Performance comparison of different supercritical carbon dioxide Brayton cycles integrated with a solar power tower

Abstract

In this study, a thermodynamic comparison of five supercritical carbon dioxide Brayton cycles integrated with a solar power tower was conducted. The Brayton cycles analyzed were simple Brayton cycle, regenerative Brayton cycle, recompression Brayton cycle, pre-compression Brayton cycle, and split expansion Brayton cycle. A complete mathematical code was developed to carry out the analysis. A heliostat field layout was generated and then optimized on an annual basis using the differential evolution method, which is an evolutionary algorithm. The heliostat field was optimized for optical performance and then integrated with the supercritical CO2 Brayton cycles. Using the results of the optimization, a comparison of net power outputs and thermal efficiencies for these cycles was performed. The findings demonstrated that the highest thermal efficiency was achieved using the recompression Brayton cycle, at June noontime. The maximum integrated system thermal efficiency using this cycle was 40% while the maximum thermal efficiency of this cycle alone was 52%. The regenerative Brayton cycle, although simpler in configuration, shows comparable performance to the recompression Brayton cycle. This analysis was carried out for Dhahran, Saudi Arabia.