On the Non-Equilibrium Behavior of Fuel-Rich Hydrocarbon/Air Combustion Within Perfectly Stirred Reactors

TLDR: In this article, the origins of PSR non-equilibrium behavior are elucidated by analyzing the relevance of the reaction steps involved in the CO/O2 kinetic mechanism, deriving and assessing analytical expressions reproducing the PSR results, and examining asymptotic limit solutions emphasizing a possible cause of the nonequilibrium behaviour observed.

Abstract: The observed origins of non-equilibrium behavior, even for relatively large residence times in perfectly stirred reactors (PSRs) burning fuel-rich mixtures, are addressed. These PSR deviations from chemical equilibrium are characterized by using PSR-based results of CO/O2 reacting mixtures. Accordingly, the origins of the PSR non-equilibrium behavior are elucidated by (i) analyzing the relevance of the reaction steps involved in the CO/O2 kinetic mechanism, (ii) deriving and assessing analytical expressions reproducing the PSR results, and (iii) examining asymptotic limit solutions emphasizing a possible cause of the non-equilibrium behavior observed. The main results highlight that the PSR non-equilibrium behavior is controlled by a competition between (i) the rate of progress variable backward component of the CO + O + M ⇌ CO2 + M reaction and (ii) the ratio between the reactor inlet O2 molar concentration and the reactor residence time. Thus, even when the reactor is operating in a region of te...