Two-Temperature Approximation Analyzing the Combustion Characteristics of Premixed Gas-Air Mixture in Inert Porous Media

A study is concerning combustion waves propagation characteristics during the filtration of premixed gas air mixtures in inert porous media, which the two-temperature approximation is used. Such processes are characterized by an intense thermal interaction between the gas and the porous material. Due to interfacial heat transfer, the solid phase is able to redistribute heat absorbed from reaction products to the unburned mixture. The analytical solution is built in three different regions: the pre-heating region, the reaction region and the region occupied by the combustion products. Analytic expressions predicting the temperature and methane mass fraction profiles in the wave, as well as the combustion wave velocity and the longitudinal extension of the reaction region are derived. The results are confirmed by a lean CH4-air case calculation. It is shown that the reaction region is not infinitely thin.