Modelling die filling with charged particles using DEM/CFD--颗粒学报PARTICUOLOGY

Nwose, E. N., Pei, C., & Wu, C.-Y. (2012). Modelling die filling with charged particles using DEM/CFD. Particuology, 10(2), 229–235. https://doi.org/10.1016/j.partic.2011.11.010

Modelling die filling with charged particles using DEM/CFD

Emmanuel Nkem Nwose, Chunlei Pei, Chuan-Yu Wu^*

School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK

10.1016/j.partic.2011.11.010

Volume 10, Issue 2, April 2012, Pages 229-235

Received 4 October 2011, Revised 22 November 2011, Accepted 26 November 2011, Available online 12 March 2012.

E-mail: c.y.wu@bham.ac.uk

Highlights

► Simulations of die filling with oppositely charged particles reveal that both fill ratio and critical filling speed generally decrease as electrostatic charge increases.

► When electrostatic charge is low, strong air/particle interaction results in lower fill ratio and lower critical filling speed as compared to those in a vacuum.

► When electrostatic charge is high, electrostatic interaction becomes dominant so that similar fill ratios and critical filling speeds are obtained both in air and in a vacuum.

Abstract

The effects of electrostatic charge on powder flow behaviour during die filling in a vacuum and in air were analysed using a coupled discrete element method and computational fluid dynamics (DEM/CFD) code, in which long range electrostatic interactions were implemented. The present 2D simulations revealed that both electrostatic charge and the presence of air can affect the powder flow behaviour during die filling. It was found that the electrostatic charge inhibited the flow of powders into the die and induced a loose packing structure. At the same filling speed, increasing the electrostatic charge led to a decrease in the fill ratio which quantifies the volumetric occupancy of powder in the die. In addition, increasing the shoe speed caused a further decrease in the fill ratio, which was characterised using the concept of critical filling speed. When the electrostatic charge was low, the air/particle interaction was strong so that a lower critical filling speed was obtained for die filling in air than in a vacuum. With high electrostatic charge, the electrostatic interactions became dominant. Consequently, similar fill ratio and critical filling speed were obtained for die filling in air and in a vacuum.

Graphical abstract

Keywords

DEM; CFD; Electrostatics; Die filling; Powder flow; Cohesion; Charged particles

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