Thermal Performance And Service Life Of Aerogel Based Vacuum Insulation Panels

As superfine thermal insulations(thermal conductivity as low as 2 mW·m^-1·K^-1),vacuum insulation panels?VIPs?exhibit extensive prospects for application in aviation,refrigerators,cold storage and building insulation.However,the thermal performance of VIPs in buildings becomes increasingly poor with the increase in the internal pressure and vapor content.As a result,commonly used VIPs has a short service life of only 5-25 years.In order to enhance the thermal performance and prolong the service life,this paper proposed a novel VIP with aerogel panel core?i.e.aerogel based VIP?.The aerogel based VIPs were first prepared via drying at ambient pressure and evacuating techniques.The microstructure,surface area and pore size,hydrophobic angle of the aerogel based core were characterized and measured,respectively.The thermal conductivity of the aerogel composite cores was measured using a steady state plate method by a thermal conductivity TA instrument.A model of predicting the thermal conductivity of aerogel based VIPs was established based on fractal cross-sphere model,Hamilton model and Rosseland function.Using Schwab model the method of predicting the service life of aerogel based VIPs was built.The models were validated with the experimental data.Based on the models,the effects of the aerogel density and fiber content on the thermal conductivity,insulation thickness and service life were investigated.The results indicated that there exist minimum thermal conductivity and maximum service life under the variation of the fiber content.Therefore,with the aim to obtain the minimum thermal conductivity and maximum service life,the fiber content was optimized.The optimal fiber content,minimum thermal conductivity and maximum service life were predicted under the variation of the aerogel density.Furthermore,the service life of the aerogel based VIPs was plotted by a contour map under the variation of the aerogel density and fiber content.A proper range of the aerogel density and fiber content was predicted to obtain a service life over 50 years for application in buildings.This study could serve as a useful reference and guideline for aerogel based VIPs applied in building insulation for energy savings.