Thermal ventilation performance of solar chimneys: A case study

Natural ventilation (NV) is a vital passive strategy for enhancing indoor air characteristics and reducing the energy consumption of mechanical cooling systems. Among NV methods, solar chimneys use buoyancy-induced airflow to promote ventilation and thermal comfort. This study investigated the optimal inclination angle, geometric shape, and size of a solar chimney designed for the climatic conditions of Erbil City to enhance airflow efficiency and thermal performance under realistic operating conditions. A hybrid approach combining computational fluid dynamics (CFD) simulations using ANSYS Fluent and experimental validation was employed. Simulations were conducted under boundary conditions reflective of the Erbil climate, exploring three tilt angles (30°, 32°, and 34°) and six cross-sectional geometries. Results showed that a 32° inclined square chimney with a 30 cm cross-section provided the best ventilation performance. Experimentally, the maximum airflows were recorded at 0.113 kg/s (mass flow rate) and 0.0927 m3/s (volume flow rate) at 12:00 on May 11, 2025. These values closely matched CFD predictions of 0.115 kg/s and 0.094 m3/s. These figures outperform those reported in other studies with similar chimney design conditions by 21.7%.