Exergoenvironmental optimization and thermoeconomic assessment of an innovative multistage Brayton cycle with dual expansion and cooling for ultra-high temperature solar power

In the background of energy scarcity and environmental pollution, solar power towers confront challenges of low conversion efficiency, high electricity price, and severe relative environmental impact difference. For that, this study develops an innovative multistage Brayton cycle for ultra-high temperature solar power based on the basic Brayton cycle. Primarily, a series of tasks are performed sequentially, including the development and validation of mathematical models for each subsystem and innovative multistage Brayton cycle, the exploration of conversion potential, the analysis of operational parameters, and the comparison of structural advancement. After optimization, the thermoeconomic and exergoenvironmental performances of each subsystem and component under optimal operational condition are exhaustively discussed. Ultimately, the operational characteristics of the innovative multistage Brayton cycle are comprehensively assessed. The optimized exergy efficiency, electricity price, and exergoenvironmental factor are 25.92 %, 0.1089 $/kWh, and 74.71 %, respectively, representing an improvement of 4.95%-8.56 % in solar-to-electricity efficiency compared to similar research. This system efficiently converts solar energy under designed operational conditions, with excellent thermodynamic performance, economic benefit, and environmental friendliness, and meets the requirements of the carbon neutral policy as well as energy saving and emission reduction.