喷油策略对柴油机燃用正丁醇、聚甲氧基二甲醚、柴油混合燃料燃烧和排放特性的影响

Effects of Fuel Injection Strategies on Combustion and Emission Characteristics of A Diesel Engine Fueled with N-Butanol and Polyoxymethylene Dimethyl Ether/Diesel Blends

以柴油(B0)为基础燃料,分别配制掺混体积比20%的正丁醇(B20)及掺混体积比20%的正丁醇+20%的聚甲氧基二甲醚(polyoxymethylene dimethyl ethers,PODE)(BP20)的混合燃料。对比研究不同喷油策略下柴油机燃用B0、B20、BP20的燃烧和排放特性。结果表明:单次喷射策略下,随喷油定时的延迟,燃用B0、B20、BP20时的放热率先升高后降低,氮氧化物(nitrogen oxides,NO_(x))排放减少,碳氢化合物(hydrocarbon,HC)和CO排放增加,燃用B0、BP20的颗粒物总质量浓度先增加后减小,燃用B0、B20、BP20的颗粒物几何平均直径(geometric mean diameter,GMD)先增加后减少。两次喷射策略下,随预喷定时的延迟,NO_(x)排放增加,HC和CO排放减少,颗粒物总质量浓度和GMD增加。柴油中加入正丁醇后,NO_(x)排放降低,HC和CO排放增加,颗粒物总质量浓度和GMD减小。正丁醇/柴油燃料添加PODE后HC和CO排放降低,但NO_(x)排放、颗粒物总质量浓度和GMD略微增加。

Based on base fuel diesel(B0),20%volume fraction n-butanol/diesel blend(B20)and 20%volume fraction n-butanol+20%volume fraction polyoxymethylene dimethyl ether/diesel blend(BP20)were prepared respectively.The combustion and emission characteristics of a diesel engine fueled with B0,B20 and BP20 under different fuel injection strategies were compared and studied.The results show that under the single injection strategy,with the delay of injection timing,the heat release rates of the diesel engine fueled with B0,B20 and BP20 first increase and then decrease,and the NO_(x)emission decreases while the HC and CO emissions increase.And the total mass concentrations of particulate matter of the diesel engine fueled with B0 and BP20 first increase and then decrease.The particle geometric mean diameters of the diesel engine fueled with B0,B20,and BP20 first increase and then decrease.Under the two-injection strategy,with the delay of pre-injection timing,the NO_(x)emission increases while the HC and CO emissions decrease,and the total particulate matter concentration and geometric mean diameter(GMD)increase.After adding n-butanol to diesel,the NO_(x)emission decreases while the HC and CO emissions increase,and the total particulate matter concentration and GMD decrease.After adding PODE to n-butanol/diesel blend,the HC and CO emissions decrease while the NO_(x)and the total particulate matter concentration and GMD increase slightly.