Heat transfer enhancement by streamlined winglet pair vortex generators for helical channel with rectangular cross section

Abstract

This paper proposes an innovative vortex generator (VG) named as streamlined winglet pair (SWP) VG. It is used in a helical channel with rectangular cross section to enhance heat transfer performance. The effects of the arrangement of the SWP VGs on the performance are investigated by using air as the working fluid. The heat transfer enhancement and pressure drop of the SWP VGs are compared with those of the equilateral triangular winglet pair (ETWP) VGs, the isosceles right-angled triangular winglet pair (IRATWP) VGs, the semicircle winglet pair (SEWP) VGs, and the spline curve winglet pair (SCWP) VGs. The field of vorticity and pressure around the VGs are analyzed. The results of this study show that, compared with those of the heat exchanger without VGs, the heat transfer coefficients increase by 46 % by using the VGs mentioned above. Among all types of VGs used in this study, the SWP VGs exhibits the least pressure drop. Compared with those of the IRATWP VGs, the friction factors of the SWP VGs decrease by 21 %. The main reason for the lower pressure drop exhibited by the SWP VGs is that the pressure drag is lower owing to its streamlined configurations. The arrangements of the SWP VGs significantly affect the thermal performance enhancement.