One + One‐Dimensional Modeling of Monolithic Catalytic Converters

Abstract

The inclusion of a washcoat model into monolithic catalyst simulations in order to create a one + one-dimensional framework using a minimum number of parameters is reviewed. All assumptions and numerical methods are presented while ensuring the prevention of excessive temperature excursions. Parametric studies illustrate the influence of model parameters (porosity, wall thickness, pore diameter) on the conversion of carbon monoxide during a light-off experiment using a uniform washcoat. Moreover, simulating a layered washcoat of dissimilar catalytic materials demonstrates a significant influence on conversion characteristics depending on the order of the layers. As a result, employing a washcoat requires careful consideration of the advection of the gas, the reactions occurring in each catalytic material, material layering, the diffusion properties of the different species, and the characteristics of the washcoat.

Adaptive Global Carbon Monoxide Kinetic Mechanism over Platinum/Alumina Catalysts

“…This embeds assumptions into the kinetic parameters reducing the physicality of the model. While it is possible to use more advanced and accurate simulation techniques (e.g., 1 + 1-D model by the authors [94]), this added computational effort made it unfeasible for calibration across all three hysteresis experiments.…”

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

“…The calculation of this parameter (and the Knudsen diffusivity, explained for the next correlation) can be found in another publication of the authors [52]. The calculation of this parameter (and the Knudsen diffusivity, explained for the next correlation) can be found in another publication of the authors [52].…”

“…As a result, the following model was created with its derivation explained in a previous paper [52]: w p 1 À 6:85 ln e (28) In 2000, Winterberg et al [4] demonstrate that the quasihomogeneous, one-phase model provides good accuracy in modeling packed-bed reactors with chemical reactions. As a result, the following model was created with its derivation explained in a previous paper [52]: w p 1 À 6:85 ln e (28) In 2000, Winterberg et al [4] demonstrate that the quasihomogeneous, one-phase model provides good accuracy in modeling packed-bed reactors with chemical reactions.…”

“…When modeling this mixing, researchers utilize a dispersion term D eff I À Á in the pseudo-homogeneous species equation instead of the effective diffusion coefficient as written (D eff ) [1,4,36,37,[49][50][51]. Note that for the presented model, the equation was derived using the assumption that the value of dispersion or diffusion does not change significantly in the z-direction [25,52]. The last term on the right-hand side includes the influence of the reaction rates R on the surface along with a catalytic surface area per unit volume term (G ca ).…”

“…Curve-fit (R 2 = 0.69) of mass transfer numbers in packed-bed reactors; summary of literature experimental data indicated is from Venderbosch[52].…”