Experimental determination of thermophysical properties of nanofluids containing spherical alumina nanoparticles

In order to study the heat transfer performance of nanofluids and use them in practical applications, it is necessary first to study their thermophysical properties. In this paper the four main thermophysical properties, i.e. the density, the specific heat capacity, the thermal conductivity, and the viscosity of Al2O3-water nanofluids have been determined experimentally. The Al2O3 nanoparticles with a nominal diameter of 40 nm were dispersed in distilled water as base fluid. The data are collected for temperatures ranging from 20 to 60 ºC and for the nanoparticle volume fractions ranging from 0.1% to 2.0%. Results show that the measured density and specific heat capacity are in good agreement with the mixing theory and the thermal equilibrium model, respectively. Moreover, measured viscosity and thermal conductivity of nanofluids are higher than the values of the base fluid. The thermal conductivity and the dynamic viscosity ratios of nanofluids increase with increasing particle volume concentration and the effect of temperature on these ratios is little. According to the experimental data two correlations are proposed for calculating the thermal conductivity and dynamic viscosity of nanofluids which depend on both the temperature as well as particle volume concentration

Keywords:

nanofluids , density , specific heat capacity , thermal conductivity , viscosity