Pollutants formation in a low-emission porous burner

Abstract

Combustion in inert porous burners has been focused in numerous research works which have demonstrated the advantages of this technique. In comparison with conventional burners, porous media combustors attain higher efficiencies over a large modulation range with reduced emission of pollutants. Additionally, these burners are compact and provide the possibility of burning leaner mixtures and fuels with lower heating value. Numerical modelling plays an important role in the development of such burners, providing guidance for future designs. In this paper, a numerical study of an innovative two-layer radiant burner is presented. The burner, designed for household heating and to be fuelled with a vaporised mixture of fuel-oil and vegetable oils, is composed by a thin SiC porous foam, which is preceded by a perforated plate, made of an insulating material. A three-dimensional model has been developed, which includes the Navier-Stokes, the energy and the chemical species transport equations, and accounts for the local thermal non-equilibrium between the reacting flow and the solid phases and for the radiative heat transfer through the porous matrix. Heptane is used as model fuel, with combustion being modelled by means of a multi-step reaction mechanism. Computer codes, based on the aforementioned model and on CFD techniques, and developed to predict detailed thermo-fluid characteristics, have been employed in order to numerically simulate the operational behavior of porous medium burner device.