Experimental evaluation of MWCNT–Al2O3 (40–60%)/5W50 hybrid nanofluid and comparison with MWCNT–Al2O3 (35–65%)/5W50 hybrid nanofluid with focus on thermophysical properties and cost performance index
Department of Mechanical Engineering, Imam Hossein University, Tehran, Iran
2 School of Chemistry, Damghan University, 36716-41167, Damghan, Iran
Accepted: 24 September 2020
Published online: 13 October 2020
The viscosity of MWCNT–Al2O3 (40–60)/5W50 hybrid nanofluid (NF) has been investigated. According to the results at different volume fractions (VFs) and temperatures, it possesses a behavior like non-Newtonian fluids. In this paper, we first compare MWCNT–Al2O3 (40–60%)/5W50 hybrid NF with MWCNT–Al2O3 (35–65%)/5W50 hybrid NF with focus on viscosity and cost performance index. Investigations were carried out for two shear rates (SR) of 3999 and 5332 (1/s). The decrease in viscosity at the SR of 3999 and in the VF of 1% at temperatures between 5 and 45 °C was 84%, and the SR of 5332 at 15 °C increased by 24%. Sensitivity was also studied, and at temperatures of 5–45 °C at a VF of 0.05%, this value was about 0.2%. This low viscosity sensitivity is very effective in improving the application of NFs in various engineering systems. A new empirical relation to anticipate the NF viscosity in accordance with the experimental results is also presented. The coefficient of determination (R2) for the mentioned relation is 0.9982, indicating the accuracy of the presented empirical relation to predict the NF viscosity at the tested temperature and concentration ranges.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020