Thermo-economic performance comparison of two configurations of combined steam and organic Rankine cycle with steam Rankine cycle driven by Al2O3-therminol VP-1 based PTSC

The main goal of this study is to compare thermo-economic performance of three configurations of power generation system driven by solar heat source in which nanofluid based PTSC is used. Configuration 1 presents simple steam Rankine cycle (SRC) and configuration 2 and 3 show combined SRC with organic Rankine cycle (ORC) in two different conditions. In second configuration, ORC absorbs heat from SRC condenser and in third one, ORC absorbs heat in ORC evaporator from remain heat of SRC evaporator exiting nanofluid. The effects of various parameters such as concentration of nanoparticles, SRC evaporation temperature and SRC condensation temperature are investigated on output parameters and each configuration is optimized by using 4 different organic fluids (R113, n-hexane, cyclohexane, toluene) in ORC. After parametric analysis and performance comparison in base case, components performance and comparison of various configurations are examined at optimal point. Comparison of applying organic fluids in ORC related to configurations 2 and 3 shows that toluene has the best performance. Nanoparticles concentration for all 3 configurations is equal to zero at the selected optimal point and configurations 1 and 2 have relatively similar thereto-economic performance. Configuration 3 has the most net power output (4293 kW); however, it has the weakest thereto-economic performance due to the highest total cost rate (1434 $/h) and less energy and exergy efficiencies.