Thermal distribution in annulus with nanofluid

Abstract

Nanofluids are basically nanoparticles in base fluids. Nanofluids have unique features different from conventional solid-liquid mixtures in which µm sized particles of metals and non-metals are dispersed. Due to their excellent characteristics, nanofluids find wide applications in enhancing heat transfer. Waterbased nanofluid containing various volume fractions of Cu, Ag, Al2O3 and TiO2 nanoparticles is used. The addition of the different types and different volume fractions of nanoparticles were found to have adverse effects on heat transfer characteristics. For high values of Rayleigh number and high L/D ratio, nanoparticles with high thermal conductivity cause significant enhancement of heat transfer characteristics. On the other hand, for intermediate values of Rayleigh number, nanoparticles with low thermal conductivity cause a reduction in heat transfer. For Ra=103 and Ra=105 the addition of Al2O3 nanoparticles improves heat transfer. However, for Ra=104, the addition of nanoparticles has a very minor effect on heat transfer characteristics