Developing of a portable microwave convective drying plant for grain stored in bulk

The data of the analysis of the application of electrophysical influences are presented and the choice of using a microwave field for the intensification of heat and mass transfer is justified; the results of a numerical experiment on the propagation of a microwave field and dissipated power in a dense grain layer at different material humidity when microwave energy is supplied through slit radiators combined with the duct of a ventilation installation. The development of combined grain drying modes in a dense stationary layer requires taking into account the maximum levels of permissible heating and the pattern of propagation of thermal fields during exposure. (Research purpose) The research purpose is developing the design of a portable ultra-high-frequency convective installation for drying grain stored in bulk. (Materials and methods) Presented a model of a portable installation for combined ultrahigh-frequency convective processing. A model of a waveguide-emitter was given for numerical simulation. (Results and discussion) A numerical experiment was conducted to determine the propagation of the microwave field in a layer of wheat of different humidity. (Conclusions) It was revealed that the results of modeling the distribution of the microwave field intensity in the grain mass can be used to develop modes of combined grain drying, taking into account the peculiarities of the propagation of thermal fields, power dissipation and the operation of field sources. It has been shown that as an intensifying factor of heat and mass transfer processes for a stationary grain layer, it is advisable to use a microwave field in a pulsed mode of operation combined with active ventilation. It was established that in order to influence the grain layer, it is necessary to use a microwave field with a frequency of 915 Megahertz, however, the absence of commercially available microwave field sources with a power of 200-1000 watts with air cooling limits this possibility. It was determined that the use of sources operating at a frequency of 2.45 Gigahertz as a microwave field is possible taking into account the development of pulsed modes of microwave field supply. It was stated that the use of an air duct with slit radiators allows for the supply of microwave energy to the required level in the height of the treated layer.