A general model for analyzing single surface VOC emission characteristics from building materials and its application

Abstract

A new and generally applicable model for calculating the surface emissions of volatile organic compounds (VOCs) from single-layered, dry building materials and the VOC instantaneous distributions in the materials is developed. Different from the mass transfer-based models in the literature, the new model does not neglect the mass transfer resistance through the air phase boundary layer and does not assume that the initial VOC concentration distribution (C0) in the building materials is uniform. And this paper provides an analytical solution for this model. For the specific case that C0 is uniform, the proposed model is validated with experimental data. Using different distribution of initial VOC concentration in building materials, the influence of initial VOC concentration on VOC emission characteristics is clarified: the influence of initial distribution on emission characteristics decreases with increasing time. When time is less than tc (critical time of early stage), the influence is strong and should be considered. After that period, such influence can be neglected. tc is mainly influenced by L and D. For the long-term emission prediction cases that the material thickness is relatively small and the diffusion coefficient is relatively large (larger than 10−11 m2/s), it would be justified to neglect the effect of initial VOC concentration distribution on emission characteristics. The model would be useful to estimate the emission characteristics of building materials.