Thermal resistance of perlite-based evacuated insulations for refrigerators

Technical Report · Mon Sep 01 00:00:00 EDT 1986

OSTI ID:5044066

Yarbrough, D W; Graves, R S; Weaver, F J; McElroy, D L

The thermal resistances of two side panels which were cut from imported refrigerators and of a single, newly manufactured evacuated packet were measured using a linear heat flow technique. The panels were composites of foamed-in-place urethane surrounding perlite-filled evacuated packets. One panel contained an apparently punctured packet and was found to have a thermal resistance at 300 K in the range 0.617 to 0.950 m/sup 2/ x K/W for 2.54 cm (3.5 to 5.4 ft/sup 2/ x h x /sup 0/F/Btu for 1.0 in.). A second apparently undamaged packet had thermal resistances in the range 1.66 to 2.45 m/sup 2/ x K/W for 2.54 cm (9.4 to 13.9 ft/sup 2/ x h x /sup 0/F/Btu for 1.0 in.). The internal pressure of the undamaged packet was calculated to be in the range 100 to 1000 Pa by comparing packet thermal properties with apparent thermal conductivities, k/sub a/, obtained as a function of pressure for the perlite removed from the damaged packet. The thermal resistance for the single evacuated packet was determined by framing the packet with polyisocyanurate of known k/sub a/ and measuring heat flow across the assembly. This yielded a thermal resistance of 18.1 ft/sup 2/ x h x /sup 0/F/Btu for 1.0 in. The k/sub a/ values of two domestic perlites and the perlite removed from the punctured refrigerator packet were measured at 300 K and pressures from atmospheric down to about 5 Pa using a radial heat flow technique. Near 1 atm the k/sub a/ of fine domestic perlite at a density of 246 kg/m/sup 3/ was 5% above that of the foreign perlite at 225 kg/m/sup 3/, but the domestic product had a k/sub a/ up to 45% greater than that of the foreign product under vacuum. The mean particle diameter of the imported perlite was near 13 ..mu..m, while the mean particle diameter of the domestic product was near 21 ..mu..m.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5044066
• Report Number(s): ORNL/CON-215; ON: DE87001591
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
36 MATERIALS SCIENCE
PERLITE
THERMAL CONDUCTIVITY
REFRIGERATORS
THERMAL INSULATION
EXPERIMENTAL DATA
PRESSURE DEPENDENCE
DATA
IGNEOUS ROCKS
INFORMATION
NUMERICAL DATA
PHYSICAL PROPERTIES
ROCKS
THERMODYNAMIC PROPERTIES
VOLCANIC ROCKS
320100* - Energy Conservation
Consumption
& Utilization- Buildings
360603 - Materials- Properties