Number： 01099017 Download Name： Shng-Chung Tzeng Titles： Professor Author： Tzer-Ming Jeng and Shng-Chung Tzeng Paper name： Heat transfer of the metallic porous heat sink in a rectangular channel with top-bypass clearance Name of activity： Jouenal of the Chinese Society of Mechanical Engineers(SCI) Keywords：hcat transfcr, mctallic porous heat sink, top-bypass Abstract： This paper measured the top-bypass effect on heat transfer of metallic porous heat sinks in a rectangular channel. Four heat sinks (5x5, 9x9 Al pin-fin, 10 and 40 PPI Al-foam) were tested. Thecoolant was air Varied parameters were Reynolds number (491≦Re≦3893) and relative top-bypass clearance (0≦C/Hf≦,l.28). The results indicate that the9x9 pin fins had the highest average Nusselt number(Nu), the 5x5 pin fins had the lowest Na, and the Nu of Al foams were medium. Besides, the empirical formula of No in terms of Re and C/Hf were obtained by the pressure-drop balance principle and all the experimental data. Finally, using the empirical formula of Nu, we found that Nu decreased 0.5-0.6 times of Nu0 when C/Hf increased from 0 to 0.6, but Nu only decreased 0.11-0.13 times of Nu0 when C/Hf, increased from 0.6 to 1.2, wherein Nu0 displays the average Nusselt number without bypass effect.