The effect of enhanced geometry(pore diameter, gap width) is investigated on the pool boiling of R-134a/oil mixture for the enhanced tubes having pores with connecting gaps. For the smooth tube, the heat transfer coefficient decreased as the oil conce...
The effect of enhanced geometry(pore diameter, gap width) is investigated on the pool boiling of R-134a/oil mixture for the enhanced tubes having pores with connecting gaps. For the smooth tube, the heat transfer coefficient decreased as the oil concentration increased. For the enhanced tube, the heat transfer coefficient decreased significantly even at a small concentration (1%). The reason may be attributed to the accumulation of oil in sub-tunnels of the enhanced geometry. The tube with largest pore diameter yielded the highest heat transfer coefficient even with oil.