Development of a light vehicle diesel aftertreatment system with DOC DPF and urea SCR

摘要

Meeting stringent emission regulations is a challenge to light vehicle diesel engines because of complexities of aftertreatment system, packaging constraints, and emission regulations. This article intends to introduce development philosophy from developing a light vehicle aftertreatment system that includes diesel oxidisation catalyst (DOC), catalytic diesel particulate filter (CDPF), urea injector and urea selective catalytic reduction (SCR). The development focus was on overall component planning to meet system emission targets at the early stage, system geometrical optimisations to meet pressure target at the intermediate stage, and design improvements of urea SCR module at the final stage. Both tests and modelling were employed seamlessly to reach decisions on major design directions. Significant efforts were spent on SCR mixing optimisation. Multiple mixer concepts were explored; the final developed SCR system was tested and able to meet all performance objectives. The roles of computational fluid dynamics (CFD) spray modelling and emission tests are discussed.