Thermodynamic and economic analysis and optimization of supercritical CO₂ partial pre-cooling cycle

In this paper the thermodynamic and economic models for the supercritical CO₂ (SCO₂) partial pre-cooling cycle are established, and the influence of key parameters on the exergy efficiency and system cost of the cycle is analyzed. The non-dominated sorting genetic algorithm II (NSGA-II) is used to optimize the thermodynamic parameters of the SCO₂ cycle with exergy efficiency and net power output as its objective functions, and Pareto optimal curves are obtained. The results show that the SCO₂ partial pre-cooling cycle is highly efficient. Under the given conditions, the cycle exergy efficiency could be increased by decreasing the pinch temperature of condensers, or increasing the efficiency of turbine and compressors. Moreover, the system cost could be reduced by improving the pressure ratio, reducing the heat source temperature or increasing the pinch temperature. And the Pareto curve indicates that the exergy efficiency and system cost cannot reach the optimal state at the same time, so the optimal solution should be selected according to the actual conditions.