ABSTRACT
Increasing demands for new and high-quality products, energy-efcient processes, environment protection, and the like have stimulated progress in drying science and technology. Mujumdar has presented a summary of the motivation for development of new drying technologies and identied a number of trends, which include the following [1]:
• Use of superheated steam in direct dryers • Increased use of indirect (conduction) heating • Use of combined (or integrated) heat transfer modes • Use of volumetric heating (microwave [MW]/radio-
frequency [RF] elds) in specialized situations • Use of two-stage (or multistage) dryers • Use of intermittent heat transfer • Use of novel combustion technologies (e.g., pulse
combustion for ¤ash drying) • Use of novel gas-solid contactors (e.g., 2D spouted
beds, intermittent or rotating spouted beds) • Design of ¤exible, multiprocessing dryers • Combination of different dryer types
Many of these topics are covered in detail elsewhere in this handbook. There are numerous other technologies that have reached various stages of maturity-ranging from concepts and pilot-scale demonstrations to large-scale industrial applications. Several of these have been reviewed in the recent literature [2].
