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The effect of surface roughness and emissivity on radiator output

Shati, A.K.A., Blakey, S.G. and Beck, S.B.M. (2011) The effect of surface roughness and emissivity on radiator output. Energy and Buildings, 43 (2-3). pp. 400-406. ISSN 0378-7788

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Abstract

The effect of altering the emissivity and the roughness of a wall behind a radiator on the radiator heat output has been studied experimentally and by using computational fluid dynamics.

The results of a 3D RNG k-epsilon turbulent model agree well with, and have the same trend as, the experimental results. The results indicate that the presence of large scale surface roughness and a high emissivity surface increases both the heat flow rate and the air velocity behind the radiator compared to a smooth shiny surface. The former increases the wall surface emissivity which causes the surface temperature of the wall to increase, effectively creating additional convective heat transfer surface. The surface roughness will increase both the surface area for heat transfer and the turbulent intensity which increase the mass transfer and free convective heat flux through the air gap.

The results indicate that the heat transfer can be increased by about 26% through the use of a high emissivity saw-tooth surface compared to a smooth shiny one. This means that using a wall surface with high roughness and emissivity behind the radiator will increase the heat output from the radiator. (C) 2010 Elsevier B.V. All rights reserved.

Item Type: Article
Copyright, Publisher and Additional Information: © 2011 Elsevier. This is an author produced version of a paper subsequently published in Energy and Buildings. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: Domestic panel radiators; Surface roughness; Surface emissivity; Heat transfer; Free convection; Radiation
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Mechanical Engineering (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 08 Apr 2011 10:10
Last Modified: 08 Apr 2011 10:10
Published Version: http://dx.doi.org/10.1016/j.enbuild.2010.10.002
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/j.enbuild.2010.10.002
URI: http://eprints.whiterose.ac.uk/id/eprint/42936

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