Thermodynamic analysis and comparison for different direct-heated supercritical CO2 Brayton cycles integrated into a solar thermal power tower system. (1st December 2017)

• Record Type: Journal Article
• Authors: Zhu, Han-Hui; Wang, Kun; He, Ya-Ling
• Is Part Of: Energy. Volume 140:Part 1(2017)
• Page Start: 144
• Page End: 157
• Publication Date: 2017-12-01
• Subjects: Direct-heated S-CO2 Brayton cycles -- Solar power tower -- Complete mathematical model -- Thermodynamic analysis -- Performance comparison; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2017.08.067
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: In this paper, a complete mathematical model is developed to carry out the thermodynamic analysis and comparison for different direct-heated S-CO2 Brayton cycles (simple, pre-compression, recompression, partial-cooling, and intercooling) integrated into a solar power tower (SPT) system. Based on the model, the effect of turbine inlet temperature (TIT) on the thermodynamic performances of the receiver, the thermal energy storage unit, the S-CO2 power cycle blocks and the integrated SPT systems is investigated respectively for these cycles. Additionally, a comparison of cycle efficiencies and overall integrated SPT system efficiencies is performed for five S-CO2 cycles at a series of total recuperator conductance ( UA total ) values. The results reveal that the TIT exhibits a parabolic effect on the overall efficiencies for each S-CO2 cycle, and the intercooling S-CO2 cycle achieves the highest overall efficiencies followed by the recompression, the partial-cooling, the pre-compression, and the simple cycles at different TIT values. Furthermore, the partial-cooling cycle possesses the highest overall specific work at each TIT and offers higher overall efficiencies than the recompression cycle at a constant TIT (650 °C) as the UA total is rather low, having the potential to reduce the costs of integrated SPT systems with limited UA total values. Highlights: The integration of five different direct-heated S-CO2 Brayton cycles into a solar power tower system is studied. A complete mathematical model is developed for the direct integrated SPT systems. A comprehensive thermodynamic analysis and comparison are carried out among five S-CO2 Brayton cycles. The effect of UA total on the cycle efficiencies and overall system efficiencies is investigated.