Heat transfer Augmentation in an Inclined Tube Using Perforated Conical Ring Inserts

Turbulent flow forced convection heat transfer and pressure drop in a uniformly heated tube equipped with perforated conical ring (PCR) and typical conical ring (TCR) with divergent arrangement inserts at different angles of tube inclination has been investigated experimentally. These characteristics includes Reynolds number (Re), Prandtl number (Pr), pitch ratio of conical ring (PR), and angle of inclination (θ). Wide range of Reynolds number has been used to extend from 4000 to 24000 under constant wall heat flux, and three angles of inclination ; θ=0^o (horizontal position), θ=45^o(inclined position), and θ=90^o(vertical position). Three values of PR were used; PR=4, 7, and 10. Correlations for friction factor and mean Nusselt number have been deduced as a function of Re, Pr, and PR at each angle of inclination. Results show that the thermal performance factors at constant pumping power in the case of tube fitted with PCR are higher than that in a tube fitted with TCR by 22%; and it improves as the angle of inclination moves from vertical to horizontal position by 3.25% for the case of PCR and vice versa for TCR case by 2.46%.