A NUMERICAL STUDY OF AIR-SIDE HEAT TRANSFER ENHANCEMENT USING V- FORMATION DELTA-WINGLET VORTEX GENERATORS IN HEAT EXCHANGERS

摘要

The numerical study proposed is to investigate the effectiveness of delta-winglet vortex generators (VGs) used for heat-transfer enhancement in a horizontal rectangular channel as a typical air passage for fin-and-tube heat exchangers. The effects of four different configurations of vortex generators have been investigated: (1) single pair VGs with a 30 degree attack angle; (2) 2-pair VG array with a 30 degree attack angle: (3) single pair VGs with a 45 attack angle; (4) 2-pair VG array with a 45 attack angle. The numerical results indicate that average Nusselt number increase is 31% - 38% and 51% - 71% for the channel mounted with VGs with a 30 degree attack angle and a 45 degree attack angle, respectively. The enhancement for single large pair of VGs is higher than that for a V-formation array with 2 small pairs. However, VGs also introduce extra pressure drop penalties to the channel flow, and higher heat-transfer performance is also accompanied by a larger pressure drop penalty. According to the results, a single large pair of VGs with 45 attack angle shows the best overall performance among all the configurations investigated.