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研究生:郭政威
研究生(外文):Jeng-Wei Guo
論文名稱:水平橢圓管內膜狀凝結之熵增分析
論文名稱(外文):Entropy Generation Analysis of Film Condensation in a Horizontal Elliptical Tube
指導教授:楊勝安楊勝安引用關係
指導教授(外文):Sheng-An Yang
學位類別:碩士
校院名稱:國立高雄應用科技大學
系所名稱:模具工程系
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:2009
畢業學年度:97
語文別:中文
論文頁數:70
中文關鍵詞:熱虹吸管水平橢圓管凝結液橢圓管熱力學離心率圓管膜狀凝結
外文關鍵詞:thermodynamics second lawhorizontal elliptical tubeentropy generationfilm condensation
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本文目的在研究水平橢圓管內一飽和蒸汽經由等壁溫散熱,使用熱力學第二定律原理與數值解析,並參考學者Adrian Bejan所提出的熵增最佳化方法(EGM)與指導教授楊勝安教授之膜狀凝結熱傳研究方法,以分析其上的膜狀凝結熵增率。本研究探討的參數包括橢圓離心率 、表面張力 、Nusselt數、 數及布林克曼參數 ,在凝結過程中對凝結液厚度與熵增率的影響。
結果顯示,熵增率與橢圓離心率、 數、布林克曼參數呈現一個正比的關係。另外,當離心率過於低時(接近圓管),表面張力對系統熵增的影響將可以忽略。最後,本研究分析結論,可作為熱力散熱系統設計的參考。
Based on the thermodynamic second law, this thesis aims to study the film condensation heat transfer phenomenon from saturated vapor flowing slowly inside a horizontal elliptical tube. This research has combined the EGM technique ( entropy generation minimization ), proposed by Adrian Bejan, for the laminar flow with convection heat transfer situation and the heat transfer approach developed by my adviser, Dr. Yang for laminar film condensation in term of ellipticity, to investigate entropy generation inside a horizontal elliptical tube numerically. Besides, the present paper found the effects of various working parameters, including eccentricity, surface tension, Nusselt number, Ra/Ja number, and Brinkman on condensate thickness and the entropy generation rate.
The results showed that entropy generation rate is directly proportional to the ellipticity, Ra/Ja number and Brinkman parameters. In addition, when ellipticity is too low(close to tube), the effect of surface tension on entropy of the system can be ignored. Finally, the present conclusions of this study can be used as the reference for thermal cooling system design.
目錄
摘 要 i
ABSTRACT ii
誌謝 iv
目錄 v
圖目錄 vii
符號說明..........................................................................................................................ix
一、緒論 1
1-1前言 1
1-2 文獻回顧 1
1-3 研究動機 5
1-4 論文架構 5
二、橢圓極座標之建立與熵増理論 7
2-1橢圓極座標 7
2-2 橢圓極座標表示之表面張力推導 9
2-3 熱力性質-熵 10
2-4 流動摩擦不可逆率與熱傳不可逆率 13
三、等壁溫水平橢圓管內凝結熱傳與熵增分析 16
3-1水平橢圓管內膜狀凝結熱力第二定律分析 16
3-1-1 凝結液局部厚度方程式之建立 16
3-1-2 局部熵增方程式之建立 19
3-1-3 總體熵增方程式之建立 22
3-2 結果與討論 24
3-2-1 膜狀凝結液厚度分佈與流動分離現象 24
3-2-2 水平橢圓管內膜狀凝結熵增探討 24
四、變壁溫水平橢圓管內凝結熱傳與熵增分析 27
4-1水平橢圓管內膜狀凝結熱力第二定律分析 27
4-1-1凝結液局部厚度方程式之建立 27
4-1-2 局部熵增方程式之建立 30
4-1-3 總體熵增方程式之建立 33
4-2結果與討論 35
4-2-1 膜狀凝結液厚度分佈與流動分離現象 35
4-2-2水平橢圓管內膜狀凝結熵增探討 36
第五章 結論 64
5-1 綜合討論 64
5-1-1 等壁溫之局部與總體熵增分析方面 64
5-1-2 變壁溫之局部與總體熵增分析方面 65
5-2 未來研究方向與建議 65
參考文獻 67
簡歷 70
參考文獻
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