The thermal characteristics of the microwave
    Materials , and electrical properties is called a medium , electromagnetic waves are manifestations of government absorption characteristics .
    Medium on the performance of the microwave absorption properties in the microwave can penetrate the internal probe into the material , its depth and microwave wavelengths from the same order of magnitude , penetration into the material inside the material absorbs microwave energy is converted into heat for heating and tough material , forming a unique thermal material --- whole is heated material way . The so-called no humidity gradient heating , when the material of the table, the inner layer temperature almost. With the continuous evaporation of surface moisture of materials , materials in the surface layer temperature will be slightly lower than the surface temperature , the formation of a temperature gradient from the inside pointing outside , the heating process is accompanied by the vapor pressure of the direction of migration occurring direction of migration are consistent with the heat . According to the theory of drying , this heated state is highly conducive to poke the dry material . Thus , the microwave heating material has a uniform heating , thermal conversion efficiency is high , the advantages of the heating time is short . Heated by the microwave theory and practice indicate that , in the unit volume of microwave power consumed by the electric field strength of the premises and the square of the frequency and microwave dielectric properties of the material parameters of proportional
    Incidence of the microwave can be said to be " transparent" , because it absorbs the incident microwave energy is minimal. For example, poly vinyl material in the case of nitrogen this nature . However, the general material , such as food ingredients , usually contain a certain amount of water , which tp at about 0.15 and 0.20 a , the greater the value , means can strongly absorb microwave energy . Thus, if the entire material consisting of the dielectric properties of the various parts of different, microwave feeding of both species exhibit about heating characteristics selected . For example , food ingredients present in the structure managers, comprising different media wear component, they are affected by the degree of heating will be slightly different .
  Select Mom microwave heating phenomenon in tough foam material is heated favorable disadvantages . Microwave heating degree also by the microwave field strength distribution of the heater or material composition. For example , the heating of food , because of a concentrated electric field border segment may overheat charred . Measures need to be adjusted through the process hang .
    In another example, the microwave energy distribution within the heater , the material to be heated since the microwave dielectric properties of the metal characteristics of the heater housing , they render the microwave absorption maximum contrast. Therefore , most of the microwave energy is dissipated in the material is heated , while the heated air around the branch , or heat energy device small gold th member . Thus , the microwave heater , its case section from heat , completely different from the far infrared or steam heating , the heating furnace and tough material while heating the school status , the room temperature harsh environment . In other words , the microwave heating is energy efficient compared with them .
    Energy is also reflected in the above method requires heating of different warm-up time . Only the power microwave preheating time , during which time the microwave tube filament preheating , it does not require heating operation of the warm-up time , the output energy is absorbed by the material towards was heated to infrared heating, etc. , but way . They are simultaneously output energy materials and cold furnace absorption , Barbara will work to achieve the status of the energy in the output after some time job , this is what we mean when heated in a conventional warm-up time . Microwave energy heating immediately after the output resistance, and the working process does not require the addition of materials outside of the working parts to maintain heat energy loss , the microwave energy heating is another important aspect.
    Must see that microwave heating of the material as a whole state , save the conventional heating heat conduction time , as compared with conventional heating , heating the material at the same time under the heating effect is shorter . Heating time is short, clearly saving benefit . It can be said , evaluate whether a particular heating energy . Not only extremely pocket size device uses power , more profit is typically heated leather from OBJECTS thermal energy conversion efficiency , the material is heated and ready to change the red- energy ratio, and total heating time square and comprehensive evaluation of the foot . For society as the microwave energy should be a big misconception to completely negate the facts .
    Material during microwave heating temperature depends on the microwave output power state. That is, when the material is heated microwave radiation , microwave radiation when stopped , the material can not be microwave energy , the heating process stops immediately stopped , showing microwave heating thermal inertia characteristics. Heating heat penetration is small, indicating that with the microwave output power regulation , the material heated state ( such as temperature and lead ) can be ruthless nature to change. This state is very conducive to some occasions, the automatic control of production needs , it can be achieved through control of material heating rate , final temperature limit of the specific needs and other production processes , thus ensuring the consistency of the food production process conditions .
    The enthusiasm of other heating methods are larger, is not conducive to food processing control of process conditions . Problems were not mindful of this , the thermal inertia of different heating methods , causing the microwave process is unique , we can not cut the experience of the conventional heating process to treat microwave heating . We need to create a new microwave heating process .
    For the adjustable output microwave power transient and microwave heating , the material is heated so that the interior of the steam vapor pressure gradient effect counterattack migration rate in the outer region also has an adjustable resistance, under the control of suitable conditions to achieve the effects of expanded material Jiao . This is puffed food production principle .