Comprehensive analysis of combined power cycles driven by sCO2-based concentrated solar power: Energy, exergy, and exergoeconomic perspectives

Abstract

Integrating Brayton cycles, utilizing supercritical carbon dioxide (sCO2) as a working medium, with a concentrating solar power (CSP) system is an attractive solution to enable high-temperature clean production of electricity. In this study, different power cycle configurations were coupled with the CSP system to examine and compare their energy, exergy, economic, and exergoeconomic performances to express a comprehensive view. A study of the impact of different parameters was also carried out to inspect the performance of each system under different operating conditions. The governing equations characterizing system performance and economics have been rigorously solved using MATLAB® R2021a, ensuring accuracy and reliability in the present analysis. Energy assessment reveals that, in indirect systems, the thermal efficiency of the recompression Brayton cycle (RBC) surpasses direct cycles by 0.9%, while the organic Rankine cycle (ORC) in dual cycles exhibits a 2% thermal efficiency advantage over triple cycles. For CSP, direct systems enhance efficiency by approximately 1.5%, compared to indirect systems, with dual cycles outperforming single and triple cycles. Exergy analysis indicates a 1.3% exergy efficiency increase for RBC in indirect systems, compared to direct systems, while ORC demonstrates an exceptional 35.66% exergy efficiency improvement in dual systems. Direct CSP systems exhibit higher exergy values than indirect counterparts. Overall exergy efficiency rankings place triple systems at the top (27%), followed by dual (25%) and single cycles (20%) for both direct and indirect systems. Exergoeconomic analysis reveals that the indirect triple cycle (ITC) system bears the greatest expense, totaling 56,968 USD per annum. Compared to the ITC systems, the indirect single- and dual-cycle systems reduce the cost by 8.2% and 1.15%, respectively.