微波干燥中介质温度梯度与含水率变化关系的研究

Study on the Correlation of Temperature Gradient and Water Content Change in Microwave Drying

含水薄层多孔介质的微波干燥处理是实现长期保存的有效方法之一。本文推导了微波干燥含水薄层介质过程中温度梯度与含水率变化的关系,可以适用于多种不同材质的含水薄层多孔介质;利用多物理场仿真软件,建立了电磁场、温度场及速度场的耦合模型,仿真了薄层多孔介质在微波干燥过程中温度梯度与含水率变化的关联关系。选取黄豆作为薄层多孔介质样本进行微波干燥的实验,测量其在微波干燥过程中温度梯度变化和含水率变化的关系及不同干燥阶段对黄豆发芽率的影响。实验结果表明黄豆在微波干燥过程中,温度梯度与干燥程度存在固定关系,通过控制梯度趋于0时的干燥时间可以达到设定的干燥程度,并且对其发芽率影响较小。

Microwave drying of water-containing thin porous medium is one of the effective methods for its long-term preservation.The relationship between temperature gradient and water content change in microwave drying process is deduced,which can be used for different water-containing thin porous materials.Coupling models of electromagnetic field,temperature field and velocity field are established by using multi-physical field simulation software,and the correlation of temperature gradient and water content change in microwave drying process of water-containing thin porous medium is simulated.Soybean is selected for the microwave drying experiment.The correlation of temperature gradient change and water content change in microwave drying and the influence of different drying stages on soybean germination rate are measured.The experimental results show that there is a fixed relationship between the temperature gradient and the drying degree of soybean in microwave drying process.By controlling the drying time when the gradient approaches zero,the set drying degree can be achieved,and the germination rate is less affected.