Effect of intermediate pressure of two-stage compression on the performance of supercritical CO2 Brayton cycle

The simple Brayton cycle consists of a combination of two constant pressure compression processes and two constant entropy processes. There are various ways to improve the cycle efficiency, of which changing the constant entropy compression process to a multi-stage compression is of great significance to improve the cycle efficiency. Using ENGINEERING EQUATION SOLVER software, a computer program was written for a supercritical CO
2
Brayton cycle model with recuperation, reheat and recompression processes. The effect of the intermediate pressure of the two-stage compression process (hereinafter referred to as the intermediate pressure) on the performance of the cycle in terms of compression power consumption, thermal efficiency, and exergy efficiency was investigated and analysed. The results show that the intermediate pressure of the two-stage compression process has a large influence on the cycle efficiency. There is an optimum pressure that minimises the compression power consumption, but at this point the cycle efficiency is not necessarily the highest, while there is an optimum pressure that maximises the cycle efficiency.