马尾松木材微波干燥特性的研究

研究了马尾松Pinus massoniana木材微波干燥速度、温度梯度和含水率梯度随时间的变化规律。实验结果表明,微波连续干燥过程明显分为加速段、等速段和减速段3个阶段,等速段在整个干燥过程中占的比例最大。微波干燥过程中,温度的变化大致分为初期升温,等温和后期升温3个阶段,初期升温和等温阶段木材内温度分布比较均匀,后期升温阶段木材内的温差逐渐增大。微波干燥过程中,在整个横断面上,木材初含水率梯度没有被加大,而是被均匀化,甚至还出现木材表面含水率提高的情况。图6参10

Microwave drying properties of Pinus massoniana lumber

The variational regularity of drying rate,temperature and moisture distribution with time during wood microwave drying was studied.The objective is to provide the theoretic accordance for microwave drying technology.The results show that the continuous microwave drying process can be divided into three stages:accelerating(speed-up)stage,constant-speed stage and speed-down stage.The constant-speed stage occupied the largest proportion.In the microwave drying process,temperature change process can be divided into coming-up stage,isothermal stage,and late coming-up stage.The temperature inside of the lumber was even both in coming-up stage and isothermal stage,and in the latter coming-up stage,the wood temperature was increased,and so as the temperature difference.The original moisture content gradient was not raised but was averaged in the whole cross section,and the surface moisture content was increased.