Lu, G.

Müller, C.R.

Third, J.R.

English

Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesThe 14th International Conference on Fluidization– From Fundamentals to Products Refereed Proceedings2013Numerical Studies of the Dynamics of Gas-Fluidized Beds Comprised of Non-SphericalParticles Using the DEM-CFDG. LuETH Zürich, SwitzerlandJ.R. ThirdETH Zürich, SwitzerlandC.R. MüllerETH Zürich, SwitzerlandFollow this and additional works at: http://dc.engconfintl.org/fluidization_xivPart of the Chemical Engineering CommonsThis Article is brought to you for free and open access by the Refereed Proceedings at ECI Digital Archives. It has been accepted for inclusion in The14th International Conference on Fluidization – From Fundamentals to Products by an authorized administrator of ECI Digital Archives. For moreinformation, please contact franco@bepress.com.Recommended CitationG. Lu, J.R. Third, and C.R. Müller, "Numerical Studies of the Dynamics of Gas-Fluidized Beds Comprised of Non-Spherical ParticlesUsing the DEM-CFD" in "The 14th International Conference on Fluidization – From Fundamentals to Products", J.A.M. Kuipers,Eindhoven University of Technology R.F. Mudde, Delft University of Technology J.R. van Ommen, Delft University of TechnologyN.G. Deen, Eindhoven University of Technology Eds, ECI Symposium Series, (2013). http://dc.engconfintl.org/fluidization_xiv/8 Numerical studies of the dynamics of gas-fluidized beds comprised of non-spherical particles using the DEM-CFD  G. Lua, J.R. Thirda and C.R. Müllera* aETH Zürich; Department of Mechanical and Process Engineering; Institute of Energy Technology; Laboratory of Energy Science and Engineering Leonhardstrasse 27, 8092 Zürich, Switzerland *T: +41 44 632 3440; E: muelchri@ethz.ch  Gas-solid fluidized beds with their characteristic rapid particle mixing, possess high rates of heat and mass transfer and are thus, widely used in industry. However, since experimental measurements are intrinsically difficult to acquire in such systems (1), numerical models considering solid-solid and solid-fluid interactions at different scales have been applied to study the dynamics of fluidized beds (2). In particular, the DEM-CFD model, i.e. the discrete element method (DEM) coupled with a finite volume computational fluid dynamics solver (CFD), is becoming increasingly popular. DEM-CFD simulations provide detailed information of gas-solid systems, such as the trajectories of and the contact forces between particles.  So far, most studies using the DEM-CFD have been restricted to spherical particle systems. However, most practical systems contain non-spherical particles. It is, however, doubtful whether conclusions drawn from spherical particle systems can be easily extrapolated to non-spherical particle systems (3,4). Here, we study a gas-fluidized bed comprised of non-spherical particles. The non-spherical particles were modeled using the super-quadric equation (5), viz. ( ) ( ) ( ) 1m n px a y b z c+ + = , where , ,a b c  are the half lengths of the principle axes and , ,m n p  are indices controlling the particle blockiness.   We first verified the DEM-CFD model by comparing the pre-fluidization pressure gradient obtained in 3D beds containing either spheres of diameter 8 mm or cubes of equal volume with the pressure drop calculated from the Ergun equation (Fig. 1). Subsequently, fluidized beds containing 10000 spherical or non-spherical particles (cubes and ellipsoids) of equal volume were simulated. These simulations were used to elaborate the differences in the fluidization dynamics (e.g. pressure flucturation, bed expansion, etc.) of beds containing spherical and non-spherical particles.      (a) 0 0.2 0.4 0.6 0.8 1 1.2 1.40510152025Superficial velocity, U (m/s)Pressure gradient (kPa/m)  Numerically obtained pressure gradientErgun equation (b) 0 0.2 0.4 0.6 0.8 1 1.2 1.4010203040Superficial velocity, U (m/s)Pressure gradient (kPa/m)  Numerically obtained pressure gradientErgun equation Fig. 1  Pressure gradient as a function of the superficial velocity obtained in 3D packed beds of (a) spheres and (b) cubes of equal volume. The upper and lower errorbars for each sample point correspond to the maximum and minimum pressure gradients over 0.1 s simulation. REFERENCES  1. C.R. Müller, D.J. Holland, A.J. Sederman, J.S. Dennis, and L.F. Gladden. Magnetic resonance measurements of high-velocity particle motion in a three-dimensional gas-solid spouted bed. Phys. Rev. E, 82(5):050302(R), 2010. 2. M.A. van der Hoef, M. Ye, M. van Sint Annaland, A.T. Andrews IV, S. Sundaresan, and J.A.M. Kuipers. Multiscale modeling of gas-fluidized beds. Adv. Chem. Eng., 31:65-149, 2006. 3. J.E. Hilton, L.R. Mason, and P.W. Cleary. Dynamics of gas-solid fluidized beds with non-spherical particle geometry. Chem. Eng. Sci., 65(5):1584-1596, 2010. 4. Z.Y. Zhou, D. Pinson, R.P. Zou, and A.B. Yu. Discrete particle simulation of gas fluidization of ellipsoidal particles. Chem. Eng. Sci., 66(23):6128-6145, 2011. 5. G. Lu, J.R. Third, and C.R. Müller. Critical assessment of two approaches for evaluating contacts between super-quadric shaped particles in DEM simulations. Chem. Eng. Sci., 78:226-235, 2012. 

Numerical Studies of the Dynamics of Gas-Fluidized Beds Comprised of Non-Spherical Particles Using the DEM-CFD

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Numerical Studies of the Dynamics of Gas-Fluidized Beds Comprised of Non-Spherical Particles Using the DEM-CFD

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