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Numerical simulation of a solar chimney for natural ventilation of a building: Comparison of different computational domains
Numerical simulation of a solar chimney for natural ventilation of a building: Comparison of different computational domains
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Date
2021
Authors
Trieu N Huynh
Y Q Nguyen
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Research Projects
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Abstract
Numerical simulations, particularly those based on the Computational Fluid Dynamics
(CFD) Method, have been widely employed in engineering and design, such as design of green
buildings. In this study, we investigated effects of the computational domain, a factor influencing
the accuracy of a CFD simulation, of a solar chimney, a device for natural ventilation of
buildings, on the predicted performance of a solar chimney attached to a building. Four different
domains which, in turn, included both the chimney and the house, the chimney and the inlet
length, the chimney with the horizontal inlet, and only the air channel of the chimney, were
examined. The CFD model was based on the RANS equations and RNG 𝑘 − 𝜖 turbulence
model. The chimney had different heights, gaps, heat fluxes, and the location of the heat source
in the air channel. The results show that the differences in the predicted flow rate and temperature
rises through the chimney among the domains changed with the height, gap, and the location of
the heat source. The simplest domain, which was a simple vertical rectangular channel, over –
predicted the flow rate and under – predicted the temperature rise. The main cause of its worse
performance is because of its inability to model the separation zones near the inlet of the air
channel. Therefore, it is not recommended for high accuracy – simulations. Two other simpler
domains, which included the inlet length and only the inlet, can be used when the required
accuracy is within 10.0%. The full domain consisting of both the chimney and the building is
preferred for the highest accuracy.
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Keywords
solar chimney,
natural ventilation,
CFD,
computational domain.