The Role of Liquid Layering on the Enhancement of Thermal Conductivity in Nanofluids

Liquid layering is considered to be one of the key mechanisms responsible for the remarkably high thermal conductivities exhibited by nanofluids. A number of models have been presented in recent years to quantify the effect of liquid layering. However, many of these models are either based on unrealistic assumptions or have been incorrectly formulated. In this study we propose a new, yet simple, model that resolves the shortcomings of earlier models. The new model is based on the Maxwell theory and takes into account the effect of nanolayering. The model was compared with several sets of experimental data on Copper Oxide-in-ethylene glycol, Copper Oxide-in-water, Alumina-in-water, and Gold-in-toluene. The results indicate that the contribution of nanolayering to the enhancement of thermal conductivity in nanofluids is relatively modest and as such cannot be solely responsible for the observed enhancements.