Internship & PhD Positions 2015: Macroscopic Modeling of Biomass Pyrolysis

Rarefaction and price increase of fossil hydrocarbons, combined with more and more restrictive rules on Greenhouse Gas Emissions (GGE), involve a growing effort for research activities in the domain of new fuels. Using biomass, which is a renewable source with an almost neutral balance for GGE on its whole life cycle, is one of the most promising ways to achieve this objective. It is for example possible to convert, by means of a thermochemical way, raw materials coming from lignocellulosic plants (wood, straw, waste…) into a synthesis gas.
This gas is an energy vector that can later intervene in the production of pure hydrogen (directly usable as a fuel or in fuel cells) or hydrocarbons (via a Fischer-Tropsch-like process). Conversion can be realized in two steps:

  • Pyrolysis, which is a thermal decomposition of biomass into a carbonaceous residue and gas,
  • Gasification, which is a heterogeneous chemical reaction, i.e. interfacial, between the carbonaceous residue and a reactive gas (typically water vapor or carbon dioxide).

Modeling of these steps, from the scale of a biomass sample to the scale of an industrial reactor, will contribute to the development and optimization of this path of energy production.
The project we propose comes within the scope of modeling the pyrolysis phase for a wood particle. The difference between the considered scales (pores, whole particle) and the complexity of microstructure make impossible a local representation of transfer mechanisms at particle scale. A homogenized representation can then be obtained with the method of volume averaging, where the particle is represented by an equivalent continuous medium. The averaged conservation equations involve effective properties (permeability, conductivity…), which are determined by solving associated closure problems on elementary cells, representative of the local geometry.
During previous work, conversion of wood was described at local scale by two parallel phase changes (wood into gas and wood into carbonaceous residue), which kinetics follow Arrhenius’ laws. The macroscopic modeling, relying on local thermal equilibrium and on the resolution of closure problems on schematic structures, led to a simplified description, without convection, of the evolution of mass with time.
The objectives of this project are now to propose a more realistic description of the process of biomass pyrolysis when heat transfer description is obtained with a non-local thermal equilibrium, taking into account the main chemical species making up the gas and considering the evolution with time of the microstructure of a wood sample tomography.

Profile:

  • Researcher with a Master level (or equivalent), having good knowledge in Fluid Mechanics, Heat Transfer, Transport in Porous Media, Numerical Simulation and if possible in Chemical Engineering.
  • The candidate must be interested in Modeling, Applied Mathematics, Image Processing and Visualization Techniques.

Terms:

  • The Internship will last six months, with a start during the first semester of 2015, while the PhD will last three years, with a start in September or October 2015. Funding will be provided for both.

Location:

“Énergétique Moléculaire et Macroscopique, Combustion” Laboratory (EM2C)
Unité Propre de Recherche 288 of the Centre National de la Recherche Scientifique (CNRS) and École Centrale Paris
École Centrale Paris,
Grande voie des vignes,
92295 Châtenay-Malabry Cedex, France
(10 km in the South of Paris, reachable from Paris in less than 45 minutes by public transportation)

Contacts:

  • Fabien Bellet (Assistant Professor at ECP / EM2C, (+33) 1 41 13 10 47)
  • Benoît Goyeau (Professor at ECP / EM2C, (+33) 1 41 13 10 58)

Application:

  • Centrale Paris Actualités

Contact

Standard Téléphone : + 33 1 41 13 10 00 Fax : + 33 1 41 13 10 10 Courriel : webmaster@ecp.fr