生物柴油在低转速二冲程内燃机的NO_x燃烧特性

NO_x emission characteristics of biodiesel in the two-stroke internal combustion engine under low speed

为了解生物柴油在内燃机中NO_x的燃烧特性,应用均质压燃反应器模拟了生物柴油在低转速二冲程内燃机中55~85r/min、空气过量系数为1.4时的不同工况下的燃烧情况,计算了反应器内NO、NO_2以及N_2O摩尔分数随曲柄转角的变化关系,并且对NO_x的反应过程进行了分析。相关反应机理研究表明,NO和NO_2在尾气中的摩尔分数随转速的降低而降低;NO摩尔分数在曲柄转角为340°~390°时下降的原因之一是转化为N_2;NO_2摩尔分数在曲柄转角为340°~390°下降的原因是转化为NO,在曲柄转角为390°~480°上升是由于NO转化为NO_2;N_2O的摩尔分数在曲柄转角为340°~480°下降是由于大部分N_2O转化为N_2。

In order to understand the combustion characteristic of biodiesel in the internal combustion engine,different burning situations of biodiesel under low-speed from 55 to 85 r/min were simulated by applying homogeneous charge compression ignition reactor,and then the mole fractions of NO,NO2 and N2 O corresponding to different crank rotation angle were calculated.According to the relevant reaction mechanism,the mole fractions of NO and NO2 in emission decreased with decline of the revolution.The decline of NO and NO2 mole fraction during 340°-390°of crank rotation angle because they were converted to N2 and NO,respectively.However,the increase of NO2 mole fraction during crank rotation angle between 390°-480°because NO was converted to NO2.In addition,the decline of N2 O mole fraction because N2 O was converted to N2.