Polyurethane foams with microencapsulated phase change material: Comparative analysis of thermal conductivity characterization approaches

The use of thermal insulation materials is regarded as the most effective passive measure of energy savings in buildings. Rigid polyurethane foams (RPU) are commonly used as the insulation layers of opaque building envelope solutions, as well as for other applications in field of transportation, textile industry and electrical appliances, accounting for almost one-third of the polyurethane market. In the assessment of the energy performance of buildings, insulation materials, such as RPU foams have good insulating properties - low thermal conductivity - however their thermal regulation capacity can be enhanced by the incorporation of phase change materials (PCMs). In this paper, three different approaches (flux meter approach, the guarded hot plate approach and the transient plane source approach) are presented to determine the thermal conductivity of RPU foams with and without the incorporation of PCMs based on steady state method and transient method. In addition, this work presents and discusses the comparison between measurements amongst the three approaches revealing the important factors that should be considered to determinate the thermal conductivity of the RPU foams with PCMs, particularly in the temperature range during PCMs phase change transition (solid/liquid state).