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Characterization of Glass Beads: Flowability and Angle of Repose

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Characterization of particulate process and product design is a difficult field because of the unique bulk properties and behaviors of particles that differ from gasses and liquids. The purpose of

Characterization of particulate process and product design is a difficult field because of the unique bulk properties and behaviors of particles that differ from gasses and liquids. The purpose of this research is to develop an equation to relate the angle of repose and flowability, the ability of the particle to flow as it pertains to particulate processes and product design. This research is important in multiple industries such as pharmaceuticals and food processes.

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  • 2019-05

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Shear Stress Properties of Granular Materials

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This thesis investigates the effects of differing diameters, removal of antistatic forces, and varying moisture content on the shear stress properties of granular glass beads through use of a Freeman

This thesis investigates the effects of differing diameters, removal of antistatic forces, and varying moisture content on the shear stress properties of granular glass beads through use of a Freeman FT4 Powder Rheometer. A yield locus results from plotting the experimental shear stress values (kPa) vs. the applied normal stress value (kPa). From these yield loci, Mohr’s Circles are constructed to quantitatively describe flowability of tested materials in terms of a flow function parameter.

By testing 120-180 µm, 120-350 µm, 250-350 µm, and 430-600 µm dry glass bead ranges, an increase in diameter size is seen to result in both higher shear stress values and an increasing slope of plotted shear stress vs. applied normal stress. From constructed Mohr’s Circles, it is observed that flow function is quite high amongst tested dry materials, all yielding values above 20. A high flow function value (>10) is indicative of a good flow.1 Flow function was observed to increase with increasing diameter size until a slight drop was observed at the 430-600 µm range, possibly due to material quality or being near the size limitation of testing within the FT4, where materials must be less than 1000 µm in diameter.However, no trend could be observed in flowability as diameter size was increased.

Through the use of an antistatic solution, the effect of electrostatic forces generated by colliding particles was tested. No significant effect on the shear stress properties was observed.

Wet material testing occurred with the 120-180 µm glass bead range using a deionized water content of 0%, 1%, 5%, 15%, and 20% by mass. The results of such testing yielded an increase in shear stress values at applied normal stress values as moisture content is increased, as well as a decrease in the resulting flow function parameter. However, this trend changed as 20% moisture content was achieved; the wet material became a consistent paste, and a large drop in shear stress values occurred along with an increase in flowability.

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Date Created
  • 2018-12

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Statistical Analysis of 3D-DEM for Steady State Conduction Heat Transfer in a Rotary Drum

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The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of

The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of fill level, rotation rate and particle size on the steady-state conduction heat transfer in rotary drums. The high heat and mass transfer rates obtained through rotary drums make them very useful for powder mixing and heating processes in metallurgical, cement, mining, pharmaceutical, detergent and other particulate processing applications. However, these complex processes are difficult to model and operate since the particles can have a wide range of properties, and there is currently no way to predict the optimal operating conditions for a given material.

Steady-state heat transfer by conduction forms the basis for understanding other steady-state and unsteady-state heat transfer in a rotary drum – conduction, convection and radiation. Statistical analysis is carried out to determine the effects of these process parameters and find optimal operating conditions, which will thereby improve the heat transfer efficiency in rotary drums. A stainless-steel drum with a diameter of 6 inches and a length of 3 inches was modeled in EDEM with silica beads of sizes 2 mm, 3 mm and 4 mm at fill levels of 10%, 17.5% and 25%, and at rotation rates of 2 rpm, 5 rpm and 10 rpm. It was found that the heating uniformity increased with decreasing particle size, decreasing fill level and increasing rotation rate. This research is the first step towards studying the other heat transfer modes and various other process parameters. Better understanding of the various heat transfer modes, when used in combination for heating the particles, will be beneficial in improving the operating efficiency, reducing material costs and leading to significant energy conservation on a global scale.

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  • 2020