Premixed carbon monoxide–nitrous oxide–hydrogen flames: measured and calculated burning velocities with and without Fe(CO)5‡‡Official contribution of the National Institute of Standards and Technology, not subject to copyright in the United States

The burning velocity of premixed carbon monoxide–nitrous oxide flames (background water levels of 5 to 15 ppm) has been determined experimentally for a range of fuel–oxidizer equivalence ratio φ from 0.6 to 3.0, with added nitrogen up to a mole fraction of X N 2 = 0.25, and with hydrogen added up to X H 2 = 0.005. Numerical modeling of the flames based on a recently developed kinetic mechanism predicts the burning velocity reasonably well, and indicates that the direct reaction of CO with N 2 O is the most important reaction for CO and N 2 O consumption for values of X H 2 ≤ 0.0014. The calculations show that a background H 2 level of 10 ppm increases the burning velocity by only about 1% compared to the bone-dry case. Addition of iron pentacarbonyl, Fe(CO) 5 , a powerful flame inhibitor in hydrocarbon–air flames, increases the burning velocity of the CO–N 2 O flames significantly. The promotion is believed to be due to the iron-catalyzed gas-phase reaction of N 2 O with CO, via N 2 O + M = N 2 + MO and CO + MO = CO 2 + M, where M is Fe, FeO, or FeOH.