Relationship between the Intensity of Secondary Flow and Convection Heat Transfer in a Helically Coiled Circular Tube with Uniform Wall Temperature.

Numerical method is used to investigate fully developed laminar flow in helically coiled circular tube in this paper. The non-dimensional parameter (secondary flow Reynolds number Se) based on absolute vorticity flux along the mainstream is used to indicate the intensity of secondary flow caused by the centrifugal effect in helically coiled circular tube. The relationship between the intensity of secondary flow and the intensity of laminar convective heat transfer is studied. The effects of curvature and torsion on the enhancement of heat transfer are also considered. The results reveal that the absolute vorticity flux along the mainstream can be used to indicate the local or averaged intensity of secondary flow; the non-dimensional parameter of the absolute vortex along the main flow determines the convective heat transfer and friction factor. The relationships of Nusselt number and friction factor with the Se are obtained. The effect of curvature on Nusselt number is obvious, but the effect of torsion on Nusselt number is less obvious. [ABSTRACT FROM AUTHOR]