Heat transfer enhancement in turbulent tube flow using Al2O3 nanoparticle suspension

Purpose - To study the hydrodynamic and thermal behaviors of a turbulent flow of nanofluids, which are composed of saturated water and Al2O3 nanoparticles at various concentrations, flowing inside a tube submitted to a uniform wall heat flux boundary condition. Design/methodology/approach - A numerical method based on the "control-volume" approach was used to solve the system of non-linear and coupled governing equations. The classical kappa-epsilon Model was employed in order to model the turbulence, together with staggered non-uniform grid system. The computer model, satisfactorily validated, was used to perform an extended parametric study covering wide ranges of the governing parameters. Information regarding the hydrodynamic and thermal behaviors of nanofluid flow are presented. Findings - Numerical results show that the inclusion of nanoparticles into the base fluid has produced an augmentation of the heat transfer coefficient, which has been found to increase appreciably with an increase of particles volume concentration. Such beneficial effect appears to be more pronounced for flows with moderate to high Reynolds number. In reverse, the presence of nanoparticles has induced a rather drastic effect on the wall shear stress that has also been found to increase with the particle loading. A new correlation, Nu(fd) = 0.085 Re-0.71 Pr-0.35, is proposed to calculate the fully-developed heat transfer coefficient for the nanofluid considered. Practical implications - This study has provided an interesting insight into the nanofluid thermal behaviors in the context of a confined tube flow. The results found can be easily exploited for various practical heat transfer and thermal applications. Originality/value - The present study is believed to be an interesting and original contribution to the knowledge of the nanofluid thermal behaviors.