本文主要是以有限差分法（Finite difference method）的數值方法，並配合最小平方法（Least-squares scheme）及溫度量測值來預測雙管板鰭管式熱交換器之矩形垂直鰭片上的平均熱傳係數（Average heat transfer coefficient）和鰭片效率（Fin efficiency）。從先前的研究可以發現，鰭片上的熱傳係數是非常不均勻的。為了利用鰭片上的溫度實驗値來預測鰭片上的熱傳係數及鰭片效率，因此將鰭片分割成數個小區塊。本文將以自行設計的板鰭雙管式熱交換器之鰭片組，並配合相關實驗設備以量取於穩態下之鰭片溫度與管壁溫度。根據這些數據，再配合數值反算法來估算鰭片上之熱傳係數。結果顯示，於自然對流（Free convection）之環境下，若鰭片間距（Fin spacing）大於0.035m時，鰭片上之平均熱傳係數將會漸趨近於一固定值；於混合對流（Mixed convection）之環境下，迎風面的熱傳係數會大於背風面的熱傳係數。所估算之平均熱傳係數將與參考文獻內之經驗公式相比較，以驗證本文反算方法之準確性及先前經驗公式之合理性。

The present study applies the finite difference method in conjunction with the least-squares scheme and the experimental temperature data to predict the average convection heat transfer coefficient and the fin efficiency on the rectangular vertical fin of two tubes plate finned-tube heat exchangers. The heat transfer coefficient on this rectangular fin is very non-uniform. Thus the whole plate fin is divided into several sub-fin regions in order to predict the average heat transfer coefficient and the fin efficiency on the fin from the knowledge of the experimental fin temperature. A double tube plate finn heat exchanger and some relative experimental equipments and set up in order to measure the fin temperature. The heat transfer coefficient can be predicted by using the present inverse scheme according to the temperature measurements on the fin. The results show that the average heat transfer coefficient will approach a fixed value under the free convection provided the fin spacing is larger than 0.035m, the heat transfer coefficient on the upstream region of the fin can be markedly higher than that on the downstream region in mixed convection. However, In order to evidence the accuracy of the present inverse scheme and the reliability of the some experimental formulas, a comparison of the average heat transfer coefficient between the present predicted results and the previous results in references is made.

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