Performance comparison of SPT systems integrated with various supercritical CO2-based mixture Brayton cycles based on multi-objective optimization

Abstract

The adoption of other gas with supercritical carbon dioxide (S-CO2) cycle is an effective way to improve the performance of the solar power tower plant (SPT). Among various supercritical CO2-based mixture cycles, it is important to select a suitable layout for the SPT system. In this paper, the ability to generate work and compatibility between the thermal storage system and power cycle are investigated simultaneously. First, the effects of key parameters on the system overall exergy efficiency and specific work are discussed separately. Second, the specific work and temperature difference of the thermal storage system are considered simultaneously with the efficiency based on the multi-objective optimization. Finally, the optimal performance of various cycles are compared. The results show that the supercritical CO2-Xe cycles yield excellent performance and present obvious advantages in generating more specific work and good compatibility that compares to the S-CO2 cycles. While adding butane has reverse effects. The inter-cooling and recompression cycles are advantage in exergy efficiency with maximum 34.1% and 33.9%, respectively. The performance comparison of different cycles based on the multi-objective optimization can be helpful in selecting the suitable cycle layout.