Computational fluid dynamics simulation and optimization of the fluid flow behaviour in a multi-stage solar updraft tower using a new chimney design

This work proposes a new chimney design that allows for the development of a multi-stage solar updraft tower (SUT). The new design consists of two successive divergent chimneys. A 3D model was established to inspect the air flow behaviour within the SUT in six configurations: four multi-stage systems with four divergence angles of the second stage were compared to the simple conventional SUT and the simple SUT with a divergent chimney. The new SUT performs better than the conventional one, while the two-stage solar tower multiplied the system efficiency. Two high-velocity zones appeared for the two-stage SUT, whereas one zone occurred for the conventional system. The velocity in the two zones achieved a significant value, like that of the conventional system. In addition, the second stage's divergence angle directly impacts the velocity value inside the two stages. The static pressure distribution varies with the change in chimney design. The depression area occurs twice for the multi-stage SUT in the inlet of each stage.