Microwave drying principle:

Microwave is an electromagnetic wave with extremely short wavelength, between 1mm and 1m, and its corresponding frequency is between 300GHz and 300MHz. In order to prevent microwaves from interfering with radio communications, broadcasts and radars, there are four internationally specified frequencies for microwave heating and microwave drying, namely: L segment, with a frequency of 890~940MHz and a center wavelength of 330mm; S segment, with a frequency of 330mm 2400～2500MHz, the center wavelength is 122mm; C segment, the frequency is 5725～5875MHz, the center wavelength is 52mm; K segment, the frequency is 22000～22250MHz, the center wavelength is 8mm. Only L segments and S segments are used in household microwave ovens.

Microwaves are obtained by passing direct current or 50Hz alternating current through electric vacuum devices or semiconductor devices, and using electrons to make special movements in the magnetic field. This kind of motion can be explained simply like this: From the perspective of the electrical structure of the medium, one type of molecules is called nonpolar molecule dielectric, and the other type is called polar molecule dielectric. Under normal circumstances, they are arranged randomly. If they are placed in an alternating electric field, the polar molecular orientation of these media will also change with the change of the polarity of the electric field. This is called polarization. The stronger the external electric field, the stronger the polarization, the faster the polarity of the external electric field changes, the faster the polarization, and the more intense the thermal motion of molecules and the friction between adjacent molecules. In this process, the conversion of electromagnetic energy to thermal energy is completed. When the heated substance is placed in the microwave field, its polar molecules swing and rub back and forth with the microwave frequency at a high frequency of billions of times per second, generating heat. It is enough to achieve the purpose of heat drying the material in a short time.