Mass‐transfer coefficients in washcoated monoliths

Bhattacharya, Madhuchhanda; Harold, Michael P.; Balakotaiah, Vemuri

doi:10.1002/aic.10212

Cited by 55 publications

(26 citation statements)

References 23 publications

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“…The solution of the latter is obtained by the finite Fourier transformation with the following assumptions: (i) convection is dominant over axial diffusion (axial Peclet number is very large), (ii) isothermal case with first order reaction (Rate = k C ), (iii) steady state, (iv) fully developed flow in a channel of circular cross‐section, and (v) washcoat thickness is small when compared with the channel hydraulic diameter so that curvature effects may be neglected. The resulting model and solution procedure and expressions for the exit cup‐mixing concentration in the fluid phase may be found in Bhattacharya et al25…”

Section: A Low‐dimensional Model For An Isothermal Monolith With Washmentioning

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: A Low‐dimensional Model For An Isothermal Monolith With Washmentioning

confidence: 99%

Low‐dimensional models for real time simulations of catalytic monoliths

2009

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“…Although the length scales are smaller, this is the same general configuration as catalytic monoliths or honeycomb reactors that are used in industrial applications 38–42. Continuum models have already been developed to describe monolith reactors,43–50 as well as related catalytic membrane reactors 51–62. Typically, these models have been solved using standard computational‐fluid dynamics (CFD) techniques, such as finite difference (FD) or finite element methods (FEM).…”

Section: Introductionmentioning

confidence: 99%

A multiscale scheme for modeling catalytic flow reactors

Majumder

Broadbelt

2006

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).A multiscale modeling approach was developed to capture concentration variations in the fluid in two dimensions for catalytic flow reactors. The methodology couples continuum descriptions of the fluid phase and kinetic Monte Carlo simulations of the catalyst domain. A number of catalytic domains, placed as patches along the length of the reactor, were solved using kinetic Monte Carlo (kMC) and linked with a finite difference (FD) solver for the fluid phase. Patch dynamics concepts, such as lifting, restriction and interpolation, were employed to provide the complete set of boundary conditions to the continuum solver. A simple kinetic mechanism involving adsorption, desorption and a single-step surface reaction was used to validate the approach by comparing the solution obtained using the multiscale scheme with a model solved using a wholly implicit solution. Solutions from a mean-field model and the multiscale scheme for a system in which surface diffusion was low were then contrasted.

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“…In order to understand the influence (and regimes of control) of kinetics and mass transfer within the packed bed, a researcher can use the Thiele modulus as a guide [55][56][57][58]. One can calculate the Thiele modulus of a species (f) using the activity of the species (k o ) along with the radius of the pellets (d p /2) and effective diffusivity of that species [59]:…”

Section: Governing Equation Of Chemical Speciesmentioning

confidence: 99%

One‐Dimensional Pseudo‐Homogeneous Packed‐Bed Reactor Modeling: I. Chemical Species Equation and Effective Diffusivity

Srinivasan¹,

Depcik²

2012

Chem Eng & Technol

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Packed-bed reactor experimentation is a key tool used in order to formulate chemical kinetics. The chemical species equation and overall methodology are described for a one-dimensional pseudo-homogeneous packed-bed reactor model useful for experimental calibration of chemical kinetics. Over the history of simulation development for this equation there exist numerous different effective diffusivity correlations. The included historical review and parametric study of these correlations help to determine the correct choice based on numerical simplicity and model outcomes. A subsequent review paper describes the energy equation and effective thermal conductivity correlations while coming to a generalized conclusion regarding modeling efforts.

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Mass‐transfer coefficients in washcoated monoliths

Abstract: The asymptotic mass-transfer

Cited by 55 publications

References 23 publications

Low‐dimensional models for real time simulations of catalytic monoliths

Low‐dimensional models for real time simulations of catalytic monoliths

A multiscale scheme for modeling catalytic flow reactors

One‐Dimensional Pseudo‐Homogeneous Packed‐Bed Reactor Modeling: I. Chemical Species Equation and Effective Diffusivity

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