真空介质条件对木材干燥速率及缺陷程度的影响

Influence of Vacuum Medium Condition on Drying Rate and Drying Defect

以尺寸规格为200mm×100mm×20mm的落叶松为试材,在干燥温度分别为60℃、80℃,绝对压力分别为0.02MPa,0.04MPa,0.06MPa和0.08MPa的真空条件下,通过对试件干燥速率及干燥缺陷的测量及对比分析,得到如下结论:同一绝对压力下,干燥温度为80℃时试材的干燥速率为60℃时的1.77～3.85倍,而且随着绝对压力的减小,倍数增大;干燥温度升高,木材纤维饱和点(FSP)以上的干燥速率增加率小于FSP以下的,且随绝对压力的减小而增大;干燥温度为60℃时,试材干燥速率及其增加率受绝对压力的影响均较小;随绝对压力的降低、温度的升高,木材缺陷的程度增大。

Larch lumbers with the dimension of 200mm ×100mm × 20mm are used as the experimental materials to find a correlation between drying rate and drying defects under the different absolute pressures of 0.02MPa, 0.04MPa, 0.06MPa and 0.08MPa and different temperatures of 60℃ and 80℃. Following conclusions are drawn： under the same absolute pressure, the drying rate of samples dried under 80℃ is 1.77-3.85 times as fast as that of samples under 60℃ and as the absolute pressure decreases,the drying rate increases; when the drying temperature increases, the increment speed of drying rate under the condition which the EMC is above FSP （fiber saturation point） in smaller than the condition which the EMC is under FSP, and the drying rate increases as the absolute pressure decreases; when the drying temperature is 60℃ ,the absolute pressure exerts relatively small influence on the drying rate and the increment speed of drying rate; the drying defect increases as the absolute pressure decreases or the dcying temperature increases.