Numerical simulation and sensitivity analysis of hot air drying for irregular flake materials based on fully coupled of multi-physics fields

Abstract

The multi-physics coupling mechanisms of irregular flake materials during hot air drying remain unclear. Therefore, a three-dimensional thermal-mass-mechanical bidirectional fully coupled model was established in this study, incorporating shrinkage deformation, dynamic porosity variations, and their feedback effects on heat and mass transfer. The model’s accuracy was validated through experiments, systematically revealing the spatially asymmetric distribution characteristics of temperature-moisture fields and stress–strain fields in materials of different sizes, along with their dynamic evolution patterns associated with structural features. The interaction mechanisms between material dimensions and drying parameters were elucidated. Sensitivity analysis using the OAT method quantified the influence of key parameters on the drying process. The research demonstrates that small-sized materials exhibit uniform thermal-moisture distribution and low stress–strain characteristics due to their high specific surface area and short mass transfer paths, while large-sized materials show significantly increased thermal and moisture stresses with stress concentration prone to occur at concave regions. Moisture stress dominates shrinkage deformation, showing positive correlations with both material size and temperature. Material size exerts a more pronounced influence on drying efficiency compared to temperature. Sensitivity analysis reveals that small-sized materials demonstrate significantly higher sensitivity to external parameters than large-sized ones, while large-sized materials are more affected by Poisson’s ratio and thermal conductivity. Young’s modulus regulates stress states but shows no correlation with the timing of stress peaks. The study further proposes separating small-sized materials from medium/large ones during drying processes, and optimizing drying temperature and mass transfer conditions to balance porosity changes with stress concentration, thereby enhancing drying uniformity. This research provides theoretical support from a multi-physics coupling perspective for optimizing drying processes, inhibiting shrinkage deformation, and improving product quality, offering practical guidance for relevant industrial applications.