Although there are already several works where the influence of injection parameters on exhaust emissions, and specifically on particulate matter emissions, in diesel engines has been evaluated, the diversity in the results that can be found in the literature indicates the need to carry out new experiments that can provide more information about the influence of these parameters on modern diesel engines. This study intends to be placed within this scientific framework, hence a parametric study was carried out based on the independent modification of the main injection timing and the injection pressure with respect to the nominal conditions of a new Euro VI direct injection diesel engine. Four steady-state operation points of the engine map were chosen: 25% load and 950 r/min, 50% load and 1500 r/min, 75% load and 2000 r/min and 100% load and 2200 r/min, where in each of these operation points, the variations of the injection parameters in the study on the combustion process and its consequent impact on the particle size distribution, including an analysis of the geometric mean diameter values, were evaluated. The results showed that the different injection strategies adopted, despite not significantly affecting the engine efficiency, did cause a significant impact on particle number emissions. At the low load operation, the size distribution showed a bimodal structure, and as the main injection timing was delayed and the injection pressure was decreased, the nucleation-mode particle concentration decreased, while the accumulation-mode particle concentration increased. In addition, at medium load, the nucleation-mode particle emission decreased considerably while the accumulation-mode particle emission increased, and this increase was much greater with the main injection timing delay and the injection pressure reduction. Similar behavior was observed at high load, but with a much more prominent pattern.

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评估喷射策略对欧 VI 中型柴油机燃烧过程和粒度分布的影响

虽然已经有几项工作评估了柴油发动机中喷射参数对废气排放的影响，特别是对颗粒物排放的影响，但文献中可以找到的结果的多样性表明需要进行新的实验这可以提供有关这些参数对现代柴油发动机影响的更多信息。本研究旨在置于该科学框架内，因此根据新的 Euro VI 直喷柴油发动机的标称条件，基于主喷射正时和喷射压力的独立修改，进行了参数研究。选择发动机图的四个稳态运行点：25% 负载和 950 r/min，50% 负载和 1500 r/min，75% 负荷和 2000 r/min 和 100% 负荷和 2200 r/min，其中在每个这些操作点，燃烧过程研究中喷射参数的变化及其对粒度分布的影响，包括对几何平均直径值的分析进行了评估。结果表明，采用的不同喷射策略，尽管对发动机效率没有显着影响，但确实对颗粒数排放产生了显着影响。在低负荷运行时，粒径分布呈双峰结构，随着主喷射时机的延迟和喷射压力的降低，成核模式粒子浓度降低，而积累模式粒子浓度增加。此外，在中等负载下，成核模式粒子发射显着减少，而积累模式粒子发射增加，并且随着主喷射时间延迟和喷射压力降低，这种增加更大。在高负载下观察到类似的行为，但具有更突出的模式。