Effect of Al2O3–SiO2/Water Hybrid Nanofluid Filled in a Square Enclosure on the Natural Convective Heat Transfer Characteristics: A Numerical Study

Abstract

In this study, heat transfer enhancement by natural convection Al2O3/water mono and Al2O3–SiO2/water hybrid nanofluid in an enclosure cavity have been performed utilizing the finite element method. For numerical computations, the homogeneous nanofluid approach was considered. The cavity was heated from the left vertical wall and cooled from the right vertical wall while the top and bottom walls were taken as adiabatic. The effects of some related factors such as the Rayleigh number (103 ≤ Ra ≤ 106) and nanoparticles’ volume fraction (0 ≤ φ ≤ 0.05) on the heat transfer by natural convection were examined. To discuss fluid characteristics of mono and hybrid type nanofluid under natural convection effect, the obtained results were presented as streamlines and isotherms. Also, variations of local and average Nusselt numbers were examined in detail. It was obtained that an increase in the nanoparticle volume fraction leads to the enhancement of convective heat transfer for all Rayleigh numbers. It was also indicated that the highest increment in heat transfer by convection occurs in the nanoparticle volume fraction of 2% for Al2O3/water and 4% for Al2O3–SiO2/water. The present study results are also consistent with the literature results.