Mixed convection with surface radiation in a rectangular channel with heat sources in presence of vortex generator and heat spreader

Abstract

In the first part of the work, triangular shaped VG is used in a vertical and horizontal channel respectively. The effects of Reynolds number, the spanwise, and pitchwise position of VG on heat transfer characteristics have been examined neglecting surface radiation. It is found that VG enhances the rate of heat transfer in the channel. The results reveal that Re and the position of vortex(spanwise and pitchwise) have considerable effect on heat transfer. A significant interaction is observed between x/H, h/H with Re. Then surface radiation is considered for detailed parametric study. The investigation has been carried out to find out the effect of VG on heat transfer for various Re(100, 250, 500, and 750). The emissivity of heat sources is varied from 0.1 to 0.9 and the emissivity of the channel walls and VG are fixed to 0.9. It is observed that and#952;m reduces 47.81% with increases in emissivity of the heat sources from 0.1 to 0.9 and the maximum temperature decreases to 342.6 K from 352.3 K. Further, the heat spreader is mounted on the each heat source. The influence of parameters like Re, height of the heat source, width and thickness of the heat spreader have been investigated. It depicts that and#952;m decreases with increase in height of the heat source. As it changes from 0.2H to 0.4H, the maximum change in and#952;m is 17.64% at Re=750. For width of the heat spreader 0.4H, 0.6H and 0.8H, and#952;m decreases 7%, 14% and 17.43% respectively at Re 250. Also and#952;m is reduces 12.68%, 14.31% and 17.43% for thickness of the heat spreader 0.025H, 0.05H and 0.1H respectively at Re 250 compared to without spreader. Finaly, surface radiation with heat spreader is considered for horizontal and vertical channel. The effect of parameters like emissivity of heat source(and#949;c), heat spreader(and#949;sp) and channel wall(and#949;s) and Re on the rate of heat transfer has reported. It reveals that non-dimensional maximum temperature(and#952;m) decreases 11.53% with respect to without spreader case after introduction of heat spreader over the heat source