| Summary: | 碩士 === 臺灣大學 === 機械工程學研究所 === 95 === This research focuses on the parametric analysis of a polymer wick for the heat transfer performance of loop heat pipe. The parameters on the wick structure, including pore radius, porosity, and permeability. It is difficult to predict and control well in the manufacturing method of sintered metal powder. Then, small form factor LHP causes the problem of the heat transpiration easily. Therefore, polystyrene which is low thermal conductivity coefficient is chosen as the material and is fabricated by salt leaching. Adjusting the size of sodium chloride powder and its percentage in the polystyrene material, it could not only control the pore radius and porosity efficiently, but also be discussed the relationship of the parameters deeply among them. The results of the test show that the pore size parameter lies in the desired range, and the porosity is able to be controlled within 1.65% MAE. With repeatedly tests, a formula between permeability and porosity expresses as Kw=6.24×10-23ε6.87. Furthermore, this would promote both the LHP design and the prediction of heat transfer.
What the results of the test reveal when the smaller the thinness and pore radius are, and the bigger the porosity is , the heat transfer would be much better. Hence, a wick structure with the thinness of 1.5mm, the pore radius of 0~20 micron, the porosity of 80%, and the permeability of 9.2×10-12m2 is installed into a LHP system to carry out the performance. The capacity of heat transfer in LHP with polymer wick structure approaches 300W, the thermal resistant is 0.25℃/W under the evaporator temperature of 85℃. The same result could be discovered within sintered metal powder method. In short, polymer wick structure, comparing with metal wick structure, has some advantages in the characteristics in its production, such as low cost, easily controllable, perfect processing, and so forth. Moreover, these merits would promote the potential of LHP as much as possible.
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