Skeletal kinetic mechanism for predicting formation of non-fuel hydrocarbons and soot in ethylene flames – A CFD approach

Abstract

Since existing reduced mechanisms of ethylene oxidation are either too large or lack of sufficient chemical reactions to describe aromatics formation, the study aims at developing a skeletal mechanism with extended predictive capability and lowered computational cost in computational fluid dynamics modeling of ethylene combustion. The newly assembled and refined kinetic mechanism composed of 664 species and 3582 reactions is minimized to 79 species and 538 reactions without empirically adjusting kinetic parameters. In the 1-D simulation for a premixed flame of ethylene, the ethylene-PAH mechanism generally well predicts experimental profiles of five hydrocarbons and nine aromatics. Integrated into a 2-D axisymmetric laminar finite-rate model, the ethylene-PAH mechanism reproduces experimental data of seven C2–C5 hydrocarbons, five aromatic hydrocarbons and soot in a diffusion flame of ethylene. In comparison with the 158-species (Narayanaswamy) mechanism, the newly proposed ethylene mechanism leads to a speedup of approximately 5.5 times in the 2-D laminar diffusion flame simulation and improved accuracy for predicting species formation in both premixed and nonpremixed flames. Moreover, we unveil the correlation between reaction pathways and intermediate formation from ethylene oxidation at the low temperature regime.