Heat Recuperation for the Self-Condensing CO2 Transcritical Power Cycle

• Published in: Journal of thermal science Vol. 33; no. 5; pp. 1630 - 1641
• Main Authors: Pan, Lisheng, Shi, Weixiu, Sun, Yin, Sun, Yiwei, Wei, Xiaolin
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2024; Springer Nature B.V
• Subjects: Brayton cycle; Carbon dioxide; Classical and Continuum Physics; Cooling; Efficiency; Engineering Fluid Dynamics; Engineering Thermodynamics; Heat; Heat and Mass Transfer; Layouts; Physics; Physics and Astronomy; Thermodynamic efficiency; heat recuperation process; CO; transcritical power cycle; self-condensing
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-024-1977-1

The supercritical CO 2 Brayton cycle has potential to be used in electricity generation occasions with its advantages of high efficiency and compact structure. Focusing on a so-called self-condensing CO 2 transcritical power cycle, a model was established and four different layouts of heat recuperation process were analyzed, a without-recuperation cycle, a post-recuperation cycle, a pre-recuperation cycle and a re-recuperation cycle. The results showed that the internal normal cycle’s share of the whole cycle increases with increasing the cooling pressure and decreasing the final cooled temperature. Heat load in the supercritical heater decreases with increasing the cooling pressure. From perspective of performance, the re-recuperation cycle and the pre-recuperation cycle have similar thermal efficiency which is much higher than other two layouts. Both thermal efficiency and net power output have a maximum value with the cooling pressure, except in the condition with the final cooled temperature of 31°C. Considering both the complexity and the economy, the pre-recuperation cycle is more applicable than the other options. Under 35°C of the final cooled temperature, the thermal efficiency of the pre-recuperation cycle reaches the peak 0.34 with the cooling pressure of 8.4 MPa and the maximum net power output is 2355.24 kW at 8.2 MPa of the cooling pressure.