Heat Transfer Characteristics Analysis of a Nanofluid in a Tube with a Co-axial Twisted Tape Inserter: A Numerical Approach

This study demonstrates the forced convection heat transfer of a water-based nanofluid inside a circular tube with a twisted tape inserter. During these simulations, it was assumed that the tube wall heated with constant heat flux, inlet of the tube had a lower temperature and Titanium Oxide (TiO2) particles were used as nanoparticles for nanofluid mixture. The results depict the effect of some significant parameters, i.e., twist ratio (T.R.), number of twists, Reynolds number, and volume fractions of nanoparticles on the heat transfer characteristics inside the tube with a twisted tape inserter. It is visualized from the numerical results that the Nusselt number (Nu) and heat transfer co-efficient have higher values at the twisted region than the outlet. During this numerical simulation, the Reynolds number (Re), volume fractions of particles, and twist ratios were varied into the range from 100 to 500, 0 to 0.1, and 1 to 5, respectively. Mixture model conducted these numerical simulations with Direct Numerical Simulation (DNS) method using ANSYS Fluent 16.2 with the help of three-dimensional Navier-Stokes equation. The results depicted for both water and nanofluid, the average Nusselt number and heat transfer co-efficient enhance at lower twist ratios and a higher number of twists. Results also show that Nusselt number and heat transfer coefficient increase with Reynolds Number. The heat transfer characteristics of twisted-tape inserter portion and their differences of those characteristics with the tube outlet were investigated numerically and graphically.