Thermal conductivity measurement of spinel-type ferrite MnFe2O4 nanofluids in the presence of a uniform magnetic field

In this work, the evaluation of thermal conductivity of MnFe2O4/water nanofluids in attendance of magnetic field is conducted. The MnFe2O4/water is synthesized and prepared in different nanoparticles concentrations, from 0.25% to 3%. The thermal conductivity of nanofluids has been determined at various nanofluid concentrations and temperatures with and without magnetic field. It is found that the thermal conductivity of nanofluid remarkably improves with augmentation of solid volume fraction. Moreover, by incrementing the nanofluid temperature, the thermal conductivity improves under no magnetic field, while it decreases at higher temperatures in attendance of magnetic field. The highest thermal conductivity improvement is achieved 26.4% at 60 °C and 3 vol.% of nanoparticles under no magnetic field and 36.5% under 400 G magnetic field which occurs at 20 °C and 3 vol.% of nanoparticles. Furthermore, an empirical correlation is derived to estimate thermal conductivity of MnFe2O4/water nanofluid in terms of magnetic field intensity, volume concentration, and temperature.