| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 96 === The focus of this study is to solve the problem of high pressure drop when fluid passes through the vapor line in micro capillary pumped loop, MCPL. In this study, MEMS technology is used to fabricate thermal bubble pump that has constant heat flux to investigate the mechanism of driving bubbles. By surface modification, the micro channel has hydrophilic and hydrophobic regions. The distribution of surface free energy will make bubbles move without external force.
Because the TaAl alloy can’t stand the high temperature (630℃) of thermal fusion bonding, this study carries out a low temperature (180℃) bonding method. The device fabricates successfully by using PDMS as the intermediate layer between two substrates. In the experiment, observation of flow visualization is used to investigate the bubble phenomenon including nucleation, growth, and movement. Effects of different heater position with the same heat flux and different heat fluxes in the same position were compared. Furthermore, the effect of channel width is discussed. The result reveals that when channel width is 500micron, heater in the geometry change of channel (h2) is the best position to observe bubbles move or not. When 10V (93mW) is applied to h2, bubble will grow to 1000micron length and reach thermal equilibrium. However, at this state the bubble only oscillates. When channel width reduce to 100micron and 6.2V (76mW) is applied to the heater, the bubble will move forward continuously and have the effect of heat transfer.
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