MIXED CONVECTIVE FLOW HEAT-TRANSFER IN A VERTICAL HELICOIDAL PIPE WITH FINITE PITCH

Fully developed laminar mixed convective flow and heat transfer in a vertical helicoidal pipe with finite pitch is studied numerically in this paper. The centrifugal, buoyancy, and torsion forces created by the pitch of the helix are considered. The thermal boundary conditions are uniform heat flux axially and uniform wall temperature peripherally. The velocity, the temperature profiles, the friction factor, and the Nusselt number are obtained. The results indicate that torsion can significantly change the axial and secondary flow patterns and temperature distributions in the helicoidal pipe with a fixed pressure gradient. Torsion can also remarkably affect the flow rate, the friction factor, and the Nusselt number. However, at a fixed Dean number, there is only slight difference in the Nusselt numbers of the upward and downward flow.