Abstract: An experimental investigation on the heat transfer effectiveness of
solid and slit ribs mounted on the bottom surface of a rectangular channel has
been carried out at Reynolds numbers of 13400, 22600, 32100 and 40800. The rib
height to hydraulic diameter ratio (e/D_h) set during
experiment is equal to 0.0624. The surface Nusselt number results from
transient liquid crystal thermography are presented. The heat transfer
enhancement performance analysis has been carried out using entropy generation
principle. The slit rib is superior to solid rib from both heat transfer
augmentation and pressure penalty point of view. The performance of the slit
rib is a function of the open area ratio (β) and the location of the slit
(b) from the bottom test surface. The optimum open area ratio is 20% and the
slit located symmetrically from the top and bottom surface of the rib is the
optimum location of the slit. The heat transfer augmentation of the slit rib
(β = 20%) is 61% in comparison to 40% for the solid rib at Re = 32100 and
the pressure penalty for the slit rib is 7% lower than the solid rib. The
entropy generation for the slit rib is 33% less than that of the solid rib.