Selective heating and moisture levelling in microwave-assisted drying of laminar materials: An explicit model

In the drying processes microwave energy can be applied in order to achieve a more uniform moisture content distribution enhancing, consequently, the final product quality. In many cases, experimental drying tests are carried out in the laboratory stage to characterise the moisture-levelling. However, based on the knowledge of dielectric properties vs. moisture content it should be possible to find out whether application of microwave heating is beneficial for moisture levelling or not. In this work, an explicit model of microwave selective heating and drying of laminar materials is presented and validated with experimental tests over leather samples. The validation of the model shows a very close relation between experimental and simulated curves and demonstrates that moisture levelling and selective heating for laminar materials can be explained based on the material dielectric properties and the microwave field intensity under certain conditions. The results indicate that as a consequence of moisture leveling drying curves show a fast convergence, leading to a more uniform moisture distribution within the hide. © Springer-Verlag Berlin Heidelberg 2006.