Addition of water to premixed laminar methanol-air flames: experimental and computational results

Premixed laminar methanol-air flames at 100 torr were studied by experiment and computation. The composition CH/sub 3/OH/O/sub 2//N/sub 2//Ar (12.3%/18.4%/65.3%/4.0%) corresponds to a stoichiometric composition. The effect of water addition was studied in stoichiometric flames containing about 2.3 mol % water and 63 mol % nitrogen but with methanol, oxygen, and argon concentrations unchanged. The amount of water added corresponded to 10 wt % of the liquid phase. Species profiles were measured by using a modulated molecular beam mass spectrometer. They changed in an insignificant way when water was added. Detailed models for methanol-air combustion, including chemical kinetics and molecular diffusion, were used to compute the flame structure. Water addition did not affect the computational concentration profiles significantly. Sensitivity analysis indicated the importance of HCO and CH/sub 2/OH consumption reactions. Comparisons of experimental and computed concentration profiles supported a high value of the rate constant for the HCO decomposition reaction. 27 references, 7 figures, 1 table.