乙醇燃料改质对HCCI燃烧特性的影响

为研究乙醇经过改质后，改质气浓度和改质气进入气缸相位对乙醇HCCI燃烧特性的影响，以一台改造的实验发动机上为模型，用CHEMKIN4．0软件进行模拟。模拟结果表明，乙醇经过改质后，改质气的主要组分为H2、CO、H2O和OH基；随着改质气浓度的增加，缸内压力升高，燃烧始点提前，缸内最高压力升高；随着改质气进入气缸相位逐渐接近上止点，HCCI燃烧始点逐渐推后，缸内的最高压力出现变化，改质气在上止点前14°CA进入气缸，缸内最高压力减小，改质气在上止点前12°CA进入气缸，缸内压力达到最大，随着改质气进入气缸相位逐渐减小，缸内最高压力逐渐减小。因此，在上止点前12°CA进入气缸是较优的相位。

Effect of Ethanol Reforming on Combustion Characteristic of Ethanol HCCI

Based on a modified direct injection diesel engine fuelled with ethanol, CHEMKIN4.0 is used to simulate the concentration of ethanol reforming gas and combustion characteristic of ethanol HCCI under the influence of the angle of reforming gas entering into cylinder. The results indicate that H2 , CO, H2O and OH radical are the main radical of the reformed ethanol. With the increase of concentration of ethanol reforming gas, the pressure of cylinder and the maximum pressure of cylinder are increased, with ignition timing of HCCI advancing. When the angle of reforming gas entering into cylinder moves to the top dead center（ TDC ）, the ignition timing of HCCI postpones, the maximum pressure of cylinder varies. When the angle of reforming gas entering into cylinder is 14 o CA before TDC, the maximum pressure of cylinder is re- duced. But when the angle of reforming gas entering into cylinder is 12 ° CA before TDC, the peak pressure of cylinder is maximum. With the decrease of the angle of reforming gas entering into cylinder,the maximum pressure of cylinder becomes smaller and smaller. So 12 °CA before TDC is a better angle for the angle of reforming gas entering into cylinder.