Study On The Emission Characteristics Of Dry Building Materials And Its Measuring Method

Dry materials (such as carpet, PVC, wood products, etc) can emit a variety of volatile organic compounds (VOCs), which are recognized as major problems affecting indoor air quality (IAQ) in China. The emission characteristics of dry materials include the initial VOC concentration (C0), the partition coefficient (K) and the diffusion coefficient (D), which is important to know the VOC emission of dry materials under various conditions.The thesis covers five chapters.Chapter one introduces the research significance. At present, one-though chambers are widely used to measure the emission characteristics, but they are mostly time-consuming. The influence of VOC initial distribution in dry materials is not considered, and the errors of the measurement are not analyzed. The main objective of this thesis is to develop a quick, simple and precise measuring method, and to measure the common building materials to determine their emission characteristics.In chapter two, C-history method was developed to measure the VOC emission characteristics of dry materials in an air-tight chamber, which is quite different from the traditional methods. The VOC is injected into the air-tight chamber with building materials inside, and the VOC concentration (C-history) is measured till the VOC concentration doesn't change. The partition coefficient (K) can be confirmed by the VOC initial concentration in building materials and the balance concentration in the chamber. According to the VOC emission model, the diffusion coefficients (D) can be determined by using the least-squares method to analyze the VOC concentration curves.The measuring equipments and the experiment approach were introduced in chapter three. The influences of experiment conditions are discussed, including the pre-disposal of the building materials, the sealed time and loading factor. Proper test condition is confirmed. The CH2O emission characteristics of five common building materials are measured. The repeated experiment results show the rationality of this test method.Chapter four discusses the influence of some experiment factors to the result, including the convective mass transfer coefficient (hm), the assumption that initial distribution of VOC concentration in building materials is uniform and the assumption that the VOC concentration in the surface of building materials equals to the initial VOC average concentrations when equilibrium. The condition that the convective mass transfer can be ignored is developed. The measuring error is analyzed. The results are compared with the one-through and air-tight emission experiments and they fit quite well. The measuring results and the analysis show that C-history method is a quick, simple measuring method with a precision which can satisfy the applicationChapter five summarizes the conclusions of this research and puts forward the future work.