Numerical study of heat transfer in two-row heat exchangers having extended fin surfaces

This paper reports on a three-dimensional study of air through two-row cyli nder tubes. The analysis is intended to present a comparison of numerical a nd experimental data to validate the laminar flow postulation. The current study explores the influence of four perforated fin surfaces on the pressur e drop and heat transfer rate. To gain further insight into the three dimen sional vortical flow structure, we conduct a topological study of the veloc ity field. Examination of the surface flow topology and the flow patterns a t cross-flow planes sheds some light on the complex interaction of the cyli nder tube with the mainstream flow. This study clearly reveals a saddle poi nt in front of the first row of cylinder tubes. Also clearly revealed by th e computed solutions is a flow reversal found in the wake of the tube. The character of the critical-point-induced flow is also addressed. This study shows that the addition of perforated fins is not without deficiency. There is, in fact a trade-off between the benefit of having an improved heat tra nsfer and the penalty of having an increased pressure drop.