Industrial Microwave Heating

This book offers a broad coverage of the theory and practice of industrial microwave heating. It introduces the physical processes behind dipolar and conductivity loss mechanisms and follows with a thorough presentation of dielectric property data of many industrial materials as a function of the moisture content, temperature and frequency, focussing on the interpretation of such data as regards the suitabiliy for processing these materials with microwave energy. The basic equations which govern the power dissipation, attenuation, phase constant, penetration depth and skin depth are derived from first principles while the transport equations of heat, mass and pressure are qualitatively described, giving particular emphasis to the physical mechanisms behind high frequency drying. The book provides established procedures backed by theoretical formulations for the design of industrial travelling wave and multimode applicators. It also provides extensive coverage of single mode fundamental or higher order resonant cavities and outlines a number of atypical applicator structures. It describes the essential features of processing with microwaves under vacuum and presents a brief introduction to the mechanisms which lead to gas breakdown. It stresses the need for a degree of hybridisation with other electrical or conventional heating systems and discusses a few such schemes. The book outlines a number of systems for limiting leakage from on-line industrial microwave systems and concludes with an extensive discussion of successful industrial applications.