CFD Study of Heat Transfer near and at the Wall of a Fixed Bed Reactor Tube:  Effect of Wall Conduction

A gas heated steam reformer (GHR) which converts natural gas to synthesis gas for methanol or Fischer-Tropsch purposes has been modelled for steady state conditions. The model is in two dimensions and is made up of a fixed bed reactor model, representing one of the reactor tubes in the GHR, and an annulus model, representing the annular space on the shell side of the GHR where hot, fully converted syngas emits heat to the reactor tube. The annulus model is described and evaluated in this article. This is a plug flow model which involves heat transfer in radial direction caused by radiation and by turbulence. The gas radiation is modelled by the use of the discrete ordinates method and the effect on heat transfer from turbulence is modelled as an effective radial thermal conductivity. Both heat transfer mechanisms vary with the radial position. An additional annulus model, made in the commercial CFD code FLUENT and based on the k-? turbulence model and the discrete ordinates radiation model, is used to estimate effective radial thermal conductivities. These were implemented in the annulus model of the GHR model. The reactor and the annulus models were combined and linked by the wall temperature profile and the heat flux profile on the outer reactor tube wall. The simulation results were used to study the heat flux and temperature profiles along the reactor length and the radial temperature profiles in the annulus.

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Oxidative dehydrogenation of ethane to ethylene over phase-pure M1 MoVNbTeOx catalysts in a micro-channel reactor

Catalysis Science & Technology ◽

10.1039/c4cy01742k ◽

2015 ◽

Vol 5 (5) ◽

pp. 2807-2813 ◽

Cited By ~ 21

Author(s):

Bozhao Chu ◽

Lara Truter ◽

Tjeerd Alexander Nijhuis ◽

Yi Cheng

Keyword(s):

Heat Transfer ◽

Oxidative Dehydrogenation ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Micro Channel ◽

Channel Reactor ◽

Reaction Conditions ◽

Oxidative Dehydrogenation Of Ethane ◽

Phase Pure

Due to its excellent heat transfer ability, the micro-channel reactor with coated phase-pure M1 catalysts can achieve reactor productivity nearly 5 times higher than that of a traditional fixed-bed reactor under the same reaction conditions in oxidative dehydrogenation of ethane (ODHE).

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Unidimensional heat transfer analysis of elephant grass and sugar cane bagasse slow pyrolysis in a fixed bed reactor

Fuel Processing Technology ◽

10.1016/j.fuproc.2004.05.014 ◽

2005 ◽

Vol 86 (5) ◽

pp. 565-575 ◽

Cited By ~ 18

Author(s):

J.M. Mesa-Perez ◽

L.A.B. Cortez ◽

J.D. Rocha ◽

L.E. Brossard-Perez ◽

E. Olivares-Gómez

Keyword(s):

Heat Transfer ◽

Sugar Cane ◽

Fixed Bed ◽

Sugar Cane Bagasse ◽

Fixed Bed Reactor ◽

Heat Transfer Analysis ◽

Elephant Grass ◽

Slow Pyrolysis

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Steady State Model for Heat Transfer in a Packed Bed Reactor of Elliptic Cylindrical Shape

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1771 ◽

2008 ◽

Vol 6 (1) ◽

Cited By ~ 2

Author(s):

Laércio G. Oliveira ◽

Ramdayal Swarnakar ◽

Antonio G. B. de Lima

Keyword(s):

Heat Transfer ◽

Steady State ◽

Fixed Bed ◽

Packed Bed ◽

Numerical Results ◽

Packed Bed Reactor ◽

Fixed Bed Reactor ◽

Dimensionless Temperature ◽

Cylindrical Shape ◽

Temperature Profiles

The fixed-bed reactors of circular cylindrical geometry with heated or cooled walls are frequently used to carry out heterogeneous reactions of solid-gas type in engineering applications. The design of a fixed bed reactor requires an extensive knowledge of heat transfer characteristics within the packed bed. In this sense, this work presents a three-dimensional mathematical model to predict the heat transfer inside a fixed bed elliptical cylinder heat exchanger. The model considers uniform velocity and temperature profiles of the fluid phase at the entrance of the reactor, and constant thermo-physical properties. The surface of the equipment convective boundary condition is assumed to be constant. The energy equation, written in the elliptical cylindrical coordinates, was discretized using a finite-volume method considering a fully implicit formulation, and WUDS interpolation scheme. Numerical results of the dimensionless temperature profiles inside the packed bed reactor at a steady state are presented and temperature distribution is interpreted. To validate the model, numerical results obtained for the circular cylinder are compared with analytical results from literature and a good agreement was obtained.

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Simultaneous estimation of kinetic and heat transfer parameters of a wall-cooled fixed-bed reactor

Chemical Engineering Science ◽

10.1016/0009-2509(96)00330-2 ◽

1996 ◽

Vol 51 (21) ◽

pp. 4791-4800 ◽

Cited By ~ 6

Author(s):

Zhen-Min Cheng ◽

Wei-Kang Yuan

Keyword(s):

Heat Transfer ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Simultaneous Estimation ◽

Transfer Parameters

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Heat Transfer inside Elliptic Cylindrical Reactor: Effect of Bed Porosity

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.336.97 ◽

2013 ◽

Vol 336 ◽

pp. 97-102

Author(s):

A.A. Silva Filho ◽

J.P. Silva de Almeida ◽

Antônio Gilson Barbosa de Lima

Keyword(s):

Heat Transfer ◽

Fixed Bed ◽

Three Dimensional ◽

Axial Direction ◽

Cylindrical Geometry ◽

Heat Diffusion ◽

Fixed Bed Reactor ◽

Three Dimensional Model ◽

Variable Porosity ◽

Steady State Heat Transfer

The study of heat transfer phenomenon in porous media by fluids percolated in the axial direction has been of interest to many researchers in various branches of science and technology. Applications are directed to different process such as filtration, distillation, absorption and adsorption in columns, drying and catalytic reactions in fixed beds. The literature has presented several solutions of the heat diffusion / convection equation in fixed bed reactors, but these studies are limited to a cylindrical geometry. In this sense, this work aim to present a pseudo-homogeneous three-dimensional model to describe the steady-state heat transfer within a fixed bed reactor with elliptic cylindrical geometry by considering variable porosity. The energy equation written in elliptical cylindrical coordinates and applied to the porous medium (particulate system) is discretized numerically using the finite volume method. Results of the temperature distribution within the bed are presented analyzed. It was verified that with increased porosity heat transfer inside the reactor tends to be more intense and thus, lower temperature gradients are found in all cross section of the reactor.

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CFD simulation of methanation reaction over 3D-printed monolithic catalysts: A comparative study

10.22541/au.161507434.44633739/v1 ◽

2021 ◽

Author(s):

Mingzheng Zhang ◽

Michelle Ng Xin Yi ◽

Ban Zhen Hong ◽

Liming Che ◽

Bing Hui Chen

Keyword(s):

Heat Transfer ◽

Cfd Simulation ◽

Hot Spot ◽

Fixed Bed ◽

Channel Structure ◽

Fixed Bed Reactor ◽

Monolithic Catalyst ◽

Methanation Reaction ◽

Monolithic Catalysts ◽

3D Printed

Exothermic methanation reaction from syngas to synthetic natural gas (SNG) in fixed-bed reactor suffers from hot-spot formation caused by limited heat transfer area and relatively poor radial heat transfer of catalyst particle packings. To address this issue, monolithic catalyst with excellent transport and mechanical properties is under development. In this contribution, CFD simulations of methanation reaction from syngas to SNG over three types of 3D-printed monolithic catalysts were performed. The simulation results are in good agreement with experimental ones. Compared with monolithic catalyst with honeycomb-shaped straight-channel structure or tetrahedral periodic structure, bio-inspired monolithic catalyst having the same characteristic of cancellous bone was found to be promising due to its lower pressure drop, better heat transfer, superior mass transfer and thus higher conversion of syngas. The mechanism and promising applications of 3D-printing bio-inspired monolithic catalyst are discussed.

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