Etude numerique du transfert thermique des 'nanofluides' dans un tuyau chauffe uniformement a la paroi

In the present work, the hydrodynamic and the thermal behaviors of a laminar and turbulent forced convection flow of nanofluids inside a uniformly heated tube have been numerically investigated. Results, as obtained for water-gammaAl 2O3 and Ethylene-glycol-gammaAl2O 3 mixtures, have eloquently revealed that the inclusion of nanoparticles has produced a considerable improvement of the heat transfer coefficient, which clearly becomes more important with an augmentation of the particle concentration. However, the presence of particles has induced drastic effects on the wall shear stress that remarkably increases with the particle volume concentration. Among the nanofluids studied in laminar flow, Ethylene-glycol-gammaAl 2O3 clearly offers higher heat transfer enhancement; it is also the one for which more pronounced adverse effects on the wall friction can be expected. Results have also shown that, in general, the heat transfer enhancement also increases considerably with an augmentation of the flow Reynolds number. Different correlations have been provided for computing the Nusselt number for the nanofluids in terms of the Reynolds and Prandtl numbers respectively for the constant wall heat flux in laminar and turbulent flow and for the constant wall temperature in a laminar flow case.