掺混比对高压共轨柴油机 颗粒物物理特性的影响
Effects of PODE Blending Ratio on the Physical Characteristics of Particulate Matters for High？？Pressure Common？？Rail Diesel Engines

针对增压中冷高压共轨柴油机燃用不同聚甲氧基二甲醚(PODE)掺混比(10％、20％和30％,体积分数)的PODE/柴油混合燃料的颗粒物排放进行了实验研究。分析了PODE掺混比对柴油机NOx和烟度排放以及颗粒粒径分布的影响规律,并采用热重分析法与热解动力学方法研究了颗粒物氧化特性与热解反应活化能。实验结果表明:在柴油中掺混PODE能够降低烟度排放,且下降幅度随着PODE掺混比增加更明显,但在中高负荷时NOx排放略有增加;随着PODE掺混比增加,颗粒总数量浓度下降,粒径分布曲线向小粒径方向移动,核态颗粒所占比例增加,积聚态颗粒所占比例降低,颗粒的数量浓度峰值、表面积浓度峰值和体积浓度峰值均减小;在柴油中掺混PODE燃烧颗粒中可溶性有机物(SOF)组分含量增加,碳烟颗粒质量损失率峰值增加,质量损失率峰值所对应温度降低,颗粒热解反应活化能有所减小,颗粒更易被氧化。
Particulate matter emissions of polyoxymethylene dimethyl ethers (PODE)/diesel mixture with different PODE blending ratios (10％, 20％ and 30％) are conducted on a turbocharged intercooled high？？pressure common？？rail diesel engine. Effects of PODE blending ratio on the diesel NOx, smoke and particle size distribution are analyzed. The oxidation features and activation energy of pyrolysis of particles are studied by using the thermogravimetric analysis method and the pyrolysis kinetics method. Results show that the addition of PODE in diesel fuel reduces smoke emission and the decrement becomes more pronounced with the increase of PODE blending ratio. However, the NOx emissions increase slightly at medium and high loads. When PODE blending ratio increases, the total particle concentration decreases, the distribution curve of particle sizes shifts to the smaller particle size, the proportion of nucleation？？mode particles increases and the proportion of accumulation？？mode particles decreases. In addition, the peak values of particle number concentration, surface area concentration and volume concentration decrease. With the addition of PODE in diesel fuel, the content of soluble organic fraction (SOF) in particulate matters increases, the peak value of the mass loss rate of soot particles increases and its peak temperature decreases. Meantime, the activation energy of pyrolysis reaction of particles reduces, which indicates that the particles are more easily oxidized