A numerical analysis of heat transfer and combustion in porous radiant burners

Abstract

A numerical study of combustion and multimode heat transfer in porous radiant burners is performed. Burner characteristics such as flame speeds, radiant outputs and efficiencies are investigated using a one-dimensional conduction, convection, radiation, and premixed flame model. The porous medium is assumed 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 gas and the solid phase. Combustion is described by a one-step global mechanism. The effect of the optical depth, scattering albedo, solid thermal conductivity, upstream environment reflectivity, and interphase heat transfer coupling on the burner performance are studied. It was revealed that for maximizing the radiant output the optical depth should be about ten and the flame should be stabilized near the center of theporous medium. Also, low solid thermal conductivity, low scattering albedo, and high inlet environment reflectivity produced a high radiant efficiency.