The effect of surface roughness and emissivity on radiator output

Research output: Contribution to journalArticlepeer-review

Authors

Colleges, School and Institutes

External organisations

  • Sheffield University
  • Department of Mechanical Engineering

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-ε 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.

Bibliographic note

Copyright: Copyright 2011 Elsevier B.V., All rights reserved.

Details

Original languageEnglish
Pages (from-to)400-406
Number of pages7
JournalEnergy and Buildings
Volume43
Issue number2-3
Publication statusPublished - Feb 2011

Keywords

  • Domestic panel radiators, Free convection, Heat transfer, Radiation, Surface emissivity, Surface roughness