Mean-Field Bounds and the Classical Nature of Thermal Conduction in Nanofluids

The initial promise of nanofluids as an advanced, nanoengineered coolant has been tempered in the recent years by a conspicuous lack of consensus on its thermal conduction mechanism. Several new mechanisms have been hypothesized in the recent years to characterize the thermal conduction behavior in nanofluids. In this presentation, we show that a large set of nanofluid thermal conductivity data is enveloped by the well-known Hashin and Shtrikman (H-S) mean-field bounds for inhomogeneous systems. The thermal conductivity in nanofluids, therefore, is largely dependent on whether the nanoparticles stays dispersed in the base fluid, form linear chain-like configurations, or assume an intermediate configuration. The experimental data, which is strikingly analogous to those in most solid composites and liquid mixtures, provides a strong evidence for the classical nature of thermal conduction in nanofluids.