Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/3992
2015-07-29T02:44:08ZOptimization of the tantalum ore production by control the milling process
http://hdl.handle.net/2117/28045
Optimization of the tantalum ore production by control the milling process
Alfonso Abella, María Pura; Oliva Moncunill, Josep; Álvarez Rodríguez, Beatriz; Jorge Sánchez, Juan; Sanmiquel Pera, Lluís; Parcerisa Duocastella, David; Tomasa Guix, Oriol; Calvo Torralba, Daniel; Guasch Cascallo, Eduard; Felipe Blanch, José Juan de; Anticoi Sudzuki, Hernán; García Vallès, Maite
Tantalum is a strategic metal with multiple applications in the new technologies. Tantalum deposits are scarce in EU. Thus, more efficient extracting processes are necessary to contribute to major European independency on these critical raw materials. Tantalum occurs mainly in pegmatites and leucogranite deposits and its placers. Europe does not produce tantalum; however, several deposits are susceptible of being exploited if technologies of processing are improved. This work is part of the Optimore Project which aims to develop modelling and control technologies, using advanced sensing and advanced industrial control by using artificial intelligence techniques, for the more efficient and flexible tantalum and tungsten processing from crushing to separation process. In this paper, a preliminary study of characterization of tantalum ores from leucogranite and alluvial deposits is presented to be used as a base for design the milling experiments to optimize the tantalum recovering during the processing. In the ore deposits tantalum appears in solid solution with niobium in complex oxides, which forms low grade aggregates which need to be processed by means of a separation process. Tantalum ores characterised here belong to alluvial placers of pegmatitic origin located in the Bolivian Amazon Craton and to leocogranites of Penuota, in Spain. Ta bearing minerals of the Bolivian placers are mainly from the columbite group minerals. In Penouta microlite is abundant and often it has a zoning characterised by a Nb-rich core followed by a Ta-rich rim of several cm in thickness.
2015-01-01T00:00:00ZImprovements on the numerical analysis of viscoplastic-type non-Newtonian fluid flows
http://hdl.handle.net/2117/27318
Improvements on the numerical analysis of viscoplastic-type non-Newtonian fluid flows
Carmona Muñoz, Ángel; Lehmkuhl Barba, Oriol; Pérez Segarra, Carlos David; Oliva Llena, Asensio
The aim of this work is to delve into the numerical analysis of viscoplastic-type non-Newtonian fluid flows with the objective of carrying out more advanced numerical simulations for them. Specifically, improvements in the spatial discretization schemes and the temporal integration methods are proposed to overcome the numerical problems introduced by the transpose diffusive term and associated with the velocity field discontinuity, the artificial viscous diffusion and the transpose viscous coupling.
2014-01-01T00:00:00ZSpectrally-consistent regularization of turbulent Rayleigh-Bénard convection
http://hdl.handle.net/2117/26901
Spectrally-consistent regularization of turbulent Rayleigh-Bénard convection
Dabbagh, Firas; Trias Miquel, Francesc Xavier; Gorobets, Andrei; Oliva Llena, Asensio
Direct numerical simulation (DNS) of turbulent Rayleigh-Bénard convection in an air filled (Pr = 0,7) rectangular cell of squared cross-section with periodic boundary conditions in the span-wise direction, has been carried out at Ra = 10^8. A fourth-order energy-conserving discretizations have been used that ensure non-physical dissipative effects introduced usually in other numerical schemes. The two sensitive fine-scales kinetic and thermal dissipation rates have been studied statistically to reveal high correlation within the thermal boundary layers and equilibrium zones of the two dissipations at strong thermal and kinetic interactions. It has been found that the foregoing zones could mark the plumes since these last reflect significant correlation regions of the kinetic and thermal fields. Afterwards, a novel class of symmetry-preserving regularization models that restrain the convective production of small scales of motion in unconditionally stable manner, have been applied on the studied problem. The obtained results are compared directly with the DNS ones to show a reasonable correspondence with and without model at this kind of moderate turbulence.
2014-01-01T00:00:00ZUnstructured 3D numerical modeling of the melting of a PCM contained in a spherical capsule
http://hdl.handle.net/2117/26897
Unstructured 3D numerical modeling of the melting of a PCM contained in a spherical capsule
Galione Klot, Pedro Andrés; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Pérez Segarra, Carlos David; Oliva Llena, Asensio
2014-01-01T00:00:00ZDirect numerical simulation of the flow over a spherical bubble in a turbulent pipe flow
http://hdl.handle.net/2117/26896
Direct numerical simulation of the flow over a spherical bubble in a turbulent pipe flow
Jofre Cruanyes, Lluís; Balcázar Arciniega, Néstor; Lehmkuhl Barba, Oriol; Borrell Pol, Ricard; Castro González, Jesús
This work aims at investigating, by means of a direct numerical simulation, the flow over a clean spherical bubble fixed on the axis of a turbulent pipe flow. The simulation is performed by means of a parallel unstructured symmetry-preserving formulation on a mesh of 5.4M cells. The main features of the turbulent flow are described by analyzing the time-averaged data collected over a significant period of time. The numerical results conclude that the bubble generates a wake, similarly to the case of a solid sphere, however, it differs in the fact that the fluid slips through the surface of the bubble instead of stopping, thus, no boundary layer is created. Moreover, due to viscosity, a transfer of momentum from the fluid surrounding the bubble to the fluid inside of it is produced. This transfer of momentum generates a turbulent toroidal vortex inside the bubble. In consequence, two short recirculation zones are found at the extremes of the bubble’s diameter, while in between, the axial velocity inverts its sign.
2014-01-01T00:00:00ZNumerical modeling of simultaneous heat and moisture transfer under complex geometry for refrigeration purposes
http://hdl.handle.net/2117/26805
Numerical modeling of simultaneous heat and moisture transfer under complex geometry for refrigeration purposes
Hou, Xiaofei; Rigola Serrano, Joaquim; Lehmkuhl Barba, Oriol; Oliet Casasayas, Carles; Pérez Segarra, Carlos David
The aim of the paper is to gain a better insight into heat and moisture transfer in refrigerator and to do fundamental study for water evaporation and condensation in refrigeration application. The governing transport equations (continuity, momentum, energy and concentration equations) in 3D Cartesian coordinates are firstly introduced. As the mixed convection is simulated in the paper, buoyancy forces caused by both temperature and concentration gradient are considered and are also included in momentum equation. Numerical results are carried out by using Termofluids code. The pressure-velocity linkage is solved by means of an explicit finite volume fractional step procedure. In order to validate the code, a humid air flowing in a horizontal 3D rectangular duct case is carried out and compared with the published numerical and experimental results. The contour of temperature and vapor density of air at a cross section is provided and analyzed. Finally, the heat and mass transfer process during the moist air flow through complicated geometry is simulated and temperature and humidity distributions are obtained.
2012-01-01T00:00:00ZOn the IBM approximation for the wheel aerodynamic simulation
http://hdl.handle.net/2117/26777
On the IBM approximation for the wheel aerodynamic simulation
Aljure Osorio, David E.; Lehmkuhl Barba, Oriol; Martínez Valdivieso, Daniel; Favre Samarra, Federico; Oliva Llena, Asensio
Challenging large eddy simulations (CLES) are performed to the flow around simplified wheels in wheelhouses. Wheel geometry is modelled using immersed boundary methods.
Results are compared to previous numerical simulations. Instantaneous flows results and turbulent structures are analysed to asses the viability of this boundary treatment on the resolution of a rotating wheel.
2014-01-01T00:00:00ZA new epoxy based layered silicate nanocomposite using a hyperbranched polymer: study of the curing reaction and nanostructure development
http://hdl.handle.net/2117/26762
A new epoxy based layered silicate nanocomposite using a hyperbranched polymer: study of the curing reaction and nanostructure development
Cortés Izquierdo, M. Pilar; Fraga Rivas, Iria; Calventus Solé, Yolanda; Hutchinson, John M.
Polymer layered silicate (PLS) nanocomposites based on epoxy resins have been widely studied previously [1], but the anticipated dramatic enhancement of their properties has not yet been realised. One approach to overcoming this problem that has recently been investigated is to incorporate hyperbranched polymers into these systems [2]. The supposed advantages of this approach are both to improve the dispersion of the clay in the epoxy resin matrix and also to increase the degree of exfoliation that takes place when the system is cured. In the present work, we further investigate this idea by fabricating PLS nanocomposites based upon a bifunctional epoxy resin and an –NH terminated poly(ethyleneimine) hyperbranched polymer, which acts as the curing agent. The effect of the clay content is studied and the results are compared also with previous work in which the curing agent was a diamine [3]
2013-01-01T00:00:00ZImplementación de biodigestores familiares en el Perú. Experiencias de Yanaoca (Cusco) y Ventanilla (Lima)
http://hdl.handle.net/2117/26618
Implementación de biodigestores familiares en el Perú. Experiencias de Yanaoca (Cusco) y Ventanilla (Lima)
Ferrer Martí, Ivet; Poggio, D; MAS, A; Batet Miracle, Lluís; Velo García, Enrique
2008-01-01T00:00:00ZSpatial optimality in power distribution networks
http://hdl.handle.net/2117/26577
Spatial optimality in power distribution networks
Luo, Lingen; Pagani, Giuliano A.; Rosas Casals, Martí
Critical infrastructures can be characterized as networks where nodes and edges are embedded in space. Transportation networks, the internet, and power grids, are examples of networks where spatial constrains are relevant. An important consequence of space is that there is a cost associated with the length of edges which in turn has important effects on the topological structure of and on the dynamical processes which take place on these spatial networks. In this paper we investigate the effect of the wiring cost in the spatial organization of a sample of power distribution networks by means of shuffling the networks in systematic ways. We show that although they share similar topologies, suboptimal networks (i.e., those with topologies not organized to reduce the wiring cost) seem to accumulate more failures. Consequences of these results and further work are finally discussed and outlined.
2014-01-01T00:00:00Z