【摘要】 为了研究间歇加热干燥对干燥应力的缓解作用及不同间歇率(非加热阶段与循环周期之比)对干燥过程的影响,以24 h为1个循环周期,设定0、33%、66%3种间歇率对杨木锯材进行常规干燥。采用分层切片及图像解析等方法分析不同间歇加热干燥过程中的分层含水率、干燥速率、弹性应变的变化趋势以及干燥质量。结果表明:间歇加热干燥方式在减少加热时间的同时,平均干燥速率比理论值提高28.9%、44.12%。间歇加热干燥过程中含水率梯度随间歇率的增加而变小,木材内部水分下降趋于一致,干燥应力减小,3种间歇加热干燥锯材均达到二级标准。当含水率为92.8%～60.0%,选取间歇率为33%干燥处理;当含水率为60.0%～30.0%,选取间歇率为66%干燥处理;含水率30.0%以下,选取间歇率为0干燥处理的干燥效果最好。更多还原

【Abstract】 The experiment was conducted to explore the effect of intermittent heating drying on drying stress relieving, and the influence of different intermittent rates(the ratio of non-heating stage to cycle period) on the drying process. Taking 24 h as a cycle period, three intermittent rates of 0, 33%, and 66% were set to routinely dry poplar lumber. The variation trend of moisture content, drying rate, elastic strain and drying quality in different interval rate drying process were analyzed by slice and image analysis. As the heating time was reduced, the average drying rate was 28.9% and 44.12% higher than the theoretical value, and the energy consumption was saved from 10.17% to 13.56%. In the process of heating and drying with intermittent, the moisture content gradient decreased with the increased of intermittent heating and drying rate, the moisture content in the wood decreased uniformly, the drying stress decreased, and the three kinds of intermittent heating and drying timber all reached the secondary standard. When MC is 92.8%-60%, the intermittent rate of 33% is selected for drying treatment; when MC is 60%-30%, the intermittent rate of 66% is selected for drying treatment; when MC is below 30%, the intermittent rate of 0 is selected for drying treatment, and the drying effect is the best.更多还原