Experimental study and development of mathematical model using surface response method to predict the rheological performance of CeO2-CuO/10W40 hybrid nanolubricant

Abstract

In this study, the rheological behavior of CeO2-CuO/10W40 hybrid nanolubricant with several volume fractions (VFs) over the range of 0.25–1.5 vol%, temperatures over the range of 5–55 °C, and shear rates varying from 20 to 1000 rpm are experimentally assessed. The viscosity measurements at various shear rates (SRs), VFs, and temperatures demonstrated that the 10W40 engine oil and hybrid nanolubricant behave non-Newtonian. The experimental results show that the maximum viscosity reduction with increasing SR occurs at T = 45 °C and VF = 1.25 %, which its value is about 30.28 %. The experimental findings demonstrate that an increase in temperature results in reduced viscosity (between 91.84 % and 93.10 %) while the viscosity increases with increasing VF. To forecast the experimental data, two correlations (functions of three variables: temperature, VF, and SR) are presented based on experimental data using curve fitting and the response surface method (RSM). The results show that good concordance exists between experimental data and correlation results to estimate the viscosity of CeO2-CuO/10W40 hybrid nano-lubricant. Additionally, the correlation developed by the RSM is more straightforward than one derived from curve fitting. This new hybrid nano-lubricant can be used as a coolant in the automotive industry.