柴油微引燃乙醇发动机燃烧、性能及排放特性研究

柴油微引燃乙醇发动机采用进气道喷射乙醇、缸内直喷微量柴油引燃的方式进行燃料供给。基于单缸四冲程柴油机,对其燃烧、性能及排放特性进行研究,固定引燃柴油喷射量为发动机能实现压燃着火的最小值,在进气压力为0.15 MPa时比较不同乙醇喷射量的工况组,通过改变柴油喷射时刻进行工况扫描。结果表明,引燃柴油的喷射时刻对发动机的燃烧、性能和排放影响显著。柴油微引燃乙醇发动机在中高负荷能够稳定运行,指示热效率可达34%以上,通过适当调节柴油喷射时刻,可以有效控制未燃碳氢(UHC)、NO_x与CO排放,同时可以实现极低的炭烟排放。柴油微引燃乙醇发动机燃烧模式为预混合或部分预混合燃烧,燃烧有两阶段放热特征,改变引燃柴油喷射时刻,可以有效控制燃烧相位。

Combustion,Performance and Emission Characteristics of Ethanol-fueled Engine with Diesel Micro-pilot Injection Ignition

Ethanol-fueled engine with diesel micro-pilot injection ignition adopted the fuel supply method of ethanol port injec-tion and diesel in-cylinder direct injection .On a single-cylinder four-stroke compression ignition engine ,the combustion ,per-formance and emission characteristics were researched .With the pilot diesel amount fixed as the minimum value to realize com -pression-ignition ,pilot diesel injection timing sweeping tests were conducted based on different ethanol injection mass under in -take air pressure of 0 .15 MPa .Pilot diesel injection timing had a strong effect on combustion ,performance and emission .The engine could work steadily at medium and high load and its thermal efficiency was more than 33% .With the appropriate pilot diesel injection timing ,unburnt hydrocarbon ,carbon monoxide and nitrogen oxide emission decreased and the ultra-low soot e-mission realized .In addition ,engine combustion form of premixed combustion or partial-premixed combustion led to 2-stage heat release characteristic and so combustion phase could be controlled effectively by changing pilot diesel injection timing .