Three-Way Catalytic Converter Modeling and Applications

Abstract

Rsprinu availablr diroctlg lrom the publisher Photocopying permitted by liscnv only Q 1998 OPA (OMnsas Publinhen Audntian) Arnrtcrdam B. V. Published under liscnw under the Gordon and B m h Science Publirhm imprint. Prinvd in India.The advent of stricter US. and European exhaust emissions regulations has increased the need for reliable 3-way catalytic converter models supporting the design of demanding exhaust systems for low-emitting vehicles. Although a number of tunable models have been presented in the literature, their efficient performance in actual 3-way applicaions requires further development and validation. The major difficulties posed in such modeling eRorts arise from the complexities in the reaction schemes and the respective rate expressions for the multitude of currently used catalyst formulations. This paper addresses the details of tuning and real world application of a two-dimensional catalytic converter model, which accounts for the HC (hvdrocarbons) and CO oxidation. as well as NO reduction reactions. The model features a &mber of innbvations regarding the catalyst transient behaviour modelling and the reaction kinetics scheme. The advanced oxygen storage submodel presented is capable of accounting for the redox and temoerature deoendence of the oxveen availabilitv under transient ooeration. The ,redox sensitivity of the reaction scheme allows to get clearer insight in the "lambda-window" behavior of 3-way catalysts. It is concluded, that mathematical modelling may successfully describe important aspects of real world three-way catalytic converter operation under dynamic conditions, and thus, is a valid tool in exhaust aftertreatment systems optimization.

NO2-Assisted Regeneration of Diesel Particulate Filters: A Modeling Study

“…Table 4 presents the kinetics employed in the model to describe the reactions in the oxidation catalyst. The reactions, kinetic expressions, and kinetic constants used in the present model are described in detail in ref 14. Figure 1 shows the measured NO 2 fraction in NO x after the oxidation catalyst as a function of temperature for the case of 6% O 2 .…”

Statistical uncertainty in automotive emissions testing

“…As a next step, the mathematical model described in [4,5] is employed in the computation of the catalytic converter behaviour in the legislated test. This model accepts as input the second-by-second variation in exhaust gas composition (CO, HC, NO, CO 2 , H 2 O, N 2 , O 2 ), exhaust gas mass flowrate and exhaust gas temperature at the catalytic converter inlet during the full test (i.e.…”

“…The above result in a variation of the catalyst conversion efficiency, mainly because catalyst activity is highly dependent upon temperature. The emissions variability of the specific car will be studied in the present paper, based on experimental data and a previously validated mathematical model of catalyst behaviour [4,5]. Figure 3 presents catalyst conversion efficiency regarding HC emissions of a reference diesel passenger car in the NEDC.…”

Dynamic behavior issues in three‐way catalyst modeling

“…The reactions, kinetic expressions, and kinetic constants used in the present model Ž . are listed in Appendix A Koltsakis et al, 1998 . According to Eq. 1, the rates of reaction and mass transfer to the catalytic surface are always in equilibrium, implying that there is no species accumulation phenomena on the solid catalytic surface.…”