Numerical Investigation of Tapered DL-MCHS with Alternating Flow Configuration

Abstract

The thermal coolant proprieties are a potential indicators of heat transfer performance, however, the coolant often remains less efficient because of its inability to absorb the excess heat. Thanks to nanotechnology, a new concept has been introduced to prepare nano-sized particles that can be dispersed in the coolant to form a stable nanofluid with excellent thermal properties. Nevertheless, the addition of the nanoparticles leads to an increase in viscosity which augments the shear stress affecting the performance of the cooling system. This study aims to investigate both the thermal and hydrodynamic behavior of nanofluid flowing in turbulent conditions through a cylindrical copper pipe while maintaining at constant temperature by using a single-phase approach. The governing equations are solved by using the shear stress transport (SST) k-w turbulence model along with the finite element method. In this work, the temperature and velocity distribution of Al₂O₃-water nanofluid for different volume fractions are studied. The effects of Reynolds number (Re) and volume fraction of nanoparticles (?) on both the Nusselt number and shear stress are also investigated thoroughly. Moreover, the impact of these types of nanoparticles (Al₂O₃ and Cuo) on the Nusselt number and pressure drop is examined. The obtained results show how the concentration of nanoparticles influences the radial distribution of temperature and velocity by giving the flow a certain homogeneity which enhances heat transfer but it also affects the hydrodynamic behavior of nanofluid leading to an increase in the shear stress. Based on these two investigations the nanofluid containing Al2O3 particles is better than that of CuO even though the thermal conductivity of CuO is higher than that of Al₂O₃.