![]() Estupinan Donoso, Alvaro Antonio ![]() ![]() in Advances in Powder Metallurgy & Particulate Materials (2015), (Proceedings of the 2015 International Conference on Powder Metallurgy Particulate Materials), 0235--0248 During technical reduction of tungsten trioxide powder in hydrogen atmospheres, the local temperature and the ratio of water vapor to hydrogen partial pressures govern the conversion rate. Water vapor ... [more ▼] During technical reduction of tungsten trioxide powder in hydrogen atmospheres, the local temperature and the ratio of water vapor to hydrogen partial pressures govern the conversion rate. Water vapor removal rate not only affects the conversion progress, but also drives the final metallic tungsten powder size distribution. The amount of water vapor inside the bed depends on the hydrogen flow, the height of powder beds and the size characteristics of the initial oxide. The chemically aggressive environment and high temperatures make it difficult to do the measurements inside the reactors for studying or control the process. On the other hand, multi-physics computational techniques help to understand the evolution of the complex phenomena involved in the process. This contribution presents the eXtended Discrete Element Method as a novel approach to investigate the complex thermochemical conversion of tungsten oxides into tungsten metal. The recently emerged technique is based on a coupled discrete and continuous numerical simulation framework. In the study, an advanced and consolidated two-phase Computational Fluid Dynamics (CFD) tool for porous media represents gaseous phase penetration and transport. The discrete feedstock description includes one-dimensional and transient distributions of temperature and species for each powder particle. This allows gaining a new and valuable insight into the process, which may lead into finer tungsten powder production, and consequently more resistant tungsten carbide products. Transient and spatial results for powder composition, gas species as well as a mass loss comparison with experimental data for non-isothermal hydrogen reduction of tungsten trioxide are demonstrated and discussed. [less ▲] Detailed reference viewed: 56 (5 UL)![]() Peters, Bernhard ![]() ![]() in 18th IFRF Member's Conference (2015) Detailed reference viewed: 76 (4 UL)![]() Peters, Bernhard ![]() in Chemical Engineering Science (2015) Detailed reference viewed: 108 (1 UL)![]() Peters, Bernhard ![]() in ECEMP 2015, European Centre for Emerging Materials and Processes (2015) Detailed reference viewed: 40 (0 UL)![]() Kolodkin, Alexey ![]() ![]() Poster (2014, December) Detailed reference viewed: 173 (14 UL)![]() Kolodkin, Alexey ![]() ![]() Poster (2014, October) Detailed reference viewed: 174 (17 UL)![]() Kolodkin, Alexey ![]() ![]() ![]() Poster (2014, September) Detailed reference viewed: 174 (7 UL)![]() Hadji-Minaglou, Jean-Régis ![]() ![]() ![]() Patent (2014) The world-wide energy consumption has almost doubled since 1980 despite efforts towards energy saving and efficiency. This trend is supposed to continue for the decades to come so that major energy crises ... [more ▼] The world-wide energy consumption has almost doubled since 1980 despite efforts towards energy saving and efficiency. This trend is supposed to continue for the decades to come so that major energy crises with electricity cuts and shortage of petrol or gas are anticipated. Furthermore, an ever increasing consumption of fossil fuels significantly contributes to further emissions of greenhouse gases and consequently to global warming in conjunction with catastrophic climate changes. These impacts are reduced to a large extent through utilisation of renewable energy sources for and within decentralised user facilities. The present invention relates to a method of communicating operation modes between a user facility control unit at a user facility and a utility grid control unit of a utility grid. In particular, it relates to a decentralised method of communicating operation modes between a user facility control unit at a user facility with renewable energy supply and a utility grid control unit of a utility grid. [less ▲] Detailed reference viewed: 99 (2 UL)![]() Kolodkin, Alexey ![]() ![]() Poster (2014, June) Detailed reference viewed: 178 (11 UL)![]() Kolodkin, Alexey ![]() ![]() Poster (2014, June) Detailed reference viewed: 158 (16 UL)![]() Ignatenko, Andrew ![]() ![]() ![]() 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: 204 (35 UL)![]() Estupinan Donoso, Alvaro Antonio ![]() ![]() 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: 234 (28 UL)![]() Mahmoudi, Amir Houshang ![]() ![]() ![]() in Journal of Analytical and Applied Pyrolysis (2014), 106 Detailed reference viewed: 419 (25 UL)![]() Mahmoudi, Amir Houshang ![]() ![]() ![]() 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: 399 (31 UL)![]() Michael, Mark ![]() ![]() 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: 562 (29 UL)![]() Peters, Bernhard ![]() in MECHANIKA (2014), 20 Detailed reference viewed: 175 (10 UL)![]() Peters, Bernhard ![]() ![]() ![]() in Industrial Combustion (2014), 14 A vast number of engineering applications involve physics not solely of a single domain but of several physical phenomena, and therefore are referred to as multi-physical. As long as the phenomena ... [more ▼] A vast number of engineering applications involve physics not solely of a single domain but of several physical phenomena, and therefore are referred to as multi-physical. As long as the phenomena considered are to be treated by either a continuous (i.e. Eulerian) or discrete (i.e. Lagrangian) approach, numerical solution methods may be employed to solve the problem. However, numerous challenges in engineering exist and evolve; those include modelling a continuous and discrete phase simultaneously, which cannot be solved accurately by continuous or discrete approaches only. Problems that involve both a continuous and a discrete phase are important in applications as diverse as the pharmaceutical industry, the food processing industry, mining, construction, agricultural machinery, metals manufacturing, energy production and systems biology. A novel technique referred to as Extended Discrete Element Method (XDEM) has been developed that offers a significant advancement for coupled discrete and continuous numerical simulation concepts. XDEM extends the dynamics of granular materials or particles as described through the classical discrete element method (DEM) to include additional properties such as the thermodynamic state or stress/strain for each particle coupled to a continuous phase such as a fluid flow or a solid structure. Contrary to a continuum mechanics concept, XDEM aims at resolving the particulate phase through the various processes attached to particles. While DEM predicts the spatial-temporal position and orientation for each particle, XDEM additionally estimates properties such as the internal temperature and/or species distribution during drying, pyrolysis or combustion of solid fuel material such as biomass in a packed bed. These predictive capabilities are further extended by an interaction with fluid flow by heat, mass and momentum transfer and the impact of particles on structures. © International Flame Research Foundation, 2014. [less ▲] Detailed reference viewed: 111 (6 UL)![]() Estupinan Donoso, Alvaro Antonio ![]() ![]() in International Journal of Refractory Metals and 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: 191 (10 UL)![]() Peters, Bernhard ![]() in Condensed Matter 2014 (2014) Detailed reference viewed: 51 (0 UL)![]() Peters, Bernhard ![]() ![]() in 24th European Symposium on Computer Aided Process Engineering, ESCAPE 24 (2014) Detailed reference viewed: 118 (1 UL) |
||