Evaluating the effects of different parameters on rheological behavior of nanofluids: A comprehensive review

Experimental investigations on viscosity and density of eco-friendly MoS2-sesame oil nano-lubricants and its influence on pumping power

In this study, the rheological behavior and density of MoS₂/sesame oil based nano-lubricants are experimentally investigated. The transmission electron microscopy and x-ray diffraction technique were utilized to confirm the morphology of the MoS₂nano particles. The experimental measurements are carried out at temperature varying from 313 to 393 K, shear rate ranging from 10to 70 s^-1and solid volume fraction ranging from 0.2% to 1.2%. For the both nano-lubricants and pure lubricant, shear thinning behavior is observed. The influence of temperature and nanoparticle concentration on viscosity and density of nano lubricants are examined. The viscosity and density of nano-lubricants increased with an increase of solid volume fraction, while, it decreased with an increase in temperature. Moreover, the effect of nano particle concentration on the pumping power of lubricant flow are discussed. Finally, an experimental correlation was developed for predicting the viscosity of MoS₂/sesame oil based nano-lubricant.

Thermal Conductivity Calculations for Nanoparticles Embedded in a Base Fluid

The Prasher analytical model was used for calculating the thermal conductivity of the embedded nanoparticles of Al2O3, CuO, ZnO, and SiO2 in conventional fluids, such as water and ethylene glycol. The values that were obtained were used in the nanofluid theoretical models for comparison with experimental data, where good agreement was obtained. Liang and Li’s theoretical model was also used to calculate the thermal conductivity of these nanoparticles, where the results agreed with those obtained using the Prasher model. The effect of the liquid nanolayer thickness around the nanoparticles that was used to enhance the effective thermal conductivity of nanofluids was explained. The role of the nanoparticles’ surface specularity parameter, which was size-dependent, was clarified. This theoretical trend provides a simple method for estimating the thermal conductivity of nanoparticles and nanofluids.