Influence of Methanol Addition on the Two Stage Combustion of a Dimethyl Ether/Air Mixture

A numerical study was performed to determine the effects of methanol addition on the two stage oxidation of a dimethyl ether/air mixture and on the production of formaldehyde and formic acid in a micro-flow reactor with a fixed temperature profile.The results indicate that methanol addition influences the reaction pathway for dimethyl ether oxidation at low velocity and this results in the low temperature reactions of dimethyl ether being suppressed.The low temperature reactions of dimethyl ether nearly vanish when methanol is added in the same mass fraction as dimethyl ether.The major cause of this is a decrease in the OH radical concentration.With increasing the amount of methanol the emission index of formic acid decreases sharply but the emission index of formaldehyde increases slightly at first,and then it decreases gradually.Therefore,appropriate methanol addition can result in the reduction of the emission indexes of formic acid and formaldehyde.