(1.Energy-saving Office of Wall Reconstruction Building in Harbin, Heilongjiang Province, Harbin 150018; 2.Residential Engineering Company of Raohe County, Heilongjiang Province, Shuangyashan 155700) Wet transfer characteristics of dry-powder and emulsion polymer thermal insulation mortar in exterior insulation system Calculation. The results show that the partial pressure of water vapour on the inner surface of the thermal bridge envelope structure using the thermal insulation mortar is lower than the saturated vapor pressure at the corresponding temperature, and the water vapor does not condense on the inner surface of the envelope structure, indicating that the selected materials are reasonable. The structural layer is properly arranged to meet the needs of the project.
Polystyrene particles thermal insulation mortar; Steam pressure; Moisture transfer calculation Polystyrene particles Thermal insulation Mortar is mixed with polyphenylene granules and checked for moisture condensation inside the envelope structure. In this paper, a composite material with a certain thermal conductivity obtained by polyphenylene granules is obtained. Thermal insulation materials such as polyphenylene granules thermal insulation mortar and polystyrene board can be combined to further improve the thermal insulation performance of the external thermal insulation system. At the same time, it is suitable for the construction of a relatively complex or irregular basic part, such as a round arch, an oblique triangle, and flatness. The low wall area is particularly important in Harbin, where European architecture is more common. Based on the polyphenylene granule thermal insulation mortar technology, we developed and produced a dry powder type and emulsion type polymer mortar (PMM), which was mixed with polyphenylene granules to make polymer thermal insulation mortar.
The moisture transfer characteristics of the external thermal insulation structural material are very important because the steam passes through the envelope structure. If a material layer with large vapor permeability is encountered, the water vapor cannot easily pass through, and condensation will occur inside the envelope structure. The condensation phenomenon will lead to serious deterioration of the performance of the insulation layer and greatly reduce the life of the insulation system. Therefore, the thermal construction design rules for civil buildings clearly specify that the heating building envelope structure should adopt moisture-proof design, and the thermal insulation mortar of the compound should be used in the external insulation system. Wet transfer characteristics are calculated to determine the moisture resistance of the material; H - total steam permeability resistance of the envelope structure (m2*h*Pa/g); ei - indoor air steam pressure (Pa); ee - outdoor air Steam partial pressure (Pa).
Since the vapor permeation resistance of the air boundary layer near the inside and outside surfaces of the envelope structure is very small compared with the permeation resistance of the structural material layer, it is negligible when calculating the total vapor permeability resistance. In this way, the partial pressure of water vapor inside and outside the envelope can be approximated as ei*ee. The partial pressure of water vapor at the inner interface of any layer of the envelope can be calculated by the following equation:
2 Internal Condensation of the Enclosure The determination of water vapour passes through the envelope structure. When a layer of material with large vapor permeability is encountered, water vapour cannot pass through, and condensation will occur inside the envelope. Judging whether the interior of the envelope structure will condense can be performed as follows: According to the temperature and humidity of the indoor and outdoor air, determine the vapor pressure ei and e and then press the following styrofoam slag and slag filling the total heating period The calculation method for the amount of condensation is: the condensation intensity at the interface between c and c; the formula for calculating the weight and humidity increment of the material in the heat insulation layer during the heating period is: P―density of the insulation material (kg/m3); 5 the required steam penetration inside the condensation interface If the amount of steam condensation in the envelope is calculated to exceed the allowable increase in humidity of the insulation material, not only the insulation performance of the material will decrease, but excessive moisture will not evaporate sufficiently during the non-heating period, resulting in accumulation year by year and passing through freezing and thawing. The protection structure has a great destructive effect and affects the durability of the envelope structure. This situation must be prevented in the design, which requires a certain steam penetration resistance at the envelope of the inner side of the condensation interface.
e―Indoor steam pressure, determined according to the indoor calculated temperature and relative humidity in the heating period (Pa); ee—the partial pressure of outdoor air vapor (determined according to the average outdoor air temperature and relative humidity in the heating period) (Pa); Ec—condensation interface Saturated water vapor partial pressure (Pa) corresponding to the interface temperature; He-the vapor permeability resistance to the outside of the condensing interface (m2*h*Pa/g)P - Dry density of the insulating material (kg/m3); §1 Thermal insulation thickness (m).
6 Wet-Transmitting Calculation Examples We use the water-vapor-permeation values ​​of the materials of the external thermal insulation system of the polymer thermal insulation mortar to determine the internal condensation of the envelope. According to the calculation results of the temperature of each part of the envelope structure, the corresponding saturation vapor pressure can be obtained. E. The relative humidity in the winter heating room in Beijing is 30%-60%, the calculation is 60%, and the average outdoor relative humidity is 50%. The water vapor permeability coefficient of polyphenylene granule thermal insulation mortar and polymer modified mortar was measured by desiccant method. The water vapor permeability coefficients of the materials are shown in Table 2. Table 2 Water Vapor Permeability Coefficient of Material Material Type Water Vapor Permeability Coefficient Polyphenylene Brick wall base polymer modified mortar dry powder type emulsion type polyphenyl particle insulation mortar dry powder type emulsion type In the room temperature of 18 °C, relative humidity of 60%, the partial pressure of steam is 1237.5Pa; outdoor calculation temperature is - When the relative humidity is 50% at 9°C and the relative humidity is 50%, the partial pressure of water vapor is 142 Pa. Calculate the water vapor permeation resistance of each layer according to Equations (4) and (5). The results are shown in Table 3. Table 3 Materials according to Equation (3) Water Vapor Permeation Resistance (m2i>h*Pa/g) Polystyrene Particles Thermal Insulation Mortar Brick Wall Base Polystyrene Polymer Mortar Body Material Number 0.3 Number Shape Series Dry Powder Lotion Dry Powder Lotion Dry Powder Emulsion Number 0.3 Number Table 4 Each Protection structure interface layer water steaming Partial pressure (Pa) water vapor partial pressure polystyrene board (a) shape coefficient. 3 Polyphenylene powder dry powder type (c) Shape factor. 3 insulation mortar type (e) shape coefficient. 3 Table 5 Saturated vapor pressure of water vapor in each interface layer (Pa) Steam partial pressure (a) Body shape coefficient. 3 Polyphenylene powder dry powder type (c) Shape factor. 3 insulation mortar type (e) shape coefficient. 3 f) The coefficient of shape> 0.3 knots, the water vapor in the main part of the wall does not condense in the interior, which shows that the moisture permeability of the polystyrene heat-insulating mortar complies with the requirements. The material selection of the external insulation system is reasonable, and the structure layer is properly arranged to meet the engineering needs.
Different materials steam pressure
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