Solar chimney optimization for enhancing thermal comfort in Egypt: An experimental and numerical study

Air motion can be induced in naturally ventilated buildings using passive solar chimneys. This work aimed to optimize solar chimney design to maximize indoor air velocity induced by natural convection, with a particular emphasis on thermal comfort. A three-dimensional, quasi-steady computational fluid dynamics (CFD) model was established for the prediction of buoyant air flow using the renormalization group (RNG) k-epsilon turbulence model. In order to validate the CFD model, experiments involving an inclined solar chimney attached to a single room were performed. The experimental results agree reasonably well with the CFD calculations, with a 5.14% deviation between the values. Moreover, a Multi-Objective Genetic Algorithm (MOGA) coupled with Design of Experiments (DOEs) and the Response Surface Method (RSM) was employed to derive the optimal solar chimney design for the enhancement of indoor air motion. The optimization results reveal that the maximum indoor air speed in the living zone is achieved using a solar chimney of 1.85 m height, 2.65 m width, 75 degrees inclination angle, and 0.28 m air gap. Sensitivity analyses indicate that solar chimney width is the most influential parameter, followed by inclination angle and then air gap, while the solar chimney height has a negligible effect. The proposed solar chimney is able to passively induce air motion of up to 0.28, 0.47, and 0.52 m/s at mean solar radiation values of 500, 700, and 850 W/m(2), respectively. These elevated air velocities are capable of enhancing thermal comfort upper limits by removing sensible and latent heat from the body.