Ignition measurements of ethylene-oxygen-diluent mixtures with and without silane addition Conference Paper uri icon

abstract

  • Several dilute mixtures of varying concentrations and equivalence ratios (φ = 0.5, 1.0) of C 2H 4/O 2/Ar/SiH 4 were studied using a shock tube at temperatures and pressures between 1115-1900 K and 0.9-3.3 atm, respectively. Argon dilution ranged from 96-98% with total concentrations between 0.67×10 -5 and 3.2×10 -5 mol/cm 3. Reaction progress was monitored using chemiluminescence emission from the hydroxyl radical A 2∑ +→X 2Π transition near 307 nm. For SiH 4 concentrations less than 10% of the ethylene in the mixture, the ignition delay time was reduced by approximately 30% to greater than 50%, depending on stoichiometry and concentration. The addition of SiH 4 had a small effect on ignition activation energy when plotted on an Arrhenius diagram, indicating the chain branching mechanism for C 2H 4 ignition is sped up but not altered greatly by the silane at higher temperatures. As in other recent works by the authors, emphasis was placed on the details of the ignition-time definitions and subsequent interpretation of the data so that they can be correctly utilized in future chemical kinetics studies. After adding an appropriate OH* submechanism, several modem kinetics mechanisms containing high-temperature ethylene chemistry were compared to the data without S1H 4 to gauge the current state of C 2H 4 oxidation modeling over the conditions of this study. Most of the mechanisms captured the ignition activation energy quite well, but only the mechanism of Wang and Laskin (1998) was typically within 10% of the absolute experimental ignition times over the entire range of conditions. The basic formation and quenching characteristics of the OH* profiles were reproduced by most mechanisms, but each requires some improvement to match all features for both lean and stoichiometric chemistry.

author list (cited authors)

  • Kalitan, D. M., Rickard, M., Hall, J. M., & Petersen, E. L.

publication date

  • July 2004