Water-ZnO nanofluid saturated porous medium for free convective cooling of a cubical electronics contained in a hemispherical cavity

A cubical electronic component held in a hemispherical cavity is cooled through a saturated ZnO-H2O nanofluid porous medium. According to the intended application, the base of the cavity could be either horizontal with dome facing upwards or vertical. The power generated by the device during its operation leads to high Rayleigh number ranging between 5.21x10 ⁷ and 7.29x10 ¹⁰ , while the volume fraction of the monophasic nanofluid varies between 0 (pure water) and 5%. Several values of the thermal conductivity of the porous medium were considered. The latter were measured through the Transient Plane Source method. The governing system solved by means of the volume control method associated to the SIMPLE algorithm allows to qualify the natural convective and pure conductive phenomena occurring in the enclosure. They are quantified with a correlation of the Nusselt-Rayleigh-Prandtl type which involves the ratio between the conductivity of the solid matrix and that of the base fluid. The results of the 3D numerical approach allows for the optimization of the thermal design of the considered electronic assembly and the increase of its reliability.