本研究主要目的為探討固液界面之間親和力的大小與表面粗糙度對於過渡層的厚度與附近熱擴散係數的影響。不同液體對固體有不同的親和力，固體表面的粗糙度也會影響液體對固體的親和力，因此過渡層的厚度與熱傳行為也會不一樣。
本實驗使用正十四烷與水兩種液體，粗糙度不同的銅片當作固體，並以溫度震盪法來量測固體表面附近的之熱擴散係數。利用步階到達次微米等級之步進馬達控制熱電偶與固體的間距；壓克力構成盛裝液體用的容器；製冷片(Peltier)提供一個從底部吸收熱量的途徑來避免液體密度不均勻而發生的對流情況。
由於量測數據的帶寬無法直接得到熱擴散係數，必須透過微擾法。我們提出一個熱擴散係數函數，加入常數γ做為整體評估固液親和力的常數做為一個微擾項，透過數值迭代來得到誤差最小的相位差與振幅比函數，結果皆能落在量測數據之內，代表數值迭代的結果為合理的。固液親合性較好，表面形貌較粗糙，則γ越大，表示過渡層範圍越大；固液親合性越差，表面形貌較平滑，則γ越小，代表過渡層範圍越小。

This study investigates the effects of surface roughness and interfacial behavior on thickness of transition layer and the thermal diffusivity. Different liquids have different affinity for the solid. Surface roughness of solids also affects the affinity between the liquid and solid and leads to that thickness and behavior of the transition layer would not be the same.
We use two kinds of liquid which is n-tetradecane and water, and two copper with different roughness as substrates and measures the thermal diffusivity by oscillation temperature method. Stepping motor which has sub-micro step controls the distance between thermocouples and the substrate. Container for liquids consists of acrylic and other insulation material. Peltier absorbs heat from the bottom to provide a way to avoid the convection because of liquid uneven density.
We get the thermal diffusivity by solving perturbation because the measuring data has small range. Using a new thermal diffusivity function as a perturbation term, the numerical iteration has nice match in the range of data, and provides us a constant, γ, to evaluate the liquid-solid affinity. It has the better affinity and thicker transition layer with larger γ, and poor affinity and thinner transition layer with smaller γ.

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