Effects of CO2 addition on the evolution of particle size distribution functions in premixed ethylene flame

The effect of CO2 addition on sooting behavior in premixed ethylene/oxygen/argon flat flames at atmospheric pressure was investigated both experimentally and computationally. The evolution of soot particle size distribution functions (PSDFs) was examined using Burner-Stabilized Stagnation (BSS) probe/Scanning Mobility Particle Sizer (SMPS) technique. To explain the experimental observations, numerical simulations of the flames were carried out to analyze the thermal and chemical effects of CO2 addition on the precursor chemistry. The evolution of PSDFs of nascent soot showed that the CO2 addition gave rise to a decline in soot nucleation rate and a slower mass growth rate, hence significantly lowering soot yield. The inhibition of soot formation by CO2 addition is found to be mainly through chemical effect, while the thermal effect only plays a minor role.