Investigation by thermodynamic properties of methane combustion mechanisms under harmonic oscillations in Perfectly Stirred Reactor

An analysis about the ability of selected global mechanisms in reproducing the correct dynamic behavior of a combustion reaction is conducted by investigating the behavior of the total entropy production rate in different ideal reactor configurations. The spontaneous ignition of a methane/air mixture at constant pressure in a batch reactor and the dynamic behavior of methane combustion in a PSR are investigated to elucidate the role of the rate of entropy produced by the chemical reactions. Four different chemical mechanisms for the methane-air combustion are thus compared, from one step to six steps global mechanisms and the detailed GRI mechanism assumed as reference mechanism. Results indicate that the analysis of entropy production in ideal reactors can be very useful to compare the ability of different chemical mechanisms in reproducing the dynamic behavior of unsteady combustion phenomena. The analysis can be useful in the selection of a global mechanism suitable for the simulation of unsteady combustion phenomena and combustion instabilities.