本研究之主題是針對廣泛使用於熱交換器之連續型平板散熱片。在熱交換器中，熱傳管的溫度隨著冷媒之流動而有變化，也造成了散熱片中不等根部溫度之條件。在不等根部溫度條件下，散熱片之溫度不僅僅受到外界空氣之影響，散熱片中之不等根部溫度也造成散熱片溫度分布的改變。
本文採用數值分析之中央差分法模擬散熱片在不等根部溫度條件下，不同熱對流係數與熱傳導係數下、散熱片尺寸、厚度等之二維溫度分布，並利用其溫度分布計算散熱片之平均散熱片效率。藉此以比較過去廣為被使用來估算散熱片之Schmidt法之差異。

其結果顯示，以Schmidt法來估計一連續型散熱片之散熱片效率，與實際之連續型平板散熱片溫度分布所計算之平均散熱片效率當在散熱片之等效半徑與熱傳管半徑比值大時兩種方式所計算之散熱片效率有極大之差異。此外，本研究並模擬當空氣進入熱交換器後，空氣與散熱片熱交換造成空氣溫度變化而影響散熱片之溫度分布等狀況，藉此探討散熱片採用逆向流與平行流排列所造成冷卻能力之差異。

The aim of my thesis is to study the temperature distribution and fin efficiency of the joined-fin whose tubes arranged inline. When the coolant running in a heat exchanger, the tubes in the same sheet of fin have different temperatures. Consequently, it causes the condition of different base (tube) temperatures in one sheet of fin. In this condition, the temperature distribution of the fin is influenced by the ambient temperature and different tubes temperatures.
The finite difference approximation was used to simulate the two-dimensional temperature distribution and to calculate mean fin efficiency under the different tubes temperatures condition. The simulation results were then compared with the Schmidt method, which is widely used to calculate the fin efficiency.

The result reveals that there is difference between Schmidt method and the method presented in the study when the equivalent radius over the radius of the tube is bigger. Besides, when air passed through the heat exchanger, the airflow heat exchanged with the extend surface, and it also caused the change of air temperature. In addition, the changes of the air temperature in the procedure were shown in the other simulation. The effects of the coolant running in parallel flow and counter flow were discussed.

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