Diesel Exhaust Clarification by a High-Pressure Injection in Combination with Selective Exhaust Gas Recirculation

本研究针对一种采用高压喷射和选择性废气再循环的新型柴油发动机系统，目的是找出显著减少柴油发动机颗粒物和氮氧化物的可能性。高压喷射是减少微粒的有效手段。因此，首先开发了全电子控制的高压喷射系统。该系统使用液压阀芯加速和油锤在一个收敛的管道。对该喷射系统的特性进行了详细的研究。在一台直喷式柴油机上进行了喷射系统试验，并通过理论研究确定了最佳喷嘴孔口。结果表明，由于喷射压力随发动机负荷的增大而增大，高负荷时的颗粒物和中负荷时的氮氧化物均得到了较好的降低。通过高速摄影对柴油机火焰的观察，发现高压喷射时火焰亮度波动减小。进一步减少氮氧化物的目的是使用选择性废气再循环，使用从废气中提取的二氧化碳和水的三原子气体。这些三原子气体具有较高的热容量，因此燃烧温度很好地降低到足以抑制一氧化氮。为了建立选择性水循环系统，首先对进气中水或湿气的引入对氧化氮还原的影响进行了实验研究。在此基础上，对不同发动机负荷下尾气冷凝水的再循环效果进行了预测。结果发现，在较高的负荷下，由于从废气中提取了更多的水，一氧化氮的显著减少是可以得到的。此外，还设计了废气中二氧化碳的再循环系统。该体系采用单乙醇胺溶剂作为化学吸光度剂。成功地建立了选择性再循环与高压喷射系统相结合的原型系统。少

This study dealt with a novel diesel engine system that uses high-pressure injection and selective exhaust gas recirculation, with an objective of finding out the possibility of a significant reduction of particulate matter and oxides of nitrogen from diesel engines. A High-pressure injection offers an effective means to reduce particulates. For this reason, a fully electronic controlled high-pressure injection system was first developed. The system uses hydraulic spool acceleration and oil-hammering in a convergent pipeline. The characteristics of this injection system were investigated in detail. Tests were made using the injection system at a direct-injection diesel engine with optimal nozzle-orifice determined by theoretical study. The result shows that particulate matter at a higher load and oxides of nitrogen at middle load are reduced successfully on account of the fact that the injection pressure increases with the engine load. According to observations of diesel flame by high- … More speed photography, fluctuations of flame luminosity is reduced at high-pressure injection.A further reduction of oxides of nitrogen is intended to use selective exhaust gas recirculation using triatomic gases of carbon dioxide and water both being extracted from the exhaust. These triatomic gases have higher heat capacity and as a result combustion temperature is well reduced enough to suppress nitric oxides. To establish the selective water recirculation, system, effects of the introduction of water or moisture in intake air on reduction of oxides of nitrogen were first investigated experimentally. Based on the results, prediction were made for the effect of recirculation of water that is condensed from exhaust gas for various engine loads. It was found that a remarkable reduction of nitric oxide is obtainable at higher loads, because of greater extraction of water from exhaust. Furthermore, the recirculation system of carbon dioxide in exhaust gas was designed. The system employed monoethanohl-amine solvent as chemical absorbance. A prototype system of selective recirculation combined with high-pressure injection system is established successfully. Less