Catalysts: Reactor Modeling Using Computational Fluid Dynamics

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Computational Catalysis".

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 11244

Special Issue Editors

Clausthal University of Technology, Institute of Chemical and Electrochemical Process Engineering, Leibnizstr 17, D-38678 Clausthal Zellerfeld, Germany
Interests: transport phenomena in chemical and electrochemical reactors; computational fluid dynamics (CFD) for reaction engineering; fixed-bed reactors; 3D printing
Special Issues, Collections and Topics in MDPI journals
Siemens Digital Industries Software, Simulation & Test Solutions, Nordostpark 3, 90411 Nürnberg, Germany
Interests: computational fluid dynamics (CFD) for reaction engineering; mixing; fixed-bed reactors; optimization

Special Issue Information

Dear Colleagues,

Many researchers today apply computational fluid dynamics (CFD) in order to gain insights into the complex interactions between local transport phenomena and local reaction rates occurring in many types of reactors. The purpose of these studies ranges from gaining benchmark data in order to calibrate engineering reactor models to design studies or assisting advanced reactor diagnostics. Since CFD modeling is basically independent from underlying geometries and correlations, its application spans across many reactor types, such as packed-bed, monolith, fluidized-bed, multiphase reactors, and many more. A crucial step, however, is the coupling of the CFD model with the appropriate kinetics. Therefore, potential contributions to this Special Issue include, but are not limited to, the following topics:

  • Single or multi-phase reactor CFD modeling;
  • Reactor design assisted by CFD;
  • Reactor diagnostics combining CFD and experimental in situ techniques;
  • Coupling strategies between kinetics solvers and CFD simulations;
  • Transient CFD simulations of reacting systems.

The purpose of the Special Issue “Recent advances in reactor modeling using computational fluid dynamics (CFD)” is to gather either review articles or original contributions in the field of CFD modeling in reacting systems and likewise activate the community to tackle urgent needs.

Prof. Dr. Gregor Dionys Wehinger
Guest Editor

Thomas Eppinger
Guest Editor Assistant

Manuscript Submission Information

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Keywords

  • catalysis
  • reactor modeling
  • computational fluid dynamics (CFD)
  • reactor design
  • transport phenomena
  • chemical reaction engineering
  • dynamics

Published Papers (5 papers)

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Research

19 pages, 4541 KiB  
Article
Hall Current and Soret Effects on Unsteady MHD Rotating Flow of Second-Grade Fluid through Porous Media under the Influences of Thermal Radiation and Chemical Reactions
by Omar T Bafakeeh, Kodi Raghunath, Farhan Ali, Muhammad Khalid, El Sayed Mohamed Tag-ElDin, Mowffaq Oreijah, Kamel Guedri, Nidhal Ben Khedher and Muhammad Ijaz Khan
Catalysts 2022, 12(10), 1233; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12101233 - 14 Oct 2022
Cited by 109 | Viewed by 2298
Abstract
The unsteady MHD free convection heat and mass transfer flow of a viscous, incompressible, and electrically conducting fluid passing through a vertical plate embedded in a porous medium in the presence of chemical reactions and thermal radiation is investigated. The effects of the [...] Read more.
The unsteady MHD free convection heat and mass transfer flow of a viscous, incompressible, and electrically conducting fluid passing through a vertical plate embedded in a porous medium in the presence of chemical reactions and thermal radiation is investigated. The effects of the Hall current, rotation and Soret are studied. Using the perturbation approach, one can obtain an accurate analytical solution to the governing equations for the fluid velocity, fluid temperature, and species concentration, provided that the initial and boundary conditions are acceptable. It is possible to obtain expressions for the shear stress, rate of heat transfer, and rate of mass transfer for both plates with the ramping temperature and isothermal conditions. On the one hand, the numerical values of the primary and secondary fluid velocities, fluid temperature, and species concentration are presented graphically. On the other hand, the numerical values of the shear stress and rate of mass transfer for the plate are presented in tabular form for various values of the relevant flow parameters. These values are given for a range of pertinent flow parameters. It was determined that an increase in the Hall and Soret parameters over the whole fluid area leads to a corresponding increase in the resulting velocity. The resultant velocity continually climbs to a high level due to the contributions of the thermal and solute buoyancy forces. Lowering the heat source parameter reduces the temperature distribution, resulting in a lower overall temperature. When there is a rise in the chemical reaction parameter over the whole fluid area, there is a corresponding decrease in the concentration. The concentration buoyancy force, Hall current, and Prandtl number reduce the skin friction. On the other hand, the permeability of the porous medium, rotation, chemical reaction, the Soret number, thermal buoyancy force, and mass diffusion all have the opposite effects on the skin friction. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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14 pages, 2644 KiB  
Article
Research on a New Drag Force Model for Cylindrical Particles in Fixed Bed Reactors
by Linbo Yan, Luchao Wang, Ziliang Wang, Cong Geng, Boshu He and Baizeng Fang
Catalysts 2022, 12(10), 1120; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12101120 - 27 Sep 2022
Viewed by 1444
Abstract
Fixed bed reactors play an important role in converting solid wastes to high-quality products. The solid wastes, as well as the corresponding catalysts, are often made into cylindrical particles. However, research on the drag force for cylindrical particles is still rarely reported. In [...] Read more.
Fixed bed reactors play an important role in converting solid wastes to high-quality products. The solid wastes, as well as the corresponding catalysts, are often made into cylindrical particles. However, research on the drag force for cylindrical particles is still rarely reported. In this work, the fixed bed porosity was firstly predicted with the unresolved CFD-DEM method and validated against experimental data. Then, the Ergun model, Di Felice model, and Ganser model were evaluated against the reported pressure drop data for both the spherical and cylindrical particles, so that a more solid drag force theory could be selected as a candidate for cylindrical particles. Finally, a new Ganser model was proposed for cylindrical particle drag force prediction based on the reported experimental results and validated by other experimental data. It was found that, for the spherical particle bed, the relative prediction errors of the Di Felice model are approximately 10%, while those of the Ergun model are approximately 15%. For the cylindrical particle bed, the relative prediction errors of the Ganser model are approximately 10%, while those of the Di Felice model are much higher than 10%. With the new Ganser model proposed in this work, the maximum error between the predicted pressure drop and the experimental data can be lowered to approximately 5%. The research is of reference value for drag force model selection when simulating similar FBRs with cylindrical particles. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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19 pages, 2516 KiB  
Article
Design of a Multi-Tubular Catalytic Reactor Assisted by CFD Based on Free-Convection Heat-Management for Decentralised Synthetic Methane Production
by Andreina Alarcón, Raquel Busqué, Teresa Andreu and Jordi Guilera
Catalysts 2022, 12(9), 1053; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12091053 - 16 Sep 2022
Cited by 2 | Viewed by 2823
Abstract
A simple reactor design for the conversion of CO2 methanation into synthetic methane based on free convection is an interesting option for small-scale, decentralised locations. In this work, we present a heat-management design of a multi-tubular reactor assisted by CFD (Ansys Fluent [...] Read more.
A simple reactor design for the conversion of CO2 methanation into synthetic methane based on free convection is an interesting option for small-scale, decentralised locations. In this work, we present a heat-management design of a multi-tubular reactor assisted by CFD (Ansys Fluent®) as an interesting tool for scaling-up laboratory reactor designs. The simulation results pointed out that the scale-up of an individual reactive channel (d = 1/4′, H = 300 mm) through a hexagonal-shaped distribution of 23 reactive channels separated by 40 mm allows to obtain a suitable decreasing temperature profile (T = 487–230 °C) for the reaction using natural convection cooling. The resulting heat-management configuration was composed of three zones: (i) preheating of the reactants up to 230 °C, followed by (ii) a free-convection zone (1 m/s air flow) in the first reactor section (0–25 mm) to limit overheating and, thus, catalyst deactivation, followed by (iii) an isolation zone in the main reactor section (25–300 mm) to guarantee a proper reactor temperature and favourable kinetics. The evaluation of the geometry, reactive channel separation, and a simple heat-management strategy by CFD indicated that the implementation of an intensive reactor cooling system could be omitted with natural air circulation. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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18 pages, 642 KiB  
Article
Numerical Assessment of Flow Pulsation Effects on Reactant Conversion in Automotive Monolithic Reactors
by Pratheeba Chanda Nagarajan, Henrik Ström and Jonas Sjöblom
Catalysts 2022, 12(6), 613; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12060613 - 03 Jun 2022
Cited by 3 | Viewed by 1410
Abstract
Highly transient engine-out emissions imply significant challenges for the optimization and control of automotive aftertreatment systems, motivating studies of the effects of flow pulsations on the system behavior. In this work, an axisymmetric aftertreatment system with a first-order reaction in the monolith section [...] Read more.
Highly transient engine-out emissions imply significant challenges for the optimization and control of automotive aftertreatment systems, motivating studies of the effects of flow pulsations on the system behavior. In this work, an axisymmetric aftertreatment system with a first-order reaction in the monolith section is chosen to demonstrate the role of pulsations on the time-averaged conversion at the exit. Reactive computational fluid dynamics simulations under transient conditions are performed by applying the SST k-ω turbulence model along with a reactant species balance equation and a porous medium description of the catalyst. Four different types of temporal velocity variations (constant, step-like, sawtooth and sinusoidal) are applied at the inlet. Additionally, the corresponding fluctuations driven by a prescribed inlet pressure are also investigated. It was found that the fluctuations in the incoming flow affect the transient response of the monolith, the time-averaged conversion, the evolution of the flow uniformity index and the dispersion downstream of the catalyst. It is also shown that the retention time distribution is modulated by the pulsations and that the mixed-cup conversion span is different for geometrically identical systems having the same velocity span if the fluctuation characteristics are different. In conclusion, simulations of phenomena that depend on time-resolved boundary conditions from experiments require proper characterization of fluctuations present in the real-world systems; otherwise, the method of recreating the signal at the boundary may influence the obtained results. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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17 pages, 20809 KiB  
Article
Non-Idealities in Lab-Scale Kinetic Testing: A Theoretical Study of a Modular Temkin Reactor
by Gregor D. Wehinger, Bjarne Kreitz and C. Franklin Goldsmith
Catalysts 2022, 12(3), 349; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12030349 - 18 Mar 2022
Cited by 9 | Viewed by 2520
Abstract
The Temkin reactor can be applied for industrial relevant catalyst testing with unmodified catalyst particles. It was assumed in the literature that this reactor behaves as a cascade of continuously stirred tank reactors (CSTR). However, this assumption was based only on outlet gas [...] Read more.
The Temkin reactor can be applied for industrial relevant catalyst testing with unmodified catalyst particles. It was assumed in the literature that this reactor behaves as a cascade of continuously stirred tank reactors (CSTR). However, this assumption was based only on outlet gas composition or inert residence time distribution measurements. The present work theoretically investigates the catalytic CO2 methanation as a test case on different catalyst geometries, a sphere, and a ring, inside a single Temkin reaction chamber under isothermal conditions. Axial gas-phase species profiles from detailed computational fluid dynamics (CFD) are compared with a CSTR and 1D plug-flow reactor (PFR) model using a sophisticated microkinetic model. In addition, a 1D chemical reactor network (CRN) model was developed, and model parameters were adjusted based on the CFD simulations. Whereas the ideal reactor models overpredict the axial product concentrations, the CRN model results agree well with the CFD simulations, especially under low to medium flow rates. This study shows that complex flow patterns greatly influence species fields inside the Temkin reactor. Although residence time measurements suggest CSTR-like behavior, the reactive flow cannot be described by either a CSTR or PFR model but with the developed CRN model. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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