Experimental investigation of viscosity and thermal conductivity of suspensions containing nanosized ceramic particles

Purpose: In this study we report measurements of effective thermal conductivity by using 3ω method and effective viscosity by vibro-viscometer for SiO2-water and Al2O3-water nanofluids at different particle concentrations and temperatures. Design/methodology/approach : The effective thermal conductivity of nanofluids is measured by a technique based on a hot wire thermal probe with ac excitation and 3ω lock-in detection. There is presented an experimental study of thermal conductivity and viscosity of nanofluids. It was investigated Alumina and Silica nanoparticles in water with different particle concentrations. Findings: Measured results showed that the effective thermal conductivity of nanofluids increase as the concentration of the particles increase but not anomalously as indicated in the majority of the literature and this enhancement is very close to Hamilton-Crosser model, also this increase is independent of the temperature. The effective viscosities of these nanofluids increased by the increasing particle concentration and decrease by the increase in temperature, and can not be predicted by Einstein model. Practical implications: The results show that for our samples, thermal conductivity values are inside the limits of (moderately lower than) Hamilton-Crosser model. Originality/value: Experiments at different temperatures show that relative thermal conductivity of nanofluids is not related with the temperature of the fluid.