Advanced exergy analysis of recompression supercritical CO2 cycle

• Published in: Energy (Oxford) Vol. 178; pp. 631 - 643
• Main Authors: Mohammadi, Z., Fallah, M., Mahmoudi, S.M. Seyed
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-07-2019; Elsevier BV
• Subjects: (Un) avoidable exergy destruction; Advanced exergy analysis; Carbon dioxide; Compressing; Destruction; Endogenous/exogenous; Exergy; Reactor; Reactors; Supercritical; Thermodynamics; Turbines; Advanced exergy analysis; Supercritical; (Un) avoidable exergy destruction; Reactor; Endogenous/exogenous
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2019.04.134

Conventional and advanced exergy analysis of a recompression supercritical CO2 cycle was investigated in this study. The first and second splitting levels of exergy destruction are calculated to determine the real potential of enhancement for the S-CO2 cycle performance. The thermodynamic cycle method of advanced exergy analysis is applied in the present work to reveal the endogenous, exogenous, avoidable, unavoidable, avoidable endogenous, unavoidable endogenous, avoidable exogenous, and unavoidable exogenous exergy destruction for each system component. The overall exergy efficiency for the system are determined as 16.63% and 17.13% under real and unavoidable conditions, respectively. Based on the total avoidable exergy destruction rate, the maximum improvement potential for the system is 106.855 MW (about 50% of the total exergy destruction), and of this avoidable value, 34.59% is endogenous, and 65.41% is exogenous. It is also revealed that, for improving the overall system performance, the priority order of components obtained by the conventional exergy analysis is different from that achieved by the advanced exergy analysis. The former suggests this order as: the reactor, the pre-cooler, the LTR, the HTR and the turbine, while the latter recommends the priority as the HTR, the turbine, and the main compressor. The results also indicate that the reactor has the least potential for improvement despite its highest exergy destruction.
•Advanced exergy analysis is performed for recompression supercritical CO2 cycle.•Detailed results and real potential of the system improvement is presented.•The total exergy destruction of the system can be reduced by up to 49.58%.•Interactions between the components of the supercritical CO2 cycle are significant.•Effective modification priorities of system components are considered.