Computer aided engineering in diesel exhaust aftertreatment systems design

Computer aided engineering (CAE) methodologies are increasingly being appli ed to assist the design of spark-ignition (SI) engine exhaust aftertreatmen t systems in view of the stage III and IV emissions standards. Following th is trend, the design of diesel exhaust aftertreatment systems is receiving more attention owing to the capabilities of recently developed mathematical models. The design of diesel exhaust systems must cope with three major af tertreatment categories: diesel oxidation catalysts, diesel particulate fil ters and de-NOx catalytic converters. An integrated CAE methodology that co uld assist the design of all these classes of systems is described in this paper. It employs the following computational tools: a computer code for mo delling transient exhaust system heat transfer, a computer code for modelli ng the transient operation of a diesel oxidation or a de-NOx catalytic conv erter, a database containing chemical kinetics data for a variety of oxidat ion and de-NOx catalyst formulations and a computer code for modelling the loading and regeneration behaviour of a wall-flow filter, assisted by catal ytic fuel additives. Application of the CAE methodology, which helps the ex haust aftertreatment system design engineer to meet the future emissions st andards, is highlighted by referring to a number of representative case stu dies.