Numerical simulation of diurnal and annual performance of coupled solar chimney with earth-to-air heat exchanger system

Abstract

The coupled solar chimney with earth-to-air heat exchanger system can passively regulate indoor air quality and thermal environment without electricity cost and carbon emissions. One dynamic model has been established and validated for the system, and using the model this system’s diurnal and annual performances were investigated. The simulation results suggested that pipe diameter and length were more critical parameters affecting the system’s airflow rate and indoor thermal environment, compared to chimney height and solar collector length. In summer, the airflow rate was significantly different between daytime (260 m3/h) and night-time (50 m3/h). In other seasons, the airflow rate during the daytime increased to around 280 m3/h, and the one during the night-time exceeded 100 m3/h. This system could provide an acceptable airflow rate during daytime, even when solar radiation intensity was low. By the thermal inertia of the subsoil, the annual fluctuation of the air temperature at buried pipe outlet was reduced within 12.8–26.5 °C. The indoor temperature was maintained by the system within the thermal comfort range for most time, with a decreased average indoor air temperature by 4.4 °C in summer and an increased one by 6.4 °C in winter.