Material Microwave Heating Computer Simulation Study

Microwave heating is a method by microwave into the inner material to produce a volume warming. Having characteristics of fast heating, high efficiency, easy to control of the heating system, especially for solid heating. However, due to the microwave electromagnetic field have relate of microwave dielectric properties and temperature, the temperature measurement and control of microwave field is not only a technical problem of microwave applications, but also an important research topic in microwave applications.In this paper, we research electromagnetism field distribution rule in microwave oven using computer numerical simulation, studied the influence of field distribution in the resonant cavity to the sample laying aside position, the temperature field distribution, and dielectric characteristic of medium in the microwave, obtained the dielectric loss of the medium and the change rule of the dielectrical loss along with the temperature. The results show that microwave heating's uniformity is decided in the uniformity of the electromagnetism field distribution in the microwave resonant cavity. After simulate the electromagnetic field distribution of rectangle resonant cavity TE101 and cylindrical resonant cavity TM010 and sphere resonant cavity concluded that the TE101 resonance pattern is more uniform than other resonant pattern in resonant cavity's electromagnetism field distribution, more likely to achieve uniform heating object; Compare with the cylinder and the sphere resonant cavity, the rectangular resonant cavity is more suitable for this microwave heating system. This paper firstly simulated microwave resonant cavity model with the feed port as same as the actual microwave oven,then studied the electric-field intensity and absorbed power of loading different medium (water and phosphogypsum), characteristics of electromagnetism field distribution and resonance frequency, quality factor, energy loss and so on. Meanwhile, with experimental study, uses methods of more glasses of water and starch tests electromagnetism field distribution in the actual microwave oven, its result coincided with the simulation.This paper also proposes a new method of simulation with fitting and thermal coefficient of microwave heat system, in order to research the dielectric properties of microwave medium. Measure the temperature in microwave resonant cavity using the automatic temperature measurement system and improved thermocouple of the laboratory. Measuring the heating and cooling temperature of objects more accurately, draw curve and fitting with software Origin, combined with the electric field strength received from simulation of microwave heating water, using heat conduction equation, we can obtained the dielectric loss of the medium and the change of the dielectrical loss along with the temperature.In short,this study indicate that the operating characteristics of microwave heating device, the dielectric properties of the media can use method of simulation with fitting to study, and the results is good.