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鄭澤明30

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鄭澤明、曾憲中、羅婷伊

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冷卻流體方向效應對多孔性介質槽道熱流特徵之分析

Analysis of Coolant Fluid Orientation on Thermo-Fluidic Characteristics of the Porous Channel

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建國科大學報, 33(2), pp. 77-90, 2014.

Keywords：堆疊銅粒密實床、90度轉彎流、槽寬=粒徑比例、熱傳遞。

Abstract：This study experimentally investigated the fluid flow and heat transfer in the brass-beads-packed-bed channel with the 90-deg turned flow and the small ratio of channel width to bead diameter.The diameters(d) of brass beads were 2 mm,4 mm and 6 mm.The corresponding ratios(Dh/d) of channel width to bead diameter were 7.5,3.75 and 2.5.The other parameters included the heated surface and Reynolds number.The results indicate that the friction factor (Cf)increased with decreasing the bead diameter.Besides,the Cf value of the straight-flow system were slightly higher than those of the 90-deg-turned-flow system at the cases of d=2 mm,they were similar for the cases of d=4mm and 6mm.When the Dh/d was small and the Re was large,the local Nusselt number (Nu)firstly increased along the streamwise direction and then decreased until the exit.Furthermore,the average Nusselt number (Nu) of d=6mm(Dh/d=2.5)was maximum,and that of d=4mm (Dh/d=3.75)was minimum.The Nu of d=2mm was generally medium.The Nu for the straight-flow system was generally higher than that for the 90-deg-turned-flow system,especially for the shorter length of the channel being analyzed.However,the effect of the heated surface on the heat transfer was insignificant.

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