The effective thermal conductivity of nanofluids based on the nanolayer and the aggregation of nanoparticles

Nanofluids, which are produced by dispersing nanoparticles into conventional fluids, exhibit anomalously high thermal conductivity. Most experiments demonstrated that the nanolayer surrounding the solid particles and the clusters formed by nanoparticles' aggregation may play an important role in the enhancement of thermal conductivity of nanofluids. By taking into account the nanolayer and nanoparticles' aggregation, a new model for the effective thermal conductivities of nanofluids is proposed. This model is expressed as a function of the thickness of the nanolayer, the nanoparticle size, the nanoparticle volume fraction and the thermal conductivities of suspended nanoparticles and base fluid. The theoretical predictions on the effective thermal conductivities of nanofluids are shown to be in good agreement with the available experimental data.