本研究提出一創新的新型部分開放垂直熱沉(A)，並以數值方法探討無限垂直通道陣列中之單一通道之自然對流特性，進而與常見的封閉垂直通道熱沉(B)及垂直U型通道平行板熱沉(C)比較。本研究分為三大部分：第一部分深入探討相同尺寸下(H=200 mm，Li=15 mm)，A、B、C三種熱沉中各流場對於散熱性能的影響並決定個別之最佳間隙Sopt。其中A設計的部分開口不同寬度與位置亦經最佳化確認。結果顯示在個別Sopt下，A熱沉與B、C相比之散熱量分別提升13.4%及30.5%；當取相同間隙S=16 mm時分別提升15.0%及66.9%。流場分析顯示，A設計性能提升原因有三：(i)熱沉A保留上方大範圍的熱氣區，與熱沉B銅能形成有效的虛擬煙囪效應；(ii)側向部分開口注入之冷空氣利於散熱；(iii)其特殊鏡對稱開口可形成漩流對，強化通道中的熱對流。第二部分探討不同鰭片長度Li =15, 29, 49 mm的影響，結果顯示Li越長，因A熱沉引入的低溫氣流的相對影響範圍減少，對B熱沉之優勢略減，最佳間隙也越小，且散熱量對間隙改變越敏感。第三部分探討不同鰭片高度H=100, 200, 300 mm的影響，結果顯示H越高，煙囪效應更強烈，Sopt更寬，A設計可更顯著提升性能。本A熱沉具有三大優勢：(1)在相同空間限制及個別Sopt下，A熱沉之散熱量顯著高於B、C熱沉；(2)最佳間隙範圍大，甚至可高達26 mm，可減少熱沉材料與重量；(3)可使用鋁擠方法快速量產。本研究提出之A熱沉實為能有效提升散熱性能且具有高度應用價值的創新設計。

In this study, the natural convection characteristics from a novel partially-open vertical heatsink (A) is investigated numerically. A single channel in an vertical infinite-channel array of Heatsink A is computed and compared with that of existing closed-duct heatsink (B) and U-duct plate-fin heatsink (C). This study is divided into three major parts. Part I investigates the flow-field effect on the thermal performance of Heatsinks A, B and C with the same dimensions (H=200 mm, Li=15 mm). The thermal performance is compared at respective optimal fin spacing Sopt of the heatsinks. The best width and position of the partial opening is also determined for Heatsink A. The results show improved heat dissipation rates of Heatsink A by 13.4% and 30.5% in comparison with B and C at respective Sopts, and 15.0% and 66.9% at the same spacing S=16 mm. Flow field analysis shows three reasons for the performance improvement of Heatsink A: (i) A strong virtual chimney effect associated with the hot plume region above the channel is retained to result in higher upward air flow; (ii) The cold inward air flow along the opening further improves heat transfer; (iii) Swirling pairs induced by the mirror-symmetric partial openings of Heatsink A intensify heat transfer within the ducts. In Part II the effect of different fin lengths (Li = 15, 29, 49 mm) is investigated. The results show that the longer the lengths, the less improvement is provided by Heatsink A. Also, its optimal spacing decreases and the heat dissipation rate is more sensitive to the spacing variation. In Part III, different fin heights (H=100, 200, 300 mm) are investigated to exhibit stronger chimney effect, wider optimal spacing, and better thermal performance by Heatsink A. With a wide optimal spacing range up to 26 mm, the cost can be reduced with less material and weight of the heatsink. Three major advantages of Heatsink A can be summarized as: (i) significant larger heat dissipation rate than existing Heatsinks B and C; (ii) wider optimal spacing range reducing the cost with less material and weight of the heatsink; (iii) suitability of mass production using aluminum extrusion. This innovative heatsink design can effectively improve heat dissipation performance and has high application value.

摘要 i
Abstract ii
符號表 v
目錄 viii
圖表目錄 x
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 2
1.2.1等溫垂直平行板熱沉 2
1.2.2 等溫垂直通道 5
1.3 研究目的 7
第二章 數值方法 10
2.1 概說 10
2.1.1模擬無限通道的單通道計算域 10
2.1.2 統御方程式與邊界條件 11
2.1.3求解方法 12
2.1.4離散方法 13
2.1.5參數設定 13
2.1.6網格測試 14
2.2模擬可靠度驗證 14
第三章 結果與討論 19
3.1 Li=15 mm, H=200 mm三種無限通道的單通道散熱量與流場特性 19
3.1.1 A設計部分開口寬度與開口位置的影響 19
3.1.2三種熱沉散熱量與流場特性之比較 19
3.2 不同鰭片長度(Li=15, 29, 49 mm)的效應 30
3.3 不同鰭片高度(H=100, 200, 300 mm)的效應 37
第四章 結論 41
參考文獻 43

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