Insulated glass was invented by Americans in 1865. It is a new building material with good heat insulation, sound insulation, beautiful appearance and practicality, and can reduce the weight of the building.
It is a high-efficiency sound-insulating and heat-insulating glass made of two (or three) pieces of glass, using a high-strength and high-airtight composite adhesive to bond the glass pieces to an aluminum alloy frame containing a desiccant. Insulated glass has many properties superior to ordinary double-glazed glass, so it has been recognized by countries all over the world. Insulated glass is to evenly space two or more pieces of glass with effective support and bond and seal the periphery, so that dry gas is formed between the glass layers. Space glassware. Its main materials are glass, warm edge spacers, corner bolts, butyl rubber, polysulfide rubber, and desiccant.
Structure
Insulated glass Insulated glass is composed of two or more layers of flat glass. Use high-strength and high-air-tight composite adhesive all around to bond and seal two or more pieces of glass with sealing strips and glass strips. Dry gas is filled in the middle, and desiccant is filled in the frame to ensure the dryness of the air between the glass sheets. Various glass original sheets with different properties can be selected according to requirements, such as colorless transparent float glass, patterned glass, heat-absorbing glass, heat-reflecting glass, wired glass, tempered glass, etc. and frames (aluminum frames or glass strips) etc.), made by cementing, welding or welding.
Its structure is as shown in the cross-section of double-layer insulating glass. The insulating glass can use 3, 4, 5, 6, 8, 10, and 12mm thick sheets of original glass, and the air layer thickness can use 6, 9, and 12mm intervals.
The thermal conductivity of glass is 27 times that of air. As long as the insulating glass is sealed, the insulating glass has the best thermal insulation effect.
There is a certain space between the glass of insulating glass. The frame is filled with desiccant to ensure the dryness of the air between the glass sheets. The distance between two layers of insulating glass is generally 8mm.
High-performance insulating glass is different from ordinary insulating glass. In addition to sealing dry air between the two layers of glass, a special metal film with good thermal performance is also coated on the air layer side of the outer glass. It can cut off a considerable amount of energy from the sun to the room and have a greater heat insulation effect.
Principle
Since there is a desiccant inside the insulating glass that can absorb water molecules, the gas is dry. When the temperature decreases, condensation will not occur inside the insulating glass. At the same time, the dew point on the outer surface of the insulating glass will also rise. high. For example, when the outdoor wind speed is 5m/s, the indoor temperature is 20°C, and the relative humidity is 60%, 5mm glass begins to condense when the outdoor temperature is 8°C, while 16mm (5+6+5) insulated glass will condense under the same conditions. Condensation will only appear when the outdoor temperature is -2°C. Condensation will only begin when the outdoor temperature of 27mm (5+6+5+6+5) triple insulating glass is -11°C.
There are three ways of energy transfer in insulating glass: radiation transfer, convection transfer and conduction transfer.
Radiative transfer
Radiative transfer is the transfer of energy in the form of radiation through rays, which include visible light, infrared and ultraviolet radiation, just like the transfer of solar rays. Reasonable configuration of insulating glass and reasonable thickness of insulating glass spacers can minimize the transmission of energy through radiation, thereby reducing energy loss.
Convection transfer
Convection transfer is due to the temperature difference on both sides of the glass, causing the air to drop on the cold side and rise on the hot side, resulting in air convection and energy loss. There are several reasons for this phenomenon: first, the sealing between the glass and the surrounding frame system is poor, causing the gas inside and outside the window frame to directly exchange and produce convection, resulting in energy loss; second, the internal space structure design of the insulating glass Unreasonable, causing the gas inside the insulating glass to generate convection due to the temperature difference, driving energy exchange, thereby causing energy loss; third, the temperature difference between the inside and outside of the windows that make up the entire system is large, resulting in the temperature difference between the inside and outside of the insulating glass. Larger, the air first generates convection on both sides of the insulating glass with the help of cold radiation and heat conduction, and then passes through the insulating glass as a whole, causing energy loss. Reasonable insulating glass design can reduce gas convection, thereby reducing energy convection loss.
Conduction transfer
Conduction transfer is through the movement of the molecules of objects, driving energy to move, and achieving the purpose of transfer, just like using an iron pot to cook or using a soldering iron to weld things, while the conduction transfer of energy by insulating glass is through the glass and its interior. Completed by air. We know that the thermal conductivity of glass is 0.77W/mk. The thermal conductivity of air is 0.028 W/mk. It can be seen that the thermal conductivity of glass is 27 times that of air, and the presence of active molecules such as water molecules in the air affects the conduction transfer and convection transfer performance of insulating glass energy. The main factor, thus improving the sealing performance of insulating glass, is an important factor in improving the thermal insulation performance of insulating glass.
