Heat transfer characteristics in a channel fitted with zigzag-cut baffles

다국어 초록 (Multilingual Abstract)

The heat transfer characteristics were experimentally investigated in a wind channel with different types of cut baffles for heat transferaugmentation. The aim of using zigzag-cut baffles is to create 3D flow structure behind the baffles instead of transverse vortex flow leadingto enhance heat transfer. In this study, 4 types of baffles were examined; conventional baffle (Rectangular cross section with no cut),baffle with rectangular zigzag-cut, baffle with triangle zigzag-cut at 45 degree and at 90 degree. All of the baffles have the same height atH = 15 mm and flow blocking area. In the experiment, the row of seven baffles was attached on the inner surface of wind channel. Theeffects of pitch spacing length were also investigated at baffle pitch distance P/H = 4, 6 and 8 (H: Height of baffle). The experimentswere performed at constant Reynolds number (Re) of 20000. The heat transfer patterns via Thermochromic liquid crystal sheet werevisualized and recorded with a digital camera. The recorded images were then analyzed with image processing technique to obtain thedistribution of Nusselt number. The flow characteristics pass through the baffles were also numerically studied with CFD simulation forunderstanding the heat transfer characteristics. The friction losses were measured to evaluate the thermal performance for each baffle. Itwas found that the baffle with rectangular zigzag-cut gives the best thermal performance due to heat transfer augmentation in upstreamand downstream side of baffle.

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