Promoting the plastic door and window glass to ene

2022-08-06
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The low-carbon era promotes the development of plastic door and window glass in the direction of energy conservation and safety.

doors and windows are the weakest link in the handling process of hydraulic material testing machine in the whole building envelope

doors and windows are the weakest link in the whole building envelope in terms of heat insulation, heat preservation, sound insulation and safety. There are roughly three ways for heat loss of doors and windows:

1. Heat conduction between door and window frames and glass

2。 Air infiltration heat exchange between door and window frames and fans, between fans and glass, and between frames and walls

3。 Thermal radiation of window glass

according to relevant data, the energy loss through doors and windows accounts for about 50% of the building, and the energy loss through glass accounts for about 75% of the doors and windows. Under certain conditions, the heat radiation and conduction of glass are the dominant factors leading to indoor energy loss

as the heat transfer performance of plastic is 1/1250 of that of aluminum, the heat transfer coefficient of single glass plastic window is 4. 3~4。 6%w/m2k is equivalent to the heat transfer effect of double glass aluminum window, indicating that the role of window frame and leaf materials in window heat transfer cannot be underestimated, but the proportion of frame and leaf materials in the heat transfer area of the whole window is small after all. The heat transfer coefficient of single glass plastic window only reaches the performance index of building energy-saving doors and windows in some areas of southern China at this stage. The distance from Beijing to realize the energy saving policy of 65% and the heat transfer coefficient of doors and windows is 2. 8w/m2k index and different heating areas 4. 0~2。 The 0%w/m2k index gap is even greater. Therefore, with the continuous development of national building energy conservation work, using energy-saving glass to effectively improve the thermal performance of door and window glass will become the main target of door and window energy conservation

in recent years, there are more and more glass varieties to choose from. The traditional functions of lighting, wind protection, rain protection and enclosure have developed into modern composite functions such as heat insulation, heat preservation, safety, noise prevention and decoration. The glass used for energy saving mainly includes heat absorbing glass, coated glass after 1980s, double-layer (or three-layer) glass, hollow glass, vacuum glass, etc. Coated glass is divided into Anti radiation glass, low radiation film glass and multi-functional coated glass

glass is a non-metallic material, although its heat transfer coefficient is only 0. 8~1。 0w/m · K, as the glass is generally 3~8mm thick, its own thermal resistance is very small, and the heat transfer is still very considerable for the area accounting for about 65~75% of the window. Glass energy saving is mainly reflected in two aspects: thermal insulation: thermal insulation means to control the loss of indoor heat energy to the outside by reducing the characteristics of glass heat conduction and convection. Such as hollow glass and vacuum glass; Heat insulation is to control the conduction of outdoor heat energy to the interior by improving the shielding characteristics of glass to solar thermal radiation. Such as heat absorption, heat reflection, low radiation glass, etc. Now we will briefly introduce the above glass properties:

1, double-layer (or three-layer) glass

2, insulating glass is developed from two-layer (or three-layer) glass

3, heat absorbing glass

4, heat reflective glass

5, low radiation glass and multi-functional coated glass

low radiation glass (ILE) and multi-functional coated glass (IMF), also known as insulating glass, have the maximum solar transmittance and the minimum reflection coefficient. It can allow 80% of visible light to enter the room and be absorbed by objects, and retain more than 90% of the long waves radiated by indoor objects in the room, greatly improving the energy utilization rate. At the same time, it can selectively transfer solar energy and transfer most of the heat radiation energy into the room, which can play a role in heat preservation and energy conservation in heating buildings. Compared with ile glass, IMF glass has the same principle in terms of heat conduction control, but it is superior in reducing the entry of heat energy. In addition, low radiation glass and multi-functional glass have selectivity for sunlight transmission of different frequency spectrums, which can filter out ultraviolet rays, avoid fading of indoor furniture, pictures, artworks, etc. due to ultraviolet radiation, and can also absorb part of visible light, playing the role of anti glare

in addition, there is another kind of coated glass that can prevent solar radiation and outdoor thermal radiation in summer. In winter, it mainly blocks indoor thermal radiation. On the basis of the performance of low radiation glass, it also takes into account the performance of heat reflective glass. On the premise of retaining the original low radiation film, it can appropriately reduce the transmittance of sunlight (especially near-infrared) by changing the thickness of other films, Improve the reflection and absorption of sunlight (especially near-infrared ray), low emissivity and small shading coefficient

each of the above energy-saving glasses has its own thermal advantages and disadvantages. It must be optimized and selected according to the geographical and climatic characteristics, building orientation, level and economic consumption level of each region. For example, if you want to know more about the hydraulic universal testing machine and change the relevant knowledge of the testing machine, the orientation and position of the building should use heat absorbing glass to give full play to the heat insulation function of the glass and will not have a great impact on the indoor light; In severe and cold climate areas, low radiation glass and multi-functional coated glass should be selected to give full play to the glass insulation function and reduce the indoor heating load; In warm winter and hot summer areas, anti radiation glass should be selected to give full play to the thermal insulation function of glass and reduce the indoor air conditioning load in summer. For example, the use of heat absorbing glass in the direction and position of the building at the lower level or where the sun cannot radiate, not only has no obvious heat insulation effect, but also affects the indoor light and increases the lighting cost; If anti radiation glass is used in severe cold and cold climate areas, solar energy cannot be effectively used, and heating costs will be increased; In warm winter and hot summer areas, the selection of low radiation glass and multi-functional coated glass will increase the indoor temperature and increase the cost of air conditioning. At the same time, although coated glass has a certain energy-saving effect, it exists in the form of hollow glass. The combination of heat absorbing glass or anti radiation glass and low radiation glass is the best match. The solar radiation is absorbed by the heat absorbing glass and becomes heat energy. Its radiation changes into long wave radiation. The long wave radiation is reflected and isolated by the low radiation glass and cannot enter the room. In the hot areas of southern China, the outer glass of the insulating glass is coated with heat reflection film, and the inner glass is coated with low radiation film, which can not only reflect the solar radiation heat radiated on the glass, but also significantly reduce the heat transfer capacity of the insulating glass heat transfer glass, which plays a very significant role in improving the indoor thermal environment and reducing the air conditioning load

it should be noted that the above energy-saving glass is much more expensive than ordinary single glass. Among them, about 40~80 yuan will be added per square meter for hollow glass, about 200~400 yuan for vacuum glass, and about 100~300 yuan for hollow coated glass (depending on the variety, performance and thickness of the membrane). However, the energy-saving effect of using energy-saving glass is very significant, with high cost performance. When selecting, full consideration should be given to the energy-saving economic effect obtained from long-term use, and the price factor should not be taken into account. The energy-saving effects of glasses with different structures are also different. In recent years, with the development of multi-storey and high-rise buildings and the strengthening of standardized building management, the safety performance of glass has begun to be highly valued by the state. In 2003, the national development and Reform Commission, the Ministry of construction, the State Administration of quality supervision, inspection and quarantine and the State Administration for Industry and Commerce jointly issued the notice on the provisions on the administration of building safety glass. It is clearly pointed out that safety glass must be used in 11 parts of buildings that need glass as building materials. Including the external windows of buildings with 7 floors and above, with an area of more than 1. 5 M2 window glass or floor to ceiling windows whose bottom edge is less than 500mm from the final decoration surface

safety glass mainly refers to tempered glass, laminated glass and other glass products processed by the combination of tempered glass or laminated glass, such as safety insulating glass, which meet the current national standards. Single piece semi tempered glass (heat strengthened glass) and single piece medium wire glass do not belong to the category of safety glass. The notice puts forward a series of specific specification requirements and measures from the production, inspection, use, architectural design, management, construction, supervision, acceptance and other aspects of safety glass

it can be seen from the above discussion that with the increase of building energy-saving policies, the standardization of building management standards and the improvement of the scientific and technological level of the glass industry, energy-saving glass, safety glass and environmental protection glass will certainly shine in the future buildings and play an increasingly greater role

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