Enhancement of convective heat transfer in rectangular ducts of interrupted surfaces

Abstract

Results are presented from systematic experimental investigations into the enhancement of heat transfer of 11 interrupted surfaces of one type and of different size formed by a multitude of short rectangular ducts with a constant cross-sectional aspect ratio of 7:1 in the absence of burrs and bends on the sharp edges of fins. Investigations were carried out with air in the range of Reynolds numbers from 500 to 10000 for geometric parameters l'/ d = 0.65−3.24 and δ = 0.058−0.114. Based on these investigations, standard experimental thermohydraulic characteristics of these surfaces are obtained as well as their correlations as functions of Re and geometric parameters l'/ d and δ/ d. New results are obtained on the effect of the geometric parameters l'/ d and δ/ d of interrupted surfaces on the enhancement of heat transfer in them and also on the experimental determination of the coefficients of overall pressure drop at the entrance and exit from the interrupted surface in a heat exchanger.