Optimal control of convective drying of saturated porous materials



Numerical simulations of optimal control applied to saturated capillary-porous materials subjected to convective drying are presented. The optimization process is concerned with such drying parameters as drying rate, energy consumption, and product quality. The thermo-hydro-mechanical model of drying is developed to describe the kinetics of drying and to determine the drying-induced stresses which are responsible for damage of dried products. The effective and the admissible stresses are defined and used to formulate the Huber-von Mises–Hencky strength criterion enabling assessment of possible material damage. The method of genetic algorithm is used for operation with drying conditions in such a way as to ensure minimum energy consumption and to get the effective stress less than the strength of dried material, and thus, to preserve a good quality of dried products at possibly high drying rate. Numerically simulated optimal drying processes are illustrated on the examples of finite dimensions of kaolin-clay cylinders subjected to convective drying. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4846–4857, 2013