(29c) Microwave and RF Drying of Heat Sensitive and Difficult to Dry Materials

While speed of heating and drying are considered major advantages for the use of microwaves, these are usually not enough to justify the high cost of using this energy source for processing, especially for large bulk materials. On the other hand, microwave drying is especially useful when it comes to drawing heat sensitive materials, or materials that may be otherwise difficult to dry. The unique manner in which microwaves evaporates solvents such as water or alcohol without the need for high temperature auxiliary heat, also permits drying at low temperatures, thereby providing a means for the removal of such solvents from heat sensitive materials. Because of these and other factors, microwave drying can provide a cost effective alternative to conventional processing. This paper will present the theory of microwave drying, as well as provide numerous examples of its industrial application.