Investigation of the effects of various parameters and the evaluation of the optimal rheological of MWCNTs based hybrid nanolubricant and providing an optimal model

Abstract

The rheological behavior of MWCNT-Al2O3 (10%−90%) / SAE40 oil hybrid nanofluid (HNF) is done with using RSM statistical method in this study. The investigation is carried out under conditions of temperature within the range T = 25–50 °C, solid volume fraction between SVF= 0.0625 until 1% and shear rate in the range of SR= 666.5–9331 s−1. In this study, three different models of 2FI, Quadratic and Cubic are evaluated using correlation indices and quality determination charts. Cubic model is chosen as the optimal model among these models and for optimization, the viscosity of HNF is used. The values of R2, C.V, C.D, P-value and Std. Dev correlation indices for the selected model are 0.9996, 1.04, −3.785 <C.D %< 4.333, 2.55e-264 and 2.12, respectively. The effects of SVF, temperature and SR parameters on viscosity are investigated. It is found that SR has the least effect and temperature has the most effect on the viscosity of HNF. Lubrication is performed for cold environment conditions. The parameters of SVF, SR, temperature and viscosity are considered at the minimum value. After performing the optimization process by DOE, the most optimal mode for the HNF viscosity is in T = 35.210°C, SVF= 0.063%, SR= 666.511 s−1 and the viscosity is 191.450 mPa.sec.