Heat transfer and pressure drop in dimpled fin channels

Heat transfer characteristics are examined comparatively for four sets of dimpled fin channels with Reynolds number (Re) ranging from 1500 to 11,000 in order to determine the effects of dimple arrangement, fin length (L) to channel hydraulic diameter (d) ratio and Re on heat transfer over the dimpled fin channel. These dimpled fin channels share the identical rectangular section of a channel aspect ratio (AR) of 6 with three different L/d of 8.9, 6.2 and 3.5. The two opposite dimpled fins with four different concave and convex arrangements affect the secondary flows and vortex structures tripped by dimples that signify various heat transfer performances over each dimpled fin. Heat transfer correlations for spatially averaged Nusselt number (Nu¯) over each dimpled fin are generated using Re and L/d as the controlling parameters. A set of design criteria for determining the optimal L/d that offers the maximum cooling power available from the dimpled fin for each specified dimple arrangement on two opposite fin walls is derived to assist the design activities using the dimpled fin array.