Improving heat transfer of air-cooled cylinders with fins with slits

In finned cylinders with slits around the cooling fin circumference, thermocouples were attached at three positions in the radial direction on the surface of the fin, and fin surface temperatures were measured by rotating the cylinders relative to the flow direction in a wind tunnel to change the angular position of the attached thermocouples. The temperature distribution around the fin circumference and the average heat transfer coefficient were then investigated at air velocities from 20 km/h (5.6 m/s) to 60 km/h (16.7 m/s). Results indicated that, compared with fins without slits, fins with slits, either aligned or offset, decreased fin surface temperatures and increased the heat transfer coefficient. The fins with slits also resulted in a more uniform circumferential temperature at the fin root at a lower air velocity, but not at a higher air velocity, compared to fins without slits.