Effects of nanoparticle clustering and alignment on thermal conductivities of Fe3O4 aqueous nanofluids

Thermal conductivities of Fe3O4 aqueous nanofluids were studied. The results show that Fe3O4 nanofluids have higher thermal conductivities than other oxide aqueous nanofluids at the same volume fraction. The experimental values are higher than those predicted by the existing models. The abnormal thermal conductivities of Fe3O4 nanofluids are attributed to the observed nanoparticle clustering and alignment. (c) 2006 American Institute of Physics.