Étude des transferts thermiques convectifs avec des nanofluides hybrides.

Abstract

This thesis's work contributes to the numerical study of mixed convection and entropy generation in two different configurations filled with simple and hybrid nanofluids. Two computational codes (Ansys-Fluent 18 and FORTRAN) have been used to solve the governing equations based on the finite volume method. The numerical results obtained were validated with other works found in the literature, and a good agreement was obtained. We present three parts regrouping the studied configurations: The first part consists in presenting a numerical study in (3-D) of mixed convection and entropy generation inside a cubic cavity that deals with the comparison between a simple nanofluid (Al2O3/water) and a hybrid nanofluid (Al2O3-Cu/water). This configuration contains a heat source placed on the bottom wall of the cavity. The effects of Reynolds number Re, the volume fraction of solid nanoparticles and displacement of the heat source were discussed. Two correlations have been developed to predict the variation of the average Nusselt number as a function of the chosen parameters. The second part deals with two-phase laminar mixed convection in a cubic cavity containing a heat source; the flow is the nanofluid (Al2O3-/water). This study used a twophase mixing model approach to demonstrate the effects of Reynolds number Re, and the volume fraction of solid nanoparticles. The third part examines the single-phase study of mixed convection and entropy generation inside a porous vertical cylinder filled with alumina (Al2O3) and copper oxide (CuO) nanoparticles in the presence of pure water with different Reynolds number Re, Richardson number, Darcy number, the volume fraction of solid nanoparticles and porosity of the porous medium. Four correlations were developed to predict the variation of the average Nusselt number (Numoy) and the total entropy generation (Stot).