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In order to meet the increasingly stringent emissions standard it is imperative that a two pronged approach is pursued for reduction of tailpipe emissions. In this regard emissions, and often the exhaust compositions, are needed to be controlled both at its source and then subsequently cleaned up at the exhaust system. In addition, an aftertreatment system often consists of an array of catalysts and its performance depends on the transient characteristics of the exhaust gas composition. To complicate the matter furthermore, relevant technologies are still evolving at a rapid pace. Consequently, an aftertreatment modeling approach should not only be system based but also offer a high level of configurability. Thus a system level approach that includes a model of an engine and vehicle may provide an efficient means to analyze system performance and examine relative effects of competing phenomena and technologies.

This article describes a system level 1D simulation tool that has been constructed on the Quasi-steady (QS) method. By assuming that spatial changes are much greater than the temporal ones, rigorous 1D governing equations can be considerably simplified thus becoming less computationally demanding to solve and therefore suitable for control oriented modeling purposes. With the proposed tool exhaust pipe wall temperature profiles, including multiple-wall-layer configurations, are solved through a finite difference scheme. Momentum equation is included for predicting pressure losses due to frictions and geometric irregularity. Exhaust fluid properties (transport and thermodynamic) are evaluated according to NASA or JANAF polynomial thermal data basis. The proposed tool allows the consideration of an arbitrary number of chemical species and reactions in the entire system. A novel semi-automatic approach was developed to handle catalytic reaction kinetics intuitively.

Engines and vehicle systems are becoming increasing complex partly due to the incorporation of emission abatement components as well as control strategies that are technologically evolving and innovative to keep up with emissions requirements. This makes the testing and verification with actual prototypes prohibitively expensive and time-consuming. Consequently, there is an increasing reliance on Software-In-the-Loop (SIL) and Hardware-In-the-Loop (HIL) simulations for design evaluation of system concepts. This paper introduces a methodology in which detailed chemical kinetic models of catalytic converters are transformed into fast running models for control design, calibration or real time ECU validation. The proposed methodology is based on the use of a hybrid, structured, semi-automatic scheme for reducing high-fidelity models into fast running models.