NATURAL CONVECTION HEAT TRANSFER WITHIN VERTICALLY ECCENTRIC DOMED SKYLIGHTS CAVITIES

Domed skylights are important architectural design elements to deliver daylight and solar heat into buildings and connect building’s occupants to outdoor. However, most of building energy simulation programs do not cover such skylights to quantify their energy performance when installed in buildings. This paper presents a numerical study on natural laminar convection within vertically eccentric domed cavities when heated from the exterior surface. Both interior and exterior surfaces are held at uniform temperatures. A commercial CFD package employing the control volume approach is used to solve the laminar convective heat transfer within the cavity. The obtained results showed that the flow is mono-cellular for small and moderate heating intensities as depicted by the Grashof number. For high Grashof numbers, small vortex cells appear within a larger vortex cell at the lower part of the cavity. The multi-cellular flow increases heat transfer. The critical gap spacing that yields the maximum heat transfer was quantified for several dome profiles. KEYWORDS Natural laminar convection; domed cavity; domed skylight, eccentric domed cavity NOMENCLATURE k Fluid thermal conductivity Lmax Maximum gap thickness Lmin Minimum gap thickness L Local gap thickness P Pressure P * Dimensionless pressure qcond Pure conduction heat transfer qi Convection heat transfer from interior surface qo Convection heat transfer from exterior surfac