Experimental analysis to study the effect of perforated louvered strip‐coiled spring insert on heat transfer performance in a double pipe heat exchanger

Abstract

AbstractExperiments have been conducted to study the effect of louvered strip‐coiled spring (PLSCS) turbulators having different pitches and the same angle of attack on thermal performance and pressure drop of a concentric tube heat exchanger. Two inserts in combined form were used for experimentation under turbulent flow at different Reynolds numbers (Re) ranging between 5000 and 20,000. Two pitches (40 mm and 50 mm) of elliptical‐shaped perforated louvered strips (PLS) having the same angles of attack have been taken that were welded on the central core rod. Spring inserts have the same coil diameter of 12 mm with two varying pitches to achieve pitch ratios of 0.5 and 1. Both heat transfer and pressure drop increase with a decrease in pitches of both LS and spring inserts. Nusselt number has the maximum value with spring of pitch 6 mm in combination with a PLS of 40 mm pitch at which is 130.75% higher than the plain tube at the lowest Re among the PLSCS inserts. With perforation, a slight increase in both Nusselt number and friction factor was observed. The maximum thermal performance efficiency value is 1.105 for the lowest Re value.