Thermodynamic and exergy analysis of 2 MW S-CO2 Brayton cycle under full/partial load operating conditions

Abstract Supercritical carbon dioxide (S-CO2) Brayton cycle with high efficiency and compact structure merits is proposed as an ideal candidate power cycle driven by new energy. Considering the characteristic curves of compressor and heat exchangers, a 2 MW shunt type S-CO2 Brayton cycle based on waste heat recovery is designed to match the thermodynamic parameters of experimental prototype. Then the thermodynamic parameters of the cycle and each component are calculated adopting Ebsilon code. From both the thermal and exergy efficiency viewpoints, the changing laws of thermodynamic parameters and cycle performance with the electricity production are studied under partial load conditions. Results show the highest exergy loss ratio in cycle comes from the furnace, followed by the regenerator and cooler, which are 58.72%, 10.81% and 5.06%, respectively. The exergy efficiency changing law of regenerator with the electricity production greatly affects the exergy loss ratio distribution of all the components. Both the thermal and exergy efficiencies decrease as the electricity production decreases, and the electricity generation efficiency, electricity supply efficiency, and exergy efficiency are 41.57%, 27.20% and 33.59% respectively under full load condition. The present research may lay a foundation for the components’ optimization design, system integration and operation regulation program development during the demonstration unit construction.