Application of the reaction engineering approach (REA) to model cyclic drying of thin layers of polyvinyl alcohol (PVA)/glycerol/water mixture

Rapid development of industrial polymer-based product requires considerable research in polymer drying. Cyclic or intermittent drying is used occasionally to save energy and improve product quality. Most published studies employ diffusion-based models. Reaction engineering approach (REA) is a lumped parameter model which is comparably simple and is now applied to cyclic situation for the first time. New definitions of equilibrium activation energy (ΔE_v,b) had to be introduced. With these definitions, very reasonable agreement between the predicted and published experimental data is shown. It has advantage over the diffusion model where in general complex diffusivity functions are used and had to be established using experimental data anyway. REA may be used in plant-wide simulations, where the drying kinetics has to be coupled with many other equations to be solved together. In this case, the computation time would be generally reduced if there is no need to solve the spatial distribution of water content inside the product.