Development of Accelerated Test Method to Evaluate the Long-Term Thermal Performance of Fumed-Silica Vacuum...

Area of Science:

• Materials Science
• Thermal Engineering
• Building Science

Background:

• International standards require lengthy 180-day accelerated tests for vacuum insulation panel (VIP) long-term thermal performance.
• Evaluating the 25-year thermal performance of VIPs is crucial for energy efficiency in buildings.

Purpose of the Study:

• To develop a simplified and faster accelerated testing method for fumed-silica VIPs.
• To accurately predict the long-term thermal performance of fumed-silica VIPs.

Main Methods:

• Proposed a highly accelerated test method using 80 °C and 70% Relative Humidity (RH).
• Compared results with existing accelerated methods (50 °C and 70% RH).
• Analyzed inner-pressure increase rates and derived long-term thermal conductivities.

Main Results:

• Inner-pressure increase rates after 70 days under highly accelerated conditions matched 180 days under accelerated conditions.
• Estimated long-term thermal conductivities were 0.0076 W/m·K (highly accelerated) and 0.0054 W/m·K (accelerated).
• The proposed method allows for approximately 70-day conditioning for reliable evaluation.

Conclusions:

• The developed highly accelerated method provides a significantly faster evaluation of fumed-silica VIPs' long-term thermal performance.
• This simplified method enables efficient production of VIPs with consistent thermal properties.
• The 70-day test under 80 °C and 70% RH is a viable alternative for international standard evaluations.