References of "Peters, Bernhard 50002840"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailComparison of ODE-based models for reactive oxygen species regulation system
Ignatenko, Andrew UL; Kolodkin, Alexey UL; Peters, Bernhard UL et al

in Proceedings of ICCSA 2014 (2014, June)

Reactive oxygen species (ROS) play important role in the functioning of any cell and especially in the lifecycle of mitochondria. Since the action of ROS can be both positive and negative then the ... [more ▼]

Reactive oxygen species (ROS) play important role in the functioning of any cell and especially in the lifecycle of mitochondria. Since the action of ROS can be both positive and negative then the remarkable role can be played by ROS regulation system. We constructed three different ODE based kinetic models of different complexity for the ROS management system and shown the difference in the dynamics of these systems under different conditions. Using results of numerical simulation we showed that extraction of some subsystems can make the model more unstable. We also introduced the objective function for comparison of the models with structure of different complexity [less ▲]

Detailed reference viewed: 128 (34 UL)
See detailROS-activated signaling network: dynamic modelling and design principles study
Kolodkin, Alexey UL; Ignatenko, Andrew UL; Sangar, Vineet et al

Poster (2014, June)

Detailed reference viewed: 116 (11 UL)
See detailDynamic modelling of ROS management and ROS-induced mitophagy
Kolodkin, Alexey UL; Ignatenko, Andrew UL; Sangar, Vineet et al

Poster (2014, June)

Detailed reference viewed: 92 (16 UL)
Full Text
Peer Reviewed
See detaileXtended Discrete Element Method used for predicting tungsten-oxide reduction in a dry-hydrogen atmosphere
Estupinan Donoso, Alvaro Antonio UL; Peters, Bernhard UL

in LLanes, Luis (Ed.) eXtended Discrete Element Method used for predicting tungsten-oxide reduction in a dry-hydrogen atmosphere (2014, March 10)

Detailed reference viewed: 175 (23 UL)
Full Text
Peer Reviewed
See detailDetailed numerical modeling of pyrolysis in a heterogeneous packed bed using XDEM
Mahmoudi, Amir Houshang UL; Hoffmann, Florian UL; Peters, Bernhard UL

in Journal of Analytical and Applied Pyrolysis (2014), 106

Detailed reference viewed: 175 (23 UL)
Full Text
Peer Reviewed
See detailApplication of XDEM as a novel approach to predict drying of a packed bed
Mahmoudi, Amir Houshang UL; Hoffmann, Florian UL; Peters, Bernhard UL

in International Journal of Thermal Sciences (2014), 75

A majority of solid fuels especially biomass contains moisture, which may amount up to the mass of the dry particles. Thus it is important to determine the details of drying when considering biomass as a ... [more ▼]

A majority of solid fuels especially biomass contains moisture, which may amount up to the mass of the dry particles. Thus it is important to determine the details of drying when considering biomass as a fuel. Therefore, the objective of this work is to apply the Extended Discrete Element Method (XDEM) as a numerical simulation framework to prediction of drying within a packed bed reactor. The novel numerical concept resolves the particulate phase by the classical Discrete Element Method (DEM), however, extends it by the thermodynamic state e.g. temperature distribution and evaporation of water content of each particle in conjunction with heat and mass transfer to the surrounding gas phase. The latter is described by a continuous approach namely a set of differential conservation equations as employed in Computational Fluid Dynamics (CFD) for porous media. Comparison with measurement was carried out and good agreement was achieved. [less ▲]

Detailed reference viewed: 170 (28 UL)
Full Text
Peer Reviewed
See detailXDEM employed to predict reduction of tungsten oxide in a dry hydrogen atmosphere
Estupinan Donoso, Alvaro Antonio UL; Peters, Bernhard UL

in International Journal of Refractory Metals & Hard Materials (2014)

Abstract The Extended Discrete Element Method (XDEM) is a novel concept to model tungsten oxides reduction. The concept extends the classical discrete element method (DEM) with additional properties such ... [more ▼]

Abstract The Extended Discrete Element Method (XDEM) is a novel concept to model tungsten oxides reduction. The concept extends the classical discrete element method (DEM) with additional properties such as the thermodynamic state. Moreover, the concept treats a solid phase represented by particles, and a fluid phase as two distinguished phases that are coupled through heat, mass and momentum transfer. hydrogen atmosphere is modelled by a direct oxygen removal from the solid oxides mechanism for which temperature and reaction progress is described by the Discrete Particle Method (DPM). An outstanding feature of the herein proposed numerical concept is that powder particles are treated as individual entities which are described by its thermodynamic state, e.g. temperature and species distribution within the particle. Therefore, it allows a detailed and accurate characterisation of isothermal literature experimentation with a high degree of accuracy. Therefore, the current approach provides a new and deep insight into the process, because particle temperatures, concentration of species and interaction of particles with the environment are inaccessible in a furnace during experiments. [less ▲]

Detailed reference viewed: 82 (8 UL)
Full Text
Peer Reviewed
See detailXDEM - FEM Coupling Simulations of the Interactions between a Tire Tread and Granular Terrain
Michael, Mark UL; Vogel, Frank; Peters, Bernhard UL

E-print/Working paper (2014)

This study proposes an efficient combination of the Discrete Element Method (DEM) and the Finite Element Method (FEM) to study the tractive performance of a rubber tire in interaction with granular ... [more ▼]

This study proposes an efficient combination of the Discrete Element Method (DEM) and the Finite Element Method (FEM) to study the tractive performance of a rubber tire in interaction with granular terrain. The presented approach is relevant to all engineering devices interacting with granular matter which causes response forces. Herein, the extended discrete element method (XDEM) is used to describe the dynamics of the granular assembly. On the one hand, the discrete approach accounts for the motion and forces of each grain individually. On the other hand, the finite element method accurately predicts the deformations and stresses acting within the tire tread. Hence, the simulation domain occupied by the tire tread is efficiently described as a continuous entity. The coupling of both methods is based on the interface shared by the two spatially separated domains. Contact forces develop at the interface and propagate into each domain. The coupling method enables to capture both responses simultaneously and allows to sufficiently resolve the different length scales. Each grain in contact with the surface of the tire tread generates a contact force which it reacts on repulsively. The contact forces sum up over the tread surface and cause the tire tread to deform. The coupling method compensates quite naturally the shortages of both numerical methods. It further employs a fast contact detection algorithm to save valuable computation time. The proposed DEM-FEM Coupling technique was employed to study the tractive performance of a rubber tire with lug tread patterns in a soil bed. The contact forces at the tread surface are captured by 3D simulations for a tire slip of 5%. The simulations showed to accurately recapture the gross tractive effort, running resistance and drawbar pull of the tire tread in comparison to related measurements. Further, the traction mechanisms between the tire tread and the granular ground are studied by analysing the motion of the soil grains and the deformation of the tread. [less ▲]

Detailed reference viewed: 277 (22 UL)
Full Text
See detailEvaluation of heat transfer on a backward acting grate
Peters, Bernhard UL; Džiugys

in MECHANIKA (2014), 20

Detailed reference viewed: 96 (10 UL)
Full Text
See detailAn Efficient 3D FEM - DEM Coupling for Granular Matter Applications
Michael, Mark UL; Peters, Bernhard UL; Vogel, Frank

in Coupled MBS-FE Applications: A New Trend in Simulation (2013, November)

The presented approach is relevant to almost all engineering applications that deal with granular matter such as off-road tire performance, transport on conveyor belts or displacement of granular material ... [more ▼]

The presented approach is relevant to almost all engineering applications that deal with granular matter such as off-road tire performance, transport on conveyor belts or displacement of granular material as in mixers or excavation of soil. For all these applications an engineering device is in contact with granular matter which causes responses due to the interaction forces. The proposed Extended Discrete Element Method (XDEM) as a combination of the Discrete Element Method (DEM) and the Finite Element Method (FEM) allows to sufficiently resolve the different domains involved in these engineering applications. Herein the motion of each grain is accounted for individually. Simultaneously, the finite element method accurately predicts the deformations experienced by the engineering device. Thus, the simulation domain occupied by the device is efficiently described as a continuous entity. The coupling of both methods is based on the interface shared by the two spatially separated domains. The interface coupling enables to apply a contact model suited to the particular contact behaviour between the grains and the surface material if the engineering device. In contact, forces develop at the interface and generate an responce in each domain. The coupling method enables to capture both responses simultaneously. Each grain in contact with the device surface generates a contact force to which it reacts repulsively. The contact forces sum up over the surface and cause deformations of device body. It further employs a fast contact detection algorithm to save valuable computation time. This concept is supported by the software tools of the Discrete Particle Method (DPM) and Diffpack. To exemplify the presented method, the tractive performance of different tire treads has been studied on a soil layer of the stony terrian. The simulation results are used to analyse the gross tractive effort, running resistance and drawbar pull of the different tread patterns. [less ▲]

Detailed reference viewed: 272 (11 UL)
Full Text
Peer Reviewed
See detailSimulation des Traktionsverhaltens von Reifen auf granularem Untergrund durch eine Kopplung zwischen der Finiten (FEM) und der Diskreten Element Methode (DEM)
Michael, Mark UL; Peters, Bernhard UL; Vogel, Frank

in VDI-Berichte "Reifen-Fahrwerk-Fahrbahn" (2013, October)

Kurzfassung Innerhalb dieses Beitrags wird die numerische Simulationsmethode der Extended Discrete Element Methode (XDEM) vorgestellt, mit der die Wechselwirkung zwischen Reifen und steinigem Untergrund ... [more ▼]

Kurzfassung Innerhalb dieses Beitrags wird die numerische Simulationsmethode der Extended Discrete Element Methode (XDEM) vorgestellt, mit der die Wechselwirkung zwischen Reifen und steinigem Untergrund detailliert beschrieben werden kann. Dabei wird der Reifen als ein Kontinuum betrachtet, das mit der Finiten Element Methode (FEM) abgebildet wird. Der grobkörnige Untergrund, wie beispielsweise Sand oder Kies, wird als granulares Medium betrachtet. Dieses kann sehr vorteilhaft mit der Diskreten Element Methode (DEM) behandelt werden, die eine Betrachtung der individuellen Partikel zulässt. Basierend auf den Gesetzen von Newton werden Position und Orientierung aller Partikel berechnet, wobei Kräfte zwischen den Partikeln und dem Reifen berücksichtigt werden. Kräfte zwischen Partikeln und Reifen treten als Randbedingungen in der FEM Struktur des Reifens auf, und führen damit zur Deformation und somit zu Spannungverteilung in der Reifenstrucktur. Eine Integration in der Zeit bestimmt sowohl den Zustand des Untergrunds als auch die Reaktion des Reifens. Dies wird durch eine innovative Kopplung zwischen der Discrete Particle Method (DPM) zur Beschreibung des granularen Mediums und dem Finite Element Löser DiffPACK erreicht und deshalb als Extended Discrete Element Methode bezeichnet wird. Beides sind objekt- orientierte Software-Werkzeuge, die über eine Schnittstelle die notwendigen Daten austauschen, so dass der Anwender sein Augenmerk auf die Problemlösung richten kann als sich mit Datenaustausch und Algorithmen zu befassen. Damit wurde ein vielseitiges und flexibles Werkzeug zur Lösung vielfältiger Probleme wie auch die Bewegung eines Reifens im Schnee geschaffen. Das neuartige Konzept ist sowohl auf Windows als auch auf UNIX basierenden Betriebssystemen verfügbar. Abstract The objective of this contribution is to resolve different length scales in structure analysis by an interface coupling the Discrete Element Method (DEM) with the Finite Element Method (FEM) and therefore, is labelled Extended Discrete Element Methode (XDEM). This approach distinguishes itself from other methods in so far that no overlapping domains between Finite and Discrete Elements exist. Both domains are separated in physical space and numerical simulation domain. The proposed approach is relevant to almost all engineering applications that deal with granular matter such as storage in hoppers, transport on conveyor belts or displacement of granular material as in mixers or excavation of soil. For these applications an engineering device such as mixer blades or cutting tools are in contact with granular matter. Contacts with individual particles generate contact forces that act on both the engineering device and the granular material. The latter experiences a displacement of individual particles whereby the engineering structure responds with deformation and stresses. In order to predict and optimize both the behaviour and motion of granular material and the structures in contact, numerical simulation tools are increasingly employed [1]. Simulations are popular especially because experiments which are often expensive, time- consuming and sometimes even dangerous [2]. The continuous increase in computing power is now enabling researchers to implement numerical methods that do not focus on the granular assembly as an entity, but rather deduce its global characteristics from observing the individual behaviour of each grain. An interaction between granular media and a structure relies on a transfer of forces between them. Granular media consists of an ensemble of particles of which a number of particles may be in contact with a surface e.g. walls as surfaces of solid structures. The contact is resolved similar to inter-particle contacts by a representative overlap. It defines the position of impact as well as the force acting on the particle at this position. The same force, however, into the opposite direction defines a mechanical load for the structure. In order to determine the effect of forces on the solid structure, it is discretised by finite elements. The impact of the force is transferred to the nodes of the respective surface element and appears as a load for the finite element system. Hence, integrating particle dynamics and the response of the solid structure due to particle impacts advances both new position of particles and corresponding deformation and stress of the solid structure in time. Developing flexible software which is capable of performing simulation in different applications will enable the engineers to focus entirely on their specific problem and hence save them valuable time. This concept is supported by the software tools of the Discrete Particle Method (DPM) and Diffpack. Hence, the solid structure is analysed by the Finite Element Method under load due to the impact of individual particles that changes both in time and space. For this purpose traditional formulations of the Finite Element Method are employed that are available by the commercial multi-physics software package Diffpack. It represents object-oriented hierarchy of classes that provide an excellent interface to introduce external loads from particle impact onto the finite element structure. Diffpack is an object-oriented development environment, which comes as a rich set of C++ classes, for the numerical modelling and solution of arbitrary differential equations. User applications cover a wider range of engineering areas and span from simple educational applications to major product development projects. The behaviour of granular material is represented by the advanced software package of the Discrete Particle Method (DPM), which is based on the Discrete Element Method. It is designed to relieve users from underlying mathematics and software design and allows them to focus on physics and their applications. The software uses object oriented techniques that support objects representing three-dimensional particles of various shapes such as cylinders, discs or tetrahedrons for example, size and material properties. This makes it a highly versatile tool dealing with a large variety of different applications of granular matter arising in the automotive industry, such as road tire interaction. Various force models for the inter- particle and particle-wall contacts are also available. A minimal user interface easily allows extending the software further by adding user-defined impact models or material properties to an already available selection of materials and properties. Thus, the user is relieved of the underlying mathematics or software design, and therefore, is able to direct his focus entirely onto the application. The Discrete Particle Method is written in C++ programming language and works both in Linux and Windows environments. [less ▲]

Detailed reference viewed: 163 (9 UL)
Full Text
See detailDesign principles study of ROS management and ROS-induced mitophagy with a kinetic model
Kolodkin, Alexey UL; Ignatenko, Andrew UL; Sangar, Vineet et al

Poster (2013, September 27)

In vivo evidence demonstrates three fundamental interconnected adaptive survival mechanisms , which protect against excessive ROS that is generated during mitochondrial dysfunction: (i) autophagy ... [more ▼]

In vivo evidence demonstrates three fundamental interconnected adaptive survival mechanisms , which protect against excessive ROS that is generated during mitochondrial dysfunction: (i) autophagy/mitophagy, (ii) adaptive antioxidant response and (iii) NFkB signaling in cancer and neurodegeneration. We have been expanding a kinetic model which recapitulates the consensus understanding of the mechanisms responsible for cellular ROS – management system and performed modular analysis to analyze emergent behavior. We started with the simplest model and added stepwise new modules. We identify the qualitative role (certain emergent behavior) attributed to each module and thus understand the design principles of the system. We propose a detailed, mechanistic, kinetic model for studying how mutations relevant for diseases such as PD and cancer affect the emergent behavior of ROS management network. [less ▲]

Detailed reference viewed: 239 (11 UL)
Full Text
Peer Reviewed
See detailDie Extended Discrete Element Method (XDEM) als integraler Ansatz für reagierende Mehrphasenströmungen
Peters, Bernhard UL; Amir, Mahmoudi

in 26. Deutscher Flammentag Verbrennung und Feuerung (2013, September)

Eine Großzahl technischer Anwendungen wie beispielsweise in der pharmazeutischen Industrie, Nahrungsmittelindustrie, Bergbau, Verfahrenstechnik oder Energiegewinnung durch Verbrennung von Feststoffen ... [more ▼]

Eine Großzahl technischer Anwendungen wie beispielsweise in der pharmazeutischen Industrie, Nahrungsmittelindustrie, Bergbau, Verfahrenstechnik oder Energiegewinnung durch Verbrennung von Feststoffen enthalten neben einer gasförmigen oder fluiden Phase eine diskrete Phase in Form von Partikeln oder Feststoffen. Diese Anwendungen lassen sich sehr vorteilhaft mit dem innovativen Konzept der Extended Discrete Element Method (XDEM) numerisch beschreiben. Hierbei werden die einzelnen Partikel über den dynamischen Zustand (Position und Orientierung) und den thermodynamischen Zustand (Temperatur und Spezies) diskret beschrieben, wo hingegen die Gas- oder Flüssigphase über kontinuumsmechanische Ansätze der Computational Fluid Dynamics (CFD) berechnet wird. Beide Phasen – diskret und kontinuumsmechanisch – sind durch Austausch von Stoff, Wärme und Impuls gekoppelt, was damit eine detaillierte Auflösung der Phasen für CFD-Gesamtrechnungen ermöglicht. Dieser Ansatz wurde angewendet, um den Reaktionsprozess während der Pyrolyse von Holz in einem Festbettreaktor zu berechnen. [less ▲]

Detailed reference viewed: 65 (6 UL)
Full Text
Peer Reviewed
See detail3D DEM – FEM Coupling to Analyse the Tractive Performance of Different Tire Treads in Soil
Michael, Mark UL; Peters, Bernhard UL

in Idelsohn, S; Papadrakakis, M; Schrefler, B (Eds.) Computational Methods for Coupled Problems in Science and Engineering V (2013, June)

This contribution investigates the tractive performance of different tire treads on granular terrain by an efficient combination of the Discrete Element Method (DEM) and the Finite Element Method (FEM ... [more ▼]

This contribution investigates the tractive performance of different tire treads on granular terrain by an efficient combination of the Discrete Element Method (DEM) and the Finite Element Method (FEM). The proposed coupling method has been shown to be a sufficient technique when resolving the different length scales involved in engineering problems dealing with granular assemblies in contact with deformable bodies [1][2]. Herein, the extended discrete element method (XDEM) is used to describe the dynamics of the granular assembly. Thereby the discrete approach accounts for the motion and forces of each grain individually. On the other hand, the finite element method accurately predicts the deformations and stresses acting within the tire tread. Hence, the simulation domain occupied by the tire is efficiently described as a continuous entity. The coupling of both method is based on the interface shared by the two spatially separated domains. The interface coupling enables to apply a contact model fitting the particular contact behaviour between the grains and the tread surface. Thus, contact forces develop at the interface and propagate into each domain. The coupling method enables to capture both responses simultaneously. Each grain in contact with the tread surface generates a contact force which it reacts on repulsively. The contact forces sum up over the surface and cause the tire tread to deform. The resultant stresses are then again recognised by the granular assembly. The coupling method compensates quite naturally the shortages of both numerical methods. It further employs a fast contact detection algorithm to spare valuable computation time [1]. The proposed DEM-FEM Coupling technique was employed to study the tractive performance of four different tire treads on a soil layer of the material sand. The simulations were conducted in accordance to the experimental measurements undertaken by Shinone et al. [3]. The contact forces at the surface of smooth, lug, rib and block tread patterns are captured by 3D simulations of different slip values of each tire tread. The simulation results are used to analyse the gross tractive effort, running resistance and drawbar pull of the different tread patterns in sand. [less ▲]

Detailed reference viewed: 181 (8 UL)
Full Text
See detailROS-induced regulation of mitophagy and its failure in Parkinson’s disease
Kolodkin, Alexey UL; Ignatenko, Andrew UL; Simeonidis, Vangelis UL et al

Poster (2013, May)

Reactive Oxygen Species (ROS) generation is an unavoidable background process in the normal functioning of the cell. The greatest contributor to ROS production is the electron transport chain (ETC) where ... [more ▼]

Reactive Oxygen Species (ROS) generation is an unavoidable background process in the normal functioning of the cell. The greatest contributor to ROS production is the electron transport chain (ETC) where O2 is reduced to H2O. Some incompletely-reduced oxygen species escape and oxidize a variety of organic molecules (e.g. proteins and lipids in the mitochondrial membrane), leading to molecular dysfunction and initiating a positive feedback loop leading to generation of even more active radicals. Increased ROS concentration damages mitochondria and further increases ROS generation. Healthy cells manage ROS enzymatically with superoxide dismutase and other enzymes, various antioxidants, and ultimately through increased mitophagy of damaged mitochondria. The precise tuning of the latter mechanism is crucial for cell survival and is controlled in the cell by a ROS-induced regulatory network, which consists of many components such as Nrf2, Keap1, Parkin and p62 with a rather complicated cross-talk (Figure 1). In many diseases (cancer, Parkinson’s disease (PD), Huntington’s disease (HD), etc.), various components of the ROS management network are altered. Deconstructing the molecular mechanisms underlying or resulting from these alterations might contribute to better understanding of the dynamics of related pathophysiological processes. We have built a kinetics-based model which recapitulates the consensus understanding of the mechanism responsible for cellular ROS – managing system. [less ▲]

Detailed reference viewed: 125 (10 UL)
Full Text
Peer Reviewed
See detailThe extended discrete element method (XDEM) for multi-physics applications
Peters, Bernhard UL

in Scholarly Journal of Engineering Research (2013), 2

The Extended Discrete Element Method (XDEM) is a novel numerical simulation technique that extends the dynamics of granular materials or particles as described through the classical Discrete Element ... [more ▼]

The Extended Discrete Element Method (XDEM) is a novel numerical simulation technique that extends the dynamics of granular materials or particles as described through the classical Discrete Element Method (DEM) by additional properties such as the thermodynamic state, stress/strain, or electromagnetic field for each particle coupled to a continuum phase such as fluid flow or solid structures. Contrary to a continuum mechanics concept, XDEM aims at resolving the particulate phase through the various processes attached to particles, while DEM predicts the special-temporal position and orientation for each particle; XDEM additionally estimates properties such as the internal temperature and/or species distribution. These predictive capabilities are further extended by an interaction to fluid flow by heat, mass and momentum transfer and impact of particles on structures. These superior features as compared to traditional and pure continuum mechanic approaches are highlighted by predicted examples of relevant engineering applications. [less ▲]

Detailed reference viewed: 210 (35 UL)
Full Text
Peer Reviewed
See detailDiscrete Element Modeling of Inter-Granular Bonds between Snow Grains
Michael, Mark UL; Nicot, Francios; Peters, Bernhard UL

in PARTEC - International Congress on Particle Technology (2013, April)

The mechanical behaviour of snow was long studied to help predict natural hazards, like avalanches. For those predictions the behaviour of snow deforming at low strain rates is of importance. On the other ... [more ▼]

The mechanical behaviour of snow was long studied to help predict natural hazards, like avalanches. For those predictions the behaviour of snow deforming at low strain rates is of importance. On the other hand, a large group of industrial applications concerning trafficability and transportation safety also benefit from the understanding of snow physics. These applications requiring an understanding of the high strain rate behaviour of snow. The material behaviour of snow is based on its micro-structure. The micro-structure consists of ice grains connected by ice bonds building up an open-foam like structure. The macroscopic response of a snow pack to loading is determined by the deformation and failure of its bonds and the inter-granular friction whiles rearrangement of the grains. The work reported here proposes an inter-granular snow model developed and deployed using a discrete element technique. The goal is to understand the material behaviour of dry snow at high strain rates, from 0.01s^-1 up to 100s^-1. The developed algorithm predicts the displacement of the individual grains due to inter-granular contact and bond forces. The micro-structure of a snow pack is represented by generating an ensemble of explicit geometrical shapes describing the individual ice grains and bonds. The distributions of grain size and position are generated by gravitational deposition and by applying a fractal algorithm. Snow structures of densities from 200 kg/m^3 up to 600 kg/m^3 are generated. The developed inter-granular bond models assume a cylindrical neck between adjoining ice grains. Material properties and constitutive models of the hexagonal single- and poly-crystal Ih ice are used to describe the material behaviour of each individual bond. Simulations of tensile and compression tests have been conducted using samples of 10^3 up to 10^5 grains. Here, results of different parametric studies are reported. Assessed are the dependences of the macroscopic snow behaviour on microstructural properties and mechanical properties on grain-scale. These results are compared to experimental measurements and corresponding finite element simulations. The calculation results enable to identify primary deformation mechanism at the given strain rates. [less ▲]

Detailed reference viewed: 181 (13 UL)
Full Text
Peer Reviewed
See detailExtended Discrete Element Method (XDEM) to Model Heterogeneous Reactions in Packed Beds
Hoffmann, Florian UL; Peters, Bernhard UL

in PARTEC - International Congress on Particle Technology (2013, April)

Packed beds, due to their high surface-area-to-volume-ratio, are widely used for chemical reactors, such as catalytic or pebble bed reactors, blast furnaces or as heat exchanging units. Depending on the ... [more ▼]

Packed beds, due to their high surface-area-to-volume-ratio, are widely used for chemical reactors, such as catalytic or pebble bed reactors, blast furnaces or as heat exchanging units. Depending on the mode of packing, structured or random, a different degree of heterogeneity is introduced. For stable and efficient process handling local quantities such as temperature or concentration of chemical species are of major interest. Direct measurement of such quantities has proven very difficult or unfeasable due to the morphology of the bed. Hence, numerical modeling can help to gain insights into inaccessible parts of such reactors. The objective of this contribution is to introduce a discrete numerical approach that describes heterogeneous reaction processes within packed and moving beds. The so-called Extended Discrete Element Method (XDEM) is used to account for convective heat and mass transfer within porous media. Both motion and chemical conversion of particulate material can be dealt with. A granular medium consists of an ensemble of particles of which each exhibits individual chemical and mechanical properties. Dynamics of solid particles is accounted for by the known discrete element approach. In addition physicochemical conversion of an individual particle like drying, gasification or redox reactions are accounted for by transient differential equations (species, energy, momentum) on a particle scale. Predictions include properties such as temperature and species distribution inside a particle. The general and modular formulation of the model allows for application to any chemical process involving heterogeneous reactions. Chemical interaction between multiple particles takes place through gaseous intermediates by heat and mass transfer. Computational Fluid Dynamics is applied for the gaseous continuum in the voidage between particles. The presented model can act as tool to gain valuable insights into chemical processes inside packed beds such as blast furnace iron making or gasification of biomass. It can serve as a toolbox for prediction, analysis and optimization of a variety of process parameters such as residence time, conversion progress, burden charging and gas flow patterns. As an example a section of the burden in a blast furnace is focused on. [less ▲]

Detailed reference viewed: 139 (7 UL)