Experimental study on synthesis, stability, thermal conductivity and viscosity of Cu–engine oil nanofluid

Abstract

In this study, a colloidal suspension consists of Cu nanoparticles and engine oil has been made by a one- step method known as Electrical Explosion of Wire (E.E.W) in three different weight concentrations of 0.2%, 0.5% and 1%. After studying physical properties of the applied nanofluids via high resolution transmission electron microscopy and measuring zeta potential for the stability analysis, thermo-physical properties such as thermal conductivity and viscosity, have been experimentally studied. Measured data of thermal conductivity and viscosity of applied nanofluids have been compared to the predicted ones through the proposed correlations for thermal conductivity and viscosity of oil based nanofluids and acceptable agreements between the two have been achieved. The range of thermal conductivity of higher weight concentration was measured to be from 0.153 to 0.17 (W/m. K) in the temperature range from 40 C to 100 C, while pure engine oil exhibits a decreasing trend in contradictory. Secondly, viscosity variations through capturing Newtonian or non- Newtonian behavior of utilized nanofluids has been investigated. The viscosity range for higher weight concentration nanofluid was observed from 235 cP to 35 cP in the applied temperature range. Finally, thermal conductivity and viscosity enhancements of 49% and 37% were observed for 1% weight fraction of utilized nanofluids.