The concept of nano insulation materials (NIM) is introduced to make a thermal insulation material with thermal conductivity as low as that of a vacuum insulation panel (VIP) in its pristine condition, but without the disadvantages of a VIP.
Illustration of the sacrificial template method for HSNS fabrication (Jelle et al. 2014).
Thermal conductivity has been measured for various powder samples of HSNS, where the conductivity values are typically in the range 20 to 90 mW/(mK), though some uncertainties in the Hot Disk apparatus measurement method must be further clarified. In this respect, the specific powder packing of the HSNS in the bulk condition is also an issue to address. Currently, attempts are being made to lower thermal conductivity by a parameter variation and by optimizing the inner diameter and wall (shell) thickness of the hollow silica sphere.