Investigating the Effect of Radiation Scattering and Surface Emission on Combined Convection Heat Transfer in an Enclosure with Moving Insulation Surface

Document Type : Research Article

Authors

Department of Mechanical Engineering, University of Sistan and Baluchestan, Zahedan, Iran

Abstract

In most cases, the effect of radiation is not taken into account in enclosures in which convection is taking place. However, this needs to be addressed given the many applications of radiation, including nuclear reactor design, furnaces, electrical coolers, and solar collectors. The combined convection-radiation heat transfer on the moving surface of a square enclosure with laminar flow and gray surfaces, absorber, emitter, and radiation isotropic scattering was solved by the finite volume method. The effects of scattering and emissivity of the cold wall on heat transfer, streamlines, and isothermal lines were investigated. All walls were assumed to be black surfaces except for the one on right. The radiation problem was solved by the discrete ordinates method and the absorption coefficient was assumed to be fixed at 0.1. The SIMPLER method was employed in the convection problem given the correlation of velocity and pressure fields, while the power law method was used to investigate the significance of convection and diffusion terms. The results showed although scattering does not significantly affect streamlines and ambient temperature, it reduces the heat flux through the wall thus lowering the radiation flux. The major difference in surface reflection and scattering is in the temperature distribution at the center of the enclosure away from the surface which is evident despite the change in reflection. Moreover, the greater influence of scattering on local radiation and convection Nusselt number on the lower insulation surface was shown, suggesting the cooling of the insulation surface with changing of scattering at a fixed absorption coefficient.

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References

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Amirkabir Journal of Mechanical Engineering
Volume 50, Issue 6
March and April 2019
Pages 1289-1302

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