Fluid flow through catalyst filled tubes

Bey, Oliver; Eigenberger, Gerhart

doi:10.1016/s0009-2509(96)00509-x

Cited by 227 publications

(175 citation statements)

References 22 publications

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“…Thus the model cannot predict the velocity maximum in the vicinity of the wall observed experimentally for those reactors [76] . An averaged velocity with a radial varying axial component can be provided by a further modification of the momentum balance [76][77][78] as improvement of the classical model.…”

Section: Momentum and Energy Equations For Porous Mediamentioning

confidence: 93%

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Computational Fluid Dynamics Simulation of Catalytic Reactors

Deutschmann

2008

Handbook of Heterogeneous Catalysis

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Catalytic reactors are generally characterized by the complex interaction of various physical and chemical processes. Monolithic reactors can serve as example, in which partial oxidation and reforming of hydrocarbons, combustion of natural gas, and the reduction of pollutant emissions from automobiles are frequently carried out. Figure 1 illustrates the physics and chemistry in a catalytic combustion monolith that glows at a temperature of about 1300 K due to the exothermic oxidation reactions. In each channel of the monolith, the transport of momentum, energy, and chemical species occurs not only in flow (axial) direction, but also in radial direction. The reactants diffuse to the inner channel wall, which is coated with the catalytic material, where the gaseous species adsorb and react on the surface. The products and intermediates desorb and diffuse back into the bulk flow. Due to the high temperatures, the chemical species may also react homogeneously in the gas phase. In catalytic reactors, the catalyst material is often dispersed in porous structures like washcoats or pellets. Mass transport in the fluid phase and chemical reactions are then superimposed by diffusion of the species to the active catalytic centers in the pores. The temperature distribution depends on the interaction of heat convection and conduction in the fluid, heat release due to chemical reactions, heat transport in the solid material, and thermal radiation. If the feed conditions vary in time and space and/or heat transfer occurs between the reactor and the ambience, a non-uniform temperature distribution over the entire monolith will result, and the behavior will differ from channel to channel.Today, the challenge in catalysis is not only the development of new catalysts to synthesize a desired product, but also the understanding of the interaction of the catalyst with the surrounding reactive flow field. Sometimes, the exploitation of these interactions can lead to

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Section: Momentum and Energy Equations For Porous Mediamentioning

confidence: 93%

“…An averaged velocity with a radial varying axial component can be provided by a further modification of the momentum balance [76][77][78] as improvement of the classical model.…”

Section: Momentum and Energy Equations For Porous Mediamentioning

confidence: 99%

Computational Fluid Dynamics Simulation of Catalytic Reactors

Deutschmann

2008

Handbook of Heterogeneous Catalysis

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“…The approach assuming constant unidirectional flow breaks down for fixed bed reactors with reactor diameters less than ten times the particle size. Thus the model cannot predict the velocity maximum in the vicinity of the wall observed experimentally for those reactors [56]. An averaged velocity with a radially varying axial component can be provided by a further modification of the momentum balance [56][57][58] as an improvement of the classical model.…”

Section: Modeling Gaseous Transport In Porous Catalystsmentioning

confidence: 96%

“…Thus the model cannot predict the velocity maximum in the vicinity of the wall observed experimentally for those reactors [56]. An averaged velocity with a radially varying axial component can be provided by a further modification of the momentum balance [56][57][58] as an improvement of the classical model. The reader is referred to the textbook by Keil [54] and references therein.…”

Section: Modeling Gaseous Transport In Porous Catalystsmentioning

confidence: 96%

Modeling of the Interactions Between Catalytic Surfaces and Gas-Phase

Deutschmann

2014

Catal Lett

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The catalytic surface interacts with the gasphase by a variety of chemical and physical processes. Hence, optimization of design and operation conditions of catalytic reactors do not only require the understanding of the catalytic reaction sequence but also its coupling with mass and heat transport and potential homogeneous reactions. The chemical, thermal, and mass-transport interactions between the catalytic surface and the gas-phase are discussed in terms of the individual and combined interactions. The state-of-the-art modelling of reactive flows and its coupling with the catalytic surface is summarized. The interactions are illustrated by a number of examples such as reforming of hydrocarbons, catalytic combustion, exhaust-gas after-treatment, each focusing on a special aspect of catalyst-gas interactions. The potentials and limitations of the numerical simulations will be discussed including experimental techniques for model validation.

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“…15 The theoretical analysis was complemented by sophisticated experiments for identifying model parameters and evaluating the simulation results. 16,17 Being aware of the inherent limitations of randomly packed beds, Gerhart shifted the focus to novel concepts in order to overcome these restrictions. Regular catalyst structures with efficient wall heat transfer were one of his focal points, 18 which led to the development of the folded sheet reactor.…”

mentioning

confidence: 99%