电场作用下建筑材料中有机挥发物迁移过程的研究

Study on the emission of volatile organic compounds in the buildings is great valueable for air quality control. The coupled migration process of volatile organic compounds in building materials with the high-voltage electric fields is mainly studied in this project. The driving forces of coupled heat and volatile organic compounds migration in building materials with the high-voltage electric fields are firstly analyzed based on the method of non-equilibrium thermodynamics. The phenomenological equations of migration with gradients of electric potential, temperature and concentration of volatile organic compounds are estableshed. And the migration coefficients in the phenomenological equation are analyzed. The pore structure and morphological characteristics in porous building materials are studied based on the experiments of scanning electron microscopy, information on image processing technology and the theory fractal geometry. The effects of pore structure, pore volume of morphological characteristics and indoor environmental conditions on these coupled migration coefficient are studied. The fractal network channel model on the migration of volatile organic compounds in porous building materials is established. The Lattice-Boltzmann method (LBM) is used to simulate the coupled migration process of heat and volatile organic compounds in building materials. The experimental study on coupled migration process of volatile organic compounds in building materials with high-voltage electric fields is carried out. The effects of coupled heat, strength and direction of high-voltage electric fields on the migration of volatile organic compounds are experimentally studied.

建筑物中有机挥发物散发的研究对空气品质的控制具有重要价值。本申请项目主要研究在高压电场作用下建筑材料中有机挥发物的耦合迁移过程。首先基于非平衡热力学方法，分析在高压电场作用下建筑材料中热、有机挥发物耦合迁移的驱动力，建立在电势、温度和有机挥发物浓度梯度下迁移的唯像方程，分析各唯像方程中迁移系数；以电镜扫描实验与信息图像处理技术为基础，基于分形几何理论，研究多孔建筑材料中的孔隙结构与形态特征，研究建筑材料的孔隙结构、孔隙体积形态特征以及室内环境条件对耦合迁移各系数的影响；建立多孔建筑材料中有机挥发物迁移的分形网络通道模型，运用格子-玻尔兹曼方法（LBM）模拟研究建筑材料中热和有机挥发物耦合迁移过程。实验研究高压电场作用下建筑材料中有机挥发物耦合迁移过程，对不同高压电场强度、方向以及与热耦合作用下建筑材料中有机挥发物迁移进行实验研究。

建筑物中有机挥发物散发规律的研究对空气品质优化控制具有重要价值。本项目主要结合实验和理论研究方法,研究高压电场作用下建筑材料中有机挥发物的耦合迁移过程。首先，基于非平衡热力学方法，分析环境温度对建材有机挥发物迁移特性的影响。采用密度泛函理论模拟研究了外加静电场对以甲醛为代表的有机挥发物分子与建材纤维素分子吸附的影响机制。结果表明：外加静电场会改变纤维素和甲醛所构成吸附分子对后的吸附能的大小，从而影响甲醛的吸附特性；随着电场强度的增强，纤维素对甲醛的吸附能力减小。引入分形理论，发展了各项异性多孔结构的分形重构方法，用以重构多孔建筑材料的三维孔隙结构。发展了基于混合动力学的格子-Boltzmann模型，对二维和三维分形重构多孔介质孔隙结构内VOCs扩散迁移行为进行系统的模拟研究。在此基础上，结合分子模拟研究的结果，对静电场影响下VOCs在多孔建材孔隙内的迁移过程进行研究，通过研究发现外加静电场后因为VOCs脱附特性的改变会造成迁移初期孔隙内有较高的VOCs浓度，VOCs向孔隙外部的散发速度增加。研究结果从微观的角度解释了建材内的VOCs迁移以及静电场的影响机理。基于足迹法的基本原理，试验研究了小型环境舱内温度和外加静电场场强对刨花板VOCs散发关键参数的影响。试验结果表明，外加静电场对甲醛散发关键参数中的吸附分配系数影响较为明显，外加静电场场强与VOCs吸附分配系数之间呈现出明显的指数函数关系。该项目研究揭示了多物理场作用下建材VOCs的迁移散发机理，为发展建材内VOCs的有效脱除方法提供了指导。