Superadiabatic combustion wave in a diluted methane-air mixture under filtration in a packed bed

Abstract

The self-sustaining combustion wave, occurring when a methane-air mixture is filtered through a porous media, is examined theoretically in this paper. Such processes are characterized by an intense thermal interaction between the gas and the porous material. Due to the interfacial heat transfer, the solid phase is able to redistribute heat absorbed from reaction products to the unburned mixture. In the case of combustion waves cocurrent with the filtration flow, this results in peak temperatures exceeding the adiabatic one for the air-methane mixture. Theoretical treatment is conducted within a two-temperature model in which external heat losses are taken into account. The ignition temperature as the main parameter used in analytical solutions is determined for experimental conditions typical for methane-air mixtures burning under filtration in a packed bed. Analytical expressions predicting the combustion wave velocity and temperature distributions in the wave are derived. The results obtained are confirmed by numerical calculations and compared with related experimental data.