Flame Stabilization and Multimode Heat Transfer in Inert Porous Media: A Numerical Study

Abstract

This paper presents a numerical analysis of combustion and multimode heat transfer in inert porous media. The work is directly relevant to the understanding of premixed flame stabilization in porous radiant burners. The influence of the flame location, the radiative properties of the porous material, the solid thermal conductivity, and stoichiometry on the flame speed and stability are determined using a one-dimensional conduction, convection, radiation, and combustion model. The porous medium is allowed to emit, absorb, and scatter radiant energy, Non-local thermal equilibrium between the solid and gas is accounted for by introducing separate energy equations for the two phases. Heat release is described by a single-step, global reaction. The results indicate that stable combustion at elevated flame speeds can be maintained in two different spatial domains. Flame propagation near the edge of the porous layer is controlled mostly by solid-phase conduction; whereas, in the interior both solid conduction and radiation heal transfer are important. The radiative characteristics of the porous matrix such as the optical depth and scattering albedo were also shown to have a considerable effect on flame stability