ESR and Mass-Spectrometric Studies of Methanol Combustion. I. The Correlation between Labile and Stable Chemical Entities in Free-Burning Methanol–Air Flames under Atmospheric Pressure

The concentration profiles of labile (H, O, and OH) and stable chemical entities (CH3OH, O2, CH2O, H2, H2O, and CO2) in premixed methanol–air flames under atmospheric pressure have been studied by the probesampling-ESR method combined with mass-spectrometric detection. The concentrations of the labile intermediates have been determined by correcting their destruction in the sampling probe caused by gas-phase reactions, wall reactions, and reactions at the pinhole of the probe. The observed profiles are in good agreement with the numerical model developed previously by Westbrook and Dryer, except that the concentration changes in all the entities are quicker than expected. The dependence of the maximum concentrations of the labile intermediates on the composition of the premixed gas is essentially the same as that observed for the methanol–air flames at low pressure.