BTL/柴油混合燃料对柴油机瞬态工况微粒粒度分布的影响

Effect of BTL-Diesel Blended Fuel on Emitted Particle Size Distribution in Common-Rail Diesel Engine under Transient Conditions

试验研究了不同添加比例的生物柴油(BTL)混合燃料对高压共轨柴油机瞬变工况下微粒排放的影响,分析了不同瞬变率工况下微粒粒度分布特征,揭示了燃料理化特性对柴油机瞬态工况微粒排放粒度分布的影响规律。研究结果表明:瞬态工况下石化柴油、生物柴油燃料微粒粒数排放均呈双峰结构,核态微粒峰值在10nm附近,积聚态微粒峰值在60nm附近;石化柴油燃料微粒排放以大粒径积聚态微粒为主,占微粒总数的55%以上;BTL燃料微粒排放以小粒径核态微粒为主,占微粒总数的96%以上。随着工况瞬变率的减小,BTL燃料、石化柴油微粒平均数量排放均逐渐减少,BTL燃料下降更明显;石化柴油核态微粒排放受瞬变率的影响较为显著,BTL燃料受瞬变率的影响不明显。对于不同添加比例的生物柴油混合燃料,在小瞬变率工况,微粒排放数量随添加比例的增加缓慢上升;在中等瞬变率工况,添加比小于30%时微粒排放数量基本不增加,但核态微粒所占比例略有上升;在高瞬变率工况,添加比例大于10%时微粒排放数量大幅度上升。

Engine tests were carried out by using TSI3090 EEPSTM particle size spectrometer to study influence of biodiesel blend on the common-rail diesel engine transient particle emission and its size distribution characteristics, as well as effects of fuel physical and chemical properties on the particle size distribution. The results show that the particle size distributions for diesel and biodiesel fuels are both bi-modal with two peaks at 10 and 60 nm over the transient conditions. The particles for biodiesel fuel are mainly small diameter nuclei mode particles, accounting for over 96% of total, and for diesel fuel are mainly large diameter accumulation mode particles, accounting for over 55% of total. The mean particle emission amounts of BTL fuel and diesel fuel decrease as transient rate reducing, but the former＇s decrease is more obvious. For different BTL fraction biodiesel fuels, in low transient rate condition the particle emissions increase slowly as the BTL fraction rising, in middle transient rate condition, it hardly changes when the BTL fraction is below 30%, and in high transient rate condition, it increases rapidly as the fraction is above 10%.