Select the general principles of the dielectric drying

    (1) If the material to be dried load size of individual geometry is larger, should choose high-frequency heating and drying. Because the penetration depth is proportional to the wavelength, frequency drying the microwave penetration depth is about 100 times. Conversely, if the material to be dried is small geometry of the individual, the appropriate choice of microwave drying.

    (2) If the required power density, power density (power per unit volume of the input) is high, should be selected to treat the microwave drying or burning avoid arcing phenomena, such as the loose material (P <0.05) should be selected for microwave drying.

    (3) If the required power of large power (> 50kw), for economic reasons, should be selected frequency drying. Microwave dryer to allow the maximum power of 60kw, and general high frequency allows the use of the power of the dryer can reach 2-3MW.

    (4) the geometry of non-rectangular cross-section irregular object, multimode microwave resonant make the skin more uniform heating dryer.

    (5) drying system compatibility, such as pneumatic or hydraulic systems use mechanical, using the metal structure of the conveyor conveying mechanism made of a metal, unless the microwave shielding take special protective measures should sample frequency drying.

    (6) self-regulation of the heating process, if large fluctuations in the load or variation in the dielectric parameters, frequency drying with an electrode on the part of the electrode power tuning or changing advantages.

    (7) Self-inhibitory frequency impedance of the object can be heated, more self-restraint, will not appear heating / drying excesses. However, if the load at low frequencies, the loss factor is less than 0.5, then the more capacitance characteristics, in the process of reducing the dielectric constant of the main changes in the microwave process with better self-inhibition. For example, the paper drying process, when the moisture content is less than 5%, the high leveling effect is very weak, because the moisture content in the range, the frequency of self-inhibition of the material, but the paper may be dried microwave to the moisture content tends to zero state.

(8) Other conditions at the same output power, the high frequency is much higher than the field strength required for the microwave, may cause an electrical breakdown. Pressure, almost breakdown field plate electrode is 2000kv / m, and the material added the maximum allowable field strength death of 100kV / m, so that drying can be determined in the actual application of the maximum power density. In addition, high-frequency equipment, microwave equipment, low investment Jiao.