Study of a computer model of the influence of structural elements and grain moisture on the Q-factor of the microwave-convective zone

   Grain drying after harvesting is often carried out in convective grain dryers with microwave exposure. When designing microwave devices with resonators strive to achieve the maximum efficiency (Q-factor) of microwave convection zones. Due to the lack of studies on the influence of grain humidity and elements located in the microwave convective zone on its Q-factor, the authors investigated these dependences on a computer model. Using the CST Microwave Studio 2019 software, the authors obtained the data on the change in the Q-factor of the resonators. Time Domain Solver methods were used to perform the calculation of the microwave active zone in a wide range of frequencies, and Eigenmode Solver methods – to find the eigenmodes (natural modes) of resonant structures. Computer modeling was carried out in two stages. At the first stage, the authors evaluated the influence on the Q-factor value of the placement in the microwave convective zone of the waveguides. At the second stage, the authors analyzed the change in the Q-factor of microwave convective zone with waveguides and grain of different moisture content (14, 24, and 26 %). The study established significant dependence of the Q-factor of the grain processing zone on the design features and placement of technological elements in it, as well as on the humidity of the processed grain and its temperature. The authors recommended that when designing microwave convective zone for technological processes, the goal should be not to achieve the maximum Q-factor, but to ensure uniform distribution of the microwave field in the active zone.

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