A parametric investigation of the heat transfer enhancement of tube bank heat exchanger with reversed trapezoidal profile fins

In this study, a reversed trapezoidal profile fins attachment to the tube bank heat exchanger was proposed to enhance the heat transfer performance. A validated computational fluid dynamics (CFD) model was used to investigate the flow behaviour and thermal performance of the staggered tube bank heat exchanger with reversed trapezoidal profile fins. The simulation employed the RNG k-ε model with enhanced wall treatment. The effects of fins’ angle (2°≤α_tf ≤ 10°), length (0.5D ≤ L_tf ≤ 2D) and thickness (1 mm ≤ H_tf ≤ 5 mm) within a range of Reynolds number (5500 ≤ Re ≤ 14500) were discussed. Nusselt number (Nu), pressure drop (ΔP) and performance evaluation criterion (PEC) were used to evaluate the heat exchanger's performance. The results showed that both Nu and ΔP followed an increasing trend as α_tf increased, which indicates a heat transfer enhancement and a larger airflow resistance. As L_tf increased from 0.5D to 2D, Nu showed a continuous increase with the maximum value obtained at L_tf = 2D. However, ΔP showed a tendency to increase and then decrease as L_tf increased, with the maximum value observed at L_tf = 1.25D. A larger thickness resulted in a higher airflow resistance penalty compared to the improvement in Nu. The thickness was recommended to be as small as possible, provided that the manufacturing process and mechanical strength requirements were met. If the adverse effect of pressure drop was not of concern, the optimal thermal–hydraulic performance (PEC) could be obtained at a larger angle, length and smaller thickness.