Modeling Thermophoresis (Soret Effect) in Nanofluids

M. Eslamian, M. Ziad Saghir
Texas A&M Univeristy- Corpus Christi, US

Keywords: nanofluids, thermophoresis, heat transfer augmentation

Summary:

Thermophoresis plays an important role in forced and natural convection in channels and enclosures when nanofluids are used instead of pure fluids. Therefore, in order to be able to estimate the extent and role of thermophoresis in heat transfer augmentation, it is essential to know the Soret coefficient. One objective of this work, therefore, is to investigate whether reliable expressions exist for the estimation of thermophoresis data. As the second objective of this work we try to show similarities between thermophoresis of nanoparticles and macromolecule with thermodiffusion of binary mixtures. To this end, a nonequilibrium thermodynamics-based expression primarily developed for the estimation of thermodiffusion factor in binary mixtures is extended and applied to thermophoresis in nanofluids. A hydrodynamics-based expression developed by Epstein for gases and revisited by Brenner, and the nonequilibrium thermodynamic-based expression developed here, are used to estimate the thermophoretic velocity in nanofluids.