- In the present study a novel 3D theoretical model of multi-scale transport phenomena in spray drying process is presented. The model utilizes two-phase flow Eulerian-Lagrangian approach combined with a comprehensive description of two-stage drying kinetics for droplets of suspensions. The formulation of internal transport phenomena includes description of thermal and mechanical stresses which may appear in wet particles during the second stage of drying. The validation of the developed model incorporated into a commercial CFD package demonstrated both good agreement and consistency with the previous experimental and calculated data. The results of steady-state simulations showed that for small micron-sized silica particles considerable internal temperature gradients may emerge. Such gradients, together with intra-particle pressure manifest themselves as thermal and mechanical stresses and are possible reasons for cracking/breakage of the obtained particulate product.