基于EGR的乙醇-生物柴油-柴油发动机排放性能

在单缸风冷四冲程直喷柴油发电机上，燃用柴油、生物柴油、10%乙醇-45%生物柴油-45%柴油（E10B45D45）和20%乙醇-40%生物柴油-40%柴油（E20B40D40），采用16%、28% EGR率，测试并分析了经济性，NOx、HC和CO的排放性能和烟气的光吸收系数。研究表明：柴油的油耗最低，生物柴油次之，随着乙醇含量的增加，混合燃料的油耗增加；随着乙醇含量的增多，NOx排放量降低，与燃用柴油相比，E10B45D45和E20B40D40平均可降低约16.1%和30.2%；采用EGR可有效降低NOx排放，对应16%、28% EGR率，E10B45D45的NOx排放可平均降低19.3%和39.5%，E20B40D40平均降低10.7%和43.5%；随着乙醇含量的增多，HC排放量显著升高，对比于柴油，E10B45D45和E20B40D40分别升高了59.8%和172.1%；采用EGR后，HC排放增加；随乙醇含量的增加，CO排放也明显增大，对比于柴油，E10B45D45和E20B40D40分别升高了58.6%和131.1%；采用EGR后CO排放增加；各燃料中，柴油在小、中负荷烟气的光吸收系数最低，大负荷时却最高；不宜在小负荷时采用较高的乙醇掺混比和较大的EGR率。

Emission performance of ethanol-biodiesel-diesel engine with exhast gas recirculation

The economy and NOx, HC, and CO emissions performance and light absorption coefficient of exhaust were tested and analyzed on a single-cylinder air-cooled four-stroke diesel generator using exhaust gas recirculation (EGR) rates of 16% or 28% and diesel, biodiesel, 10% ethanol-45% biodiesel-45% diesel (E10B45D45), or 20% ethanol-40% biodiesel-40% diesel (E20B40D40) as fuels. The results show that the volume consumption of diesel fuel was the lowest, the volume consumption of E20B40D40 fuel was the highest, and the volume consumption of E10B45D45 fuel was higher than that of biodiesel. With an increase in ethanol volume fraction in blended fuel, NOx emissions decreased. For E10B45D45 and E20B40D40, the NOx emissions were lower by 16.1% and 30.2% when compared with the NOx emissions from diesel. EGR reduced NOx emissions. When using 16% and 28% EGR rates, the NOx emissions were reduced by 19.3% and 39.5%, respectively for E10B45D45 and 10.7% and 43.5% respectively for E20B40D40. With an increase in ethanol volume fraction in blended fuel, HC and CO emissions increased significantly. Compared to diesel fuel, HC emissions increased by about 59.8% and 172.1% for E10B45D45 and E20B40D40, respectively, and CO emissions increased by about 58.6% and 131.1%. With an increase in the EGR rate, the HC and CO emissions were higher. Compared to other fuels, the light absorption coefficient for diesel was the lowest for the light and medium loads and the highest for the heavy load. A larger ethanol blend ratio and a higher EGR rate were not suitable for the light load.