Numerical calculation and measurement of low temperature thermal conductivity of polyurethane rigid foam

Abstract

In the structure of cold compressors, polyurethane rigid foams (PURF) are often used as important thermal insulations for large temperature gradient. Heat transfer in PURF occurs by conduction through the solid skeleton and gases trapped in cells as well as radiation. According to the actual structure and operating conditions of helium cold compressors, a heat transfer hierarchical model has been established, which can predict the apparent thermal conductivity of PURF more simply. Meanwhile the thermal conductivity of a sample PURF has been measured in the physical property measurement system from 4.4K to 300K.