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A Model for the Flow Distribution in Dual Cell Density Monoliths. Processes (Basel) 2023. [DOI: 10.3390/pr11030827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
Abstract
Monoliths are promising as catalytic structured supports due to their many operational advantages. Compared to pellets, monoliths offer low backpressure and good heat distribution, even at high flow rates. There is interest in the industry for improving temperature control in highly exothermic systems, such as the catalytic hydrogenation of CO2 for e-fuels synthesis. In this context, novel substrate shapes, such as non-homogeneous cell density monoliths, show good potential; however, to date, they have only been sparsely described. This work focuses on a dual cell density substrate and uses a computational model of a straight-channel monolith with two concentric regions to analyze its flow distribution. The central (core) and peripheral (ring) regions of the substrate differ in cell density in order to obtain a non-homogeneous cross-section. The model is validated against classical data in the literature and theoretical equations. Then, the flow fraction passing through each region of the substrate is registered. Several flow rates, core sizes and combinations of apparent permeabilities are tested. According to the results, the flow distribution depends only on the monolith geometrical features and not on the flow rate. A model for this phenomenon is proposed. The model accurately predicted the flow fraction passing through each region of the monolith for all the cases analyzed.
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On the Use of Dual Cell Density Monoliths. Catalysts 2021. [DOI: 10.3390/catal11091075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
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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Hayes RE, Cornejo I. Multi‐scale modelling of monolith reactors: A 30‐year perspective from 1990 to 2020. CAN J CHEM ENG 2021. [DOI: 10.1002/cjce.24144] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Robert E. Hayes
- Department of Chemical and Materials Engineering University of Alberta Edmonton Alberta Canada
| | - Ivan Cornejo
- Departamento de Ingenieria Quimica y Ambiental Universidad Tecnica Federico Santa Maria Valparaiso Chile
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4
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Leskovjan M, Němec J, Plachá M, Kočí P, Isoz M, Svoboda M, Novák V, Price E, Thompsett D. Multiscale Modeling and Analysis of Pressure Drop Contributions in Catalytic Filters. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.0c05362] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Martin Leskovjan
- University of Chemistry and Technology, Prague, Department of Chemical Engineering, Technická 5, Praha 166 28, Czech Republic
| | - Jan Němec
- University of Chemistry and Technology, Prague, Department of Chemical Engineering, Technická 5, Praha 166 28, Czech Republic
| | - Marie Plachá
- University of Chemistry and Technology, Prague, Department of Chemical Engineering, Technická 5, Praha 166 28, Czech Republic
| | - Petr Kočí
- University of Chemistry and Technology, Prague, Department of Chemical Engineering, Technická 5, Praha 166 28, Czech Republic
- New Technologies Research Centre, University of West Bohemia, Univerzitní 8, Pilsen 306 14, Czech Republic
| | - Martin Isoz
- University of Chemistry and Technology, Prague, Department of Mathematics, Technická 5, Praha 166 28, Czech Republic
- Czech Academy of Sciences, Institute of Thermomechanics, Dolejškova 5, Praha 182 00, Czech Republic
| | - Miloš Svoboda
- New Technologies Research Centre, University of West Bohemia, Univerzitní 8, Pilsen 306 14, Czech Republic
| | - Vladimír Novák
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Emily Price
- Johnson Matthey Technology Centre, Blounts Court Road, Sonning Common, Reading RG4 9NH, United Kingdom
| | - David Thompsett
- Johnson Matthey Technology Centre, Blounts Court Road, Sonning Common, Reading RG4 9NH, United Kingdom
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A Review of the Critical Aspects in the Multi-Scale Modelling of Structured Catalytic Reactors. Catalysts 2021. [DOI: 10.3390/catal11010089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Structured catalytic reactors are enjoying an increasingly important role in the reaction engineering world. At the same time, there are large and growing efforts to use advanced computational models to describe such reactors. The structured reactor represents a multi-scale problem that is typically modelled at the largest scale only, with sub-models being used to improve the model granularity. Rather than a literature review, this paper provides an overview of the key factors that must be considered when choosing these sub-models (or scale bridges). The example structured reactor selected for illustration purposes is the washcoated honeycomb monolith design. The sub-models reviewed include those for pressure drop, inter- and intra-phase mass and heat transfer, and effective thermal conductivity.
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