EXPERIMENTAL AND NUMERICAL THERMAL PERFORMANCE EVALUATION OF HELICAL SCREW INSERTS IN A TUBE WITH DOUBLE STRIPS AT LAMINAR FLOW

In this study, experimental analysis was conducted to evaluate the thermal hydraulic performance of the fluid flow in a double strip helical screw insert with a tube at different twist ratio values in the laminar flow regime. Computational fluid dynamics (CFD) analysis was also considered to investigate the thermal and fluid flow characteristics in the tube with the insert. The double strip helical screw inserts showed enhancement in the heat transfer at decreasing twist ratio values and increasing Reynolds numbers compared to single strip helical screw inserts. A maximum enhancement of 327% was found in the Nusselt number with the double strip helical screw insert at a twist ratio of 1.5 and Reynolds number of 300 compared to the plain tube. The maximum Nusselt number value was found with a double strip helical screw insert at a twist ratio of 1.5 and Reynolds number of 2000, whereas the maximum value of the Nusselt number ratio was found to be 4.27 at a twist ratio of 1.5 and Reynolds number of 300.A correlation between theNusselt number and friction factor was developed by using the experimental results. The maximum value of the thermal performance factor was found to be 2.39 with the double strip compared to the single strip helical screw inserts at a twist ratio of 2.5 in the laminar flow regime. Therefore, this analysis shows the suitability of applying double strip helical screw inserts in the miniaturization of heat exchangers. This could be enabled to save our environment by reducing pollution through the efficient use of energy resources.