ИЗЛУЧАТЕЛИ ДЛЯ СВЕРХВЫСОКОЧАСТОТНЫХ КОНВЕКТИВНЫХ УСТАНОВОК. РЕЗУЛЬТАТЫ МОДЕЛИРОВАНИЯ

Abstract

The studies were carried out to simulate the distribution of the electromagnetic field to assess the efficiency of three types of emitters according to the following parameters: standing wave coefficient, which makes it possible to compare the consistency of emitters; radiation efficiency, showing the amount of energy transferred to the grain layer; microwave field radiation pattern, which allows one to evaluate the uniformity of the field distribution in the grain layer. For evaluation and comparison, three types of waveguides were considered: horn, rectangular with slot emitters; semicircular with slot emitters. The distribution of the electromagnetic field was modeled using the CST Microwave Studio program. The use of horn waveguides in ultra-high-frequency convective installations makes it possible to produce fairly simple devices for grain processing. The standing wave coefficient for the operating frequency in this case is 1.3, with a radiation efficiency of 78 dB. However, they do not ensure uniform distribution of the ultrahigh frequency field at the exit from the waveguide, which affects the efficiency of grain processing. The use of rectangular waveguides 55 mm × 110 mm with slot emitters ensures more uniform radiation of the electromagnetic field across the entire spectrum of wave types. The standing wave ratio is 1.0 and the radiation efficiency is 94.43 dB. However, their use requires additional design developments to ensure the supply of coolant to the processing zone. Semicircular waveguides with slot emitters provide a standing wave ratio of 1.0 over the entire frequency range from 2 to 3 GHz. Radiation efficiency is 94.28 dB. The uniformity of the electromagnetic field distribution along a semicircular waveguide is better than along a rectangular one.