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Influence of position and quantity of Low-E film in insulating triple glass on performance​

1. Overview

Insulating glass has great advantages in reducing self-weight and improving building performance. The performance of insulating glass can be optimized without increasing the cost. For triple-glass insulating glass containing 2 pieces of Low-E glass, some manufacturers put the Low-E film on the second and fifth sides, and some put the Low-E film on the second and fourth sides. surface; what effect it has on the overall performance of the glass, this paper analyzes this through experiments.

2. Rationale

There are three forms of glass energy transfer in buildings: radiation transfer, convection transfer, and conduction transfer.

The industrial glass

(1) Radiation transfer is a form of light transfer, which is generally directly related to sunlight and directly related to physical properties such as the refractive index and reflectivity of the surface of the object. For light-transmitting products such as glass, radiation heat transfer is the main heat transfer. To improve the heat transfer performance of the glass, physical properties such as light transmittance and rear reflectivity can be changed through coating.

(2) Convective heat transfer is based on airflow, and the flow of energy from high to low direction drives the flow of molecules in the air, forming convection; the main defect is the sealing problem if the boundaries between two spaces with different temperatures are clear and sufficient Airtightness will not form convection heat transfer, but the current actual situation is to continuously improve and reduce air convection.

(3) Conduction heat transfer is due to the energy difference between two objects in contact with each other, which is mainly reflected in the form of temperature difference. The energy is transferred through molecular motion between objects, just like iron pans for cooking, electric irons for ironing clothes, etc., which are hollow For glass, its heat conduction form is due to the large temperature difference between indoor and outdoor, high indoor air temperature in winter, low outdoor air temperature, energy conduction through mutual contact between air and glass, resulting in temperature loss.

Therefore, the gas in the middle of the insulating glass can be changed from air to an inert gas such as chlorine. Because chlorine has poorer thermal conductivity, argon can be used to reduce conduction and heat transfer, thereby improving the performance of insulating glass. The characteristics of coated glass are realized by coating a layer of film containing metallic silver ions on the surface of ordinary white glass. Metallic silver ions are easily oxidized and scratched. Coated glass is not directly exposed to the air as a single piece, but is most often compounded as insulating glass.

3. Test analysis

This paper explores the related issues of Low-E film in insulating glass, mainly using the control variable method of keeping the convection transfer and conduction transfer unchanged, changing the radiation transfer, using the glass system module in MQMC2012 for calculation, comparing the result data, and drawing conclusions.

Figure 1 Schematic diagram of insulating glass (1# is the outdoor side, 6# is the indoor side)

Figure 1 Schematic diagram of insulating glass (1# is the outdoor side, 6# is the indoor side) 

Calculation data: Table 1 is the relevant calculation data, and two kinds of products, single silver, and double silver, are simulated and calculated. When each Low-E product has one piece, Several different conditions are in different positions when two tablets. The main factor affecting the performance of the glass is the reflectivity, which is to reflect the far-infrared heat radiation to play the role of thermal insulation.

Table 1 Relevant Calculation Data

NumberThe Type of Low-E Glass FilmQuantity (Pieces)PositionGlass ConfigurationK ValueScg
1Single Silver Low-E Glass

Double Silver Low-E Glass

4. Conclusion

(1) Under the same conditions, the difference of the heat transfer coefficient of the cavity filled with air or argon is only related to the type and quantity of the Low-E film and has nothing to do with the position.

(2) When there is only one Low-E glass in the three glasses, the K value of the Low-E film on the fourth or fifth side is the lowest, and the shading coefficient is the highest on the fifth side.

(3) When there is two Low-E glass in the three glass, the K value of the Low-E film is the lowest on the second, fourth, third, and fifth sides, and the shading coefficient is the highest on the third and fifth sides, followed by the second and fifth sides. , the second and fourth sides are the lowest.

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