Vortex-Controlled Heat Transfer in Eight-Row Plate Fin and Tube Heat Exchangers

This paper investigates and characterizes the row-dependent thermal performance of an 8-row finned tube heat exchanger with staggered tube arrangement and plain fins. Computational fluid dynamics simulations reveal distinct hydraulic–thermal behavior across tube rows, with the first, second, and eighth rows exhibiting noticeably greater heat transfer efficiency than the exchanger’s average under specific flow conditions. At air velocities below 3 m/s with Reynolds number (Re < 2500), the initial rows demonstrate increased performance, while the eighth row shows comparably enhanced performance at velocities exceeding 6 m/s. Across the range (0.5–10 m/s), rows 1, 2, and 8 exceed rows 3–7 by approximately 15–25% in Nusselt number, indicating that rows 1, 2, and 8 operate under separate flow–thermal conditions. The study also derives individual Nusselt number correlations for each row through systematic simulations across velocity regimes ranging from 0.5 to 10 m/s (Re = 500–6000). The analysis further tries to link these variations to specific flow mechanisms, such as boundary layer development, wake interference, and vortex shedding, which govern the distinct thermal behavior of the first, second, and last rows. These findings could enable optimization: reducing capital costs through minimized row count for target thermal output and lowering operating costs via decreased pressure drop.