Experimental study of rheological characteristics of MWCNT-Al2O3 (40:60) / SAE50 hybrid nano-lubricant to identify optimal lubrication conditions and post-processing of results using the response surface method
Mohammad Hemmat Esfe, Saeed Esfandeh, Soheyl Alidoust, Davood Toghraie
Abstract
In this study, the rheological behavior of MWCNT-Al2O3 (40:60)/SAE50 hybrid nano-lubricant was studied to identify the maximum drop, the maximum increase in viscosity (μnf), as well as how the parameters of temperature, ϕ and shear rate (γ˙) affect the μnf. Various methods theoretically show that the nano-lubricant has a flow of pseudo-plastic non-Newtonian fluids. Statistical reports show that the highest increase and decrease in μnf of nano-lubricant compared to the base fluid in ϕ = 1%, T = 30 °C and γ=˙ 6665 s−1 (equivalent to high engine speed) and ϕ = 0.0625%, T = 25 °C and γ=˙ 3999 s−1 (equivalent to low engine speed) are occurred, which are equal to 38.76% and −5.14%, respectively. To predict the dependent variable data, a three-variable-quadratic model was presented with the RSM method with an R-Squared = 0.9997. The margin of deviation for data was determined in the range of −2.41% <MOD <3.13%. Using numerical simulation, it was found that with increasing the ϕ, the pressure drop of the flow and the applied shear stress to the wall of the pipe increase.