在向下加熱池核沸騰系統中，上方的加熱面會阻礙汽泡的脫離，並使得汽泡脫離後沿著加熱表面滑行，使得其汽泡的移動機制與向上加熱時不同。過去的學者對於向下加熱的池核沸騰研究多半只研究熱通率、臨界熱通率與表面過熱度之關係，鮮少有對汽泡機制的研究。因此，本實驗旨在研究池核沸騰向下加熱時，在不同加熱面傾斜角的情況下，其熱通率、表面過熱度和汽泡相關參數之關係，並建立一套分析模型，目的即在於透過不同角度下的汽泡機制來分析熱傳能力。
本實驗使用銅做為加熱表面，以水作為工作流體，進行加熱面傾斜角為90°、120°、135°、150°、170°的沸騰實驗。在實驗水槽中以加熱棒先將槽內的水加熱至飽和溫度，並透過電源供應器供應電壓給加熱塊作為熱源，將不同的電壓下所對應的加熱塊溫度數據記錄下來，並推算其表面過熱度與熱通率。此外，透過高速攝影機將加熱表面的汽泡行為錄製下來，藉此量測汽泡相關參數。最後再以一套分析模型結合熱通率和汽泡數據進行後續分析。
經實驗後發現，當加熱面角度上升時，熱傳之能力會逐漸上升。此外，本研究所提出的分析模型低估實驗所得之數據，但其原因仍有待釐清。

In the downward heating system, the heating surface would stop the departure of bubbles. Bubbles would slide along the heating surface. Therefore, the mechanism of bubble movement was different from the upward heating system. In the past, most scholars have studied the relationship between heat flux, critical heat flux and wall superheat in the downward heating system. However, the studies of bubble dynamics were rare. In this study, the relationships between heat flux, wall superheat and some bubble parameters with different orientations of the heating surface were studied. Besides, the analysis model was created in order to analyze the heat transfer performance by the bubble mechanism in different heating orientations.
In this experiment, the copper was used as the heating surface. Water was used as the working fluid. The orientations of the heating surface included 90°, 120°, 135°, 150° and 170°. Water was heated to saturation temperature by heating rods. The power supply provided electric power to the heating block as the heat source. The temperature data of the heating block corresponding to different voltages were recorded, so the wall superheat and heat flux were calculated. Besides, the bubble behaviors were recorded by a high speed camera to measure the bubble parameters. Then the heat flux and bubble parameters were combined with the analysis model.
The results showed that the slope of the curve increased as the orientation angle increased. Besides, the heat flux calculated by the analysis model underestimated the experimental data. However, the reason hasn’t been found yet.

目錄
致謝 i
摘要 ii
Abstract iii
目錄 iv
圖目錄 vi
表目錄 ix
符號對照表 x
第一章 緒論 1
1.1 研究背景 1
1.2研究目的與動機 2
第二章 文獻回顧 4
2-1 加熱面角度相關實驗回顧 4
2-2經驗公式相關文獻回顧 26
第三章 實驗方法 34
3.1 實驗器材介紹 34
3.1.1 濾水系統 34
3.1.2 加熱系統 35
3.1.3 數據分析系統 41
3.2 實驗參數條件與流程 42
3.3實驗量測方法與誤差分析 47
3.3.1誤差分析方法 47
3.3.2溫度、熱通率與表面過熱度 47
3.3.3有效成核址線密度 49
3.3.4汽泡滑動速度 49
3.3.5汽泡直徑 50
3.3.6汽泡頻率 50
第四章 分析模型與結果討論 51
4.1沸騰模型 51
4.1.1 RPI model介紹 51
4.1.2 沸騰模型之改進 52
4.2 實驗之重複性 56
4.3 熱傳能力與沸騰曲線 58
4.4 汽泡機制 59
4.4.1 有效成核址線密度 60
4.4.2 汽泡滑動速度 60
4.4.3 汽泡直徑 63
4.4.4 汽泡頻率 69
4.5 分析模型和實驗數據之整合 74
第五章 結論 77
參考文獻 78

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