Abo Bibliothek: Guest
International Symposium on Heat and Mass Transfer in Refrigeration and Cryogenics
September, 1-5, 1986, Dubrovnik, Yugoslavia

DOI: 10.1615/ICHMT.1986.IntSympHMTinRefCryo


ISBN Print: 978-3-54017-957-3

A Structural Model of Heat Transfer through Rigid Polyurethane Foam

pages 32-51
DOI: 10.1615/ICHMT.1986.IntSympHMTinRefCryo.40
Get accessGet access

ABSTRAKT

The low thermal conductivity of polyurethane (PUR) rigid foam is considered commercially to be one of its most important solid-state properties. Such foam can be easily fabricated on the large-scale with initial λ-values in the range 0.016-0.019 W/mK (10°C).
Although it is well known that these low initial λ-values primarily result from the production of a closed cell material incorporating a low λ-value gas, structural parameters can also play an important secondary role. For instance, both average cell-size and cellular anisotropy strongly influence the measured λ-value. In this paper a structural model of heat transfer by way of conduction and radiation is proposed with specific emphasis on the anisotropy of heat transfer via thermal conduction.
Together with a new method for the accurate determination of anisotropic cell size, this model is used in conjunction with experimentally determined, initial foam, λ-values to develop an improved structural understanding of heat transfer through commercial rigid polyurethane foam (PUR). In conclusion, an estimate of the minimum λ-value theoretically obtainable, without any change of blowing agent, is given.

Digitales Portal Digitale Bibliothek eBooks Zeitschriften Referenzen und Berichte Forschungssammlungen Preise und Aborichtlinien Begell House Kontakt Language English 中文 Русский Português German French Spain