Moisture transport dynamics in wood during drying studied by long-wave near-infrared hyperspectral imaging
Moisture transport dynamics in wood during drying studied by long-wave near-infrared hyperspectral imaging
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DOI：
10.1007/s10570-021-04290-y
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发表时间：
2021-11
期刊：
影响因子：
5.7
通讯作者：
Te Ma;Genki Morita;T. Inagaki;S. Tsuchikawa
中科院分区：
文献类型：
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作者：
Te Ma;Genki Morita;T. Inagaki;S. Tsuchikawa
木材微观结构的复杂性给理解干燥过程中水分运动特性带来了困难。本文采用基于长波近红外高光谱成像（NIR-HSI）的快速高分辨率含水率（MC）制图方法，研究了不同样品长度（30 mm、60 mm和90 mm）和不同干燥温度（30 °C、60 °C和90 °C）的软木（日本扁柏）水分运移动态。本研究的观察结果如下：在约30 °C下缓慢干燥时，木材样品的次表面附近区域在干燥过程中倾向于具有比中心部分更高的MC，特别是在较长的木材样品的情况下。在较高温度下干燥，强结合水在表面区域出现得更早，这容易导致样品变形和开裂。总体而言，实验结果表明，毛细管效应可以发挥主要作用，在第一阶段的缓慢干燥在纤维水平，然后，之间的转移结合水和自由水可以发挥重要的动力源在第二干燥阶段。本研究为研究和模拟多孔材料和亲水性材料的干燥特性提供了依据。
The complexities of wood microstructure cause difficulties in understanding water movement characteristics during drying. Here, the water transport dynamics in softwood (Japanese cypress) with different sample lengths (30 mm, 60 mm, and 90 mm) and various drying temperatures (30 °C, 60 °C, and 90 °C) were studied using a rapid and high-resolution moisture content (MC) mapping method based on long-wave near-infrared hyperspectral imaging (NIR-HSI). The observations of this study are as follows: slow drying at approximately 30 °C, the area near the subsurface of the wood samples tends to have higher MC than the central parts during drying, especially in the case of longer wood samples. For drying at higher temperatures, strongly bonded water appeared at the surface areas much earlier, which could easily cause sample deformation and cracking. Overall, the experimental results suggest the capillary effects could play a major role at the first stage of slow drying at fiber level; then, the transfers between bound and free water could play a significant power source in the second drying stage. It is expected that this study will be of help in providing a basis to study and simulate the drying characteristics of cellular and hydrophilic materials.