本研究以逆算法搭配實驗溫度量測值，探討不同管徑、鰭片間距以及風速下，單管環狀鰭管式熱交換器之熱傳特性與流動特性。由於鰭片上的熱傳係數可能為不均勻分佈，故將鰭片劃分為數個小區域。之後，利用結合有限差分法、最小平方法及實驗溫度量測值之逆算法來預測鰭片之熱傳係數。為驗證其準確性，本文利用計算流體力學軟體FLUENT與本文逆算法所得之預測值做比較，並探討不同流動模式與網格劃分對於不同條件之物理模型的適用度。
結果顯示環狀圓鰭片之穩態熱傳係數應為位置函數而非常數。於自然對流中，加熱圓管上方存在一低速尾流區，鰭片上半部之平均熱傳係數較下半部為低。於混合對流中，加熱圓管下游存在一低速尾流區，鰭片下游區之平均熱傳係數較上游區為低。數值模擬結果顯示在自然對流及混合對流中分別為Zero-equation紊流模式及RNG紊流模式所得之結果較為準確，且總網格數會隨鰭片間距及風速的增加而上升。此外，流動模式選定及網格測試須與實驗量測值及逆算法預測值相互比較以求得較為準確之結果。模擬結果與本文之皆顯示增加鰭片間距及風速均能提高鰭片之散熱效果。

The present study applies the inverse method and computational fluid dynamics commercial software in conjunction with the experimental method to predict the heat transfer and fluid flow characteristics of annular finned tube heat exchangers. The effects of some physical parameters such as fin spacing, air velocity and tube diameter are examined. Due to the heat transfer coefficient on the fin is non-uniform, the fin is divided into several sub-regions. Later, the inverse method applied finite difference method in conjunction with the least-squares scheme and the experimental data to estimate the heat transfer coefficient on the fins.
The results shows that, there is a low velocity wake region at downstream of the tube. Therefore the heat transfer coefficient at the upstream region of the fin is higher than the downstream region of the fin. The increase of fin spacing and air velocity can improve the cooling effect of the fins. In natural convection, the heat transfer coefficient increases with the increase of the fin to tube diameter ratio. For a fixed air flow velocity, the higher the fins and the closer they are to one another, the lower the heat transfer coefficient on the fin is. Numerical simulation result obtained using zero-equation and RNG k-ε turbulence flow model is more accurate for natural convection and mixed convection respectively.

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