Number：

04_01曾憲中

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Name：

Sheng-Chung Tzeng

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Paper name：

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

Name of activity：

International Journal of Heat and Mass Transfer

Keywords： Heat transfer 180-Deg turned channel Aluminu,-foam blocks

Abstract：This word experimentally investigated the local and average heat transfer characteristics in a180-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 turned channel with the square cross section.Total four kinds of test section ,with various arrangements of aluminum-foam blocks.were employed.The results 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-bers 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 1and 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(vertically staggered configuration)by 180-280%

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