Ultra Thinwall Light-off Performance - Varying Substrates, Catalysts, and Flow Rates; Models and Engine Testing

To establish performance trends in ultra thin wall substrates and help support their selection criteria for designing catalytic converter systems, the light-off behavior of five Ultra Thin Wall ceramic substrates and two catalysts on an engine dynamometer are hereby examined. Modeling predictions are also compared to the engine results and the trends and implications are discussed.

To quantify the performance of these different systems, light-off tests were performed on an engine dynamometer using a simulated FTP cycle. Five systems were evaluated (600/4, 600/3, 600/2, 900/2 and 1200/2) each with two different catalyst formulations. Engine bench aging was used to simulate typical aged conditions in the converter systems. Second by second emissions data for temperature, hydrocarbons and carbon monoxide, were used to evaluate the relative performances of the substrates. Next, the model was used to perform a parametric study to compare the performance of ultra thin wall ceramic substrates under various engine flow rate and temperature ramp regimes.

Engine dynamometer testing confirms the model predictions that a balance exists even in the light-off regime between bulk density and surface area, and that this balance is affected by catalyst changes.