低循环风速下木材表层水分蒸发的试验研究

The Experimental Study of Moisture Evaporation from Wood Surface under Low Circulation Velocity

木材干燥过程中,介质循环速度是一个影响木材干燥的重要工艺参数.在木材各含水率阶段,通过试验分析研究不同介质循环速度对木材干燥速度的影响.结果表明,介质循环速度对干燥速度的影响显著,但其影响随木材含水率（MC）的降低而减弱.在低介质循环速度条件下,试件MC大于45％时,表现为木材干燥速度和木材含水率偏差（△MC）随循环风速的增加而增加,呈显著正相关关系;试件MC介于35％ ～ 45％之间时,正相关关系存在但不显著;试件MC小于35％时,干燥室内循环风速的大小不影响木材的干燥速度和木材含水率偏差（△MC）.对试件表层含水率分析,试件表层含水率大于25％时,试件表面循环风速对试件表层含水率的影响显著;试件表层含水率小于25％时,试件表面循环风速对试件表层含水率的影响很小,不同循环风速下试件表层含水率基本一样.

Medium circulation velocity is one of the very important process parameters that can affect wood drying. In this paper, it is to analyze the influence of medium circulation velocity on wood drying rate at different wood moisture content stages by experiment. Results showed that the influence of medium circulation velocity on wood drying rate was significant, but this influence tended to become weaker with the reduction of wood moisture content. Under the low medium circulation velocity, the wood drying rate and the moisture content error in the sample surface increased when the medium circulation velocity became higher and the wood moisture con- tent was greater than 45% , and showed a significant positive correlation; when the wood moisture content ranged between 35% and 45% , there was a positive correlation, but it was not significant; when the wood moisture content was less than 35%, medium cireu- lation velocity had no impacts on the wood drying rate and the moisture content error in the sample surface. When the moisture content of specimen surface layer was greater than 25% , the impact of medium circulation velocity of specimen surface layer on the moisture content of specimen surface layer was significant; when the specimen surface layer moisture content was less than 25% , the impact was very small and the moisture content of specimen surface layer remained constant at different medium circulation velocity.