Development of a generic thermomechanical model for pyrolyzing porous materials – PYROMECA

Pyrolysis is a key phenomenon for high temperature applications involving polymer materials. Some of them are at the heart of societal challenges such as biomass pyrolysis for the production of green energy and molecules. Three scientific communities have mainly contributed to the development of fundamental knowledge on pyrolysis : biomass pyrolysis, fire protection, atmospheric entry. A recent contribution enabled combining the progress of the three communities into a generic model, made available open source in a software framework. However, a first order phenomenon was never studied at a fundamental level: solid mechanics and deformation. Wood for example looses 50% of its volume and internal stresses lead to cracks. The objective of this project is to develop the field of thermomechanics of pyrolyzing materials, which we propose to call pyromechanics. Towards this end, we will revisit high temperature drying in order to account for liquid water pressure, thermodynamics of pyrolysis to account for pore pressure (poromechanics), and elastoplastic deformations generated by thermal dilatation and pyrolysis volume loss. Our team specialized in porous media will usefully combine diverse abilities to develop a new generation of models for pyrolyzing materials from the microscopic scale up to the macroscopic scale. For validation, we will develop an original in-situ pyrolysis module to study the multi-scale behavior of wood in a tomography facility.