Experimental investigation of vortex-enhanced heat transfer in narrow rectangular channels
摘要
Narrow rectangular channels have attracted much attention due to their efficient heat transfer and miniaturization of equipment. In this study, a 10 × 2 × 100 mm narrow rectangular channel was designed. The effects of the synergistic effect of vortex generator (VG) and bubbles on flow and heat transfer in a narrow rectangular channel were investigated by PIV experiments. The results show that in the single-phase flow, increasing the number of VG (VG = 7 is the best) can enhance the vortex and thin the boundary layer, and the maximum heat transfer coefficient is 11,023.6 W·m−2·K−1. In the two-phase flow, VG = 7 weakens heat transfer due to the increase in stagnation zone. achieves the optimal heat transfer in two-phase flow performance PEC = 1.5 by balancing vortex strengthening and pressure drop. The heat transfer coefficient is up to 41,108.1 W·m−2·K−1 when the steam quality is 0.046. When the upstream and downstream flow patterns change, the downstream vortex intensity of VG = 7 is 300% higher than that of the upstream. Under adiabatic condition, the downstream vortex intensity is also increased by 58.9%. The synergy of VG and bubbles can significantly improve the heat transfer capacity, turbulence and eddy current intensity.