Analysis of Effectiveness and Stress Development during Convective and Microwave Drying

Abstract

The aim of the article is to study the effectiveness of convective and microwave drying with respect to drying time and stress generation in clay-like dried bodies. The theoretical analysis of stresses was confined to the constant drying rate period because clay shrinks and the stresses are generated mainly in this period. The theoretical prediction of stress development was validated using an acoustic emission method by monitoring the micro- and macrocracks formation caused by the stresses. Apart from the stress analysis, the combined convective-microwave drying was examined experimentally during whole process in order to show that the volumetric heat supply due to microwave heating enhances convective drying and, apart from this, such a combined drying process develops less stress in dried material. The theoretical and experimental studies were performed on a kaolin sample in the form of a thin plate.

Keywords:

• Acoustic emission
• Convective-microwave drying
• Effectiveness
• Stresses

ACKNOWLEDGEMENTS

This work was carried out as a part of the research project No. 3 T09C 030 28 sponsored by the Ministry of Science and Education.