CFD analysis of heat transfer in a helical coil heat exchanger with constant wall heat transfer coefficient

Abstract

There is a wide application of coiled heat exchanger in the field of cryogenics and other industrial applications for its enhanced heat transfer characteristics and compact structure. Lots of researches are going on to improve the heat transfer rate of the helical coil heat exchanger. Here, in this work, an analysis has been done for a tube-in-tube helical heat exchanger with constant heat transfer coefficient with turbulent flow. There are various factors present that may affect the heat transfer characteristics of the heat exchanger. Here, the experiment has been done by varying the curvature ratio i.e. ratio of coil diameter to inner tube diameter and inlet velocity of the hot fluid in the inner tube. The curvature ratio is varied from 8 to 25 and inlet velocity is varied from 1m/s to 2m/s step wise. The analysis has done using ANSYS 13 CFD methodology. Different parameters are calculated from the results obtained and graphs are plotted between various parameters such as Nusselt number, friction factor, pressure drop and pumping power versus Reynolds number. These graphs have been analyzed and discussed to find out the optimal result for which the heat exchanger would give the best performance.