| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 98 === 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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