Improving Electricity Production in Solar Chimney Power Plants with Sloping Ground Design: An Extensive CFD Research

Unlike other solar energy systems, solar chimney power plants (SCPPs) allow power output even when there is no sun. SCPPs are promising with their simple structure and 24-hour electricity production potential. Massive pressure tower in the system maintains continuous energy generation irrespective of climatic conditions. Solar energy harnessed by the huge collector area is transmitted to the gorund material for sensible or latent heat storage purpose, and this stored energy during daytime yields to enhanced thermal and buoyant effects even after sunset. SCPPs are also in the centre of interest owing to their eco-friendly operation not causing any CO2 emission. Design aspects in SCPPs are widely studied numerically by researchers. However, geometric design factors are merely analysed for collector and chimney, and very few attempts are done for the ground design. In the present work, a new design for ground is proposed in order to improve the energy stored in the ground material, and the upward movement of the air flow in the system from collector to chimney by changing the ground geometry. The upward movement of the air under the collector is enhanced with the new design created by inclining the ground at a distance of 21 m from the chimney inlet to a certain distance from the collector inlet. ANSYS WORKBENCH based CFD analysis is carried out based on the geometric dimensions of the Manzanares pilot plant. Analyses are based on a 90° 3D CFD model for the purpose of time saving in iterations. The CFD model is supported by RNG k-? turbulence and DO (discrete ordinates) solar ray tracing models. After CFD results are verified with the experimental data, simulations are repeated for different designs and the ideal design is achieved. It is observed that the maximum air flow velocity, which is 14.202 m/s on the horizontal ground for the reference case, is improved by 34.1% in the new design to 19.046 m/s. In addition, it is seen that the power output of the reference case (54.333 kW) is enhanced by 23.04% to 66.855 kW