Microporous insulation

Microporous insulation materials consist mainly of highly dispersed silica with a particle size of only 5-30 nm. The highly dispersed silica powder is pressed to plates, which receive heat treatment up to 800 °C, after which the plates are self-supporting and possess a micropore structure with pore diameter of 0.1pm. The addition of opacifiers to the highly dispersed silica starting material reduces the loss of heat by radiation. The dates for such insulation boards are shown in Table 18. 

The addition of opacifiers to the highly dispersed sihca starting material reduces the loss of heat by radiation. The data for such insulation boards are shown in Table 21.18. 

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Microporous insulation represents a good compromise its thermal conductivity reaches 4-8 mWrrf K-1 in a pressure range of only 0.1-1 mbar. Another advan-... 

Since the 1980s a new microporous insulation material based on silicic aerogels is in a test phase. About 60 years ago Kistler from Stanford University developed a method to produce aerogels from silicic material without shrinking them He reacted waterglass with hydrochloric acid, washed out the sodium and chloride ions from the gel, substituted the water with alcohol and dried the gel in an autoclave above the critical point. Other methods begin with tetramethoxysilane for the production of monolithic aerogels. 

The structure of aerogel is similar to the structure of a compressed fumed silica The diameter of the Si02 sphere is about 5 nm, the diameter of the pores in the aerogel is about 50 nm. Aerogels are, therefore, also excellent microporous insulation materials. 

For a long time the technical application of this microporous insulation was limited, as the material made from pressed powder was hardly workable and, for example, had to be protected through a covering made from glass fiber. 

The uses of microporous insulation materials are almost unlimited. This material can be used to protect specific areas from high temperature. It can increase the effective volume and the productivity of heated devices for the same energy consumption. 

Microporous insulation inner temperature or ceramic blanket outer temperature Tn. 354 °C. 

Stainless steel inner temperature or microporous insulation outer temperature T5 54 °C. 

Moreover, the proposed solution does not take into account any economic considerations. For example, the microporous insulation and the ceramic paper are significantly more expensive than the insulating wool. Also, the solution proposed uses the maximum allowable steel shell diameter, which may be prohibitively costly. Alternative solutions may be possible and less costly, particularly if forced convection (such as a fan) is used to draw additional heat away from the outer reactor wall. 

Batteries developed for electric vehicles employed evacuated insulation to minimize thickness and weight. Both ABB and SPL used a double-walled, evacuated thermal enclosures with either a fiber board or microporous insulation. Chemical gettering agents were placed within the enclosure to maintain the needed levels of vacuum. This type of system was the only identified design that adequately minimized heat loss while providing the necessary load-bearing capability. 

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