Analysis of the advantages and disadvantages of microwave drying equipment

Any drying method has its own advantages and disadvantages. Compared with conventional heating and drying methods, microwave drying equipment has incomparable advantages, but does this drying method also have disadvantages? By analyzing the characteristics of microwave drying, this paper reveals the mystery of the advantages and disadvantages of microwave drying.

Advantages of microwave features (compared with conventional heating modes)

Penetrating radiation, direct integral accumulation heating material heating from the inside, low test surface temperature (temperature gradient inversion), instantaneous power and temperature response, heating materials in a clean environment, microwave transparent material is difficult to be heated, and a bad temperature conductor will form a large temperature gradient or lead to uneven heating.

Controllable energy (field) distribution of instantaneous energy is highly concentrated, optimizes the power-time relationship, improves production, and improves product quality. It can operate, but process automation equipment is more expensive and complex and should be specially designed above the critical temperature. Material dielectric loss increased rapidly, but rapid heating (10–50 times faster than normal temperature heating), rapid drying, rubber, etc. will not cause cracking. Reduce the process cost (saving energy consumption, time, space, labor, etc.). Too fast heating will lead to "hot spots" and "thermal runaway" and the sample temperature is difficult to measure.

For different degrees of coupling of material components, the selection of heating can selectively heat the interior or surface of the material. Through additives or coatings, the sintering of microwave-transparent materials can sometimes react with undesirable impurities or contamination with the insulation layer.

Automatic control When a component heats, the heating can terminate, making it difficult to maintain a certain temperature.

The advantages of microwave drying cannot be surpassed, but the disadvantages of microwave drying also give the manufacturers and users a severe test. 

For microwave equipment manufacturers, the magnetic field distribution of microwave should be strictly controlled to ensure uniform heating of materials; the temperature control probe should be set to prevent "thermal runaway" in the heating process; an automatic temperature control device should be set to control the material temperature within the required temperature section; in addition, appropriate equipment material should be selected so that the material does not react with the microwave cavity or break down the cavity. For users, it is necessary to choose pure materials to prevent materials and impurities from entering the microwave heating process, resulting in material pollution. More important is the selection of good microwave manufacturers and good microwave equipment.