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研究生:王智弘
研究生(外文):Chih-Hung Wang
論文名稱:共軛混合對流下水平流道內具表面輻射之發熱元件的散熱性能分析
論文名稱(外文):Conjugate Mixed Convection with Surface Radiation From a Horizontal Channel with Heat Generating Component
指導教授:黃博全黃博全引用關係
口試委員:牛仰堯黃仁智
口試日期:2013-07-30
學位類別:碩士
校院名稱:國立臺北科技大學
系所名稱:能源與冷凍空調工程系碩士班
學門:工程學門
學類:其他工程學類
論文種類:學術論文
論文出版年:2013
畢業學年度:101
語文別:中文
論文頁數:88
中文關鍵詞:混合對流輻射熱傳共軛熱傳電子冷卻
外文關鍵詞:Mixed convectionRadiation heat transferConjugate heat transferElectronic cooling
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近年來,由於電子產品快速發展,相對電子元件總發熱量越來越高,如何有效的增加電子元件散熱的方法來確保電子設備的效率、壽命已成一個重要課題。不過以往對於電子元件散熱熱傳分析,一般研究皆幾乎忽略輻射的影響,僅考慮傳導、對流,分析結果無法準確反應實際的狀況。因此本文研究目的即探討在考慮有表面輻射熱傳及管壁熱傳導效應下,電子元件的散熱特性。
研究方法是以數值方法模擬於平行板流道內,具表面輻射熱傳之矩形電子裝構發熱元件在共軛混合對流下,流道內熱流場分佈及發熱元件之散熱熱傳特性。文中純流體區內遵守Navier-Stoke方程式,再配合介面及邊界條件,以流線函數-渦度轉換公式解上述流場及溫度場之聯立方程式,再藉固流介面的能量守恆條件,導入輻射熱傳機至於熱流場中,以獲得元件總熱傳量,輻射熱傳則使用輻射/入射輻射方法。
另藉由變化各項參數,來探討熱流場的變化及其對矩形電子裝構發熱元件的散熱效益。其變化參數包括雷諾數 、封裝材料表面放射率 、流道內壁表面放射率 、封裝材料熱傳導係數比 、流道內壁熱傳導係數比 與葛瑞斯何夫數 ,並選定基本操作參數值為Re=500、Gr=2.89x105、qv=3x106、kp/kf=100、ks/kf=50、εp=0.55、εs=0.55,作為參數影響之基本比較。經由計算結果可得到以下結論,(1)當探討電路板上晶片之熱分析時,考慮輻射熱傳可以更精準的預測操作時的最大溫度,本文在基本操作參數下,考慮輻射熱傳,系統內最大溫度下降了大約12度; (2)矩形電子裝構發熱元件之散熱效果,隨著雷諾數 增加而增加,系統內最高溫度下降大約16度; (3)相較於增加封裝材料表面放射率 ,增加流道內壁表面放射率 能更有效的降低系統內溫度; (4)也可以藉由增加熱傳導係數比更容易觀察平板和矩形發熱元件之熱傳現象。整體而言,在雷諾數較低或是系統溫度較高的條件下,可以更明顯的觀察到輻射熱傳的散熱效果,進一步改善來達到所需要的工作環境。


In recent years, due to the rapid development of electronic products, the relative electronic components heat is getting higher and higher, how to effectively remove the heat of electronic components to ensure the efficiency and life of the electronic equipment has become an important issue. However, the general studies in the electronic cooling almost ignored the effect of radiation and only took conduction, and convection into consideration. The obtained results can not accurately reflect the actual situation. The purpose of this study is to investigate the cooling of the electronic components under the consideration of surface radiation and the conduction in the wall.
In this work, a numerical study was carried out for the thermal and flow field distributions and heat transfer characteristics from a steady-state flow, horizontal channel with the rectangle electronic package heat source blocks. The thermal-flow field is governed by energy and Navier-Stokes equations in the fluid region. Through the use of a stream function-vorticity transformation, solution of the coupled governing equations for the fluid/solid system is obtained using the control-volume method. Then importing the solid/fluid interface energy conservation conditions with the radiant heat transfer to obtain the total heat transfer. The radiation heat transfer is based on the radiosity / irradiation method. This study details the effects of variations in the Reynolds number, surface emissivity of packaging materials and the channel walls, thermal conductivity ratio of the packaging materials and the channel walls, and the modified Grashof number, to illustrate the important fundamental relations between the thermal-fluid field and the heat-source cooling.
Selected basic operating parametersRe=500、Gr=2.89x105、qv=3x106、kp/kf=100、ks/kf=50、εp=0.55、εs=0.55. The numerical results obtained the following conclusions: (1) While carrying out a thermal analysis of circuit boards with electronic chips, the consideration of radiation heat transfer is absolutely essential to accurately predict the non-dimensional maximum temperature, in this study the maximum temperature drops from 355K in the pure convection case to 343K in same case with radiation, (2) The cooling effect of rectangle electronic package devices increases with the Reynolds number, and the maximum temperature drop is about 16 degrees, (3) compared to the surface emissivity of packaging material, increasing the surface emissivity of channel walls can be more effectively reduce the system temperature, (4) Increasing the thermal conductivity ratio leads to strong the heat transfer phenomena in rectangle electronic package blocks and the channel walls. Overall, in the low Reynolds number condition or the system under the conditions of high temperature, the cooling effect of the radiation heat transfer is more significant resulting in further improvements to achieve the desired working environment.


目 錄

摘 要 i
ABSTRACT iii
誌 謝 v
目 錄 vi
表目錄 viii
圖目錄 ix
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 2
1.2.1 電子冷卻技術 2
1.2.2 混合對流熱傳研究 3
1.2.3 結合傳導、對流與輻射之電子冷卻的應用 3
1.3 研究目的 5
第二章 基礎理論 6
2.1 系統描述 6
2.2 基本假設 7
2.3 統御方程式 8
2.3.1 純流體區統御方程式 8
2.3.2 固體區統御方程式 9
2.3.3 輻射熱傳統御方程式 10
2.3.4 解析區域之邊界條件 13
2.4 無因次化分析 15
2.4.1 無因次化純流體區 16
2.4.2 無因次化固體區 17
2.4.3 無因次化輻射熱傳 17
2.4.4 無因次化邊界條件 18
2.4.5 紐賽數的計算 20
第三章 數值分析 21
3.1 流體區差分方程式 22
3.2 固體區差分方程式 29
3.3 輻射之矩陣問題 32
3.4 靠近平板壁面處之渦度邊界問題 36
3.5 鬆弛係數(Relaxation factor) 37
3.6 格點產生(Grid generation) 39
3.7 求解步驟 41
第四章 結果與討論 43
4.1 網格獨立 43
4.2 數值驗證 44
4.3 穩定流場下輻射熱傳所引起之熱流場變化 48
4.4 雷諾數 之影響 53
4.5 封裝材料表面放射率 之影響 57
4.6 流道內壁表面放射率 之影響 62
4.7 封裝材料熱傳導係數比 之影響 69
4.8 流道內壁熱傳導係數比 之影響 72
4.9 葛瑞斯何夫數 之影響 75
第五章 結論 80
參考文獻 82
符號彙編 85


參考文獻

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