Numerical Investigation of Coupled Surface Radiation and Natural Convection in a Triangular Shaped Roof (Gabel Roof) under Winter Conditions

Abstract:

In the building, roof is a major element contributing to the space thermal load. Due to its importance, this component has been widely studies in the literature and under various climatic conditions. In this paper, a numerical study was carried out for the coupling of natural convection and surface radiation heat transfer in a triangular shaped roof with eave (Gabel roof) for cold climates. The numerical solution is obtained using a finite volume method based on the SIMPLER algorithm for the treatment of velocity-pressure coupling. Concerning the radiation exchange, the working fluid (air) is assumed to be transparent, so only the solid surfaces (assumed diffuse-grey) give a contribute to such exchange. Governing parameters on heat transfer and flow fields are Rayleigh number (Ra), aspect ratio (A) and eave lengths (e^*). Numerical results are obtained to display the isotherms, streamlines and the heat transfer rate in terms of local and average Nusselt numbers. We found that the production of several circular cells is proportional to the decrease of aspect ratio and the increase of Rayleigh number. In addition, the heat transfer is much more pronounced in the presence of thermal radiation.

• Periodical: Defect and Diffusion Forum (Volume 392)
• Pages: 200-217
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.392.200
• Online since: April 2019
• Authors: Abdel Illah Amrani*, Nadia Dihmani, Samir Amraqui, Ahmed Mezrhab
• Keywords: Building, Gabel Roof, Natural Convection, Surface Radiation, Triangular Shaped Roof

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