Establishment and Research of Direct-fired Supercritical Carbon Dioxide Gas Turbine Cycle

The high-quality development of new power systems has necessitated a significant supply of low-carbon and dispatchable power sources. According to the thermodynamic properties of supercritical carbon dioxide, a direct-fired supercritical carbon dioxide gas turbine (SCGT) thermal cycle was developed, enabling zero-carbon power generation and regulation functions. Thermodynamic cycle characteristics, performance optimization strategies and coupled application scenarios with new energy sources were investigated. Results show that SCGT achieves a net power generation efficiency of 55.62% and a specific output power of 794.7 kW/kg. Compared with gas turbine combined cycle equipped with carbon capture and storage (CCS) facility, SCGT shows an improvement of 4.56 percentage points in net power generation efficiency. Compared with Allam cycle, SCGT shows an improvement of 141% in specific output power. The combustor, turbine, and regenerator account for 58.99%, 17.57%, and 7.87% of exergy loss in SCGT respectively, and constitute the primary sources of net power generation efficiency deficit. Increasing gas turbine inlet temperature proves most effective for improving power generation efficiency, and optimizing turbine backpressure enables the optimal power generation efficiency under constant inlet conditions. SCGT coupled with energy storage achieves an energy storage efficiency of around 70% and an energy storage capacity ratio of 28.6%. Owing to its advantages of low fuel cost, high power density and long-duration energy storage capability, SCGT technology is well-aligned with the development requirements of new power systems.