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

Abstract

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-ε 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.

Impacts of Ground Slope on Main Performance Figures of Solar Chimney Power Plants: A Comprehensive CFD Research with Experimental Validation

“…Convergence, coherency, and reliability are notably affected by the aforesaid effects as well as discretization techniques. If the previous numerical findings of other researchers given in Figure 4 are examined, it is observed that the numerical approach adopted in the present study is more adaptive to the experimental data due to the abovementioned factors [32].…”

Impact of Ground Heat Source Addition on Main Performance Parameters of Solar Chimney Power Plants: A Numerical Study

“…Since Ra, which is the critical dimensionless number for natural convection, is greater than 10 9 , which is the critical value for the MPP, the flow is considered turbulent, and the RNG k-e turbulence model, which gives the best results in rotating flows, is used in the analysis [15]. The Ra number equation and the equations of the turbulence model are as follows, respectively [42]:…”

Modeling the Thermal Performance for Different Types of Solar Chimney Power Plants

“…However, in most studies, transmission phenomena in the power plant have been modeled in a reliable state [22][23][24]. While the constraints of accumulation, especially the accumulation of heat in the surface layers of the earth and the chimney wall, can cause a significant error in the simulation results [25].…”