Oxy-Fuel Combustion Modeling: Performance of Global Reaction Mechanisms

Abstract

Three global reaction mechanisms derived for oxy-fuel combustion and one global reference mechanism are investigated and compared under gaseous oxy-fuel combustion conditions. The aim is to evaluate their prediction of major in-flame species and temperature by comparison with a detailed reaction mechanism (validated for oxy-fuel conditions) and experimental data. The evaluation is performed using a 1D plug flow reactor (PFR) method and 3D CFD calculations. Through the PFR calculations, it is found that the global mechanisms all predict a too early onset of fuel oxidation compared to the detailed mechanism. Furthermore, the global reference mechanism predicts gas concentrations more in line with the detailed mechanism than the oxy-fuel mechanisms, which yield incorrect reaction sequences. In the CFD analysis, significant differences in the predicted gas concentrations and temperature fields between the global mechanisms show that the choice of reaction mechanism strongly influences the results. In summary, the global reference mechanism is a preferable alternative to represent the combustion chemistry when modeling oxy-fuel combustion using CFD, if the use of a detailed reaction mechanism is prohibited due to computational limitations.