本文通过不同比例的汽油与柴油混合组成宽馏分燃料,在一台单缸试验发动机上进行了燃料组分和喷油压力对低温燃烧影响的试验研究。研究结果表明,在燃烧放热重心(CA50)控制相同的条件下,随着汽油比例升高,燃烧放热速率增大,燃烧持续期缩短,缸内最大压力升高率和爆发压力升高,碳烟排放降低,但NO_x排放增大,并且由于低汽油比例的宽馏分燃料(G70)可以采用更大的EGR率,可以实现更低的NO_x排放。但燃料组分对热效率的影响较小。提高喷油压力可有效降低宽馏分燃料soot排放,但过高的喷油压力对降低soot排放的作用减小;提高喷油压力使NO_x排放升高,但随着EGR率升高,喷油压力对NO_x排放的作用减小。因此对于不同组分的宽馏分燃料存在一个最佳的喷油压力,随着汽油比例升高,最佳喷油压力降低。
In this paper,different ratios of gasoline and diesel are blended as wide-distillation fuels, and experimental study on the effects of fuel component and injection pressure on low temperature combustion has been conducted on a single-cylinder test engine.The results demonstrate that with the fixed CA50.higher gasoline ratio leads to higher combustion heat release rate,maximum pressure rise rate and cylinder pressure,as well as shorter combustion duration;soot emission decreases but NO_x emission increases,while higher EGR rate could be used by the wide-distillation fuel(GTO) with lower gasoline ratio,so that NO_x emission can be further reduced.Increasing of injection pressure enables significant reduction of soot emission of wide-distillation fuels,but the effect on soot becomes smaller with excessive ones;higher injection pressure increases NO_x emission,whereas the effect on NO_x is declining with the increase of EGR,rate.Therefore,for each wide-distillation fuel there exists an optimal injection pressure,which decreases with the increase of gasoline ratio.