Exergoeconomic analysis of the gas turbine-supercritical CO ₂ -ORC combined cycle

A combined cycle integrating a gas turbine (GT) with supercritical carbon dioxide (sCO 2 ) and organic Rankine cycles (ORC) can recover waste heat from the GT’s flue gas. To evaluate the exergoeconomic performance of this GT/sCO 2 /ORC system, both conventional and advanced exergoeconomic analyses were performed. The results indicate that 27.12% of the combined cycle’s exergy destruction costs(EDC) are avoidable, with endogenous avoidable and exogenous avoidable costs accounting for 13.96% and 13.16%, respectively. Within the individual cycles, the combustion chamber(CC), high-temperature turbine(HT), and ORC turbine exhibit the highest endogenous exergy destruction(ED) costs for the GT, sCO2, and ORC cycles, respectively. A comparative assessment of the two exergoeconomic approaches revealed that the conventional method overestimates the limited optimization potential of the combustion chamber. Prioritizing components based on the advanced exergoeconomic factor suggests the following optimization order for the combined cycle: air compressor(AC), low-temperature turbine(LT), high-temperature turbine, ORC turbine, and then pumps. Therefore, it is recommended that these rotating components be optimized to improve the system.