Experimental determination of viscosity of water based magnetite nanofluid for application in heating and cooling systems

• Preparing Magnetite nanofluids with solid volume fractions up to 3%.
• Measuring viscosity in temperature range of 20–55 °C using Brookfield Viscometer.
• Maximum viscosity enhancement occurred at volume fraction of 3% and was 129.7%.
• Proposing new correlation to predict the viscosity of Fe3O4/water nanofluid.

In this paper, experimental determination of dynamic viscosity of water based magnetite nanofluid (Fe3O4/water) was performed. The viscosity was measured in the temperature range of 20–55 °C for various samples with solid volume fractions of 0.1%, 0.2%, 0.4%, 1%, 2% and 3%. The results showed that the viscosity considerably decreases with increasing temperature. Moreover, the viscosity enhances with an increase in the solid volume fraction, remarkably. The calculated viscosity ratios showed that the maximum viscosity enhancement was 129.7%. Using experimental data, a new correlation has been proposed to predict the viscosity of magnetite nanofluid (Fe3O4/water). A comparison between the experimental results and the correlation outputs showed that the proposed model has a suitable accuracy.