Studying the Influence of Moisture Content in Grain on the Efficiency of the Microwave Field Transfer into a Grain Layer with the Use of a Computer Model

Abstract

The objective of these studies was to determine the dependence of the distribution of the microwave field into a grain layer and the efficiency of energy transfer from the magnetron into the grain layer, via a waveguide, on the moisture content. The subject of the research was a semicircular waveguide with slot radiators that supply a microwave field to the grain surrounding the waveguide. The change in the directional diagram of the microwave field in the longitudinal direction of the waveguide was studied using CST Microwave Studio 2019 software. It was found that the change in the moisture content of the processed grain leads to a significant change in both the radiation and total efficiency values of the waveguide. For instance, the radiation efficiency of the waveguide decreases by 15.1% (from 68.729 dB to 58.294 dB) when the moisture content of the processed grain increases from 14% to 26%. The total radiation efficiency also decreases (from 11.27 dB to 21.7 dB). In this case, not only the value of the radiation efficiency but also the shape of its dependence on the magnetron radiation frequency change. The results of this study enable the formulation of a requirement for a selective approach to the alignment of emitting waveguides depending on the moisture content of the processed grain. Data were obtained on the change in the Q-factor for resonators in which grain layers are processed, depending on the variation in grain moisture content. The research results suggest that when designing microwave convective zones for grain processing, the quality factor of the resonator should not be considered as the primary parameter. The main focus should be on maximizing the radiation efficiency of the waveguides.