Effect of the surface thermal radiation on turbulent natural convection in tall cavities of façade elements

J. P. Xamán; J. F. Hinojosa; J. J. Flores; R. E. Cabanillas

doi:10.1007/s00231-008-0393-5

Effect of the surface thermal radiation on turbulent natural convection in tall cavities of façade elements

J. P. Xamán, J. F. Hinojosa, J. J. Flores, R. E. Cabanillas

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Abstract

The effect of the surface thermal radiation in tall cavities with turbulent natural convection regime was analyzed and quantified numerically. The parameters considered were: the Rayleigh number 10⁹-10¹², the aspect ratio 20, 40 and 80 and the emmisivity 0.0-1.0. The percentage contribution of the radiative surface to the total heat transfer has a maximum value of 15.19% (Ra = 10⁹, A = 20) with emissivity equal to 1.0 and a minimum of 0.5% (Ra = 10¹², A = 80) with ε* = 0.2. The average radiative Nusselt number for a fixed emissivity is independent of the Rayleigh number, but for a fixed Rayleigh number diminishes with the increase of the aspect ratio. The results indicate that the surface thermal radiation does not modify significantly the flow pattern in the cavity, just negligible effects in the bottom and top of the cavity were observed. Two different temperature patterns were observed a conductive regime Ra = 10⁹ and a boundary layer regime Ra = 10¹².

Original language	English
Pages (from-to)	177-185
Number of pages	9
Journal	Heat and Mass Transfer/Waerme- und Stoffuebertragung
Volume	45
Issue number	2
DOIs	https://doi.org/10.1007/s00231-008-0393-5
State	Published - Dec 2008

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title = "Effect of the surface thermal radiation on turbulent natural convection in tall cavities of fa{\c c}ade elements",

abstract = "The effect of the surface thermal radiation in tall cavities with turbulent natural convection regime was analyzed and quantified numerically. The parameters considered were: the Rayleigh number 109-1012, the aspect ratio 20, 40 and 80 and the emmisivity 0.0-1.0. The percentage contribution of the radiative surface to the total heat transfer has a maximum value of 15.19% (Ra = 109, A = 20) with emissivity equal to 1.0 and a minimum of 0.5% (Ra = 1012, A = 80) with ε* = 0.2. The average radiative Nusselt number for a fixed emissivity is independent of the Rayleigh number, but for a fixed Rayleigh number diminishes with the increase of the aspect ratio. The results indicate that the surface thermal radiation does not modify significantly the flow pattern in the cavity, just negligible effects in the bottom and top of the cavity were observed. Two different temperature patterns were observed a conductive regime Ra = 109 and a boundary layer regime Ra = 1012.",

author = "Xam{\'a}n, {J. P.} and Hinojosa, {J. F.} and Flores, {J. J.} and Cabanillas, {R. E.}",

year = "2008",

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doi = "10.1007/s00231-008-0393-5",

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T1 - Effect of the surface thermal radiation on turbulent natural convection in tall cavities of façade elements

AU - Xamán, J. P.

AU - Hinojosa, J. F.

AU - Flores, J. J.

AU - Cabanillas, R. E.

PY - 2008/12

Y1 - 2008/12

N2 - The effect of the surface thermal radiation in tall cavities with turbulent natural convection regime was analyzed and quantified numerically. The parameters considered were: the Rayleigh number 109-1012, the aspect ratio 20, 40 and 80 and the emmisivity 0.0-1.0. The percentage contribution of the radiative surface to the total heat transfer has a maximum value of 15.19% (Ra = 109, A = 20) with emissivity equal to 1.0 and a minimum of 0.5% (Ra = 1012, A = 80) with ε* = 0.2. The average radiative Nusselt number for a fixed emissivity is independent of the Rayleigh number, but for a fixed Rayleigh number diminishes with the increase of the aspect ratio. The results indicate that the surface thermal radiation does not modify significantly the flow pattern in the cavity, just negligible effects in the bottom and top of the cavity were observed. Two different temperature patterns were observed a conductive regime Ra = 109 and a boundary layer regime Ra = 1012.

AB - The effect of the surface thermal radiation in tall cavities with turbulent natural convection regime was analyzed and quantified numerically. The parameters considered were: the Rayleigh number 109-1012, the aspect ratio 20, 40 and 80 and the emmisivity 0.0-1.0. The percentage contribution of the radiative surface to the total heat transfer has a maximum value of 15.19% (Ra = 109, A = 20) with emissivity equal to 1.0 and a minimum of 0.5% (Ra = 1012, A = 80) with ε* = 0.2. The average radiative Nusselt number for a fixed emissivity is independent of the Rayleigh number, but for a fixed Rayleigh number diminishes with the increase of the aspect ratio. The results indicate that the surface thermal radiation does not modify significantly the flow pattern in the cavity, just negligible effects in the bottom and top of the cavity were observed. Two different temperature patterns were observed a conductive regime Ra = 109 and a boundary layer regime Ra = 1012.

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JO - Heat and Mass Transfer/Waerme- und Stoffuebertragung

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ER -

Effect of the surface thermal radiation on turbulent natural convection in tall cavities of façade elements

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