Aging of Rigid Polyurethane Foams: Thermal Conductivity of N2 and Cyclopentane Gas Mixtures

The thermal conductivity of three mixtures of nitrogen and cyclopentane is measured using a transient hot wire method, at temperatures between 315.14 and 395.89K, and pressures up to 0.53MPa. These mixtures are important in the evaluation of the evolution of the thermal insulation capacity of closed-cell polyurethane foams considering their aging during the respective applications’ total life time. The experimental thermal conductivity data are correlated with the Wassiljewa mixing rules as modified by Mason and Saxena, and predicted using extended corresponding states theory (ECST), with an average absolute deviation of 1.1 and 8.9%, respectively. The increase of the nitrogen fraction in cyclopentane–nitrogen mixtures leads to higher thermal conductivity values than has been predicted by ECST using only pure component thermal conductivity data for all measurements.