(582ay) An Integrated Workflow for Numerical Generation and Meshing of Packed Beds of Non-Spherical Particles: Applications in Chemical Reaction Engineering

An
integrated workflow for numerical generation and meshing of packed beds of
non-spherical particles: Applications in chemical reaction engineering

Behnam Partopour, Anthony G. Dixon

Department of Chemical Engineering,
Worcester Polytechnic Institute,

Worcester, MA, USA, 01609

            Packed
beds are widely used in different areas of the chemical industry such as
reaction engineering.In particular, packed bed models
are needed where different particle shapes are used to fill low
tube-to-particle diameter ratio (N) beds. Therefore, along with experimental
methods, the numerical generation of these beds is extensively investigated. Unlike
packed beds of spherical particles, the contacts between non-spherical
particles could include lines and surfaces. Therefore, collision detection and
subsequent meshing in those areas can computationally be challenging.

In this work we introduce the
automated packed bed generator (PBG) package for spherical and non-spherical
particles based on the Bullet physics library. The library includes a robust
collision detection module which uses the impulse based collision detection
method¹. The package gets the user input for parameters such as
shape, dimensions and number of particles, as well as friction and restitution
factors, etc., and returns an STL file of the constructed geometry along with
the bed properties (e.g. void fraction and angle distributions, see first
figure).

The constructed packed bed STL file
then is imported to meshing software and a 3-dimensional mesh is generated
based on the shrink-wrap method. The bed properties for packed beds of
different shapes of particles are validated against existing experimental and
computational data in the literature. The meshed geometries are imported to CFD
software, and momentum and heat transfer simulations are carried out. Velocity
and temperature profiles are validated against the experimental data, and
previous CFD simulations, respectively. Finally, for the first time the
generated and meshed geometries are successfully used for resolved particle
fixed bed CFD simulations. An ethylene epoxidation reaction mechanism² is
coupled to three-dimensional CFD simulations of randomly packed bed of spheres,
Raschig rings, and quadrilobes. Ethylene mass fraction gradients on the surface
of the quadrilobe particles as well as velocity
contours are shown in the second figure.

References

1- Pytlos M, Gilbert M, Smith CC. Modelling granular soil
behaviour using a physics engine. Géotechnique
Letters 2015; 5:243–249

2- Linic S, Barteau MA. Construction of a reaction coordinate and a
microkinetic model for ethylene epoxidation on silver from DT calculations and
surface science experiments. J. Catal. 2003;
214:200-2012