Numerical analysis of tube flow with helical insert using nano fluid to enhance heat transfer

Abstract

The researchers have been seeking ways to enhance heat transfer characteristics of system without need to increase pumping power. The use of helical insert in tube can significantly enhance its heat transfer characteristics by changing laminar flow to turbulent flow. The presented study investigates the augmentation of heat transfer in tube with the incorporation of helical insert the procedures of Computational Fluid Dynamics. The CAD model of tube is developed in CATIA V5 software and is imported in ANSYS CFX software for further analysis. The turbulence model used for analysis is k-omega which are accurate and robust for a wide range of boundary layer flows with pressure gradient. Subsequent analysis is conducted to determine the enhancement of heat transfer by changing base fluid to nano fluid. The nanofluids used in the analysis is CuO/water with 1% and 2% volume fraction. The temperature, velocity profile and heat transfer coefficient are determined for each case and comparison is made from water. The results have shown that the helical coil insert changes flow type (laminar to turbulent) and enhances heat transfer rate. The use of CuO/water nanofluid increased Nusselt number by 11.1% at higher Reynolds number and for lower Reynolds number the Nusselt number increased by 18.03%.