Waste recovery is one of the main pillars of the energy transition. The energy
needs associated with environmental issues require the use of new energy sources
and the development of eco-efficient processes for recycling waste. In this
context, thermal and/or catalytic solid waste treatment processes (urban,
biomass or plastics) have become an essential step in their recovery process in
a sustainable development and circular economy approach. The most common
operations in bulk material processing and handling are dosing, weighing,
drying, grinding, sieving, mixing, storage and conditioning. In the vast
majority of cases, these operations are linked together by pneumatic conveying
which becomes a key step in the process.
The PHOBARS project (Pneumatic Handling Of Bio And Recycled Solids) aims at
studying the pneumatic transport of non-conventional powders resulting from
plastic wastes or second-generation biomasses. Those particles are more
challenging to convey and were less investigated in the literature. A lack of
knowledge on the relationship among the properties of particles, the operating
conditions, the dimensions and configuration of the installations, and the
performance of the operation results in difficulty of design of transport lines.
There is therefore a need to better understand and model the behaviour of these
so-called non-conventional powders during pneumatic transport in order to better
control and optimize their implementation and transformation processes.
As a part of the project, multi-scale modelling of experimental results
according to different approaches such as Euler-Euler (TFM), Euler-Lagrange
(DEM-CFD) or hybrid Euler-Lagrange (Multi-Phase-Particle in Cell, MP-PIC), is
utilized to take into account the effect of gas/particle and particle/particle
interactions on transport dynamics.
CFD-DEM simulation of pneumatic conveying is increasingly used for modelling and
analyzing key phenomena such as flow regimes and their transitions, particle
attrition, electrostatic forces, etc. Despite the still very limited number of
particles that can be treated by this approach, it remains the only one capable
of giving a detailed description of the hydrodynamics of the operation by
integrating all the interactions which take place within the system.
The objective of this postdoc project is to perform CFD-DEM simulations to study
the effect of particles shape and electrostatic phenomena on pneumatic transport
of solids. The results will be compared to experimental data with the aim of
developing numerical models capable of predicting gas/solid flow behaviour with
various types of non-conventional solids and determining at which conditions the
common TFM or MP-PIC approaches may be used without losing significant
information on the flow dynamics. Phase diagrams of pneumatic conveying
(ΔP vs. gas velocity for different solid flow rates) will then be plotted. The
developed models would also be used for (i) acquiring information on complex
phenomena and operating conditions that are difficult to treat experimentally,
(ii) extrapolating pneumatic transport on a large scale (from pilot to
industrial scale), (iii) establishing design rules and (iv) troubleshooting
and optimizing the operation of the installation.
The simulation will be performed for vertical and horizontal flow. The data
relative to ΔP, particle velocity, concentration, particle-particle and
particle-wall forces will be collected for each simulation. In addition to the
typical forces acting on particles such as gravity, particleparticle
contact and gas-particle interaction, the electrostatic forces will also be
included. In addition to phase diagrams, further effort will be dedicated to
find the common properties/parameters that define the transition from one flow
regime to the other.
Candidate profile:
The candidate should have a PhD in Chemical or Mechanical Engineering with
knowledge of multiphase flow. Extensive experience with CFD-DEM is required. The
candidate must be autonomous and pragmatic. Knowledge of other CFD tools is also
appreciated.
Duration and remuneration :
1.5 year contract. Gross salary of around 3150 euros/month + welcome bonus.
To Apply:
Please send your Resume, Motivational letter, Two reference letters and a copy
of the first page of PhD dissertation reporting the completion date.
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