Thermohydraulic Performance Enhancement in a Plate Fin-and-Tube Heat Exchanger with Flat Plates

The study proposes enhancing the thermohydraulic performance of a plate fin-and-tube heat exchanger by employing flat plates. A plate-and-tube heat exchanger is simulated as a small finned-tube bank with periodic boundary conditions in the spanwise direction using a Large Eddy Simulation approach. A benchmark case is validated using experimental pathlines and Nusselt numbers from a semi-empirical correlation, and the results show good agreement between the numerical and experimental data. Four case studies with different flat-plate arrangements are proposed to reduce pressure drop without penalizing heat transfer. Numerical predictions reveal that the pressure drop decreases because the flat plates prevent the formation of a stagnation zone in front of the tubes. However, heat transfer is unaffected because the flow forms horseshoe vortices, and the flat plates act as microfins. The mean thermohydraulic performance based on a benchmark case is highest in case 5 (1.1473, 1.1469, and 1.0618) for all Reynolds numbers, while the mean air pumping power based on a benchmark case (0.96–0.97) is less than 1. The flat-plate effect is stronger at low Reynolds numbers (1155) across all case studies; however, the thermohydraulic performance decreases as the Reynolds number increases.