Experimental investigation of heat transfer and fluid flow in a circular tube with lanced ring insert

Circular ring inserts are found to enhance the heat transfer rates in the tube flow, while perforations in the ring inserts mitigate the frictional losses. In this study, the geometry of perforated ring is modified by creating lanced holes with a deflector. The experimental data for lanced ring are collected by varying the pitch ratio from 3.33-6.66 and diameter ratio from 0.5-0.6 in the Reynolds number range of 10000-37754. The enhancements in the Nusselt number and friction factor are found to vary in the range of 1.69-4.1 and 16-72, respectively.