Abstract
The use of renewable energy, particularly in the context of increasing environmental concerns and the depletion of fossil fuel resources, has gained significant importance. One of the promising methods for harnessing solar energy is the solar chimney system, which drives airflow using solar radiation to generate energy. Despite its high potential, the actual performance of solar chimneys in experimental tests often does not match predictions from numerical simulations. The thermal and hydrodynamic behaviour within the collector and chimney plays a crucial role in determining system performance, as heat transfer mechanisms and flow development directly influence pressure losses and overall airflow delivery. The results of this study indicate that the primary reason for this discrepancy is the formation of secondary flows and vortices within the collector and chimney. These swirling flows increase hydraulic losses, reduce airflow velocity, and decrease the uniformity of the upward flow, ultimately lowering the overall system efficiency. In this research, three experimental solar chimney setups and numerical modelling were employed to identify and analyse secondary flows, revealing that these flows originate at the collector inlet and persist up to the chimney entrance. The findings also demonstrate that collector geometry, inlet height, and divergence angle significantly influence the intensity and direction of secondary flows, and consequently, the overall system performance. Optimizing the collector angle and reducing the inlet height can mitigate vortex formation and backflows, thereby enhancing system efficiency. These results highlight the critical importance of controlling secondary flows in solar chimney design to achieve optimal performance. Furthermore, the insights gained from this study provide guidance for practical system design, effective utilization of solar chimneys, and a foundation for future research on advanced collector configurations and performance improvement under diverse climatic conditions.
Abstract by the authors, reproduced under the CC BY 4.0 licence. Original publication via the link below.