The high latitudes of the northern hemisphere are alpine regions in winter. The temperature in winter is extremely low, and the temperature difference between indoor and outdoor is large. To meet the living requirements of residents in winter, it is necessary to carry out a good thermal insulation design for buildings. Among them, the thermal insulation performance of windows is a very important link in the thermal insulation performance of buildings.
Building doors and windows (the entry "building doors and windows" is provided by Google) is the weakest part of the building envelope's thermal insulation performance. Its long-term energy consumption accounts for about 50% of the long-term energy consumption of the entire building. Therefore, improve the thermal insulation of doors and windows. Performance is an important way to reduce the long-term energy consumption of buildings. The thermal insulation performance of windows not only significantly affects the heating energy consumption of buildings, but also has a significant impact on the indoor thermal environment, comfort, and indoor hygiene. If windows are poorly insulated, heat loss from heat transfer through the window (term "heat loss" courtesy of Google) and air infiltration through window gaps can increase significantly, resulting in a significant increase in heating energy consumption. The widely used insulating glass (the entry "insulating glass" is provided by Google) is a new type of building material that is heat-insulating, sound-insulating, beautiful and practical, and can reduce the weight of buildings. The purpose of this article is to study the design scheme of the double insulating glass spacing and strive to obtain an optimized spacing scheme that can achieve a higher level of thermal insulation performance and to carry out experimental verification to provide a certain reference for the thermal insulation design of building windows in high latitudes in the northern hemisphere in the future. In addition, the double-layer insulating glass produced by Jinan LIJIANG Glass automatic insulating glass production line has a long service life, good thermal insulation effect, and is economical and practical.
1. Experimental scheme
The thermal insulation performance of glass windows is directly reflected by the K value of the heat transfer coefficient (the entry "heat transfer coefficient" is provided by Google). The lower the heat transfer coefficient, the less heat dissipation and the better the thermal insulation performance of the window. Therefore, this experiment mainly explores the glass spacing combination that minimizes the heat transfer coefficient under the existing technical conditions. By formulating the gradually proposed spacing combination, the experiment of measuring the heat transfer coefficient is carried out, and the changing image of the spacing combination and the heat transfer coefficient is drawn, and the relationship between the spacing combination and the heat transfer coefficient is studied according to the image. Excellent spacing combination, complete the research. After the research on the combination, the orientation of δ1 and δ2, that is, the orientation of the glass during the installation of the glass was studied, and the influence of different orientations on the thermal insulation performance of the window was studied. After the final spacing combination is determined, the optimal orientation is further explored to further improve the thermal insulation performance of the windows and provide a basis for the installation of windows during the building construction process. According to previous experimental data, when the double-glass spacing is less than 10 mm, the spacing and thermal resistance are almost in a linear relationship; when the double-glass spacing is 10 mm to 30 mm, the relationship between the spacing and thermal resistance is a curve; when the spacing exceeds At 30 mm, the thermal resistance of the air layer increases very slowly due to the combined effect of convection and radiation heat exchange.
The design should be based on the needs of thermal resistance and the economic scale of the frame material, and the spacing of the glass should be properly determined, generally not less than 9 mm. At present, the double-insulating glass windows widely used on the market include plastic windows, wooden windows, aluminum alloy windows, and aluminum-plastic composite windows. 2.8 W·m-2·K-1, plus the errors in winter heating and other conditions, the living environment of ordinary residents must not have the excellent conditions of the laboratory, and this coefficient will be higher in practice. Jinan LIJIANG Glass also visited some urban dwellings in high latitudes of the northern hemisphere and measured the indoor temperature. In some places, the indoor temperature is only 15℃. It is not difficult to find that most of the heat is dissipated through the windows, resulting in greater pressure and more resources for heating. Much waste. The window glass is changed from a single glass to double glass or triple glass, and the thermal insulation performance of glass will be significantly improved. It is not the glass thermal resistance that plays a role, but the air layer between the glass is the main reason for the increase in thermal resistance because the heat transfer coefficient of still air is lower than that of any material.
Figure 1 The special type double-insulating glass aluminum-plastic composite windows
Therefore, in line with the improvement of the development level of glass window technology, to better improve the thermal insulation performance of doors and windows, triple glass windows can be made. According to the relationship between the thermal resistance of the airtight air layer and the thickness of the air layer, the thickness of the clear spacing to meet the better thermal insulation performance is studied, and the orientation of different spacings of the glass is studied to complete the research of this project.
2. Experimental processes and results
According to the influence of airflow, glass thickness, and other factors on the heat transfer coefficient of glass windows, equal spacing can achieve the best thermal insulation effect. If one of the two spacings is too large and the other is too small, according to the changing trend of the K value of the double-glass glass, it can be seen that the excessively large spacing undertakes most of the thermal insulation tasks, but the heat transfer coefficient will not be greatly reduced when the glass spacing is too large. The width will become smaller and smaller, so too large spacing can only be a waste, and too small spacing is too sensitive to the thermal insulation effect, a slight increase in spacing will cause a significant reduction in the heat transfer coefficient, so it is not suitable to use Spacing that is too small, too large, or too small will ultimately lead to a deterioration in thermal insulation performance, so it is assumed that the equally divided spacing minimizes the heat transfer coefficient of the window.
According to the research, the three-glass windows with specifications of 3 mm+3 mm, 6 mm+6 mm, 9 mm+9 mm, and 12 mm+12 mm are widely used in the market. Glass windows with smaller spacing are mainly used for smaller openings in auxiliary rooms such as toilets, while glass windows with larger spacing are mainly used for larger openings in main rooms with high thermal requirements such as living rooms and bedrooms.
At the same time, the author conducted research on high-latitude countries in the northern hemisphere, such as Finland or Norway, and participated in the experiment of heat transfer coefficient determination, and obtained some experimental data. The general three-glass windows of these specifications are 12 mm + 12 mm. The thermal conductivity is the lowest, the thermal conductivity of the main material in the plastic window is 1. 7～1. 8 W·m-2·K-1, three-glass wood window: 1.7～1. 8W·m-2·K-1, aluminum Plastic composite triple glass: 2.0～ 2.1W·m-2·K-1.
The three-glass window with equal spacing is commonly used in the market, so what about the unequal spacing? Because the heat transfer coefficient decreases linearly when the glass spacing is before 10 mm, excluding the possible combination of 3 mm, it cannot play the role of still air. The advantage of low thermal conductivity. At the same time, considering that the thin three-glass window will also make the thermal conductivity close to two-glass, several groups of combinations are drawn up according to 12 mm + 12 mm: 6 mm + 18 mm, 9 mm + 15 mm, and these two sets of spacing combinations are carried out. experiment. The experiment is consistent with the hypothesis. The combined heat transfer coefficient of 6 mm + 18 mm spacing is 2. 2 W · m-2 · K-1, and the combined heat transfer coefficient of 9 mm + 15 mm is 2. 0 W · m-2 · K -1. Comparing it with the heat transfer coefficient of the 12 mm+12 mm triple-glass window, it is not difficult to see that the heat transfer coefficient of the 12 mm+ 12 mm combination triple-glass window has the lowest heat transfer coefficient among these combinations, so the current optimal spacing can be obtained. The combination is the equally spaced combination. Wide spacing combinations are envisaged, say 15 mm + 15 mm, but depending on current thermal resistance needs, technology level, and economical size of frame material, total spacing combinations are 24 mm, 15 mm + 15 mm, and even higher spacings The combination is not economical, as it would lead to a sudden and sudden increase in the cost of making window frames (term "frame" by Google) at the current state of the art, so this possibility is ruled out.
Figure 2 The double-layer insulating glass 1
According to the research, experiment, analysis, and data arrangement, it is concluded that the triple-glass window with the spacing combination of 12 mm + 12 mm is the most economical and thermally insulating spacing combination at present. Such windows should be widely used with large openings in various buildings to replace two-glass windows with much lower heat transfer coefficients or three-glass windows with other spacing combinations. For bathrooms, storage rooms, kitchens, corridors and other auxiliary rooms that do not have high thermal insulation performance requirements for main rooms such as living rooms, bedrooms, etc., a combination of 9 mm + 9 mm or lower spacing can be used. Although they do not have 12 mm + 12 mm spacing insulation, the thermal insulation requirements of these rooms are not as high as those of the main rooms. Such spacing can meet the thermal insulation requirements of these auxiliary rooms and is higher than the thermal insulation performance of two-glass windows, which is more economical.