甲醇替代率对两段喷射F-T柴油/甲醇双燃料发动机排放的影响

The impact of methanol substitution rate on emissions of two-stage injection Fischer-Tropsch diesel/methanol dual-fuel engine

以一台高压共轨柴油机为基础,在进气歧管处加装甲醇喷射系统,同时缸内两段直喷(预喷+主喷)煤制费托合成柴油(F-T柴油),搭建F-T柴油/甲醇(F/M)双燃料发动机试验台架,在转速为2 000 r/min,负荷为25%,50%,75%和100%的工况下分别探究甲醇替代率对发动机排放性能的影响,同时为实现F-T柴油/甲醇反应活性控制压燃模式探寻理论基础。研究结果表明:在中高负荷下,F/M双燃料发动机的燃油经济性较好;与单燃料压燃模式相比,F/M双燃料燃烧模式的HC,CO,Soot,甲醇和甲醛排放量均有所增加,且随着甲醇替代率的增大而增加,随着负荷的升高而下降;CO_(2),NO_(x)和NO的排放量随着甲醇替代率的增大而减小,随着负荷的升高而增加;NO_(2)的排放量随着甲醇替代率和负荷的增大而增加。

Based on a high-pressure common rail diesel engine,a methanol injection system is installed at the intake manifold.A two-stage direct injection(pre-injection+main injection)of coal-to-Fischer-Tropsch(F-T)diesel is installed in the cylinder.A two-stage injection F-T diesel/methanol(F/M)dual-fuel engine test stand is built to explore the effect of different methanol substitution rates on engine emission performance at 2000r/min and loads of25%,50%75%and 100%.Simultaneously,the theoretical basis for realizing the F-T diesel/methanol reactivity contrlled compression ignition(RCCI)mode is explored.The results indicates that the fuel economy of the F/M dual-fuel engine is better at medium and high loads.The emissions of HC,CO,Soot,methanol and formaldehyde increase in the F/M dual-fuel combustion mode compared with the single-fuel compression-ignition mode.These emissions increase with the augmentationmethanol substitution rate and decrease with an increase in load.In contrast,the emissions of CO_(2),NO_(x),and NO decrease with an increase in methanol substitution rate but increase with an increase in load.The emissions of NO_(2) increase with both the rise in methanol substitution rate and load.The test results show that simply adding a methanol injection system to the intake manifold cannot achieve an efficient and low-emission RCCI combustion mode,and its fuel injection strategy needs to be calibrated.