桉木冷冻干燥和常规干燥对比研究  

Comparative Study on Freeze Drying and Conventional Drying of Eucalyptus Wood

作　　者：李明侠 LI Ming-xia(College of Furnishings and Industrial Design,Nanjing Forestry University,Nanjing Jiangsu 210037,China)

机构地区：[1]南京林业大学家居与工业设计学院,江苏南京210037

出　　处：《林业机械与木工设备》2020年第11期32-35,共4页Forestry Machinery & Woodworking Equipment

摘　　要：桉木速生材是极具开发潜力的人工林木材,但常规干燥过程中因毛细管张力引起皱缩问题严重降低其应用价值。木材冷冻干燥过程中内部的水由冰直接升华为水蒸气,没有毛细管张力,可以防止木材产生皱缩。以尾巨桉(Eucalyptus urophylla×E.grandis)为试材,对其进行冷冻和常规干燥并对比干燥结果。研究表明:冷冻干燥速度大于常规干燥,尤其在纤维饱和点(FSP)以下;干燥过程各含水率阶段,冷冻干燥的含水率梯度大于常规干燥,但其干燥应力及干缩率都小于常规干燥;冷冻干燥导致的桉木皱缩很小,在预防木材皱缩上具有开发潜力。Fast growing Eucalyptus wood is potential plantation timber,but its application value is seriously cut due to the collapse caused by capillary tension during conventional drying.During freeze drying,water in wood is sublimated directly from ice to vapor without capillary tension,which can prevent wood from collapse.In this paper,Eucalyptus urophylla×E.grandis wood,as testpiece,was subjected to freeze and conventional drying and the test results were compared.The results showed that freeze drying rate was higher than that of conventional drying,especially below the fiber saturation point(FSP).The moisture content gradient of freeze drying was higher than that of conventional drying at each moisture stage in the drying process,but its drying stress and shrinkage rate are lower than those of conventional drying;the collapse of eucalyptus after freeze drying was very small,so freeze drying has the potential to prevent the collapse of eucalyptus.

关 键 词：桉木 冷冻干燥 常规干燥 干燥应力 皱缩 

分 类 号：TS664[轻工技术与工程]