Theoretical investigation of nanoparticles aggregation effect on Water-alumina laminar convective heat transfer

This paper is related to a theoretical study to analyze the nanoclusters and their structural effects on the laminar forced convection heat transfer coefficients of Al2O3-water nanofluids in a circular tube. In this study, Eulerian/Eulerian two-phase model is used with regard to nanoclusters Brownian motion and their fractal structure. The hydrodynamic effects, nanofluid concentration, size, and fractal structure of nanoclusters were investigated. Modeling results were compared to the experimental data and it was shown that the numerical predictions agree well with the experimental data. Based on the results, convective heat transfer coefficient increases by increasing the nanoparticles concentration and reducing of the nanoclusters fractal dimension. The results clearly showed that Brownian motion has a significant effect on the convective heat transfer coefficient enhancement of Al2O3/water nanofluids.