低辛烷值高挥发性燃料直喷压燃宽运行范围的燃烧模式

Direct Injection Compression Ignition Modes of a Low Octane Number Fuel with High Volatility in Wide Operating Range

在一台单缸柴油机上采用低辛烷值高挥发性汽/柴油混合燃料,在不同转速和负荷条件下对比了部分预混压燃(PPCI)和多段预混压燃(MPCI)等多种压燃模式的燃烧和排放特性,并在宽运行范围与原机柴油试验结果进行对比,以确定宽运行范围的最优燃烧控制策略.结果表明:试验用低辛烷值燃料能够在宽运行范围实现压燃模式的稳定运行;为使燃烧排放结果最优,低负荷区间应采用单次喷射PPCI模式,中、低转速(中、高负荷)采用MPCI模式,高转速(中、高负荷)采用多次喷射PPCI模式;宽运行范围内低辛烷值燃料可以实现NOx排放低于0.4,g/(k W·h)、碳烟排放低于0.5,FSN及最高压力升高率低于1,MPa/(°)CA;与原机柴油燃烧结果相比,低辛烷值燃料可以同时降低NOx和碳烟排放以及燃油消耗率,但CO和HC排放增加,循环波动系数也略有增加.

The blended gasoline and diesel fuel with low octane number and high volatility was tested on a single cylinder diesel engine under different operating conditions. Comparison of combustion and emission characteristics of partially premixed compression ignition(PPCI)and multiple premixed compression ignition(MPCI)modes was made to optimize the combustion controlling strategies. Results show that the compression ignition modes can be realized using the low octane number fuel in engine wide operating range. At low loads with full speed,the single injection PPCI favors to obtain the high efficiency and low emissions. At medium and high loads with medium and high speeds,the MPCI is the best. The multi-injection PPCI is mostly suitable for the medium and high loads with high speeds. In the wide operating range,NOx emission of the low octane fuel is less than 0.4,g/(k W·h),and soot emission is less than 0.5,FSN,while rate of maximum pressure rise is less than 1,MPa/(°)CA. Compared with the original diesel combustion,low fuel consumption,NOx and soot emissions are achieved simultaneously,while CO and HC emissions are increased and load variation coefficient is slightly increaseed.