| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 105 === This thesis is conducted with the study on the heat transfer performance of gravity heat pipes with anodized aluminum oxide nano-surface. The main purpose is to experimentally investigate the influences of aluminum oxide nanotube length and diameter on the temperature distribution, thermal resistance, and dryout phenomenon of gravity heat pipes under different thermal powers input. First, the anodic oxidation method is used to generate anodic aluminum nanotubes on the inner wall-surface of the evaporation section of aluminum gravity heat pipes. Then, nano-surfaces with different nanotube lengths and diameters are obtained by controlling the anodic oxidation time and voltage. Further, the shape of those nanotubes are observed by using the FE-SEM. Finally, these gravity heat pipes are placed in a thermal test system so as to measure the temperature, calculate the thermal resistance, and record the dryout phenomenon.
The results show that the increase in the anodic oxidation time could increase the length of an anodized aluminum nanotube under a particular thermal power input. Increasing the nanotube length reduces the temperature change between the evaporation section and condensation section and the thermal resistance; moreover, the dryout phenomenon is delayed. In addition, the increase in the anodic oxidation voltage could increase the nanotube diameter. Increasing the nanotube diameter also reduces the temperature change between the evaporation section and condensation section and the thermal resistance; however, the increase in diameter does not seem to affect the dryout phenomenon. In summary, if the anodic oxidation treatment is applied to the inner wall surface of the evaporation section of a gravity heat pipe, the heat transfer performance could be obviously improved. The heat transfer performance of the gravity heat pipe could further be enhanced by increasing the anodic oxidation time and voltage.
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