An improved mass transfer based model for analyzing VOC emissions from building materials

An improved generally applicable model for calculating the surface emissions of volatile organic compounds (VOCs) from building materials and the VOC instantaneous distributions in materials is developed. Differing from the mass transfer based models in the literature, it does not neglect the mass transfer resistance through the air phase boundary layer. The results of using the presented model are validated with the experiments in the literature. By normalizing the model, factors of influencing the surface emissions of VOCs from building material are clarified and the influences are quantitatively analyzed. It is found that the dimensionless emission rate of VOCs is just a function of Bim (the Biot number for mass transfer)/K (the partition coefficient) and Fom (the Fourier number for mass transfer), which summarizes the general surface emission characteristics of VOCs from building materials and provides the basis for fitting experimental data to formulate empirical correlations of VOC emissions. Based upon the model and the analysis, the applicable condition of the famous Little model is presented.