An improved low and high-temperature dimethyl ether kinetic model for the combustion atmospheres with high CO2 concentration

The Dimethyl ether (DME) kinetic model is significant to understand the DME combustion in the atmosphere containing high CO2 concentration, such as pressurized oxy-fuel combustion process and exhaust gas recirculation, and design the combustor. In this paper, the ignition delay times (IDTs) of DME were measured in a shock tube under the conditions of equivalence ratios of 0.5, 1 and 1.5, temperature ranges from 1007 K to 1340 K, and pressures of 2 and 11 atm. A detailed kinetic model of DME named as OXYDME was put forward based on the OXY-Aramco model, and was validated by the low and high temperature IDTs, laminar flame speeds, and species profiles measured in this work and those from literatures in atmospheres of O2/Ar/CO2, O2/N2, O2/N2/He/CO2 and O2/CO2. The OXYDME model was compared with OXY-Aramco, Liu-DME model in detail. The effects of CO2 on the DME ignition are very weak and not sensitive to the temperature and pressure. The reason for the weak effects of CO2 is that the chemical effects of CO2 promote ignition, which counteracts the inhibition effects caused by the physical properties of CO2. The chaperon effects of CO2 dominate the chemical effects. Meanwhile, the effects of the reactions with CO2 are very small.