A Simplified Three-Way Catalyst Model for Transient Hot-Mode Driving Cycles

Abstract

Numerous models for the simulation of chemical phenomena in three-way catalytic converters (3WCCs) have been proposed in the literature, ranging from models of the detailed mechanism of the catalytic reactions on the surface to purely empirical correlations for the pollutant conversion efficiency. The application of these models for transient exhaust-gas conditions, such as real-world driving cycles, usually involves a tradeoff between the chemical background of the model, on one hand, and the computational load and ease of model parametrization on the other. In this work, a simplified mathematical model to simulate pollutant conversion in three-way catalytic converters is developed, that has a low computational load and ease of parametrization as primary priorities, but without completely disregarding the chemical background. The intended application of this model is the simulation of pollutant emissions from pilot fleets of vehicles, under real-world driving cycles, starting with a hot engine. Its main novelty is that it models the complex chemical phenomena in a 3WCC almost entirely on the basis of oxygen storage and release dynamics. One-dimensional simulation of the heat-and mass-transfer phenomena is also included in the model, based on well-established approaches from the literature. The model is validated against a large database of measured driving cycles, performed with different types of passenger cars. It is found to present an acceptable degree of correlation between simulated and experimental results, in terms of both instantaneous and cumulative pollutant emissions.

A fleet-prediction oriented catalyst model for highly transient driving in cold and hot mode conditions

“…Consequently, the hot emissions of this generation of cars are significantly lower than that of former generations. 21 Model prediction is quite good.…”

“…The tests consisted of 36 real-world driving cycles, conducted at the chassis dynamometer of Empa. 21 The extension of the model to cold-start cycles took place in parallel with the extension of the database to Euro-4 certified vehicles. During 2009, four such cars were tested in 22 driving cycles, including tests beginning with cold engine.…”

Modeling of Three-Way Catalyst Dynamics for a Compressed Natural Gas Engine during Lean–Rich Transitions

“…Calibration of the kinetic reaction model inside the catalyst is certainly one of the most challenging topics. Several studies are available in literature, mostly concerning traditional gasoline spark ignition (SI) engines [9][10][11].…”

Extended Kalman filter and adaptive backstepping for mean temperature control of a three‐way catalytic converter

“…First principles modelling for the TWC usually leads to a mathematical description in form of partial differential equations (PDEs) (e.g. ). Thereby, the complexity of the model is mainly determined by the level of detail used to describe the chemical reactions within the TWC.…”

“…Thereby, the complexity of the model is mainly determined by the level of detail used to describe the chemical reactions within the TWC. Very detailed kinetic models are usually only used for simulation purposes, because the large number of participating chemical components brings about a high numerical complexity . Models that are to be used for control design are often significantly simplified, and the underlying PDEs are completely eliminated .…”