls
指導教授:王立文王立文引用關係
指導教授(外文):Lin-Wen Wang
學位類別:碩士
校院名稱:元智大學
系所名稱:機械工程學系
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:2006
畢業學年度:94
語文別:中文
論文頁數:136
中文關鍵詞:熱質自然對流絕緣璧封閉盒凸塊
外文關鍵詞:Heat and Mass ConvectionAdiabatic WallsEnclosureBlocks
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本研究主要乃藉由實驗方法來探討幾何形狀為一正方形的封閉盒,其由溫度梯度與濃度梯度所引起的熱質自然對流現象。左、右邊界由銅板所組成而上、下板與凸塊則為絕緣之電木板。本次的實驗區域,利用其幾何形狀與邊界條件的設定,藉由改變開口比Ap及傾斜封閉盒,使得在實驗中可以觀察到凸塊效應,並針對不同Gr,t、Gr,m來探討封閉區域內流場結構影響。
實驗工作流體為硫酸銅水溶液( CuSO4 + 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。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Gr,m、Gr,t之關係做量測與分析。
實驗結果顯示,傾斜角度對流場質傳遞率有顯著影響。對傾斜角度而言,會造成降低質傳遞率。而無傾斜角度時,由於產生之質柱狀流(solutal plume)及鹽手指(salt finger)現象會造成質傳遞率增加。
The purpose of present study is to investigate flow pattern, temperature and concentration gradients resulting from buoyancy force due to a combination of temperature and species convection effects in an enclosure with blocks. Effect of Gr,t, Gr,m and blocks is the main objective in this study.
The test cell is a square 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 concentration differences are made between two right and left copper walls and the blocks are made of bakelite simulate. 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. Electrical measurements will be used to obtain mass transfer rates to infer Sherwood numbers.
To understand the flow structures, the temperature distribution and concentration distribution will be investigated. Finally, the correlations between the Sherwood number, the solutal Grashof number, the thermal Grashof number will also need to be analyzed. The effects of the blocks will be investigated carefully.
It is demonstrated that Sh decreased with increasing inclination angle for fixed Gr,m value. This is because
the increasing inclination angle results in decreasingly
solutal plumes and finger type flow and,hence, monotonically decreasing Sh.
書名頁………………………………………………………… I
論文口試委員審書 ……………………………………………II
授權書 …………………………………………………………III
中文摘要 ………………………………………………………VI
英文摘要 ………………………………………………………VII
誌謝 ……………………………………………………………VIII
目錄 ……………………………………………………………IX
圖目錄 …………………………………………………………XIV
符號說明 ………………………………………………………XVIII
一、前言 ………………………………………………………1
1.1研究動機……………………………………………………1
1.2文獻探討……………………………………………………2
二、實驗原理與設計 …………………………………………8
2.1溫度梯度之建立……………………………………………8
2.2濃度梯度之建立……………………………………………8
2.3實驗裝置 …………………………………………………11
2.4實驗過程 …………………………………………………11
2.5流場整體結構 ……………………………………………13
2.6流場觀察 …………………………………………………14
2.6.1雷射光暗影法 …………………………………………14
2.6.2溫度的量測 ……………………………………………14
2.6.3濃度的量測 ……………………………………………14
三、實驗結果與討論…………………………………………16
3.1雷射光暗影法流場分析 …………………………………16
3.1.1水平(θ=0°),開口比(Ap=0.625):左板熱板,右板冷板
之流場型態 …………………………………………………16
(1)Case1順向流場……………………………………………16
(2)Case2逆向流場 …………………………………………18
3.1.2水平(θ=0°),開口比(Ap=0.125):左板熱板,右板冷板
之流場型態 …………………………………………………20
(1)Case3順向流場 …………………………………………20
(2)Case4逆向流場 …………………………………………21
3.1.3傾斜(θ=45°),開口比(Ap=0.625):左板熱板,右板冷
板之流場型態 ………………………………………………22
(1)Case5順向流場 …………………………………………22
(2)Case6逆向流場 …………………………………………23
3.1.4傾斜(θ=45°),開口比(Ap=0.125):左板熱板,右板冷
板之流場型態 ………………………………………………25
(1)Case7順向流場 …………………………………………25
(2)Case8逆向流場 …………………………………………26
3.2流場的溫度分佈 …………………………………………28
3.2.1水平(θ=0°),開口比(Ap=0.625):左板熱板,右板冷板
之流場無因次溫度分佈 ……………………………………28
(1)Case1順向流場 …………………………………………28
(2)Case2逆向流場 …………………………………………29
3.2.2水平(θ=0°),開口比(Ap=0.125):左板熱板,右板冷板
之流場無因次溫度分佈 ……………………………………30
(1)Case3順向流場 …………………………………………30
(2)Case4逆向流場 …………………………………………30
3.2.3傾斜(θ=45°),開口比(Ap=0.625):左板熱板,右板冷
板之流場無因次溫度分佈 …………………………………31
(1)Case5順向流場 …………………………………………31
(2)Case6逆向流場 …………………………………………32
3.2.4傾斜(θ=45°),開口比(Ap=0.125):左板熱板,右板冷
板之流場無因次溫度分佈 …………………………………33
(1)Case7順向流場 …………………………………………33
(2)Case8逆向流場 …………………………………………33
3.3流場的濃度分佈 …………………………………………35
3.3.1水平(θ=0°),開口比(Ap=0.625):左板熱板,右板冷板
之流場無因次濃度分佈 ……………………………………35
(1)Case1順向流場 …………………………………………35
(2)Case2逆向流場 …………………………………………36
3.3.2水平(θ=0°),開口比(Ap=0.125):左板熱板,右板冷板
之流場無因次濃度分佈 ……………………………………37
(1)Case3順向流場 …………………………………………37
(2)Case4逆向流場 …………………………………………37
3.3.3傾斜(θ=45°),開口比(Ap=0.625):左板熱板,右板冷
板之流場無因次濃度分佈 …………………………………38
(1)Case5順向流場 …………………………………………38
(2)Case6逆向流場 …………………………………………39
3.3.4傾斜(θ=45°),開口比(Ap=0.125):左板熱板,右板冷
板之流場無因次濃度分佈 …………………………………40
(1)Case7順向流場 …………………………………………40
(2)Case8逆向流場 …………………………………………40
3.4無因次質傳遞率Sh值分析 ………………………………42
3.4.1 Sh與Gr,t之關係 ……………………………………42
3.4.2 Sh與熱質順、逆向之關係 …………………………43
3.4.3 Sh與θ角之關係 ………………………………………43
3.4.4 Sh與Ap之關係 ………………………………………43
四、結論 ……………………………………………………44
參考文獻 ……………………………………………………47
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