竹材热压干燥过程中的水分迁移特性研究

研究了竹材热压干燥过程中的水分迁移特性.结果表明:在整个干燥过程中,前期含水率降低较快,后期含水率降低较慢.竹材平均干燥速度与次表层竹材的干燥速度相近;在含水率较高的干燥初期,水分迁移的阻力在竹材表面,水分迁移主要靠毛细管张力作用;在含水率较低的干燥后期,水分迁移的阻力在竹材内部,水分迁移主要以扩散方式进行,干燥速度取决于木材内部水分移动的速度.竹材热压干燥过程中的水分移动,主要受温度梯度和含水率梯度的共同作用.

A Study of Water Movement during the Process of Hot-press Drying of Bamboo Timber

The characteristic of water movement during the process of hot-press drying of bamboo timber was studied.The results show that the drop rate of moisture content(M.C) at the early stage of drying is faster than that of the late stage in the whole drying process.The average drying rate of bamboo timber is near the drying rate of the second layer along a thickness direction.In the initial drying period,the resistance of moisture movement in bamboo timber is on its surfaces due to a rather high moisture content,and therefore,the moisture movement is by the function of capillarity.In a later drying period,the resistance of moisture movement in wood is mainly centralized in the interior of the bamboo timber due to a rather low moisture content,and therefore,the moisture movement is mainly through the pattern of diffusion.The moisture movement was mainly controlled by both temperature gradient and moisture gradient.