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Abstract
The classification of superinsulation commonly means insulating elements with thermal resitivities greater than 3.5mxK/W. Superinsulations can be produced by evacuating a layer ofsmall diameter particles, fibers, or mixtures of powders and fibers. The small diameter particles limit gas-phase molecular collisions which reduces gas-phase conduction and reduce radiative transport. Opacifiers can be added to further decrease radiative transport. Conduction through the solid phase is reduced by minimizing particle to particle contact. The thermal testing of encapsulated superinsulations represents a challenge for the testing community because the test specimens are not homogeneous and, in general, are not the dimensions of a conventional thermal test specimen. The heat fluxes through superinsulations are much smaller than these across conventional insulation. As a result specialized equipment and calibrations are required. Currently, the most attractive applications for superinsulation are in refrigeration equipment. Efforts are underway to identify candidate uses for superinsulations in the building envelope.
The classification of superinsulation commonly means insulating elements with thermal resitivities greater than 3.5mxK/W. Superinsulations can be produced by evacuating a layer ofsmall diameter particles, fibers, or mixtures of powders and fibers. The small diameter particles limit gas-phase molecular collisions which reduces gas-phase conduction and reduce radiative transport. Opacifiers can be added to further decrease radiative transport. Conduction through the solid phase is reduced by minimizing particle to particle contact. The thermal testing of encapsulated superinsulations represents a challenge for the testing community because the test specimens are not homogeneous and, in general, are not the dimensions of a conventional thermal test specimen. The heat fluxes through superinsulations are much smaller than these across conventional insulation. As a result specialized equipment and calibrations are required. Currently, the most attractive applications for superinsulation are in refrigeration equipment. Efforts are underway to identify candidate uses for superinsulations in the building envelope.
Date
11/1995
11/1995
Author(s)
David Yarbrough; Kenneth Wilkes
David Yarbrough; Kenneth Wilkes
Page(s)
7-18
7-18
Source
Oak Ridge National Lab
Oak Ridge National Lab
Keyword(s)
superinsulation; design; development; thermal testing; encapsulated insulation; building enevelope
superinsulation; design; development; thermal testing; encapsulated insulation; building enevelope