Aerogels thermal insulation windows

Thermal Insulation. In addition to their low thermal conductivity, as discussed in the section above, siUca aerogels can be prepared to be highly transparent in the visible spectmm region. Thus, they are promising materials as superinsulating window-spacer. To take further advantage of its... 

Silica aerogels, a newly developing type of material, also have been produced as thermal insulations with superinsulation characteristics. The nanometer-size cells limit the gas phase conduction that can take place. The aerogels are transparent to visible light, so they have potential as window insulation. The use of superinsulations at present is limited by cost and the need to have a design that protects the evacuated packets or aerogels from mechanical damage. 

Figure 4 Spectral specific extinction (absorption) of pure silica aerogel (dashed), silica aerogel doped with 5% carbon black (dotted), and RF aerogel (solid). Note that the transmission window in pure silica aerogel between 3 and 5 j4m leads to a dramatic increase in thermal radiative transport and renders pure Si02 aerogels ineffective as thermal insulators above 100°C. The integration of an opacifier markedly improves the thermal resistance of Si02 aerogels.

Thermal insulation for windows Aerogel window spacers, solar collector coatings... 

Aerogels are one of the strongest, lightest and yet transparent (although non-polymeric) building products with 99% of empty volume, typically produced from silicone or carbon with equivalent thermal insulating efficiency equal to 10-20 glass window panes [47]. 

Aerogels are particularly well suited for insulation applications because of their exceptionally low density, thermal stability, and high transparency. In fact, they can have a thermal conductivity only one-third that of polyurethane or polystyrene foam, and with recent process improvements that reduce the cost of manufacmre by an order of magnitude their practical use in certain construction applications is now feasible [31]. The insulating properties can be enhanced through the addition of IR opacifiers [32]. The high transparency of aerogels makes them suitable as insulation in windows or translucent panels. 

The proposed appUcatirms of aerogel are numerous and vary a great deal yet most remain uiu ealized. Commercial applications such as thermal window insulatirHi, acoustic insulation, optical coatings, capacitor electrodes, low dielectric constant layers in integrated circuits, piezoelectric transducers, and catalytic supports have all been proposed, but little in the way of actual use has resulted [1, 5-11]. However, sihca aerogel monohths have been used extensively in Cerenkov radiation detectors in high-energy physics experiments [12-16]. 

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