Influence of Pulsating Flow on Close-Coupled Catalyst Performance

Abstract

Close coupling of automotive three-way catalytic converters is becoming a common practice in order to reduce pollutant emissions during cold start. In such applications, the exhaust gas mass flow may fluctuate, as a function of crankshaft angle. A simplified one-dimensional channel model is developed, assuming that pollutant conversion in the catalyst is mass transfer limited. This model is applied to evaluate the effect of pulsations in catalyst performance, and assess the accuracy of the “quasi-steady state” approach usually involved in three-way catalytic converter models, when applied to simulate converters under pulsating flow.