Last ned (Gratis)

Abstrakt

Vacuum insulation panels (VIP) is a high performance thermal insulation material solution
with thermal conductivity values reaching as low as 4.0 mW/(mK). With time the thermal
performance of the VIPs will degrade as moisture and gas permeate through the barrier
envelope of the panels. To better evaluate these ageing effects, accelerated ageing
experiments are needed. VIPs consist of a porous core of pyrogenic silica (SiO2) and a gas
and vapour tight envelope. The external factors that are found to contribute most to ageing of
VIPs are temperature, moisture and pressure.
Several experiments have been initiated to evaluate the acceleration effects by the application
of severe temperature, moisture and pressure conditions, including:
1. Thermal ageing at 80°C for 180 days according to CUAP 12.01/30
2. Exposure to cyclic climate in a vertical climate simulator according to NT Build 495. One
VIP sample is fully exposed in the simulator and one is placed in a wooden frame
structure.
3. Exposure to high vapour pressure by storage at 70°C and 90-100 % RH for 90 days.
The increases in thermal conductivity during ageing were relatively small compared to the
initial thermal conductivity of the VIPs, which is in agreement with the theoretical
predictions. The temperature and moisture experiment seemed to achieve a rather large
acceleration effect.
In addition, the thermally aged VIP and the exposed VIP in the climate simulator show
physical alterations. E.g. swelling, curving and delamination of the outer fire protection layer
are observed.

Referanser

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