Kinetic study of the effect of sub-atmospheric conditions on the laminar burning velocity of high C<sub>2</sub>H<sub>6</sub> content natural gas mixtures
收藏资源简介：
The laminar burning velocity (<i>S</i><sub>L</sub>) was measured at sub-atmospheric pressure (0.84 atm) and an environmental temperature of 295 ± 2 K for two high C<sub>2</sub>H<sub>6</sub> content fuel mixtures, 75% CH<sub>4</sub> – 25% C<sub>2</sub>H<sub>6</sub> (mixture M1), and 50% CH<sub>4</sub> – 50% C<sub>2</sub>H<sub>6</sub> (mixture M2), as well as the pure constituent fuels. The equivalence ratios for the experiments ranged between 0.8 and 1.4. Numerical calculations predicting <i>S</i><sub>L</sub> were performed using 3 detailed reaction mechanisms, finding GRI-Mech 3.0 to achieve the best agreement at the pressure conditions evaluated. The pre-exponential factor of reaction H + O<sub>2 </sub>= O + OH (R38) was modified in order to improve the numerical results at sub-atmospheric conditions. Kinetic analysis by means of the defined reaction factor (FR,i±j) was carried out to identify the mechanism for <i>S</i><sub>L</sub> changes at sub-atmospheric conditions. According to the experimental results, <i>S</i><sub>L</sub> increased by 15.9% and 26.3% for mixtures M1 and M2, respectively, at 0.84 atm as compared to 1.0 atm. The reaction pathways elaborated employing <i>F</i><sub>R</sub> indicate that the increase in <i>S</i><sub>L</sub> at sub-atmospheric conditions is caused by increased CH<sub>3</sub> radical production by reaction C<sub>2</sub>H<sub>5 </sub>+ H = 2CH<sub>3</sub> (R159), which increases the formation of H radical through reactions O + CH<sub>3 </sub>= H + CH<sub>2</sub>O (R10) and O + CH<sub>3 </sub>= H + H<sub>2 </sub>+ CO (R284). The recombination reactions associated with the production of CH<sub>4</sub> and C<sub>2</sub>H<sub>6</sub> also contribute to <i>S</i><sub>L</sub> increases at sub-atmospheric conditions.
