RHEOLOGICAL BEHAVIOUR AND HEAT TRANSFER OF Al_2O_3 NANOPARTICLES DISPERSED IN ETHYLENE GLYCOL AND WATER MIXTURE

摘要

This paper presents an experimental investigation of rheological and thermal transfer properties of Al_2O_3 nanoparticles suspended in 45:55 (by volume) ethylene glycol and water mixture. The linear relation between shear stress and shear rate at the same temperature shows that the Al_2O_3 nanofluid exhibits Newtonian behavior. The viscosity of nanofluid considerably increases with the enhancement of particle volume fraction, and decreases with increasing temperature from 10°C to 60°C. The enhanced thermal conductivity ratios of the nanofluids with the volume fraction 1% and 3% were measured. The results show that the absolute thermal conductivities increase with the increasing temperature, while the enhanced ratios are almost constant It maybe due to the decrease of the Brownian motion velocity and the ratio of the effective area to the volume, arising from the agglomeration of nanoparticles.