Characterization of diabatic air-water flow in helically coiled micro-channel

Abstract

Experimental studies on flow patterns and heat transfer (HT) phenomena in a two-phase air-water system within a vertically helically coiled micro-scale tube were conducted using an SS-304 tube with a 1 mm diameter, a coil diameter of 50 mm, and a uniform coil pitch of 20 mm. The study investigated heat transfer characteristics under constant heat flux conditions. The superficial gas and liquid Reynolds numbers ranged from 290 to 3800 and 780 to 1170, respectively. The results indicated that throat-annular flow exhibited superior heat transfer performance compared to bubble flow, slug flow, churn flow, and annular flow. Finally, the observed flow regimes from the experiment were analyzed and compared with existing prediction methods.