Industry Knowledge

Introduction

With the development of building energy conservation, three-glass two-chamber insulating glass has become the leading product form of building exterior windows. Compared with the traditional single-chamber insulating glass, the increase in chambers improves the thermal insulation performance of insulating glass. Compared with the K value of (6+16A+6) insulating glass of 2.7 (WmK), the K value of (6+16A+6+16A+6) insulating glass reaches 1.7W/mK. If low-emission (Low-E), inert gas filling, warm edge strips and other technologies are applied, such as (6Low-E+16Ar+6+16Ar+6Low-E) insulating glass, the K value can reach 0.8W/m”K.

While improving the thermal insulation performance of doors and windows, three-glass two-chamber insulating glass also increases the material consumption of doors and windows. . First, the weight of the glass increases, which in turn increases the width and thickness of the profile and the strength requirements of the hardware. For triple-pane double-chamber insulating glass, the two outer glasses bear the support and load functions. The main function of the middle glass is to separate the chamber, limit the convection heat transfer of the filling gas, and thus increase the thickness of the insulation layer, but it must also meet certain mechanical performance requirements. For the purpose of the middle glass, it is easy to think that other thin materials are used to replace the existing 6mm middle glass, which forms thin-glass triple pane glazing. 

1 Center-mounted thin glass insulating glass

2TD

Inorganic glass is the leading product form of three-glass two-chamber insulating glass. The thinning method is considered from the three layers of glass it constitutes. The outdoor glass is subjected to wind load and is thinned under the premise of meeting the mechanical performance requirements. The indoor glass is not directly subjected to wind load, so it is used as Since the use surface still requires mechanical performance requirements, there is a certain potential for thinning. The glass between the interior and exterior (center glass) does not directly bear the wind load, so it has the greatest potential for thinning. Japan's Lixil thinned the original (3+3+3) mm glass to (3+1.3+3) mm, with a lightweight rate of about 19%; when the thinning is (3+1.3+1.3) mm, the lightweight rate is about 38%, as shown in Figure 1. The Western Pacific National Laboratory in the United States replaced traditional insulating glass with high-efficiency energy-saving thin insulating glass. The research on the energy-saving effect of replacing existing building glass was carried out. The thin insulating glass is composed of two 1/8 inch (about 3.2mm) glass with Low-E film and a 1/16 inch (about 16mm) thin glass in the middle. The test results show that the HVAC energy saving is 0.2~18.7 kWh per day in the heating season (3%~18% energy saving per person), and 2.5~8.0 kWh per day in the cooling season (23%~41% energy saving), and the sound penetration is reduced by 8~10dB. Lawrence Berkeley National Laboratory placed 0.7mm thin glass in ordinary insulating glass (3mm glass + 3mmLow-E) to form thin insulating glass, as shown in Figure 2. Studies have shown that in climates dominated by heating (such as Minneapolis, Minnesota), the energy-saving potential of thin insulating glass instead of typical exterior window glass is 16%, in mixed climates (such as Washington, DC), the energy-saving potential is 12%, and in climates dominated by cooling (such as Houston, Texas), the energy-saving potential is 7%. The thickness of glass used for exterior windows in my country has been increasing. In the 1980s, 3mm glass was the dominant specification of float glass in my country. After 1993, 5 In the past, 5mm glass was the mainstream product, and recently 6mm glass has become the mainstream product. In 2013, Wang Xinchun and others proposed the suggestion of thinning flat glass products. The annual per capita consumption of flat glass in my country is 20.7kg, which is 1.25 times that of EU countries, twice that of the United States, and 2.6 times the world average. The thickness of flat glass is one of the reasons for the abnormal per capita consumption of flat glass in my country. It is estimated that if the 5mm glass is thinned to 4mm in 2012, 7.1 million tons of glass production can be reduced, and 7.71 million tons of raw material consumption can be reduced, including 6.35 million tons of natural resources such as silica sand and 1.36 million tons of chemical products such as soda ash. The article proposes to transform the development model of industries and enterprises and improve production technology. Five suggestions were made, including adjusting the industrial chain of technical level, increasing scientific research efforts, and relevant departments starting the work of thinning flat glass as soon as possible. At the same time, companies such as CSG Group are also actively trying thin applications for exterior windows.

At present, the development of thin insulating glass has good adaptability. First, to adapt to the development concepts of "dual carbon goals", green manufacturing, green buildings, etc., thin insulating glass will drive energy saving, material saving and carbon reduction in the glass, profiles, doors and windows curtain walls, and transportation industry chains. Secondly, double-chamber/multi-chamber insulating glass is the leading product of my country's high-efficiency and energy-saving transparent enclosure structure, and has the potential for thinning. Third, the central thin glass insulating glass has a broad industrial foundation, which is conducive to driving the transformation and development of the industry. Fourth, my country's thin glass / Ultra-thin glass manufacturing provides materials and industrial foundation. Photovoltaic glass of sodium-lime-silicon system and protective glass can provide basic products. The thinning conversion and production of flat glass are unparalleled in technology and production. Compared with industrial glass crucibles and architectural glass crucibles:

2 Insulating glass with central film materials

Insulating glass with central organic film materials (as shown in Figure 3) divides a single chamber into two or more chambers of insulating glass. Non-functional organic film (white film) only separates the chamber to limit convection, increase the thickness of the insulation layer and achieve thinness and lightness. Functional organic film (heat mirror film) imparts functions such as low emissivity, and increases the energy-saving effect of controlling thermal radiation on the basis of white film. Insulating glass with central film materials is made by Southwall of the United States. Technologies company, it came out in 1970 and has been used in buildings. Heat mirror film insulating glass has excellent thermal properties, and Li Wu and others have conducted research on this. The central film material is a thermoplastic film, which is tightened by thermoplasticity when heated. The laying and installation of the membrane material requires manual participation, which increases the production cost. He Xueping and others studied the key assembly process design of the central film material insulating glass system. Reducing the cost of membrane materials, realizing the automatic installation of membranes, reducing the degree of manual intervention and the corresponding processing costs will become the key points of the development of central film material insulating glass.

3 Real glass composite insulating glass

Vacuum glass is a glass product that is separated by two or more pieces of glass with support columns, the periphery is sealed to form a cavity, and the cavity is evacuated to form a vacuum cavity. Considering the balance of heat transfer and force performance of the support column, the number and area of the support column should be minimized, so the support column with a small cross-sectional area and shortness is selected without affecting the visual effect. In theory, convective heat transfer and conductive heat transfer have nothing to do with the thickness of the vacuum layer. Vacuum layer thickness The thickness is generally between 0.15 and 0.25 mm: At least one piece of vacuum glass is made of low-emissivity glass to achieve effective insulation in the three basic heat transfer modes of thermal conduction, convection and thermal radiation. Therefore, vacuum glass itself is a highly efficient thin glass product. Only vacuum glass composite insulating glass can give full play to the insulation performance of vacuum glass, and its structure is shown in Figure 4. Although there is a piece of glass in the vacuum glass in the middle of the insulating glass, this piece is affected by the atmospheric pressure after vacuuming and bears the pressure of the support column, so the thinning of the vacuum glass is limited. Vacuum glass reduces the overall thickness of the composite insulating glass with its high efficiency and energy-saving performance, achieving the purpose of thinning. The production level of vacuum glass in my country has made great progress, but cost is still the main factor affecting its promotion. At least one piece of vacuum glass is made of low-emissivity glass to achieve effective insulation in the three basic heat transfer modes of thermal conduction, convection and thermal radiation. Therefore, vacuum glass itself is a highly efficient thin glass product. Only vacuum glass composite insulating glass can Give full play to the insulation performance of vacuum glass, and its structure is shown in Figure 4. Although there is a piece of glass in the middle of the hollow glass, this piece is affected by the atmospheric pressure after vacuuming and bears the pressure of the supporting column, so the thinning of the vacuum glass is limited. Vacuum glass reduces the overall thickness of the composite hollow glass with its high efficiency and energy saving performance, achieving the purpose of thinning. The production level of vacuum glass in my country has made great progress, but cost is still the main factor affecting its promotion.

4 Aerogel hollow glass

Aerogel has excellent lightweight thermal insulation performance. Placing it in hollow glass can achieve thinness and high efficiency and energy saving. The K value of (6+12A+6) hollow glass is 2.8W/mK, the K value of (6Low-E+12A+6) is 1.8W/m'K, and the K value of (6+12aerogel+6) reaches 1.0W/m'K. A feasible way to place aerogel in the middle is to use aerogel particles for filling, which is relatively low in cost. The difference between the refractive index formed by the aerogel and particle interface and the glass and The transparency of aerogel itself will increase the haze value of insulating glass and affect the transparency of insulating glass. Reducing the haze value of aerogel itself and achieving the composite of a whole piece of aerogel (rather than particles) is one of the effective ways to improve the transparency. The transparent enclosure structure of the building facade (external doors and windows, curtain walls) has high requirements for transparency, and it is expected to be widely used in the enclosure structure for the purpose of lighting. However, it is necessary to study the effects of solar radiation heat accumulation and cold and hot shock on the mechanical properties of insulating glass.

5 Summary

The thinning of insulating glass is a development trend with multiple benefits such as material saving, energy saving and carbon saving. As a development strategy and choice, the middle thin glass insulating glass has a good industrialization foundation and good cost advantages, and is the preferred development direction. The middle film material insulating glass and vacuum glass composite insulating glass have a high degree of thinness, have a certain application space in new buildings, and have obvious advantages in the replacement of glass in the energy-saving transformation of existing buildings. As a future development direction, aerogel insulating glass should be applied in lighting enclosure structures.