Experimental study on the influence of volume concentration on natural convection heat transfer with Al2O3-MWCNT/water hybrid nanofluids

Abstract

Recent research has focused on combining multiple types of nanoparticles with a base fluid, a process known as the hybridisation of nanofluids. Studies showed that hybrid nanofluids demonstrated improved rheological and thermal properties compared to mono nanoparticle nanofluids. In this study, alumina–multiwalled carbon nanotube/water hybrid nanofluid was prepared using a two-step procedure at a percentage weight ratio of 10:90 Al2O3: MWNCT at various volume concentrations of 0.00, 0.05, 0.10, 0.15, and 0.20 vol%. The natural convection of the formulated hybrid nanofluid was experimentally studied inside a square cavity with an aspect ratio of 1. An exhaustive investigation on the influence of volume concentration of hybrid nanofluid on natural convection heat transfer was performed. Results showed that an increase in volume concentration improved the heat transfer to an optimum value of 49.27% enhancement, at 0.10% volume concentration in comparison to the base fluid. However, a further increment of volume concentration led to a deterioration of natural convection heat transfer. There is evidence from this study that hybrid nanofluids offer an edge over traditional heat transfer fluids. It is concluded that the application of Al2O3-MWCNT/water hybrid nanofluid in a square cavity demonstrated enhanced natural convection heat transfer.