Numerical and experimental study of the impact of conical chimney angle on the thermodynamic characteristics of a solar chimney power plant

The goal of this paper is to study and optimize the conical chimney angle (alpha) of a divergent solar chimney power plant (DSCPP) by using CFD technique. The local airflow characteristics were analyzed in four configurations with different conical angles alpha = 0 degrees, alpha = 3 degrees, alpha = 6 degrees and alpha = 9 degrees. The first design is validated experimentally by using a pilot prototype build at the National School of Engineers of Sfax, Tunisia. In addition, some experimental results of the temperature, the velocity and the power output were presented during a typical day. A novel mathematical correlation was developed to prove the effect of the conical angle and the DSCPP scale on the power output. In fact, the relationship between the optimum conical angle and the system scale was performed based on both quadratic and cubic regressions. The computational results ensure that the conical chimney angle presents a parabolic tendency with the turbulence airflow characteristics and the power output. The performance of the DSCCP was degraded since the conical angle is greater than alpha = 3 degrees. Furthermore, the optimum angle decreases with an increasing system scale. A commercial solar chimney with a conical angle around alpha = 1 degrees presents an efficient system.