Enhancement of thermal conductivity of magnetic nanofluids in magnetic field

This paper investigated the enhancement of thermal conductivity of engine oil based magnetite (Fe
3
O
4
) nanofluids, which were prepared via a co-precipitation method with and without ultrasound assistance, in the presence of external magnetic field. The thermal conductivity was determined using a thermal constants analyzer. Effects of particle size, particle volume fraction and magnetic field on the thermal conductivity ratio of the magnetic nanofluids were analyzed. The results showed that the thermal conductivity could be enhanced with the finer magnetite particles used in the nanofluid at a greater particle volume fraction. In addition, the thermal conductivity enhancement was found to be related to magnetic field parallel to temperature gradient.