Modelization of ascendant gas-liquid flows in small size fixed beds

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Modelization of ascendant gas-liquid flows in small size fixed beds

Context :

Catalytic fixed beds are widely used in chemical engineering, for petrochemistry applications, creation of biofuels, and other bio-chemistry applications. Fixed bed reactors consist in a stack of catalytic solid porous particles of various shape. At the pilot unit small scale, fixed beds are operated using ascendant gas-liquid flows. The complex gas-liquid hydrodynamics inside such systems is mostly unknown.

A numerical twin for gas-liquid flows inside catalytic fixed beds would thus be of highest interest to better understand and predict the involved physical phenomena. Direct Numerical Simulations can be realized, thanks to the small size of fixed bed reactors at the pilot unit scale.

Using CFD, a new insight in classical problems encountered experimentally, like preferential paths, wettability issues, uncertainties and random-ness, residence time maldistribution, mass transfer limitations and catalyst deactivation, is expected.

Description :

The overall objective of the project is to develop a numerical twin model for the simulation of catalytic fixed beds. The general approach will rely on developments based on the opensource software OpenFOAM. OpenFOAM is free of charge and provides full access to all its sources, making it a valuable and flexible platform for the implementation, testing and integration of new models.

After being trained to the OpenFOAM suite, this internship will have the following main objectives:

Train on fixed beds meshing and simulations, using single-phase flow solvers in a first place. Meshing will be done using available automatic tools, like snappyHexMesh.
Setup small size fixed beds Volume-Of-Fluid simulations, using a limited number of particles, on 2D and then 3D configurations. These cases can be taken from the literature, if available. Parameters like mesh sensitivity, existing boundary conditions (contact angle, partial slip) should be explored, as well as existing Adaptive Mesh Refinement (AMR) methods.
Explore the bibliography on boundary conditions to be applied on a catalyst particle wall. Catalytic particles are highly porous, which could conduct to develop specific boundary conditions. The accent will be put on lubrification models, during this research. The finite area method currently available in the code is a potential option to implement lubrication models.
Implement the selected method, if there is enough remaining time at the end of this internship.

Opportunity to continue with a PhD on the same subject.