Multi-objective performance analysis of different SCO2 Brayton cycles on hypersonic vehicles

Abstract

To provide the continuous and stable power supply of hypersonic vehicles, this study investigates four candidate cycles on the basis of three critical parameters. Specifically, the effects of cycle pressure ratio (PR), recompression split ratio (x), and cycle intermediate pressure ratio (RPR) on the regenerative, recompression, precompression, and partial cooling supercritical carbon dioxide (SCO2) Brayton cycles (BCs) are emphasized. The analysis is carried on by using an established thermodynamic simulation platform. Using PR as the working condition parameter, the influence laws of x and RPR on each cycle at common working conditions are given. The Non-dominated Solution Genetic Algorithm-II (NSGA-II) performs multi-objective optimization for different cycle types. The performance of these cycles is then compared under optimal conditions. The results show that the regenerative SCO2 BC could maintain relatively high output power while keep the structure simple, compared with other three cycles. The optimum power generation in the study range and the common operating conditions of regenerative SCO2 BC is 203.49 kW and 154.03 kW, respectively. Therefore, the regenerative SCO2 BC preferably satisfies the requirements of the hypersonic vehicles.