Experimental study of fluid flow properties in spiral tube heat exchanger with varying insert shape over spiral tube profile

Abstract

Experimental and computational analysis is carried out for analyzing the effect of different shapes of inserts. The inserts used are conical inserts, hemispherical shape insert, helical insert and these are mounted over cascaded spiral copper tube heat exchanger. The performance characteristics and fluid flow characteristics are studied for turbulent-counter flow and the fluid is water. Experimentation carried out for cold water at 304 K and hot water at 333 K and the rate of fluid flow for cold water inside spiral tube is 0.725 to 2.955 L/min. The hot water flows at 333 K with fluid rate of flow 4.025 L/min horizontally across outer shell. The comparative study of different shapes of insert with rate of fluid flow and Reynolds number is considered ranging from 4236 to18545. The study stated that the helical type insert gives promising and significant improvement by 18.5 % more than spiral tube without insert, 15.5 % more than conical insert and 11.5 % more than hemispherical shape insert for thermal performance under turbulent-counter flow. The minimum and maximum values obtained from the study for h htr , Nu, f, effectiveness N.T.U and ɳ tp varies from 1298.5 to 3541.6, 88.28–160, 0.0438–0.0306, 0.89–0.59, 2.51–1.24 and 2.41–1.31 respectively. The maximum optimum value is obtained for performance factor (ɳ tp ) is 1.51 for Reynolds number ranging 13,322 for helical insert of 2 mm diameter and 10 mm pitch distance.