Modeling of Natural Ventilation in Solar Chimney and Optimization of the Channel Profile by CFD Method

The natural ventilation in solar chimney was numerically simulated by computational fluid dynamics method and the effect of solar chimney profiles was discussed. The flow rate through a rectangular solar chimney increased with the solar chimney height. The flow pattern in the chimney was laminar flow when the chimney height was lower than a critical height and then became turbulent flow as the height further increased. When designing the solar chimney, it is important to remember that the critical chimney height should ensure the air flow in the channel could develop to be turbulent in order to get a large flow rate. As the width of the solar chimney increased, the flow rate increased to a peak value and then decreased to a minimum value and then increased again. The reason was due to the curve flow stream and uneven pressure distribution formed when the chimney width increased. A modified chimney profile of linearly tapered solar chimney could remove the reverse flow and improved the flow rate by 25%.