(487am) Low-Dimensional Models for Real Time Simulations of Catalytic Monoliths

We present accurate low-dimensional models for real time simulation, control and optimization of monolithic catalytic converters used in automobile exhaust treatment. These are derived directly by averaging the governing equations and using the concepts of internal and external mass transfer coefficients. They are described by a system of differential algebraic equations involving multiple concentration and temperature modes and take into account washcoat diffusion as well as micro-kinetics effects accurately. The models reduce to the classical two-phase models in the limit of vanishingly thin washcoat. We demonstrate the application of the models by simulating the FTP cycle in real time. The effect of axial variation of precious metal loading on cumulative emissions is studied. The models are also useful for estimating the parameters in micro-kinetic reaction scheme. Further, we show the extension of the models to include oxygen or NOx storage, axial activity variation and period operation. It is shown that these new models are robust and accurate with practically acceptable error, speed up the computations by orders of magnitude, and can be used with confidence for the real time simulation and design of catalytic monoliths.