Microwave heating principle
    Microwave is the wavelength of 1 mm to 1 m of electromagnetic waves, electromagnetic waves , such as it has a reflection, transmission , interference, diffraction, polarization and energy transmission wave characteristics . In recent years, the microwave heating characteristics of the further development of efficient , making its application field of communications shift from the traditional chemistry, material processing , pollution control and other fields. Which, in the field of pollution control , particularly in the industrial sludge , medical waste , used tires , electronic waste and construction waste and other solid waste disposal has made great progress .
    In the microwave heating process, the microwave energy into heat has two mechanisms , namely dipole rotation mechanism and the mechanism of ion conduction . Dipole rotation mechanism is inside the object by the microwave radiation-induced friction between molecules to generate heat . The nature of the media are made with a positive charge at one end , the other end of the negatively charged molecules ( or dipole ) components. In the natural state , as a medium dipole haphazard movement and arrangement , when the medium in an electric field , the internal re- arranged into a certain orientation , a regular arrangement of polarized molecules. When the alternating electric field is changed to a certain frequency , the medium polarization orientation of dipoles in a similar frequency of changes in the transformation process, due to intermolecular friction , collision and generate heat . Frequency electric field changes the faster the frequency of dipole rotation sooner , the thermal effect is stronger, while the microwave band electromagnetic frequencies up to 108 orders of magnitude , so the microwave radiation, the heat generated by the dipole rotation is considerable, so that the system in a very short time to reach the high temperatures . Dipole rotation generated by the heating efficiency depends on the dielectric relaxation time , temperature and viscosity.
    Ionic conduction mechanism is the dissociation of ions in an electric field generated conductive movement hindered due to media on the ion thermal effects arising . Heating efficiency resulting ionic conductivity depends on the size of the ion concentration , the charge amount and conductivity .
    The use of conventional heating means for conduction and convection , the first heating vessel , the heat conductive container to the surface , then the heat transfer from the surface to the object interior , thereby obtaining thermal equilibrium condition, and therefore the heating takes a long time . The heated environment is generally impossible strictly adiabatic closed prolonged heating , it may emit a lot of heat to the environment . The microwave heating is usually carried out in a fully closed state , the microwave power to penetrate inside the object light , change in time for the heat to avoid the prolonged heating in the process of heat loss , and can be carried out inside and outside the object , " whole" heat and, therefore, compared to traditional heating , microwave heating with high efficiency, speed, and low energy consumption .