吸湿过程中木材的含水率及温度变化

为了探讨木材在水分吸着过程中的含水率、温度的变化，以尺寸20 mm(T)×20 mm(R)×2 mm(L)的杨木(Populus euramericana Cv.)为试材，利用自行研制的恒温箱、配合红外热像仪，考察了在30℃，从绝干→22%、47%和75% RH 3种相对湿度条件下吸湿过程中试材的含水率、温度变化及其顺纹方向上的温度梯度分布情况。结果表明：在吸湿初期，试材含水率迅速上升，其整体平均温度也明显升高2~5.5℃；随着吸湿过程的进行，木材含水率和整体平均温度逐渐趋向平衡；在顺纹方向上，试材的温度呈现出表面温度高、中间温度低的分布形态，表层与芯层之间的温度差在吸湿过程初期90 s内达到最大值，约为0.8℃，当达到吸湿平衡时二者之间的温差约降至0.02℃。

Moisture Content and Temperature Changes of Wood During Adsorption Processes

In order to study moisture content and temperature changes of wood during moisture sorption, adsorption processes of poplar (Populus euramericana Cv.) with size of 20 mm (T)×20 mm (R)×2 mm (L) were investigated from oven-dry state to three different relative humidity conditions of 22%, 47%, and 75% at 30℃. A self-designed temperature chamber was used and thermal images were taken at certain time intervals during the processes. The result showed that: at the beginning of adsorption process, moisture content of the specimens increased significantly, and their average temperatures rose 2-5.5℃ as well. Along with adsorption, the moisture content and average temperature of the specimens were gradually approaching the equilibrium state. The temperature for surface layer along the longitudinal direction of the specimens was higher than that for center layer, and the temperature difference between the surface and center reached the maximum value of 0.8℃ at the first 90 s of the adsorption process and eventually reduced to 0.02℃ at equilibrium state.