Numerical study of nanofluid heat transfer enhancement with mixing thermal conductivity models [Conference Object]

Abstract

Nanofluids has shown its possibility in enhancing heat transfer performance above its base fluids. This work presents a numerical study to analyze the nanofluid heat transfer enhancement using different theoretical models; the effective viscosity and the effective thermal conductivity models. The Maxwell, Brownian motion, and Yu and Choi models are considered as thermal conductivity models and the models are used in the simulation domain alternately, named the mixing models. The Al2O3-water nanofluids is chosen in this study and assumed to flow under laminar fully developed flow condition through a rectangular pipe as in a circuit application. The governing equations written in terms of the primitive variables are solved through an in-house program using the finite volume method and the SIMPLE algorithm. The results showed that different effective viscosity and thermal conductivity models play important roles, especially at wall surfaces where the convective heat transfer is enhanced effectively. Moreover, the small volume fractions, the nanofluid volume fractions from 0.01 to 0.03 can increase the heat transfer enhancement. Therefore, the volume fraction, the effective viscosity and the effective thermal conductivity at the wall region can be increased by increasing nanoparticle amount. This work can strongly support the literatures that the volume fraction, the effective viscosity and the effective thermal conductivity can enhance the heat transfer performance in the nanofluid flows not only with the single-phase model considered but also with the mixing models examined.