Modelling dust liberation by Discrete Element Method and Computational Fluid Dynamics

Research of S.M. Ebrahim Derakhshani

Dust emissions are a common problem in many forms of industry. The examples are all around us: dry bulk terminals, construction, agriculture, and mining. In the foreseeable future the generation of dust will be hazardous for health, the environment as well as industry. The aim of this PhD project is to further develop the integration between Computational Fluid Dynamics and the Discrete Element Method, with emphasis on experimental validation and application for industrial situations.

Problem Domain

Dust emissions can have significant effects on the human health, environment and industry equipment. Understanding the dust generation helps to select a suitable dust preventing approach and also is useful to evaluate the environmental impact of dust emission. To describe these processes, numerical methods such as Computational Fluid Dynamics (CFD) are widely used, however nowadays particle based methods allow us to model interaction between particles and gas boundary layer. One of the gaps still faced by the modern CFD codes is the incapacity of simulating in details the motive systems involving granular solids, which are common in many industrial processes.

Goals/Objectives

The objective of this study is minimizing liberation of dust. For instance, influence of material properties and equipment characteristics on dust liberation will be studied and some of important parameters will be selected for using in numerical modelling.

1.  Reducing computational time by using an adjusting domain frame for fine granular materials: 
    a. Modelling behavior of bulk materials with the Discrete Element Method
    b. Dust liberation modelling with CFDEM

2.  Studying the effects of particle properties (Size, Shape, Particle distribution, Density, Cohesion, …) with DEM, and on the dust liberation by modelling with CFDEM

3.  Modeling dust liberation and finding effective parameter for controlling and minimizing dust liberation by a case study of transfer point based on modelling results

4.  Evaluating final code for a belt conveyor system

Approach

In fact dust generation mainly consider as two phase Solid-Gas flow. In the case of  multiphase flows  currently there are three approaches for the coupling numerical calculations:

• Euler-Lagrange approach
  This model allows momentum exchange between the fluid and the solid phases only. Lagrangian coupling may be considered the equivalent of the discrete particle method (DPM) model. Lagrangian coupling allows for only momentum exchange between the fluid and the solid phases.
• Euler-Euler approach
  This model allows momentum exchange between the fluid and solid phases, but also considers the effect of the particle solid fraction on the fluid phase. Eulerian coupling allows momentum exchange between the fluid and solid phases but additionally considers the effect of the particle solid fraction on the fluid phase.
• CFD-DEM coupling approach
  In the computational fluid dynamics (CFD) and discrete element method (DEM) coupling methods, the motion of discrete particles is obtained by solving Newton's equations of motion and the flow of continuum gas by the Navier–Stokes equations. The macroscopic behaviour of particulate matter is controlled by the interactions between individual particles as well as interactions with surrounding fluids. In comparison with methods 1 and 2, particle–particle interaction is also being used in this method.

Funding
This research is supported Ministery of Science , Research and Technology, Islamic Republic of IRAN. Their support is gratefully acknowledged.

Contact
S.M. Ebrahim Derakhshani
T +31 (0)15 27 87292
F +31 (0)15 27 81397
s.m.derakhshani@tudelft.nl
Room 8B-1-280
Mekelweg 2
2628 CD  Delft
Promotor: Prof.dr.ir. G. Lodewijks
Co-promotor/daily supervisor: Dr.ir. D.L. Schott