Numerical Prediction of Transient Conversion Characteristics in a Three-Way Catalytic Converter

Abstract

<div class="htmlview paragraph">This paper deals with oxygen storage effect and NOx conversion reaction modeling.</div> <div class="htmlview paragraph">It was found that the oxygen stored in the catalyst increases with catalytic wall temperature and lean ( or rich ) depth from experiments using a well controlled flow reactor. Oxygen storage-release model (OSR model), incorporated with the NOx reduction reaction and THC or CO oxidation reaction, was established from the experimental results.</div> <div class="htmlview paragraph">Reaction rate parameters for three-way catalyst have been determined from the least data of flow reactor experiments using Evolutionary Algorithm.</div> <div class="htmlview paragraph">Transient temperatures and emissions are predicted using the developed OSR model and the determined reaction rate parameters for three-way catalyst, which are incorporated in the numerical algorithms used in the previous paper to predict flow and temperature field in a catalytic converter.</div> <div class="htmlview paragraph">It was found that the predicted emissions (CO,THC,NOx) for early 120 sec of LA#4 mode test showed good agreement with measured emissions. Oxygen amount, stored in or released from the three-way catalytic converter, is higher in the front area of the converter and lower in the rear. Consequently, fluctuation of the air fuel ratio in the outlet gas from a three-way catalytic converter is greatly reduced by the oxygen storage effect.</div>