ESPÍN MILLA , Manuel Jesús

This paper summarizes the research project performed by the authors in the Teacher Training Programme for Novices supported by the University of Seville (Spain). Based on the viewpoints of the students and teachers involved, it was discovered that an improvement in the laboratory sessions of the subject Foundations of Physics for Technical...

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...

In this work we describe the electrorheology of suspensions consisting of hematite ( α − Fe 2 O 3 ) particles dispersed in silicone oil in the presence of large dc electric fields. If an electric field pulse is applied to the systems, it is possible to estimate the time that the electrorheological (ER) fluid takes to reach its final...

The behavior of a fluidized bed of fine magnetite particles as affected by a cross-flow magnetic field is investigated. A distinct feature of this naturally cohesive powder, as compared to noncohesive magnetic grains usually employed in magnetofluidized beds, is that the fluidized bed displays a range of stable fluidization even in the absence...

The fluidization behavior of a bed of fine magnetizable particles excited by an externally applied magnetic field is found to depend on the aggregative nature of the particles before the field was applied. Usually nonaggregated particles organize in quasivertical local linear chains when the field is applied. In contrast, naturally aggregated...

Experimental observations on the fluid to solid transition in beds of magnetized fine particles fluidized by gas are reported for different particle sizes dp. Contrarily to stability analysis prediction, the fluidized bed is stabilized by a sufficiently strong magnetic field in the cross-flow configuration. As the strength H of the horizontally...

Electrostatic charging of powders is a relevant phenomenon for a number of industrial applications. The design of new processes and the use of high resistivity materials and ultrafine powders may lead to higher charging rates and to higher levels of charge accumulation that can become a serious problem. In this work we investigate...

Fluidización de polvos finos y ultrafinos asistida por campos eléctricos oscilantes.Se describe un método para mejorar la fluidización con gas de polvos finos y ultrafinos. Un procedimiento de fluidización de polvos que comprende hacer pasar un flujo de g

The electromechanical behavior of a gas-fluidized bed of insulating silica nanoparticles is investigated. When fluidized by gas, these nanoparticles form highly porous agglomerates of size of the order of hundreds of microns, which gives rise to a nonbubbling fluidization regime. Bed expansion is enhanced by an imposed alternating electric...

In this study we investigate the behaviour of a fluidized bed of fine magnetite particles as affected by a crossflow uniform magnetic field. Due to the small particle size (35 microns), the fluidized system displays a typical Geldart A fluidization behaviour in the absence of an external field, i.e. natural van der Waals forces are able to...

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...

La presente invención tiene por objeto un procedimiento destinado a mejorar la fluidizabilidad de polvos finos cohesivos (tipo Geldart C) empleados en la adsorción de CO2 y en técnicas avanzadas de combustión basadas en lechos fluidos. El procedimiento propuesto consiste en mezclar el polvo fino cohesivo adsorbente de CO2 con un polvo...

Fine powders are the cornerstone of new energy storage solutions to assist concentrated solar power plants. Though, their ability to behave like fluid can be seriously affected at high temperatures. This work investigates the use of nanosilica in fine limestone (calcium carbonate, CaCO) powders to mitigate the promotion of cohesion forces at...