Load-Bearing Evacuated Fibrous Superinsulations — Improvements with Peg-Support and Metal-Coated Fibers

Abstract

Optimization of load-bearing evacuated thermal superinsulations requires a detailed investigation of two thermal loss channels: The solid conduction via contacting fibers, and the radiative heat transfer. In this paper we report two important findings which allow to further improve thermal superinsulations: (i) with metal-coated fibers we obtained extinction coefficients of several hundred m²/kg; this corresponds to a drastic reduction of radiative losses compared to the case of non-coated fibers; (ii) with peg-supported insulation systems the solid conductivity was reduced to about 0.5·10^-3 W/(m·K) at 1.15 bar external pressure; this could lead to an improvement by more than a factor of three compared to not-segmented fibrous insulations. The measurements were performed with evacuable and load-controlled guarded hot plate devices and with a FTIR spectrometer.