Numerical Analysis of Convection Heat Transfer in Micro Pin Finned Channels

• Main Authors: LAI, YIN-LIANG, 賴銀良
• Other Authors: CHIEN, LIANG-HAN
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/3k6cy3

碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系 === 107 === In this study, the computational fluid dynamics analysis software Ansys-Fluent was used to study single phase flow field, pressure and convective heat transfer performance of micro-channels having micro-cavity-fin by using dielectric fluid FC-72. The working fluid flows through a microchannel with a depth of 100 μm. The heating source area is 10×10 mm2. Circular bubble nucleation pores are located in the center of each fin, with a diameter of 60 μm. The saturation temperature of entrance is set at 35 and 50℃, the flow rate varies at 6, 12, 20 and 31 ml/min, and heat flux is fixed 4 W/cm2. The result shows that the main factor of heat transfer and pressure drop is the flow rate of working fluid. Contrarily, the differences of cavity mouth size is not significant. However, the influence of eddy current increased with increasing cavity mouth, and the greater eddy current hindered bubble nucleation. On the other hand, the smaller cavity mouth size resulted in minor eddy current, and therefore the bubbles are easier to generate. The simulation results are substituted in the bubble growth theories in the literature. According to the analysis of the effective bubble nucleation cavity, the radius of the cavity mouth will exceed the maximum effective radius at high flow rate except for the cavity with 5m cavity opening radius. The simulation results were also compared with the experimental results of the identical geometries of silicon micro-fin channels made by in micro-electrical machining technology, and reasonable agreement was found.