Ethylene glycol based silicon nitride nanofluids: An experimental study on their thermophysical, electrical and optical properties

This paper presents the results of an experimental investigation into the basic physical properties of silicon nitride (Si3N4) - ethylene glycol (EG) nanofluids. Samples with various volume fractions of nanoparticles were prepared using a two step method. Basic physical properties such as viscosity, thermal conductivity, electrical conductivity and optical properties were examined. A rheological investigation showed that silicon nitride ethylene glycol nanofluids present non-Newtonian shear thinning behavior. Thermal conductivity indicates a linear dependence on the volume fraction. As well as thermal conductivity increasing with increasing volume fraction, electrical conductivity is also related with the volume fraction of nanoparticles, and this relation is both very strong and nonlinear. The refractive index increases linearly with the volume fraction of nanoparticles in these nanofluids. Finally, it has been found that absorption of examined nanofluids is improved as the volume fraction of nanoparticles increases, especially in the UV region.