Abstract

A one-dimensional model accounting for the interaction of convection, conduction, radiation and chemical reaction in a porous radiant burner/healer has been developed to predict the thermal performance of the natural gas burner. The porous radiant burner consists of two layers of cellular (reticulated) ceramics of different porosity and mechanical structure. The chemical heat release was simulated using a uniform heat source model to avoid the uncertainties associated with chemical kinetics parameters in a reduced chemical mechanism under strongly non-adiabatic conditions. Radiative transfer in the porous medium is modeled using the two-flux approximation. The model predictions reveal quantitatively conjugate heat transfer between convection, conduction, radiation and chemical heat release. A study of the effects of various parameters on the thermal performance of the porous radiant burner and comparison of predictions with experimental data are reported. The results obtained show that the flame thickness in this type of burners is much broader than that of conventional adiabatic combustion due to the strong conduction and radiation feedback from the high temperature (flame) region to the preheat region. The peak gas temperature is lower than that for conventional adiabatic premixed combustion conditions since part of the chemical heat release is convected to the solid.

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