The Effect of the Hole on the Rectangular Vortex Generator on the Thermal-Hydrodynamic Performance of the Minichannel

There are several ways to increase heat transfer in mini-channels, like adding a vortex generator. In this paper, the effect of the presence of the hole on vortex generators on the heat transfer parameters is examined. In this study, a 50 mm long mini channel with eleven rectangular vortex generators, with holes with area of 5 to 60% of the vortex generator area, was analyzed with water-based fluid under constant flux in the range of Reynolds numbers 200-1000. The results showed the presence of holes on the vortex generators reduced the pressure drop resulting from the obstruction against the fluid flow and 34.7% decrease in pressure drop is observed for minimum and maximum area of holes in Reynolds number 1000. The Nusselt number is increased by existence of a hole in the Reynolds numbers range and then is decreased by increasing the size of the hole due to the reduction of the vortex size behind the obstacle, so that in the maximum Reynolds number by increasing hole size, 34.3% decrease is observed. The results also showed that the maximum performance evaluation criterion for the Reynolds number 200 is obtained in the VG-15 model and by increasing Reynolds number in the models with smaller holes, which maximum value of the performance evaluation criterion is occurred in VG-05 model in the Reynolds number 1000.