Studies on heat transfer and friction factor characteristics of turbulent flow through a micro-finned tube fitted with left–right inserts

Experimental investigation on heat transfer and friction factor characteristics of micro-finned tube fitted with full-length twisted tape and left–right twisted tape inserts of twist ratio 7.44, 8.27 and 11.17 has been presented. The experimental data obtained were compared with those obtained from plain tube published data. The heat transfer coefficient enhancement for left–right twisted inserts is higher than that for full-length twisted tape inserts for a given twist ratio. The empirical correlation for Nusselt number, friction relating Reynolds number and twist ratio was formed for both twisted tape inserts and left–right inserts and found to fit the experimental data within ±3.6% and ±2.5% for Nusselt number and ±7% and ±8.5% friction factor, respectively. Performance evaluation analysis was made and the maximum performance ratio was obtained for left–right twisted tape inserts.