This study presents a numerical analysis of laminar convective heat transfer in a rectangular channel with different configurations of delta-winglet vortex generators (VG). A low and high Reynolds number case of 225 and 1123 is simulated which is representative of the lower and upper limits of the air velocity range between 1-5 m/s in a typical air-cooled condenser (ACC) system. The effects of interacting and non-interacting vortices on the Nusselt number and pressure drop are observed for the two Reynolds numbers. The low-Re cases flow cleaner through the channel, pressure drop is slightly lower for the array in comparison to a straight-line formation for two VG pairs; however, the increase in Nusselt number is higher in the straight-line configuration. For the high-Re cases the vortices generated are stronger and persist longer and interactions between vortices in the array configuration lead to Nusselt number increases, but a higher pressure drop results. The straight-line configuration has an almost equal increase in Nusselt number and pressure drop. Recommendations are made to further explore the VG placement using different Reynolds numbers for constructive augmentation of the vortices as the vortex behavior and interactions are mainly a affected by the inlet flow velocity.
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Vortex generator arrays in air-cooled condensers for power plant applications