Improved application of a solar chimney concept in a two-story building: An enhanced geometry through a numerical approach

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The energy consumption of buildings, which in large part provides comfortable conditions for occupants, in many countries is significant and increasing. Many factors need to be considered to establish comfortable conditions, and the presence of each is important for a building. One of these is ventilation which is achievable in two chief ways: mechanical ventilation and natural ventilation. Solar chimney systems enhance natural ventilation through buildings via buoyancy forces. In the present paper, an improved design for a solar chimney for a two-story building is investigated computationally. The dimensions of each floor are 8.5 m × 5 m × 3.65 m, for a floor volume of 155 m3. Initially, a two-dimensional computational fluid dynamics approach is utilized to specify the influence of changing diagonal angle on the ventilation rates of the floors and the relationship between geometric parameters of the system and ventilation rate. In the second phase of this paper, three-dimensional computational fluid dynamics approaches are used to computationally assess the improved design for the sloped solar chimney in order to determine the most effective geometry for inducing a high number of air changes per hour for the specific case. Also, the numerical approaches allow integration of the new modified geometry for a sloped solar chimney as well as assessment of the ventilation rate of the system and comparisons of the results with those for conventional geometries. The results demonstrate that changing the inclination angle of the titled surface is significant whenever the length of this part is sufficiently long. Also, it is shown that the improved geometry takes on a funnel form in order to eliminate the effects caused by dissipative flow phenomena as well as turbulence and vortices. Furthermore, it is observed that the new geometry enhances the natural ventilation rate of the building by 24% compared to conventional designs.