Enhancement of heat transfer of laminar flow of viscous oil through a circular tube having integral helical rib roughness and fitted with helical screw-tapes

The experimental friction factor and Nusselt number data for laminar flow of viscous oil through a circular duct having integral helical rib roughness and fitted with helical screw-tape insert 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 the helical screw-tape inserts in combination with integral helical rib roughness perform significantly better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain value of fin parameter.

► Laminar flow in helically ribbed duct with helical screw-tape is studied.
► Friction factor and Nusselt number correlations are developed.
► The thermohydraulic performance is evaluated.
► This finned geometry performs significantly better within limits.
► Results are useful for solar thermal heating in solar thermal electric power plants.