Exergoeconomic Optimization of an Integrated Supercritical CO₂ Power Plant and Ejector-Based Refrigeration System for Electricity and Cooling Production

This paper presents a cogeneration supercritical CO₂ recompression Brayton cycle (SCRBC) integrated with an ejector refrigeration cycle (ERC). The system uses the waste heat of SCRBC to drive ERC to produce both electricity and cooling effect. The generator of ERC cools the hot CO₂ before entering the compressor and simultaneously heats the ERC refrigerant. Ammonia is selected as a working refrigerant in the ERC. A comprehensive thermodynamic and exergoeconomic study examines a base case of the SCRBC/ERC plant. A sensitivity study is conducted to identify the substantial parameters needed for multi-objective optimization (MOO), which balances cost-saving and energy efficiency. Because the proposed plant produces two useful outputs, electricity and cooling effect, three MOO cases are investigated to enhance the plant performance. Case (1) maximizes the energy utilization factor and minimizes the total product unit cost. Case (2) provides a compromise between the cost of exergy destruction per unit product exergy and the plant investment cost per product exergy unit. Finally, case (3) focuses on finding the best trade-off between the proposed plant's electricity cost and second-law efficiency. The optimization study indicates that case (3) provides the lowest cost of products at the maximum energy and exergy efficiencies. According to it, 13.45 MW for electric power and 4.47 MW for cooling effect are delivered at an evaporator temperature of 5 °C, which is more suitable for cooling applications.