A Review of the Critical Aspects in the Multi-Scale Modelling of Structured Catalytic Reactors

Cornejo, Iván; Hayes, Robert E.

doi:10.3390/catal11010089

Cited by 6 publications

(4 citation statements)

References 60 publications

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“…The values of the constants and blending functions, Equations ( 4) to (6), can be found in [24,25]. The term S u i in Equation (2) had a nonzero value only inside the porous medium and was used to account for the extra head loss due to flow passing through the monolith.…”

Section: Flow Modelmentioning

confidence: 99%

“…This type of substrate has proven to be convenient in many industrial processes, such as carbon dioxide hydrogenation [2], monopropellant thrusters [3], and pharmaceutical synthesis [4]. For some years, there has been an interesting discussion about the role of structured catalyst supports in the next generation of optimized substrates, where 3D printing and computational models are used as ideal tools to explore innovative substrate configurations [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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On the Use of Dual Cell Density Monoliths

2021

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Monolith-type substrates are extensively used in automotive catalytic converters and have gained popularity in several other industrial processes. Despite their advantages over traditional unstructured catalysts, such as large surface area and low pressure drop, novel monolith configurations have not been investigated in depth. In this paper, we use a detailed computational model at the reactor scale, which considers entrance length, turbulence dissipation and internal diffusion limitations, to investigate the impact of using a dual cell substrate on conversion efficiency, pressure drop, and flow distribution. The substrate is divided into two concentric regions, one at its core and one at its periphery, and a different cell density is given to each part. According to the results, a difference of 40% in apparent permeability is sufficient to lead to a large flow maldistribution, which impacts conversion efficiency and pressure drop. The two mentioned variables show a positive or negative correlation depending on what part of the substrate—core or ring—has the highest permeability. This and other results contribute relevant evidence for further monolith optimization.

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Section: Flow Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Use of Dual Cell Density Monoliths

2021

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“…Schematic representation of the elements of the reactor, from the full-scale reactor (a) to a honeycomb channel cross-section showing the wash-coat layer in light brown (e). Adapted from [17].…”

Section: Introductionmentioning

confidence: 99%

Transition of the Flow Regime Inside of Monolith Microchannel Reactors Fed with Highly Turbulent Flow

2023

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This paper investigates the flow behaviour of monolith microchannels. Specifically, the study characterizes the flow regime within in-series monolith channels where highly turbulent flow approaches them but inside of the channels, the Reynolds number is subcritical. Results from LES and a transitional RANS model are compared to those obtained when directly assuming laminar flow inside of the channels. A space-resolved model of channels placed in series and channel Reynolds numbers ranging from 50 to 300 are considered. The results show that the flow pattern in is almost identical in the two channels and that the frequency of fluctuations tends to increase with the Reynolds number. The flow regime in both channels is unsteady laminar, containing a wide spectrum of frequencies. The tested transitional RANS model (k-kL-ω) is unable to capture the velocity fluctuations predicted by LES. Despite the differences in the velocity field prediction, the pressure drop estimation from all models is practically the same. This study provides insights into the flow behaviour of monolith reactors and is useful for reactor design and optimization.

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“…During the last decades, monoliths have been tested in several other industrial applications, such as hydrogenation, peroxide oxidation, and low-temperature Fischer-Tropsch [11][12][13]. 3D-printing and advanced computational models have opened a door for novel substrate configurations, which, in turn, require advanced modeling for systematic optimization [14][15][16][17][18]. One of the main advantages that make monoliths suitable for process intensification is their practically linear relationship between pressure drop and flow rate.…”

Section: Introductionmentioning

confidence: 99%

A Model for Correcting the Pressure Drop between Two Monoliths

Cornejo

2021

Catalysts

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This paper is concerned with the modeling of the pressure drop through monolith honeycombs. Monolith substrates are promising for the intensification of catalytic processes, especially because of their low back-pressure. There have been several improvements in the modeling of monolith reactors during the last decade, most of them focused on a single substrate configuration, while research in multiple substrates in a single reactor is still sparse. One example is the so-called "minor losses", such as those because of the flow entering and leaving a substrate. Both phenomena interact when two monoliths are placed close in series, and the extra losses produced by them may become relevant when relatively short monoliths are used. In this paper, a spatially resolved computational model of monolith channels arranged in series is used to compute the extra pressure drop because of the flow leaving one substrate and entering the next one downstream. Several Reynolds numbers and spacing lengths for the channels between substrates are investigated. According to the results, for close-coupled monoliths, the inlet and outlet effects produce a negligible pressure drop compared to that in a single monolith configuration. This phenomenon can be accounted for by introducing a correction factor. The magnitude of the correction factor depends on the channel’s Reynolds number, diameter, and spacing length. A model for such a factor is proposed. The model accurately predicts the trend and magnitude of the correction factor.

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A Review of the Critical Aspects in the Multi-Scale Modelling of Structured Catalytic Reactors

Cited by 6 publications

References 60 publications

On the Use of Dual Cell Density Monoliths

On the Use of Dual Cell Density Monoliths

Transition of the Flow Regime Inside of Monolith Microchannel Reactors Fed with Highly Turbulent Flow

A Model for Correcting the Pressure Drop between Two Monoliths

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