Dispersion and thermal conductivity of Al2O3 and TiO2 binary nanofluids

The dispersion stabilities and thermal conductivities of Al2O3 and TiO2 ammonia water nanofluids are investigated by the absorbency index methods and transient double-hot-wire method, respectively. The results show that the dispersion stabilities of the two kinds of binary nanofluids are greatly improved by adding surfactants or increasing the ammonia content. The effective thermal conductivity ratios of the two kind of binary nanofluids increase with the increase of the content of nano-particles. It is the same with the increase of the ammonia content. The thermal conductivity will decrease with the rising of storage time by the role of natural sedimentation. The thermal conductivity of TiO2 nanofluid is more insensitive to the storage time than Al2O3 nanofluid because of its better dispersion stability