Uniformity Issue in Microwave Drying

Abstract

Microwave drying is an advanced drying technique in which heat is generated inside the material due to transformation of high-frequency electromagnetic energy so the liquid moisture is intensively evaporated and transported toward the material surface. However, an inherent problem in microwave drying is nonuniform heat generation, which leads to uneven drying. In this article, the factors causing nonuniform microwave heating were identified, and feasible approaches to solving the nonuniformity problem were analyzed in terms of improving the uniformity of the electromagnetic field distribution and random or organized dislocation of the processed material in virtually nonuniform microwave field. The R&D trends in microwave drying toward reducing uneven heating were pointed out and discussed.

Keywords:

• Drying
• Heat generation
• Heating uniformity
• Hybrid technologies
• Microwaves
• Temperature distribution

Notes

T. Kudra is an honorary professor at Tianjin University of Science and Technology. He is currently at CanmetENERGY in Varennes, Canada.