Eur. Phys. J. Plus (2020) 135: 817
https://doi.org/10.1140/epjp/s13360-020-00807-9

Regular Article

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

¹ Department of Mechanical Engineering, Imam Hossein University, Tehran, Iran
² School of Chemistry, Damghan University, 36716-41167, Damghan, Iran

^b s.alidoust1369@gmail.com

Received: 23 June 2020
Accepted: 24 September 2020
Published online: 13 October 2020

Abstract

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.