Investigation of the geometrical structure of louvered fins in fin-tube heat exchangers for determining the minimum distance of the headers

The effects of the geometrical arrangement of fins on the streamlines, pressure drop and heat transfer in louvered fin and tube compact heat exchangers were numerically studied using the ε-NTU method. The effects of pitch variation, angle, the number of louvers, and flow redirection location in a series of the fins, as well as non-louvered inlet and exit fin length were investigated. Also, the effects of the aligned, non-aligned, positive, and negative louver angles were examined. The simulation results show that the redirection of streamlines depends on the louver angle and the distance of flow re-direction location from the inlet edge of the fin and not on the non-louvered inlet and exit fin lengths, fin pitch, or the number of louvers. Moreover, based on the obtained results, the angle relative to horizon of suction or blowing direction does not affect heat exchanger efficiency. In contrast, the alignment of suction or blowing directions in multiple fins has a significant impact on heat exchanger performance, increasing the amount of heat transfer by 40 %. An analytical equation has been proposed for estimating the maximum height of flow deviation based on two effective parameters of louver angle and the distance of flow redirection location from the inlet edge of the fin.