聚甲氧基二甲醚对轻型柴油机排放特性的影响

为了降低柴油机的颗粒排放,将聚甲氧基二甲醚(PODE)按照体积分数10%,20%和30%掺混于柴油中,制备出柴油-PODE混合燃料(记为P10,P20和P30),在一台轻型柴油机上对柴油-PODE混合燃料进行了燃烧和排放特性试验研究,并采用热重方法分析了混合燃料的挥发性与氧化特性。结果表明:P10,P20和P30在常温下都具有良好的稳定性,在0~5℃区间PODE掺混比例高于20%将出现浑浊现象,混合燃料的黏度随着掺混比例增加与温度升高而逐渐下降;随PODE掺混比例的增加,混合燃料的活化能下降,综合燃烧指数提高,P10,P20和P30的起始失重温度相对于柴油分别降低了3.3,4.3,5.3℃,起始燃烧温度分别降低了9.4,17.8,24.2℃;柴油机燃用柴油-PODE混合燃料时,随着PODE掺混比例的增加,滞燃期缩短,放热率曲线和压力升高率曲线向前偏移,缸内最高压力提高;在标定工况下,燃用P10,P20和P30的烟度较燃用柴油分别降低了26.1%,31.2%和34.8%,颗粒物较柴油在各粒径下的质量浓度均有不同程度降低,且分布峰值向小粒径偏移。

Effect of Polyoxymethylene Dimethyl Ether on Light Duty Diesel Engine Emissions

In order to reduce diesel particulate matter emissions,the polyoxymethylene dimethyl ethers (PODE) were blended with diesel fuel in volume ratio of 10％,20％ and 30％,which was marked as P10,P20 and P30 sequentially.The effects of diesel/PODE blends on combustion and emission characteristics were experimentally investigated in a single-cylinder light duty diesel engine,and the volatility and oxidation characteristics of blended fuels were investigated with thermogravimetric analysis method.The results show that P10,P20 and P30 fuels have good stability at room temperature and the blend fuels with blending ratio above 20 ％ will appear turbid phenomenon at 0-5 ℃.The viscosity of diesel-PODE blends declines gradually with the increase of blending ratio and temperature.The activation energy decreases and the comprehensive combustion index improves with the increase of the blending ratio.Compared with diesel fuel,the initial weight loss temperatures of P10,P20 and P30 fuels decrease by 3.3,4.3,5.3 ℃ and the initial combustion temperatures of those fuels decrease by 9.4,17.8,24.2 C respectively.With the increase of blending ratio,the ignition delay period shortens,the heat release rate and the rate of pressure rise curves move forward,and the maximum cylinder pressure increases.At the rated condition,the smokes of P10,P20 and P30 fuels reduce by 26.1 ％,31.2％ and 34.8％ respectively.The particle mass concentration of blended fuels under different particle sizes decreases to some extent and its peak distribution moves to the small particle size.