Shock-tube and modeling study of ethylene pyrolysis and oxidation

Pyrolysis and oxidation of ethylene were studied behind reflected shock wav es in the temperature range 1100-2100 K at pressures of 1.5-4.5 atm. Ethyle ne decay in both the pyrolysis and oxidation reactions was measured by usin g both time-resolved IR-laser absorption at 3.39 mu m and time-resolved IR- emission at 3.48 mu m. CO2 production in the oxidation was also measured by time-resolved IR-emission at 4.24 mu m. The production yields were also st udied using a single pulse method. The pyrolysis and oxidation of ethylene were modeled using a kinetic reaction mechanism including the most recent m echanism for formaldehyde, ketene, methane, ethane, and acetylene oxidation s. The present and some earlier shock tube data was reproduced using the pr oposed mechanism with 161 reaction steps and 51 species. The reactions and the rate constants in the mechanism were discussed in detail. It was found that reactions C2H4 + M --> C2H2 + H-2 + M, C2H4 + M --> C2H3 + H + M, C2H4 + C2H4 --> C2H3 + C2H5, C2H4 + H --> C2H3 + H-2, C2H4 + C2H3 --> 1, 3-C6H6 + H, C2H4 + O --> products and C2H3 + O-2 --> products were important to p redict our data, which was with mixtures of wide composition from ethylene- rich to ethylene-lean. (C) 1999 by The Combustion Institute.