基于干燥理论的热功能织物火场下水分迁移机理及分形多尺度传输模型

Heat and moisture transfer through fibrous porous fabric under fire and high temperature condition underlie rapid drying process by means of intense heating. A heat and moisture transfer model for fabric can be proposed based on the mechanism of heat-mass transport during drying process for thermal engineering.This application will make that protective clothing play the most important role and protect firefighters and others workers from thermal hazards under intense heat flux. This has become a new cross research area between heat-mass transfer and personal safety protection field. Firstyly, this project analyzes the moisture movement mechanisms within clothing material under intense convective and radiant heat flux by using 3D tomography technique. Multi-scale geometry structural model is proposed in the project. Non-linear variation laws for fabric pore structure is then investigated experimentally during drying and the drying shrinkage process of fabric is comprehensively characterized in terms of fractal theory. The fractal dimension variation law is used to state quantitatively variation of thermal transport parameters during fabric drying. Based on the above descriptions, an improved heat and moisture transfer model for clothing materials has been proposed in the project. Simulataneously, yarns structural area parameters are introduced into the model and the extinction law for radiant heat flux in the internal region of fabric or yarn is discussed in detail. The theoretical research results can be applied to heat-moisture ergonomics design for emergency protective clothing. The methods proposed in the project will also help to establish the theoretical basis for the characteristics of moisture movement and energy-saving drying technology.

火场高温环境下纤维多孔织物热湿传递表现为强加热方式的快速干燥过程。利用干燥过程热质传输机理构建织物传热传湿模型对热功能服装进行热设计，使服装在火灾环境中发挥最大作用，保障作业人员的安全，形成传热传质学与个体安全防护学科交叉领域新的研究课题。本项目首先拟采用3维断层扫描成像技术分析含湿服装材料在强对流辐射热作用下的湿分迁移特性；然后构建了机织物多尺度几何结构模型，实验研究织物干燥过程孔隙结构非线性变化规律，借助分形理论对织物干燥收缩变形过程进行全面表征，运用干燥分形维数变化的规律来描述织物输运物性参数非线性定量变化，以此构建了含湿服装材料热湿传递模型；同时，在模型中引入纱线结构区域参数，讨论辐射热源在织物内纱线中渗透衰减规律；从而可以利用热质模型对热功能防护服装进行热湿工效优化设计。此项目的研究为含湿多孔介质水分迁移特性及干燥节能技术提供一定的理论基础。

火场等模拟高温环境下纤维多孔织物热湿传递表现为强加热方式的快速干燥过程。利用干燥过程热质传输机理构建织物传热传湿模型对热功能服装进行热设计，使服装在火灾环境中发挥最大作用，保障作业人员的安全，形成传热传质学与个体安全防护学科交叉领域新的研究课题。本项目首先利用低场核磁共振（LF-NMR）成像无损检测技术分析含湿服装材料在热辐射作用后的湿分迁移特性，作为后续项目构建模型的质量守恒方程的依据；利用不同尺度的实验分析纤维织物在高温作用下的水分蒸发过程，获得小规模尺度(Bench scale)及微观尺度下（Micro-scale）的织物干燥动力学模型，并计算了不同尺度下的湿扩散系数及表观活化能；以上述结果与结论作为构建含湿服装材料热湿输运模型的依据，分两种情况分别建立了低含湿服装材料与高含湿服装材料在高温热辐射作用下的热质传输模型，利用模型开展织物参数设计；同时，在构建模型过程中研究了湿态织物的热传输参数变化规律，包括织物导热系数与含水率变化关系的串并联复合结构模型，利用热质模型并结合热属性参数研究结论可以对热功能防护服装进行热湿工效优化设计。此项目的研究为含湿多孔介质水分迁移特性及干燥节能技术提供一定的理论基础。