Mathematical Modelling of the Performance of a Solar Chimney Power Plant with Divergent Chimneys

Abstract

Chimney is a critical component influencing the performance of a Solar Chimney Power Plant (SCPP). An enhancement on the power output of SCPPs with divergent chimneys was observed in a number of experimental and numerical studies using Computational Fluid Dynamic (CFD) models. In this paper, a mathematical model was established to analyse the hydrodynamic features of a series of divergent chimneys in a SCPP. The importance of estimating the loss from the potential diffuser stall in divergent chimneys was especially discussed in this study. The result of the mathematical model was compared with those of CFD simulation to evaluate the validity and the performance of this present model. Subsequently, parametric studies were conducted by using this mathematical model. The performance of divergent SCPPs was found to be governed by the area ratio of chimney entrance over its exit. The result further indicated that the optimal area ratio of divergent chimneys was different when the chimney height varied from 100m to 300m. Besides, several shorter divergent SCPPs showed a comparable power output as the cylindrical SCPPs with taller chimneys, which demonstrated an outstanding advantage of divergent SCPPs for commercial application.

Experimental Investigation on The Effect of Divergent Tower Solar Chimney on The Theoretical Power Potential

“…Numerical outcomes conclude that divergent shaped chimney is 13 times more efficient than the cylindrical chimney [10]. Moreover, the study validated numerical solution with outcomes obtained from the CFD performed on a divergent shaped chimney with different area ratios and cylindrical chimney, the results suggest a 100-meter divergent chimney can generate 380kW which exceed the power generated by a 200 meter and 300-meter cylindrical chimney [9]. Convergent chimney performance was also studied by several researchers [17,19].…”

“…Aurybi et al, [2] propose a solar chimney integrated with a thermal power plant, it uses the hot waste flue gas as a heat source to operate the solar chimney during night time or at low solar radiation intensity [2]. Hu and Leung [9] and Hu et al, [10] performed numerical solution on cylindrical, divergent and various shape of diffuser chimney. Numerical outcomes conclude that divergent shaped chimney is 13 times more efficient than the cylindrical chimney [10].…”

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

“…Hu et al. 17 explained this effect by solving the momentum equation in divergent chimney. The decline in the power output after the optimum angle can be explained by the boundary layer separation in the turbulent flow inside the chimney.…”

“…This variation was explained by the previous work of Hassan et al 14 Compared against these results, the same evolution of the Manzanares power is achieved. Hu et al 17 explained this effect by solving the momentum equation in divergent chimney. The decline in the power output after the optimum angle can be explained by the boundary layer separation in the turbulent flow inside the chimney.…”

“…The numerical simulations showed a parabolic tendency in the power output of the system with the increase of the conical angle. Hu et al 17 proposed a simple mathematical model of SCPP with divergent chimney to investigate the growth of the power output with the variation of chimney height and the chimney wall angle. However, they not presented the impact of the considered form on the thermodynamic characteristics of the turbulent airflow.…”