Analysis of the mass transfer controlled regime in automotive catalytic converters

Santos, H.; Costa, Mário

doi:10.1016/j.ijheatmasstransfer.2007.04.044

Cited by 25 publications

(21 citation statements)

References 21 publications

(61 reference statements)

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“…In addition, this approach as used in the literature has its limitations (and conceptual difficulties), especially for the case of multiple reactions, time varying inlet and transient conditions and has not been validated, for example, by comparing the two‐phase model solution with that of the full governing equations. The recent experimental work of Santos and Costa15, 16 underscores the importance of including washcoat diffusional effects in the transient modeling of three‐way catalytic converters (TWCs).…”

Section: Introductionmentioning

confidence: 99%

Low‐dimensional models for real time simulations of catalytic monoliths

2009

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in Wiley InterScience (www.interscience.wiley.com).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 expressed in terms of three concentration and two temperature modes and include washcoat diffusional effects without using the concept of the effectiveness factor. The models reduce to the classical two-phase models in the limit of vanishingly thin washcoat. The models are validated by simulating the transient behavior of a three-way converter for various cases and comparing the predictions with detailed solutions. 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 control of monolithic and other catalytic reactors.

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Section: Introductionmentioning

confidence: 99%

Low‐dimensional models for real time simulations of catalytic monoliths

2009

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“…A major simplification in models used in the literature is to represent the multiple-channel reactor by a single channel with the assumption of equivalent passages with no interaction [6,7]. The catalyst is assumed to be perfectly insulated and it is exposed to a uniform flow.…”

Section: Introductionmentioning

confidence: 99%

“…The catalyst is assumed to be perfectly insulated and it is exposed to a uniform flow. The effects of thermal gradients in the radial direction are considered to be insignificant and the temperature and concentration profiles are assumed to be the same in all channels [6]. These assumptions simplify the problem significantly leading to a "single channel" model, and the performance predicted for one channel can be extended to the entire reactor [1].…”

Section: Introductionmentioning

confidence: 99%

“…Two broadly classified hierarchical models are used in the literature: Three-or two-dimensional (3-D or 2-D) convection-diffusion models with a wall reaction [8][9][10][11] and 1-D models, which describe the axial variation of a radially average concentration and temperature in a channel cross-section [2,6,8,[12][13][14]. Over the years, 1-D models became more popular because of their simplicity and the less computational time required for the solution of the pertinent differential equations [6] while they provide sufficiently accurate predictions and also allow for fast kinetic investigations.…”

Section: Introductionmentioning

confidence: 99%

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Mass and Heat Transfer Coefficients in Automotive Exhaust Catalytic Converter Channels

Templis

Papayannakos

2019

Catalysts

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Mass and heat transfer coefficients (MTC and HTC) in automotive exhaust catalytic monolith channels are estimated and correlated for a wide range of gas velocities and prevailing conditions of small up to real size converters. The coefficient estimation is based on a two dimensional computational fluid dynamic (2-D CFD) model developed in Comsol Multiphysics, taking into account catalytic rates of a real catalytic converter. The effect of channel size and reaction rates on mass and heat transfer coefficients and the applicability of the proposed correlations at different conditions are discussed. The correlations proposed predict very satisfactorily the mass and heat transfer coefficients calculated from the 2-D CFD model along the channel length. The use of a one dimensional (1-D) simplified model that couples a plug flow reactor (PFR) with mass transport and heat transport effects using the mass and heat transfer correlations of this study is proved to be appropriate for the simulation of the monolith channel operation.

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“…Three-way catalysts (TWCs) converters have been developed to control and reduce emissions of vehicles [7][8][9]. TWCs controls emissions of these three polluting gases simultaneously: (i) nitrogen oxides are reduced into nitrogen; (ii) hydrocarbons and carbon monoxide are subjected to catalytic combustion, which leads to carbon dioxide and water [2,3,5,[8][9][10][11]. Support materials have been used to provide stable and large surface area and thus reducing sintering of active particles of the catalyst [2,[12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Characterization and Activity of Pd–Ir Catalysts in CO and C3H6 Oxidation Under Stoichiometric Conditions

et al. 2016

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Bimetallic Pd-Ir catalysts based on halogen free precursors supported on alumina and La-stabilized alumina were prepared and characterized. The influence of iridium co-metal loading on activity of supported palladium catalysts in CO and C 3 H 6 oxidation was studied. In addition, the effect of thermal aging on the catalytic activity was discussed. The powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy combined with energy dispersive X-ray spectroscopy, thermogravimetric analysis were used for characterization of the catalysts. The catalytic activity of prepared catalysts was determined based on conversion of CO and C 3 H 6 under stoichiometric condition. The activity tests showed that bimetallic catalyst with Pd:Ir molar ratio of 1.00:0.18 on both support materials has the lowest light-off temperature difference between the fresh and aged catalysts in CO and C 3 H 6 oxidation. However, high Ir loading improved the activity of the catalysts only, if La-stabilized aluminum oxide was used as a support material. Lanthanum oxide promoted the activity of the fresh catalysts in CO and C 3 H 6 oxidation. Overall, Ir is a promising co-metal candidate for Pd-based catalyst for improving CO and C 3 H 6 oxidation activity of the catalyst under stoichiometric conditions.

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Analysis of the mass transfer controlled regime in automotive catalytic converters

Cited by 25 publications

References 21 publications

Low‐dimensional models for real time simulations of catalytic monoliths

Low‐dimensional models for real time simulations of catalytic monoliths

Mass and Heat Transfer Coefficients in Automotive Exhaust Catalytic Converter Channels

Characterization and Activity of Pd–Ir Catalysts in CO and C3H6 Oxidation Under Stoichiometric Conditions

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