Pylypenko Y. Mechanisms, kinetics and energetics of dehydration processes under the conditions of combined microwave and infrared energy generators operation

The dissertation work is devoted to the study of the impact of the dehydration process of food raw material by involving electromagnetic energy sources and the development of equipment based on these technologies. A healthy nation is a strong state. This thesis should be the basis of all activity spheres of the society of each country. Ensuring good health is first of all a healthy diet. The diet of each person should include all nutrients, the source of which is usually plant raw materials. However, since ancient times, mankind has faced the main problem of preserving fresh products from spoilage. In general, the problem of storage is related to the high moisture content of food raw material, the solution of which lies in its removal. The drying process is one of the oldest methods of processing food raw material with the aim of extending the shelf life, reducing the total weight to solve the problems of transporting large volumes of products. Today, the classification of drying technologies by the method of organizing the process includes many types, among which the most common are: convective, contact, radiation, alternative energy sources, dielectric, sublimation, etc. drying. During the 20th century, in conditions of low prices for energy carriers, domestic production acquired rapid development of convective dryers. Increasing the productivity of convective dryers was usually achieved by increasing the speed of the drying agent. However, at the same time, thermal energy losses along with spent drying agent also increased rapidly, significantly reducing the energy efficiency of the plant up to 20%, which is not acceptable in the context of the current situation on the energy market. However, along with the development of drying technologies, scientific research aimed at solving the resource and energy efficiency problems of dehydration processes was actively conducted, anticipating an energy crisis in the world market. Recently, the scientific community is increasingly paying attention to electromagnetic energy sources. The analysis of the available literary data and research results showed that the interest in the development of drying technologies in this direction has gained significant momentum, but the prospects for the involvement of such technologies have not yet been fully revealed. Numerous results of experimental studies are of a limited nature. Recommendations for introduction into production are not presented. Algorithms for calculating drying equipment based on electromagnetic energy sources have not yet been developed. This work is devoted to the solution of these problems. First of all, the theoretical foundations and technique of traditional drying equipment were considered. The scientific and technical problems of the existing drying equipment were highlighted and ways of solving them were proposed. It is assumed that the organization of direct energy delivery to the product or even to the moisture contained in the product, without the use of an intermediate heat carrier, through the interaction of electromagnetic radiation of the microwave and infrared ranges, will allow to significantly reduce energy costs and the duration of the drying process without harming the structure and quality of the raw material. At the second stage, based on the proposed assumptions, scientific and technical hypotheses were formulated, which clearly describe the intensification mechanism of dehydration processes under the electromagnetic field conditions, along with a significant increase in the feasibility of using raw and energy resources. Analytical modeling of dehydration processes under the conditions of an electromagnetic field in the IR and MW range was carried out. On the basis of parametric and physical drying models, an implicit model in generalized variables was obtained using the methods of similarity theory. The third stage consists in the direct conduct of experimental studies and the construction of kinetic dependences of dehydration processes under the conditions of an electromagnetic field action in a stationary layer. The obtained results give the right to claim that technologies of address energy delivery directly to moisture in raw material lead to significant intensification of moisture removal. The result of the fourth stage was the designed belt dryer with the combined action of infrared and microwave emitters. Experimental studies of the dehydration process kinetics in the moving layer were quite positive due to the removal of moisture to the surface of the product due to the volume introduction of microwave energy, and its subsequent removal from the surface by processing in the conditions of the infrared field. The design of a belt dryer with combined infrared and microwave energy sources has successfully passed production tests at the Vygodyansk branch of SE "Suntrade".