Thermal Conductivity of Nanofluid with Magnetic Nanoparticles

The thermal conductivities of Fe3O4 and Al2O3 nanofluids with the viscous base fluid composed by various fluids are investigated in this study. In order to change the viscosity of mixed fluid, the volumetric fractions between two fluids in the mixed fluid are varied. Measured values of thermal conductivity of nanofluids gradually approach the values predicted by Maxwell equation with increasing the viscosity. Our measured results demonstrate that Brownian motion of suspended magnetic particles could be an important factor that enhances the thermal conductivity of nanofluids, but it has little effect for suspended Al2O3 nanoparticles. It also indicates that the conduction part of prediction model can be obtained from Maxwell prediction.