A predictive model for airflow in a typical solar chimney based on solar radiation

A solar chimney is an important green architectural element that aides the ventilation, heating and cooling of buildings. The proper design of a solar chimney requires a reliable model to estimate the airflow rate generated by solar radiation. Previous analytical models are based on inputs such as temperature, density or heat supply, which are difficult to predict the ventilation performance of a solar chimney at the preliminary design stage. This paper presents a new predictive model for the airflow rate in a typical solar chimney based on inputs such as incident solar radiation intensity and the emissivity of the glass cover considering both room and chimney cavity configurations. This model is developed after obtaining the predictive model of heat gain ratio of air in the gap. In the new predictive model, the airflow rate is expressed explicitly as a function of incident solar radiation intensity, internal heat source intensity, the emissivity of the glass cover and geometrical parameters. This model is verified by using experimental data in the literature. Simple in form, the predictive model has the potential to improve upon existing engineering designs. It is very convenient to estimate the ventilation performance of a solar chimney according to incident solar radiation intensity.