Author
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NELSON, STUART - Former ARS Employee |
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Submitted to: Elsevier
Publication Type: Book / Chapter Publication Acceptance Date: 12/15/2014 Publication Date: 4/9/2015 Citation: Nelson, S. 2015. Dielectric properties of agricultural materials and their application. Elsevier. ISBN 978-0-12-802305-1. Interpretive Summary: This work is a compilation of results of more than sixty years’ research that ARS has conducted on dielectric properties of materials and their applications to problems in agriculture and related industries. It is prepared as a reference work for this particular field of science and engineering. Dielectric properties are electrical characteristics of materials that determine their interaction with electric fields. Dielectric properties of materials are therefore important in applications where radio-frequency and microwave energy is used for dielectric or microwave heating of materials such as agricultural products and food materials. The dielectric properties of agricultural products are also useful in sensing qualities of agricultural products that are correlated with their dielectric properties, because electrical instruments can be used to sense those properties and provide rapid measurements of quality attributes, such as moisture content in grain and seed. The theory and fundamental principles necessary for an understanding of the dielectric properties of agricultural materials are presented early in the book. The dependence of those properties on variables such as moisture content, frequency of the applied electric fields, temperature of the materials and their density is also discussed. Techniques for measurement of the dielectric properties are presented for frequencies ranging from audio frequencies to microwaves. A wide range of agricultural applications is discussed, including dielectric heating for treatment of seed-borne pathogens; radio-frequency heating of insects in grain to control stored-grain insects; seed treatment by dielectric heating to improve germination; product conditioning to improve nutritional value of soybeans, carotene retention in alfalfa forage, and quality maintenance in pecans; sensing moisture content in grain and seed; assessment of microwaves for soil pest control; quality sensing in fruits and vegetables; and sensing moisture and density in solid biofuels. Included are dielectric properties information relating to mining applications such as dielectric heating for rock fragmentation, selective heating of pyrite in coal, and measuring rock and coal dust proportions for mine safety purposes. Dielectric properties of selected foods are included to show their variation with frequency, moisture content, and temperature. Mathematical models for the dielectric properties of grain and seed are presented so that estimates of their values can be calculated when needed for research or practical applications. The development of microwave moisture sensing instrumentation is also described for the nondestructive measurement of kernel moisture content in unshelled peanuts and for continuous monitoring of kernel moisture content in peanut pods during the drying process. In addition, dielectric properties data are included for several kinds of grain and oilseed, fresh fruits and vegetables, pecan nuts, and insects for reference purposes. The book provides a comprehensive source of information on dielectric properties of agricultural materials for scientific researchers and engineers involved in practical application of radio-frequency and microwave energy for potential problem solutions. Technical Abstract: This book is prepared as a comprehensive source of information on dielectric properties of agricultural materials for scientific researchers and engineers involved in practical application of radio-frequency and microwave energy for potential problem solutions. Dielectric properties of materials determine the interaction of the materials with electric fields. They are therefore important in applications where radio-frequency and microwave energy is used for dielectric or microwave heating of materials such as agricultural products and food materials. The dielectric properties of agricultural products are also useful in sensing qualities of agricultural products that are correlated with their dielectric properties, because electrical instruments can be used to sense those properties and provide rapid measurements of quality attributes, such as moisture content in grain and seed. The theory and fundamental principles necessary for an understanding of the dielectric properties of agricultural materials are presented early in the book. The dependence of those properties on variables such as moisture content, frequency of the applied electric fields, temperature of the materials and their density is also discussed. Techniques for measurement of the dielectric properties are presented for frequencies ranging from audio frequencies to microwaves. A wide range of agricultural applications is discussed, including dielectric heating for treatment of seed-borne pathogens; radio-frequency heating of insects in grain to control the insects; seed treatment by dielectric heating to improve germination; product conditioning to improve nutritional value of soybeans, carotene retention in alfalfa forage, and maintenance of quality in pecans; sensing moisture content in grain and seed; assessment of microwave energy for soil pest control; quality sensing in fruits and vegetables; and sensing moisture and density in solid biofuels. Included are dielectric properties information relating to mining applications such as dielectric heating for rock fragmentation, selective heating of pyrite in coal, and measuring rock and coal dust proportions for mine safety purposes. Dielectric properties of selected foods are included to show their variation with frequency, moisture content, and temperature. Mathematical models for the dielectric properties of grain and seed are presented so that estimates of their values can be calculated when needed for research or practical applications. The development of microwave moisture sensing instrumentation is also described for the nondestructive measurement of kernel moisture content in unshelled peanuts and for continuous monitoring of kernel moisture content in peanut pods during the drying process. In addition, dielectric properties data are included for several kinds of grain and oilseed, fresh fruits and vegetables, pecan nuts, and insects for reference purposes. |
