[China Aluminum Industry Network] I. Overview In recent years, with the rapid development of the building doors and windows and glass curtain wall industry in China, traditional wooden windows, solid belly and fasting steel windows have basically been eliminated, all kinds of new types of architectural doors and windows and glass curtain walls. Widely used. Because of the changes in structure and material, these products really make people feel pleasing, but there are still problems in terms of function, especially in thermal performance, energy loss, and the ideal indoor temperature environment cannot be guaranteed. The use of common windows and curtain walls in cold or hot areas is not sufficient.

II. Energy Saving on Aluminum Alloy Windows and Curtain Wall 1. Energy-saving nature The energy-saving construction includes many aspects, and the energy saving of aluminum alloy windows and glass curtain walls is an important part of it. The energy saving of aluminum alloy windows and curtain walls mainly refers to the process of obtaining the ideal temperature environment and light environment with minimal energy consumption during the use of the building through product design, material selection and Other measures. For example, in hot summers and cold winters, people often need to use electrical facilities that consume electrical energy to regulate the indoor temperature environment in order to obtain a normal use environment. The energy saving effect of windows and curtain walls directly affects the energy consumption. In general, energy-saving windows and energy-saving curtain wall products should have high thermal insulation performance in hot summer and high insulation performance in cold winter.

So, how to achieve summer insulation, winter insulation function?

The first thing to understand is the heat transfer method. We all know that there are three ways to transfer heat:

1) Convective radiation heat conduction.

Convective heat transfer: Refers to the heat exchange phenomenon of a gas or liquid with thermal energy while moving.

Radiative heat transfer: A phenomenon in which heat is transmitted from one object to another in the form of electromagnetic waves.

Heat conduction: It refers to the phenomenon that the heat inside the object shifts from the high temperature side to the low temperature side.

The heat transfer of buildings is the result of the combined effects of the above three methods. For this reason, the energy-saving design of windows and glass curtain walls focuses on the design of reasonable control measures in the above three heat transfer methods to achieve energy-saving purposes. In terms of affecting the thermal performance of glass curtain walls and aluminum alloy windows, energy conservation can be achieved by controlling heat transfer and increasing shielding.

According to the experimental results, the heat transfer and convective heat transfer capacity can be measured by the heat transfer coefficient. The radiation heat transfer capability can be controlled by the shading system.

Heat transfer coefficient K0=1/(Ri+d/λ+1/Re)[W/?·K]

Where Ri, Re - surface heat transfer coefficient 2 · K/Wλ - dielectric thermal conductivity W/m · K

d—The medium thickness K0 is called the total heat transfer coefficient, R0 is called the total heat transfer resistance, R0=1/K0, and K0 and R0 are two very important physical quantities in the thermal calculation of doors, windows and curtain walls.

2. Some Provisions on Energy Saving in China As the awareness of building energy conservation in China increases, the heat transfer coefficients of energy-saving windows and glass curtain walls are tentatively defined as follows:

(1) General requirements The heat transfer coefficient has a preserving period of 8 years.

(2) Advanced Apartment Buildings are Class A, K=2~2.4W/?·K

(3) Mid-range merchandise office building is Class B, K=2.6~3W/?·K

(4) General engineering regulations are Class C, K=3.1~6W/?·K

The heat transfer coefficient of similar domestic energy-saving windows and glass curtain walls in foreign countries is generally specified as K=1.8-2 W/?·K and the stability period is not less than 10 years.

III. Methods of Energy Saving for Windows, Doors, and Curtain Walls Common energy-saving methods for aluminum alloy windows and glass curtain walls are classified into the following types:

Glass energy-saving method Aluminum alloy heat-insulating material energy-saving method Double (multiple) layer structure system Energy-saving method Shading system Energy-saving method Point-supporting glass curtain wall Energy-saving method 1. Glass energy-saving method For aluminum alloy windows and glass curtain walls, due to the area occupied by glass The vast majority of surfaces, which can participate in the heat exchange area, determine that glass is the key to the energy saving of windows and glass curtain walls.

(1) Whether the glass is coated and the material of the film can be preliminarily determined to be energy-saving. Under normal circumstances, the glass can be divided into the following categories: 1) Float clear glass 2) On-line coated glass 3) Off-line coated glass 4) Low radiation On-line coated glass 5) Low-radiation off-line coated glass. Although there is no obvious change in the heat transfer coefficient of these glasses, due to the different control ability of the film on light (energy), its energy-saving effect increases sequentially.

(2) According to the glass structure, it can be divided into the following categories: 1) single glass 2) hollow glass 3) multi-layer hollow glass. The heat transfer coefficient is reduced in turn, that is, the energy-saving effect is successively enhanced. The calculation and experimental data show that the heat transfer coefficient of monolithic glass is usually K=6W/?·K, and the hollow glass (ordinary) is K=2.3~3.2W/?·K, while the low-emissivity coated insulating glass is used. Layer filling inert gas) K = 1.4 ~ 1.8W/? · K.

(3) In addition to the above methods, glass can also be applied to the energy-saving film to improve energy-saving effects.

2. Aluminum alloy thermal cuts energy-saving law:

Aluminum alloy profiles in the window and curtain wall system not only play the role of supporting the keel, but also have a great impact on the energy saving effect. Under normal circumstances, the aluminum alloy section is much smaller than the area of ​​the glass. For this reason, the thermal conductivity has a greater impact on the energy saving effect. For this reason, a heat cut section is produced. According to the different methods of heat-dissipating aluminum profiles, they are divided into perfusion-type heat-insulating aluminum profiles and cutting-bar-type heat-insulating aluminum profiles. The common feature of these two types of aluminum alloy heat-insulating profiles is that the aluminum materials on the inner and outer sides are separated by a low thermal conductivity insulating material with sufficient strength. This reduces the heat transfer coefficient and increases the thermal resistance. Even in the hot summer season, when the sun is exposed, the surface temperature of the outdoor section of the hot-junction profile can usually reach 35 to 85°C, and the room can still be maintained at about 24 to 28°C, effectively reducing the heat transferred to the room. Reduce cooling costs; in the cold winter, the outdoor aluminum temperature can be equivalent to the ambient temperature (typically -28 ~ -20 °C) and the indoor aluminum can still reach 8 ~ 15 °C, thereby reducing heat loss, saving winter heating Costs to achieve energy savings.

3. Double (multiple) layer structure system energy-saving method.

Normal windows and glass curtain walls are generally single-layer structures in warm areas, while in cold or hot areas, multi-layer (double)-layer windows or double-curtain walls/dynamic curtain walls can be used, utilizing two-story structures. The air layer (through the designed air layer) reduces the overall heat transfer coefficient of the system to achieve energy saving.

4. Shading system energy-saving method:

Since aluminum alloy windows and glass curtain walls use glass in a large area, the sun's radiation is radiant heat. The essence of energy saving is how to keep the light (energy) outdoors during the hot summer sun, or allow enough light (energy) into the room in the cold winter. Despite many efforts made by researchers in building materials, it is still difficult to find the ideal material to solve this problem. The integration of shading technology into aluminum alloy windows and curtain wall systems is also one of the effective ways to save energy. In foreign countries, the sunshade products that have been systematically used have been widely used and have achieved significant energy-saving effects. They are believed to be favored in China.

5. Energy-saving methods for supporting glass curtain walls:

In addition to the aforementioned glass method, energy conservation of point-supporting glass curtain walls also handles the thermal insulation design of the glass and spliced ​​joints. Engineering experience and experiments have proved that energy-saving design of point-supported curtain walls is worth adopting in cold regions and hot regions.

IV. Comparison of aluminum alloy energy-saving windows and plastic steel windows 1. Differences in grades: Domestic aluminum alloy thermal insulation windows and plastic steel windows are consumer groups that are suitable for different buildings. Statistics show that plastic steel windows are suitable for general low-rise residential buildings. Consumers of this grade are often not very demanding on the quality of the product, while the high-performance thermal insulation aluminum alloy window is suitable for all types of height and various grades of construction, and the quality and longevity performance can withstand high. Standard test.

2. Difference in performance: The two have similar energy-saving effects; however, due to the difference in materials, the plastic window is easily deformed after being used for a period of time, and the sealing performance is inferior to that of high-performance aluminum alloy windows.

3. The difference in life: due to the difference in strength, elastic modulus and wear resistance of the material, the service life of the high performance aluminum alloy window is often greater than the service life of the plastic steel window.

4. The price difference: Generally speaking, the price of high-performance aluminum alloy windows is usually higher than the price of plastic steel windows. However, in the long run, although the price of high-performance aluminum alloy windows is high, they have a long service life. While steel windows are cheaper, they have a shorter service life. Therefore, the comprehensive price ratio is comparable.

This shows that high-performance aluminum alloy windows have a more competitive advantage.

Keps Nuts

Keps Lock Nut,Stainless Steel Kep Nut,Steel Kep Nut,Hegonal Toothed Nut

Kunshan Zhonggu Precision Hardware Co., Ltd. , https://www.zgfastener.com