Optimizing thermal management in buildings: the role of mixed convection and solar chimneys

This study investigates the performance of solar chimney ventilation in multi-storey buildings under mixed convection conditions, focusing on different scenarios. The analysis covers a range of Grashof numbers from 10³ to 10⁶, with fixed Reynolds and Prandtl numbers of Re = 10 and Pr = 0.71, respectively. The system consists of a thermal chimney integrated into the building, an air inlet supplying cooler airflow, and an opening connecting the interior space to the chimney. The chimney surface is heated, while the incoming air remains cooler. Computational simulations are performed to examine the impact of mixed convection heat transfer and fluid dynamics, using partial differential equations solved through the Galerkin finite element method in Comsol Multiphysics software. The results reveal that as the Grashof number increases, the Nusselt number also rises, indicating a stronger buoyancy-driven flow and more effective heat dissipation. This emphasizes the role of temperature differences in enhancing natural convection. The study also underscores the importance of the thermal chimney's design, where the placement and size of the chimney and air inlet significantly affect convective heat transfer efficiency. The findings suggest that optimizing the chimney's geometry can reduce the need for mechanical cooling, offering a sustainable solution for energy-efficient building design.