Study Of The Thermal Conductivity About Wall Insulation Materials

In the current situation of energy and building energy efficiency, building energy efficiency is a major concern, but the hot and humid environment overall energy thermal conductivity of porous building materials and construction, and interior are closely related. To achieve low-energy buildings, low-carbon economy goals, in consideration of the heat and moisture properties of porous materials premise rational design envelope is particularly important. More than 50 percent of industrial insulation materials and intermediate products grainy, among solid- gas two-phase particles of porous materials based on solid- predict the thermal conductivity of the gas two-phase particles in a porous material moisture condition, yet see the relevant literature is given.Therefore, the basis of domestic and foreign effective thermal conductivity of porous material research, will analyze the theoretical and experimental study of the combination of a variety of different density polystyrene board(EPS), extruded plate(XPS), polyurethane(PU) and phenolic resin(PF) as test subjects, conducted research,and gives its prediction model thermal conductivity.(1) The main basic research include:1. Determination of the typical use of solid density method- two-phase gas-particle porosity of the porous material; and the use of domestic and experimental data fit the sample being tested by gas, the thermal conductivity of pure solid phase material;2. The system introduced testing methods effective thermal conductivity of porous material, Introduces transient hot-wire method and sample at absolute dry state effective thermal conductivity measurement;3. The density of the sample were different moisture, put wet performance studies,has been absorbing different materials, put the wet variation; and to study the relationship between moisture content and its thermal conductivity of porous material,fit its function;4. On the basis of experimental data prediction model domestic and foreign scholars have been measured with a porous material on theoretical analysis and correction, predictive model proposed new thermal conductivity;5. Establish a porous material to calculate the effective thermal conductivity model in a non-wet saturation, and contrast with the experimental analysis.(2) The results show that:1. Within the scope of porosity testing, the effective thermal conductivity with increasing porosity of the material decreases;2. EPS board, XPS board moisture absorption process, PU board and PF board four kinds of materials into three phases: rapid absorption phase, more stable phase moisture, moisture stabilization phase; desorption process is divided into two cases: a species are put off quickly after wet wet flatten, such as EPS board, PU board; the other is relatively mild throughout the desorption process, there is no rapid desorption phenomena, such as XPS board, PF board;3. As the water content increases, the thermal conductivity of the porous material is increasing; different densities of the same material when it reaches the saturated moisture absorption state, its saturation water content increases with decreasing density;4. The four materials in the absolute dry state, thermal conductivity relative error ellipsoid model predictions and experimental values of less than 3.5%; moisture in the state, the relative error of the prediction model and experimental values of less than 5%,to prove the accuracy of the ellipsoid model.