臺灣博碩士論文加值系統

本文以實驗溫度及逆算法搭配CFD軟體得出在三角熱管於空腔中之自然對流時的熱傳及流場特性，並探討鰭片高度 s 與旋轉角度 θ 對上述流場特性之影響，以期得到最佳散熱之形式，以及探討空腔之幾何形狀對Nu圖產生之影響。結果顯示於模擬中選用RNG k-ε紊流模型處理較為符合實驗結果與趨勢，並且當鰭片高度增加時與空腔之距離縮短阻礙了空氣間的對流，過高的鰭片高度則會影響三角管的散熱效率。以及三角管平均溫度則在θ=60°與θ=180°時，因浮力對流效應增強對流範圍變大，熱邊界層之高溫範圍也更廣，頂部空氣有著較強的渦流，熱傳效果較為理想。而當模型在s =30 mm及θ=180°時，總平均熱傳係數最高，代表在此時的熱傳效率最好，與最低效率的模型相比有了19.5%的提升。最後與相關文獻的比較可以得到，在特定瑞利數範圍中之Nusselt number圖，趨勢部分主要仍是受加熱管之幾何形狀所主導。

In this study, the experimental temperature and inverse algorithm are combined with CFD software to obtain the heat transfer and flow field characteristics of the triangular heat pipe during natural convection in the cavity. The effects of the fin height s and the rotation angle θ on the above flow field characteristics are discussed. In order to get the best form of heat dissipation. Discuss the effect of cavity geometry on Nu chart.
The results show that using the RNG k-ε turbulence model in the simulation is more in line with the experimental results and trends. When the height of the fins increases, the distance from the cavity is reduced, which hinders the convection between the air. Excessive fin height will affect the heat dissipation efficiency of the triangular tube. When the average temperature of the triangular tube is θ = 60° and θ = 180°, the convection range becomes larger due to the enhanced buoyant convection effect. The high temperature range of the thermal boundary layer is also wider. The top air has a strong vortex. The heat transfer effect is ideal. When the model is at s = 30 mm and θ = 180°, the overall average heat transfer coefficient is the highest. It represents the best heat transfer efficiency at this time, which is a 19.5% improvement compared to the least efficient model. Finally, a comparison with related literature can be obtained. The trend portion of the Nusselt number chart in a specific Rayleigh number range is still dominated by the geometry of the heating tube.

目錄
摘要 I
目錄 IX
誌謝 XI
表目錄 XII
圖目錄 XIII
符號說明 XV
第一章 緒論 1
1-1 研究背景 1
1-2 文獻回顧 2
1-3 研究目的與方法 4
1-4 本文架構 6
第二章 逆向數值方法 7
2-1 簡介 7
2-2 基本假設 8
2-3 流動模型之統御方程組 8
2-4 層流模式 9
2-5 紊流模式 10
2-5-1 零方程式模式 11
2-5-2 RNG k-ε紊流模式 12
2-5-3 SST k-ω紊流模型 18
2-6 最小平方法之理論分析 21
2-7 RMSE 分析 23
2-8 Nusselt number理論分析 24
第三章 計算流體力學軟體分析 25
3-1 簡介 25
3-2 幾何模型 27
3-3 邊界條件 29
3-4 網格品質 31
3-5 數值方法 33
3-6 收斂條件 34
3-7 網格測試 35
第四章 實驗架設與操作 37
4-1 簡介 37
4-2 實驗設備 38
4-2-1 矩形封閉空腔 38
4-2-2 管式熱交換器 40
4-2-3 溫度擷取系統 41
4-3 實驗步驟 43
第五章 結果與討論 45
5-1 簡介 45
5-2 流動模式之選定 46
5-3 鰭片高度變化之影響 48
5-4 旋轉角度之影響 49
5-5 相關文獻之比較 50
第六章 結論與建議 84
6-1 結論 84
6-2 建議與未來展望 85
參考文獻 87

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