THREE-DIMENSIONAL SIMULATIONS OF THE FLOW DEFLECTION IN A LOUVERED FIN HEAT EXCHANGER WITH ROUND TUBES IN A STAGGERED ARRANGEMENT

摘要

In this study three-dimensional numerical simulations were performed to investigate the flow deflection and its influence on the horseshoe vortex development in a louvered fin round tube heat exchanger with three tube rows in a staggered layout. The numerical results are validated against experimental data. It was found that the flow deflection is affected by the tubes in the same tube row and by the tubes in the upstream tube rows. The flow efficiency values obtained with two-dimensional studies are only representative for the flow behaviour in the first tube row of a staggered louvered fin heat exchanger with round tubes. The flow behaviour in the louvered elements of the subsequent tube rows differs strongly due to its three dimensional nature. Furthermore it was found that the flow deflection affects the local pressure distributions upstream the tubes of the downstream tube rows which explains the stronger horseshoe vortex system at these locations.