System Design and Application of Supercritical and Transcritical CO₂ Power Cycles: A Review

Improving energy efficiency and reducing carbon emissions are crucial for the technological advancement of power systems. Various carbon dioxide (CO₂) power cycles have been proposed for various applications. For high-temperature heat sources, the CO₂ power system is more efficient than the ultra-supercritical steam Rankine cycle. As a working fluid, CO₂ exhibits environmentally friendly properties. CO₂ can be used as an alternative to organic working fluids in small- and medium-sized power systems for low-grade heat sources. In this paper, the main configurations and performance characteristics of CO₂ power systems are reviewed. Furthermore, recent system improvements of CO₂ power cycles, including supercritical Brayton cycles and transcritical Rankine cycles, are presented. Applications of combined systems and their economic performance are discussed. Finally, the challenges and potential future developments of CO₂ power cycles are discussed. CO₂ power cycles have their advantages in various applications. As working fluids must exhibit environmentally-friendly properties, CO₂ power cycles provide an alternative for power generation, especially for low-grade heat sources.