木材中非等温水分迁移的研究

为研究微波真空等高强度干燥过程中，温度梯度对木材中水分迁移的影响程度，该文通过试验测定了封闭马尾松木材试件在短期温度梯度作用下，木材内部温度场和含水率场的分布，含水率梯度与温度梯度比值的大小（dM/dT）及其影响因素. 试验结果表明:在短期温度梯度的作用下，木材内部的水分会从热端向冷端迁移，使冷端的木材含水率高于热端，形成方向相反的温度梯度场和含水率梯度场，且dM/dT在0.9%/℃以下；木材内温度、初始含水率和作用时间是影响dM/dT的重要因素；随着木材温度和初始含水率的增加，木材中的dM/dT越大；随着作用时间的延长，木材中的dM/dT增加. 

Nonisothermal moisture movement in wood

In order to study the effect of temperature gradient on moisture movement during high intensive drying such as microwave_vacuum drying, the authors measured the temperature and moisture content profiles in sealed wood whose opposite faces were subjected to temperature gradient for a short time.Then the absolute value of the ratio of the moisture content gradient to the temperature gradient(dM/dT) was calculated. The initial moisture content, temperature range and experimental period are all important factors affecting the experiment. The results indicated that moisture fluxed into the wood from the warm surface to the cold one even if opposite faces of the sealed wood assembly were exposed continuously to different but constant temperatures for a short period, the moisture content in cold surface was higher than that in the warm face, the moisture content gradient opposite to the temperature gradient was established, and the dM/dT is below 0.9%/℃. Some factors, such as experimental time, temperature and initial moisture content in wood, had significant effects on dM/dT, which was found to increase with these factors.