NUMERICAL STUDY OF FORCED CONVECTION HEAT TRANSFER OVER CIRCULAR AND OVAL TUBE BANKS USING RECTANGULAR WINGLET VORTEX GENERATORS
The present work represents a two- dimensional numerical investigation of forced convection heat transfer
over circular and oval tube banks of seven rows in an inline arrangement with rectangular longitudinal vortex
generators (LVGs). The effects of Reynolds number (from 550 to 1775), the number of vortex generators (3,
and 7) and the angle of attack (30° and 45°) of rectangular VGs on the heat transfer and fluid flow
characteristics are examined. The characteristics of average Nusselt number (Nu), associated pressure drop
(ΔP), streamline distribution and temperature contours are studied numerically by the aid of the
computational fluid dynamics (CFD). The maximum heat transfer coefficient (nearly 75 Wm-2K-1) is achieved for 7 VGs and 45 degree of angle of attack configuration for circular tube banks (compared to the baseline case of 18 Wm-2K-1), with a pressure drop penalty of nearly 210 Pa. The streamline plot shows an excellent recirculation region near the location of the VG's, indicating that the addition of vortex generators intensifies the mixing between the hot and cold fluids and thereby enhances heat transfer significantly. The performance of the oval and circular tube banks with vortex generators under the same operating conditions is compared with a focus on finding the optimized configuration of vortex generators.