Entropy generation of MHD natural convection heat transfer in a heated incinerator using hybrid-nanoliquid

Bouchmel Mliki *, Mohamed Ammar Abbassi

Materials, Energy and Renewable Energies, Faculty of Sciences of Gafsa, B.P.19, Zarroug, Gafsa, 2112, Tunisia

Abstract: The present study explores magnetic hybrid-nanoliquid (Al₂O₃-Cu/H₂O) natural convection in a heated incinerator shaped cavity by using the lattice Boltzmann method (LBM). Numerical results are presented in the form temperature contours, stream function and local entropy generation. Complex interaction between various physical phenomena characterizing this problem including the natural convection and the magnetic field has been observed. Influences of Rayleigh number (Ra=10³-10⁶), volumetric fraction of nanoparticles (Φ=0-0.04), and Hartmann number (Ha=0-90) are clarified in details through graphical portraits. Results depict that the average Nusselt number (Num) and average entropy generation (S_gen,A) increases with an increase of the Rayleigh number while are decreased by applying a magnetic field. In addition, it is found that the average Nusselt number (Nu_m) increases with the rise of volumetric fraction of nanoparticles for all Rayleigh and Hartmann numbers. Conversely, an opposite effect is obtained by an increase in volumetric fraction of nanoparticles on the average entropy generation (S_gen,A). Finally, the numerical results demonstrate that the effect of Lorentz force is reduced when the heat transfer regime conduction is considered.

Keywords: Incinerator; Entropy generation; Natural convection; Hybrid-nanoliquid; Magnetohydrodynamic (MHD)