An empirical model to predict the performance of typical solar chimneys considering both room and cavity configurations

The solar chimney is a reliable passive ventilation system that can largely reduce the energy requirements with both low costs and maintenance for buildings to overcome the current energy crisis. To optimize its design, an empirical model is developed to predict the performance of typical solar chimneys considering both room and chimney cavity configurations using easily acquired inputs. Fire Dynamics Simulator (FDS) as an excellent and open-source tool to solve heating, ventilation and air conditioning problems is selected for this study. The numerical modelling of FDS was first validated by previous experimental data, and then used to develop the empirical model. In this model, a coefficient describing room and chimney configuration (e.g., room opening, inlet and outlet of cavity) is proposed. It is shown that room size (length, width and height) and opening location have limited influence on performance. Also the radiation from hot walls can be ignored when compared to convection heat transfer between the hot walls and the air inside the cavity. This study provides key knowledge to optimize the design of solar chimneys in energy saving for buildings.