摘要
本篇論文主要為探討密閉矩形空腔在熱壁上新增矩形鰭片後的自然對流熱傳特性研究，以3D計算流體力學逆運算法的概念，由實驗量測空腔內數個特定溫度點，結合計算流體力學商業模擬軟體ANSYS Icepak 15.0模擬流場流動模式，並搭配最小平方法計算模型所需之未知熱源，找出和實驗數據相符合之流動模型，最後利用後處理系統呈現模擬結果，並與實驗做研究討論。
吾人在實驗中作了以下嘗試:不同鰭片數量、不同鰭片材質、改變空腔高度和改變熱源溫度，結合半經驗公式計算空腔內之Ra數和("Nu" ) ̅數，且有固定趨勢，並發現以下幾點:(1)在加入鰭片於熱壁上後和無鰭片模型相比，熱傳效率皆有所提升；(2)七片鰭片模型和三片鰭片模型相比，雖然流動性較差、Ra數也較低，但因為導熱表面積較大，整體熱傳效率還是比三片鰭片模型稍高；(3)在使用兩種導熱性有明顯差距之鰭片材質時，熱傳效率為AISI 304表現較好，但差距非常有限；(4)將空腔高度提高後，Bénard Cell的尺寸會隨之增加且更完整，Ra數和("Nu" ) ̅數也有上升情形；(5)將熱壁溫度提高後，整體流場流動速度增加，對整體熱傳效率也有所提升。

In order to investigate the heat transfer characteristics of natural convection in a closed rectangular cavity with a new rectangular fin on the hot wall, this paper uses the concept of 3D CFD inverse operation method to measure several specific temperature points in the cavity by experiment. The unknown heat source required by the least square method is used to find the flow model which is consistent with the experimental data. We made the following attempt in the experiments, different number of fins, fin material, change the cavity height and change the heat source temperature, combining with the semi-empirical formula for calculating the cavity of Ra number and Nu number, and found the following points: (1) after adding fins on hot wall compared to no fins model, heat transfer efficiency is improved. (2) Compared with the three-fin model, the seven-fin model has lower fluidity and Ra number, but the overall heat transfer efficiency is slightly higher than that of the three-fin model because of the larger thermal conductivity surface area. (3) AISI 304 has a better performance when using two fin materials with significant difference in thermal conductivity, but the difference is very limited. (4) When the cavity height is increased, the size of Bénard cell will increase and become more complete, and the Ra number and Nu number will also increase; (5) When the temperature of hot wall is increased, the flow velocity of the overall flow field is increased, and the overall heat transfer efficiency is also improved.

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