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How Much Does Inert Gas In Insulating Glass Contribute To The Heat Transfer Coefficient K?

The purpose of filling insulating glass with inert gas is to reduce the heat transfer coefficient K value and improve the sound insulation performance. Therefore, it is necessary to select the inert gas with large molecular weight, higher thermal resistance than air, abundant in nature and easy to prepare. Argon is undoubtedly the best choice.

How much contribution can argon make to the K value of insulating glass? For comparison and convenience, the same Low-E insulating glass as in the previous problem is still adopted. The K value data measured after 85% argon is shown in Figure 2. Two conclusions can be drawn by comparing them: Firstly, the K value decreases regardless of the thickness of the gas layer, and the thickness of the gas layer decreases by about 0.3W/ (m2·K). When the gas thickness is above 12mm, the decrease is small, about 0.2W/ (m2·K), which indicates that the inert gas is very effective in limiting the molecular collision heat transfer. Secondly, the change trend of K value with thickness after argon filling is the same as that of air, that is, the optimal gas layer thickness is also 12mm.


It can be seen that the K value can be reduced by about 0.2W/ (m2·K) by charging argon. It should be noted that the actual charging rate of argon is impossible to reach 100%, because the air contains argon. In the charging process, pure argon will mix with the air and reduce the purity of argon, no matter how slow the charging rate is. The filling rate of the automatic hollow production line can generally reach more than 85%. Therefore, when using Window software to calculate the K value parameter, it is not necessary to choose 100% argon gas, even if the calculated value is false theoretical value, because the actual value cannot reach it at all.


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