为研究废气再循环（EGR）对煤制油生物柴油混合燃料NOx，CO和HC等气体排放物及炭烟颗粒排放特征的影响，在四缸增压中冷柴油机上，以FB50（50%煤基F-T柴油和50%生物柴油的混合物）为试验燃料，测量了标定转速2 100 r/min下，负荷为25%，50%和75%，EGR率为0，10%，20%和30%时的NOx，CO和HC比排放，研究了颗粒的粒径分布、碳氧质量之比（φC/O）、可溶性有机物与固态炭烟质量之比（φSOF/Soot）和氧化活性等特征参数。结果表明：在转速和负荷一定时， EGR能显著降低柴油机的NOx比排放，最大降幅为52%；EGR率高于20%时，中高负荷下CO，HC明显增加；随着EGR率的增加，小于1 μm颗粒的数密度逐渐增加。颗粒的φC/O与峰值粒径呈正相关，颗粒的φSOF/Soot与活化能呈负相关。EGR率在0~30%的范围内，低负荷时核态颗粒数密度增加，颗粒的φC/O变小，φSOF/Soot变大，颗粒易被氧化；中高负荷时积聚态颗粒的数密度明显增加，颗粒的φC/O变大，φSOF/Soot变小，颗粒较难被氧化。
In order to study the effects of exhaust gas recirculation (EGR) on the NOx, CO, HC and particle emission of coal-made fuel and biodiesel blended fuel, the measurement of NOx, CO and HC emission was conducted according to the set EGR rates of 0%, 10%, 20% and 30% on a 4-cylinder turbocharged intercooling diesel engine at rated speed of 2 100 r/min with 25%, 50% and 75% load, and the particle size distribution, carbonoxygen mass ratio (φC/O), ratio of soluble organic matter to solid soot mass (φSOF/Soot) and oxidation activity were also studied based on FB50 test fuel consisting of 50% coalbased FT diesel and 50% biodiesel. The test results showed that EGR could reduce the NOx emission of diesel engine significantly with the highest drop of 52% at a certain speed and load. CO and HC emissions increased obviously at medium and high load when the EGR rate was higher than 20%. The particle number concentration with the size of less than 1μm increased with the increase of EGR rate. In addition, φC/O had a positive correlation with peak particle size and φSOF/Soot had a negative correlation with oxidation activity. Within the range of EGR rate between 0 and 30%, the nuclear particle number concentration increased, φC/O decreased, φSOF/Soot increased and the particle oxidation became easy at low load, and the aggregated particle number concentration increased obviously, φC/O increased, φSOF/Soot decreased and the particle oxidation became difficult at medium and high load.
