Abstract
Entropy generation analysis has been introduced to investigate the effectiveness in heat transfer during natural convection within porous rhombic enclosures of various inclination angles ϕ for differential (case 1) and Rayleigh Benard (case 2), heating situations. The results are presented in terms of streamlines (ψ), isotherms (θ), and entropy generation maps (S θ and S ψ ). Entropy production on the basis of various heating patterns and geometrical orientations have been reported based on the relation between total entropy generation (Stotal) and average Nusselt number via Bejan Number, which relates the available thermal energy to irreversibilities.