Entropy Generation of Nanofluids during Natural Convection in Rectangular Porous Enclosures

Entropy generation of nanofluids during natural convection in rectangular porous enclosures is analyzed in this paper. The objective is to find optimum circumstances from the standpoints of the First Law and the Second Law of thermodynamics. For this purpose، the mass، momentum، and energy conservation equations are solved numerically. Thereafter، the generation of entropy is calculated and discussed. Computations are undertaken for Cu، Al2O3، and TiO2 nanoparticles in a base fluid of water and the corresponding results are compared. Moreover، the influences of volume fraction of the nanoparticles، Rayleigh number، enclosure aspect ratio، radiation exchange، and non-Darcy effects on heat transfer and entropy generation in the porous enclosure are analyzed. Inspection of the presented results demonstrates that radiation exchange and non-Darcy effects possess prominent consequences on heat transfer and entropy generation inside the enclosure. Among the current nanofluids، the highest heat transfer and entropy generation appears in the Cu-water nanofluid.