Flow reversal effects on buoyancy induced air flow in a solar chimney

Abstract

This paper reports a numerical investigation of flow reversal effects on the buoyancy induced air flow in a solar chimney for ventilation applications over a range of controlling parameters. The reverse flow phenomenon is quantitatively examined by calculating its penetration depth. In order to suppress the reverse flow and enhance ventilation performance, a configuration with an inclined passive wall is proposed as a new design; the effectiveness of this design has been examined over the Rayleigh number range of 109⩽Ra⩽1011. It is identified that there exists an optimum inclination angle corresponding to an optimum aspect ratio at which the mass flow rate is the maximum for a given Rayleigh number. The numerical results are supported by a scaling argument and a flow visualization experiment.