本研究以實驗觀察迴路式熱虹吸的冷凝器，分別在不同熱負載、傾斜角度與親、疏水表面時內部的冷凝現象並計算其冷凝熱阻，進而作為迴路式熱虹吸的冷凝器的設計參考。實驗中蒸發器採用多層銅網毛細結構並作親水處理以保持薄膜蒸發模式，可降低蒸發熱阻並可避免蒸發器內部沸騰震盪造成的不穩定性。冷凝器部分採用玻璃水冷套作冷卻，首先採用玻璃冷凝管進行可視化實驗，未特殊處理的玻璃管的靜態接觸角為18度，做疏水處理後為86度，觀察到親水玻璃管內部為膜式凝結，而疏水玻璃管可觀察到水珠的成長、合併與掃除等滴式凝結之特徵；再利用銅管作熱阻定量分析，將六支熱電偶分成三對用絕熱膠帶密貼於銅管外壁上不同縱向位置，以量測出管外壁溫度並據以計算冷凝熱阻。做親水處理之銅管的靜態接觸角為0度，做疏水處理後為116度。在親水銅管各傾斜角度皆發現下游處因累積冷凝水，且蒸汽剪力效果減弱而產生較厚之液膜，另外當親水管傾斜擺放時，可觀察到管壁上下兩側因液膜分布不均而存在溫差，其中當親水管傾斜45度時具有最低之液膜熱阻。疏水銅管在各個傾斜角度時熱阻值差異不大，且管壁各點皆接近均溫。整體而言，蒸發器如採用充分親水的毛細結構並形成薄膜蒸發，可具較低蒸發熱阻；冷凝管採用疏水表面的冷凝熱阻會低於親水表面，冷凝管呈約45度傾斜角具較低冷凝熱阻。

This study experimentally investigated the tube condenser of a loop thermosyphon by visualization and condenser resistance measurements under different heat loads, inclination angles, inner surface wettabilities of the condenser tube. These results can be used for the condenser design. In the evaporator, the thin-film evaporation was managed by adopting multi-layer copper mesh wick with hydrophilic treatment. This led to low evaporator resistances and stable evaporation without intense oscillation due to boiling in the evaporator. Visualization experiments were first conducted for glass condenser tubes. The static contact angle of a sessile water drop on the untreated glass was 18°, while it was 86° after a hydrophobic surface treatment. Film condensation was observed in the untreated glass tube, while dropwise condensation was observed with a cyclic process of rapid drop growth from very small size, coalescence of drops until a threshold size, drop falling to sweep off the drops below, and the regrowth from very small drops. Quantitative measurements of the condenser resistances were conducted for copper condensation tubes, with three pairs of thermocouples tightly attached to the outer tube wall by plastic insulation belts to measure the longitudinal temperature distributions along the outer wall. The condenser resistances were estimated by dividing the temperature differences between the condenser’s inlet vapor temperature and the outer wall temperatures by the heat load. The static contact angle of a sessile water drop was 0° and 116° on the copper tube with hydrophilic and hydrophobic treatment, respectively. Under various inclination angles, slightly lowered temperatures by thicker water films were measured near the lower end of the condenser, due to water accumulation and weakened or reversed vapor shear stress. Under inclination, the wall temperatures were slightly lower at the lower side of the tube due to the thicker water films. For the hydrophobic tube, the wall temperatures were nearly uniform, irrespective of the inclination angle. The condenser resistances were also similar for different inclination angles. In summary, an evaporator operating with thin-film evaporation provides lower evaporator resistances; hydrophobic condenser tubes leads to lower condenser resistances than hydrophilic tubes; and an inclination angle of about 45° yields lowest condenser resistances.

摘要 I
Abstract II
目錄 III
圖表目錄 V
符號表 VIII
第一章　緒論 1
1.1 研究背景 1
1.2 基本原理與文獻回顧 1
1.2.1 熱虹吸管原理 1
1.2.2 迴路式熱虹吸 2
1.3 影響管內冷凝性能之參數 5
1.4 研究目的 9
第二章　實驗設備與方法 17
2.1簡介 17
2.2 迴路式熱虹吸實驗 17
2.2.1實驗裝置 17
2.2.2實驗架構與配置 19
2.2.3實驗步驟 19
2.2.4實驗參數與實驗參數計算 21
第三章　實驗結果與討論 37
3.1冷凝過程 37
3.1.1親水管 37
3.1.2疏水管 39
3.2冷凝熱阻 40
3.2.1親水銅管冷凝熱阻 41
3.2.2疏水銅管冷凝熱阻 41
3.2.3相同傾斜角度之熱阻比較 42
3.2.4熱傳係數 42
3.3蒸發熱阻 42
3.4蒸發器與液體通道水位差ΔH 43
第四章　結論 57
參考文獻 59
附錄 冷凝管外壁溫度量測可靠性之數值檢驗 64

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