本文擬以逆向數值方法配合實驗溫度數據來得出管式熱交換器於空腔中內的三維自然對流熱傳特性，並選取適當流動模型。空腔內有水平之兩支方管及一支矩形熱管，這兩支方管放置於矩形熱管上方，並且會隨著旋轉角度 θ 而改變位置。由於空腔內的流場在經過管式熱交換器時會產生複雜的流動且難以預測，為了瞭解其中的流動形式，本文利用逆向數值方法求得的溫度數據與實驗數據進行比較，選取方均根最小的流動模型來進行後續的分析，以期得到較正確的熱傳與流動特性。結果顯示於模擬中選用 RNG k-ε 紊流模型輔以增強型壁面處理和標準壁面函數較為符合實驗結果與趨勢，隨著管間距縮小，方管與矩形熱管的溫差會下降，而隨著旋轉角度改變，方管與熱邊界層接觸的面積增加，其與矩形熱管的溫差也會下降，由此可知，適當的旋轉角度及縮小管間距可以使空腔內的溫度分佈會更為平均。

In this study, the inverse numerical method and experimental temperature data are used to obtain the three-dimensional natural convection heat transfer characteristics of the tubed heat exchanger in the cavity, and an appropriate flow model is selected. There are two horizontal square tubes and one rectangular heat tube in the cavity. These two square tubes are placed above the rectangular heat tube and will change their positions with the rotation angle θ. Since the flow field in the cavity will generate complex flow and difficult to predict when passing through the tubed heat exchanger, in order to understand the flow in the cavity, the temperature data obtained by the inverse numerical method is compared with the experimental data, and select the flow model with the smallest root mean square for subsequent analysis, in order to obtain more accurate heat transfer and flow characteristics.
The results show that the selection of RNG k-ε turbulence model with enhanced wall treatment and standard wall function in the simulation is more in line with the experimental results and trends. As the distance between the square tube is reduced, the temperature difference between the square tube and the rectangular heat tube will decrease. With the change of the rotation angle, the contact area between the square tube and the thermal boundary layer increases, and the temperature difference between the square tube and the rectangular heat tube also decreases. From this, the temperature distribution in the cavity can be more uniform by appropriate rotation angle and reducing the distance between the square tube.

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