Vacuum insulation panels for high-temperature applications - Design principles, challenges and pathways

Vacuum insulation panels (VIPs) are predicted to play an important role in reducing thermal losses in heating/ cooling systems due to a higher thermal resistance than conventional insulation such as glass wool, polystyrene and polyurethane foam. Driven by tightening regulations and rise of environmentally conscious consumers, demand for energy -efficient domestic and industrial appliances has increased in recent years. The focus of nearly all studies published to date have been on building and refrigeration applications (<70 C-degrees). A review paper covering studies reporting high-temperature (>= 70 C-degrees) applications of VIPs and their performance requirements is yet to be published and purpose of this paper is to fulfil that knowledge gap. A critical analysis of 83 peerreviewed and reliable industrial and government reports/regulations has specific applications, properties of materials, measurement methods and computer models to predict thermophysical characteristics of VIPs have been extensively discussed. Current knowledge gaps in the development of high-temperature VIPs, technoeconomic challenges facing them and future directions to develop commercially viable VIP for hightemperature applications are presented. This study discusses the principles of design, material selection and performance parameters relevant for high-temperature (>= 70 C-degrees) vacuum insulation panels. It is concluded that opacifiers and density of core composites are the most important factors to achieve VIPs with reduced overall thermal conductivity. Methods to reduce thermal bridging effect of stainless-steel envelope are needed to be investigated. Development of robust and cost-effective performance measurement techniques and equipment are essential to produce VIPs suitable for high-temperature applications in domestic, commercial and industrial scenarios.