Thermal performance and service life of vacuum insulation panels with aerogel composite cores

As a type of superfine thermal insulations, vacuum insulation panels (VIPs) have already been extensively applied in insulating refrigerators, cold storages and building envelopes. However, their thermal insulation performance becomes poor with the increase of internal pressure, which results in a short service life of 5-25 years for commonly used VIPs. To enhance their thermal performance and prolong their service life, VIPs with fiber felt/silica aerogel composite cores were prepared. The microstructure and thermal conductivity of the as-prepared core material were experimentally investigated. Based on the experimental results, theoretical models for predicting the thermal performance and service life of VIPs were firstly developed. By using the models the effects of aerogel density (50-200 kg m−3) and fiber content (0-20 vol.%) on the thermal performance and the service life of VIPs with aerogel composite cores were studied. The results indicated that a minimum insulation thickness with 5.6 mm was obtained by optimizing the fiber content for a maximum U-value of 0.6 W m−2 K−1 in accordance with the building efficiency standard of the cold area in China of the energy efficiency of public buildings (GB 50189-2015). Finally, the simultaneous effects of the aerogel density and fiber content on service life were further explored by using the service life contour. A long service life with over 50 years was achieved for VIPs with aerogel composite cores, which could promote their applications in building thermal insulation for energy efficiency.