Effects of humidity on thermal performance of aerogel insulation blankets

Actual thermal conductivity of insulation materials is subject to change over time under various environmental conditions. Particularly, insulations may degrade due to moisture absorption or condensation when they are exposed to humidity. This work presents a comprehensive investigation of aerogel blankets thermal conductivity (k-value) in humid conditions at transient and steady state regimes. Transient plane source (TPS) tests revealed that the k-value of aerogel blankets can increase by up to approximately 15% as the ambient relative humidity (RH) increases from 0% to 90% at 25 °C. In addition, a relatively long time is required, at constant T (temperature) and RH, for such enhancement. Therefore, mechanisms affecting the k-value of aerogel blankets as a function of RH and T are investigated. Also, theoretical approaches for predicting the moisture content and k-value over time are discussed, and parametric analyses are performed to identify the most affecting variables.