木材微波预处理圆柱形谐振腔理论模拟与设计

Mathematical Simulation and Design of Cylindrical Cavity of Microwave Pretreatment Equipment Used for Wood Modification

基于麦克斯韦电磁场方程和木材传热传质机制,构建微波预处理过程中木材内电磁场分布及热质迁移模型,采用有限元分析软件（Comsol Multiphysics）模拟微波馈入方式及谐振腔半径对圆柱形谐振腔中木材内温度分布均匀性和微波能量利用效率的影响规律,获得优化的微波谐振腔型.结果表明：1）微波馈入方式和谐振腔半径对木材内温度分布均匀性和微波能量利用效率的影响显著;2）在本研究范围内,采用三微波口馈入方式加热时,木材横截面上的温度分布最均匀,且微波能量利用效率最高,达到87.48％;3）随着微波谐振腔半径的增加,木材内温度变异系数和能量利用效率整体呈现出先减小后增加的变化趋势,优化的谐振腔半径介于0.186 ～0.211 m之间.

Based on the Maxwell electromagnetic heat and mass transport and a electromagnetic field field equations and the heat and mass transfer mechanism of wood, a distribution model for wood microwave pretreatment were developed to simulate the effect of the microwave feeding mode and cylindrical resonant cavity radius on the temperature uniformity and microwave energy utilization efficiency using finite element analysis software （Comsol Muhiphysics ）, and the optimizational parameters for the cylindrical resonant cavity was achieved. The results showed that： 1 ） the effect of microwave feeding mode and the radius of the cylindrical resonant cavity on the temperature uniformity within wood and microwave energy utilization efficiency was significant. 2） Compared with the other microwave feeding mode, the temperature distribution uniformity within wood and microwave energy utilization efficiency was the highest （up to 87.48% ） when the microwave radiation with 3 waveguides feeding is used to heat wood. 3） The temperature coefficient variation and microwave energy utilization efficiency basically decreased and then increased with the increasing the radius of the cylindrical resonant cavity, and the optimizational radius for the cylindrical resonant cavity was in the range from 0. 186 m to 0.211 m.