喷油策略对混合燃料压燃模式排放物的影响

摘要

针对燃油喷射参数对微粒排放的影响进行了试验, 分析了燃油喷射时刻、喷射压力及EGR率对微粒排放粒径分布的影响规律, 试验在一台4缸柴油机上进行, 采用了体积分数为80％, 汽油与20％, 柴油的混合燃料 (记为G80) .结果表明:在其他喷油策略不变的情况下, 提高喷射压力, 各模态微粒数量浓度峰值向小粒径方向偏移, 各模态微粒数量均呈下降趋势, NOx排放有大幅度提升;当EGR率从10％, 增加到30％, 时, 各模态微粒数量浓度峰值均向大粒径方向偏移, 各模态微粒数均呈上升趋势, 尤其EGR率从25％, 增加到30％, 时, 微粒数量大幅度增加, 而EGR率的增加同样抑制了NOx的生成;提前第一次喷射时刻, 对微粒排放影响不大, NOx排放降低;提前第二次喷射时刻, 各模态微粒数量浓度峰值均向小粒径方向偏移, 且各模态微粒数均呈下降趋势, 而NOx排放呈现明显的上升趋势.%This experiment focused on the influence of fuel injection parameters on the particulate matter emissions, especially the fuel injection timing, injection pressure and EGR ratio.The experiment was conducted on a fourcylinder diesel engine with a mixing fuel named G80, which is composed of 80％, gasoline and 20％, diesel in volume.The experimental results show that when increasing the injection pressure, the modal particle number concentration peak shifts toward the small particle size, the quantity of modal particles decreases, and the NOx emission increases significantly.When the EGR ratio increases from 10％, to 30％, , the modal particle number concentration peak shifts toward the large particle size, and the modal particle number also increases.Especially, when the EGR ratio increases from 25％, to 30％, , the number of particles sharply increases, and the increase of EGR rate also reduces the formation of NOx .The experiment results also show that when advancing the first injection timing, the particulate matter emissions change little and the NOx emissions reduce.When advancing the second injection timing, the modal particle number concentration peak shifts toward the small particle size, the number of modal particles decreases, and the NOx emission has a large increase.