加氢催化生物柴油对GCI发动机燃烧与排放影响

Effect of Hydrogenation Catalyzed Biodiesel on Combustion and Emissions of GCI Engines

汽油压燃(GCI)发动机具有较高的热效率及较低的排放,但使用商用高辛烷值汽油存在低负荷工况下着火困难、燃烧稳定性差的难题.将高十六烷值的加氢催化生物柴油(HCB)按照不同体积比例添加到95号汽油中,通过一台共轨单缸柴油机,研究在小负荷工况下加氢催化生物柴油体积分数对发动机燃烧与排放特性的影响.结果表明:随着加氢催化生物柴油体积分数的增加,燃料的着火性能显著改善,有效降低燃烧爆压.同时,不同活性燃料的掺混比例应与运行工况匹配才能获得较为合适的燃烧相位,进而提高发动机性能.排放方面,掺混燃料在降低颗粒物排放方面有着巨大的潜力,随着生物柴油体积分数的增加,虽然颗粒物排放有所增加,但可以有效地降低CO及未燃碳氢化合物(UHC)排放.掺混燃料中生物柴油掺混比例对NO_x排放的影响在不同负荷下表现出不同的趋势.

Gasoline compression ignition(GCI)engines have high thermal efficiency and low toxic emissions.However,GCI engines fueled by commercial gasoline with high octane number have ignition difficulties and poor combustion stability at low loads.To this end,hydrogenation catalyzed biodiesel(HCB)with high cetane number was blended into the No.95 gasoline in different volume ratios,and the effects of different blended ratios on combustion and emissions characteristics were explored in a common rail heavy-duty single-cylinder diesel engine.The results indicate that the auto-ignition performance of the blended fuel is significantly improved with increasing the proportion of the HCB,resulting in lower combustion pressure.Meanwhile,the blended ratios of fuels with different reactivities should be matched with the operation conditions to obtain suitable combustion phasing and then good engine performances.In terms of emissions,blended fuels have great potentials to reduce soot emissions.With the increase of HCB volume fraction,soot emissions increase,but CO and unburnt hydrocarbon(UHC)emissions can be effectively reduced.The influence of the HCB blended ratio on NO_x emissions shows different trends at different loads.