本文以有限差分法、最小平方法之逆算法搭配實驗溫度量測值來估算板鰭式熱沉垂直置放於開放環境中之熱傳係數與散熱量，並以CFD探討鰭片間之空氣溫度與流場速度分佈情形。由於鰭片上的熱傳係數並非均勻分佈，故於進行反算前，須將鰭片分割為N個小區域，而後把熱電偶安裝於小區域上以量測不同條件下之量測位置的溫度。再以商用軟體FLUENT搭配各種流動模式及適當格點數目求取各量測點之鰭片溫度、鰭片上之熱傳係數。除此之外，在相同條件下由各種流動模式所求得之數值結果將相互比較，以探討其差異性。為求得本研究較正確之熱傳及流體流動特性，選用適當的流動模式及網格格點數所求得之鰭片熱傳係數，須盡可能接近實驗溫度量測值及逆算結果，本文採用層流模式來作為本文的主要探討對象。結果顯示，流動模式及網格點數目對數值結果之影響不容忽視。本文以高低差排列，改變不同高低比例與鳍片間距，並以研究短鳍片之現象來比較其差異；發現鰭片上的平均熱傳係數會隨鰭片間距的增加而提高且同時隨著鰭片高低比的增加而減少。在本文實驗中，具有高低差排列鳍片，短鳍片的平均熱傳係數會較等高鳍片來得高。為了驗證所得結果之可靠性及可用性，所求得熱傳係數之逆算結果配合實驗與模擬來與先前結果或其他相關文獻之經驗式相比較。

In this study, finite difference method, least square method and inverse method combined with experimental temperature data are applied to consider the thermal performance of dual-height heat fins placed horizontally in open environment. CFD is also conducted to investigate the temperature and flow field of the apparatus. The effects of fin spacing, dual-height ratio and fin length are the comparisons we concern. Plate-fin heat sink is divided into several regions to calculate each thermal characteristic. Choosing appropriate flow model and number of grid points are based on the numerical and experimental analysis. The results shows that heat transfer coefficient increases with fin spacing S and it will reach a constant value when S reaches a certain value. However, the relation between heat transfer coefficient and dual-height ratio H* shows a line of negative slope, which has a similar trend with fin length L. The dual-height configuration of plate-fin heat sink subject to natural convection can bring about enhancement in thermal performance when the ratio decreases. In order to verify the reliability of predicted results of this research, the present study is also compared with the empirical correlations of other relevant literature.

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