Contribution of Brownian Motion in Thermal Conductivity of Nanofluids

As a hot research topic nanofluids have attracted great interest from researchers worldwide. Although nanofluids are found to exhibit higher thermal conductivity compared to their base fluids, the underlying mechanisms for the enhancement are still debated and not fully understood. In addition, there has been little agreement among different studies and no widely accepted model is also available for the prediction of the effective thermal conductivity of nanofluids. In this study, an improved Brownian motion-based combined thermal conductivity model is reported and a renovated Brownian motion term is used in this model. Besides the Brownian motion of nanoparticles, this model also takes into account several other important factors such as particle size interfacial nanolayer and fluid temperature that are believed to intensify the enhancement of the effective thermal conductivity of nanofluids. The present model shows reasonably good agreement with the experimental results of various aqueous nanofluids and gives better predictions compared to classical and recently developed models used for nanofluids.