Study of surface tension behavior of water-ethylene glycol /nano Al۲O۳ –nano graphene hybrid nanofluid

Nanofluids resulting from the distribution of nanoscale particles in the base fluid are a new generation of fluids with very high potential in industrial applications. In this research, experiments were conducted to investigate the effect of temperature and concentration of nanoparticles on the surface tension of Graphene-Al۲O۳/Ethylene Glycol-Water hybrid nanofluid at low and sub-zero temperatures. Nanoparticles were characterized by Transmission Electron Microscopy (TEM) and X-ray diffraction(XRD) methods. Hybrid nanofluids were prepared at room temperature by adding nanoparticles with different volume fractions (۰.۰۵-۲.۵%) to base fluid containing a combination of water and ethylene glycol (W:EG/۵۰:۵۰ vol%) and oleic acid and sodium dodecyl sulfonate as surfactants. The surface tension of the hybrid nanofluids were experimentally assessed for temperatures between ۲۵۳ and ۳۰۳K. Experimental results show that the surface tension dependence on nanoparticle concentration has acritical limit. The hybrid nanofluid surface tension decreases as the surfactant is added to the base fluid and decreases with the elevation of temperature. The surface tension improvements are observed approximately ۴۸.۲۵%, ۴۷.۸۴% and ۵۴.۳% at the concentration of ۲.۵%, ۲% and ۲% vol. for temperatures of ۲۵۸.۱۵K, ۲۶۸.۱۵K and ۲۸۳.۱۵K, respectively.

Keywords:

Al۲O۳ nanoparticles , Graphene nanoplates , Hybrid nanofluids , Surface tension , Concentration effect , Sub-zero temperatures.