Mathematical models of the monolith catalytic converter: Part II. Application to automobile exhaust

Abstract

Calculations are done for a series of mathematical models for a mono-Phenomena studied include axial conduction in the wall, diffusion and conduction in the gas in a transverse direction perpendicular to the flow direction, multiple steady states, and transients giving wall temperatures exceeding the adiabatic temperature.lith catalytic converter to oxidize carbon monoxide in automobile exhaust. SCOPEFor better or for worse, the use of catalytic converters to reduce automobile emissions of carbon monoxide and hydrocarbons has become a reality. Two types of catalytic converters are used for this application: packed beds and monoliths. The present study is concerned with mathematical models for the monolith converter. The simplest model which will give realistic predictions is determined, and the model calculations illustrate the important phenomena occurring in the device.Although conyiderable attention has been devoted to modeling packed-bed converters (Wei, 1975), little published information is available on modeling monolith Larry C. Young is with Amoco Production Company, Tulsa, Oklahoma.converters. Kuo (1973) developed a lumped parameter model for the monolith converter, which has been used by eight automobile and oil companies. Votruba et al. (1975) have also presented a similar model. Both these models include axial conduction in the wall. Hegedus (1974) neglects axial conduction. In a preliminary study, Young and Finlayson (1974) proposed and solved two models for the monolith, which cast some doubt on the validity of the simpler models. The essential question is whether or not to include diffusion and conduction in the fluid in a transverse direction perpendicular to the flow (and duct) axis, as did Young and Finlayson, or whether a simple lumped parameter model of this phenomenon, with specified Nusselt and Sherwood numbers,

Investigating carbon monoxide and propene oxidation on a platinum diesel oxidation catalyst

“…It is interesting to discuss a few early uses of the Voltz model, because these early works introduce some significant variations that have been incorporated by the majority of subsequent researchers. There were at least 27 publications up to and including 1980 that used the Voltz CO oxidation model, often in the context of catalytic converters, but these were mainly theoretical studies that simply used the Voltz model to represent a ‘typical’ LHHW type system . The first use, following publication of the original paper, of the Voltz model to fit experimental data came with three papers published from 1980 to 1985 .…”

Environmental Catalysis: Stationary Sources

“…Young and Finlayson (1976) modeled steady and unsteady-state heat and mass transfer processes for CO oxidation in a monolithic converter applicable to representative auto exhaust conditions. Young and Finlayson (1976) modeled steady and unsteady-state heat and mass transfer processes for CO oxidation in a monolithic converter applicable to representative auto exhaust conditions.…”

Influence of Spacing on the Thermal Efficiency of a Dual-Monolithic Catalytic Converter During Warmup

“…The reaction rate expressions for NO reduction kinetics were suggested by Subramaniam and Varma (1985). Young and Finlayson (1976) developed a two-dimensional reactor model in a pioneering work and presented the applicability of the quasi-steady assumption in the gas phase during transient operation. The majority of models are one-dimensional plug flow models (Oh and Cavendish, 1982;Eigenberger, 1996, 1997;Dubien et al, 1997;Siemund et al, 1996;Onorati et al, 2002;Subramanian et al, 2002), which neglect radial variations across the catalyst inlet and channels.…”