Experimental and numerical study on the ignition delay times of dimethyl ether/ethane/oxygen/carbon dioxide mixtures

The ignition delay times (IDTs) of dimethyl ether (DME)/ethane/O-2/CO2 mixtures were measured in a shock tube at pressures of 0.8, 2, and 10 atm; temperatures within the range of 1126-1449 K; equivalence ratio of 0.5; and DME proportions within the range of 0-100%. Four chemical kinetic models named OXYMECH, AramcoMech 3.0, San-Diego 2016 and Wang-DME were validated using the IDTs measured in this work. The results indicate that the OXYMECH predicts well the experimental data under O-2/CO2 and O-2/N-2 atmospheres. At P = 0.8 and 2 atm, T = 1300 K, the increase of the DME proportion inhibits the ignition of the mixtures under O-2/N-2 and O-2/CO2 atmospheres. At P = 10 atm, T = 1300 K, the IDTs of the mixtures firstly decrease when DME proportion increases from 0 to 20%, and then increase when DME proportion increases from 20 to 100% under O-2/CO2 atmosphere, while the IDTs of the mixtures increase as the DME proportion increases under O-2/N-2 atmosphere. The valley-values of the IDTs of the mixtures appear at the certain DME proportion at P = 10 atm, T = 1100 K and 1200 K under O-2/N-2 and O-2/CO2 atmospheres. The analyses of sensitivity and the rate of production were conducted to interpret the effect of DME addition and the properties of CO2 on the ignition of the DME/C2H6/O-2/CO2 mixtures.