| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 94 === The microscale heat transfer phenomena of two-dimensional porous nanowires were investigated based on the microscopic heat transport theory. The phonon Boltzmann equation model was established to analyze the size effect on the thermal conductivity of porous nanowires. The effects of pore size, pore surface area and the distance between pores were emphasized in present study. Numerical analysis was conducted to estimate the thermal conductivity of porous silicon nanowires. The results showed that, unlike the bulk material, thermal conductivity of the wire did not remain constant when the phonon mean free paths were comparable with or even larger than the diameter of wire. The pore size, pore surface area and the distance between pores showed pronounced effects on the thermal conductivity of the wire. The pore size affects the probability of the collision of phonons with the pore boundary, which indicates that the thermal conductivity of the wire increases with decreasing pore size. The results could be used to direct the development of high-efficiency thermoelectric materials.
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