本文藉由模擬分析與實驗的方式相互對照並探討微米外環/毫米內管之同心雙圓管流道在等熱通量加熱下，內部共軛對流熱傳遞之特性。此研究初步階段藉由同心雙圓管物理模型與數學模型建構出其溫度場之數值模擬，經由比較不同尺寸參數之數值模擬結果後，選出幾組較具優勢之組合並以當前現有管材之規格為前提下，評估較為可行之組合後，選定以外徑為3mm，內徑為2.5mm之無氧銅圓管當作同心雙圓管流道之外管；以外徑為2mm，內徑為1.4mm之不鏽鋼圓管作為同心雙圓管流道之內管，實驗條件的設定上熱通量為9.19kW/m^2並固定流體入口溫度於 下，分別以總流量46.61、59.48及91.93cm^3/min，調控7組不同內/外環流量比進行實驗，工作流體的選擇上除了通入純水外，將調製體積分率 及 之氧化鋁-水奈米流體作為工作流體。
由實驗結果發現外環在使用體積百分濃度0.5%氧化鋁-水奈米流體在熱傳增益的表現不佳，但其熱傳效果依然優於以純水作為工作流體之單圓管架構。外環在使用體積百分濃度1.0%氧化鋁-水奈米流體下有最佳之熱傳效果，當總流量為46.61cm^3/min流量比為3.2的條件下，與單圓管通入純水相比之局部與平均熱傳增益分別為1.30以及1.69，總流量提升至91.93cm^3/min後，在相同流量比下，局部熱傳增益提升16.2%，同時與外環及內管工作流體皆為純水之結果相比後，在平均熱傳增益上提升2.4%。

In present study, conjugate forced convection heat transfer characteristics and efficacy of concurrent flows through a concentric double-tube duct of a micro-outer annulus and a mini-inner tube are researched by numerical simulation and experiment method. After comparing several simulation results under different dimensional parameters, such as the inner radius ratio of the outer tube to the inner tube, and the inner and outer radius ratio of the outer annulus, select some sets of more advantageous combinations as well as evaluate the more feasible combinations under the premise of the common pipe specifications. Therefore, the final combination of concentric double-tube has a oxygen-free tube which outer and inner diameters are 3.0mm and 2.5mm, respectively. The inner tube is a stainless tube which outer diameter is 2.0mm and inner diameter is 1.4mm. The condition setting of experiment including inlet temperature at 50 degree Celsius, heat flux 9.19kW/m^2 , three different total volumetric flow rates 46.61, 59.48, 91.93cm^3/min, respectively, seven different the volumetric flow rate ratios between the outer annulus as well as the inner tube, and three combinations of working fluid such as water and two different volumetric concentrations of Al2O3 nanofluid.
According to the results of experiment, although the heat transfer effectiveness of using volumetric concentrations 0.5% Al2O3 nanofluid through outer annular isn’t perform its advantage as expected, the heat transfer coefficient of this combination of working fluid is still better than the single tube construction which uses water as working fluid at same total volumetric flow rates. The volumetric concentration 1.0% Al2O3 nanofluid through outer annular has the best heat transfer effectiveness to single tube. The local and average heat transfer effectiveness is 1.30 and 1.69, respectively, at total volumetric flow rate 46.61cm^3/min, the volumetric flow rate ratio 3.2. When the total volumetric flow rate is up to 91.93 cm^3/min, the local heat transfer effectiveness increases 16.2%. In comparison with the combination of working fluid that both ducts use water, the average heat transfer effectiveness that using volumetric concentrations 1.0% Al2O3 nanofluid through outer annular improves 2.4%.

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