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研究了一种高效低排放的稀混合燃烧——预混合压缩着火(PCI)燃烧系统,阐述了其优点及存在的问题。在PCI燃烧系统中,早在压缩行程就将燃油喷入燃烧室,经过较长时间的混合形成预混合稀混合气。试验发动机就由这种预混合的稀混合气自行着火燃烧而工作,从对燃烧的观察和数值模拟的结果可见,有必要防止油束附着在气缸壁和燃烧室壁上。因此,制造了低贯穿距的冲击-雾化油嘴并进行了试验。结果表明,可以实现很低的NO_x排放,燃油耗却增加很少,同时也发现PCI燃烧的发动机工作范围限制在部分负荷工况内,并引起HC排放增加。然而,由于它能获得放热等容度高的燃烧特性,因此,PCI燃烧系统可能代表着比传统柴油机更有效、更清洁的燃烧系统(超低NO_x和低烟度)。
A highly efficient and low emission lean mixture combustion - premixed compression ignition (PCI) combustion system was studied, its advantages and existing problems were expounded. In the PCI combustion system, fuel was injected into the combustion chamber as early as the compression stroke, forming a premixed lean mixture over a longer period of time. The test engine was operated by self-ignition combustion of this pre-mixed lean mixture. As a result of observation and numerical simulation of the combustion, it was found necessary to prevent the oil bundle from adhering to the cylinder wall and the combustion chamber wall. As a result, an impact-atomizing nozzle with low penetration was manufactured and tested. The results show that very low NO_x emissions can be achieved with little increase in fuel consumption. It is also found that the engine operating range of PCI combustion is limited to part load conditions and causes an increase of HC emissions. However, the PCI combustion system may represent a more efficient and cleaner combustion system (ultralow NO x and lower smoke) than traditional diesel engines due to its ability to achieve combustion characteristics with high exotherm equivalence.