Modeling and parameter identification of a maltodextrin DE 12 drying process in a convection oven

The drying kinetics of maltodextrin DE 12 in a convection oven are modeled using Fick's second law of diffusion and following the William, Landel and Ferry (WLF) equation for the moisture and temperature dependence of the effective diffusivity. An experimental design with a temperature range from 70°C to 140°C and sample amount varying from 4 to 12 ml is used. The resulting diffusion equation describing the dynamics of moisture content is highly nonlinear and possesses Dirichlet and Neumann boundary conditions. Ordinary differential equations are added to take the time-dependent variation of temperature into account. The method of lines is applied to discretize the partial differential equation w.r.t. the space variable leading to a highly stiff and numerically unstable system of ordinary differential equations. The data fitting problem is formulated to estimate some unknown model parameters simultaneously for 18 data sets under consideration.