Numerical Modeling of Counterflow Diffusion Flames Inhibited by Iron211 Pentacarbonyl

摘要

This paper presents the first detailed numerical study of the extinction of211u001emethane-air counterflow diffusion flames by the super-effective agent iron 211u001epentacarbonyl. Calcualations using a gas-phase chemical mechanism reproduce the 211u001emagnitude of inhibition for small amounts of inhibitor in the air, but 211u001eoverpredict the inhibition effect for larger amounts of inhibitor. Reaction 211u001epathway and reaction flux analyses show that a catalytic cycle involving FeO, 211u001eFe(OH)2, and FeOH is primarily responsible for catalytic recombination of H atoms 211u001ewhich produces the inhibition, and that a new cycle involving Fe(OH), FeOOH, and 211u001eFe(OH)2 has a minor role. Reaction flux calculations demonstrate that the 211u001efractional flux of H and O atoms through the iron reactions increases as 211u001einhibitor concentration increases, but eventually the fractional fluxes level 211u001eoff. Saturation of the catalytic cycles can partially explain the diminishing 211u001eeffect of the inhibitos at high inhibitor loading shown in both the calculated 211u001eand experimental results. Flame structure calculations are used to determine the 211u001ereasons for stronger inhibition for air-side addition of the inhibitor than for 211u001efuel-side. Simulations using an idealized inhibitor confirm the important role of 211u001etransport in inhibition of counterflow diffusion flames.