EXPERIMENTS ON CONVECTIVE HEAT TRANSFER IN CORRUGATED CHANNELS

Experiments have been performed to study convective heat transfer in the entrance region of corrugated channels. With water as the working fluid, two channel spacings were examined for a single corrugation angle of 20 degrees. The flow rate was varied over the range 150 <= Re <= 4000. Flow visualization under low-Reynolds-number flow conditions suggested the presence of longitudinal vortices, while at somewhat higher Reynolds numbers, the existence of spanwise vortices was clearly revealed. For Re > 1500, Nusselt numbers in the corrugated channels exceeded those in the parallel-plate channel by approximately 140% and 240% for the two channel spacings, the corresponding increases in friction factor being 130% and 280%. Performance evaluations under the criteria of equal mass flow rate, equal pumping power, and equal pressure drop per unit length established both the corrugated channels as superior to the parallel-plate channel in intensifying heat transfer.