Numerical simulation and theoretical analysis of premixed low-velocity filtration combustion

This paper investigates combustion wave characteristics of lean premixtures in a porous medium burner. Heat recuperation originated by the porous medium is examined by an one-dimensional numerical model. Attention is focused on the influences of solid properties, heat loss, equivalence ratio, etc., on the combustion wave speed and the maximum combustion temperature attained in the wave. Based on the flame sheet assumption a relationship between the combustion wave speed and the maximum combustion temperature is given. Then an approach from the laminar premixed flame theory is applied and the entire flame zone is divided into a pre-heating region and a reaction region, and treated separately. In this way, the second relationship between the two parameters is deduced. Thus a closed analytical solution for the combustion wave speed and the maximum combustion temperature is obtained. Over a wide range of working conditions, the numerical predictions and theoretical results show qualitative agreements with experimental data available from the literature. The results reveal that the mechanism of superadiabatic combustion is attributed to the overlapping of the thermal wave and combustion wave under certain conditions.