间歇和连续微波干燥对木材内蒸汽压力与温度变化的影响  

Variety of Vapor Pressure and Temperature in Wood during Intermittent and Continuous Microwave Drying

作　　者：刘志军[1] 张璧光[2] 刘智[1] 

机构地区：[1]河北农业大学林学院,保定071000 [2]北京林业大学材料科学与技术学院,北京100083

出　　处：《林业科学》2008年第7期68-72,共5页Scientia Silvae Sinicae

基　　金：国家自然科学基金资助项目(598760005)

摘　　要：对间歇和连续微波干燥过程中木材内部温度、蒸汽压力的变化以及二者相互关系进行探索。结果表明:木材在连续微波干燥过程中,温度的变化大致分为快速升温段、恒温段和后期升温段;微波辐射功率增加,升温速度加快,恒温段温度提高,时间缩短;内裂通常在高含水率木材高功率连续加热时出现;在木材温度上升到100℃之后,适当减少微波功率输入,或采用间歇输入微波能的方法可有效避免内裂的发生;炭化通常出现在木材干燥后期,适当控制木材中含水率,避免过低,减少微波能输入或采用间歇输入微波能的方法,可有效防止木材炭化。The study was conducted to investigate the variety of inner-temperature, vapor pressure and both relations during the progress of intermittent and continuous microwave drying. Results obtained are summarized as follows： during continuous microwave drying, there are three stages in the change of temperature（ rapid temperature-increasing stage, constant temperature stage and later temperature-increasing stage）. The higher the power is, the quicker the temperature increases. In the period of constant temperature stage, the higher the temperature is, the shorter the time is. As the high power was continuously applied to heat wood with high moisture content, inner cracking was found, which can be avoided by decreasing the power supply or using intermittent power supply after the temperature increased to lO0 ~C . Charring of wood was mainly found in final stage of drying, and the phenomenon of charring may be avoided by the methods of controlling and avoiding too low moisture contents of wood in the last stage, decreasing the power supply or using intermittent power supply.

关 键 词：干燥缺陷 能量 汽化 干燥速率 

分 类 号：S781.71[农业科学—木材科学与技术]