Numerical investigation on lean methane combustion with modified effective thermal conductivity of the porous media

Abstract

In this work, to further optimise the porous media combustion model and explore the combustion characteristics of low-concentration methane in porous media, a thermal non-equilibrium model of porous media combustion is established with modified effective thermal conductivity of the porous media based on the volume average method. The effects of foam ceramics pore density, inlet velocity and wall heat loss coefficient, as well as combinations of different pore density foam ceramics on flame stability were studied. Results show that the predicted temperature profile matched well compared with the experimental data. The temperature inside the burner can be divided into the following four zones: preheating zone, combustion zone, cooling zone dominated by wall heat loss and cooling zone dominated by heat radiation at the burner outlet. Moreover, it was found that the porous media combustion model with modified effective thermal conductivity of the porous media could simulate the flame front shape in different pore density foam ceramics. On the contrary, the flame front shape in the simulation with constant thermal conductivity does not change and remains a uniform radial disc. In addition, the flame is easier to stabilise at the interface of the foam ceramic with different pore densities.