“Non-Fickian” diffusion of wood moisture refers to the unexplained anomalous behaviour of water vapour sorption in wood. The depression of moisture diffusion rates in thin sections of wood tissue during moisture content change at high relative humidity is one of the least-understood aspects of “non-Fickian” diffusion. In a previous work, a rate-limiting effect by two cooperative couplings of moisture and heat transfer, was shown to generate some signature features of “non-Fickian” diffusion. The present work aims to heuristically study the simultaneous action of this thermal rate-limiting effect and intrinsic slow relaxation processes in wood. Using an analytical non-geometrical model, exact solutions are obtained which show that the thermal rate-limiting effect acts directly and equally on diffusion and all relaxation processes, effectively time-stretching the entire dynamic wood moisture response. The magnitude of the time-scaling effect is proportional to the coupling strength between heat and mass transfer, which increases progressively with the relative humidity.

中文翻译：

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木材含水量变化过程中热交换与慢弛豫过程相互作用的启发式研究

木材水分的“非菲克式”扩散是指木材中水蒸气吸附的无法解释的异常行为。在高相对湿度下水分含量变化期间，木材组织薄片中水分扩散速率的降低是“非菲克式”扩散中最难理解的方面之一。在先前的工作中，通过水分和热传递的两个协同耦合产生的限速作用被证明会产生“非菲克”扩散的一些特征。目前的工作旨在启发性地研究这种热速率限制效应和木材固有的缓慢弛豫过程的同时作用。使用解析非几何模型，可以获得精确的解，这些解表明，热速率限制效应直接且同等地作用于扩散和所有弛豫过程，有效地拉伸整个动态木材的水分响应时间。时间缩放效应的大小与传热和传质之间的耦合强度成正比，并且随着相对湿度的增加而逐渐增加。