Review of SCO₂ Brayton Cycle Active-Cooling Application Technologies for Hypersonic Vehicles

Conventional thermoelectric conversion and onboard power-generation systems struggle to meet the active-cooling requirements of hypersonic vehicles under extreme conditions. The SCO₂ Brayton cycle emerges as a promising solution due to its high density, specific heat capacity, cost-effectiveness, and superior heat-transfer characteristics. This review analyzes the evolution of SCO₂ Brayton cycle configurations, focusing on the following four primary types: recuperated, compression, combined, and other specialized cycles. Their working principles and processes are summarized. Current application progress is detailed across the following four key areas: cycle layout design, printed circuit heat exchangers, SCO₂ heat-transfer behavior, and operational dynamics. Future research directions for SCO₂-based active cooling in hypersonic applications are identified. Emphasis is placed on understanding SCO₂ flow dynamics within cooling channels during transient vehicle operation and investigating component coupling effects in integrated power-generation systems.