Multi-scale simulation study on the hygrothermal behavior of closed-cell thermal insulation

Abstract

Closed-cell thermal insulation is one typical type of thermal insulation applied in the engineering field. However, it is observed that moisture may gradually accumulate in the insulation and highly decrease the system thermal behavior. The hygrothermal behavior depends on the mesoscopic structure and moisture distribution of the closed-cell materials. In order to investigate the impact of mesoscopic structure on the hygrothermal behavior of closed-cell insulation, a multi-scale simulation study is reported in this work. An improved random reconstruction method is first proposed to describe the structure of closed-cell insulation, and then a multi-scale thermal model is proposed to study the impact of mesoscopic structure at both mesoscopic and macroscopic scales. The trend of the results derived from the proposed multi-scale model is consistent with the experimental results, and the relevant error is lower than 10% when the degree of saturation is low. Based on the proposed models, it is found that the mesoscopic structures have significant impacts on the hygrothermal behavior of closed-cell thermal insulation at multiple scales. Both the porosity related parameters and other structure parameters are considered and discussed in detail, with sensitivity analysis provided at the end.