Mehrdad Ahmadinejad

Simulation of automotive emission control systems

Abstract As emissions requirements become evermore stringent, designing a system to meet the legislation subject to packaging and cost constraints becomes progressively more difficult. This is further exacerbated by increasing system complexity, where more than one technology may be required to control all the legislated pollutants and/or an active regeneration strategy is involved. By using computer simulation to aid design, this process can be considerably shortened, saving time and money. As an added bonus, the exercise of model development and application can lead to a greater understanding of the chemistry and physics of the system. This chapter gives an overview of some of the work done at Johnson Matthey on simulating emissions control devices. It covers both model development and the application of modelling to aid the design of exhaust aftertreatment systems. Simulation of the majority of emissions control technologies is covered, viz. 3-way catalysts for gasoline exhaust; and oxidation catalysts, urea/ammonia selective catalytic reduction, NO X traps and particulate filters for diesel exhaust. Examples of the application of modelling to consider parameters such as substrate (monolith) type, catalyst size and aspect ratio, engine calibration and precious metal loading and distribution are given.