在柴油发动机台架上,考察普通柴油和2种原料不同的生物柴油(B100-1,大豆油为原料;B100-2,废油为原料)在2个固定转速不同负荷的4个工况点的细颗粒物PM2.5及其中多环芳烃(PAHs)的排放特性.用石英滤膜采集了尾气中的细颗粒物,并用GC/MS分析了颗粒物中的PAHs.生物柴油在高负荷时降低了柴油机PM2.5的排放速率,最大降幅达到了37.3%,在低负荷情况下增加了PM2.5排放速率.在所测试的工况下,生物柴油的颗粒相PAHs的排放速率较普通柴油均有不同程度的降低,最大降幅达到77.6%.生物柴油不但降低了PAHs的排放速率,还降低了PAHs在PM2.5中的质量百分比.B100-2的PM2.5和PAHs的平均排放速率比B100-1分别增加14.7%和17.8%.3种燃料排放PM2.5中的PAHs的主要化合物相似,均以小分子量为主,其中以菲的含量最高,2~3环PAHs超过总排放50%.生物柴油排放的PAHs毒性当量与柴油相比有较大程度地下降.
PM2.5 emissions and polycyclic aromatic hydrocarbons (PAHs) in PM2.5 of pure biodiesel derived from different feedstocks were investigated and compared with diesel fuel. B100-1 (soyabean oil derived), B100-2(waste oil derived) and diesel fuel were tested on a diesel engine bench at four operating conditions, including two steady speeds of different loads. The fine particles were collected by fiber quartz filter and particle phase PAHs were analyzed by GC-MS. Compared with diesel fuel, biodiesel decreased PM2.5 emission rates with a maximal reduction rate of 37.3% at operating modes of high loads, while increased PM2.5 emission rates at low loads. PAHs emission rates from biodiesel decreased at all tested modes, with a maximal reduction rate of 77.6% . The emission rates of PM2.5 and PAHs of B100-2 were 14.7% and 17.8% times of B100-1. Low molecular weight PAHs dominated in the emission of three fuels with phenanthrene as maxima and 2-ring and 3-ring PAHs accounted for more than 50% of the total PAHs. Toxic equivalence of PAHs emissions of biodiesel was decreased greatly compared with that of diesel.