Exergy analysis of a nanofluid–based direct absorption solar collector (DASC) occupied by porous foam

In this work, the energy and exergy efficiencies of a nanofluid–based direct absorption solar collector (DASC) are examined experimentally. Attention is focused to analyze the consequences of installation of porous foam in the collector, concentration of the nanoparticles (NPs) in the working fluid, and volumetric flow rate of the nanofluid from the standpoints of the first law and second law of thermodynamics. The porous foam is made up of SiC while the nanofluid contains SiC NPs in water as the base fluid. The results indicate that the foam installation improves both efficiencies. The dominant parameter on the energy efficiency is recorded to be the volumetric flow rate of the nanofluid but the highest contribution on the exergy efficiency belongs to the NPs concentration in the working fluid. More precisely, maximum changes in the exergy efficiency due to the variation in the NPs concentration in the working fluid is recorded to be 63.2%. Meanwhile, it is found that the foam installation and the alternation of the volumetric flow rate of the nanofluid bring 38.2% and 25.3% variations in the exergy efficiency, respectively.