STP1116: A Review of Techniques for Improved Foam Conductivity: Reducing Radiation Heat Transfer, Limiting Aging and Inclusion of Vacuum Elements

    Glicksman, LR
    Professorgraduate students, Thermal Science and Building TechnologyMassachusetts Institute of TechnologyMassachusetts Institute of Technology, CambridgeCambridge, MAMA

    Burke, M
    Professorgraduate students, Thermal Science and Building TechnologyMassachusetts Institute of TechnologyMassachusetts Institute of Technology, CambridgeCambridge, MAMA

    Marge, A
    Professorgraduate students, Thermal Science and Building TechnologyMassachusetts Institute of TechnologyMassachusetts Institute of Technology, CambridgeCambridge, MAMA

    Mozgowiec, M
    Professorgraduate students, Thermal Science and Building TechnologyMassachusetts Institute of TechnologyMassachusetts Institute of Technology, CambridgeCambridge, MAMA

    Pages: 23    Published: Jan 1991


    Abstract

    To comply with international agreement closed cell polyurethane and polyisocyanerate foams must be made with blowing agents which minimize ozone depletion in the stratosphere. Candidate blowing agents have higher vapor conductivities resulting in lower R values for the foams. This paper reviews recent results of research at M.I.T. sponsored by the Department of Energy and the Environmental Protection Agency to find means to recover high R values. Use of small opaque particles or smaller foam cells reduces the radiative transfer in foams which is usually one third of the total heat transfer at standard conditions. The thermal aging of foams made with new blowing agents is a function of the permeability which has been measured for several new materials. The rate of aging can be reduced by proper use of diffusion barriers on the foam surface. The inclusion of vacuum elements in foam should increase the overall R value. A key problem is to find packaging materials for the vacuum elements which preserve the vacuum over the insulation life while not causing substantial secondary heat transfer around the circumference of the element.

    Keywords:

    foam, conductivity, heat transfer, foam aging, vacuum insulation


    Paper ID: STP16350S

    Committee/Subcommittee: C16.30

    DOI: 10.1520/STP16350S


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