Simulation of the heat transfer performance of Al2O3–Cu/water binary nanofluid in a homogenous copper metal foam.

The present study analyzed the behavior of a hybrid nanofluid with the aim of improving its heat transfer in tubes filled with a porous medium, which is a metal foam in this case. To this end, the impact of changes in influential factors, namely the Reynolds number, nanofluid concentration, porosity, number of pores per inch and Prandtl number on the heat transfer performance of an Al2O3–Cu/water hybrid nanofluid in tubes containing a porous medium, was investigated via numerical simulation. According to the results, increases in Reynolds number (in the laminar flow range), nanofluid concentration, pores per inch, and Prandtl number improved the Nusselt number and, hence, the thermal performance of the nanofluid. In contrast, an increase in porosity in the studied range reduced Nusselt number, resulting in a drop in the thermal efficiency of the nanofluid. Subsequently, the thermal behavior of the Al2O3–Cu/water hybrid nanofluid was studied under the presence and absence of the porous medium. The results indicated the positive effect of the porous medium on the Nusselt number and, as a result, the thermal efficiency of the nanofluid. Ultimately, the data obtained from the numerical simulation were used to obtain a general Nusselt correlation for the Al2O3–Cu/water hybrid nanofluid under constant- and variable-porosity media. The accuracy of the Nusselt correlation produced for examining the thermal performance of the hybrid nanofluid was 98% for the constant-porosity medium and 96% for the variable-porosity medium. [ABSTRACT FROM AUTHOR]