掺甲醇汽油对国III汽油机排放性能影响

在一台整车试验满足国III排放法规要求的多点电喷汽油机上,采用甲醇掺入汽油的混合燃料（甲醇的体积分数分别为0%、15%和50%）进行台架试验,使用傅里叶变换红外光谱分析仪（FTIR）在线检测了常规车用三效催化转化器前后的常规和非常规排放.研究结果表明：怠速工况下,掺醇燃料对NOx排放基本没有影响,但CO和HC随掺醇比增加而普遍降低,非常规排放中乙醛排放有所降低,甲醇和甲醛则随掺醇比的增加有较大幅度升高,热怠速时经催化后掺醇燃料对各种排放均无影响,可被控制在极低的水平;其它工况下,随掺醇比增加,CO和HC减少,NOx在高掺醇比下低速低负荷和高速高负荷时有较为明显的改善,非常规排放甲醛和甲醇排放随掺醇比增大而急剧增加,乙醛排放则随之减少.经三效催化转化器作用,无论常规排放NOx、CO和HC,还是非常规排放甲醛、甲醇和乙醛基本上能够实现零排放.

Effects of methanol-gasoline blend on emission characteristics of gasoline engine in National Grade III standard

Three different ratios of methanol-gasoline blends, 0%, 15% and 50% of methanol in volume, were tested in an electronically controlled multi-point port injection gasoline engine. Fourier transform infrared (FTIR) spectrometers were used to detect the regular and irregular exhaust emissions before and after the conventional three-way catalyst. The measuring results showed that at the cold idling speed, the blends with methanol did not have any impact to NO_x emission, but decreased CO and HC emissions as methanol percentage in the blends increased. Acetaldehyde decreased while formaldehyde and methanol emission increased. At warm idling speed, the blends with methanol did not have significant effects on pollutant emissions. While running at other operating conditions, CO and HC was reduced and NO_x was only improved when methanol percentage in the blends was high. The side emissions of formaldehyde and methanol increased tremendously, while acetaldehyde decreased. All emissions were reduced close to zero level after reaction of TWC.