Experimental and numerical study on the combustion characteristic of H2 and CH4 in oxygen-enriched environment

Oxygen-enriched combustion could rise the hazard of unexpected fire and explosion in industry. This study experimentally and numerically analyzed the combustion characteristic of H-2 and CH4 in oxygen-enriched environment (Omega = 21%-100 %). For H-2 at Phi = 1 and Omega = 100 %, the maximum explosion pressure and maximum pressure rise rate were about 3.89 MPa and 1259.2 MPa/s. For CH4, these values were about 4.77 MPa and 6279.4 MPa/s. The upper flammability limit of gases increased sharply with the increase of Omega, however, the lower flammability limit was almost unchanged. Besides, the increasing of Omega also could result in the rising of aforementioned combustion parameters. The sensitivity of burning velocity was also analyzed. For H-2 flame at Phi = 0.8, R35 could slow down burning velocity when Omega = 21 %, but promote it when Omega = 30 % and 70 %. For CH4 flame at Phi = 1.4, the sensitivity coefficients of R11, R35, R43 and R84 changed from negative to positive when Omega increased from 21 % - 30 %-70 % - 100 %. It was concluded that the oxygen concentration not only affect the inert gas but also affect the reaction kinetic of flame.