Anaerobic Biogas Digester Modelling

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Anaerobic Biogas Digester
Modelling
Using OpenFOAM and Fluent
Andrew Coughtrie
Civil Engineering
Biogas Digestion?
Problem Definition
• Waste Treatment
• Mixing effectiveness
• Failure when scaled up
• Difficult to monitor
experimentally
Experimental bench scale internal airlift loop biogas digester.*
* Karim k. et al. [2007] Gas-lift Digester Configuration Effects on Mixing Effectiveness
CFD
• Structured square mesh
• Ansys Meshing and
BlockMesh
• Approximation for inlet
boundary
Slurry Surface
Inlet
Outlet
Walls
Problem Setup
• Inlet boundary condition based on approximation
of flow velocity
• RNG k-epsilon turbulence model
• Zero shear wall at surface
OpenFOAM Control
Linear solver
Discretisation Schemes
Function to monitor velocity
Fluent Wall Treatment
Standard Wall
Functions
Scalable Wall
Functions
Enhanced Wall
Treatment
Fluent vs. OpenFOAM
OpenFOAM
*Karim k. et al. [2004] Flow Pattern Visualization of a Simulated Digester
Fluent
OpenFOAM
Fluent
Experimental*
Single-phase vs. Multiphase
DPM
Single-Phase
Ongoing Work
• Non-Newtonian fluid modelling
• Comparison between single and multiphase
for OpenFOAM and Fluent
• Multiphase 3D modelling
• Euler-Euler Multiphase using OpenFOAM
Three-Dimensional
• Full 3D geometry for
DPM
• Import mesh to
OpenFOAM for use with
bubbleFoam
Questions?

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