Research On Prediction, Measurement And Control Of VOC Emissions From Dry Building Materials

VOCs (Volatile Organic Compounds) from dry building materials are one of the main causes resulting in poor IAQ (Indoor Air Quality). Therefore, it is important to study prediction, measurement and control of VOC emissions from dry building materials for improving IAQ. Accordingly, this thesis makes the following researches: (1) VOC emission model of dry building materials; (2) determination of key characteristic parameters of the model: diffusion coefficient, partition coefficient and initial mobile VOC concentration within dry building matareials; (3) the correlation between partition coefficients and properties of VOCs; (4) analysis on some methods for lowering VOC emissions from dry building materials.Firstly, an analytical model is proposed for predicting VOC emissions from dry multi-layer building materials with double emission surfaces and inner sources or sinks, which is validated by experimental data. Based on the model, (1) Kuamr and Little's double-layer model is analyzed and it shows that relative error of nomorlized emission factor predicted by Kumar and Little's model is no more than 10% when Bim≥100 and Fom≥0.002; (2) application condition of decay model, the most popular empiric model for VOC emissions from dry building materials, is obtained as Fom≥0.2; (3) secondary VOC emissions from dry building materials are also discussed.Secondly, multi sorption equilibrium regression method (MSER method) is presented to estimate the key parameters of the presented model including the partition coefficient, mass diffusion coefficient and the initial mobile VOC concentration. The method is simple, time-saving and can satisfy engineering accuracy.Thirdly, for conveniently determining partition coefficients, according to adsorption potential theory the correlation between partition coefficients and liquid molar volume is brought out, which is validated and modified by the experimental data. Based upon the correlation, partition coefficients of other VOCs with the same bond and function group as the typical VOCs can be estimated after partion coefficients of some typical series VOCs in the building materials are measured and the constant of the correlation is determined,.Finally, by means of the foregoing VOC emission model, four methods to weaken VOC emissions from building materials are theoretically analyzed, including substrate layer to adsorb and fix the VOC in dry building materials, barrier layer to impede VOC emissions from dry building materials, additive to slow up VOC emissions and catalyzer to eliminate VOC in dry building materials. And characteristics parameters respectively reflecting effects of barrier layer and additive, Rm and Sm, are proposed. Those provide theory for controlling VOC emissions from dry building materials.