Erdem Simsek

Modeling of Granular Flow and Combined Heat Transfer in Hoppers by the Discrete Element Method (DEM)

The discrete element method can be used for modeling moving granular media in which heat and mass transport takes place. In this paper the concept of discrete element modeling with special emphasis on applicable force laws is introduced and the necessary equations for heat transport within particle assemblies are derived. Possible flow regimes in moving granular media are discussed. The developed discrete element model is applied to a new staged reforming process for biomass and waste utilization which employs a solid heat carrier. Results are presented for the flow regime and heat transport in substantial vessels of the process.

A Comparative Numerical Study of Particle Mixing on Different Grate Designs Through the Discrete Element Method

Based on LEAT’s discrete element codes, granular flow and mixing on conveying equipment are studied in two and three dimensions. Discrete element simulations, which are briefly introduced, provide detailed information on particle positions and velocities over time. This information is used to derive quantities characterizing the dynamic process of mixing. The main focus of the study presented is the mixing process of inhomogeneous particle ensembles on different grate types. For this purpose, the introduced mixing parameters are used to compare the mixing in a 3D situation with the corresponding 2D approximation on identical grates and to compare different grate designs in two dimensions.

An Experimental and Numerical Study of Transversal Dispersion of Granular Material on a Vibrating Conveyor

The mixing of thin granular layers transported on the surface of an oscillating trough is experimentally and numerically examined. The particle dispersion was experimentally quantified by an image processing system recording the growth of the mixing layer thickness of two differently colored but otherwise identical sand particle streams along the longitudinal position within the transporting channel. Granular flow and dispersion on the vibrating conveyor were studied numerically based on a three-dimensional discrete element code. Both experiments and simulations were used to derive quantities characterizing the transversal dispersion. The mixing was found to be directly proportional to the vertical acceleration of the conveyor and inversely proportional to the mass flow of the transported material. Keeping the above-mentioned parameters constant, the dispersion increases with increasing mean particle diameter. When performing the experiments with materials of different mean particle diameters and tuning the mass flow to achieve the same level of dimensionless bed height, the magnitude of the dispersion coefficient remains constant, as was also confirmed by the numerical simulation.

A Numerical Study of Particle Flow and Mixing on Conveying Equipment in Two and Three Dimensions by the Discrete Element Method (DEM)

Based on LEAT’s discrete element codes, granular flow and mixing on conveying equipment is studied in two and three dimensions. Discrete element simulations, which are briefly introduced, provide detailed information on particle positions and velocities over time. This information is used to derive quantities characterizing the dynamic process of mixing. The main focus of the study presented is the mixing process of inhomogeneous particle ensembles on different grate types. For this purpose the introduced mixing parameters are used to compare the mixing in a 3D situation with the corresponding 2D approximation on identical grates and to compare different grate designs in two dimensions.Copyright