Experimental investigation on the thermo-hydraulic performance of air–water two-phase flow inside a horizontal circumferentially corrugated tube

In this study, flow visualization, pressure drop and thermal characteristics of the corrugated tube with non-boiling air–water two-phase flow were experimentally studied. Glass tubes were used to visualize the flow patterns of two-phase flow. Furthermore, the thermal behavior of two phase flow was studied in the copper made tubes which was under constant heat flux. The total of 740 W thermal energy was applied on tubes. Superficial velocity of liquid was within the range of 0.42 m/s to 1.69 m/s. Also, the superficial velocity of air was within the range of 0.21 m/s to 1.06 m/s. The results revealed that the corrugations significantly affect the flow patterns which results in earlier transition. The flow patterns of bubbly, churn, wavy slug, wavy plug, wavy stratified and mist flow were observed inside corrugated tube. Also, it was found that the maximum Nusselt number increment in corrugated tube was 3%. Besides, formation of the mist flow in corrugated tube reduced the Nusselt number. Also, the pressure drop was significantly affected by the air–water two-phase flow presenting around 165 % in the pressure drop compared to the single phase flow.