The Effect of Rib Size and Configuration Towards the Flow Direction of A Triangular Duct on Enhancing Heat Transfer Factors (Part 1: An Experimental Study)

This article presents an experimental work to investigate the behavior of heat transfer and coefficient of heat transfer at the entrance of a duct having an equilateral triangle section. The duct was subjected to constant heat flux applied through a single side on which different arrangements of ribs were placed. These ribs were placed to act as vortex generators on the heated side while other sides are smooth and thermally insulated. Eight models were used in this work according to the number of ribs, location, and arrangement of ribs. Each rib was placed in the bottom wall of the test section but its distance from the leading edge was varied. The flow was laminar and different Reynolds numbers were selected in this study. Reynolds numbers that were considered in this work were in the range of 125-2000. It was found that the pressure drop and heat transfer rate were greatly affected by adding ribs to the channel compared to the smooth channel. The investigation showed that higher friction loss and heat transfer were achieved in in-line ribs compared to the staggered ribs at the same operating conditions. A significant increase in friction factor and Nusselt number were obtained when the ribs added to the duct. A greater thermal performance was obtained in the V-shape ribs arrangement. The coefficients of heat transfer conducted from the experimental work were correlated with the friction factor and Nusselt number in terms of Reynolds number and the resulting empirical correlation for all considered ribs arrangement inside the duct. These correlations of the present stud give a clear reason for the effect of ribs location and arrangement on the rate of fluid heat exchange and pressure drop with functional fluid velocity.