Thermal resistance study and numerical optimization of plate fin-and-tube with mechanical expanded joint

Abstract

This paper analyzed the mechanical expanded joint process of a plate fin-and-tube heat exchanger and the geometry of the fin's tube-hole in an effort to reduce the thermal contact resistance between the fin and the base tube and improve the tube-fin's heat transfer capability. A plate fin-and-tube heat exchanger was used in the heat transfer performance experiment, and a novel experimental technique was used to estimate the thermal contact resistance between the fins and the tube. By using the finite element simulation, the post-expansion contact stress between the fin and the base tube was calculated, and a correlation between the contact stress and the thermal contact resistance was established. The simulation approach optimizes the expansion parameters and design of the fin's tube-hole. Based on the fin type of the specimen, simulation calculations were performed by adjusting the expansion interference and the interval between the fin's tube-hole and the base tube before the expansion. The results of the calculations indicate that, within a certain range, increasing the expansion interference and lowering the interval between the tube-hole and the base tube can increase contact stress and decrease thermal contact resistance. Changing the shape of the specimen's tube-hole can more efficiently to reduce thermal contact resistance. In order to alter the shape, a power function curve was applied to the original straight part of the fin profile.