Experimental investigation of the effect of an external magnetic field on the thermal conductivity and viscosity of Fe3O4–glycerol

Thermophysical properties, such as thermal conductivity and viscosity, of magnetic nanofluids (MNFs) can be enhanced by applying external magnetic fields. Such property enhancement can be beneficial for having a non-contact control of heat transfer rates in many applications such as cooling of electronic devices, heating mediator for targeted cancer treatment, drug delivery, and heat transfer medium in energy conversion systems. In this study, a detailed experimental investigation has been carried out to measure the thermal conductivity and viscosity of a magnetic nanofluid under the influence of a uniform external magnetic field. The MNF (i.e., glycerol–Fe3O4) is prepared by dispersing Fe3O4 magnetic nanoparticles in glycerol at different volume fractions of nanoparticles (i.e., φ = 0.5, 1.0, 1.5, 2.0, and 3.0%). The experimental results showed that the viscosity linearly increased with the increase in volume fractions while significantly decreased with the increase in temperature. With respect to the viscosity measurement, the maximum ratio revealed a value of 7.2 for 3.0% volume fraction and 50 °C subjected to 543 [G] magnetic field. Also, a 16.9% thermal conductivity enhancement was achieved when φ = 3.0% at 40 °C under 543 [G] magnetic field. Using the experimental results, a nonlinear model was developed as a function of temperature (T), magnetic field (B), and volume fractions of nanoparticles (φ) to predict the thermal conductivity of glycerol–Fe3O4. The proposed model provided satisfactory performance with an R2 value of 0.961, MSE value of 0.00015, and MAE value of 0.00932.