Theoretical model for high-rise solar chimneys and optimum shape for uniform flowrate distribution

Abstract

Solar chimneys (SCs) are effective in inducing natural ventilation. However, extending SCs from low-rise to high-rise buildings causes non-uniform flowrate distribution among storeys, where the flowrates on the lower storeys can be 300 % higher than those on the higher storeys. This paper aims to improve the uniformity of flowrate distribution among storeys in high-rise SCs up to 40 storeys. A concise one-equation theoretical model was derived to predict the flowrate distribution among storeys. This theoretical model was well verified by an experimentally validated numerical model. Furthermore, based on this flowrate distribution equation, the optimum shape (i.e., square-root-law (SRL) structure) was derived and proposed for high-rise solar chimneys to achieve a highly uniform flowrate distribution. Numerical simulations showed that the SRL structure reduced the relative difference in flowrate among storeys from 330.6 % to 15.0 % in a 20-storey SC. The findings of this study can provide guidance on how to design optimum high-rise SCs and maximise its ventilation performance.