RESUMO
The science of nanofluids is still fairly new and due to this, the properties of many nanofluids are yet to be explored. Therefore, equations for precise calculations in this field are not available yet. For this reason, as a thermophysical property of an MWCNT (40%)/TiO2 (60%) hybrid nanofluid (HNF), in this research, the viscosity of HNF with 10W40 oil as the base fluid, in a temperature range of T = 5-55 °C and with solid volume fractions of SVF = 0.5-1% is studied and modelled. The viscosity of the nanofluid was examined in different conditions. Lab data were used to model dynamic viscosity of HNF using the Response Surface Methodology (RSM), and first, second, third, fourth and fifth-order models were created. An analysis of the statistical parameters concluded that with a correlation coefficient of 0.9999, the fifth-order model is the best performer. The trend of alterations in viscosity shows that an increase in temperature has great effects on viscosity, and its influence is also more important than that of changes in shear rate (SR) and SVF. Optimal viscosity was also calculated and was equal to 158.1 mPa.sec at SVF = 0.05 %, SR = 11,997 s- 1 and T = 14.97 °C.