Design and assessment of a combined solar energy system with storage and power production

The present study aims to develop a novel design of an integrated energy system that synergistically integrates an open-loop Brayton cycle and a closed-loop Rankine cycle with a solar-assisted heat recovery and power production system. Three tailored configurations are simulated to operate in the charging phase during peak solar hours, in low solar radiation periods, and the discharging phase without solar radiation. The combined cycle power system comprises concentrated solar collectors configured to concentrate solar radiation for an effective use, a topping cycle configured to generate electricity by expanding the first working fluid, and a bottoming cycle configured to generate electricity by utilizing the exhaust heat of the topping cycle. The developed configurations aim to simultaneously achieve clean power production and heat storage for later use. The Aspen Plus process simulator is employed to solve the mass and energy balances under steady-state conditions. The open-loop Brayton cycle parameters (such as split ratio and turbine pressure), discharging parameters (temperature), and system performance indicators (energy and exergy efficiencies) are also examined. For the charging configuration, the optimized turbine pressure and split fraction are 6 bar and 0.5, which result in an oil temperature of 400.64 °C. The overall energy and exergy efficiencies of the charging configuration are 98.26% and 48.36 %, respectively. The overall energy and exergy efficiencies of the discharging configuration are 69.34% and 39.54%, respectively.