二甲醚预混比对预混压燃发动机性能影响的试验研究

Experimental Study on Effects of DME Premixed Ratio on Performance of a PCCI Engine

在一台由2105柴油机改装成的预混压燃(PCCI)发动机上研究了二甲醚(DME)预混比对燃烧、排放特性以及燃油经济性的影响。结果表明,随着DME预混比的增大,PCCI发动机燃烧始点前移,缸内最高燃烧温度和最大爆发压力均逐渐增大,压力升高率曲线由2个波峰发展成3个波峰,最大压力升高率随着DME预混比的增加先增大后减小再增大,放热过程由2个阶段发展到3个阶段,放热率曲线整体前移,累积放热率逐渐增大且迅速升高的位置前移,整个燃烧持续期逐渐缩短,NOx和碳烟排放量降低,当量燃油消耗率逐渐下降,有效热效率逐渐升高。

The experimental investigation on the effects of DME premixed ratio on the combustion characteristics, emissions characteristics and fuel economy was conducted in a PCCI engine modified from a 2105 diesel engine. The results showed that the igniting timing advanced, and the maximum cylinder temperature and pressure increased with an increase in the DME premixed ratio. The rate of the pressure rise developed from two peaks to three peaks, and the maximum rate of the pressure rise increased first and then decreased and increased again with an increase in the DME premixed ratio. The heat release process changed from two-stage heat release to three- stage heat release, and the overall heat release rate curve moved forward with an increase in the DME premixed ratio. The cumulative heat release rate increased gradually; the position of the rise also advanced; the combustion duration shortened~ the NOw and smoke emissions decreased. The equivalent fuel-consumption rate beq gradually decreased, and the effective thermal efficiency gradually increased.