Résumé:
Heat transfer is very important for good design and reliable operation of a system.
Reliability and system performance are highly dependent on the operating temperature,
in particular, in electronic equipment. Several cooling methods have been proposed in
order to improve the heat transfer. These techniques include two: which consists in
grafting blades offering a greater contact surface with the environment; and which
consists of using nanofluids comprising metallic particles or carbon nanotubes. The
latter is currently present the best solution.
In the first part of the thesis, a numerical study of 2D laminar mixed convection in
a horizontal channel with three fins nanofluid has been carried out made. The influence
of Reynolds and Richardson numbers and concentration of nanoparticles (Al2O3, Cu, Ag
and TiO2) dispersed in a base fluid (water), on the flow and thermal fields is presented.
A computer code in Fortran, based on finite volume method was used to simulate 2D
flow with heat transfer. The results indicate that the addition of nanoparticles in pure
water can improve the cooling performance, in particular, low Richardson number. The
influence of the solid volume fraction on increasing the heat transfer is more sensitive to
higher values of Reynolds number. Although, the addition of nanofluids (TiO2 and
Al
2O3) also increases heat transfer, their influence is not important for Cu-Ag-water and
water.
The second part is to find an optimal geometry for good cooling. Numerical
calculations were carried out using the software ""FLUENT 6.3"" to simulate 3D laminar
mixed convection flow in a channel containing fins with nanofluid. The effects of
Reynolds number, height, and distance between the fins are presented and discussed.
