Modeling of flame characteristics under O2/CO2 atmosphere by detailed chemical kinetics

Oxy-fuel (O-2/CO2) combustion is one of the several promising new technologies which can realize the integrated control of CO2, SO2, NOX, and other pollutants. The most significant feature of oxy-fuel combustion is the presence of high CO2 concentration in the combustion atmosphere. As the physical and chemical properties of CO2 and N-2 are very different, the flame characteristics of fuels under O-2/CO2 atmosphere can be quite different from those under conventional air atmosphere. Up to now, the variation of flame characteristics of n-alkanes and the reaction mechanisms under O-2/CO2 atmosphere have been unclear. In this paper, flame characteristics of three typical pre-mixed flames were studied under both ordinary air atmosphere and O-2/CO2 atmospheres over a wide range of CO2 concentrations in the combustion systems. A unified detailed chemical kinetic model was also validated and used to simulate the flame characteristics of the three types of fuels. Based on the verified model, the influences of various parameters (atmosphere, excess oxygen ratio, O-2 concentration, CO2 concentration, and alkane type) on the flame characteristics were systematically investigated. It can be concluded that a high CO2 concentration atmosphere has different effects on the ignition, laminar flame speed, and adiabatic temperature characteristics. This work confirms that the chemical effects of CO2 play a pronounced role on the flame characteristics, especially for the ignition time property. These calculations also give new insight into the complexity of the effects of the high CO2 concentration atmosphere and should help to improve the understanding of experimentally measured oxy-fuel combustion and flame characteristics in the literature. (C) 2013 Society of Chemical Industry and John Wiley & Sons, Ltd