Thermodynamic comparison of CO2 power cycles and their compression processes

Abstract

The power system using carbon dioxide (CO2) as the working fluid has been the research hotspot due to its high performance and potential for use in many energy fields. In this paper, the difference of compression processes between supercritical CO2 (S–CO2) and transcritical CO2 (T-CO2) power cycles is researched, and their effects on the thermodynamic performances of power cycles and equipment are discussed. The results show that the thermal efficiency and net output power increase with the decreasing of the compressor/pump inlet temperature, and there is a big jump near the critical temperature. The condensation margin is more sensitive to the temperature than the pressure near the critical point. To minimize the compressor input power and to guarantee the reliability of equipment, the inlet parameters of compressors should be designed and operated carefully. And the inlet velocity of compressors should be set below the usually recommend value.

Keywords

• Supercritical CO2 power cycle
• Transcritical CO2 power cycle
• Compression process
• Compressor
• Pump