喷油正时和压力对混合燃料燃烧影响的试验

摘要

Comparative study of effects of injection strategies on combustion and emission characteristics was conducted on a four-cylinder diesel engine fueled with diesel/gasoline-butanol.During the experiment,the engine was operated at a constant speed of 1 600 r/min.Four different fuels including pure diesel (D100),blended fuels of diesel/gasoline (D70G30),diesel-butanol (D70B30) and diesel/gasoline-butanol (D70B 15G 15) were tested.Results show that,compared with D100,the soot emissions of three blended fuels reduce greatly.The soot emission of D70B30 is the lowest among them.The addition of gasoline or n-butanol into diesel results in the increase in peak cylinder pressure,peak heat release rate,maximum pressure rise rate (MPRR) and brake specific fuel consumption (BSFC),while the extension of ignition delay period and the postponement of CA 50 (crank angle of 50％ accumulated heat release rate).However,the CO emissions increase after blended gasoline or n-butanol into diesel.The advancing of injection timings can obviously offset the above phenomenon.There is little difference in NOx emissions between blended fuels and D100.Moreover,the injection strategies show a more remarkable effect on the soot emissions of D100 than that of blended fuels.Nevertheless,the delay of injection timings can greatly offset the increase of MPRR,induced by the blending of gasoline or n-butanol.In addition,the effect of injection pressures on soot emissions is more obvious than injection timing.%在一台4缸柴油机上对比研究喷油策略对柴油/汽油/正丁醇混合燃料燃烧和排放特性的影响.试验中发动机转速固定为1 600 r/min,使用的4种燃料为纯柴油(D100)、柴油/汽油混合燃料(D70G 30)、柴油/正丁醇混合燃料(D70B30)和柴油/汽油/正丁醇混合燃料(D70B15G15).结果显示:与D100相比,3种混合燃料的soot排放大幅降低,其中D70B30最低.汽油或正丁醇的混入导致缸内压力峰值、放热率峰值和最大压力升高率(MPRR)增大,滞燃期延长,主燃烧放热时刻(CA 50)推迟,燃油经济性恶化.然而,CO排放升高,喷油时刻提前,可以明显削弱这一现象.D100与混合燃料的NOx排放之间基本没有差异.并且,混合燃料的soot排放对喷油策略的敏感程度远低于D100.但推迟喷油能够大幅度抵消掺混汽油或正丁醇所引起的MPRR升高趋势.此外,喷油压力对soot排放的影响大于喷油正时.