生物柴油-柴油-DEC混合燃料发动机的喷雾、燃烧与排放性能分析

Analysis of spray,combustion and emission performance of biodiesel-diesel-DEC fuel blends

应用纹影法观察高压共轨系统下燃料的宏观喷雾特性,在高压共轨柴油机上开展外特性下燃烧和排放试验,分析生物柴油-柴油-碳酸二乙酯(diethyl carbonate,DEC)混合燃料的喷雾、燃烧与排放特性,生物柴油和柴油按体积比为3:7混合后的燃料记为B30,DEC和B30按体积比2:8掺混后的燃料记为B30DEC20。试验结果表明:混合性燃料B30DEC20的雾化效果明显提升,喷雾形态匀称、饱满,喷雾锥角、喷雾浓度等接近柴油;外特性运行时,燃用B30DEC20的发动机转矩比燃用柴油低27.4 N·m,但其热效率比燃用柴油高,转速为2400 r/min时,燃用B30DEC20的发动机热效率比燃用柴油高1.5%;B30DEC20的含氧属性使其具有较低的颗粒物(particulate matter,PM)和CO排放,燃用该燃料的发动机PM排放比燃用柴油降低65%~85%,THC排放低于燃用柴油;虽然燃用B30DEC20发动机的NO_(x)比排放大于燃用其他燃料,但当发动机转速大于2400 r/min后,燃用B30DEC20发动机的NO_(x)排放低于燃用柴油。

The schlieren method is used to observe the macro spray characteristics of the fuel under the high-pressure common rail system,and the combustion and emission tests of the external characteristics are carried out on the high-pressure common rail diesel engine to analyze the spray,combustion and emission characteristics of the biodiesel-diesel-DEC blend fuel.The fuel mixed with biodiesel and diesel in a volume ratio of 3:7 is referred to as B30,while the fuel mixed with DEC and B30 in a volume ratio of 2:8 is referred to as B30DEC20.The test results show that B30DEC20 fuel atomization effect is improved,the spray shape is symmetrical and full,and the spray cone angle and spray concentration are close to diesel fuel.In the external characteristics,the torque of the engine fueled with B30DEC20 is 27.4 N·m lower than that of a diesel engine,but its thermal efficiency is higher.When the engine speed is 2400 r/min,the thermal efficiency of the engine fueled with B30DEC20 is 1.5%higher than diesel engine.The oxygen-containing properties of B30DEC20 result in fewer PM and CO emissions,with PM emissions of the engine fueled with B30DEC20 reduces by 65%-85%and THC emissions is lower than diesel engine.Although the NO_(x) emissions of the engine using B30DEC20 are higher than other fuels engine,but the test found that when speed over 2400 r/min,NO_(x) emissions are lower than those of diesel.