高原环境下EGR中的各组分对柴油机性能的影响

摘要

The effects of exhaust gas recirculation(EGR)on the operation characteristics of diesel under high altitude were studied based on the one-dimensional simulation model of D19 high pressure common rail diesel engine. The effects of different components of EGR on combustion and emissions generation under high altitude(2,km)were ana-lyzed by coupling the CFD model with TRF chemical kinetic model. The calculation results show that the scope of EGR application will become narrower and soot emission will be more sensitive to EGR under high altitude. The inci-dental components of EGR have no obvious influence on heat release rate,pressure,temperature in cylinder and CO and soot emissions,but they will cause NO emission to derease first and then increase,resulting in a final value higher than that when there are only the main components. The trend of pyrene is different from that of benzene, naphthalene and phenanthrene under the effects of plateau environment and the EGR. A large amount of soot was gen-erated from pyrene under high temperature and hypoxic environment. As a result,the soot emission is seventimes that under the altitude of 0,km and in the absence of EGR.%基于D19型高压共轨柴油机的一维仿真模型，研究高原环境下EGR对柴油机工作特性的影响，并将其CFD 模型与 TRF 化学动力学模型耦合，研究高海拔下(2,km)EGR 中的各组分对燃烧及污染物生成的影响。结果表明：高原环境会使EGR适用范围缩小，使碳烟排放对EGR更加敏感；EGR中非主要组分对缸内放热率、压力、温度及CO排放、碳烟排放并无明显影响，但会导致NO排放呈现先减少后增加的趋势，其终值比只有EGR主要组分时的值高；在高原环境与 EGR 的共同作用下，芘与苯、萘、菲呈现不同的变化趋势，高温缺氧的环境使大量芘生成碳烟，且氧化量减少，导致碳烟终值约为0,km、无,EGR时的7倍。