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Spherical Glass Beads (spherical + glass_bead)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Experimental investigation of slip-stick behaviour in granular materials

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2006
Khalid A. Alshibli
Abstract This paper presents the results of an experimental programme to study load oscillation in granular materials. Spherical glass beads were used in the investigation. Cylindrical specimens were compressed under axisymmetric triaxial loading condition at 25,100,250 and 400 kPa confining pressures. The test parameters included: (i) particle size; (ii) gradation (uniform versus non-uniform specimens); (iii) confining pressure; (iv) loading rate; and (v) specimen density. In general, a slight post-peak principal stress softening was observed as well as a continuous volume increase (dilation) even at relatively high strains. This appears to be caused by the uniform shape and smooth surface of the spherical particles. Load oscillations were observed in the very small, small, and well-graded beads at each confining pressure. For the medium beads, the oscillations appeared at high confining pressure (250 and 400 kPa), and they did not appear in the large beads. The influences of the confining pressure, loading rate, particle size, gradation and specimen density on load oscillation are presented and discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Simulation and experiments of mixing and segregation in a tote blender

AICHE JOURNAL, Issue 3 2005
O. S. Sudah
Abstract Experimental and computational investigation of mixing and segregation of granular material in a tote blender was carried out. The discrete element method (DEM) was used to simulate flow of spherical, free-flowing particles where the results of the computations were compared to blending. Computational results are compared to blending experiments of monodisperse and bidisperse systems using spherical glass beads in a 1:1 scale. Although some discrepancies were observed, DEM simulations illustrated good agreement with experimentally measured mixing and segregation rates for different fill levels and loading conditions. The effects of blender geometry on particle velocities and flow patterns were examined using DEM. The presence of a hopper and bin section, as well as the axial offset proved to introduce greater axial mixing rates that would be expected from pure dispersion. Vibrated experiments showed better agreement than not-vibrated experiments, indicating that modeling of friction forces needs to be further improved to enhance the accuracy of DEM methods. © 2005 American Institute of Chemical Engineers AIChE J, 51: 836,844, 2005 [source]

Gas Classification of Particles Using a Packed Bed

PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 4 2008
Wei Yang
Abstract Gas classification of particles using a packed bed is, for the first time, proposed and tested for two materials, i.e., glass ballotini and microcrystalline cellulose (MCC). A 2,m long column with 9.5,mm diameter is packed with 2,mm spherical particles. The particles to be classified are injected into the inlet of the packed bed by a carrier gas. Measurements of the breakthrough curves of the particles are carried out at the outlet of the packed bed. The results show that the particle elution order is particle size dependent with large particles elutriated faster than small ones. Taking the particle size into account, the retention time of irregular MCC particles is much longer than that of spherical glass beads and the difference is attributed to the particle shape and cohesiveness. Based on the findings, binary mixtures of both, glass and MCC beads are injected into the packed bed for the classification experiments. The results show different dependence on the superficial gas velocity of the particle classification efficiency. The particle classification efficiency of glass particles increases with decreasing superficial gas velocity, whereas that of MCC particles increases with increasing superficial gas velocity. [source]

Transient Barrier Discharge Characteristics of Parallel-Plate-Type, Packed-Bed, Non-Thermal Plasma Reactor Under High-Humidity Conditions

PLASMA PROCESSES AND POLYMERS, Issue 9 2006
Jen-Shih Chang
Abstract Summary: Barrier discharge has been used for ozone generation for water treatments and pollutant gas removal. An experiment has been conducted to observe transient barrier discharge characteristics of parallel-plate-type, 3 mm diameter, spherical glass beads packed-bed, non-thermal plasma reactors under high-humidity conditions. The results show that: 1) steady operation of the reactor requires 5 to 10 min of operation under an initial 20 to 80% relative humidity at 20,°C in air, as a result of the desorption of water from the packed materials, 2) the usual method to determine discharge power using a Q - V Lissajous figure may be distorted by adsorption/desorption of water vapor from the surface, and 3) since the surface of the packed material is heated to 50 to 160,°C, the mechanism of desorption may be a result of pure thermal effects. Change in reactor surface temperature with time. [source]