本論文總共分兩個部分，第一部分使用吸入型開放式風洞對圓形及橢圓形鰭片鰭管式熱交換之測試本體(其中橢圓管長短軸比為2.5、2.8及3.1)做熱液動性能分析，分別找出其熱傳因子j和壓降因子f，並找出其對Re之關係圖相比較。第二部分在開發一套空氣冷凝器之電腦輔助分析及設計軟體。
　　熱交器熱液動性能分析部分：影響鰭管式熱交換器之性能除了熱交換器本體之鰭片間距，鰭片材質等之外，鰭片型式亦是一個重要因素。本論文除了改變熱交換器鰭片長短軸比及管陣的排列方式外，另外測試了總共有兩種不同鰭片形式的熱交換器。從實驗結果看出：圓形鳍片比橢圓鳍片的熱傳效果較好外，其中橢圓鳍片長短軸比越近似圓形熱傳效果越好(2.5 > 2.83 > 3.1)。由實驗結果發現在入口風速1~6 m/s下，當空氣通過時，空氣側熱傳係數會隨著正向速度的增加而增加，其中交錯排列式鰭片鰭管熱交換器的熱傳因子j值比對齊排列式大10~26％。
　　熱交換器電腦輔助分析及設計軟體部分：本論文建立了一套分析及設計軟體，使用者經過簡單的操作，可以分析已知尺寸及性質，也可以由所需的操作條件設計出最適合的熱交換器之尺寸及性能。

　This study was focused on the investigation of air-cooled condensers, including two main parts as expressed in the following.

　First, the open wind tunnel was used to study the circular and oval fin air-cooled condensers experimentally. These air-cooled condensers involved the ratios (Ar) of its minor axis to major axis are 1, 2.5, 2.8, and 3.1, respectively. The relationships between the Colburn factor j and the Reynolds number/the ratio (Ar) were presented. Moreover, the relationships between the friction factor and the Reynolds number/the ratio (Ar) were also presented.

　Second, there is an interactive computer-aided design software for the air-cooled condensers was developed. It has been written by Visual Basic 6.0 and can be run in any personal computer. The software has the following two functions:
(1) Predicting the performance of a radiator when the dimensions are given.
(2) Determining the necessary size of a radiator when given the required performance.

At last, the experimental results were demonstrated by the computer-aided design software. The results show that the efficiency of circular air-cooled condenser is better than oval air-cooled condenser.

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