Thermal properties improvement of multilayersuper insulators based on novolac aerogel

In human-made materials, aerogels have the least thermal conduction coefficient. The least thermal conduction, which aerogels can have, is equivalent to air conduction, about 0.021W/mK. In some applications, lowest conductions is to be needed. In this study, novolac aerogles are used as spacer, for designing and making multilayer super insulators with aluminum foil reflective layers. The performance of these insulators, are extremely depends on density, porosity and the size of pores in aerogel and number of layers in the overall thickness of insulator. In this study, for decreasing effective thermal conduction of multilayer insulations, tow parameters of density of aerogel and ratio of number of layers to thickness of insulator (layer density), are examined in 25 ˚C to 200 ˚C boundary conditions. First, by assessment of aerogel novolac density effect on thermal conduction, aerogel with density of 0.076 g/cm3 was chosen as the best spacer. In the next part, ratio of 25 layer per centimeter of thickness was chosen as the best layer density. Finally, by making multilayer super insulators, based on this results, an insulator with 5×10-4W/mK effective thermal conductivity was obtaind without evacuation of spacer.