The Use of Microwave Energy at Thermal Treatment of Grain Crops

The Use of Microwave Energy at Thermal Treatment of Grain Crops

Dmitry Budnikov (Federal Scientific Agroengineering Center VIM, Russia) and Aleksey Vasiliev (Federal Scientific Agroengineering Center VIM, Russia)
DOI: 10.4018/978-1-5225-3867-7.ch020


Thermal treatment is used for different grain crops during the processes of drying, disinfection, and preparation to feeding, etc. The high cost of the processes is caused by the cost of energy and the energy-output ratio of the processes. The development of the processing regimes with the use of electric technologies in general and electromagnetic fields in particular can reduce the cost of the mentioned processes. When IR and MW fields are used, there occurs the direct heating of the grain material without the coolant, due to the effect of the field on water molecules in the kernels. As the grain is a colloid capillary-porous substance, moisture can be in a bound or free state that affects the properties of the material and the thermal processes in it. The use of the special programs gives vast possibilities for the design of such equipment. Using of MW fields allows reducing the cost of the thermal treatment 15-20% depending on the process and type of the processing material.
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Dielectrics are a class of materials that are poor conductors of electricity, in contrast to materials such as metals that are generally good electrical conductors. Many materials, including foods, living organisms, and most agricultural products, conduct electric currents to some degree, but they are still classified as dielectrics. The electrical nature of these materials can be described by their dielectric properties, which influence the distribution of electromagnetic fields and currents in the region occupied by the materials, and which determine the behavior of the materials in electric fields. Thus, the dielectric properties determine how rapidly a material will warm up in RF or microwave dielectric heating applications. Their influence on electric fields also provides a means for sensing certain other properties of materials, which may be correlated with the dielectric properties, by nondestructive electrical measurements. Therefore, dielectric properties of agricultural products may be important for quality-sensing applications in the agricultural industry as well as in dielectric heating applications (Bakker-Arkema F.W., 1995; Nelson S.O., 2015, 2004; Suzan Tireki, 2006; Stanislaw Grundas, 2008).

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