Experimental investigation of heat transfer and fluid flow behaviour in multiple square perforated twisted tape with square wing inserts heat exchanger tube

The present work deals with experimental investigation of heat transfer and fluid flow characteristics of multiple square perforated twisted tape with wing inserts in a heat exchanger tube. The range of selected geometrical parameters are, perforation width ratio (a/W T ) of 0.083–0.333, twist ratio (T L /W T ) of 2.0–3.5, wing depth ratio (W d /W T ) of 0.042–0.167 and number of twisted tapes (T P ) of 4. The Reynolds number (Re n ) selected for experimentation ranges from 5000 to 27,000. The maximum heat transfer and friction factor enhancement was found to be 6.96 and 8.34 times that of plane tube, respectively. The maximum heat transfer enhancement is observed at a a/W T of 0.250, T L /W T of 2.5, and W d /W T of 0.167.