相同氧含量醇类混合燃料燃烧和排放特性差异研究

Study on the Difference of Combustion and Emission Characteristics of Alcoholic Fuels with Same Oxygen Content

对一台4缸发动机燃用相同氧浓度的不同醇类混合燃料进行了试验研究,以对比不同三元燃料柴油机在相同转速不同负荷情况下的燃烧特性和常规排放的差异。试验结果表明:甲醇混合燃料在醇类混合燃料中获得最高的燃烧压力,而丁醇混合燃料的热释放率最高。与普通柴油相比,戊醇混合燃料在不同混合物中具有相对最佳的CO和未燃碳氢排放,甲醇混合燃料可获得最优的氮氧化物排放;乙醇混合燃料减小颗粒物效果明显,最大可以减少22.4%～55.6%的颗粒物数量浓度和3.4%～12.8%的颗粒物粒径,其中乙醇混合燃料的核态颗粒物和聚集态颗粒物排放量也最低,戊醇混合燃料达到最高(除高负荷外)。

An experimental study was conducted on a 4-cylinder,direct injection diesel engine at a constant engine speed under five loads to evaluate the effect of different ternary fuels on combustion and regulated emissions of the engine.Several alcohols,namely,methanol,ethanol,butanol and pentanol,were mixed separately with a blended fuel containing diesel and biodiesel to prepare four ternary fuels with same oxygen concentration,including methanol blend(DBM),ethanol blend(DBE),butanol blend(DBBu)and pentanol blend(DBP).Results show that use of methanol blend allows to have the highest combustion pressure in alcohol blends,while butanol blend has the highest heat release rate.Moreover,pentanol blend has the best CO and HC emissions in comparison with diesel fuel,while the optimal NOxemissions result from the use of methanol blend.Ethanol blend has the most obvious effect on particle reduction,which can reduce particle concentration by 22.4% to 55.6% and particle size by 3.4% to 12.8% and minimizing the emissions of nucleation mode and accumulation mode particles,while pentanol blend maximizes the emissions of both particles(except for high loads).