Flame stability analysis of the premixed methane-air combustion in a two-layer porous media burner by numerical simulation

چکیده مقاله

The flame stabilization within a two-layer porous burner was investigated numerically in the present study. Two-dimensional model was implemented to simulate the premixed methane-air combustion process. The governing equations including the radiative transport equation and separate energy equations for the solid and gas phases were solved by using the finite volume method. In order to validate the utilized model, the gas and solid temperature profiles within the burner were compared to the experimental temperature distribution and good agreement was observed. The results proved that the stability limit and flame temperature within a porous burner can be controlled by the equivalence ratio of the incoming mixture. Heat recirculation study showed that high convective heat recirculation occurred at low equivalence ratios caused higher stable inlet velocities. The radiative recirculation efficiency was almost constant over the stability limit at constant equivalence ratio while this parameter decreased with increasing equivalence ratio. Also, the effect of outlet diameter of the burner on the flame stabilization suggested that the optimum outlet diameter eventuating the highest flame stability limit was double the amount of inlet diameter. The study of the effect of the length of first porous layer on the flame status showed that the optimum ratio of preheat zone to combustion zone length was 0.33 to reach the highest burner operating range.