臺灣博碩士論文加值系統

隨著近年來LED的相關產業蓬勃發展，要將具備低驅動電壓、高色再現性、不含汞等特性的發光二極體應用在液晶電視的背光模組中即將不再是耗費高成本的難事了，未來極有可能以低成本、無額外耗電、無震動現象等優點的自然對流方式來解決大尺寸背光模組的散熱問題。因此在液晶電視的外型厚度、外殼開孔面積限制下，找出最佳化的散熱鰭片設計為本文主要探討的重點。本文所採用的數值方法，在有限的對流空間限制下，鰭片的溫度分布、熱傳效率、最佳化形狀設計都與開放空間中明顯不同，極難以完全開放空間的結果加以推估；在外殼開孔率的邊界影響之下，系統內的流場對流溫度隨著開孔率降低而產生升高的現象，其中更以開孔率低於50%時變化最為明顯。另外本文最後也以流場的紐塞數、雷里數的關係曲線來分析不同情況下的對流效果，發現只有改變屏蔽間隙與開孔率此兩項參數才會明顯影響流場的紐塞數、雷里數對應關係，其餘如調整鰭片之間的距離雖然可以直接改變了鰭片表面溫度，但是對於上述對應關係卻無太大幅度的影響。

Along with the explosion of LED-related industry, applying LED containing low-voltage operation, high-color rendering, and low pollution to LCD TV backlight is going to be no longer a high-priced business. In the future, it is very possible to solve the heat dissipation problem in the jumbo-sized backlight models by the application of natural convection which is low-cost, no extra power supply, and no vibration phenomenon. Therefore, under the limitation of TV exterior shape and open area of shell, figuring out the optimizing design of the heat sink is the keystone of this article. Furthermore, according to the result of simulation, the temperature distribution, heat transfer efficiency, and optimized design of heat sink within the definite convection space are apparently different from those in free space, and the results in shrouded space is even hard to be estimated by those in all free space. Under the influence of opening ratio of the shell, the convection temperature of fluid in the system increase as the ratio decrease, especially obviously below 50% of the open area. In addition, at the end of the article Nusselt Number－Rayleigh Number relation curve is used to analyze the convection effect under different conditions. The result shows that only by changing the two parameters, shrouded clearance and opening ratio, the Nusselt Number－Rayleigh Number correspondent relationship can be obviously affected. Other parameter, like adjusting the fin pitch, can directly change the surface temperature of heat sink, but it has nothing to do with Nusselt Number－Rayleigh Number correspondent relationship.

目錄
口試委員會審定書 ⅰ
誌謝ii
中文摘要iii
英文摘要iv
目錄v
圖目錄vii
表目錄xi
符號說明xii
第一章 緒論1
1.1 研究背景1
1.2 研究動機3
1.2.1 LED背光模組發熱原理4
1.2.2 LED背光模組發展進程與趨勢4
1.2.3 LED背光模組之散熱效能評估6
1.3 文獻回顧8
1.3.1 自然對流之散熱鰭片發展過程8
1.3.2 屏蔽式散熱鰭片之分析10
1.3.3 開孔率之實驗、模擬與應用11
1.4 研究目的與內容12
第二章 理論模式與數值方法13
2.1 基本理論13
2.1.1 自然對流模式與統御方程式13
2.1.2 開孔率邊界與壓降方程式14
2.2 數值模擬軟體簡介16
2.3 數值求解流程17
2.4 時間與空間離散模式17
2.5 壓力與速度耦合方程式18
2.6 紊流模式與壁面函數19
2.7 鬆弛因子22
第三章 實例測試與驗證23
3.1 軟體測試：二維實例測試23
3.2 自然對流之流場測試與驗證23
3.2.1 流場外型與網格系統23
3.2.2 流場邊界設定與紊流模式24
3.2.3 測試結果與比較24
3.3 開孔邊界壓降方程式之驗證26
3.3.1 壓降係數與流場設定26
3.3.2 結果比較27
3.3.3 討論與評估29
3.4 自然對流流場中的開孔邊界29
3.4.1 試誤法流程介紹30
3.4.2 二維流場之邊界設定與網格系統30
3.4.3 結果測試與討論31
第四章 三維流場實際模擬結果33
4.1 三維流場之物理計算模型與網格系統33
4.2 基本假設、邊界條件說明34
4.3 網格系統36
4.4 流場參數說明37
4.5 控制參數－改變屏蔽間隙39
4.5.1 三維流場之結果驗證40
4.5.2 改變屏蔽間隙之結果討論41
4.5.3 改變鰭片間距之結果討論46
4.6 結論48
第五章 開孔率影響之討論50
5.1 開孔率參數設計50
5.2 結果比較－鰭片溫度50
5.3 討論－流量與對流速度51
5.4 討論－鰭片效率52
5.5 總結53
第六章 結論與建議55
5.1 結論55
5.2 建議與未來展望56
參考文獻58
附圖61
附表92

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