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Heat transfer enhancement of turbulent channel flow by baffles with rectangular, triangular and trapezoidal upper edges
Author(s)
Date Issued
July 29, 2015
Type
Article
Abstract
An experimental study was undertaken for investigating the heat transfer enhancement in a channel with baffle turbulators mounted on the lower wall. The baffles with rectangular, triangular, and trapezoidal upper edges were examined. The experiments were conducted in the rectangular channel with aspect ratio AR = 10 and height H = 30 mm, using air as the working fluid for Reynolds numbers between 5100 and 22,500. The effect of a baffle height to channel height ratio (y/H = 0.2, 0.3, and 0.4) on the heat transfer, pressure drop, and thermal enhancement factor characteristics was also investigated. The uniform heat flux condition was applied to the external surface of the lower wall of the channel. The results revealed that the baffles with rectangular upper edges gave a higher Nusselt number and friction factor than the ones with triangular and trapezoidal upper edges. Nusselt number increased while thermal performance factor decreased as a baffle to channel height ratio (y/H) and Reynolds number increased. For the range determined, the maximum thermal performance factor was achieved by using the baffles with trapezoidal upper edges at the smallest baffle to channel height ratio and the lowest Reynolds number, due to the best tradeoff between the increases of heat transfer and friction loss.
Citation
Journal of Engineering Thermophysics, 24(3), 296-304, 2015