A NUMERICAL STUDY ON THE SECOND LAW ANALYSIS OF THE FLAME STABILIZATION AND OPTIMIZATION IN A POROUS BURNER

Combustion in porous media is studied numerically in an axisymmetric, two-dimensional porous burner by a second-order finite volume method to solve the governing equations including continuity, full Navier-Stokes, energy, and the chemical species transport equations using a multistep reduced kinetic mechanism. The effects of the solid thermal conductivity, optical thickness, volumetric heat-transfer coefficient, and the equivalence ratio on the important flame characteristics involving heat recirculation flux, output radiant flux, effective flame speed ratio, thermal load, heat recirculation efficiency, and output radiant efficiency are investigated in detail. Furthermore, the second law analysis of the burner performance is carried out to evaluate the effects of the foregoing parameters on the available exergy, the rate of entropy generation, and the Merit number. It is revealed that in order to crease the available exergy, the solid thermal conductivity and the volumetric heat-transfer coefficient must be increased within the optimum optical thickness values. On the other hand, to decrease the rate of entropy generation and to increase the Merit number, the volumetric heat-transfer coefficient must be increased within the optimum values of the solid thermal conductivity and the optical thickness.