Numerical and experimental study of the influence of CO2 dilution on burning characteristics of syngas/air flame

作者:Manh-Vu Tran*; Scribano, Gianfranco; Chong, Cheng Tung; Ng, Jo-Han; Ho, Thinh X.
来源:Journal of the Energy Institute, 2019, 92(5): 1379-1387.
DOI:10.1016/j.joei.2018.09.004

摘要

In this study, effect of carbon dioxide dilution on explosive behavior of syngas/air mixture was investigated numerically and experimentally. Explosion in a 3-D cylindrical geometry model with dimensions identical to the chamber used in the experiment was simulated using ANSYS Fluent. The simulated results showed that after ignition, the flame front propagated outward spherically until it touched the wall, like the propagating flame observed in the experiment. Both experimental and simulated results presented a same trend of decreasing the maximum explosion pressure and prolonging the explosion time with CO2 dilution. The results showed that for CO2 additions, the maximum explosion pressure decreased linearly and the explosion time increased linearly, while the maximum rate of pressure rise decreased nonlinearly, which can be correlated to an exponential equation. In addition, both results showed a good agreement for syngas/air flame with CO2 addition up to 20% in volume. However, larger discrepancies were observed for higher levels of CO2 dilutions. Of the three diluents tested, carbon dioxide displayed the strongest effect in reducing explosion hazard of syngas/air flame compared to helium and nitrogen. Chemical kinetic analysis results showed that maximum concentration of major radicals and net reaction rates of important reactions drastically decreased with CO2 addition, causing a reduction of laminar flame speed.