Convective drying of wood chips: Accelerating coupled DEM-CFD simulations with parametrized reduced single particle models

The simulation of industry-scale reactive bulks is challenging due to the complex interaction between fluid and particles. The particles in the bulk and their interaction with the fluid flow can be described by combined Discrete Element Method - Computational Fluid Dynamics (DEM-CFD) models. However, the computational cost of the Finite Volume (FV) methods deployed in these models can become prohibitively expensive, especially for high inner-particle resolution. Single particle Reduced Models (RMs) can be used to achieve both fast and accurate descriptions of the processes in each particle. As an example of bulk systems comprising heat and mass transfer, we compared FV and RM simulations for the drying of wood chips in a bulk reactor. A manifold-based nonlinear interpolation was applied to resolve changing boundary conditions for the RM. Our simulations showed that RMs provide accurate values for the thermodynamic state variables of the particles. Furthermore, the time required for the bulk simulation was reduced by 67% with the RMs. It is evident that simulations with high inner-particle resolution can be accelerated by RMs if manifold-based nonlinear interpolation is used to address changing boundary conditions.