Investigating the effect of different parameters on the rheological behavior of hybrid nano-lubricant containing MWCNT and CuO nanoparticles using response surface methodology (RSM)

Abstract

In this study, changes in the viscosity of MWCNT-CuO (40%-60%)/ 10 W40 hybrid nano-lubricant (HNL) were modeled and evaluated with the influence of independent parameters using response surface methodology (RSM). RSM with statistical mathematical techniques and appropriate modeling is one of the best methods for evaluating changes in viscosity in terms of independent parameters. Independent and effective parameters on viscosity include temperature (T), solid volume fraction (SVF) and shear rate (SR). Viscosity changes were investigated by presenting different models using 174 laboratory data and the best model among the different models with three parameters T, SR and SVF was introduced. The accuracy of the models was checked with R2, Adjusted R2, and Predicted R2 parameter values. The three-parameter model with parameter values R2 = 0.9992 Adjusted R2 = 0.9990 and Predicted R2 = 0.9986 has higher accuracy than other models. Using the optimal model, the process of viscosity changes was analyzed and investigated, and after evaluating the independent parameters, it was found that the effect of T on viscosity is greater than other parameters. The SR parameter has the least effect on viscosity changes. Also, the normal scatter diagram for the Quartic model for viscosity in terms of T, SVF and SR parameters is close to the bisector line and does not need a transfer function. The graph of the residual values according to the predicted values is in the range between + 3.7 and −3.7. Tthis shows that the accuracy of the selected model is satisfactory.