[Abstract] The principle and characteristics of microwave drying equipment and the basic composition of microwave drying system were analyzed. At the same time, the application of microwave drying equipment in agricultural products drying was predicted and analyzed.
[Key words] drying; microwave; microwave drying of agricultural products.
1 Fundamentals of microwave drying
1.1 principle of microwave heating
Microwave refers to electromagnetic waves with penetrating characteristics in the wavelength range of 1 m~1 m and frequency range of 3.0*102~3.0*105 MHz. The commonly used microwave frequencies are 915 MHz and 2 450 MHz. The magnetron of the microwave generator receives power from the power supply and generates microwave power, which is transmitted to the microwave heater through the waveguide. The materials that need to be heated are heated under the action of microwave field.
Microwave heating utilizes the principle of dielectric loss, and the loss factor of water is much larger than that of dry matter. Most of the energy released by electromagnetic field is absorbed by water molecules in the material. Generally speaking, due to Brownian motion, the arrangement of water molecules in dried materials is disorderly and rapidly changing.
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