Abstract: Fluid flow and heat transfer characteristics of three types of plate fin-and-tube surfaces are numerically investigated, plain plate fin-and-round tube, slotted plate fin-and- round tube, and slotted plate fin-and oval tube. The ratio of the long axis over the short one of the oval tube is 2.25 with the same perimeter length as the round tube. The strips in the slotted fin surfaces are arranged radially, with more strips located in the downstream part of the fin surfaces. It is found that the heat transfer rate of the two slotted fin surfaces is appreciably higher than that of the plain one, and the pressure drop of the oval tube slotted fin surface is much lower than that of the round tube slotted surface. When the pumping power of the oval tube surface is 2.5% lower than that of the round tube surface, the heat transfer rate of the oval slotted fin surface is 7% higher than that of the round tube surface. It is found that the pressure drop of the oval tube is significantly lower than that of slotted round-tube fin surface, leading to its superiority in the thermal-hydraulic performance.

Key words: Enhanced heat transfer mechanism, Oval tube, Slotted fin