多物理场耦合仿真对流在微波加热中的作用机理研究

Multiphysics coupled simulation to study the mechanism of convection in microwave heating

摘要:

微波炉加热水或者牛奶等液态食物时，在温度横向分布向不均匀的同时会出现比较明显的纵向不均匀，其特点是上部的温度高于底部温度，最终导致微波加热不充分.为了分析温度纵向不均匀性产生的作用机理，以进一步提高加热效果，本文使用了多物理场仿真软件，模拟了微波与常规电热器等底部加热方式加热一杯水时温度变化的情况.通过分析对流现象对电场与温度分布的影响，我们发现：由于微波加热的不均匀导致对流只发生在局部区域，无法形成类似于电热器底部加热方式中自下而上的对流，最终导致了温度分层的现象.

Abstract:

When a microwave oven heats liquid foods such as water or milk, there is a phenomenon of longitudinal and transverse temperature inhomogeneity because of the nonuniform of electromagnetic field distribution. To explore the mechanism for the phenomenon, the multiphysics simulation software was used to simulate the temperature change when heating a cup of water from bottom by microwave and conventional electric heaters. By analyzing the effect of the convection on the distribution of electric field and temperature, it came to conclusion that convection only occurs in the local area owing to nonuniform of microwave heating, different from the traditional method where it forms a bottomup onvection, which eventually leads to the temperature delamination.