Numerical Study of Solar Chimney Operation in a Two Story Building

In the present study a CFD model is developed for the examination of natural ventilation in a two store building with a solar chimney. The steady-state transport equations for the vector and scalar quantities (velocity vectors, turbulence, energy and spectral intensity of radiation) are solved numerically by a FV numerical method. The turbulent nature of the flow is simulated by the two equation k-ω high Reynolds model while for the incident radiation is used the Discrete Ordinates (DO) model. The model efficiently renders the buoyancy effects inside the building, through density variation caused by temperature raise. The radiation modelling takes into account the thermal and optical spectral properties of materials. The developed numerical model was validated against published works for relative flows. Three modifications of the basic 2D geometry were examined in order to exploit the functionality design of a solar chimney. The better performance was achieved with the simpler design which has single openings connecting the solar chimney and the ventilated rooms, while the ventilation rate was compared with analytical models. 2D simulations' results can be used safely as indication about the solar chimney qualitative performance while they underestimate the mass flow rate in comparison with equivalent 3D approaches. The solar chimney operates better at morning and afternoon, while the worst operation is observed at the noon of June, as far it concerns the ventilation of the whole building