Numerical Determination of the Thermal Characteristics of a Heat Exchanger with Semicircular Tubes and Wavy Fins

Abstract

The article describes the numerical simulations of a heat exchanger section with a bundle of eight semicircular tube, either plain or connected with longitudinal wavy fins of four different lengths. The inlet velocity ranged from 0.433 to 4.33 m/s (Re=1,000-10,000), with study focused on pressure drop, total heat transfer rate and outlet temperature. The results indicate that fin elongation intensifies measured parameters. Com-pared to the plain tube configuration, wavy fins increased the heat transfer rate by 11%-108%, outlet temperature by 1%-5%, while the pressure drop by 11%-188%, depending on the fin length and inlet velocity. As a consequence, the JF-factor decreased by around 10%pt for every wavelength elongation in comparison to the plain semicircular tubes, with the highest value (80%) for case with the shortest fin. Although the investigated wavy fins provided by up to 21% higher heat transfer than straight‑fin semicircular tubes reported in the literature, they were accompanied by increased pressure losses, reaching up to 27%. The gathered results suggest further experimental investigation to confirm the effectiveness of wavy-finned semicircular tubes in the applications where the intensified heat transfer rate is required.