A naturally aspirated, direct injection diesel engine was modified in order to run on LPG/diesel mixing fuel, with a conventional pumplinenozzle system. Compared with the original diesel engine, the ignition delay period of L30 fuel (the mixing ratio of LPG is 30%) is obviously longer, the maximum pressure and the maximum rate of pressure rise are lower, and the corresponded crank angles are retarded. The maximum heat release rate is similar and the corresponded crank angle is retarded. At rotation of 2000 r/min, the pressure curve of L30 appears both peaks, which is similar to MK (modulated kinetics) combustion model. The power output and fuel consumption of L30 are nearly as same as that of diesel, and the engine noise is reduced. The smoke and NOx emissions can be greatly decreased, and CO emissions decreased too, but HC emissions slightly increase.%采用带传统泵嘴供给系统的自然吸气、直喷柴油机,经改装燃用LPG/柴油混合燃料.通过与原柴油机的对比试验可知,LPG混合比为30%(L30)的混合燃料的滞燃期明显延长,最高燃烧压力和最大压力升高率降低,对应的曲轴转角滞后,最大燃烧放热率与原机基本相同,对应的曲轴转角滞后.在转速为2 000 r/min时, L30发动机的压力曲线出现双峰,近似于MK(modulated kinetics)燃烧.动力性与经济性与原机基本相同,燃烧噪声降低.碳烟和NOx排放大幅下降,CO略有降低,HC排放有所升高.
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