Abstract:
The solar chimney (or solar updraft tower) consists of a
circular solar collector, a tower in the center of the collector,
and turbines installed in the collector output or the tower
entrance. The solar radiation passes through the translucent
collector, reaches the ground surface and heats it. The air
within the device is heated by the radiation emitted by the
ground and by convection currents formed under the collector.
The thermal energy is stored in the absorber layer of the ground
when there is incidence of solar radiation and it is released from
the ground when solar radiation is low. The density difference
between the hot air inside the device and the ambient air creates
convection currents that drive the air in the collector from the
base to the top of the tower. Finally, the airflow in the tower
drives the turbines which are coupled to electrical generators.
The environmental winds influence the performance of the
solar updraft towers in three main ways: heat losses by
convection from the outer surface of the collector to the
environment, heated air drag out of the cover and drag on the
top of the chimney generating a suction effect and enhancing
the upward flow in the tower. This work studied the influence
of crosswinds on the system flow conditions through a
numerical analysis using CFD. Results indicate that an increase
on the environmental crosswinds speed from 0 to 25 m/s
decreased the outlet temperature of the device in 0.3% and
increased the outlet velocity in 50.26%, increasing the energetic
efficiency of the device in 56.31%.
Description:
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.
