柴油机燃用柴油/乙醇混合燃料的燃烧特性

分析了柴油机燃用柴油/乙醇混合燃料的燃烧特性和放热规律,研究了相同十六烷值条件下混合燃料中含氧量对燃烧特性和放热过程的影响,为柴油机燃用含氧混合燃料提供理论指导和试验依据.研究结果表明:十六烷值改进剂(亚硝酸异戊酯)的体积分数为0.2%时,可使其着火性能与乙醇的体积分数减小10%时的水平相当.当保持十六烷值不变,混合燃料中氧的质量分数提高3.6%,扩散燃烧期和总燃期的曲轴转角平均缩短0.8°,中高负荷放热率曲线型心位置的曲轴转角向上止点平均靠近0.25°,可以认为,试验结果反映了混合燃料含氧量对燃烧的影响.

Combustion Characteristics of a Compression Ignition Engine Fuelled with Diesel/Ethanol Blends

The combustion characteristics and heat release were investigated in a compression ignition engine fuelled with diesel/ethanol blends.The cetane number improver was employed to recover the cetane number of the blended fuels due to the addition of ethanol with low cetane number.The results show that added 0.2% volume fraction of cetane number improver(iso-amyl nitrite)the combustion performances of diesel/ethanol blends are equivalent to that of the mixed blends reduced 10% ethanol fraction.Maintaining cetane number constantly,for every 3.6%(increase) in oxygen mass fraction,the diffusive combustion duration and total combustion duration decreased by 0.8 crank angle degree,and the position of the center of heat release curve moved close to the top dead center by 0.25 crank angle degree under middle and high loads,which can be regarded as the influence of the ethanol addition as extracting the effect from ignition delay.