Effect of perturbations in the exhaust gas composition on three-way catalyst light off

摘要

The influence of perturbations in the exhaust gas composition on the operation of three-way catalytic converters (3WCC) has been the subject of many research works. This paper aims to investigate the effect of such transients on the light-off temperature of a commercial 3WCC, by using a dynamic mathematical model for 3WCC simulation. This modeling approach embodies a comprehensive oxygen storage and release submodel into an existing 3WCC quasi-steady model. The dynamic model developed is validated against previously published experimental data, which imply that the presence of transients in the exhaust gas results in an improved low-temperature catalyst performance. Having validated the model, the improved light-off performance is investigated, and attributed primarily to exhaust gas stoichiometry and secondarily to the heat released in the catalyst by the oxidation reactions (self-acceleration). Finally, a parametric study is performed to assess the influence of different patterns of transient exhaust gas composition. The results obtained show that lean composition of the exhaust gas is more favorable during the light-off phase, while frequency and amplitude of the composition oscillation play only a minimal role. This investigation encourages further application of mathematical modeling in areas like lambda control strategy optimization, which were beyond the scope of earlier 3WCC models. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 23]