Effects of nanofluid concentration and channeling on the thermal effectiveness of highly porous open-cell foam metals: a numerical and experimental study

The following study aimed to determine the effect of nanofluid concentration and the inclusion of porously filled channels on the thermal performance of highly porous open-cell foam metals. The study considered variable heat flux, nanofluid concentration and considered porously filled channels and bulk porous media. The nanofluid used in the experimental and numerical work was gamma-Al2O3 nanoparticles suspended in water. The foam metal used was composed of 6061-T6 aluminum with a porosity of 0.91 and a permeability of 3.36e - 8 m(2). The nanofluid concentrations used for the study were 0.1%, 0.3%, and 0.6% by volume. The experimental and numerical work showed good agreement with a maximum relative error between numerical and experimental temperature of 4.8% and an average error of 3.0%. The thermal performance of the system was evaluated based on Nusselt number and an index of performance including pressure effects. The results indicate that the optimal conditions for system operation are 0.6% with porously filled channels when pumping power is not considered of importance. However, should the pumping power be considered as an essential operating parameter then the optimal system conditions are 0.3% with bulk porous media.