Entropy Generation and Mixed Convection in an Enclosure with Five Baffles Exposed to a Uniform Magnetic Field with Volumetric Radiation for Solar Collectors via Lattice Boltzmann Method.

This study employed the Lattice Boltzmann method to numerically investigate mixed, free and forced convection of nanofluid in a 2D rectangular enclosure. This cavity had five circular obstacles on the hot wall and a cold moving wall, which has been used in the cooling of solar panels. A handwritten code was used for this purpose. The enclosure included one moving (upper wall) and three fixed walls. The moving wall was cold, and its opposite wall was hot. Five semicircular blades with equal temperatures were laid on the hot wall. A magnetic field (MGF) was applied to the enclosure with volumetric radiation (VOR). The variables included the Hartmann number (Ha) (0–40), Enclosure height (ENH) (0.5–2), and radiation (0–1). Finally, the thermal entropy, fluid loss entropy, total entropy (TENT), and Bejan (BE) were examined. The simulation results showed that the surge of radiation reduced the total generated entropy, such that entropy generation (ETG) was maximal in the absence of radiation. The rise in the Ha, especially at higher heights, reduced entropy generation in the enclosure, while the increase in the enclosure height decreased BE.