Numerical Simulation of Two Dimensional and Axisymmetric of Premixed Methane- Air Combustion in Porous Media Burner with Variation of Porosity and Multi Step Mechanisms

In this paper a two-dimensional axisymmetric numerical model with variable porosity for premixed methane/air combustion in porous media has been developed. For this purpose، multi step mechanisms such as GRI 1. 2، GRI. 2. 11، GRI. 3. 0، Skeletal and a mechanism with 17 species and 58 chemical reactions has been used and the effects of the mechanisms on the temperature profile، mass fraction of species and emission of pollutants have been investigated. This model solves the continuity، Navier Stokes، the gas and solid energy and the chemical species transport equations by using the finite volume method. The pressure and velocity have been coupled with the SIMPLE algorithm. The results showed that the combustion mechanisms have the same accuracy in predicting of temperature profile and mass fraction of species in order to the GRI. 1. 2، GRI. 2. 11، GRI. 3. 0 mechanisms are the same accuracy and also the skeletal and 17 species mechanisms are the same in predicting of temperature profile and mass fraction of species. Also the effects of increasing the inlet velocity and the volumetric heat transfer coefficient at combustion zone with variation porosity are investigated. The results showed that by increasing in inlet velocity، the peak temperature and the amount of NOx emission will be decreased and also by decreasing in volumetric heat transfer، the peak temperature will be decreased.