Performance investigation of the solar power tower driven combined cascade supercritical CO2 cycle and organic Rankine cycle using HFO fluids

Current study examined the effect of solar power tower (SPT) design parameters (solar emittance, concentration ratio and heat transfer fluid velocity, solar irradiation) on SPT-integrated combined cascade sCO(2) (CSCO2) cycle and organic Rankine cycle (ORC) using ultra-low global warming potential (GWP) hydro fluoro olefins (HFO) fluids. Exergy efficiency, thermal efficiency and net output power were considered as performance parameters. A computational technique was used for the analysis. It was investigated that thermal and exergy efficiencies of the standalone (SPT+ CSCO2) cycle improved by 2.36% and 2.41%, respectively, by the incorporation of the ORC as bottoming cycle. Highest exergy efficiency, thermal efficiency and net output power were increased with solar irradiation, concentration ratio, heat transfer fluid velocity while decreased with solar emittance. Highest performance were found with R1224yd(E) while lowest with R1234yf among other considered low GWP fluids at current input conditions.