NUMERICAL MODELING OF TWO-DIMENSIONAL CYLINDRICAL POROUS RADIANT BURNERS WITH SIDEWALL HEAT LOSSES

In this paper, numerical modeling of axisymmetric cylindrical porous radiant burners with sidewall heat loss has been studied. Nonlocal thermal equilibrium is assumed between gas and solid phases and the solid phase is considered as the thermal radiation medium in this modeling. Lateral heat loss at the experimental conditions is found to be 6% of the supplied fuel energy, which causes the highly two-dimensional characteristics and lower temperature profiles in the burner. The experienced maximum peak temperature reduction is about 150 K compared to a one-dimensional flame. The lower flame peak temperature leads to less NOx formation, which results in about 44% reduction of NO concentration at the burner outlet surface for a stoichiometric mixture. This brings about the new results very close to the experimental results. As lateral heat loss increases, the flame front moves downstream. About 6 mm of backward movement is observed when the lateral heat loss is about 23% of the firing rate. This is due to the lower flame speed at lower flame temperature. The new findings are observed for both stoichiometric as well as lean mixtures.