Study of turbulent convective heat transfer enhancement by Al_2O_3-water nanofluid through a rough circular tube

摘要

Nanotechnology is a novel approach in thermal engineering science to enhance the overall thermal performance of compact heat exchangers by the homogeneous dispersion of solid nanoparticles of higher thermal conductivity in conventional base fluid like water, oil, ethylene glycol etc. The heat transfer rate is substantially intensified by the addition of nano-sized solid particles which provide superior thermo-physical properties in comparison with base fluid. In the present study, a numerical simulation is performed to investigate the turbulent convective heat transfer characteristics of Al_2O_3-water nanofluid of volume fractions (1%, 3% and 5%) through a rough circular tube subjected to constant heat flux for a range of Reynolds number 10,000 to 30,000. The finite volume method is employed for solving the governing equations and k-ω SST turbulent model for single phase analysis is considered. At a Reynolds number of 25000, application of nanofluid combined with rough tube enhances the Nusselt number by 13.10%, 21.86% and 63.03% in case of relative roughness of the wall of 0.001, 0.005 and 0.01 respectively.