Heat transfer in a conical gap using H2O–Cu nanofluid and porous media. Effects of the main physical parameters

Abstract

Heat transfer around a conical antenna is quantified in this work. Cooling of this active electronic component is ensured by a medium of high porosity saturated by a H2O–Cu nanofluid with a volume fraction varying between 0% and 5%. The ratio between the thermal conductivity of the porous materials and that of the water (base fluid) ranges from 4 to 41.2, the null value corresponding to a heat transfer without porous media (only nanofluid). The conical enclosure's aspect ratio varies in the 0.2–0.6 range, being its base inclined between 0° (horizontal base with cone's top oriented upwards) and 180° range (horizontal base with cone's top oriented downwards). The associated Rayleigh number varies within the 3.32x105-6.74x107 range. Heat transfer by natural convection is quantified for any configuration combining these five parameters and presented via a correlation allowing determination of the average Nusselt number. This study shows that heat transfer increases when the cone is tilted. For a given aspect ratio, the maximum is reached when the cone is vertical with the top pointing down. This observation remains valid in the overall Rayleigh number range. The average Nusselt number enhancement varies between 20 and 70%, according on the considered cavity's aspect ratio. This study complements a recent one restricted to the case of a cone whose horizontal base is located at the bottom, being 0.2 the aspect ratio of the enclosure.