VALVERDE MILLÁN , José Manuel

Experimental measurements are reported on the tensile yield stress of magnetofluidized beds of fine magnetic powders operated in the cross-flow configuration. In the absence of externally applied magnetic field the yield stress of the powder depends on particle size as expected, i.e., it increases as bead size is decreased. This trend is...

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The Geldart's diagram, which was originally based on empirical observations on beds fluidized by air at ambient conditions, has been routinely used to predict the type of gas-fluidization expected for a granular material. However, the Geldart's diagram, based on particle size and density, is not currently a useful tool to predict the...

Some years ago it was shown that gas-fluidized powders may transit from solidlike to fluidlike fluidization prior to bubbling, shedding light on a long-standing controversy on the nature of "homogeneous" fluidization. In this paper it is shown that some gas-fluidized powders may also transit from the fluidlike regime to elutriation, with full...

Fine particles agglomerate in the fluidized state due to the strength of interparticle attractive forces as compared to particle weight. Interparticle adhesion can be largely increased by consolidation stresses applied during powder handling. As a consequence, fragments of the consolidated powder may persist when the powder is fluidized, which...

La presente invención tiene por objeto un procedimiento de adsorción de CO2 que consiste en hacer pasar un flujo de gas con una concentración determinada de CO2 a través de un lecho de polvo dispuesto sobre una placa porosa en una cámara de fluidización,

We explore the role of gas viscosity in the behavior of gas-fluidized beds of fine powders by means of experimental measurements using nitrogen and neon as fluidizing gases, and theoretical considerations. The existence of a nonbubbling fluidlike regime has been recently observed in beds of fine powders fluidized with nitrogen. Our experiments...

This work reports a novel in situ XRD analysis on the multicycle calcination/carbonation of natural limestone and dolomite at relevant conditions for thermochemical energy storage (TCES) in concentrated solar power (CSP) plants. The experiments allow analysing noninvasively the time evolution of the different phases involved in the Calcium...

This work reports an in situ XRD analysis of whether the calcination/carbonation behavior of natural limestone (CaCO3) is affected by the addition of H2O to the calciner at a very low concentration under relevant Calcium-Looping (CaL) conditions for CO2 capture in coal fired power plants (CFPP) and Thermochemical Energy Storage (TCES) in...

The calcium looping (CaL) process, based on the calcination/carbonation of CaCO3 at high temperatures, has emerged in the last years as a potentially low cost technology for CO2 capture. In this work, we show that the application of high intensity sound waves to granular beds of limestone and dolomite in a CaL reactor enhances significantly...

Pyroclastic flows are characterized by their high mobility, which is often attributed to gas fluidization of the usually fine and/or low-density particles. However, the physical mechanism that might drive sustained fluidization of pyroclastic flows over extraordinarily long runout distances is elusive. In this letter it is proposed that a...

In this work, we present experimental measurements of the yield stress of gas-fluidized beds of magnetizable particles stabilized by an externally imposed magnetic field. Powder samples consist of spherical magnetite particles 35-65 μm in size. The magnetic field is applied in the bubbling regime and the gas velocity is decreased. At a critical...

Fluidized beds of granular materials can be stabilized by interparticle attractive forces which confer the expanded bed an elastic modulus that stabilizes it against flow perturbations. Stabilization in a structure of enduring contacts is seen to occur naturally due to the universal van der Waals forces for ∼50 μm particle size beds albeit in a...

La presente invención presenta un sistema integrado de producción de Na2HCO3 a partir del CO2 capturada de industrias o plantas de potencia mediante un proceso de carbonato seco partiendo de trona como materia prima (Na2CO3 · NaHCO3 · 2H2O) y convirtiéndo

Nanoparticles (NPs) are applied in a wide range of processes, and their use continues to increase. Fluidization is one of the best techniques available to disperse and process NPs. NPs cannot be fluidized individually; they fluidize as very porous agglomerates. The objective of this article is to review the developments in nanopowder...

Dispositivo y procedimiento para medir la cohesión de medios granulares finos. El objeto de la presente invención es un dispositivo automatizado para la medida de la cohesión de medios granulares finos (polvos). El aparato se basa en un procedimiento que

Dynamical weakening of dense granular flows plays a critical role on diverse geological events such as seismic faulting and landslides. A common feature of these processes is the development of fluid-solid relative flows that could lead to fluidization by hydrodynamic viscous stresses. Volcanic ash landslides (pyroclastic flows) are...

Understanding the flowability of cohesive powders at high temperature is of great importance for many industrial applications where these materials are handled at harsh thermal conditions. For instance, the Calcium-Looping (CaL) process, involving the transport, storage and fluidization of limestone powders at high temperature, is being...

Slender axisymmetric dielectric liquid bridges are made stable by the action of an axial electric field. In this paper, the subsequent dynamics of a slender liquid bridge after turning off the electric field is considered. The evolution in time of the bridge profile is investigated both theoretically and experimentally. A one-dimensional model...

We report a novel experimental study on the jamming transition of dry fine powders with controlled attractive energy and particle size. Like in attractive colloids dry fine particles experience diffusionlimited clustering in the fluidlike regime. At the jamming threshold fractal clusters crowd in a metastable state at volume fractions depending...

In this work we measure the mechanical strength of a bed of glass beads that has been previously subjected to a controlled flow of humid air by using a fluidized bed setup. The material is first initialized in a reproducible state by subjecting it to a high flow of dry air that drives the bed to bubbling. Then the gas flow is abruptly turned...