1. The overview
Double-layer IGP (InsulationGlass & Polycarbonate) side window glass is a new type of insulating safety glass, which has a certain range of applications in some special areas abroad, such as the United States, Brazil, Argentina, Chile, Malaysia, the Philippines, and other countries. applications, of which the United States, Brazil, Argentina, and other countries have been widely used. However, when used in a tropical rainforest climate, there is a problem of internal fogging, as shown in Figure 1. After detailed analysis, research, and experimental verification, the double-layer IGP side window glass cannot meet the use environment of tropical rainforest climate. To solve the problem of using IPG side window glass in a tropical rainforest climate, a design scheme of three-layer IGP side window glass from Jinan LIJIANG Glass is proposed.
Figure 1 The fogging phenomenon of double-layer IGP side window glass
2 IGP side window glass structure and performance
The structure of double-layer IGP side window glass is the same as that of ordinary insulating glass, as shown in Figure 2. The outer layer of IGP side window glass is a PC (polycarbonate) board, the middle layer is Ar or other inert gas, the inner layer is safety tempered glass, and the periphery is a spacer, molecular sieve, and sealing adhesive.
Figure 2 Double layer IGP side window glass structure
Figure 3 New layer IGP side window glass structure
The three-layer IGP side window glass structure is in the form of PC plus double-layer ordinary insulating glass, as shown in Figure 3. The outer layer of IGP side window glass is PC board, the middle layer is Ar or other inert gas, the inner layer is ordinary double-layer insulating glass, and the periphery is spacer bar, molecular sieve, and sealing adhesive.
Three-layer IGP side window glass has better sound insulation and heat insulation performance than double-layer IGP glass. The most important feature is that the gas layer between the outermost PC and the innermost glass is divided into two independent spaces by the middle class, which greatly reduces the friction between the inner surface of the outermost PC and its adjacent glass surface. temperature difference, thereby reducing or avoiding the possibility of fogging.
3. The analysis of climate characteristics of tropical rain forest and selection of parameters
3.1 Climate characteristics of tropical rainforest
The tropical rain forest climate is distributed near the equator, mainly in the Amazon River Basin in South America, eastern Central America, the Congo River Basin in Africa, the northern coast of the Gulf of Guinea, the eastern part of Madagascar, the southern part of the Malay Peninsula, the Malay Archipelago, the southern part of the Philippine Archipelago, Irian Island, Indonesia, Oceania from Sumatra to New Guinea, northeastern Australia. These places are hot and rainy throughout the year, and the annual variation of solar radiation is small. The average temperature of each month in a year is 24 ℃ ~ 28 ℃, and the annual temperature difference generally does not exceed 5 ℃, especially in the ocean, it usually does not exceed 1.
The daily variation of temperature is larger than that of the year, and the daily range can reach 10°C to 15°C. However, the daily maximum temperature rarely exceeds 35°C, and the daily minimum temperature rarely falls below 20°C. The humidity is the highest throughout the year, with the relative humidity reaching over 90%, and the relative humidity in sunny weather is generally around 65%.
3.2 Application Environment Research
To obtain more accurate environmental data, our company researched trains operating in tropical rainforest climates and measured the temperature and ambient humidity of the side windows of running trains and stationary trains, as shown in Figure 4. The survey found that fogging of the side window glass occurs in sunny weather. Although the relative humidity is high in rainy weather, the ambient temperature is low and the temperature difference between the inside and outside of the car is small. On the contrary, the fogging of the side window glass will not occur.
Figure 4 The application environment research of three-layer IGP side window glass
4. The principle and conditions of fog formation inside the insulated glass
4.1 The fogging principle of insulated glass
After a certain amount of water vapor enters the interior of the insulating glass, if the glass temperature on one side is lower than the temperature on the other side, in the presence of a temperature difference in the gas inside the insulating glass, the gas density in the area with high temperature is lower than that in the area with low temperature. Under the action of gravity, the gas circulates from the high-temperature glass surface to the low-temperature glass surface, when the gas containing water vapor flows to the low-temperature glass surface, the water vapor may condense on the low-temperature glass surface, forming mists. The principle is shown in Figure 5.
Figure 5 The fogging principle of insulated glass
4.2 Insulated glass fogging conditions
Under certain atmospheric pressure, two factors cause fogging inside the insulating glass: one is the relative humidity of the gas inside the insulating glass, and the other is the temperature difference between the high and low-temperature glass. Whether the insulating glass will be fogged can be analyzed by a flame-wet graph or flame-wet calculation software on the premise of obtaining the gas temperature distribution. Due to the water vapor permeability of PC, the relative humidity of the gas inside the insulating glass is close to the external environment of the vehicle. Therefore, without changing the water vapor permeability of the PC material, the temperature difference between the PC and the adjacent glass can be reduced. The fogging problem of IGP glass.
5. Analysis of the internal temperature field of three-layer IGP glass
According to the previously selected environmental parameters, use ANSYS fluent software to analyze the temperature field of the three-layer IGP glass with two structural parameters. The first structural parameters are shown in Figure 6, and the second structural parameters are shown in Figure 7; The temperature field distribution of the IGP glass with the structural parameters is shown in Fig. 8, and the temperature field of the IGP glass with the second structural parameter is shown in Fig. 9.
Figure 6 The first structural parameter of IGP glass
Figure 7 The second structural parameter of IGP glass
Figure 8 The first structural parameter IGP glass temperature field
Figure 9 The second structural parameter IGP glass temperature field
It can be seen from Figures 8 and 9 that the gas temperature on the PC side in the IGP glass with the first structural parameter is 49.2 °C, and the gas temperature on the adjacent glass side is 43.91 °C. The gas temperature was 49.24°C, and the gas temperature on the adjacent glass side was 44.43°C. The dew point temperature of the gas in the glass was calculated to be 42 °C by the flame wet calculation software. Therefore, the three-layer IGP of the two structural parameters does not meet the conditions of fog formation, which can meet the use requirements of the tropical rainforest climate.
6. Test and verification
Due to the limitation of installation space, only the first structural parameter was selected for sample production and verification of three-layer IGP glass. The entire verification is carried out in two stages. In the first stage, laboratory samples are produced to simulate the vehicle operating environment for verification in the laboratory. In the second stage, physical sample windows are produced and installed on the operating vehicles for verification. At present, the two-stage verification has been made of wood, and there is no fogging phenomenon.
7. Conclusions and Recommendations
Jinan LIJIANG Glass selects reasonable analysis parameters through the research and analysis of the climate characteristics of tropical rain forests, combined with the actual field survey data, and assisted analysis through ANSYS fluent, and then through laboratory sample verification and physical loading verification, three-layer IGP side glass window, which could produce by automatic Insulated glass production line, could be adjusted to meet the requirements of anti-fogging performance in tropical rain forest climate environment. The three-layer IGP structure parameters can be optimized according to the actual vehicle installation environment to ensure the rationality of the actual product structure parameters.
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