Semi-resolved modeling of heat-up, drying and pyrolysis of biomass solid particles as a new feature in XDEM

The main aim of this study was to present a new approach for modeling multi-phase systems of granular media in which solid phases are fully resolved while the surrounding gas phase is semi-resolved. The presented method is based on a volume averaging model implemented in the XDEM framework in which the fluid phase is a continuous phase and individual particles are tracked with a Lagrangian approach. In the semi-resolved model, the gas phase is described on a length scale smaller than the particles size. This method facilitates mesh generation for complex geometries. Moreover, it is computationally less expensive than a fully resolved model since it allows for coarser grids to solve gas flow through the void space between particles. In this work, the proposed model is used to predict heat-up of steel particles and pyrolysis of wet wood particles in a packed bed. Numerical results have been compared with experimental data and good agreements were achieved. Detailed results in both gas and solid phases are presented, which highlight the process heterogeneities of non-uniformly packed beds.