Numerical Analysis for Saving Fin Material in Helical Segmented-Tubes

A numerical analysis is carried out in a small finned tube bank for several cutoff angles (30°, 45°, 60°, and 90°) at the rear part of helical segmented-tubes. Numerical simulations are undertaken using the Reynolds Averaged Navier-Stokes Equations approach. The turbulence effect is modeled with the Re-Normalization Group k-ε model and the finned tube geometry is represented by means of cut-cell method. Numerical results of these proposals are compared to a benchmark case (uncut fin case). Predictions show transport properties (energy and momentum) similar for cutoff angles less than (or equal to) 60°, since flow separation occurs nearly at this angle. Variations in heat transfer are less than 1% for 45° cutoff angle (fin material is reduced 25%) and less than 3.37% for 60° cutoff angle (fin material is reduced 33%). Therefore, finned tubes with cutoff angles of either 60° or 45° are recommended because their heat transfer and aerodynamics are approximately equal to those of benchmark case.