Abstract:
The solar chimney allows natural ventilation to be achieved during periods
when the wind velocities are low and the difference between internal and
external air temperatures is minimal. The correct design of such building
components requires that designers have appropriate design tools available to
them that are both effective and easy to use. The aim of this project was to
evaluate design tools currently available and if appropriate to provide a tool
that would allow the effects of variations in key physical parameters to be
evaluated.
Two design tools are currently available to designers; zonal models and CFD
programmes. Both of these were however found to be unsuitable for the
evaluation of the performance of a solar chimney. Zonal models assume that
the air within a zone is fully mixed which results in the effects of variations in
physical parameters on the mass flow rate being incorrectly predicted. CFD
programmes require validation of any models developed before confidence in
the predictions can be established, it was found however that data for such
validation was not available for realistic flow configurations.
An experimental rig was designed and tested to ensure that the uncertainty in
the data produced was both minimised and accurately quantified.
A detailed review of the sensitivity of a CFD programme to model and input
variables was undertaken allowing development of an appropriate model.
Comparison of the results of the experimental investigation and CFD
predictions showed that the CFD programme, utilising the ke turbulence
model accurately predicted air flow rates through a solar chimney across a
range of key physical parameter variations.
Within the limits of the validity determined for the CFD model, a detailed
parametric investigation was then undertaken.
The result of the parametric investigation was the development of a design tool
appropriate for the determination of the effects of variations of the key physical
variables on the mass flow rate through a solar chimney.
