Experimental study on heat transfer in ducts with winglet disturbances

Heat transfer and friction characteristics for a new type of enhanced rectangular duct with winglets have been investigated experimentally. The results indicate that, in the range of Reynolds number from 5 x 10(3) to 4.7 x 10(4), heat transfer performance of the enhanced duct with winglets is superior to the enhanced duct with transverse disturbances. Comparisons under the identical pumping power condition reveal that the Nusselt number ratio Nu/Nu(o) of the winglet duct to the smooth duct varies from 1.7 to 3.5, while this ratio is usually less than 1.5 for the enhanced ducts with transverse disturbances. For condition of same mass flow, the ratio Nu/Nu(o) of the winglet duct to the smooth duct varies between 2.7 and 6.0.