STP922

    Effects of Moisture on the Thermal Performance of Spray-Applied Insulation Systems

    Published: Jan 1987


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    Abstract

    The absorption of moisture in insulation systems can produce a degradation of the thermal performance of these systems. These effects have been studied with both laboratory and field testing methods in fiberglass and cellulose spray-applied insulation systems. In the laboratory, transient thermal resistance and moisture gain of horizontal, 25-cm-square, 5-cm-thick specimens have been measured. The upper metal substrate surfaces of the specimens were maintained at 10°C, and the bottom free surfaces were exposed to a flow of air at 30°C and 10 to 50% relative humidities. Moisture gain was measured by periodic weighing of the specimens, and the thermal resistance was calculated from thermocouple and heat-flow sensor readings. The fiberglass and cellulose materials gained as much as 5 and 8% moisture by volume, respectively, when exposed to air at 50% relative humidity; much lower moisture gains were observed at lower air humidity levels. The process of vapor flow toward the substrate surfaces contributed significantly to the apparent thermal conductivity. Field measurements of thermal resistances were made on horizontal 1.2-m-square, 5-cm-thick specimens. The corrugated metal substrates were exposed to outdoor ambient conditions while the bottom free insulation surfaces were exposed to a steady flow of indoor air. Field measurements were made under both summer and winter conditions, and no moisture contribution to the thermal conductivity was noted.

    Keywords:

    insulation systems, thermal performance, spray-applied insulations, moisture, thermal insulation


    Author Information:

    Benner, SM
    Assistant professor of chemical engineering and professor of physics and atmospheric science, Drexel University, Philadelphia, PA

    Modi, D
    Member of technical staff, Singer Co., Cherry Hill, NJ

    Larson, DC
    Assistant professor of chemical engineering and professor of physics and atmospheric science, Drexel University, Philadelphia, PA


    Paper ID: STP18491S

    Committee/Subcommittee: C16.40

    DOI: 10.1520/STP18491S


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