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

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dc.contributor.author Smith, Geoff en_US
dc.contributor.editor en_US
dc.date.accessioned 2010-05-28T09:48:18Z
dc.date.available 2010-05-28T09:48:18Z
dc.date.issued 2009 en_US
dc.identifier 2008007795 en_US
dc.identifier.citation Smith Geoffrey 2009, 'Amplified radiative cooling via optimised combinations of aperture geometry and spectral emittance profiles of surfaces and the atmosphere', Elsevier Science Bv, vol. 93, no. 9, pp. 1696-1701. en_US
dc.identifier.issn 0927-0248 en_US
dc.identifier.other C1 en_US
dc.identifier.uri http://hdl.handle.net/10453/9234
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 mu m and 13 mu m 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 degrees C below ambient, under a 45 degrees aperture lined with shiny aluminium, can achieve a net output power near 135W m(-2) under a clear sky. en_US
dc.language en_US
dc.publisher Elsevier Science Bv en_US
dc.relation.hasversion Accepted manuscript version en_US
dc.relation.isbasedon http://dx.doi.org/10.1016/j.solmat.2009.05.015 en_US
dc.rights NOTICE: this is the author’s version of a work that was accepted for publication in Solar Energy Materials And Solar Cells. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Solar Energy Materials And Solar Cells, [VOL 93, ISSUE 9, (2009)] DOI: http://dx.doi.org/10.1016/j.solmat.2009.05.015 en_US
dc.title Amplified radiative cooling via optimised combinations of aperture geometry and spectral emittance profiles of surfaces and the atmosphere en_US
dc.parent Solar Energy Materials And Solar Cells en_US
dc.journal.volume 93 en_US
dc.journal.number 9 en_US
dc.publocation Amsterdam en_US
dc.identifier.startpage 1696 en_US
dc.identifier.endpage 1701 en_US
dc.cauo.name SCI.Faculty of Science en_US
dc.conference Verified OK en_US
dc.for 091200 en_US
dc.personcode 730312 en_US
dc.percentage 100 en_US
dc.classification.name Materials Engineering en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US
dc.date.activity en_US
dc.location.activity ISI:000268373200039 en_US
dc.description.keywords Radiative cooling; Sky; Atmosphere; Apertures; Selective surfaces; Emittance en_US
dc.staffid en_US
dc.staffid 730312 en_US


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