臺灣博碩士論文加值系統

本研究利用暫態液晶實驗法測定方形鰭柱陣列於矩形槽道內其邊壁熱傳特性，採用壓克力製作之方柱鰭片散熱座，並具有不同軸之軸向與橫向相對方柱間距，鰭柱尺寸為8mm (d) × 8mm (d) × 64mm (Hf)，均勻直行排列於240mm (L)×120mm (W)×64mm (H)之矩形槽道內，方形鰭柱數目計有(n=24)、(n=36)、(n=48)、(n=612)、(n=714)、(n=816)等六種，相對方柱間距(SL/d=ST/d)為(7.5mm、5 mm、3.75 mm、2.5 mm、2.14 mm、1.88 mm)，測試計有六種相對間距方型鰭柱之排列組合，且採用環境空氣為工作流體，變動參數為雷諾數與鰭柱間距，結果顯示平均紐塞數(Nu)會隨著雷諾數(Re)之增加而增加，也會隨橫向相對方柱間距(XT)降低而增加，不過相較之下軸向相對方柱間距(XL)對紐塞數(Nu)的影響則較不顯著。
在本實驗中可了解到摩擦係數(f)主要形狀阻力所致，故而摩擦係數(f)與雷諾數(Re)的二次方成正比關係，此外，f會隨橫向相對方柱間距降低、或軸向相對方柱間距增大而增大；最後本研究提出矩形槽道內之方型柱狀鰭片散熱座之平均紐塞數對雷諾數之經驗修正公式，和平均紐塞數對應無因次鼓風功率參數(fRe3)之關係式，實驗中發現在相同鼓風功率下，橫向相對方柱間距與軸向相對方柱間距愈小會有較佳之Nu，而fRe3與Nu之關係只與散熱座之鰭柱間距安排有關。

This work investigated the detailed end-wall heat transfer characteristics of the square pin-fin array in a rectangular channel by using the transient liquid crystal method. Use acrylic make square pin-fin teat sink has different relative axial and transverse distances against.The pin fins of dimension 8mm (d) × 8mm (d) × 64mm (Hf) were uniformly filled in the 240mm (L) × 120mm (W) × 64mm (H) channel with in-line arrangement. Six pin-fin numbers were employed. There were (n=24)、(n=36)、(n=48)、(n=612)、(n=714)、(n=816). The working fluid was air. Relative distances against the square pin-fin ( 7.5mm、5 mm、3.75 mm、2.5 mm、2.14 mm、1.88 mm ). A total of seven combinations of relative distance were tested. The working fluid was air. Varied parameters were the Reynolds number and the space between fins. The results showed that the average Nusselt number increases as the Reynold number increases, and decreases as the relative transverse distance against the square pin-fin (XT) decreases. Under comparison, the relative axial distance (XL) has insignificant effect on Nu. Friction coefficient (f) is subject to shape resistance, thus, f is proportional to the square of Re. Also, f increases as the relative transverse distance decreases, and the relative axial distance increases. Lastly, modification of empirical formula of average Nu to Re for in-channel square pin-fin heat sink, and relation of average Nu to dimensionless air blast power parameter (fRe3),are proposed. It was found that under the same blast power, smaller relative axial and transverse distances against the square pin-fin would generate better Nu, and the relation between fRe3 and Nu is only correlated with the interval between the pin-fin.

目　　錄

頁次
中文摘要 Ⅰ
英文摘要 Ⅱ
致謝 Ⅲ
目錄 Ⅳ
表目錄 Ⅵ
圖目錄 Ⅶ
符號說明 IV
第一章 緒論 1
　　1-1 研究動機與背景 1
　　1-2 熱傳遞機制 3
　　1-3 文獻回顧 4
1-3-1 鰭片在槽道中研究之應用 4
1-3-2 液晶在熱傳研究之應用 10
　　1-4 研究目標 14
1-5 研究架構 15
第二章 理論分析 17
　　2-1 實驗理論 17
　　2-2 液晶定義與應用 18
第三章 實驗方法 21
　　3-1 實驗步驟 21
3-2 實驗設備 22
　　 3-2-1 熱空氣供應系統 22
3-2-2 實驗測試段 22
3-2-3 方形柱狀鰭片測試段 23
3-2-4 液晶 23
3-2-5 影像擷取系統 24
3-2-6 影像分析程序 25
3-2-7 溫度擷取系統 25
3-2-8 數據擷取器 26
3-3 實驗操作流程 27
3-4 數據整理 28
3-5 不準確度分析 29
第四章 結果與討論 48
　　4-1 不同相對間距對平均紐塞數之影響 50
　　4-2 不同相對間距對壓降之影響 52
　　4-3 雷諾數對摩擦係數之影響 53
4-4 雷諾數對平均紐塞數之影響 54
第五章 結論與未來展望 100
　　5-1 本研究之重要結論 100
　　5-2 未來展望 102
參考文獻 104
附錄A 110
附錄B 111
附錄C 112
附錄D 113
作者簡歷 117

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