微波场中加热水的模拟计算

Modeling Calculation of Heating Water in Microwave Field

微波环境下测温存在一些问题,借助数值模拟的方法可计算微波场中试样温度随加热时间的变化。计算过程中需考虑材料的介电常数随温度的变化。水的介电常数数据最完整,所以选水为研究对象,进行微波场中加热水的实验研究及数值计算。计算结果表明微波在炉腔内金属壁上全反射形成驻波。随着微波在水中的传播,其强度逐渐衰减,因此水表面的微波场最强。考虑水的介电常数随温度变化以及微波场在水中传播时的衰减等因素后,模拟计算出的水温随微波加热时间的变化与实验结果吻合较好。

In order to know the temperature of the sample heated in microwave field accurately and timely, numerical simulation was applied to calculate the temperature change of sample with microwave heating time. It was necessary to consider the permittivity dependence on temperature to calculate the temperature of the heated sample. Because the permittivity date of water was well known, water was chosen as heating and calculating sample under microwave irradiation. It was calculated that standing wave was formed because of the reflection of microwave on the stainless steel wall of the oven. The strength of microwave was attenuated with its propagating in the water. So microwave on the surface of water was most strong. When the factors of permittivity dependence on temperature, and microwave attenuation with propagating distance were considered, the results of experiment and simulation agreed well.