New analytical models to investigate thermal conductivity of nanofluids.

Nanofluids are identified suitable for micro and nano scale heat transfer applications where a high heat flux is required. These fluids are still in their early developmental stage and the exact heat transfer mechanism in them is not known yet. Due to this situation, there exists no suitable theoretical model for predicting the thermal conductivity of nanofluid. In this paper two new models for nanofluid thermal conductivity are developed. The first model which is based on Weber formula is used to predict the nanofluid thermal conductivity. The thermal conductivity of Al2O3/water, CuO/water, TiO2/water and TiO2/ethylene glycol nanofluids predicted by this model were compared with the published experimental data. The second model is used to analyze the influence of the effects of particle shape, nanolayer thickness and Brownian motion in enhancing thermal conductivity of nanofluids.