Thermodynamic modeling and comparative analysis of supercritical carbon dioxide Brayton cycle

Abstract

Supercritical CO2 cycles is a promising technology for the next generation power conversion cycles. Supercritical CO2 Brayton cycles offer equivalent or higher cycle efficiency when compared with steam cycles at similar temperatures. This paper presents an investigation of the sCO2 recompression cycle, where recompressing a fraction of the flow without heat rejection, results in an increase in thermal efficiency. A thermodynamic analysis of a 600 MWth power cycle has been carried out, in order to study the effect of the most significant design parameters on the components performance and cycle efficiency, using two different simulation tools to model the recompression system. An iterative model using basic thermodynamic equations describing the system's components was employed in this direction. The system was also modeled by means of commercial process modeling software for comparison. Hence, useful results regarding the operating pressures and temperatures of the cycle and how they affect the recuperators, the compressor and the turbine performance have been derived. Finally, a comparative analysis of the results of the two simulation tools and those of a reference cycle from the bibliography is carried out, showing deviations in the range of 2.8 to 4%. Copyright © 2017 ASME.