The effect of oxygen storage capacity on the dynamic characteristics of an automotive catalytic converter

Automotive catalytic converters, which are employed to reduce engine exhaust emissions, are subjected to highly transient conditions during a typical driving cycle. These transient conditions arise from changes in driving mode, the hysteresis and flow lags of the feedback control system, and result in fluctuations of air–fuel ratio, exhaust gas flow rates and temperatures. The catalyst performance is also strongly influenced by the oxygen storage capacity. This paper presents a computational investigation of the effect of oxygen storage capacity on the dynamic behavior of an automotive catalytic converter subjected to modulations in exhaust gases. The modulations are generated by forcing the temporal variations in exhaust gases air–fuel ratio, gas flow rates and temperatures. The study employs a single-channel based, one-dimensional, non-adiabatic model. The results show that the imposed modulations cause a significant departure in the catalyst behavior from its steady behavior, and the oxygen storage capacity plays an important role in determining the catalyst’s response to the imposed modulations. Modulations and oxygen storage capacity are found to have relatively greater influence on the catalyst’s performance near stoichiometric conditions.