Effect of Flow Area to Fluid Power and Turbine Pressure Drop Factor of Solar Chimney Power Plants

In this paper, a theoretical model of solar chimney power plants (SCPPs) is presented based on compressible ideal gas law assumptions. The theoretical optimal turbine pressure drop factors (TPDFs) for constant and nonconstant densities (CD and NCD) are studied, and the effects of flow area parameters examined. Results show that the theoretical optimal TPDF for CD is equal to 2/3 and is independent of the flow area parameters. Results also show that the theoretical optimal TPDF for NCD is close to 1 and is affected by the flow area parameters. However, the theoretical maximum fluid power (MFP) obtained for NCD is never attained in real life. For the actual states, the theoretical optimal TPDF for NCD is still effectively high enough. The TPDF and the fluid power for NCD increase with the reduction of the collector inlet area, and more precisely with the reduction of the chimney inlet area. The TPDF and the fluid power definitely increase with larger chimney flow area. The increase in the fluid power due to shape optimization of the SCPP is limited compared to that due to higher input heat flux of collector. Divergent-top and upward slanting roof shapes are recommended for the solar chimney and the solar collector, respectively, for better SCPP performance. Additionally, locations exposed to strong solar radiation are preferred for SCPPs.