Experimental investigations and theoretical determination of thermal conductivity and viscosity of TiO2–ethylene glycol nanofluid

Experimental and theoretical investigations of effective thermal conductivity and effective dynamic viscosity of TiO2-ethylene glycol nanofluid are presented in this paper. The nanofluid was prepared by a two step method; synthesizing TiO2 nanoparticles using ultrasound assisted chemical precipitation method and dispersing them in pure ethylene glycol using an ultrasonicator. TiO2-ethylene glycol nanofluid with a nominal diameter of 5-nm at different volume concentrations (0-7%) at room temperature was used in the current study. The thermal conductivity and viscosities of nanofluids are measured and it is found that both thermophysical parameters (thermal conductivity and viscosity) show increasing trends with addition of nanoparticles to base fluids and the thermal conductivity increase is substantially higher than the viscosity at higher volume fraction. The Bruggeman and Einstein models show reasonably good agreement with our experimental results of thermal conductivity and viscosity respectively.