The influence of thermal properties of delafossite nanofluid CuAlO2 on the turbulent natural convection inside a cavity

Abstract

In the present work, an enhancement for the free turbulent convection in a rectangular cavity is examined by using a novel Delafossite Nanofluid. Delafossite CuAlO2 nanoparticles prepared using Al2O3 as dominant at four different weight concentrations of the doping copper 0, 1, 3 and 5% using an easily scalable co- precipitation chemical approach. Al2O3 nanofluid was prepared at three volume concentration 1, 3 and 5%, while the Delafossite CuAl2O3 at 5%. The microstructure of as prepared delafossite CuAlO2 nanoparticles were dedicated by different common methods showed a mean particle size of 28 nm. Thermal properties of water-based nanofluid increased with increasing of a Cu loading level in CuAl2O3. The nanofluid viscosity increases with the augmentation of the nanoparticles and also with increasing the copper content in the delafossite structure. An experimental setup was designed to investigate the influence of the CuAlO2 delafossite nanofluid on both heat transfer and flow structure. A cavity was fabricated with two opposite copper plates. One plate was considered as a heat source subjected to constant heat flux while the other with lower temperature and the rest of sides are considered insulated. The Rayleigh number varied from 7.3 × 107 to 2.21 × 108. The effect of Rayleigh number, volume fraction and the type of nanoparticle were examined experimentally and numerically. The maximum augmentation in the average Nusselt number reaches 51% at Ra = 2.21 × 108 for ϕ = 5% for CuAlO2 for Cu = 5%wt comparing to Al2O3. Keywords: Turbulent, Natural convection, Delafossite nanofluid