建材VOC散发过程模拟与传质参数测定新方法

建材中挥发性有机化合物(VOC)的散发是一个复杂传质过程。为准确把握传质特性,首先建立了一套描述干建材散发行为的显性完全解析模型,适用于模拟对人体最不利的无换气情况;代入有关文献中的传质参数预测了环境舱浓度,与文献中对应的实验数据及数值算法预测值吻合良好。然后基于对模型的分析提出一套简便快捷的实验方法,能够利用不同VOC背景值下干建材在密闭舱中散发的平衡浓度或逐时浓度,求取预测散发过程的4个重要的传质参数:可散发浓度C₀、扩散系数D、分配系数K和对流传质系数h_m;实验部分测算了两类密度板中甲醛散发的C₀、D、K、h_m,代入数值算法预测了密闭舱和直流舱的环境舱浓度,与实验数据吻合良好。该套模型和测定方法能够应用于建材散发的模拟研究。

New method for simulation of VOC emission from building materials and measurement of mass transfer parameters

Emission of volatile organic compounds (VOC) from building materials is a complex process of mass transfer.To have a clear picture of mass transfer characteristics, this paper first established an explicitly fully analytical model describing VOC emission behavior from dry building materials, which is applicable to emission simulation in static chamber that is most unfavorable to human health.The VOC concentration in the chamber predicted based on the mass transfer parameters in literature is in good agreement with corresponding experimental data and numerical calculation in literature.Based on this model, an experimental method is proposed for convenient, rapid and simultaneous measurement of four important mass transfer parameters for VOC emission prediction(emittable concentration C₀, diffusion coefficient D, partition coefficient K and convection mass transfer coefficient h_m) by making use of emission equilibrium or process concentration in a static chamber at a series of background concentrations. With the values of C₀, D, K and h_m for formaldehyde emission mass transfer obtained experimentally from two different medium density fiberboards, the numerically predicted results of VOC concentration in either static or dynamic chamber are coincident with experimental data.The model and method are accurate enough for emission simulation of building materials.