本研究利用計算流體力學軟體(Computational fluid dynamics，CFD)，模擬微結構落膜系統內之流力與熱傳特性。本研究採用FLUENT內之流體體積(Volume of fluid, VOF)模式，氣液界面間之熱傳面積與熱傳量則利用使用者定義函數(UDF，User defined function)計算。本研究限於層流範圍。
透過模擬建立了微結構落膜系統內部之特性分佈，包括速度、溫度、液膜與氣液界面熱傳量，並一一分析了系統條件參數之影響，包含表面張力、流體流量、液體黏度、液體密度、氣液溫度差、傾斜角度等。
分析結果顯示，雖然是在層流範圍內，因各項條件參數之不同，液膜波動程度與液膜厚度會有差異。針對液膜厚度與熱傳係數，比較模擬結果與理論值亦發現只有在液體雷諾數很小時較接近，當雷諾數增大時，偏差程度即會加大。因此，使用CFD模擬落膜系統以確實掌握其流力與熱傳特性是有必要的。

The thesis studies the hydrodynamics and heat transfer for a microstructure falling film device by CFD simulation using FLUENT. VOF (Volume of Fluid) model is adopted. For calculating gas-liquid interface heat transfer, a User Defined Functions (UDF) is developed. The study is limited to laminar flow region.
Grid independent study is conducted to determine the acceptable grid size. The model is used to simulate the profiles in the system, including velocity, pressure, phase and temperature. The model is further used to investigate the effects of system parameters, including surface tension, fluid flow rates, liquid density and viscosity, angle of inclination and temperature difference.  
Even for the laminar flow system, the simulation results indicate that the liquid film characteristics, such as the eddy, the wave, and the film thickness, are affected by the condition parameters studied. Regarding the film thickness and heat transfer coefficient, comparisons between simulated results and theoretical predictions also indicate discrepancies and the difference is larger for higher liquid Reynolds number. All these conclude that using CFD simulation to obtain the hydrodynamics and heat transfer characteristics for laminar falling film is necessary.

目錄
中文摘要	I
英文摘要	II
目錄	III
圖目錄	VI
表目錄	IX
第一章 前言	1
第二章 文獻回顧	4
第三章  計算流體力學模式建立	8
3.1 微結構落膜裝置	10
3.2 數學模式	12
3.2.1基本統制方程式	12
3.2.2流體體積(VOF)模式	12
3.2.2.1兩相界面計算	14
3.2.2.2表面張力（Surface tension）模式	15
3.3 求解方法	16
3.3.1 離散方法	16
3.3.2 速度-壓力耦合方法	17
3.3.3 邊界條件、收斂準則與疊代參數	17
3.4資料後處理	19
第四章  微結構落膜系統流場模擬	20
4.1網格建立	23
4.2 網格影響分析	29
4.2.1 網格設定	29
4.2.2速度分佈	33
4.2.3 液膜	37
4.3 基本個案特性分析	40
4.3.1速度	40
4.3.2壓力	43
4.3.3液膜	44
4.4參數影響分析	46
4.4.1 表面張力之影響	46
4.4.2液體密度之影響	54
4.4.3 液體黏度之影響	54
4.4.4 氣液相速度之影響	55
4.4.5傾斜角度之影響	59
4.5液膜厚度之總結	61
第五章 熱傳模擬	63
5.1基本個案熱傳特性	65
5.2條件參數影響分析	67
5.3熱傳係數之比較	73
第六章 結論與建議	76
符號說明	79
參考文獻	83
附錄	87
圖目錄
圖 1.1理想中程序強化型工廠	2
圖 2.1 水平管中兩相流流動模式	5
圖 2.2 垂直管中兩相流流動模式	5
圖 2.3 微落膜反應器	7
圖3.1 計算流體力學模擬運算流程	9
圖3.2 微結構落膜裝置	10
圖3.3幾何重建法	15
圖4.1 二維網格 (a)結構式四邊形(b)非結構式四邊形(c)非結構式三角形	24
圖4.2 系統示意圖與網格配置	25
圖4.3 微落膜系統上段網格	26
圖4.4 微落膜系統下段網格	26
圖4.5 微結構落膜系統之邊界條件	27
圖4.6 微落膜系統傾斜角度	28
圖4.7 CASEA系統上段網格 (a) CaseA-1 (b) CaseA-2 (c) CaseA-3	31
圖4.8 CASEB系統上段網格 (a) CaseB-1 (b) CaseB-2	32
圖4.9 微落膜系統截線位置	33
圖4.10 網格細化對速度之影響－垂直截線	35
圖4.11 網格細化對速度之影響－水平截線	36
圖4.12 無表面張力下液膜厚度之比較	37
圖4.13 有表面張力下液膜厚度之比較 (0.0722 N/m)	38
圖4.14 有表面張力下液膜之比較 (0.0722 N/m)	39
圖4.15 基本個案氣相區截線速度分佈	41
圖4.16 基本個案液相區截線速度分佈	41
圖4.17 基本個案全區速度分佈	42
圖4.18 基本個案液膜附近速度分佈 (a)上段 (b)中段 (c)下段	42
圖4.19 基本個案縱向截線壓力分佈	43
圖4.20 基本個案全區相分佈	44
圖4.21 基本個案近液膜區相分佈 (a)上段 (b)中段 (c)下段	45
圖4.22 不同表面張力個案之壓力分佈	47
圖4.23 不同表面張力個案之速度分佈	48
圖4.24 不同表面張力個案之液膜速度等高線分佈	49
圖4.25 不同表面張力個案之液膜	51
圖4.26 不同表面張力個案之液膜流動	52
圖4.27 不同表面張力個案之平均液膜厚度	53
圖4.28 不同液體密度個案之平均液膜厚度	54
圖4.29 不同液體黏度個案之液膜厚度	55
圖4.30 不同氣體流量個案之液膜流動	57
圖4.31 不同氣體流量個案之平均液膜厚度	58
圖4.32 不同液體流量個案之平均液膜厚度	59
圖4.33 不同傾斜角個案之液膜流動 (a) 90o  (b) 45o	60
圖4.34 理論計算與模擬之液膜厚度	62
圖5.1 氣相區截線溫度分佈	65
圖5.2 液相區截線溫度分佈	66
圖5.3 全區之等高溫度分佈	66
圖5.4 表面張力對熱傳量之影響	70
圖5.5 液體流量對熱傳量之影響	70
圖5.6 氣體流量對熱傳量之影響	71
圖5.7 氣相溫度對熱傳量之影響	71
圖5.8 氣相溫度400K個案之液膜分佈 (a)系統上段 (b)系統下段	72
圖5.9 熱傳係數之比較	75

 
表目錄
表3.1 微結構落膜裝置規格	11
表3.2 離散方法與鬆弛因子設定	17
表3.3 收斂準則	18
表3.4 時間步長設定	18
表4.1 模擬個案	21
表4.2 流體物性	22
表4.3 微結構落膜裝置規格	23
表4.4 網格無關化分析個案	30
表4.5 截線座標位置	34
表4.6 不同傾斜角個案之平均液膜厚度	59
表4.7 個案之平均液膜厚度	62
表5.1 熱傳模擬個案	64
表5.2 熱傳模擬結果	69
表5.3 氣液相之溫度差	74
表5.4 熱傳係數	74

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