Study of the parameters affecting conjugated heat transfer in plate-fin and tube heat exchanger

A numerical method was used to study the effect of conduction through the fins and convection over the fins of a single-row plate-fin and tube heat exchanger. The simulations were conducted for conditions that are equivalent to those encountered in real heat exchangers. The influence of several parameters on conjugate heat transfer was analyzed. The fin surface is divided in two regions: one of high heat transfer in the region upstream of the tubes, and one of low heat transfer located downstream of the tubes. The region upstream of the tubes is the most affected by conduction through the fins, with decrease of temperature arid heat transfer when conduction is considerable. It was also possible to identify a region of heat transfer reversal in the region downstream of the tubes. The parameters found to affect conjugate heat transfer were fin conductivity and thickness, Reynolds number and tube eccentricity There is a possibility of heat transfer augmentation by making the tube eccentric respect to fin length. By moving the tube nearer to the trailing edge of the fin, the area of low heat transfer downstream of the tube is reduced in size and, at the same tune, the area upstream of the tubes is increased, with reduced heat transfer: This suggests the existence of an optimum position of the tube with respect to the fin length.