An improved free-superstructure method for optimal synthesis of semi-closed CO2 power cycles

The semi-closed CO2 power cycle is a promising technology for efficient and clean fossil fuel utilization, providing high net efficiency and zero carbon emissions. To identify the optimal configuration for the semi- closed cycle, this study proposes an innovative free-superstructure method that combines evolutionary algorithms for the synergistic optimization of structures and parameters to achieve maximum efficiency. The improved optimization method surpasses conventional approaches based on predefined superstructures by expanding the search space. The results indicate that the net efficiency of the semi-closed CO2 power cycle system (OPT-2 case), optimized using the proposed method, increased from 40.18 % to 45.53 %. Furthermore, the net efficiency is 1.39 percentage points higher compared to the conventional optimization (OPT-1 case), due to the well-matched heat recovery process and reduced turbine exergy destruction. The study would provide an innovative and efficient method for the optimal synthesis of the semi-closed CO2 power cycle.