Thermal design of a spherical electronic device naturally cooled by means of water–copper nanofluid saturated porous media

Abstract

The present work deals with thermal regulation of a spherical electronic device used in naval navigation techniques. Cooling is achieved by means of porous media saturated with water–copper nanofluid contained in another sphere kept isothermal. Nanofluid volume fraction varies between 0 (pure water) and 5%, Rayleigh number ranges from 6.5 × 106 to 1.32 × 109, while ratio between the thermal conductivity of the porous material’s matrix and that of water varies in the 0–40 range. Results for different configurations obtained through variation of these three influencing parameters show that the thermal conductivity ratio has a strong influence on the component’s average surface temperature, while the fraction volume has a moderate influence throughout the range of the considered Rayleigh number. Evolution of the average temperature versus the Rayleigh number is conventional of the power type. It can be calculated through the correlation proposed in this work for any combination of the three influencing parameters. This work complements a recent study where heat transfer occurring around the active sphere is quantified. This optimizes the thermal sizing of the assembly and enhances its reliability.