Heat transfer enhancement by a circumferentially non-uniform array of longitudinal fins assembled inside a circular channel

Abstract

Circular channels are one of the most common tools used in several types of heat exchangers. When available energy for supplying pumping power is a constraint, improving the design of heat transfer elements, such as longitudinal fins, becomes significant. In this paper, a new array of fins is introduced, in which the longitudinal fins are assembled non-uniformly along the internal circumference of a circular channel. A numerical model is used for calculating the pressure drop, required pumping power, and heat transfer of finned-tube laminar flow. Three cases including smooth channels, uniformly finned channels, and non-uniformly finned channels, sharing the same pumping power, are compared to each other according to their heat transfer capacity. It is proved that the proposed non-uniform configuration of fins improves the thermal performance up to 46% in comparison with smooth channels and traditional uniformly finned channels, depending on the magnitude of the required pumping power. Finally, the effects of geometrical parameters such as the number of fins, relative fin heights, and length to diameter ratios on the thermal performance of the fins' assembly are reported.