Advancing a 3D pore-informed continuum particle model through combined numerical analysis and experimental characterization: Application to particle heating

Accurate modeling of biomass pyrolysis requires particle-scale approaches that capture the influence of intra-particle structure and morphology on transport processes while remaining computationally tractable. In this work, a three-dimensional pore-informed continuum particle model was developed to investigate the effects of intra-particle structure and particle shape on particle heating. The model is supported by time-resolved measurements of internal and surface temperatures under constant heating rate and near-isothermal reactor conditions at approximately 600 °C. Experiments were conducted using natural beech wood particles (spheres and cubes), densified wood particles (spheres and cubes), and non-reactive aluminium oxide particles (cubes). The particle model incorporates permeability coefficients derived from pore-resolved simulations for natural wood, densified wood, and aluminium oxide particles. A thermal conductivity tensor was also derived from pore-resolved simulations for natural wood, while values from literature were used for densified wood and aluminium oxide particles. Intra-particle temperatures were measured using embedded thermocouples, while surface temperatures were obtained using a surface thermocouple and lifetime-based phosphor thermometry. The experiments revealed differences in the intra-particle temperature evolution of natural wood particles, consistent with anisotropic intra-particle transport, with less pronounced shape-induced effects. For densified particles, shape-dependent differences were also small. Using phosphor thermometry-based surface temperatures as thermal boundary conditions, the model reproduced the experimental intra-particle temperatures for aluminium oxide and for wood particles up to approximately 200–250 °C, above which pyrolysis reactions become significant, not included in the present model. The simulated temperature fields showed only weak anisotropic effects, likely partly due to the spatially uniform thermal boundary condition. Overall, the proposed numerical–experimental framework provides a basis for future extensions including reactive conversion, evolving particle morphology, and dynamically changing transport properties.