CFD Simulations of one Period of a Louvered Fin where the Airflow is Inclined Relative to the Heat Exchanger

Artikel i vetenskaplig tidskrift, 2015

This article presents Computational Fluid Dynamics (CFD) simulations of one period of a louvered fin, for a crossflow compact finned heat exchanger, where the incoming airflow was inclined relative to its core. Four inclinations were investigated: 90°, which was when the air flowed perpendicular to the heat exchanger, 60°, 30° and 10° angles relative to the vertical plane. The study included three heat exchanger designs, where two of them had symmetrical louvered fins and a thickness of 19mm and 52mm. The third had a thickness of 19mm and had the louvers angled in one direction. All heat exchangers have been simulated when the airflow entered both from above and below relative to the horizontal plane. Simulations have also been carried out when the airflow entered from the side, illustrating the heat exchanger to be angled relative to the vertical axis. Two air speeds have been investigated for each configuration, where the results were compared to experimental data. The results showed that the airflow characteristics were strongly dependent on the inclination angle. A more inclined heat exchanger generated larger separated areas at the entrance of the heat exchanger core. After approximately six louvers the airflow was fairly similar for all inclinations. The pressure drop over the core was not affected by the direction of the entered airflow. It was also seen that the heat exchanger with the louvers in only one direction resulted in approximately the same pressure drop as the one with symmetrical louvered fins. For a constant velocity in the longitudinal direction within the core, the pressure drop did not varied between the inclinations. Depending on the definition of the heat exchanger arrangement the heat transfer rate was affected. Simulated pressure drop followed the same trend as experimental data, even though the values were over-predicted.