Thermohydraulics of laminar flow of viscous oil through a circular tube having integral axial rib roughness and fitted with center-cleared twisted-tape

The experimental friction factor and Nusselt number data for laminar flow through a circular duct having integral axial rib roughness and fitted with center-cleared twisted-tape have been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are that with and without center-cleared twisted tapes in combination with integral axial rib roughness perform significantly better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain amount of twisted-tape center-clearance. (C) 2012 Elsevier Inc. All rights reserved.