Amplified radiative cooling via optimised combinations of aperture geometry and spectral emittance profiles of surfaces and the atmosphere

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Show simple item record Smith, GB 2010-05-28T09:48:18Z 2009-09
dc.identifier.citation Solar Energy Materials and Solar Cells, 2009, 93 (9), pp. 1696 - 1701
dc.identifier.issn 0927-0248
dc.identifier.other C1 en_US
dc.description.abstract Net thermal radiation cooling, from surfaces at sub-ambient temperatures, to the night sky is amplified if the aperture to the sky is partially blocked with heat mirrors. The temperature at which radiation loss stagnates (the effective sky temperature) falls continuously as the aperture closes and is derived in terms of the aperture size and the spectral properties and temperatures of the atmosphere and of the emitting surface. Cooling surfaces must have high absorptance between 7.9 μm and 13 μm where the atmosphere is most transparent. The best response for the remainder of the Planck radiation spectrum surprisingly switches between two spectral extremes at a temperature which falls as the aperture gets smaller. A perfect absorber is best above this switch, while surfaces which reflect all of this radiation are best below it. A simple formula is presented for the cross-over temperature as a function of aperture size. With known material properties plus representative non-radiative heat gains a high emittance surface is generally better except when heat mirrors are not used. A known high emittance roof paint at 10° C below ambient, under a 45° aperture lined with shiny aluminium, can achieve a net output power near 135 W m-2 under a clear sky. © 2009 Elsevier B.V. All rights reserved.
dc.language eng
dc.relation.hasversion Accepted manuscript version en_US
dc.relation.isbasedon 10.1016/j.solmat.2009.05.015
dc.title Amplified radiative cooling via optimised combinations of aperture geometry and spectral emittance profiles of surfaces and the atmosphere
dc.type Journal Article
dc.description.version Published
dc.parent Solar Energy Materials and Solar Cells
dc.journal.volume 9
dc.journal.volume 93
dc.journal.number 9 en_US
dc.publocation Amsterdam en_US
dc.identifier.startpage 1696 en_US
dc.identifier.endpage 1701 en_US SCI.Faculty of Science en_US
dc.conference Verified OK en_US
dc.for 0912 Materials Engineering
dc.personcode 730312
dc.percentage 100 en_US Materials Engineering en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US en_US
dc.location.activity ISI:000268373200039 en_US
dc.description.keywords Apertures
dc.description.keywords Atmosphere
dc.description.keywords Emittance
dc.description.keywords Radiative cooling
dc.description.keywords Selective surfaces
dc.description.keywords Sky
pubs.embargo.period Not known
pubs.organisational-group /University of Technology Sydney
pubs.organisational-group /University of Technology Sydney/Faculty of Science
pubs.organisational-group /University of Technology Sydney/Strength - Materials and Technology for Energy Efficiency
utslib.copyright.status Open Access 2015-04-15 12:23:47.074767+10
pubs.consider-herdc true
utslib.collection.history School of Physics and Advanced Materials (ID: 343)
utslib.collection.history General (ID: 2)

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