Thermal conductivity and characterization of compacted, granular silica aerogel
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Gibson_Thermal and SI.pdf
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Author(s)
Neugebauer, Adam Halbert
Chen, Kevin
Tang, Astera S.
Allgeier, A.
Glicksman, Leon R.
Gibson, Lorna J.
Date Issued
April 2014
Journal
Energy and Buildings
Publisher
Elsevier
Citation
Neugebauera, A., K. Chen, A. Tang, A. Allgeier, L.R. Glicksman, and L.J. Gibson. "Thermal conductivity and characterization of compacted, granular silica aerogel." Energy and Buildings 79 (August 2014), pp. 47-57.
Version
Author's final manuscript
Abstract
Monolithic silica aerogels are well known for their low thermal conductivity (approximately 15 mW/(m K)) (Aegerter et al. (Eds.), 2011. Aerogels Handbook, first ed., Springer-Verlag New York, LLC, New York, NY). Their low relative density (typically less than 5%) reduces conduction through the solid and their small pore size, typically less than one hundred nanometers, on the order of the mean free path of air, reduces conduction through air, as well as convection and radiation. As they are fragile and brittle, they are often used in a granular form in thermal insulation, with some increase in their thermal conductivity from the air between the granules. Here, we describe a technique for compacting a bed of granular silica aerogel that reduces the thermal conductivity from 24 mW/(m K) (when uncompacted) to 13 mW/(m K) (after compaction). We find that there is an optimum level of compaction to minimize the thermal conductivity: at higher levels of compaction, the contact area between the granules increases and the granules densify, increasing conduction through the solid.
MIT Department
Massachusetts Institute of Technology. Department of Architecture
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/j.enbuild.2014.04.025
