Heat Transfer of Jet Impingement Cooling with Porous Medium

• Main Authors: Sung, Hsiang-Chu, 宋翔駒
• Other Authors: Liu, Yao-Hsein
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/08649717839664445050

碩士 === 國立交通大學 === 機械工程系所 === 105 === Jet Impingement Cooling with porous medium was experimentally investigated using transient liquid crystal technique. In this experiment, porous medium was put inside the impingement channel. This jet impingement experiment was conducted using an orifice plate with 4×12 circular holes . The diameter of the hole is 0.5cm, and the jet-to-jet distance is 4 times the hole diameter. With the target-to-orifice distance of 3 times the hole diameter, we investigated the jet Reynolds numbers of 2500, 5100 to 7700. We proposed and compared some test condition when the porous medium in the impingement channel. For example, the fill ratios of the porous medium are 1, 1/2 and 1/4. The experiment result shows that the porous medium in the impingement channel would make the jet flow dispersed and decrease the direct impingement of the jet flow on the target surface. And the heat transfer coefficient decrease more obviously when the fill ratio of the porous medium is increased or the porous media is located away from the orifice plate. When the porous medium partially covers the orifice plate, the air flow through the porous medium is hindered and the heat transfer coefficient is enhanced for the region without porous medium little. The higher heat transfer is found when the fill ratio of the porous medium is 1/4, but the total average Nusselt number is still 13% lower than the case without porous medium. The heat transfer with the fill ratio of 1 is the worst, and the total average Nusselt number is only 50% compared to the case without porous medium.