Industrial Microwave Heating

by A.C. Metaxas, R.J. Meredith

Overview

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.

Product Details

ISBN-13:	9780906048894
Publisher:	The Institution of Engineering and Technology
Publication date:	06/30/1988
Series:	Energy Engineering , #4
Pages:	376
Product dimensions:	6.00(w) x 9.10(h) x 0.90(d)

About the Author

Ricky Metaxas is a Teaching Fellow at the UniversityEngineering Department and Fellow of St John's College, Cambridge. He received a BSc in Electrical Engineering and a PhD in Physics in 1968 from Imperial College, London, for work on two stage ionisation phenomena in radio frequency discharges. In 1968 he joined the Department of Physics at the UniversityCollege of Swansea, Wales, as a Post-Doctoral Fellow where he worked on problems related to fusion reactors. Between 1972 and 1982 he was a member of the Electrophysics Group of the Electricity Council Research Centre, England, where he specialised in industrial applications of radio frequency and microwave energy. Since 1982 Dr Metaxas has been teaching topics related to energy utilisation and electroheat. In 1986 he was the recipient of the Outstanding Paper Award from the International Microwave Power Institute for the most significant contribution to the Journal of Microwave Power during 1985.

Roger Meredith is Managing Director of APV-Magnetronics Ltd, a wholly owned subsidiary of APV Baker plc. He graduated from the Universityof Bristol in 1951 in Electrical Engineering. After a graduate apprenticeship with the former British Thomson Houston Co (now GEC) he joined the electronic engineering department and worked on microwave systems and transmitters for radio and communications and industrial heating for fifteen years. In 1968 he formed Magnetronics Ltd, to specialise in industrial applications of microwave energy.

Table of Contents

• Chapter 1: Introduction
• Chapter 2: Dielectric loss
• Chapter 3: Dielectric properties
• Chapter 4: Theoretical aspects of volumetric heating
• Chapter 5: Travelling wave applicators
• Chapter 6: Multimode oven applicators
• Chapter 7: Single mode resonant cavities
• Chapter 8: Special applicator structures
• Chapter 9: The microwave heating circuit, breakdown phenomena andvacuum processing
• Chapter 10: Hazards, leakage and safety
• Chapter 11: Industrial applications
• Appendix 1: Definitions of moisture content
• Appendix 2: Conversion of various units to SI units
• Appendix 3: Some useful trigonometric functions and formulae
• Appendix 4: Some useful series and Bessel functions
• Appendix 5: Some useful constants and temperature interrelation
• Appendix 6: Relation between dB and power and voltage ratios following the function dB = 20 log₁₀(V_A/V_B) = 10 log₁₀(P_A/P_B)
• Appendix 7: Waveguide frequency ranges, dimensions and official designations
• Appendix 8: Glossary of radio frequency and microwave heating terms used in this book