Experimental investigation on the heat transfer properties of Al2O3 nanofluids using the mixture of ethylene glycol and water as base fluid

This paper presents an experimental investigation of rheological and heat transfer properties of Al2O3 nanofluids based on the mixture of 45 vol.% ethylene glycol and 55 vol. % water. The Al2O3 nanofluids (volume fraction φ = 0.02) over 45 °C exhibit Newtonian behaviors, below 45 °C, they will be non-Newtonian fluids. The enhanced thermal conductivity ratios of the nanofluids with the volume fraction 1.0%, 2.0% and 3.0% are 3.8%, 7.7%, and 11.6% respectively, slightly larger than those predicted by the classic theoretical models. The heat transfer coefficients of the nanofluids with 1.0 vol.% and 2.0 vol.% have been found an increase up to 57% and 106%, respectively, when the Reynolds number is 2000.