Influence of a membrane on nanofluid heat transfer and irreversibilities inside a cavity with two constant-temperature semicircular sources on the lower wall: applicable to solar collectors

In this paper, free heat transfer ( H T ) and the entropy generation ( E g e n ) of Alumina/ H 2 O nanofluid (NF) in an square cavity (CV) are simulated owing to its application in solar collectors. For this purpose, a square CV with an angle γ is placed under a fixed magnetic field. The upper wall has a temperature of Tc and sidewalls are insulated. On the lower wall of the CV, which is also insulated, two half-pipe with a temperature of Th are mounted. In the middle of the CV, there is a partition with a conductivity coefficient. The Control volume method is employed to follow the SIMPLE algorithm for the simulation. The variable parameter included 10 3 < Ra < 10 6 , 1 < k s < 1000 , 0 < Ha < 40 , 0 < < 0.06 , 0 < γ < 90. The simulation results demonstrated that growing the Rayleigh (Ra) number increased the rate of H T and E g e n , while the increase in the Hartmann (Ha) number decreased both these parameters. Furthermore, the addition of nanoparticles (NPs) resulted in more H T . Increasing the thermal conductivity of the partition in strong free convective H T mode enhanced the H T , while, in poor free convective H T , it reduced the H T . The lowest H T and E g e n occurred in the horizontal CV.