The Effects of Decreasing Hydraulic Diameter on Forced Convection Heat Transfer in a Rectangular Channel with Upper Wall Exposed to the Constant Heat Flux

In this paper, an experimental study on the effects of the hydraulic diameter on heat transfer and fluid flow characteristics in fully developed turbulent flow in a rectangular channel with one wall (upper) exposed to the heat flux is presented. The hydraulic diameter of the channel was varied by using a wooden block mounted on the bottom wall of the channel. The block to channel height ratio, Hb/H was kept at 0.6, the block to channel length ratio L b /L was kept at 1, and the block to channel width ratio, B b /B was varied from 0 to 0.6. Four cases were investigated in this study for Reynolds number ranging from 6,000 to 20,000. The results of this investigation demonstrate that, the pressure drop is increased with decreasing hydraulic diameter and heat transfer coefficient is decreased with decreasing hydraulic diameter.