Effect of chain-like magnetite nanoparticle aggregates on thermal conductivity of magnetic nanofluid in magnetic field

[Display omitted] ► Simulated thermal conductivity enhancement ratio of magnetic nanofluids increased with increasing magnetic field for an engine oil based magnetite nanofluid. ► The observed thermal conductivity enhancement was related to the particle volume fraction. ► Simulated results were similar to measured data for the magnetic nanofluid in magnetic field. ► The thermal conductivity enhancement was due to the chainlike aggregates formation in magnetic nanofluids. This paper investigated the effect of chain-like magnetic nanoparticles aggregates on the thermal conductivity of magnetic nanofluids (MNFs) in magnetic field via a proposed model of thermal conductivity of MNFs. The anisotropic feature of thermal conductivity ratio was predicted based on the field induced chain-like magnetic nanoparticles aggregates in MNFs. It was indicated that for a magnetic field parallel to temperature gradient, the thermal conductivity component along the magnetic field was significantly enhanced due to the magnetic field induced chain-like magnetic nanoparticles aggregates. The experimental data of thermal conductivity enhancement along the magnetic field direction were similar to those predicted by the proposed model.