What Is a Microwave Heating System?
A microwave heating system is a system that heats dielectric materials using electromagnetic waves with a wavelength of about micrometers.
In other heating methods (using radiation from hot air or electric heating), heat is gradually conducted from the surface of the object and heated, which takes a certain amount of time.
Microwave heating, however, reacts directly with the molecules inside the material, thus raising the internal temperature in a shorter time. Because microwaves can be irradiated almost uniformly to the target, even inside and outside of the material can be heated uniformly. Since the heating efficiency varies depending on the dielectric loss of the target, the material can also be selectively heated according to the loss factor.
Uses for Microwave Heating System
Although microwave heating systems are best known for their use in microwave ovens, they are also applied industrially for food-related applications.
Specifically, they are used for cooking, sterilization, and drying of food products. For example, when microwave heating system is used in the process of heating chicken, the heating time can be reduced by half compared to the conventional method, and even partial darkening of the bones can be prevented.
Microwave heating is also used to dry wood, printed matter, textiles, and paper, and in the medical field, thermal therapy is being used to treat cancer.
Principle of Microwave Heating System
Electromagnetic waves such as microwaves act on materials by periodically changing the intensity of the electric field.
Unlike conductors such as metals, molecules of insulators (dielectrics) such as water have their own polarity, so they react with the electric field of electromagnetic waves, causing a bias in the distribution of positive and negative charges among the molecules inside the dielectric.
As the frequency of electromagnetic waves increases, the molecules that make up the dielectric rotate and vibrate violently and collide with each other, but a higher frequency does not necessarily mean that heating is easier. If the frequency is too high, the molecules inside the dielectric cannot respond.
In the case of water, it reacts well with electromagnetic waves in the microwave region (infrared rays). The energy generated by the reaction (internal energy) is converted into heat, which heats the dielectric. Microwave heating systems are equipped with electron tubes called magnetrons to generate microwaves. The microwaves emitted from this tube are guided into the heating oven, where they heat the object.