自然吸气直喷压燃式发动机燃用柴油醇的性能和排放

Performance and Emissions of a Naturally Aspirated DI CI Engine Fueled with Diesohol

应用助溶剂解决了乙醇和柴油相溶性较差的问题并配制柴油醇燃料,分析了柴油醇的主要理化特性,结果表明,柴油醇的黏度、热值和十六烷值有所下降,但汽化潜热却明显增加。自然吸气直喷压燃式发动机不作任何调整,燃用E10柴油醇,动力性和经济性基本不变,燃用E20柴油醇,动力性下降,小负荷经济性恶化。燃用柴油醇,在中小负荷工况,CO和HC浓度排放增加,NOx浓度排放减少;在大负荷工况,CO浓度排放减少,HC浓度排放变化较小,NOx浓度排放增加,排气烟度降低明显。柴油醇中乙醇含量越多,排放性能变化越大。适当推迟供油提前角对压燃式发动机燃用柴油醇的性能有利。

A solublizer was added to the blend of diesel and ethanol to help to form a stabilized diesohol fuel.The main physical and chemical properties of diesohol were analyzed.The results show that the viscosity,the lower heating value and the cetane number of the diesohols decrease with increase of ethanol fraction in fuel blend,while the vaporization latent heat increases with increase of ethanol fraction in fuel blend.For a no modified naturally aspirated DI CI engine,engine power output and fuel economy fueled with E10 could keep the same level to those of diesel fuel operation while the engine power output fueled with E20 would decrease and fuel economy at low load would deteriorate.Meanwhile,NO_x emission decrease while CO and HC emission increase at the low and moderate load conditions.At the high load conditions,great reduction in smoke,a decrease in CO emission,an increase in NO_x emission and little variation in HC emission were observed for diesohol,and the behavior tended to be more obvious at high ethanol fraction.The study suggests that appropriate postponing of fuel delivery angle will beneficial to the engine performance fueled with the diesohol.