Behavior of Methanol and Formaldehyde in Burned Gas from Methanol Combustion : A Chemical Kinetic Study

A detailed chemical kinetic model has been proposed to explain the formaldehyde formation in a methanol fueled spark ignition engine. In comparison of the calculated results with the experimental results from a reactor tube, the reactions NO+HO2=NO2+OH and NO2+H=NO+OH became important for methanol oxidation and formaldehyde formation in exhaust gases with a large amount of nitric oxide. Accordingly, N-series reactions should be included in this scheme. According to the calculated results, methanol decreases with an increase of the residence time. On the other hand, formaldehyde increases to maximum value and then slowly decreases. At temperatures in excess of 950 K, methanol and formaldehyde oxidations are rapid, and complete in the residence time of 20 milliseconds. At temperatures below 800 K, methanol oxidation is considerably slower and formaldehyde is accumulated by increasing the residence time. The agreement between experimental and calculated results indicates that this proposed scheme is reasonable for studying formaldehyde formation mechanism.