The Solar Chimney Power Plant (scpp)

The solar chimney power plant (SCPP) are designed to generate electricity from the solar radiation. A solar chimney power plant is equipped generally by one or many turbines which are designed

to extract the kinetic energy of the wind flowing upward due to the natural convection. Then, the

generator, which is coupled with the turbine, converts the wind's kinetic energy into electrical power.

Several researchers reported that the use of the solar chimney power plant is an encouraging solution to produce electrical energy. The optimization of the solar setup requires the study of the geometrical parameters such as the collector diameter, the collector roof height [1], the chimney height [2], the chimney diameter, the inclination of the roof [3] and the design of the turbine. The first prototype of the SCPP was built in Manzanares. The prototype is characterized by a height equals to 194.6 m and a collector radius equals to 122 m. In this context, Haaf et al. [4-5] developed the results of preliminary tests of the SCPP. They presented the energy audits, the collector efficiency values, the pressure losses due to friction and losses in the turbine section. Ayadi et al. [3] developed a numerical model to evaluate the performance of the solar chimney power systems while varying the collector roof angle. The authors reported that the efficiency of the solar chimney power plant increases with a negative angle of the collector roof. Xu et al. [6] analyzed numerically the influences of the solar radiation and the pressure drop across the turbine on the power output of the solar chimney power plant. From the literature, researchers have reported some configurations of the turbine layouts such as the single rotor turbine without inlet guide vanes (IGV), single rotor turbine with IGVs, counter rotating turbine without IGVs and the counter rotating turbine with IGVs. The turbo-generator of the Manzanares prototype was designed by Schwarz and Knauss [7]. The authors proposed a single rotor layout without guide vanes. Later, Gannon and Von Backstr?m [8] carried out an experimental analysis of the solar chimney turbine performance. It was reported by the authors that the total-to-total efficiency and the total-to-static efficiency are equal respectively to 85-90% and 77-80% over the concept range. Another work was presented by the same authors [9] to develop analytical equations to defining the impact of each coefficient on the efficiency on the turbine. Recently, Ming et al. [10] carried out a numerical simulation for a solar chimney power plant coupled with a five-blade turbine. The considered system is characterized by the chimney height equal to 400 m, the chimney radius equal to 30 m and the collector radius equal to 1500 m. The authors presented the impact of the rotational speed of the turbine on the average velocity of the chimney outlet, the average temperature of the chimney outlet, the pressure drop across the turbine and the mass flow rate of the system. The maximum generated power and the turbine efficiency are about 10 MW and 50%, respectively. Guo et al. [11] presented a 3D numerical simulation of a solar chimney coupling with a turbine. In their work, they have varied the rotational speed of the turbine to study the optimal operating condition of the turbine. In their study, they have taken account the influences of the incident angle of the sunlight. Results revealed that the hourly variation of the zenith angle of the sun is an important parameter to predict the annual performance of the SCPP.

Focusing on the literature, it has been noted that the most published papers highlight the effect of the geometrical parameters of the solar setup such as the collector roof height, the collector diameter, the chimney height and the chimney diameter. In this paper, we are going to focus on the study of the turbine. Especially, the effect of the turbine diameter on the flow characteristics inside a solar chimney power plant is reported. This paper is identified as important to engineers in supplying them technical solutions to enhance the ventilation within a solar chimney power plant.