熱交換器已被廣泛的應用於各工業上，其熱對流係數更直接的反映出其散熱之效果，因此本文設計了幾種鰭管式熱交換器模組，利用反算法中的急遽遞減法(Steepest Descent Method)，並結合熱流計算軟體CFX4.4，求解鰭管式熱交換器鰭片暫態表面熱傳係數之三維逆向熱傳問題(Inverse Heat Transfer Problem)。
　　在實際之工程問題上，常有許多物理量無法藉由直接量測或計算之方法獲得其值，因此為了求得這些物理量，往往必須藉由其他可量測之資料來反求之，這類的問題稱之為逆向或反算問題(Inverse Problem)。
　　在本文第二章中針對鰭管式熱交換器鰭片進行熱傳分析之數值模擬，利用熱流套裝軟體CFX4.4來處理物理幾何模型，利用其強大的熱流計算能力來計算所需之正解部分，接著和反算程式串聯起來，以對鰭片上熱對流係數之預測，並討論溫度量測誤差對熱對流係數預測值準確度的影響。
在本文第三章的部分則實際經由實驗，利用紅外線熱像儀量測鰭片上的溫度，分別對對齊式鰭片(In-line)和交錯式鰭片(Staggered)各別在不同的風速及鰭片間距下，根據急遽遞減法來預測出鰭片上的穩態熱對流係數，並做分析與探討。

　　The local time-dependent surface heat transfer coefficients for plate finned-tube heat exchangers are determined in a three-dimensional inverse heat conduction problem. The inverse algorithm utilizing the Steepest Descent Method (SDM) and a general purpose commercial code CFX4.4 is applied successfully in this study in accordance with the simulated measured temperature distributions on fin surface by infrared thermography. Two different heat transfer coefficients for staggered as well as in-line tube arrangements with different measurement errors are to be estimated. Results of numerical simulation show that the reliable estimated heat transfer coefficients can be obtain by using this inverse algorithm.

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