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系統識別號 U0026-2208201708463900
論文名稱(中文) 具潛熱/顯熱冷却頂板毫米矩形熱沉內奈米流體共軛對流熱傳遞特性之數值模擬
論文名稱(英文) Numerical simulation on conjugate convection heat transfer characteristics of a nanofluid flow in a mini-channel heat sink with a latently- or sensibly-cooled ceiling
校院名稱 成功大學
系所名稱(中) 機械工程學系
系所名稱(英) Department of Mechanical Engineering
學年度 105
學期 2
出版年 106
研究生(中文) 曾郁婷
研究生(英文) Yu-Ting Tseng
學號 N16044195
學位類別 碩士
語文別 中文
論文頁數 122頁
口試委員 指導教授-何清政
口試委員-謝曉星
口試委員-林清發
口試委員-吳志陽
口試委員-溫昌達
中文關鍵字 氧化鋁奈米流體  相變化微膠囊  矩形熱沉系統  強制對流  熱浮力效應 
英文關鍵字 nanofluid  Micro-Encapsulated Phase Change Material (MEPCM)  rectangular mini-channel  conjugate forced convection  conjugate mixed convection 
學科別分類
中文摘要 本研究以數值方法模擬三維矩形流道熱沉系統,流道內分別通以純水與氧化鋁奈米流體。主要分成兩部分探討在不同情況下熱沉內共軛對流冷卻特性,第一部分考慮純水和氧化鋁奈米流體於流場中因為受到溫度梯度的影響,探討有/無熱浮力效應對熱傳地特性的影響;第二部分則在上頂壁加一等溫邊界條件,並在上頂板加入相變化膠囊(MEPCM),探討系統在穩態的情況下,相變化為膠囊層潛熱吸收對於整體散熱效果的影響。流道內三維速度場以擬渦度-速度法(Pseudo-Vorticity-Velocity)建構,並以有限體積法離散數學。單一流道的尺寸為:寬1.01mm、高2.02mm、加熱段長50.0mm、鰭片厚度1.01mm、加熱底板厚度2.02mm與上蓋厚度4.54mm。數值模擬探討之相關參數與範圍:氧化鋁奈米流體的重量百分濃度分別為5%和10%(體積百分濃度1.4%和2.8%);流道入口溫度 ;單一流道入口流量為30-180 〖"cm" 〗^"3" /min (〖Re〗_bf=500-2000);加熱底板的熱通量為25.9, 34.0 and 41.9 W/〖"cm" 〗^"3" 。
本研究所得數值模擬結果顯示:在無熱浮力效應時,ω_np=10%的氧化鋁奈米流體在雷諾數2000的情況下,最大壁溫的降幅可達到7.62%;ω_np=10%氧化鋁奈米流體的熱阻相較於純水減少8%。考慮熱浮力效應時,模擬結果發現低雷諾數有較大的理查森數,故熱浮力效應較明顯,在相同雷諾數的條件下,純水較奈米流體的熱浮力應明顯,隨著奈米流體濃度增加熱浮力效應減弱,純水在有/無熱浮力效應的熱傳係數相差5%。當頂板加入相變化為膠囊時,純水相較氧化鋁奈米流體在有/無相變化膠囊層對流體平均溫度影響較大。在低雷諾數下,純水在具相變化微膠囊層條件下可以有效降低流體溫度,純水在雷諾數500的條件下流道出口有1 的溫差。
英文摘要 In present study, we use numerical simulation method to examine the conjugation cooling characteristics of 〖"Al" 〗_"2" "O" _"3" -water nanofluid flow on a three-dimensional min-channel heat sink. The study is divided into two parts to discuss the results. In first part, we discuss the effect of thermal buoyancy on temperature field and velocity field. The second part is to investigate the effect of latently-or sensible-cooled ceiling which is embedded with/without Micro-Encapsulated Phase Change Material(MEPCM). The geometric dimensions for a unit mini-channel are 1.01 mm in width, 2.02 mm in height, 50.0 mm in heating section length, and 1.01 mm in thickness of the fin. Numerical simulations for the conjugate convection problem have been preformed for relevant parameters in following ranges: the inlet temperature, T_"in" =34 ; the volumetric fraction of 〖"Al" 〗_"2" "O" _"3" nanofluid, ω_np=5% and ω_np=10%; the volumetric flow rate Q ̇=30-180 〖"cm" 〗^"3" /min (equivalently 〖Re〗_bf=500-2000); and the heat flux imposed on bottom surface of the heat sink, q_h^"=25.9, 34.0 and 41.9 W/〖"cm" 〗^"3" . The numerical simulation results clearly reveal that using the 〖"Al" 〗_"2" "O" _"3" -water nanofluid to replace the pure water as the coolant can reduce that maximum wall temperature and thermal resistance are 7.62% and 8% respectively. Furthermore, consider the thermal buoyancy effect, the results show that the thermal buoyancy effect is more obvious using the pure water as the coolant in the low flow rate. The heat transfer coefficient is increased about 5% in the case of the pure water with the thermal buoyancy effect. Last, the pure water had a greater effect on the bulk mean temperature
than the 〖"Al" 〗_"2" "O" _"3" -water nanofluid in the case of ceiling with/without MEPCM. The bulk mean temperature can reduce 1 under the condition of low Reynolds number and ceiling with MEPCM.
論文目次 摘要 I
致謝 VI
目錄 VII
表目錄 X
圖目錄 XII
符號表 XV
第一章 緒論 1
1-1前言 1
1-2文獻回顧 3
1-3研究動機與目的 6
1-4論文架構 7
第二章 水/奈米流體於穩態強制/混合對流共軛熱傳模擬分析 8
2-1 物理模型 9
2-2 數學模型 9
2-2-1 基本假設 9
2-2-2 統御方程式 10
2-2-3邊界條件 12
2-2-4無因次化參數 16
2-2-5無因次化統御方程式 18
2-2-6無因次化邊界條件 19
2-2-7流體熱物性質 23
2-2-8熱質傳遞相關物理參數定義 26
2-2-9數值方法 31
2-2-10解題流程 32
2-3模擬驗證 33
2-4網格測試 35
2-5純水強制共軛對流模擬結果 36
2-5-1流場與溫度場分析 36
2-5-2軸向熱傳現象分析 36
2-5-3熱傳效果分析 37
2-5-4流道熱阻分析 37
2-6奈米流體強制共軛對流與混合共軛對流模擬結果 38
2-6-1流場與溫度場分析 38
2-6-2熱傳效果、熱沉延伸壁面散熱率分析 40
2-6-3流道熱阻分析 41
2-6-4效能指標分析 41
第三章 具相變化微膠囊冷卻頂板於穩態下強制共軛熱傳分析 80
3-1物理模型 80
3-2數學模型 81
3-2-1基本假設 81
3-2-2統御方程式 82
3-2-3邊界條件 84
3-2-4無因化次參數 87
3-2-5無因次統御方程式 89
3-2-6無因次化邊界條件 90
3-2-7相變化微膠囊層之熱物性質 93
3-2-8數值方法 94
3-2-9解題流程 95
3-3具相變化微膠囊冷卻頂板結果 96
3-3-1流場與溫度場分析 96
3-3-2微膠囊層熔解率分析 97
3-3-3熱傳效果分析 98
3-3-4流道熱阻分析 98
第四章 結論 116
4-1結論 116
4-2未來研究與展望 118
參考文獻 119
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