Number：

05_02鄭澤明

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Name：

Tzer-Ming Jeng

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Experimental study of heat transfer characteristics in a 180-deg round turned channel with discrete aluminum-foam blocks

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Keywords：Heat transfer 180-Deg turned channel Aluminum-foam blocks

Abstract：This work wxperimentally investigated the local and average heat transfer characteristics in a 180-deg round turned channel with discrete aluminum-foam blocks.The air was used as coolant.Several alumi-num-foam blocks(0.90 porosity and 10 PPI pore density)were installed discretely in the 180-deg round turnd channel with the square cross section.Total four kinds of test section,with various arrangernents of aluminum-foam,were employed.The result indicate that the local peak values of the Nusselt numbers would appear at the positions of the aluminum-foam blocks.The local Nusselt numbers of the upper and bottom walls were higher than those of the side walls in the straight ducts;while the local Nusselt numbers of the outer side wall were higher than those of others walls in the turn.The local Nus-selt numbers of the inner side wall generally were the lowest values.Besides,the average Nusselt num-ber of the present porous channels were 74-140%higher than that of the empty channel,suggesting the significant heat transfer enhancement of the aluminum-foam blocks.Furthermore,in the straight duct,the staggered aluminum-foam blocks could promote heat transfer more efficiently than the symmetric aluminum-foam blocks did.The average Nusselt numbers of Model 3 and Model 4 (the whole channel filled with aluminum-foam blocks)were 20-30%higher than those of Model 1 and Model 2 (only straight ducts filled with aluminum-foam blocks).It is noteworthy that the pressure drops of Model 1 and Model 3 test sections(vertically symmetric configuration)are much higher than those of Model 2 and Model 4 test sections(vertically staggered configuration)by 180-280%

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