近年來，隨著全球能源需求不斷的增加以及化石能源儲備的日漸枯竭，如何更有效率地運用有限化石能源是全球面臨的共同課題。目前使用的燃料大多都通過熱能轉換供社會或工業使用，因此提升熱交換器的熱傳性能是提升能源利用效率的重要方式之一。本研究在前人最佳設計之具翼型擾流器之蛇形方管熱交換器基礎上，進一步優化擾流器擺放方式以增益其熱傳，並使用紅外線熱像儀(Infrared Thermography，簡稱IRT)、壓力傳感器以及質點影像測速儀(Particle Image Velocimetry，簡稱PIV)量測方管中局部溫度分布、壓力損失以及流場結構，以便探討流場結構如何影響熱傳增益與壓力損失。
本研究使用之翼形擾流器皆為3D列印所印製，按照與管道壁面貼合方式可分為I (側壁貼合)、II (上下壁面貼合)、III (下壁面貼合)三種類型，擺放方式為平行(Inline)或交錯(Staggered)。IRT熱傳與壓損量測實驗於雷諾數(𝑅𝑒)範圍5000 ≤ 𝑅𝑒 ≤ 20000內進行，PIV流場實驗於𝑅𝑒 =10000進行。由PIV與IRT實驗可以發現，於通道中轉彎區擺放三翼形擾流器I以及在出彎處擺放兩翼形擾流器II將使主流流體加速，讓第一通道的高熱傳得以延續到的二通道，通道整體紐塞數比((Nu) ̅/〖Nu〗_0)相較於前人提升6.4%。而雙排交錯擺放之翼形擾流器III，能大幅增強通道中二次流強度，增進冷熱流體混合。本研究使用雙排交錯擺放的翼形擾流器III，(Nu) ̅/〖Nu〗_0較前人提升46%，在壓損(f ̅/f0)區間45≤ f ̅/f0 ≤200內，雙排平行擺放的翼形擾流器III有最佳熱性能係數(Thermal Performance Factor，簡稱TPF)為1.45，優於先前文獻。而進一步探討平均流力因子與側向平均紐塞數比¯((Nu/〖Nu〗_0))_sp皮爾森相關性(Pearson Correlation)發現縱向速度¯((|V|/U_b))_CS、側向速度¯((|W|/U_b))_sp與無因次渦度¯((|ω|D_H/U_b))_CS三流力因子與其有較高的相關程度，相關係數(R)分別為0.85、0.84與0.83。最後本研究整合前人平滑管道與機翼型擾流器及本研究實驗數據，提出兩個較前人適用範圍更為廣泛之¯((Nu/〖Nu〗_0))_sp經驗公式，此公式亦將為未來熱傳機器學習提供數據基礎。

In recent years, due to the growing demand for energy and depletion of fossil fuels, the efficient use of the limited fossil fuels becomes a challenge facing our planet. As most fuels for residential and industrial applications nowadays are utilized in the way of thermal energy, increasing the thermal performance of heat exchangers is one of the most important methods to improve the efficiency of energy use. This research aims to enhance the thermal performance of previous wing-shaped turbulators in a square serpentine channel with different turbulator arrangements. To explore the effects of turbulent flow structures on heat transfer and pressure loss, the Infrared Thermography (IRT), pressure sensors, and Particle Image Velocimetry (PIV) are applied to measure the local temperature distributions, pressure loss and flow fields, respectively.
In this study, according to the wall attachment methods the adopted turbulators fabricated by the 3D printing technology can be categorized into three types: I (attached to the sidewalls), II (attached to the top and bottom walls) and III (attached to the bottom wall). The arrangement of the turbulators inside the channel is either inline or staggered. In the IRT and pressure loss experiments, the Reynolds Number (𝑅𝑒) is in the range of 5000 ≤ 𝑅𝑒 ≤ 20000 whereas in the PIV experiments it is fixed at 𝑅𝑒 =10000. From the IRT and PIV experiments, it is observed that the installation of three type I and two type II wing-shaped turbulators in the turn region of the two pass channel accelerates the main flow, leading to the continuation of high heat transfer regions from the first pass to the second pass. Compared with previous data, the overall Nusselt number ratio ((Nu) ̅/〖Nu〗_0) increases 6.4%. In addition, the two-row staggered arrangement of type III wing-shaped turbulators significantly augments the strength of secondary flows in the channel, thus promoting the mixing of cold and hot fluids. The (Nu) ̅/〖Nu〗_0 in the two-row staggered arrangement is 46% higher than that of previous single-row arrangement. In the range of 45≤ f ̅/f0 (friction factor ratio) ≤200, the two-row inline arrangement exhbits the best Thermal Performance Factor (TPF) of 1.45 superior to the previous highest value. Furthermore, the correlations between the mean flow parameters and spanwise-averaged local Nusselt number¯((Nu/〖Nu〗_0))_sp are explored by the Pearson correlation. The spanwise-averaged mean transverse velocity¯((|V|/U_b))_CS, spanwise velocity ¯((|W|/U_b))_sp, and the cross-sectional averaged mean vorticity ¯((|ω|D_H/U_b))_CS are discovered to have a high correlation with ¯((Nu/〖Nu〗_0))_sp, with the respective correlation coefficient R equal to 0.85, 0.84, 0.83. Lastly, by combing the thermal-fluidic data of the present and previous designs including the smooth channel and channel with wing-shaped turbulators, two empirical heat transfer formulas with a wider applicable range are proposed, which provides database for using the machine learning program of heat transfer in the future work.

摘要 i
Abstract iii
致謝 v
目錄 vi
表目錄 viii
圖目錄 ix
符號說明 xii
第一章 緒論 1
1-1前言 1
1-2文獻回顧 2
1-2-1擾流器類型 2
1-2-2導葉 9
1-2-3擾流器擺放 12
1-3研究目的 13
第二章 實驗系統與方法 27
2-1 實驗管道與擾流器模型 27
2-2流場量測系統 28
2-2-1視蹤粒子產生裝置 28
2-2-2雷射光學照明系統 29
2-2-3影像擷取系統 29
2-2-4影像分析程序 30
2-3熱傳量測系統 30
2-3-1紅外線熱像儀 30
2-3-2電阻溫度感測器系統 31
2-4實驗條件 31
2-5熱傳實驗數據處理 31
2-6實驗誤差分析 33
第三章 實驗結果與討論 44
3-1實驗技術驗證 44
3-2轉彎區擾流器擺放方式之影響 44
3-2-1流場實驗結果 44
3-2-2熱傳實驗結果 46
3-3直通道擾流器擺放方式之影響 49
3-3-1 流場實驗結果 49
3-3-2 熱傳實驗結果 51
3-3-3 紐塞數與流力因子相關性分析 53
3-3-4 迴歸分析 56
第四章 結論與未來建議 81
4-1結論 81
4-2重要研究成果 82
4-3未來建議 82
附錄A 熱傳上下壁面對稱性(翼形擾流器III) 84
附錄B 論文口試之補充答辯 85
參考文獻 88

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